Contribution of impaired Nrf2-Keap1 pathway to oxidative stress and inflammation in chronic renal failure

Natural products as Nrf2 modulators for ferroptosis inhibition in renal disease therapy: Recent progress and future prospects

BACKGROUND

The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2, NFE2L2) is a pivotal regulator of redox balance, metabolism, protein homeostasis and inflammation. Nrf2 is critically involved in both ferroptosis and renal diseases, and may serve as a significant target for many natural products in the treatment of renal diseases. However, a comprehensive overview on this topic is still lacking.

PURPOSE

To review the protective or therapeutic effects of natural products regulating Nrf2-related ferroptosis against various renal diseases.

METHODS

We systematically searched the electronic databases involving PubMed, Web of Science, Google Scholar, China National Knowledge Internet (CNKI), Wanfang Database and VIP Database. To ensure a comprehensive exploration, keywords including Nrf2, ferroptosis, natural products, phytochemicals, renal disease, kidney disease, kidney injury and nephropathy were employed.

RESULTS

Ferroptosis is deeply implicated in various kinds of renal diseases, notably including cisplatin-induced acute kidney injury, sepsis-associated acute kidney injury, renal ischemia/reperfusion injury, diabetic nephropathy, kidney stones and renal fibrosis. Nrf2 plays a regulatory role on many important genes related to iron metabolism, antioxidant system and lipid metabolism, thereby modulating ferroptosis. More than twenty natural products exert renoprotective effects by inhibiting ferroptosis via the regulation of Nrf2. This review presents a comprehensive overview of recent advancements in elucidating the ferroptosis involvement in renal diseases, the role of Nrf2 in regulating ferroptosis, and summarizes the renoprotective natural products as Nrf2 modulators for ferroptosis inhibition.

CONCLUSION

Through the comprehensive insights, this review clarifies the protective or therapeutic effects of natural products as Nrf2 modulators for ferroptosis inhibition in renal disease therapy, in the pursuit of providing new research ideas and directions for the treatment of renal diseases. Further drug development aimed at discovering more natural products and optimizing their utilization for disease treatment is necessary.

Association Between Triglyceride Glucose Index and Chronic Kidney Disease in Normal-Weight Chinese Adults With Hypertension

This study aimed to examine the association between the triglyceride-glucose (TyG) index and chronic kidney disease (CKD) in normotensive adults with hypertension and further investigate potential effect modifiers of this association. A total of 7975 normoweight hypertensive participants were enrolled from the Chinese H-type hypertension registry (CHHRS) cohort. The TyG index was calculated using the formula: ln (fasting triglyceride [mg/dL] × fasting plasma glucose [mg/dL])/2. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 of body surface area. Multivariate logistic regression analysis revealed a 50% increased risk of CKD (OR: 1.50, 95% CI: 1.26-1.79) for each unit increase in the TyG index. A linear dose-response relationship between the TyG index and CKD risk was observed using restricted cubic spline analysis. Compared to the first quartile of the TyG index, the fourth quartile showed a significantly higher risk of CKD (OR: 1.88; 95% CI: 1.41-2.50). Subgroup analysis identified a stronger association between the TyG index and CKD risk in males and individuals with a history of alcohol consumption (all p values for interaction < 0.05). In conclusions, the TyG index was significantly associated with an increased risk of CKD in normoweight adults with hypertension, particularly in males and those with a history of alcohol consumption.

Identification of serum biomarkers for chronic kidney disease using serum metabolomics

This study aimed to identify biomarkers for chronic kidney disease (CKD) by studying serum metabolomics. Serum samples were collected from 194 non-dialysis CKD patients and 317 healthy controls (HC). Using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS), untargeted metabolomics analysis was conducted. A random forest model was developed and validated in separate sets of HC and CKD patients. The serum metabolomic profiles of patients with chronic kidney disease (CKD) exhibited significant differences compared to healthy controls (HC). A total of 314 metabolites were identified as significantly different, with 179 being upregulated and 135 being downregulated in CKD patients. KEGG enrichment analysis revealed several key pathways, including arginine biosynthesis, phenylalanine metabolism, linoleic acid metabolism, and purine metabolism. The diagnostic efficacy of the classifier was high, with an area under the curve of 1 in the training and validation sets and 0.9435 in the cross-validation set. This study provides comprehensive insights into serum metabolism in non-dialysis CKD patients, highlighting the potential involvement of abnormal biological metabolism in CKD pathogenesis. Exploring metabolites may offer new possibilities for the management of CKD.

Adjuvant therapy with zinc supplementation; anti-inflammatory and anti-oxidative role in multiple myeloma patients receiving autologous hematopoietic stem cell transplantation: a randomized controlled clinical trial

Multiple myeloma (MM) patients are often accompanied by heightened levels of oxidative stress, even following bone marrow transplantation. Trace mineral supplements have been found to regulate and inhibit the activity of oxidative radicals and inflammatory factors, which are involved in the pathogenesis of MM. The study sought to evaluate the effectiveness of the supplementation by analyzing changes in oxidative, anti-oxidative, and inflammation markers. Patients were randomly assigned to a zinc or placebo group, with the former receiving 30 mg of zinc or placebo tablets daily for 1 month. Blood samples were collected from the patients on the day of transplantation, 15 days, and 30 days post-transplantation. Real-time PCR was employed to measure the expression of oxidative/antioxidative genes. Furthermore, the protein level of oxidative markers in serum samples was assessed. Finally, serum TNF-α concentrations were measured using the ELISA technique. The expression levels of SOD1, SOD2, and NRF2 genes were significantly higher on days 15 and 30 compared to the control group (P < 0.05), with a greater increase on day 30 (P < 0.05). Conversely, the expression levels of Keap1 and NOX2 genes were lower on day 30 than those of the control group (P < 0.05), with a further decrease from day 15 to day 30 (P < 0.05). The experimental group exhibited a notable reduction in TNF-α cytokine levels on day 30 compared to the control and placebo groups (P < 0.05). All findings were coordinated according to the nutritional questionnaire. Our findings suggest a potential benefit of zinc supplementation in managing the adverse effects of chemotherapy in MM patients, warranting further investigation.

Renal microRNA-144-3p is associated with transforming growth factor-β1-induced oxidative stress and fibrosis by suppressing the NRF2 pathway in hypertensive diabetic kidney disease

Chronic kidney disease (CKD) is a global health problem characterized by progressive renal fibrosis and excessive extracellular matrix deposition. Oxidative stress and epigenetic regulation, particularly through microRNAs (miRNAs), play crucial roles in the pathogenesis of CKD. In this study, we investigated the role of urinary miR-144-3p, which is upregulated in rats with CKD induced by diabetes and hypertension, in renal fibrosis progression, particularly its regulation of the nuclear factor erythroid-2-related factor 2 (NRF2) pathway. Our findings revealed elevated miR-144-3p levels and reduced NRF2 and target gene levels in kidney tissues of streptozotocin-treated spontaneously hypertensive rats. In vitro experiments demonstrated that miR-144-3p directly binds to the 3'-untranslated region of nrf2, suppressing the NRF2 pathway in renal tubular epithelial cells. Additionally, the profibrogenic factor transforming growth factor (TGF)-β1 increased miR-144-3p expression. TGF-β1-induced NRF2 suppression and reactive oxygen species elevation were found to be mediated through miR-144-3p upregulation. In vivo, cilostazol, an antiplatelet drug with an NRF2-activating effect, ameliorated renal injury in diabetic hypertensive rats by decreasing TGF-β1 and miR-144-3p levels while increasing NRF2 and its target gene levels in the kidneys. These findings highlight the potential therapeutic value of targeting the miR-144-3p/NRF2 pathway to attenuate CKD progression in hypertensive diabetic conditions.

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

G protein-coupled estrogen receptor activation attenuates cisplatin-induced CKD in C57BL/6 mice: An insight into sex-related differences

Gender contributes to differences in incidence and progression of chronic kidney disease (CKD) post-cisplatin therapy. This study aims at investigating the potential effect of G1 compound, a GPER agonist, on attenuating cisplatin-induced CKD. To induce CKD in male, intact female, and ovariectomized (OVX) mice, CKD was induced by injecting two cycles of 2.5 mg/kg cisplatin with a 16-day recovery period between cycles). G1 (50 or 100 μg/kg was administered daily for 6 weeks. Severity of renal damage was more pronounced in males than females. Interestingly, OVX resulted in renal damage that is non-significant compared to males and significantly higher than females. G1 improved renal function and blood flow as evidenced by reduction of serum creatinine and elevation of creatinine clearance, NO production, and reduction of ET1. This renoprotective effect could be attributed to its immunomodulatory effect regulated by TGF-β that shifted the balance to favor anti-inflammatory cytokine production (increased IL-10) rather than pro-inflammatory cytokines (decreased Th17 expression). Reduction of TGF-β activation also inhibited epithelial-to-mesenchymal transition that eventually ameliorated CKD development. Antioxidant potential of G1 has been demonstrated by upregulation of Nrf2 and subsequent antioxidant enzymes. These data suggest that G1 could be a promising therapeutic tool to attenuate CP-induced CKD.

