Human Kidney Disease Research Articles

Small RNAs pack a punch in human kidney disease

microRNAs play prominent regulatory roles by inducing target mRNA degradation or translational repression. Several studies have highlighted the power of microRNAs as biomarkers and potential mechanistic mediators of human kidney disease. Small RNA deep sequencing libraries can be generated from minute amounts of formalin-fixed paraffin-embedded tissues including specific tissue regions. Such analyses have unique advantages and may complement analyses of fresh kidney specimens to advance tissue functional genomics-based precision medicine for human kidney disease.

Phosphorylation of key podocyte proteins and the association with proteinuric kidney disease.

Podocyte dysfunction contributes to proteinuric chronic kidney disease. A number of key proteins are essential for podocyte function, including nephrin, podocin, CD2-associated protein (CD2AP), synaptopodin, and α-actinin-4 (ACTN4). Although most of these proteins were first identified through genetic studies associated with human kidney disease, subsequent studies have identified phosphorylation of these proteins as an important posttranslational event that regulates their function. In this review, a brief overview of the function of these key podocyte proteins is provided. Second, the role of phosphorylation in regulating the function of these proteins is described. Third, the association between these phosphorylation pathways and kidney disease is reviewed. Finally, challenges and future directions in studying phosphorylation are discussed. Better characterization of these phosphorylation pathways and others yet to be discovered holds promise for translating this knowledge into new therapies for patients with proteinuric chronic kidney disease.

Guided Differentiation of Mature Kidney Podocytes from Human Induced Pluripotent Stem Cells Under Chemically Defined Conditions.

Kidney disease affects more than 10% of the global population and costs billions of dollars in federal expenditures. The most severe forms of kidney disease and eventual end-stage renal failure are often caused by the damage to the glomerular podocytes, which are the highly specialized epithelial cells that function together with endothelial cells and the glomerular basement membrane to form the kidney's filtration barrier. Advances in renal medicine have been hindered by the limited availability of primary tissues and the lack of robust methods for the derivation of functional human kidney cells, such as podocytes. The ability to derive podocytes from renewable sources, such as stem cells, could help advance current understanding of the mechanisms of human kidney development and disease, as well as provide new tools for therapeutic discovery. The goal of this protocol was to develop a method to derive mature, post-mitotic podocytes from human induced pluripotent stem (hiPS) cells with high efficiency and specificity, and under chemically defined conditions. The hiPS cell-derived podocytes produced by this method express lineage-specific markers (including nephrin, podocin, and Wilm's Tumor 1) and exhibit the specialized morphological characteristics (including primary and secondary foot processes) associated with mature and functional podocytes. Intriguingly, these specialized features are notably absent in the immortalized podocyte cell line widely used in the field, which suggests that the protocol described herein produces human kidney podocytes that have a developmentally more mature phenotype than the existing podocyte cell lines typically used to study human kidney biology.

Abstract PR02: Glyphosate as a potential carcinogen for multiple myeloma

Abstract Glyphosate is the most commercially successful and the most widely used herbicide in the United States and worldwide. It represents about 50% of United States herbicide usage at approximately 250 million pounds annually; the annual use of glyphosate worldwide is about 1.8 billion pounds. There has been considerable debate around the carcinogenicity of glyphosate. IARC labeled glyphosate as “probably carcinogenic to humans.” However, other agencies like the EPA have maintained that glyphosate is unlikely to pose a carcinogenic risk. In epidemiologic studies on the association of cancer and glyphosate, only multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) have a positive and statistically significant association with glyphosate. MM is a plasma cell neoplasm and the second most common hematologic malignancy in the United States. Virtually all MM cases are preceded by a precursor condition, monoclonal gammopathy of undetermined significance (MGUS). MM is regarded as a disease with environmental causes, yet its etiology and what prompts progression remain largely unclear. We employed the Vk*Myc mouse model of MM to assess the impact of glyphosate exposure on MM pathogenesis. In both wild-type and Vk*Myc mice, glyphosate induced splenomegaly and multiple peripheral blood abnormalities, including anemia and high serum IgG levels, hallmarks of MGUS and MM in humans. In Vk*Myc mice, glyphosate triggered bone lytic lesions, as well as renal damage, a phenomenon associated with human MM kidney disease. Most importantly, glyphosate upregulated Aicda, which encodes the activation-induced cytidine deaminase (AID) in the spleen and bone marrow of both wild-type and Vk*MYC mice. AID mediates somatic hypermutation and class-switch recombination of immunoglobulin genes in B cells to produce diverse immunoglobins in secretive forms. Our data indicate that glyphosate accelerates MGUS development and promotes progression to MM in genetically predisposed mice. Given that AID dysregulation is a key pathogenic driver in both MM and NHL, this work offers the first direct experimental evidence establishing glyphosate as an environmental risk factor for MM and NHL. This abstract is also being presented as Poster A50. Citation Format: Yong Li. Glyphosate as a potential carcinogen for multiple myeloma [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr PR02.

