Medicine, Faculty of
Pathology and Laboratory Medicine, Department of
DSpace
Biomolecules 13 (2): 388 (2023)
International Collaboration on Repair Discoveries
Vancouver Coastal Health Authority. Research Institute
Gleave, Anna
Granville, David James
Autoimmune diseases often present with cutaneous symptoms that contribute to dysfunction, disfigurement, and in many cases, reduced quality-of-life. Unfortunately, treatment options for many autoimmune skin diseases are limited. Local and systemic corticosteroids remain the current standard-of-care but are associated with significant adverse effects. Hence, there is an unmet need for novel therapies that block molecular drivers of disease in a local and/or targeted manner. Granzyme B (GzmB) is a serine protease with known cytotoxic activity and emerging extracellular functions, including the cleavage of cell–cell junctions, basement membranes, cell receptors, and other structural proteins. While minimal to absent in healthy skin, GzmB is markedly elevated in alopecia areata, interface dermatitis, pemphigoid disease, psoriasis, systemic sclerosis, and vitiligo. This review will discuss the role of GzmB in immunity, blistering, apoptosis, and barrier dysfunction in the context of autoimmune skin disease. GzmB plays a causal role in the development of pemphigoid disease and carries diagnostic and prognostic significance in cutaneous lupus erythematosus, vitiligo, and alopecia areata. Taken together, these data support GzmB as a promising therapeutic target for autoimmune skin diseases impacted by impaired barrier function, inflammation, and/or blistering.
Citation: Gleave, A.; Granville, D.J.Granzyme B in Autoimmune SkinDisease. Biomolecules 2023, 13, 388.https://doi.org/10.3390/biom13020388Academic Editors: Ralf J. Ludwig,Takashi Hashimoto andRobert GniadeckiReceived: 6 January 2023Revised: 15 February 2023Accepted: 16 February 2023Published: 18 February 2023Copyright: © 2023 by the authors.Licensee MDPI, Basel, Switzerland.This article is an open access articledistributed under the terms andconditions of the Creative CommonsAttribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).biomoleculesReviewGranzyme B in Autoimmune Skin DiseaseAnna Gleave 1 and David J. Granville 1,2,*1 British Columbia Professional Firefighters’ Burn and Wound Healing Laboratory, International CollaborationOn Repair Discoveries (ICORD) Centre, Vancouver Coastal Health Research Institute, University of BritishColumbia, Vancouver, BC V5Z 1M9, Canada2 Department of Pathology and Laboratory Medicine, University of British Columbia,Vancouver, BC V6T 1Z7, Canada* Correspondence: dgranville@icord.orgAbstract: Autoimmune diseases often present with cutaneous symptoms that contribute to dysfunc-tion, disfigurement, and in many cases, reduced quality-of-life. Unfortunately, treatment options formany autoimmune skin diseases are limited. Local and systemic corticosteroids remain the currentstandard-of-care but are associated with significant adverse effects. Hence, there is an unmet need fornovel therapies that block molecular drivers of disease in a local and/or targeted manner. GranzymeB (GzmB) is a serine protease with known cytotoxic activity and emerging extracellular functions,including the cleavage of cell–cell junctions, basement membranes, cell receptors, and other structuralproteins. While minimal to absent in healthy skin, GzmB is markedly elevated in alopecia areata,interface dermatitis, pemphigoid disease, psoriasis, systemic sclerosis, and vitiligo. This review willdiscuss the role of GzmB in immunity, blistering, apoptosis, and barrier dysfunction in the contextof autoimmune skin disease. GzmB plays a causal role in the development of pemphigoid diseaseand carries diagnostic and prognostic significance in cutaneous lupus erythematosus, vitiligo, andalopecia areata. Taken together, these data support GzmB as a promising therapeutic target forautoimmune skin diseases impacted by impaired barrier function, inflammation, and/or blistering.Keywords: Granzyme B; serine protease; autoimmune skin disease; inflammation; extracellularmatrix; small molecule inhibitor1. BackgroundAutoimmune diseases are a major cause of global morbidity and mortality [1–3]. Overthe past three decades, the incidence and prevalence of autoimmune diseases have beenincreasing at an accelerated rate [3,4]. Because the onset of autoimmune diseases oftenoccurs early in life and most are chronic in nature, the resulting disruption of workingand reproductive capabilities incurs significant societal costs [5,6]. This has precipitatedefforts to better characterize autoimmune disease pathophysiology, which despite recentadvancements, remains poorly defined. Autoimmune diseases are thought to occur inindividuals with a genetic predisposition to immune dysregulation following exposureto an environmental trigger [5]. Immune responses can be categorized into two distinctbut frequently intertwined mechanisms [7]. The Th1 or “cytotoxic” response involvesCD8+ T cells targeting intracellular antigens, causing apoptosis. Conversely, the Th2 or“humoral” response involves B cell proliferation and antibody generation in response to anextracellular antigen. In autoimmune diseases, these immune responses are erroneouslydirected against self-antigens, triggering a cascade of inflammatory cytokine release (IL-1β,IL-2, IL-12, TNF-α, and IFN-γ in the Th1 response; IL-4, IL-5, IL-10, and IL-13 in the Th2response), immune cell recruitment, and inflammation with potentially permanent targettissue damage [7,8].The skin is the largest organ in the human body and is impacted by many autoimmunediseases [9]. Several conditions, such as vitiligo, alopecia areata, and pemphigoid disease,Biomolecules 2023, 13, 388. https://doi.org/10.3390/biom13020388 https://www.mdpi.com/journal/biomoleculesBiomolecules 2023, 13, 388 2 of 14primarily affect the integumentary system. Additionally, systemic autoimmune diseasesoften have characteristic skin findings. An estimated 80% of systemic lupus erythematosus(SLE) patients have cutaneous symptoms, ranging from the classic malar rash to permanentdiscoid scarring [10]. In systemic sclerosis, 50% of patients develop digital ulcers thatpredispose them to osteomyelitis, gangrene, and amputation [11]. Skin lesions can alsoprecede other symptoms, creating opportunities for early diagnosis and intervention. Forinstance, 75% of patients with dermatitis herpetiformis have concurrent glucose-associatedenteropathies, despite only 20% presenting with gastrointestinal symptoms [12]. Unfor-tunately, therapies for autoimmune dermatological diseases remain limited. Local andsystemic corticosteroids are the current standard of care, but they can cause unpleasant andeven life-threatening side effects [13–15]. Hence, there is an unmet need for novel therapiesthat block pathological disease drivers in a local and/or targeted manner.Granzyme B (GzmB) is a serine protease produced by natural killer (NK) and CD8+T cells and stored within cytotoxic intracellular granules [16–18]. GzmB has well-definedintracellular activity; following granule secretion, GzmB is internalized into target cells withthe help of the pore-forming protein, perforin, where it initiates apoptosis through caspase-dependent and -independent mechanisms [18–20]. Interestingly, during this process, GzmBmay also leak into the extracellular space [21]. More recently, extracellular functions forGranzyme B have been recognized that expand its role beyond cytotoxicity [17,22,23]. Forinstance, GzmB is produced by multiple immune and non-immune cell types that do notexpress perforin, including mast cells [24], basophils [25], neutrophils [26], B cells [27], plas-macytoid dendritic cells [28], macrophages [29], CD4+ T cells [30], regulatory T cells [31],and keratinocytes [32]. GzmB released from the aforementioned cell types accumulatesin the extracellular space, where it retains proteolytic activity, and depending on locationand available substrates, cleaves extracellular matrix proteins, attachment/barrier proteins,complement factors, coagulation factors, and augments cytokine/growth factor activity,among other actions [21,33,34].In humans, GzmB is encoded by the GZMB gene, which is 3500 base pairs