Nephrology
Abstract
The LAMA5 gene encodes laminin α5, an indispensable component of glomerular basement membrane and other types of basement membrane. A homozygous pathological variant in LAMA5 is known to cause systemic developmental syndrome, including glomerulopathy. However, the roles of heterozygous LAMA5 gene variants in human renal and systemic disease have remained unclear. We performed whole-exome sequence analyses of a family with slowly progressive nephropathy associated with hereditary focal segmental glomerulosclerosis; we identified a probable pathogenic novel variant of LAMA5, NP_005551.3:p.Val3687Met. In vitro analyses revealed cell type-dependent changes in secretion of variant laminin α5 LG4-5 domain. Heterozygous and homozygous knock-in mice with a corresponding variant of human LAMA5, p.Val3687Met, developed focal segmental glomerulosclerosis-like pathology with reduced laminin α5 and increased glomerular vinculin levels; this suggested that impaired cell adhesion may underlie this glomerulopathy. We also identified pulmonary defects such as bronchial deformity and alveolar dilation. Re-examinations of the family revealed phenotypes compatible with reduced laminin α5 and increased vinculin levels in affected tissues. Thus, the heterozygous p.Val3687Met variant may cause a new syndromic nephropathy with focal segmental glomerulosclerosis through possibly defective secretion of laminin α5. Enhanced vinculin may be a useful disease marker.
Authors
Jun-Ya Kaimori, Yamato Kikkawa, Daisuke Motooka, Tomoko Namba-Hamano, Ayako Takuwa, Atsuko Imai-Okazaki, Kaori Kobayashi, Arisa Tanigawa, Yuko Kotani, Yoshihiro Uno, Kazuto Yoshimi, Koki Hattori, Yuta Asahina, Sachio Kajimoto, Yohei Doi, Tatsufumi Oka, Yusuke Sakaguchi, Tomoji Mashimo, Kiyotoshi Sekiguchi, Akihiro Nakaya, Motoyoshi Nomizu, Yoshitaka Isaka
Abstract
Lipoprotein modification by reactive dicarbonyls, including isolevuglandin (IsoLG), produces dysfunctional particles. Kidneys participate in lipoprotein metabolism, including tubular uptake. However, the process beyond the proximal tubule is unclear, as is the effect of kidney injury on this pathway. We found that patients and animals with proteinuric injury have increased urinary apolipoprotein AI (apoAI), IsoLG, and IsoLG adduct enrichment of the urinary apoAI fraction compared with other proteins. Proteinuric mice, induced by podocyte specific injury, showed more tubular absorption of IsoLG-apoAI and increased expression of lipoprotein transporters in proximal tubular cells compared with uninjured animals. Renal lymph reflects composition of the interstitial compartment, and showed increased apoAI and IsoLG in proteinuric animals, supporting a tubular cell-interstitium-lymph pathway for renal handling of lipoproteins. IsoLG-modified apoAI was not only a marker of renal injury, but also directly damaged renal cells. IsoLG-apoAI increased inflammatory cytokines in cultured tubular epithelial cells, activated lymphatic endothelial cells and caused greater contractility of renal lymphatic vessels than unmodified apoAI. In vivo, inhibition of IsoLG by a dicarbonyl scavenger reduced both albuminuria and urinary apoAI and decreased tubular epithelial cell and lymphatic endothelial cell injury, lymphangiogenesis, and interstitial fibrosis. Our results indicate that IsoLG-modified apolipoprotein AI is a novel pathogenic mediator and therapeutic target in kidney disease.
Authors
Jianyong Zhong, Hai-Chun Yang, Elaine L. Shelton, Taiji Matsusaka, Amanda J. Clark, Valery Yermalitsky, Zahra Mashhadi, Linda S. May-Zhang, MacRae F. Linton, Agnes B. Fogo, Annet Kirabo, Sean S. Davies, Valentina Kon
Abstract
Acute kidney injury (AKI) represents a common complication in critically ill patients that is associated with increased morbidity and mortality. In a murine AKI model induced by ischemia-reperfusion-injury (IRI), we show that glutamine significantly decreases kidney damage and improves kidney function. We demonstrate that glutamine causes transcriptomic and proteomic reprogramming in murine renal tubular epithelial cells (TECs), resulting in decreased epithelial apoptosis, neutrophil recruitment and improved mitochondrial functionality and respiration provoked by an ameliorated oxidative phosphorylation. We identify the proteins glutamine gamma glutamyltransferase 2 (Tgm2) and apoptosis signal-regulating kinase (Ask1) as the major targets of glutamine in apoptotic signaling. Furthermore, the direct modulation of the Tgm2-HSP70 signalosome and reduced Ask1 activation result in decreased JNK activation leading to diminished mitochondrial intrinsic apoptosis in TECs. Glutamine administration attenuated kidney damage in vivo during AKI and TEC viability in vitro under inflammatory or hypoxic conditions.
