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1.
FASEB J ; 38(7): e23584, 2024 Apr 15.
Article in English | MEDLINE | ID: mdl-38568836

ABSTRACT

Cisplatin-induced acute kidney injury (AKI) is commonly seen in the clinical practice, and ferroptosis, a type of non-apoptotic cell death, plays a pivotal role in it. Previous studies suggested that protein arginine methyltransferase 4 (PRMT4) was incorporated in various bioprocesses, but its role in renal injuries has not been investigated. Our present study showed that PRMT4 was highly expressed in renal proximal tubular cells, and it was downregulated in cisplatin-induced AKI. Besides, genetic disruption of PRMT4 exacerbated, while its overexpression attenuated, cisplatin-induced redox injuries in renal proximal epithelia. Mechanistically, our work showed that PRMT4 interacted with NCOA4 to inhibit ferritinophagy, a type of selective autophagy favoring lipid peroxidation to accelerate ferroptosis. Taken together, our study demonstrated that PRMT4 interacted with NCOA4 to attenuate ferroptosis in cisplatin-induced AKI, suggesting that PRMT4 might present as a new therapeutic target for cisplatin-related nephropathy.


Subject(s)
Acute Kidney Injury , Cisplatin , Humans , Cisplatin/adverse effects , Acute Kidney Injury/chemically induced , Acute Kidney Injury/genetics , Acute Kidney Injury/metabolism , Kidney/metabolism , Transcription Factors/metabolism , Autophagy , Nuclear Receptor Coactivators/genetics , Nuclear Receptor Coactivators/metabolism
2.
iScience ; 26(10): 107762, 2023 Oct 20.
Article in English | MEDLINE | ID: mdl-37692286

ABSTRACT

Septic acute kidney injury (S-AKI), the most common type of acute kidney injury (AKI), is intimately related to pyroptosis and oxidative stress in its pathogenesis. Carboxy-terminus of Hsc70-interacting protein (CHIP), a U-box E3 ligase, modulates oxidative stress by degrading its targeted proteins. The role of CHIP in S-AKI and its relevance with pyroptosis have not been investigated. In this study, we showed that CHIP was downregulated in renal proximal tubular cells in lipopolysaccharide (LPS)-induced S-AKI. Besides, the extent of redox injuries in S-AKI was attenuated by CHIP overexpression or activation but accentuated by CHIP gene disruption. Mechanistically, our work demonstrated that CHIP interacted with and ubiquitinated NLRP3 to promote its proteasomal degradation, leading to the inhibition of NLRP3/ACS inflammasome-mediated pyroptosis. In summary, this study revealed that CHIP ubiquitinated NLRP3 to alleviate pyroptosis in septic renal injuries, suggesting that CHIP might be a potential therapeutic target for S-AKI.

3.
J Biol Chem ; 299(9): 105185, 2023 09.
Article in English | MEDLINE | ID: mdl-37611830

ABSTRACT

A substantial body of evidence has established the contributions of both mitochondrial dynamics and lipid metabolism to the pathogenesis of diabetic kidney disease (DKD). However, the precise interplay between these two key metabolic regulators of DKD is not fully understood. Here, we uncover a link between mitochondrial dynamics and lipid metabolism by investigating the role of carbohydrate-response element-binding protein (ChREBP), a glucose-responsive transcription factor and a master regulator of lipogenesis, in kidney podocytes. We find that inducible podocyte-specific knockdown of ChREBP in diabetic db/db mice improves key biochemical and histological features of DKD in addition to significantly reducing mitochondrial fragmentation. Because of the critical role of ChREBP in lipid metabolism, we interrogated whether and how mitochondrial lipidomes play a role in ChREBP-mediated mitochondrial fission. Our findings suggest a key role for a family of ether phospholipids in ChREBP-induced mitochondrial remodeling. We find that overexpression of glyceronephosphate O-acyltransferase, a critical enzyme in the biosynthesis of plasmalogens, reverses the protective phenotype of ChREBP deficiency on mitochondrial fragmentation. Finally, our data also points to Gnpat as a direct transcriptional target of ChREBP. Taken together, our results uncover a distinct mitochondrial lipid signature as the link between ChREBP-induced mitochondrial dynamics and progression of DKD.


