Rationale & Objective Secondary hyperparathyroidism (SHPT) is a common health problem among patients on maintenance hemodialysis. SHR6508, an allosteric modulator of calcium-sensing receptor, is developed to reduce parathyroid hormone (PTH) secretion among Chinese hemodialysis patients with SHPT. This study aimed to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of SHR6508 administered intravenously. Study Design This was a multicenter, randomized, double-blind, placebo-controlled single and multiple ascending dose phase I trial. Setting & Participants This study was conducted at 18 sites in China. Hemodialysis patients who had serum intact PTH (iPTH) of 400−1300 pg/mL and corrected calcium (cCa) of ≥ 8.4mg/dL (2.1 mmol/L) were enrolled. Interventions Patients were randomized in a ratio of 4:1 to receive SHR6508 or placebo by intravenous injection after hemodialysis. Outcomes The primary outcomes are PK parameters and changes in iPTH and cCa. Results The plasma drug exposures (mean maximum plasma concentration, area under the concentration-time curve) increased proportionally with the dose after the administration of SHR6508. iPTH level declined markedly after a single dose of SHR6508 in all cohorts (5-30mg). Following multiple doses of 5-15 mg, the percentage of patients achieving a reduction in iPTH concentration of ≥30% from baseline to Week 2 (25.0%-90.9%) and Week 4 (36.4%-100.0%) in the 5mg, 10mg, and 15mg groups was higher compared to those (12.5% and 14.3%, respectively) observed in the placebo group. Treatment-emergent adverse events occurred in 41 (95.3%) SHR6508-treated patients and in all patients with placebo, most of which were mild and moderate. Limitations This study had a relatively small sample size and short treatment and follow-up period. Conclusions SHR6508 showed promising efficacy and safety in Chinese hemodialysis patients with SHPT. A starting dose at 5 mg for titration was the best dose and will be used in phase II study.

Extracellular vesicles (EVs) facilitate intercellular communication by traversing the extracellular matrix (ECM). However, their motility within fibrotic ECM and its role in fibrosis development remain unclear. We engineered stress-relaxing (SR) hydrogels of tunable stiffness (2, 50 kPa) through dynamic crosslinking of short peptide (WGG(KA)) and heparin to mimic normal and fibrotic ECM. Super-resolution nanoimaging and quantitative three dimensional (3D) single-particle tracking (SPT) of single EV were performed, and the motion dynamics was quantified. The interplay between EVs and ECM was further investigated, particularly its effects on fibroblast activation and renal fibrosis. It was identified that both normal and fibrotic kidney-derived EVs exhibited confined Brownian-like motion according to 3D SPT, with enhanced mobility in the stiffer (50 kPa) hydrogel. Notably, fibrotic tubule-derived EVs carried higher levels of integrin β6 (ITGB6), which reduced their mobility within the hydrogel-based ECM mimic, as confirmed by the restoration of motility upon ITGB6 blocking or digestion. This suggested that EV motility may be influenced by the interplay between ECM stiffness and the intrinsic properties of the EVs. Furthermore, enrichment of ITGB6 on fibrotic tubule-derived EVs promotes local retention, thereby increasing EV-fibroblast interaction and profibrotic signaling. This indicated the underappreciated role of EV in fibrosis related to its motility and its interplay with fibroblast in fibrotic niche. Our study provides new insights into the mechano-dependent mechanisms governing EV motility within the fibrotic ECM. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) play key roles in cell communication, but how they move through fibrotic tissue remains poorly understood. This study reveals that kidney-derived EVs exhibit confined Brownian-like motion within engineered hydrogels mimicking fibrotic extracellular matrix. We found that EVs from fibrotic tubules carry elevated integrin β6, which restricts their mobility and promotes pro-fibrotic signaling by increasing EV-fibroblast interaction. Our study provides new insights into the mechano-dependent mechanisms governing EV motility within the fibrotic ECM. This work provide a biophysical perspective for understanding EVs mediated pathological communication in fibrosis.

