Diabetes aggravates renal ischemia-reperfusion injury by repressing mitochondrial function and PINK1/Parkin-mediated mitophagy

Salvianolic acid B improves diabetic skin wound repair through Pink1/Parkin-mediated mitophagy

Diabetic skin wound is a disturbing and rapidly evolving clinical issue. Here, we investigated how salvianolic acid B (Sal B) affected the diabetic wound healing process. Following Sal B administration, histopathological damage was investigated by H&E and Masson staining, and CD34, apoptosis and mitophagy markers were measured by immunofluorescence, immunohistochemistry, and western blotting. Migration, proliferation, and mitochondrial function of high glucose (HG) -induced HMEC-1 cells were measured. The effects of si-Parkin on endothelial cell migration, apoptosis and mitochondrial autophagy were examined. Sal B alleviated inflammatory cell infiltration and promoted angiogenesis in skin wound tissue. Apoptosis and mitophagy were ameliorated by Sal B in diabetic skin wound tissues and HG-induced HMEC-1 cells. Parkin inhibition impaired the migratorypromoted cell apoptosis and inhibited mitophagy of HMEC-1 cells. This finding demonstrated that Sal B promoted diabetic skin wound repair via Pink1/Parkin-mediated mitophagy, improved our understanding of the diabetic wound healing process.

Microbial metabolite sodium butyrate enhances the anti-tumor efficacy of 5-fluorouracil against colorectal cancer by modulating PINK1/Parkin signaling and intestinal flora

Colorectal cancer (CRC) is a prevalent global health issue, with 5-fluorouracil (5-FU) being a commonly used chemotherapeutic agent for its treatment. However, the efficacy of 5-FU is often hindered by drug tolerance. Sodium butyrate (NaB), a derivative of intestinal flora, has demonstrated anti-cancer properties both in vitro and in vivo through pro-apoptotic effects and has shown promise in improving outcomes when used in conjunction with traditional chemotherapy agents. This study seeks to evaluate the impact and potential mechanisms of NaB in combination with 5-FU on CRC. We employed a comprehensive set of assays, including CCK-8, EdU staining, Hoechst 33258 staining, flow cytometry, ROS assay, MMP assay, immunofluorescence, and mitophagy assay, to detect the effect of NaB on the biological function of CRC cells in vitro. Western blotting and immunohistochemistry were used to verify the above experimental results. The xenograft tumor model was established to evaluate the in vivo anti-CRC activity of NaB. Subsequently, 16S rRNA gene sequencing was used to analyze the intestinal flora. The findings of our study demonstrate that sodium butyrate (NaB) exerts inhibitory effects on tumor cell proliferation and promotes tumor cell apoptosis in vitro, while also impeding tumor progression in vivo through the enhancement of the mitophagy pathway. Furthermore, the combined treatment of NaB and 5-fluorouracil (5-FU) yielded superior therapeutic outcomes compared to monotherapy with either agent. Moreover, this combination therapy resulted in the specific enrichment of Bacteroides, LigiLactobacillus, butyric acid-producing bacteria, and acetic acid-producing bacteria in the intestinal microbiota. The improvement in the intestinal microbiota contributed to enhanced therapeutic outcomes and reduced the adverse effects of 5-FU. Taken together, these findings indicate that NaB, a histone acetylation inhibitor synthesized through intestinal flora fermentation, has the potential to significantly enhance the therapeutic efficacy of 5-FU in CRC treatment and improve the prognosis of CRC patients.

Chinese botanical drugs targeting mitophagy to alleviate diabetic kidney disease, a comprehensive review

Diabetic kidney disease (DKD) is one of the chronic microvascular complications caused by diabetes, which is characterized by persistent albuminuria and/or progressive decline of estimated glomerular filtration rate (eGFR), and has been the major cause of dialysis around the world. At present, although the treatments for DKD including lifestyle modification, glycemic control and even using of Sodium-glucose cotransporter 2 (SGLT2) inhibitors can relieve kidney damage caused to a certain extent, there is still a lack of effective treatment schemes that can prevent DKD progressing to ESRD. It is urgent to find new complementary and effective therapeutic agents. Growing animal researches have shown that mitophagy makes a great difference to the pathogenesis of DKD, therefore, exploration of new drugs that target the restoration of mitophagy maybe a potential perspective treatment for DKD. The use of Chinese botanical drugs (CBD) has been identified to be an effective treatment option for DKD. There is growing concern on the molecular mechanism of CBD for treatment of DKD by regulating mitophagy. In this review, we highlight the current findings regarding the function of mitophagy in the pathological damages and progression of DKD and summarize the contributions of CBD that ameliorate renal injuries in DKD by interfering with mitophagy, which will help us further explain the mechanism of CBD in treatment for DKD and explore potential therapeutic strategies for DKD.

