Lipotoxicity and Diabetic Nephropathy: Novel Mechanistic Insights and Therapeutic Opportunities

Lipotoxicity is characterized by the ectopic accumulation of lipids in organs different from adipose tissue. Lipotoxicity is mainly associated with dysfunctional signaling and insulin resistance response in non-adipose tissue such as myocardium, pancreas, skeletal muscle, liver, and kidney. Serum lipid abnormalities and renal ectopic lipid accumulation have been associated with the development of kidney diseases, in particular diabetic nephropathy. Chronic hyperinsulinemia, often seen in type 2 diabetes, plays a crucial role in blood and liver lipid metabolism abnormalities, thus resulting in increased non-esterified fatty acids (NEFA). Excessive lipid accumulation alters cellular homeostasis and activates lipogenic and glycogenic cell-signaling pathways. Recent evidences indicate that both quantity and quality of lipids are involved in renal damage associated to lipotoxicity by activating inflammation, oxidative stress, mitochondrial dysfunction, and cell-death. The pathological effects of lipotoxicity have been observed in renal cells, thus promoting podocyte injury, tubular damage, mesangial proliferation, endothelial activation, and formation of macrophage-derived foam cells. Therefore, this review examines the recent preclinical and clinical research about the potentially harmful effects of lipids in the kidney, metabolic markers associated with these mechanisms, major signaling pathways affected, the causes of excessive lipid accumulation, and the types of lipids involved, as well as offers a comprehensive update of therapeutic strategies targeting lipotoxicity

The coming age of flavonoids in the treatment of diabetic complications

Diabetes mellitus (DM), and its micro and macrovascular complications, is one of the biggest challenges for world public health. Despite overall improvement in prevention, diagnosis and treatment, its incidence is expected to continue increasing over the next years. Nowadays, finding therapies to prevent or retard the progression of diabetic complications remains an unmet need due to the complexity of mechanisms involved, which include inflammation, oxidative stress and angiogenesis, among others. Flavonoids are natural antioxidant compounds that have been shown to possess anti-diabetic properties. Moreover, increasing scientific evidence has demonstrated their potential anti-inflammatory and anti-oxidant effects. Consequently, the use of these compounds as anti-diabetic drugs has generated growing interest, as is reflected in the numerous in vitro and in vivo studies related to this field. Therefore, the aim of this review is to assess the recent pre-clinical and clinical research about the potential effect of flavonoids in the amelioration of diabetic complications. In brief, we provide updated information concerning the discrepancy between the numerous experimental studies supporting the eficacy of flavonoids on diabetic complications and the lack of appropriate and well-designed clinical trials. Due to the well-described beneficial effects on different mechanisms involved in diabetic complications, the excellent tolerability and low cost, future randomized controlled studies with compounds that have adequate bioavailability should be evaluated as add-on therapy on well-established anti-diabetic drugsThis paper was not funded. The authors work has been supported by FEDER-ISCIII Funds (PI17/00130, PI17/01495), Spanish Ministry of Economy and Competitiveness (RTI2018-098788-B-100, DTS17/00203, DTS19/00093, RYC-2017-22369), Spanish Society of Cardiology (SEC), Spanish Society of Nephrology (SEN) and Spanish Society of Atherosclerosis (SEA). TCO is an employee of FAES Pharma. The authors (except JAM) have an ongoing research project in common with FAES Pharma on Flavonoids in diabetic complications under the auspices of the joint-RETOS Collaborations Project 2017 (RTC-2017-6089-1), program supported by Spanish Ministry of Economy and Competitiveness

Targeting nf-κb by the cell-permeable nemo-binding domain peptide improves albuminuria and renal lesions in an experimental model of type 2 diabetic nephropathy