Distinct Functional Requirements for Podocalyxin in Immature and Mature Podocytes Reveal Mechanisms of Human Kidney Disease

Dominant and recessive mutations in podocalyxin (PODXL) are associated with human kidney disease. Interestingly, some PODXL mutations manifest as anuria while others are associated with proteinuric kidney disease. PODXL heterozygosity is associated with adult-onset kidney disease and podocalyxin shedding into the urine is a common biomarker of a variety nephrotic syndromes. It is unknown, however, how various lesions in PODXL contribute to these disparate disease pathologies. Here we generated two mouse stains: one that deletes Podxl in developmentally mature podocytes (Podxl∆Pod) and a second that is heterozygous for podocalyxin in all tissues (Podxl+/−). We used histologic and ultrastructural analyses, as well as clinical chemistry assays to evaluate kidney development and function in these strains. In contrast to null knockout mice (Podxl−/−), which die shortly after birth from anuria and hypertension, Podxl∆Pod mice develop an acute congenital nephrotic syndrome characterized by focal segmental glomerulosclerosis (FSGS) and proteinuria. Podxl+/− mice, in contrast, have a normal lifespan, and fail to develop kidney disease under normal conditions. Intriguingly, although wild-type C57Bl/6 mice are resistant to puromycin aminonucleoside (PA)-induced nephrosis (PAN), Podxl+/− mice are highly sensitive and PA induces severe proteinuria and collapsing FSGS. In summary, we find that the developmental timepoint at which podocalyxin is ablated (immature vs. mature podocytes) has a profound effect on the urinary phenotype due to its critical roles in both the formation and the maintenance of podocyte ultrastructure. In addition, Podxl∆Pod and Podxl+/− mice offer powerful new mouse models to evaluate early biomarkers of proteinuric kidney disease and to test novel therapeutics.

P0546EARLY, BUT NOT LATE, CONTRALATERAL NEPHRECTOMY OVERCOMES PROGRESSION TO CKD AFTER UNILATERAL ISCHEMIC INJURY

Abstract Background and Aims It is increasingly clear that acute kidney injury (AKI) can result in the development of chronic kidney disease (CKD) in humans. Murine renal unilateral ischemia-reperfusion injury (UIRI) models this AKI-to-CKD progression in the injured kidney in the presence of its healthy counterpart (Le Clef et al, Plos One 2016). In mice, we and others demonstrated that contralateral nephrectomy (Nx), when performed shortly after UIRI (i.e. 3 days), is able to significantly attenuate the progression to CKD. Although non-translatable, Nx can be considered an experimental therapeutic intervention that incites inherent physiological recovery mechanisms in the kidney. Here, we investigate in rats to what extent contralateral Nx is able to attenuate or revert CKD progression when performed well beyond the acute injury phase, i.e. with increased Nx delay time after UIRI. Method AKI was induced in male Wister rats by left UIRI for 60 min at 35°C core body temperature after which contralateral Nx was performed 3, 10 or 20 days later, or no Nx was performed. Control animals underwent sham-UIRI and sham-Nx 3 days later. Renal function was assessed by serum creatinine and transcutaneous GFR measurement 24h and 72h after Nx and weekly thereafter. Rats were euthanized 11 weeks after Nx. Kidneys were weighed and histology was evaluated by PAS stain for overall morphology and Sirius Red stain for interstitial fibrosis. Results When no Nx was performed, renal function of the injured kidney decreased 44% compared to control animals at week 11. Nx at day 3 induced full functional recovery from week 5 after Nx on, whereas Nx at day 10 and 20 both lead to a persistent 20% loss of renal function at week 9 after Nx (p<0.05). Nx at day 3 was able to attenuate renal atrophy and fibrotic tubulointerstitial expansion. Nx at day 10 and 20 were less efficient and led to 1.6 (p>0.05) and 2.6 (p<0.05) fold increase of tubulointerstitial area compared to controls. Nx at day 3 and 10 induced a significant increase in renal mass-to-body weight ratio compared to control from 2.9±0.1 mg/g (control) to 4.6±0.4 mg/g (day 3) and 4.8±0.3 mg/g (day 10) respectively. When Nx was performed at day 20 or no Nx was performed, renal mass-to-body weight ratio did not differ significantly from control animals, however, parallel with renal function, histopathology was considerably worse. Conclusion Early contralateral Nx after UIRI rescues renal function and morphology, whereas delayed Nx does not allow full recovery of the injured kidney. There was no additional functional loss when Nx was performed on day 20 versus day 10, though, histopathology aggravated. These results imply that a damaged kidney loses its intrinsic (compensatory) recovery potential over time and that an early intervention is crucial for averting CKD outcome after AKI.