long,comprises 5 exons and 4 introns, and is located on chromosome 14 [35]. Transcriptionalactivation of the GZMB gene is mediated by a combination of T cell activation and cytokineco-stimulation [36]. Once transcribed, the 32 KDa, 247 amino acid polypeptide is targetedto the endoplasmic reticulum and cleaved into an inactive pro-enzyme [23]. GzmB is thentagged with mannose-6-phosphate in the Golgi, which promotes internalization [23]. Thetertiary structure of GzmB involves eight loops grouped into two domains with the activesite situated in between [37]. The active site contains an Arg residue, which interacts strictlywith substrates containing Asp, or less preferentially Glu, in the P1 position [37,38]. Finally,GzmB is activated through the cleavage of the N-terminal dipeptide by cathepsin C [23].While proteolytic activity is suppressed within the acidic granules, subsequent release intoa pH-neutral environment enables optimal function [38]. The only known endogenousintracellular GzmB inhibitor is proteinase inhibitor-9 (SerpinB9), which is produced byimmune cells and serves as protection in the event of accidental GzmB release [39]. Todate, however, no extracellular endogenous GzmB inhibitors have been identified. Severalexogenous GzmB inhibitors have also been developed, including Compound 20 [40,41],Z-IETD-fluoromethylketone [42,43], and VTI-1002 [33,44,45] among others. Only VTI-1002has been studied in preclinical models of autoimmune skin disease, showing no adverseeffects for up to 30 days of daily administration, but has not yet been examined in clinicaltrials [34].While virtually absent in healthy skin, several autoimmune skin diseases exhibit el-evated GzmB levels. This suggests a lack of physiologic function for GzmB, renderingit an attractive therapeutic target for minimizing adverse effects [46–49]. In this review,we summarize our current understanding of GzmB and its contributions to autoimmuneskin disease pathophysiology, including skin inflammation, cell apoptosis, and structuralprotein disruption. We discuss a broad range of autoimmune skin diseases, such as alopeciaareata, interface dermatitis, pemphigoid disease, psoriasis, systemic sclerosis, and vitiligo,Biomolecules 2023, 13, 388 3 of 14among others (Figure 1). A causal relationship has been established between GzmB levelsand the onset of pemphigoid disease, with GzmB inhibition with VTI-1002 effectivelyreverting symptoms [34,40]. GzmB may also carry diagnostic and prognostic significance incutaneous lupus erythematosus [50–52], vitiligo [53,54], and alopecia areata/scarring alope-cia [55–57]. Collectively, the current evidence nominates GzmB as a promising biomarkerand therapeutic target in autoimmune skin disease.Biomolecules 2023, 13, x FOR PEER REVIEW 3 of 14 disease pathophysiology, including skin inflammation, cell apoptosis, and structural pro-tein disruption. We discuss a broad range of autoimmune skin diseases, such as alopecia areata, interface dermatitis, pemphigoid disease, psoriasis, systemic sclerosis, and vitiligo, among others (Figure 1). A causal relationship has been established between GzmB levels and the onset of pemphigoid disease, with GzmB inhibition with VTI-1002 effectively re-verting symptoms [34,40]. GzmB may also carry diagnostic and prognostic significance in cutaneous lupus erythematosus [50–52], vitiligo [53,54], and alopecia areata/scarring alo-pecia [55–57]. Collectively, the current evidence nominates GzmB as a promising bi-omarker and therapeutic target in autoimmune skin disease. Figure 1. Current understanding of GzmB in cutaneous autoimmune diseases, including psoriasis, vitiligo, systemic sclerosis, alopecia areata, interface dermatitis, and bullous pemphigoid. Not to scale. Created with BioRender.com, accessed on 4 January 2023. 2. Alopecia Areata Alopecia areata (AA) is characterized by transient, non-scarring hair loss secondary to immune privilege collapse within the hair follicle [58]. The extent of hair loss ranges from well-circumscribed patches to complete loss from all hair-bearing sites [58]. AA im-munopathogenesis is not currently well understood but is thought to involve hair follicle autoantigen recognition, which triggers CD8+ T cell recruitment, J AK-STAT pathway activation, and perforin and GzmB release (Figure 2a) [59–62]. Other pathways, including endogenous retinoids [63–65] and substance P [65,66], are functionally linked to AA and may increase GzmB levels. GzmB has been proposed as a downstream mediator in the JAK/STAT pathway in AA, as the Jak3 inhibitor tofacitinib was observed to downregulate GzmB in AA-affected skin cells in a mouse model [59]. Moreover, GzmB-expressing CD8+ T cells exist in close contact with affected hair follicles [67]. GzmB has even been detected within the hair follicle isthmus, the primary site of immune collapse [63]. A temporal association between hair loss and GzmB expression has Figure 1. Current understanding of GzmB in cutaneous autoimmune diseases, including psoriasis,vitiligo, systemic sclerosis, alopecia areata, interface dermatitis, and bullous pemphigoid. Not toscale. Created with BioRender.com, accessed on 4 January 2023.2. Alopecia AreataAlopecia areata (AA) is characterized by transient, non-scarring hair loss secondaryto immune privilege collapse within the hair follicle [58]. The extent of hair loss rangesfrom well-circumscribed patches to complete loss from all hair-bearing sites [58]. AAimmunopathogenesis is not currently well understood but is thought to involve hair follicleautoantigen recognition, which triggers CD8+ T cell recruitment, JAK-STAT pathway activation, and perforin and GzmB release (Figure 2a) [59–62].Other pathways, including endogenous retinoids [63–65] and substance P [65,66], arefunctionally linked to AA and may increase GzmB levels. GzmB has been proposed as adownstream mediator in the JAK/STAT pathway in AA, as the Jak3 inhibitor tofacitinibwas ob erved to downregulate GzmB in AA-affected skin cells in a mouse model [59].Moreov r, GzmB-expressing CD8+ T cells exist in close contact with affected hair fol i-cles . even be n detected within the hair follic e isthmus, the primary site ofimmune collapse [63]. A temporal association betw en hair loss and GzmB expression hasalso been established using in vivo models. McPhee et al. [68] transplanted skin grafts fromthe C3H/HeJ mouse model into normal mice, which stimulated hair loss and increasedGzmB expression. Similarly, Hashimoto et al. [69] injected cryopreserved lymphocytesBiomolecules 2023, 13, 388 4 of 14from C3H/HeJ mice into control mice, which caused 90% of recipient mice to develop hairloss and marked upregulation of GzmB mRNA. While these data implicate GzmB in AApathogenesis, a causal relationship has not been established.Biomolecules 2023, 13, x FOR PEER REVIEW 4 of 14 also been established using in vivo models. McPhee et al. [68] transplanted skin grafts from the C3H/HeJ mouse model into normal mice, which stimulated hair loss and in-creased GzmB expression. Similarly, Hashimoto et al. [69] injected cryopreserved lym-phocytes from C3H/HeJ mice into control mice, which caused 90% of recipient mice to develop hair loss and marked upregulation of GzmB mRNA. While these data implicate GzmB in AA pathogenesis, a causal relationship has not been established. Figure 2. Flow chart depicting proposed GzmB involvement in the immunopathogenesis of cutane-ous autoimmune diseases, including (a) alopecia and scarring alopecia; (b) interface dermatitides such as (bi) lichen planus and (bii) cutaneous lupus erythematosus; (c) pemphigoid disease; (d) psoriasis; and (e) vitiligo. Of note, the contribution of extracellular GzmB to disease onset and se-verity requires further elucidation and is likely underrepresented in this figure. Characterization of the extracellular functions of GzmB is an area of ongoing investigation. Systemic sclerosis is not included due to the absence of relevant data. Created with BioRender.com, accessed on 17 February 2023. GzmB expression in AA may also predict disease severity and treatment response. Koguchi-Yoshioka et al. [55] compared lymphocyte phenotypes in AA lesions from re-sponders and non-responders to squaric acid dibutyl ester, a topical immunotherapy for refractory