Protection of Ndrg2 deficiency on renal ischemia-reperfusion injury via activating PINK1/Parkin-mediated mitophagy

BACKGROUND

Renal ischemia-reperfusion (R-I/R) injury is the most prevalent cause of acute kidney injury, with high mortality and poor prognosis. However, the underlying pathological mechanisms are not yet fully understood. Therefore, this study aimed to investigate the role of N-myc downstream-regulated gene 2 (Ndrg2) in R-I/R injury.

METHODS

We examined the expression of Ndrg2 in the kidney under normal physiological conditions and after R-I/R injury by immunofluorescence staining, real-time polymerase chain reaction, and western blotting. We then detected R-I/R injury in Ndrg2-deficient (Ndrg2-/-) mice and wild type (Ndrg2+/+) littermates in vivo, and detected oxygen and glucose deprivation and reperfusion injury (OGD-R) in HK-2 cells. We further conducted transcriptomic sequencing to investigate the role of Ndrg2 in R-I/R injury and detected levels of oxidative stress and mitochondrial damage by dihydroethidium staining, biochemical assays, and western blot. Finally, we measured the levels of mitophagy in Ndrg2+/+ and Ndrg2-/- mice after R-I/R injury or HK-2 cells in OGD-R injury.

RESULTS

We found that Ndrg2 was primarily expressed in renal proximal tubules and significantly decreased its expression 24 h after R-I/R injury. Ndrg2-/- mice exhibited significantly attenuated R-I/R injury compared to Ndrg2+/+ mice. Transcriptomics profiling showed that Ndrg2 deficiency induced perturbations of multiple signaling pathways, downregulated inflammatory responses and oxidative stress, and increased autophagy following R-I/R injury. Further studies revealed that Ndrg2 deficiency reduced oxidative stress and mitochondrial damage. Notably, Ndrg2 deficiency significantly activated phosphatase and tensin homologue on chromosome ten-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy. The downregulation of NDRG2 expression significantly increased cell viability after OGD-R injury, increased the expression of heme oxygenase-1, decreased the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, and increased the expression of the PINK1/Parkin pathway.

CONCLUSION

Ndrg2 deficiency might become a therapy target for R-I/R injury by decreasing oxidative stress, maintaining mitochondrial homeostasis, and activating PINK1/Parkin-mediated mitophagy.

Renoprotective effect of esculetin against ischemic acute kidney injury-diabetic comorbidity

Mitophagy maintains cellular homeostasis by eliminating damaged mitochondria. Accumulated damaged mitochondria can lead to oxidative stress and cell death. Induction of the PINK1/Parkin-mediated mitophagy is reported to be renoprotective in acute kidney injury (AKI). Esculetin, a naturally available coumarin, has shown protective action against diabetic complications. However, its effect on AKI-diabetes comorbidity has not been explored yet. Therefore, we aimed to investigate the renoprotective effect of esculetin against AKI under diabetic conditions via regulating PINK1/Parkin-mediated mitophagy. For this, type 1 diabetic male Wistar rats were treated with two doses of esculetin (50 and 100 mg/kg/day orally) for five days followed by AKI induction by bilateral ischemic-reperfusion injury (IRI). NRK-52E cells grown in high glucose were exposed to sodium azide (10 mM) for induction of hypoxia/reperfusion injury (HRI) in-vitro. Esculetin (50 µM) treatment for 24 h was given to the cells before HRI. The in-vitro samples were utilized for cell viability and ΔΨm assay, immunoblotting, and immunofluorescence. Rats' plasma, urine, and kidney samples were collected for biochemical analysis, histopathology, and western blotting. Our results showed a significant decrease in kidney injury-specific markers and increased expression of mitophagy markers (PINK1 and Parkin) with esculetin treatment. Moreover, esculetin prevented the HRI and hyperglycemia-induced decrease in ΔΨm and autophagosome marker. Also, esculetin therapy reduced oxidative stress via increased Nrf2 and Keap1 expression. Esculetin attenuated AKI under diabetic condition by preventing mitochondrial dysfunction via inducing PINK1/Parkin-mediated mitophagy, suggesting its potential as an effective therapy for preventing AKI-diabetes comorbidity.

