Mitochondrial dysfunction in diabetic kidney disease

Supplemented Gegen Qinlian Decoction Formula attenuates podocyte mitochondrial fission and renal fibrosis in diabetic kidney disease by inhibiting TNF-α-mediated necroptosis, compared with empagliflozin

ETHNOPHARMACOLOGICAL RELEVANCE

Recently, podocyte mitochondrial dysfunction and necroptosis have been shown to play critical roles in renal fibrosis (RF) in diabetic kidney disease (DKD); however, these conditions lack effective treatment. In China, the supplemented Gegen Qinlian Decoction Formula (SGQDF), which originates from the classical prescription Gegen Qinlian Decoction, has been widely used to treat patients with DKD. However, it remains unclear whether SGQDF alleviates podocyte injury-associated RF in patients with DKD.

AIM OF STUDY

This study aimed to clarify the therapeutic effects of SGQDF compared with those of empagliflozin (EMPA) on podocyte mitochondrial fission and RF in DKD and its necroptosis-related mechanisms.

MATERIALS AND METHODS

Modified DKD rat models were developed through a combination of uninephrectomy, streptozotocin administration through intraperitoneal injection, and exposure to a high-fat diet. Following RF formation, the DKD rat models received either a high dose of SGQDF (H-SGQDF), a low dose of SGQDF (L-SGQDF), EMPA, or vehicle for 4 weeks. In our in vitro study, we subjected cultured murine podocytes to a high-glucose environment and various treatments including Mdivi-1, adalimumab, and necrostatin-1, with or without H-SGQDF or EMPA. SGQDF target prediction and molecular docking verification were performed. For the in vivo study, we focused on examining changes in the parameters associated with renal injury, RF, and oxidative stress (OS)-induced injuries in podocytes. Both in vivo and in vitro studies included an analysis of changes in podocyte mitochondrial fission, TNF-α-induced podocyte necroptosis, and the RIPK1/RIPK3/MLKL signaling pathway activation.

RESULTS

SGQDF improved renal injury markers, including body weight, blood glucose, serum creatinine, blood urea nitrogen, and urinary albumin, in a dose-dependent manner. The beneficial effects of H-SGQDF in vivo were greater than those of L-SGQDF alone in vivo. Interestingly, similar to EMPA, H-SGQDF ameliorated RF and reduced OS-induced podocyte injury in diabetic kidneys. Furthermore, TNF-α signaling was shown to be important in the network construction of "the SGQDF-component-target." Based on this, we also showed that the beneficial effects in vivo and in vitro of H-SGQDF were closely related to the improvement in mitochondrial dysfunction and the inhibition of TNF-α-induced necroptosis in podocytes.

CONCLUSION

In the present study, we showed that H-SGQDF, similar to EMPA, attenuates podocyte mitochondrial fission and RF, and that the underlying therapeutic mechanisms are closely related to inhibiting the activation of the RIPK1/RIPK3/MLKL signaling axis in diabetic kidneys. Our findings provide new pharmacological evidence for the application of H-SGQDF in the RF treatment of DKD.

Iron chelation mitigates mitochondrial dysfunction and oxidative stress by enhancing nrf2-mediated antioxidant responses in the renal cortex of a murine model of type 2 diabetes

Renal iron overload is a common complication of diabetes that leads to oxidative stress and mitochondrial dysfunction in the kidneys. This study investigated the effects of iron chelation using deferiprone on mitochondrial dysfunction and oxidative stress in the renal cortex of a murine model of type 2 diabetes. Diabetic rats were treated with deferiprone (50 mg/kg BW) for 16 weeks. Our results show that iron chelation with deferiprone significantly increased the nuclear accumulation of Nrf2, a transcription factor that regulates the expression of antioxidant enzymes. This led to enhanced antioxidant capacity, reduced production of reactive oxygen species, and improved mitochondrial bioenergetic function in diabetic rats. However, chronic iron chelation led to altered mitochondrial respiration and increased oxidative stress in non-diabetic rats. In conclusion, our findings suggest that iron chelation with deferiprone protects mitochondrial bioenergetics and mitigates oxidative stress in the renal cortex, involving the NRF2 pathway in type 2 diabetes.

Sodium-Glucose Cotransporter Inhibitors: Cellular Mechanisms Involved in the Lipid Metabolism and the Treatment of Chronic Kidney Disease Associated with Metabolic Syndrome

Metabolic syndrome (MetS) is a multifactorial condition that significantly increases the risk of cardiovascular disease and chronic kidney disease (CKD). Recent studies have emphasized the role of lipid dysregulation in activating cellular mechanisms that contribute to CKD progression in the context of MetS. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have demonstrated efficacy in improving various components of MetS, including obesity, dyslipidemia, and insulin resistance. While SGLT2i have shown cardioprotective benefits, the underlying cellular mechanisms in MetS and CKD remain poorly studied. Therefore, this review aims to elucidate the cellular mechanisms by which SGLT2i modulate lipid metabolism and their impact on insulin resistance, mitochondrial dysfunction, oxidative stress, and CKD progression. We also explore the potential benefits of combining SGLT2i with other antidiabetic drugs. By examining the beneficial effects, molecular targets, and cytoprotective mechanisms of both natural and synthetic SGLT2i, this review provides a comprehensive understanding of their therapeutic potential in managing MetS-induced CKD. The information presented here highlights the significance of SGLT2i in addressing the complex interplay between metabolic dysregulation, lipid metabolism dysfunction, and renal impairment, offering clinicians and researchers a valuable resource for developing improved treatment strategies and personalized approaches for patients with MetS and CKD.

The renal apical sodium-dependent bile acid transporter expression rescue attenuates renal damage in diabetic nephropathy via farnesoid X receptor activation

AIM

Bile acids (BA) function as signalling molecules regulating glucose-lipid homeostasis and energy expenditure. However, the expression of the apical sodium-dependent bile acid transporter (ASBT) in the kidney, responsible for renal BA reabsorption, is downregulated in patients with diabetic kidney disease (DKD). Using the db/db mouse model of DKD, this study aimed to investigate the effects of rescuing ASBT expression via adeno-associated virus-mediated delivery of ASBT (AAVASBT) on kidney protection.

METHODS

Six-week-old male db/db mice received an intraparenchymal injection of AAVASBT at a dose of 1 × 1011 viral genomes (vg)/animal and were subsequently fed a chow diet for 2 weeks. Male db/m mice served as controls. For drug treatment, daily intraperitoneal (i.p.) injections of the farnesoid X receptor (FXR) antagonist guggulsterone (GS, 10 mg/kg) were administered one day after initiating the experiment.

RESULTS

AAVASBT treatment rescued renal ASBT expression and reduced the urinary BA output in db/db mice. AAVASBT treatment activated kidney mitochondrial biogenesis and ameliorated renal impairment associated with diabetes by activating FXR. In addition, the injection of FXR antagonist GS in DKD mice would reverse these beneficial effects by AAVASBT treatment.

CONCLUSION

Our work indicated that restoring renal ASBT expression slowed the course of DKD via activating FXR. FXR activation stimulates mitochondrial biogenesis while reducing renal oxidative stress and lipid build up, indicating FXR activation's crucial role in preventing DKD. These findings further suggest that the maintenance of renal BA reabsorption could be a viable treatment for DKD.

Advancements in diabetic kidney disease management: integrating innovative therapies and targeted drug development

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease and affects approximately 40% of individuals with diabetes . Cases of DKD continue to rise globally as the prevalence of diabetes mellitus increases, with an estimated 415 million people living with diabetes in 2015 and a projected 642 million by 2040. DKD is associated with significant morbidity and mortality, representing 34% and 36% of all chronic kidney disease deaths in men and women, respectively. Common comorbidities including hypertension and ageing-related nephron loss further complicate disease diagnosis and progression. The progression of DKD involves several mechanisms including glomerular endothelial cell dysfunction, inflammation, and fibrosis. Targeting these mechanisms has formed the basis of several therapeutic agents. Renin-angiotensin-aldosterone system (RAAS) blockers, specifically angiotensin receptor blockers (ARBs), demonstrate significant reductions in macroalbuminuria. Sodium-glucose transporter type 2 (SGLT-2) inhibitors demonstrate kidney protection independent of diabetes control while also decreasing the incidence of cardiovascular events. Emerging agents including glucagon-like peptide 1 (GLP-1) agonists, anti-inflammatory agents like bardoxolone, and mineralocorticoid receptor antagonists show promise in mitigating DKD progression. Many novel therapies including monoclonal antibodies CSL346, lixudebart, and tozorakimab; mesenchymal stem/stromal cell infusion; and cannabinoid-1 receptor inverse agonism via INV-202 are currently in clinical trials and present opportunities for further drug development.