P0129DIET INDUCED ACCELERATION OF RENAL INJURY IN THE BTBROB/OB MOUSE MODEL OF DIABETIC KIDNEY DISEASE

Abstract Background and Aims There is a need of disease relevant models for efficient evaluation of new drug targets in the renal field. The obese diabetic BTBRob/ob mouse model have features resembling important aspects of human diabetic kidney disease and is extensively used in pharmacological studies. Since diet composition plays a role in diabetic- and renal disease it is important to have detailed control of nutritional intake in our pre-clinical models, especially since many studies use in-diet drug administration. In this study we compared disease progression in obese diabetic mice on non-defined chow diet (R3) with the defined control diet D12450B (Research Diets). Method BTBRob/ob mice were fed either regular laboratory rodent chow (R3) or the defined control diet D12450B containing 35% sucrose from 6 weeks of age. The animals were studied for 14 to 20 weeks of age and both physical parameters, urine and blood parameters, histology and gene expression was examined. (R3 group n=14, D12450B group n=8). Results Mice on the defined D12450B diet displayed increased calorie- and water intake, but gained less weight compared to R3 group. Blood glucose and HbA1c was higher at all timepoints, and urinary albumin-to-creatinine ratio was highly elevated compared to mice on R3 diet. Mice fed D12450B also displayed lower levels of plasma insulin and increased plasma b-hydroxybutyrate levels. Histopathological evaluation revealed that the defined D12450B diet increased induction both of mesangial injury score and gene expression of tubular injury markers NGAL and Kim-1. Conclusion : In summary, the choice of diet composition will have a huge impact on the disease progression in diabetic leptin-deficient overeating mouse models. These finding underline the importance of describing the diet composition in detail and take precaution on diet selection for preclinical studies.

2147-PUB: Change in Matrix Metalloproteinase Activity Is Associated with Zinc Level in the Development of Renal Changes in a Diabetic Preclinical Model

Zinc is required for activation of Matrix Metalloproteinases (MMPs). Circulating zinc levels are decreased in diabetes1 and decreased activity of some MMPs is associated with the development of diabetic nephropathy (DN). The association between MMP activity and zinc in the development of DN has not been investigated and was examined in a preclinical model in this study. In this study, diabetic (DM: STZ: 3x 65mg/kg) male BALB/c mice were euthanized after 5, 10 and 30wks of diabetes. Age-matched mice acted as controls. At termination, kidneys, plasma and urine were collected for histopathology, measurement of biochemical parameters, total MMP activity using a broad spectrum MMP fluorogenic substrate and zinc level by ICPMS. In DM mice, blood glucose levels were increased at 5, 10 and 30wks (P<0.01) as were kidney/body weight (P<0.05) and urinary albumin/creatinine ratios (P<0.05). After 5wks of diabetes histopathological changes were evident and albumin/creatinine ratio increased (P<0.05). Urinary MMP activity was decreased (P<0.001) at 5wks and preceded a decrease in kidney and plasma MMP activity at 10 and 30wks (both P<0.05). DM decreased plasma but not urinary zinc levels at 10 and 30wks (both P<0.05). In DM mice, the kidney MMP activity correlated positively with plasma MMP activity (r=0.3774, P<0.03) and diabetes duration. Plasma zinc correlated with plasma MMP activity (r=-0.77, P=0.04) but only at 30wks. These results suggest an association between plasma MMP activity and zinc but only after a long duration of diabetes. The early decrease in urinary total MMP activity suggests it may have utility as a marker of early kidney disease. Whether this is so for human kidney disease is currently not known and requires further study. 1 Chabosseau and Rutter, Archives of Biochemistry and Biophysics (2016). Disclosure A. Tao: None. R. McQuilty: None. S.S. Sutanto: None. L.A. Ban: None. S.M. Twigg: Advisory Panel; Self; Abbott, AstraZeneca, Sanofi. Speaker’s Bureau; Self; Abbott, AstraZeneca, Novo Nordisk Inc., Roche Diabetes Care, Sanofi. S. McLennan: None.

