Bromodomain Protein Inhibition Protects ß-Cells from Cytokine-Induced Death and Dysfunction via Antagonism of NF-κB Pathway.

Cytokine-induced ß-cell apoptosis is a major pathogenic mechanism in type 1 diabetes (T1D). Despite significant advances in understanding its underlying mechanisms, few drugs have been translated to protect ß-cells in T1D. Epigenetic modulators such as bromodomain-containing BET (bromo- and extra-terminal) proteins are important regulators of immune responses. Pre-clinical studies have demonstrated a protective effect of BET inhibitors in an NOD (non-obese diabetes) mouse model of T1D. However, the effect of BET protein inhibition on ß-cell function in response to cytokines is unknown. Here, we demonstrate that I-BET, a BET protein inhibitor, protected ß-cells from cytokine-induced dysfunction and death. In vivo administration of I-BET to mice exposed to low-dose STZ (streptozotocin), a model of T1D, significantly reduced ß-cell apoptosis, suggesting a cytoprotective function. Mechanistically, I-BET treatment inhibited cytokine-induced NF-kB signaling and enhanced FOXO1-mediated anti-oxidant response in ß-cells. RNA-Seq analysis revealed that I-BET treatment also suppressed pathways involved in apoptosis while maintaining the expression of genes critical for ß-cell function, such as Pdx1 and Ins1. Taken together, this study demonstrates that I-BET is effective in protecting ß-cells from cytokine-induced dysfunction and apoptosis, and targeting BET proteins could have potential therapeutic value in preserving ß-cell functional mass in T1D.

Mannan-Binding Lectin Is Associated with Inflammation and Kidney Damage in a Mouse Model of Type 2 Diabetes.

Autoreactivity of the complement system may escalate the development of diabetic nephropathy. We used the BTBR OB mouse model of type 2 diabetes to investigate the role of the complement factor mannan-binding lectin (MBL) in diabetic nephropathy. Female BTBR OB mice (n = 30) and BTBR non-diabetic WT mice (n = 30) were included. Plasma samples (weeks 12 and 21) and urine samples (week 19) were analyzed for MBL, C3, C3-fragments, SAA3, and markers for renal function. Renal tissue sections were analyzed for fibrosis, inflammation, and complement deposition. The renal cortex was analyzed for gene expression (complement, inflammation, and fibrosis), and isolated glomerular cells were investigated for MBL protein. Human vascular endothelial cells cultured under normo- and hyperglycemic conditions were analyzed by flow cytometry. We found that the OB mice had elevated plasma and urine concentrations of MBL-C (p < 0.0001 and p < 0.001, respectively) and higher plasma C3 levels (p < 0.001) compared to WT mice. Renal cryosections from OB mice showed increased MBL-C and C4 deposition in the glomeruli and increased macrophage infiltration (p = 0.002). Isolated glomeruli revealed significantly higher MBL protein levels (p < 0.001) compared to the OB and WT mice, and no renal MBL expression was detected. We report that chronic inflammation plays an important role in the development of DN through the binding of MBL to hyperglycemia-exposed renal cells.

A translational model of chronic diabetic nephropathy in the Nile grass rat.

