Dysregulated autophagy: A key player in the pathophysiology of type 2 diabetes and its complications

Metformin instigates cellular autophagy to ameliorate high-fat diet-induced pancreatic inflammation and fibrosis/EMT in mice

BACKGROUND

Chronic pancreatic dysfunction is frequently observed as a consequence of prolonged high-fat diet consumption and is a serious public health concern. This pro-diabetic insult aggravates inflammation-influenced fibrotic lesions and is associated with deregulated autophagy. Metformin, a conventional anti-hyperglycemic drug, might be beneficial for pancreatic health, but the complex molecular regulations are not clarified. Considering the worldwide prevalence of chronic pancreatic dysfunction in obese individuals, we aimed to unwind the molecular intricacies explaining the involvement of oxidative stress, inflammation and fibrosis and to approbate metformin as a plausible intervention in this crossroad.

MAIN METHODS

Age-matched Swiss Albino mice were exposed to high-fat diet (60 kcal%) against control diet (10 kcal%) to establish diet-induced stress model. Metformin treatment was introduced after 4 weeks to metformin-control and HFD-exposed metformin groups. After 8 weeks, metabolic and molecular outcomes were assessed to establish the impact of metformin on chronic consequences of HFD-mediated injury.

KEY FINDINGS

High-fat diet administration to healthy mice primes oxidative stress-mediated chronic inflammation through Nrf2/Keap1/NF-κB interplay. Besides, pro-inflammatory cytokine bias leading to fibrotic (increased TGF-β, α-SMA, and MMP9) and pro-EMT (Twist1, Slug, Vimentin, E-cadherin) repercussions in pancreatic lobules were evident. Metformin distinctly rescues high-fat diet-induced remodeling of pancreatic pro-diabetic alterations and cellular survival/death switch. Further, metformin abrogates the p62-Twist1 crosstalk in an autophagy-dependent manner (elevated beclin1, LC3-II/I, Lamp2) to restore pancreatic homeostasis.

CONCLUSION

Our research validates the therapeutic potential of metformin in the inflammation-fibrosis nexus to ameliorate high-fat diet-induced pancreatic dysfunction and related metabolic alterations.

Lysosomal dysfunction-derived autophagy impairment of gingival epithelial cells in diabetes-associated periodontitis with altered protein acetylation

Diabetes-associated periodontitis (DP) presents severe inflammation and resistance to periodontal conventional treatment, presenting a significant challenge in clinical management. In this study, we investigated the underlying mechanism driving the hyperinflammatory response in gingival epithelial cells (GECs) of DP patients. Our findings indicate that lysosomal dysfunction under high glucose conditions leads to the blockage of autophagy flux, exacerbating inflammatory response in GECs. Single-cell RNA sequencing and immunohistochemistry analyses of clinical gingival epithelia revealed dysregulation in the lysosome pathway characterized by reduced levels of lysosome-associated membrane glycoprotein 2 (LAMP2) and V-type proton ATPase 16 kDa proteolipid subunit c (ATP6V0C) in subjects with DP. In vitro stimulation of human gingival epithelial cells (HGECs) with a hyperglycemic microenvironment showed elevated release of proinflammatory cytokines, compromised lysosomal acidity and blocked autophagy. Moreover, HGECs with deficiency in ATP6V0C demonstrated impaired autophagy and heightened inflammatory response, mirroring the effects of high glucose stimulation. Proteomic analysis of acetylation modifications identified altered acetylation levels in 28 autophagy-lysosome pathway-related proteins and 37 sites in HGECs subjected to high glucose stimulation or siATP6V0C. Overall, our finding highlights the pivotal role of lysosome impairment in autophagy obstruction in DP and suggests a potential impact of altered acetylation of relevant proteins on the interplay between lysosome dysfunction and autophagy blockage. These insights may pave the way for the development of effective therapeutic strategies against DP.

Dapagliflozin restores autophagy and attenuates apoptosis via the AMPK/mTOR pathway in diabetic nephropathy rats and high glucose-induced HK-2 cells

PURPOSE

Diabetic nephropathy (DN) is a serious microvascular complication of diabetes mellitus. Significantly reduced levels of autophagy in diabetic kidneys play an important role in the development of DN. The present study investigated the effects of dapagliflozin (DAP) on renal autophagy and AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway in vivo and in vitro.