Association between triglyceride-glucose index and chronic kidney disease: results from NHANES 1999-2020

AIMS

Examining the connection between the triglyceride-glucose (TyG) index and chronic kidney disease (CKD) was the aim of this investigation.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) covering the years 1999-2020 were analyzed in this study. The TyG index was calculated as Ln (triglycerides (mg/dl) * fasting glucose (mg/dl)/2). The two criteria used to diagnose CKD were low estimated glomerular filtration rate (eGFR) (eGFR < 60 mL/min/1.73m2) or albuminuria (urine albumin-to-creatinine ratio (ACR) ≥ 30 mg/g). To look into the independent associations between TyG index levels with CKD, albuminuria, and low-eGFR, weighted multivariable logistic regression and generalized additive models were employed. To assess and contrast the diagnostic ability, receiver operating characteristic (ROC) curves were employed.

RESULTS

Out of 18,078 total participants recruited, 48.54% were male. 8.48 + 0.68 was the mean value of the TyG index. CKD, albuminuria, and low-eGFR were common, with respective prevalences of 17.06%, 11.26%, and 8.03%, respectively. The TyG index and CKD were observed to positively correlate (OR = 4.03; 95% CI 1.81, 8.96). In US adults between the ages of 41 and 60, a J-shaped connection was found between the two. Furthermore, a higher TyG index is associated with a higher prevalence of albuminuria (OR = 6.11; 95% CI 2.64, 14.14). Subgroup analyses and interaction tests revealed that different stratifications did not significantly affect the relationship between TyG index and CKD, albuminuria, and low-eGFR. Comparing the TyG index to other indicators [lipid accumulation product (LAP), Visceral adiposity index (VAI), and the triglyceride glucose-body mass index (TyG-BMI)], it may be more accurate and discriminative in predicting CKD and albuminuria.

CONCLUSION

When predicting CKD and albuminuria, the TyG index may be a more useful marker when compared to other markers (LAP, VAI, and TyG-BMI index). In addition, in American adults aged 41-60, the TyG index shows a J-shaped relationship with CKD. As a result, when assessing the kidney health of US adults, we must pay close attention to the significance of the TyG index.

The Dual Burden: Exploring Cardiovascular Complications in Chronic Kidney Disease

Chronic kidney disease (CKD) represents a significant global health challenge, affecting millions of individuals and leading to substantial morbidity and mortality. This review aims to explore the epidemiology, cardiovascular complications, and management strategies associated with CKD, emphasizing the importance of preventing cardiovascular disease and early intervention. CKD is primarily driven by conditions such as diabetes mellitus, hypertension, and cardiovascular diseases, which often coexist and exacerbate renal impairment. Effective management requires a multifaceted approach, including lifestyle modifications, pharmacological interventions, and regular monitoring. Dietary changes, such as sodium restriction and a controlled intake of phosphorus and potassium, play a vital role in preserving renal function. Pharmacological therapies, particularly angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and emerging agents like SGLT2 inhibitors, have shown efficacy in slowing disease progression and improving patient outcomes. Furthermore, patients undergoing dialysis face increased cardiovascular risk, necessitating comprehensive management strategies to address both renal and cardiac health. As the landscape of CKD treatment evolves, ongoing research into novel therapeutic options and personalized medical approaches are essential. This review underscores the urgent need for awareness, education, and effective preventive measures to mitigate the burden of CKD and enhance the quality of life for affected individuals.

Association between inflammatory biomarkers and postoperative acute kidney injury after cardiac surgery in patients with preoperative renal dysfunction: a retrospective pilot analysis

BACKGROUND

Acute kidney injury (AKI) represents a significant post-cardiac surgery complication, particularly prevalent among individuals with pre-existing renal dysfunction. Chronic kidney disease (CKD) is frequently accompanied by persistent, low-grade inflammation, which is known to exacerbate systemic stress responses during surgical procedures. This study hypothesizes that these inflammatory responses might influence the incidence and severity of postoperative acute kidney injury (AKI), potentially serving as a protective mechanism by preconditioning the kidney to stress.

METHODS

This retrospective study enrolled patients with preoperative renal dysfunction (eGFR between 15 and 60 ml/min/1.73 m²) who underwent cardiac surgery between January 2020 and December 2022. Preoperative inflammatory biomarkers were evaluated. The primary outcome was the incidence of postoperative AKI, as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Multivariate regression models and sensitivity analyses were conducted to ascertain the relationship between inflammatory biomarkers and AKI. Restricted cubic spines (RCS) was conducted to explore nonlinear associations between inflammatory biomarkers and AKI.

RESULTS

AKI occurred in 53.4% (392/734) of patients, accompanied by significant mortality and length of hospital stay increases in cases of AKI (P < 0.005). After full adjustment of confounders, neutrophil percentage-to-albumin ratio (OR = 0.28), systemic inflammation response index (OR = 0.70), systemic immune inflammation index (OR = 0.69), neutrophil-to-lymphocyte ratio (OR = 0.70), monocyte/high-density lipoprotein cholesterol ratio (OR = 0.53), neutrophil/high-density lipoprotein cholesterol ratio (OR = 0.43) demonstrated an inverse association with AKI. Sensitivity analyses revealed that patients in the highest quartile of these biomarkers exhibited a significantly lower prevalence of AKI compared to those in the lowest quartile (p for trend < 0.05). The RCS analysis suggested an "Inverted U-shaped" association of both LnNPAR and LnSIRI with AKI.

CONCLUSIONS

This study identified an inverse association between preoperative inflammatory biomarkers and postoperative AKI in patients with preoperative renal dysfunction. The findings implied that preoperative inflammation may play a protective role against postoperative AKI in this patient population undergoing cardiac surgery.

Zinc: a potential star for regulating peritoneal fibrosis

Peritoneal dialysis (PD) is a commonly used renal replacement therapy for patients with end-stage renal disease (ESRD). During PD, the peritoneum (PM), a semi-permeable membrane, is exposed to nonbiocompatible PD solutions. Peritonitis can occur, leading to structural and functional PM disorders, resulting in peritoneal fibrosis and ultrafiltration failure, which are important reasons for patients with ESRD to discontinue PD. Increasing evidence suggests that oxidative stress (OS) plays a key role in the pathogenesis of peritoneal fibrosis. Furthermore, zinc deficiency is often present to a certain extent in patients undergoing PD. As an essential trace element, zinc is also an antioxidant, potentially playing an anti-OS role and slowing down peritoneal fibrosis progression. This study summarises and analyses recent research conducted by domestic and foreign scholars on the possible mechanisms through which zinc prevents peritoneal fibrosis.

Brazil nuts potential: effects on lipid peroxidation and heart health in nephrectomized rats

OBJECTIVES

To investigate the effects of a Brazil nut-enriched diet on the wall thickness and the left ventricular chamber diameter of the heart, and lipid peroxidation in a CKD-induced model.

METHODS

Male Wistar rats at 12 weeks of age were divided into two groups (n=16/group): the Nx group, which underwent 5/6 nephrectomy, and the Sham group, as a control. After 5 weeks, the groups were subdivided according to diet (n=8/group): the Nx and Sham groups received a control diet; the Nx5% and Sham5% groups received a diet enriched with 5 % Brazil nuts for 8 weeks. The left ventricular thickening and chamber diameter were determined. Plasma biochemical parameters were evaluated. Analysis of thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activity was performed in the plasma and the left ventricle (LV). LV mRNA expression of nuclear factor-kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) was evaluated by reverse transcription-polymerase chain reaction.

RESULTS

The Nx5% group showed a remodeled LV wall with decreased thickness compared to the Nx group (p=0.016). Furthermore, LV TBARS concentration was reduced in the Nx5% group (p=0.0064). In addition, the Nx5% group showed an increase in plasma GPx activity (p=0.0431). No significant results were found concerning the LV mRNA expression of NF-κB and Nrf2 genes.

CONCLUSIONS

A Brazil nut-enriched diet decreased LV thickness and LV TBARS concentration and increased GPx activity in a 5/6 nephrectomy experimental model, making it a promising adjuvant therapy to improve antioxidant status and cardiovascular outcomes in chronic kidney disease.

Zinc and Diabetes: A Connection between Micronutrient and Metabolism

Diabetes mellitus is a global health problem and a major contributor to mortality and morbidity. The management of this condition typically involves using oral antidiabetic medication, insulin, and appropriate dietary modifications, with a focus on macronutrient intake. However, several human studies have indicated that a deficiency in micronutrients, such as zinc, can be associated with insulin resistance as well as greater glucose intolerance. Zinc serves as a chemical messenger, acts as a cofactor to increase enzyme activity, and is involved in insulin formation, release, and storage. These diverse functions make zinc an important trace element for the regulation of blood glucose levels. Adequate zinc levels have also been shown to reduce the risk of developing diabetic complications. This review article explains the role of zinc in glucose metabolism and the effects of its inadequacy on the development, progression, and complications of diabetes mellitus. Furthermore, it describes the impact of zinc supplementation on preventing diabetes mellitus. The available information suggests that zinc has beneficial effects on the management of diabetic patients. Although additional large-scale randomized clinical trials are needed to establish zinc's clinical utility further, efforts should be made to increase awareness of its potential benefits on human health and disease.

