Nephrology
Abstract
Lysyl oxidase (LOX) is a copper-dependent monoamine oxidase whose primary function is the covalent cross-linking of collagen and elastin in the extracellular matrix (ECM). However, the regulation of LOX activity in renal fibrosis is not well understood. Here, our study showed that (a) LOX expression and ECM cross-linking were markedly increased in fibrotic kidneys. Reduction of copper levels in the Golgi apparatus by treatment with the copper chelator tetrathiomolybdate or by specific knockdown of copper transporter 1 (CTR1) decreased LOX activity and ameliorated renal fibrosis. (b) Overexpression of ATP7A caused an elevation of copper ions within the Golgi apparatus, resulting in increased LOX activity and enhanced ECM crosslinking, thereby promoting the progression of renal fibrosis. Knockdown of ATP7A showed the opposite result. (c) FBLN4 was essential for the ATP7A-mediated transfer of copper to LOX and formed a ternary complex of ATP7A-FBLN4-LOX. Our research revealed that high ATP7A expression induced copper overload in the Golgi apparatuses. FBLN4 then assisted ATP7A in transporting this excess copper to LOX, resulting in LOX overactivation. This, in turn, catalyzed the cross-linking of ECM components, thereby accelerating renal fibrosis.
Authors
Wenqian Zhou, Yan Zheng, Yuqing Liu, Jing Liu, Yiguo Liu, Yangyang Niu, Ying Yu, Xiaoqin Zhang, Yingying Zhang, Chen Yu
Abstract
Because older donor age is a major concern when considering kidneys for potential transplantation, we explored the actual impact of donor age on the features of kidneys that have been transplanted. We studied the correlations of donor age with molecular injury and rejection scores in 4502 kidney transplant biopsies assessed by microarrays, as well as function and postbiopsy survival. We used multivariable analyses to correct for the correlations of donor age with other predictive variables: recipient age, time of biopsy posttransplant, and deceased vs. living donors. Older donor age correlated with lower GFR and increased acute and chronic injury transcripts, but had no effect on rejection, which anti-correlated with recipient age. Acute injury transcripts peaked immediately posttransplant and regressed. Older donor age had little effect on acute molecular injury immediately posttransplant but strongly increased molecular injury scores at later times, peaking about 1-year posttransplant, indicating that older age does not increase molecular injury but increases failed repair post-injury. As expected, older donor age correlated with increased chronic injury and lower GFR, evident from the earliest time posttransplant, pre-transplant aging. However, despite significant age-related effects, the quantitative contribution of donor aging to molecular injury, function, and survival was very small.
Authors
Katelynn Madill-Thomsen, Martina Mackova, Jessica Chang, Enver Akalin, Tarek Alhamad, Sanjiv Anand, Miha Arnol, Rajendra Baliga, Mirosław Banasik, Christopher Blosser, Georg Böhmig, Daniel Brennan, Jonathan Bromberg, Klemens Budde, Andrzej Chamienia, Kevin V Chow, Michał Ciszek, Declan de Freitas, Dominika Dęborska-Materkowska, Alicja Dębska-Ślizień, Arjang Djamali, Leszek Domański, Magdalena Durlik, Gunilla Einecke, Farsad Eskandary, Richard Fatica, Iman Bajjoka-Francis, Justyna Fryc, John Gill, Jagbir Gill, Maciej Glyda, Sita Gourishankar, Marta Gryczman, Gaurav Gupta, Petra Hruba, Peter Hughes, Arskarapuk Jittirat, Zeljka Jurekovic, Layla Kamal, Mahmoud Kamel, Sam Kant, Nika Kojc, Joanna Konopa, James Lan, Roslyn Mannon, Arthur Matas, Joanna Mazurkiewicz, Marius Miglinas, Thomas Mueller, Marek Myślak, Beata Naumnik, Anita Patel, Agnieszka Perkowska-Ptasińska, Michael Picton, Grzegorz Piecha, Emillio Poggio, Silvie Rajnochova Bloudickova, Thomas Schachtner, Sung Shin, Soroush Shojai, Majid Sikosana, Janka Slatinská, Katarzyna Smykal-Jankowiak, Ashish Solanki, Zeljka Veceric Haler, Ondrej Viklicky, Ksenija Vucur Simic, Matthew R. Weir, Andrzej Wiecek, Zbigniew Włodarczyk, Ziad Zaky, Philip F. Halloran
Abstract
Background Cancer accounts for over 20% of late post-transplant mortality, yet the contribution of genetic susceptibility to post-transplant cancer risk remains unclear. This study investigates germline genetic risk factors for post-transplant cancer in the Finnish population using data from the FinnGen cohort. Methods A pan-cancer polygenic risk score (PRS) was constructed using genetic variants identified in UK and US populations to assess the influence of common germline variants on time to first cancer diagnosis in 1,802 Finnish kidney transplant recipients (KTRs), of whom 317 developed post-transplant cancer. The PRS was first validated in the FinnGen non-transplantation cohort and subsequently applied to KTRs, with replication in lung and liver transplant recipients (n = 476). Functional relevance was explored by assessing associations between the PRS and expression levels of 2,923 plasma proteins in the UK Biobank (n = 53,013). Results Compared to a matched non-transplantation cohort (n = 68,294), KTRs exhibited earlier cancer onset. The PRS was significantly associated with time to first cancer diagnosis in the non-transplantation population (HR 1.04; 95% CI 1.038-1.056; p = 3.75 x 10-25). Among KTRs younger than 40 years, higher PRS was associated with earlier cancer onset (HR, 1.08; 95% CI ,1.01-1.17; p = 0.036), indicating a stronger genetic effect at younger ages. The PRS significantly (Bonferroni < 0.05) altered the regulation of 87 plasma proteins, several of which were known cancer-related markers. Conclusion Inherited genetic predisposition, captured by pan-cancer PRS, may contribute to individual susceptibility to cancer after solid organ transplantation, particularly at younger ages.