Diabetic nephropathy (DN) is a major healthcare challenge for individuals with diabetes and associated with increased cardiovascular morbidity and mortality. The existing rodent models do not fully represent the complex course of the human disease. Hence, developing a translational model of diabetes that reproduces both the early and the advanced characteristics of DN and faithfully recapitulates the overall human pathology is an unmet need. Here, we introduce the Nile grass rat (NGR) as a novel model of DN and characterize key pathologies underlying DN. NGRs spontaneously developed insulin resistance, reactive hyperinsulinemia, and hyperglycemia. Diabetic NGRs evolved DN and the key histopathological aspects of the human advanced DN, including glomerular hypertrophy, infiltration of mononuclear cells, tubular dilatation, and atrophy. Enlargement of the glomerular tufts and the Bowman's capsule areas accompanied the expansion of the Bowman's space. Glomerular sclerosis, renal arteriolar hyalinosis, Kimmelsteil-Wilson nodular lesions, and protein cast formations in the kidneys of diabetic NGR occurred with DN. Diabetic kidneys displayed interstitial and glomerular fibrosis, key characteristics of late human pathology as well as thickening of the glomerular basement membrane and podocyte effacement. Signs of injury included glomerular lipid accumulation, significantly more apoptotic cells, and expression of KIM-1. Diabetic NGRs became hypertensive, a known risk factor for kidney dysfunction, and showed decreased glomerular filtration rate. Diabetic NGRs recapitulate the breadth of human DN pathology and reproduce the consequences of chronic kidney disease, including injury and loss of function of the kidney. Hence, NGR represents a robust model for studying DN-related complications and provides a new foundation for more detailed mechanistic studies of the genesis of nephropathy, and the development of new therapeutic approaches.

Hyperglycemia influences the cell proliferation and death of the rat endocrine pancreas in the neonatal period.

AIMS: To evaluate the cell proliferation and death, and structural morphology of the pancreatic islet cells of the rats with hyperglycemia in the first month of life and compare to those of the control rats. MAIN METHODS: Female Sprague-Dawley newborn rats received Streptozotocin (a beta-cytotoxic drug) at birth for diabetes induction. Control and hyperglycemic animals were euthanized on different days of life: 5, 10, 15, and 30. The pancreas was collected and processed for immunohistochemical analysis of cleaved Caspase-3 (cell death), Ki-67 (cell proliferation), PDX-1 (transcription factor responsible for insulin synthesis), and endocrine hormones (insulin, glucagon, and somatostatin). KEY FINDINGS: Control females showed a higher percentage (%) of Ki-67-positive(+) cells on D10 and D15, a higher % of insulin+ and somatostatin+ cells on D15 and D30, a lower % of PDX-1+ cells on D10, and a higher % of glucagon+ cells on D10 and D30. Hyperglycemic females showed a lower % of Ki-67+ cells on D15, a higher % of cleaved Caspase-3+ cells on D15, and insulin+ cells on D15 and D30. In the comparison among the experimental groups, the hyperglycemic females showed an increased % of cleaved Caspase-3+ and Ki-67+ cells and a lower % of PDX-1+ cells. SIGNIFICANCE: This study enabled a better understanding of the abnormal pancreas development regarding cellular proliferation, apoptosis, and hormonal synthesis in the neonatal period. Thus, the pancreatic islets of hyperglycemic rats do not reestablish the normal endocrine cell population, and cellular apoptosis overcame the proliferative activity of these cells.

Dapagliflozin administration to a mouse model of type 2 diabetes induces DNA methylation and gene expression changes in pancreatic islets.

Decreased pancreatic ß-cell volume is a serious problem in patients with type 2 diabetes mellitus, and there is a need to establish appropriate treatments. Increasingly, sodium/glucose cotransporter 2 (SGLT2) inhibitors, which have a protective effect on pancreatic ß-cells, are being prescribed to treat diabetes; however, the underlying mechanism is not well understood. We previously administered SGLT2 inhibitor dapagliflozin to a mouse model of type 2 diabetes and found significant changes in gene expression in the early-treated group, which led us to hypothesize that epigenetic regulation was a possible mechanism of these changes. Therefore, we performed comprehensive DNA methylation analysis by methylated DNA immunoprecipitation using isolated pancreatic islets after dapagliflozin administration to diabetic model mice. As a result, we identified 31 genes with changes in expression due to DNA methylation changes. Upon immunostaining, cystic fibrosis transmembrane conductance regulator and cadherin 24 were found to be upregulated in islets in the dapagliflozin-treated group. These molecules may contribute to the maintenance of islet morphology and insulin secretory capacity, suggesting that SGLT2 inhibitors' protective effect on pancreatic ß-cells is accompanied by DNA methylation changes, and that the effect is long-term and not temporary. In future diabetes care, SGLT2 inhibitors may be expected to have positive therapeutic effects, including pancreatic ß-cell protection.