Apolipoprotein L-1 renal risk variants form active channels at the plasma membrane driving cytotoxicity.

Recently evolved alleles of Apolipoprotein L-1 (APOL1) provide increased protection against African trypanosome parasites while also significantly increasing the risk of developing kidney disease in humans. APOL1 protects against trypanosome infections by forming ion channels within the parasite, causing lysis. While the correlation to kidney disease is robust, there is little consensus concerning the underlying disease mechanism. We show in human cells that the APOL1 renal risk variants have a population of active channels at the plasma membrane, which results in an influx of both Na+ and Ca2+. We propose a model wherein APOL1 channel activity is the upstream event causing cell death, and that the activate-state, plasma membrane-localized channel represents the ideal drug target to combat APOL1-mediated kidney disease.

Urinary Extracellular Vesicles as Biomarkers of Kidney Disease: From Diagnostics to Therapeutics.

Cell-derived extracellular vesicles (EVs) can be isolated from various body fluids, including urine. Urinary EVs have gained important recognition as potential diagnostic biomarkers in renal disease since their cargo includes nucleic acids, proteins, and other cellular components, which likely mirror the physiological and possibly pathophysiological state of cells along the nephron. Accumulating evidence highlights the feasibility of using EVs as biomarkers for diagnostic, prognostic, and therapeutic purposes in several forms of renal disease, such as acute kidney injury, glomerulonephritis, and renal transplantation. Additionally, exogenous delivery of EVs released in vitro by cells in culture may have salutary benefits for renal diseases. In this review, we introduce recent studies that attempt to identify urinary EVs as candidate biomarkers for human kidney diseases and consider their potential implication as a therapeutic option in key kidney diseases.

A common glomerular transcriptomic signature distinguishes diabetic kidney disease from other kidney diseases in humans and mice

BackgroundCurrent uncertainties about the similarity between human diseases and their experimental models are hampering the development of new therapies. This is especially the case for diabetic kidney disease (DKD), the most common cause of end-stage kidney disease. To better understand the nature of the commonality between humans and their mouse models, we posed the question: in diabetic kidney disease are transcriptional profiles primarily disease-specific or species-specific? MethodsWe performed a meta-comparison of the glomerular transcriptomic characteristics of 133 human and 66 mouse samples including five human kidney diseases and five mouse models, validating expression patterns of a central node by immunohistochemistry. FindingsPrincipal component analysis controlled for mouse background, revealed that gene expression changes in glomeruli from humans with DKD are more similar to those of diabetic mice than they are to other human glomerular diseases. This similarity enabled the construction of a discriminatory classifier that distinguishes diabetic glomeruli from other glomerular phenotypes regardless of their species of origin. To identify where the commonality between mice and humans with diabetes lies, networks of maximally perturbed protein interactions were examined, identifying a central role for the epidermal growth factor receptor (EGFR). By immunohistochemical staining, we found EGFR to be approximately doubled in its glomerular expression in both humans and mice. InterpretationThese findings indicate that diabetic mouse models do mimic some of the features of human kidney disease, at least with respect to their glomerular transcriptomic signatures, and they identify EGFR as being a central player in this inter-species overlap.

