Journal of the American Society of Nephrology

Introduction: HNF4A is required for proximal tubule maturation during kidney development, but its role in maintaining proximal tubule identity in the adult kidney has not been defined. Following acute kidney injury, Hnf4a expression is rapidly suppressed in proximal tubule cells, coinciding with loss of mature epithelial features and activation of injury-associated transcriptional programs. It remains unknown whether HNF4A loss is sufficient to drive injury-associated transcriptional changes. Methods: We conditionally deleted Hnf4a in mature proximal tubules using Slc34a1Cre in mice and analyzed the consequences of Hnf4a loss in adult kidneys. To identify genes directly regulated by HNF4A, we performed proximal tubule-specific transcriptional profiling together with genome-wide mapping of HNF4A binding sites using CUT&RUN. Results: In Hnf4a mutant kidneys, HNF4A protein initially persisted in proximal tubules but was progressively lost from convoluted proximal tubule cells. Loss of Hnf4a resulted in downregulation of proximal tubule-specific transport and metabolic genes, accompanied by reactivation of developmental and injury-associated genes. CUT&RUN analysis revealed that HNF4A directly regulates genes predominantly involved in solute transport and metabolic processes. Conclusions: These findings identify HNF4A as a key regulator of proximal tubule identity and homeostasis in the adult mouse kidney. Genetic loss of Hnf4a in mature proximal tubules leads to loss of mature proximal tubule gene expression and activation of injury-associated transcriptional programs, implicating Hnf4a suppression as a potential contributor to maladaptive repair after kidney injury.

Nephrotic syndrome, the leading cause of chronic kidney disease worldwide, is associated with injury and eventual loss of podocytes, the specialized epithelial cells that form the final layer of the kidney's filtration apparatus. The progression from injury to loss is largely irreversible. However, some forms of nephrotic syndrome undergo remission, suggesting that injured podocytes may retain a capacity for repair, the structural basis of which remains unknown. Podocytes respond to injury by the stereotypical morphological change known as foot process effacement (FPE), which can be visualized using transmission electron microscopy. Using modified ultrastructure expansion microscopy (U-ExM) protocol combined with super-resolution microscopy, we discovered that injured podocytes exhibit a three-stage progression of FPE maturation, with kinetics determined by the degree of actomyosin contractility. Through longitudinal study of adriamycin-induced nephropathy in mice, we identified three sequential stages of actomyosin reorganization within the sarcomere-like structures (SLSs) that define the injury response: focal infiltration of myosin IIA into synaptopodin-rich foot processes (Stage 1), disordered intermingling of synaptopodin/myosin IIA (Stage 2), and the formation of highly organized periodic contractile arrays oriented perpendicular to the direction of capillary blood flow (Stage 3). Longitudinal quantification revealed predictable temporal dynamics, with mature Stage 3 predominating by day 7-9 post-injury. To determine whether this sequence is conserved in human disease, we analyzed kidney biopsies from patients with minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and diabetic nephropathy. The same three stages were present across all four diseases, and their distribution tracked disease course: acute podocytopathies exhibited heterogeneous early-stage patterns, whereas chronic injuries converged on uniform, mature SLS organization. These findings demonstrate that podocyte injury is a graded, potentially reversible process rather than a binary switch. They identify structured actomyosin remodeling as a conserved wound response across mechanistically distinct kidney diseases and suggest that therapeutic strategies targeting specific stages of this progression could alter the trajectory of diverse glomerular diseases.

