Pharmacological Targeting of Mitochondria in Diabetic Kidney Disease

4-Octyl itaconate attenuates renal tubular injury in db/db mice by activating Nrf2 and promoting PGC-1α-mediated mitochondrial biogenesis

Objectives: The aim of this study was to investigate the mechanism of itaconate's potential effect in diabetic kidney disease.

Methods: Renal immune responsive gene 1 (IRG1) levels were measured in db/db mice and streptozotocin (STZ) + high-fat diet (HFD)-induced diabetic mice. Irg1 knockout mice were generated. db/db mice were treated with 4-octyl itaconate (4-OI, 50 mg/kg), a derivative of itaconate, for 4 weeks. Renal function and morphological changes were investigated. Ultrastructural alterations were determined by transmission electron microscopy.

Results: Renal IRG1 levels were reduced in two diabetic models. STZ+HFD-treated Irg1 knockout mice exhibited aggravated renal tubular injury and worsened renal function. Treatment with 4-OI lowered urinary albumin-to-creatinine ratio and blood urea nitrogen levels, and restored renal histological changes in db/db mice. It improved mitochondrial damage, increased expressions of peroxisome-proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitochondrial transcription factor A (TFAM) in the renal cortex of db/db mice. These were confirmed in vitro; 4-OI improved high glucose-induced abnormal mitochondrial morphology and TFAM expression in HK-2 cells, effects that were inhibited by PGC-1α silencing. Moreover, 4-OI reduced the number of apoptotic cells in the renal cortex of db/db mice. Further study showed that 4-OI increased renal Nrf2 expression and decreased oxidative stress levels in db/db mice. In HK-2 cells, 4-OI decreased high glucose-induced mitochondrial ROS production, which was reversed by Nrf2 silencing. Nrf2 depletion also inhibited 4-OI-mediated regulation of PGC-1α, TFAM, and mitochondrial apoptotic protein expressions.

Conclusions: 4-OI attenuates renal tubular injury in db/db mice by activating Nrf2 and promoting PGC-1α-mediated mitochondrial biogenesis.

Polygala fallax Hemsl. ameliorated high glucose-induced podocyte injury by modulating mitochondrial mPTP opening through the SIRT1/PGC-1α pathway

This study aimed to investigate the effects and molecular mechanism of PF on high glucose (HG)-induced podocyte injury. Results found that PF increased proliferation activity, decreased apoptosis, LDH, and caspase-3 levels, and increased nephrin and podocin expression in HG-induced cells. Similarly, PF improved HG-induced mitochondrial damage, decreased Ca2+ and ROS content, alleviated oxidative stress, inhibited mPTP opening, increased mitochondrial membrane potential, and decreased the expressions of Drp1, Bak, Bax, and Cytc in cytoplasm, increased the expressions of SIRT1, PGC-1α, HSP70, HK2, and Cytc in mitochondria of podocytes. The use of mPTP agonist/blocker and SIRT1 inhibitor confirmed that PF alleviates HG-induced podocyte injury by regulating mitochondrial mPTP opening through SIRT1/PGC-1α. In addition, PF affected HK2-VDAC1 protein binding to regulate mPTP opening via the SIRT1/PGC-1α pathway. In conclusion, PF-regulated HK2-VDAC1 protein binding affected mitochondrial mPTP opening and improved HG-induced podocyte injury through the SIRT1/PGC-1α pathway.

Comprehensive analysis of cuproptosis-related ceRNA network and immune infiltration in diabetic kidney disease

Background

Diabetic kidney disease (DKD) is the primary contributor to renal failure and poses a severe threat to human health. Accumulating studies demonstrated that competing endogenous RNA (ceRNA) network is involved in cuproptosis and DKD progression. However, the role of cuproptosis-associated ceRNA network and immune infiltration in DKD remains largely unclear. This study aimed to investigate the cuproptosis-related ceRNA regulation network and immune infiltration in DKD.

Methods

The rat model of DKD was induced by combining the nephrectomy of the left kidney, high-fat diet, and streptozotocin. Differentially expressed genes (DEGs), miRNAs (DEMs), and lncRNAs (DELs) between normal and DKD rats were obtained. DEGs were intersected with cuproptosis-related genes (CRGs) to obtain DE-CRGs. LncRNAs and miRNAs were predicted based on the DE-CRGs, and they were intersected with DEMs and DELs, respectively. Subsequently, a cuproptosis-associated lncRNA-miRNA-mRNA network was established in DKD. In addition, the relative proportion of 22 infiltrating immune cell types in each sample was calculated, and the relationship between hub DE-CRGs and immune cells was explored.

Results

In total, there were 429 DEGs, 22 DEMs, and 48 DELs between CON and MOD groups. Then, 73 DE-CRGs were obtained, which were significantly enriched in 22 pathways, such as MAPK signaling pathway, IL-17 signaling pathway, and TNF signaling pathway. In addition, a core cuproptosis-related ceRNA network that included one lncRNA (USR0000B2476D), one miRNA (miR-34a-3p), and eight mRNAs (Mmp9, Pik3c3, Prom1, Snta1, Slc51b, Ntrk3, Snca, Egf) was established. In addition, 18 hub DE-CRGs were obtained. CIBERSORT algorithms showed that resting dendritic cells and resting NK cells were more infiltrated whereas regulatory T cells were less infiltrated in DKD rats than in normal rats. Spearman's correlation analysis revealed that hub DE-CRGs showed significant positive or negative correlations with naive B cells, regulatory T cells, resting NK cells, M0 macrophages, resting dendritic cells, and resting mast cells.

Conclusion

A ceRNA network was comprehensively constructed, and 18 hub DE-CRGs were obtained, which will provide novel insights into the pathologic mechanism elucidation and targeted therapy development of DKD.