Acute kidney injury (AKI) arises from diverse insults that trigger distinct immune responses, and an integrative framework for intercellular communication is now emerging. Extracellular vesicles (EVs), membrane-enclosed particles carrying proteins, microRNAs, lipids, and metabolites, mediate crosstalk between renal parenchymal cells and immune effectors to shape inflammation and repair. This review examines three dimensions of EV biology in AKI. This review examines three dimensions of EV biology in AKI, applying the term ‘EV’ throughout in accordance with MISEV2023 guidance unless the cited primary study has experimentally established subtype origin. First, we outline the molecular basis of EV-mediated immune signaling by contrasting vesicular communication with soluble cytokine and cell-contact pathways, highlighting cargo stability, tissue tropism, and multi-signal integration as distinguishing features. Second, we describe how EV composition shifts after injury: tubular epithelial cells, podocytes, and endothelial vesicles become enriched in damage-associated patterns and pro-inflammatory microRNAs, whereas immune cell-derived EVs propagate or resolve inflammation depending on polarization and disease phase. Third, we compare vesicular signaling across four AKI etiologies (allograft rejection, sepsis, nephrotoxicity, and ischemia-reperfusion), noting that EV cargo, cellular origin, and immune targets differ markedly by insult type and evolve through early, peak, and reparative phases. Advances in single-vesicle proteomics, intravital imaging, and kidney organoid systems now enable functional dissection of EV heterogeneity at unprecedented resolution. Key gaps remain: the limited mechanistic definition of dendritic cell- and T cell-derived EVs in non-transplant settings, the underdeveloped vesicular framework for renal ischemia-reperfusion, and the absence of standardized clinical assays. Addressing these limitations is essential for translating mechanistic insights into etiology-stratified diagnostics and stage-matched immunomodulatory interventions.

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease worldwide and diabetes predisposes patients to pruritus. Anrikefon is a novel selective peripherally restricted kappa-opioid receptor agonist. This post hoc analysis utilized data from phase 3 anrikefon-302 study to investigate the efficacy and safety of anrikefon in the treatment of diabetic hemodialysis patients with pruritus. This is a post hoc analysis of data collected in a randomized, placebo-controlled phase 3 study. Diabetic hemodialysis patients were included (anrikefon n = 67 and placebo n = 79). The percentage of patients achieving at least a 4-point or 3-point reduction in weekly mean 24 hour worst itching intensity numerical rating scale (WI-NRS) score from baseline to week 12 were analyzed. The changes in itch related quality of life from baseline using the Skindex-10 and 5-D itch scales were also compared. The baseline demographics and characteristics were generally similar in the individual placebo and anrikefon treatment arms. Interestingly, significantly more patients reported a clinically meaningful ≥ 4-point (29.9

Cyclin-dependent kinase 12 (CDK12) has been identified as a susceptibility locus for kidney function, but its role in chronic kidney disease (CKD) remains unclear. We generated tubule-specific CDK12 knockdown and overexpression mice and establish CKD models via adenine-induced and unilateral ureteral obstruction. We assessed renal injury, lipid metabolism, and transcriptional alterations using histology, functional assays, full-length transcriptome sequencing, and mechanistic rescue experiments. We detected significant reduction of CDK12 expression in renal tubular epithelial cells in human patients and experimental chronic kidney disease models. We find tubule-specific CDK12 knockdown exacerbates renal dysfunction, fibrosis, and lipid accumulation, whereas CDK12 overexpression confers protection. Mechanistically, CDK12 deficiency induces intronic polyadenylation of NCEH1 (neutral cholesterol ester hydrolase 1), resulting in reduced NCEH1 expression and cholesteryl ester accumulation. Restoring NCEH1 partially rescues lipid dysregulation and renal injury, identifying it as a key downstream effector. This study reveals that CDK12 protects against CKD progression by suppressing NCEH1 intronic polyadenylation and maintaining lipid homeostasis. The CDK12-NCEH1 axis represents a previously unrecognised mechanism linking transcriptional regulation to renal lipotoxicity and fibrosis, and may provide a potential therapeutic target.

Sepsis-induced acute kidney injury (S-AKI) is a life-threatening condition driven by excessive immune inflammation, and effective treatments remain lacking. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEV) have been demonstrated to possess potent immunomodulatory activity. This study aimed to investigate the role and underlying mechanism of MSC-sEV in S-AKI. We established in vivo and in vitro models of S-AKI and employed techniques such as small RNA sequencing, transcriptome sequencing, luciferase reporter assays, and engineered gene editing to validate therapeutic efficacy and elucidate mechanisms. Results demonstrated that in S-AKI, MSC-sEV homed to injured kidneys and were internalized by renal tubular epithelial cells, significantly ameliorating renal damage and improving survival rates. Mechanistically, MSC-sEV delivered miR-125a-5p to target and inhibit TNFR2 expression, thereby blocking TNF-driven pyroptosis mediated by the NF-κB/NLRP3 signaling pathway. Furthermore, engineered modification with the EXOMotif GGAG significantly enhanced MSC-sEV delivery of miR-125a-5p and inhibition of TNFR2. In conclusion, this study demonstrates that MSC-sEV represent a promising drug delivery vehicle with substantial targeted therapeutic potential for S-AKI.