Targeting Nrf2/HO-1 and NF-κB/TNF-α signaling pathways with empagliflozin protects against atrial fibrillation-induced acute kidney injury in rats

A bidirectional relationship exists between atrial fibrillation (AF) and kidney function. Uncontrolled AF may lead to kidney injury, whereas renal dysfunction may contribute to AF initiation and maintenance. This study aimed to investigate the protective effect of the sodium glucose cotransporter-2 inhibitor empagliflozin (EMPA) on acute kidney injury (AKI) associated with AF induced by acetylcholine and calcium chloride (ACh/CaCl2) in rats and elucidate the potential underlying mechanism. Rats were randomly divided as follows: control (CTRL) group: administered vehicles only; AF group: intravenously injected 1 ml/kg of an ACh/CaCl2 mixture for seven days to induce AF; EMPA group: orally administered EMPA (30 mg/kg) for seven days; AF+EMPA10 and AF+EMPA30 groups: co-administered the induction mixture and EMPA (10 and 30 mg/kg, respectively) for seven days. Our results showed that EMPA (10 and 30 mg/kg) effectively maintained kidney function and demonstrated a significant antioxidant potential. EMPA also suppressed AF-induced renal tubulointerstitial injury and fibrotic changes concurrently with reducing renal levels of the pro-inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-6, as well as the pro-fibrotic marker transforming growth factor beta-1 and collagen type I. Mechanistically, EMPA boosted nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) renal tissue expression while repressing nuclear factor kappa B (NF-κB) activation. In addition, these beneficial effects of EMPA on kidneys were concurrent with its ability to effectively inhibit AF-related electrocardiographic changes, reduce incidence and duration of AF episodes, and markedly suppress serum B-type natriuretic peptide and C-reactive protein levels. In conclusion, EMPA protected against AKI associated with AF induced by ACh/CaCl2 in rats through simultaneous modulation of the Nrf2/HO-1 and the NF-κB/TNF-α signaling pathways, exerting antioxidant, anti-inflammatory, and anti-fibrotic effects.

Targeting Nrf2 signaling pathways in the role of bladder cancer: From signal network to targeted therapy

Bladder cancer (BC) is the most common malignancy of the urinary system and often recurs after tumor removal and/or is resistant to chemotherapy. In cancer cells, the activity of the signaling pathway changes significantly, affecting a wide range of cell activities from growth and proliferation to apoptosis, invasion and metastasis. Nrf2 is a transcription factor that plays an important role in cellular defense responses to a variety of cellular stresses. There is increasing evidence that Nrf2 acts as a tumor driver and that it is involved in the maintenance of malignant cell phenotypes. Abnormal expression of Nrf2 has been found to be common in a variety of tumors, including bladder cancer. Over-activation of Nrf2 can lead to DNA damage and the development of bladder cancer, and is also associated with various pathological phenomena of bladder cancer, such as metastasis, angiogenesis, and reduced toxicity and efficacy of therapeutic anticancer drugs to provide cell protection for cancer cells. However, the above process can be effectively inhibited or reversed by inhibiting Nrf2. Therefore, Nrf2 signaling may be a potential targeting pathway for bladder cancer. In this review, we will characterize this signaling pathway and summarize the effects of Nrf2 and crosstalk with other signaling pathways on bladder cancer progression. The focus will be on the impact of Nrf2 activation on bladder cancer progression and current therapeutic strategies aimed at blocking the effects of Nrf2. To better determine how to promote new chemotherapy agents, develop new therapeutic agents, and potential therapeutic targets.

Potential role of molecular hydrogen therapy on oxidative stress and redox signaling in chronic kidney disease

Oxidative stress plays a key role in chronic kidney disease (CKD) development and progression, inducing kidney cell damage, inflammation, and fibrosis. However, effective therapeutic interventions to slow down CKD advancement are currently lacking. The multifaceted pharmacological effects of molecular hydrogen (H2) have made it a promising therapeutic avenue. H2 is capable of capturing harmful •OH and ONOO- while maintaining the crucial reactive oxygen species (ROS) involved in cellular signaling. The NRF2-KEAP1 system, which manages cell redox balance, could be used to treat CKD. H2 activates this pathway, fortifying antioxidant defenses and scavenging ROS to counteract oxidative stress. H2 can improve NRF2 signaling by using the Wnt/β-catenin pathway and indirectly activate NRF2-KEAP1 in mitochondria. Additionally, H2 modulates NF-κB activity by regulating cellular redox status, inhibiting MAPK pathways, and maintaining Trx levels. Treatment with H2 also attenuates HIF signaling by neutralizing ROS while indirectly bolstering HIF-1α function. Furthermore, H2 affects FOXO factors and enhances the activity of antioxidant enzymes. Despite the encouraging results of bench studies, clinical trials are still limited and require further investigation. The focus of this review is on hydrogen's role in treating renal diseases, with a specific focus on oxidative stress and redox signaling regulation, and it discusses its potential clinical applications.

Delaying Renal Aging: Metformin Holds Promise as a Potential Treatment

Given the rapid aging of the population, age-related diseases have become an excessive burden on global health care. The kidney, a crucial metabolic organ, ages relatively quickly. While the aging process itself does not directly cause kidney damage, the physiological changes that accompany it can impair the kidney's capacity for self-repair. This makes aging kidneys more susceptible to diseases, including increased risks of chronic kidney disease and end-stage renal disease. Therefore, delaying the progression of renal aging and preserving the youthful vitality of the kidney are crucial for preventing kidney diseases. However, effective strategies against renal aging are still lacking due to the underlying mechanisms of renal aging, which have not been fully elucidated. Accumulating evidence suggests that metformin has beneficial effects in mitigating renal aging. Metformin has shown promising anti-aging results in animal models but has not been tested for this purpose yet in clinical trials. These findings indicate the potential of metformin as an anti-renal aging drug. In this review, we primarily discuss the characteristics and mechanisms of kidney aging and the potential effects of metformin against renal aging.

Evaluation of C4d expression and staining patterns by immunohistochemistry in renal biopsy samples with focal segmental glomerulosclerosis and minimal change disease

INTRODUCTION

C4d is an activation product of lectin pathway of complement. Glomerular deposition of C4d is associated with poor prognosis in different types of immune-related glomerulonephritis. The present study was conducted to investigate expression level of C4d and its staining pattern in renal biopsy of patients with focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) by immunohistochemistry method.

MATERIALS AND METHODS

In this retrospective cross-sectional study, renal biopsy specimens from 46 samples of MCD, 47 samples of FSGS, and 15 samples without glomerular disease as the controls, were subjected to immunohistochemistry staining with C4d. Demographic characteristics and information obtained from light and electron microscopy (EM) of patients were also extracted from their files.

RESULTS

C4d positive staining was observed in 97.9 % of FSGS and 43.5 % of MCD samples, which showed a statistically significant difference (P < 0.001). The sensitivity and specificity of C4d expression for diagnosing FSGS were 97.9 % and 56.5 %, respectively. There was no significant correlation between C4d expression and any of the light and electron microscopy findings, including presence of foam cells, mesangial matrix expansion, interstitial fibrosis and tubular atrophy, and basement membrane changes in MCD patients. Also, no significant correlation was observed between C4d expression and clinical symptoms of proteinuria or prolonged high level of creatinine in patients with MCD.

DISCUSSION AND CONCLUSION

The expression of C4d marker had a good sensitivity and negative predictive value in the diagnosis of FSGS.

Indoxyl Sulfate-Induced Macrophage Toxicity and Therapeutic Strategies in Uremic Atherosclerosis

Cardiovascular disease (CVD) frequently occurs in patients with chronic kidney disease (CKD), particularly those undergoing dialysis. The mechanisms behind this may be related to traditional risk factors and CKD-specific factors that accelerate atherosclerosis and vascular calcification in CKD patients. The accumulation of uremic toxins is a significant factor in CKD-related systemic disorders. Basic research suggests that indoxyl sulfate (IS), a small protein-bound uremic toxin, is associated with macrophage dysfunctions, including increased oxidative stress, exacerbation of chronic inflammation, and abnormalities in lipid metabolism. Strategies to mitigate the toxicity of IS include optimizing gut microbiota, intervening against the abnormality of intracellular signal transduction, and using blood purification therapy with higher efficiency. Further research is needed to examine whether lowering protein-bound uremic toxins through intervention leads to a reduction in CVD in patients with CKD.

Correlation between the triglyceride-glucose index and chronic kidney disease among adults with metabolic-associated fatty liver disease: fourteen-year follow-up

Background and aims

According to previous studies, triglyceride-glucose (TyG) is related to chronic kidney disease (CKD), but no studies have explored the correlation between TyG and CKD among adults with metabolic dysfunction-associated fatty liver disease (MAFLD). We aimed to explore the associations of the TyG index with CKD among adults with MAFLD.

