Nephrology
Abstract
Obstructive nephropathy is a significant and preventable contributor to chronic kidney disease, yet no disease-modifying anti-fibrotic agents are currently available.We hypothesized that interferon regulatory factor 5 (IRF5) functions as a macrophage transcriptional regulator that directly transactivates matrix metalloproteinase 9 (MMP9) to initiate early extracellular matrix (ECM) remodeling. Analysis of 30 human obstructive nephropathy biopsy specimens demonstrated that IRF5+CD68+ macrophage density increased progressively with fibrosis severity and correlated significantly with α-smooth muscle actin (α-SMA) positive areas. In the murine unilateral ureteral obstruction (UUO) model, both global and myeloid-specific Irf5 deletion significantly attenuated collagen deposition, immune cell infiltration, and fibrotic gene expression compared with wild-type controls. Cleavage under targets and tagmentation (CUT&Tag) analysis demonstrated that IRF5 directly binds the Mmp9 enhancer region and increases chromatin accessibility. Consequently, myeloid-specific Irf5 knockout significantly reduced Mmp9 mRNA and MMP9 protein levels. Pharmacological inhibition using the IRF5 inhibitor N5-1 mitigated established fibrosis, down-regulated α-SMA and MMP9 expression, and reduced CD68+ macrophage infiltration. These findings identify the IRF5-MMP9 axis as a therapeutically targetable pathway driving macrophage-mediated ECM expansion and provide pre-clinical evidence supporting IRF5 inhibition as a potential treatment strategy for patients with obstructive nephropathy.
Authors
Jia Wei, Gengyu Du, Zixia Li, Min Yang, Ting Chen, Zihao Xu, Zhen Yuan, Yidan Zheng, Xiang Yan
Abstract
Polycystic kidney disease (PKD) arises from mutations in cilia-associated genes, such as PKD1 and PKD2, expressed in renal epithelial cells, leading to progressive kidney dysfunction and end-stage kidney disease (ESKD). PKD patients exhibit significant heterogeneity in disease progression, largely due to genetic and environmental modifiers. Like patients, mouse models of PKD also exhibit significant heterogeneity with regards to the gene mutated, age of disease onset, and rate of disease progression. To elucidate the cellular and molecular consequences of these variables, we constructed an integrated single-cell RNA sequencing atlas across mouse models of PKD, mapping changes in cell type composition, gene expression, and intercellular signaling networks across the whole atlas and within individual models. Across models, single cell RNA sequencing (scRNAseq) data revealed increased Spp1 (osteopontin) expression and signaling from PKD-enriched clusters. Global deletion of Spp1 in Pkd1RC/RC mice resulted in a modest reduction in cyst severity and improved kidney function. From these studies, we created a freely available, searchable website (https://bmblx.bmi.osumc.edu/scPKD/) that can be used to identify cross- and intra-model changes in gene expression, guiding researchers to new therapeutic targets for treating PKD.
Authors
Sarah J. Miller, Hua Zhong, Weidong Wu, Audrey M. Cordova, Morgan E. Yashchenko, Alex Yashchenko, Zhang Li, Daniyal J. Jafree, Chelsea N. Zimmerman, Christa I. DeVette, Vicki Do, Maya E. Hignite, Yohan Park, Fariha Nusrat, Bibi Maryam, Sizhao Lu, Xiaoyan Li, Jenny R. Gipson, Xiaogang Li, David A. Long, Mary C.M. Weiser-Evans, Bradley K. Yoder, Benjamin D. Cowley, Jr., Katharina Hopp, Jason R. Stubbs, Qin Ma, Anjun Ma, Kurt A. Zimmerman
Abstract
Renin cells are essential for survival and serve as key regulators of blood pressure and fluid-electrolyte homeostasis. Their function and identity are dependent on signals from their local microenvironment afforded by neighboring cells and nerves. Whether and how renin cells contribute to the development and maintenance of this microenvironment remains unclear. Because renin cells are rare -0.01 % of kidney cells- conventional histological approaches cannot capture their interaction with nerve fibers and surrounding cells within the nephron and its vasculature. Using high-resolution 3D imaging, cell-specific multicolor reporter mice, single-cell RNA-Seq, and conditional gene deletions, we mapped how renin cells assemble within arterioles and communicate with axon fibers to organize the growth and orientation of the kidney arterioles during development and disease. This co-inductive process is mediated by Ngf produced by renin cell precursors and is necessary for renin cell survival and innervation. Interestingly, renin enzymatic insufficiency elevates Ngf and drives arteriolar hypertrophy with aberrant axon sprouting and hyperinnervation. These findings indicate that renin cells regulate kidney neurovascular development revealing them as active organizers of their local neuroregulatory microenvironment in health and disease.
