Mechanisms of diabetic cardiomyopathy and potential therapeutic strategies: preclinical and clinical evidence

Evolution of myocardial steatosis in high cardiovascular risk T2DM patients treated by GLP1 receptor agonists: LICAS study

BACKGROUND

We hypothesized that the reduction of intramyocardial fat content may be involved in the cardioprotective effect of glucagon-like peptide-1 receptor agonists (GLP1-RA) in patients with type 2 diabetes (T2D). Therefore, we aimed to evaluate the change in intramyocardial triglyceride content in T2D patients treated with GLP1-RA.

METHODS

This monocentric proof-of-concept cohort study included patients with unbalanced T2D prior to the introduction of GLP1-RA. Patients underwent cardiac magnetic resonance imaging (MRI) coupled with nuclear magnetic resonance (NMR) spectroscopy at baseline and six months after the introduction (M6) of a GLP1-RA to assess changes in intramyocardial triglyceride levels and morphological, functional, and cardiac tissue parameters. The relative delta (Δr) between baseline and M6 was calculated and analyzed by Student test or sign test.

RESULTS

Twenty-six patients (mean age = 62.2 ± 6.7 years, median HbA1c = 9.1 %) fulfilled inclusion criteria and had both NMR measures. Compared with baseline, relative intramyocardial triglyceride levels significantly decreased after six months of treatment (mean Δr = -26 % [95 %CI:-39; -13]p = 0.003), as well as glycated hemoglobin (HbA1c) (median Δr = -26 % [IQR:25], p < 0.0001), body mass index (BMI) (mean Δr = -6% [-9; -4], p < 0.0001) and left ventricular mass (mean Δr = -6 [-12; -1] p = 0.02). The relative evolution of intramyocardial triglyceride content was not correlated with the relative evolution of HbA1c (r = 0.10) and BMI (r = -0.02).

CONCLUSIONS

We demonstrate a significant reduction in intramyocardial triglyceride content in patients with T2D after six months of treatment with GLP1-RA. The lack of correlation with reductions in HbA1c and BMI suggests a specific effect of GLP1-RA on myocardial steatosis, which might contribute to their previously demonstrated cardiovascular benefits.

Luteolin alleviates diabetic cardiac injury related to inhibiting SHP2/STAT3 pathway

Diabetic cardiomyopathy, a heart disease resulting from diabetes mellitus, inflicts structural and functional damage to the heart. Recent studies have highlighted the potential role of luteolin, a flavonoid, in mitigating diabetic cardiovascular injuries. The Src homology 2-containing protein tyrosine phosphatase 2 (SHP2) is implicated in exacerbating diabetes- and obesity-related complications. Interestingly, luteolin has been shown to inhibit protein tyrosine phosphatases, but it's unclear how SHP2 relates to luteolin's protective effects against diabetic heart disease. Here, we hypothesized that the inhibition of SHP2 signaling could play a role in luteolin's protective action against diabetic heart injury. Diabetes was induced in male Sprague-Dawley rats through a high-fat diet followed by a single intraperitoneal dose of streptozotocin (30 mg/kg). Five weeks post-diabetes induction, these rats were intraperitoneally injected with luteolin at varying doses (5, 10, 20 mg/kg) every other day for an additional 5 weeks. Then cardiac function was assessed, and hearts were isolated for further analysis. We found that luteolin notably improved cardiac function, inhibited cardiac hypertrophy and fibrosis, reduced levels of inflammatory factors and reactive oxygen species, and activated superoxide dismutase. Importantly, luteolin treatment also reduced the expression of SHP2 and phosphorylated signal transducer and activator of transcription 3 (STAT3) in a dose-dependent manner. These findings suggest that luteolin protects the diabetic heart against inflammation, oxidative stress, hypertrophy, and fibrosis, which may relate to down-regulating cardiac SHP2/STAT3 signaling.

L-arginine administration exacerbates myocardial injury in diabetics via prooxidant and proinflammatory mechanisms along with myocardial structural disruption

BACKGROUND

L-arginine (L-Arg) is one of the most widely used amino acids in dietary and pharmacological products. However, the evidence on its usefulness and dose limitations, especially in diabetics is still controversial.

AIM

To investigate the effects of chronic administration of different doses of L-Arg on the cardiac muscle of type 2 diabetic rats.

METHODS

Of 96 male rats were divided into 8 groups as follows (n = 12): Control, 0.5 g/kg L-Arg, 1 g/kg L-Arg, 1.5 g/kg L-Arg, diabetic, diabetic + 0.5 g/kg L-Arg, diabetic + 1 g/kg L-Arg, and diabetic + 1.5 g/kg L-Arg; whereas L-Arg was orally administered for 3 months to all treated groups.

RESULTS

L-Arg produced a moderate upregulation of blood glucose levels to normal rats, but when given to diabetics a significant upregulation was observed, associated with increased nitric oxide, inflammatory cytokines, and malonaldehyde levels in diabetic rats treated with 1 g/kg L-Arg and 1.5 g/kg L-Arg. A substantial decrease in the antioxidant capacity, superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione concentrations, and Nrf-2 tissue depletion were observed at 1 g/kg and 1.5 g/kg L-Arg diabetic treated groups, associated with myocardial injury, fibrosis, α-smooth muscle actin upregulation, and disruption of desmin cardiac myofilaments, and these effects were not noticeable at normal treated groups. On the other hand, L-Arg could significantly improve the lipid profile of diabetic rats and decrease their body weights.

CONCLUSION

L-Arg dose of 1 g/kg or more can exacerbates the diabetes injurious effects on the myocardium, while 0.5 g/kg dose can improve the lipid profile and decrease the body weight.

Microvessel co-transplantation improves poor remuscularization by hiPSC-cardiomyocytes in a complex disease model of myocardial infarction and type 2 diabetes

People with type 2 diabetes (T2D) are at a higher risk for myocardial infarction (MI) than age-matched healthy individuals. Here, we studied cell-based cardiac regeneration post MI in T2D rats modeling the co-morbid conditions in patients with MI. We recapitulated the T2D hallmarks and clinical aspects of diabetic cardiomyopathy using high-fat diet and streptozotocin in athymic rats, which were then subjected to MI and intramyocardial implantation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with or without rat adipose-derived microvessels (MVs). hiPSC-CM alone engrafted poorly. Co-delivery of hiPSC-CMs with MVs yielded a smaller infarct area and a thicker left ventricle wall. Additionally, MVs robustly integrated into the infarcted hearts, improved the survival of hiPSC-CMs, and improved cardiac function. MV-conditioned media also promoted hiPSC-CM maturation in vitro, increasing cardiomyocyte (CM) size in an interleukin (IL)-6-dependent manner. Given the availability of MVs from human adipose tissue, MVs present great translational potential for the treatment of heart failure in people with T2D.

Bioprinting of bespoke islet-specific niches to promote maturation of stem cell-derived islets

Pancreatic islets are densely packed cellular aggregates containing various hormonal cell types essential for blood glucose regulation. Interactions among these cells markedly affect the glucoregulatory functions of islets along with the surrounding niche and pancreatic tissue-specific geometrical organization. However, stem cell (SC)-derived islets generated in vitro often lack the three-dimensional extracellular microenvironment and peri-vasculature, which leads to the immaturity of SC-derived islets, reducing their ability to detect glucose fluctuations and insulin release. Here, we bioengineer the in vivo-like pancreatic niches by optimizing the combination of pancreatic tissue-specific extracellular matrix and basement membrane proteins and utilizing bioprinting-based geometrical guidance to recreate the spatial pattern of islet peripheries. The bioprinted islet-specific niche promotes coordinated interactions between islets and vasculature, supporting structural and functional features resembling native islets. Our strategy not only improves SC-derived islet functionality but also offers significant potential for advancing research on islet development, maturation, and diabetic disease modeling, with future implications for translational applications.

BRG1 Deficiency Promotes Cardiomyocyte Inflammation and Apoptosis by Activating the cGAS-STING Signaling in Diabetic Cardiomyopathy

Brahma-related gene 1 (BRG1) has been implicated in the repair of DNA double-strand breaks (DSBs). Downregulation of BRG1 impairs DSBs repair leading to accumulation of double-stranded DNA (dsDNA). Currently, the role of BRG1 in diabetic cardiomyopathy (DCM) has not been clarified. In this study, we aimed to explore the function and molecular by which BRG1 regulates DCM using mice and cell models. We found that BRG1 was downregulated in the cardiac tissues of DCM mice and in cardiomyocytes cultured with high glucose and palmitic acid (HG/PA), which was accompanied by accumulation of dsDNA and activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. shRNA-mediated Brg1 knockdown aggravated DCM mice cardiac functions, enhanced dsDNA accumulation, cGAS-STING signaling activation, which induced inflammation and apoptosis. In addition, the results were further verified in HG/PA-treated primary neonatal rat cardiomyocytes (NRCMs). Overexpression of BRG1 in NRCMs yielded opposite results. Furthermore, a selective cGAS inhibitor RU.521 or STING inhibitor C-176 partially reversed the BRG1 knockdown-induced inflammation and apoptosis in vitro. In conclusion, our results demonstrate that BRG1 is downregulated during DCM in vivo and in vitro, resulting in cardiomyocyte inflammation and apoptosis due to dsDNA accumulation and cGAS-STING signaling activation. Therefore, targeting the BRG1-cGAS-STING pathway may represent a novel therapeutic strategy for improving cardiac function of patients with DCM.