AA. Skin lesions from responders, non-responders, and controls all had similar numbers of GzmB-expressing lymphocytes. However, individual lymphocytes from non-responders produced significantly more GzmB than responders and controls. This was observed in skin lesions but not in the serum, suggesting that topical GzmB inhibition may effectively treat AA while avoiding systemic side effects. AA is one of the most prev-alent autoimmune conditions [70]; despite this, little consensus exists regarding treatment due to arbitrary reference cut-offs and variable results from randomized trials [71,72]. The finding that GzmB acts locally as a downstream mediator of inflammation highlights its potential as a therapeutic target in AA. Figure 2. Flow chart depicting proposed GzmB involvement in the immunopathogenesis of cutaneousautoimmune diseases, including (a) alopecia and scarring alopecia; (b) interface dermatitides such as(bi) lichen planus and (bii) cutaneous lupus erythematosus; (c) pemphigoid disease; (d) psoriasis;and (e) vitiligo. Of note, the contribution of extracellular GzmB to disease onset and severity requiresfurther elucidation and is likely underrepresented in this fi ure. Characterization of the xtracellularfunctions of GzmB is an area of ongoing investigation. Systemic sclerosis is not included due to theabsence of relevant data. Created with BioRender.com, accessed on 17 February 2023.i i l i t i s erit tr at ent res onse.i- t l. c te e otypes in lesions fro re-t i i i t l t rl i f i- i l t . o ever, i i i al ly phocytes fro non-ifi tli skin lesions but not in the s rum, suggesting tha topical GzmB inhibition mayeffectiv ly treat AA while avoiding systemic side eff cts. AA is one f the most preval ntutoimmune co diti s [70]; despite this, little cons nsus xist regardin treatment du toarbitrary referenc cut-offs and variable results from randomize trials [71,72]. The findingthat GzmB acts locally as a downstream mediator of inflammation highlights its potentialas a therapeutic target in AA.Unlike AA, in which hair follicle integrity is preserved, scarring or cicatricial alopeciainvolves permanent follicular destruction and hair loss [73]. The resultant scarring isirreversible and causes profound injury to patient quality-of-life [74]. As such, efforts toelucidate the mechanisms that drive scarring are ongoing. In one study, Ghoreishi et al. [56]Biomolecules 2023, 13, 388 5 of 14noted an increased number of GzmB-positive CD8+ and NK cells in cicatricial alopeciacompared to AA, indicating a greater extent of T cell activation. Similar findings wereobserved in frontal fibrosing alopecia, a subtype of scarring alopecia with progressivefrontotemporal and eyebrow hair loss [57]. GzmB is also known to cleave decorin, ananti-fibrotic proteoglycan that sequesters active transforming growth factor beta (TGF-β) [75]. Keloid and hypertrophic scars contain reduced decorin, suggesting that GzmB maymediate scarring through decorin cleavage and subsequent TGF-β release [76–78]. GzmBinhibitors serpina3n and VTI-1002 prevent degradation of extracellular decorin in vivoand, therefore, represent attractive anti-fibrotic therapies [44,79]. However, the role of thedecorin-TGF axis in cicatricial alopecia remains uncertain. Some have observed elevatedTGF-β in cicatricial alopecia [80] while others report unchanged [81] and even reduced [82]TGF-β levels. The impact of GzmB on the decorin-TGF axis in scarring alopecia should befurther explored.3. Interface DermatitisInterface dermatitis comprises a diverse group of skin disorders characterized bykeratinocyte apoptosis and pathologic inflammation within the dermal-epidermal junction(DEJ) [83]. A classic feature of interface dermatitis is the formation of colloid bodies, whichreflect intraepidermal apoptosis [84]. Lichen planus is the prototypical example of interfacedermatitis, although the term also includes systemic illnesses, such as systemic lupuserythematosus (SLE) and dermatomyositis. These conditions are thought to possess ashared inflammatory signaling pathway involving the recognition of self-antigens on ker-atinocytes, followed by CD8+ and NK cell recruitment to the DEJ, and finally keratinocyteapoptosis within the stratum basale [85]. The triggering self-antigens vary by condition;for example, Ro/SSA antigen may act as a specific target in SLE while allogenic MHCmay play a role in graft-versus-host disease [86]. GzmB release from CD8+ and NK cells isa common inducer of keratinocyte cell death across the interface dermatitides, althoughTNF-alpha and Fas/Fas Ligand systems may also play a role [48].Lichen planus (LP) is a chronic autoimmune condition with cutaneous and oral man-ifestations that classically presents with violaceous plaques and a white lacelike patterntermed Wickham’s striae [87]. The triggering event is thought to involve IFN-1 release fromplasmacytoid dendritic cells, which promotes inflammatory cell recruitment to the DEJ(Figure 2bi) [88]. The inflammatory infiltrate contains CD8+ T cells that stain strongly forGzmB and perforin, which is not observed in healthy skin [47,48,88,89]. Ammar et al. [90]demonstrated that GzmB levels are 200 times higher in LP than in healthy skin, withhigher expression observed in oral compared to cutaneous LP [48]. The number of GzmB-expressing cells is highest early in the disease and eventually plateaus, suggesting thatGzmB plays a role in early LP pathogenesis. Notably, a correlation has been establishedbetween the number of lymphocytes expressing GzmB and the extent of keratinocytedeath [91]. This is supported by Lage et al. [48], who observed GzmB-containing T lympho-cytes in close proximity to apoptotic keratinocytes. Similarly, Shimizu et al. [89] reportedGzmB release from T cells into the intracellular space directly adjacent to apoptotic ker-atinocytes. While association has been established, the impact of GzmB inhibition ondisease onset and severity has yet to be studied in LP.Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that can affectnearly every organ system. Approximately 80% of SLE patients have cutaneous symptomsknown as cutaneous lupus erythematosus (CLE) [10]. Symptoms can be highly heteroge-nous, ranging from systemic involvement to the classic malar rash and photosensitivityin acute presentations, and chronic disfiguring scarring in discoid lupus erythematosus(DLE) [92]. Immunopathogenesis is thought to occur in genetically susceptible individualsfollowing an environmental trigger, such as ultraviolet damage. This triggers an IFNsignaling loop, cytokine release, and immune cell infiltrate, including CD8+ T cells andautoantibody-producing plasma cells (Figure 2bii) [93,94]. Current treatment options in-clude hydroxychloroquine and methotrexate, which are effective but have well-documentedBiomolecules 2023, 13, 388 6 of 14adverse effects [14]. GzmB has been implicated in the pathogenesis of CLE, with one studydetecting GzmB in histological skin specimens in 77% of affected patients [84]. Moreover,CD8+ lymphocytes in CLE produce GzmB-specific autoantigens, a finding that is abolishedby the addition of a GzmB inhibitor [50,95]. Biopsies of DLE stain strongly for GzmBrelative to nonscarring CLE and controls, with expression levels correlating to clinico-pathological severity [96,97]. Others have arrived at similar conclusions, linking GzmBexpression to both disease severity, duration and/or chronicity [50,51]. Another study on alarge cohort of SLE patients found higher levels of serum GzmB in patients with cutaneoussymptoms [52]. Some have even linked the presence of GzmB in skin biopsies and serumwith poor renal function, including elevated creatinine and proteinuria [51,96]. Thesestudies suggest that GzmB is a key driver in the pathogenesis of SLE and may correlatewith disease severity.Dermatomyositis (DM) is a chronic autoimmune myopathy with distinct cutaneousmanifestations, including heliotrope rash and Gottron’s papules [98]. Conflicting evidenceexists regarding the role of GzmB in DM. For instance, Grassi et al. [84] compared GzmBstaining in histological skin specimens of DM and SLE. They observed strong staining inonly 2 of 20 DM specimens, whereas 17 of 22 SLE specimens stained strongly for GzmB. TheFas/Fas Ligand pathway