Renal aging and mitochondrial quality control

Mitochondria are dynamic organelles that participate in different cellular process that control metabolism, cell division, and survival, and the kidney is one of the most metabolically active organs that contains abundant mitochondria. Perturbations in mitochondrial homeostasis in the kidney can accelerate kidney aging, and maintaining mitochondrial homeostasis can effectively delay aging in the kidney. Kidney aging is a degenerative process linked to detrimental processes. The significance of aberrant mitochondrial homeostasis in renal aging has received increasing attention. However, the contribution of mitochondrial quality control (MQC) to renal aging has not been reviewed in detail. Here, we generalize the current factors contributing to renal aging, review the alterations in MQC during renal injury and aging, and analyze the relationship between mitochondria and intrinsic renal cells. We also introduce MQC in the context of renal aging, and discuss the study of mitochondria in the intrinsic cells of the kidney, which is the innovation of our paper. In addition, during kidney injury and repair, the specific functions and regulatory mechanisms of MQC systems in resident and circulating cell types remain unclear. Currently, most of the studies we reviewed are based on animal and cellular models, the relationship between renal tissue aging and mitochondria has not been adequately investigated in clinical studies, and there is still a long way to go.

miR-4645-3p attenuates podocyte injury and mitochondrial dysfunction in diabetic kidney disease by targeting Cdk5

Podocyte injury plays a critical role in the progression of diabetic kidney disease (DKD), but the underlying cellular and molecular mechanisms remain poorly understanding. MicroRNAs (miRNAs) can disrupt gene expression by inducing translation inhibition and mRNA degradation, and recent evidence has shown that miRNAs may play a key role in many kidney diseases. In this study, we identified miR-4645-3p by global transcriptome expression profiling as one of the major downregulated miRNAs in high glucose-cultured podocytes. Moreover, whether DKD patients or STZ-induced diabetic mice, expression of miR-4645-3p was also significantly decreased in kidney. In the podocytes cultured by normal glucose, inhibition of miR-4645-3p expression promoted mitochondrial damage and podocyte apoptosis. In the podocytes cultured by high glucose (30 mM glucose), overexpression of miR-4645-3p significantly attenuated mitochondrial dysfunction and podocyte apoptosis induced by high glucose. Furthermore, we found that miR-4645-3p exerted protective roles by targeting Cdk5 inhibition. In vitro, miR-4645-3p obviously antagonized podocyte injury by inhibiting overexpression of Cdk5. In vivo of diabetic mice, podocyte injury, proteinuria, and impaired renal function were all effectively ameliorated by treatment with exogenous miR-4645-3p. Collectively, these findings demonstrate that miR-4645-3p can attenuate podocyte injury and mitochondrial dysfunction in DKD by targeting Cdk5. Sustaining the expression of miR-4645-3p in podocytes may be a novel strategy to treat DKD.

Role of mitochondrial dysfunction in kidney disease: Insights from the cGAS-STING signaling pathway

ABSTRACT

Over the past decade, mitochondrial dysfunction has been investigated as a key contributor to acute and chronic kidney disease. However, the precise molecular mechanisms linking mitochondrial damage to kidney disease remain elusive. The recent insights into the cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthetase (cGAS)-stimulator of interferon gene (STING) signaling pathway have revealed its involvement in many renal diseases. One of these findings is that mitochondrial DNA (mtDNA) induces inflammatory responses via the cGAS-STING pathway. Herein, we provide an overview of the mechanisms underlying mtDNA release following mitochondrial damage, focusing specifically on the association between mtDNA release-activated cGAS-STING signaling and the development of kidney diseases. Furthermore, we summarize the latest findings of cGAS-STING signaling pathway in cell, with a particular emphasis on its downstream signaling related to kidney diseases. This review intends to enhance our understanding of the intricate relationship among the cGAS-STING pathway, kidney diseases, and mitochondrial dysfunction.

Iridoids modulate inflammation in diabetic kidney disease: A review

In recent years, preclinical research on diabetic kidney disease (DKD) has surged to the forefront of scientific and clinical attention. DKD has become a pervasive complication of type 2 diabetes. Given the complexity of its etiology and pathological mechanisms, current interventions, including drugs, dietary modifications, exercise, hypoglycemic treatments and lipid-lowering methods, often fall short in achieving desired therapeutic outcomes. Iridoids, primarily derived from the potent components of traditional herbs, have been the subject of long-standing research. Preclinical data suggest that iridoids possess notable renal protective properties; however, there has been no summary of the research on their efficacy in the management and treatment of DKD. This article consolidates findings from in vivo and in vitro research on iridoids in the context of DKD and highlights their shared anti-inflammatory activities in treating this condition. Additionally, it explores how certain iridoid components modify their chemical structures through the regulation of intestinal flora, potentially bolstering their therapeutic effects. This review provides a focused examination of the mechanisms through which iridoids may prevent or treat DKD, offering valuable insights for future research endeavors. Please cite this article as: Zhou TY, Tian N, Li L, Yu R. Iridoids modulate inflammation in diabetic kidney disease: A review. J Integr Med. 2024; 22(3): 210-222.

Diabetes and diabetic associative diseases: An overview of epigenetic regulations of TUG1

The epigenetic regulation of lncRNA TUG1 has garnered significant attention in the context of diabetes and its associated disorders. TUG1's multifaceted roles in gene expression modulation, and cellular differentiation, and it plays a major role in the growth of diabetes and the issues that are related to it due to pathological processes. In diabetes, aberrant epigenetic modifications can lead to dysregulation of TUG1 expression, contributing to disrupted insulin signaling, impaired glucose metabolism, and beta-cell dysfunction. Moreover, it has been reported that TUG1 contributes to the development of problems linked to diabetes, such as nephropathy, retinopathy, and cardiovascular complications, through epigenetically mediated mechanisms. Understanding the epigenetic regulations of TUG1 offers novel insights into the primary molecular mechanisms of diabetes and provides a possible path for healing interventions. Targeting epigenetic modifications associated with TUG1 holds promise for restoring proper gene expression patterns, ameliorating insulin sensitivity, and mitigating the inception and development of diabetic associative diseases. This review highlights the intricate epigenetic landscape that governs TUG1 expression in diabetes, encompassing DNA methylation and alterations in histone structure, as well as microRNA interactions.

Association Between Triglyceride-Glucose Index and Hearing Threshold Shifts of Adults in the United States: National Health and Nutrition Examination Survey, 2015-2016

Objective

Sensorineural Hearing Loss (SNHL) is a representative human sensory impairment, few studies have paid attention to the correlation between the Triglyceride-Glucose (TyG) index and SNHL to date. We conducted this analysis to elucidate the correlation between the TyG index and pure tone hearing thresholds among US adults.

Methods

Our analysis included 1226 adults (age range: 20 to 69 years old) from the 2015-2016 National Health and Nutrition Examination Survey (NHANES) data. TyG index was scored into three quartiles. Weighted univariate analysis, weighted multivariate linear regression analyses as well as smooth curve fittings evaluated the associations between TyG index and pure tone hearing thresholds.

Results

In the multiple regression analysis, the second tertile of TyG index was negatively associated with high-frequency hearing thresholds shifts. Furthermore, the non-linear relationships between TyG index and speech-frequency and high-frequency hearing thresholds were identified by smooth curve fittings. After adjusting for potential confounders, the fitted smooth curves were approximately U-shaped, and the two-segment linear regression models were constructed to calculate their inflection points.

Conclusion

Our findings suggested that the TyG index was nearly U-shaped association with speech-frequency and high-frequency hearing thresholds. These results may imply the importance of maintaining a balanced TyG index in health management.

Prevalence and Associated Factors of Sensorineural Hearing Impairment Among Patients with T2DM in Amhara Region, Northwest Ethiopia, 2022: A Multi-Centered Cross-Sectional Study

Background

Generally, people with type 2 diabetes mellitus in various countries experience a significant rate of sensorineural hearing impairment. Nonetheless, there is scant evidence of sensorineural hearing impairment among type 2 diabetes mellitus patients in Northwest Ethiopian. Therefore, the objective of this study was to evaluate the occurrence rate and contributing factors of sensorineural hearing impairment in type 2 diabetics at comprehensive and specialized referral hospitals in Northwest Ethiopia.

Methods

A facility-based cross-sectional study design was carried out from May 3, 2022, to June 14, 2022, on 846 study participants in Ethiopia, with a response rate of 99.65%. The research subjects were chosen by simple random sampling techniques. Data was gathered by using audiometric measurements and structured interview-administered questionnaires and then entered into EPI data version 4.6. Finally, it was exported to STATA 14 for analysis. Binary logistic regression, chi-square test, and odds ratio were done to verify the assumptions and degree of association. Ultimately, factors exhibiting a p-value < 0.05 with a 95% CI were regarded as significant predictors of hearing impairment.

Results

The magnitude of sensorineural hearing impairment in this investigation was 50.49% (95% CI: 45.67%, 55.26%). Factors significantly associated with sensorineural hearing impairment were age (AOR=1.10, 95% CI: 1.07, 1.14), hyperlipidemia (AOR=2.86, 95% CI: 1.05, 7.82), duration of diabetes (AOR=2.26, 95% CI: 1.26, 4.06), hypertension (AOR=1.94, 95% CI: 1.02, 3.69) and regular physical exercise (AOR=0.25, 95% CI: 0.09, 0.68).

Conclusions and Recommendations

In this study, relatively high rates of sensorineural hearing impairment were observed. Stakeholders should establish routine hearing screening, and participants will advise to incorporate regular physical exercise into their routines.

