TERTIARY LYMPHOID ORGANS IN TYPE I DIABETES MELLITUS

这项工作的长期目标是了解I型糖尿病的发病机制，重点是阐明炎症和决定因素扩散的机制。需要检验的假设是，局部部位的第三淋巴器官是许多自身免疫性疾病的特征，对IDDM至关重要。在胰岛素启动子控制下转基因淋巴毒素(LTalpha；TNFbeta)的小鼠(RIPLT小鼠)在胰腺和肾脏表达转基因，并在这些部位发生炎症。胰岛炎症和肾炎具有淋巴结(LN)特征，包括T、B细胞分区，抗原提呈细胞(FDC和DC)，具有高内皮微静脉(HEV)形态和抗原特征的血管(MAdCAM-1和Pnad)，以及免疫后分泌特异性Ig G的浆细胞。这个过程被称为淋巴样新器官发生，需要TNFR1，并可能成为LT在发育中作用的模型，因为LT/TNF家族成员缺陷的小鼠在淋巴器官中存在严重缺陷。LTbetaR参与Pnad的表达，并影响三级淋巴器官幼稚细胞的比例。趋化因子(RANTES、MCP-1和IP-10)在RIPLT胰岛中被诱导。当RIPLT小鼠与RIPB7小鼠杂交时，就会发生糖尿病。其具体目的是：1.通过RIPLT小鼠与RIPLT诱导的趋化因子缺乏的小鼠(MCP-1)或经原位杂交证实参与淋巴器官发育和单核细胞运输(BRL-1)的小鼠杂交，鉴定趋化因子在胰岛三级淋巴器官中的作用；2.用β细胞特异性的LT四环素(Dox)诱导系统表征三级淋巴器官的动力学；3.确定胰岛浸润液是否是能够递送内源性(Y-Ae)和外源抗原的功能性淋巴器官；4.确定胰岛渗出的淋巴器官是否是能够对抗原做出反应的功能性淋巴器官；5.发现在LT诱导的糖尿病中是否发生决定簇扩散，以及这一过程是否需要维持第三淋巴器官。这些研究将深入了解炎症性自身免疫中抗原是如何以及在哪里呈现的，集中在确定这一过程的细胞、分子和解剖学要求上。他们也提供了细胞因子诱导淋巴器官发育的机制的洞察力。了解胰岛三级淋巴器官是如何建立和功能的，将有助于确定IDDM的决定性扩散和组织损伤的治疗靶点。

The long term objective of this work is to understand the pathogenesis of Type I diabetes mellitus with an emphasis on elucidating mechanisms of inflammation and determinant spreading. The hypothesis to be tested is that tertiary lymphoid organs at the local site, which are characteristic of many autoimmune diseases, are crucial for IDDM. Mice transgenic for lymphotoxin (LTalpha; TNFbeta) under the control of the insulin promoter (RIPLT mice) express the transgene in the pancreas and kidney and develop inflammation at those sites. The insulitis and nephritis have lymph node (LN) characteristics, including T, B cell compartmentalization, antigen presenting cells (FDC and DC), vessels with the morphologic and antigenic (MAdCAM-1 and PNAd) characteristics of high endothelial venules (HEV), and plasma cells secreting specific IgG after immunization. This process, termed lymphoid neo-organogenesis, requires TNFR1 and may be a model for LT's role in development since mice deficient in members of the LT/TNF family have profound defects in lymphoid organs. LTbetaR contributes to PNAd expression and influences the ratio of naive cells in the tertiary lymphoid organ. Chemokines (RANTES, MCP-1, and IP-10) are induced in RIPLT islets. When RIPLT mice are crossed to RIPB7 mice, diabetes occurs. The specific aims are to: 1. Identify the role of chemokines in islet tertiary lymphoid organs by crossing RIPLT mice with mice deficient in chemokines induced in RIPLT islets (MCP-1) or identified to be involved in lymphoid organ development and mononuclear trafficking (BRL-1) and by in situ hybridization; 2. Characterize the kinetics of tertiary lymphoid organs with a beta cell specific LT tetracycline (Dox) inducible system; 3. Determine whether the islet infiltrate is a functional lymphoid organ capable of presenting endogenous (Y-Ae) and exogenous antigen; 4. Determine whether the islet infiltrate is a functional lymphoid organ capable of responding to antigen; 5. Discover whether determinant spreading occurs in LT-induced diabetes and if maintenance of a tertiary lymphoid organ is required for this process. These studies which will provide insight into how and where antigens are presented in inflammatory autoimmunity concentrate on identifying cellular, molecular, and anatomic requirements for this process. They also provide insight into the mechanism of cytokine induction of lymphoid organs in development. Understanding how islet tertiary lymphoid organs are established and function will allow identification of therapeutic targets for determinant spreading and tissue damage in IDDM.