INTRODUCTION RNA editing has been implicated in endogenous double-stranded RNA (dsRNA) sensing and inflammatory disease, but its prevalence, genetic regulation, and consequences in diseased human kidney tissue have not been systematically characterized. Because ADAR enzymes edit multiple neighboring adenosines often in the same transcript, analyzing these sites holistically (as "clusters") may reveal effects missed by single-site analysis. METHODS We profiled both single-site and cluster A-to-I RNA editing in the kidneys of 215 participants from the Nephrotic Syndrome Study Network with focal segmental glomerulosclerosis or minimal change disease who had microdissected glomerular and/or tubulointerstitial RNA-seq and blood genome sequencing. We tested single-site and cluster editing association with estimated glomerular filtration rate, proteinuria, and an interferon stimulated gene expression score. To discover the genetic determinants of editing, we conducted mapping of both single-site, cis-editing QTL and cluster-level editing QTLs (cledQTLs). We then tested cledQTLs for colocalization with kidney eQTLs and kidney-relevant GWAS. RESULTS Greater cluster mean editing in tubulointerstitium was associated with lower interferon-stimulated gene activity (P = 4.81 x 10-9), lower UPCR (P = 0.01) and higher eGFR (P = 8.52 x 10-5). Genetic mapping identified 290 glomerular and 473 tubulointerstitial single-site edQTLs, as well as 21 glomerular and 51 tubulointerstitial cledQTLs. We identified 10 colocalized signals between cledQTL and GWAS and 14 between cledQTL and eQTL. Nine of 51 tubulointerstitial cledQTL clusters were individually associated with eGFR in NEPTUNE. CONCLUSION These results identify A-to-I RNA editing as a measurable and partly genetically regulated molecular phenotype in proteinuric kidney disease and nominate clustered editing of tubulointerstitial transcripts as a putative contributor to attenuated immune activity and higher kidney function. Cluster-level analysis identified additional genetically regulated editing patterns and colocalized signals not detected at individual sites, highlighting the added value of analyzing nearby editing sites as clusters.

Background: Genomic reassessment may reveal clinically relevant diagnoses in patients with young-onset kidney failure despite established clinical diagnostic labels. We evaluated this approach after excluding clinically apparent polycystic kidney disease (PKD). Methods: Among 1,139 patients receiving maintenance dialysis at participating Japanese facilities, 355 had initiated dialysis at age [≤]50 years. After excluding 17 patients with clinically apparent PKD, 108 of 338 eligible patients underwent whole-genome sequencing through voluntary, nonrandom enrollment. Analysis included 465 nuclear candidate genes, mitochondrial DNA, and copy-number/structural variants. Clinically concordant diagnoses were adjudicated using integrated clinical and genetic evidence, with a separate pathogenic/likely pathogenic (P/LP)-supported subset. Results: Diagnoses were identified in 10/108 participants (9.3%; 95% confidence interval, 5.1-16.2), comprising seven renal and three systemic/metabolic diagnoses. Nine diagnoses were P/LP-supported (8.3%; 95% confidence interval, 4.4-15.1). The remaining diagnosis was phenotype-based clinical Dent disease associated with a CLCN5 variant of uncertain significance. Diagnoses occurred across diabetic kidney disease, nephrosclerosis, chronic glomerulonephritis, unknown-cause, and other clinical categories. In a post hoc analysis excluding three participants with low target coverage, the integrated and P/LP-supported proportions were 9/105 (8.6%) and 8/105 (7.6%). Six exploratory findings were excluded from both diagnostic numerators. Gitelman syndrome was included as a clinically manifest renal disorder, although its contribution to kidney failure remained uncertain. Conclusions: Integrated genomic assessment can uncover renal and systemic/metabolic diagnoses across conventional labels in young-onset kidney failure after exclusion of clinically apparent PKD. Nonrandom enrollment and variable sequencing coverage limit generalizability and interpretation of negative results.

HNF1B is a transcription factor required for proximal tubule (PT) specification during kidney development, but whether it is also required to maintain PT identity after differentiation remains unknown. Using PT-specific genetic deletion in mice, we found that loss of Hnf1b in differentiated PT cells causes cyst formation and early postnatal lethality. PT-specific transcriptomic analysis revealed downregulation of PT-specific gene programs, including Hnf4a and PT-enriched transport and metabolic genes. Strikingly, Hnf1b-deficient PT cells ectopically activated podocyte-specific genes, including Wt1 and Nphs1, demonstrating that PT cells retain the capacity to engage alternative nephron segment programs when identity-stabilizing mechanisms are disrupted. In addition, loss of Hnf1b disrupted epithelial integrity, as evidenced by reduced epithelial adhesion gene expression and induction of mesenchymal markers. Wnt/{beta}-catenin signaling was also aberrantly activated, suggesting broader dysregulation of epithelial homeostasis. These findings establish HNF1B as a critical post-specification regulator of PT identity that sustains PT-specific transcriptional programs and actively suppresses alternative segmental identity programs.