Authors
Manako Yamaguchi, Georgina Gyarmati, Liam McLaughlin, Hiroki Yamaguchi, Jason P. Smith, Lucas Ferreira de Almeida, Daisuke Matsuoka, Alexandre G. Martini, Sara M. Wilmsen, Sijie Hao, Kazuki Tainaka, Silvia Medrano, Sanjay Jain, Janos Peti-Peterdi, Maria Luisa S. Sequeira-Lopez, R. Ariel Gomez
Abstract
Authors
Muhammad Atif Rauf, Sanskriti Agarwal, Rebecca R. Baker, Jennifer Steeden, Alfredo Petrosino, Maria Kiliaris, Robert Unwin, Keith Siew, Alan D. Salama, Rhys D.R. Evans
Abstract
BACKGROUND. Primary laminopathies are a heterogeneous group of rare diseases caused by nuclear lamina dysfunction due to pathogenic LMNA variants. However, despite their ubiquitous expression, LMNA variants have rarely been linked to chronic kidney disease (CKD). Here, we systematically investigate clinical implications and functional underpinnings of a distinct LMNA missense variant (lamin A/C p.(Arg349Trp)) that has sporadically been found in patients with a complex phenotype including lipodystrophy, proteinuria, and focal segmental glomerulosclerosis (FSGS). METHODS. In clinical and functional terms, we compare lamin A/C Arg349Trp with missense changes at Arg482, the most common hotspot residue for type 2 familial partial lipodystrophy (FPLD2). In particular, we assess renal endpoints in corresponding patient cohorts and investigate disease-associated alterations in vitro. RESULTS. In contrast to FPLD2 patients, individuals with lamin A/C Arg349Trp experience high-grade proteinuria and a rapid decline of glomerular filtration rate with kidney failure at a median age of 43 years. Mechanistically, we demonstrate that Arg349Trp associates with an abrogation of the structural interaction between lamin A/C and nucleoporin 155, nuclear pore complex aggregation, and an alteration of TGF-β1-dependent signaling. CONCLUSIONS. While patients with Lamin A/C Arg482 missense changes are at very low risk for progressive CKD, patients harboring Arg349Trp show nephrotic range proteinuria and kidney failure in midlife. Hence, high-grade proteinuric kidney disease is genotype-specific and patients with the Arg349Trp substitution require early renoprotective intervention to potentially halt progression and prevent kidney failure. FUNDING. German Research Foundation, project IDs 502928386, 445703531, and grants HA 9779/2-1, HA 6908/4-1, HA 6908/7-1, HA 6908/8-1, HA 6908/12-1.