[Construction of a mouse model of type 2 diabetes induced by high fat diet alone and evaluation of pathological changes].

The purpose of the present study was to investigate the modeling time of type 2 diabetes mellitus (T2DM) mouse model induced by high fat diet (HFD) alone and the effects of HFD on the pathology and function of organs related to glucose and lipid metabolism. C57BL/6 mice were fed with normal diet (NC group) or HFD (HFD group). The time of successful T2DM modeling was evaluated by measuring body weight, fasting blood glucose and glucose tolerance at time points of 0, 4, 8, 12, 16 and 20 weeks. The functional and pathological changes of glucose and lipid metabolism related organs were evaluated by detecting insulin tolerance, plasma lipid levels, vascular function, as well as HE staining of pancreas and liver. The results showed that compared with the NC group, the HFD group had significantly increased body weight after 8 weeks of HFD. After 16 weeks of HFD, the HFD group exhibited impaired fasting glucose tolerance. After 20 weeks of HFD, the HFD group mice reached diabetic state, showing impaired glucose tolerance and insulin resistance, islet volume reduction and vacuolar degeneration; Large number of lipid droplets appeared in liver cells, and the level of AMPK phosphorylation in liver tissue was significantly increased in the HFD groups, compared with the NC group; There was endothelial dependent diastolic dysfunction in the thoracic aorta of the HFD group; Compared with the NC group, the HFD group mice showed a significant increase in urinary protein levels. These results suggest that T2DM mouse model can be successfully established by HFD induction alone for 20 weeks. The model is characterized by insulin resistance, fatty liver, hyperlipidemia, vascular dysfunction, renal dysfunction and pathological changes of islet and liver cells, which are similar to those of T2DM patients. Therefore it can be used as an ideal animal model for T2DM research.

Smooth muscle NF90 deficiency ameliorates diabetic atherosclerotic calcification in male mice via FBXW7-AGER1-AGEs axis.

Hyperglycemia accelerates calcification of atherosclerotic plaques in diabetic patients, and the accumulation of advanced glycation end products (AGEs) is closely related to the atherosclerotic calcification. Here, we show that hyperglycemia-mediated AGEs markedly increase vascular smooth muscle cells (VSMCs) NF90/110 activation in male diabetic patients with atherosclerotic calcified samples. VSMC-specific NF90/110 knockout in male mice decreases obviously AGEs-induced atherosclerotic calcification, along with the inhibitions of VSMC phenotypic changes to osteoblast-like cells, apoptosis, and matrix vesicle release. Mechanistically, AGEs increase the activity of NF90, which then enhances ubiquitination and degradation of AGE receptor 1 (AGER1) by stabilizing the mRNA of E3 ubiquitin ligase FBXW7, thus causing the accumulation of more AGEs and atherosclerotic calcification. Collectively, our study demonstrates the effects of VSMC NF90 in mediating the metabolic imbalance of AGEs to accelerate diabetic atherosclerotic calcification. Therefore, inhibition of VSMC NF90 may be a potential therapeutic target for diabetic atherosclerotic calcification.

Kiwifruit (Actinidia deliciosa) aqueous extract improves hyperglycemia, testicular inflammation, apoptosis, and tissue structure induced by Streptozotocin via oxidative stress inhibition.

