Abstract：
BACKGROUND: The Bacillus-derived cyclic lipopeptides (surfactin, iturin, and fengycin) form potent Heterogeneous Lipopeptide Micelle (HeLM) complexes. HeLM is a small molecule that has been shown to have immunomodulatory effects. However, how HeLM regulates inflammation is not clear, moreover its application to Inflammatory Bowel Disease (IBD), specifically Ulcerative Colitis (UC), has not been tested before.
OBJECTIVE: To use a murine model of IBD and determine the effects of HeLM and related molecular mechanisms of action.
METHODS: Colitis was induced in mice by administration of 4% Dextran Sodium Sulfate. Three preparations were tested against negative and positive controls: Purified HeLM, the wild-type strain that produces it, and an isogenic mutant that does not produce HeLM. Clinical, biochemical, and histological scoring systems were used to assess the severity of colitis. RT-qPCR and cell cultures were used to determine the levels of molecular signaling. Fecal samples were processed for metagenomic analysis.
RESULTS: Purified HeLM, and the wild-type strain, significantly decreased the severity of colitis as determined by the disease activity index (DAI), mouse colitis histology index (MCHI), fecal calprotectin, and colonic length. This effect was not seen in the mutant. HeLM was found to be an agonist to TLR-2, seemingly activating the Toll-Like Receptor 2/IL-10 pathway, with subsequent downregulation of inflammatory cytokines (TNF-α, IL-1β, and IL-6). At higher concentrations HeLM inhibited lipopolysaccharide ligands from activating TLR-4. The reduction in colitis was not due to microbiome modulation, as had previously been hypothesized.
CONCLUSIONS: Our results indicate that HeLM ameliorates colitis by TLR-2-induced IL-10 production and possibly via the inhibition of lipopolysaccharide.
OBJECTIVE: To use a murine model of IBD and determine the effects of HeLM and related molecular mechanisms of action.
METHODS: Colitis was induced in mice by administration of 4% Dextran Sodium Sulfate. Three preparations were tested against negative and positive controls: Purified HeLM, the wild-type strain that produces it, and an isogenic mutant that does not produce HeLM. Clinical, biochemical, and histological scoring systems were used to assess the severity of colitis. RT-qPCR and cell cultures were used to determine the levels of molecular signaling. Fecal samples were processed for metagenomic analysis.
RESULTS: Purified HeLM, and the wild-type strain, significantly decreased the severity of colitis as determined by the disease activity index (DAI), mouse colitis histology index (MCHI), fecal calprotectin, and colonic length. This effect was not seen in the mutant. HeLM was found to be an agonist to TLR-2, seemingly activating the Toll-Like Receptor 2/IL-10 pathway, with subsequent downregulation of inflammatory cytokines (TNF-α, IL-1β, and IL-6). At higher concentrations HeLM inhibited lipopolysaccharide ligands from activating TLR-4. The reduction in colitis was not due to microbiome modulation, as had previously been hypothesized.
CONCLUSIONS: Our results indicate that HeLM ameliorates colitis by TLR-2-induced IL-10 production and possibly via the inhibition of lipopolysaccharide.
摘要：
背景：芽孢杆菌衍生的环状脂肽（表面活性素，iturin,和fengycin）形成有效的异质脂肽胶束（HeLM）复合物。HeLM是一种小分子，已被证明具有免疫调节作用。然而,HeLM如何调节炎症尚不清楚，此外，它在炎症性肠病（IBD）中的应用，特别是溃疡性结肠炎（UC），以前没有测试过。
目的：建立IBD小鼠模型，研究HeLM的作用及其分子作用机制。
方法:通过施用4%葡聚糖硫酸钠在小鼠中诱导结肠炎。针对阴性和阳性对照测试了三种制剂：纯化的HeLM，产生它的野生型菌株，和一个不产生HeLM的等基因突变体。临床,生物化学，和组织学评分系统用于评估结肠炎的严重程度。使用RT-qPCR和细胞培养物来确定分子信号的水平。处理粪便样品用于宏基因组分析。
结果：纯化的HeLM，和野生型菌株，由疾病活动指数（DAI）确定的结肠炎的严重程度显着降低，小鼠结肠炎组织学指数（MCHI），粪便钙卫蛋白,和结肠长度。在突变体中未观察到这种效果。发现HeLM是TLR-2的激动剂，似乎激活Toll样受体2/IL-10途径，随后下调炎症细胞因子(TNF-α，IL-1β,和IL-6）。在较高浓度下,HLM抑制脂多糖配体激活TLR-4。结肠炎的减少不是由于微生物组调节，正如之前所假设的那样。
结论：我们的结果表明，HeLM通过TLR-2诱导的IL-10产生和可能通过抑制脂多糖改善结肠炎。
目的：建立IBD小鼠模型，研究HeLM的作用及其分子作用机制。
方法:通过施用4%葡聚糖硫酸钠在小鼠中诱导结肠炎。针对阴性和阳性对照测试了三种制剂：纯化的HeLM，产生它的野生型菌株，和一个不产生HeLM的等基因突变体。临床,生物化学，和组织学评分系统用于评估结肠炎的严重程度。使用RT-qPCR和细胞培养物来确定分子信号的水平。处理粪便样品用于宏基因组分析。
结果：纯化的HeLM，和野生型菌株，由疾病活动指数（DAI）确定的结肠炎的严重程度显着降低，小鼠结肠炎组织学指数（MCHI），粪便钙卫蛋白,和结肠长度。在突变体中未观察到这种效果。发现HeLM是TLR-2的激动剂，似乎激活Toll样受体2/IL-10途径，随后下调炎症细胞因子(TNF-α，IL-1β,和IL-6）。在较高浓度下,HLM抑制脂多糖配体激活TLR-4。结肠炎的减少不是由于微生物组调节，正如之前所假设的那样。
结论：我们的结果表明，HeLM通过TLR-2诱导的IL-10产生和可能通过抑制脂多糖改善结肠炎。
