Maladaptive repair following acute kidney injury (AKI) is an independent risk factor for the progression to chronic kidney disease (CKD). We hypothesize that renal tubular cell senescence and subsequent epithelial-mesenchymal transition drive maladaptive repair after AKI, ultimately leading to chronic renal fibrosis. We re-analyzed single-cell RNA sequencing data (ScRNA-seq, GSE212273) from kidney tissues post-IRI. Invivo, we employed unilateral IRI and folic acid models to simulate the AKI to CKD transition. Senolytics or verteporfin were given from Day 3 post-modeling. Invitro, human renal tubular epithelial (HK-2) cells were exposed to hydrogen peroxide or TGF-β. Sustained YAP1 overexpression promoted fibroblast activation and a profibrotic phenotypic shift. AKI induced a sustained increase in YAP1 expression, which was associated with tubular cell senescence and renal interstitial fibrosis. Senolytics effectively suppressed YAP1 activity, renal senescence, and alleviated kidney fibrosis. Invitro, persistent oxidative stress upregulated YAP1 expression and induced cell senescence. Knockdown of YAP1 downregulated Hippo signaling pathway, extracellular matrix reorganization, and reduced cell senescence. Conversely, YAP1 overexpression reversed the anti-senescence effect of senolytics. Finally, pharmacological inhibition of YAP1/TEAD1 attenuated cell senescence and post-ischemic renal fibrosis. Our findings indicate that sustained YAP1 overexpression mediates tubular cell senescence, which drives maladaptive kidney repair and facilitates the AKI to CKD transition. Senolytics or verteporfin therapy initiated after the peak of AKI offers a dual benefit: it protects the regenerative capacity of tubular cells and concurrently inhibits YAP1-driven epithelial-mesenchymal transition, thereby mitigating the progression of renal fibrosis.

Nesfatin-1 attenuates renal interstitial fibrosis, oxidative stress, and inflammation through dual suppression of TGF-β1/Smad and NF-κB/GPR12 signaling.

Soluble PD-1 drives renal fibrosis in CKD by disrupting immune homeostasis: Therapeutic mitigation via a targeted sPD-1 sequestration strategy.

The ketogenic diet (KD) is widely used in disease management and healthy populations, but its long-term physiological safety remains unclear. While KD protects against kidney injury in models, its effects on healthy renal tissue are poorly understood. Two-sample Mendelian randomization (MR) analyzed causality between serum 3-hydroxybutyrate (BHB) and renal injury. Mice underwent 3-month KD, short-term BHB gavage, or time-restricted feeding (tRF). Renal histology, fibrosis, and partial epithelial-mesenchymal transition (pEMT) were assessed. RNA sequencing identified pathways, validated in HK-2 cells. Genetically elevated serum BHB was causally linked to higher renal injury risk. In healthy mice, long-term KD induced renal interstitial fibrosis and maladaptive repair of renal tubular epithelial cells (TECs), characterized by partial EMT, while short-term BHB gavage or tRF reproduced early pro-fibrotic changes (partial EMT and increased fibronectin/collagen I expression) without establishing overt fibrosis. In contrast, in mice with unilateral ischemia-reperfusion injury (UIRI), both BHB and tRF reduced renal damage, renal interstitial collagen deposition and maladaptive repair of TECs. Mechanically, KD upregulated Wnt8b and Junb in healthy kidneys, and BHB treatment promoted β-catenin nuclear translocation in a Wnt8b-dependent manner. Knockdown of Wnt8b or Junb suppressed BHB-induced partial EMT in HK-2 cells. Notably, BHB oppositely regulated Wnt8b in injured kidneys, where it attenuated injury-driven Wnt8b elevation. Ketosis exhibits a dichotomous renal role: promoting fibrosis through Wnt8b/Junb mediated partial EMT in healthy tissue, while protecting against injury-induced fibrosis. These findings emphasize the context-dependence of KD and caution against its long-term use in healthy individuals.

Nesfatin-1 mitigates calcium oxalate nephropathy in mice through GPR12 receptor modulation and PKCα/NADPH oxidase pathway inhibition.