SGLT2 inhibitors, intrarenal hypoxia and the diabetic kidney: insights into pathophysiological concepts and current evidence

Approximately 20-40% of all diabetic patients experience chronic kidney disease, which is related to higher mortality (cardiovascular and all-cause). A large body of evidence suggests that renal hypoxia is one of the main forces that drives diabetic kidney disease, both in its early and advanced stages. It promotes inflammation, generation of intrarenal collagen, capillary rarefaction and eventually accumulation of extracellular matrix that destroys normal renal architecture. SGLT2 inhibitors are unquestionably a practice-changing drug class and a valuable weapon for patients with type 2 diabetes and chronic kidney disease. They have achieved several beneficial kidney effects after targeting multiple and interrelated signaling pathways, including renal hypoxia, independent of their antihyperglycemic activities. This manuscript discusses the pathophysiological concepts that underly their possible effects on modulating renal hypoxia. It also comprehensively investigates both preclinical and clinical studies that explored the possible role of SGLT2 inhibitors in this setting, so as to achieve long-term renoprotective benefits.

Phloretin as an add-on therapy to losartan attenuates diabetes-induced AKI in rats: A potential therapeutic approach targeting TLR4-induced inflammation

AIM

Targeting Toll-like receptor 4 (TLR4) and Angiotensin II type 1 receptor (AT1R) could provide renoprotection during acute kidney injury (AKI) mainly by regulating inflammation, oxidative stress, mitochondrial dysfunction, and apoptosis. Phloretin (TLR4 inhibitor) as an add-on therapy to losartan (AT1R inhibitor) could provide more therapeutic benefits against AKI under diabetic condition. We aimed to study the effect of phloretin as an add-on therapy to losartan against AKI under diabetic condition.

MAIN METHODS

To mimic diabetic AKI condition, bilateral ischemia-reperfusion injury (BIRI) was done in diabetic male Wistar rats, and sodium azide treatment was given to high glucose NRK52E cells to mimic hypoxia-reperfusion injury. In diabetic rats, phloretin (50 mg/kg/per os (p.o.)) and losartan (10 mg/kg/p.o.) treatment was given for 4 days and 1 h prior to surgery while in NRK52E cells, both drugs (phloretin 50 μM and losartan 10 μM) were given 24 h prior to the hypoxia condition. The in vivo and in vitro samples were further used for different experiments.

KEY FINDINGS

Treatment with phloretin and losartan decreased diabetic and AKI biomarkers such as plasma creatinine, blood urea nitrogen (BUN), and kidney injury molecular 1 (KIM1). Moreover, a combination of phloretin and losartan significantly preserved ΔΨm and kidney morphology potentially by inhibiting TLR4-associated inflammation and AT1R-associated mitochondrial dysfunction, thereby oxidative stress.

SIGNIFICANCE

Combination therapy of phloretin and losartan was more effective than monotherapies. Both drugs target TLR4/MyD88/NF-κB pathway and reduce inflammation and mitochondrial dysfunction in AKI under diabetic condition.

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.

Redefining Autoimmune Disorders' Pathoetiology: Implications for Mood and Psychotic Disorders' Association with Neurodegenerative and Classical Autoimmune Disorders

Although previously restricted to a limited number of medical conditions, there is a growing appreciation that 'autoimmune' (or immune-mediated) processes are important aspects of a wide array of diverse medical conditions, including cancers, neurodegenerative diseases and psychiatric disorders. All of these classes of medical conditions are associated with alterations in mitochondrial function across an array of diverse cell types. Accumulating data indicate the presence of the mitochondrial melatonergic pathway in possibly all body cells, with important consequences for pathways crucial in driving CD8⁺ T cell and B-cell 'autoimmune'-linked processes. Melatonin suppression coupled with the upregulation of oxidative stress suppress PTEN-induced kinase 1 (PINK1)/parkin-driven mitophagy, raising the levels of the major histocompatibility complex (MHC)-1, which underpins the chemoattraction of CD8⁺ T cells and the activation of antibody-producing B-cells. Many factors and processes closely associated with autoimmunity, including gut microbiome/permeability, circadian rhythms, aging, the aryl hydrocarbon receptor, brain-derived neurotrophic factor (BDNF) and its receptor tyrosine receptor kinase B (TrkB) all interact with the mitochondrial melatonergic pathway. A number of future research directions and novel treatment implications are indicated for this wide collection of poorly conceptualized and treated medical presentations. It is proposed that the etiology of many 'autoimmune'/'immune-mediated' disorders should be conceptualized as significantly determined by mitochondrial dysregulation, with alterations in the mitochondrial melatonergic pathway being an important aspect of these pathoetiologies.

