Pudilan xiaoyan oral liquid alleviates LPS-induced respiratory injury through decreasing nitroxidative stress and blocking TLR4 activation along with NF-ΚB phosphorylation in mice

Abstract

Ethnopharmacological relevancePudilan xiaoyan oral liquid (PDL), collected in Chinese Pharmacopoeia, has been used clinically for treating inflammatory diseases such as upper respiratory tract infection diseases. However, its potential anti-inflammation and the mechanism are still unclear. Materials and methodslipopolysaccharide (LPS) was used to induce respiratory inflammation of mice by intratracheal administration. UPLC/MS was performed for components analysis of PDL. Enzyme-linked immune sorbent assay (ELISA) was conducted for determining interleukin-6(IL-6), interleukin-1β(IL-1β) and tumor necrosis factor-α(TNF-α) in serum and supernatant of tracheal tissue while Nitric oxide assay kit for nitric oxide (NO) content. Hematoxylin-Eosin (HE) staining was applied to evaluate pathological lesions. Western blotting analysis (WB) and Immunohistochemistry(IHC) were employed for the determination of Toll-like receptors 4(TLR4), TNF-α, IL-6, inducible nitric oxide synthase(iNOS) and nuclear factor-kappa B p65 (NF-κB p65) protein expressions. ResultsSeven major compounds of PDL were analyzed simultaneously. The treatment of PDL could attenuate LPS-induced histopathological damage of tracheal tissues, followed by reducing pro-inflammation mediators including TNF-α and IL-6 in serum and supernatant of tracheal tissue. LPS-induced nitroxidative stress including NO content and iNOS expression was inhibited significantly by PDL. Furthermore, PDL also down-regulated NF-kB p65 phosphorylation and TLR4 expressions. ConclusionThe results indicated that the PDL had a protective effect on LPS-induced respiratory inflammation injury in mice. Our findings for the first time provide experimental evidence for the application of PDL on respiratory inflammation injury in clinical practice.