Nephrology
Abstract
The role of endothelial dysfunction in tubulointerstitial fibrosis associated with chronic kidney disease (CKD) is not well understood. In this study, we demonstrate that the activation of the endothelial tyrosine kinase TIE2 alleviates renal pathology in experimental CKD in mice. TIE2 activation was achieved using a human angiopoietin-2 (ANGPT2)-binding and TIE2-activating antibody (ABTAA), or through adult-induced endothelial-specific knockout of the vascular endothelial protein tyrosine phosphatase gene (Veptp). Both methods significantly protected CKD mice from endothelial dysfunction, peritubular capillary loss, tubular epithelial injury, and tubulointerstitial fibrosis. Conversely, silencing TIE2 through adult-induced endothelial-specific knockout of the Tie2 gene exacerbated CKD pathology. Additionally, we found that endothelial dysfunction promotes renal fibrosis not through endothelial-to-mesenchymal transition as previously expected, but by inducing the expression of pro-fibrotic PDGFB in tubular epithelial cells, a process that is inhibited by TIE2 activation. Our findings suggest that TIE2 activation via ABTAA warrants investigation as a therapy in human CKD, where there is a substantial unmet medical need.
Authors
Riikka Pietilä, Amanda M. Marks-Hultström, Liqun He, Sami Nanavazadeh, Susan E. Quaggin, Christer Betsholtz, Marie Jeansson
Abstract
Lymphatic vessels maintain tissue fluid homeostasis and modulate inflammation, yet their spatial organisation and molecular identity in the healthy human kidney, and how these change during chronic transplant rejection, remain poorly defined. Here, we show that lymphatic capillaries initiate adjacent to cortical kidney tubules and lack smooth muscle coverage. These vessels exhibit an organ-specific molecular signature, enriched for CCL14, DNASE1L3, and MDK, with limited expression of canonical immune-trafficking markers found in other organ lymphatics, such as LYVE1 and CXCL8. In allografts with chronic mixed rejection, lymphatics become disorganised and infiltrate the medulla, with their endothelial junctions remodelling from a button-like to a continuous, zipper-like architecture. Lymphatics in rejecting kidneys localise around and interconnect tertiary lymphoid structures at different maturation stages, with altered intra- and peri-lymphatic CD4⁺ T cell distribution. The infiltrating T cells express IFNγ, which upregulates co-inhibitory ligands in lymphatic endothelial cells, including PVR and LGALS9. Simultaneously, lymphatics acquire HLA class II expression and exhibit C4d deposition, consistent with alloantibody binding and complement activation. Together, these findings define the spatial and molecular features of human kidney lymphatics, revealing tolerogenic reprogramming, accompanied by structural perturbations, during chronic transplant rejection.
Authors
Daniyal J. Jafree, Benjamin J Stewart, Karen L. Price, Maria Kolatsi-Joannou, Camille Laroche, Barian Mohidin, Benjamin Davis, Hannah Mitchell, Lauren G. Russell, Lucía Marinas del Rey, Chun Jing Wang, William J. Mason, Byung Il Lee, Lauren Heptinstall, Ayshwarya Subramanian, Gideon Pomeranz, Dale Moulding, Laura Wilson, Tahmina Wickenden, Saif N. Malik, Natalie Holroyd, Claire L. Walsh, Jennifer C. Chandler, Kevin X. Cao, Paul J.D. Winyard, Adrian S. Woolf, Marc Aurel Busche, Simon Walker-Samuel, Lucy S.K. Walker, Tessa Crompton, Peter J. Scambler, Reza Motallebzadeh, Menna R. Clatworthy, David A. Long
Abstract
To maintain potassium homeostasis, the kidney’s distal convoluted tubule (DCT) evolved to convert small changes in blood [K+] into robust effects on salt reabsorption. This process requires NaCl cotransporter (NCC) activation by the With-No-Lysine (WNK) kinases. During hypokalemia, the Kidney-Specific WNK1 isoform (KS-WNK1) scaffolds the DCT-expressed WNK signaling pathway within biomolecular condensates of unknown function termed WNK bodies. Here, we show that KS-WNK1 amplifies kidney tubule reactivity to blood [K+], in part via WNK bodies. Genetically modified mice with targeted condensate disruption trap the WNK pathway, causing renal salt wasting that is more pronounced in females. In humans, WNK bodies accumulate as plasma potassium falls below 4.0 mmol/L, suggesting that the human DCT experiences the stress of potassium deficiency even when [K+] is in the low-normal range. These data identify WNK bodies as kinase signal amplifiers that mediate tubular [K+] responsiveness, nephron sexual dimorphism, and blood pressure salt-sensitivity. Our results illustrate how biomolecular condensate specialization can optimize a mammalian physiologic stress response that impacts human health.
