The glomerular filtration barrier (GFB) produces primary urine and is composed of a fenestrated endothelium, a glomerular basement membrane (GBM), podocytes, and a slit diaphragm. Impairment of the GFB leads to albuminuria and microhematuria. The GBM is generated via secreted proteins from both endothelial cells and podocytes and is supposed to majorly contribute to filtration selectivity. While genetic mutations or variations of GBM components have been recently proposed to be a common cause of glomerular diseases, pathways modifying and stabilizing the GBM remain incompletely understood. Here, we identified prolyl 3-hydroxylase 2 (P3H2) as a regulator of the GBM in an a cohort of patients with albuminuria. P3H2 hydroxylates the 3′ of prolines in collagen IV subchains in the endoplasmic reticulum. Characterization of a P3h2ΔPod mouse line revealed that the absence of P3H2 protein in podocytes induced a thin basement membrane nephropathy (TBMN) phenotype with a thinner GBM than that in WT mice and the development of microhematuria and microalbuminuria over time. Mechanistically, differential quantitative proteomics of the GBM identified a significant decrease in the abundance of collagen IV subchains and their interaction partners in P3h2ΔPod mice. To our knowledge, P3H2 protein is the first identified GBM modifier, and loss or mutation of P3H2 causes TBMN and focal segmental glomerulosclerosis in mice and humans.
Hande Aypek, Christoph Krisp, Shun Lu, Shuya Liu, Dominik Kylies, Oliver Kretz, Guochao Wu, Manuela Moritz, Kerstin Amann, Kerstin Benz, Ping Tong, Zheng-mao Hu, Sulaiman M. Alsulaiman, Arif O. Khan, Maik Grohmann, Timo Wagner, Janina Müller-Deile, Hartmut Schlüter, Victor G. Puelles, Carsten Bergmann, Tobias B. Huber, Florian Grahammer
The roles of neutrophils in renal inflammation are currently unclear. On examining these cells in the unilateral ureteral obstruction murine model of chronic kidney disease, we found that the injured kidney bore a large and rapidly expanding population of neutrophils that expressed the eosinophil marker Siglec-F. We first confirmed that these cells were neutrophils. Siglec-F+ neutrophils were recently detected for the first time by several studies on other disease contexts. We then showed that (i) these cells were derived from conventional neutrophils in the renal vasculature by TGF-β1 and GM-CSF, (ii) they differed from their parent cells by more frequent hypersegmentation, higher expression of pro-fibrotic inflammatory cytokines, and, notably, expression of Collagen 1, and (iii) their depletion reduced collagen deposition and disease progression, but adoptive transfer increased renal fibrosis. These findings have thus unveiled a subtype of neutrophils that participate in renal fibrosis and maybe a new therapeutic target in chronic kidney disease.
Seungwon Ryu, Jae Woo Shin, Soie Kwon, Jiwon Lee, Yong Chul Kim, Yoe-Sik Bae, Yong-Soo Bae, Dong Ki Kim, Yon Su Kim, Seung Hee Yang, Hye Young Kim
As life expectancy continues to increase, clinicians are challenged by age-related renal impairment that involves podocyte senescence and glomerulosclerosis. There is now compelling evidence that lithium has a potent antiaging activity that ameliorates brain aging and increases longevity in Drosophila and Caenorhabditis elegans. As the major molecular target of lithium action and a multitasking protein kinase recently implicated in a variety of renal diseases, glycogen synthase kinase 3β (GSK3β) is overexpressed and hyperactive with age in glomerular podocytes, correlating with functional and histological signs of kidney aging. Moreover, podocyte-specific ablation of GSK3β substantially attenuated podocyte senescence and glomerular aging in mice. Mechanistically, key mediators of senescence signaling, such as p16INK4A and p53, contain high numbers of GSK3β consensus motifs, physically interact with GSK3β, and act as its putative substrates. In addition, therapeutic targeting of GSK3β by microdose lithium later in life reduced senescence signaling and delayed kidney aging in mice. Furthermore, in psychiatric patients, lithium carbonate therapy inhibited GSK3β activity and mitigated senescence signaling in urinary exfoliated podocytes and was associated with preservation of kidney function. Thus, GSK3β appears to play a key role in podocyte senescence by modulating senescence signaling and may be an actionable senostatic target to delay kidney aging.