Renal cysts are categorized as non-pathogenic simple cysts and pathogenic malignant cysts based on their pathophysiological status. Cyst formation is divided by cyst initiation and cyst progression/promotion. Pathogenic cysts are thought to be developed through continuous initiation followed by progression until pathogenic status is achieved. Although many genetic and environmental factors are identified to cause pathogenic cyst formation, the mechanisms that discriminate cyst initiation and progression are poorly understood. Using genetic mutation models of ETV transcription factors, ETV1, ETV4, and ETV5, and a pharmacological inhibitor of hedgehog signaling, cyclopamine, we identified one of the mechanisms regulating cyst initiation and progression. Nephron specific deletion of ETV4 and ETV5 initiated cyst formation. However, cyst initiation did not continue as animals grow, and a limited number of the initial cysts underwent further growth. Additional deletion of ETV1 was required for continuous initiation in addition to promotion of cyst growth. Furthermore, administration of cyclopamine attenuated promotion of cyst progression but had little effect on cyst initiation. Therefore, we provide evidence that cyst initiation and progression is genetically and molecularly distinct and can be modulated. This information provides new insight into how to control renal cyst initiation and progression and can be used to suppress pathogenic cyst growth.

Banff acute lesion scores underpin histologic classification of kidney allograft biopsies; however, biomarker studies rely on second-order associations with diagnostic categories that introduce confounding. We quantified the first-order relationships between Banff acute lesion scores and the validated urinary cell three-gene rejection signature. In 354 biopsy-urine pairs, three-gene signature scores computed using a locked regression equation incorporating absolute copy numbers of CD3E mRNA, CXCL10 mRNA, and 18S rRNA in urinary cell RNA-were related to glomerulitis (g), peritubular capillaritis (ptc), interstitial inflammation (i), and tubulitis (t). Signature scores rose monotonically with Banff acute lesion severity, with 1.5 to 1.8-fold higher odds of more severed g, ptc, i, and t (all P<0.0001), and showed good calibration. Associations remained robust for composite microvascular (g+ptc) and tubulointerstitial (i+t) indices and were strongest for severe g and t, supporting this signature as a noninvasive, quantitative readout of acute rejection pathology with immediate diagnostic applicability.

BackgroundAcute kidney injury (AKI) frequently progresses to chronic kidney disease (CKD), yet mechanisms governing this transition remain poorly understood. The endocannabinoid system (ECS), particularly cannabinoid-1 receptor (CB1R), regulates inflammation and metabolism in various organs, but its role in post-AKI maladaptive repair is less established. MethodsWe analyzed CB1R expression in kidney biopsies from pre- and post-transplant recipients and in murine AKI models (ischemia-reperfusion injury [IRI] and folic acid [FA]-induced AKI). Peripheral CB1R blockade was evaluated in FA-AKI model and in human primary kidney proximal tubule cells (hKPTCs). Spatial metabolomics, semi-targeted metabolomic profiling, and gene and protein expression characterized molecular mechanisms. ResultsCB1R expression was increased in kidneys undergoing maladaptive repair in both humans and mice, but remained unchanged during acute injury. In the FA-induced AKI model, the ECS showed stage-specific alterations, with temporal and spatial fluctuations in endocannabinoid levels and their enzymatic regulators. Peripheral CB1R blockade during the repair phase preserved kidney function, reduced injury, and maintained systemic glucose homeostasis. Metabolomic and molecular analyses revealed that CB1R blockade restored dysregulated arginine metabolism and reduced AKT/NF-{kappa}B-p65 pathway in post-AKI kidneys, linking CB1R activation to inflammatory signaling. In hKPTCs, 2-AG-induced activation of CB1R increased VCAM1 expression, a failed-repair marker, while its antagonism reduced TNF/2-AG-induced expression of pro-inflammatory adhesion molecules, chemokines, cytokines, and arginine metabolism enzymes. ConclusionsCB1R overactivation drives AKI-to-CKD progression by promoting inflammatory signaling and metabolic dysregulation. Peripheral CB1R blockade during the repair phase represents a novel therapeutic strategy to prevent maladaptive repair and CKD development after AKI. These findings establish CB1R as a phase-specific therapeutic target for post-AKI intervention. Translational StatementPeripheral CB1R antagonists offer a first-in-class therapeutic strategy to halt progression from acute kidney injury (AKI) to chronic kidney disease (CKD) by selectively targeting maladaptive tubular repair. By blocking CB1R signaling specifically in the kidney, these agents attenuate inflammation, metabolic dysregulation, and fibrogenic pathways that drive failed repair, while sparing central nervous system CB1R and thereby minimizing neuropsychiatric adverse effects. This phase-specific, peripherally restricted approach supports the development of peripheral CB1R antagonists as a viable translational therapy to improve long-term renal outcomes after AKI.