Authors
Cary R. Boyd-Shiwarski, Rebecca T. Beacham, Jared A. Lashway, Katherine E. Querry, Shawn E. Griffiths, Daniel J. Shiwarski, Sophia A. Knoell, Nga H. Nguyen, Lubika J. Nkashama, Melissa N. Valladares, Anagha Bandaru, Allison L. Marciszyn, Jonathan Franks, Mara Sullivan, Simon C. Watkins, Aylin R. Rodan, Chou-Long Huang, Sean D. Stocker, Ossama B. Kashlan, Arohan R. Subramanya
Abstract
Graft endothelial cells (ECs) express donor alloantigens and encounter cytotoxic T lymphocytes (CTLs) but are generally spared during T cell-mediated rejection (TCMR), which predominantly affects epithelial structures. The mechanisms underlying this vascular immune privilege are unclear. Transcriptomic analyses and endothelial-mesenchymal transition assessments confirmed that the graft endothelium is preserved during TCMR. Co-culture experiments revealed that endothelial and epithelial cells are equally susceptible to CTL-mediated lysis, ruling out cell-intrinsic protection. Intravital microscopy of murine kidney grafts and single-cell RNA sequencing of human renal allografts demonstrated that CTL interactions with ECs are transient compared to epithelial cells. This disparity is mediated by a chemotactic gradient produced by graft stromal cells, guiding CTLs away from ECs toward epithelial targets. In vitro, chemotaxis overrode TCR-induced cytotoxicity, preventing endothelial damage. Finally, analysis of TCMR biopsies revealed that disruption of the chemotactic gradient correlates with endothelialitis lesions, linking its loss to vascular damage. These findings challenge the traditional view of cell-intrinsic immune privilege, proposing a cell-extrinsic mechanism where chemotaxis preserves graft vasculature during TCMR. This mechanism may have implications beyond transplantation, highlighting its role in maintaining vascular integrity across pathological conditions.
Authors
T. Barba, M. Oberbarnscheidt, G. Franck, C. Gao, S. This, M. Rabeyrin, C. Roufosse, L. Moran, A. Koenig, V. Mathias, C. Saison, V. Dubois, N. Pallet, D. Anglicheau, B. Lamarthée, A. Hertig, E. Morelon, A Hot, H. Paidassi, T. Defrance, A. Nicoletti, J.P. Duong-Van-Huyen, Y. Xu-Dubois, F.G. Lakkis, O. Thaunat
Abstract
BACKGROUND. Kidney stone disease (KSD) affects ~10% of adults, is heritable, and associated with mineral metabolic abnormalities. METHODS. Genetic variants and pathways increasing KSD risk via calcium and phosphate homeostasis were ascertained using genome-wide association analyses, region-specific Mendelian randomization (MR), and genetic colocalization. Utility of pathway modulation was estimated via drug-target MR, and effects of variants on calcium-sensing receptor (CaSR)-signaling characterized. RESULTS. Seventy-nine independent KSD-associated genetic signals at 71 loci were identified. MR identified three loci affecting KSD risk via increased serum calcium or decreased serum phosphate concentrations (odds ratios for genomic regions=4.30, 