Yudong Fang, Bohan Chen, Zhangsuo Liu, Athena Y. Gong, William T. Gunning, Yan Ge, Deepak Malhotra, Amira F. Gohara, Lance D. Dworkin, Rujun Gong
Tertiary lymphoid tissues (TLTs) facilitate local T- and B-cell interactions in chronically inflamed organs. However, the cells and molecular pathways that govern TLT formation are poorly defined. Here we identify TNF superfamily CD153-CD30 signaling between two unique age-dependent lymphocyte subpopulations, CD153+PD-1+CD4+ senescence-associated T (SAT) cells and CD30+T-bet+ age-associated B cells (ABCs), as a driver for TLT expansion. SAT cells, which produced ABC-inducing factors IL21 and IFNγ, and ABCs progressively accumulated within TLTs in aged kidneys after injury. Notably, in kidney injury models, CD153 or CD30 deficiency impaired functional SAT cell induction, which resulted in reduced ABC numbers and attenuated TLT formation with improved inflammation, fibrosis and renal function. Attenuated TLT formation after transplantation of CD153-deficient bone marrow further supported the importance of CD153 in immune cells. Clonal analysis revealed that SAT cells and ABCs in the kidneys arose from both local differentiation and recruitment from the spleen. In the synovium of aged rheumatoid arthritis patients, T peripheral helper/T follicular helper cells and ABCs also expressed CD153 and CD30, respectively. Together, our data reveal a previously unappreciated function of CD153-CD30 signaling in TLT formation and propose targeting CD153-CD30 signaling pathway as a therapeutic target for slowing kidney disease progression.
Yuki Sato, Akiko Oguchi, Yuji Fukushima, Kyoko Masuda, Naoya Toriu, Keisuke Taniguchi, Takahisa Yoshikawa, Xiaotong Cui, Makiko Kondo, Takeshi Hosoi, Shota Komidori, Yoko Shimizu, Harumi Fujita, Li Jiang, Yingyi Kong, Takashi Yamanashi, Jun Seita, Takuya Yamamoto, Shinya Toyokuni, Yoko Hamazaki, Masakazu Hattori, Yasunobu Yoshikai, Peter Boor, Jürgen Floege, Hiroshi Kawamoto, Yasuhiro Murakawa, Nagahiro Minato, Motoko Yanagita
Chronic kidney disease (CKD) imposes a strong and independent risk for peripheral artery disease (PAD). While solutes retained in CKD patients (uremic solutes) inflict vascular damage, their role in PAD remain elusive. Here, we show that the dietary tryptophan-derived uremic solute including indoxyl sulfate (IS) and Kynurenine (Kyn), at concentrations corresponding to CKD patients suppressed β-catenin in several cell-types including microvascular endothelial cells (EC), inhibiting Wnt activity and proangiogenic Wnt targets in ECs. Mechanistic probing revealed that these uremic solutes downregulated β-catenin, dependent on serine 33 in its degron motif and through Aryl Hydrocarbon Receptor (AHR). Hindlimb ischemia in adenine-induced CKD and IS solute-specific mice models showed diminished β-catenin and VEGF-A in the capillaries and reduced capillary density, which correlated inversely with blood levels of IS and Kyn and AHR activity in ECs. An AHR inhibitor treatment normalized post-ischemic angiogenic response in CKD mice to a non-CKD level. In a prospective cohort of PAD patients, plasma levels of tryptophan metabolites and plasma’s AHR-inducing activity in ECs significantly increased the risk of future adverse limb events. This work uncovers tryptophan metabolites-AHR-β-catenin axis as a mediator of microvascular rarefaction in CKD patients and demonstrates its targetability for PAD in CKD models.
Nkiruka V. Arinze, Wenqing Yin, Saran Lotfollahzadeh, Marc Arthur Napoleon, Sean Richards, Joshua A. Walker, Mostafa Belghasem, Jonathan D. Ravid, Mohamed Hassan Kamel, Stephen A. Whelan, Norman Lee, Jeffrey J. Siracuse, Stephan Anderson, Alik Farber, David Sherr, Jean Francis, Naomi M. Hamburg, Nader Rahimi, Vipul C. Chitalia
Severe glomerular injury ultimately leads to tubulointerstitial fibrosis which determines patient outcome, but the immunological molecules connecting these two processes remain unresolved. The present study addressed whether V-domain Ig suppressor of T cell activation (VISTA), constitutively expressed in kidney macrophages, plays a protective role in tubulointerstitial fibrotic transformation after acute antibody-mediated glomerulonephritis. After acute glomerular injury using nephrotoxic serum, tubules in the VISTA-deficient (Vsir–/–) kidney suffered more damage than in wild type kidneys. When interstitial immune cells were examined, the contact frequency of macrophages with infiltrated T cells increased, and the immunometabolic features of T cells changed to high oxidative phosphorylation and fatty acid metabolism and overproduction of interferon-γ. The Vsir–/– parenchymal tissue cells responded to this altered milieu of interstitial immune cells as more interleukin-9 was produced, which augmented tubulointerstitial fibrosis. Blocking antibodies against interferon-γ and interleukin-9 protected the above pathological process in VISTA-depleted conditions. In human samples with acute glomerular injury (e.g., anti-neutrophil cytoplasmic autoantibody vasculitis), high VISTA expression in tubulointerstitial immune cells was associated with low tubulointerstitial fibrosis and good prognosis. Therefore, VISTA is a sentinel protein expressed in kidney macrophages that prevents tubulointerstitial fibrosis via the interferon-γ-interleukin-9 axis after acute antibody-mediated glomerular injury.