Introduction: Autosomal-dominant tubulointerstitial kidney disease (ADTKD) is characterized by chronic kidney disease (CKD) with an average age of end-stage renal disease (ESRD) of approximately 45 years, bland urinary sediment, the absence of proteinuria and autosomal dominant inheritance. While several causative genes have been found, there remain families in whom no molecular diagnosis has been identified (ADTKD-NMD). Methods: We identified BICC1 truncating variants in several families with ADTKD-NMD in the Wake Forest Rare Inherited Kidney Disease Registry and then screened families in our database and other referred families for BICC1 truncating variants. We performed segregation analysis and characterized affected individuals for clinical and histopathologic phenotypes. We analyzed oligomer formation of BICC1 mutants with wild-type BICC1-, ANKS3- and ANKS6 proteins through co-immunoprecipitation and Western blotting, and we tested for posttranscriptional regulation of the BICC1 target mRNA, Dand5, in a Luciferase reporter assay. Results: We found 6 heterozygous truncating mutations in BICC1 segregating with the ADTKD phenotype in 8 independent pedigrees worldwide. Affected individuals developed kidney failure in the 6th to 7th decade of life that was characterized pathologically by tubular atrophy and interstitial fibrosis. The truncated gene products localized to cytoplasmic bodies and demonstrated various degrees of self-association or binding to the known interaction partners, ANKS3 and ANKS6. While the wild-type BICC1 gene product acts as a posttranscriptional repressor of target mRNAs, all truncation variants exhibited increased expression of substrate mRNA. Conclusions: Truncating variants in BICC1 are a novel cause of ADTKD, segregating with the disease phenotype and upregulating BICC1 target gene expression through a dominant-negative- or a gain-of-function mode of action.

Wnt/{beta}-catenin signaling is a critical pathway that regulates nephron progenitor renewal versus differentiation as well as nephron patterning. In addition to its role as a transcription co-factor, {beta}-catenin also functions as a structural component of adherens junctions, where it interacts with cadherins to link cell-cell contacts to the cytoskeleton. However, the relationship between the nuclear and junctional localization of {beta}-catenin during vertebrate nephron development remains poorly understood. To define how endogenous {beta}-catenin localization changes during nephrogenesis, we optimized an accelerated-turnover {beta}-catenin chromobody for live imaging in Xenopus embryos. Using in vivo imaging of Xenopus pronephric development, we visualized endogenous {beta}-catenin within the nuclear, cytoplasmic, and junctional compartments. Across successive developmental stages, {beta}-catenin became progressively enriched at epithelial junctions during nephron maturation while remaining abundant within nuclear and cytoplasmic compartments. Quantitative analyses indicate that epithelial maturation is accompanied by coordinated expansion and partitioning of multiple intracellular {beta}-catenin pools rather than a simple redistribution from nuclear to junctional compartments.