has been alternatively proposed to drive keratinocyte apoptosisin DM based on the finding of strong Fas staining within the epidermis of Gottron’spapules [99]. Conversely, other studies have implicated GzmB in DM. Goebels et al. [100]noted increased GzmB staining in DM while Mammen [101] identified a protein called Jo-1,which correlates with DM disease severity and is cleaved by GzmB in the lungs. Not unlikeother autoimmune conditions, the roles of GzmB in DM, and particularly its extracellularroles, remain unclear and should be further elucidated.4. Pemphigoid DiseasesPemphigoid diseases encompass bullous pemphigoid, epidermolysis bullosa acquisita,and dermatitis herpetiformis. These conditions are characterized by tense, pruritic subepi-dermal bullae secondary to autoantibody targeting of extracellular structural proteinswithin the DEJ basement membrane (Figure 2c) [102]. Subsequent separation between thedermis and epidermis causes blistering, erythema, and erosion. Bullous pemphigoid (BP),the most common autoimmune blistering disease, is becoming more prevalent owing to anaging population and more frequent use of triggering medications [103]. Potent steroidsare effective in treating BP, but their use, especially long-term, is limited by significantside effects [104]. Adverse effects include skin atrophy and impaired wound healing lo-cally and systemic side effects, such as decreased bone density and Cushing’s syndrome,which can be especially problematic in the medically vulnerable elderly population [105].Therefore, the development of novel targeted therapies for pemphigoid diseases is anunmet clinical need. Prior research on GzmB in pemphigoid disease is scant owing to theformer belief that GzmB functioned as an exclusively intracellular protease. In light ofnew research revealing an extracellular function for GzmB, one involving extracellularmatrix and hemidesmosomal protein cleavage, the role of GzmB in pemphigoid diseasehas received increased attention [34,40,106].GzmB has been shown to be elevated in the immune cells and extracellular milieu inpemphigoid diseases. Furthermore, GzmB proteolysis likely plays a key role in cleavingstructural proteins that are critical for maintaining DEJ integrity. For example, hemidesmo-somal proteins Collagen XVII, Collagen VII, and α6/β4 integrin are known autoantibodytargets in pemphigoid diseases and substrates of GzmB [34,40,107]. Based on these find-ings, a causal relationship between GzmB and pemphigoid disease has been investigated.Russo et al. [40] performed an immunohistochemical analysis of BP, epidermolysis bul-losa acquisita, and dermatitis herpetiformis specimens, and they observed GzmB-specificcleavage of Collagen XVII, Collagen VII, and α6/β4 integrin. Blister formation in diseasedspecimens was indicated histologically by the presence of clefts separating the dermisand epidermis. This was accompanied by GzmB accumulation at the DEJ, along with aBiomolecules 2023, 13, 388 7 of 14paucity of Collagen XVII, Collagen VII, and α6/β4 integrin. Importantly, the incubationof GzmB with healthy skin samples produced a similar cleft-forming phenotype, whichwas abolished following GzmB inhibition with Compound 20. To explore a causal, mecha-nistic role in vivo, Hiroyasu et al. [34] utilized a murine model of BP, as well as local andsystemic antibody-transfer murine models of epidermolysis bullosa acquisita, to assessthe role of GzmB via either GzmB knockout or topical pharmacological inhibition withVTI-1002. GzmB was produced by mast cells and basophils, which do not produce perforin,further suggesting an extracellular function [34]. GzmB inhibition led to a 45% reduction inlesional area; prevented cleavage of Collagen XVII, Collagen VII, and α6/β4 integrin; andmarkedly reduced skin frailty compared to the controls. Moreover, an analysis of GzmBlevels in human BP patients via ELISA revealed that GzmB was significantly elevated inBP blister fluids but negligible in BP and control sera [34]. These findings imply a causalrole for extracellular (not intracellular/perforin-dependent) GzmB in pemphigoid diseasepathogenesis. Further exploration of therapeutic approaches that target extracellular GzmBfor pemphigoid diseases is of significant interest.5. PsoriasisPsoriasis is a chronic, complex, and relapsing skin condition affecting 3% of thepopulation [108]. The most prevalent subtype, psoriasis vulgaris, is characterized byimmune cell infiltration and hyperproliferation of abnormal keratinocytes within theepidermis [109]. Clinical features include the formation of erythematous, pruritic, andscaly plaques affecting the trunk, scalp, and extensor body surfaces [109]. The TNF-αand IL-23/TH17 pathways are critical drivers of psoriasis development and chronicity(Figure 2d) [110]. These pathways are targeted by several biologic therapies that providehighly effective disease management [110]. At present, the role of GzmB in psoriasispathophysiology is poorly understood. While GzmB is elevated in psoriasis compared tohealthy controls, no correlation has been established between GzmB expression and clinicalseverity [111,112]. An alternate role for GzmB has been proposed by Fenix et al. [113],who used mouse models to study CD49a+ resident memory T (Trm) cells associated withsite-specific disease memory in psoriasis. Comparison across acute, chronic, and resolvedlesions showed significantly increased GzmB production by Trm cells in resolved psoriasis.This led the authors to speculate that GzmB contributes to relapsing rather than acutedisease. Because biologics can be prohibitively expensive, drug tapers are often attempteddespite poorly defined tapering regimens, resulting in disease re-occurrence [114,115].The exploration of GzmB inhibition as a means for maintaining psoriatic remission maytherefore be warranted.6. Systemic SclerosisSystemic sclerosis, also known as scleroderma, is a fibrogenic rheumatic condition thatcauses progressive sclerosis of the skin and internal organs, as well as vasculopathy [116].Albeit uncommon, systemic sclerosis bears the highest mortality rate of any rheumaticdisease [116]. Given its infrequency, high mortality, and breadth of organ systems affected,establishing determinants of distinct clinical subsets would be beneficial for guiding riskstratification and therapy. Evidence suggests that GzmB is elevated in systemic sclerosisand may be associated with certain disease complications [117]. For example, Ulanetet al. [118] demonstrated that B23, a nucleolar phosphoprotein associated with pulmonaryhypertension in scleroderma, was cleaved efficiently by GzmB in vascular smooth musclecells. Interestingly, other cell lines were highly resistant to B23 cleavage by GzmB. Theauthors, therefore, proposed that autoantigens generated by cleavage from tissue-specificproteases, including GzmB, induce different disease subtypes and represent targets forindividualized therapies.GzmB has also been investigated in other scleroderma-associated vasculopathies. It iswell known that plasminogen cleavage paradoxically produces both proangiogenic plasminand antiangiogenic angiostatin. Mulligan-Kehoe et al. [119] analyzed the serum of sclero-Biomolecules 2023, 13, 388 8 of 14derma patients and noted elevated angiostatin along with reduced plasmin concentrations.Furthermore, GzmB incubation with plasminogen and plasmin produced angiostatin frag-ments. This led the authors to speculate that GzmB may account for some of the vasculardefects observed in scleroderma via the generation of antiangiogenic factors like angiostatin.Another study considered ischemic digital loss, a complication of vasculopathy seen insystemic sclerosis. Schachna et al. [120] performed immunoblots with cell lysates fromscleroderma patients with and without digital loss; staining for GzmB autoantigens waspositive in 84% of patients with digital loss, compared to 40% without digital loss. Hence,the presence of specific autoantigens cleaved by GzmB carries clinical relevance, as it maypredict the development of complications like ischemic digital loss. In fact, it has beenproposed that GzmB-mediated autoantigen cleavage occurs in the majority of autoimmunediseases, with generated peptide fragments contributing to a feed-forward loop