WTAP and METTL14 regulate the m6A modification of DKK3 in renal tubular epithelial cells of diabetic nephropathy

Diabetic nephropathy (DN) is an important cause of death in diabetes patients, which is mainly due to its complex pathogenesis. Here, we explored the role of N6-methyladenosine (m6A) RNA methylation in DN development. Renal tubular epithelial cells from DN patients and experimental DN mice treated with streptozotocin (STZ) exhibited a considerable increase in METTL14 and WTAP expression as well as overall m6A methylation. Knocking down the expression of METTL14 and WTAP inhibited the migration and proliferation of tubular epithelial cells. MeRIP-seq analysis of the renal tissues of DN patients revealed that the genes with elevated m6A methylation were concentrated in the Wnt/β-Catenin signaling pathway. Dickkopf homolog 3 (DKK3) was screened out as the gene with the most significant increase in m6A methylation. In addition, the expression change pattern of DKK3 under DN circumstances is in line with those of METTL14 and WTAP. DKK3's m6A methylation sites were confirmed to be located in the 3'UTR region, which is how METTL14 and WTAP improved DKK3's mRNA stability. Finally, YTHDF1, a m6A reader, was demonstrated to recognize m6A-methylated DKK3 and promote DKK3 expression.

IGFBP2 induces podocyte apoptosis promoted by mitochondrial damage via integrin α5/FAK in diabetic kidney disease

Podocyte apoptosis or loss is the pivotal pathological characteristic of diabetic kidney disease (DKD). Insulin-like growth factor-binding protein 2 (IGFBP2) have a proinflammatory and proapoptotic effect on diseases. Previous studies have shown that serum IGFBP2 level significantly increased in DKD patients, but the precise mechanisms remain unclear. Here, we found that IGFBP2 levels obviously increased under a diabetic state and high glucose stimuli. Deficiency of IGFBP2 attenuated the urine protein, renal pathological injury and glomeruli hypertrophy of DKD mice induced by STZ, and knockdown or deletion of IGFBP2 alleviated podocytes apoptosis induced by high concentration of glucose or in DKD mouse. Furthermore, IGFBP2 facilitated apoptosis, which was characterized by increase in inflammation and oxidative stress, by binding with integrin α5 (ITGA5) of podocytes, and then activating the phosphorylation of focal adhesion kinase (FAK)-mediated mitochondrial injury, including membrane potential decreasing, ROS production increasing. Moreover, ITGA5 knockdown or FAK inhibition attenuated the podocyte apoptosis caused by high glucose or IGFBP2 overexpression. Taken together, these findings unveiled the insight mechanism that IGFBP2 increased podocyte apoptosis by mitochondrial injury via ITGA5/FAK phosphorylation pathway in DKD progression, and provided the potential therapeutic strategies for diabetic kidney disease.

A glycopolymersome strategy for 'drug-free' treatment of diabetic nephropathy

Diabetic nephropathy is a severe complication of diabetes. Treatment of diabetic nephropathy is an important challenge due to persistent hyperglycemia and elevated levels of reactive oxygen species (ROS) in the kidney. Herein, we designed a glycopolymersome that can treat type 2 diabetic nephropathy by effectively inhibiting hyperglycemia and ROS-associated diabetic nephropathy pathogenesis. The glycopolymersome is self-assembled from phenylboronic acid derivative-containing copolymer, poly(ethylene oxide)45-block-poly[(aspartic acid)13-stat-glucosamine24-stat-(phenylboronic acid)18-stat-(phenylboronic acid pinacol ester)3] [PEO45-b-P(Asp13-stat-GA24-stat-PBA18-stat-PAPE3)]. PBA segment can reversibly bind blood glucose or GA segment for long-term regulation of blood glucose levels; PAPE segment can scavenge excessive ROS for renoprotection. In vitro studies confirmed that the glycopolymersomes exhibit efficient blood glucose responsiveness within 2 h and satisfactory ROS-scavenging ability with 500 μM H2O2. Moreover, the glycopolymersomes display long-acting regulation of blood glucose levels in type 2 diabetic nephropathy mice within 32 h. Dihydroethidium staining revealed that these glycopolymersomes reduced ROS to normal levels in the kidney, which led to 61.7% and 76.6% reduction in creatinine and urea levels, respectively, along with suppressing renal apoptosis, collagen accumulation, and glycogen deposition in type 2 diabetic nephropathy mice. Notably, the polypeptide-based glycopolymersome was synthesized by ring-opening polymerization (ROP) of N-carboxyanhydrides (NCAs), thereby exhibiting favorable biodegradability. Overall, we proposed a new glycopolymersome strategy for 'drug-free' treatment of diabetic nephropathy, which could be extended to encompass the design of various multifunctional nanoparticles targeting diabetes and its associated complications.

Phenylsulfate-induced oxidative stress and mitochondrial dysfunction in podocytes are ameliorated by Astragaloside IV activation of the SIRT1/PGC1α /Nrf1 signaling pathway

Astragaloside IV (AS-IV) exhibits diverse biological activities. Despite this, the detailed molecular mechanisms by which AS-IV ameliorates diabetic nephropathy (DN) and shields podocytes from oxidative stress (OS) and mitochondrial dysfunction remain poorly understood. In this study, we used biochemical assays, histopathological analysis, Doppler ultrasound, transmission electron microscopy，flow cytometry, fluorescence staining, and Western blotting and other methods. AS-IV was administered to db/db mice for in vivo experimentation. Our findings indicated that AS-IV treatment significantly reduced diabetes-associated markers, proteinuria, and kidney damage. It also diminished ROS levels in the kidney, enhanced the expression of endogenous antioxidant enzymes, and improved mitochondrial health. Phenyl sulfate (PS), a protein-bound uremic solute of enteric origin, has been closely linked with DN and represents a promising avenue for further research. In vitro, PS exposure induced OS and mitochondrial dysfunction in podocytes, increasing ROS levels while decreasing antioxidant enzyme activity (Catalase, Heme Oxygenase-1, Superoxide Dismutase, and Glutathione Peroxidase). ROS inhibitors (N-acetyl-L-cysteine, NAC) as the positive control group can significantly reduce the levels of ROS and restore antioxidant enzymes protein levels. Additionally, PS reduced markers associated with mitochondrial biosynthesis and function (SIRT1, PGC1α, Nrf1, and TFAM). These adverse effects were partially reversed by AS-IV treatment. However, co-treatment with AS-IV and the SIRT1 inhibitor EX527 failed to restore these indicators. Overall, our study demonstrates that AS-IV effectively attenuates DN and mitigates PS-induced OS and mitochondrial dysfunction in podocytes via the SIRT1/PGC1α/Nrf1 pathway.