Mitochondrial DNA and Inflammation Are Associated with Cerebral Vessel Remodeling and Early Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus

Cerebrovascular disease accounts for major neurologic disabilities in patients with type 2 diabetes mellitus (DM). A potential association of mitochondrial DNA (mtDNA) and inflammation with cerebral vessel remodeling in patients with type 2 DM was evaluated. A cohort of 150 patients and 30 healthy controls were assessed concerning urinary albumin/creatinine ratio (UACR), synaptopodin, podocalyxin, kidney injury molecule-1 (KIM-1), N-acetyl-β-(D)-glucosaminidase (NAG), interleukins IL-17A, IL-18, IL-10, tumor necrosis factor-alpha (TNFα), intercellular adhesion molecule-1 (ICAM-1). MtDNA-CN and nuclear DNA (nDNA) were quantified in peripheral blood and urine by qRT-PCR. Cytochrome b (CYTB) gene, subunit 2 of NADH dehydrogenase (ND2), and beta 2 microglobulin nuclear gene (B2M) were assessed by TaqMan assays. mtDNA-CN was defined as the ratio of the number of mtDNA/nDNA copies, through analysis of the CYTB/B2M and ND2/B2M ratio; cerebral Doppler ultrasound: intima-media thickness (IMT)-the common carotid arteries (CCAs), the pulsatility index (PI) and resistivity index (RI)- the internal carotid arteries (ICAs) and middle cerebral arteries (MCAs), the breath-holding index (BHI). The results showed direct correlations of CCAs-IMT, PI-ICAs, PI-MCAs, RI-ICAs, RI-MCAs with urinary mtDNA, IL-17A, IL-18, TNFα, ICAM-1, UACR, synaptopodin, podocalyxin, KIM-1, NAG, and indirect correlations with serum mtDNA, IL-10. BHI correlated directly with serum IL-10, and serum mtDNA, and negatively with serum IL-17A, serum ICAM-1, and NAG. In neurologically asymptomatic patients with type 2 DM cerebrovascular remodeling and impaired cerebrovascular reactivity may be associated with mtDNA variations and inflammation from the early stages of diabetic kidney disease.

Nicotinamide riboside activates renal metabolism and protects the kidney in a model of Alport syndrome

Chronic kidney disease (CKD) is associated with renal metabolic disturbances, including impaired fatty acid oxidation (FAO). Nicotinamide adenine dinucleotide (NAD + ) is a small molecule that participates in hundreds of metabolism-related reactions. NAD + levels are decreased in CKD, and NAD + supplementation is protective. However, both the mechanism of how NAD + supplementation protects from CKD, as well as the cell types most responsible, are poorly understood. Using a mouse model of Alport syndrome, we show that nicotinamide riboside (NR), an NAD + precursor, stimulates renal peroxisome proliferator-activated receptor α signaling and restores FAO in the proximal tubules, thereby protecting from CKD in both sexes. Bulk RNA-sequencing shows that renal metabolic pathways are impaired in Alport mice and dramatically activated by NR in both sexes. These transcriptional changes are confirmed by orthogonal imaging techniques and biochemical assays. Single nuclei RNA-sequencing and spatial transcriptomics, both the first of their kind from Alport mice, show that NAD + supplementation restores FAO in the proximal tubules with minimal effects on the podocytes. Finally, we also report, for the first time, sex differences at the transcriptional level in this Alport model. Male Alport mice had more severe inflammation and fibrosis than female mice at the transcriptional level. In summary, the data herein identify both the protective mechanism and location of NAD + supplementation in this model of CKD.

Crosstalk among podocytes, glomerular endothelial cells and mesangial cells in diabetic kidney disease: an updated review

Diabetic kidney disease (DKD) is a long-term and serious complication of diabetes that affects millions of people worldwide. It is characterized by proteinuria, glomerular damage, and renal fibrosis, leading to end-stage renal disease, and the pathogenesis is complex and involves multiple cellular and molecular mechanisms. Among three kinds of intraglomerular cells including podocytes, glomerular endothelial cells (GECs) and mesangial cells (MCs), the alterations in one cell type can produce changes in the others. The cell-to-cell crosstalk plays a crucial role in maintaining the glomerular filtration barrier (GFB) and homeostasis. In this review, we summarized the recent advances in understanding the pathological changes and interactions of these three types of cells in DKD and then focused on the signaling pathways and factors that mediate the crosstalk, such as angiopoietins, vascular endothelial growth factors, transforming growth factor-β, Krüppel-like factors, retinoic acid receptor response protein 1 and exosomes, etc. Furthermore, we also simply introduce the application of the latest technologies in studying cell interactions within glomerular cells and new promising mediators for cell crosstalk in DKD. In conclusion, this review provides a comprehensive and updated overview of the glomerular crosstalk in DKD and highlights its importance for the development of novel intervention approaches.

The cGAS-STING pathway: a therapeutic target in diabetes and its complications

Diabetic wound healing (DWH) represents a major complication of diabetes where inflammation is a key impediment to proper healing. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has emerged as a central mediator of inflammatory responses to cell stress and damage. However, the contribution of cGAS-STING activation to impaired healing in DWH remains understudied. In this review, we examine the evidence that cGAS-STING-driven inflammation is a critical factor underlying defective DWH. We summarize studies revealing upregulation of the cGAS-STING pathway in diabetic wounds and discuss how this exacerbates inflammation and senescence and disrupts cellular metabolism to block healing. Partial pharmaceutical inhibition of cGAS-STING has shown promise in damping inflammation and improving DWH in preclinical models. We highlight key knowledge gaps regarding cGAS-STING in DWH, including its relationships with endoplasmic reticulum stress and metal-ion signaling. Elucidating these mechanisms may unveil new therapeutic targets within the cGAS-STING pathway to improve healing outcomes in DWH. This review synthesizes current understanding of how cGAS-STING activation contributes to DWH pathology and proposes future research directions to exploit modulation of this pathway for therapeutic benefit.

Mitochondrial transfer - a novel promising approach for the treatment of metabolic diseases

Metabolic disorders remain a major global health concern in the 21st century, with increasing incidence and prevalence. Mitochondria play a critical role in cellular energy production, calcium homeostasis, signal transduction, and apoptosis. Under physiological conditions, mitochondrial transfer plays a crucial role in tissue homeostasis and development. Mitochondrial dysfunction has been implicated in the pathogenesis of metabolic disorders. Numerous studies have demonstrated that mitochondria can be transferred from stem cells to pathologically injured cells, leading to mitochondrial functional restoration. Compared to cell therapy, mitochondrial transplantation has lower immunogenicity, making exogenous transplantation of healthy mitochondria a promising therapeutic approach for treating diseases, particularly metabolic disorders. This review summarizes the association between metabolic disorders and mitochondria, the mechanisms of mitochondrial transfer, and the therapeutic potential of mitochondrial transfer for metabolic disorders. We hope this review provides novel insights into targeted mitochondrial therapy for metabolic disorders.

CD36 deletion ameliorates diabetic kidney disease by restoring fatty acid oxidation and improving mitochondrial function

Renal tubular epithelial cells (TECs) are vulnerable to mitochondrial dysregulation, which is an integral part of diabetic kidney disease (DKD). We found that CD36 knockout ameliorated mitochondrial dysfunction and diabetic kidney injury in mice, improved renal function, glomerular hypertrophy, tubular injury, tubulointerstitial fibrosis, and kidney cell apoptosis. Furthermore, CD36 knockout conferred protection against diabetes-induced mitochondrial dysfunction and restored renal tubular cells and mitochondrial morphology. CD36 knockout also restored mitochondrial fatty acid oxidation (FAO) and enhanced FAO-associated respiration in diabetic TECs. CD36 was found to alter cellular metabolic pathways in diabetic kidneys partly via PDK4 the -AMPK axis inactivation. Because CD36 protects against DKD by improving mitochondrial function and restoring FAO, it can serve as a potential therapeutic target.

Urinary mitochondrial DNA may be useful in diagnosing early diabetic nephropathy

The present study aimed to determine whether urinary mitochondrial (mt)DNA could be combined as a non-invasive biomarker with other clinical findings of kidney injury to help diagnose early diabetic nephropathy (DN). A total of 165 patients with type 2 diabetes mellitus (T2DM) were enrolled in the present study and the mtDNA levels in urine were measured using quantitative PCR. The diagnostic value of urinary mtDNA levels in patients with T2DM was compared using estimated glomerular filtration rate (eGFR) or albumin-to-creatinine ratio staging. Spearman correlation analysis was used to analyze the correlation between urinary mtDNA and other clinical findings. Correlation factors for early DN were assessed using univariate logistic regression analysis. Urinary leukocyte and glucose levels do not interfere with urinary mtDNA levels. In patients with T2DM, the level of urinary mtDNA increases in the early stages of kidney injury and further increases with the severity of kidney injury. Urinary mtDNA levels in patients with eGFR 60-90 ml/min/1.73 m2 were higher than that in patients with eGFR >90 ml/min/1.73 m2. The levels of urinary mt89DNA and mt349DNA were negatively correlated with the eGFR level (ρ=-0.437; P<0.001; ρ=-0.390; P<0.001) and positively correlated with the level of cystatin C (ρ=0.177; P=0.025; ρ=0.144; P=0.070). Urinary mtDNA is positively correlated with early DN occurrence [odds ratio (OR), 1.330; 95% confidence interval (CI), 1.175-1.507; P<0.001; OR, 1.328; 95% CI, 1.156-1.525; P<0.001]. In conclusion, urinary mtDNA combined with other clinical indicators of kidney injury may help the diagnosis of early DN.