Diabetes mellitus (DM) is a well-known hyperglycemic metabolic condition identified by oxidative stress and biological function disruption. Kiwifruit is a valuable source of polyphenols and vitamin C with great antioxidant, nutritional, and health-promoting effects. Therefore, this study was initiated to explore the antioxidant and anti-hyperglycemic effects of kiwifruit aqueous extract (KFE) against oxidative injury and testis dysfunction in rats with diabetes. Twenty-four male Wistar Albino rats (160-170 g) were divided into four groups: Group 1 served as the control, Group 2 supplemented orally with kiwifruit extract (KFE; 1 g/kg/day) for one month, Group 3 was treated with a single streptozotocin dose (STZ; 50 mg/kg ip), and Group 4 where the diabetic rats were administered with KFE, respectively. According to the results, the GC-MS analysis of KFE revealed several main components with strong antioxidant properties. In diabetic rats, lipid peroxidation and hyperglycemia were accompanied by perturbations in hormone levels and sperm characteristics. Antioxidant enzymes, glutathione content, aminotransferase, phosphatase activities, and protein content were decreased. Furthermore, histology, immunohistochemical PCNA expression, and histochemical analysis of collagen, DNA, RNA, and total protein. were altered in rat testis sections, supporting the changes in biochemistry. Furthermore, diabetic rats supplemented with KFE manifested considerable amendment in all the tested parameters besides improved tissue structure and gene expressions (NF-kB, p53, IL-1ß, Bax, IL-10, and Bcl2) relative to the diabetic group. In conclusion, KFE has beneficial effects as it can improve glucose levels and testis function, so it might be used as a complementary therapy in DM.

Stimulated Full-Thickness Cutaneous Wound Healing with Bioactive Dressings of Zinc and Cobalt Ion-Doped Bioactive Glass-Coated Eggshell Membranes in a Diabetic Rabbit Model.

Eggshell membrane-based biomedical applications have recently received great attention for their wound-healing properties. However, there are limited studies on diabetic wound healing. In this regard, we devised four types of composite eggshell membrane mats with nanoscale coatings of bioactive glass/Zn/Co-doped bioactive glass (ESM + BAG, ESM + ZnBAG, ESM + CoBAG, and ESM + ZnCoBAG) as wound-dressing materials for chronic nonhealing diabetic wounds. A detailed study of the physicochemical properties of the mats was conducted. In vitro studies demonstrated cytocompatibility and viability of human dermal fibroblasts on all four types of mats. The cells also attached finely on the mats with the help of cellular extensions, as evident from scanning electron microscopy (SEM) and rhodamine-phalloidin and Hoechst 33342 staining of cellular components. Endowed with bioactive properties, these mats influenced all aspects of full-thickness skin wound healing in diabetic animal model studies. All of the mats, especially the ESM + ZnCoBAG mat, showed the earliest wound closure, effective renewal, and restructuring of the extracellular matrix in terms of an accurate and timely accumulation of collagen, elastin, and reticulin fibers. Hydroxyproline and sulfated glycosaminoglycans were significantly (p < 0.01, p < 0.05) higher in ESM-ZnCoBAG-treated wounds in comparison to ESM-BAG-treated wounds, which suggests that these newly developed mats have potential as an affordable diabetic wound care solution in biomedical research.

Podocyte OTUD5 alleviates diabetic kidney disease through deubiquitinating TAK1 and reducing podocyte inflammation and injury.

Recent studies have shown the crucial role of podocyte injury in the development of diabetic kidney disease (DKD). Deubiquitinating modification of proteins is widely involved in the occurrence and development of diseases. Here, we explore the role and regulating mechanism of a deubiquitinating enzyme, OTUD5, in podocyte injury and DKD. RNA-seq analysis indicates a significantly decreased expression of OTUD5 in HG/PA-stimulated podocytes. Podocyte-specific Otud5 knockout exacerbates podocyte injury and DKD in both type 1 and type 2 diabetic mice. Furthermore, AVV9-mediated OTUD5 overexpression in podocytes shows a therapeutic effect against DKD. Mass spectrometry and co-immunoprecipitation experiments reveal an inflammation-regulating protein, TAK1, as the substrate of OTUD5 in podocytes. Mechanistically, OTUD5 deubiquitinates K63-linked TAK1 at the K158 site through its active site C224, which subsequently prevents the phosphorylation of TAK1 and reduces downstream inflammatory responses in podocytes. Our findings show an OTUD5-TAK1 axis in podocyte inflammation and injury and highlight the potential of OTUD5 as a promising therapeutic target for DKD.