Insight into the cardioprotective effects of melatonin: shining a spotlight on intercellular Sirt signaling communication

Cardiovascular diseases (CVDs) are the leading causes of death and illness worldwide. While there have been advancements in the treatment of CVDs using medication and medical procedures, these conventional methods have limited effectiveness in halting the progression of heart diseases to complete heart failure. However, in recent years, the hormone melatonin has shown promise as a protective agent for the heart. Melatonin, which is secreted by the pineal gland and regulates our sleep-wake cycle, plays a role in various biological processes including oxidative stress, mitochondrial function, and cell death. The Sirtuin (Sirt) family of proteins has gained attention for their involvement in many cellular functions related to heart health. It has been well established that melatonin activates the Sirt signaling pathways, leading to several beneficial effects on the heart. These include preserving mitochondrial function, reducing oxidative stress, decreasing inflammation, preventing cell death, and regulating autophagy in cardiac cells. Therefore, melatonin could play crucial roles in ameliorating various cardiovascular pathologies, such as sepsis, drug toxicity-induced myocardial injury, myocardial ischemia-reperfusion injury, hypertension, heart failure, and diabetic cardiomyopathy. These effects may be partly attributed to the modulation of different Sirt family members by melatonin. This review summarizes the existing body of literature highlighting the cardioprotective effects of melatonin, specifically the ones including modulation of Sirt signaling pathways. Also, we discuss the potential use of melatonin-Sirt interactions as a forthcoming therapeutic target for managing and preventing CVDs.

Empagliflozin in diabetic cardiomyopathy: elucidating mechanisms, therapeutic potentials, and future directions

Diabetic cardiomyopathy (DCM) represents a significant health burden, exacerbated by the global increase in type 2 diabetes mellitus (T2DM). This condition contributes substantially to the morbidity and mortality associated with diabetes, primarily through myocardial dysfunction independent of coronary artery disease. Current treatment strategies focus on managing symptoms rather than targeting the underlying pathophysiological mechanisms, highlighting a critical need for specific therapeutic interventions. This review explores the multifaceted role of empagliflozin, a sodium-glucose cotransporter 2 (SGLT-2) inhibitor, in addressing the complex etiology of DCM. We discuss the key mechanisms by which hyperglycemia contributes to cardiac dysfunction, including oxidative stress, mitochondrial impairment, and inflammation, and how empagliflozin mitigates these effects. Empagliflozin's effects on reducing hospitalization for heart failure and potentially lowering cardiovascular mortality mark it as a promising candidate for DCM management. By elucidating the underlying mechanisms through which empagliflozin operates, this review underscores its therapeutic potential and paves the way for future research into its broader applications in diabetic cardiac care. This synthesis aims to foster a deeper understanding of DCM and encourage the integration of empagliflozin into treatment paradigms, offering hope for improved outcomes in patients suffering from this debilitating condition.

Multi-omics mechanical analysis of gut microbiota, carboxylic acids, and cardiac gene expression interaction triggering diabetic cardiomyopathy

It is well known that gut microbial imbalance is a potential factor for the occurrence and development of diabetes mellitus (DM) and its complications. Moreover, the heart and gut microbiota can regulate each other through the gut-metabolite-heart axis. In this study, metagenomics, metabolomics, and transcriptomics were chosen to sequence the changes in gut microbiota, serum metabolite levels, and differentially expressed genes (DEGs) in leptin receptor-deficient db/db mice and analyze the correlation between serum metabolites and gut microbiota or DEGs. According to the results, there were significant differences in the 1,029 cardiac genes and 353 serum metabolites in diabetic mice of the db/db group, including DEGs enriched in the PPAR signaling pathway and increased short-chain carboxylic acids (CAs), when compared with the normal db/m group. According to metagenomics, the gut microbiota of mice in the db/db group were disrupted, and particularly Lachnospiraceae bacteria and Oscillospiraceae bacteria significantly decreased. Also, according to the Pearson correlation analysis, a significant positive correlation was found between CAs and PPAR signaling pathway-related DEGs, and a negative correlation was found between CAs and the abundance of the above-mentioned species. To sum up, type 2 diabetes mellitus (T2DM) can upregulate the expression of partial cardiac genes through the levels of serum short-chain CAs affected by gut microbiota, thus playing a role in the occurrence and development of diabetic cardiomyopathy (DCM).

IMPORTANCE

Our research results clearly link the changes in heart genes of T2DM and normal mice with changes in serum metabolites and gut microbiota, indicating that some genes in biological processes are closely related to the reduction of protective microbiota in the gut microbiota. This study provides a theoretical basis for investigating the mechanism of DCM and may provide preliminary evidence for the future use of gut microbiota therapy for DCM.

Echocardiographic phenotypes of diabetic myocardial disorder: evolution over 15 months follow-up in the ARISE-HF trial

BACKGROUND

Diabetic myocardial disorder (DbMD, evidenced by abnormal echocardiography or cardiac biomarkers) is a form of stage B heart failure (SBHF) at high risk for progression to overt HF. SBHF is defined by abnormal LV morphology and function and/or abnormal cardiac biomarker concentrations.

OBJECTIVE

To compare the evolution of four DbMD groups based on biomarkers alone, systolic and diastolic dysfunction alone, or their combination.

METHODS

The Aldose Reductase Inhibition for Stabilization of Exercise Capacity in Heart Failure (ARISE-HF) trial was a Phase 3 randomised trial of an aldose reductase inhibitor in patients with well-controlled type 2 diabetes mellitus (T2DM). The 1858 potential participants (age 67 ± 7 years; 50% women) were screened for SBHF based on abnormal echocardiography or biomarkers (N-terminal pro-B-type natriuretic peptide ≥ 40 ng/L or high sensitivity cardiac troponin T ≥ 10 ng/L [women] and ≥ 16 ng/L [men]). Exercise capacity (peak VO2) was reduced in 669 with DbMD (age 68 ± 7, 50% women), and peak VO2 was reassessed at 15 months.

RESULTS

The 1463 (79%) participants with DbMD were allocated to four clusters; 907 (49%) showed isolated elevation of cardiac biomarkers, 301 (16%) with systolic dysfunction/hypertrophy, 162 (9%) with diastolic dysfunction and 93 (5%) comprised an overlap cluster (combined diastolic, systolic or LV geometric abnormalities). Reduced VO2 (< 75% predicted) was present in 669 (46%); 72% of those with both systolic and diastolic dysfunction, 56% of those with systolic dysfunction and LVH, 53% of those with diastolic dysfunction and 38% with biomarkers alone (p < 0.0001). In 669 patients followed over 15 months, there was a similar small decrement in VO2 in all groups.

CONCLUSIONS

Among individuals with T2DM and SBHF, reduced functional capacity is most prevalent in those with multiple physiological disturbances. However, there was no difference between phenogroups in the evolution of exercise intolerance.

TRIAL REGISTRATION

ARISE-HF, NCT04083339.

Daphnetin ameliorates diabetic cardiomyopathy by regulating inflammation and endoplasmic reticulum stress-induced apoptosis

Daphnetin has been demonstrated to exert beneficial effects on diabetes mellitus and renal complications. However, the role and molecular mechanism of daphnetin in diabetic cardiomyopathy (DCM) remain unclear. In this study, rats were injected with streptozotocin (STZ) to induce diabetes. The diabetic rats were then administered daphnetin (1 and 4 mg/kg) or dimethyl sulfoxide (DMSO) daily for 12 weeks. The results demonstrated that the diabetic rats exhibited elevated blood glucose levels, which were dose-dependently ameliorated by daphnetin. At 13 weeks following STZ injection, the rats exhibited typical diabetic signs, cardiac dysfunction, and evident pathological alterations in myocardial tissues. The administration of daphnetin to diabetic rats resulted in improvement in cardiac function, reductions in myocardial injury biomarkers, and the inhibition of myocardial fibrosis. Furthermore, daphnetin treatment suppressed inflammation and endoplasmic reticulum stress-induced apoptosis in a dose-dependent manner. Additionally, daphnetin exhibited partial blockade of the activation of mitogen-activated protein kinase pathways induced by diabetes. These findings indicate that daphnetin may be a promising therapeutic agent for the treatment of DCM.

Vitamin D and exercise improve VEGF-B production and IGF-1 levels in diabetic rats: insights the role of miR-1 suppression

BACKGROUND

Type 2 Diabetes Mellitus (T2DM) is closely associated with the development of vascular damage in the heart. In this study, the researchers aimed to determine whether Aerobic Training (AT) and Vitamin D supplementation (Vit D) could alleviate heart complications and vascular damage caused by diabetes. The effects of an eight-week AT program and Vit D on the expression of miR-1, IGF-1 genes, and VEGF-B in the cardiomyocytes of rats with T2DM.

METHODS

This study was an experimental investigation. Fifty male Wistar rats were divided into 2 groups Non-Diabetic Obese Control (NC; n = 10), and diabetic (n = 40). The rats were then randomly divided into four groups: AT plus Vit D (AT + Vit D; n-=10), AT (n = 10), Vit D (Vit D; n = 10), and Control Diabetic (C; n = 10). The exercise groups underwent treadmill training for 8 weeks at an aerobic intensity equal to 50-60% of their maximal oxygen uptake (VO2max), which corresponded to a speed of 15-25 m/min at a 0% incline, for 30-60 min per day, 5 days per week. The Vit D and AT + Vit D groups received 5,000 international units (IU) of Vitamin D (combined with sesame oil) per week via a single-dose injection. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test for multiple comparisons among the groups. Paired data were analyzed using paired t-tests.

RESULTS

The results showed that BW, BMI, and FI significantly decreased in the AT + Vit D (p = 0.001 for all variables), AT (p = 0.001 for all variables), and Vit D (p = 0.001 for all variables) groups compared to baseline. In contrast, BW, BMI, and FI increased in the C (p = 0.001, p = 0.006, p = 0.020, respectively) and NC (p = 0.001 for all variables) groups. Significant differences were observed between the groups in terms of visceral fat, insulin, glucose, and HOMA-IR (p = 0.001 for all variables). Serum 25-hydroxyvitamin D levels varied significantly among the groups (p = 0.002). The AT + Vit D group showed significantly increased VEGF-B (p = 0.001 for both comparisons), upregulated IGF-1 (p = 0.001 for both comparisons), and downregulated miR-1 (p = 0.001 for both comparisons) compared to the AT and Vit D groups, respectively.

