Reduction in circulating Endothelin-1 levels by inhaled COPD medications

Chronic obstructive pulmonary disease (COPD) can be complicated by pulmonary hypertension (PH), impacting prognosis and quality of life. Endothelin-1 (ET-1) is implicated in PH development and elevated in COPD patients. The impact of COPD treatments on ET-1 and COPD-related PH remains unclear. This study investigated changes in ET-1 levels after administration of inhaled COPD medications and explored underlying mechanisms.

Patients underwent pulmonary function tests, COPD Assessment Test, and plasma ET-1 measurement before and 4-12 weeks after treatment initiation. In mice, elastase-induced emphysema was treated with budesonide (BUD), glycopyrronium (GLY), and formoterol (FOR) combinations for 2 weeks. Plasma ET-1 concentration and cytokine expression were analysed. HULEC-5a cells were used to examine ET-1 expression after TNFα stimulation.

The study included 33 patients. COPD patients (n = 24) showed higher baseline plasma ET-1 levels compared to controls (n = 9) (2.12 pg/ml vs 1.54 pg/ml, p < 0.001). Plasma ET-1 levels decreased in COPD patients posttreatment (2.12-1.82 pg/ml, p = 0.004), with reductions observed across all disease stages and treatment regimens. Mice showed elevated ET-1 levels and expression of inflammatory cytokines after elastase instillation. BUD/GLY/FOR treatment significantly reduced ET-1 concentration and TNFα expression. Furthermore, TNFα stimulation upregulated ET-1 expression in HULEC-5a cells.

In COPD patients conventional treatment decreased ET-1 concentration. In mouse models TNFα expression was suppressed by BUD/GLY/FOR. In HULEC-5a cells, TNFα stimulation exerted an increased ET-1expression. These findings suggest that the suppressive effect of inhaler therapy on ET-1 expression is due to the anti-inflammatory effects of these drugs.