Sirtuin-6 knockout causes exacerbated stalled healing of diabetic ulcers in mice.

BACKGROUND: Diabetic ulcers (DUs) are characterized by chronic inflammation and delayed re-epithelialization, with a high incidence and weighty economic burden. The primary therapeutic strategies for refractory wounds include surgery, non-invasive wound therapy, and drugs, while the optimum regimen remains controversial. Sirtuin-6 (SIRT6) is a histone deacetylase and a key epigenetic factor that exerts anti-inflammatory and pro-proliferatory effects in wound healing. However, the exact function of SIRT6 in DUs remains unclear. METHODS: We generated tamoxifen-inducible SIRT6 knockout mice by crossing SIRT6flox/flox homozygous mice with UBC-creERT2+ transgenic mice. Systemic SIRT6 null mice, under either normal or diabetic conditions, were utilized to assess the effects of SIRT6 in DUs treatment. Gene and protein expressions of SIRT6 and inflammatory cytokines were measured by Western blotting and RT-qPCR. Histopathological examination confirmed the altered re-epithelialization (PCNA), inflammation (NF-κB p50 and F4/80), and angiogenesis (CD31) markers during DUs restoration. RESULTS: Knockout of SIRT6 inhibited the healing ability of DUs, presenting attenuated re-epithelialization (PCNA), exacerbated inflammation responses (NF-κB p50, F4/80, Il-1ß, Tnf-α, Il-6, Il-10, and Il-4), and hyperplasia vascular (CD31) compared with control mice. CONCLUSIONS: SIRT6 could boost impaired wound healing through improving epidermal proliferation, inflammation, and angiogenesis. Our study highlighted the therapeutic potential of the SIRT6 agonist for DUs treatment.

Marrow mesenchymal stem cell mediates diabetic nephropathy progression via modulation of Smad2/3/WTAP/m6A/ENO1 axis.

Diabetic nephropathy (DN) is one of the common microvascular complications in diabetic patients. Marrow mesenchymal stem cells (MSCs) have attracted attention in DN therapy but the underlying mechanism remains unclear. Here, we show that MSC administration alleviates high glucose (HG)-induced human kidney tubular epithelial cell (HK-2 cell) injury and ameliorates renal injury in DN mice. We identify that Smad2/3 is responsible for MSCs-regulated DN progression. The activity of Smad2/3 was predominantly upregulated in HG-induced HK-2 cell and DN mice and suppressed with MSC administration. Activation of Smad2/3 via transforming growth factor-ß1 (TGF-ß1) administration abrogates the protective effect of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Smad2/3 has been reported to interact with methyltransferase of N6-methyladenosine (m6A) complex and we found a methyltransferase, Wilms' tumor 1-associating protein (WTAP), is involved in MSCs-Smad2/3-regulated DN development. Moreover, WTAP overexpression abrogates the improvement of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Subsequently, α-enolase (ENO1) is the downstream target of WTAP-mediated m6A modification and contributes to the MSCs-mediated regulation. Collectively, these findings reveal a molecular mechanism in DN progression and indicate that Smad2/3/WTAP/ENO1 may present a target for MSCs-mediated DN therapy.

Disturbed glycolipid metabolism activates CXCL13-CXCR5 axis in senescent TSCs to promote heterotopic ossification.