Methods

In this retrospective observational cohort study, data from 11,860 participants who underwent a minimum of three health assessments between 2008 and 2015 were retrospectively collected. Participants were followed up until the final medical visit or health examination. CKD refers to an eGFR < 60 mL/min per 1·73 m2 or the occurrence of two or more incidents of proteinuria.

Results

Within a median 10·02-year follow-up period, 2005 (16·9%) participants reported developing CKD. Multivariate Cox regression models indicated a noticeable correlation between the TyG index and CKD incidence (HR per unit increase, 1.19; 95% CI: 1.09-1.29) and between the TyG index and CKD incidence (HR per SD increase, 1.12; 95% CI: 1.06-1.18). The CKD incidence increased by 1.8 times in participants in the highest TyG index quartile relative to patients in the lowest quartile of the TyG index quartile (HR 1·18, 95% CI: 1.01-1.38, P = 0.007). According to subgroup analysis, an elevated TyG index is likely to become more harmful to participants younger than 60 years (P for interaction = 0.035).

Conclusion

An elevated TyG index may increase CKD incidence among MAFLD adults, particularly among younger people. Early intervention may help reduce the incidence of CKD.

Icariin alleviates renal inflammation and tubulointerstitial fibrosis via Nrf2-mediated attenuation of mitochondrial damage

Tubulointerstitial fibrosis is an inevitable consequence of all progressive chronic kidney disease (CKD) and contributes to a substantial health burden worldwide. Icariin, an active flavonoid glycoside obtained from Epimedium species, exerts potential antifibrotic effect. The study aimed to explore the protective effects of icariin against tubulointerstitial fibrosis in unilateral ureteral obstruction (UUO)-induced CKD mice and TGF-β1-treated HK-2 cells, and furthermore, to elucidate the underlying mechanisms. The results demonstrated that icariin significantly improved renal function, alleviated tubular injuries, and reduced fibrotic lesions in UUO mice. Furthermore, icariin suppressed renal inflammation, reduced oxidative stress as evidenced by elevated superoxide dismutase activity and decreased malondialdehyde level. Additionally, TOMM20 immunofluorescence staining and transmission electron microscope revealed that mitochondrial mass and morphology of tubular epithelial cells in UUO mice was restored by icariin. In HK-2 cells treated with TGF-β1, icariin markedly decreased profibrotic proteins expression, inhibited inflammatory factors, and protected mitochondria along with preserving mitochondrial morphology, reducing reactive oxygen species (ROS) and mitochondrial ROS (mtROS) overproduction, and preserving membrane potential. Further investigations demonstrated that icariin could activate nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway both in vivo and in vitro, whereas inhibition of Nrf2 by ML385 counteracted the protective effects of icariin on TGF-β1-induced HK-2 cells. In conclusion, icariin protects against renal inflammation and tubulointerstitial fibrosis at least partly through Nrf2-mediated attenuation of mitochondrial dysfunction, which suggests that icariin could be developed as a promising therapeutic candidate for the treatment of CKD.

Downregulation of the kidney glucagon receptor, essential for renal function and systemic homeostasis, contributes to chronic kidney disease

The glucagon receptor (GCGR) in the kidney is expressed in nephron tubules. In humans and animal models with chronic kidney disease, renal GCGR expression is reduced. However, the role of kidney GCGR in normal renal function and in disease development has not been addressed. Here, we examined its role by analyzing mice with constitutive or conditional kidney-specific loss of the Gcgr. Adult renal Gcgr knockout mice exhibit metabolic dysregulation and a functional impairment of the kidneys. These mice exhibit hyperaminoacidemia associated with reduced kidney glucose output, oxidative stress, enhanced inflammasome activity, and excess lipid accumulation in the kidney. Upon a lipid challenge, they display maladaptive responses with acute hypertriglyceridemia and chronic proinflammatory and profibrotic activation. In aged mice, kidney Gcgr ablation elicits widespread renal deposition of collagen and fibronectin, indicative of fibrosis. Taken together, our findings demonstrate an essential role of the renal GCGR in normal kidney metabolic and homeostatic functions. Importantly, mice deficient for kidney Gcgr recapitulate some of the key pathophysiological features of chronic kidney disease.

Effects of NRF2 polymorphisms on safety and efficacy of bardoxolone methyl: subanalysis of TSUBAKI study

BACKGROUND

In the TSUBAKI study, bardoxolone methyl significantly increased measured and estimated glomerular filtration rates (GFR) in patients with multiple forms of chronic kidney disease (CKD), including Japanese patients with type 2 diabetes and stage 3-4 CKD. Since bardoxolone methyl targets the nuclear factor erythroid 2-related factor 2 pathway, this exploratory analysis of the TSUBAKI study investigated the impact of the regulatory single nucleotide polymorphism, rs6721961, on the effects of bardoxolone methyl.

METHODS

Japanese patients aged 20-79 years with type 2 diabetes and stage 3-4 CKD were randomized to bardoxolone methyl 5-15 mg/day (titrated as tolerated) or placebo for 16 weeks. Genotype frequency, clinical characteristics, renal function, and adverse events were primarily assessed.

RESULTS

Of 104 patients (bardoxolone methyl n = 55, placebo n = 49); 57% were genotype C/C, 32% C/A and 12% A/A. The frequency of the A/A genotype was higher among patients with diabetic kidney disease than in the general Japanese population (~ 5%). Measured and estimated GFRs increased from baseline in all genotypes receiving bardoxolone methyl. There were no significant differences between genotypes for safety parameters, including blood pressure, bodyweight, and levels of B-type natriuretic peptide, or in the type and frequency of adverse events, suggesting that the efficacy and safety of bardoxolone methyl are unaffected by the rs6721961 polymorphism-617 (C→A) genotype.

CONCLUSIONS

Our approach of combining genome analysis with clinical trials for an investigational drug provides important and useful clues for exploring the efficacy and safety of the drug.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT02316821.

Exercise for patients with chronic kidney disease: from cells to systems to function

Chronic kidney disease (CKD) is among the leading causes of death and disability, affecting an estimated 800 million adults globally. The underlying pathophysiology of CKD is complex creating challenges to its management. Primary risk factors for the development and progression of CKD include diabetes mellitus, hypertension, age, obesity, diet, inflammation, and physical inactivity. The high prevalence of diabetes and hypertension in patients with CKD increases the risk for secondary consequences such as cardiovascular disease and peripheral neuropathy. Moreover, the increased prevalence of obesity and chronic levels of systemic inflammation in CKD have downstream effects on critical cellular functions regulating homeostasis. The combination of these factors results in the deterioration of health and functional capacity in those living with CKD. Exercise offers protective benefits for the maintenance of health and function with age, even in the presence of CKD. Despite accumulating data supporting the implementation of exercise for the promotion of health and function in patients with CKD, a thorough description of the responses and adaptations to exercise at the cellular, system, and whole body levels is currently lacking. Therefore, the purpose of this review is to provide an up-to-date comprehensive review of the effects of exercise training on vascular endothelial progenitor cells at the cellular level; cardiovascular, musculoskeletal, and neural factors at the system level; and physical function, frailty, and fatigability at the whole body level in patients with CKD.

Oxidative stress and the role of redox signalling in chronic kidney disease

Chronic kidney disease (CKD) is a major public health concern, underscoring a need to identify pathogenic mechanisms and potential therapeutic targets. Reactive oxygen species (ROS) are derivatives of oxygen molecules that are generated during aerobic metabolism and are involved in a variety of cellular functions that are governed by redox conditions. Low levels of ROS are required for diverse processes, including intracellular signal transduction, metabolism, immune and hypoxic responses, and transcriptional regulation. However, excess ROS can be pathological, and contribute to the development and progression of chronic diseases. Despite evidence linking elevated levels of ROS to CKD development and progression, the use of low-molecular-weight antioxidants to remove ROS has not been successful in preventing or slowing disease progression. More recent advances have enabled evaluation of the molecular interactions between specific ROS and their targets in redox signalling pathways. Such studies may pave the way for the development of sophisticated treatments that allow the selective control of specific ROS-mediated signalling pathways.

Defining the threshold: triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio's non-linear impact on tubular atrophy in primary membranous nephropathy

Background

Hyperlipidemia is common in primary membranous nephropathy (PMN) patients, and tubular atrophy (TA) is an unfavorable prognostic factor. However, the correlation between the triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio and TA is controversial. Therefore, our study aimed to investigate the association between the TG/HDL-C ratio and TA in PMN patients.

Methods

We conducted a cross-sectional study and collected data from 363 PMN patients at Shenzhen Second People's Hospital from January 2008 to April 2023. The primary objective was to evaluate the independent correlation between the TG/HDL-C ratio and TA using binary logistic regression model. We used a generalized additive model along with smooth curve fitting and multiple sensitivity analyses to explore the relationship between these variables. Additionally, subgroup analyses were conducted to delve deeper into the results.

