Penehyclidine Hydrochloride Decreases Pulmonary Microvascular Endothelial Inflammatory Injury Through a Beta-Arrestin-1-Dependent Mechanism

Penehyclidine hydrochloride (PHC), a type of hyoscyamus drug, has both antimuscarinic and antinicotinic activities and retains potent central and peripheral anticholinergic activities. Compared with other hyoscyamine, the notable advantage of PHC is that it has few M₂ receptor-associated cardiovascular side effects. Recent studies and clinical trials have suggested that treatment with penehyclidine hydrochloride may also possess good effects in the treatment of lung injury. The mechanism responsible for this effect has yet to be determined; however, one possibility is that they might do so by a direct effect on pulmonary vascular endothelium. Since inflammatory reactions of the endothelium are signs of endothelial injury in the pathogenesis of lung injury, we determined the effects of penehyclidine hydrochloride on endothelial inflammatory injury in cultured human pulmonary microvascular endothelial cells (HPMVEC). Furthermore, human pulmonary microvascular endothelial cells were transfected with a shRNA-containing plasmid that specifically targets beta-arrestin-1 mRNA, to test whether the effect of penehyclidine hydrochloride on lipopolysaccharide (LPS)-induced endothelial cell injury is dependent on its upregulation of beta-arrestin-1 or not. Penehyclidine hydrochloride reduced the inflammatory responses to LPS stimulation, as evidenced by reduced lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α), and interleukelin-6 (IL-6) levels, as well as vascular cell adhesion molecule 1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) expressions. This was found to result from increased beta-arrestin-1 expression and decreased nuclear transcription factor-κB (NF-κB) activation. Expression of a shRNA-containing plasmid that specifically targets beta-arrestin-1 mRNA nullified these effects of penehyclidine hydrochloride. The results indicate that penehyclidine hydrochloride exerts a protective effect on pulmonary microvascular endothelial inflammatory injury induced by LPS. We also demonstrate that this is due to its ability to increase beta-arrestin-1, which in turn inhibits NF-κB activation.