Poricoic acid A induces mitophagy to ameliorate podocyte injury in diabetic kidney disease via downregulating FUNDC1

Diabetic kidney disease (DKD) is a devastating complication of diabetes mellitus (DM) and is the most prevalent chronic kidney disease (CKD). Poricoic acid A (PAA), a component isolated from Traditional Chinese Medicine (TCM) Poria cocos, has hypoglycaemic and anti-fibrosis effects. However, the role of PAA in DKD remains largely unclear. To mimics an in vitro model of DKD, the mouse podocyte MPC5 cells were treated with high glucose (25 mM; HG) for 24 h. CCK-8 and flow cytometry assays were conducted for assessing MPC5 cell viability and apoptosis. Meanwhile, streptozotocin (STZ) was used to induce experimental DKD in mice by intraperitoneal injection. PAA notably inhibited the apoptosis and inflammation, reduced the generation of ROS, and elevated the MMP level in HG-treated MPC5 cells. Moreover, PAA obviously reduced blood glucose and urine protein levels, inhibited renal fibrosis in DKD mice. Meanwhile, PAA markedly increased LC3 and ATG5 levels and declined p62 and FUNDC1 levels in HG-treated MPC5 cells and in the kidney tissues of DKD mice, leading to the activation of cell mitophagy. Furthermore, the downregulation of FUNDC1 also inhibited apoptosis, inflammation, and promoted mitophagy in HG-treated MPC5 cells. As expected, the knockdown of FUNDC1 further enhanced the protective role of PAA in MPC5 cells following HG treatment, indicating that induction of mitophagy could attenuate podocyte injury. Collectively, PAA could exert beneficial effects on podocyte injury in DKD by promoting mitophagy via downregulating FUNDC1. These findings suggested that PAA may have great potential in alleviating kidney injury in DKD.

Correction to: YY1 inactivated transcription co-regulator PGC-1α to promote mitochondrial dysfunction of early diabetic nephropathy-associated tubulointerstitial fibrosis

The development of diabetic nephropathy (DN) could be promoted by the occurrence of tubulointerstitial fibrosis (TIF), which has a close relationship with mitochondrial dysfunction of renal tubular epithelial cells (RTECs). As a key regulator of metabolic homeostasis, Yin Yang 1 (YY1) plays an important role not only in regulating the fibrosis process but also in maintaining the mitochondrial function of pancreatic β-cells. However, it was not clear whether YY1 participated in maintaining mitochondrial function of RTECs in early DN-associated TIF. In this study, we dynamically detected mitochondrial functions and protein expression of YY1 in db/db mice and high glucose (HG)-cultured HK-2 cells. Our results showed that comparing with the occurrence of TIF, the emergence of mitochondrial dysfunction of RTECs was an earlier even, besides the up-regulated and nuclear translocated YY1. Correlation analysis showed YY1 expressions were negatively associated with PGC-1α in vitro and in vivo. Further mechanism research demonstrated the formation of mTOR-YY1 heterodimer induced by HG up-regulated YY1, the nuclear translocation of which inactivated PGC-1α by binding to the PGC-1α promoter. Overexpression of YY1 induced mitochondrial dysfunctions in normal glucose-cultured HK-2 cells and 8-weeks-old db/m mice. While, dysfunctional mitochondria induced by HG could be improved by knockdown of YY1. Finally, downregulation of YY1 could retard the progression of TIF by preventing mitochondrial functions, resulting in the improvement of epithelial-mesenchymal transition (EMT) in early DN. These findings suggested that YY1 was a novel regulator of mitochondrial function of RTECs and contributed to the occurrence of early DN-associated TIF.

Podocyte injury of diabetic nephropathy: Novel mechanism discovery and therapeutic prospects

Diabetic nephropathy (DN) is a severe complication of diabetes mellitus, posing significant challenges in terms of early prevention, clinical diagnosis, and treatment. Consequently, it has emerged as a major contributor to end-stage renal disease. The glomerular filtration barrier, composed of podocytes, endothelial cells, and the glomerular basement membrane, plays a vital role in maintaining renal function. Disruptions in podocyte function, including hypertrophy, shedding, reduced density, and apoptosis, can impair the integrity of the glomerular filtration barrier, resulting in elevated proteinuria, abnormal glomerular filtration rate, and increased creatinine levels. Hence, recent research has increasingly focused on the role of podocyte injury in DN, with a growing emphasis on exploring therapeutic interventions targeting podocyte injury. Studies have revealed that factors such as lipotoxicity, hemodynamic abnormalities, oxidative stress, mitochondrial dysfunction, and impaired autophagy can contribute to podocyte injury. This review aims to summarize the underlying mechanisms of podocyte injury in DN and provide an overview of the current research status regarding experimental drugs targeting podocyte injury in DN. The findings presented herein may offer potential therapeutic targets and strategies for the management of DN associated with podocyte injury.

Schisandrin B Alleviates Renal Tubular Cell Epithelial-Mesenchymal Transition and Mitochondrial Dysfunction by Kielin/Chordin-like Protein Upregulation via Akt Pathway Inactivation and Adenosine 5'-Monophosphate (AMP)-Activated Protein Kinase Pathway Activation in Diabetic Kidney Disease

Diabetic kidney disease is a common complication of diabetes and remains the primary cause of end-stage kidney disease in the general population. Schisandrin B (Sch B) is an active ingredient in Schisandra chinensis. Our study illustrates that Sch B can mitigate renal tubular cell (RTC) epithelial-mesenchymal transition (EMT) and mitochondrial dysfunction in db/db mice, accompanied by the downregulation of TGF-β1 and the upregulation of PGC-1α. Similarly, Sch B demonstrated a protective effect by reducing the expression of TGF-β1, α-SMA, fibronectin, and Col I, meanwhile enhancing the expression of E-cadherin in human RTCs (HK2 cells) stimulated with high glucose. Moreover, under high glucose conditions, Sch B effectively increased mitochondrial membrane potential, lowered ROS production, and increased the ATP content in HK2 cells, accompanied by the upregulation of PGC-1α, TFAM, MFN1, and MFN2. Mechanistically, the RNA-seq results showed a significant increase in KCP mRNA levels in HK2 cells treated with Sch B in a high glucose culture. The influence of Sch B on KCP mRNA levels was confirmed by real-time PCR in high glucose-treated HK2 cells. Depletion of the KCP gene reversed the impact of Sch B on TGF-β1 and PGC-1α in HK2 cells with high glucose level exposure, whereas overexpression of the KCP gene blocked EMT and mitochondrial dysfunction. Furthermore, the PI3K/Akt pathway was inhibited and the AMPK pathway was activated in HK2 cells exposed to a high concentration of glucose after the Sch B treatment. Treatment with the PI3K/Akt pathway agonist insulin and the AMPK pathway antagonist compound C attenuated the Sch B-induced KCP expression in HK2 cells exposed to a high level of glucose. Finally, molecular autodock experiments illustrated that Sch B could bind to Akt and AMPK. In summary, our findings suggested that Sch B could alleviate RTC EMT and mitochondrial dysfunction by upregulating KCP via inhibiting the Akt pathway and activating the AMPK pathway in DKD.

CUL3 induces mitochondrial dysfunction via MRPL12 ubiquitination in renal tubular epithelial cells

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease worldwide and the strongest predictor of mortality in patients with diabetes. Despite its significance, the pathological mechanism underlying the onset and progression of DKD remains incompletely understood. In this study, we have shown that mitochondrial ribosomal protein L12 (MRPL12) plays a significant role in DKD by modulating mitochondrial function. We demonstrated that MRPL12 was mainly ubiquitinated at K150 in renal tubular epithelial cells. We have found that Cullin3 (CUL3), an E3 ubiquitin ligase, directly interacts with MRPL12 and induces the K63-linked ubiquitination of MRPL12, resulting in mitochondrial biosynthesis dysfunction. Moreover, under high-glucose (HG) conditions in renal tubular epithelial cells, we observed up-regulation of CUL3 expression, significant increase in CUL3-mediated ubiquitination of MRPL12 and dysregulation of mitochondrial biosynthesis. Notably, CUL3 knockdown stabilised the MRPL12 protein and protected mitochondrial biosynthesis under HG conditions. Our findings provide novel insight into how CUL3 affects mitochondrial biosynthesis in renal tubular epithelial cells through MRPL12 ubiquitination and suggest a potential therapeutic strategy for DKD in the future.

