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

Abstract

<i>Gelsemium elegans Benth.</i> (<i>G. elegans</i>), 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 <i>G. elegans</i> 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-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math>, IL-6, IL-1<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math>, NO, iNOS, and COX-2, which was closely connected with the inhibition of NF-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi></mml:math>B pathway for the decrease of phosphorylation of I<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi></mml:math>B<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> and NF-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi></mml:math>B 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-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi></mml:math>B signaling pathway and preventing intestinal barrier dysfunction.