CONCLUSIONS

AT and Vit D increased the expression of IGF-1 and VEGF-B in the heart of T2DM rats while decreasing the expression of miR-1. These effects were more pronounced when AT and Vit D were combined. The study concludes that the combination of AT and Vit D has cardio-protective effects in T2DM rats, counteracting abnormal angiogenesis induced by diabetes. These effects are mediated, at least in part, by the upregulation of IGF-1 and VEGF-B, and the downregulation of miR-1.

Effects of exercise intensity and diet on cardiac tissue structure and FGF21/β-Klotho signaling in type 2 diabetic mice: a comparative study of HFD and HFD + STZ induced type 2 diabetes models in mice

BACKGROUND

Structural heart disease is one of the leading causes of death in people with type 2 diabetes (T2D), which is not known to have an effect on exercise training. The aim of this study was to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on heart tissue structure, the serum level of FGF21 and the heart tissue level of β-Klotho, an FGF21 coreceptor, in HFD and HFD + STZ-induced diabetic mice.

METHODS

Thirty-six male C57BL/6J mice were divided into high-fat diet (HFD) and normal chow diet (ND) groups. After 20 weeks of diet, the HFD mice were divided into HFD and HFD + STZ groups, and the latter group was injected with STZ. Then, the mice in the ND, HFD and HFD + STZ groups were divided into three subgroups of control (C), HIIT and MICT, and mice were placed in one of nine groups ND-C, ND-HIIT, ND-MICT, HFD-C, HFD-HIIT, HFD-MICT, HFD + STZ-C, HFD + STZ-HIIT, and HFD + STZ-MICT. The mice in the exercise training (ET) groups were run on a treadmill for eight weeks. Finally, the tissue and serum samples were collected and analyzed by two-way ANOVA.

RESULTS

Statistical analyses showed that the main effect of diabetes inducing model (DIM) was significant for all variables (p < 0.05), except vascular density (p = 0.055); the main effect of ET type on fasting blood glucose and FGF21 was significant (p < 0.001); and the interaction was significant for fasting blood glucose, heart weight and FGF21 (p < 0.001). Post hoc and subgroup analysis showed a superior effect of MICT over HIIT in decreasing fasting blood glucose and serum level of FGF21 (p < 0.001). Additionally, the results of the myocardial tissue qualitative analyses differed between the diabetic mouse models and the ET groups.

CONCLUSIONS

In a mouse model, type 2 diabetes can negatively affect heart tissue structure and FGF21 signaling in cardiac tissue, and both HIIT and MICT can prevent this effect. However, MICT likely more effective that HIIT in reducing circulating FGF21.

N6-methyladenosine modification of SPOP relieves ferroptosis and diabetic cardiomyopathy by enhancing ubiquitination of VDAC3

Understanding the pathogenesis of diabetic cardiomyopathy (DCM), a common microvascular complication affecting the heart, is crucial for identifying new therapeutic targets and intervention strategies for DCM. Our study revealed a significant downregulation in Speckle-type POZ protein (SPOP) expression in DCM, while the overexpression of SPOP improved DCM-induced myocardial dysfunction, injury, fibrosis, hypertrophy, and ferroptosis. Mechanistically, SPOP facilitated the degradation of voltage-dependent anion channel 3 (VDAC3) by enhancing its ubiquitination. M6A demethylase AlkB homolog 5 (ALKBH5) reduced the mRNA stability of SPOP by decreasing m6A modification in its 3'UTR. The m6A reader insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) enhanced the stability of SPOP mRNA through recognition of m6A-modified SPOP 3'UTR. Furthermore, ALKBH5 promoted ferroptosis by inhibiting SPOP-induced VDAC3 degradation, while IGF2BP2 inhibited ferroptosis via activation of SPOP-induced VDAC3 degradation in high glucose-treated neonatal mouse ventricular cardiomyocytes (NMVCs). Overall, our study has unveiled a novel role of SPOP in the pathogenesis of ferroptosis and DCM, thereby significantly advancing our understanding of the involvement of ferroptosis during the progression of DCM. Moreover, this discovery offers promising potential therapeutic interventions targeting DCM.

Impaired Iron-Sulfur Cluster Synthesis Induces Mitochondrial PARthanatos in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM), a severe complication of diabetes, is characterized by mitochondrial dysfunction, oxidative stress, and DNA damage. Despite its severity, the intrinsic factors governing cardiomyocyte damage in DCM remain unclear. It is hypothesized that impaired iron-sulfur (Fe-S) cluster synthesis plays a crucial role in the pathogenesis of DCM. Reduced S-sulfhydration of cysteine desulfurase (NFS1) is a novel mechanism that contributes to mitochondrial dysfunction and PARthanatos in DCM. Mechanistically, hydrogen sulfide (H2S) supplementation restores NFS1 S-sulfhydration at cysteine 383 residue, thereby enhancing Fe-S cluster synthesis, improving mitochondrial function, increasing cardiomyocyte viability, and alleviating cardiac damage. This study provides novel insights into the interplay between Fe-S clusters, mitochondrial dysfunction, and PARthanatos, highlighting a promising therapeutic target for DCM and paving the way for potential clinical interventions to improve patient outcomes.

Advances in diabetic cardiomyopathy: current and potential management strategies and emerging biomarkers

Background

Diabetic cardiomyopathy (DCM) is a significant complication of diabetes mellitus (DM) and a major contributor to heart failure (HF). Despite its prevalence and impact, there is a notable lack of targeted therapies, highlighting the need for ongoing research into novel treatment strategies. Current management primarily involves blood sugar control, lifestyle modifications, and addressing risk factors. Conventional treatments, including Renin-angiotensin-aldosterone system (RAAS) inhibitors, angiotensin receptor/neprilysin inhibitor, beta-blockers, ivabradine, and vericiguat, are also employed.

Methodology

A comprehensive search was made using PubMed, Scopus, and Google Scholar for studies published. The search focused on DCM, therapeutic strategies, and emerging biomarkers. Articles were selected based on relevance, study quality, and inclusion criteria, which emphasized peer-reviewed studies on DCM management and biomarker identification.

Results and discussion

Our review reveals that targeting oxidative stress through these antioxidant therapies offers a promising approach for limiting DCM progression. Clinical trials provide evidence supporting the efficacy of these agents in reducing oxidative damage and improving cardiac function in diabetes-induced cardiomyopathy.

Conclusion

The current landscape of DCM management highlights the need for novel therapeutic strategies and early detection methods. Antioxidant therapies show potential for addressing the oxidative stress that underlies DCM, and ongoing research into emerging biomarkers may offer new avenues for early diagnosis and treatment.

The role of m6A modification in cardiovascular disease: A systematic review and integrative analysis

BACKGROUND AND AIMS

This study focused on the recent advancements in understanding the association between N6-methyladenosine (m6A) modification and cardiovascular disease (CVD).

METHODS

The potential mechanisms of m6A related to CVD were summarized by literature review. Associations between m6A levels and CVD were explored across 8 electronic databases: PubMed, Embase, Web of Science, Cochrane Library, Sinomed, Wan Fang, CNKI, and Vip. Standard mean difference (SMD) and 95 % confidence interval (95 % CI) were calculated to assess the total effect in integrated analysis.

RESULTS

The systematic review summarized previous studies on the association between m6A modification and CVD, highlighting the potential role of m6A in CVD progression. A total of 11 studies were included for integrative analysis. The mean m6A levels were significantly higher in CVD than those in normal controls (SMD = 1.86, 95 % CI: 0.16-3.56, P < 0.01).

CONCLUSIONS

This systematic review provided new targets for early detection and treatment for CVD. And the integrated analysis showed that increased level of m6A was associated with CVD.

Uncovering the molecular networks of ferroptosis in the pathogenesis of type 2 diabetes and its complications: a multi-omics investigation

BACKGROUND

Diabetes is a multi-factorial disorder and related complications constitute one of the principal causes of global mortality and disability. The role of ferroptosis in diabetes and its complications is intricate and significant. This study endeavors to disclose the role of ferroptosis in the aforementioned diseases from multiple perspectives through multi-omics.

METHODS

We performed genetic correlation analyses via the Linkage Disequilibrium Score and High-Definition Likelihood approaches for type 2 diabetes (T2D) and its complications. The data concerning the expression of ferroptosis-related genes (FRGs) were obtained from the meta-analysis of studies on gene expression and protein abundance. Mendelian randomization analyses and cross-validation were implemented using the discovery cohort, replication cohort, and imaging genomics cohort of T2D and its complications. Moreover, we conducted colocalization analyses on T2D and tissue-specific single-cell RNA sequencing investigations on the complications to complement the results.

RESULTS

Genetic association analysis indicated that the selected datasets could be incorporated into a secondary analysis of T2D complications. In the primary analysis, six FRGs (CDKN1A, ENO3, FURIN, RARRES2, TYRO3, and YTHDC2) were found to be positively associated with T2D risk. Conversely, eight FRGs (ARNTL, CAMKK2, CTSB, FADS2, KDM5A, MEG3, SREBF1, and STAT3) were inversely associated with T2D risk. The 14 FRGs were included in the secondary analysis. Within the FRGs, which received full support from both the discovery and replication cohorts, and were further validated by imaging genomics, higher levels of CDKN1A were positively associated with DKD risk. Higher levels of CAMKK2 and KDM5A were associated with a decreased risk of DKD. For DCM, higher levels of CTSB were positively associated with DCM risk. And genetically predicted higher levels of ARNTL and SREBF1 were associated with a decreased risk of NAFLD. Finally, we validated the tissue-specific expression of each complication with scRNA-seq datasets.

CONCLUSIONS

This study identified FRGs in relation to T2D and its complications, which may enhance the understanding of the pathogenic mechanisms of their development. Meanwhile, it offers cross-validation for imaging genomics and further indicates the direction for non-invasive diagnosis.

