Koumine Alleviates Lipopolysaccharide-Induced Intestinal Barrier Dysfunction in IPEC-J2 Cells by Regulating Nrf2/NF-κB Pathway.

Gelsemium elegans Benth. (G. elegans), a traditional Chinese medicine, has great potential as an effective growth promoter in animals, however, the mechanism of its actin remains unclear. Here, we evaluated the protective effects of koumine extract from G. elegans against lipopolysaccharide (LPS)-induced intestinal barrier dysfunction in IPEC-J2 cells through alleviation of inflammation and oxidative stress. MTT and LDH assays revealed that koumine significantly reduced LPS cytotoxicity. Transepithelial electrical resistance (TEER) and cell monolayer permeability assays showed that koumine treatment attenuated the LPS-induced intestinal barrier dysfunction with no particularly different effects in tight junction proteins such as ZO-1, claudin-1, and occludin. LPS-triggered inflammatory response was also suppressed by koumine, as evidenced by the downregulated inflammatory factors, including TNF-α, IL-6, IL-1ß, NO, iNOS, and COX-2, which was closely connected with the inhibition of NF-κB pathway for the decrease of phosphorylation of IκBα and NF-κB and nuclear translocation of p-p65. Amount of reactive oxygen species (ROS) and MDA induced by LPS was also reduced by koumine through activation of Nrf2 pathway, and increased in the levels of Nrf2 and HO-1 degradation of keap-1 to promote anti-oxidants, including superoxide dismutase (SOD) and catalase (CAT). To summarize, koumine-reduced the oxidative stress and inflammatory reaction triggered by LPS through regulation of the Nrf2/NF-κB signaling pathway and preventing intestinal barrier dysfunction.

A Potential Mechanism for the Anti-Apoptotic Property of Koumine Involving Mitochondrial Pathway in LPS-Mediated RAW 264.7 Macrophages.

Koumine is a kind of alkaloid extracted from Gelsemium elegans (G. elegans). Benth, which has shown promise as an anti-tumor, anxiolytic, and analgesic agent. In our present study, the effect of koumine on lipopolysaccharide (LPS)-mediated RAW 264.7 cell apoptosis was evaluated. MTT assays showed that koumine obviously increased cell viability in LPS-mediated RAW 264.7 macrophages. Preincubation with koumine ameliorated LPS-medicated apoptosis by decreasing reactive oxygen species (ROS) production, which resulted in a significant decrease in the levels of nitric oxide (NO) and inducible nitric oxide synthase (iNOS). In addition, koumine-pretreated RAW 264.7 macrophages exhibited reduction of LPS-induced levels of TNF-α, IL-1ß, and IL-6 mRNA. Furthermore, pretreatment with koumine suppressed LPS-mediated p53 activation, loss of mitochondrial membrane potential, caspase-3 activation, decrease of Bcl-2 expression, and elevation of Bax and caspase-3 expressions, suggesting that koumine might act directly on RAW 264.7 cells to inhibit LPS-induced apoptosis. It seems as though the mechanism that koumine possesses is the anti-apoptotic effect mediated by suppressing production of ROS, activation of p53, and mitochondrial apoptotic pathways in RAW 264 cells. Koumine could potentially serve as a protective effect against LPS-induced apoptosis.