Results

Of the 363 PMN patients, 75 had TA (20.66%). The study population had a mean age of 46.598 ± 14.462 years, with 217 (59.78%) being male. After adjusting for sex, age, BMI, hypertension, history of diabetes, smoking, alcohol consumption, UPRO, eGFR, HB, FPG, and ALB, we found that the TG/HDL-C ratio was an independent risk factor for TA in PMN patients (OR=1.29, 95% CI: 1.04, 1.61, P=0.0213). A non-linear correlation was observed between the TG/HDL-C ratio and TA, with an inflection point at 4.25. The odds ratios (OR) on the left and right sides of this inflection point were 1.56 (95% CI: 1.17, 2.07) and 0.25 (95% CI: 0.04, 1.54), respectively. Sensitivity analysis confirmed these results. Subgroup analysis showed a consistent association between the TG/HDL-C ratio and TA, implying that factors such as gender, BMI, age, UPRO, ALB, hypertension and severe nephrotic syndrome had negligible effects on the link between the TG/HDL-C ratio and TA.

Conclusion

Our study demonstrates a non-linear positive correlation between the TG/HDL-C ratio and the risk of TA in PMN patients, independent of other factors. Specifically, the association is more pronounced when the ratio falls below 4.25. Based on our findings, it would be advisable to decrease the TG/HDL-C ratio below the inflection point in PMN patients as part of treatment strategies.

Exploration of Diagnostic Markers Associated with Inflammation in Chronic Kidney Disease Based on WGCNA and Machine Learning

Chronic kidney disease (CKD) is a common disorder related to inflammatory pathways; its effective management remains limited. This study aimed to use bioinformatics analysis to find diagnostic markers that might be therapeutic targets for CKD. CKD microarray datasets were screened from the GEO database and the differentially expressed genes (DEGs) in CKD dataset GSE98603 were analyzed. Gene set variation analysis (GSVA) was used to explore the activity scores of the inflammatory pathways and samples. Algorithms such as weighted gene co-expression network analysis (WGCNA) and Lasso were used to screen CKD diagnostic markers related to inflammation. Then functional enrichment analysis of inflammation-related DEGs was performed. ROC curves were conducted to examine the diagnostic value of inflammation-related hub-genes. Lastly, quantitative real-time PCR further verified the prediction of bioinformatics. A total of 71 inflammation-related DEGs were obtained, of which 5 were hub genes. Enrichment analysis showed that these genes were significantly enriched in inflammation-related pathways (NF-κB, JAK-STAT, and MAPK signaling pathways). ROC curves showed that the 5 CKD diagnostic markers (TIGD7, ACTA2, ACTG2, MAP4K4, and HOXA11) also exhibited good diagnostic value. In addition, TIGD7, ACTA2, ACTG2, and HOXA11 expression was downregulated while MAP4K4 expression was upregulated in LPS-induced HK-2 cells. The present study identified TIGD7, ACTA2, ACTG2, MAP4K4, and HOXA11 as reliable CKD diagnostic markers, thereby providing a basis for further understanding of CKD in clinical treatments.

Relationship between Compound α-Ketoacid and Microinflammation in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) refers to the presence of structural or functional abnormalities in the kidneys that affect health, lasting for more than 3 months. CKD is not only the direct cause of global incidence rate and mortality, but also an important risk factor for cardiovascular disease. Persistent microinflammatory state has been recognized as an important component of CKD, which can lead to renal fibrosis and loss of renal function, and plays a crucial role in the pathophysiology and progression of the disease. Simultaneously, compound α-Ketoacid can bind nitrogen-containing metabolites in the blood and accelerate their excretion from the body, thereby reducing the level of metabolic waste, alleviating gastrointestinal reactions in patients, and reducing the inflammatory response and oxidative stress state of the body. Compound α-Ketoacid contains amino acids required by CKD patients. In this review, we explore the relationship between compound α-Ketoacid and microinflammation in patients with CKD. The review indicated that compound α-Ketoacid can improve the microinflammatory state in CKD patients by improving the nutritional status of CKD patients, improving patient's acid-base balance disorder, regulating oxidative stress, improving gut microbiota, and regulating abnormal lipid metabolism.

Chronic Kidney Disease Associated with Ischemic Heart Disease: To What Extent Do Biomarkers Help?

Chronic kidney disease represents a complex and multifaceted pathology characterized by the presence of structural or functional renal anomalies associated with a persistent reduction in renal function. As the disease progresses, complications arise due to the chronic inflammatory syndrome, hydro-electrolytic disorders, and toxicity secondary to the uremic environment. Cardiovascular complications are the leading cause of death for these patients. Ischemic cardiac pathology can be both a consequence and complication of chronic kidney disease, highlighting the need to identify specific cardiorenal dysfunction biomarkers targeting pathophysiological mechanisms common to both conditions. This identification is crucial for establishing accurate diagnoses, prognoses, and risk stratifications for patients. This work is intended to elucidate the intricate relationship between chronic kidney disease and ischemic heart disease and to investigate the roles of cardiorenal biomarkers, including cardiac troponin, natriuretic peptides, galectin-3, copeptin, fibroblast growth factor 23 and its co-receptor Klotho, soluble suppression of tumorigenicity 2, and plasma growth differentiation factor 15.

Catalytic antioxidant nanoparticles mitigate secondary injury progression and promote functional recovery in spinal cord injury model

Traumatic spinal cord injury exacerbates disability with time due to secondary injury cascade triggered largely by overproduction of reactive oxygen species (ROS) at the lesion site, causing oxidative stress. This study explored nanoparticles containing antioxidant enzymes (antioxidant NPs) to neutralize excess ROS at the lesion site and its impact. When tested in a rat contusion model of spinal cord injury, a single dose of antioxidant NPs, administered intravenously three hours after injury, effectively restored the redox balance at the lesion site, interrupting the secondary injury progression. This led to reduced spinal cord tissue inflammation, apoptosis, cavitation, and inhibition of syringomyelia. Moreover, the treatment reduced scar tissue forming collagen at the lesion site, protected axons from demyelination, and stimulated lesion healing, with further analysis indicating the formation of immature neurons. The ultimate effect of the treatment was improved motor and sensory functions and rapid post-injury weight loss recovery. Histological analysis revealed activated microglia in the spinal cord displaying rod-shaped anti-inflammatory and regenerative phenotype in treated animals, contrasting with amoeboid inflammatory and degenerative phenotype in untreated control. Overall data suggest that restoring redox balance at the lesion site shifts the dynamics in the injured spinal cord microenvironment from degenerative to regenerative, potentially by promoting endogenous repair mechanisms. Antioxidant NPs show promise to be developed as an early therapeutic intervention in stabilizing injured spinal cord for enhanced recovery.

Dioscorea nipponica Makino: A comprehensive review of its chemical composition and pharmacology on chronic kidney disease

Chronic kidney disease (CKD) is a widespread ailment that significantly impacts global health. It is characterized by high prevalence, poor prognosis, and substantial healthcare costs, making it a major public health concern. The current clinical treatments for CKD are not entirely satisfactory, leading to a high demand for alternative therapeutic options. Chinese herbal medicine, with its long history, diverse varieties, and proven efficacy, offers a promising avenue for exploration. One such Chinese herbal medicine, Dioscorea nipponica Makino (DNM), is frequently used to treat kidney diseases. In this review, we have compiled studies examining the mechanisms of action of DNM in the context of CKD, focusing on five primary areas: improvement of oxidative stress, inhibition of renal fibrosis, regulation of metabolism, reduction of inflammatory response, and regulation of autophagy.

Lactobacillus coryniformis subsp. torquens T3 alleviates non-alcoholic fatty liver disease via reconstruction of the gut microbiota and redox system

BACKGROUND

A high-fat diet (HFD) that induces obesity has become the most common type of diet worldwide, leading to serious global health issues. Obesity is associated with an increased risk of non-alcoholic fatty liver disease (NAFLD). Probiotic supplements have been shown to help alleviate obesity. The present study aimed to investigate the mechanism by which Lactobacillus coryniformis supsp. torquens T3 (T3L) alleviated NAFLD induced by HFD via reconstruction of the gut microbiota and redox system.

RESULTS

The results showed that, compared with the HFD group, T3L inhibited obesity and relieved fat accumulation in the liver of mice with NAFLD. In addition, T3L inhibited liver inflammation and oxidative stress injury in NAFLD mice by regulating the lipopolysaccharide (LPS) inflammatory pathway in the liver. Furthermore, T3L changed the composition of the intestinal flora, reduced the abundance of harmful bacteria in the intestinal tract, enhanced the mechanical function of the intestinal barrier, and increased the short-chain fatty acid contents, thus inhibiting the secondary metabolite LPS, which directly causes liver damage through the portal vein.

CONCLUSION

In summary, T3L ameliorated NAFLD induced by obesity through the liver-gut axis pathway, thus reducing oxidative stress and liver injury. © 2023 Society of Chemical Industry.