Subject(s)
Diabetes Mellitus , Diabetic Nephropathies , Animals , Mice , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Diabetes Mellitus/metabolism , Diabetic Nephropathies/metabolism , Gene Expression Regulation , Kidney/metabolism , Lipidomics , Transcription Factors/genetics , Transcription Factors/metabolism
5.
JCI Insight ; 7(6)2022 03 22.
Article in English | MEDLINE | ID: mdl-35315361

ABSTRACT

In this investigation, a potentially novel signaling pathway in gentamicin-induced acute kidney injury-worsened by overexpression of proximal tubular enzyme, myo-inositol oxygenase (MIOX)-was elucidated. WT, MIOX-transgenic (MIOX-Tg), and MIOX-KO mice were used. Gentamicin was administered to induce tubular injury. MIOX-Tg mice had severe tubular lesions associated with increased serum creatinine and proteinuria. Lesions were relatively mild, with no rise in serum creatinine and no albuminuria in MIOX-KO mice. Transfection of HK-2 cells with MIOX-pcDNA led to increased gentamicin-induced reactive oxygen species (ROS). Marked increase of ROS-mediated lipid hydroperoxidation was noted in MIOX-Tg mice, as assessed by 4-HNE staining. This was associated with increased expression of arachidonate 12-lipoxygenase (ALOX-12) and generation of 12-hydroxyeicosatetraenoic acid (12-HETE). In addition, notable monocyte/macrophage influx, upregulation of NF-κB and inflammatory cytokines, and apoptosis was observed in MIOX-Tg mice. Treatment of cells with ALOX-12 siRNA abolished gentamicin-mediated induction of cytokines and 12-HETE generation. HETE-12 treatment promoted this effect, along with upregulation of various signaling kinases and activation of GPCR31. Similarly, treatment of cells or mice with the ALOX-12 inhibitor ML355 attenuated inflammatory response, kinase signaling cascade, and albuminuria. Collectively, these studies highlight a potentially novel mechanism (i.e., the ROS/ALOX-12/12-HETE/GPR31 signaling axis) relevant to gentamicin-induced nephrotoxicity modulated by MIOX.


Subject(s)
Acute Kidney Injury , Inositol Oxygenase , 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/adverse effects , Acute Kidney Injury/chemically induced , Animals , Creatinine , Cytokines , Gentamicins/toxicity , Inositol Oxygenase/genetics , Inositol Oxygenase/metabolism , Mice , Reactive Oxygen Species/metabolism , Signal Transduction
6.
Am J Physiol Renal Physiol ; 322(3): F344-F359, 2022 03 01.
Article in English | MEDLINE | ID: mdl-35100813

ABSTRACT

Conceivably, like other forms of acute kidney injury, cadmium-induced renal injury may also be associated with oxidative stress and various forms of cell death, including necroptosis, a form of regulated necrosis-associated cell death. Myo-inositol oxygenase (MIOX), an enzyme localized in renal proximal tubules, regulates oxidative stress and programmed cell death in various forms of renal injuries. Herein, the role and potential mechanism(s) by which MIOX potentiates cadmium-induced renal tubular damage were investigated. Overexpression of MIOX exacerbated cadmium-induced cell death and proximal tubular injury in mice, whereas MIOX gene disruption attenuated cellular damage in vitro and in vivo. Furthermore, necroptosis was observed in the renal tubular compartment, and, more importantly, it was corroborated by inhibitor experiments with necrostatin-1 (Nec-1). Coadministration of Nec-1 dampened including receptor-interacting protein kinase (RIP)1/RIP3/mixed-lineage kinase domain-like signaling, which is relevant to the process of necroptosis. Interestingly, the necroptosis induced by cadmium in tubules was modulated by MIOX expression profile. Also, the increased reactive oxygen species generation and NADPH consumption were accelerated by MIOX overexpression, and they were mitigated by Nec-1 administration. These findings suggest that MIOX-potentiated redox injury and necroptosis are intricately involved in the pathogenesis of cadmium-induced nephropathy, and this may yield novel potential therapeutic targets for amelioration of cadmium-induced kidney injury.NEW & NOTEWORTHY This is a seminal article documenting the role of myo-inositol oxygenase (MIOX), a renal proximal tubule-specific enzyme, in the exacerbation of cadmium-induced acute kidney injury by perturbing redox balance and inducing necroptosis. MIOX gene disruption or administration of necrostatin-1 (a necroptosis inhibitor) diminished cadmium-induced renal damage, in both in vitro and in vivo systems, suggesting a therapeutic potential of MIOX to attenuate necroptosis and relevant signaling pathways in cadmium-induced renal injury.