Renal interstitial fibrosis is the predominant cause of end-stage renal disease. Oxidative stress and an increased PI3K/Akt/mTOR pathway play a key role in the development of renal interstitial fibrosis caused by ureteral obstruction. 6-gingerol (6-G) is known to have a natural antioxidant effect; however, the effect of 6-G on progressive renal fibrosis due to ureteral obstruction has not been fully elucidated. The aim of the study is to evaluate the antifibrotic effect of 6-G and characterize the underlying mechanism of its action on unilateral ureteral obstruction (UUO) rats. Male Sprague-Dawley rats underwent UUO via double ligation of the left ureter for a duration of 14 days. Sham rats underwent identical treatment, with the exception of the absence of double ligation. The levels of phosphorylated PI3K/Akt/mTOR in the kidney were assessed by semiquantitative immunoblotting, while the gene expressions of TGF-β1 and α-SMA were evaluated through qRT-PCR. Oxidative stress parameters were evaluated with an ELISA kit and spectrophotometer, while histopathological assessment was conducted through Masson's trichrome, hematoxylin and eosin (HE), and immunohistochemical analysis of collagen type III. In comparison to UUO rats, renal fibrosis and collagen type III deposition were diminished, and the phosphorylation of PI3K/Akt/mTOR was reduced in rats treated with 6-G. 6-G also reduced the expression of TGF-β1 and α-SMA genes in obstructed kidneys. In comparison to UUO rats, rats administered with 6-G exhibited elevated activities of glutathione peroxidase and decreased levels of malondialdehyde. The findings suggest that 6-G is a potential therapeutic agent for renal interstitial fibrosis, with its antifibrotic actions perhaps facilitated by the enhanced activity of the PI3K/Akt/mTOR pathways and decreased oxidative stress in UUO rats.

X-linked Alport syndrome (XLAS) is a hereditary glomerular basement membrane (GBM) disease caused byCOL4A5 mutations, leading to end-stage renal disease. With unclear pathogenesis and limited treatments, reliable animal models are urgently needed. In this study, the mutation K229X in COL4A5 detected in XLAS patients was introduced into mice model by CRISPR/Cas. The clinical manifestations and pathological changes in the K229X mice were characterized through urinary and serum tests, histopathology, immunofluorescence, and transmission electron microscopy. In K229X male mice, we observed significant hematuria and proteinuria, along with azotemia, and noted a marked decrease in the expression of COL4A5 at both the mRNA and protein levels within the kidneys. Pathological examination revealed glomerulosclerosis, increased mononuclear cells in the renal interstitium, interstitial fibrosis, and absence of α5 collagen IV, with histological abnormalities in the glomeruli, renal tubules, and interstitium progressing with age. Electron microscopy found irregular thickening of the GBM, accompanied by irregular layering. The phenotypic and pathological features of this mouse model are consistent with those observed in XLAS patients and other previously established mouse models. This K229X mouse model is of significant importance for exploring the pathogenic mechanisms of XLAS and researching potential therapeutic approaches.

S100A8/A9 promotes renal fibrosis by driving macrophage-to-myofibroblast transition via the TLR4/NF-κB pathway.

