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The anti-inflammatory effects of long-acting beta-agonists on bronchial epithelium

University of British Columbia

Long-acting β2-agonists (LABAs) are a staple of Chronic Obstructive Pulmonary Disease (COPD) maintenance treatment frequently prescribed to patients for prolonged bronchodilation. Recent studies have suggested that they may also be anti-inflammatory, as demonstrated by lowered neutrophil infiltration and lower mucus secretion. The mechanism of action behind these effects are unknown and further study is needed to elucidate the pathways involved. The purpose of this project was to study the effect of the LABA olodaterol on an in vitro model of the airway epithelium in response to an inflammatory stimulus. Primary airway epithelial cells derived from COPD and control non-COPD patient bronchial brushings were grown into air-liquid interface (ALI) cultures. Cells underwent priming with olodaterol in addition to respiratory syncytial virus (RSV) infection. Culture media was quantified for interleukin-8 (IL-8) secretion via ELISA. Whole cultures underwent immunohistochemistry for quantification of Muc5AC staining, an airway mucin protein. The 1HAEo- and the NCI-H292 cell lines were used to model the bronchial epithelium. Olodaterol was used to pre-treat both cell lines, after which either RSV or lipopolysaccharide (LPS) was added as an inflammatory stimulus and the IL-8 content was measured. Protein lysates were characterized using western blotting for the β2-adrenergic receptor (β2AR), the binding receptor for LABAs. siRNA was used to silence the β2AR. RT-qPCR was used to quantify the knockdown efficiency. ALI cultures showed that COPD subjects secreted higher baseline IL-8 levels than non-COPD controls, indicating that COPD subjects have an altered inflammatory phenotype. When both COPD and non-COPD ALIs were treated with olodaterol and RSV, olodaterol attenuated RSV-induced secretion of IL-8 and Muc5AC in both subject groups. In both 1HAEo- and NCI-H292 cells, RSV and LPS were able to stimulate high IL-8 secretion that was inhibited by treatment with olodaterol. siRNA gene silencing of β2AR in NCI-H292 cells negated olodaterol-mediated attenuation of LPS and RSV-induced IL-8 secretion, suggesting that the anti-inflammatory effect of olodaterol proceeds through the canonical binding receptor. LABAs such as olodaterol have clear anti-inflammatory effects in vitro and may hold clinical relevance. Further studies are needed to determine if these effects have a significant impact on patient therapy.

Text

2021-02-28

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/73867

Experimental Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/