Tertiary lymphoid neogenesis in human lupus nephritis

描述（由申请人提供）：SLE最常见的严重表现是狼疮肾炎（LN）。在病理学上，狼疮肾炎（LN）的特点是免疫复合物沉积和肾小球和小管间质炎症，如果不及时治疗，可导致瘢痕和不可逆的器官衰竭。在LN的病理表现中，肾小球肾炎（glomerulonephritis， GN）是研究得最好的，也是自身免疫性疾病小鼠模型中最常复制的特征。然而，小管间质炎症也是LN的常见特征，它有助于整体疾病活动性并决定长期预后。无数的研究表明，GN是由于B细胞耐受性的全身性破坏和免疫复合物的局部沉积，这些复合物含有与普遍存在的自身抗原反应的抗体。然而，SLE小管间质疾病的发病机制尚不清楚。在这项拨款申请中，我们证明在超过一半的患者中，小管间质炎症浸润组织成边界明确的T:B细胞聚集体或含有滤泡树突状细胞的生发中心（GCs）。使用激光捕获显微镜结合RT-PCR对原位表达的免疫球蛋白进行取样，发现两种组织学模式的保留库都受到限制，这可能是由局部克隆扩增引起的。此外，GC表达的免疫球蛋白的体细胞超突变模式与正在进行的抗原驱动选择一致。T:B聚集体或GCs的存在与更严重的小管间质炎症和免疫复合物在小管基底膜的沉积密切相关。这些观察结果提出了一种新的可能性，即狼疮小管间质性肾炎不是对普遍存在的自身抗原的系统性自身免疫的表现。相反，它可能是由于对局部表达抗原的耐受性中断所致。在这项拨款申请中，我们假设在狼疮肾炎中，原位选择的B细胞分泌自身反应性抗体，这些抗体沉积在小管间质中并导致局部炎症。这一假设将在以下具体目标中进行检验：目标1。探讨红斑狼疮肾炎活检中表现为弥漫性、T:B聚集性和GC型的原位B细胞反应。目的2：确定狼疮肾炎患者原位B细胞库的来源。目的3：鉴定SLE肾炎中原位表达抗体的抗原特异性。公共卫生相关性系统性红斑狼疮最普遍、最严重的表现是肾炎。最近，我们已经证明，三级淋巴新生是狼疮性肾炎的一个共同特征，它与严重的小管间质炎症有关。在本应用中，我们将确定小管间质性肾炎是否由局部耐受性中断和原位免疫反应的发展引起。

DESCRIPTION (provided by applicant): The most frequent severe manifestation of SLE is lupus nephritis (LN). Pathologically, lupus nephritis (LN) is characterized by immune complex deposition and inflammation in both glomeruli and tubuluointersitium that, if left untreated, can result in scarring and irreversible organ failure. Of the pathological manifestations of LN, glomerulonephritis (GN) is both the best studied and the feature most often replicated in murine models of autoimmune disease. However, tubulointerstitial inflammation is also a usual feature of LN that contributes to overall disease activity and determines long-term prognosis. Myriad studies indicate that GN results from a systemic break in B cell tolerance and the local deposition of immune complexes containing antibodies reactive with ubiquitous self-antigens. However, the pathogenesis of SLE tubulointerstitial disease is not known. In this grant application, we demonstrate that in over half of patients, the tubulointerstitial inflammatory infiltrate is organized into either well-circumscribed T:B cell aggregates or germinal centers (GCs) containing follicular dendritic cells. Sampling of in situ expressed immunoglobulins using laser capture microscopy coupled to RT-PCR revealed a restricted repertoire in both histological patterns that likely arose from local clonal expansion. Furthermore, the pattern of somatic hypermutations in GC expressed immunoglobulins was consistent with ongoing antigen-driven selection. The presence of either T:B aggregates or GCs was strongly associated with more severe tubulointerstitial inflammation and the deposition of immune complexes in tubular basement membranes. These observations raise the novel possibility that lupus tubulointerstitial nephritis is not a manifestation of systemic autoimmunity to ubiquitous autoantigens. Rather, it might result from a break in tolerance to locally expressed antigens. In this grant application, we hypothesize that in lupus nephritis, in situ selected B cells secrete autoreactive antibodies which deposit in the tubulointerstitium and contribute to local inflammation. This hypothesis will be tested in the following Specific Aims: Aim 1. To characterize in situ B cell responses in lupus nephritis biopsies manifesting the diffuse, T:B aggregate and GC histological patterns. Aim 2: To determine the origin of the in situ B cell repertoire in lupus nephritis. In Aim 3: To identify the antigenic specificities of in situ expressed antibodies in SLE nephritis. PUBLIC HEALTH RELEVANCE The most prevalent, severe manifestation of systemic lupus erythematosus is nephritis. Recently, we have demonstrated that tertiary lymphoid neogenesis is a common feature of lupus nephritis that is associated with severe tubulointerstitial inflammation. In this application, we will determine if tubulointerstitial nephritis results from a local break in tolerance and the development of in situ immune responses.