ObjectiveRenal fibrosis plays a pivotal role in the progression of renal dysfunction in diabetic kidney disease (DKD), with the macrophage-to-myofibroblast transition (MMT) serving as a central mechanism driving the advancement of renal fibrosis to end-stage renal disease (ESRD) in various chronic kidney conditions. Although the sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin (DAPA) slows renal function decline in DKD, its antifibrotic mechanisms remain unclear. This study aimed to elucidate whether DAPA ameliorates renal fibrosis by suppressing MMT, and the underlying molecular mechanisms.MethodsWe established a DKD model in male C57BL/6J mice by inducing them with a high-fat diet (HFD) followed by streptozotocin (STZ) injection. The effects of DAPA on renal function parameters (serum creatinine (Scr), urinary albumin-to-creatinine ratio (UACR)), and renal pathological injury, fibrosis markers (α-smooth muscle actin (α-SMA), type I collagen (Col-I)) were comprehensively evaluated. Immunofluorescence (IF) and Western blot were employed to analyze MMT progression (F4/80+/α-SMA+ double-positive cells) and TGF-β1-Smad3/7 pathway activity.ResultsDAPA significantly reduced blood glucose levels, mitigated weight loss, and effectively inhibited type 2 diabetes-induced increase in Scr (43.78 ± 3.84 vs. 33.93 ± 6.77 µmol/L, P < 0.05) and UACR (89.17 ± 16.33 vs. 52.51 ± 10.51 mg/g, P < 0.05) in DKD mice. DAPA significantly attenuated glomerular hypertrophy, mesangial hyperplasia, and vacuolar degeneration of the tubular epithelium in DKD mice, while concurrently reducing glomerular and tubular injury scores, as well as the renal interstitial fibrosis area (P < 0.05). IF revealed increased MMT within the renal tubulointerstitium in DKD mice, accompanied by elevated deposition of α-SMA and Col-I. DAPA treatment markedly reduced F4/80+ macrophage infiltration and F4/80+/α-SMA+ and F4/80+/Col-I+ double-positive MMT cells, with decreased α-SMA and Col-I expression (P < 0.05). Additionally, TGF-β1 and phosphorylated Smad3 (p-Smad3) expression were significantly upregulated in DKD mice, whereas Smad7 was downregulated (P < 0.05). DAPA treatment significantly reduced TGF-β1 and p-Smad3 levels and restored Smad7 expression, rebalancing the Smad3/Smad7 axis (P < 0.05). Therefore, we propose that DAPA likely alleviates renal fibrosis in DKD by modulating renal TGF-β1 activity and restoring the Smad3/Smad7 balance, thereby suppressing MMT.ConclusionThis study is the first to reveal that DAPA is highly likely to exert anti-fibrotic effects through a novel mechanism involving targeted modulation of the TGF-β1-Smad3/7 axis to inhibit MMT, thereby laying a theoretical foundation and identifying a potential therapeutic target for precision treatment of DKD.

This prospective study designed to evaluate the diagnostic capabilities of diffusion kurtosis imaging (DKI) and intravoxel incoherent motion (IVIM) in assessing renal interstitial fibrosis in glomerulonephritis (GN). GN was induced in rats by tail vein injection of puromycin amino nucleoside. Animals were sacrificed at six time points (weeks 2, 4, 6, 10, 14, 16) to capture progressive fibrosis, which was graded T0, T1, and T2 by Masson's trichrome staining. A total of 43 rats included in the final analysis were compared across fibrosis stages, and diagnostic performance was assessed by receiver operating characteristic curve analysis. With increasing fibrosis, MK and FA rose significantly, whereas MD, D, D*, and f declined. Fibrosis categories correlated positively with MK and FA and negatively with MD, D, D*, and f (all P < 0.05). When differentiating T0 from healthy control group and T1 from T0, medullary FA in DKI provided the highest area under the curve (AUC), while medullary D* in IVIM showed the highest AUC. The combination of medullary D* and FA yielded significantly better AUC than individual parameters (P < 0.05). In distinguishing T1 from T2, cortical MK in DKI provided the highest AUC, while medullary D* in IVIM was the most AUC. However, no statistically significant difference was found between the combined and individual parameters (P > 0.05). Mild-to-moderate GN-related fibrosis (T0-T1) was more effectively differentiated using medullary IVIM parameters, whereas advanced fibrosis (T2) was better distinguished by cortical DKI metrics. The combined application of IVIM and DKI provided complementary value for fibrosis staging.

Dual-targeted engineered mesenchymal stem cell-derived extracellular vesicles delivering Nedd4 attenuate renal fibrosis in diabetic kidney disease.

Targeting DYRK1A with harmine abrogates the FOXO1-NF-κB axis to alleviate cellular senescence and renal fibrosis.