11.42, and 13.83 per 1 standard deviation alteration; p<5.6x10-10). Colocalization analyses defined putative, non-coding KSD-causing variants estimated to account for 11-19% of KSD cases in proximity to diacylglycerol kinase delta (DGKD), a CaSR-signalling partner; solute carrier family 34 member 1 (SLC34A1), a renal sodium-phosphate transporter; and cytochrome P450 family 24 subfamily A member 1 (CYP24A1), which degrades 1,25-dihydroxyvitamin D. Drug- target MR indicated that reducing serum calcium by 0.08mmol/L via CASR, DGKD, or CYP24A1, or increasing serum phosphate by 0.16mmol/L via SLC34A1 may reduce KSD relative risk by up to 90%. Furthermore, reduced DGKδ expression and KSD-associated DGKD missense variants impaired CaSR-signal transduction in vitro, which was ameliorated by cinacalcet, a positive CaSR-allosteric modulator. CONCLUSION. DGKD-, SLC34A1-, and CYP24A1-associated variants linked to reduced CaSR-signal transduction, increased urinary phosphate excretion, and impaired 1,25-dihydroxyvitamin D inactivation, respectively, are common causes of KSD. Genotyping patients with KSD may facilitate personalised KSD-risk stratification and targeted pharmacomodulation of associated pathways to prevent KSD.
Authors
Catherine E. Lovegrove, Michelle Goldsworthy, Jeremy Haley, Diane Smelser, Caroline Gorvin, Fadil M. Hannan, Anubha Mahajan, Mohnish Suri, Omid Sadeghi-Alavijeh, Shabbir H. Moochhala, Daniel P. Gale, David Carey, Michael V. Holmes, Dominic Furniss, Rajesh V. Thakker, Sarah A. Howles
Abstract
The ATP6V0A4 gene encodes the a4 subunit of Vacuolar H+-ATPase (V-ATPase), which mediates hydrogen ion transport across the membrane. Previous studies have suggested that mutations in ATP6V0A4 consistently result in a loss of function (LOF), impairing the hydrogen ion transport efficacy of V-ATPase and leading to distal renal tubular acidosis (dRTA) and sensorineural hearing loss. Here, we identified a 32-year-old male patient and his father, both of whom harbored a heterozygous ATP6V0A4 p.V512L mutation, and both exhibited with hypochloremic metabolic alkalosis, acidic urine and hypokalemia. Through a series of protein structural analyses and functional experiments, the V512L mutation was confirmed as a gain-of-function (GOF) mutation in the ATP6V0A4 gene. V512-a4 increased a4 subunit expression abundance by enhancing V512L-a4 stability and reducing its degradation, which in turn potentiated V-ATPase's capacity to acidify the tubular lumen, leading to acidic urine and metabolic alkalosis. Through mutant V512L-a4 subunit structure-based virtual and experimental screening, we discovered F351 (C25H26FN3O2S), a small-molecule inhibitor specifically targeting the V512L-a4 mutant. In conclusion, we identify a GOF mutation in the ATP6V0A4 gene, broadening its phenotypic and mutational spectrum, and provide valuable insights into potential therapeutic approaches for diseases associated with ATP6V0A4 mutations.