Protective effect of eriodictyol against hyperglycemia-induced diabetic nephropathy in rats entails antioxidant and anti-inflammatory effects mediated by activating Nrf2

The pathogenesis of diabetic nephropathy (DN) involves cellular activation of oxidative stress and inflammation. Eriodictyol is a citrus-derived flavonoid with multiple pharmacological and protective effects in various conditions. The protective role of Eriodictyol against diabetes and diabetic nephropathy is less investigated. The current research aimed to explore the role of eriodictyol in protecting against DN prompted by streptozotocin in male rats and investigate some possible mechanisms of action. Diabetes was brought about in rats by an i.p injection of a lone dose (65 mg/kg). Five groups of rats were included (n = 8 each) as control (non-diabetic), eriodictyol (20 mg/kg, orally), STZ-diabetic, STZ + eriodictyol (20 mg/kg, orally), and STZ + eriodictyol (20 mg/kg, orally) + ML385 (30 µg/kg, i.p.). Kidney histology and the levels of some markers of kidney function, renal oxidative stress, and renal inflammation were analyzed in all groups of rats. Treatment with eriodictyol prevented the damage in the renal glomeruli and tubules and reduced renal immune cell infiltration in STZ-treated animals. It also spiked urinary creatinine excretion and reduced urine volume and urinary levels of albumin, monocyte chemoattractant protein 1 (MCP-1), urinary kidney injury molecule-1 (KIM-1), and nephrin in these diabetic rats. In addition, eriodictyol stimulated the nuclear protein accumulation of Nrf2 and boosted the expression of superoxide dismutase (SOD), glutathione (GSH), heme oxygenase-1 (HO-1), and catalase (CAT) in the diabetic rat kidneys. In concomitance, it reduced the nuclear levels of NF-κB and levels of interleukine-6 (IL-6), malondialdehyde (MDA), and tumor necrosis factor-α (TNF-α) and attenuated the reduction in renal ATP levels and the increase in the mitochondria transition pore opening (mtTPT). However, the administration of eriodictyol did not affect rats' body weights and fasting glucose and insulin levels but significantly reduced serum levels of cholesterol, triglycerides, LDL-c, and oxidized LDL-c (ox-LDL-c). In conclusion, eriodictyol prevents STZ-induced nephropathy by a hypolipidemic effect and concomitant antioxidant and anti-inflammatory effects mediated by activating Nrf2/NF-κB/antioxidant axis.

The potential mechanism of gut microbiota-microbial metabolites-mitochondrial axis in progression of diabetic kidney disease

Diabetic kidney disease (DKD), has become the main cause of end-stage renal disease (ESRD) worldwide. Lately, it has been shown that the onset and advancement of DKD are linked to imbalances of gut microbiota and the abnormal generation of microbial metabolites. Similarly, a body of recent evidence revealed that biological alterations of mitochondria ranging from mitochondrial dysfunction and morphology can also exert significant effects on the occurrence of DKD. Based on the prevailing theory of endosymbiosis, it is believed that human mitochondria originated from microorganisms and share comparable biological characteristics with the microbiota found in the gut. Recent research has shown a strong correlation between the gut microbiome and mitochondrial function in the occurrence and development of metabolic disorders. The gut microbiome's metabolites may play a vital role in this communication. However, the relationship between the gut microbiome and mitochondrial function in the development of DKD is not yet fully understood, and the role of microbial metabolites is still unclear. Recent studies are highlighted in this review to examine the possible mechanism of the gut microbiota-microbial metabolites-mitochondrial axis in the progression of DKD and the new therapeutic approaches for preventing or reducing DKD based on this biological axis in the future.

Association between HbA1c and hearing loss: a tertiary care center-based study

The purpose of this study was to investigate the correlation between glycated hemoglobin (HbA1c) levels and hearing loss (HL) using data from a tertiary hospital. Our hypothesis regarding the relationship between HL and HbA1c levels was that elevated HbA1c levels are associated with an increased risk of HL. We retrospectively reviewed the medical charts of patients diagnosed with sensorineural HL or diabetes between 2006 and 2021 at the Catholic Medical Center (CMC). Data were collected from the CMC's Clinical Data Warehouse. Participants were selected from patients who were prescribed pure-tone audiometry and an HbA1c blood test. The survey was completed for 5287 participants. The better ear pure-tone audiometry (PTA) for air conduction thresholds at 500, 1000, 2000, and 4000 Hz was calculated. Sensorineural HL was defined as a better ear PTA of 25 dB or higher. We used the HbA1c level as a diagnostic criterion for diabetes. The following criteria were used to define the HbA1c level: normal, HbA1c level below 5.6%; prediabetes, level between 5.6 and 6.4%; and diabetes, level of 6.5% or more. Among 5287 participants, 1129 were categorized as normal, 2119 as prediabetic, and 2039 as diabetic. The diabetic group was significantly older (p < 0.05). The PTA also significantly deteriorated in the diabetes group (p < 0.05). We analyzed the effects of age, sex, and HbA1c level on frequency-specific hearing using multiple regression. The hearing thresholds at all frequencies deteriorated significantly with increasing age and HbA1c level (p < 0.05). A case-control study was also performed to facilitate a comprehensive comparison between distinct groups. The participants were categorized into two groups: a case (PTA > 25 dB) and control group (PTA ≤ 25 dB), based on their PTA threshold of four frequencies. After adjusting for age and sex, we found no significant odds ratio (OR) of HL between the prediabetes group and the normal group. Notably, the OR of HL was significantly higher in the diabetes group with each PTA threshold and frequency. The 6.3% HbA1c level cutoff value was determined by analyzing the receiver operating characteristic curve for predicting hearing impairment > 25 dB. Diabetes was associated with hearing loss in all frequency ranges, particularly at high frequencies. Screening for HL is strongly recommended for patients with elevated HbA1c levels.

LncRNA H19: a novel player in the regulation of diabetic kidney disease

Diabetic kidney disease (DKD), one of the most severe complications of diabetes mellitus (DM), has received considerable attention owing to its increasing prevalence and contribution to chronic kidney disease (CKD) and end-stage kidney disease (ESRD). However, the use of drugs targeting DKD remains limited. Recent data suggest that long non-coding RNAs (lncRNAs) play a vital role in the development of DKD. The lncRNA H19 is the first imprinted gene, which is expressed in the embryo and down-regulated at birth, and its role in tumors has long been a subject of controversy, however, in recent years, it has received increasing attention in kidney disease. The LncRNA H19 is engaged in the pathological progression of DKD, including glomerulosclerosis and tubulointerstitial fibrosis via the induction of inflammatory responses, apoptosis, ferroptosis, pyroptosis, autophagy, and oxidative damage. In this review, we highlight the most recent research on the molecular mechanism and regulatory forms of lncRNA H19 in DKD, including epigenetic, post-transcriptional, and post-translational regulation, providing a new predictive marker and therapeutic target for the management of DKD.

Clinical Use and Treatment Mechanism of Molecular Hydrogen in the Treatment of Various Kidney Diseases including Diabetic Kidney Disease

As diabetes rates surge globally, there is a corresponding rise in the number of patients suffering from diabetic kidney disease (DKD), a common complication of diabetes. DKD is a significant contributor to chronic kidney disease, often leading to end-stage renal failure. However, the effectiveness of current medical treatments for DKD leaves much to be desired. Molecular hydrogen (H2) is an antioxidant that selectively reduces hydroxyl radicals, a reactive oxygen species with a very potent oxidative capacity. Recent studies have demonstrated that H2 not only possesses antioxidant properties but also exhibits anti-inflammatory effects, regulates cell lethality, and modulates signal transduction. Consequently, it is now being utilized in clinical applications. Many factors contribute to the onset and progression of DKD, with mitochondrial dysfunction, oxidative stress, and inflammation being strongly implicated. Recent preclinical and clinical trials reported that substances with antioxidant properties may slow the progression of DKD. Hence, we undertook a comprehensive review of the literature focusing on animal models and human clinical trials where H2 demonstrated effectiveness against a variety of renal diseases. The collective evidence from this literature review, along with our previous findings, suggests that H2 may have therapeutic benefits for patients with DKD by enhancing mitochondrial function. To substantiate these findings, future large-scale clinical studies are needed.

Research progress on multiple cell death pathways of podocytes in diabetic kidney disease

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease, and its clinical manifestations are progressive proteinuria, decreased glomerular filtration rate, and renal failure. The injury and death of glomerular podocytes are the keys to DKD. Currently, a variety of cell death modes have been identified in podocytes, including apoptosis, autophagy, endoplasmic reticulum (ER) stress, pyroptosis, necroptosis, ferroptosis, mitotic catastrophe, etc. The signaling pathways leading to these cell death processes are interconnected and can be activated simultaneously or in parallel. They are essential for cell survival and death that determine the fate of cells. With the deepening of the research on the mechanism of cell death, more and more researchers have devoted their attention to the underlying pathologic research and the drug therapy research of DKD. In this paper, we discussed the podocyte physiologic role and DKD processes. We also provide an overview of the types and specific mechanisms involved in each type of cell death in DKD, as well as related targeted therapy methods and drugs are reviewed. In the last part we discuss the complexity and potential crosstalk between various modes of cell death, which will help improve the understanding of podocyte death and lay a foundation for new and ideal targeted therapy strategies for DKD treatment in the future.