Increased oxidative stress caused by impaired mitophagy aggravated liver ischemia and reperfusion injury in diabetic mice

AIMS/INTRODUCTION

Emerging evidence has suggested the detrimental role of oxidative stress in aggravating ischemia and reperfusion (IR) injury in diabetic livers. Interplay between oxidative stress and mitophagy has been shown. However, the role and mechanism of mitophagy in regulating oxidative stress and IR injury in diabetic livers remain unclear.

MATERIALS AND METHODS

Wild-type and db/db (DB) mice were subjected to a partial warm liver IR model. Liver injury, oxidative stress, mitophagy and related molecular pathways were analyzed.

RESULTS

Here, we found that increased liver IR injury was observed in DB mice, as evidenced by higher levels of serum alanine aminotransferase and serum aspartate, worsened liver architecture damage and more hepatocellular death. DB mice also showed increased mitochondrial oxidative stress. Mitochondrial reactive oxygen species scavenge alleviated liver IR injury in DB mice. Mechanistic analysis showed that 5' adenosine monophosphate-activated protein kinase-mediated mitophagy was suppressed in DB mice post-IR. Pharmacological activation of 5' adenosine monophosphate-activated protein kinase by its agonist effectively restored mitophagy activation, leading to decreased mitochondrial oxidative stress and attenuated liver IR injury in DB mice.

CONCLUSIONS

Our findings showed that diabetes increased oxidative stress to exacerbate liver IR injury by impairing 5' adenosine monophosphate-activated protein kinase-mediated mitophagy. Strategies targeting oxidative stress and mitophagy might provide a promising approach to ameliorate liver IR injury in diabetes patients.

Polyethylene glycol capped gold nanoparticles ameliorate renal ischemia-reperfusion injury in diabetic mice through AMPK-Nrf2 signaling pathway

The aim of this study is to investigate the protective effect of polyethylene glycol capped gold nanoparticles (PEG-AuNPs) on renal ischemia-reperfusion injury (I/R)-induced acute kidney injury (AKI) in diabetic mice via the activation of adenosine 5' monophosphate-activated protein kinase-nuclear factor erythroid-2-related factor-2 (AMPK-Nrf2) pathway. Diabetes was induced in male mice (12/group) by streptozotocin (50 mg/kg) for 5 consecutive days. After 4 weeks, the mice have intravenously received doses of PEG-AuNPs (40, 150, and 400 µg/kg body weight) for 3 consecutive days, and then animals were subjected to 30 min ischemia and 48 h reperfusion. Following the treatment with three different doses of PEG-AuNPs, the levels of blood urea nitrogen (BUN) and creatinine were reduced. Obvious reduction in renal tubular atrophy, glomerular damage, mitochondrial damage, and necrotic area were ultra-structurally detected, and renal interstitial inflammation and apoptosis were diminished. Moreover, PEG-AuNPs increased the recovering of damaged renal cells, suppressed significantly levels of malondialdehyde (MDA), downregulated significantly the level of inflammatory cytokines (TNF-α and IL-1β), and upregulated the AMPK-Nrf2 pathway. PEG-AuNPs exhibited a promising alternative therapeutic target for diabetic renal I/R-induced AKI through upregulation of AMPK/PI3K/AKT path which additionally stimulated Nrf2-regulated antioxidant enzymes in a dose-dependent manner.