Introduction: Mitochondrial DNA (mtDNA) is not routinely analyzed in inherited kidney disease. We evaluated mtDNA variation in families who remained genetically unresolved despite extensive testing. Methods: We reviewed pedigrees from the Wake Forest-Charles University Rare Inherited Kidney Disease Registry to identify genetically unresolved families with suspected maternal inheritance, performed mtDNA genotyping, clinically characterized variant carriers, and functionally evaluated disease-associated mitochondrial variants. Results: Among 33 families with evidence of maternal inheritance, 18 (55%) carried one of seven disease-associated mtDNA variant types, including homoplasmic recurrent single-nucleotide insertions in the second light-strand promoter (LSP2; 9 families), novel MT-TW and MT-TL2 variants (2 and 1 families, respectively), and previously reported MT-TF and heteroplasmic MT-ND5 variant (5 and 1 families, respectively). In 16 families, variants occurred on distinct haplotypes, consistent with independent mutational events and rapid enrichment to homoplasmy across generations. Maternal transmission was strongly supported, with below-normal kidney function observed in 54/60 (90%) offspring of affected mothers versus 1/17 (6%) offspring of affected fathers (p = 1.23 x 10e-11). Pathogenicity was further supported by predicted deleterious structural effects and functional evidence of impaired mitochondrial transcription and translation, respiratory chain deficiency, and CoQ10 depletion. Affected individuals predominantly presented with chronic tubulointerstitial kidney disease, occasionally accompanied by gout and only sporadically with extrarenal manifestations. The rate of kidney disease progression appeared to vary both between and within families. Overall, 109/119 genetically affected individuals or obligate at-risk carriers were clinically affected; most unaffected carriers were younger than 45 years of age. Clinical status was unavailable for an additional 66 obligate at-risk carriers. Conclusions: These findings establish the physiological relevance of the LSP2 promoter, support routine assessment of the mitochondrial genome in inherited kidney disease, and highlight mtDNA variants as an important cause of familial and sporadic tubulointerstitial kidney disease of previously unexplained etiology.

Biological sex is an important determinant of kidney disease susceptibility and outcomes. The epigenetic modifier KDM6A is an X chromosome-expressed lysine demethylase and molecular scaffold that escapes X chromosome inactivation. Here, we compared the effects of deletion of KDM6A from kidney tubule epithelial cells in female and male mice (KDM6ATubKO). Knockout of KDM6A from tubule cells aggravated kidney fibrosis caused by unilateral ureteral obstruction (UUO) in female mice, whereas male mice were unaffected by KDM6A absence. Unexpectedly, female (but not male) KDM6ATubKO mice developed spontaneous glucosuria that, when stressed by ligation of one ureter, presented as polyuria and a Fanconi renotubular syndrome-like picture affecting the unobstructed kidney. Absence of KDM6A from tubule epithelial cells of female mice caused mitochondrial circularization, tubule cell vacuolization with focal atrophy and lymphoid infiltration, and diminished sodium/glucose cotransporter 2 (SGLT2). Spatial transcriptomics and untargeted metabolomics revealed that knockout of KDM6A in female mice caused a shift in gene programs and metabolic pathways indicative of tubule cell metabolic dysfunction. In male mice, transcripts of the Y chromosome-expressed gametolog of Kdm6a, Uty were present in tubule epithelial cells at levels comparable to Kdm6a and they were upregulated with UUO. In summary, KDM6A is essential for normal tubule epithelial cell homeostasis in females but not in males. KDM6A and UTY are a dynamically regulated X-Y gene pair with at least partial compensatory overlap in function necessary for the preservation of kidney health and stress tolerance. Graphical abstract. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/740137v1_ufig1.gif" ALT="Figure 1000"> View larger version (29K): org.highwire.dtl.DTLVardef@7d26a4org.highwire.dtl.DTLVardef@740972org.highwire.dtl.DTLVardef@1851f7org.highwire.dtl.DTLVardef@ad6485_HPS_FORMAT_FIGEXP M_FIG C_FIG