Subject(s)
Acute Kidney Injury , Inositol Oxygenase , Acute Kidney Injury/chemically induced , Acute Kidney Injury/genetics , Acute Kidney Injury/metabolism , Animals , Cadmium/metabolism , Cadmium/toxicity , Female , Humans , Inositol Oxygenase/genetics , Inositol Oxygenase/metabolism , Kidney/metabolism , Male , Mice , Necroptosis , Oxidants
7.
Article in English | MEDLINE | ID: mdl-36612797

ABSTRACT

Depression and anxiety are common comorbid symptoms among patients with diabetic kidney disease (DKD). Little is known about the influence of poor psychological conditions on the disease progression and quality of life (QOL) in DKD patients. This study aimed to investigate the prevalence of, and risk factors for, depression and anxiety in Chinese DKD patients, and to analyze their impact on the renal function, proteinuria, and QOL. A total of 620 adult patients with Type 2 diabetes and DKD being treated at a tertiary hospital in East China were recruited. Depression and anxiety symptoms were assessed by the Zung Self-Rating Depression Scale and Anxiety Scale. Among the DKD participants, 41.3% had symptoms of depression and 45.0% had anxiety symptoms. A poor education, physical inactivity, stroke, low serum albumin, CKD stage 3-4, macroalbuminuria, and a poor QOL were independent risk factors for depression in the DKD patients. Whereas a higher education, physical inactivity, diabetic retinopathy and neuropathy, low hemoglobin, CKD stage 3-4, and a poor QOL were risk factors for anxiety. Depression and anxiety scores among the DKD patients were negatively correlated with the eGFR and QOL scores. Moreover, depression and anxiety symptoms were independent risk factors for DKD patients with CKD stage 3-4 and a poor QOL. Our findings suggest a high prevalence of depression and anxiety among Chinese DKD patients, and the severity of psychological symptoms is closely linked to the deterioration of renal function and the QOL. The early screening and intervention of psychopathological disorders is thus strongly recommended for improving the QOL and clinical outcomes among DKD patients.


Subject(s)
Diabetes Mellitus, Type 2 , Diabetic Nephropathies , Renal Insufficiency, Chronic , Humans , Adult , Diabetic Nephropathies/epidemiology , Diabetic Nephropathies/etiology , Quality of Life/psychology , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/epidemiology , Cross-Sectional Studies , Depression/epidemiology , East Asian People , Anxiety/epidemiology , Renal Insufficiency, Chronic/complications
8.
Cells ; 12(1)2022 12 21.
Article in English | MEDLINE | ID: mdl-36611810