GYY4137 protects against type 2 diabetes mellitus-associated myocardial autophagy by suppressing FOXO1 signal pathway

Purpose: Diabetic cardiomyopathy (DCM) is a major complication of type 2 diabetes mellitus (T2DM), but its effective prevention and treatment are still limited. We investigated the effects of GYY4137, a slow-releasing hydrogen sulfide donor, and its downstream mediator forkhead box protein O1 (FOXO1) on T2DM-associated DCM. Methods: In vivo, T2DM mice were induced by a high-fat diet coupled with streptozotocin injection. Intragastric administration of GYY4137 was also performed. In vitro, AC16 cardiomyocytes were treated with glucose and palmitate to mimic high-glucose and high-fat (HGHF) conditions, in which GYY4137 or a FOXO1 inhibitor (AS1842856) was also introduced. Bioinformatics analysis was performed using public GEO datasets. Results: GYY4137 demonstrated a protective effect against cardiac dysfunction, fibrosis, and autophagy in cardiac tissues of T2DM mice. Moreover, GYY4137 alleviated cell injury and lipid accumulation in HGHF-treated AC16 cells. In both in vivo and in vitro models, hyperactivation of autophagy was dampened by GYY4137. Bioinformatic analysis revealed the potential role of the FOXO pathway and autophagy in DCM. Further experiments showed that GYY4137 rescued diabetes-induced overexpression of FOXO1. AS1842856 displayed a notable capacity to shield cardiomyocytes against diabetes-induced injury similar to that achieved by GYY4137. Conclusion: GYY4137 protected against cardiac dysfunction and fibrosis in T2DM mice, and the mechanism might involve suppression of FOXO1-induced autophagy.

Challenging directions in pediatric diabetes - the place of oxidative stress and antioxidants in systemic decline

Diabetes is a complex condition with a rising global incidence, and its impact is equally evident in pediatric practice. Regardless of whether we are dealing with type 1 or type 2 diabetes, the development of complications following the onset of the disease is inevitable. Consequently, contemporary medicine must concentrate on understanding the pathophysiological mechanisms driving systemic decline and on finding ways to address them. We are particularly interested in the effects of oxidative stress on target cells and organs, such as pancreatic islets, the retina, kidneys, and the neurological or cardiovascular systems. Our goal is to explore, using the latest data from international scientific databases, the relationship between oxidative stress and the development or persistence of systemic damage associated with diabetes in children. Additionally, we highlight the beneficial roles of antioxidants such as vitamins, minerals, polyphenols, and other bioactive molecules; in mitigating the pathogenic cascade, detailing how they intervene and their bioactive properties. As a result, our study provides a comprehensive exploration of the key aspects of the oxidative stress-antioxidants-pediatric diabetes triad, expanding understanding of their significance in various systemic diseases.

Recent Trends in Advanced Glycation End Products in Foods: Formation, Toxicity, and Innovative Strategies for Extraction, Detection, and Inhibition

Advanced glycation end products (AGEs) are produced in foods during their thermal treatment through routes like the Maillard reaction. They have been linked to various health issues such as diabetes, neurodegenerative disorders, and cardiovascular diseases. There are multiple pathways through which AGEs can form in foods and the body. Therefore, this review work aims to explore multiple formation pathways of AGEs to gain insights into their generation mechanisms. Furthermore, this review work has analyzed the recent trends in the detection and inhibition of AGEs in food matrices. It can be highlighted, based on the surveyed literature, that UHPLC-Orbitrap-Q-Exactive-MS and UPLC-ESI-MS/MS can produce highly sensitive results with a low limit of detection levels for AGEs in food matrices. Moreover, various works on inhibitory agents like spices, herbs, fruits, vegetables, hydrocolloids, plasma-activated water, and probiotic bacteria were assessed for their capacity to suppress the formation of AGEs in food products and simulation models. Overall, it is essential to decrease the occurrence of AGEs in food products, and future scope might include studying the interaction of macromolecular components in food products to minimize the production of AGEs without sacrificing the organoleptic qualities of processed foods.

Down-regulation of HSPB1 and MGST1 promote ferroptosis and impact immune infiltration in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a leading cause of death in diabetic patients. Current therapies do not adequately resolve this problem and focus only on the optimal level of blood glucose for patients. Ferroptosis plays an important role in diabetes mellitus and cardiovascular diseases. However, the role of ferroptosis in DCM remains unclear. Differentially expressed ferroptosis-related genes (DE-FRGs) were identified by intersecting GSE26887 dataset and the Ferroptosis Database (FerrDb). The associations between the DE-FRGs and immune cells in DCM, estimated by CIBERSORTx algorithm, were analyzed. Using ow cytometry (FCM) to evaluated the infiltration of immune cells of myocardial tissues. The expression of DE-FRGs, Glutathione peroxidase 4 (GPX4) and Solute carrier family 7 member 11 (SLC7A11) were examined by real-time quantitative PCR and western blotting. 3 DE-FRGs were identified, which are Heat shock protein family B (small) member 1 (HSPB1), Microsomal glutathione S-transferase 1 (MGST1) and solute carrier family 40 member 1 (SLC40A1) respectively, and they were closely linked to immune cells in DCM. In vivo, the levels of CD8 + T cells, B cells and Treg cells were significantly decreased in the DCM group, while the levels of CD4 + T cells, M1 cells, M2 cells and monocytes were increased. Diabetes significantly decreased HSPB1 and MGST1 levels and increased ferroptosis compared to normal group. Furthermore, ferroptosis inhibitor ferrostatin-1 (Fer-1) alleviated high-fat diet (HFD)-induced cadiomyocyte injury and rescued the ferroptosis. This study suggests that ferroptosis related gene HSPB1 and MGST1 are closely related to immune cell infiltration, which may become therapeutic targets for DCM.

Elevated whole blood viscosity is associated with an impaired insulin-stimulated myocardial glucose metabolism

BACKGROUND

Increased whole blood viscosity (WBV) was associated with impaired peripheral glucose metabolism, type 2 diabetes, and cardiovascular disease (CVD). Impaired myocardial glucose metabolism is a risk factor for CVD. Whether an increased WBV is associated with impaired myocardial glucose metabolism is still undefined.

METHODS

To elucidate this issue, we evaluated the association between WBV and myocardial glucose metabolic rate (MRGlu) in 57 individuals with different glucose tolerance status. Myocardial MRGlu was assessed using dynamic cardiac 18F-FDG PET combined with euglycemic hyperinsulinemic clamp. WBV was calculated using a validated equation including hematocrit and plasma proteins: WBV = [0.12 × h] + [0.17 × (p - 2.07)], where h is the hematocrit (%) and p the plasma proteins (g/dl). The subjects were stratified into tertiles according to their myocardial MrGlu values.

RESULTS

As compared with individuals in the highest myocardial MrGlu tertile, those in the lowest tertile showed an age-adjusted increase in WBV (5.54 ± 0.3 cP vs. 6.13 ± 0.4 cP respectively; P = 0.001), hematocrit (39.1 ± 3.1% vs. 43.2 ± 3.7% respectively; P = 0.004), and total proteins (7.06 ± 0.3 g/l vs. 7.60 ± 0.3 g/l respectively; P < 0.0001). WBV was negatively correlated with myocardial MRGlu (r = - 0.416, P = 0.001). In a stepwise multivariate regression analysis, including several cardiovascular risk factors, the only variables significantly associated with myocardial MrGlu were WBV (β - 0.505; P < 0.0001), fasting insulin (β - 0.346; P = 0.004), fasting plasma glucose (β - 0.287; P = 0.01), and sex (β 0.280; P = 0.003) explaining the 69.6% of its variation.

CONCLUSIONS

The current study showed a strongly association between an increase of WBV and an impaired myocardial glucose metabolism in individuals with a broad spectrum of glucose tolerance.

Understanding Diabetic Cardiomyopathy: Insulin Resistance and Beyond

Background: Diabetic cardiomyopathy (DC) is a syndrome of heart failure occurring in patients with diabetes mellitus (DM), independent of other risk factors. It is a relatively underdiagnosed condition with a prolonged subclinical phase. There is an abundance of studies put forward to explain the underlying pathogenic mechanisms observed in this condition. This review aims to summarize the evidence available in contemporary medical literature with regard to the molecular mechanisms, abnormalities in signalling and metabolism and structural and functional abnormalities manifesting as DC. Methods: We conducted a literature search using the terms 'diabetic cardiomyopathy', 'heart failure AND Diabetes mellitus', 'Cardiomyopathy AND Diabetes mellitus'. We searched the reference lists of included studies and relevant systematic reviews. Results: In this review, we elucidate all the mechanisms that have been postulated to have a role in the pathogenesis of DC, in addition to insulin resistance, such as inflammation, renin-angiotensin-aldosterone system activation and deranged protein homeostasis. Conclusions: DC is an underrecognized cardiac complication of DM. A comprehensive knowledge of all the pathways and mediators will aid in the development of diagnostic and prognostic markers, screening protocols and novel management strategies.

