Nanovesicles From Lactobacillus johnsonii N6.2 Reduce Apoptosis in Human Beta Cells by Promoting AHR Translocation and IL10 Secretion.

L. johnsonii N6.2 releases nano-sized vesicles (NVs) with distinct protein and lipid contents. We hypothesized that these NVs play a central role in the delivery of bioactive molecules that may act as mechanistic effectors in immune modulation. In this report, we observed that addition of NVs to the human pancreatic cell line βlox5 reduced cytokine-induced apoptosis. Through RNAseq analyses, increased expression of CYP1A1, CYP1B1, AHRR, and TIPARP genes in the aryl hydrocarbon receptor (AHR) pathways were found to be significantly induced in presence of NVs. AHR nuclear translocation was confirmed by confocal microscopy. The role of NVs on beta cell function was further evaluated using primary human pancreatic islets. It was found that NVs significantly increased insulin secretion in presence of high glucose concentrations. These increases positively correlated with increased GLUT6 and SREBF1 mRNA and coincided with reduced oxidative stress markers. Furthermore, incubation of NVs with THP-1 macrophages promoted the M2 tolerogenic phenotype through STAT3 activation, expression of AHR-dependent genes and secretion of IL10. Altogether, our findings indicate that bacterial NVs have the potential to modulate glucose homeostasis in the host by directly affecting insulin secretion by islets and through the induction of a tolerogenic immune phenotype.

约氏乳杆菌N6.2会释放出具有独特蛋白质和脂质成分的纳米级囊泡（NVs）。我们假设这些NVs在生物活性分子的传递中发挥核心作用，而这些生物活性分子可能作为免疫调节的机制效应物。在本报告中，我们观察到，将NVs添加到人胰腺细胞系βlox5中可减少细胞因子诱导的细胞凋亡。通过RNA测序分析发现，在NVs存在的情况下，芳烃受体（AHR）通路中的CYP1A1、CYP1B1、AHRR和TIPARP基因的表达显著上调。共聚焦显微镜证实了AHR的核转位。我们还利用原代人胰岛进一步评估了NVs对β细胞功能的作用。结果发现，在高葡萄糖浓度下，NVs显著增加了胰岛素分泌。这些增加与GLUT6和SREBF1信使核糖核酸（mRNA）的增加呈正相关，且与氧化应激标志物的减少同时出现。此外，将NVs与THP - 1巨噬细胞共同孵育，通过激活信号转导及转录激活因子3（STAT3）、诱导AHR依赖基因的表达以及白细胞介素10（IL10）的分泌，促进了M2致耐受性表型的形成。总之，我们的研究结果表明，细菌来源的NVs有潜力通过直接影响胰岛的胰岛素分泌以及诱导致耐受性免疫表型，来调节宿主体内的葡萄糖稳态。