Authors
Katharina Thomas, Lisa Zondler, Nadine Ludwig, Marina Kardell, Corinna Lüneburg, Katharina Henke, Sina Mersmann, Andreas Margraf, Tilmann Spieker, Tobias Tekath, Ana Velic, Richard Holtmeier, Juliane Hermann, Vera Jankowski, Melanie Meersch, Dietmar Vestweber, Martin Westphal, Johannes Roth, Michael A. Schaefers, John A. Kellum, Clifford A. Lowell, Jan Rossaint, Alexander Zarbock
Abstract
The kidney contains a population of resident macrophages from birth that expands as it grows and forms a contiguous network throughout the tissue. Kidney resident macrophages (KRMs) are important in homeostasis and the response to acute kidney injury (AKI). While the kidney contains many microenvironments, it is unknown whether KRMs are a heterogeneous population differentiated by function and location. We combined single-cell RNA sequencing (scRNAseq), spatial transcriptomics, flow cytometry, and immunofluorescence imaging to localize, characterize, and validate KRM populations during quiescence and following 19 minutes of bilateral ischemic kidney injury. scRNAseq and spatial transcriptomics revealed seven distinct KRM subpopulations, which are organized into zones corresponding to regions of the nephron. Each subpopulation was identifiable by a unique transcriptomic signature suggesting distinct functions. Specific protein markers were identified for two clusters allowing analysis by flow cytometry or immunofluorescence imaging. Following injury, the original localization of each subpopulation is lost, either from changing locations or transcriptomic signatures. The original spatial distribution of KRMs is not fully restored for at least 28 days post-injury. The change in KRM localization confirms a long hypothesized dysregulation of the local immune system following acute injury and may explain the increased risk for chronic kidney disease.
Authors
Matthew D. Cheung, Elise N. Erman, Kyle H. Moore, Jeremie M.P. Lever, Zhang Li, Jennifer R. LaFontaine, Gelare Ghajar-Rahimi, Shanrun Liu, Zhengqin Yang, Rafay Karim, Bradley K. Yoder, Anupam Agarwal, James F. George
Abstract
BACKGROUND. Metabolomic profiling in individuals with chronic kidney disease (CKD) has the potential to identify novel biomarkers and provide insight into disease pathogenesis. Methods: We examined the association between blood metabolites and CKD progression, defined as the subsequent development of end-stage renal disease (ESRD) or estimated glomerular filtrate rate (eGFR) halving, in 1773 participants of the Chronic Renal Insufficiency Cohort (CRIC) study, 962 participants of the African American Study of Kidney Disease and Hypertension (AASK), and 5305 participants of the Atherosclerosis Risk in Communities (ARIC) study. RESULTS. In CRIC, more than half of measured metabolites were associated with CKD progression in minimally adjusted Cox proportional hazards models, but the number and strength of associations were markedly attenuated by serial adjustment for covariates, particularly eGFR. Ten metabolites were significantly associated with CKD progression in fully-adjusted models in CRIC; three of these metabolites were also significant in fully-adjusted models in AASK and ARIC, highlighting potential markers of glomerular filtration (pseudouridine), histamine metabolism (methylimidazoleacetate), and azotemia (homocitrulline). Our findings also nominate N-acetylserine as a potential marker of kidney tubular function, with significant associations with CKD progression observed in CRIC and ARIC. CONCLUSION. Together, our findings demonstrate the application of metabolomics to identify potential biomarkers and causal pathways in CKD progression. TRIAL REGISTRATION. Not applicable FUNDING. This study was supported by the NIH (U01 DK106981, U01 DK106982, U01 DK085689, R01 DK108803, R01 DK124399)
