Macrophages and attenuation of inflammation resolution in APOL1 nephropathy

项目总结 在美国，自我认同为黑人的人经历了不成比例的高发病率 发展为慢性肾脏病(CKD)并经历CKD进展为终末期肾病 (ESKD)。这种健康差异的一部分无法用社会经济和传统风险因素来解释， 有必要研究导致疾病发病的其他生物因素。人类遗传学研究 已经确定并验证了灵长类特异载脂蛋白L1(APOL1)的两个常见编码变体 导致非洲血统患者高蛋白尿性慢性肾脏病发生率的基因。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，它们进化并变得普遍 锥虫病。尽管它们在灵长类动物的先天免疫中起作用，但对免疫细胞的作用知之甚少。 如巨噬细胞，有助于肾脏损伤和修复，在APOL1肾病中发挥作用。 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)来源 巨噬细胞和转基因小鼠研究G1和G2 APOL1如何改变巨噬细胞功能以促进 肾脏疾病。我们把重点放在巨噬细胞上，因为它在对病原体和 对肾脏损伤和纤维化的贡献。在初步研究中，我们已经产生了基因组编辑的G1 ipscs 与G0对照共享相同的基因背景，并发现G1 iPSC来源的巨噬细胞保持较高水平 促炎症基因在多种条件下的表达。因为慢性无菌巨噬细胞 炎症可以导致肾脏疾病，我们正在研究G1和G2促进APOL1的机制 持续的促炎巨噬细胞表型和不适应的组织修复。在各种复杂的疾病中 包括慢性肾脏病在内，组织炎症的解决需要免疫细胞的抗炎重新编程和 巨噬细胞通过胞吐清除凋亡细胞。此外，巨噬细胞炎症可以 由内质网(ER)应激或功能障碍引起的，这与APOL1生物学有关 在其他细胞类型中。因此，我们假设G1和G2巨噬细胞的抗炎功能受损。 通过增强内质网应激进行重新编程和低效的胞吐作用，从而导致无法解决 肾炎与APOL1肾病。为了检验这一中心假设，我们将描绘出哪种内质网压力 途径G1和G2 APOL1扰动(目标1)，研究抗炎信号和线粒体 G1和G2巨噬细胞修复性重编程的减弱功能障碍(目标2)，并确定 G1和G2载脂蛋白1抑制胞吐作用的机制(目标3)。拟议中的调查将考验 一种新的假设，即APOL1风险等位基因通过巨噬细胞功能障碍放大肾脏损伤。澄清 巨噬细胞在APOL1肾病中的作用将为开发补充策略提供关键的见解 通过促进巨噬细胞介导的组织修复来治疗APOL1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.