BACKGROUNDChronic renin-angiotensin system (RAS) inhibition activates renin cells and induces afferent arteriolar hypertrophy, a maladaptive vascular response that may contribute to nephrosclerosis-like renal injury. Although genetic or cell ablation approaches have shown that renin cells are required for this remodeling, no pharmacological strategy to restrain hyperactivated renin cells while preserving RAS inhibition benefits has been established. Natriuretic peptides (NPs) counteract RAS; however, whether NP signaling modulates renin cell activation and afferent arteriolar remodeling remains unclear. METHODSWe examined direct effects of atrial natriuretic peptide (ANP) on As4.1 renin-producing cells using reverse transcription-quantitative PCR, ELISA, and RNA sequencing (RNA-seq). We established a mouse model of long-term RAS inhibition using valsartan, an angiotensin II receptor blocker (ARB), and compared it with sacubitril/valsartan, an angiotensin receptor-neprilysin inhibitor (ARNI). Valsartan was matched between the ARB and ARNI groups. Renin cell activation, afferent arteriolar remodeling, and renal injury were evaluated using biochemical assays, histology, immunostaining, single-nucleus RNA-seq, and region-specific photo-isolation chemistry RNA-seq of afferent arteriolar/juxtaglomerular regions. RESULTSANP suppressed Ren1 expression and renin secretion in As4.1 cells; this effect was attenuated by a natriuretic peptide receptor A antagonist. RNA-seq demonstrated that ANP induced receptor-dependent remodeling of renin cell gene programs. In mice, long-term ARB treatment induced renin cell hyperactivation, expansion of renin-positive juxtaglomerular regions, afferent arteriolar hypertrophy, renal dysfunction, tubular injury markers, and fibrosis. ARNI increased plasma ANP levels and attenuated these pathological changes, despite a comparable blood pressure reduction. Single-nucleus transcriptomics revealed attenuation of tubular injury-associated cellular states and altered renin cell-associated mesenchymal programs with ARNI. Region-specific transcriptomics further demonstrated distinct molecular states in afferent arteriolar/juxtaglomerular regions between ARB- and ARNI-treated kidneys. Integrated transcriptomic analysis suggested that NP signaling converges on vascular regulatory programs in hyperactivated renin-expressing cells. CONCLUSIONSNP signaling acts as a pharmacologically augmentable modulator of maladaptive renin cell activation. ARNI attenuates renin cell hyperactivation, afferent arteriolar hypertrophy, and renal injury during long-term RAS inhibition, suggesting that neprilysin inhibition may preserve RAS blockade benefits while limiting renin cell-driven renal vascular remodeling.

While ultra-rare missense variants in UMOD cause highly penetrant autosomal dominant tubulointerstitial kidney disease, a more frequent UMOD T62P variant conveys intermediate risk with variable penetrance. To determine whether age or polygenic risk contributes to the variable penetrance of T62P, we combined genotype and phenotype data from 882,306 individuals across the UK Biobank (discovery cohort) and the All of Us and MyCode biobanks (validation cohorts). We also analyzed the impact of aging on uromodulin processing and cellular stress in stably transfected kidney tubular cells expressing wild-type or mutant UMOD. We compared the effects of the GPS on risk of CKD between T62P carriers and non-carriers and tested for the GPS-by-T62P interaction. The UMOD T62P variant was reproducibly associated with increased risk of CKD in an age-dependent manner. Compared to wild-type, clones of T62P-expressing cells exhibited a defective uromodulin maturation profile, causing endoplasmic reticulum retention and stress. We also observed significant T62P-by-GPS interaction, with T62P carriers in the top quintile of the GPS having over 5-fold higher risk of CKD compared to population average (OR 5.17, 95%CI: 2.94-9.08, P=1.0E-08). In summary, we demonstrate that the penetrance of kidney disease in T62P carriers is strongly modified by both age and polygenic risk.

Background: Chronic kidney disease (CKD) is a major risk factor for cardiovascular morbidity, promoting left ventricular hypertrophy (LVH) prior to overt heart failure. The mechanisms underlying early cardiac remodeling in CKD remain incompletely understood. The IL-23/Th17/IL-17A inflammatory axis has emerged as a key mediator of cardiovascular pathology; however, its role in CKD-associated cardiac remodeling remains unclear. This study aimed to elucidate the contribution of this pathway to the early cardiac changes in CKD. Methods: Using a 5/6 nephrectomy (5/6Nx) mouse model of CKD, we evaluated cardiac structure, mitochondrial function, and inflammatory signaling. Cardiomyocyte transcriptomes were analyzed by RamDA-seq to identify molecular alterations. Circulating cytokines were profiled longitudinally, and IL-17A neutralization experiments were performed to assess causality. In addition, serum IL-12p40 concentrations were measured in patients with CKD and correlated with their renal function and cardiac remodeling indices. Results: At 16 weeks post-5/6Nx, mice developed LVH with preserved systolic function, accompanied by increased oxidative stress and mitochondrial structural abnormalities, but without significant myocardial fibrosis. Transcriptomic analysis identified oxidative phosphorylation as the most significantly downregulated pathway in cardiomyocytes. Despite increased mitochondrial DNA copy number and elevated PGC-1 expression, ATP production and mitochondrial respiratory chain proteins were reduced, indicating mitochondrial dysfunction. Circulating IL-12p40 and IL-23 levels increased progressively, concurrent with expansion of splenic Th17 cells and elevated cardiac IL-17A expression. Recombinant IL-17A directly impaired mitochondrial respiration in cultured cardiomyocytes. In vivo, IL-17A neutralization attenuated LVH, reduced oxidative stress, and partially restored mitochondrial protein expression without improving renal function. In patients with CKD, serum IL-12p40 levels correlated inversely with estimated glomerular filtration rate and positively with left ventricular mass index, supporting clinical relevance. Conclusions: Activation of the systemic IL-23/Th17/IL-17A axis contributes to early CKD-associated cardiac remodeling by promoting oxidative stress and mitochondrial dysfunction. Circulating IL-12p40 may serve as a biomarker of cardiorenal remodeling, and the IL-23/IL-17A pathway represents a potential therapeutic target.