that drivesdisease self-sustenance [121]. Further investigation into autoantigen fragments that mayserve as biomarkers for other clinical subtypes would be a topic of future interest.7. VitiligoVitiligo is a chronic depigmenting disorder resulting from an autoimmune attackagainst melanocytes, the cell type responsible for producing melanin. It affects 0.2% of thepopulation and is characterized by the presence of well-defined nonpigmented maculesand patches [122,123]. Autoimmunity is driven by the recognition of melanocyte-specificautoantigens, CD8+ T cell recruitment, and activation of the IFN-γ-CXCL10 cytokinesignaling pathway (Figure 2e) [124]. While phototherapy and corticosteroids are effectiveshort-term therapies for vitiligo, they are time-consuming, require long-term follow-up, andmay not provide longstanding symptomatic control [13]. To address these challenges, theidentification of biomarkers for disease prognostication and therapeutic targeting would beinvaluable. Several single nucleotide polymorphisms in GZMB, the gene encoding GzmB,have been associated with vitiligo [125–127]. In fact, one study, including over 3000 patientsof Chinese Han ancestry, associated the SNP rs8192917 C allele with a 40% increased risk ofdeveloping vitiligo [128]. These findings suggest that GzmB is an important genetic locusin vitiligo, although this should be further investigated in studies incorporating subjectsfrom more diverse ethnic backgrounds.In addition to conferring a genetic predisposition to vitiligo, GzmB may offer clinicalrelevance as a diagnostic and prognostic tool. Immunohistochemical analysis has shownlocalization of GzmB-containing CD8+ T cells along the edges of vitiligo lesions in directcontact with apoptotic melanocytes [46]. These findings were absent in lesional, non-lesional, and healthy control specimens. Others have similarly observed elevated expressionof GzmB in vitiligo patients’ skin biopsies, plasma samples, or both [54,129–131]. Moreover,a complete cytokine panel by Ng et al. [54] ranked GzmB among the top three predictivebiomarkers for disease severity. This was consistent with Bertolotti et al. [53], who notedmore profound infiltration of GzmB-expressing T cells in very progressive vitiligo. In spiteof evidence nominating GzmB as a potential predictive biomarker and therapeutic target invitiligo, causality has not been established. The effects of GzmB knockout or inhibition invitiligo should be further examined.8. ConclusionsDespite having a high prevalence and morbidity, cutaneous autoimmune diseaseslack accessible and effective therapies with reasonable side effect profiles. While previ-ously recognized exclusively for its pro-apoptotic function, GzmB has emerged as a keypathologic initiator of extracellular processes ranging from dysregulated growth factor re-lease and inflammation to desmosomal/hemidesmosomal cleavage and/or fibrosis. GzmBelevations accompany many autoimmune skin diseases and may play a driving role inthe onset and progression of the disease. These findings reflect the central role of GzmBas a downstream mediator of several pathways involved in skin autoimmunity. SinceGzmB is not significantly observed in the extracellular milieu under normal conditions, itBiomolecules 2023, 13, 388 9 of 14represents an attractive therapeutic target for minimizing off-target effects. In spite of this,there remains a need to assess viable drug candidates in the clinic. Future efforts shouldfocus on advancing clinical trials examining the safety and efficacy of GzmB inhibitionand the generation of GzmB-based diagnostic and prognostic tools. It is important tonote that, while extracellular GzmB contributes to impaired barrier function, the cleavageof basement membrane/dermal-epidermal junction proteins, vascular permeability, andinflammation, the role(s) of extracellular GzmB in autoimmune pathologies is still in itsinfancy and not yet fully characterized. Consequently, while GzmB is abundant in manyautoimmune skin pathologies, the majority of previous studies have not considered therecently discovered extracellular roles for this protease. Given that GzmB retains its activityin the extracellular milieu, it is likely that such mechanisms could contribute to the onsetand progression of disease.Author Contributions: Conceptualization, A.G. and D.J.G.; data curation and writing—original draftpreparation, A.G.; writing—review and editing, D.J.G.. All authors have read and agreed to thepublished version of the manuscript.Funding: This research was funded by: Canadian Institutes of Health Research: FDN-143324;Michael Smith Foundation for Health Research: I2C-2017-2032; Cancer Research Society: 25422;Eczema Society of Canada: -; Mitacs: IT23676; Praxis Spinal Cord Institute: -; and LEO Foundation:LF-OC-20-000523.Institutional Review Board Statement: Not applicable.Informed Consent Statement: Not applicable.Data Availability Statement: Not applicable.Conflicts of Interest: D.J.G. is a co-founder and CSO of viDA Therapeutics.References1. Mitratza, M.; Klijs, B.; Hak, A.E.; Kardaun, J.W.P.F.; Kunst, A.E. Systemic autoimmune disease as a cause of death: Mortalityburden and comorbidities. Rheumatology 2020, 60, 1321–1330. [CrossRef] [PubMed]2. Cooper, G.S.; Bynum, M.L.; Somers, E.C. Recent insights in the epidemiology of autoimmune diseases: Improved prevalenceestimates and understanding of clustering of diseases. J. Autoimmun. 2009, 33, 197–207. [CrossRef]3. Lerner, A.; Jeremias, P.; Matthias, T. The World Incidence and Prevalence of Autoimmune Diseases is Increasing. Int. J. Celiac Dis.2015, 3, 151–155. [CrossRef]4. Dinse, G.E.; Parks, C.G.; Weinberg, C.R.; Co, C.A.; Wilkerson, J.; Zeldin, D.C.; Chan, E.K.L.; Miller, F.W. Increasing Prevalence ofAntinuclear Antibodies in the United States. Arthritis Rheumatol. 2022, 74, 2032–2041. [CrossRef] [PubMed]5. Rosenblum, M.D.; Remedios, K.A.; Abbas, A.K. Mechanisms of human autoimmunity. J. Clin. Investig. 2015, 125, 2228–2233.[CrossRef]6. Julian, M.K. Autoimmune disease. Nurs. Manag. 2014, 45, 24–29. [CrossRef]7. Lee, H.L.; Jang, J.W.; Lee, S.W.; Yoo, S.H.; Kwon, J.H.; Nam, S.W.; Bae, S.H.; Choi, J.Y.; Han, N.I.; Yoon, S.K. Inflammatory cytokinesand change of Th1/Th2 balance as prognostic indicators for hepatocellular carcinoma in patients treated with transarterialchemoembolization. Sci. Rep. 2019, 9, 1–8. [CrossRef]8. Santamaria, P. Cytokines and Chemokines in Autoimmune Disease: An Overview. Adv. Exp. Med. Biol. 2003, 520, 1–7. [CrossRef]9. Rashtak, S.; Pittelkow, M.R. Skin Involvement in Systemic Autoimmune Diseases. Dermatol. Immun. 2008, 10, 344–358. [CrossRef]10. Grönhagen, C.; Nyberg, F. Cutaneous lupus erythematosus: An update. Indian Dermatol. Online J. 2014, 5, 7–13. [CrossRef]11. Hughes, M.; Herrick, A.L. Digital Ulcers in Systemic Sclerosis. Rheumatology 2017, 56, 14–25. [CrossRef] [PubMed]12. Reunala, T.; Hervonen, K.; Salmi, T. Dermatitis Herpetiformis: An Update on Diagnosis and Management. Am. J. Clin. Dermatol.2021, 22, 329–338. [CrossRef] [PubMed]13. Whitton, M.E.; Pinart, M.; Batchelor, J.; Leonardi-Bee, J.; González, U.; Jiyad, Z.; Eleftheriadou, V.; Ezzedine, K. Interventions forVitiligo. Cochrane Database Syst. Rev. 2015. [CrossRef] [PubMed]14. Hannon, C.W.; McCourt, C.; Lima, H.C.; Chen, S.; Bennett, C. Interventions for Cutaneous Disease in Systemic Lupus Ery-thematosus. Cochrane Database Syst. Rev. 2021. [CrossRef]15. Mehta, A.; Nadkarni, N.; Patil, S.; Godse, K.; Gautam, M.; Agarwal, S. Topical corticosteroids in dermatology. Indian J. Dermatol.Venereol. Leprol. 2016, 82, 371–378. [CrossRef]16. Jung, K.; Pawluk, M.A.; Lane, M.; Nabai, L.; Granville, D.J. Granzyme B in epithelial barrier dysfunction and related skin diseases.Am. J. Physiol. Physiol. 2022, 323, C170–C189. [CrossRef]Biomolecules 2023, 13, 388 10 of 1417. Hiroyasu, S.; Hiroyasu, A.; Granville, D.J.; Tsuruta, D. Pathological functions of granzyme B in inflammatory skin diseases. J.Dermatol. Sci. 2021, 104, 76–82. [CrossRef]18. Turner, C.T.; Lim, D.; Granville, D.J. Granzyme B in skin inflammation and disease. Matrix Biol. 2019, 75–76, 126–140. [CrossRef]19. Lord, S.J.; Rajotte, R.V.; Korbutt, G.S.; Bleackley, R.C. Granzyme B: A natural born killer. Immunol. Rev. 2003, 193, 31–38. [CrossRef]20. Voskoboinik, I.; Whisstock, J.C.; Trapani, J.A. Perforin and granzymes: Function, dysfunction and human pathology. Nat. Rev.Immunol. 