MicroRNA regulators of vascular pathophysiology in chronic kidney disease

Coronary artery disease (CAD) is a severe comorbidity in chronic kidney disease (CKD) due to heavy calcification in the medial layer and inflamed plaques. Chronic inflammation, endothelial dysfunction and vascular calcification are major contributors that lead to artherosclerosis in CKD. The lack of specific symptoms and signs of CAD and decreased accuracy of noninvasive diagnostic tools result in delayed diagnosis leading to increased mortality. MicroRNAs (miRNAs) are post-transcriptional regulators present in various biofluids throughout the body. In the circulation, miRNAs have been reported to be encapsulated in extracellular vesicles and serve as stable messengers for crosstalk among cells. miRNAs are involved in pathophysiologic mechanisms including CAD and can potentially be extended from basic research to clinical translational practice.

A Study of Oxidative Stress, Inflammation, and Endothelial Dysfunction in Diabetic and Nondiabetic Chronic Kidney Disease Pre-Dialysis Patients

Background

Oxidative stress, inflammation, and endothelial dysfunction represent a key triad for the development and progression of atherosclerosis. Due to chronic low-grade inflammation in chronic kidney disease (CKD), concentrations of various inflammatory, endothelial, and oxidative stress markers are elevated, increasing the risk of atherosclerosis. The present study was undertaken to compare oxidative stress, inflammation, and endothelial dysfunction in diabetic and nondiabetic CKD pre-dialysis patients.

Materials and Methods

This was an observational study on 120 CKD pre-dialysis patients: 60 with diabetes and 60 without diabetes. Markers of oxidative stress were measured in blood - malondialdehyde (MDA), ferric reducing ability of plasma (FRAP), paroxonase-1 (PON-1), ischemia-modified albumin (IMA); inflammation - interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP); and endothelial dysfunction - nitric oxide (NO), carotid wall intima-media thickness (CIMT). Comparisons between the two groups for continuous variables were made with the Student's unpaired t-test or Mann-Whitney test and for categorical values with χ2-test, as appropriate.

Results

MDA, IMA, IL-6, hsCRP, NO, and CIMT were significantly higher, while FRAP and PON-1 were significantly lower in the diabetic group when compared to nondiabetic group (P < 0.001). The number of atherosclerotic plaques was also significantly higher in the diabetic group compared to nondiabetic group.

Conclusion

Our study showed increased oxidative stress, inflammation, endothelial dysfunction, and atherosclerosis in diabetic CKD pre-dialysis patients when compared to nondiabetic CKD pre-dialysis patients and in late stages when compared to early stages of CKD in both groups, indicating increased cardiovascular risk in late stages and diabetic CKD pre-dialysis patients.

Further insights into the impact of rebamipide on gentamicin-induced nephrotoxicity in rats: modulation of SIRT1 and β-catenin/cyclin D1 pathways

Gentamicin (GM) is an effective antibiotic administered to treat acute Gram-negative infections. Nevertheless, its clinical application is limited due to nephrotoxicity. Therefore, our research aimed to investigate the potential renoprotective impact of rebamipide (RBM), a gastroprotective drug, on GM-induced kidney damage in rats, as well as putative nephroprotective pathways. RBM was orally administered (100 mg/kg/d for 14 d) commencing 7 d before the administration of GM (100 mg/kg/d, intraperitoneally). Nephrotoxicity was elucidated, and the silent information regulator 1 (SIRT1) and β-catenin/cyclin D1 pathways were assessed. GM induced a significant elevation in the serum levels of creatinine, blood urea nitrogen (BUN), and kidney injury molecule-1 (KIM-1), as well as the relative kidney index. In addition, GM increased lipid peroxidation and lowered total antioxidant capacity (TAC) level and superoxide dismutase (SOD) activity. GM administration also demonstrated a significant amplification in tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), nuclear factor-κappa B p65 (NF-κB p65), p38 mitogen-activated protein kinase (p38 MAPK), and caspase-3 kidney levels, as well as B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax)/Bcl-2 ratio. Notably, RBM treatment amended all these changes induced by GM. Furthermore, the potential role of SIRT1 and β-catenin-dependent signaling pathways in GM-induced renal injury was assessed. Our findings showed that GM-treated rats demonstrated a substantial decrease in SIRT1, nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) along with an increase in β-catenin, forkhead box O-3a (FOXO-3a), and cyclin D1 protein expressions. RMB treatment markedly attenuated the deterioration caused by GM on these pathways. Additionally, RBM alleviated the GM-induced deleterious kidney tissue histopathology. In conclusion, our findings have verified that RBM can halt GM-induced renal injury by partly modulating SIRT1 and β-catenin pathways.

The effect of aerobic exercise on oxidative stress in patients with chronic kidney disease: a systematic review and meta-analysis with trial sequential analysis

PURPOSE

The purpose of this study was to investigate how aerobic exercise affects oxidative stress (OS) in patients with chronic kidney disease (CKD).

METHODS

Retrieval dates range from the date the database was established to 19 July 2023, without languages being restricted. A meta-analysis and sensitivity analysis were conducted using RevMan 5.3 and Stata 16.0.

RESULTS

The meta-analysis showed that, compared to usual activity or no exercise, aerobic exercise significantly reduced the oxidative markers malondialdehyde (MDA) (mean differences (MD) - 0.96 (95% CI -1.33, - 0.59); p < 0.00001), advanced oxidation protein product (AOPP) (MD - 3.49 (95% CI - 5.05, - 1.93); p < 0.00001), F2-isoprostanes (F2-iso) (MD - 11.02 (95% CI - 17.79, - 4.25); p = 0.001). Aerobic exercise also increased the antioxidant marker superoxide dismutase (SOD) in CKD patients (standardized mean differences (SMD) 1.30 (95% CI 0.56, 2.04); p = 0.0005). Subgroup analysis showed a significant increase in glutathione peroxidase (GPX) in patients aged ≥60 years (SMD 2.11 (95% CI 1.69, 2.54); p < 0.00001). The change in total antioxidant capacity (TAC) after aerobic exercise was insignificant in patients with CKD. The trial sequential analysis supported aerobic exercise's effectiveness in improving MDA, SOD, AOPP, and F2-iso in patients with CKD.

CONCLUSION

The results of this review suggest that aerobic exercise improves OS indicators (MDA, SOD, AOPP, and F2-iso) in CKD patients compared to conventional treatment or no exercise and that the effects on GPX and TAC indicators need further confirmation. For better validation of benefits and exploration of the best aerobic exercise regimen to improve OS status with CKD, further studies with high methodological quality and large sample sizes are needed.

Inflammatory Mechanisms in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is now the most common form of heart failure and a significant public health concern for which limited effective therapies exist. Inflammation triggered by comorbidity burden is a critical element of HFpEF pathophysiology. Here, we discuss evidence for comorbidity-driven systemic and myocardial inflammation and the mechanistic role of inflammation in pathological myocardial remodeling in HFpEF.

Causal effects of systemic inflammatory regulators on chronic kidney diseases and renal function: a bidirectional Mendelian randomization study

Background

While targeted systemic inflammatory modulators show promise in preventing chronic kidney disease (CKD) progression, the causal link between specific inflammatory factors and CKD remains uncertain.

Methods

Using a genome-wide association study of 41 serum cytokines from 8,293 Finnish individuals, we conducted a bidirectional two-sample Mendelian randomization (MR) analysis. In addition, we genetically predicted causal associations between inflammatory factors and 5 phenotypes, including CKD, estimated glomerular filtration rate (eGFR), dialysis, rapid progression of CKD, and rapid decline in eGFR. Inverse variance weighting (IVW) served as the primary MR method, while MR-Egger, weighted median, and MR-pleiotropy residual sum and outlier (MR-PRESSO) were utilized for sensitivity analysis. Cochrane's Q test for heterogeneity. Leave-one-out method ensured stability of MR results, and Bonferroni correction assessed causal relationship strength.

Results

Seventeen cytokines were associated with diverse renal outcomes. Among them, after Bonferroni correction test, higher tumor necrosis factor alpha levels were associated with a rapid decrease in eGFR (OR = 1.064, 95% CI 1.028 - 1.103, P = 0.001), higher interleukin-4 levels were associated with an increase in eGFR (β = 0.003, 95% CI 0.001 - 0.005, P = 0.002), and higher growth regulated oncogene alpha (GROα) levels were associated with an increased risk of CKD (OR=1.035, 95% CI 1.012 - 1.058, P = 0.003). In contrast, genetic susceptibility to CKD was associated with an increase in GROa, and a decrease in eGFR may lead to an increase in stem cell factor. We did not find the presence of horizontal pleiotropy during the analysis.

Conclusion

We discovered causally related inflammatory factors that contribute to the initiation and progression of CKD at the genetic prediction level.

