Abstract：
While NLRP3 contributes to kidney fibrosis, the function of most NOD-like receptors (NLRs) in chronic kidney disease (CKD) remains unexplored. To identify further NLR members involved in the pathogenesis of CKD, we searched for NLR genes expressed by normal kidneys and differentially expressed in human CKD transcriptomics databases. For NLRP6, lower kidney expression correlated with decreasing glomerular filtration rate. The role and molecular mechanisms of Nlrp6 in kidney fibrosis were explored in wild-type and Nlrp6-deficient mice and cell cultures. Data mining of single-cell transcriptomics databases identified proximal tubular cells as the main site of Nlrp6 expression in normal human kidneys and tubular cell Nlrp6 was lost in CKD. We confirmed kidney Nlrp6 downregulation following murine unilateral ureteral obstruction. Nlrp6-deficient mice had higher kidney p38 MAPK activation and more severe kidney inflammation and fibrosis. Similar results were obtained in adenine-induced kidney fibrosis. Mechanistically, profibrotic cytokines transforming growth factor beta 1 (TGF-β1) and TWEAK decreased Nlrp6 expression in cultured tubular cells, and Nlrp6 downregulation resulted in increased TGF-β1 and CTGF expression through p38 MAPK activation, as well as in downregulation of the antifibrotic factor Klotho, suggesting that loss of Nlrp6 promotes maladaptive tubular cell responses. The pattern of gene expression following Nlrp6 targeting in cultured proximal tubular cells was consistent with maladaptive transitions for proximal tubular cells described in single-cell transcriptomics datasets. In conclusion, endogenous constitutive Nlrp6 dampens sterile kidney inflammation and fibrosis. Loss of Nlrp6 expression by tubular cells may contribute to CKD progression.
摘要：
虽然NLRP3有助于肾脏纤维化，大多数NOD样受体(NLR)在慢性肾脏病(CKD)中的功能仍未被研究.为了进一步确定参与CKD发病机制的NLR成员，我们在人类CKD转录组学数据库中搜索了正常肾脏表达和差异表达的NLR基因.对于NLRP6，较低的肾脏表达与肾小球滤过率降低相关。在野生型和Nlrp6缺陷小鼠和细胞培养物中探讨了Nlrp6在肾纤维化中的作用和分子机制。单细胞转录组学数据库的数据挖掘确定近端肾小管细胞是正常人肾脏中Nlrp6表达的主要位点，而肾小管细胞Nlrp6在CKD中丢失。我们证实了小鼠单侧输尿管梗阻后肾脏Nlrp6下调。Nlrp6缺陷小鼠具有较高的肾脏p38MAPK活化和更严重的肾脏炎症和纤维化。在腺嘌呤诱导的肾纤维化中获得了类似的结果。机械上,促纤维化细胞因子转化生长因子β1（TGF-β1）和TWEAK降低培养的肾小管细胞中Nlrp6的表达，Nlrp6下调通过p38MAPK激活导致TGF-β1和CTGF表达增加，以及抗纤维化因子Klotho的下调，表明Nlrp6的缺失促进了适应不良的肾小管细胞反应。在培养的近端肾小管细胞中Nlrp6靶向后的基因表达模式与单细胞转录组学数据集中描述的近端肾小管细胞的适应不良转变一致。总之,内源性Nlrp6抑制无菌肾脏炎症和纤维化。肾小管细胞Nlrp6表达的缺失可能有助于CKD进展。