Authors
Donghai Wen, Zihe Zheng, Aditya Surapaneni, Bing Yu, Linda Zhou, Wen Zhou, Dawei Xie, Haochang Shou, Julian Avila-Pacheco, Sahir Kalim, Jiang He, Chi-yuan Hsu, Afshin Parsa, Panduranga Rao, James Sondheimer, Raymond Townsend, Sushrut S. Waikar, Casey M. Rebholz, Michelle R. Denburg, Paul L. Kimmel, Ramachandran S. Vasan, Clary B. Clish, Josef Coresh, Harold I. Feldman, Morgan E. Grams, Eugene P. Rhee
Abstract
Energy metabolism failure in proximal tubule cells (PTC) is a hallmark of chronic kidney injury. We combined transcriptomic, metabolomic and lipidomic approaches in experimental models and patient cohorts to investigate the molecular bases of the progression to chronic kidney allograft injury initiated by ischemia-reperfusion injury (IRI). The urinary metabolome of kidney transplant recipients with chronic allograft injury and who experienced severe IRI was significantly enriched with long chain fatty acids (FA). We identified a renal FA-related gene signature with low levels of Cpt2 and Acsm5 and high levels of Acsl4 and Acsm5 associated with IRI, transition to chronic injury, and established CKD in mouse models and kidney transplant recipients. The findings were consistent with the presence of Cpt2-, Acsl4+, Acsl5+, Acsm5- PTC failing to recover from IRI as identified by snRNAseq. In vitro experiments indicated that endoplasmic reticulum (ER) stress contributes to CPT2 repression, which, in turn, promotes lipids accumulation, drives profibrogenic epithelial phenotypic changes, and activates the unfolded protein response. ER stress through CPT2 inhibition and lipid accumulation, engages an auto-amplification loop leading to lipotoxicity and self-sustained cellular stress. Thus, IRI imprints a persistent FA metabolism disturbance in the proximal tubule sustaining the progression to chronic kidney allograft injury.
Authors
Anna Rinaldi, Hélène Lazareth, Virginie Poindessous, Ivan Nemazanyy, Julio L. Sampaio, Daniele Malpetti, Yohan Bignon, Maarten Naesens, Marion Rabant, Dany Anglicheau, Pietro E. Cippà, Nicolas Pallet
Abstract
Aristolochic acid nephropathy (AAN) is characterized by acute proximal tubule necrosis and immune cell infiltration, contributing to the global burden of chronic kidney disease and urothelial cancer. Although the proximal tubule has been defined as the primary target of aristolochic acids I (AAI), the mechanistic underpinning of gross renal deterioration caused by AAI has not been explicitly explained, prohibiting effective therapeutic intervention. To this point, we employed integrated single-cell RNA-sequencing, bulk RNA-sequencing, and mass spectrometry-based proteomics to analyze mouse kidney post-acute AAI exposure. Our results revealed a dramatic reduction of proximal tubule epithelial cells, associated with apoptotic and inflammatory pathways, indicating permanent damage beyond repair. We found the enriched development pathways in other nephron segments, suggesting activation of reparative programs triggered by AAI. The divergent response may be attributed to the segment-specific distribution of organic anions channels along the nephron, including OAT1 and OAT3. Moreover, we observed dramatic activation and recruitment of cytotoxic T and macrophage M1 cells, highlighting inflammation as a principal contributor to permanent renal injury. Ligand-receptor pairing revealed critical intercellular crosstalk underpins damage-induced activation of immune cells. These results provide novel insight into AAI-induced kidney injury and point out potential pathways for future therapeutic intervention.
