Functional analysis of the molecular cross-talk between methanogenic archaea and the human immune system

虽然微生物群在人类健康和疾病中的功能重要性已在许多研究和报告中得到证实，但甲烷古菌作为肠道微生物群的稳定部分，在解决和阐明微生物组成员与免疫系统组分之间的相互依赖性的报告中经常被忽视。在之前的资助期间，我们进行了人类免疫细胞对甲烷古菌的炎症反应的第一次全面研究，这表明Methanosphaera stadtmanae能够诱导比Methanobrevibacter smithii明显更高的炎症细胞因子反应。根据我们第一个融资期的结果，我们假设M。Stadtmanae具有促进人肠道中的炎症过程的潜力，因此可能是迄今为止被忽视的人肠道病理状况的贡献者。相比之下，M。Smithii似乎已经进化出抑制肠道炎症过程的机制，而且可能在人类肠道生态系统中具有免疫调节作用。我们获得的数据进一步有力地证明了人类中存在一种特定的古细菌相关模式识别受体。最后，我们证明了甲烷古菌易于产生抗菌肽（AMP）样细菌的溶解作用，并且能够通过人类免疫细胞调节其释放。因此，古细菌菌株可以影响整体人类免疫稳态到与细菌相当的程度。因此，我们现在的目标是（1）鉴定所涉及的甲烷古菌相关分子模式以及参与信号传导过程的相应人类模式识别受体和介质，（2）通过比较甲烷古菌与人类上皮细胞和外周血细胞接触后的转录组变化来分析甲烷古菌在人类肠道内的免疫调节过程，（3）评估M.通过监测健康和患病个体的肠活检和粪便样品中的总细胞数，阐明M. stadtmanae和M. smithii对人细胞分泌的AMP和细胞因子的影响;（5）分析M. smithii和M. Stadtmanae在不同条件下在人上皮细胞上形成生物膜的能力，这些研究将在分子和免疫学水平上扩展我们的最新发现，并评估M. stadtmanae与人类肠道中的病理条件相关，因此将强调甲烷古菌作为人类微生物群的一部分的功能重要性。

Although the functional importance of the microbiota in human s health and disease has been confirmed in numerous studies and reports, methanoarchaea as a stable part of the gut microbiota have frequently been overlooked in reports addressing and elucidating the interdependency between members of the microbiome and components of the immune system. During the previous funding period we performed the first comprehensive study of the inflammatory response of human immune cells to methanoarchaea, which demonstrated that Methanosphaera stadtmanae is capable to induce a markedly higher inflammatory cytokine response than Methanobrevibacter smithii. Based on our results of the first funding period we hypothesize that M. stadtmanae has the potential to promote inflammatory processes in the human gut and may thus represent a so far overlooked contributor to pathological conditions in the human gut. In contrast, M. smithii appears to have evolved mechanism to suppress inflammatory processes in the gut and moreover might have immunmodulatory influence in the human gut ecosystem. Our data obtained further strongly argue for the presence of a specific archaea-associated pattern recognition receptor in humans. Finally, we demonstrated that methanoarchaea are prone to the lytic effects of antimicrobial peptides (AMPs) like bacteria and are capable to regulate their release by human immune cells. Accordingly, archaeal strains may influence the overall human immune homeostasis to comparable extents as has been shown for bacteria. Consequently we now aim to (1) identify the involved methanoarchaeal-associated molecular patterns as well as the respective human pattern-recognition receptors and mediators involved in signaling processes, (2) analyze the immunomodulating processes of methanoarchaea within the human intestine by comparing transcriptome changes upon contact of methanoarchaea with human epithelial and peripheral blood cells, (3) evaluate a potential correlation between the presence of M. stadtmanae and inflammatory gut diseases by monitoring the total cell numbers in intestinal biopsy and stool samples of healthy and diseased individuals, (4) elucidating the cellular stress responses of M. stadtmanae and M. smithii to AMPs and cytokines released by human cells, and (5) analyze the ability of M. smithii and M. stadtmanae to form biofilms on human epithelia under various conditions.Generally, these studies will expand our recent discoveries on the molecular and immunological level and evaluate the hypothesized contribution of M. stadtmanae to pathological conditions in the human gut and thus will emphasize the functional importance of methanoarchaea as a part of the human microbiota.