METHODS

We explored the effect of DAP in streptozotocin (STZ)-induced DN rats. The anti-DN effect of DAP was assessed by body weight, kidney weight/body weight ratio, blood and urine biochemical parameters, and pathological changes of kidney tissue. Number of autophagosomes in the kidney was investigated through Transmission electron microscopy. Besides, cell viability and apoptosis of DAP alone or combined with Compound C (CC, a selective AMPK inhibitor)-treated high glucose (HG)-induced HK-2 cells were detected by Cell Counting Kit-8 (CCK-8) and flow cytometry assays. Immunohistochemistry, Western blot, Enzyme-linked immunosorbent assay (ELISA), and immunofluorescence were employed to detect the expression levels of extracellular matrix (ECM) deposition, autophagy, apoptosis, and AMPK/mTOR pathway-associated targets in vivo and in vitro.

RESULTS

The results showed that DAP ameliorated the body weight and decreased kidney weight, fasting blood glucose, and serum/urine biochemical parameters of renal damage, as well as renal pathological changes. Moreover, DAP significantly ameliorated HG-induced cell apoptosis and ECM deposition in HK-2 cells. However, these favorable effects of DAP could be abolished by co-treatment with CC in HG-induced HK-2 cells. Mechanistically, DAP can enhance autophagy in DN including increased LC3-II/I ratio, Beclin-1, p-AMPK protein levels, and decreased p62 and p-mTOR protein expressions, as well as inhibited renal fibrosis and apoptosis.

CONCLUSION

In summary, DAP alleviated fibrosis, apoptosis, and autophagy in DN rats and HG-induced HK-2 cells by regulating the AMPK/mTOR pathway.

Dysregulation of pancreatic β-cell autophagy and the risk of type 2 diabetes

Macroautophagy/autophagy is an essential degradation process that removes abnormal cellular components, maintains homeostasis within cells, and provides nutrition during starvation. Activated autophagy enhances cell survival during stressful conditions, although overactivation of autophagy triggers induction of autophagic cell death. Therefore, early-onset autophagy promotes cell survival whereas late-onset autophagy provokes programmed cell death, which can prevent disease progression. Moreover, autophagy regulates pancreatic β-cell functions by different mechanisms, although the precise role of autophagy in type 2 diabetes (T2D) is not completely understood. Consequently, this mini-review discusses the protective and harmful roles of autophagy in the pancreatic β cell and in the pathophysiology of T2D.

Multifaceted role of dynamin-related protein 1 in cardiovascular disease: From mitochondrial fission to therapeutic interventions

Mitochondria are central to cellular energy production and metabolic regulation, particularly in cardiomyocytes. These organelles constantly undergo cycles of fusion and fission, orchestrated by key proteins like Dynamin-related Protein 1 (Drp-1). This review focuses on the intricate roles of Drp-1 in regulating mitochondrial dynamics, its implications in cardiovascular health, and particularly in myocardial infarction. Drp-1 is not merely a mediator of mitochondrial fission; it also plays pivotal roles in autophagy, mitophagy, apoptosis, and necrosis in cardiac cells. This multifaceted functionality is often modulated through various post-translational alterations, and Drp-1's interaction with intracellular calcium (Ca2 + ) adds another layer of complexity. We also explore the pathological consequences of Drp-1 dysregulation, including increased reactive oxygen species (ROS) production and endothelial dysfunction. Furthermore, this review delves into the potential therapeutic interventions targeting Drp-1 to modulate mitochondrial dynamics and improve cardiovascular outcomes. We highlight recent findings on the interaction between Drp-1 and sirtuin-3 and suggest that understanding this interaction may open new avenues for therapeutically modulating endothelial cells, fibroblasts, and cardiomyocytes. As the cardiovascular system increasingly becomes the focal point of aging and chronic disease research, understanding the nuances of Drp-1's functionality can lead to innovative therapeutic approaches.

A review on associated factors and management measures for sarcopenia in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease characterized by hyperglycemia, insulin resistance, and insufficient insulin secretion. Sarcopenia, as a new complication of diabetes, is characterized by the loss of muscle mass and the progressive decline of muscle strength and function in T2DM patients, which has a serious impact on the physical and mental health of patients. Insulin resistance, mitochondrial dysfunction, and chronic inflammation are common mechanisms of diabetes and sarcopenia. Reasonable exercise training, nutrition supplement, and drug intervention may improve the quality of life of patients with diabetes combined with sarcopenia. This article reviews the relevant factors and management measures of sarcopenia in T2DM patients, in order to achieve early detection, diagnosis, and intervention.