2015, 15, 388–400. [CrossRef]21. Isaaz, S.; Baetz, K.; Olsen, K.; Podack, E.; Griffiths, G.M. Serial killing by cytotoxic T lymphocytes: T cell receptor triggersdegranulation, re-filling of the lytic granules and secretion of lytic proteins via a non-granule pathway. Eur. J. Immunol. 1995, 25,1071–1079. [CrossRef] [PubMed]22. Wang, H.; Huang, Y.; He, J.; Zhong, L.; Zhao, Y. Dual roles of granzyme B. Scand. J. Immunol. 2021, 94, e13086. [CrossRef]23. Boivin, W.A.; Cooper, D.M.; Hiebert, P.R.; Granville, D.J. Intracellular versus extracellular granzyme B in immunity and disease:Challenging the dogma. Lab. Investig. 2009, 89, 1195–1220. [CrossRef] [PubMed]24. Parkinson, L.G.; Toro, A.; Zhao, H.; Brown, K.; Tebbutt, S.J.; Granville, D.J. Granzyme B mediates both direct and indirect cleavageof extracellular matrix in skin after chronic low-dose ultraviolet light irradiation. Aging Cell 2014, 14, 67–77. [CrossRef]25. Shah, H.; Eisenbarth, S.; Tormey, C.A.; Siddon, A.J. Behind the scenes with basophils: An emerging therapeutic target. Immunother.Adv. 2021, 1, ltab008. [CrossRef]26. Martin, A.; Seignez, C.; Racoeur, C.; Isambert, N.; Mabrouk, N.; Scagliarini, A.; Reveneau, S.; Arnould, L.; Bettaieb, A.; Jeannin,J.-F.; et al. Tumor-derived granzyme B-expressing neutrophils acquire antitumor potential after lipid A treatment. Oncotarget2018, 9, 28364–28378. [CrossRef]27. Abebe, E.C.; Dejenie, T.A.; Ayele, T.M.; Baye, N.D.; Teshome, A.A.; Muche, Z.T. The Role of Regulatory B Cells in Health andDiseases: A Systemic Review. J. Inflamm. Res. 2021, 14, 75–84. [CrossRef]28. Karrich, J.J.; Jachimowski, L.C.M.; Nagasawa, M.; Kamp, A.; Balzarolo, M.; Wolkers, M.; Uittenbogaart, C.H.; Van Ham, S.M.;Blom, B. IL-21–stimulated human plasmacytoid dendritic cells secrete granzyme B, which impairs their capacity to induce T-cellproliferation. Blood 2013, 121, 3103–3111. [CrossRef]29. Choy, J.C.; McDonald, P.C.; Suarez, A.C.; Hung, V.H.Y.; Wilson, J.E.; McManus, B.M.; Granville, D.J. Granzyme B in Atherosclerosisand Transplant Vascular Disease: Association with Cell Death and Atherosclerotic Disease Severity. Mod. Pathol. 2003, 16, 460–470.[CrossRef]30. Park, S.; Anderson, N.L.; Canaria, D.A.; Olson, M.R. Granzyme-Producing CD4 T Cells in Cancer and Autoimmune Disease.Immunohorizons 2021, 5, 909–917. [CrossRef]31. Grover, P.; Goel, P.N.; Greene, M.I. Regulatory T Cells: Regulation of Identity and Function. Front. Immunol. 2021, 12, 750542.[CrossRef]32. Hernandez-Pigeon, H.; Jean, C.; Charruyer, A.; Haure, M.-J.; Titeux, M.; Tonasso, L.; Quillet-Mary, A.; Baudouin, C.; Charveron,M.; Laurent, G. Human Keratinocytes Acquire Cellular Cytotoxicity under UV-B Irradiation: Implication of Granzyme B andPerforin. J. Biol. Chem. 2006, 281, 13525–13532. [CrossRef]33. Kaiserman, D.; Bird, P.I. Control of granzymes by serpins. Cell Death Differ. 2009, 17, 586–595. [CrossRef]34. Hiroyasu, S.; Zeglinski, M.R.; Zhao, H.; Pawluk, M.A.; Turner, C.T.; Kasprick, A.; Tateishi, C.; Nishie, W.; Burleigh, A.; Lennox,P.A.; et al. Granzyme B inhibition reduces disease severity in autoimmune blistering diseases. Nat. Commun. 2021, 12, 302.[CrossRef]35. Klein, J.L.; Shows, T.B.; Dupont, B.; Trapani, J.A. Genomic organization and chromosomal assignment for a serine protease gene(CSPB) expressed by human cytotoxic lymphocytes. Genomics 1989, 5, 110–117. [CrossRef] [PubMed]36. Chowdhury, D.; Lieberman, J. Death by a Thousand Cuts: Granzyme Pathways of Programmed Cell Death. Annu. Rev. Immunol.2008, 26, 389–420. [CrossRef]37. Waugh, S.M.; Craik, C.S.; Harris, J.L.; Fletterick, R. The structure of the pro-apoptotic protease granzyme B reveals the moleculardeterminants of its specificity. Nat. Struct. Biol. 2000, 7, 762–765. [CrossRef]38. Estebanez-Perpina, E.; Fuentes-Prior, P.; Belorgey, D.; Braun, M.; Kiefersauer, R.; Maskos, K.; Huber, R.; Rubin, H.; Bode, W.Crystal Structure of the Caspase Activator Human Granzyme B, a Proteinase Highly Specific for an Asp-P1 Residue. Biol. Chem.2000, 381, 1203–1214. [CrossRef] [PubMed]39. Sun, J.; Bird, C.H.; Sutton, V.; McDonald, L.; Coughlin, P.B.; De Jong, T.A.; Trapani, J.; Bird, P. A Cytosolic Granzyme B InhibitorRelated to the Viral Apoptotic Regulator Cytokine Response Modifier A Is Present in Cytotoxic Lymphocytes. J. Biol. Chem. 1996,271, 27802–27809. [CrossRef] [PubMed]40. Russo, V.; Klein, T.; Lim, D.J.; Solis, N.; Machado, Y.; Hiroyasu, S.; Nabai, L.; Shen, Y.; Zeglinski, M.R.; Zhao, H.; et al. Granzyme Bis elevated in autoimmune blistering diseases and cleaves key anchoring proteins of the dermal-epidermal junction. Sci. Rep.2018, 8, 1–11. [CrossRef] [PubMed]41. Willoughby, C.A.; Bull, H.G.; Garcia-Calvo, M.; Jiang, J.; Chapman, K.T.; Thornberry, N.A. Discovery of potent, selective humangranzyme B inhibitors that inhibit CTL mediated apoptosis. Bioorganic Med. Chem. Lett. 2002, 12, 2197–2200. [CrossRef] [PubMed]42. Thornberry, N.A.; Rano, T.A.; Peterson, E.P.; Rasper, D.M.; Timkey, T.; Garcia-Calvo, M.; Houtzager, V.M.; Nordstrom, P.A.; Roy,S.; Vaillancourt, J.P.; et al. A Combinatorial Approach Defines Specificities of Members of the Caspase Family and Granzyme B. J.Biol. Chem. 1997, 272, 17907–17911. [CrossRef] [PubMed]Biomolecules 2023, 13, 388 11 of 1443. Harris, J.L.; Peterson, E.P.; Hudig, D.; Thornberry, N.A.; Craik, C.S. Definition and Redesign of the Extended Substrate Specificityof Granzyme B. J. Biol. Chem. 1998, 273, 27364–27373. [CrossRef]44. Shen, Y.; Zeglinski, M.; Turner, C.; Raithatha, S.A.; Wu, Z.; Russo, V.; Oram, C.; Hiroyasu, S.; Nabai, L.; Zhao, H.; et al. Topicalsmall molecule granzyme B inhibitor improves remodeling in a murine model of impaired burn wound healing. Exp. Mol. Med.2018, 50, 1–11. [CrossRef] [PubMed]45. Turner, C.T.; Zeglinski, M.R.; Richardson, K.C.; Santacruz, S.; Hiroyasu, S.; Wang, C.; Zhao, H.; Shen, Y.; Sehmi, R.; Lima, H.;et al. Granzyme B Contributes to Barrier Dysfunction in Oxazolone-Induced Skin Inflammation through E-Cadherin and FLGCleavage. J. Investig. Dermatol. 2020, 141, 36–47. [CrossRef] [PubMed]46. Wijngaard, R.V.D.; Wankowicz-Kalinska, A.; Le Poole, C.; Tigges, B.; Westerhof, W.; Das, P. Local Immune Response in Skin ofGeneralized Vitiligo Patients. Lab. Investig. 2000, 80, 1299–1309. [CrossRef] [PubMed]47. Hunger, R.E.; Brönnimann, M.; Kappeler, A.; Mueller, C.; Braathen, L.R.; Yawalkar, N. Detection of perforin and granzyme BmRNA expressing cells in lichen sclerosus. Exp. Dermatol. 2007, 16, 416–420. [CrossRef] [PubMed]48. Lage, D.; Pimentel, V.N.; Soares, T.C.B.; Souza, E.M.; Metze, K.; Cintra, M.L. Perforin and granzyme B expression in oral andcutaneous lichen planus—A comparative study. J. Cutan. Pathol. 2011, 38, 973–978. [CrossRef]49. Hussein, M.R.; Ali, F.M.N.; Omar, A.-E.M.M. Immunohistological analysis of immune cells in blistering skin lesions. J. Clin.Pathol. 2007, 60, 62–71. [CrossRef]50. Blanco, P.; Pitard, V.; Taupin, J.-L.; Pellegrin, J.-L. Increase in activated CD8+ T lymphocytes expressing perforin and granzyme Bcorrelates with disease activity in patients with systemic lupus erythematosus. Arthritis Rheum. 2005, 52, 201–211. [CrossRef]51. Kok, H.M.; Hoogen, L.L.V.D.; Van Roon, J.A.G.; Adriaansen, E.J.M.; Fritsch-Stork, R.D.E.; Nguyen, T.Q.; Goldschmeding, R.;Radstake, T.R.D.J.; Bovenschen, N. Systemic and local granzyme B levels are associated with disease activity, kidney damage andinterferon signature in systemic lupus erythematosus. Rheumatology 2017, 56, 2129–2134. [CrossRef]52. Shah, D.; Kiran, R.; Wanchu, A.; Bhatnagar, A. Soluble granzyme B and cytotoxic T lymphocyte activity in the pathogenesis ofsystemic lupus erythematosus. Cell. Immunol. 2011, 269, 16–21. [CrossRef] [PubMed]53. Bertolotti, A.; Boniface, K.; Vergier, B.; Mossalayi, D.; Taieb, A.; Ezzedine, K.; Seneschal, J. Type I interferon signature in theinitiation of the immune response in vitiligo. Pigment. Cell Melanoma Res. 2014, 27, 398–407. [CrossRef] [PubMed]54. Ng, C.Y.; Chiu, Y.-C.; Chan, Y.-P.; Lin, Y.-J.; Chung, P.-H.; Chung, W.-H.; Ku, C.-L. Skin Interstitial Fluid and Plasma MultiplexCytokine Analysis Reveals IFN-γ Signatures and Granzyme B as Useful Biomarker for Activity, Severity and Prognosis Assessmentin Vitiligo. Front. Immunol. 