Heterotopic ossification (HO) occurs as a common complication after injury, while its risk factor and mechanism remain unclear, which restricts the development of pharmacological treatment. Clinical research suggests that diabetes mellitus (DM) patients are prone to developing HO in the tendon, but solid evidence and mechanical research are still needed. Here, we combined the clinical samples and the DM mice model to identify that disordered glycolipid metabolism aggravates the senescence of tendon-derived stem cells (TSCs) and promotes osteogenic differentiation. Then, combining the RNA-seq results of the aging tendon, we detected the abnormally activated autocrine CXCL13-CXCR5 axis in TSCs cultured in a high fat, high glucose (HFHG) environment and also in the aged tendon. Genetic inhibition of CXCL13 successfully alleviated HO formation in DM mice, providing a potential therapeutic target for suppressing HO formation in DM patients after trauma or surgery.

Renal Tissue-Derived Exosomal miRNA-34a in Diabetic Nephropathy Induces Renal Tubular Cell Fibrosis by Promoting the Polarization of M1 Macrophages.

Background: Diabetic nephropathy (DN) is the leading cause of chronic kidney disease, and the activation and infiltration of phagocytes are critical steps of DN. This study aimed to explore the mechanism of exosomes in macrophages and diabetes nephropathy and the role of miRNA-34a, which might provide a new path for treating DN. Materials and Methods: The DN model was established, and the success of the model establishment was confirmed by detecting general indicators, HE staining, and immunohistochemistry. Electron microscopy and NanoSight Tracking Analysis (NTA) were used to see the morphology and size of exosomes. MiRNA-34a inhibitor, miRNA-34a mimics, pc-PPARGC1A, and controls were transfected in macrophages with or without kidney exosomal. A dual-luciferase reporter gene experiment verifies the targeting relationship between miRNA-34a and PPARGC1A. After exosomal culture, macrophages are co-cultured with normal renal tubular cells to detect renal tubular cell fibrosis. Q-PCR and western blot were undertaken to detect related RNA and proteins. Results: An animal model of diabetic nephropathy was successfully constructed. Macrophages could phagocytose exosomes. After ingesting model exosomes, M1 macrophages were activated, while M2 macrophages were weakened, indicating the model mice's kidney exosomes caused the polarization. MiRNA-34a inhibitor increased PPARGC1A expression. MiRNA-34a expressed higher in diabetic nephropathy Model-Exo. MiRNA-34a negatively regulated PPARGC1A. PPARGC1A rescued macrophage polarization and renal tubular cell fibrosis. Conclusion: Exosomal miRNA-34a of tubular epithelial cells promoted M1 macrophage activation in diabetic nephropathy via negatively regulating PPARGC1A expression, which may provide a new direction for further exploration of DN treatment.

Induction of diabetes by Tacrolimus in a phenotypic model of obesity and metabolic syndrome.

Introduction: The pathogenesis of Post-Transplant Diabetes Mellitus (PTDM) is complex and multifactorial and it resembles that of Type-2 Diabetes Mellitus (T2DM). One risk factor specific to PTDM differentiates both entities: the use of immunosuppressive therapy. Specifically, Tacrolimus interacts with obesity and insulin resistance (IR) in accelerating the onset of PTDM. In a genotypic model of IR, the obese Zucker rats, Tacrolimus is highly diabetogenic by promoting the same changes in beta-cell already modified by IR. Nevertheless, genotypic animal models have their limitations and may not resemble the real pathophysiology of diabetes. In this study, we have evaluated the interaction between beta-cell damage and Tacrolimus in a non-genotypic animal model of obesity and metabolic syndrome. Methods: Sprague Dawley rats were fed a high-fat enriched diet during 45 days to induce obesity and metabolic dysregulation. On top of this established obesity, the administration of Tacrolimus (1mg/kg/day) during 15 days induced severe hyperglycaemia and changes in morphological and structural characteristics of the pancreas. Results: Obese animals administered with Tacrolimus showed increased size of islets of Langerhans and reduced beta-cell proliferation without changes in apoptosis. There were also changes in beta-cell nuclear factors such as a decrease in nuclear expression of MafA and a nuclear overexpression of FoxO1A, PDX-1 and NeuroD1. These animals also showed increased levels of pancreatic insulin and glucagon. Discussion: This model could be evidence of the relationship between the T2DM and PTDM physiopathology and, eventually, the model may be instrumental to study the pathogenesis of T2DM.

