Macrophages and attenuation of inflammation resolution in APOL1 nephropathy

项目摘要 在美国，自我认同为黑人的人经历不成比例的高失业率。 发生慢性肾病（CKD）并经历CKD进展为终末期肾病 （ESKD）。这种健康差异的一部分不能用社会经济和传统风险因素来解释， 这就需要研究导致疾病发病的其他生物学因素。人类遗传学研究 已经鉴定并验证了灵长类特异性载脂蛋白L1（APOL1）中的两种常见编码变体 这些基因导致非洲血统患者蛋白尿性CKD的高发病率。这些等位基因被称为G1 和G2，由于它们赋予非洲人的生存优势， 锥虫尽管它们在灵长类动物先天免疫中的作用，但对免疫细胞的作用知之甚少。 例如巨噬细胞，其有助于肾损伤和修复，在APOL 1肾病中起作用。 为了解决这一差距，我们建议使用基因组编辑的诱导多能干细胞（iPSC）衍生的细胞。 巨噬细胞和转基因小鼠研究G1和G2 APOL 1如何改变巨噬细胞的功能， 肾病由于巨噬细胞在对病原体的先天免疫反应中的双重作用， 导致肾损伤和纤维化。在初步研究中，我们已经产生了基因组编辑的G1 iPSCs， 与G0对照共享同基因背景，并发现G1 iPSC衍生的巨噬细胞维持更高的 在多种条件下促炎基因的表达。因为慢性不育的巨噬细胞 炎症可以驱动肾脏疾病，我们正在研究G1和G2 APOL 1促进 持续的促炎巨噬细胞表型和适应不良的组织修复。在各种复杂的疾病中 包括CKD，组织炎症的消退需要免疫细胞的抗炎重编程， 巨噬细胞通过吞噬作用清除凋亡细胞。此外，巨噬细胞炎症可以是 由内质网（ER）的应激或功能障碍诱导，这与APOL 1生物学有关 其他细胞类型。因此，我们假设G1和G2巨噬细胞经历受损的抗炎作用， 通过增强的ER应激重编程和无效的胞浆细胞增多，从而导致非消退性 肾脏炎症和APOL 1肾病。为了验证这一中心假设，我们将描述哪种ER应激 途径G1和G2 APOL 1干扰（目的1），研究抗炎信号传导和线粒体 G1和G2巨噬细胞修复性重编程衰减功能障碍（目的2），并确定 G1和G2 APOL 1损害红细胞增多症的机制（目的3）。拟议的调查将测试 一种新的假说，即APOL1风险等位基因通过巨噬细胞功能障碍放大肾损伤。阐明 巨噬细胞在APOL1肾病中的作用将为开发补充策略提供重要的见解 通过增强巨噬细胞介导的组织修复来治疗APOL 1疾病。

PROJECT SUMMARY Individuals who self-identify as Black in the United States experience disproportionately higher rates of developing chronic kidney disease (CKD) and experiencing CKD progression to end-stage kidney disease (ESKD). A portion of this health difference is not explained by socioeconomic and traditional risk factors, necessitating the study of other biological factors contributing to disease pathogenesis. Human genetics studies have identified and validated two common coding variants in the primate-specific Apolipoprotein L1 (APOL1) gene that contribute to high rates of proteinuric CKD in patients with African ancestry. These alleles, termed G1 and G2, evolved and became common due to the survival advantage they confer against African trypanosomiasis. Despite their role in primate innate immunity, not much is known about the role immune cells such as macrophages, which contribute to kidney injury and repair, play in APOL1 nephropathy. To address this gap, we propose to use genome-edited induced pluripotent stem cell (iPSC) derived macrophages and transgenic mice to investigate how G1 and G2 APOL1 alter macrophage function to promote kidney disease. We focus on the macrophage due to its dual role in innate immune responses to pathogens and contribution to kidney injury and fibrosis. In preliminary studies, we have generated genome-edited G1 iPSCs sharing an isogenic background with G0 controls and found that G1 iPSC derived macrophages maintain higher expression of proinflammatory genes under multiple conditions. Because chronic sterile macrophage inflammation can drive kidney disease, we are investigating mechanisms by which G1 and G2 APOL1 promote a sustained proinflammatory macrophage phenotype and maladaptive tissue repair. In various complex diseases including CKD, resolution of tissue inflammation requires anti-inflammatory reprogramming of immune cells and clearance of apoptotic cells by macrophages via efferocytosis. Additionally, macrophage inflammation can be induced by stress or dysfunction of the endoplasmic reticulum (ER), which has been implicated in APOL1 biology in other cell types. Therefore, we hypothesize that G1 and G2 macrophages undergo impaired anti-inflammatory reprogramming and inefficient efferocytosis through enhanced ER stress, thereby contributing to non-resolving kidney inflammation and APOL1 nephropathy. To test this central hypothesis, we will delineate which ER stress pathways G1 and G2 APOL1 perturb (Aim 1), investigate anti-inflammatory signaling and mitochondrial dysfunction in the attenuation of reparative reprogramming of G1 and G2 macrophages (Aim 2), and determine the mechanisms by which G1 and G2 APOL1 impair efferocytosis (Aim 3). The proposed investigations will test a novel hypothesis that APOL1 risk alleles amplify kidney injury through macrophage dysfunction. Elucidating the macrophage’s role in APOL1 nephropathy will offer critical insight for developing complementary strategies to treat APOL1 disease through enhancing macrophage-mediated tissue repair.