ABSTRACT

Myo-inositol, a carbocyclic sugar, is believed to be relevant to renal pathobiology since the kidney is the major site for its catabolism. Its role in acute kidney injury (AKI) has not been fully investigated. Ferroptosis, a unique form of regulated cell death, is involved in various types of renal injuries. The relevance of myo-inositol with respect to the process of ferroptosis has not been explored either. Herein, our current exploratory studies revealed that supplementation of myo-inositol attenuates cisplatin-induced injury in cultured Boston University mouse proximal tubular (BUMPT) cells and renal tubules in vivo. Moreover, our studies unraveled that metabolic parameters pertaining to ferroptosis were disrupted in cisplatin-treated proximal tubular cells, which were seemingly remedied by the administration of myo-inositol. Mechanistically, we noted that cisplatin treatment led to the up-regulation of NOX4, a key enzyme relevant to ferroptosis, which was normalized by the administration of myo-inositol. Furthermore, we observed that changes in the NOX4 expression induced by cisplatin or myo-inositol were modulated by carboxy-terminus of Hsc70-interacting protein (CHIP), an E3 ubiquitin ligase. Taken together, our investigation suggests that myo-inositol promotes CHIP-mediated ubiquitination of NOX4 to decelerate the process of ferroptosis, leading to the amelioration of cisplatin-induced AKI.


Subject(s)
Acute Kidney Injury , Ferroptosis , Animals , Mice , Acute Kidney Injury/chemically induced , Acute Kidney Injury/drug therapy , Carrier Proteins , Cisplatin/pharmacology , Dietary Supplements , Inositol/metabolism , Inositol/pharmacology
9.
Kidney Med ; 3(4): 644-648, 2021.
Article in English | MEDLINE | ID: mdl-34401730

ABSTRACT

Kidney amyloidosis typically presents with nephrotic-range proteinuria. Rare cases of crescentic glomerulonephritis have been reported in patients with kidney amyloidosis but most cases were in the setting of patients with AA amyloidosis from long-standing inflammation and malignancy. We present a case of a previously healthy man in his 70s who was admitted with severe acute kidney injury, nephrotic-range proteinuria, and nephritic urinary sediment. Initial serologic testing for causes of rapidly progressive glomerulonephritis were negative. Kidney biopsy demonstrated the presence of active cellular and fibrocellular crescents with Congo red-positive staining in glomeruli and microvasculature on light microscopy and amyloid fibrils in glomerular basement membrane on electron microscopy. Urinary protein electrophoresis revealed monoclonal λ light chains, leading to a diagnosis of kidney AL amyloidosis, which was confirmed with bone marrow biopsy. Our case illustrates that AL amyloidosis can present with findings suspicious for rapidly progressive glomerulonephritis and crescent formation on kidney biopsy specimens.

10.
Front Med (Lausanne) ; 8: 673556, 2021.
Article in English | MEDLINE | ID: mdl-34268323

ABSTRACT

Incidence of obesity related renal disorders have increased 10-folds in recent years. One of the consequences of obesity is an increased glomerular filtration rate (GFR) that leads to the enlargement of the renal glomerulus, i.e., glomerulomegaly. This heightened hyper-filtration in the setting of type 2 diabetes irreparably damages the kidney and leads to progression of end stage renal disease (ESRD). The patients suffering from type 2 diabetes have progressive proteinuria, and eventually one third of them develop chronic kidney disease (CKD) and ESRD. For ameliorating the progression of CKD, inhibitors of renin angiotensin aldosterone system (RAAS) seemed to be effective, but on a short-term basis only. Long term and stable treatment strategies like weight loss via restricted or hypo-caloric diet or bariatric surgery have yielded better promising results in terms of amelioration of proteinuria and maintenance of normal GFR. Body mass index (BMI) is considered as a traditional marker for the onset of obesity, but apparently, it is not a reliable indicator, and thus there is a need for more precise evaluation of regional fat distribution and amount of muscle mass. With respect to the pathogenesis, recent investigations have suggested perturbation in fatty acid and cholesterol metabolism as the critical mediators in ectopic renal lipid accumulation associated with inflammation, increased generation of ROS, RAAS activation and consequential tubulo-interstitial injury. This review summarizes the renewed approaches for the obesity assessment and evaluation of the pathogenesis of CKD, altered renal hemodynamics and potential therapeutic targets.