Diabetes mellitus disrupts lncRNA Malat1 regulation of cardiac mitochondrial genome-encoded protein expression

Understanding the cellular mechanisms behind diabetes-related cardiomyopathy is crucial as it is a common and deadly complication of diabetes mellitus. Dysregulation of the mitochondrial genome has been linked to diabetic cardiomyopathy and can be ameliorated by altering microRNA (miRNA) availability in the mitochondrion. Long noncoding RNAs (lncRNAs) have been identified to downregulate miRNAs. This study aimed to determine if diabetes mellitus impacts the mitochondrial localization of lncRNAs, their interaction with miRNAs, and how this influences mitochondrial and cardiac function. In mouse and human nondiabetic and type 2 diabetic cardiac tissue, RNA was isolated from purified mitochondria and sequenced (Ilumina HiSeq). Malat1 was significantly downregulated in both human and mouse cardiac mitochondria. The use of a mouse model with an insertional deletion of Malat1 transcript expression resulted in exacerbated systolic and diastolic dysfunction when evaluated in conjunction with a high-fat diet. The cardiac effects of a high-fat diet were countered in a mouse model with transgenic overexpression of Malat1. MiR-320a, a miRNA that binds to both mitochondrial genome-encoded gene NADH-ubiquinone oxidoreductase chain 1 (MT-ND1) as well as Malat1, was upregulated in human and mouse diabetic mitochondria. Conversely, MT-ND1 was downregulated in human and mouse diabetic mitochondria. Mice with an insertional inactivation of Malat1 displayed increased recruitment of both miR-320a and MT-ND1 to the RNA-induced silencing complex (RISC). In vitro pulldown assays of Malat1 fragments with conserved secondary structure confirmed binding capacity for miR-320a. In vitro Seahorse assays indicated that Malat1 knockdown and miR-320a overexpression impaired overall mitochondrial bioenergetics and Complex I functionality. In summary, the disruption of Malat1 presence in mitochondria, as observed in diabetic cardiomyopathy, is linked to cardiac dysfunction and mitochondrial genome regulation.NEW & NOTEWORTHY Currently, there is no known mechanism for the development of diabetes-related cardiac dysfunction. Previous evaluations have shown that mitochondria, specifically mitochondrial genome-encoded transcripts, are disrupted in diabetic cardiac cells. This study explores the presence of long noncoding RNAs (lncRNAs) such as Malat1 in cardiac mitochondria and how that presence is impacted by diabetes mellitus. Furthermore, this study will examine how the loss of Malat1 results in bioenergetic and cardiac dysfunction through mitochondrial transcriptome dysregulation.

Role for the F-box proteins in heart diseases

The maintenance of cardiac homeostasis necessitates proper protein turnover, which is regulated by the ubiquitin-proteasome system. F-box proteins are one type of E3 ubiquitin ligases, and accumulating evidence suggests that dysregulation of FBPs exacerbates heart diseases. Therefore, in this review, we summarized the F-box proteins present in the heart, which can be divided into three types based on their repeated sequences, namely FBXO (Fbxo32, Fbxo25, Fbxo44, Fbxo27 and Fbxo28), FBXW (Fbxw7 and Fbxw5), and FBXL (Fbxl1, Fbxl10, Fbxl16 and Fbxl2). Moreover, the physiological and pathological roles and the functional mechanisms of these F-box proteins were elucidated within the cardiac context, providing new theories and strategies for the prevention and treatment of heart diseases.

Automated echocardiographic diastolic function grading: A hybrid multi-task deep learning and machine learning approach

BACKGROUND

Assessing left ventricular diastolic function (LVDF) with echocardiography as per ASE guidelines is tedious and time-consuming. The study aims to develop a fully automatic approach of this procedure by a lightweight hybrid algorithm combining deep learning (DL) and machine learning (ML).

METHODS

The model features multi-modality input and multi-task output, measuring LV ejection fraction (LVEF), left atrial end-systolic volume (LAESV), and Doppler parameters: mitral E wave velocity (E), A wave velocity (A), mitral annulus e' velocity (e'), and tricuspid regurgitation velocity (TRmax). The algorithm was trained and tested on two internal datasets (862 and 239 echocardiograms) and validated using three external datasets, including EchoNet-Dynamic and CAMUS. The ASE diastolic function decision tree and total probability theory were used to provide diastolic grading probabilities.

RESULTS

The algorithm, named MMnet, demonstrated high accuracy in both test and validation datasets, with Dice coefficients for segmentation between 0.922 and 0.932 and classification accuracies between 0.9977 and 1.0. The mean absolute errors (MAEs) for LVEF and LAESV were 3.7 % and 5.8 ml, respectively, and for LVEF in external validation, MAEs ranged from 4.9 % to 5.6 %. The diastolic function grading accuracy was 0.88 with hard criteria and up to 0.98 with soft criteria which account for the top two probability in total probability theory.

CONCLUSIONS

MMnet can automatically grade ASE diastolic function with high accuracy and efficiency by annotating 2D videos and Doppler images.

Ghrelin inhibits myocardial pyroptosis in diabetic cardiomyopathy by regulating ERS and NLRP3 inflammasome crosstalk through the PI3K/AKT pathway

AIMS

Endoplasmic reticulum stress(ERS) can induce inflammation mediated by NLRP3 inflammatory bodies and link inflammation with oxidative stress in myocardial tissue. Ghrelin is an endogenous growth hormone-releasing peptide that has been proven to have multiple effects, such as regulating energy metabolism and inhibiting inflammation. However, the role of ghrelin in myocardial injury in diabetic rats and the mechanism have not been reported.

RESULTS

We found that ghrelin could improve endoplasmic reticulum stress and inflammatory pyroptosis in the myocardial tissue of diabetic rats and reduce ERS and NLRP3 inflammasome crosstalk in H9C2 cardiomyocytes. Interestingly, ghrelin could activate the PI3K/AKT signalling pathway, playing a role in inhibiting endoplasmic reticulum stress and reducing the expression of pyroptosis-related proteins. However, these protective effects could be largely eliminated by LY294002.

CONCLUSIONS

In summary, we demonstrated that ghrelin inhibited myocardial pyroptosis in diabetic cardiomyopathy by regulating ERS and NLRP3 inflammasome crosstalk through the PI3K/AKT pathway. Our results provide new insights into the mechanism of diabetic myocardial injury induced by high glucose and high palmitic acid and ghrelin-mediated anti-inflammatory protection and provide potential therapeutic targets and strategies for diabetic cardiomyopathy.

The interregulatory circuit between non-coding RNA and apoptotic signaling in diabetic cardiomyopathy

Diabetes mellitus has surged in prevalence, emerging as a prominent epidemic and assuming a foremost position among prevalent medical disorders. Diabetes constitutes a pivotal risk element for cardiovascular maladies, with diabetic cardiomyopathy (DCM) standing out as a substantial complication encountered by individuals with diabetes. Apoptosis represents a physiological phenomenon observed throughout the aging and developmental stages, giving rise to the programmed cell death, which is implicated in DCM. Non-coding RNAs assume significant functions in modulation of gene expression. Their deviant expression of ncRNAs is implicated in overseeing diverse cellular attributes such as proliferation, apoptosis, and has been postulated to play a role in the progression of DCM. Notably, ncRNAs and the process of apoptosis can mutually influence and cooperate in shaping the destiny of human cardiac tissues. Therefore, the exploration of the interplay between apoptosis and non-coding RNAs holds paramount importance in the formulation of efficacious therapeutic and preventive approaches for managing DCM. In this review, we provide a comprehensive overview of the apoptotic signaling pathways relevant to DCM and subsequently delve into the reciprocal regulation between apoptosis and ncRNAs in DCM. These insights contribute to an enhanced comprehension of DCM and the development of therapeutic strategies.

Association between triglyceride-glucose index and the risk of heart failure hospitalization in older diabetic patients received right ventricular pacing: a retrospective cohort study

BACKGROUND

The prognostic value of triglyceride-glucose (TyG) index is not yet known for older diabetic patients received right ventricular pacing (RVP). We aimed to investigate the association between TyG index and the risk of heart failure hospitalization (HFH) in older diabetic patients received RVP.

METHODS

This study was conducted between January 2017 and January 2018 at Fuwai Hospital, Beijing, China, and included older (age ≥ 65 years) diabetic patients that received RVP for the first time. TyG index were obtained before implantation. The primary endpoint was HFH.

RESULTS

A total of 231 patients were divided into three groups according to the tertiles of TyG index: < 8.5 (T1, N = 77), 8.5-9.1 (T2, N = 77), and > 9.1 (T3, N = 77). T3 group had higher rate of HFH (Log-rank = 11.7, P = 0.003). Multivariate analyses showed that, TyG index served as an independent predictor for HFH, both as numerical variable (HR = 1.94, 95% CI 1.21-3.11, P = 0.006), and as categorical variable (HR = 2.31, 95% CI 1.09-4.89, P = 0.03). RCS demonstrated that the risk of HFH was relatively low until TyG index exceeded 8.8, beyond which the risk began to increase rapidly (P-non-linear = 0.006).

CONCLUSION

Preimplantation TyG index emerges as a robust, independent predictor for HFH in older diabetic patients received RVP, and TyG index > 8.8 might be the optimal cut-off value.

New insights into FGF21 alleviates diabetic cardiomyopathy by suppressing ferroptosis: a commentary

Diabetic cardiomyopathy (DCM) is a severe cardiovascular complication of diabetes characterized by myocardial hypertrophy, fibrosis, and impaired cardiac function. Fibroblast growth factor 21 (FGF21) has emerged as a promising therapeutic target due to its antifibrotic, antioxidant, and anti-inflammatory properties. Our commentary summarizes and affirms the recent study by Wang et al., which demonstrates the significant role of ferroptosis in DCM pathogenesis. FGF21 has shown promise as a therapeutic target for DCM, potentially inhibiting ferroptosis, mitigating oxidative damage, and protecting cardiomyocyte function. Mechanistically, the study identified ATF4 as an upstream regulator of FGF21 in DCM, revealing that FGF21 directly interacts with ferritin and extends its half-life, thus inhibiting ferroptosis in DCM. These findings provide a theoretical basis for understanding the pathogenesis and treatment of DCM. Our commentary suggests that future studies should explore the role of non-cardiomyocyte cell types in DCM, verify findings with clinical samples, and address comprehensive methods for ferroptosis detection. Additionally, we discuss the clinical application and future potential of FGF21-based therapies for DCM. Such efforts may contribute to advancing DCM diagnosis and treatment, fostering the development of innovative therapeutic strategies.

Effect of Tricin on cardiomyocyte damage caused by diabetic cardiomyopathy (DCM)

OBJECTIVES

Flavonoid compounds exhibit remarkable antioxidant and anti-inflammatory properties in DCM and various other diseases. However, the specific mechanisms by which Tricin, 4',5,7-trihydroxy-3',5'-dimethoxyflavone, exerts its effects in the context of DCM remain to be elucidated.

