Glomerular endothelial cells (GEC) are a crucial component of the glomerular physiology and their damage contributes to the progression of chronic kidney diseases. How GEC affect the pathology of Alport syndrome (AS) however, is unclear. We characterized GEC from wild type (WT) and col4α5 knockout AS mice, a hereditary disorder characterized by progressive renal failure. We used endothelial-specific Tek-tdTomato reporter mice to isolate GEC by FACS and performed transcriptome analysis on them from WT and AS mice, followed by in vitro functional assays and confocal and intravital imaging studies. Biopsies from patients with chronic kidney disease, including AS were compared with our findings in mice. We identified two subpopulations of GEC (dim^tdT and bright^tdT) based on the fluorescence intensity of the Tek^tdT signal. In AS mice, the bright^tdT cell number increased and presented differential expression of endothelial markers compared to WT. RNA-seq analysis revealed differences in the immune and metabolic signaling pathways. In AS mice, dim^tdT and bright^tdT cells had different expression profiles of matrix-associated genes (Svep1, Itgβ6), metabolic activity (Apom, Pgc1α) and immune modulation (Apelin, Icam1) compared to WT mice. We confirmed a new pro-inflammatory role of Apelin in AS mice and in cultured human GEC. Gene modulations were identified comparable to the biopsies from patients with AS and focal segmental glomerulosclerosis, possibly indicating that the same mechanisms apply to humans. We report the presence of two GEC subpopulations that differ between AS and healthy mice or humans. This finding paves the way to a better understanding of the pathogenic role of GEC in AS progression and could lead to novel therapeutic targets.

肾小球内皮细胞（GEC）是肾小球生理的重要组成部分，其损害有助于慢性肾脏疾病的发展。目前尚不清楚GEC如何影响Alport综合征（AS）的病理。我们的特点GEC来自野生型（WT）和COL4 α 5基因敲除小鼠，一种遗传性疾病，其特征为进行性肾功能衰竭。我们使用内皮特异性的Tek-tdTomato报告基因小鼠通过FACS分离GEC，并从WT和AS小鼠身上对其进行转录组分析，然后进行体外功能测定以及共聚焦和活体成像研究。将包括AS在内的慢性肾脏疾病患者的活检与我们在小鼠中的发现进行了比较。我们确定了GEC的两个亚群（dim ^tdT和^{Bright tdT}）取决于Tek ^tdT信号的荧光强度。在AS小鼠中，与WT相比，明亮的^tdT细胞数量增加并呈现出内皮标志物的差异表达。RNA-seq分析揭示了免疫和代谢信号传导途径的差异。在AS小鼠中，暗淡的^tdT和明亮的^tdT细胞具有不同的基质相关基因（Svep1，Itgβ6），代谢活性（Apom，Pgc1α）和免疫调节（Apelin，Icam1）表达谱）与WT小鼠相比。我们证实了Apelin在AS小鼠和培养的人GEC中具有新的促炎作用。鉴定出的基因调制与AS和局灶性节段性肾小球硬化患者的活检具有可比性，可能表明相同的机制适用于人类。我们报告了两个AS和健康小鼠或人类之间存在差异的GEC亚群。这一发现为更好地了解GEC在AS进展中的致病性铺平了道路，并可能导致新的治疗靶标。