11.
Arthritis Rheumatol ; 73(12): 2314-2326, 2021 12.
Article in English | MEDLINE | ID: mdl-34105254

ABSTRACT

OBJECTIVE: To explore the molecular mechanisms underlying dysregulation of lipid metabolism in the pathogenesis of systemic lupus erythematosus (SLE). METHODS: B cells in peripheral blood from patients with SLE and healthy controls were stained with BODIPY dye for detection of lipids. Mice with targeted knockout of genes for B cell-specific inositol-requiring enzyme 1α (IRE-1α) and stearoyl-coenzyme A desaturase 1 (SCD-1) were used for studying the influence of the IRE-1α/SCD-1/SCD-2 pathway on B cell differentiation and autoantibody production. The preclinical efficacy of IRE-1α suppression as a treatment for lupus was tested in MRL.Faslpr mice. RESULTS: In cultures with mouse IRE-1α-null B cells, supplementation with monounsaturated fatty acids largely rescued differentiation of plasma cells from B cells, indicating that the compromised capacity of B cell differentiation in the absence of IRE-1α may be attributable to a defect in monounsaturated fatty acid synthesis. Moreover, activation with IRE-1α/X-box binding protein 1 (XBP-1) was required to facilitate B cell expression of SCD-1 and SCD-2, which are 2 critical enzymes that catalyze monounsaturated fatty acid synthesis. Mice with targeted Scd1 gene deletion displayed a phenotype that was similar to that of IRE-1α-deficient mice, with diminished B cell differentiation into plasma cells. Importantly, in B cells from patients with lupus, both IRE-1α expression and Xbp1 messenger RNA splicing were significantly increased, and this was positively correlated with the expression of both Scd1 and Scd2 as well as with the amount of B cell lipid deposition. In MRL.Faslpr mice, both genetic and pharmacologic suppression of IRE-1α protected against the pathologic development and progression of lupus-like autoimmune disease. CONCLUSION: The results of this study reveal a molecular link in the dysregulation of lipid metabolism in the pathogenesis of lupus, demonstrating that the IRE-1α/XBP-1 pathway controls plasma cell differentiation through SCD-1/SCD-2-mediated monounsaturated fatty acid synthesis. These findings provide a rationale for targeting IRE-1α and monounsaturated fatty acid synthesis in the treatment of patients with SLE.


Subject(s)
Autoimmune Diseases/genetics , B-Lymphocytes/metabolism , Cell Differentiation/genetics , Endoribonucleases/genetics , Fatty Acids, Monounsaturated/metabolism , Lupus Erythematosus, Systemic/genetics , Protein Serine-Threonine Kinases/genetics , Stearoyl-CoA Desaturase/genetics , Animals , Autoimmune Diseases/metabolism , Endoribonucleases/metabolism , Humans , Lipid Metabolism/genetics , Lupus Erythematosus, Systemic/metabolism , Mice , Mice, Knockout , Protein Serine-Threonine Kinases/metabolism , Stearoyl-CoA Desaturase/metabolism
12.
J Oncol Pharm Pract ; 27(8): 2010-2013, 2021 Dec.
Article in English | MEDLINE | ID: mdl-33789526

ABSTRACT

INTRODUCTION: We report the case of a woman who developed hyperlipidemia on lorlatinib therapy found to have minimal change disease. We review therapies for cancer known to alter the lipid profile, in addition to reviewing secondary hyperlipidemia workup. We also propose a mechanism for lorlatinib-induced hyperlipidemia. CASE REPORT: A 63 year old woman with non-small cell lung adenocarcinoma on lorlatinib therapy develops marked hyperlipidemia.Management & outcome: A secondary hyperlipidemia workup is performed which reveals nephrotic range proteinuria. Minimal change disease is found on renal biopsy. The hyperlipidemia was initially responsive to statin therapy, then required addition of ezetimibe. DISCUSSION: This is a case of hyperlipidemia in a patient on lorlatinib. The case highlights that therapies for lung cancer and other malignancies have the potential to alter the lipid profile. We propose minimal change disease as a possible mechanism for lorlatinib-induced dyslipidemia. Additionally, we discuss the crucial aspects of secondary hyperlipidemia workup.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Hyperlipidemias , Lung Neoplasms , Aminopyridines , Carcinoma, Non-Small-Cell Lung/drug therapy , Female , Humans , Hyperlipidemias/chemically induced , Lactams , Lung Neoplasms/drug therapy , Middle Aged , Pyrazoles
13.
Am J Physiol Renal Physiol ; 320(4): F578-F595, 2021 04 01.
Article in English | MEDLINE | ID: mdl-33615890