Diabetic nephropathy (DN) is a multifactorial disease characterized by hyperglycemia and close interaction of hemodynamic, metabolic and inflammatory factors. Nuclear factor-κB (NF-κB) is a principal matchmaker linking hyperglycemia and inflammation. The present work investigates the cell-permeable peptide containing the inhibitor of kappa B kinase γ (IKKγ)/NF-κB essential modulator (NEMO)-binding domain (NBD) as therapeutic option to modulate inflammation in a preclinical model of type 2 diabetes (T2D) with DN. Black and tan, brachyuric obese/obese mice were randomized into 4 interventions groups: Active NBD peptide (10 and 6 µg/g body weight); Inactive mutant peptide (10 µg/g); and vehicle control. In vivo/ex vivo fluorescence imaging revealed efficient delivery of NBD peptide, systemic biodistribution and selective renal metabolization. In vivo administration of active NBD peptide improved albuminuria (>40% reduction on average) and kidney damage, decreased podocyte loss and basement membrane thickness, and modulated the expression of proinflammatory and oxidative stress markers. In vitro, NBD blocked IKK-mediated NF-κB induction and target gene expression in mesangial cells exposed to diabetic-like milieu. These results constitute the first nephroprotective effect of NBD peptide in a T2D mouse model that recapitulates the kidney lesions observed in DN patients. Targeting IKK-dependent NF-κB activation could be a therapeutic strategy to combat kidney inflammation in DN.This work was supported by grants from: Fondecyt Project No 1160465 to S.M. and PhD CONICYT Grant No 21150768 to L.O-R.; Spanish Ministry of Economy and Competitiveness (MINECO/FEDER; SAF2015-63696-R to C.G-G.), Ministry of Science and Innovation (MICINN/FEDER; RTI2018-098788-B-1I00 to C.G-G.) and Instituto de Salud Carlos III (FIS/FEDER; PI17/01495 and DTS-2017/00203 to J.E.

Nephroprotective effects of synthetic flavonoid hidrosmin in experimental diabetic nephropathy

Diabetes mellitus (DM) is a high‐impact disease commonly characterized by hyperglycemia, inflammation, and oxidative stress. Diabetic nephropathy (DN) is a common diabetic microvascular complication and the leading cause of chronic kidney disease worldwide. This study investigates the protective effects of the synthetic flavonoid hidrosmin (5‐O‐(beta-hydroxyethyl) diosmin) in experimental DN induced by streptozotocin injection in apolipoprotein E deficient mice. Oral administration of hidrosmin (300 mg/kg/day, n = 11) to diabetic mice for 7 weeks markedly reduced albuminuria (albumin‐to‐creatinine ratio: 47 ± 11% vs. control) and ameliorated renal pathological damage and expression of kidney injury markers. Kidneys of hidrosmin‐treated mice exhibited lower content of macrophages and T cells, reduced expression of cytokines and chemokines, and attenuated inflammatory signaling pathways. Hidrosmin treatment improved the redox balance by reducing prooxidant enzymes and enhancing antioxidant genes, and also decreased senescence markers in diabetic kidneys. In vitro, hidrosmin dose‐dependently reduced the expression of inflammatory and oxidative genes in tubuloepithelial cells exposed to either high‐glucose or cytokines, with no evidence of cytotoxicity at effective concentrations. In conclusion, the synthetic flavonoid hidrosmin exerts a beneficial effect against DN by reducing inflammation, oxidative stress, and senescence pathways. Hidrosmin could have a potential role as a coadjutant therapy for the chronic complications of DM.This work was supported by grants from the Spanish Ministry of Science and Innovation- FEDER funds (Retos Colaboración RTC2017-6089-1 and Retos Investigación RTI2018-098788-B-I00) and Instituto de Salud Carlos III (PI20/00487 and DTS 19/00093

Pathogenic pathways and therapeutic approaches targeting inflammation in diabetic nephropathy

Diabetic nephropathy (DN) is associated with an increased morbidity and mortality, resulting in elevated cost for public health systems. DN is the main cause of chronic kidney disease (CKD) and its incidence increases the number of patients that develop the end-stage renal disease (ESRD). There are growing epidemiological and preclinical evidence about the close relationship between inflammatory response and the occurrence and progression of DN. Several antiinflammatory strategies targeting specific inflammatory mediators (cell adhesion molecules, chemokines and cytokines) and intracellular signaling pathways have shown beneficial effects in experimental models of DN, decreasing proteinuria and renal lesions. A number of inflammatory molecules have been shown useful to identify diabetic patients at high risk of developing renal complications. In this review, we focus on the key role of inflammation in the genesis and progression of DN, with a special interest in effector molecules and activated intracellular pathways leading to renal damage, as well as a comprehensive update of new therapeutic strategies targeting inflammation to prevent and/or retard renal injury.The authors work has been supported by grants from Instituto de Salud Carlos III (ISCIII, FIS-FEDER PI17/00130, PI17/01495, PI19/00588, ERA-PerMed-JTC2018-PERSTIGAN AC18/00071), Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) and Cardiovascular (CIBERCV), Fondecyt Project (No. 1160465), Spanish Ministry of Science and Innovation (RTI2018-098788-B-100, DTS17/00203, DTS19/00093, RYC-2017-22369), and Spanish Societies of Cardiology (SEC), Nephrology (SEN) and Atherosclerosis (SEA). The “PFIS” and “Sara Borrell” training program of the ISCIII supported the salary of MGH (FI18/00310), SR-M (CD19/00021) and CH-B (CP16/00017). Córdoba University supported the salary of C.G.C