Zebrafish an emerging model for Preclinical Drug Discovery

For understanding the pathogenesis of human disease at cellular and molecular level bio medical research depends on the use of animal models. Maximum animal models used in medical research of human disease are basically performed in murine system. Though there are advantages of using these animals, murine’s have long gestational period, sexual maturation rate and are expensive. These invertebrates lack many structures and organ systems that are involved in human disease pathogenesis. Forward-genetic screens and random mutagenesis based reverse genetics though possible in mouse and are currently underway; they cannot be done on a large scale as they require considerable staff and infrastructure support. Due to these drawbacks other animal models have been developed that provide initial genetic or drug target information. For developmental genetic studies larval zebrafish are used extensively due to their small size, external development, optical transparency, and accessibility in large numbers. Not only are they vertebrate, they also have high fecundity, which can be easily visualised and experimentally manipulated. 70% of all human disease genes have functional homologous in zebrafish. There has been significant increase in the use of zebra fish to elucidate the etiology of human disease like cancer, infectious diseases, cardiovascular disease, kidney disease, diabetes, blindness, deafness, digestive diseases, hematopoiesis, muscle disorders and neural disorders.

Interleukin-36α as a potential biomarker for renal tubular damage induced by dietary phosphate load.

Excessive intake of phosphate has been known to induce renal tubular damage and interstitial inflammation, leading to acute kidney injury or chronic kidney disease in rodents and humans. However, sensitive and early biomarkers for phosphate‐induced kidney damage remain to be identified. Our previous RNA sequencing analysis of renal gene expression identified interleukin‐36α (IL‐36α) as a gene significantly upregulated by dietary phosphate load in mice. To determine the time course and dose dependency of renal IL‐36α expression induced by dietary phosphate load, we placed mice with or without uninephrectomy on a diet containing either 0.35%, 1.0%, 1.5%, or 2.0% inorganic phosphate for 10 days, 4 weeks, or 8 weeks and evaluated renal expression of IL‐36α and other markers of tubular damage and inflammation by quantitative RT‐PCR, immunoblot analysis, and immunohistochemistry. We found that IL‐36α expression was induced in distal convoluted tubules and correlated with phosphate excretion per nephron. The increase in IL‐36α expression was simultaneous with but more robust in amplitude than the increase in tubular damage markers such as Osteopontin and neutrophil gelatinase‐associated lipocalin, preceding the increase in expression of other inflammatory cytokines, including transforming growth factor‐α, interleukin‐1β, and transforming growth factor‐β1. We conclude that IL‐36α serves as a marker that reflects the degree of phosphate load excreted per nephron and of associated kidney damage.

Increased phosphorylation of ACTN4 leads to podocyte vulnerability and proteinuric kidney disease and is stimulated by high glucose and TGF‐b

Defects in the podocyte cytoskeleton contribute to podocyte vulnerability within the glomerulus and proteinuric kidney disease. Genetic mutations in ACTN4—an essential crosslinker of the actin cytoskeleton—have been linked to proteinuric kidney disease in humans. However, how post‐translational modifications of ACTN4 affect podocyte integrity and kidney function remain unknown. We detected phosphorylation of ACTN4 at serine 159 (S159) by mass spectrometry. Our ACTN4 X‐ray crystal structure showed that phosphomimetic S159D ACTN4 changes the charge at S159 without changing the protein’s conformation. Phosphomimetic Actn4 mouse models were generated using CRISPR/Cas9 technology, and these mice developed proteinuria and glomerulosclerosis after subtotal nephrectomy. The link between ACTN4 phosphorylation at S159 and renal pathology prompted us to use targeted mass spectrometry to identify upstream signaling pathways that might increase ACTN4 phosphorylation at S159. Since high extracellular glucose and TGF‐b can both lead to kidney disease and podocyte dysfunction, we examined whether these stimuli lead to increased ACTN4 phosphorylation at S159. We found that mean S159 phosphorylation was nearly 2‐fold higher in podocytes treated with high glucose vs mannitol control (p<0.05). Similarly, mean S159 phosphorylation was nearly 2‐fold higher in the podocytes treated with TGF‐b vs in untreated podocytes (p<0.05). Moreover, we quantified the F‐actin alignment in phalloidin‐stained podocytes. WT podocytes treated with high glucose demonstrated more spatially correlated F‐actin alignment, similar to the alignment seen in phosphomimetic Actn4 podocytes but different from nonphosphorylatable Actn4 podocytes. Our findings suggest that ACTN4 may mediate podocyte injury as a consequence of both genetic mutations and signaling events that modulate phosphorylation. Future studies using whole animal models and human samples should determine the extent to which the detrimental effects of high glucose on the kidney are mediated by phosphorylation of ACTN4.Support or Funding InformationK01DK114329, R37DK059588 and Wyss Institute for Biologically Inspired Engineering at Harvard University