2022, 13, 872458. [CrossRef] [PubMed]55. Koguchi-Yoshioka, H.; Watanabe, R.; Matsumura, Y.; Okiyama, N.; Ishitsuka, Y.; Nakamura, Y.; Fujisawa, Y.; Fujimoto, M. ThePossible Linkage of Granzyme B-Producing Skin T Cells with the Disease Prognosis of Alopecia Areata. J. Investig. Dermatol.2020, 141, 427–429.e10. [CrossRef] [PubMed]56. Ghoreishi, M.; Martinka, M.; Dutz, J. Type 1 interferon signature in the scalp lesions of alopecia areata. Br. J. Dermatol. 2010, 163,57–62. [CrossRef] [PubMed]57. Del Duca, E.; Ruiz, J.R.; Pavel, A.; Sanyal, R.D.; Song, T.; Gay-Mimbrera, J.; Zhang, N.; Estrada, Y.; Peng, X.; Renert-Yuval, Y.; et al.Frontal fibrosing alopecia shows robust T helper 1 and Janus kinase 3 skewing. Br. J. Dermatol. 2020, 183, 1083–1093. [CrossRef]58. Pratt, C.H.; King, L.E.; Messenger, A.G.; Christiano, A.M.; Sundberg, J.P. Alopecia Areata. Nat. Rev. Dis. Primers 2017, 3, 17011.[CrossRef]59. Xing, L.; Dai, Z.; Jabbari, A.; Cerise, J.E.; Higgins, C.A.; Gong, W.; de Jong, A.; Harel, S.; DeStefano, G.M.; Rothman, L.; et al.Alopecia areata is driven by cytotoxic T lymphocytes and is reversed by JAK inhibition. Nat. Med. 2014, 20, 1043–1049. [CrossRef]60. Phan, K.; Sebaratnam, D.F. JAK inhibitors for alopecia areata: A systematic review and meta-analysis. J. Eur. Acad. Dermatol.Venereol. 2019, 33, 850–856. [CrossRef]61. Banerjee, S.; Biehl, A.; Gadina, M.; Hasni, S.; Schwartz, D.M. JAK–STAT Signaling as a Target for Inflammatory and Auto-immuneDiseases: Current and Future Prospects. Drugs 2017, 77, 521–546. [CrossRef]62. Olayinka, J.T.; Richmond, J.M. Immunopathogenesis of alopecia areata. Curr. Res. Immunol. 2021, 2, 7–11. [CrossRef] [PubMed]63. Duncan, F.J.; Silva, K.A.; Johnson, C.J.; King, B.L.; Szatkiewicz, J.P.; Kamdar, S.P.; Ong, D.E.; Napoli, J.L.; Wang, J.; King, L.E.; et al.Endogenous Retinoids in the Pathogenesis of Alopecia Areata. J. Investig. Dermatol. 2013, 133, 334–343. [CrossRef] [PubMed]64. Duriancik, D.M.; Lackey, D.E.; Hoag, K.A. Vitamin A as a Regulator of Antigen Presenting Cells. J. Nutr. 2010, 140, 1395–1399.[CrossRef] [PubMed]65. Siebenhaar, F.; Sharov, A.A.; Peters, E.M.; Sharova, T.Y.; Syska, W.; Mardaryev, A.N.; Freyschmidt-Paul, P.; Sundberg, J.P.;Maurer, M.; Botchkarev, V.A. Substance P as an Immunomodulatory Neuropeptide in a Mouse Model for Autoimmune Hair Loss(Alopecia Areata). J. Investig. Dermatol. 2007, 127, 1489–1497. [CrossRef]66. O’Connor, T.M.; O’Connell, J.; O’Brien, D.I.; Goode, T.; Bredin, C.P.; Shanahan, F. The role of substance P in inflammatory disease.J. Cell. Physiol. 2004, 201, 167–180. [CrossRef]67. Guo, H.; Cheng, Y.; Shapiro, J.; McElwee, K. The role of lymphocytes in the development and treatment of alopecia areata. ExpertRev. Clin. Immunol. 2015, 11, 1335–1351. [CrossRef]68. McPhee, C.G.; Duncan, F.J.; Silva, K.A.; King, L.E.; HogenEsch, H.; Roopenian, D.C.; Everts, H.B.; Sundberg, J.P. IncreasedExpression of Cxcr3 and Its Ligands, Cxcl9 and Cxcl10, during the Development of Alopecia Areata in the Mouse. J. Investig.Dermatol. 2012, 132, 1736–1738. [CrossRef] [PubMed]Biomolecules 2023, 13, 388 12 of 1469. Hashimoto, K.; Yamada, Y.; Sekiguchi, K.; Matsuda, S.; Mori, S.; Matsumoto, T. Induction of alopecia areata in C3H/HeJ miceusing cryopreserved lymphocytes. J. Dermatol. Sci. 2021, 102, 177–183. [CrossRef]70. Villasante Fricke, A.C.; Miteva, M. Epidemiology and Burden of Alopecia Areata: A Systematic Review. Clin. Cosmet. Investig.Dermatol. 2015, 8, 397–403.71. Fukumoto, T.; Fukumoto, R.; Magno, E.; Oka, M.; Nishigori, C.; Horita, N. Treatments for alopecia areata: A systematic reviewand network meta-analysis. Dermatol. Ther. 2021, 34, e14916. [CrossRef] [PubMed]72. Lai, V.W.Y.; Chen, G.; Gin, D.; Sinclair, R. Systemic treatments for alopecia areata: A systematic review. Australas. J. Dermatol.2018, 60, e1–e13. [CrossRef] [PubMed]73. Kanti, V.; Röwert-Huber, J.; Vogt, A.; Blume-Peytavi, U. Cicatricial alopecia. JDDG J. Dtsch. Dermatol. Ges. 2018, 16, 435–461.[CrossRef] [PubMed]74. Katoulis, A.C.; Christodoulou, C.; Liakou, A.I.; Kouris, A.; Korkoliakou, P.; Kaloudi, E.; Kanelleas, A.; Papageorgiou, C.;Rigopoulos, D. Quality of life and psychosocial impact of scarring and non-scarring alopecia in women. JDDG J. Dtsch. Dermatol.Ges. 2015, 13, 137–141. [CrossRef]75. Boivin, W.A.; Shackleford, M.; Hoek, A.V.; Zhao, H.; Hackett, T.L.; Knight, D.A.; Granville, D.J. Granzyme B Cleaves Decorin,Biglycan and Soluble Betaglycan, Releasing Active Transforming Growth Factor-β1. PLoS ONE 2012, 7, e33163. [CrossRef]76. Honardoust, D.; Varkey, M.; Hori, K.; Ding, J.; Shankowsky, H.A.; Tredget, E.E. Small leucine-rich proteoglycans, decorin andfibromodulin, are reduced in postburn hypertrophic scar. Wound Repair Regen. 2011, 19, 368–378. [CrossRef]77. Meenakshi, J.; Vidyameenakshi, S.; Ananthram, D.; Ramakrishnan, K.M.; Jayaraman, V.; Babu, M. Low decorin expression alongwith inherent activation of ERK1,2 in ear lobe keloids. Burns 2009, 35, 519–526. [CrossRef]78. Mukhopadhyay, A.; Wong, M.Y.; Chan, S.Y.; Do, D.V.; Khoo, A.; Ong, C.T.; Cheong, H.H.; Lim, I.J.; Phan, T.T. Syndecan-2 andDecorin: Proteoglycans with a Difference—Implications in Keloid Pathogenesis. J. Trauma: Inj. Infect. Crit. Care 2010, 68, 999–1008.[CrossRef]79. Ang, L.S.; Boivin, W.A.; Williams, S.J.; Zhao, H.; Abraham, T.; Carmine-Simmen, K.; McManus, B.M.; Bleackley, R.C.; Granville,D.J. Serpina3n attenuates granzyme B-mediated decorin cleavage and rupture in a murine model of aortic aneurysm. Cell DeathDis. 2011, 2, e209. [CrossRef]80. Moretti, S.; Amato, L.; Massi, D.; Bianchi, B.; Gallerani, I.; Fabbri, P. Evaluation of inflammatory infiltrate and fibrogenic cytokinesin pseudopelade of Brocq suggests the involvement of T-helper 2 and 3 cytokines. Br. J. Dermatol. 2004, 151, 84–90. [CrossRef][PubMed]81. Aguh, C.; Dina, Y.; Talbot, C.C.; Garza, L. Fibroproliferative genes are preferentially expressed in central centrifugal cicatricialalopecia. J. Am. Acad. Dermatol. 2018, 79, 904–912.e1. [CrossRef] [PubMed]82. Harries, M.J.; Paus, R. The Pathogenesis of Primary Cicatricial Alopecias. Am. J. Pathol. 2010, 177, 2152–2162. [CrossRef]83. Joshi, R. Interface Dermatitis. Indian J. Dermatol. Venereol. Leprol. 2013, 79, 349. [CrossRef] [PubMed]84. Grassi, M.; Capello, F.; Bertolino, L.; Seia, Z.; Pippione, M. Identification of granzyme B-expressing CD-8-positive T cells inlymphocytic inflammatory infiltrate in cutaneous lupus erythematosus and in dermatomyositis. Clin. Exp. Dermatol. 2009, 34,910–914. [CrossRef]85. Sontheimer, R.D. Lichenoid Tissue Reaction/Interface Dermatitis: Clinical and Histological Perspectives. J. Investig. Dermatol.2009, 129, 1088–1099. [CrossRef] [PubMed]86. Okiyama, N.; Fujimoto, M. Clinical perspectives and murine models of lichenoid tissue reaction/interface dermatitis. J. Dermatol.Sci. 2015, 78, 167–172. [CrossRef]87. Boch, K.; Langan, E.A.; Kridin, K.; Zillikens, D.; Ludwig, R.J.; Bieber, K. Lichen Planus. Front. Med. 2021, 8, 737813. [CrossRef]88. Wenzel, J.; Scheler, M.; Proelss, J.; Bieber, T.; Tüting, T. Type I interferon-associated cytotoxic inflammation in lichen planus. J.Cutan. Pathol. 2006, 33, 672–678. [CrossRef]89. Shimizu, M.; Higaki, Y.; Higaki, M.; Kawashima, M. The role of granzyme B-expressing CD8-positive T cells in apoptosis ofkeratinocytes in lichen planus. Arch. Dermatol. Res. 1997, 289, 527–532. [CrossRef]90. Ammar, M.; Mokni, M.; Boubaker, S.; El Gaied, A.; Ben Osman, A.; Louzir, H. Involvement of granzyme B and granulysin in thecytotoxic response in lichen planus. J. Cutan. Pathol. 2008, 35, 630–634. [CrossRef]91. Pimentel, V.N.; De Matos, L.S.; Soares, T.C.B.; Adam, R.; Metze, K.; Correa, M.E.P.; De Souza, C.A.; Cintra, M.L. Perforin andgranzyme B involvement in oral lesions of lichen planus and chronic GVHD. J. Oral Pathol. Med. 2010, 39, 741–746. [CrossRef][PubMed]92. Blake, S.C.; Daniel, B.S. Cutaneous lupus erythematosus: A review of the literature. Int. J. Women’s Dermatol. 2019, 5, 320–329.[CrossRef]93. Tsokos, G.C.; Lo, M.S.; Reis, P.C.; Sullivan, K.E. New insights into the immunopathogenesis of systemic lupus erythematosus.Nat. Rev. Rheumatol. 