Interval training and Crataegus persica ameliorate diabetic nephropathy via miR-126/Nrf-2 mediated inhibition of stress oxidative in rats with diabetes after myocardial ischemia-reperfusion injury

Myocardial disorders are the most common cause of renal failure and mortality in diabetic patients, but the molecular mechanism of this process is not yet clear. The reduction of nuclear Erythroid2-related factor-2 (Nrf-2) and positive regulators of Nrf-2 proteins, such as DJ-1 and microRNA-126 (miR-126), after hypoxia and the promotion of reactive oxygen species, might be an intervention indicator in renal failure after myocardial ischemia-reperfusion. Therefore, this study evaluates the renoprotective effect of exercise training and Crataegus persica extract (CE) on myocardial ischemia-reperfusion-induced kidney injury in diabetic rats. Fifty rats were divided into five groups: healthy sedentary control (Con), sedentary diabetic (D), interval trained diabetic (TD), diabetic plus Crataegus persica extract treatment (CD), and interval trained diabetic plus Crataegus persica extract treatment (TCD) groups. The rats in the exercise groups were subjected to moderate-intensity interval training five days per week for ten weeks. The rats in CD and TCD groups received 300 mg/kg of Crataegus persica through gavage for ten weeks. Then, the subjects underwent 30 min of myocardial ischemia and subsequently reperfusion for 24 h. At the end of the experiment, insulin sensitivity, oxidative stress, renal function, histopathology of the kidney, Nrf-2, miR-126, and DJ-1 gene expression levels were evaluated. The results show that the treatments decreased elevated levels of renal oxidative stress, glomerular filtration rate, insulin sensitivity, and pathological score in diabetic rats. Also, the expression of Nrf-2 and miR-126, unlike DJ-1, decreased in diabetic rats due to interval training. Due to the results, diabetes aggravates acute myocardial ischemia-reperfusion-induced kidney injury, while moderate-intensity interval training and Crataegus persica treatment simultaneously ameliorate myocardial ischemia-reperfusion-induced renal injury via miR-126/Nrf-2 pathway and improve insulin sensitivity and renal function in type 1 diabetic rats.

Mitochondrial dysfunction in diabetic tubulopathy

Diabetic kidney disease (DKD) is a devastating microvascular complication associated with diabetes mellitus. Recently, the major focus of glomerular lesions of DKD has partly shifted to diabetic tubulopathy because of renal insufficiency and prognosis of patients is closely related to tubular atrophy and interstitial fibrosis. Indeed, the proximal tubule enriching in mitochondria for its high energy demand and dependence on aerobic metabolism has given us pause to focus primarily on the mitochondria-centric view of early diabetic tubulopathy. Multiple studies suggest that diabetes condition directly damages renal tubules, resulting in mitochondria dysfunction, including decreased bioenergetics, overproduction of mitochondrial reactive oxygen species (mtROSs), defective mitophagy and dynamics disturbances, which in turn trigger a series of metabolic abnormalities. However, the precise mechanism underlying mitochondrial dysfunction of renal tubules is still in its infancy. Understanding tubulointerstitial's pathobiology would facilitate the search for new biomarkers of DKD. In this Review, we summarize the current literature and postulate that the potential effects of mitochondrial dysfunction may accelerate initiation of early-stage diabetic tubulopathy, as well as their potential therapeutic strategies.

PINK1/Parkin-mediated mitophagy mitigates T-2 toxin-induced nephrotoxicity

T-2 toxin can cause mitochondrial impairment and subsequent renal damage. PINK1/Parkin-mediated mitophagy can mitigate renal impairment by alleviating mitochondrial damage. Nevertheless, the impact of PINK1/Parkin-mediated mitophagy in T-2 toxin-induced renal injury remains unclear. Here, we studied the role of PINK1/Parkin-mediated mitophagy in T-2 toxin-induced nephrotoxicity. Mitochondrial damage was accompanied by NLRP3-inflammasome activation and PINK1/Parkin-mediated mitophagy in the kidney of T-2 toxin-exposed C57BL/6N mice. Knocking out Parkin inhibited the mitophagy but aggravated the structural and functional damage, NLRP3-inflammasome activation, mitochondrial damage, and apoptosis. Correlation analysis revealed that NLRP3-inflammasome activation was correlated with apoptosis. These results show that PINK1/Parkin-mediated mitophagy mitigates T-2 toxin-induced nephrotoxicity.