METHODS

Rat H9C2 cells were cultured and subjected to high glucose conditions to establish a DCM cell model. Tricin was administered in varying concentrations to evaluate its effects on cellular oxidative stress markers, including ROS, LDH, and SOD. Additionally, the levels of inflammatory cytokines TNF-α, IL-1β, and IL-6, as well as the expression of TLR4, MYD88, and p-NF-κB, were assessed through ELISA and Western blotting.

RESULTS

Tricin treatment significantly ameliorated high glucose-induced oxidative stress in H9C2 cells, evidenced by reduced ROS and LDH levels and increased SOD levels in a dose-dependent manner. Furthermore, Tricin effectively suppressed the elevation of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Tricin also inhibited the overactivation of the TLR4-MYD88-NF-κB signaling pathway, suggesting its role in modulating key inflammatory processes in DCM.

CONCLUSIONS

Tricin exhibits a protective role against high glucose-induced cardiac damage in a DCM cell model. By reducing oxidative stress and inflammation, and inhibiting the TLR4-MYD88-NF-κB pathway, Tricin shows significant therapeutic potential for DCM treatment. This study underscores the value of Tricin as a novel therapeutic approach for managing diabetic cardiomyopathy, warranting further research and clinical investigation.

CLINICAL TRIAL NUMBER

Not applicable.

Gastrodin attenuates diabetic cardiomyopathy characterized by myocardial fibrosis by inhibiting the KLK8-PAR1 signaling axis

BACKGROUND

Diabetic cardiomyopathy (DCM), characterized by myocardial fibrosis, is a major cause of mortality and morbidity in diabetic patients; the inhibition of cardiac fibrosis is a fundamental strategy for treating DCM. Gastrodin (GAS), a compound extracted from Gastrodia elata protects against DCM, but the molecular mechanism underlying its antifibrotic effect has not been elucidated.

METHODS

In vivo, the effects of GAS were investigated using C57BL/6 mice with DCM, which was induced by administering a high-sugar, high-fat (HSF) diet and streptozotocin (STZ). We assessed the cardiac function in these mice and detected histopathological changes in their hearts and the degree of cardiac fibrosis. In vitro, neonatal rat cardiac fibroblasts (CFs) were transformed into myofibroblasts by exposing them to high glucose combined with high palmitic acid (HG-PA), and CFs were induced by pEX-1 (pGCMV/MCS/EGFP/Neo) plasmid-mediated overexpression of KLK8, which contains the rat KLK8 gene. The KLK8 siRNA was knocked down to study the effects of GAS on CF differentiation, collagen synthesis, and cell migration by specific mechanisms of action of GAS.

RESULTS

GAS attenuated pathological changes in the hearts of DCM mice, rescued impaired cardiac function, and attenuated cardiac fibrosis. Additionally, the results of molecular docking analysis showed that GAS binds to kinin-releasing enzyme-related peptidase 8 (KLK8) to inhibit the increase in protease-activated receptor-1 (PAR-1), thus attenuating myocardial fibrosis. Specifically, GAS attenuated the transformation of neonatal rat CFs to myofibroblasts exposed to HG-PA. Overexpressing KLK8 promoted CF differentiation, collagen synthesis, and cell migration, and KLK8 siRNA attenuated HG-PA-induced CF differentiation, collagen synthesis, and cell migration. Further studies revealed that a PAR-1 antagonist, but not a PAR-2 antagonist, could attenuate CF differentiation, collagen synthesis, and cell migration. Additionally, GAS inhibited KLK8 upregulation and PAR1 activation, thus blocking the differentiation, collagen synthesis, and cell migration of HG-PA-exposed CFs and triggering TGF-β1/Smad3 signaling.

CONCLUSION

GAS alleviated pathological changes in the hearts of DCM model mice induced by an HSF diet combined with STZ. KLK8 mediated HG-PA-induced differentiation, collagen synthesis, and the migration of CFs. GAS attenuated the differentiation, collagen synthesis, and migration of CFs by inhibiting the KLK8-PAR1 signaling axis, a process in which TGF-β1 and Smad3 are involved.

Targeting DUSP26 to drive cardiac mitochondrial dynamics via FAK-ERK signaling in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a severe cardiac complication of diabetes mellitus, characterized by structural and functional myocardial abnormalities. The molecular mechanisms underlying DCM, particularly the role of dual-specificity phosphatase 26 (DUSP26), remain insufficiently understood. Our study reveals that DUSP26 expression is markedly downregulated in the cardiomyocytes of diabetic db/db mice and under glucolipotoxic stress. Overexpression of DUSP26 in db/db mice significantly improved cardiac function, as demonstrated by enhanced left ventricular ejection fraction and fractional shortening, alongside reduced myocardial fibrosis and hypertrophy. Mitochondrial analysis indicated that DUSP26 overexpression led to increased ATP production, enhanced mitochondrial fusion, and improved structural integrity. In addition, lipid accumulation was reduced, reflecting enhanced metabolic function. We also discovered that DUSP26 is necessary for regulating the focal adhesion kinase (FAK)-extracellular signal-regulated kinase (ERK) pathway, with pharmacological activation of FAK partially offsetting the benefits of DUSP26 overexpression in rescue experiments. These findings underscore the pivotal role of DUSP26 as a potential therapeutic target, highlighting the importance of developing targeted molecular interventions to address diabetic cardiac complications.

Preclinical evidence and possible mechanisms of cardioprotective effects of resveratrol in diabetic cardiomyopathy: a systematic review and meta-analysis

INTRODUCTION

Diabetic cardiomyopathy (DCM) is a significant complication of diabetes, characterized primarily by the development of heart failure in individuals with diabetes. Numerous animal studies have indicated that resveratrol enhances cardiac function in diabetic cardiomyopathy; however, its reliability and underlying mechanism remain unclear. This study aims to assess the cardioprotective effects of resveratrol on DCM and explore its potential mechanism.

METHODS

We searched PubMed, EMBASE, WOS, Cochrane Library, CNKI, CBM, Chinese VIP, and Wan Fang Database until March 31st, 2024, without language restrictions. Continuous outcome measures were analyzed using weighted mean difference or standardized mean difference, and heterogeneity was assessed with I2. The risk of bias in animal experiments was evaluated using the SYRCLE tool, and evidence reliability was determined with the GRADE tool. All data were analyzed using Review Manager 5.4.1 and Stata 17. This study has been registered on the PROSPERO (CRD42024523944).

RESULTS

A total of 18 studies meeting the criteria were identified. The analysis revealed that the resveratrol intervention group exhibited significant improvements in LVEF (WMD = 17.88), LVFS (WMD = 8.77), HW/BW (SMD=-2.92), SOD (SMD = 4.53), and MDA (SMD=-5.07) compared to the control group. The GRADE grading assessment indicated moderate certainty for LVEF, HW/BW, and MDA, while certainty for other factors was considered low.

CONCLUSION

Our research suggests that resveratrol may protect cardiac function in DCM through anti-inflammatory and anti-oxidative stress effects. However, these findings are based on preclinical data, and further extensive trials are needed to confirm their effectiveness and safety before clinical application.

Mechanistic insights and therapeutic potential of astilbin and apigenin in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) represents a critical complication of Diabetes mellitus (DM), characterized by structural and functional changes in the myocardium independent of coronary artery disease or hypertension. Emerging evidence highlights the significant roles of phytochemicals, particularly astilbin and apigenin, in modulating key molecular pathways implicated in DCM. This review synthesizes current mechanistic insights and therapeutic potential of these compounds, focusing on their interactions with AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptors (PPARs), O-linked N-acetylglucosamine (O-GlcNAc), sodium-glucose co-transporter 2 (SGLT2), protein kinase C (PKC), nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK) pathways. Astilbin and apigenin have demonstrated the ability to improve cardiac function, mitigate oxidative stress, and reduce inflammatory responses in diabetic conditions. By activating AMPK and PPARs, these flavonoids enhance glucose uptake and fatty acid oxidation, contributing to improved metabolic homeostasis. Their inhibition of O-GlcNAcylation, SGLT2 activity, and PKC signaling further attenuates hyperglycemia-induced cellular damage. Additionally, suppression of NF-κB, MAPK, and JNK pathways by astilbin and apigenin results in reduced pro-inflammatory cytokine production and apoptotic cell death. Collectively, these interactions position astilbin and apigenin as promising therapeutic agents for ameliorating DCM, offering novel avenues for treatment strategies aimed at modulating multiple pathogenic pathways.

Healthy longevity-associated protein improves cardiac function in murine models of cardiomyopathy with preserved ejection fraction

AIMS

Aging is influenced by genetic determinants and comorbidities, among which diabetes increases the risk for heart failure with preserved ejection fraction. There is no therapy to prevent heart dysfunction in aging and diabetic individuals. In previous studies, a single administration of the longevity-associated variant (LAV) of the human BPIFB4 gene halted heart decline in older and type 2 diabetic mice. Here, we asked whether orally administered LAV-BPIFB4 protein replicates these benefits.

MATERIALS AND METHODS

In two controlled, randomized studies, 18-month-old male C57BL/6 J mice and 9-week-old C57BLKS/J-Leprdb/Leprdb/Dock7 + [db/db] mice of both sexes underwent baseline echocardiography. They then received a recombinant purified LAV-BPIFB4 protein (3 µg/animal, every three days) or vehicle by gavage. After 30 days, the animals underwent echocardiography, and the hearts were collected post-termination for histology.

RESULTS

All the animals completed the study except one female diabetic mouse, which was culled prematurely because tooth malocclusion caused eating problems. There was no effect of the LAV-BPIFB4 protein on body weight in the two studies or glycosuria in the diabetic study. In aging mice, LAV-BPIFB4 increased myocardial Bpifb4 expression, improving heart contractility and capillarity while reducing perivascular fibrosis and senesce. In male diabetic mice, LAV-BPIFB4 therapy improved systolic function, microvascular density, and senescence, whereas the benefit was limited to systolic function in females.

