The anti-proliferative and anti-inflammatory response of COPD airway smooth muscle cells to hydrogen sulfide.

Backbround: COPD is a common, highly debilitating disease of the airways, primarily caused by smoking. Chronic inflammation and structural remodelling are key pathological features of this disease caused, in part, by the aberrant function of airway smooth muscle (ASM). We have previously demonstrated that hydrogen sulfide (HS) can inhibit ASM cell proliferation and CXCL8 release, from cells isolated from non-smokers.

Methods: We examined the effect of HS upon ASM cells from COPD patients. ASM cells were isolated from non-smokers, smokers and patients with COPD (n = 9). Proliferation and cytokine release (IL-6 and CXCL8) of ASM was induced by FCS, and measured by bromodeoxyuridine incorporation and ELISA, respectively.

Results: Exposure of ASM to HS donors inhibited FCS-induced proliferation and cytokine release, but was less effective upon COPD ASM cells compared to the non-smokers and smokers. The mRNA and protein expression of the enzymes responsible for endogenous HS production (cystathionine-β-synthase [CBS] and 3-mercaptopyruvate sulphur transferase [MPST]) were inhibited by HS donors. Finally, we report that exogenous HS inhibited FCS-stimulated phosphorylation of ERK-1/2 and p38 mitogen activated protein kinases (MAPKs), in the non-smoker and smoker ASM cells, with little effect in COPD cells.

Conclusions: HS production provides a novel mechanism for the repression of ASM proliferation and cytokine release. The ability of COPD ASM cells to respond to HS is attenuated in COPD ASM cells despite the presence of the enzymes responsible for HS production.