The role of mononuclear phagocytes in the development of FSGS

足细胞病如局灶节段性肾小球硬化的发病机制是复杂的。涉及的免疫机制知之甚少，蛋白尿本身是一种促炎刺激。尽管单核细胞吞噬细胞（单核细胞、树突状细胞（DC）和巨噬细胞）是肾内免疫系统的主要成分，但它们对足细胞病中疾病进展的贡献仍不清楚。在本研究项目中，我们将分析携带致病性NPHS 2突变的小鼠，这些突变导致类似于FSGS的进行性蛋白尿。这些小鼠的肾小球显示出促炎途径的强烈激活以及肾小球周围和肾小管间质浸润。首先，我们将分析关键的免疫细胞亚群，重点关注疾病不同阶段的单核吞噬细胞，并阐明单核细胞和树突状细胞发挥的作用（目的1）。其次，我们将通过一种化合物和两种抗体（Aim 2）中和单核细胞吸引细胞因子。我们将通过对光学透明的肾脏进行光片荧光显微镜检查，在整个器官水平上观察疾病进展和免疫细胞浸润（目的3）。最后，将利用新建立的MCD/FSGS-register（FOrMe）来表征疾病首次诊断、缓解和复发期间患者的血液和尿液免疫细胞，并将这些发现与疾病结局相关联。我们将对MCD和FSGS患者的尿细胞进行单核RNAseq，以深入了解分子机制并建立新的诊断工具（目的4）。我们的项目不仅将提供对FSGS发病机制中免疫细胞功能的更深入了解，还将有助于基于免疫细胞数据个性化免疫抑制策略，使临床医生能够为每个人选择最佳治疗方案。

The pathogenesis of podocytopathies like focal-segmental glomerulosclerosis is complex. The immunological mechanisms involved are poorly understood and proteinuria itself is a proinflammatory stimulus. Although Mononuclear phagocytes (monocytes, dendritic cells (DCs) and macrophages) are the main constituents of the intrarenal immune system, their contribution to disease progression in podocytopathies is still unclear. In this research project, we will analyze mice which carry pathogenic NPHS2 mutations resulting in progressive proteinuria similar to FSGS. Glomeruli of these mice show a robust activation of proinflammatory pathways and periglomerular and tubulointerstitial infiltrates. First, we will analyze key immune cell subsets, focusing on mononuclear phagocytes at different stages of disease and clarify which role monocytes and dendritic cells play (Aim 1). Secondly, we will neutralize monocyte-attracting cytokines by a chemical compound and two antibodies (Aim2). We will visualize disease progression and immune cell infiltration on a whole organ level by performing light sheet fluorescence microscopy of optically cleared kidneys (Aim 3). Finally, will take advantage of the newly established MCD/FSGS-register (FOrMe) to characterize blood and urinary immune cells of patients during the first diagnosis, remission and recurrence of the disease and correlate these finding with the disease outcome. We will perform single nucleus RNAseq of urinary cells from MCD and FSGS patients to gain in-depth insight into molecular mechanisms and establish a new diagnostic tool (Aim 4). Our project will not only provide a deeper understanding of immune cell function in the pathogenesis of FSGS but will also help personalizing immunosuppressive strategies based on immune cell data, enabling clinicians to choose the optimal treatment options for each individual.