ABSTRACT

Regulated cell death (RCD), distinct from accidental cell death, refers to a process of well-controlled programmed cell death with well-defined pathological mechanisms. In the past few decades, various terms for RCDs were coined, and some of them have been implicated in the pathogenesis of various types of acute kidney injury (AKI). Cisplatin is widely used as a chemotherapeutic drug for a broad spectrum of cancers, but its usage was hampered because of being highly nephrotoxic. Cisplatin-induced AKI is commonly seen clinically, and it also serves as a well-established prototypic model for laboratory investigations relevant to acute nephropathy affecting especially the tubular compartment. Literature reports over a period of three decades have indicated that there are multiple types of RCDs, including apoptosis, necroptosis, pyroptosis, ferroptosis, and mitochondrial permeability transition-mediated necrosis, and some of them are pertinent to the pathogenesis of cisplatin-induced AKI. Interestingly, myo-inositol metabolism, a vital biological process that is largely restricted to the kidney, seems to be relevant to the pathogenesis of certain forms of RCDs. A comprehensive understanding of RCDs in cisplatin-induced AKI and their relevance to myo-inositol homeostasis may yield novel therapeutic targets for the amelioration of cisplatin-related nephropathy.


Subject(s)
Acute Kidney Injury/chemically induced , Apoptosis/drug effects , Cisplatin/pharmacology , Inositol/metabolism , Necroptosis/drug effects , Acute Kidney Injury/pathology , Animals , Humans , Kidney/drug effects , Kidney/metabolism , Kidney/pathology , Mice, Inbred C57BL , Necrosis/metabolism , Necrosis/pathology , Regulated Cell Death/drug effects
14.
Transpl Infect Dis ; 23(3): e13534, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33251715

ABSTRACT

Mucormycosis infrequently may present with isolated renal involvement. Among solid organ transplant recipients, renal allograft mucormycosis has been most often associated with medical tourism or transplantation outside of the western world. We report a case of an HIV/HCV co-infected woman who underwent simultaneous liver and kidney transplantation with a Public Health Service increased risk donor organ. 16 days after transplant, she developed massive hematuria and was found to have renal allograft Rhizopus spp. involvement, we surmise to have been from donor-derived infection. Therapy included nephrectomy, debridement, liposomal amphotericin B, and posaconazole with survival. We reviewed PubMed indexed, English-language cases of isolated renal mucormycosis in general, in HIV/AIDS, and from donor-derived renal allograft infections.


Subject(s)
Kidney Transplantation , Mucormycosis , Allografts , Female , Humans , Liver , Rhizopus
15.
Kidney Int ; 99(4): 900-913, 2021 04.
Article in English | MEDLINE | ID: mdl-33316280

ABSTRACT

Aminopeptidase A is one of the most potent enzymes within the renin-angiotensin system in terms of angiotensin II degradation. Here, we examined whether there is a kidney phenotype and any compensatory changes in other renin angiotensin system enzymes involved in the metabolism of angiotensin II associated with aminopeptidase A deficiency. Kidneys harvested from aminopeptidase A knockout mice were examined by light and electron microscopy, immunohistochemistry and immunofluorescence. Kidney angiotensin II levels and the ability of renin angiotensin system enzymes in the glomerulus to degrade angiotensin II ex vivo, their activities, protein and mRNA levels in kidney lysates were evaluated. Knockout mice had increased blood pressure and mild glomerular mesangial expansion without significant albuminuria. By electron microscopy, knockout mice exhibited a mild increase of the mesangial matrix, moderate thickening of the glomerular basement membrane but a striking appearance of knob-like structures. These knobs were seen in both male and female mice and persisted after the treatment of hypertension. In isolated glomeruli from knockout mice, the level of angiotensin II was more than three-fold higher as compared to wild type control mice. In kidney lysates from knockout mice angiotensin converting enzyme activity, protein and mRNA levels were markedly decreased possibly as a compensatory mechanism to reduce angiotensin II formation. Thus, our findings support a role for aminopeptidase A in the maintenance of glomerular structure and intra-kidney homeostasis of angiotensin peptides.