Propofol Reduces Renal Ischemia Reperfusion-mediated Necroptosis by Up-regulation of SIRT1 in Rats

Propofol (Pro) is well known to regulate the asleep-awake-asleep technique. Increasing indication recommends that Pro also has promising properties such as anti-oxidant and anti-inflammation belongings in several disease models. It has been described that Pro has beneficial properties against renal ischemia/reperfusion (rI/R)-mediated acute lung injury (ALI). Nevertheless, pathogenesis underlying the beneficial action of Pro on the remote ALI mediated by rI/R remains unwell unstated. In this research, we displayed that Pro administration remarkably inhibits rI/R-mediated pro-inflammatory cytokines production. Increased levels of oxidative stress were mainly decreased by Pro. Pro administration ameliorated apoptosis-related caspase-3 activation. Furthermore, the levels of crucial necroptosis-associated protein were reduced by Pro. Sirtuin 1 (SIRT1) inhibitor attenuated the aforementioned changes of Pro. In conclusion, these results propose that Pro attenuates rI/R-induced inflammation, oxidative stress, apoptosis, and necroptosis by up-regulation of SIRT1 in rats. Our findings disclose an original pathogenesis underlying the beneficial effect of Pro against rI/R-mediated ALI and reinforce the knowledge that Pro might be a hopeful beneficial agent for the rI/R-mediated ALI.

PINK1/Parkin-mediated mitophagy is activated to protect against AFB1-induced kidney damage in mice

Aflatoxin B₁ (AFB₁) is a toxic food pollutant that has extensive deleterious impacts on the kidney. Oxidative stress represents the primary mechanism of AFB₁ nephrotoxicity and can also cause mitochondrial damage. Damaged mitochondria can trigger apoptosis leading to kidney injury. PINK1/Parkin-mediated mitophagy can alleviate mitochondrial injury to maintain cellular homeostasis, however, its role in AFB₁-induced kidney damage is unknown. To investigate the effect of PINK1/Parkin-mediated mitophagy on kidney impairment triggered by AFB₁, 40 male wild-type (WT) C57BL/6N mice were first assigned to 4 groups and orally exposed to AFB₁ at 0, 0.5, 0.75, and 1 mg/kg body weight (BW) for 28 days. The results revealed that AFB₁ induced kidney damage, oxidative stress, mitochondrial damage, apoptosis and activated PINK1/Parkin-mediated mitophagy with a dose-dependent effect. Then, 20 male WT C57BL/6N mice and 20 male Parkin knockout (Parkin^-/-) C57BL/6N mice were assigned to 4 groups and orally exposed to AFB₁ at 0, 1, 0, and 1 mg/kg BW for 28 days. The results revealed that Parkin^-/- suppressed mitophagy and exacerbated kidney damage, oxidative stress, mitochondrial damage, and apoptosis under AFB₁ exposure. The aforementioned evidences demonstrate that PINK1/Parkin-mediated mitophagy is activated by AFB₁ and protects against kidney damage in mice.

Identification of ULK1 as a novel mitophagy-related gene in diabetic nephropathy

BACKGROUND

Accumulating evidence indicates that mitophagy is crucial for the development of diabetic nephropathy (DN). However, little is known about the key genes involved. The present study is to identify the potential mitophagy-related genes (MRGs) in DN.

METHODS

Five datasets were obtained from the Gene Expression Omnibus (GEO) database and were split into the training and validation set. Then the differentially expressed MRGs were screened and further analyzed for GO and KEGG enrichment. Next, three algorithms (SVM-RFE, LASSO and RF) were used to identify hub genes. The ROC curves were plotted based on the hub genes. We then used the CIBERSORT algorithm to assess the infiltration of 22 types of immune cells and explore the correlation between hub genes and immune cells. Finally, the Nephroseq V5 tool was used to analyze the correlation between hub genes and GFR in DN patients.

RESULTS

Compared with the tubulointerstitium, the expression of MRGs was more noticeably varied in the glomeruli. Twelve DE-MRGs were identified in glomerular samples, of which 11 genes were down-regulated and only MFN1 was up-regulated. GO and KEGG analysis indicated that several enrichment terms were associated with changes in autophagy. Three genes (MFN1, ULK1 and PARK2) were finally determined as potential hub genes by three algorithms. In the training set, the AUROC of MFN1, ULK1 and PARK2 were 0.839, 0.906 and 0.842. However, the results of the validation set demonstrated that MFN1 and PARK2 had no significant difference in distinguishing DN samples from healthy controls, while the AUROC of ULK1 was 0.894. Immune infiltration analysis using CIBERSORT showed that ULK1 was positively related to neutrophils, whereas negatively related to M1 and M2 macrophages. Finally, ULK1 was positively correlated with GFR in Nephroseq database.