Renal fibrosis, a pivotal pathological process in chronic kidney disease (CKD), is closely associated with inflammatory responses and gut microbiota dysbiosis. Curcumin (CUR), a natural polyphenol derived from turmeric, shows anti-inflammatory and microbiota-modulating properties. However, its potential to attenuate renal fibrosis via gut microbiota-derived metabolites remains unclear. In this study, we investigated the mechanisms underlying the renoprotective effects of CUR, using a murine model of unilateral ureteral obstruction and LPS-stimulated bone marrow-derived macrophages (BMDMs). CUR treatment significantly alleviated renal interstitial fibrosis, reduced collagen deposition, and downregulated the pro-inflammatory mediators S100 calcium-binding proteins A8 (S100A8)/A9. Additionally, CUR modified the gut microbiota composition by enriching short-chain fatty acid (SCFA)-producing bacteria, leading to elevated systemic SCFA levels, particularly acetate, whose supplementation also ameliorated renal fibrosis, suppressed the S100A8/A9-toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF‑κB) signaling axis, and inhibited macrophage-myofibroblast transition (MMT). Acetate in vitro treatment attenuated the LPS-induced co-expression of S100A8/A9 and TLR4 in BMDMs, reduced pro-inflammatory cytokine release, and suppressed M1 polarization. These findings highlight that acetate, a key microbiota-derived metabolite increased by CUR treatment, mediates renal protection by targeting the S100A8/A9-TLR4 signaling pathway in macrophages, suggesting a novel gut-kidney axis-based therapeutic strategy for CKD.

Chronic kidney disease (CKD) represents a considerable health burden for both humans and veterinary patients globally. Renal fibrosis is the final common pathway for the progression of CKD to end-stage renal disease, which can eventually lead to renal failure. Thymoquinone (TQ), the primary bioactive constituent of Nigella sativa, has demonstrated significant antifibrotic potential; however, the specific molecular mechanisms underlying its renoprotective effects remain incompletely elucidated. This study aimed to investigate how TQ alleviates renal fibrosis to support its potential as a therapeutic agent. TQ’s renoprotective effects were evaluated in a murine unilateral ureteral obstruction (UUO) model using histopathology, Western blotting, immunofluorescence, and RT-qPCR. Network pharmacology and untargeted metabolomics were integrated to identify key pathways, which were further assessed through in vivo and in vitro experiments. TQ treatment attenuated UUO-induced renal interstitial injury. TQ treatment downregulated α-smooth muscle actin (α-SMA) and fibronectin, thereby suppressing myofibroblast activation and extracellular matrix (ECM) accumulation. Integrated multi-omics analyses indicated that the antifibrotic activity of TQ is associated with modulation of the PI3K/AKT signaling axis. Subsequent in vivo and in vitro studies suggested that TQ protects against renal injury by inhibiting aberrant PI3K/AKT signaling. This study found that TQ ameliorates renal interstitial fibrosis in UUO mice. The underlying mechanism appears to involve suppression of myofibroblast activation and ECM accumulation via inhibition of PI3K/AKT signaling. These findings highlight the therapeutic potential of TQ for renal fibrosis.

