Goblet Cell Secretion and Antigen Delivery

描述（由申请人提供）：肠上皮是一种动态屏障，可保护身体免受腔体内大量细菌的侵害。然而，存在多种机制，允许腔采样，以促进耐受性和防止对无害的饮食抗原的炎症反应。通过使用双光子（2 p）显微镜，杯状细胞（GC）最近被确定为可溶性抗原的CD 103+树突状细胞驻留在绒毛固有层的传递机制，表明这种机制促进耐受性免疫应答。我们将这些抗原递送细胞称为杯状细胞相关抗原传代（GAP）。GAP的形成似乎与钙介导的复合胞吐作用（CE）期间响应于乙酰胆碱通过毒蕈碱受体（mAchR）释放GC产物有关。在稳定状态下，CE和GAP形成仅发生在特定病原体自由圈养的成年小鼠（SPF）的小肠中，而不是结肠中。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转导改变的Myd 88-/-小鼠的结肠中观察到GAP。在这个提议中，我们假设GAP形成和CE通过刺激GC上的mAchR而发生，并且该途径被TLR和NOD信号传导抑制以响应增加的微生物生长或病原性感染。我们建议阐明mAchR信号如何导致CE和TLR和NOD交叉信号级联的细节。通过这项资助，我们希望更好地了解GAP如何提供抗原以维持致耐受性免疫反应。

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.