Baicalin Decreases the LPS-Induced Intestine Inflammatory Responses by ROS/p-ERK/p-P38 Signal Pathways In Vivo and In Vitro

Abstract

Background: This study aimed to investigate the role of ROS/MAPK signaling pathways and the effects of baicalin in LPS-induced inflammatory responses in mice and porcine intestinal epithelial cells (IPEC-J2). Methods: In vivo, 18 male C57BL/6J mice were randomly divided into three groups (n = 6): control, LPS (3.5 mg/kg LPS administered intraperitoneally [ip] on day 7), and baicalin (200 mg/kg orally for 7 days, with LPS ip on day 7). On day 8, mice were sacrificed, and jejunal tissues were collected for H&E staining. ROS levels in serum and cytokine protein expressions (TNF-α and IL-6) in the jejunum were measured via ELISA, while intestinal MAPK proteins were analyzed using Western blotting. In vitro, the study involved two experimental setups: NAC (a ROS scavenger) and baicalin. For the NAC experiment, IPEC-J2 cells were divided into three groups: control, LPS, and NAC. In the LPS group, cells were treated with LPS (40 μg/mL) for 1 h. In the NAC group, cells were pretreated with NAC prior to LPS exposure. For the baicalin experiment, IPEC-J2 cells were divided into five groups: control, LPS, and baicalin at low (10 μM), medium (20 μM), and high (40 μM) doses. Cells were pretreated with baicalin for 24 h before LPS exposure. ROS/LDH levels and cytokine expressions in the supernatant were determined via ELISA, and MAPK protein expressions were assessed using Western blotting. Results: In vivo, LPS-induced oxidative stress and inflammatory responses in the intestine, reduced the villus height-to-crypt ratio, and significantly increased protein expressions of p-ERK, p-P38, JNK, and p-JNK (p < 0.05). Baicalin treatment significantly inhibited serum ROS levels (p < 0.01), reduced jejunal cytokine expressions (TNF-α and IL-6, p < 0.05), improved intestinal structural damage, and decreased p-ERK, p-P38, and p-JNK protein expressions (p < 0.05). In vitro, NAC significantly reduced ROS levels (p < 0.01), cytokine expressions (TNF-α and IL-6), and MAPK activation (ERK, JNK, P38, and their phosphorylated forms, p < 0.05). Baicalin also significantly decreased ROS (p < 0.05), TNF-α (p < 0.05), IL-6 (p < 0.05), and MAPK protein expressions (ERK, p-ERK, and p-P38, p < 0.05). Molecular docking demonstrated that baicalin effectively bound to ERK and P38 proteins. Conclusions: Baicalin mitigated LPS-induced inflammatory responses via the ROS/p-ERK/p-P38 signaling pathway in vivo and in vitro.

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