Macrophage-mediated inflammation plays a significant role in the development and progression of diabetic nephropathy (DN). However, the underlying mechanisms remain unclear. Studies suggest that T cell immunoglobulin domain and mucin domain-3 (Tim-3) has complicated roles in regulating macrophage activation, but its roles in the progression of DN are still completely unknown. We downregulated Tim-3 expression in kidney (intrarenal injection of Tim-3 shRNA expressing lentivirus or global Tim-3 knockout mice) and induced DN by streptozotocin (STZ). We analyzed the degree of renal injury, especially the podocyte injury induced by activated macrophages in vitro and in vivo. Then, we transferred different bone marrow derived macrophages (BMs) into STZ-induced Tim-3 knockdown mice to examine the effects of Tim-3 on macrophages in DN. First, we found that Tim-3 expression on renal macrophages was increased in patients with DN and in two diabetic mouse models, i.e. STZ-induced diabetic mice and db/db mice, and positively correlated with renal dysfunction of DN patients. Tim-3 deficiency ameliorated renal damage in STZ-induced diabetes with concurrent increase in protein levels of Nephrin and WT-1. Similar effects were observed in mice with Tim-3 knockdown diabetic mice. Second, adoptive transfer of Tim-3-expressing macrophages, but not Tim-3 knockout macrophages, accelerated diabetic renal injury in DN mice, suggesting a key role for Tim-3 on macrophages in the development of DN. Furthermore, we found NF-κB activation and TNF-α excretion were upregulated by Tim-3 in diabetic kidneys, and podocyte injury was associated with the Tim-3-mediated activation of the NF-κB/TNF-α signaling pathway in DN macrophages both in vivo and in vitro. These results suggest that Tim-3 functions as a key regulator in renal inflammatory processes and serves as a potential therapeutic target for renal injury in DN.

Renal fibrosis is the ultimate presentation of chronic kidney disease, which progresses to end-stage renal disease. Hydroxychloroquine (HCQ) has been adapted for the treatment of autoimmune diseases; however, the potential mechanism underlying the role of HCQ in renal fibrosis remains unclear. C57BL/6 J mice were randomly divided into three groups (sham group, UUO group, and UUO + HCQ group (20 mg/kg)). HE and Masson staining were performed to assess kidney tissue damage and fibrosis, and western blotting was performed to assess the expression of epithelial-mesenchymal transition (EMT), extracellular matrix (ECM), PI3K/AKT, and NF-κB-related proteins. PCR and TUNEL were adopted to detect inflammatory factors and cell apoptosis. HK-2 cells treated with TGF-β1 were used for the in vitro experiments. HCQ may potentially have therapeutic effects on renal fibrosis mediated through 122 target genes, and the Kyoto Encyclopedia of Genes and Genomes pathways of these genes were enriched for PI3K/AKT signaling based on network pharmacology. UUO mice that received HCQ demonstrated significantly less tubular damage than the UUO mice. HCQ treatment additionally blunted EMT in UUO kidneys and TGF-β1-treated renal tubular epithelial cells, and alleviated ECM deposition in kidney tissue. Furthermore, HCQ treatment reduced UUO-induced inflammation and apoptosis. Mechanistically, HCQ treatment suppressed the activation of the PI3K/Akt and NF-kB pathways. This study demonstrated that HCQ ameliorated renal fibrosis by inhibiting the PI3K/AKT and NF-κB signaling pathways to attenuate inflammatory factors and the apoptotic function of renal tubular epithelial cells, thus providing renewed theoretical evidence for HCQ treatment of renal fibrosis.