Senolytic combination of dasatinib and quercetin attenuates renal damage in diabetic kidney disease

BACKGROUND

Senolytic combination of dasatinib and quercetin (DQ) is the most studied senolytics drugs used to treat various age-related diseases. However, its protective activity against diabetic kidney disease (DKD) and underlying mechanisms are uncertain.

PURPOSE

To investigate the functions and potential mechanisms of the senolytics DQ on DKD.

METHODS

Diabetic db/db mice were administrated DQ or transfected with over-expressed PPARα or shPPARα vector. The positive control group was administered irbesartan. Renal function and fibrotic changes in kidney tissue were tested. Single-cell RNA-seq (scRNA-seq) was conducted to analyze the differential transcriptome between the diabetic and control mice. Molecular docking simulation was used to assess the combination of DQ and potential factors. Moreover, tubular epithelial cells under high-glucose (HG) conditions were incubated with DQ and transfected with or without over-expressed PPARα/siPPARα vector.

RESULTS

DQ significantly improved renal function, histopathological and fibrotic changes, alleviated lipid deposition, and increased ATP levels in mice with DKD. DQ reduced multiple fatty acid oxidation (FAO) pathway-related proteins and up-regulated PPARα in db/db mice. Overexpression of PPARα upregulated the expression of PPARα-targeting downstream FAO pathway-related proteins, restored renal function, and inhibited renal fibrosis in vitro and in vivo. Moreover, molecular docking and dynamics simulation analyses indicated the nephroprotective effect of DQ via binding to PPARα. Knockdown of PPARα reversed the effect of DQ on the FAO pathway and impaired the protective effect of DQ during DKD.

CONCLUSION

For the first time, DQ was found to exert a renal protective effect by binding to PPARα and attenuating renal damage through the promotion of FAO in DKD.

PDZK1 protects against mechanical overload-induced chondrocyte senescence and osteoarthritis by targeting mitochondrial function

Mechanical overloading and aging are two essential factors for osteoarthritis (OA) development. Mitochondria have been identified as a mechano-transducer situated between extracellular mechanical signals and chondrocyte biology, but their roles and the associated mechanisms in mechanical stress-associated chondrocyte senescence and OA have not been elucidated. Herein, we found that PDZ domain containing 1 (PDZK1), one of the PDZ proteins, which belongs to the Na+/H+ Exchanger (NHE) regulatory factor family, is a key factor in biomechanically induced mitochondrial dysfunction and chondrocyte senescence during OA progression. PDZK1 is reduced by mechanical overload, and is diminished in the articular cartilage of OA patients, aged mice and OA mice. Pdzk1 knockout in chondrocytes exacerbates mechanical overload-induced cartilage degeneration, whereas intraarticular injection of adeno-associated virus-expressing PDZK1 had a therapeutic effect. Moreover, PDZK1 loss impaired chondrocyte mitochondrial function with accumulated damaged mitochondria, decreased mitochondrion DNA (mtDNA) content and increased reactive oxygen species (ROS) production. PDZK1 supplementation or mitoubiquinone (MitoQ) application alleviated chondrocyte senescence and cartilage degeneration and significantly protected chondrocyte mitochondrial functions. MRNA sequencing in articular cartilage from Pdzk1 knockout mice and controls showed that PDZK1 deficiency in chondrocytes interfered with mitochondrial function through inhibiting Hmgcs2 by increasing its ubiquitination. Our results suggested that PDZK1 deficiency plays a crucial role in mediating excessive mechanical load-induced chondrocyte senescence and is associated with mitochondrial dysfunction. PDZK1 overexpression or preservation of mitochondrial functions by MitoQ might present a new therapeutic approach for mechanical overload-induced OA.

JinChan YiShen TongLuo Formula ameliorate mitochondrial dysfunction and apoptosis in diabetic nephropathy through the HIF-1α-PINK1-Parkin pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The JinChan YiShen TongLuo (JCYSTL) formula, a traditional Chinese medicine (TCM), has been used clinically for decades to treat diabetic nephropathy (DN). TCM believes that the core pathogenesis of DN is "kidney deficiency and collateral obstruction," and JCYSTL has the effect of "tonifying kidney and clearing collateral," thus alleviating the damage to kidney structure and function caused by diabetes. From the perspective of modern medicine, mitochondrial damage is an important factor in DN pathogenesis. Our study suggests that the regulation of mitophagy and mitochondrial function by JCYSTL may be one of the internal mechanisms underlying its good clinical efficacy.

AIM OF THE STUDY

This study aimed to investigate the mechanisms underlying the renoprotective effects of JCYSTL.

MATERIALS AND METHODS

Unilateral nephrectomy combined with low-dose streptozotocin intraperitoneally injected in a DN rat model and high glucose (HG) plus hypoxia-induced HK-2 cells were used to explore the effects of JCYSTL on the HIF-1α/mitophagy pathway, mitochondrial function and apoptosis.