Authors
Jiayun Chen, Piao Luo, Chen Wang, Chuanbin Yang, Yunmeng Bai, Xueling He, Qian Zhang, Junzhe Zhang, Jing Yang, Shuang Wang, Jigang Wang
Abstract
Acute and chronic kidney injuries induce increased cell cycle progression in renal tubules. While increased cell cycle progression promotes repair after acute injury, the role of ongoing tubular cell cycle progression in chronic kidney disease is unknown. Two weeks after initiation of chronic kidney disease, we blocked cell cycle progression at G1/S phase by using an FDA-approved, selective inhibitor of CDK4/6. Blocking CDK4/6 improved renal function and reduced tubular injury and fibrosis in 2 murine models of chronic kidney disease. However, selective deletion of cyclin D1, which complexes with CDK4/6 to promote cell cycle progression, paradoxically increased tubular injury. Expression quantitative trait loci (eQTLs) for CCND1 (cyclin D1) and the CDK4/6 inhibitor CDKN2B were associated with eGFR in genome-wide association studies. Consistent with the preclinical studies, reduced expression of CDKN2B correlated with lower eGFR values, and higher levels of CCND1 correlated with higher eGFR values. CDK4/6 inhibition promoted tubular cell survival, in part, through a STAT3/IL-1β pathway and was dependent upon on its effects on the cell cycle. Our data challenge the paradigm that tubular cell cycle progression is beneficial in the context of chronic kidney injury. Unlike the reparative role of cell cycle progression following acute kidney injury, these data suggest that blocking cell cycle progression by inhibiting CDK4/6, but not cyclin D1, protects against chronic kidney injury.
Authors
Yosuke Osaki, Marika Manolopoulou, Alla V. Ivanova, Nicholas Vartanian, Melanie Phillips Mignemi, Justin Kern, Jianchun Chen, Haichun Yang, Agnes B. Fogo, Mingzhi Zhang, Cassianne Robinson-Cohen, Leslie S. Gewin
Abstract
Acute kidney injury increases morbidity and mortality and previous studies have shown that remote ischemic preconditioning (RIPC) reduces the risk of acute kidney injury after cardiac surgery. RIPC increases urinary HMGB1 (high mobility group box protein-1) levels in patients which correlates with kidney protection. Here, we show that RIPC reduces renal ischemia-reperfusion injury and improves kidney function in mice. Mechanistically, RIPC increases HMGB1 levels in the plasma and urine and HMGB1 binds to Toll-like receptor 4 (TLR4) on renal tubular epithelial cells, inducing transcriptomic modulation of renal tubular epithelial cells and providing renal protection, whereas TLR4 activation on non-renal cells was shown to contribute to renal injury. This protection is mediated by activation of induction of AMPK⍺ and NF-kB, which induces the upregulation of Sema5b that triggers a transient, protective G1 cell-cycle arrest. In cardiac surgery patients at high risk for postoperative acute kidney injury, increased HMGB1 and Sema5b levels after RIPC were associated with renal protection after surgery. The results may help to develop future clinical treatment options for acute kidney injury.
Authors
Jan Rossaint, Melanie Meersch, Katharina Thomas, Sina Mersmann, Martin Lehmann, Jennifer Skupski, Tobias Tekath, Peter Rosenberger, John A. Kellum, Hermann Pavenstädt, Alexander Zarbock
Abstract
Although macrophages are undoubtedly attractive therapeutic targets for acute kidney injury (AKI) because of their critical roles in renal inflammation and repair, the underlying mechanisms of macrophage phenotype switching and efferocytosis in the regulation of inflammatory responses during AKI are still largely unclear. The present study was to elucidate the role of JAML (junctional adhesion molecule-like protein) in the pathogenesis of AKI. We found that JAML was significantly up-regulated in the kidney from two different murine AKI models including renal ischemia/reperfusion injury (IRI) and cisplatin-induced AKI. By generation of bone marrow chimeric mice, macrophage-specific and tubular-specific Jaml conditional knockout mice, we demonstrated JAML promotes AKI mainly via a macrophage-dependent mechanism and found that JAML-mediated macrophage phenotype polarization and efferocytosis is one of critical signal transduction pathways linking inflammatory responses to AKI. Mechanistically, the effects of JAML on the regulation of macrophages was at least in part, associated with a Mincle-dependent mechanism. Collectively, our studies for the first time explore new biological functions of JAML in macrophages and conclude that JAML is an important mediator and biomarker of AKI. Pharmacologic targeting of JAML mediated signaling pathways at multiple levels may provide a novel therapeutic strategy for patients with AKI.
Authors
Wei Huang, Bi-Ou Wang, Yunfeng Hou, Yi Fu, Sijia Cui, Jinghan Zhu, Xinyu Zhan, Rongkun Li, Wei Tang, Jichao Wu, Ziying Wang, Mei Wang, Xiaojie Wang, Yan Zhang, Min Liu, Yusheng Xie, Yu Sun, Fan Yi
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