Goblet Cell Secretion and Antigen Delivery

描述(申请人提供)：肠道上皮是一种动态屏障，保护身体免受腔内大量细菌的侵袭。然而，存在多种机制，允许对管腔进行采样，以促进耐受性并防止对无害饮食抗原的炎症反应。通过使用双光子(2P)显微镜，杯状细胞(GC)最近被证实是一种将可溶性抗原运送到位于绒毛固有层的CD103树突状细胞的机制，表明这一机制促进了耐受性免疫反应。我们将这些抗原递送细胞称为杯状细胞相关抗原通道(GAP)。GAP的形成似乎与钙介导的化合物胞吐作用(CE)中GC产物的释放有关，这是通过M受体(MAchR)对乙酰胆碱的反应。在稳定状态下，CE和GAP的形成仅发生在特定病原体放养的成年小鼠(SPF)的小肠，而不是结肠。然而，我们确实观察到了无菌小鼠、新生SPF寄生小鼠和微生物信号改变的MyD88-/-小鼠的结肠间隙。在这个建议中，我们假设GAP和CE的形成是通过刺激GCs上的mAchR来发生的，并且这一途径被TLR和NOD信号抑制，以响应微生物生长增加或病原体感染。我们建议阐明mAchR信号如何导致CE以及TLR和NOD在哪里与信号级联相交的细节。通过这笔赠款，我们希望更好地了解GAP是如何传递抗原以维持耐受性免疫反应的。

DESCRIPTION (provided by applicant): The intestinal epithelium is a dynamic barrier that protects the body from the multitudes of bacteria that reside in the lumen. Yet multiple mechanisms exist allowing sampling of the lumen in order to promote tolerance and prevent inflammatory responses against innocuous dietary antigens. Through the use of two-photon (2p) microscopy, goblet cells (GC) were recently identified as a delivery mechanism for soluble antigen to the CD103+ dendritic cells residing in the villous lamina propria suggesting this mechanism promotes a tolerogenic immune response. We refer to these antigen delivery cells as Goblet Cell Associated Antigen Passages (GAPs). The formation of GAPs appears to be connected to the release of GC products during calcium- mediated compound exocytosis (CE), in response to acetylcholine through muscarinic receptors (mAchR). At steady-state, CE and GAP formation only occurs in the small intestine but not the colon of specific pathogen free-housed adult mice (SPF). However we did observe GAPs in the colon of germfree mice, neonatal SPF-housed mice, and Myd88-/- mice with altered microbial signaling. In this proposal, we hypothesize GAP formation and CE occurs through stimulation of the mAchR on GCs, and that this pathway is inhibited by TLR and NOD signaling in response to increased microbial growth or pathogenic infections. We propose to elucidate the details of how mAchR signaling leads to CE and where TLR and NOD intersect the signaling cascade. Through this grant, we hope to better understand how GAPs deliver antigen for the purpose of maintaining tolerogenic immune responses.