The efficacy and safety of Niaoduqing granules in the treatment of diabetic kidney disease: a systematic review and meta-analysis

Background: Diabetic nephropathy (DN) is the main cause of chronic kidney disease (CKD) and end-stage renal failure (ESRF), and the control of disease progression and adverse events during treatment needs to be improved. Objective: This study aimed to systematically evaluate the clinical efficacy and safety of Niaoduqing granules (NDQG) in the treatment of diabetic kidney disease (DKD). Method: Randomized controlled trials (RCTs) of NDQG for DKD from Chinese and English databases up to 31 August 2022 were included. The quality of the literature was assessed using the risk of bias tool of the Cochrane Handbook. At a 95% confidence interval (CI), relative risk (RR) and Cohen's d were used for the categorical and continuous variables, respectively, and Stata 16.0 software was used for statistical analysis. A funnel plot and Egger's tests were used to assess publication bias. Result: A total of 4,006 patients were included in 52 RCTs, including 1,987 cases in the control group and 2,019 cases in the treatment group. Compared with conventional treatment (CT), combined NDQG therapy is more effective in improving clinical efficiency [RR = 1.23, 95% confidence interval (1.17, 1.29), p < 0.001, I ² = 53.17%], kidney function (urinary albumin excretion rate [SMD = -0.90, 95% CI (-1.14, -0.66), p < 0.001, I ² = 78.19%], 24hUTP levels [SMD = -0.81, 95% CI (-1.08, -0.55), p < 0.001, I ² = 87.08%], blood urea nitrogen [SMD = -0.54, 95% CI (-0.69, -0.39), p < 0.01, I ² = 77.01%], SCr [SMD = -0.68, 95% CI (-0.90, -0.45), p < 0.001, I ² = 89.97%], CCr [SMD = 0.76, 95% CI (0.10,1.42), p = 0.02, I ² = 95.97%], and Cys-C [SMD = -1.32, 95% CI (-2.25, -0.40), p = 0.01, I ² = 93.44%]), the level of glucose metabolism (fasting blood glucose [SMD = -0.18, 95% CI (-0.38, 0.03), p = 0.10, I ² = 71.18%] and HbA1c [SMD = -0.42, 95% CI (-0.86, -0.02), p = 0.06, I ² = 81.64%]), the level of lipid metabolism (total cholesterol [SMD = -0.70, 95% CI (-1.01, -0.39), p < 0.001, I ² = 86.74%] and triglyceride [SMD = -0.61, 95% CI (-0.87,-0.36), p < 0.001, I ² = 80.64%]), inflammatory factors (Hs-CRP [SMD = -1.00, 95% CI (-1.54, -0.46), p < 0.001, I ² = 86.81%], IL-18 [SMD = -1.25, 95% CI (-1.58, -0.92), p < 0.001, I ² = 0], and TNF-α [SMD = -1.28, 95% CI (-1.64, -0.91), p < 0.001, I ² = 75.73%]), and indicators of oxidative stress (malondialdehyde [SMD = -0.88, 95% CI (-1.22, -0.54), p < 0.001, I ² = 66.01%] and advanced oxidation protein products [SMD = -0.92, 95% CI (-1.85, 0.00), p < 0.001, I ² = 90.68%]). In terms of improving uric acid [SMD = -1.59, 95% CI (-3.45, 0.27), p = 0.09, I ² = 94.67%], 2hPG [SMD = -0.04, 95% CI (-0.61, 0.53), p = 0.89, I ² = 84.33%], HDL-C [SMD = 0.71, 95% CI (0.02, 1.40), p = 0.04, I ² = 87.43%], Hb [SMD = 0.11, 95% CI (-0.10, 0.32), p = 0.32, I ² = 0.00]), and superoxide dismutase [SMD = 1.32, 95% CI (0.44, 2.20), p < 0.001, I ² = 93.48%], the effect is not obvious. Adjuvant treatment with NDQG did not increase the incidence of adverse reactions in the control group [SMD = 0.98, 95% CI (0.71, 1.34), p = 0.89, I ² = 1.59%]. Obvious publication bias was detected by funnel plot and Egger's test. Conclusion: Our meta-analysis showed that adjuvant treatment with NDQG has more advantages than conventional treatment alone in the DKD treatment, which could improve clinical efficiency, kidney function, the level of glucose metabolism, the level of lipid metabolism, inflammatory factors, and oxidative stress indicators. At the same time, it also showed that NDQG are relatively safe. However, more high-quality studies are needed to provide more reliable evidence for clinical use. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022373726, identifier CRD42022373726.

The role of exercise in improving hyperlipidemia-renal injuries induced by a high-fat diet: a literature review

A diet that is high in sugar and fat is a precursor to various chronic diseases, especially hyperlipidemia. Patients with hyperlipidemia have increased levels of plasma free fatty acids and an ectopic accumulation of lipids. The kidney is one of the main organs affected by this disease and, recently, there have been more studies conducted on renal injury caused by hyperlipidemia. The main pathological mechanism is closely related to renal lipotoxicity. However, in different kidney cells, the reaction mechanism varies due to the different affinities of the lipid receptors. At present, it is believed that in addition to lipotoxicity, hyperlipidemia induced-renal injury is also closely related to oxidative stress, endoplasmic reticulum stress, and inflammatory reactions, which are the result of multiple factors. Exercise plays an important role in the prevention of various chronic diseases and recently emerging researches indicated its positive effects to renal injury caused by hyperlipidemia. However, there are few studies summarizing the effects of exercise on this disease and the specific mechanisms need to be further explored. This article summarizes the mechanisms of hyperlipidemia induced-renal injury at the cellular level and discusses the ways in which exercise may regulate it. The results provide theoretical support and novel approaches for identifying the intervention target to treat hyperlipidemia induced-renal injury.

Redox Signaling in Chronic Kidney Disease-Associated Cachexia

Redox signaling alterations contribute to chronic kidney disease (CKD)-associated cachexia. This review aims to summarize studies about redox pathophysiology in CKD-associated cachexia and muscle wasting and to discuss potential therapeutic approaches based on antioxidant and anti-inflammatory molecules to restore redox homeostasis. Enzymatic and non-enzymatic systems of antioxidant molecules have been studied in experimental models of kidney diseases and patients with CKD. Oxidative stress is increased by several factors present in CKD, including uremic toxins, inflammation, and metabolic and hormone alterations, leading to muscle wasting. Rehabilitative nutritional and physical exercises have shown beneficial effects for CKD-associated cachexia. Anti-inflammatory molecules have also been tested in experimental models of CKD. The importance of oxidative stress has been shown by experimental studies in which antioxidant therapies ameliorated CKD and its associated complications in the 5/6 nephrectomy model. Treatment of CKD-associated cachexia is a challenge and further studies are necessary to investigate potential therapies involving antioxidant therapy.

Nrf2 Protein Serum Concentration in Human CKD Shows a Biphasic Behavior

Oxidative stress contributes to the progression of chronic kidney disease (CKD) and CKD-related mortality. The nuclear factor erythroid 2-related factor 2 (Nrf2) is essential in the regulation of cellular redox status, and Nrf2-activating therapies are under evaluation in several chronic diseases, including CKD. It is therefore inevitable to understand how Nrf2 behaves in advancing CKD. We analyzed Nrf2 protein concentrations in patients with varying extents of CKD but without renal replacement therapy, and in healthy subjects. Compared to healthy controls, Nrf2 protein was upregulated in mild to moderate kidney function impairment (G1-3). Within the CKD population, we found a significant positive correlation between Nrf2 protein concentration and kidney function (estimated glomerular filtration rate). In severe kidney function impairment (G4,5), Nrf2 protein was reduced compared to mild to moderate kidney function impairment. We conclude that Nrf2 protein concentration in severe kidney function impairment is reduced relative to the mild to moderate kidney function impairment where increased Nrf2 protein concentrations prevail. With respect to the implementation of Nrf2 targeted therapies, it will be necessary to explore in which population of patients with CKD such therapies are able to effectively add to the endogenous Nrf2 activity.

Antiretrovirals Promote Metabolic Syndrome through Mitochondrial Stress and Dysfunction: An In Vitro Study

The prevalence of metabolic syndrome MetS in HIV-infected patients on chronic antiretroviral (ARV) therapy continues to rise rapidly, with an estimated 21% experiencing insulin resistance. The progression of insulin resistance is strongly related to mitochondrial stress and dysfunction. This study aimed to draw links between the singular and combinational use of Tenofovir disoproxil fumarate (TDF), Lamivudine (3TC), and Dolutegravir (DTG) on mitochondrial stress and dysfunction as an underlying mechanism for insulin resistance following a 120 h treatment period using an in vitro system of human liver cells (HepG2). The relative protein expressions of pNrf2, SOD2, CAT, PINK1, p62, SIRT3, and UCP2, were determined using Western blot. Transcript levels of PINK1 and p62 were assessed using quantitative PCR (qPCR). ATP concentrations were quantified using luminometry, and oxidative damage (malondialdehyde (MDA) concentration) was measured using spectrophotometry. The findings suggest that despite the activation of antioxidant responses (pNrf2, SOD2, CAT) and mitochondrial maintenance systems (PINK1 and p62) in selected singular and combinational treatments with ARVs, oxidative damage and reduced ATP production persisted. This was attributed to a significant suppression in mitochondrial stress responses SIRT3 and UCP2 for all treatments. Notable results were observed for combinational treatments with significant increases in pNrf2 (p = 0.0090), SOD2 (p = 0.0005), CAT (p = 0.0002), PINK1 (p = 0.0064), and p62 (p = 0.0228); followed by significant decreases in SIRT3 (p = 0.0003) and UCP2 (p = 0.0119) protein expression. Overall there were elevated levels of MDA (p = 0.0066) and decreased ATP production (p = 0.0017). In conclusion, ARVs induce mitochondrial stress and dysfunction, which may be closely associated with the progression of insulin resistance.