Authors
Sebastian Sewerin, Charlotte Aurnhammer, Mohamed Hamed, Gwladys Revêchon, Ria Schönauer, Christin Findeisen, Konstanze Miehle, Šárka Tesařová, Theodoros Georgomanolis, Carsten Bergmann, Constantin A. Wolff, Marek Kollár, Baris Akinci, David Araujo-Vilar, Giovanni Ceccarini, Éva Csajbók, Alessandra Gambineri, Martin Heni, Thomas Scherer, Iztok Štotl, Ekaterina Sorkina, Marie-Christine Vantyghem, Elena Vorona, Martin Wabitsch, Julia von Schnurbein, Camille Vatier, Joëlle Roume, Yves Reznik, Maria Eriksson, Wolfram Antonin, Corinne Vigouroux, Jan Halbritter
Abstract
Ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) leading to renal fibrosis. Here, we investigate the kinetics of autophagy, apoptosis, and necroptosis activation in tubular epithelial cells (TECs) and peritubular capillaries (PTCs) after renal IRI, and their relative contributions to renal fibrogenesis. IRI with renal artery clamping in GFP-LC3 transgenic mice induced a predominant and sustained necroptotic response in TECs, while apoptosis and autophagy played minor roles. PTCs showed early and persistent activation of apoptosis, brief necroptosis induction, and increased autophagy at a distance from IRI. Disruption of the autophagic process with chloroquine (CHQ) injections in association with renal IRI did not modulate tubular death but enhanced PTC apoptosis and increased microvascular rarefaction and fibrosis. Apoptosis-deficient GFP-LC3/Caspase-3–/– mice exposed to renal IRI showed enhanced PTC autophagy, reduced PTC rarefaction, and inhibition of renal fibrosis, in spite of increased necroptosis in TECs. Inhibition of both autophagy with CHQ and apoptosis in GFP-LC3/Caspase-3–/– mice led to a marked switch toward necroptosis in PTCs. This was associated with aggravated microvascular rarefaction, increased leukocyte infiltration, and enhanced renal fibrosis. These findings establish a predominant role for PTC autophagy and caspase-3–dependent apoptosis in the development of renal fibrosis after IRI.
Authors
Hyunyun Kim, Francis Migneault, Shanshan Lan, Imane Kaci, Julie Turgeon, Annie Karakeussian Rimbaud, Martin Dupont, Shijie Qi, Mélanie Dieudé, Marie-Josée Hébert
Abstract
The distal nephron segments play a critical role in maintaining electrolyte balance, yet the mechanisms that preserve epithelial identity and segmental organization within this region remain poorly defined. Yes-associated protein (YAP), a key effector of Hippo signaling, is essential for kidney development, but its function in distal nephron epithelia is unknown. Using a genetic gain-of-function approach to activate YAP selectively in distal nephron segments, we found that sustained YAP activity profoundly disrupts epithelial organization and nephron patterning. Lineage tracing revealed that both distal convoluted tubule and connecting tubule cells originate from Slc12a3-expressing cells, and YAP activation in these segments led to increased proliferation, displacement of lineage-labeled cells beyond expected segment boundaries, and loss of segment-specific gene expression. These changes were accompanied by defects in apicobasal polarity and junctional integrity, consistent with epithelial plasticity. Unexpectedly, YAP activation in distal nephron segments also suppressed proximal tubule gene expression, indicating non-cell-autonomous effects on nephron differentiation. Together, these findings identify YAP as a critical regulator of epithelial identity in the distal nephron segments and reveal a previously unrecognized role for Hippo signaling in coordinating intersegmental organization during kidney development.
Authors
Zeinab Dehghani-Ghobadi, Eunah Chung, Mohammed Sayed, Christopher Ahn, Hyojin Alex Choi, Annissa Aamoum, Benjamin R. Thomson, Yueh-Chiang Hu, Hee-Woong Lim, Joo-Seop Park
Abstract
Circulating fatty acids (FA) are constitutively taken up by basolateral kidney proximal tubule transporters and are the preferred metabolic substrate. In many chronic kidney diseases, the damaged glomerular filtration barrier permits passage of albumin-bound FA, which are reabsorbed by apical FA transport protein-2 (FATP2). Bilateral FA uptake leads to lipotoxicity and progressive renal function decline, but the relative apical versus basolateral contribution and intracellular mechanisms are not established. Apical or bilateral (but not basolateral) palmitate incubation with human proximal tubule cells stimulated endoplasmic reticulum (ER) stress gene expression, ER stress pathway activation, and ER fragmentation. Apical or bilateral palmitate was associated with reduced lipid droplets, and decreased expression of ER-localized lipid droplet biogenesis transcripts. Inhibition of lipid droplet formation also precipitated ER stress, suggesting diminished sequestration of FA metabolites as the cause. Indeed, C16:0 ceramide was increased in bilateral palmitate-treated cells, and in kidneys from mice that phenocopy progressive diabetic kidney disease. Ceramide synthesis inhibition abrogated ER stress, and transfection with C16:0 ceramide decreased ER membrane fluidity and caused ER stress. We conclude that aberrant filtration and uptake of FA by apical FATP2 exceeded the capacity for lipid droplet incorporation, and led to cytotoxicity from ceramide-induced ER lipid bilayer stress.