RESULTS

JCYSTL treatment significantly decreased albuminuria, serum creatinine, blood urea nitrogen, and uric acid levels and increased creatinine clearance levels in DN rats. In vitro, medicated serum containing JCYSTL formula increased mitochondrial membrane potential (MMP); improved activities of mitochondrial respiratory chain complexes I, III, and IV; decreased the apoptotic cell percentage and apoptotic protein Bax expression; and increased anti-apoptotic protein Bcl-2 expression in HG/hypoxia-induced HK-2 cells. The treatment group exhibited increased accumulation of PINK1, Parkin, and LC3-II and reduced P62 levels in HG/hypoxia-induced HK-2 cells, whereas in PINK1 knockdown HK-2 cells, JCYSTL did not improve the HG/hypoxia-induced changes in Parkin, LC3-II, and P62. When mitophagy was impaired by PINK1 knockdown, the inhibitory effect of JCYSTL on Bax and its promoting effect on MMP and Bcl-2 disappeared. The JCYSTL-treated group displayed significantly higher HIF-1α expression than the model group in vivo, which was comparable to the effects of FG-4592 in DN rats. PINK1 knockdown did not affect HIF-1α accumulation in JCYSTL-treated HK-2 cells exposed to HG/hypoxia. Both JCYSTL and FG-4592 ameliorated mitochondrial morphological abnormalities and reduced the mitochondrial respiratory chain complex activity in the renal tubules of DN rats. Mitochondrial apoptosis signals in DN rats, such as increased Bax and Caspase-3 expression and apoptosis ratio, were weakened by JCYSTL or FG-4592 administration.

CONCLUSION

This study demonstrates that the JCYSTL formula activates PINK1/Parkin-mediated mitophagy by stabilizing HIF-1α to protect renal tubules from mitochondrial dysfunction and apoptosis in diabetic conditions, presenting a promising therapy for the treatment of DN.

Diabetes and Renal Complications: An Overview on Pathophysiology, Biomarkers and Therapeutic Interventions

Diabetic kidney disease (DKD) is a major microvascular complication of both type 1 and type 2 diabetes. DKD is characterised by injury to both glomerular and tubular compartments, leading to kidney dysfunction over time. It is one of the most common causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Persistent high blood glucose levels can damage the small blood vessels in the kidneys, impairing their ability to filter waste and fluids from the blood effectively. Other factors like high blood pressure (hypertension), genetics, and lifestyle habits can also contribute to the development and progression of DKD. The key features of renal complications of diabetes include morphological and functional alterations to renal glomeruli and tubules leading to mesangial expansion, glomerulosclerosis, homogenous thickening of the glomerular basement membrane (GBM), albuminuria, tubulointerstitial fibrosis and progressive decline in renal function. In advanced stages, DKD may require treatments such as dialysis or kidney transplant to sustain life. Therefore, early detection and proactive management of diabetes and its complications are crucial in preventing DKD and preserving kidney function.

Serotonin regulation of mitochondria in kidney diseases

Serotonin, while conventionally recognized as a neurotransmitter in the CNS, has recently gained attention for its role in the kidney. Specifically, serotonin is not only synthesized in the kidney, but it also regulates glomerular function, vascular resistance, and mitochondrial homeostasis. Because of serotonin's importance to mitochondrial health, this review is focused on the role of serotonin and its receptors in mitochondrial function in the context of acute kidney injury, chronic kidney disease, and diabetic kidney disease, all of which are characterized by mitochondrial dysfunction and none of which has approved pharmacological treatments. Evidence indicates that activation of certain serotonin receptors can stimulate mitochondrial biogenesis (MB) and restore mitochondrial homeostasis, resulting in improved renal function. Serotonin receptor agonists that induce MB are therefore of interest as potential therapeutic strategies for renal injury and disease. SIGNIFICANCE STATEMENT: Mitochondrial dysfunction is associated with many human renal diseases such as acute kidney injury, chronic kidney disease, and diabetic kidney disease, which are associated with increased morbidity and mortality. Unfortunately, none of these pathologies has an FDA-approved pharmacological intervention, underscoring the urgency of identifying new therapeutics for such disorders. Studies show that induction of mitochondrial biogenesis via serotonin (5-hydroxytryptamine, 5-HT) receptors reduces kidney injury markers, restores mitochondrial and renal function after kidney injury, and decreases mortality, suggesting that targeting 5-HT receptors may be a promising therapeutic avenue for mitochondrial dysfunction in kidney diseases. While numerous reviews describe the importance of mitochondria and mitochondrial quality control mechanisms in kidney disease, the relevance of 5-HT receptor-mediated mitochondrial metabolic modulation in the kidney has yet to be thoroughly explored.

Oxidative Stress: A Culprit in the Progression of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the principal culprit behind chronic kidney disease (CKD), ultimately developing end-stage renal disease (ESRD) and necessitating costly dialysis or kidney transplantation. The limited therapeutic efficiency among individuals with DKD is a result of our finite understanding of its pathogenesis. DKD is the result of complex interactions between various factors. Oxidative stress is a fundamental factor that can establish a link between hyperglycemia and the vascular complications frequently encountered in diabetes, particularly DKD. It is crucial to recognize the essential and integral role of oxidative stress in the development of diabetic vascular complications, particularly DKD. Hyperglycemia is the primary culprit that can trigger an upsurge in the production of reactive oxygen species (ROS), ultimately sparking oxidative stress. The main endogenous sources of ROS include mitochondrial ROS production, NADPH oxidases (Nox), uncoupled endothelial nitric oxide synthase (eNOS), xanthine oxidase (XO), cytochrome P450 (CYP450), and lipoxygenase. Under persistent high glucose levels, immune cells, the complement system, advanced glycation end products (AGEs), protein kinase C (PKC), polyol pathway, and the hexosamine pathway are activated. Consequently, the oxidant-antioxidant balance within the body is disrupted, which triggers a series of reactions in various downstream pathways, including phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), transforming growth factor beta/p38-mitogen-activated protein kinase (TGF-β/p38-MAPK), nuclear factor kappa B (NF-κB), adenosine monophosphate-activated protein kinase (AMPK), and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling. The disease might persist even if strict glucose control is achieved, which can be attributed to epigenetic modifications. The treatment of DKD remains an unresolved issue. Therefore, reducing ROS is an intriguing therapeutic target. The clinical trials have shown that bardoxolone methyl, a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, blood glucose-lowering drugs, such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists can effectively slow down the progression of DKD by reducing oxidative stress. Other antioxidants, including vitamins, lipoic acid, Nox inhibitors, epigenetic regulators, and complement inhibitors, present a promising therapeutic option for the treatment of DKD. In this review, we conduct a thorough assessment of both preclinical studies and current findings from clinical studies that focus on targeted interventions aimed at manipulating these pathways. We aim to provide a comprehensive overview of the current state of research in this area and identify key areas for future exploration.