CD248 plays important role in profibrotic phenotype switching of macrophages and tissue fibrosis

In human chronic kidney disease, upregulated CD248 in myofibroblasts is linked to poor renal survival. Although the role of macrophages and myofibroblasts in organ fibrosis have been extensively studied, how macrophages and myofibroblasts crosstalk to promote organ fibrosis is not clear. In this study we showed that Cd248 was upregulated in myofibroblasts in murine models of renal and peritoneal fibrosis. Cd248 knockout (Cd248−/−) could attenuate both renal and peritoneal fibrosis. By parabiosis of both the GFP reporter mice and Cd248−/− mice, we showed that decrease of fibrosis was related to a decrease in macrophage infiltration. Moreover, decreases of chemokine (C‐C motif) ligand 17 and Ccl22 was also found in Cd248−/− or galectin‐3‐deficient macrophages demonstrated that CD248 and galectin‐3 played a similar role in profibrotic phenotype switching of macrophages in injured organs. We also showed that CD248 interacted specifically with macrophage galectin‐3 and promoted myofibroblasts collagen synthesis. Mice with DNA vaccination targeting CD248 showed decreased fibrosis. We propose a novel interaction between CD248 on myofibroblasts and galectin‐3 on macrophages is a key step in mediating kidney fibrosis.Support or Funding InformationThis study is supported by Taiwan MOST (108‐2319‐B‐002‐002 and 108‐2320‐B‐002‐051‐MY3), National Core Facility for Biopharmaceuticals, and the Mrs. Hsiu‐Chin Lee Kidney Research Foundation.

A Modular Differentiation System Maps Multiple Human Kidney Lineages from Pluripotent Stem Cells

Recent studies using human pluripotent stem cells (hPSCs) have developed protocols to induce kidney-lineage cells and reconstruct kidney organoids. However, the separate generation of metanephric nephron progenitors (NPs), mesonephric NPs, and ureteric bud (UB) cells, which constitute embryonic kidneys, in invitro differentiation culture systems has not been fully investigated. Here, we create a culture system in which these mesoderm-like cell types and paraxial and lateral plate mesoderm-like cells are separately generated from hPSCs. We recapitulate nephrogenic niches from separately induced metanephric NP-like and UB-like cells, which are subsequently differentiated into glomeruli, renal tubules, and collecting ducts invitro and further vascularized invivo. Our selective differentiation protocols should contribute to understanding the mechanisms underlying human kidney development and disease and also supply cell sources for regenerative therapies.

SerpinB2 Regulates Immune Response in Kidney Injury and Aging.

Expression of SerpinB2, a regulator of inflammatory processes, has been described in the context of macrophage activation and cellular senescence. Given that mechanisms for these processes interact and can shape kidney disease, it seems plausible that SerpinB2 might play a role in renal aging, injury, and repair. We subjected SerpinB2 knockout mice to ischemia-reperfusion injury or unilateral ureteral obstruction. We performed phagocyte depletion to study SerpinB2's role beyond the effects of macrophages and transplanted bone marrow from knockout mice to wild-type mice and vice versa to dissect cell type-dependent effects. Primary tubular cells and macrophages from SerpinB2 knockout and wild-type mice were used for functional studies and transcriptional profiling. Cultured senescent tubular cells, kidneys of aged mice, and renal stress models exhibited upregulation of SerpinB2 expression. Functionally, lack of SerpinB2 in aged knockout mice had no effect on the magnitude of senescence markers but associated with enhanced kidney damage and fibrosis. In stress models, inflammatory cell infiltration was initially lower in knockout mice but later increased, leading to an accumulation of significantly more macrophages. SerpinB2 knockout tubular cells showed significantly reduced expression of the chemokine CCL2. Macrophages from knockout mice exhibited reduced phagocytosis and enhanced migration. Macrophage depletion and bone marrow transplantation experiments validated the functional relevance of these cell type-specific functions of SerpinB2. SerpinB2 influences tubule-macrophage crosstalk by supporting tubular CCL2 expression and regulating macrophage phagocytosis and migration. In mice, SerpinB2 expression seems to be needed for coordination and timely resolution of inflammation, successful repair, and kidney homeostasis during aging. Implications of SerpinB2 in human kidney disease deserve further exploration.