Dulaglutide restores endothelial progenitor cell levels in diabetic mice and mitigates high glucose-induced endothelial injury through SIRT1-mediated mitochondrial fission.

Type 2 diabetes mellitus (T2DM) significantly impairs the functionality and number of endothelial progenitor cells (EPCs) and resident endothelial cells, critical for vascular repair and regeneration, exacerbating the risk of vascular complications. GLP-1 receptor agonists, like dulaglutide, have emerged as promising therapeutic agents due to their multifaceted effects, including the enhancement of EPC activity and protection of endothelial cells. This study investigates dulaglutide's effects on peripheral blood levels of CD34+ and CD133+ cells in a mouse model of lower limb ischemia and its protective mechanisms against high-glucose-induced damage in endothelial cells. Results demonstrated that dulaglutide significantly improves blood flow, reduces tissue damage and inflammation in ischemic limbs, and enhances glycemic control. Furthermore, dulaglutide alleviated high-glucose-induced endothelial cell damage, evident from improved tube formation, reduced reactive oxygen species accumulation, and restored endothelial junction integrity. Mechanistically, dulaglutide mitigated mitochondrial fission in endothelial cells under high-glucose conditions, partly through maintaining SIRT1 expression, which is crucial for mitochondrial dynamics. This study reveals the potential of dulaglutide as a therapeutic option for vascular complications in T2DM patients, highlighting its role in improving endothelial function and mitochondrial integrity.

A Zn-MOF-GOx-based cascade nanoreactor promotes diabetic infected wound healing by NO release and microenvironment regulation.

Diabetic wound healing is a great clinical challenge due to the microenvironment of hyperglycemia and high pH value, bacterial infection and persistent inflammation. Here, we develop a cascade nanoreactor hydrogel (Arg@Zn-MOF-GOx Gel, AZG-Gel) with arginine (Arg) loaded Zinc metal organic framework (Zn-MOF) and glucose oxidase (GOx) based on chondroitin sulfate (CS) and Pluronic (F127) to accelerate diabetic infected wound healing. GOx in AZG-Gel was triggered by hyperglycemic environment to reduce local glucose and pH, and simultaneously produced hydrogen peroxide (H2O2) to enable Arg-to release nitric oxide (NO) for inflammation regulation, providing a suitable microenvironment for wound healing. Zinc ions (Zn2+) released from acid-responsive Zn-MOF significantly inhibited the proliferation and biofilm formation of S.aureus and E.coli. AZG-Gel significantly accelerated diabetic infected wound healing by down-regulating pro-inflammatory tumor necrosis factor (TNF)-α and interleukin (IL)-6, up-regulating anti-inflammatory factor IL-4, promoting angiogenesis and collagen deposition in vivo. Collectively, our nanoreactor cascade strategy combining "endogenous improvement (reducing glucose and pH)" with "exogenous resistance (anti-bacterial and anti-inflammatory)" provides a new idea for promoting diabetic infected wound healing by addressing both symptoms and root causes. STATEMENT OF SIGNIFICANCE: A cascade nanoreactor (AZG-Gel) is constructed to solve three key problems in diabetic wound healing, namely, hyperglycemia and high pH microenvironment, bacterial infection and persistent inflammation. Local glucose and pH levels are reduced by GOx to provide a suitable microenvironment for wound healing. The release of Zn2+ significantly inhibits bacterial proliferation and biofilm formation, and NO reduces wound inflammation and promotes angiogenesis. The pH change when AZG-Gel is applied to wounds is expected to enable the visualization of wound healing to guide the treatment of diabetic wound. Our strategy of "endogenous improvement (reducing glucose and pH)" combined with "exogenous resistance (anti-bacterial and anti-inflammatory)" provides a new way for promoting diabetic wound healing.