Metabolic disorders in prediabetes: From mechanisms to therapeutic management

Diabetes, one of the world's top ten diseases, is known for its high mortality and complication rates and low cure rate. Prediabetes precedes the onset of diabetes, during which effective treatment can reduce diabetes risk. Prediabetes risk factors include high-calorie and high-fat diets, sedentary lifestyles, and stress. Consequences may include considerable damage to vital organs, including the retina, liver, and kidneys. Interventions for treating prediabetes include a healthy lifestyle diet and pharmacological treatments. However, while these options are effective in the short term, they may fail due to the difficulty of long-term implementation. Medications may also be used to treat prediabetes. This review examines prediabetic treatments, particularly metformin, glucagon-like peptide-1 receptor agonists, sodium glucose cotransporter 2 inhibitors, vitamin D, and herbal medicines. Given the remarkable impact of prediabetes on the progression of diabetes mellitus, it is crucial to intervene promptly and effectively to regulate prediabetes. However, the current body of research on prediabetes is limited, and there is considerable confusion surrounding clinically relevant medications. This paper aims to provide a comprehensive summary of the pathogenesis of pre-diabetes mellitus and its associated therapeutic drugs. The ultimate goal is to facilitate the clinical utilization of medications and achieve efficient and timely control of diabetes mellitus.

NDUFS4 regulates cristae remodeling in diabetic kidney disease

The mitochondrial electron transport chain (ETC) is a highly adaptive process to meet metabolic demands of the cell, and its dysregulation has been associated with diverse clinical pathologies. However, the role and nature of impaired ETC in kidney diseases remains poorly understood. Here, we generate diabetic mice with podocyte-specific overexpression of Ndufs4, an accessory subunit of mitochondrial complex I, as a model investigate the role of ETC integrity in diabetic kidney disease (DKD). We find that conditional male mice with genetic overexpression of Ndufs4 exhibit significant improvements in cristae morphology, mitochondrial dynamics, and albuminuria. By coupling proximity labeling with super-resolution imaging, we also identify the role of cristae shaping protein STOML2 in linking NDUFS4 with improved cristae morphology. Together, we provide the evidence on the central role of NDUFS4 as a regulator of cristae remodeling and mitochondrial function in kidney podocytes. We propose that targeting NDUFS4 represents a promising approach to slow the progression of DKD.

The potential of therapeutic strategies targeting mitochondrial biogenesis for the treatment of insulin resistance and type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a persistent metabolic disorder marked by deficiencies in insulin secretion and/or function, affecting various tissues and organs and leading to numerous complications. Mitochondrial biogenesis, the process by which cells generate new mitochondria utilizing existing ones plays a crucial role in energy homeostasis, glucose metabolism, and lipid handling. Recent evidence suggests that promoting mitochondrial biogenesis can alleviate insulin resistance in the liver, adipose tissue, and skeletal muscle while improving pancreatic β-cell function. Moreover, enhanced mitochondrial biogenesis has been shown to ameliorate T2DM symptoms and may contribute to therapeutic effects for the treatment of diabetic nephropathy, cardiomyopathy, retinopathy, and neuropathy. This review summarizes the intricate connection between mitochondrial biogenesis and T2DM, highlighting the potential of novel therapeutic strategies targeting mitochondrial biogenesis for T2DM treatment and its associated complications. It also discusses several natural products that exhibit beneficial effects on T2DM by promoting mitochondrial biogenesis.

PGC1-α in diabetic kidney disease: unraveling renoprotection and molecular mechanisms

Mitochondrial dysfunction represents a pivotal aspect of the pathogenesis and progression of diabetic kidney disease (DKD). Central to the orchestration of mitochondrial biogenesis is the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1-α), a master regulator with a profound impact on mitochondrial function. In the context of DKD, PGC1-α exhibits significant downregulation within intrinsic renal cells, precipitating a cascade of deleterious events. This includes a reduction in mitochondrial biogenesis, heightened levels of mitochondrial oxidative stress, perturbed mitochondrial dynamics, and dysregulated mitophagy. Concurrently, structural and functional abnormalities within the mitochondrial network ensue. In stark contrast, the sustained expression of PGC1-α emerges as a beacon of hope in maintaining mitochondrial homeostasis within intrinsic renal cells, ultimately demonstrating an impressive renoprotective potential in animal models afflicted with DKD. This comprehensive review aims to delve into the recent advancements in our understanding of the renoprotective properties wielded by PGC1-α. Specifically, it elucidates the potential molecular mechanisms underlying PGC1-α's protective effects within renal tubular epithelial cells, podocytes, glomerular endothelial cells, and mesangial cells in the context of DKD. By shedding light on these intricate mechanisms, we aspire to provide valuable insights that may pave the way for innovative therapeutic interventions in the management of DKD.