Cisplatin nephrotoxicity is induced via poly(ADP-ribose) polymerase activation in adult zebrafish and mice.

Cisplatin is a well-known chemotherapy medication used to treat numerous cancers. However, treatment with cisplatin in cancer therapy has major side effects, such as nephrotoxic acute kidney injury. Adult vertebrate kidneys are commonly used as models of cisplatin-induced nephrotoxic acute kidney injury. Embryonic zebrafish kidney is more simplified and is composed simply of two nephrons and thus is an excellent model for the investigation of cisplatin nephrotoxicity. Here, we developed a novel model to induce cisplatin nephrotoxicity in adult zebrafish and demonstrated that intraperitoneal injection of cisplatin caused a decline in kidney proximal tubular function based on fluorescein-labeled dextran uptake and alkaline phosphatase staining. We also showed that cisplatin induced histological injury of the kidney tubules, quantified by tubular injury scores on the periodic acid-Schiff-stained kidney sections. As shown in a mouse model of cisplatin-induced nephrotoxicity, the activation of poly(ADP-ribose) polymerase (PARP), an enzyme implicated in cisplatin-induced cell death, was markedly increased after cisplatin injection in adult zebrafish. Furthermore, pharmacological inhibition of PARP using a specific PARP inhibitor PJ 34 hydrochloride (PJ34) or 3-aminobenzamide ameliorated kidney proximal tubular functional and histological damages in cisplatin-injected adult zebrafish kidneys. Administration of a combination of PARP inhibitors PJ34 and 3-aminobenzamide additively protected renal function and histology in zebrafish and mouse models of cisplatin nephrotoxicity. In conclusion, these data suggest that adult zebrafish are not only suitable for drug screening and genetic manipulation but also useful as a simplified but powerful model to study the pathophysiology of cisplatin nephrotoxicity and establish new therapies for treating human kidney diseases.

Disease Modeling To Understand the Pathomechanisms of Human Genetic Kidney Disorders.

The class of human genetic kidney diseases is extremely broad and heterogeneous. Accordingly, the range of associated disease phenotypes is highly variable. Many children and adults affected by inherited kidney disease will progress to ESKD at some point in life. Extensive research has been performed on various different disease models to investigate the underlying causes of genetic kidney disease and to identify disease mechanisms that are amenable to therapy. We review some of the research highlights that, by modeling inherited kidney disease, contributed to a better understanding of the underlying pathomechanisms, leading to the identification of novel genetic causes, new therapeutic targets, and to the development of new treatments. We also discuss how the implementation of more efficient genome-editing techniques and tissue-culture methods for kidney research is providing us with personalized models for a precision-medicine approach that takes into account the specificities of the patient and the underlying disease. We focus on the most common model systems used in kidney research and discuss how, according to their specific features, they can differentially contribute to biomedical research. Unfortunately, no definitive treatment exists for most inherited kidney disorders, warranting further exploitation of the existing disease models, as well as the implementation of novel, complex, human patient-specific models to deliver research breakthroughs.

Aldosterone and the mineralocorticoid receptor in renal injury: A potential therapeutic target in feline chronic kidney disease.

There is a growing body of experimental and clinical evidence supporting mineralocorticoid receptor (MR) activation as a powerful mediator of renal damage in laboratory animals and humans. Multiple pathophysiological mechanisms are proposed, with the strongest evidence supporting aldosterone‐induced vasculopathy, exacerbation of oxidative stress and inflammation, and increased growth factor signalling promoting fibroblast proliferation and deranged extracellular matrix homeostasis. Further involvement of the MR is supported by extensive animal model experiments where MR antagonists (such as spironolactone and eplerenone) abrogate renal injury, including ischaemia‐induced damage. Additionally, clinical trials have shown MR antagonists to be beneficial in human chronic kidney disease (CKD) in terms of reducing proteinuria and cardiovascular events, though current studies have not evaluated primary end points which allow conclusions to made about whether MR antagonists reduce mortality or slow CKD progression. Although differences between human and feline CKD exist, feline CKD shares many characteristics with human disease including tubulointerstitial fibrosis. This review evaluates the evidence for the role of the MR in renal injury and summarizes the literature concerning aldosterone in feline CKD. MR antagonists may represent a promising therapeutic strategy in feline CKD.