2016, 12, 716–730. [CrossRef] [PubMed]94. Garelli, C.J.; Refat, M.A.; Nanaware, P.P.; Ramirez-Ortiz, Z.G.; Rashighi, M.; Richmond, J.M. Current Insights in Cutaneous LupusErythematosus Immunopathogenesis. Front. Immunol. 2020, 11, 1353. [CrossRef]95. Casciola-Rosen, L.; Andrade, F.; Ulanet, D.; Wong, W.B.; Rosen, A. Cleavage by Granzyme B Is Strongly Predictive of AutoantigenStatus. J. Exp. Med. 1999, 190, 815–826. [CrossRef] [PubMed]96. Abdou, A.G.; Shoeib, M.; Bakry, O.A.; El-Bality, H. Immunohistochemical Expression of Granzyme B and Perforin in DiscoidLupus Erythematosus. Ultrastruct. Pathol. 2013, 37, 408–416. [CrossRef] [PubMed]Biomolecules 2023, 13, 388 13 of 1497. Wenzel, J.; Uerlich, M.; Worrenkamper, E.; Freutel, S.; Bieber, T.; Tuting, T. Scarring skin lesions of discoid lupus erythematosusare characterized by high numbers of skin-homing cytotoxic lymphocytes associated with strong expression of the type Iinterferon-induced protein MxA. Br. J. Dermatol. 2005, 153, 1011–1015. [CrossRef]98. DeWane, M.E.; Waldman, R.; Lu, J. Dermatomyositis: Clinical features and pathogenesis. J. Am. Acad. Dermatol. 2020, 82, 267–281.[CrossRef] [PubMed]99. Torchia, D.; Caproni, M.; Volpi, W.; Barletta, E.; Fabbri, P. The Fas/Fas ligand system, rather than granzyme B, may represent themain mediator of epidermal apoptosis in dermatomyositis. Clin. Exp. Dermatol. 2010, 35, 669–670. [CrossRef]100. Goebels, N.; Michaelis, D.; Engelhardt, M.; Huber, S.; Bender, A.; Pongratz, D.; Johnson, M.A.; Wekerle, H.; Tschopp, J.; Jenne, D.;et al. Differential expression of perforin in muscle-infiltrating T cells in polymyositis and dermatomyositis. J. Clin. Investig. 1996,97, 2905–2910. [CrossRef]101. Mammen, A.L. Dermatomyositis and Polymyositis: Clinical Presentation, Autoantibodies, and Pathogenesis. Ann. N. Y. Acad. Sci.2010, 1184, 134–153. [CrossRef] [PubMed]102. Daniel, B.S.; Murrell, D.F. Review of Autoimmune Blistering Diseases: The Pemphigoid Diseases. J. Eur. Acad. Dermatol. Venereol.2019, 33, 1685–1694. [CrossRef] [PubMed]103. Kridin, K.; Ludwig, R. The Growing Incidence of Bullous Pemphigoid: Overview and Potential Explanations. Front. Med. 2018, 5,220. [CrossRef] [PubMed]104. Garrido, P.M.; Queirós, C.S.; Travassos, A.R.; Borges-Costa, J.; Filipe, P. Emerging treatments for bullous pemphigoid. J. Dermatol.Treat. 2021, 33, 649–661. [CrossRef]105. Kirtschig, G.; Middleton, P.; Bennett, C.; Murrell, D.F.; Wojnarowska, F.; Khumalo, N.P. Interventions for Bullous Pemphigoid.Cochrane Database Syst. Rev. 2010. [CrossRef]106. Hiroyasu, S.; Turner, C.T.; Richardson, K.; Granville, D.J. Proteases in Pemphigoid Diseases. Front. Immunol. 2019, 10, 1454.[CrossRef]107. Nishie, W. Collagen XVII Processing and Blistering Skin Diseases. Acta Derm. Venereol. 2020, 100, 102–107. [CrossRef]108. Armstrong, A.W.; Read, C. Pathophysiology, Clinical Presentation, and Treatment of Psoriasis: A Review. JAMA—J. Am. Med.Assoc. 2020, 323, 1945–1960. [CrossRef]109. Rendon, A.; Schäkel, K. Psoriasis Pathogenesis and Treatment. Int. J. Mol. Sci. 2019, 20, 1475. [CrossRef]110. Rønholt, K.; Iversen, L. Old and New Biological Therapies for Psoriasis. Int. J. Mol. Sci. 2017, 18, 2297. [CrossRef]111. Yawalkar, N.; Schmid, S.; Braathen, L.; Pichler, W. Perforin and granzyme B may contribute to skin inflammation in atopicdermatitis and psoriasis. Br. J. Dermatol. 2001, 144, 1133–1139. [CrossRef] [PubMed]112. Kamata, Y.; Kimura, U.; Matsuda, H.; Tengara, S.; Kamo, A.; Umehara, Y.; Iizumi, K.; Kawasaki, H.; Suga, Y.; Ogawa, H.; et al.Relationships among plasma granzyme B level, pruritus and dermatitis in patients with atopic dermatitis. J. Dermatol. Sci. 2016,84, 266–271. [CrossRef] [PubMed]113. Fenix, K.; Wijesundara, D.K.; Cowin, A.J.; Grubor-Bauk, B.; Kopecki, Z. Immunological Memory in Imiquimod-Induced MurineModel of Psoriasiform Dermatitis. Int. J. Mol. Sci. 2020, 21, 7228. [CrossRef] [PubMed]114. Shi, L.; Lian, N.; Liu, L.; Chen, M. Tapering and discontinuation of systemic medications in psoriasis patients with low diseaseactivity. Dermatol. Ther. 2020, 33, e13599. [CrossRef]115. Piaserico, S.; Gisondi, P.; Simone, C.; Marinello, E.; Conti, A.; Amerio, P.; Peserico, A. Down-titration of Adalimumab andEtanercept in Psoriatic Patients: A Multicentre Observational Study. Acta Derm. Venereol. 2016, 96, 251–252. [CrossRef]116. Denton, C.; Khanna, D. Systemic Sclerosis. Lancet 2017, 390, 1685–1699. [CrossRef]117. Henriques, A.; Santiago, M.; Martinho, A.; Trindade, H.; Silva-Santos, B.; Henriques, M.J.; Da Silva, J.A.P.; Paiva, A.; Silva, C.Subset-specific alterations in frequencies and functional signatures of γδ T cells in systemic sclerosis patients. Inflamm. Res. 2016,65, 985–994. [CrossRef]118. Ulanet, D.B.; Flavahan, N.A.; Casciola-Rosen, L.; Rosen, A. Selective cleavage of nucleolar autoantigen B23 by granzyme Bin differentiated vascular smooth muscle cells: Insights into the association of specific autoantibodies with distinct diseasephenotypes. Arthritis Rheum. 2004, 50, 233–241. [CrossRef]119. Mulligan-Kehoe, M.J.; Drinane, M.C.; Casciola-Rosen, L.; Hummers, L.K.; Hall, A.E.; Rosen, A.; Wigley, F.M.; Simons, M.Granzyme B-dependent matrix degradation generates anti-angiostatic activity in scleroderma patients. Vasc. Pharmacol. 2006, 45,e147. [CrossRef]120. Schachna, L.; Wigley, F.M.; Morris, S.; Gelber, A.C.; Rosen, A.; Casciola-Rosen, L. Recognition of Granzyme B-generatedautoantigen fragments in scleroderma patients with ischemic digital loss. Arthritis Rheum. 2002, 46, 1873–1884. [CrossRef]121. Darrah, E.; Rosen, A. Granzyme B cleavage of autoantigens in autoimmunity. Cell Death Differ. 2010, 17, 624–632. [CrossRef]122. Bergqvist, C.; Ezzedine, K. Vitiligo: A Review. Dermatology 2020, 236, 571–592. [CrossRef]123. Zhang, Y.; Cai, Y.; Shi, M.; Jiang, S.; Cui, S.; Wu, Y.; Gao, X.-H.; Chen, H.-D. The Prevalence of Vitiligo: A Meta-Analysis. PLoSONE 2016, 11, e0163806. [CrossRef] [PubMed]124. Rashighi, M.; Harris, J.E. Vitiligo Pathogenesis and Emerging Treatments. Dermatol. Clin. 2017, 35, 257–265. [CrossRef] [PubMed]125. Krüger, C.; Schallreuter, K.U. A review of the worldwide prevalence of vitiligo in children/adolescents and adults. Int. J. Dermatol.2012, 51, 1206–1212. [CrossRef] [PubMed]126. Ferrara, T.M.; Jin, Y.; Gowan, K.; Fain, P.R.; Spritz, R.A. Risk of Generalized Vitiligo Is Associated with the Common 55R-94A-247HVariant Haplotype of GZMB (Encoding Granzyme B). J. Investig. Dermatol. 2013, 133, 1677–1679. [CrossRef] [PubMed]Biomolecules 2023, 13, 388 14 of 14127. Jeong, K.-H.; Kim, S.K.; Seo, J.-K.; Shin, M.K.; Lee, M.-H. Association of GZMB polymorphisms and susceptibility to non-segmentalvitiligo in a Korean population. Sci. Rep. 2021, 11, 397. [CrossRef]128. Xu, M.; Liu, Y.; Liu, Y.; Li, X.; Chen, G.; Dong, W.; Xiao, S. Genetic polymorphisms of GZMB and vitiligo: A genetic associationstudy based on Chinese Han population. Sci. Rep. 2018, 8, 13001. [CrossRef]129. Tulic, M.K.; Cavazza, E.; Cheli, Y.; Jacquel, A.; Luci, C.; Cardot-Leccia, N.; Hadhiri-Bzioueche, H.; Abbe, P.; Gesson, M.; Sormani,L.; et al. Innate lymphocyte-induced CXCR3B-mediated melanocyte apoptosis is a potential initiator of T-cell autoreactivity invitiligo. Nat. Commun. 2019, 10, 2178. [CrossRef]130. Boniface, K.; Jacquemin, C.; Darrigade, A.-S.; Dessarthe, B.; Martins, C.; Boukhedouni, N.; Vernisse, C.; Grasseau, A.; Thiolat, D.;Rambert, J.; et al. Vitiligo Skin Is Imprinted with Resident Memory CD8 T Cells Expressing CXCR3. J. Investig. Dermatol. 2017,138, 355–364. [CrossRef]131. Yang, L.; Wei, Y.; Sun, Y.; Shi, W.; Yang, J.; Zhu, L.; Li, M. Interferon-gamma Inhibits Melanogenesis and Induces Apoptosisin Melanocytes: A Pivotal Role of CD8+ Cytotoxic T Lymphocytes in Vitiligo. Acta Dermato-Venereologica 2015, 95, 664–670.[CrossRef] [PubMed]Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individualauthor(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury topeople or property resulting from any ideas, methods, instructions or products referred to in the content.
Article
eng
Reviewed
Vancouver : University of British Columbia Library
Multidisciplinary Digital Publishing Institute
CC BY 4.0
Faculty
Researcher
Granzyme B
serine protease
autoimmune skin disease
inflammation
extracellular matrix
small molecule inhibitor
Granzyme B in Autoimmune Skin Disease
Text