CONCLUSIONS

This study shows the feasibility and efficacy of a variant protein associated with human longevity in contrasting pivotal risk factors for heart failure in animal models. The diabetic study revealed that sex influences the treatment efficacy.

Fibroblast growth factor 21 improves diabetic cardiomyopathy by inhibiting ferroptosis via ferritin pathway

BACKGROUND

Diabetic cardiomyopathy (DCM) is a serious complication in patients with type 2 diabetes mellitus, and its mechanisms are complex and poorly understood. Despite growing evidence suggesting that ferroptosis plays a significant role in cardiovascular disease, it has been less extensively studied in DCM. Fibroblast growth factor 21 (FGF21), whose mechanism of action is closely related to ferroptosis, is widely utilized in studies focused on the prevention and treatment of glucolipid metabolism-related diseases and cardiovascular diseases.

OBJECTIVE

To confirm the significant role of ferroptosis in DCM and to investigate whether FGF21 improves DCM by inhibiting ferroptosis and elucidating its specific molecular mechanisms.

METHODS

The animal DCM models were established through high-fat feeding combined with streptozotocin injection in C57BL/6J mice or by db/db mice, and the diabetic cardiomyocyte injury model was created using high glucose and high fat (HG/HF) culture of primary cardiomyocytes. Intervention modeling of FGF21 were performed by injecting adeno-associated virus 9-FGF21 in mice and transfecting FGF21 siRNA or overexpression plasmid in primary cardiomyocytes.

RESULTS

The findings indicated that ferroptosis was exacerbated and played a significant role in DCM. The overexpression of FGF21 inhibited ferroptosis and improved cardiac injury and function, whereas the knockdown of FGF21 aggravated ferroptosis and cardiac injury and function in DCM. Furthermore, we discovered that FGF21 inhibited ferroptosis in DCM by directly acting on ferritin and prolonging its half-life. Specifically, FGF21 binded to the heavy and light chains of ferritin, thereby reducing its excessive degradation in the proteasome and lysosomal-autophagy pathways in DCM. Additionally, activating transcription factor 4 (ATF4) served as the upstream regulator of FGF21 in DCM.

CONCLUSIONS

The ATF4-FGF21-ferritin axis mediates the protective effects in DCM through the ferroptosis pathway and represents a potential therapeutic target for DCM.

Subcellular mass spectrometric detection unveils hyperglycemic memory in the diabetic heart

BACKGROUND

Intensive glycemic control is insufficient to reduce the risk of heart failure in patients with diabetes mellitus. While the hyperglycemic memory in the diabetic cardiomyopathy has been well documented, its underlying mechanisms are not fully understood. The present study tried to investigate whether the dysregulated proteins/biological pathways, which persistently altered in diabetic hearts during normoglycemia, participate in the hyperglycemic memory.

METHODS

Hearts of streptozotocin-induced diabetic mice, with or without intensive glycemic control using slow-release insulin implants, were collected. Proteins from total heart samples and subcellular fractions were assessed by mass spectrometry, Western blotting, and KEGG pathway enrichment analysis. mRNA sequencing was used to determine whether the persistently altered proteins were regulated at the transcriptional or post-transcriptional level.

RESULTS

Western blot validation of several proteins with high pathophysiological importance, including MYH7, HMGCS2, PDK4, and BDH1, indicated that mass spectrometry was able to qualitatively, but not quantitatively, reflect the fold changes of certain proteins in diabetes. Pathway analysis revealed that the peroxisome, PPAR pathway, and fatty acid metabolism could be efficiently rescued by glycemic control. However, dysregulation of oxidative phosphorylation and reactive oxygen species persisted even after normalization of hyperglycemia. Notably, mRNA sequencing revealed that dysregulated proteins in the oxidative phosphorylation pathway were not accompanied by coordinated changes in mRNA levels, indicating post-transcriptional regulation. Moreover, literature review and bioinformatics analysis suggested that hyperglycemia-induced persistent alterations of miRNAs targeted genes from the persistently dysregulated oxidative phosphorylation pathway, whereas, oxidative phosphorylation dysfunction-induced ROS regulated miRNA expression, which thereby might sustained the dysregulation of miRNAs.

CONCLUSIONS

Glycemic control cannot rescue hyperglycemia-induced alterations of subcellular proteins in the diabetic heart, and persistently altered proteins are involved in multiple functional pathways, including oxidative phosphorylation. These findings might provide novel insights into hyperglycemic memory in diabetic cardiomyopathy.

Role of bariatric surgery in improving diabetic cardiomyopathy: Molecular mechanisms and therapeutic perspectives (Review)

Diabetic cardiomyopathy (DCM), a significant complication of diabetes mellitus, is marked by myocardial structural and functional alterations due to chronic hyperglycemia. Despite its clinical significance, optimal treatment strategies are still elusive. Bariatric surgery via sleeve gastrectomy and Roux-en-Y gastric bypass have shown promise in treating morbid obesity and associated metabolic disorders including improvements in diabetes mellitus and DCM. The present study reviews the molecular mechanisms by which bariatric surgery improves DCM, offering insights into potential therapeutic targets. Future research should further investigate the mechanistic links between bariatric surgery and DCM, to evaluate the benefits and limitations of these surgical interventions for DCM treatment. The present study aims to provide a foundation for more effective DCM therapies, contributing to the advancement of patient care.

Investigating the research trajectory and future trends of immune disorders in diabetes cardiovascular complications: A bibliometric analysis over the past decade based on big data

INTRODUCTION

Cardiovascular complications of diabetes are a top cause of death in diabetics and often involve immune system problems. Despite numerous studies, there's a shortage of extensive data to advance this field. This study aims to systematically analyze the role of immune dysregulation in these complications using bibliometric methods, to outline the research path and predict future directions.

METHODS

Published from January 1, 2014 to December 31, 2023, 2826 records from the Web of Science Core Collection were analyzed. Collaboration networks, keyword co-occurrences, references, and research hotspots were visualized and analyzed using Microsoft Office Excel 2019, VOSviewer, CiteSpace, and R software.

RESULTS

The number of research papers and citations on this topic has been increasing from 2014 to 2023, with significant contributions from the United States and China. Studies have focused on the effects of oxidative stress, inflammation, metabolism, gut microbiota, and COVID-19 on diabetic heart problems, highlighting the role of immune dysregulation in these diseases.

CONCLUSION

This research provides an overview of immune dysregulation in the cardiovascular complications of diabetes, explores potential treatments including immunomodulation, insulin resistance, and the benefits of vitamin D on cardiovascular disease, and helps advance the field.

Renal denervation ameliorates atrial remodeling in type 2 diabetic rats by regulating mitochondrial dynamics

There is no effective treatment for diabetes-related atrial remodeling currently. This study aimed to investigate the effects of renal denervation (RDN) on diabetes-related atrial remodeling and explore the related mechanisms. A type 2 diabetes mellitus model was established by high-fat diet feeding and low-dose streptozotocin injection in Sprague‒Dawley rats. After successful modeling, the diabetic rats were randomly assigned to two groups according to whether they were subjected to RDN or sham RDN surgery. At the end of the experiment, cardiac function and structure were evaluated by echocardiography and histology, respectively. Mitochondrial morphology, function and mitochondrial dynamics were assessed by multiple methods. Mdivi1 was used to verify the mechanism by which RDN improves atrial remodeling. In the 10th week, diabetic rats exhibited obvious atrial remodeling, including atrial enlargement and diastolic dysfunction. Pathological staining showed that diabetic rats had cardiomyocyte hypertrophy and interstitial fibrosis in atrial tissues. In terms of mitochondrial morphology and function, diabetic rats exhibited fragmented mitochondria, reduced adenosine triphosphate production and decreased mitochondrial membrane potential levels. Abnormal mitochondrial dynamics in diabetic rats were characterized by the inhibition of mitochondrial fusion, excessive mitochondrial fission, and the suppression of mitophagy. However, RDN effectively ameliorated diabetes-induced pathological atrial remodeling. In addition, RDN significantly improved mitochondrial morphological and functional abnormalities and corrected the disorders of mitochondrial dynamics. Furthermore, the protective effects of RDN against atrial remodeling were related to the regulation of mitochondrial dynamics. RDN prevented diabetes-induced atrial remodeling. These protective effects might be related to improvements in mitochondrial dynamics.

(Pro)renin receptor aggravates myocardial pyroptosis in diabetic cardiomyopathy through AMPK-NLRP3 pathway

Introduction

As one of the most common complications of diabetes, diabetic cardiomyopathy (DCM) is the main cause of heart failure in patients with diabetes. However, the lack of effective treatments for DCM remains a clinical challenge. (Pro) renin receptor (PRR) is a member of renin angiotensin aldosterone system (RAAS). Here, we aim to determine whether PRR is involved in myocardial pyroptosis in diabetic cardiomyopathy.

Methods

We established diabetic rats model by intraperitoneal injection of streptozotocin (STZ). PRR overexpression adenovirus or PRR knockdown adenovirus was injected into the tail vein. Western blot, histopathology and immunohistochemistry staining, ELISA and Echocardiography were used to detect cardiac function changes and myocardial injury levels of DCM rats. Primary cardiomyocytes were stimulated with high glucose and PRR overexpression or PRR knockdown was achieved by adenovirus transfection, we also used the inhibitor of AMPK to decrease the activity of AMPK. Western blot, Real-time PCR, Immunofluorescence and ELISA were used to detect the level of PRR and pyroptosis in cardiomyocyte.

Results

We found that high glucose increased the expression of PRR in heart. After overexpression of PRR, the expression of the pyroptosis related proteins such as Caspase-1, IL-1β, IL-18, and NLRP3 was significantly increased, the phosphorylation level of AMPK was significantly decreased, and the fibrosis level was significantly increased, thus aggravating the cardiac function injury of DCM. On the contrary, PRR knockdown can alleviate the level of myocardial pyroptosis in DCM and improve cardiac function. The related mechanism was that PRR could inhibit AMPK phosphorylation and promote the activation of NLRP3 inflammasome.