Background/Objectives: Chronic urate nephropathy (CUN), also referred to as gouty nephropathy, represents a severe renal disease primarily precipitated by long-term hyperuricemia (HUA) and gout. However, the precise molecular mechanisms underlying its pathogenesis remain poorly understood. The present study was designed to explore these mechanisms from the perspective of targeted metabolomics. Methods: The HUA mice constructed by urate oxidase (Uox) gene knockout (KO) and their corresponding wild-type controls were employed for the present study. Serum clinical biochemical parameters were determined, and renal histopathological changes were evaluated using hematoxylin-eosin (HE) staining and Masson's trichrome staining. A targeted metabolomic strategy based on multiple reaction monitoring (MRM) was utilized to profile the renal metabolic landscape of Uox-KO mice, and potential metabolic biomarkers for CUN were identified via multivariate data analysis. Results: Clinical biochemical analysis revealed a significant elevation in serum uric acid, creatinine, and urea nitrogen levels in Uox-KO mice compared with control mice. Histopathological observations confirmed a typical CUN phenotype in Uox-KO mice, characterized by renal tubular vacuolar degeneration and dilatation, desquamation of tubular epithelial cells into the lumen, neutrophil infiltration, glomerular crowding, and renal interstitial fibrosis. Metabolomic analysis identified a total of 291 differentially regulated metabolites in Uox-KO mice relative to control animals. These perturbed metabolites were involved in multiple key biochemical pathways, including amino acid biosynthesis, ABC transporter signaling pathway, purine metabolism, aminoacyl-tRNA biosynthesis, protein digestion and absorption, glycerophospholipid metabolism, and serotonergic synaptic transmission. Notably, pathological parameters, including biochemical measurements and histological observations, were significantly correlated with key differential metabolites associated with CUN progression. Furthermore, eleven differential metabolites (pyroglutamic acid, fructose, riboflavin, dimethyl-L-arginine, glucaric acid, indoxyl sulfate, palmitoylethanolamide, trimethylamine N-oxide, 3-hydroxyanthranilic acid, spermidine, and hippuric acid) were identified as potential metabolic biomarkers for the diagnosis and prognosis of CUN. Conclusions: These findings illustrate that targeted tissue metabolomic analysis constitutes a powerful tool for deciphering the molecular mechanisms of diseases, thus offering novel insights into the pathogenesis of CUN.

PurposeRenal interstitial fibrosis (RIF) is a critical pathological process in the progression of chronic kidney disease (CKD). This study aimed to identify and validate inflammation- and hypoxia-related differentially expressed genes (IHRDEGs) associated with RIF and to construct a robust diagnostic model with potential clinical applications.Patients and MethodsThree public GEO datasets (GSE22459, GSE76882, GSE53605) comprising 76 RIF and 142 control samples were integrated following batch correction and normalization. Differentially expressed IHRDEGs were screened and analyzed using GO and KEGG pathway enrichment. A diagnostic model was constructed using logistic regression and optimized through SVM and LASSO algorithms. Immune infiltration was evaluated using ssGSEA, and consensus clustering was used to define molecular subtypes. Experimental validation was conducted in a rat model of RIF using RT-qPCR, Western blotting, and immunohistochemistry.ResultsA total of five hub IHRDEGs (EDN1, HLA-G, MYC, HIF1A, and TLR2) were identified and incorporated into a diagnostic model that demonstrated strong predictive ability (AUC 0.7–0.9; sensitivity and specificity > 70–90%). These genes were significantly correlated with immune cell infiltration patterns. Subtype analysis revealed two distinct molecular clusters of RIF with different immunopathological features. Co-expression and regulatory interaction analyses further elucidated the involvement of hub genes in fibrotic mechanisms. Experimental validation confirmed the upregulation of hub genes at both mRNA and protein levels in the RIF model.ConclusionThis study uncovers the diagnostic and mechanistic significance of inflammation- and hypoxia-related genes in RIF. The five identified hub genes may serve as promising biomarkers and therapeutic targets. These findings provide novel insights into the immune-hypoxia interplay in renal fibrosis and offer a potential framework for early diagnosis and targeted treatment of CKD-related fibrosis.

The excessive accumulation of extracellular matrix (ECM) is a hallmark of renal interstitial fibrosis, its underlying mechanisms are incompletely understood. Here, we identify the E3 ubiquitin ligase Tripartite motif-containing protein 21 (Trim21) as a key regulator of this process. We found that Trim21 is upregulated in the tubular cells of fibrotic kidneys from both chronic kidney disease (CKD) patients and mouse models. Using tubular cell-specific Trim21 knockout mice, we demonstrated that Trim21 induction protects against ECM accumulation and renal fibrosis. Mechanistically, Trim21 binds to the N-terminal domain of Lysyl Oxidase-like 2 (Loxl2), promoting its ubiquitination and degradation, which in turn alleviates ECM deposition. Furthermore, we observed an upregulation of interferon-γ (IFN-γ) and its receptor in tubular cells during fibrosis. IFN-γ treatment increased Trim21 expression, reduced Loxl2 expression and renal fibrosis; critically, this protective effect was abolished in tubular-specific Trim21 knockout mice. In summary, our study defines a protective IFN-γ/Trim21/Loxl2 axis in the kidney, wherein IFN-γ signaling induces Trim21 to target Loxl2 for degradation, thereby mitigating fibrosis.