Cardiovascular-kidney-metabolic (CKM) syndrome is a recently defined clinical entity that encompasses cardiovascular disease (CVD), chronic kidney disease (CKD) and metabolic disorders. It has emerged as a growing public health concern that adversely affects the quality of life and imposes a substantial burden on human health. Sodium-glucose cotransporter 2 inhibitor (SGLT-2i) is a novel class of oral hypoglycemic agent with novel insulin-independent mechanism. In the last decade, published studies highlight its substantial effects on renal and cardiovascular outcomes. SGLT-2i is recommended for patients with stages 2–4 CKM syndrome, particularly those with CKD or diabetes to delay disease progression, and improve long-term clinical outcomes. This review comprehensively summarizes the current clinical evidence and elucidates the underlying mechanisms of SGLT-2i in CKM syndrome. Glycosuria and natriuresis, the primary effects of SGLT2 inhibition, play a pivotal role in improving glycemic control, reducing body weight, and lowering blood pressure. These initial effects trigger a cascade of downstream mechanisms: hemodynamic optimization via interstitial fluid reduction, enhanced cardiac efficiency through ketogenesis, and attenuation of inflammation and oxidative stress. Additional systemic benefits include increased fatty acid utilization, reduced hyperuricemia and stimulated erythropoiesis, thereby generating a network of interrelated therapeutic benefits in CKM syndrome. The pleiotropic effects of SGLT-2i position it as a highly promising therapeutic strategy for CKM syndrome. A deeper understanding of underlying mechanisms will better inform the application of SGLT-2i for this newly defined condition and guide optimal treatment strategies.

Rationale & Objective:Secondary hyperparathyroidism (SHPT) is a common health problem among patients receiving maintenance hemodialysis. SHR6508, an allosteric modulator of calcium-sensing receptors, was developed to reduce parathyroid hormone secretion among Chinese hemodialysis patients with SHPT. This study aimed to evaluate the safety, pharmacokinetics, and pharmacodynamics of SHR6508 administered intravenously. Study Design:This was a multicenter, randomized, double-blind, placebo-controlled single and multiple ascending dose phase 1 trial. Setting & Participants:This study was conducted at 18 sites in China. Hemodialysis patients who had serum intact parathyroid hormone (iPTH) concentration 400-1,300 pg/mL and corrected calcium ≥8.4 mg/dL (2.1 mmol/L) were enrolled. Interventions:Patients were randomized in a 4:1 ratio to receive SHR6508 or placebo by intravenous injection after hemodialysis. Outcomes:The primary outcomes were pharmacokinetic parameters and changes in iPTH and corrected calcium concentrations. Results:The plasma drug exposures (mean maximum plasma concentration, area under the concentration-time curve) increased proportionally with the dose after the administration of SHR6508. iPTH level declined markedly after a single dose of SHR6508 in all cohorts (5-30 mg). After multiple doses of 5-15 mg, the percentage of patients achieving a reduction in iPTH concentration ≥30% from baseline to week 2 (25.0%-90.9%) and week 4 (36.4%-100.0%) in the 5, 10, and 15 mg groups was higher than those observed in the placebo group (12.5% and 14.3%, respectively). Treatment-emergent adverse events, which were mostly mild or moderate, occurred in 41 (95.3%) SHR6508-treated patients and in all patients treated with placebo. Limitations:This study had a relatively small sample size and short treatment and follow-up period. Conclusions:SHR6508 showed promising efficacy and safety in Chinese hemodialysis patients with SHPT. A starting dose of 5 mg for titration was the best dose and will be used in the phase 2 study.