Meta-analysis on GLP-1 mediated modulation of autophagy in islet β-cells: Prospectus for improved wound healing in type 2 diabetes

Type 2 diabetes mellitus refers to a significantly challenging health disease due to its high prevalence and risk of other chronic diseases across the world. Notably, GLP-1 has been recognized to enhance the treatment of T2DM, along with this, GLP-1 is also involved in autophagy modulation. However, ineffectiveness of few analogue types can limit the efficacy of this treatment. This study particularly aims to elucidate the influence of GLP-1 receptor analogues on wound infection and patients with type 2 diabetes. To conduct the meta-analysis, an expansive literature survey was conducted to unveil the studies and research conducted on T2DM patients that revealed whether the adoption of any GLP-1 analogue in the form of specific interventions impacts the type 2 diabetes mellitus. The literature was searched using multiple search terms, screened and data were extracted to conduct the meta-analysis and it was conducted using metabin function of R package meta. A total of 800 patients consisting of the both intervention and control groups were employed to carry out the meta-analysis to analyse and evaluate the impact of GLP-1 mediated modulation to improve wound healing in the T2DM patients. The results revealed that GLP-1 mediated modulation considering one type of analogue was an effective intervention to patients suffering from T2DM. The variations in these results depicted insignificant outcomes with the values (risk ratio [RR]: 1.03, 95% confidence interval [CI]: 0.90-1.18, p > 0.05) and enlightened the fact that adopting different GLP-1 analogues may significantly improve the efficacy of wound healing in T2DM patients. Hence, interventions of GLP-1 mediated modulation must be utilized in the clinical practice to reduce the incidence of T2DM patients.

Mechanism of traditional Chinese medicine in elderly diabetes mellitus and a systematic review of its clinical application

Objective: Affected by aging, the elderly diabetes patients have many pathological characteristics different from the young people, including more complications, vascular aging, cognitive impairment, osteoporosis, and sarcopenia. This article will explore their pathogenesis and the mechanism of Traditional Chinese medicine (TCM) intervention, and use the method of systematic review to evaluate the clinical application of TCM in elderly diabetes. Method: Searching for randomized controlled trials (RCTs) published from January 2000 to November 2023 in the following databases: Web of Science, Pubmed, Embase, Cochrane Library, Sinomed, China National Knowledge Internet, Wanfang and VIP. They were evaluated by three subgroups of Traditional Chinese Prescription, Traditional Chinese patent medicines and Traditional Chinese medicine extracts for their common prescriptions, drugs, adverse reactions and the quality of them. Results and Conclusion: TCM has the advantages of multi-target and synergistic treatment in the treatment of elderly diabetes. However, current clinical researches have shortcomings including the inclusion of age criteria and diagnosis of subjects are unclear, imprecise research design, non-standard intervention measures, and its safety needs further exploration. In the future, the diagnosis of elderly people with diabetes needs to be further clarified. Traditional Chinese patent medicines included in the pharmacopoeia can be used to conduct more rigorous RCTs, and then gradually standardize the traditional Chinese medicine prescriptions and traditional Chinese medicine extracts, providing higher level evidence for the treatment of elderly diabetes with traditional Chinese medicine.

Pharmacological targets at the lysosomal autophagy-NLRP3 inflammasome crossroads

Many aspects of cell homeostasis and integrity are maintained by the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome. The NLRP3 oligomeric protein complex assembles in response to exogenous and endogenous danger signals. This inflammasome has also been implicated in the pathogenesis of a range of disease conditions, particularly chronic inflammatory diseases. Given that NLRP3 modulates autophagy, which is also a key regulator of inflammasome activity, excessive inflammation may be controlled by targeting this intersecting pathway. However, specific niche areas of NLRP3-autophagy interactions and their reciprocal regulatory mechanisms remain underexplored. Consequently, we lack treatment methods specifically targeting this pivotal axis. Here, we discuss the potential of such strategies in the context of autoimmune and metabolic diseases and propose some research avenues.

Zinc oxide nanoparticles inhibit malignant progression and chemotherapy resistance of ovarian cancer cells by activating endoplasmic reticulum stress and promoting autophagy