Min-Gang Kim, Donghwan Yun, Chae Lin Kang, Minki Hong, Juhyeon Hwang, Kyung Chul Moon, Chang Wook Jeong, Cheol Kwak, Dong Ki Kim, Kook-Hwan Oh, Kwon Wook Joo, Yon Su Kim, Dong-Sup Lee, Seung Seok Han
Coding variants in apolipoprotein L1 (APOL1), termed G1 and G2, can explain most excess kidney disease risk in African Americans; however, the molecular pathways of APOL1-induced kidney dysfunction remain poorly understood. Here, we report that expression of G2 APOL1 in the podocytes of Nphs1rtTA/TRE-G2APOL1 (G2APOL1) mice leads to early activation of the cytosolic nucleotide sensor, stimulator of interferon genes (STING), and the NLR family pyrin domain–containing 3 (NLRP3) inflammasome. STING and NLRP3 expression was increased in podocytes from patients with high-risk APOL1 genotypes, and expression of APOL1 correlated with caspase-1 and gasdermin D (GSDMD) levels. To demonstrate the role of NLRP3 and STING in APOL1-associated kidney disease, we generated transgenic mice with the G2 APOL1 risk variant and genetic deletion of Nlrp3 (G2APOL1/Nlrp3 KO), Gsdmd (G2APOL1/Gsdmd KO), and STING (G2APOL1/STING KO). Knockout mice displayed marked reduction in albuminuria, azotemia, and kidney fibrosis compared with G2APOL1 mice. To evaluate the therapeutic potential of targeting NLRP3, GSDMD, and STING, we treated mice with MCC950, disulfiram, and C176, potent and selective inhibitors of NLRP3, GSDMD, and STING, respectively. G2APOL1 mice treated with MCC950, disulfiram, and C176 showed lower albuminuria and improved kidney function even when inhibitor treatment was initiated after the development of albuminuria.
Junnan Wu, Archana Raman, Nathan J. Coffey, Xin Sheng, Joseph Wahba, Matthew J. Seasock, Ziyuan Ma, Pazit Beckerman, Dorottya Laczkó, Matthew B. Palmer, Jeffrey B. Kopp, Jay J. Kuo, Steven S. Pullen, Carine M. Boustany-Kari, Andreas Linkermann, Katalin Susztak
Apolipoprotein L1 (APOL1) risk-alleles in donor kidneys associate with graft loss but whether recipient risk-allele expression impacts transplant outcomes is unclear. To test whether recipient APOL1 risk-alleles independently correlate with transplant outcomes, we analyzed genome-wide SNP genotyping data of donors and recipients from two kidney transplant cohorts, Genomics of Chronic Allograft Rejection (GOCAR) and Clinical Trials in Organ Transplantation (CTOT1/17). We estimated genetic ancestry (quantified as proportion of African ancestry or pAFR) by ADMIXTURE and correlated APOL1 genotypes and pAFR with outcomes. In the GOCAR discovery set, we observed that the number of recipient APOL1 G1/G2 alleles (R-nAPOL1) associated with increased risk of death-censored allograft loss (DCAL), independent of ancestry (HR = 2.14; P = 0.006), and within the subgroup of African American and Hispanic (AA/H) recipients (HR = 2.36; P = 0.003). R-nAPOL1 also associated with increased risk of any T cell-mediated rejection (TCMR) event. These associations were validated in CTOT1/17. Ex vivo studies of peripheral blood mononuclear cells revealed unanticipated high APOL1 expression in activated CD4+/CD8+ T cells and natural killer cells. We detected enriched immune response gene pathways in risk-allele carriers vs. non-carriers on the kidney transplant waitlist and among healthy controls. Our findings demonstrate an immunomodulatory role for recipient APOL1 risk-alleles associating with TCMR and DCAL. This finding has broader implications for immune mediated injury to native kidneys.