Authors
Si-qi Peng, Qian-qian Wu, Wan-yi Wang, Yi-Lin Zhang, Rui-ning Zhou, Jun Liao, Jin-xuan Wei, Yan Yang, Wen Shi, Jun-lan Yang, Xiao-xu Wang, Zhi-yuan Wei, Jia-xuan Sun, Lu Huang, Hong Fan, Hui Cai, Cheng-kun Wang, Xin-hua Li, Ting-song Li, Bi-Cheng Liu, Xiao-liang Zhang, Bin Wang
Abstract
Authors
Michaela A.A. Fuchs, Myles Wolf
Abstract
Authors
Sandrine Lemoine, Arnaud Molin, Alice Koenig, Justine Bacchetta
Abstract
In the kidney, cells of thick ascending limb of the loop of Henle (TAL) are resistant to ischemic injury, despite high energy demands. This adaptive metabolic response is not fully understood even though the integrity of TAL cells is essential for recovery from acute kidney injury (AKI). TAL cells uniquely express uromodulin, the most abundant protein secreted in healthy urine. Here, we demonstrate that alternative splicing generates a conserved intracellular isoform of uromodulin, which contributes to metabolic adaptation of TAL cells. This splice variant was induced by oxidative stress and was up-regulated by AKI that is associated with recovery, but not by severe AKI and chronic kidney disease (CKD). This intracellular variant was targeted to the mitochondria, increased NAD+ and ATP levels, and protected TAL cells from hypoxic injury. Augmentation of this variant using antisense oligonucleotides after severe AKI improved the course of injury. These findings underscore an important role of condition-specific alternative splicing in adaptive energy metabolism to hypoxic stress. Enhancing this protective splice variant in TAL cells could become a novel therapeutic intervention for AKI.
Authors
Azuma Nanamatsu, George J. Rhodes, Kaice A. LaFavers, Radmila Micanovic, Virginie Lazar, Shehnaz Khan, Daria Barwinska, Shinichi Makino, Amy Zollman, Ying-Hua Cheng, Emma H. Doud, Amber L. Mosley, Matthew J. Repass, Malgorzata M. Kamocka, Aravind Baride, Carrie L. Phillips, Katherine J. Kelly, Michael T. Eadon, Jonathan Himmelfarb, Matthias Kretzler, Robert L. Bacallao, Pierre C. Dagher, Takashi Hato, Tarek M. El-Achkar
Abstract
Background: Men with chronic kidney disease (CKD) experience faster kidney function decline than women. Studies in individuals undergoing sex hormone therapy suggest a role for sex hormones, as estimated glomerular filtration rate (eGFR) increases with feminizing therapy and decreases with masculinizing therapy. However, effects on measured GFR (mGFR), glomerular and tubular function, and involved molecular mechanisms remain unexplored. Methods: This prospective, observational study included individuals initiating feminizing (estradiol and antiandrogens; n=23) or masculinizing (testosterone; n=21) therapy. Baseline and three-month assessments included mGFR (Iohexol clearance), kidney perfusion (para-aminohippuric acid clearance), tubular injury biomarkers, and plasma proteomics. Results: During feminizing therapy, mGFR and kidney perfusion increased (+3.6% and +9.1%, respectively; p<0.05), without increased glomerular pressure. Tubular injury biomarkers, including urine neutrophil gelatinase-associated lipocalin, EGF, monocyte chemoattractant protein-1, and chitinase 3-like protein 1 (YKL-40), decreased significantly (-53%, -42%, -45%, and -58%, respectively). During masculinizing therapy, mGFR and kidney perfusion remained unchanged, but urine YKL-40 and plasma TNFR-1 increased (+134% and +8%, respectively; p<0.05). Proteomic analysis revealed differential expression of 49 proteins during feminizing, and 356 proteins during masculinizing therapy. Many kidney-protective proteins were positively associated with estradiol and negatively associated with testosterone, including proteins involved in endothelial function (SFRP4, SOD3), inflammation reduction (TSG-6), and maintaining kidney tissue structure (agrin). Conclusion: Sex hormones influence kidney physiology, with estradiol showing protective effects on glomerular and tubular function, while testosterone predominantly exerts opposing effects. These findings emphasize the role of sex hormones in sexual dimorphism observed in kidney function and physiology and suggest new approaches for sex-specific precision medicine.
Authors
Sarah A. van Eeghen, Laura Pyle, Phoom Narongkiatikhun, Ye Ji Choi, Wassim Obeid, Chirag R. Parikh, Taryn G. Vosters, Irene GM van Valkengoed, Merle M. Krebber, Daan J. Touw, Martin den Heijer, Petter Bjornstad, Daniël Raalte, Natalie J. Nokoff
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)