Toll-like receptors in acute kidney injury

Acute kidney injury (AKI) is an important health problem, affecting 13.3 million individuals/year. It is associated with increased mortality, mainly in low- and middle-income countries, where renal replacement therapy is limited. Moreover, survivors show adverse long-term outcomes, including increased risk of developing recurrent AKI bouts, cardiovascular events, and chronic kidney disease. However, there are no specific treatments to decrease the adverse consequences of AKI. Epidemiological and preclinical studies show the pathological role of inflammation in AKI, not only at the acute phase but also in the progression to chronic kidney disease. Toll-like receptors (TLRs) are key regulators of the inflammatory response and have been associated to many cellular processes activated during AKI. For that reason, a number of anti-inflammatory agents targeting TLRs have been analyzed in preclinical studies to decrease renal damage during AKI. In this review, we updated recent knowledge about the role of TLRs, mainly TLR4, in the initiation and development of AKI as well as novel compounds targeting these molecules to diminish kidney injury associated to this pathological conditionThe authors work has been supported by grants from Instituto de Salud Carlos III (ISCIII, FIS-FEDER PI17/00130, PI17/01495, PI20/00375, PI20/00487), Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) and Cardiovascular (CIBERCV), Spanish Ministry of Science and Innovation (RTI2018-099114-B-100, RTI2018-098788-B-100, DTS19/00093, RYC-2017-22369), and Spanish Societies of Cardiology (SEC), Nephrology (SEN) and Atherosclerosis (SEA). The “PFIS” and “Sara Borrell” training program of the ISCIII supported the salary of MGH (FI18/00310), SR-M (CD19/00021) and CH-B (CP16/00017). Córdoba University supported the salary of C.G.C

Neutrophils play a key role in the initiation of glomerular hematuria in a postinfectious igan experimental model

2 p.BACKGROUND AND AIMS: Hematuria is a common finding in patients with IgA nephropathy (IgAN), occurring mainly after upper respiratory tract infections.Hematuria can lead to acute kidney injury and chronic loss of renal function in IgAN.However, the mechanisms involved in egression of erythrocytes from the glomerular capillaries into the urinary space are unknown. To answer this question, we developed an infection with Streptococcus pneumoniae (SP) in a humanized experimental IgAN model (a1KICD89tg mice) that resembles the pathological and clinical findings of disease (IgA1 and soluble CD89 mesangial deposits, complement activation,proteinuria and hematuria).METHOD: a1KICD89tg mice (12 weeks old) received an intranasal instillation of SP(107 bacteria). Blood, urine and renal samples were obtained during 1 month after induction of respiratory infection. The presence of SP in lungs from these mice was confirmed by microbiological analysis. Hematuria was quantified in the urinary sediment and renal function was determined by biochemical analysis. Renal histological characteristics were evaluated by hematoxylin/eosin, masson’s trichrome and PAS staining. IgA glomerular deposits, activation of complement system and infiltration of proinflammatory cells was examined by immunohistochemistry or immunofluorescence. Circulating leukocyte populations were studied on a hemocytometer. Renal inflammatory cytokines, metalloproteases, as well as markers of tubular and glomerular damage were determined in kidneys by RT-PCR and western-blot. To further validate the role of neutrophils in this pathological setting, we selective depleted these cells through a single injection of anti-Ly6G mAb (200 mg/kg i.p).RESULTS: SP-intranasal instillation in a1KICD89tg mice increased hematuria,microalbuminuria and proteinuria, peaking at 48h after induction of the respiratory infection. SP instillation caused disruption of the glomerular basement membrane,with decreased expression of the slit diaphragm proteins nephrin and synaptopodin, as well as higher glomerular accumulation of IgA and proteins of complement system (C3, MBL). Hematuria intensity was positively correlated with the presence of interstitial F4/80þ macrophages, matrix metalloproteinase 9 (MMP-9), inflammatory cytokines and chemokines (IL-1b, IL-6, TNF-a, CCL-2, CCL5 and CX3CL1/CX3CR1) as well as p65 NF-jB activation. Hematuria was negatively correlated with anti inflammatory IL-10 mRNA expression, Factor H levels and collagen IV content. Notably, SP infection induced expression of the tubular injury markers N-GAL andKIM-1. Increased peripheral neutrophils levels were observed in the SP-infected a1KICD89tg mice. Mechanistically, anti-Ly6G-mediated neutrophil depletion reduced SP-mediated hematuria, proteinuria and albuminuria, prevented loss of synaptopodin and nephrin, decreased renal inflammation and MMP-9 expression in a1KICD89tg mice.CONCLUSION: In a humanized mouse model of IgAN, hematuria bouts following respiratory tract infections are caused by a neutrophil-mediated alteration of the glomerular filtration barrier (podocyte damage, complement deposits and loss of Collagen IV). These findings may help to unveil novel potential therapeutic approaches to combat one of the key elements in the progression of IgAN and related conditions.Peer reviewe