Mitophagy regulates mitochondrial number following pharmacological induction of mitochondrial biogenesis in renal proximal tubule cells

Background: Mitochondrial biogenesis (MB) induction through the activation of the 5-Hydroxytriptamine (5-HT) 1F receptor (HTR1F) is a promising mechanism for the treatment of diseases characterized by mitochondrial dysfunction, such as acute kidney injury (AKI). While several studies report pharmacological activation of MB in the proximal tubule, it is unclear how the proximal tubule regulates itself once the pharmacological activation is removed. Mitophagy is the process of selective mitochondria degradation. We hypothesize that mitophagy decreases mitochondrial number after pharmacological stimulation and restore mitochondrial homeostasis. Methods: Renal proximal tubules were treated at time 0hr with LY344864 or vehicle for 24 h and then removed. LY344864, a selective HTR1F agonist, induces MB in renal proximal tubules as previously reported (Gibbs et al., Am J Physiol Renal Physiol, 2018, 314(2), F260-F268). Vehicle and pharmacological reagents were added at the 24 h time point. Electron microscopy was used to assess mitochondrial morphology, number, and autolysosomes. Seahorse Bioscience XF-96 extracellular flux analyzer was used to measure maximal mitochondrial oxygen consumption rates (FCCP-OCR), a functional marker of MB. Results: LY344864 treatment increased FCCP-OCR, phosphorylation of protein kinase B (AKT), peroxisome proliferator-activated receptor γ coactivator-1alpha (PGC-1α), and mitochondrial number after 24 h. These endpoints decreased to baseline 24 h after LY344864 removal. Treatment with ROC-325, an autophagy inhibitor, increased Sequestosome-1 (SQSTM1/P62) and microtubule-associated protein-1 light chain 3 (LC3B) after 24 h of treatment. Also, ROC-325 treatment sustained the elevated mitochondrial number after LY344864 pre-treatment and removal. Conclusion: These data revealed that inhibition of autophagy extends elevated mitochondrial number and function by preventing the lysosomal degradation of mitochondria after the removal of LY344864.

Association of systemic immune-inflammation index with diabetic kidney disease in patients with type 2 diabetes: a cross-sectional study in Chinese population

Objective

Systemic immune-inflammation index (SII), a novel inflammatory marker, has been reported to be associated with diabetic kidney disease (DKD) in the U.S., however, such a close relationship with DKD in other countries, including China, has not been never determined. We aimed to explore the association between SII and DKD in Chinese population.

Methods

A total of 1922 hospitalized patients with type 2 diabetes mellitus (T2DM) included in this cross-sectional study were divided into three groups based on estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR): non-DKD group, DKD stages 1-2 Alb group, and DKD-non-Alb+DKD stage 3 Alb group. The possible association of SII with DKD was investigated by correlation and multivariate logistic regression analysis, and receiver-operating characteristic (ROC) curves analysis.

Results

Moving from the non-DKD group to the DKD-non-Alb+DKD stage 3 Alb group, SII level was gradually increased (P for trend <0.01). Partial correlation analysis revealed that SII was positively associated with urinary ACR and prevalence of DKD, and negatively with eGFR (all P<0.01). Multivariate logistic regression analysis showed that SII remained independently significantly associated with the presence of DKD after adjustment for all confounding factors [(odds ratio (OR), 2.735; 95% confidence interval (CI), 1.840-4.063; P < 0.01)]. Moreover, compared with subjects in the lowest quartile of SII (Q1), the fully adjusted OR for presence of DKD was 1.060 (95% CI 0.773-1.455) in Q2, 1.167 (95% CI 0.995-1.368) in Q3, 1.266 (95% CI 1.129-1.420) in the highest quartile (Q4) (P for trend <0.01). Similar results were observed in presence of DKD stages 1-2 Alb or presence of DKD-non- Alb+DKD stage 3 Alb among SII quartiles. Last, the analysis of ROC curves revealed that the best cutoff values for SII to predict DKD, Alb DKD stages 1- 2, and DKD-non-Alb+ DKD stage 3 Alb were 609.85 (sensitivity: 48.3%; specificity: 72.8%), 601.71 (sensitivity: 43.9%; specificity: 72.3%), and 589.27 (sensitivity: 61.1%; specificity: 71.1%), respectively.

Conclusion

Higher SII is independently associated with an increased risk of the presence and severity of DKD, and SII might be a promising biomarker for DKD and its distinct phenotypes in Chinese population.

Modified Hu-lu-ba-wan protects diabetic glomerular podocytes via promoting PKM2-mediated mitochondrial dynamic homeostasis

BACKGROUND

Mitochondrial dysfunction is implicated in the progression of diabetic kidney disease (DKD). Damaged mitochondria produce excessive reactive oxygen species (ROS) that can cause apoptosis. Mitochondrial dynamics control the quality and function of mitochondria. Targeting mitochondrial dynamics may reduce ROS-induced apoptosis and improve renal injury in DKD. Modified Hu-lu-ba-wan (MHLBW) shows distinct clinical effects on DKD patients, which are related to its role in antioxidant stress modulation. However, the relevant mechanisms of MHLBW have not been clearly explored.

PURPOSE

This study was aimed to evaluate the therapeutic effects of MHLBW on spontaneous DKD mice and clarify the potential mechanisms.

METHODS

The main components of MHLBW were identified by HPLC. Using db/db mice as DKD models, we evaluated the therapeutic effects of MHLBW on mice after an 8-week administration. We investigated the molecular mechanism of MHLBW in regulating mitochondrial dynamic homeostasis, podocyte apoptosis, and glomerular damage. After that, computational docking analysis and in vitro experiments were conducted for further mechanism verification.

RESULTS

Intragastric administration of MHLBW for 8 weeks in db/db mice significantly improved glucose metabolism, basement membrane thickening, mesangial expansion, glomerular fibrosis, and podocyte injury. MHLBW can reverse podocyte apoptosis via promoting mitochondrial dynamic homeostasis, which was related to regulating the PKM2/ PGC-1α/Opa1 pathway. Berberine (BBR), one of the components of MHLBW, exhibited preeminent affinity with PKM2 as reflected by computational docking analysis. In cultured podocytes, BBR can also prevent apoptosis by promoting PKM2-mediated mitochondrial dynamic homeostasis.