Discussion

PRR aggravated pyroptosis of cardiomyocyte, increased the dysfunction of cardiomyocyte, and may be related to the decrease of AMPK phosphorylation and the overactivation of NLRP3. This may provide new ideas and targets for the treatment of DCM.

Sleep restriction exacerbates cardiac dysfunction in diabetic mice by causing cardiomyocyte death and fibrosis through mitochondrial damage

Diabetic cardiomyopathy (DCM) is a cardiovascular complication of diabetes mellitus with a poor prognosis and is the leading cause of death in diabetic patients. Sleep deficiency is not only recognized as an important risk factor for the development of type 2 DM, but is also associated with increased morbidity and mortality of cardiovascular disease. The underlying role and mechanisms of sleep restriction (SR) in DCM are far from clear. The KK/Upj-Ay mouse model of T2 DM was used as a study subject, and the small animal ultrasound imaging system was used to detect the function of the heart; immunopathological staining was used to clarify the histo-structural pathological alterations of the heart; and TUNEL staining, qPCR, transmission electron microscopy (TEM), and ELISA kits were used to detect apoptosis, oxidative stress, inflammation, and mitochondrial damage, and related molecular alterations. SR led to a significant increase in mortality, cardiac hypertrophy, necrosis, glycogen deposition and fibrosis further deteriorated in DM KK mice. SR increased cardiomyocyte death in KK mice through the Bax/Bcl2 pathway. In addition to this, SR not only exacerbated the inflammatory response, but also aggravated mitochondrial damage and promoted oxidative stress in KK mice through the PRDM16-PGC-1α pathway. Overall, SR exacerbates structural alterations and dysfunction through inflammation, oxidative stress, and apoptosis in DM KK mice, increasing the risk of death. Clinicians and diabetic patients are prompted to pay attention to sleep habits to avoid accelerating the transition of DCM to heart failure and inducing death due to poor sleep habits.

UCF101 Rescues against Diabetes-Evoked Cardiac Remodeling and Contractile Anomalies through AMP-Activated Protein Kinase-Mediated Induction of Mitophagy

INTRODUCTION

Diabetes mellitus is known to provoke devastating anomalies in myocardial structure and function, while effective therapeutic regimen is still lacking. The selective protease inhibitor UCF101 (5-[5-(2-nitrophenyl) furfuryl iodine]-1,3-diphenyl-2-thiobarbituric acid) has been shown to fend off ischemic heart injury, although its impact on diabetic cardiomyopathy remains elusive.

METHODS

Our present work was conducted to examine the effect of UCF101 on experimental diabetes-evoked cardiac geometric and functional abnormalities as well as mechanisms involved. Adult mice were made diabetic using streptozotocin (STZ, 50 mg/kg, i.p., for 5 days) while receiving UCF101 (7.15 mg/kg, i.p.).

RESULTS

STZ evoked cardiac hypertrophy, interstitial fibrosis, mitochondrial ultrastructural damage, oxidative stress, dampened autophagy (LC3B, Beclin 1, elevated p62), mitophagy (FUNDC1 and Parkin with upregulated TOM20), increased left ventricular end systolic diameter, reduced fractional shortening, ejection fraction, cardiomyocyte shortening capacity, velocities of shortening/re-lengthening, and rise in intracellular Ca2+ in conjunction with elongated diastole and intracellular Ca2+ removal, the responses were overtly reconciled by UCF101 with little effects from UCF101 itself. Levels of cell injury markers Omi/HtrA2, TNFα, and stress signaling (JNK, ERK, p38) were overtly enhanced along with compromised phosphorylation of cellular fuel AMP-activated protein kinase (AMPK) (Thr172) and cell survival molecule GSK3β, as well as downregulated SERCA2a and elevated phospholamban, the effect was reversed by UCF101 (except for SERCA2a). AMPK knockout, pharmacological inhibition, the mitophagy inhibitor liensinine, and parkin knockout nullified UCF101-offered cardioprotection in diabetes. UCF101 reversed STZ-induced upregulation in the AMPK degrading enzymes PP2A and PP2C.

CONCLUSION

These findings suggest that UCF101 rescues diabetes-mediated alterations in cardiac structure and function, likely through AMPK-mediated regulation of mitophagy.

Role of melatonin in mitigation of insulin resistance and ensuing diabetic cardiomyopathy

Addressing insulin resistance or hyperinsulinemia might offer a viable treatment approach to stop the onset of diabetic cardiomyopathy, as these conditions independently predispose to the development of the disease, which is initially characterized by diastolic abnormalities. The development of diabetic cardiomyopathy appears to be driven mainly by insulin resistance or impaired insulin signalling and/or hyperinsulinemia. Oxidative stress, hypertrophy, fibrosis, cardiac diastolic dysfunction, and, ultimately, systolic heart failure are the outcomes of these pathophysiological alterations. Melatonin is a ubiquitous indoleamine, a widely distributed compound secreted mainly by the pineal gland, and serves a variety of purposes in almost every living creature. Melatonin is found to play a leading role by improving myocardial cell metabolism, decreasing vascular endothelial cell death, reversing micro-circulation disorders, reducing myocardial fibrosis, decreasing oxidative and endoplasmic reticulum stress, regulating cell autophagy and apoptosis, and enhancing mitochondrial function. This review highlights a relationship between insulin resistance and associated cardiomyopathy. It explores the potential therapeutic strategies offered by the neurohormone melatonin, an important antioxidant that plays a leading role in maintaining glucose homeostasis by influencing the glucose transporters independently and through its receptors. The vast distribution of melatonin receptors in the body, including beta cells of pancreatic islets, asserts the role of this indole molecule in maintaining glucose homeostasis. Melatonin controls the production of GLUT4 and/or the phosphorylation process of the receptor for insulin and its intracellular substrates, activating the insulin-signalling pathway through its G-protein-coupled membrane receptors.

Identification of immune feature genes and intercellular profiles in diabetic cardiomyopathy

BACKGROUND

Diabetic cardiomyopathy (DCM) is a multifaceted cardiovascular disorder in which immune dysregulation plays a pivotal role. The immunological molecular mechanisms underlying DCM are poorly understood.

AIM

To examine the immunological molecular mechanisms of DCM and construct diagnostic and prognostic models of DCM based on immune feature genes (IFGs).

METHODS

Weighted gene co-expression network analysis along with machine learning methods were employed to pinpoint IFGs within bulk RNA sequencing (RNA-seq) datasets. Single-sample gene set enrichment analysis (ssGSEA) facilitated the analysis of immune cell infiltration. Diagnostic and prognostic models for these IFGs were developed and assessed in a validation cohort. Gene expression in the DCM cell model was confirmed through real time-quantitative polymerase chain reaction and western blotting techniques. Additionally, single-cell RNA-seq data provided deeper insights into cellular profiles and interactions.

RESULTS

The overlap between 69 differentially expressed genes in the DCM-associated module and 2483 immune genes yielded 7 differentially expressed immune-related genes. Four IFGs showed good diagnostic and prognostic values in the validation cohort: Proenkephalin (Penk) and retinol binding protein 7 (Rbp7), which were highly expressed, and glucagon receptor and inhibin subunit alpha, which were expressed at low levels in DCM patients (all area under the curves > 0.9). SsGSEA revealed that IFG-related immune cell infiltration primarily involved type 2 T helper cells. High expression of Penk (P < 0.0001) and Rbp7 (P = 0.001) was detected in cardiomyocytes and interstitial cells and further confirmed in a DCM cell model in vitro. Intercellular events and communication analysis revealed abnormal cellular phenotype transformation and signaling communication in DCM, especially between mesenchymal cells and macrophages.

CONCLUSION

The present study identified Penk and Rbp7 as potential DCM biomarkers, and aberrant mesenchymal-immune cell phenotype communication may be an important aspect of DCM pathogenesis.

Cardiomyocyte LGR6 alleviates ferroptosis in diabetic cardiomyopathy via regulating mitochondrial biogenesis

AIMS

The majority of people with diabetes are susceptible to cardiac dysfunction and heart failure, and conventional drug therapy cannot correct the progression of diabetic cardiomyopathy. We assessed the potential role and therapeutic value of LGR6 (G protein-coupled receptor containing leucine-rich repeats 6) in diabetic cardiomyopathy.

METHODS AND RESULTS

Type 2 diabetes models were established using high-fat diet/streptozotocin-induced diabetes in mice. LGR6 knockout mice were generated. Recombinant adeno-associated virus serotype 9 carrying LGR6 under the cardiac troponin T promoter was injected into diabetic mice. Cardiomyocytes incubated with high glucose (HG) were used to imitate diabetic cardiomyopathy in vitro. The molecular mechanism was explored through RNA sequencing and a chromatin immunoprecipitation assay. We found that LGR6 expression was upregulated in diabetic hearts and HL1 cardiomyocytes treated with HG. The LGR6 knockout aggravated, but cardiomyocyte-specific LGR6 overexpression ameliorated, cardiac dysfunction and remodeling in diabetic mice. Mechanistically, in vivo and in vitro experiments revealed that LGR6 deletion aggravated, whereas LGR6 overexpression alleviated, ferroptosis and disrupted mitochondrial biogenesis by regulating STAT3/Pgc1a signaling. STAT3 inhibition and Pgc1a activation abrogated LGR6 knockout-induced mitochondrial dysfunction and ferroptosis in diabetic mice. In addition, LGR6 activation by recombinant RSPO3 treatment ameliorated cardiac dysfunction, ferroptosis and mitochondrial dysfunction in diabetic mice.

CONCLUSIONS

We identified a previously undescribed signaling pathway of the LGR6-STAT3-Pgc1a axis that plays a critical role in ferroptosis and mitochondrial disorders during diabetic cardiomyopathy and provides an option for treatment of diabetic hearts.