Subject(s)
Glomerular Basement Membrane , Glutamyl Aminopeptidase , Kidney , Angiotensin II/metabolism , Animals , Female , Glomerular Basement Membrane/metabolism , Glutamyl Aminopeptidase/genetics , Glutamyl Aminopeptidase/metabolism , Kidney/metabolism , Male , Mice , Mice, Knockout , Renin-Angiotensin System/genetics
17.
Am J Physiol Renal Physiol ; 319(5): F765-F772, 2020 11 01.
Article in English | MEDLINE | ID: mdl-32954851

ABSTRACT

Endothelial dysfunction represents a predominant early feature of diabetes, rendering patients with diabetes prone to renal complications, e.g., proteinuria. Recent studies have indicated a possible role for xanthine oxidase (XO) in the pathogenesis of vascular dysfunctions associated with diabetes. In the present study, we investigated the contribution of XO activation on the progression of diabetic nephropathy in a mouse model using selective XO inhibitors. Male Ins2Akita heterozygous mice were used with wild-type mice as controls. Akita mice were treated with topiroxostat (Topi) or vehicle for 4 wk. Serum uric acid levels were significantly reduced in Akita + Topi mice compared with Akita + vehicle mice. The Akita + Topi group had a significant reduction in urinary albumin excretion compared with the Akita + vehicle group. Mesangial expansion, glomerular collagen type IV deposition, and glomerular endothelial injury (assessed by lectin staining and transmission electron microscopy) were considerably reduced in the Akita + topi group compared with the Akita + vehicle group. Furthermore, glomerular permeability was significantly higher in the Akita + vehicle group compared with the wild-type group. These changes were reduced with the administration of Topi. We conclude that XO inhibitors preserve glomerular endothelial functions and rescue compromised glomerular permeability, suggesting that XO activation plays a vital role in the pathogenesis of diabetic nephropathy.


Subject(s)
Ameloblasts/metabolism , Diabetic Nephropathies/metabolism , Kidney Glomerulus/metabolism , Xanthine Oxidase/metabolism , Albuminuria/metabolism , Animals , Diabetes Mellitus, Experimental/metabolism , Disease Models, Animal , Kidney/metabolism , Mice , NADPH Oxidases/metabolism , Oxidative Stress/physiology , Uric Acid/metabolism
18.
Kidney Int ; 98(6): 1489-1501, 2020 12.
Article in English | MEDLINE | ID: mdl-32822703

ABSTRACT

Delayed graft function due to transplant ischemia/reperfusion injury adversely affects up to 50% of deceased-donor kidney transplant recipients. However, key factors contributing to the severity of ischemia/reperfusion injury remain unclear. Here, using a clinically relevant mouse model of delayed graft function, we demonstrated that donor genetic background and kidney-intrinsic MyD88/Trif-dependent innate immunity were key determinants of delayed graft function. Functional deterioration of kidney grafts directly corresponded with the duration of cold ischemia time. The graft dysfunction became irreversible after cold ischemia time exceeded six hours. When cold ischemia time reached four hours, kidney grafts displayed histological features reflective of delayed graft function seen in clinical kidney transplantation. Notably, kidneys of B6 mice exhibited significantly more severe histological and functional impairment than kidneys of C3H or BALB/c mice, regardless of recipient strains or alloreactivities. Furthermore, allografts of B6 mice also showed an upregulation of IL-6, neutrophil gelatinase-associated lipocalin, and endoplasmic reticulum stress genes, as well as an increased influx of host neutrophils and memory CD8 T-cells. In contrast, donor MyD88/Trif deficiency inhibited neutrophil influx and decreased the expression of IL-6 and endoplasmic reticulum stress genes, along with improved graft function and prolonged allograft survival. Thus, kidney-intrinsic factors involving genetic characteristics and innate immunity serve as critical determinants of the severity of delayed graft function. This preclinical murine model allows for further investigations of the mechanisms underlying delayed graft function.