CONCLUSION

Our study demonstrates that MHLBW can treat DKD by inhibiting glomerular damage and podocyte apoptosis through positive regulation of PKM2-mediated mitochondrial dynamic homeostasis. These results may provide a potential strategy against DKD.

Lasmiditan restores mitochondrial quality control mechanisms and accelerates renal recovery after ischemia-reperfusion injury

BACKGROUND

Mitochondrial dysfunction is a well-established result of acute kidney injury (AKI). Previously, we identified that 5-hydroxytryptamine 1F (5-HT1F) receptor agonism with lasmiditan induces mitochondrial biogenesis (MB) and improves renal vasculature and function in an AKI mouse model. We hypothesize that lasmiditan also modulates mitochondrial dynamics and mitophagy in a mouse model of AKI.

METHODS

Male mice were subjected to renal ischemia/reperfusion (I/R) and treated daily with lasmiditan (0.3 mg/kg) or vehicle beginning 24 h after injury for 3 or 6d. Serum creatinine was measured to estimate glomerular filtration. Electron microscopy was used to assess mitochondrial morphology and mitophagy. Mitochondrial-related protein were confirmed with immunoblotting. Mitochondrial function was assessed with ATP measurements.

RESULTS

Lasmiditan treatment improved mitochondrial and kidney recovery as early as 3d post-AKI, as evidenced by increased ATP, and decreased serum creatinine, respectively. Electron micrographs of renal cortices revealed that lasmiditan also decreased mitochondrial damage and increased mitochondrial area and size by 6d after I/R injury. Additionally, lasmiditan treatment increased mitolysosomes by 3d, indicating induction of mitophagy. Phosphorylation of mitophagy-related proteins were also increased in the renal cortices of lasmiditan-treated AKI mice 3d after I/R injury, whereas fusion-related proteins were increased at 6d after I/R injury.

CONCLUSION

These data reveal that lasmiditan accelerates renal recovery, restores normal mitochondrial membrane and cristae morphology, decreases excessive mitochondrial fission, and accelerates mitophagy post-AKI in a time-dependent manner, establishing mitochondrial function and recovery from AKI.

Therapeutic application of traditional Chinese medicine in kidney disease: Sirtuins as potential targets

Sirtuins are a family of NAD+ III-dependent histone deacetylases that consists of seven family members, Sirt1-Sirt7, which regulate various signalling pathways and are involved in many critical biological processes of kidney diseases. Traditional Chinese medicine (TCM), as an essential part of the global healthcare system, has multi-component and multi-pathway therapeutic characteristics and plays a role in preventing and controlling various diseases. Through ongoing collaboration with modern medicine, TCM has recently achieved many remarkable advancements in theoretical investigation, mechanistic research, and clinical applications related to kidney diseases. Therefore, a comprehensive and systematic summary of TCM that focuses on sirtuins as the intervention target for kidney diseases is necessary. This review introduces the relationship between abnormal sirtuins levels and common kidney diseases, such as diabetic kidney disease and acute kidney injury. Based on the standard biological processes, such as inflammation, oxidative stress, autophagy, mitochondrial homeostasis, and fibrosis, which are underlying kidney diseases, comprehensively describes the roles and regulatory effects of TCM targeting the sirtuins family in various kidney diseases.

Preventive Action of Beta-Carotene against the Indoxyl Sulfate-Induced Renal Dysfunction in Male Adult Zebrafish via Regulations of Mitochondrial Inflammatory and β-Carotene Oxygenase-2 Actions

Indoxyl sulfate (IS) is a metabolic byproduct of indole metabolism. IS readily interacts with the mitochondrial redox metabolism, leading to altered renal function. The β-carotene oxygenase-2 (BCO2) enzyme converts carotenoids to intermediate products. However, the role of β-carotene (BC) in IS-induced renal dysfunction in zebrafish and their modulatory action on BCO2 and mitochondrial inflammations have not been explored yet. Hence, the present study is designed to investigate the role of BC in the attenuation of IS-induced renal dysfunction via regulations of mitochondrial redox balance by BCO2 actions. Renal dysfunction was induced by exposure to IS (10 mg/L/hour/day) for 4 weeks. BC (50 and 100 mg/L/hour/day) and coenzyme Q10 (CoQ10; 20 mg/L/hour/day) were added before IS exposure. BC attenuated the IS-induced increase in blood urea nitrogen (BUN) and creatinine concentrations, adenosine triphosphate (ATP), and complex I activity levels, and the reduction of renal mitochondrial biomarkers, i.e., BCO2, superoxide dismutase-2 (SOD2), glutathione peroxidase-1 (GPX1), reduced and oxidized glutathione (GSH/GSSG) ratio, and carbonylated proteins. Moreover, renal histopathological changes were analyzed by the eosin and hematoxylin staining method. As a result, the administration of BC attenuated the IS-induced renal damage via the regulation of mitochondrial function.

Advances in the pharmacological study of Chinese herbal medicine to alleviate diabetic nephropathy by improving mitochondrial oxidative stress

Diabetic nephropathy (DN) is one of the serious complications of diabetes mellitus, primarily arising from type 2 diabetes (T2DM), and can progress to chronic kidney disease (CKD) and end stage renal disease (ESRD). The pathogenesis of DN involves various factors such as hemodynamic changes, oxidative stress, inflammatory response, and lipid metabolism disorders. Increasing attention is being given to DN caused by oxidative stress in the mitochondrial pathway, prompting researchers to explore drugs that can regulate these target pathways. Chinese herbal medicine, known for its accessibility, rich historical usage, and remarkable efficacy, has shown promise in ameliorating renal injury caused by DN by modulating oxidative stress in the mitochondrial pathway. This review aims to provide a reference for the prevention and treatment of DN. Firstly, we outline the mechanisms by which mitochondrial dysfunction impairs DN, focusing on outlining the damage to mitochondria by oxidative stress. Subsequently, we describe the process by which formulas, herbs and monomeric compounds protect the kidney by ameliorating oxidative stress in the mitochondrial pathway. Finally, the rich variety of Chinese herbal medicine, combined with modern extraction techniques, has great potential, and as we gradually understand the pathogenesis of DN and research techniques are constantly updated, there will be more and more promising therapeutic targets and herbal drug candidates. This paper aims to provide a reference for the prevention and treatment of DN.