Authors
Zhiyu Liu, Robert J. Gaivin, Shenaz Khan, Vincent Li, Amal Chaba, Fraser J. Moss, Usman Sabir, Takhar Kasumov, Tingwei Mu, Jeffrey R. Schelling
Abstract
While Wilms tumors commonly arise from renal precursor cells and maintain features of the developing kidney, recent studies have demonstrated significant genetic, histologic, and molecular heterogeneity. To further investigate tumor variability as well as unifying features in tumor biology, we performed single nuclei RNA-sequencing (snRNA-seq) on treatment naïve, favorable histology Wilms tumors utilizing a reference atlas established from tumor-adjacent kidney samples and fetal kidney. Transcriptional profiles of blastemal, stromal, and epithelial components were correlated with tumor histology and demonstrate developmental-lineage plasticity, with PAX2 and PAX8 expression normally restricted to the nephron lineage of the fetal kidney found to be expressed in tumor stroma, as well as the stromal marker POSTN identified in tumor blastema. Further analyses of the blastema show shared transcriptional features with the differentiation trajectory of “uninduced” to “early differentiating” fetal nephron progenitor cells as well as aberrant expression of stromal signatures. A number of pathways from fetal nephron progenitors were maintained in the blastema, including regulation of stem cell maintainence and axonogenesis, whereas other pathways appear enriched in specific tumor samples, demonstrating the ability of snRNA-seq to identify both unifiying transcriptional signatures and uncover distinct molecular targets in signaling pathways and/or biological drivers of Wilms tumorigenesis.
Authors
Mike Adam, Keri A. Drake, Naomi Pode-Shakked, Katherine VandenHeuvel, Steve Potter, James Geller
Abstract
Transcriptional reprogramming has an important role in kidney glomerular disease. Using in vivo murine models of podocyte injury, we studied the roles of the FOXC2 and WT1 transcription factors (TFs) in podocyte injury. Podocytes are a crucial cell type of glomeruli, the filtration units of each nephron. Podocyte injury is often the incipient event leading to chronic kidney disease. It is well established that the TFs FOXC2 and WT1 are required in podocytes to maintain the glomerular filtration barrier. Their role in the response to injury is less well understood. Here, we tested the hypothesis that FOXC2 and WT1 act together to mediate transcriptional reprogramming in response to podocyte injury. Similarly to that of WT1, genome-wide FOXC2 binding to target genes is dynamic during the course of injury, initially increasing, but late in injury there is a dramatic decrease in FOXC2 expression and in its binding to target genes. Podocyte-specific inactivation of FoxC2 or Wt1 in adult mice limits the transcriptional response to injury. Correlating FOXC2 and WT1 ChIP-seq analyses demonstrated that they co-bind many genes expressed in podocytes. Thus, reprogramming the transcriptome involves dynamic changes in the binding of FOXC2 and WT1 to their target genes during a reparative injury response.
Authors
Sandrine Ettou, Anya Greenberg, Sangyoon Lee, Arjun Rajesh, Liang Sun, Nahid Tabibzadeh, Haruka Oishi, Ran Konoe, Phillip J. McCown, Sean Eddy, Victoria Driscoll, Tomoya Miyoshi, Ken Hiratsuka, Jason Lam, R. Sathish Srinivasan, Youngsook L. Jung, Biju Isaac, Mingwei Sun, Mary E. Taglienti, Keith Keller, Hong Chen, Matthias Kretzler, Astrid Weins, Ryuji Morizane, Shira Rockowitz, Valerie A. Schumacher, Dongwon Lee, Jordan A. Kreidberg
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