3-MCPD Induced Mitochondrial Damage of Renal Cells Via the Rhythmic Protein BMAL1 Targeting SIRT3/SOD2

Biorhythm regulates a variety of physiological functions and enables organisms to adapt to changing environments. 3-Monochloro-1,2-propanediol (3-MCPD) is a common food thermal processing contaminant, and the kidney is its toxic target organ. However, the nephrotoxicity mechanism of 3-MCPD has not been fully elucidated. In the study, we found that 3-MCPD caused mitochondrial damage in renal cells by inhibiting the SIRT3/SOD2 pathway. Further, we found that 3-MCPD could interfere with rhythm protein BMAL1 expression at protein and mRNA levels in mice kidney and NRK-52E cells. Simultaneously, the balance of the daily oscillation of SIRT3/SOD2 pathway proteins was impeded under 3-MCPD treatment. To determine the role of BAML1 in mitochondrial damage, we overexpressed the BMAL1 protein. The data showed that BMAL1 overexpression upregulated SIRT3 and SOD2 expression and attenuated mitochondrial damage caused by 3-MCPD. These results indicated that 3-MCPD inhibited the SIRT3/SOD2 pathway by affecting the expression of the rhythm protein BMAL1, thereby inducing mitochondrial damage in renal cells. Taken together, our work reveals that 3-MCPD may possess a toxic effect via circadian clock mechanisms.

CDCT-induced nephrotoxicity in rat by apoptosis via metabolic disturbance

Compound diclofenac sodium chlorphenamine maleate tablets (CDCT) are widely used for the cold in Asia. However, CDCT can cause hematuria symptoms in clinical, and the underlying mechanism is unknown. This study aims to investigate the CDCT-induced changes of morphology in kidney and metabolites and further explore the possible mechanisms of CDCT-induced nephrotoxicity. Sprague-Dawley rats were exposed to the CDCT at a clinical equivalent dose for 6 days. CDCT exposure can induce kidney injury and death. Pathological changes, including creatinine, urea nitrogen, and histopathology, were observed in rats. Furthermore, metabolomic-driven energy and glycerophospholipid metabolism pathway disorders, accompanied by remarkably changed key metabolites, such as succinate, leukotriene B4 (LTB4 ), and cardiolipin (CL), are observed in the CDCT-induced nephrotoxicity. Functionally, succinate accumulation leads to mitochondrial damage, as evidence by the imbalance of complex I and complex II and an increase in mitochondrial reactive oxygen species (mito SOX). Meanwhile, LTB4 activated the NF-κB signaling, as shown by increased protein of p65, phosphor-p65, and decreased protein of IκBα and phosphor-IκBα. Eventually, the apoptosis pathway was triggered in response to reduced CL, inflammation, and mito SOX, as demonstrated by the expression of cyt c, Bax, Bcl-2, caspase-3, and caspase-9. This study indicated that CDCT-induced metabolic disorders triggered nephrotoxicity and provided a comprehensive information to elucidate the mechanism of CDCT induced nephrotoxicity.

Biofactors regulating mitochondrial function and dynamics in podocytes and podocytopathies

Podocytes are terminally differentiated kidney cells acting as the main gatekeepers of the glomerular filtration barrier; hence, inhibiting proteinuria. Podocytopathies are classified as kidney diseases caused by podocyte damage. Different genetic and environmental risk factors can cause podocyte damage and death. Recent evidence shows that mitochondrial dysfunction also contributes to podocyte damage. Understanding alterations in mitochondrial metabolism and function in podocytopathies and whether altered mitochondrial homeostasis/dynamics is a cause or effect of podocyte damage are issues that need in-depth studies. This review highlights the roles of mitochondria and their bioenergetics in podocytes. Then, factors/signalings that regulate mitochondria in podocytes are discussed. After that, the role of mitochondrial dysfunction is reviewed in podocyte injury and the development of different podocytopathies. Finally, the mitochondrial therapeutic targets are considered.

Loss of Farnesoid X receptor (FXR) accelerates dysregulated glucose and renal injury in db/db mice

Background

End-stage renal disease is primarily caused by diabetic kidney disease (DKD). The Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, has anti-inflammatory, lipid-lowering and hypoglycemic properties. It also inhibits renal fibrosis. Although its physiological role is not fully understood, it also plays a role in the control of diabetic nephropathy (DN).

Methods

In the present study, we examined male FXR & leptin receptor double knockout mice, in which weight, blood glucose, body fat, and other indicators were monitored. After 6 months of rearing, blood and urine samples were collected and biochemical parameters were measured. Fibrosis was assessed by Masson's stain, while the assessment of the resuscitation case's condition was performed using succinate dehydrogenase (SDHA) stain immunohistochemistry, which measures aerobic respiration. Expression of molecules such as connective tissue growth factor (CTGF), SMAD family members 3 (Smad3) and 7 (Smad7), and small heterodimer partner were detected by RT-PCR and Western blotting as part of the application.

Results

FXR knockout decreased body weight and body fat in db/db mice, but increased blood glucose, urine output, and renal fibrosis. Primary mesangial cells (P-MCs) from FXR+/ + mice stimulated with transforming growth factor β1 (TGFβ1) showed significantly higher levels of related fibrosis factors, TGFβ1 and Smad3 mRNA and protein, and significantly reduced levels of Smad7. These effects were reversed by the action of FXR agonist chenodeoxycholic acid (CDCA). P-MCs from FXR-/ - mice stimulated with TGFβ1 resulted in an increase in the expression and protein levels of collagen I and TGFβ1, and the addition of CDCA had no significant effect on TGFβ1 stimulation. However, compared with FXR+/ +db/db mice, the rate of oxygen consumption, the rate of carbon dioxide production, and the rate of energy conversion were increased in FXR-/ -db/db mice, whereas the SDHA succinate dehydrogenase, a marker enzyme for aerobic respiration, was significantly decreased.

Conclusions

These results provide evidence that FXR plays a critical role in the regulation of mesangial cells in DN. The likely mechanism is that aberrant FXR expression activates TGFβ1, which induces extracellular matrix accumulation through the classical Smad signaling pathway, leading to mitochondrial dysfunction.

Tubular injury in diabetic kidney disease: molecular mechanisms and potential therapeutic perspectives

Diabetic kidney disease (DKD) is a chronic complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. Currently, there are limited therapeutic drugs available for DKD. While previous research has primarily focused on glomerular injury, recent studies have increasingly emphasized the role of renal tubular injury in the pathogenesis of DKD. Various factors, including hyperglycemia, lipid accumulation, oxidative stress, hypoxia, RAAS, ER stress, inflammation, EMT and programmed cell death, have been shown to induce renal tubular injury and contribute to the progression of DKD. Additionally, traditional hypoglycemic drugs, anti-inflammation therapies, anti-senescence therapies, mineralocorticoid receptor antagonists, and stem cell therapies have demonstrated their potential to alleviate renal tubular injury in DKD. This review will provide insights into the latest research on the mechanisms and treatments of renal tubular injury in DKD.

Eucommia lignans alleviate the progression of diabetic nephropathy through mediating the AR/Nrf2/HO-1/AMPK axis in vivo and in vitro

Lignans derived from Eucommia ulmoides Oliver (Eucommia lignans) inhibit the progression of inflammatory diseases, while their effect on the progression of diabetic nephropathy (DN) remained unclear. This work was designed to assess the function of Eucommia lignans in DN. The major constituents of Eucommia lignans were analyzed by UPLC-Q-TOF-MS/MS. The binding between Eucommia lignans and aldose reductase (AR) was predicted by molecular docking. Eucommia lignans (200, 100, and 50 mg·kg^-1) were used in model animals to evaluate their renal function changes. Rat glomerular mesangial cells (HBZY-1) were transfected with sh-AR, sh-AMPK, and oe-AR in the presence of high glucose (HG) or HG combined with Eucommia lignans to evaluate whether Eucommia lignans affected HG-induced cell injury and mitochondrial dysfunction through the AR/Nrf2/HO-1/AMPK axis. Eucommia lignans significantly attenuated the progression of DN in vivo. Eucommia lignans notably reversed HG-induced upregulation of inflammatory cytokines and mitochondrial injury, while downregulating the levels of Cyto c, caspase 9, AR, and NOX4 in HBZY-1 cells. In contrast, HG-induced downregulation of Nrf2, HO-1 and p-AMPKα levels were abolished by Eucommia lignans. Meanwhile, knockdown of AR exerted similar therapeutic effect of Eucommia lignans on DN progression, and AR overexpression reversed the effect of Eucommia lignans. Eucommia lignans alleviated renal injury through the AR/Nrf2/HO-1/AMPK axis. Thus, these findings might provide evidence for the use of Eucommia lignans in treating DN.

Mitochondrial DNA Changes in Blood and Urine Display a Specific Signature in Relation to Inflammation in Normoalbuminuric Diabetic Kidney Disease in Type 2 Diabetes Mellitus Patients

Mitochondrial dysfunction is an important mechanism contributing to the development and progression of diabetic kidney disease (DKD). Mitochondrial DNA (mtDNA) levels in blood and urine were evaluated in relation to podocyte injury and proximal tubule (PT) dysfunction, as well as to a specific inflammatory response in normoalbuminuric DKD. A total of 150 type 2 diabetes mellitus (DM) patients (52 normoalbuminuric, 48 microalbuminuric, and 50 macroalbuminuric ones, respectively) and 30 healthy controls were assessed concerning the urinary albumin/creatinine ratio (UACR), biomarkers of podocyte damage (synaptopodin and podocalyxin), PT dysfunction (kidney injury molecule-1 (KIM-1) and N-acetyl-β-(D)-glucosaminidase (NAG)), and inflammation (serum and urinary interleukins (IL-17A, IL-18, and IL-10)). MtDNA-CN and nuclear DNA (nDNA) were quantified in peripheral blood and urine via qRT-PCR. MtDNA-CN was defined as the ratio of the number of mtDNA/nDNA copies via analysis of the CYTB/B2M and ND2/B2M ratio. Multivariable regression analysis provided models in which serum mtDNA directly correlated with IL-10 and indirectly correlated with UACR, IL-17A, and KIM-1 (R² = 0.626; p < 0.0001). Urinary mtDNA directly correlated with UACR, podocalyxin, IL-18, and NAG, and negatively correlated with eGFR and IL-10 (R² = 0.631; p < 0.0001). Mitochondrial DNA changes in serum and urine display a specific signature in relation to inflammation both at the podocyte and tubular levels in normoalbuminuric type 2 DM patients.