Primary cilia coordinate signaling pathways that regulate tissue homeostasis and development, and defects in cilia contribute to numerous ciliopathies. However, the transcriptional consequences of disrupting ciliary protein localization remain poorly defined. ARL13B is a cilia-enriched regulatory GTPase required for ciliary trafficking and signaling. The ARL13BV358A variant is undetectable in cilia yet retains known biochemical functions, providing a unique model to investigate the functions of ciliary ARL13B independently of ciliogenesis. To define transcriptional programs associated with loss of ciliary ARL13B, we generated two independent Arl13bV358A/V358A kidney epithelial cell lines and matched rescue lines. The ARL13BV358A mutation did not affect ciliation frequency or cilia length but altered ciliary protein composition, including loss of ARL3 and INPP5E localization and increased accumulation of GPR161 and TULP3. RNA sequencing revealed expression changes in genes associated with ciliary biology, mechanotransduction, epithelial organization, and kidney-related phenotypes. Despite similar ciliary phenotypes, the independently-derived, mutant clones displayed substantial transcriptomic heterogeneity, highlighting a potential source of variation in CRISPR-based transcriptional studies. By integrating data from the independent mutant and rescue clones, we identified a high-confidence set of 131 genes whose expression reproducibly tracked with loss and restoration of ciliary ARL13B. Together, these findings demonstrate that ciliary ARL13B is required to maintain normal ciliary composition and gene expression programs and underscores the value of multi-clone, rescue-based experimental designs for robust transcriptomic analyses. Summary for ReviewersThis study examined how excluding the protein ARL13B from primary cilia affects kidney epithelial cells. The researchers created two independent cell lines carrying a modified form of ARL13B,along with matched rescue cell lines. The findings show that ciliary ARL13B helps maintain normal ciliary composition. By comparing the cell lines, the researchers identified a high-confidence set of genes associated with loss of ciliary ARL13B. By highlighting the importance of using independent gene-edited clones and rescue-based controls, these results advance understanding of how cilia regulate kidney cell function and provide guidance for designing robust transcriptomic analyses.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a genetically heterogeneous group of diseases that regularly lead to kidney failure in mid adulthood. In ADTKD-MUC1 a distinct neoprotein generated by a frameshift mutation, MUC1-fs, is pathogenic and accumulates in distal renal tubular cells. However, the pathomechanism of the disease and the regulation of the MUC1-fs are poorly understood. Primary tubular cells from the urine of several probands were established and immortalized. The length of the repeat region of both alleles of MUC1, as well as the mutated repeat localization were precisely defined by long range sequencing. The pathogenic MUC1-fs is readily detectable in patient-derived cells and has a considerably longer half-life than the wild-type mucin 1. Targeting the secretory pathway with BRD4780, a compound previously reported as putatively therapeutic, leads to downregulation of MUC1-fs in each of our patient-derived cell model. However, wild-type mucin 1 and numerous other transcriptional pathways were also affected by BRD4780, thus being rather unselective. Tubular cells derived from the urine appear to be a suitable model to analyze the pathogenic MUC1-fs of an individual patient, enabling pharmacological studies of novel therapies.

