Tertiary Lymphoid Neogenesis in Human Lupus Nephritis

描述(申请人提供)：SLE最常见的严重表现是狼疮性肾炎(LN)。从病理上讲，狼疮性肾炎(LN)的特征是肾小球和肾小管间质的免疫复合体沉积和炎症，如果不治疗，可能会导致瘢痕形成和不可逆转的器官衰竭。在LN的病理表现中，肾小球肾炎(GN)是研究得最好的，也是自身免疫性疾病小鼠模型中最常见的特征。然而，肾小管间质炎症也是LN的常见特征，有助于疾病的整体活动性，并决定长期预后。无数研究表明，GN是由于B细胞耐受性的全身性破坏和含有与无处不在的自身抗原反应的抗体的免疫复合体的局部沉积所致。然而，SLE肾小管间质疾病的发病机制尚不清楚。在这项赠款申请中，我们证明，在超过一半的患者中，肾小管间质炎症浸润物被组织成边界清楚的T：B细胞聚集体或含有滤泡树突状细胞的生发中心(GC)。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采样，发现在这两种组织学模式中都存在可能源于局部克隆性扩增的限制性谱系。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的选择是一致的。T：B聚集体或GC的存在与更严重的肾小管间质炎症和肾小管基底膜中免疫复合体的沉积密切相关。这些观察提出了一种新的可能性，即狼疮性小管间质肾炎不是对无处不在的自身抗原的全身性自身免疫的表现。相反，它可能是由于对当地表达的抗原的耐受性下降所致。在这项赠款申请中，我们假设在狼疮性肾炎中，原位选择的B细胞分泌自身反应性抗体，这些抗体沉积在肾小管间质中，有助于局部炎症。这一假说将在以下特定目标中得到验证：目的1.研究狼疮性肾炎活检组织中表现为弥漫性、T：B聚集性和GC组织学类型的原位B细胞反应。目的：探讨狼疮性肾炎中原位B细胞谱系的来源。目的3：鉴定原位表达的抗体在SLE肾炎中的抗原性。公共卫生相关性系统性红斑狼疮最常见、最严重的表现是肾炎。最近，我们发现三级淋巴样新生是狼疮性肾炎的一个共同特征，它与严重的肾小管间质炎症有关。在这项应用中，我们将确定肾小管间质肾炎是否是由于局部耐受性的破坏和原位免疫反应的发展所致。

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.