Mesenchymal stem cell-derived exosomes (MSC-Exos) have shown considerable therapeutic potential in regenerative medicine. However, the biosafety profile of these exosomes following repeated administration has not been adequately characterised, and this knowledge gap continues to hinder clinical translation. Human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Exos) were produced on a xeno-free platform by replacing fetal bovine serum (FBS) with human platelet lysate (hPL). A relatively comprehensive and integrated repeated-dose preclinical biosafety profile assessment was then conducted using polyethylene glycol (PEG)-Liposomes as reference nanovesicles. The assessment included pharmacokinetic and distribution analyses using DiD labelling, haematological cytology testing, quantitative measurement of inflammatory cytokines and chemokines, histopathological scoring, and RNA sequencing. In this study, the safety assessment revealed that: (1) hucMSC-Exos primarily accumulated in the liver and spleen and exhibited an approximately 4-h circulation time; (2) repeated intravenous administration of hucMSC-Exos for 30 days did not result in overt systemic inflammation, and the evaluated haematological and biochemical parameters remained within the normal range; (3) RNA sequencing showed that hucMSC-Exos avoided immune pathway activation (e.g., IL-17/antigen presentation) triggered by PEG-Liposomes, instead enriching complement-coagulation cascades (e.g., C1qc, C6 upregulation) and metabolic pathways (steroidogenesis, retinol metabolism). Together, these findings suggest that hucMSC-Exos have a favourable biosafety profile in a murine model and support further preclinical evaluation for regenerative medicine applications. This study suggests that repeated intravenous administration of hucMSC-Exos confers a relatively favourable biosafety profile in a murine model and provides preliminary preclinical evidence for further investigation towards clinical translation.

Acute kidney injury (AKI) remains a major clinical challenge due to the lack of effective interventions. While mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) show therapeutic promise for AKI, their exact mechanisms are largely to be understood. Human umbilical cord-derived MSC-EVs were isolated, characterized, and tested in a murine bilateral renal ischemia reperfusion injury (bIRI) model and in hypoxia/reoxygenation (H/R) treated tubular epithelial cells in vitro. Integrated transcriptomic, miRNA, and biochemical analyses were performed to elucidate the metabolic pathways and molecular mechanisms underlying the renoprotective effects of MSC-EVs. MSC-EVs preferentially targeted injured kidneys and significantly improved renal function, ameliorated tubular injury, and suppressed inflammation in IRI-AKI. RNA sequencing and targeted metabolomics revealed substantial dysregulation of steroid metabolism after IRI, marked by activation of the cholesterol 25-hydroxylase (CH25H)/25-hydroxycholesterol (25HC) axis. Importantly, accumulated 25HC induced lipid peroxidation and ferroptosis in tubular epithelial cells. MSC-EVs treatment reversed these pathological changes by downregulating CH25H, lowering 25HC levels, and restoring redox homeostasis. miRNA profiling further identified miR-26b-5p as a key MSC-EVs cargo that directly targets the 3′UTR of CH25H mRNA to repress its expression. Notably, inhibiting miR-26b-5p within EVs abrogated their ability to suppress CH25H/25HC-driven ferroptosis, thereby demonstrating its essential role in the metabolic and cytoprotective actions of MSC-EVs. Our findings unveil the CH25H/25HC axis as a key metabolic checkpoint governing tubular ferroptosis in ischemic AKI. MSC-EVs deliver miR-26b-5p to suppress this axis, thereby rectifying oxysterol metabolism and preventing ferroptosis.

BACKGROUND:This study aimed to evaluate the efficacy and safety of ferric citrate tablets in Chinese patients with hyperphosphatemia undergoing maintenance hemodialysis (MHD). METHODS:In this phase III, multicenter, randomized, open-label, non-inferiority trial, patients with hyperphosphatemia on maintenance hemodialysis were randomly assigned to receive either ferric citrate or sevelamer carbonate tablets for 12 weeks. The primary endpoint was the change in serum phosphorus levels from baseline to week 12, with a non-inferiority margin of 0.32 mmol/L. Secondary endpoints included changes in serum calcium, intact parathyroid hormone, and safety assessments. RESULTS:A total of 239 patients were randomized to the ferric citrate group (n = 119) or the sevelamer carbonate group (n = 120). The mean change in serum phosphorus levels was -0.70 ± 0.50 mmol/L in the ferric citrate group and -0.61 ± 0.59 mmol/L in the sevelamer carbonate group (least squares mean difference, -0.09 mmol/L; 95% CI, -0.24 to 0.05 mmol/L; non-inferiority margin, 0.32 mmol/L). No significant inter-group differences were found in the percentage of patients achieving target phosphorus levels (49.09% vs. 48.28%, p = 0.902). Ferric citrate significantly improved iron-related parameters and hemoglobin levels. Most treatment-emergent adverse events were mild, with gastrointestinal disorders being the most common. CONCLUSIONS:Ferric citrate tablets were non-inferior to sevelamer carbonate in reducing serum phosphorus levels in hyperphosphatemia patients on maintenance hemodialysis, with the added benefit of improving iron-related anemia and a favorable safety profile.