CONCLUSIONS

ULK1 is a potential biomarker for DN and may influence the development of diabetic nephropathy by regulating mitophagy.

Mitochondrial Regulation of Diabetic Kidney Disease

The role and nature of mitochondrial dysfunction in diabetic kidney disease (DKD) has been extensively studied. Yet, the molecular drivers of mitochondrial remodeling in DKD are poorly understood. Diabetic kidney cells exhibit a cascade of mitochondrial dysfunction ranging from changes in mitochondrial morphology to significant alterations in mitochondrial biogenesis, biosynthetic, bioenergetics and production of reactive oxygen species (ROS). How these changes individually or in aggregate contribute to progression of DKD remain to be fully elucidated. Nevertheless, because of the remarkable progress in our basic understanding of the role of mitochondrial biology and its dysfunction in DKD, there is great excitement on future targeted therapies based on improving mitochondrial function in DKD. This review will highlight the latest advances in understanding the nature of mitochondria dysfunction and its role in progression of DKD, and the development of mitochondrial targets that could be potentially used to prevent its progression.

The impact of Traditional Chinese Medicine on mitophagy in disease models

Mitophagy plays an important role in maintaining mitochondrial quality and cell homeostasis through the degradation of damaged, aged, and dysfunctional mitochondria and misfolded proteins. Many human diseases, particularly neurodegenerative diseases, are related to disorders of mitochondrial phagocytosis. Exploring the regulatory mechanisms of mitophagy is of great significance for revealing the molecular mechanisms underlying the related diseases. Herein, we summarize the major mechanisms of mitophagy, the relationship of mitophagy with human diseases, and the role of traditional Chinese medicine (TCM) in mitophagy. These discussions enhance our knowledge of mitophagy and its potential therapeutic targets using TCM.

Mitochondrial dysfunction and beneficial effects of mitochondria-targeted small peptide SS-31 in Diabetes Mellitus and Alzheimer's disease

Diabetes and Alzheimer's disease are common chronic illnesses in the United States and lack clearly demonstrated therapeutics. Mitochondria, the "powerhouse of the cell", is involved in the homeostatic regulation of glucose, energy, and reduction/oxidation reactions. The mitochondria has been associated with the etiology of metabolic and neurological disorders through a dysfunction of regulation of reactive oxygen species. Mitochondria-targeted chemicals, such as the Szeto-Schiller-31 peptide, have advanced therapeutic potential through the inhibition of oxidative stress and the restoration of normal mitochondrial function as compared to traditional antioxidants, such as vitamin E. In this article, we summarize the pathophysiological relevance of the mitochondria and the beneficial effects of Szeto-Schiller-31 peptide in the treatment of Diabetes and Alzheimer's disease.

Penicilliumin B Protects against Cisplatin-Induced Renal Tubular Cell Apoptosis through Activation of AMPK-Induced Autophagy and Mitochondrial Biogenesis

INTRODUCTION

Acute kidney injury (AKI) is at a high prevalence in hospitalized patients, especially in those receiving chemotherapy. Cisplatin is the most widely used chemotherapy drug; however, with its side effects that include nephrotoxicity, it also exhibits a risk of inducing AKI. Importantly, recent studies have shown that autophagy plays a protective role in cisplatin-induced AKI. However, therapeutic strategies and candidate drugs for inducing activation of autophagy remain limited.

METHODS

In the present study, we adopted a novel candidate drug from a deep sea-derived Penicillium strain, penicilliumin B, to testify its protective role in cisplatin-induced renal tubular cell injury.

RESULTS

Penicilliumin B exhibited protection against cisplatin-induced apoptosis in cultured renal tubular epithelial cells and in cisplatin-treated mice. Moreover, penicilliumin B maintained normal mitochondrial morphology and inhibited the production of mitochondrial reactive oxygen species. Further studies demonstrated that penicilliumin B enhanced autophagic flux, promoted the activation of multiple autophagy-related proteins, such as mTOR, Beclin-1, ATG5, PINK1, and LC3B, and induced the degradation of p62. Interestingly, we also found penicilliumin B triggered phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK), which is an upstream inducer of nearly all autophagy pathways and also an activator of mitochondrial biogenesis. These results suggest that AMPK may represent an activated site of penicilliumin B. Consistently, compound C, an AMPK inhibitor, significantly blocked the protective effects of penicilliumin B on mitochondria and apoptotic inhibition.