Exercise and chronic kidney disease: potential mechanisms underlying the physiological benefits

Increasing evidence indicates that exercise has beneficial effects on chronic inflammation, cardiorespiratory function, muscle and bone strength and metabolic markers in adults with chronic kidney disease (CKD), kidney failure or kidney transplants. However, the mechanisms that underlie these benefits have received little attention, and the available clinical evidence is mainly from small, short-duration (<12 weeks) exercise intervention studies. The available data, mainly from patients with CKD or on dialysis, suggest that exercise-mediated shifts towards a less inflammatory immune cell profile, enhanced activity of the NRF2 pathway and reduced monocyte infiltration into adipose tissue may underlie improvements in inflammatory biomarkers. Exercise-mediated increases in nitric oxide release and bioavailability, reduced angiotensin II accumulation in the heart, left ventricular remodelling and reductions in myocardial fibrosis may contribute to improvements in left ventricular hypertrophy. Exercise stimulates an anabolic response in skeletal muscle in CKD, but increases in mitochondrial mass and satellite cell activation seem to be impaired in this population. Exercise-mediated activation of the canonical wnt pathway may lead to bone formation and improvements in the levels of the bone-derived hormones klotho and fibroblast growth factor 23 (FGF23). Longer duration studies with larger sample sizes are needed to confirm these mechanisms in CKD, kidney failure and kidney transplant populations and provide evidence for targeted exercise interventions.

Insights into the Molecular Mechanisms of NRF2 in Kidney Injury and Diseases

Redox is a constant phenomenon in organisms. From the signaling pathway transduction to the oxidative stress during the inflammation and disease process, all are related to reduction-oxidation (redox). Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor targeting many antioxidant genes. In non-stressed conditions, NRF2 maintains the hemostasis of redox with housekeeping work. It expresses constitutively with basal activity, maintained by Kelch-like-ECH-associated protein 1 (KEAP1)-associated ubiquitination and degradation. When encountering stress, it can be up-regulated by several mechanisms to exert its anti-oxidative ability in diseases or inflammatory processes to protect tissues and organs from further damage. From acute kidney injury to chronic kidney diseases, such as diabetic nephropathy or glomerular disease, many results of studies have suggested that, as a master of regulating redox, NRF2 is a therapeutic option. It was not until the early termination of the clinical phase 3 trial of diabetic nephropathy due to heart failure as an unexpected side effect that we renewed our understanding of NRF2. NRF2 is not just a simple antioxidant capacity but has pleiotropic activities, harmful or helpful, depending on the conditions and backgrounds.

Therapeutic Potential of Two Derivative Prescriptions of Rokumijiogan, Hachimijiogan and Bakumijiogan against Renal Damage in Nephrectomized Rats

Background: Hachimijiogan (HJG) and Bakumijiogan (BJG), two derivative prescriptions of Rokumijiogan (RJG), were selected to investigate their renoprotective potential in the 5/6 nephrectomized (5/6Nx) rat model. Methods: Rats were treated with HJG and BJG orally at 150 mg/kg body weight/day once daily for 10 weeks after resection of 5/6 of the renal volume, and their renoprotective effects were compared with 5/6Nx vehicle-treated and sham-operated control rats. Results: Improvements in renal lesions, glomerulosclerosis, tubulointerstitial injury, and arteriosclerotic lesions estimated by histologic scoring indices in the HJG-treated group were compared with those in the BJG-treated group. HJG- and BJG-treated groups ameliorated the renal function parameters. Elevated levels of renal oxidative stress-related biomarkers were reduced, while decreased antioxidant defence systems (superoxide dismutase and the glutathione/oxidized glutathione ratio) were increased in the HJG-treated group rather than the BJG-treated group. In contrast, BJG administration significantly reduced expression of the inflammatory response through oxidative stress. The HJG-treated group showed a decrease in inflammatory mediators through the JNK pathway. To gain a deeper understanding of their therapeutic action, the effects of the main components detected in HJG and BJG were evaluated using the LLC-PK₁ renal tubular epithelial cell line, which is the renal tissue most vulnerable to oxidative stress. Corni Fructus and Moutan Cortex-originated compositions afforded important protection against oxidative stress induced by peroxynitrite. Conclusions: From our described and discussed analyses, it can be concluded that RJG-containing prescriptions, HJG and BJG are an excellent medicine for chronic kidney disease. In the future, appropriately designed clinical studies in people with chronic kidney disease are necessary to evaluate the renoprotective activities of HJG and BJG.

The Protective Role of Nrf2 in Renal Tubular Cells in Oxidised Low-Density Lipoprotein-Induced Fibrosis

Background: CD36 is the receptor of oxidised low-density lipoprotein (OxLDL) in renal tubular epithelial cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) is the key factor in the activation of the Nrf2 signalling pathway and the regulation of oxidative stress. Kelch-like ECH-associated protein 1 (Keap1) is known as an Nrf2 inhibitor. Methods: We used OxLDL and Nrf2 inhibitors at different concentrations and durations to treat renal tubular epithelial cells; the expression of CD36 and cytoplasmic and nucleic Nrf2 and E-cadherin in those cells were observed by Western blot and reverse-transcription polymerase chain reaction. Results: The protein levels of Nrf2 decreased in expression after 24 hours of OxLDL treatment. At the same time, the Nrf2 protein level in the cytoplasm did not change significantly compared with that of the control group, and the Nrf2 protein level expression in the nucleus increased. Both the messenger ribonucleic acid (mRNA) and protein expression of CD36 decreased following the treatment of cells with the Nrf2 inhibitor Keap1. Kelch-like ECH-associated protein 1 was overexpressed, and CD36 mRNA and protein expression were decreased in OxLDL-treated cells. Following the overexpression of Keap1, E-cadherin expression was reduced in NRK-52E cells. Conclusion: Nuclear factor erythroid 2-related factor 2 can be activated by OxLDL; however, it can only alleviate OxLDL-induced oxidative stress by transferring from the cytoplasm to the nucleus. Additionally, Nrf2 may play a protective role by upregulating CD36.

NETosis and kidney disease: what do we know?

Neutrophils are the most abundant leukocytes in the blood. They are rapidly mobilized from the circulation to sites of inflammation and/or infection. In affected tissues, neutrophils exhibit some dramatic antimicrobial functions, including degranulation, reactive oxygen species (ROS) production, phagocytosis, and formation of neutrophil extracellular traps (NETs). Like other cells of the immune system, after fulfilling their biological duties, they enter the path of death. Depending on the conditions, they may undergo different types of cell death (apoptosis, necrosis, necroptosis, autophagy, NETosis, and pyroptosis) that require the participation of multiple signaling pathways. NETosis is a unique neutrophil cell death mechanism that gives rise to different inflammatory and autoimmune pathological conditions. Recent studies have shown that NETosis also plays a role in the formation and/or progression of kidney diseases. This review discusses the underlying mechanism of NETosis and its relationship with some major kidney diseases in light of the current knowledge.

Pathogenesis of Chronic Kidney Disease Is Closely Bound up with Alzheimer's Disease, Especially via the Renin-Angiotensin System

Chronic kidney disease (CKD) is a clinical syndrome secondary to the definitive change in function and structure of the kidney, which is characterized by its irreversibility and slow and progressive evolution. Alzheimer's disease (AD) is characterized by the extracellular accumulation of misfolded β-amyloid (Aβ) proteins into senile plaques and the formation of neurofibrillary tangles (NFTs) containing hyperphosphorylated tau. In the aging population, CKD and AD are growing problems. CKD patients are prone to cognitive decline and AD. However, the connection between CKD and AD is still unclear. In this review, we take the lead in showing that the development of the pathophysiology of CKD may also cause or exacerbate AD, especially the renin-angiotensin system (RAS). In vivo studies had already shown that the increased expression of angiotensin-converting enzyme (ACE) produces a positive effect in aggravating AD, but ACE inhibitors (ACEIs) have protective effects against AD. Among the possible association of risk factors in CKD and AD, we mainly discuss the RAS in the systemic circulation and the brain.

Chronic Kidney Disease as a Comorbidity in Heart Failure

Heart failure (HF) is one of the greatest problems in healthcare and it often coexists with declining renal function. The pathophysiology between the heart and the kidneys is bidirectional. Common mechanisms leading to the dysfunction of these organs result in a vicious cycle of cardiorenal deterioration. It is also associated with difficulties in the treatment of aggravating HF and chronic kidney disease (CKD) and, as a consequence, recurrent hospitalizations and death. As the worsening of renal function has an undeniably negative impact on the outcomes in patients with HF, searching for new treatment strategies and identification of biomarkers is necessary. This review is focused on the pathomechanisms in chronic kidney disease in patients with HF and therapeutic strategies for co-existing CKD and HF.