Introduction: Enarodustat is an oral HIF-PHI for the treatment of chronic kidney disease anemia. Methods: This phase 3, multicenter, randomized 24-week study assessed enarodustat's noninferiority to rHuEPO for treating hemodialysis-dependent CKD (HD-CKD) anemia. Overall, 100 ESAs-treated patients were randomized 1:1 to enarodustat or rHuEPO for a 24-week treatment with dose adjustment every 4 weeks to maintain hemoglobin (Hb) within target range 100-120 g/L. The primary efficacy endpoint was the between-group difference in mean Hb over weeks 20-24 (evaluation period [noninferiority margin: -10 g/L]). Safety was assessed by treatment-emergent adverse events (TEAEs). Results: Of the 100 patients treated (enarodustat: 50; rHuEPO: 50), 93 completed the study. Demographic and baseline characteristics were comparable. During the evaluation period, the mean Hb level was 106.81 g/L in the enarodustat group and 99.68 g/L in the rHuEPO group. Enarodustat was noninferior to rHuEPO (least squares mean difference: 7.47 g/L [95% confidence interval: 4.17, 10.78]; p < 0.001). The mean Hb level in the enarodustat group remained within the target range throughout the treatment period, with a maintenance rate of 79.6% during weeks 20-24 versus 51.0% for rHuEPO. After switching from ESAs, the enarodustat group showed increased total iron-binding capacity, transferrin, and serum iron, decreased hepcidin by week 4, and increased RET% by week 2. TEAEs incidences were comparable (enarodustat: 90.0%, rHuEPO: 90.0%), with no additional safety concerns for enarodustat. Conclusions: Enarodustat was noninferior to rHuEPO for the treatment of anemia in HD-CKD patients, with good safety and tolerability over 24 weeks.

The plasma protein corona (PC) critically influences the in vivo fate of nanomedicines, yet its composition and impact on extracellular vesicles (EVs) remain poorly defined. Using a biomimetic circulation system, we characterized PC formation and modulation on two clinically relevant EV types: mesenchymal stromal cell-derived EVs (MSC-EVs) and HEK293F-derived EVs (293F-EVs). Under dynamic flow, both EV types acquired stable coronas, resulting in increased particle size and decreased surface charge. Proteomic profiling revealed a shared corona signature enriched in immunoglobulins, complements, and other plasma components. Functionally, PC formation enhanced macrophage uptake and triggered inflammatory activation, primarily via interactions between corona-bound immunoglobulins or complement C3 and their respective receptors. To disrupt this process, we developed a charge-shielding strategy using positively charged chitosan oligosaccharide (COS) to inhibit PC assembly. COS coating effectively neutralized EV surface charge and reduced opsonin adsorption and non-specific macrophage clearance, thereby reshaping EV biodistribution-limiting hepatic sequestration and enhancing delivery to extrahepatic organs. In a murine sepsis model, COS-modified MSC-EVs further improved renal and pulmonary outcomes and markedly increased survival. Collectively, these findings elucidate the molecular architecture and immunological impact of the EV-associated plasma PC and introduce a promising anti-corona strategy for engineering stealthier and more effective EV-based nanotherapeutics.