FGF21 overexpression alleviates VSMC senescence in diabetic mice by modulating the SYK-NLRP3 inflammasome-PPARγ-catalase pathway.

Diabetes accelerates vascular senescence, which is the basis for atherosclerosis and stiffness. The activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and oxidative stress are closely associated with progressive senescence in vascular smooth muscle cells (VSMCs). The vascular protective effect of FGF21 has gradually gained increasing attention, but its role in diabetes-induced vascular senescence needs further investigation. In this study, diabetic mice and primary VSMCs are transfected with an FGF21 activation plasmid and treated with a peroxisome proliferator-activated receptor γ (PPARγ) agonist (rosiglitazone), an NLRP3 inhibitor (MCC950), and a spleen tyrosine kinase (SYK)-specific inhibitor, R406, to detect senescence-associated markers. We find that FGF21 overexpression significantly restores the level of catalase (CAT), vascular relaxation, inhibits the intensity of ROSgreen fluorescence and p21 immunofluorescence, and reduces the area of SA-ß-gal staining and collagen deposition in the aortas of diabetic mice. FGF21 overexpression restores CAT, inhibits the expression of p21, and limits the area of SA-ß-gal staining in VSMCs under high glucose conditions. Mechanistically, FGF21 inhibits SYK phosphorylation, the production of the NLRP3 dimer, the expression of NLRP3, and the colocalization of NLRP3 with PYCARD (ASC), as well as NLRP3 with caspase-1, to reverse the cleavage of PPARγ, preserve CAT levels, suppress ROSgreen density, and reduce the expression of p21 in VSMCs under high glucose conditions. Our results suggest that FGF21 alleviates vascular senescence by regulating the SYK-NLRP3 inflammasome-PPARγ-catalase pathway in diabetic mice.

cGAS suppresses ß-cell proliferation by a STING-independent but CEBPß-dependent mechanism.

AIMS/HYPOTHESIS: cGAS (cyclic GMP-AMP synthase) has been implicated in various cellular processes, but its role in ß-cell proliferation and diabetes is not fully understood. This study investigates the impact of cGAS on ß-cell proliferation, particularly in the context of diabetes. METHODS: Utilizing mouse models, including cGAS and STING (stimulator of interferon genes) knockout mice, we explored the role of cGAS in ß-cell function. This involved ß-cell-specific cGAS knockout (cGASßKO) mice, created by breeding cGAS floxed mice with transgenic mice expressing Cre recombinase under the insulin II promoter. We analyzed cGAS expression in diabetic mouse models, evaluated the effects of cGAS deficiency on glucose tolerance, and investigated the molecular mechanisms underlying these effects through RNA sequencing. RESULTS: cGAS expression is upregulated in the islets of diabetic mice and by high glucose treatment in MIN6 cells. Both global cGAS deficiency and ß-cell-specific cGAS knockout mice lead to improved glucose tolerance by promoting ß-cell mass. Interestingly, STING knockout did not affect pancreatic ß-cell mass, suggesting a STING-independent mechanism for cGAS's role in ß-cells. Further analyses revealed that cGAS- but not STING-deficiency leads to reduced expression of CEBPß, a known suppressor of ß-cell proliferation, concurrently with increased ß-cell proliferation. Moreover, overexpression of CEBPß reverses the upregulation of Cyclin D1 and D2 induced by cGAS deficiency, thereby regulating ß-cell proliferation. These results confirm that cGAS regulation of ß-cell proliferation via a CEBPß-dependent but STING-independent mechanism. CONCLUSIONS/INTERPRETATION: Our findings highlight the pivotal role of cGAS in promoting ß-cell proliferation and maintaining glucose homeostasis, potentially by regulating CEBPß expression in a STING-independent manner. This study uncovers the significance of cGAS in controlling ß-cell mass and identifies a potential therapeutic target for enhancing ß-cell proliferation in the treatment of diabetes.