Modulación del microambiente inflamatorio en la progresión de la enfermedad renal diabética

Esta tesis tiene embargado el acceso al texto completo hasta el 05-06-2020Tesis doctoral inédita cotutelada por la Universidad Austral de Chile y la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Medicina. Fecha de lectura: 05-12-2018La Diabetes Mellitus es un problema de salud pública mundial, siendo la Nefropatía Diabética (ND) la principal causa de Enfermedad Renal Terminal. Aunque los actuales tratamientos enlentecen la evolución de la enfermedad, es necesario establecer nuevas estrategias terapéuticas en estadios tempranos, con el fin promover la renoprotección y retrasar la terapia de reemplazo renal. La activación de la vía NF-κB y JAK/STAT contribuyen significativamente en la progresión del daño renal a través de la generación de una cascada inflamatoria, que puede ser controlada por diferentes mecanismos, entre los que se encuentran los péptidos inhibidores transcripcionales NBD y MiS1, respectivamente. A través de la caracterización del daño renal temprano determinado en el modelo BTBR ob/ob, se propuso un tratamiento de 7 semanas de duración por administración intraperitoneal de péptidos NBD y MiS1 a partir de la 6ª semana. Se monitoreo glicemia capilar, peso corporal, proteinuria y parámetros bioquímicos. Los resultados muestran reducción de la proteinuria y daño histopatológico con mejora en el recuento de podocitos en ambos tratamientos, sin modificación de parámetros metabólicos. Por su parte, el péptido MiS1 reduce la microinflamación renal por inhibición de la actividad de STAT1/STAT3, restricción de la infiltración de monocitos/macrófagos F4/80+ y linfocitos T CD3+ y reducción en la expresión génica de citoquinas y quimioquinas pro-inflamatorias. Reducción del estrés oxidativo por regulación del eje NRF2/HO-1, que restringe la producción de anión superóxido y modula la expresión génica de marcadores del balance REDOX. Efectos anti-lipotóxicos fueron observados tanto a nivel renal como a nivel hepático. De acuerdo a estos resultados, el péptido MiS1 es efectivo en modular el microambiente inflamatorio, oxidativo y lipotóxico en una etapa temprana de daño renal en el modelo BTBR ob/ob.Diabetes Mellitus is a global public health problem, with Diabetic Nephropathy (DN) being the main cause of end-stage kidney disease. Although current treatments deaccelerate the progression of the disease, it is necessary to define new therapeutic strategies in early stages, in order to promote the renoprotection and delay the renal replacement therapy. Activation of the NF-κB and JAK/STAT pathway significantly contributes to the progression of kidney damage through the generation of an inflammatory cascade, which can be controlled by different mechanisms, among which are the transcriptional inhibitor peptides NBD and MiS1, respectively. Through the characterization of early renal damage determined in the BTBR ob / ob model, a 7-week treatment was proposed by intraperitoneal administration of NBD and MiS1 peptides beginning at the 6th week. glycemia, body weight, proteinuria and biochemical parameters were monitored each week. The results showed reduction of proteinuria and histopathological damage with improvement in podocyte count in both treatments, without modification of metabolic parameters. On the other hand, the MiS1 peptide reduced renal microinflammation by inhibiting the activity of STAT1/STAT3, restricting the infiltration of monocytes/macrophages F4/80+ and CD3+ T lymphocytes and reducing the gene expression of proinflammatory cytokines and chemokines. Reduction of oxidative stress by NRF2/HO-1 axis regulation, which restricts the production of superoxide anion and modulates the gene expression of REDOX balance markers was demostrated. Anti-lipotoxic effects were observed both in renal and hepatic level. According to these results, the MiS1 peptide is effective in modulating the inflammatory, oxidative and lipotoxic microenvironment at an early stage of renal damage in the BTBR ob/ob model