Therapeutic Potential of Targeting Complement C5a Receptors in Diabetic Kidney Disease

Diabetic kidney disease (DKD) affects 30-40% of patients with diabetes and is currently the leading cause of end-stage renal disease (ESRD). The activation of the complement cascade, a highly conserved element of the innate immune system, has been implicated in the pathogenesis of diabetes and its complications. The potent anaphylatoxin C5a is a critical effector of complement-mediated inflammation. Excessive activation of the C5a-signalling axis promotes a potent inflammatory environment and is associated with mitochondrial dysfunction, inflammasome activation, and the production of reactive oxygen species. Conventional renoprotective agents used in the treatment of diabetes do not target the complement system. Mounting preclinical evidence indicates that inhibition of the complement system may prove protective in DKD by reducing inflammation and fibrosis. Targeting the C5a-receptor signaling axis is of particular interest, as inhibition at this level attenuates inflammation while preserving the critical immunological defense functions of the complement system. In this review, the important role of the C5a/C5a-receptor axis in the pathogenesis of diabetes and kidney injuries will be discussed, and an overview of the status and mechanisms of action of current complement therapeutics in development will be provided.

The role of pyroptosis in inflammatory diseases

Programmed cell death has crucial roles in the physiological maturation of an organism, the maintenance of metabolism, and disease progression. Pyroptosis, a form of programmed cell death which has recently received much attention, is closely related to inflammation and occurs via canonical, non-canonical, caspase-3-dependent, and unclassified pathways. The pore-forming gasdermin proteins mediate pyroptosis by promoting cell lysis, contributing to the outflow of large amounts of inflammatory cytokines and cellular contents. Although the inflammatory response is critical for the body's defense against pathogens, uncontrolled inflammation can cause tissue damage and is a vital factor in the occurrence and progression of various diseases. In this review, we briefly summarize the major signaling pathways of pyroptosis and discuss current research on the pathological function of pyroptosis in autoinflammatory diseases and sterile inflammatory diseases.

Biochanin A Ameliorates Nephropathy in High-Fat Diet/Streptozotocin-Induced Diabetic Rats: Effects on NF-kB/NLRP3 Axis, Pyroptosis, and Fibrosis

Nephropathy is the most prevalent microvascular disorder in diabetes mellitus. Oxidative stress and inflammatory cascade provoked by the persistent hyperglycemic milieu play integral roles in the aggravation of renal injury and fibrosis. We explored the impact of biochanin A (BCA), an isoflavonoid, on the inflammatory response, nod-like receptor protein 3 (NLRP3) inflammasome activation, oxidative stress, and fibrosis in diabetic kidneys. A high-fat-diet/streptozotocin (HFD/STZ)-induced experimental model of diabetic nephropathy (DN) was established in Sprague Dawley rats, and in vitro studies were performed in high-glucose-induced renal tubular epithelial (NRK-52E) cells. Persistent hyperglycemia in diabetic rats was manifested by perturbation of renal function, marked histological alterations, and oxidative and inflammatory renal damage. Therapeutic intervention of BCA mitigated histological changes, improved renal function and antioxidant capacity, and suppressed phosphorylation of nuclear factor-kappa B (NF-κB) and nuclear factor-kappa B inhibitor alpha (IκBα) proteins. Our in vitro data reveal excessive superoxide generation, apoptosis, and altered mitochondrial membrane potential in NRK-52E cells that were cultured in a high-glucose (HG) environment were subsided by BCA intervention. Meanwhile, the upregulated expressions of NLRP3 and its associated proteins, the pyroptosis-indicative protein gasdermin-D (GSDMD) in the kidneys, and HG-stimulated NRK-52E cells were significantly ameliorated by BCA treatment. Additionally, BCA blunted transforming growth factor (TGF)-β/Smad signaling and production of collagen I, collagen III, fibronectin, and alfa-smooth muscle actin (α-SMA) in diabetic kidneys. Our results indicate the plausible role of BCA in attenuating DN, presumably through modulation of the apoptotic cascade in renal tubular epithelial cells and the NF-κB/NLRP3 axis.

Germacrone protects renal tubular cells against ferroptotic death and ROS release by re-activating mitophagy in diabetic nephropathy

Mitophagy is a critical intracellular event during the progression of diabetic nephropathy (DN). Our previous study demonstrated that germacrone has anti-ferroptotic properties and is a potential therapeutic agent for DN. However, the relationship among germacrone, mitophagy, and ferroptosis in DN remains unclear. In this study, the data confirmed that germacrone ameliorates high glucose (HG)-induced ferroptosis through limiting Fe (2+) content and lipid reactive oxygen species (ROS) accumulation in human kidney 2 (HK-2) cells. Germacrone reversed HG-mediated inhibition of mitophagy. Mitophagy inhibition and anabatic mitochondrial ROS abrogate germacrone-mediated protective effects against ferroptotic death, resulting in the subsequent activation of mitochondrial DNA (mtDNA) cytosolic leakage-induced stimulator of interferon response CGAMP interactor 1 (STING) signaling. The combination of a mitochondrial ROS antagonist and germacrone acts synergistically to alleviate the ferroptotic death of tubular cells and DN symptoms. In summary, germacrone ameliorated ferroptotic death in tubular cells by reactivating mitophagy and inhibiting mtDNA-STING signaling in DN. This study provides a novel insight into germacrone-mediated protection against DN progression and further confirms that antioxidant pharmacological strategies facilitate the treatment of DN.

Mitochondrial transfer from bone mesenchymal stem cells protects against tendinopathy both in vitro and in vivo

BACKGROUND

Although mesenchymal stem cells (MSCs) have been effective in tendinopathy, the mechanisms by which MSCs promote tendon healing have not been fully elucidated. In this study, we tested the hypothesis that MSCs transfer mitochondria to injured tenocytes in vitro and in vivo to protect against Achilles tendinopathy (AT).

METHODS

Bone marrow MSCs and H₂O₂-injured tenocytes were co-cultured, and mitochondrial transfer was visualized by MitoTracker dye staining. Mitochondrial function, including mitochondrial membrane potential, oxygen consumption rate, and adenosine triphosphate content, was quantified in sorted tenocytes. Tenocyte proliferation, apoptosis, oxidative stress, and inflammation were analyzed. Furthermore, a collagenase type I-induced rat AT model was used to detect mitochondrial transfer in tissues and evaluate Achilles tendon healing.

RESULTS

MSCs successfully donated healthy mitochondria to in vitro and in vivo damaged tenocytes. Interestingly, mitochondrial transfer was almost completely blocked by co-treatment with cytochalasin B. Transfer of MSC-derived mitochondria decreased apoptosis, promoted proliferation, and restored mitochondrial function in H₂O₂-induced tenocytes. A decrease in reactive oxygen species and pro-inflammatory cytokine levels (interleukin-6 and -1β) was observed. In vivo, mitochondrial transfer from MSCs improved the expression of tendon-specific markers (scleraxis, tenascin C, and tenomodulin) and decreased the infiltration of inflammatory cells into the tendon. In addition, the fibers of the tendon tissue were neatly arranged and the structure of the tendon was remodeled. Inhibition of mitochondrial transfer by cytochalasin B abrogated the therapeutic efficacy of MSCs in tenocytes and tendon tissues.

CONCLUSIONS

MSCs rescued distressed tenocytes from apoptosis by transferring mitochondria. This provides evidence that mitochondrial transfer is one mechanism by which MSCs exert their therapeutic effects on damaged tenocytes.

Astragaloside IV attenuates podocyte apoptosis through ameliorating mitochondrial dysfunction by up-regulated Nrf2-ARE/TFAM signaling in diabetic kidney disease

Defective antioxidant system as well as mitochondrial dysfunction contributes to the pathogenesis and progression of diabetic kidney disease (DKD). Nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated signaling is the central defensive mechanism against oxidative stress and therefore pharmacological activation of Nrf2 is a promising therapeutic strategy. In this study, using molecular docking we found that Astragaloside IV (AS-IV), an active ingredient from traditional formula of Huangqi decoction (HQD), exerted a higher potential to promote Nrf2 escape from Keap1-Nrf2 interaction via competitively bind to amino acid sites in Keap1. When podocyte exposed to high glucose (HG) stimulation, mitochondrial morphological alterations and podocyte apoptosis were presented and accompanied by Nrf2 and mitochondrial transcription factor A (TFAM) downregulation. Mechanistically, HG promoted a decrease in mitochondria-specific electron transport chain (ETC) complexes, ATP synthesis and mtDNA content as well as increased ROS production. Conversely, all these mitochondrial defects were dramatically alleviated by AS-IV, but suppression of Nrf2 with inhibitor or siRNA and TFAM siRNA simultaneously alleviated the AS-IV efficacy. Moreover, experimental diabetic mice exhibited significant renal injury as well as mitochondrial disorder, corresponding with the decreased expression of Nrf2 and TFAM. On the contrary, AS-IV reversed the abnormality and the Nrf2 and TFAM expression were also restored. Taken together, the present findings demonstrate the improvement of AS-IV on mitochondrial function, thereby resistance to oxidative stress-induced diabetic kidney injury and podocyte apoptosis, and the process is closely associated with activation of Nrf2-ARE/TFAM signaling.