Tubulointerstitial fibrosis is the central pathological feature of hypertensive nephropathy, with cellular senescence being a key driver. Therefore, identifying therapeutic targets in senescent renal tubular epithelial cells is clinically important. The cytoplasmic FMR1-interacting protein (CYFIP) family, which comprises two evolutionarily conserved members, CYFIP1 and CYFIP2, plays crucial roles in neurological regulation. CYFIP2, a key member, is implicated in cytoskeletal dynamics and apoptosis within the nervous system; however, its renal expression pattern and function remain undefined. This study revealed that CYFIP2 expression was significantly upregulated in the renal cortex, particularly in the proximal tubules, of DOCA/salt-induced hypertensive mice, and was positively correlated with the extent of fibrosis. Consistently, CYFIP2 was highly expressed in the renal tubules of patients with hypertensive nephropathy, where its level inversely correlated with the estimated glomerular filtration rate (eGFR). Tubule-specific deletion of CYFIP2 attenuated hypertension-induced cellular senescence (reduced SA-β-gal, p53/p21, and SASP; increased Klotho) and mitigated renal dysfunction, collagen deposition, and epithelial‒mesenchymal transition (EMT). In vitro, CYFIP2 silencing alleviated TGF-β1-induced senescence and fibrosis in HK-2 cells. Mechanistically, CYFIP2 and p53 formed a positive feedback loop that promoted fibrosis by inhibiting the Hippo pathway and enhancing YAP nuclear translocation. The p53 agonist Nutlin-3a reversed the protective effect of CYFIP2 knockout, while the inhibitor Pifithrin-α mimicked this effect. These findings underscore the pivotal role of the CYFIP2/p53-Hippo/YAP axis in hypertensive renal injury, and identify CYFIP2 as a potential therapeutic target. CYFIP2/p53-Hippo signaling drives tubular senescence and renal fibrosis in hypertensive nephropathy.

Renal interstitial fibrosis (RIF) is a core pathological process in the progression of chronic kidney disease (CKD), but effective therapeutic drugs are currently lacking. Panax notoginseng saponins (PNS) exhibit potential anti-inflammatory and anti-fibrotic effects, yet their mechanism of action in RIF remains unclear. This study aims to investigate the ameliorative effects of Panax notoginseng saponins (PNS) on renal interstitial fibrosis in a rat model of chronic kidney disease (CKD) and to elucidate whether these effects are mediated through the regulation of the TLR4/NF-κB signaling pathway. A rat model of CKD was established, with experimental groups including a healthy control group, a model group, PNS treated group, TAK 242 group, LPS group and combination groups (PNS+TAK 242 and PNS+LPS). Renal pathology and fibrosis were evaluated by HE and Masson staining, while the expression of fibrosis markers and TLR4/NF κB pathway molecules was analyzed via RT qPCR and Western blot. (1) Compared with the model group, PNS treatment significantly alleviated renal tissue damage and reduced the fibrotic area, while also downregulating the gene and protein expression of fibrosis markers, TLR4 and Rel (which encodes NF-κB p65); (2) he TLR4 inhibitor TAK-242 exhibited anti-fibrotic effects similar to those of PNS and the combination of PNS and TAK-242 yielded the most pronounced therapeutic outcomes. PNS significantly alleviates renal interstitial fibrosis in the CKD model rats and its mechanism is associated with the inhibition of the TLR4/NF-κB signaling pathway, thereby downregulating the expression of downstream pro fibrotic factors.

Yupingfeng San extract ameliorates cisplatin induced renal interstitial fibrosis via IL-6/JAK/STAT3 mediated restoration of mitochondrial homeostasis.