The mortality rate of ovarian cancer (OC) is high, posing a serious threat to women's lives. Zinc oxide nanoparticles (ZnO-NPs) show great potential in the treatment of cancer. However, the mechanism of ZnO-NPs in inhibiting the malignant proliferation and chemotherapy resistance of OC has remained elusive. In the present study, ZnO-NPs at different concentrations were used to treat SKOV3 cells, and subsequently, analyses including the Cell Counting Kit-8 assay, EDU staining, colony-formation assay, flow cytometry, wound-healing assay, Transwell assay and western blot were used to detect cell proliferation, invasion, migration, epithelial-mesenchymal transition (EMT) and chemotherapy resistance, as well as endoplasmic reticulum stress (ERS)- and autophagy-related indicators. Finally, the mechanisms of action of ZnO-NPs on OC were examined by adding ERS inhibitor 4-phenylbutyric acid (4-PBA) and autophagy inhibitor 3-methyladenine (3-MA). It was found that ZnO-NPs inhibited SKOV3 cell proliferation, facilitated apoptosis and induced cell cycle arrest. Furthermore, ZnO-NPs inhibited the invasion, migration and EMT of SKOV3 cells. ZnO-NPs also inhibited chemotherapy resistance of SKOV3 cells. ZnO-NPs activated ERS and promoted autophagy. The addition of 4-PBA or 3-MA significantly reversed the effects of ZnO-NPs on SKOV3 cells. Overall, ZnO-NPs inhibit the malignant progression and the chemotherapy resistance of SKOV3 cells by activating ERS and promoting autophagy.

Autophagy, a critical element in the aging male reproductive disorders and prostate cancer: a therapeutic point of view

Autophagy is a highly conserved, lysosome-dependent biological mechanism involved in the degradation and recycling of cellular components. There is growing evidence that autophagy is related to male reproductive biology, particularly spermatogenic and endocrinologic processes closely associated with male sexual and reproductive health. In recent decades, problems such as decreasing sperm count, erectile dysfunction, and infertility have worsened. In addition, reproductive health is closely related to overall health and comorbidity in aging men. In this review, we will outline the role of autophagy as a new player in aging male reproductive dysfunction and prostate cancer. We first provide an overview of the mechanisms of autophagy and its role in regulating male reproductive cells. We then focus on the link between autophagy and aging-related diseases. This is followed by a discussion of therapeutic strategies targeting autophagy before we end with limitations of current studies and suggestions for future developments in the field.

Autophagy and diabetes

The current literature findings on autophagy’s beneficial and detrimental roles in diabetes mellitus (DM) and diabetes-related comorbidities were reviewed. The effects of oral hypoglycaemic medicines and autophagy in DM. Autophagy plays an important function in cellular homeostasis by promoting cell survival or initiating cell death in physiological settings was also assessed. Although autophagy protects insulin-target tissues, organelle failure caused by autophagy malfunction influences DM and other metabolic diseases. Endoplasmic reticulum and oxidative stress enhance autophagy levels, making it easier to regulate stress-induced intracellular changes. Evidence suggests that autophagy-caused cell death can occur when autophagy is overstimulated and constitutively activated, which might prevent or develop DM. Even though the precise role of autophagy in DM complications is uncertain, deregulation of the autophagic machinery is strongly linked to beta cell destruction and the aetiology of DM. Thus, improving autophagy dysfunction is a possible therapeutic objective in treating DM and other metabolic disorders.

Exposure to a static magnetic field attenuates hepatic damage and function abnormality in obese and diabetic mice

Static magnetic fields (SMFs) exhibit significant effect on health care. However, the effect of SMF on hepatic metabolism and function in obesity and diabetes are still unknown. Liver is not only the main site for glucolipid metabolism but also the core part for iron metabolism regulation. Dysregulations of iron metabolism and redox status are risk factors for the development of hepatic injury and affect glucolipid metabolism in obesity and diabetes. Mice of HFD-induced obesity and HFD/streptozocin-induced diabetes were exposed to a moderate-intensity SMF (0.4-0.7 T, direction: upward, 4 h/day, 8 weeks). Results showed that SMF attenuated hepatic damage by decreasing inflammation and fibrosis in obese and diabetic mice. SMF had no effects on improving glucose/insulin tolerance but regulated proteins (GLUT1 and GLUT4) and genes (G6pc, Pdk4, Gys2 and Pkl) participating in glucose metabolism with phosphorylation of Akt/AMPK/GSK3β. SMF also reduced lipid droplets accumulation through decreasing Plin2 and Plin5 and regulated lipid metabolism with elevated hepatic expressions of PPARγ and C/EBPα in obese mice. In addition, SMF decreased hepatic iron deposition with lower FTH1 expression and modulated systematic iron homeostasis via BMP6-mediated regulation of hepcidin. Moreover, SMF balanced hepatic redox status with regulation on mitochondrial function and MAPKs/Nrf2/HO-1 pathway. Finally, we found that SMF activated hepatic autophagy and enhanced lipophagy by upregulating PNPLA2 expression in obese and diabetic mice. Our results demonstrated that SMF significantly ameliorated the development of hepatic injury in obese and diabetic mice by inhibiting inflammatory level, improving glycolipid metabolism, regulating iron metabolism, balancing redox level and activating autophagy.