Metabolic disturbance is a key feature in acute kidney injury (AKI) and chronic kidney disease (CKD). The kidney highly depends on fatty acid metabolism; how renal cells rewire metabolism upon AKI and CKD transition remained unclear. Here, we combine spatial transcriptomics with biochemical analyses to characterize metabolic changes and intercellular interactions during AKI to CKD transition. Using aristolochic acid model of CKD, we spatio-temporally correlated changes in structure and function with metabolic profile during AKI to CKD transition. Surprisingly, keto-gluconeogenic metabolic axis was highly enriched in healthy kidney and paralleled injury phase transitions. Intercellular interaction analysis associated a subtype of macrophage with the drift to chronicity. Online scRNAseq datasets analysis confirmed altered keto-gluconeogenic metabolic pathways in ischemia-reperfusion injured mouse kidneys and AKI and CKD human kidney biopsies compared to healthy controls. This study identifies a metabolic axis transcriptionally mirroring renal homeostasis and injury responses, and tubulo-interstitial interactions that can be targeted to mitigate AKI to CKD transition.

Introduction: B cell depletion with rituximab leads to complete or partial remission (CR/PR) in only ~60% of patients with primary membranous nephropathy (PMN). Adding belimumab to rituximab may result in greater depletion of memory B cells, limit the re-emergence of autoreactive B cells, and improve clinical responses. Methods: REBOOT Part A (NCT03949855) is a single arm, open-label, pharmacokinetic study where all participants had proteinuria [&ge;] 4g/day and detectable serum anti-phospholipase A2 receptor (anti-PLA2R) antibodies. Participants received belimumab 200 mg subcutaneously weekly for 52 weeks and rituximab 1000 mg intravenously at weeks 4 and 6. Assessments included belimumab exposure at week 4 and CR/PR at week 104. Results: Seventeen participants started belimumab. Belimumab exposure was not significantly reduced in those with high (> 9 g/day) proteinuria at week 4. Among all treated participants, 59% (10/17) achieved CR/PR at week 104, while in per protocol analyses, 91% (10/11) achieved CR/PR at week 104. All participants in per protocol analyses had normal serum albumin and undetectable serum anti-PLA2R by week 104. Circulating memory B cells increased before rituximab and were depleted by rituximab. B cell re-constitution occurred after week 52 with primarily naive and transitional B cells. Belimumab with rituximab was well-tolerated, with one participant discontinuing belimumab due to infection. Conclusion: In this study, a high proportion of participants receiving belimumab with rituximab achieved CR/PR. Thus, a multi-targeted approach to B cell depletion may improve immunologic and clinical outcomes in PMN and is being studied in a larger, randomized, placebo-controlled clinical trial.

Background: Chronic kidney disease (CKD) imposes persistent metabolic stress, yet whether metabolic organization can be preserved under sustained renal stress remains unclear. Essential trace elements support redox defense, mitochondrial function, and intermediary metabolism, and their homeostasis is disturbed in CKD; however, single-element supplementation has yielded heterogeneous results. We examined whether a defined multi-element formulation preserves metabolic resilience in CKD. Methods: In a randomized, double-blind, placebo-controlled trial, 80 maintenance dialysis patients received standard care alone (n = 40) or plus a trace element cocktail (TEX, 20 mL/day; n = 40). Longitudinal trajectories were analyzed with linear mixed-effects models; endpoint plasma metabolomics and fecal metagenomics were profiled in subsets. A 5/6 nephrectomy mouse model was used to quantify plasma tryptophan-pathway branches and renal spatial metabolism by MALDI imaging mass spectrometry. Results: TEX was well tolerated, with no treatment-related safety signal, and was associated with modestly more favorable creatinine and eGFR trajectories. Supplementation constrained, rather than erased, CKD-associated metabolic displacement (median |Cohen's d|, 0.25 versus 2.09 for disease effects), selectively realigning circulating metabolism toward the healthy state. The host kynurenine branch responded most strongly, whereas microbial indole metabolism and gut community structure changed little. Renal metabolic remodeling was region-specific, with preservation of selected tubular and antioxidant features. Conclusions: Trace element supplementation preserved metabolic resilience in CKD, limiting metabolic displacement without complete restoration. Preservation of metabolic organization may represent a complementary dimension of therapeutic response in CKD. Trial registration: International Traditional Medicine Clinical Trial Registry, ITMCTR2026000263 (registered 3 February 2026).