Authors
Jarmo Ritari, Kati Hyvärinen, Kirsi Jahnukainen, Jukka Partanen, Ilkka Helanterä, Timo Jahnukainen
Abstract
Donnai-Barrow Syndrome (DBS) arises from loss-of-function (LoF) variants in the endocytic receptor LRP2/megalin and is characterized by low molecular weight (LMW) proteinuria and developmental abnormalities. Urinary proteomics of nine DBS patients revealed that the urinary proteome of a DBS patient with the missense variant LRP2 p.C1400R was indistinguishable from that of patients with splice site, nonsense, or frameshift mutations. A CRISPR mouse model of the variant was generated to determine the mechanism of LoF and proteinuria. The mutant LRP2 was expressed and observed to dimerize and localize to the proximal tubule apical membrane. However, both fluid-phase and receptor-mediated endocytosis were impaired in the context of a general perturbation of endocytic flux. Immunofluorescence revealed aberrant endocytic recycling with mislocalized RAB11+ and TFR1+ compartments and enlarged lysosomes. Structural modeling showed the LRP2 assembly likely tolerates the cysteine to arginine substitution at the cell surface, but at endosomal pH the variant introduced steric clashes that may disrupt intramolecular interfaces and disturb receptor recycling. These findings point to the importance of LRP2 recycling for global endocytic flux and offer a blueprint for leveraging patient-specific alleles to dissect proximal tubule function.
Authors
Andrew Beenken, Tian H. Shen, Aryan Ghotra, Hediye Erdjument-Bromage, Jeong Lee, Jared S. Kushner, Rachel E. Sturley, Atlas Khan, Jeffrey R. Arace, Leora Kronenberg, Lucy D. Shen, Gabriel H. Rahmani, Patricia K. Donahoe, Thomas A. Neubert, Frances A. High, Ora A. Weisz, Jonathan Barasch
Abstract
High dietary salt intake elevates blood pressure and drives multi-organ damage. However, the molecular programs underlying progressive organ injury remain poorly defined. Here, we present a longitudinal multi-organ transcriptomic atlas of salt-induced hypertensive injury. We profiled kidney cortex, kidney medulla, heart, and liver across four stages spanning early hypertension to advanced pathology in Dahl salt-sensitive rats. We identified dynamic and tissue-specific molecular trajectories, including a shared early proliferative response that converges on proinflammatory and fibrotic remodeling. Notably, we uncovered compartment-specific renal responses, showing that the cortex and medulla, despite their proximity, follow distinct molecular trajectories during disease progression. We further identified 79 stage- and tissue-specific transcription factors that drive gene expression dynamics in salt-induced hypertensive injury. Integration with human genome-wide association studies revealed conserved pathways in endocrine signaling, ion transport, lipid metabolism, and detoxification, establishing cross-species relevance and highlighting mechanistic targets of clinical importance. Compound–transcriptome analysis revealed stage- and organ-specific therapeutic opportunities, prioritizing kinase and epigenetic modulators as candidates to rebalance maladaptive gene programs. Overall, this study provides a resource for understanding molecular mechanisms from early salt-induced hypertension to tissue-specific injury and underscores the need for precision interventions.
