Procyanidin B1 Protects HPAEpiCs from Lipopolysaccharide-mediated Inflammation Damage by Modulating the eNOS/NO/cGMP Pathway

Abstract

Background: Procyanidin B1 can attenuate inflammation, but its specific impact and mechanism on sepsis-related acute lung injury (ALI) are obscure. Therefore, this study aimed to explore the effect and mechanism of Procyanidin B1 on the lipopolysaccharide (LPS)-mediated human pulmonary alveolar epithelial cells (HPAEpiCs) injury. Methods: The effect of varying concentrations of Procyanidin B1 (50, 100, 150, or 200 μM) on the viability of HPAEpiCs cells and LPS-mediated HPAEpiCs was assessed using cell counting kit-8. After Procyanidin B1 treatment, the proliferation and apoptosis of LPS-mediated HPAEpiCs, and angiogenesis of human umbilical vein endothelial cells (HUVEC) were evaluated employing colony formation assay, flow cytometer, and angiogenesis experiments. Endothelial nitric oxide synthase (eNOS)/nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway and inflammation were examined using quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA), and western blot analysis. The effects of Procyanidin B1 and L-N-nitro-L-arginine methyl ester (L-NAME) on inflammation and eNOS/NO/cGMP pathway were assessed employing ELISA, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis. Results: Different concentrations of Procyanidin B1 (50, 100, 150, or 200 μM), which was not toxic to normal cells, enhanced LPS-mediated HPAEpiCs activity (p < 0.05), proliferation (p < 0.05), and eNOS expression (p < 0.01). However, Procyanidin B1 reduced apoptosis of LPS-mediated HPAEpiCs (p < 0.05) and stimulated angiogenesis of HUVEC (p < 0.01). Moreover, Procyanidin B1 repressed inflammation, endothelin-1 (ET-1), and inducible nitric oxide synthase (iNOS) levels and enhanced the NO production, cGMP, eNOS, and phosphorylated eNOS levels in LPS-mediated HPAEpiCs (p < 0.05). However, these effects were counteracted by L-NAME (p < 0.05). Conclusions: Procyanidin B1 protected HPAEpiCs from LPS-mediated inflammation damage by modulating the eNOS/NO/cGMP pathway.