Immunoregulatory Defects In Inflammatory Bowel Disease

炎症性肠病的免疫调节缺陷

• 批准号: 8336042
• 负责人: Warren Strober
• 金额: $ 65.51万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8336042
• 关键词: Antigens; Area; Autoantigens; Autoimmune Diseases; B-Lymphocytes; Binding; Blood Circulation; CD4 Positive T Lymphocytes; Cell Count; Cells; Characteristics; Colitis; Defect; Diffuse; Disease; Epithelial Cells; Exhibits; Exotoxins; Family; Feedback; Glycolipids; Goals; Human; Immunologics; Individual; Inflammation; Inflammatory Bowel Diseases; Interleukin-13; Interleukin-4; KLRB1 gene; Lamina Propria; Lesion; Link; Mediating; Minor; Modeling; Mononuclear; Mucous Membrane; Natural Killer Cells; Oxazolone; Pathogenesis; Pathologic; Patients; Population; Production; Pseudomonas; Qualifying; Reporting; Sulfoglycosphingolipids; Surrogate Markers; Tissues; Ulcerative Colitis; Up-Regulation; Ursidae Family; autocrine; cytokine; cytotoxic; cytotoxicity; interleukin-13 receptor; member; peripheral blood; receptor; receptor expression; response

The studies reported here center around two major findings. The first is that the non-invariant NKT cells previously identified in UC are in fact capable of responding to a self-glycolipid, a member of the sulfatide family of NKT cell stimulants. This finding strongly suggests that NKT cells in UC are responding to a self antigen and that UC qualifies as a classical autoimmune disease. The second is that NKT cells in UC bear the IL-13Rα2 receptor that: 1) is up-regulated by sulfatide stimulation; and 2) is the receptor through which IL-13 interacts with NKT cells to induce enhancement of NKT cell cytotoxicity in an autocrine fashion. This receptor is therefore critical to NKT cell-mediated pathologic effects. The response of UC lamina propria NKT cells to sulfatide was shown in three ways: it induced NKT cell cytokine production, induced NKT cell cytotoxic function and augmented NKT cell expression of the IL-13Rα2 receptor, but not the IL-13Rα1 receptor. These findings were consistent with and help explain our previous observation that NKT cells in UC respond to stimulation by a B cell stably expressing high levels of CD1d in the absence of exogenous antigen, since in the latter case it is possible that the CD1d on the B cell was loaded with an endogenous self-glycolipid that cross-react with sulfatide. The responses elicited by the lyso-sulfatide are also consistent with our previous studies in that they showed that NKT cells in UC can be stimulated by the aforementioned transfected B cell to mediate an atypical Th2 response characterized by production of IL-13 but not IL-4 (or various Th1 cytokines) and to exhibit cytotoxicity for epithelial cells ( ). A totally new observation obtained from the present study was that, as eluded to above, sulfatide upregulation of the IL-13Rα2 receptor not only results in enhancement of the number of cells bearing the receptor, but perhaps more importantly to a great increase in the intensity of receptor expression on individual cells. This observation implies that stimulation of NKT cells by sulfatide leads to a positive feedback circuit in which induction of cytotoxicity by TCR-recognition of antigen can ultimately be enhanced by increased expression of a receptor that also mediates cytotoxity. The observation that sulfatide stimulation of NKT cells results in upregulation of the IL-13Rα2 but not the IL-13Rα1 prompted us to determine if this receptor could server as a surrogate marker of NKT cells in UC. To investigate this possibility we turned to the oxazolone-colitis model, a colitis driven by IL-13 and NKT cells, and showed that administration of IL-13 linked to pseudomonas exotoxin (IL-13-PE) ablates oxazolone-colitis by targeting and eliminating NKT cells and its IL-13 secretion. Since it is well documented that the cytotoxic effect of IL-13-PE depends on binding to the IL-13Rα2 receptor ( ), this study provided strong evidence that NKT cells involved in a UC type inflammation bear this receptor. Additional studies showing that invariant TCR-bearing cells detected with α-GalCer-tetramer also bear IL-13Rα2 supported this conclusion. In parallel studies of humans with UC we first showed that circulating CD4+ T cells in patients have easily detectable cells bearing the IL-13Rα2 whereas patients with CD have barely detectable levels. Furthermore, depletion of cells with IL-13-PE led to co-depletion of receptor-bearing cells and IL-13-producing cells. These findings relating to IL-13Rα2-bearing cells in the circulation of UC patients presaged findings in the inflamed tissues of patients. In the latter case, we found that the majority of lesional lamina propria mononuclear cells (approximately 70%) bear IL-13Rα2 whereas the percentage of cells bearing the IL-13Rα1 receptor was low. In addition, the receptor-bearing cells also bear the NKT cell marker, CD161 and most (if not all) are IL-13-producing cells. Finally, we showed that IL-13-PE depletion of UC lamina propria cells led to greatly reduced IL-13 production and cytotoxic activity, as in the case of circulating cells, again validating the concept that IL-13Rα2 is an NKT cell marker in UC. These studies provide unequivocal evidence that IL-13-producing cells bearing NKT cell markers are more than a minor sub-population of cells in actively inflamed UC mucosa there are no proper lesions in UC as the disease is diffuse; on the contrary, they make up the majority of cells in the inflamed areas. This fact greatly increases the likelihood that UC is primarily due to these cells and the IL-13 they produce.