Glucose-Lowering Effects of Imeglimin and Its Possible Beneficial Effects on Diabetic Complications

Mitochondrial dysfunction is a prominent pathological feature of type 2 diabetes, which contributes to β-cell mass reduction and insulin resistance. Imeglimin is a novel oral hypoglycemic agent with a unique mechanism of action targeting mitochondrial bioenergetics. Imeglimin reduces reactive oxygen species production, improves mitochondrial function and integrity, and also improves the structure and function of endoplasmic reticulum (ER), changes which enhance glucose-stimulated insulin secretion and inhibit the apoptosis of β-cells, leading to β-cell mass preservation. Further, imeglimin inhibits hepatic glucose production and ameliorates insulin sensitivity. Clinical trials into the effects of imeglimin monotherapy and combination therapy exhibited an excellent hypoglycemic efficacy and safety profile in type 2 diabetic patients. Mitochondrial impairment is closely associated with endothelial dysfunction, which is a very early event in atherosclerosis. Imeglimin improved endothelial dysfunction in patients with type 2 diabetes via both glycemic control-dependent and -independent mechanisms. In experimental animals, imeglimin improved cardiac and kidney function via an improvement in mitochondrial and ER function or/and an improvement in endothelial function. Furthermore, imeglimin reduced ischemia-induced brain damage. In addition to glucose-lowering effects, imeglimin can be a useful therapeutic option for diabetic complications in type 2 diabetic patients.

Renal-Protective Roles of Lipoic Acid in Kidney Disease

The kidney is a crucial organ that eliminates metabolic waste and reabsorbs nutritious elements. It also participates in the regulation of blood pressure, maintenance of electrolyte balance and blood pH homeostasis, as well as erythropoiesis and vitamin D maturation. Due to such a heavy workload, the kidney is an energy-demanding organ and is constantly exposed to endogenous and exogenous insults, leading to the development of either acute kidney injury (AKI) or chronic kidney disease (CKD). Nevertheless, there are no therapeutic managements to treat AKI or CKD effectively. Therefore, novel therapeutic approaches for fighting kidney injury are urgently needed. This review article discusses the role of α-lipoic acid (ALA) in preventing and treating kidney diseases. We focus on various animal models of kidney injury by which the underlying renoprotective mechanisms of ALA have been unraveled. The animal models covered include diabetic nephropathy, sepsis-induced kidney injury, renal ischemic injury, unilateral ureteral obstruction, and kidney injuries induced by folic acid and metals such as cisplatin, cadmium, and iron. We highlight the common mechanisms of ALA’s renal protective actions that include decreasing oxidative damage, increasing antioxidant capacities, counteracting inflammation, mitigating renal fibrosis, and attenuating nephron cell death. It is by these mechanisms that ALA achieves its biological function of alleviating kidney injury and improving kidney function. Nevertheless, we also point out that more comprehensive, preclinical, and clinical studies will be needed to make ALA a better therapeutic agent for targeting kidney disorders.

Oxidative stress as a culprit in diabetic kidney disease

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease (ESRD), and the prevalence of DKD has increased worldwide during recent years. DKD is associated with poor therapeutic outcomes in most patients, but there is limited understanding of its pathogenesis. This review suggests that oxidative stress interacts with many other factors in causing DKD. Highly active mitochondria and NAD(P)H oxidase are major sources of oxidants, and they significantly affect the risk for DKD. Oxidative stress and inflammation may be considered reciprocal causes of DKD, in that each is a cause and an effect of DKD. Reactive oxygen species (ROS) can act as second messengers in various signaling pathways and as regulators of metabolism, activation, proliferation, differentiation, and apoptosis of immune cells. Epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs can modulate oxidative stress. The development of new technologies and identification of new epigenetic mechanisms may provide novel opportunities for the diagnosis and treatment of DKD. Clinical trials demonstrated that novel therapies which reduce oxidative stress can slow the progression of DKD. These therapies include the NRF2 activator bardoxolone methyl, new blood glucose-lowering drugs such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists. Future studies should focus on improving early diagnosis and the development of more effective combination treatments for this multifactorial disease.

The Role of Ketone Bodies in Various Animal Models of Kidney Disease

The kidney is a vital organ that carries out significant metabolic functions in our body. Due to the complexity of its role, the kidney is also susceptible to many disease conditions, such as acute kidney injury (AKI) and chronic kidney disease (CKD). Despite the prevalence and our increased understanding of the pathophysiology of both AKI and CKD as well as the transition of AKI to CKD, no well-established therapeutics have been applied clinically to these conditions, rendering an urgent need for a novel potential therapeutic target to be developed. In this article, we reviewed the function of ketone bodies in some common kidney conditions, such as drug-induced nephrotoxicity, ischemia and reperfusion injury, fibrosis development, diabetic kidney disease, kidney aging, hypertension, and CKD progression. All the selected studies reviewed were performed in animal models by primarily utilizing rodents, which also provide invaluable sources for future clinical applications. Ketone bodies have shown significant renal protective properties via attenuation of oxidative stress, increased expression of anti-inflammatory proteins, gene regulation, and a reduction of apoptosis of renal cells. A physiological level of ketone bodies could be achieved by fasting, a ketogenic diet, and an exogenous ketone supplement. Finally, the limitations of the long-term ketogenic diet were also discussed.