鼠李糖乳杆菌调节ETEC腹泻仔猪肠黏膜Th17和Treg细胞应答的分子机制

Piglet diarrhea seriously threatens the healthy development to pig industry. Enterotoxigenic Escherichia coli (ETEC) is a major cause of weanling piglet diarrhea induced by Escherichia coli. Dose-dependent amelioration of ETEC-induced diarrhea in piglets by Lactobacillus rhamnosus GG (LGG), which might be closely related with regulating host immune responses, especially the differentiation of CD4+ T lymphocytes. Forkhead box P3 (FOXP3)+ Treg cells and FOXP3- IL-10-secreting Treg type 1 cells (Tr1-like cells) are particularly important in the intestine. In the present study, the models of ETEC-induced weanling piglet diarrhea (in vivo assay) and cell research (in vitro assay) will be established. Our objectives are to reveal the molecular mechanisms of LGG regulating Th17 and Treg (regulatory T) cell responses in the intestinal mucosa of piglets via: 1) evaluating effects of LGG on Toll-like receptors (TLRs)/Nod-like receptors (NLRs), cytokines, transcription factors (STAT, FOXP3, FOXO1) and IgA, subsets of innate lymphoid cells (ILCs) and CD4+ T cells in piglets orally infected with ETEC. 2) examining whether thymic stromal lymphopoietin (TSLP), TGF-beta and IL-10 could induce the differentiation of CD4+ T cells into FOXP3+ Treg cells and Tr1-like cells and regulate Th17 response. 3) understanding the interactions of LGG with ETEC, and host cells (ie intestinal epithelial cells and dendritic cells). 4) investigating whether LGG inhibits the ETEC-induced nuclear factor-kappaB activation. The study can provide scientific basis for rational use of LGG and effective prevention of piglet diarrhea in pig industry.

仔猪腹泻严重威胁养猪业的健康发展，肠毒性大肠杆菌(ETEC)在断奶仔猪腹泻中占重要地位。鼠李糖乳杆菌（LGG）剂量依赖改善仔猪ETEC腹泻，这可能与其对宿主免疫应答调控尤其CD4+ T细胞分化密切相关。本项目拟建立断奶仔猪ETEC腹泻模型，并结合运用肠上皮细胞和树突状细胞体外模型，旨在通过研究：1. LGG对仔猪肠黏膜TLR和NLR表达，细胞因子、转录因子和IgA水平，肠黏膜先天淋巴样细胞、T细胞亚群分布及其应答的影响；2. 胸腺基质淋巴细胞生成素、TGF-beta和IL-10在促使T细胞向FOXP3+ Treg或Tr1-like方向分化以及调节Th17应答中的作用；3. LGG与ETEC、宿主细胞间的互作；4. LGG是否抑制了ETEC介导的NFkappaB活化。揭示LGG调节仔猪肠黏膜Th17和Treg细胞应答的分子机制，为养猪业合理利用LGG并有效防治仔猪腹泻提供科学依据。

仔猪腹泻严重威胁养猪业的健康发展，肠毒性大肠杆菌(ETEC)在断奶仔猪腹泻中占重要地位。鼠李糖乳杆菌（LGG）剂量依赖改善仔猪ETEC腹泻，这可能与其对宿主免疫应答调控尤其CD4+ T细胞分化密切相关。鼠李糖乳杆菌（LGG）能有效降低ETEC导致的仔猪腹泻率，但LGG对仔猪肠黏膜TLR和NLR表达，细胞因子、转录因子和IgA水平，肠黏膜先天淋巴样细胞、T细胞亚群分布及其应答的影响并不清楚。本项目通过建立断奶仔猪ETEC腹泻模型，并结合运用肠上皮细胞和树突状细胞体外模型，对以下内容进行了研究：1. LGG对仔猪肠黏膜TLR和NLR表达，细胞因子、转录因子和IgA水平，肠黏膜先天淋巴样细胞、T细胞亚群分布及其应答的影响；2. 胸腺基质淋巴细胞生成素、TGF-β和IL-10在促使T细胞向FOXP3+ Treg或Tr1-like方向分化以及调节Th17应答中的作用；3. LGG与ETEC、宿主细胞间的互作；4. LGG是否抑制了ETEC介导的NF-kB活化。揭示了LGG调节仔猪肠黏膜Th17和Treg细胞应答的分子机制，为养猪业合理利用LGG并有效防治仔猪腹泻提供科学依据。目前，本项目相关研究工作已发表SCI论文9篇。