BACKGROUND:Renal interstitial inflammation (RII) is a frequent pathological feature in IgA nephropathy (IgAN), but its prognostic value remains uncertain. This study investigated the effect of RII on renal outcomes and developed a machine learning-based model incorporating RII for individualized prognosis. MATERIALS AND METHODS:We retrospectively analyzed 540 IgAN patients diagnosed by renal biopsy at Zhongda Hospital and the First People's Hospital of Huai'an (2012 - 2023). The endpoint was a ≥ 50% decline in eGFR or end-stage renal disease, with follow-up to June 2024. Predictors included demographics, clinical/laboratory parameters (blood tests, serum biochemistry, 24-hour urine protein), and histopathology (Oxford MEST-C and RII scores). Variable selection used random forest, extreme gradient boosting, artificial neural networks, and LASSO regression. A logistic regression model and nomogram were developed and validated internally and externally. RESULTS:Of 540 patients (mean age 40.8 years; 50.6% male), 273 were in the derivation, 117 in the internal validation, and 150 in the external validation cohort. Patients with progression had lower baseline serum albumin (p = 0.023), lower estimated glomerular filtration rate (eGFR) (p < 0.001), and higher systolic blood pressure (SBP) and proteinuria (all p < 0.001). In multivariate analysis, RIIS1 (odds ratio (OR) 4.16, 95% CI 0.91 - 24.51, p = 0.048) and RIIS2 (OR 6.80, 95% CI 0.98 - 54.49, p = 0.039) independently predicted adverse outcomes. Use of renin-angiotensin-aldosterone system inhibitors was protective (OR 0.34, p = 0.026), while higher SBP increased risk (OR 1.04, p < 0.001). The nomogram achieved C-indices of 0.91, 0.90, and 0.92 in the derivation, internal, and external validation cohorts, respectively. CONCLUSION:RII is an independent predictor of renal progression in IgAN. The developed model and nomogram may assist in individualized risk stratification.

BACKGROUND:Renal fibrosis (RF) is a progressive pathological process driven by chronic inflammation and Th17/Treg imbalance. Asiaticoside (AS), a triterpenoid compound from Centella asiatica (L.) Urb., exhibits anti-inflammatory and antifibrotic activities, though its molecular mechanism remains unclear. OBJECTIVE:This study aimed to investigate whether AS alleviates RF by targeting Signal transducer and activator of transcription 3 (STAT3) through a "bind to destabilize" mechanism to restore Th17/Treg homeostasis. METHODS:An integrated approach combining network pharmacology, transcriptomics, and multimodal experimental validation was applied. UUO mice were treated with AS (10, 50, 100mg/kg/d) for 10 days. Histopathology, RNA‑seq, flow cytometry, immunofluorescence, Luminex, qPCR, DARTS‑LC‑MS/MS, molecular docking/dynamics simulations and SPR were performed. Pharmacological interventions using Stattic (STAT3 inhibitor) and Colivelin (STAT3 agonist) were included to functionally validate the role of STAT3. RESULTS:Network pharmacology identified STAT3 as the core target, with Th17 differentiation as the key pathway. AS treatment significantly attenuated RF, improved renal function, and rebalanced Th17/Treg ratios in UUO mice, accompanied by reduced IL-17A and elevated IL-10. Transcriptomic analysis revealed enriched Th17 cell differentiation genes, validated by qPCR. DARTS-LC-MS/MS confirmed direct binding of AS to STAT3 and identified a peptide derived from the SH2 domain (residues 582-602), indicating conformational destabilization. SPR showed high affinity binding to both human and murine STAT3. Molecular docking and dynamics simulations demonstrated a "local anchoring-allosteric effect" mode within the SH2 domain. qPCR analysis showed that AS significantly inhibited the mRNA expression of both IL-17A and total STAT3 in the renal tissues of UUO mice. Immunofluorescence revealed reduced STAT3 and p-STAT3 expression in kidneys. STAT3 inhibitor Stattic mimicked AS's antifibrotic and Th17 suppressive effects, whereas agonist Colivelin exacerbated fibrosis and was partially rescued by AS. CONCLUSION:AS alleviates RF via a novel "bind to destabilize" allosteric degradation mechanism that directly targets the STAT3 SH2 domain. This interaction induces conformational instability, suppresses STAT3 activation and transcriptional activity, restores Th17/Treg homeostasis, and ultimately mitigates renal inflammation and fibrosis. Collectively, these findings establish a new therapeutic strategy for STAT3-driven fibrotic diseases.

