Goblet Cell Secretion and Antigen Delivery

描述（由申请人提供）：肠上皮是一个动态屏障，保护身体免受居住在管腔中的大量细菌的侵害。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针对无害饮食抗原的炎症反应。通过使用双光子显微镜（2p），杯状细胞（GC）最近被确定为可溶性抗原递送到绒毛固有层CD103+树突状细胞的机制，这表明这种机制促进了耐受性免疫反应。我们把这些抗原传递细胞称为杯状细胞相关抗原传代（GAPs）。gap的形成似乎与钙介导的复合胞吐（CE）过程中GC产物的释放有关，这是对乙酰胆碱通过毒蕈碱受体（mAchR）的反应。在稳态下，特定病原体散养成年小鼠（SPF）的CE和GAP只发生在小肠而不发生在结肠。然而，我们确实在无菌小鼠、spf饲养的新生小鼠和微生物信号改变的Myd88-/-小鼠的结肠中观察到了gap。在本研究中，我们假设GAP的形成和CE是通过刺激GCs上的mAchR发生的，并且在微生物生长或致病性感染增加的情况下，这一途径被TLR和NOD信号抑制。我们建议阐明mAchR信号如何导致CE的细节，以及TLR和NOD在信号级联中的相交位置。通过这项资助，我们希望更好地了解GAPs如何递送抗原以维持耐受性免疫反应。

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.