Authors
Ratnakar Tiwari, Olha Kravtsova, Lashodya V. Dissanayake, Melissa Lowe, Biyang Xu, Vladislav Levchenko, Steven Didik, Ruslan Bohovyk, Daria V. Ilatovskaya, Oleg Palygin, Alexander Staruschenko
Abstract
Heat stroke (HS) is the most severe heat-related emergency, and its pathophysiology remains largely unknown, especially for exertional HS (EHS), which affects younger populations, athletes, and manual workers. Herein, we performed single-cell-transcriptomics, T cell receptor sequencing, and flow cytometry of PBMCs from 9 healthy control participants, 9 patients with heat exhaustion, and 9 patients with EHS to explore complex immunological responses associated with HS pathobiology. We showcased that granzyme-positive T cells and CD56dim NK cells with high cytotoxicity features and IL-1B+NLRP3+ monocytes with high inflammation and pyroptosis scores were enriched in HS, while the CD161+ T cells with innate immune-like, low cytotoxicity, and clonal expansion features were reduced in HS. Importantly, elevated granzyme-positive T and NK cells might interact with monocytes to induce pyroptosis of hepatic and renal cells and target organ injuries, and blocking the NLRP3 inflammasome pathway prior to the induction could alleviate organ injury in HS. This study offers deeper insights into the pathogenesis of HS, supporting the development of optimal treatment strategies.
Authors
Min Zhang, Bin Wang, Ding Sun, Xizhao Chen, Yena Zhou, Jin Yao, Liwen Du, Zehao Zhang, Hao Li, Zeyu Qu, Lu Chen, Qing Luo, Jie Zhang, Xinye Jin, Xiaowei Cheng, Jingxue Niu, Qinrui Xing, Xuezeng Tan, Tao Wang, Jie Liu, Lei Li, Qing Song, Xiangmei Chen, Yizhi Chen
Abstract
Modulation of miRNA expression in glomerular cells is associated with renal disease. Here, we investigated the role of miR-93-5p in mitigating glomerular damage in Alport syndrome and whether the disease-modifying activity of extracellular vesicles from human amniotic fluid stem cells (hAFSC-EVs) is mediated by their miR-93-5p cargo. We identified downregulation of miR-93-5p specifically in glomerular endothelial cells in Alport syndrome along disease progression. Silencing of miR-93-5p in hAFSC-EVs changed the transcriptomic and proteomic profile, regulating EV disease-modifying activity. Compared with naive hAFSC-EVs, silenced hAFSC-EVs did not rescue glomerular endothelial function in vitro and did not restore kidney function in vivo. We established that hAFSC-EVs regulate VEGFR1 and VEGFR2 signaling by miR-93-5p cargo transfer, highlighting that miR-93-5p can restore glomerular endothelial cell biology. Spatial transcriptomics analysis of hAFSC-EV–injected kidneys showed that these EVs can reverse pathways altered during disease progression by stimulating proregenerative processes, specifically in the glomerulus, by regulating miR-93-5p targets. Alteration of glomerular endothelial cell transcriptomics and miR-93-5p targets was also confirmed in biopsies of patients with Alport syndrome using spatial molecular imaging. We demonstrated the critical role of miR-93-5p in glomerular endothelial cells and the capability of hAFSC-EVs to regulate miR-93-5p and its targets in Alport syndrome.
Authors
Charmi Dedhia, Valentina Villani, Xiaogang Hou, Paolo Neviani, Geremy Clair, Mohammadreza Kasravi, Cristina Grange, Paolo Cravedi, Paola Aguiari, Velia Alcala, Giuseppe Orlando, Xue-Ying Song, Jonathan E. Zuckerman, Roger E. De Filippo, Stefano Da Sacco, Sargis Sedrakyan, Benedetta Bussolati, Laura Perin
Abstract
Introduction: BK polyomavirus (BKV) infection is associated with injury and subsequent graft loss due to the extent of injury or rejection. However, the molecular mechanisms driving injury and subsequent adverse outcomes remain poorly understood. Methods: In a cross-sectional study, single-cell RNA sequencing from kidney allograft biopsies was used to assess cell type-specific responses between uninfected controls and two distinct phases of BKV infection: peaking (increasing viral blood titers) and resolving (decreasing viral titers following immunosuppression reduction). Results: Genes upregulated in BK viral nephropathy (BKVN) were enriched for polyomavirus infection hallmarks, including ribosome biogenesis, translation, and energy restructuring. Additionally enriched pathways included wound healing, cellular stress, antigen presentation and immune signaling. Even without BKVN (peaking BK viremia alone), epithelial cells expressed signatures for wound healing, cellular stress, and extracellular matrix remodeling. In vivo tubular cell responses at single-cell resolution were validated against single cell transcriptomic data of BKV infected cells in a cell culture model. Despite similarities, in vivo tubular cells underwent metabolic adaptation favoring fatty acid oxidation and proinflammatory responses not observed in culture models likely due to an absent innate and adaptive immune system. Despite lymphopenia and immunosuppressive therapies, the proportion of recipient derived intrarenal adaptive immune cells was increased in biopsies associated with peaking viremia alongside activation of innate immune responses. Adaptive immune cells exhibited persistent inflammatory signaling and remodeling of energy metabolism during the resolving phase of infection. Conclusion: These not previously reported insights into BKV-associated injury may have implications for clinical management and improved allograft outcomes.