这里报告的研究围绕着两个主要发现。 首先，以前在UC中鉴定的非恒定NKT细胞实际上能够对自身糖脂（NKT细胞刺激剂的硫苷脂家族的成员）作出反应。 这一发现强烈表明，UC中的NKT细胞对自身抗原有反应，并且UC有资格成为经典的自身免疫性疾病。 第二个是UC中的NKT细胞携带IL-13 Rα 2受体，其：1）通过硫苷脂刺激上调;和2）是IL-13与NKT细胞相互作用以自分泌方式诱导NKT细胞毒性增强的受体。 因此，这种受体对NKT细胞介导的病理效应至关重要。 UC固有层NKT细胞对硫苷脂的反应表现在三个方面：它诱导NKT细胞产生细胞因子，诱导NKT细胞的细胞毒性功能和增加NKT细胞表达IL-13 R 2受体，但不增加IL-13 R 1受体。这些发现与我们之前的观察结果一致，并有助于解释我们之前的观察结果，即在不存在外源性抗原的情况下，UC中的NKT细胞对稳定表达高水平CD 1d的B细胞的刺激有反应，因为在后一种情况下，B细胞上的CD 1d可能负载有与硫苷脂交叉反应的内源性自身糖脂。 溶血硫苷脂引起的反应也与我们先前的研究一致，因为它们表明UC中的NKT细胞可被上述转染的B细胞刺激，以介导以产生IL-13而非IL-4（或各种Th 1细胞因子）为特征的非典型Th 2反应，并表现出对上皮细胞的细胞毒性（）。从本研究中获得的一个全新观察结果是，如上所述，IL-13 R 2受体的硫苷脂上调不仅会导致携带该受体的细胞数量增加，而且可能更重要的是会大大增加受体的强度单个细胞上的表达。这一观察结果意味着硫苷脂对NKT细胞的刺激会导致正反馈回路，其中抗原的TCR识别对细胞毒性的诱导最终可以通过增加也介导细胞毒性的受体的表达来增强。 观察到NKT细胞的硫苷脂刺激导致IL-13 R2而不是IL-13 R1的上调，这促使我们确定该受体是否可以作为UC中NKT细胞的替代标记物。为了研究这种可能性，我们转向恶唑酮-结肠炎模型，一种由IL-13和NKT细胞驱动的结肠炎，并显示与假单胞菌外毒素（IL-13-PE）连接的IL-13的施用通过靶向和消除NKT细胞及其IL-13分泌来消除恶唑酮-结肠炎。 由于已充分证明IL-13-PE的细胞毒性作用取决于与IL-13 R 2受体的结合（），因此本研究提供了有力证据，证明UC型炎症中涉及的NKT细胞携带该受体。另外的研究表明，用β-GalCer-四聚体检测到的携带恒定TCR的细胞也携带IL-13 R2支持这一结论。 在患有UC的人的平行研究中，我们首先显示患者中的循环CD 4 + T细胞具有容易检测到的携带IL-13 R2的细胞，而患有CD的患者几乎没有检测到的水平。此外，用IL-13-PE消耗细胞导致携带受体的细胞和产生IL-13的细胞的共消耗。这些与UC患者循环中的IL-13 R2-承载细胞相关的发现预示了患者炎症组织中的发现。 在后一种情况下，我们发现大多数病变固有层单核细胞（约70%）携带IL-13 R 2，而携带IL-13 R 1受体的细胞的百分比很低。 此外，携带受体的细胞还携带NKT细胞标记物CD 161，并且大多数（如果不是全部）是产生IL-13的细胞。 最后，我们表明UC固有层细胞的IL-13-PE消耗导致IL-13产生和细胞毒性活性大大降低，如在循环细胞的情况下，再次验证了IL-13 R2是UC中的NKT细胞标志物的概念。这些研究提供了明确的证据，即携带NKT细胞标志物的IL-13产生细胞不仅仅是活动性炎症UC粘膜中的细胞的次要亚群，因为疾病是弥漫性的，所以UC中没有适当的病变;相反，它们构成了炎症区域中的大部分细胞。 这一事实大大增加了UC主要是由于这些细胞及其产生的IL-13的可能性。