Aqueous extract of Aconitum carmichaelii Debeaux attenuates sepsis-induced acute lung injury via regulation of TLR4/NF-ΚB pathway

Abstract

Purpose: To investigate the therapeutic effect of aqueous extract of Aconitum carmichaelii Debeaux (AEACD) on sepsis-induced acute lung injury (ALI), as well as explore the underlying mechanism of action. Methods: C57BL/6 mice were treated with AEACD by gavage (4.0 g/kg/day) for 5 days before cecal ligation and puncture (CLP) challenge. After 24 h, the pathological morphology of lung tissue and the biochemical parameters in bronchoalveolar lavage fluid (BALF) were determined by H&E staining and enzyme-linked immunosorbent assay (ELISA). Furthermore, the total protein content and lactate dehydrogenase (LDH) level of BALF, as well as the oxidative biomarkers (malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD)) were evaluated in the lung homogenates by ELISA assay. The levels of pro-inflammatory cytokines, TNFα, IL-1β, and IL-6, in lung tissue were measured by qRT-PCR or ELISA. Finally, key proteins in Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway in lung tissue were evaluated by western blot. Results: CLP challenge induced abnormal changes in the histological structures of lung tissue, lung wet-to-dry weight (W/D) ratio, protein content and LDH levels of BALF, which were remarkably reversed by AEACD. In addition, AEACD decreased MDA levels, and increased GSH levels and SOD activity in the lung tissue of CLP–treated mice (p < 0.05). Furthermore, AEACD attenuated the CLP challengeinduced upregulation of TNFα, IL-1β, and IL-6. Finally, AEACD inactivated TLR4/NF-κB pathway by upregulating IκBα and downregulating TLR4 and phosphorylated-p65 levels. Conclusion: AEACD administration protects mice against sepsis-induced ALI through the regulation of oxidative stress and inflammatory responses in lung tissues. The underlying mechanism occurs by inhibiting TLR4/NF-κB signaling pathway. Keywords: Aconitum carmichaelii Debeaux, Acute lung injury, Sepsis, TLR4, NF-κB