Department of Critical Care Medicine, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
Department of Oncology, The Yan'an Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
PeerJ. 2024 Sep 26;12:e18185. doi: 10.7717/peerj.18185. eCollection 2024.
The severity of acute gastrointestinal injury (AGI) is a critical determinant of survival in sepsis. However, there is no specifically interventional management for gastrointestinal dysfunction. Toll-like Receptor 4 (TLR4) is an important contributor to sepsis-induced multiple organ dysfunction syndrome. So, we investigated the effect of TLR4 on leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) + cells and goblet cells and its potential mechanism.
A cecal ligation and puncture (CLP) model reflecting the development of clinical sepsis was developed. Tak-242, a TLR4 inhibitor, was administered to septic rats at a dose of 3 mg/kg via intraperitoneal injection. Immunohistochemistry was performed to detect TLR4 and Lgr5+ cells. AB-PAS staining was performed to detect goblet cells. MUC1 and MUC2 secreted by goblet cells, biomarkers of endoplasmic reticulum (ER) stress and inflammatory cytokines in the intestine were detected by western blotting and real-time PCR.
We found that the upregulation of the TLR4/NF-κB signaling pathway activated intestinal inflammatory response in sepsis. Meanwhile, the structure of intestinal mucosa was destroyed, Lgr5+ cells and goblet cells count were significantly reduced, and the secretory function of goblet cells also decreased. Further studies have found that TLR4 increased the levels of activating transcription factor-6 (ATF6), XBP1, ER chaperone (Bip) and CHOP, but did not activate the protein kinase RNA (PKR)-like ER kinase (P-PERK).
We concluded that the inhibition of TLR4/NF-κB signaling pathway can reduce intestinal inflammatory response, protect intestinal mucosa, protect Lgr5+ cells, goblet cells and relieve ER stress. Our findings suggest that Tak-242 protects Lgr5+ cells and goblet cells after sepsis, partly may be through the suppression of ER stress. Thus, inhibition of TLR4-mediated ER stress may be a promising therapy of septic AGI.
急性胃肠损伤（AGI）的严重程度是脓毒症患者生存的关键决定因素。然而，目前尚无针对胃肠功能障碍的特异性干预治疗方法。Toll 样受体 4（TLR4）是导致脓毒症引起的多器官功能障碍综合征的重要因素。因此，我们研究了 TLR4 对富含亮氨酸重复序列的 G 蛋白偶联受体 5（Lgr5）+细胞和杯状细胞的影响及其潜在机制。
建立了反映临床脓毒症发展的盲肠结扎穿孔（CLP）模型。采用腹腔注射 TLR4 抑制剂 Tak-242（剂量为 3mg/kg）处理脓毒症大鼠。采用免疫组织化学法检测 TLR4 和 Lgr5+细胞。AB-PAS 染色法检测杯状细胞。采用 Western blot 和实时 PCR 检测杯状细胞分泌的 MUC1 和 MUC2 以及肠内内质网（ER）应激和炎症细胞因子的生物标志物。
我们发现 TLR4/NF-κB 信号通路的上调激活了脓毒症中的肠道炎症反应。同时，肠黏膜结构被破坏，Lgr5+细胞和杯状细胞数量明显减少，杯状细胞的分泌功能也下降。进一步的研究发现，TLR4 增加了激活转录因子 6（ATF6）、X 盒结合蛋白 1（XBP1）、内质网伴侣（Bip）和 C/EBP 同源蛋白（CHOP）的水平，但没有激活蛋白激酶 RNA（PKR）样内质网激酶（P-PERK）。
我们得出结论，抑制 TLR4/NF-κB 信号通路可以减轻肠道炎症反应，保护肠黏膜，保护 Lgr5+细胞、杯状细胞，缓解 ER 应激。我们的研究结果表明，Tak-242 可保护脓毒症后 Lgr5+细胞和杯状细胞，部分可能是通过抑制 ER 应激。因此，抑制 TLR4 介导的 ER 应激可能是脓毒症 AGI 的一种有前途的治疗方法。