CONCLUSION

Taken together, our findings indicate that penicilliumin B represents a novel AMPK activator that may provide protection against renal tubular cell apoptosis through activation of AMPK-induced autophagy and mitochondrial biogenesis.

Down-regulating miR-217-5p Protects Cardiomyocytes against Ischemia/Reperfusion Injury by Restoring Mitochondrial Function via Targeting SIRT1

Downregulating miR-217-5p could protect cardiomyocytes against ischemia/reperfusion (I/R) injury, but its role in restoring mitochondrial function of I/R-injured cardiomyocytes remained unclear. H9C2 cardiomyocyte-derived cell line with I/R injury was established in vitro on the basis of hypoxia/reperfusion (H/R) model. Cell viability and apoptosis were respectively detected by MTT assay and flow cytometry. Contents of lactate dehydrogenase (LDH) and adenosine triphosphate (ATP) were determined. Flow cytometry was performed to measure the production of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Target gene and potential binding sites between miR-217-5p and Sirtuin1 (SIRT1) were predicted by TargetScan and confirmed by dual-luciferase reporter assay. Relative SIRT1 and expressions of autophagy-related and apoptosis-related genes were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. After I/R treatment, the viability of H9C2 cardiomyocyte-derived cell line and ATP contents were reduced, but LDH and ROS contents were increased, at the same time, cell apoptosis and the expressions of miR-217-5p, p62 and cleaved caspase-3 were increased, whereas the expressions of SIRT1, LC3 (light chain 3), PINK1 (PTEN-induced kinase 1), Parkin, Bcl-2, and c-IAP (inhibitor of apoptosis protein) were reduced. However, downregulating miR-217-5p expression reversed the effects of I/R. SIRT1 was predicted and verified to be the target of miR-217-5p, and silencing SIRT1 reversed the effects of downregulating miR-217-5p on I/R-injured cells. Downregulating miR-217-5p could help restore mitochondrial function via targeting SIRT1, so as to protect cardiomyocytes against I/R-induced injury.

Diabetes induces hepatocyte pyroptosis by promoting oxidative stress-mediated NLRP3 inflammasome activation during liver ischaemia and reperfusion injury

Background

Although diabetes mellitus has been reported to aggravate liver ischaemia and reperfusion (IR) injury, the basic mechanism remains largely unknown. The object of the present study was to determine the role of oxidative stress and hepatocellular pyroptosis in liver IR injury in diabetic mice.

Methods

Db/db and C57BL/6 mice at 8 weeks of age were subjected to liver IR injury. Liver injury and hepatocyte cell death were analyzed. A NOD-like receptor family pyrin domain-containing 3 protein (NLRP3) inflammasome antagonist (CY09) and a reactive oxygen species (ROS) antagonist (N-Acetyl-L-cysteine, NAC) were used to determine the role of ROS-mediated hepatocellular pyroptosis in diabetic mice post-IR.

Results

Aggravated liver IR injury was found in db/db mice compared to C57BL/6 control mice, as demonstrated by increased serum alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) levels, liver architecture damage and Suzuki scores. Interestingly, IR induces the pyroptosis of hepatocytes in db/db mice, as evidenced by enhanced NLRP3 inflammasome activation, increased numbers of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive hepatocytes and increased gene expression of interleukin-1β (IL-1β) and IL-18 in livers post-IR. The inhibitory effect of CY09, an NLRP3 antagonist, efficiently abrogated the exacerbation effects of diabetes on liver IR injury in db/db mice. Furthermore, increased ROS expression was detected in db/db mice compared to control mice after IR. ROS scavenging by NAC pretreatment markedly inhibited hepatocellular NLRP3 inflammasome activation and pyroptosis in the db/db mice post-IR, indicating that ROS play an essential role in mediating hepatocyte pyroptosis in the setting of diabetes mellitus.

Conclusions

Our results demonstrate that diabetes induces hepatocyte pyroptosis by promoting oxidative stress-mediated NLRP3 inflammasome activation during liver IR injury. Strategies targeting ROS and NLRP3 inflammasome activation would be beneficial for preventing liver IR injury in diabetic patients.