Protease-activated receptors in kidney diseases: A comprehensive review of pathological roles, therapeutic outcomes and challenges

Studies have demonstrated that protease-activated receptors (PARs) with four subtypes (PAR1-4) are mainly expressed in the renal epithelial, endothelial, and podocyte cells. Some endogenous and urinary proteases, namely thrombin, trypsin, urokinase, and kallikrein released during diseased conditions, are responsible for activating different subtypes of PARs. Each PAR receptor subtype is involved in kidney disease of distinct aetiology. PAR1 and PAR2 have shown differential therapeutic outcomes in rodent models of type-1 and type-2 diabetic kidney diseases due to the distinct etiological basis of each disease type, however such findings need to be confirmed in other diabetic renal injury models. PAR1 and PAR2 blockers have been observed to abolish drug-induced nephrotoxicity in rodents by suppressing tubular inflammation and fibrosis and preventing mitochondrial dysfunction. Notably, PAR2 inhibition improved autophagy and prevented fibrosis, inflammation, and remodeling in the urethral obstruction model. Only the PAR1/4 subtypes have emerged as a therapeutic target for treating experimentally induced nephrotic syndrome, where their respective antibodies attenuated the podocyte apoptosis induced upon thrombin activation. Strikingly PAR2 and PAR4 subtypes involvement has been tested in sepsis-induced acute kidney injury (AKI) and renal ischemia-reperfusion injury models. Thus, more studies are required to delineate the role of other subtypes in the sepsis-AKI model. Evidence suggests that PARs regulate oxidative, inflammatory stress, immune cell activation, fibrosis, autophagic flux, and apoptosis during kidney diseases.

A bifunctional fusion protein protected against diabetic nephropathy by suppressing NLRP3 activation

Diabetic nephropathy (DN), the principal pathogeny of end-stage renal disease (ESRD), is related to metabolic disorders, chronic inflammation, and oxidative stress. It was reported that high expression of interleukin-17A (IL-17A) was intimately related to the progression of DN, and targeting IL-17A exhibited regulating effects on inflammation and autoimmunity but had only limited impact on the oxidative stress damage in DN. Recent studies showed that interleukin-22 (IL-22) could inhibit mitochondrial damage and inflammatory response. Thus, the cytokine IL-22 was first fused to anti-IL-17A antibody for endowing the antibody with the anti-hyperglycemia and anti-inflammation activity. Our study demonstrated that the fusion molecule, anti-IL17A/IL22 fusion protein, could not only lead to the increase of M1 macrophages and the decrease of M2 macrophages, further improving the immune microenvironment, but also prevent the loss of mitochondrial membrane potential by reducing the production of ROS in murine DN model. In addition, the fusion protein could block TRAF6/NF-κB and AKT/ROS/TXNIP signaling pathways, further synergistically restraining the production of NLRP3, thus suppressing the inflammatory response and playing beneficial effect on slowing down the progression of DN. In conclusion, our findings demonstrated that the bifunctional IL-17A antibody and IL-22 fusion protein were of great benefit to DN, which highlighted a potential therapeutic strategy. KEY POINTS: • Anti-IL17A/IL22 fusion protein could improve the immune microenvironment and reduce the production of ROS. • Anti-IL17A/IL22 fusion protein could block TRAF6/NF-κB and AKT/ROS/TXNIP signaling pathways and then restrain the activation of NLRP3.

Identification of transcription factors related to diabetic tubulointerstitial injury

BACKGROUND

Diabetic nephropathy (DN) is a main cause of chronic renal failure. Despite decades of extensive study, the molecular mechanisms underlying diabetic tubulointerstitial injury remain unclear. We aim to identify key transcription factor genes involved in diabetic tubulointerstitial injury.

METHODS

A microarray dataset (GSE30122) from Gene Expression Omnibus (GEO) was downloaded. A total of 38 transcription factor genes based on 166 differentially expressed genes (DEGs) were identified by UCSC_TFBS.

RESULTS

The regulatory network showed connections between the top 10 transcription factors and their target DEGs. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of targeted DEGs indicated that extracellular space, extracellular exosome, cell surface and complement and coagulation cascades were most significantly enriched. Utilizing Nephroseq v5 online platform, the mRNA expression pattern analysis of transcription factor genes demonstrated that mRNA expression of CDC5, CEBPA, FAC1, HFH1, IRF1, NFE2 and TGIF1 increased in renal tubulointerstitium of DN patients compared with normal controls while that of CEBPB and FOXO4 decreased in renal tubulointerstitium of DN patients compared with normal controls. Correlation analysis between mRNA expression of transcription factor genes in renal tubulointerstitium and clinical features showed that AP1, BACH1, CDC5, FAC1, FOXD1, FOXJ2, FOXO1, FOXO4, HFH1, IRF1, POU3F2, SOX5, SOX9, RSRFC4, S8 and TGIF1 may be related to diabetic tubulointerstitial injury.

CONCLUSIONS

(1) CDC5, FAC1, FOXO4, HFH1, IRF1 and TGIF1 may be key transcription factor genes. (2)Transcription factors involved in diabetic tubulointerstitial injury may become prospective targets for diagnosis and treatment of DN.

The Role of Histone Modifications in the Pathogenesis of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease. The pathogenesis of DKD is multifactorial, with several molecular pathways implicated. Recent data suggest that histone modification plays an important role in the development and progression of DKD. Histone modification appears to induce oxidative stress, inflammation and fibrosis in the diabetic kidney. In the present review, we summarize the current knowledge on the association between histone modification and DKD.

Mitochondria-associated endoplasmic reticulum membranes promote mitochondrial fission through AKAP1-Drp1 pathway in podocytes under high glucose conditions

Excessive mitochondrial fission in podocytes is a critical feature of diabetic nephropathy (DN). Mitochondria-associated endoplasmic reticulum membranes (MAMs) are contact sites between the endoplasmic reticulum (ER) and mitochondria, which are suggested to be related to mitochondrial function. However, the role of MAMs in mitochondrial dynamics disorder in podocytes remains unknown. Here, we firstly reported a novel mechanism of MAMs' effects on mitochondrial dynamics in podocytes under diabetic conditions. Increased MAMs were found in diabetic podocytes in vivo and in vitro, which were positively correlated with excessive mitochondrial fission. What's more, we also found that A-kinase anchoring protein 1 (AKAP1) was located in MAMs, and its translocation to MAMs was increased in podocytes cultured with high glucose (HG). In addition, AKAP1 knockdown significantly reduced mitochondrial fission and attenuated high glucose induced-podocyte injury through regulating phosphorylation of dynamin-related protein 1 (Drp1) and its subsequent mitochondrial translocation. On the contrary, AKAP1 overexpression in these podocytes showed the opposite effect. Finally, pharmacological inhibition of Drp1 alleviated excessive mitochondrial fission and podocyte damage in AKAP1 overexpressed podocytes. Our data suggest that MAMs were increased in podocytes under diabetic conditions, leading to excessive mitochondrial fission and podocyte damage through AKAP1-Drp1 signaling.

miR-124-3p improves mitochondrial function of renal tubular epithelial cells in db/db mice

Diabetic kidney disease (DKD) is one of the most serious complications of diabetes mellitus (DM) and the main cause of end-stage renal failure. However, the pathogenesis of DKD is complicated. In this study, we found that miR-124-3p plays a key role in regulating renal mitochondrial function and explored its possible mechanism in DKD progression by performing a series of in vitro and in vivo experiments. Decreased expression of miR-124-3p was found in db/db mice compared to db/m mice. Moreover, miR-124-3p down-regulated FOXQ1 by targeting FOXQ1 mRNA 3'-UTR in NRK-52E cells. Also, an increase in FOXQ1 and down-regulation of Sirt4 were found in db/db mouse kidney and renal tubular epithelial cells cultured with high glucose and high lipid. Overexpression of FOXQ1 could further down-regulate the expression of Sirt4 and aggravate the damage of mitochondria. Conversely, the knockdown of the FOXQ1 gene induced Sirt4 expression and partially restored mitochondrial function. To verify the effects of miR-124-3p on Sirt4 and mitochondria, we found that miR-124-3p mimics could up-regulate Sirt4 and inhibit ROS production and MitoSOX, thus restoring the number and morphology of mitochondria. These results showed that under high-glucose and high-lipid conditions, the down-regulation of miR-124-3p induces FOXQ1 in renal tubular epithelial cells, which in turn suppresses Sirt4 and leads to mitochondrial dysfunction, promoting the development of DKD.