Authors
Tess Marvin, Rachel Sealfon, Phillip J. McCown, Fadhl AlAkwaa, Evan A. Farkash, Edgar A. Otto, Felix Eichinger, Ping An, Rajasree Menon, Celine C. Berthier, Tavis J. Reed, Paula Arrowsmith, Lalita Subramanian, Kelly J. Shaffer, Silas P. Norman, Ramnika Gumber, Michael J. Imperiale, James M. Pipas, Olga G. Troyanskaya, Matthias Kretzler, Chandra L. Theesfeld, Abhijit S. Naik
Abstract
Macrophages (MΦ), endowed with remarkable phenotypic plasticity are essential for orchestrating injury responses and regulating iron homeostasis. Given the central role of ferritin heavy chain (FtH) as a molecular rheostat linking iron sequestration to redox-dependent signaling, we examined how myeloid FtH governs renal iron trafficking and ensuing oxidative-stress pathways during acute kidney injury (AKI). Transcriptome analysis revealed coupling of FtH deficiency in monocytes and MΦ with ferroptosis activation, a regulated cell death associated with iron accumulation. Moreover, myeloid FtH deletion worsened AKI, increasing leukocyte infiltration and iron deposition, together with ferroptosis‐associated gene induction, oxidative stress, and lipid peroxidation. Notably, ⍺-synuclein (SNCA), an iron-binding protein and the main pathological driver of Parkinson’s disease, was robustly induced by both FtH deficiency and following AKI. Mechanistic studies showed that monomeric SNCA exhibits ferrireductase activity, amplifying redox cycling and promoting ferroptotic cell death. Furthermore, SNCA expression was elevated in kidney pathologies characterized by leukocyte expansion in both mouse models and human cohorts, suggesting that inflammatory microenvironments promote SNCA accumulation and redox imbalance. These findings define a MΦ FtH-SNCA regulatory axis as a key driver of ferroptosis in AKI, implicating SNCA as a pathological nexus between iron dyshomeostasis and inflammatory kidney injury.
Authors
Tanima Chatterjee, Sarah Machado, Kellen Cowen, Mary E. Miller, Bronte Johnson, Yanfeng Zhang, Laura A. Volpicelli-Daley, Lauren A. Fielding, Rudradip Pattanayak, Frida Rosenblum, László Potor, György Balla, Jozsef Balla, Christian Faul, Abolfazl Zarjou
Abstract
Low nephron endowment constitutes a risk factor for hypertension and renal disease. Epigenetic regulation is crucial for nephron progenitor cell differentiation, affecting nephron number and renal function. The role of many epigenetic modulators, such as Lysine-specific histone demethylase 1a (LSD1 or KDM1A), remains unclear. We used Kdm1a-KO mice to demonstrate that Kdm1a depletion in nephron progenitor cells results in reduced kidney size in neonates and led to glomerulosclerosis, proteinuria, and renal cysts in adults. Notably, Kdm1a deletion in podocytes or tubular cells did not replicate these effects. CRISPR/Cas9-mediated KDM1A deletion in human kidney organoids caused cyst formation and altered gene expression, with snRNA-seq revealing downregulation of podocyte genes and upregulation of metabolic genes. The presence of noncoding RNAs indicated roles in cell proliferation. Our study reveals the critical role of Kdm1a function in nephron development and highlights its affect on transcriptional programming for long-term renal function and susceptibility to cyst formation.
Authors
Nicola Wanner, Julia Keller, Nastassia Liaukouskaya, Geoffroy Andrieux, Sandra D. Laufer, Manuel Rogg, Tillmann Bork, Wei Liang, Fabian Braun, Fabian Haas, Milagros N. Wong, Victor G. Puelles, Sydney E. Gies, Charlotte Meyer, Melanie Boerries, Martin Helmstädter, Oliver Kretz, Iris Hild, Eric Metzger, Roland Schüle, Wibke Bechtel-Walz, Tobias B. Huber
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