Autosomal dominant tubulointerstitial kidney disease -UMOD is characterized by progressive renal interstitial inflammation and fibrosis. However, its underlying mechanisms remain unclear. Here, we identify a large ADTKD pedigree harboring a novel UMOD p.H36Y mutation. Using CRISPR/Cas9 technology, we generated a UmodH36Y/+ mouse model that recapitulates the key phenotypes observed in affected individuals, including renal dysfunction, cyst formation, and interstitial inflammation. Multi-omics analyses in kidneys from male UmodH36Y/+ mice revealed marked macrophage pyroptosis. Mechanistically, the Umod p.H36Y variant activated the amyloid precursor protein (App)-Cd74 axis which mediated the crosstalk between renal mutant tubular cells and macrophages. This axis sustains NF-κB pathway activation in macrophages, initiating pyroptosis and pro-inflammatory cytokine release. The same mechanism is recapitulated in the UMOD p.Trp31Cys cell model. Notably, Pharmacologic inhibition using ARN2966, a small-molecule App inhibitor, attenuated renal injury in male UmodH36Y/+ mice. Collectively, these findings uncover a targetable pathway in ADTKD-UMOD.

BACKGROUND:Renal tubular injury, one of the most critical events in diabetic kidney disease (DKD), plays a pivotal role in the progression of the disease. Metabolic reprogramming of renal tubular cells emerges as a prominent pathological feature, yet its underlying molecular mechanisms remain incompletely understood. METHODS:We established a streptozotocin-induced mouse model of diabetes. Metabolomic analysis was then used to characterise DKD-specific metabolic alterations. To test the functional consequence of a metabolic intervention, DKD mice received intraperitoneal injections of oxaloacetate (OAA). Furthermore, molecular docking and cellular thermal shift assays were used to elucidate the molecular mechanisms underlying OAA's effects on renal tubular injury, which were further validated in HK-2 cells exposed to high glucose. Finally, a specific pharmacological inhibitor was applied to study the relevant signalling pathway. RESULTS:Metabolomic profiling identified a marked decrease in OAA, a key tricarboxylic acid (TCA) cycle intermediate, in injured renal tubular cells. OAA supplementation significantly attenuated tubulointerstitial injury, as evidenced by reduced tubular cell damage, fibrosis, and macrophage infiltration. Moreover, restored mitochondrial homeostasis was observed in DKD mice after OAA treatment. Mechanistically, we found that OAA inhibited prolyl hydroxylase domain 2 (PHD2), an essential regulator of hypoxia-inducible factor-1α (HIF-1α), thereby stabilising mitochondrial homeostasis. Furthermore, pharmacological inhibition of HIF-1α abolished the protective effects of OAA, confirming the involvement of the PHD2/HIF-1α axis. CONCLUSIONS:OAA ameliorates renal tubulointerstitial injury in DKD by restoring mitochondrial homeostasis through the PHD2/HIF-1α axis.

IntroductionVascular calcification (VC) is a prevalent and life-threatening complication of chronic kidney disease (CKD), yet the mechanisms by which hyperphosphatemia drives VC remain incompletely understood. This study investigates the role of endothelial cells (ECs)-derived exosomal microRNAs in mediating osteogenic differentiation of vascular smooth muscle cells (VSMCs) under high phosphate (HP) conditions.MethodsA CKD-VC mouse model was established using a HP and high-adenine diet. Exosomes (Exos) were isolated from ECs cultured under normal or HP conditions. The effects of Exos on calcification of VSMCs were evaluated using in vitro co-culture systems and in vivo administration. miRNA sequencing, dual-luciferase reporter assays, and loss/gain of function experiments were performed to identify key exosomal miRNAs and their downstream targets. Western blotting, qRT-PCR, and histological analyses were used to assess molecular and pathological changes.ResultsHP-stimulated ECs released Exos (HP-Exos) that were internalized by VSMCs and significantly promoted VC in both in vitro and in vivo models. miRNA sequencing identified miR-299-3p as significantly upregulated in HP-Exos. Functional studies demonstrated that exosomal miR-299-3p directly targeted membrane-associated RING-CH3 (MARCH3), leading to activation of the p-JAK2/STAT5 signaling pathway. This cascade subsequently upregulated osteogenic markers and downregulated contractile marker, thereby promoting osteogenic differentiation of VSMCs. Knockdown of miR-299-3p in vivo attenuated VC in CKD mice.DiscussionThese findings reveal a previously unrecognized mechanism by which HP drives CKD-VC through ECs-derived exosomal miR-299-3p. The miR-299-3p/MARCH3/p-JAK2/STAT5 signaling axis represents a critical regulatory pathway in VC pathogenesis and offers a potential therapeutic target for this life-threatening complication of CKD.