Background: Previous studies have shown that podocyte autophagy is an important trigger for proteinuria and glomerulosclerosis. The mammalian rapamycin target protein (mTOR) occupies a pivotal position in the autophagy pathway. In this study, we planned to clarify the mechanism of mTOR regulation of podocyte autophagy and the effect of rapamycin (RAPA). Methods: All rats were randomly divided into normal control group (n = 8), DN group (n = 8), and RAPA group (n = 8). Blood and urine samples were collected at the 4th, 8th, and 12th weeks of the experiment. The serum creatinine (Scr), urine volume levels, and the 24 h urine protein (UP) levels were examined. The nephrin, podocin, mTOR, ribosomal S6 kinase 1 (S6K1), and autophagy marker light chain 3 (LC3II) expression levels were evaluated by immunohistochemistry, quantitative PCR, and immunoblotting. Results: The urine volume, 24 h UP, and Scr of the DN and RAPA groups increased significantly compared with the NC group (p < .05). Nephrin and podocin expression was decreased in the kidney tissues of the DN and RAPA groups compared with the NC group (p < .05). The expression levels of mTOR and S6K1 increased and LC3II expression decreased in the renal tissues of the DN and RAPA groups compared with the NC group (p < .05). After RAPA treatment, all the above indexes were improved compared with the DN group (p < .05), but were significantly abnormal compared with the NC group (p < .05). Conclusion: The proteinuria and kidney function had improved after RAPA treatment. These results confirmed that RAPA specifically binds to mTOR kinase, and inhibits mTOR activity, thereby regulating the pathological autophagic process.

Ntaining 33mM glucose. The cells were divided into the following groups: (1) normal glucose group as control incubated in Roswell Park Memorial Institute (RPMI) 1640 containing 5mM glucose; (2) Ang-(1–7), 10nM, incubated in RPMI 1640 containing 5mM glucose; (3) the HG group incubated in RPMI 1640 containing 33mM glucose; and (4) Ang-(1–7), 10nM, incubated in HG group incubated in RPMI 1640 containing 33mM glucose. After a period of 24 hours, mitochondrial fission and podocyte fusion were observed by electron microscope. Additionally, p53 and Drp1 were tested by Western blot, the position of Drp1 was detected by immunofluorescence, and miR-30a was analyzed by quantitative real-time polymerase chain reaction. Results Ang-(1–7) inhibited mitochondrial fission in HG-treated podocytes. However, Ang-(1–7) also significantly reduced the expression of Drp1 and p53, and improved the expression of miR-30a in HG-induced podocytes. Conclusion Ang-(1–7) inhibited mitochondrial fission in HG-induced podocytes by upregulation of miR-30a and downregulation of Drp1 and p53....

Introduction: IgA nephropathy (IgAN) is the most common disease leading to end-stage renal disease, and tubular fibrosis represents an important risk factor for disease progression. However, research on early molecular diagnostic indicators of tubular fibrosis and the mechanisms underlying disease progression is still lacking.Methods: The GSE93798 dataset was downloaded from the GEO database. DEGs were screened and analyzed for GO and KEGG enrichment in IgAN. The least absolute shrinkage and selection operator (LASSO) and support vector machine recursive feature elimination (SVM-RFE) algorithms were applied to screen for hub secretory genes. The expression and diagnostic efficacy of hub genes were confirmed by the GSE35487 dataset. ELISA was applied to detect the expression of APOC1 in serum. The expression and localization of hub genes in IgAN were verified by the expression of IHC and IF in human kidney tissues, and the correlation of expression with clinical data was verified in the Nephroseq database. Finally, cellular experiments clarified the role of hub genes in the signaling pathway.Results: A total of 339 DEGs were identified in IgAN, of which 237 were upregulated and 102 downregulated. The KEGG signaling pathway is enriched in the ECM–receptor interaction and AGE-RAGE signaling pathway. APOC1, ALB, CCL8, CXCL2, SRPX2, and TGFBI identified six hub secretory genes using the LASSO and SVM-RFE algorithms. In vivo and in vitro experiments demonstrated that APOC1 expression was elevated in IgAN. The serum concentration of APOC1 was 1.232 ± 0.1812 μg/ml in IgAN patients, whereas it was 0.3956 ± 0.1233 μg/ml in healthy individuals. APOC1 exhibited high diagnostic efficacy for IgAN (AUC of 99.091%, specificity of 95.455%, and sensitivity of 99.141%) in the GSE93798 dataset. APOC1 expression negatively correlated with eGFR (R² = 0.2285, p = 0.0385) and positively correlated with serum creatinine (R² = 0.41, p = 0.000567) in IgAN. APOC1 exacerbated renal fibrosis, possibly in part by activating the NF-κB pathway in IgAN.Conclusion: APOC1 was identified as the core secretory gene of IgAN, which was closely associated with blood creatinine and eGFR and had significant efficacy in the diagnosis of IgAN. Mechanistic studies revealed that the knockdown of APOC1 could improve IgAN renal fibrosis by inhibiting the NF pathway, which may be a potential therapeutic target for improving renal fibrosis in IgAN.