Anti-inflammatory, antioxidant and renoprotective effects of SOCS1 mimetic peptide in the BTBR ob/ob mouse model of type 2 diabetes

Introduction Diabetic nephropathy (DN) is the leading cause of chronic kidney disease worldwide. The Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway participates in the development and progression of DN. Among the different mechanisms involved in JAK/STAT negative regulation, the family of suppressor of cytokine signaling (SOCS) proteins has been proposed as a new target for DN. Our aim was to evaluate the effect of SOCS1 mimetic peptide in a mouse model of obesity and type 2 diabetes (T2D) with progressive DN.Research design and methods Six-week-old BTBR (black and tan brachyuric) mice with the ob/ob (obese/obese) leptin-deficiency mutation were treated for 7 weeks with two different doses of active SOCS1 peptide (MiS1 2 and 4 µg/g body weight), using inactive mutant peptide (Mut 4 µg) and vehicle as control groups. At the end of the study, the animals were sacrificed to obtain blood, urine and kidney tissue for further analysis.Results Treatment of diabetic mice with active peptide significantly decreased urine albumin to creatinine ratio by up to 50%, reduced renal weight, glomerular and tubulointerstitial damage, and restored podocyte numbers. Kidneys from treated mice exhibited lower inflammatory infiltrate, proinflammatory gene expression and STAT activation. Concomitantly, active peptide administration modulated redox balance markers and reduced lipid peroxidation and cholesterol transporter gene expression in diabetic kidneys.Conclusion Targeting SOCS proteins by mimetic peptides to control JAK/STAT signaling pathway ameliorates albuminuria, morphological renal lesions, inflammation, oxidative stress and lipotoxicity, and could be a therapeutic approach to T2D kidney disease

Semaglutide Improves Liver Steatosis and De Novo Lipogenesis Markers in Obese and Type-2-Diabetic Mice with Metabolic-Dysfunction-Associated Steatotic Liver Disease

Metabolic-dysfunction-associated steatotic liver disease (MASLD) is a prevalent clinical condition associated with elevated morbidity and mortality rates. Patients with MASLD treated with semaglutide, a glucagon-like peptide-1 receptor agonist, demonstrate improvement in terms of liver damage. However, the mechanisms underlaying this beneficial effect are not yet fully elucidated. We investigated the efficacy of semaglutide in halting MASLD progression using a genetic mouse model of diabesity. Leptin-receptor-deficient mice with obesity and diabetes (BKS db/db) were either untreated or administered with semaglutide for 11 weeks. Changes in food and water intake, body weight and glycemia were monitored throughout the study. Body fat composition was assessed by dual-energy X-ray absorptiometry. Upon sacrifice, serum biochemical parameters, liver morphology, lipidomic profile and liver-lipid-related pathways were evaluated. The semaglutide-treated mice exhibited lower levels of glycemia, body weight, serum markers of liver dysfunction and total and percentage of fat mass compared to untreated db/db mice without a significant reduction in food intake. Histologically, semaglutide reduced hepatic steatosis, hepatocellular ballooning and intrahepatic triglycerides. Furthermore, the treatment ameliorated the hepatic expression of de novo lipogenesis markers and modified lipid composition by increasing the amount of polyunsaturated fatty acids. The administration of semaglutide to leptin-receptor-deficient, hyperphagic and diabetic mice resulted in the amelioration of MASLD, likely independently of daily caloric intake, suggesting a direct effect of semaglutide on the liver through modulation of the lipid profile