Zhongyang Zhang, Zeguo Sun, Jia Fu, Qisheng Lin, Khadija Banu, Kinsuk Chauhan, Marina Planoutene, Chengguo Wei, Fadi Salem, Zhengzi Yi, Ruijie Liu, Paolo Cravedi, Haoxiang Cheng, Ke Hao, Philip J. O’Connell, Shuta Ishibe, Weijia Zhang, Steven G. Coca, Ian W. Gibson, Robert B. Colvin, John C. He, Peter S. Heeger, Barbara T. Murphy, Madhav C. Menon
The western pattern diet is rich not only in fat and calorie but also in phosphate. Negative impacts of excessive fat and calorie intake on health are widely accepted, whereas potential harms of excessive phosphate intake are poorly recognized. Here we show the mechanism by which dietary phosphate damages the kidney. When phosphate intake was excessive relative to the functioning nephron number, circulating fibroblast growth factor-23 (FGF23), a hormone that increases phosphate excretion per nephron, was increased to maintain phosphate homeostasis. FGF23 suppressed phosphate reabsorption in renal tubules and thus raised the phosphate concentration in the tubular fluid. Once it exceeded a threshold, microscopic particles containing calcium phosphate crystals appeared in the tubular lumen, which damaged tubular cells through binding to Toll-like receptor-4 expressed on them. Persistent tubular damage induced interstitial fibrosis, reduced the nephron number, and further boosted FGF23 to trigger a deterioration spiral leading to progressive nephron loss. In humans, progression of chronic kidney disease (CKD) ensued when the serum FGF23 level exceeded 53 pg/mL. The present study identified the calcium phosphate particles in the renal tubular fluid as an effective therapeutic target to decelerate nephron loss during the course of aging and CKD progression.
Kazuhiro Shiizaki, Asako Tsubouchi, Yutaka Miura, Kinya Seo, Takahiro Kuchimaru, Hirosaka Hayashi, Yoshitaka Iwazu, Marina Miura, Batpurev Battulga, Nobuhiko Ohno, Toru Hara, Rina Kunishige, Mamiko Masutani, Keita Negishi, Kazuomi Kario, Kazuhiko Kotani, Toshiyuki Yamada, Daisuke Nagata, Issei Komuro, Hiroshi Itoh, Hiroshi Kurosu, Masayuki Murata, Makoto Kuro-o
Skeletal muscle wasting is commonly associated with chronic kidney disease (CKD), resulting in increased morbidity and mortality. However, the link between kidney and muscle function remains poorly understood. Here, we took a complementary interorgan approach to investigate skeletal muscle wasting in CKD. We identified increased production and elevated blood levels of soluble pro-cachectic factors, including activin A, directly linking experimental and human CKD to skeletal muscle wasting programs. Single-cell sequencing data identified the expression of activin A in specific kidney cell populations of fibroblasts and cells of the juxtaglomerular apparatus. We propose that persistent and increased kidney production of pro-cachectic factors, combined with a lack of kidney clearance, facilitates a vicious kidney/muscle signaling cycle, leading to exacerbated blood accumulation and, thereby, skeletal muscle wasting. Systemic pharmacological blockade of activin A using soluble activin receptor type IIB ligand trap as well as muscle-specific adeno-associated virus–mediated downregulation of its receptor ACVR2A/B prevented muscle wasting in different mouse models of experimental CKD, suggesting that activin A is a key factor in CKD-induced cachexia. In summary, we uncovered a crosstalk between kidney and muscle and propose modulation of activin signaling as a potential therapeutic strategy for skeletal muscle wasting in CKD.
Francesca Solagna, Caterina Tezze, Maja T. Lindenmeyer, Shun Lu, Guochao Wu, Shuya Liu, Yu Zhao, Robert Mitchell, Charlotte Meyer, Saleh Omairi, Temel Kilic, Andrea Paolini, Olli Ritvos, Arja Pasternack, Antonios Matsakas, Dominik Kylies, Julian Schulze zur Wiesch, Jan-Eric Turner, Nicola Wanner, Viji Nair, Felix Eichinger, Rajasree Menon, Ina V. Martin, Barbara M. Klinkhammer, Elion Hoxha, Clemens D. Cohen, Pierre-Louis Tharaux, Peter Boor, Tammo Ostendorf, Matthias Kretzler, Marco Sandri, Oliver Kretz, Victor G. Puelles, Ketan Patel, Tobias B. Huber