Subject(s)
Delayed Graft Function , Reperfusion Injury , Animals , Delayed Graft Function/genetics , Disease Models, Animal , Graft Survival , Ischemia , Kidney , Mice , Mice, Inbred BALB C , Mice, Inbred C3H , Reperfusion Injury/genetics
19.
Biomedicines ; 8(7)2020 Jul 16.
Article in English | MEDLINE | ID: mdl-32708636

ABSTRACT

Obesity is associated with perturbations in cellular energy homeostasis and consequential renal injury leading to chronic renal disease (CKD). Myo-inositol oxygenase (MIOX), a tubular enzyme, alters redox balance and subsequent tubular injury in the settings of obesity. Mechanism(s) for such adverse changes remain enigmatic. Conceivably, MIOX accentuates renal injury via reducing expression/activity of metabolic sensors, which perturb mitochondrial dynamics and, if sustained, would ultimately contribute towards CKD. In this brief communication, we utilized MIOX-TG (Transgenic) and MIOXKO mice, and subjected them to high fat diet (HFD) administration. In addition, ob/ob and ob/MIOXKO mice of comparable age were used. Mice fed with HFD had increased MIOX expression and remarkable derangements in tubular injury biomarkers. Decreased expression of p-AMPKα (phospho AMP-activated protein kinase) in the tubules was also observed, and it was accentuated in MIOX-TG mice. Interestingly, ob/ob mice also had decreased p-AMPKα expression, which was restored in ob/MIOXKO mice. Parallel changes were observed in Sirt1/Sirt3 (silent mating type information regulation 2 homolog), and expression of other metabolic sensors, i.e., PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and Yin Yang (YY-1). In vitro experiments with tubular cells subjected to palmitate-BSA and MIOX-siRNA had results in conformity with the in vivo observations. These findings link the biology of metabolic sensors to MIOX expression in impaired cellular energy homeostasis with exacerbation/amelioration of renal injury.

20.
Pathogens ; 9(8)2020 Jul 26.
Article in English | MEDLINE | ID: mdl-32722544

ABSTRACT

Transplantation tolerance is achieved when recipients are unresponsive to donor alloantigen yet mobilize against third-party antigens, including virus. After transplantation, cytomegalovirus (CMV) reactivation in latently-infected transplants reduces allograft viability. To determine if pre-tolerized recipients are resistant to viral dissemination in this setting, we transfused chemically-fixed donor splenocytes (1-ethyl-3- (3'-dimethyl-aminopropyl)-carbo-diimide (ECDI)-treated splenocytes (ECDIsp)) to induce donor antigen tolerance without immunosuppression. In parallel, we implanted donor islet cells to validate operational tolerance. These pre-tolerized recipients were implanted with murine CMV (MCMV) latently-infected donor kidneys (a validated model of CMV latency) to monitor graft inflammation and viral dissemination. Our results indicate that tolerance to donor islets was sustained in recipients after implantation of donor kidneys. In addition, kidney allografts implanted after ECDIsp and islet implantation exhibited low levels of fibrosis and tubulitis. In contrast, kidney cellular and innate immune infiltrates trended higher in the CMV group and exhibited increased markers of CD8+ T cell activation. Tolerance induction was unable to prevent increases in MCMV-specific CD8+ T cells or dissemination of viral IE-1 DNA. Our data suggest that latently-infected allografts are inherently more susceptible to inflammation that is associated with viral dissemination in pre-tolerized recipients. Thus, CMV latently-infected allografts require enhanced strategies to protect allograft integrity and viral spread.

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