Department of Urology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
Urolithiasis. 2024 Aug 28;52(1):122. doi: 10.1007/s00240-024-01622-y.
Randall's plaques (RP) serve as anchoring sites for calcium oxalate (CaOx) stones, but the underlying mechanism remains unclear. Renal interstitium with a high-calcium environment is identified as pathogenesis of RP formation where the role of human renal interstitial fibroblasts (hRIFs) was highlighted. Our study aims to elucidate the potential mechanism by which a high-calcium environment drives ectopic calcification of hRIFs to participate in RP formation. Alizarin Red staining demonstrated calcium nodules in hRIFs treated with high-calcium medium. Utilizing transcriptome sequencing, tissue factor pathway inhibitor-2 (TFPI-2) was found to be upregulated in high-calcium-induced hRIFs and RP tissues, and TFPI-2 promoted high-calcium-induced calcification of hRIFs. Subsequently, the downstream regulator of TFPI2 was screened by transcriptome sequencing analysis of hRIFs with TFPI-2 knockdown or overexpressed. Dachsous Cadherin Related 1 (DCHS1) knockdown was identified to suppress the calcification of hRIFs enhanced by TFPI-2. Further investigation revealed that TFPI-2/DCHS1 axis promoted high-calcium-induced calcification of hRIFs via disturbing the balance of ENPP1/ALP activities, but without effect on the canonical osteogenic markers, such as osteopontin (OPN), osteogenic factors runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2). In summary, our study mimicked the high-calcium environment observed in CaOx stone patients with hypercalciuria, and discovered that the high-calcium drove ectopic calcification of hRIFs via a novel TFPI-2-DCHS1-ALP/ENPP1 pathway rather than adaption of osteogenic phenotypes to participate in RP formation.
Randall 斑（RP）作为草酸钙（CaOx）结石的锚定点，但潜在机制尚不清楚。高钙环境下的肾间质被认为是 RP 形成的发病机制，其中人肾间质成纤维细胞（hRIF）的作用得到了强调。我们的研究旨在阐明高钙环境驱动 hRIF 异位钙化参与 RP 形成的潜在机制。茜素红染色显示高钙培养基处理的 hRIFs 中有钙结节。利用转录组测序，发现组织因子途径抑制剂 2（TFPI-2）在高钙诱导的 hRIFs 和 RP 组织中上调，TFPI-2 促进 hRIFs 的高钙诱导钙化。随后，通过 TFPI-2 敲低或过表达的 hRIFs 的转录组测序分析筛选 TFPI2 的下游调节剂。发现 Dachsous Cadherin Related 1（DCHS1）敲低可抑制 TFPI-2 增强的 hRIFs 钙化。进一步研究表明，TFPI-2/DCHS1 轴通过干扰 ENPP1/ALP 活性平衡促进 hRIFs 的高钙诱导钙化，但对经典成骨标志物如骨桥蛋白（OPN）、成骨因子 runt 相关转录因子 2（RUNX2）、骨形态发生蛋白 2（BMP2）没有影响。总之，我们的研究模拟了高钙尿症 CaOx 结石患者中观察到的高钙环境，发现高钙通过 novel TFPI-2-DCHS1-ALP/ENPP1 途径驱动 hRIFs 的异位钙化，而不是通过成骨表型的适应来参与 RP 形成。
