Sex Differences of the Diabetic Heart

Fibroblast-specific TGF-β signaling mediates cardiac dysfunction, fibrosis, and hypertrophy in obese diabetic mice

AIMS

Transforming growth factor (TGF)-β is up-regulated in the diabetic myocardium and may mediate fibroblast activation. We aimed at examining the role of TGF-β-induced fibroblast activation in the pathogenesis of diabetic cardiomyopathy.

METHODS AND RESULTS

We generated lean and obese db/db mice with fibroblast-specific loss of TbR2, the Type 2 receptor-mediating signaling through all three TGF-β isoforms, and mice with fibroblast-specific Smad3 disruption. Systolic and diastolic function, myocardial fibrosis, and hypertrophy were assessed. Transcriptomic studies and in vitro experiments were used to dissect mechanisms of fibroblast activation. Fibroblast-specific TbR2 loss attenuated systolic and diastolic dysfunction in db/db mice. The protective effects of fibroblast TbR2 loss in db/db mice were associated with attenuated fibrosis and reduced cardiomyocyte hypertrophy, suggesting that in addition to their role in fibrous tissue deposition, TGF-β-stimulated fibroblasts may also exert paracrine actions on cardiomyocytes. Fibroblast-specific Smad3 loss phenocopied the protective effects of fibroblast TbR2 loss in db/db mice. Db/db fibroblasts had increased expression of genes associated with oxidative response (such as Fmo2, encoding flavin-containing monooxygenase 2), matricellular genes (such as Thbs4 and Fbln2), and Lox (encoding lysyl oxidase). Ingenuity pathway analysis (IPA) predicted that neurohumoral mediators, cytokines, and growth factors (such as AGT, TGFB1, and TNF) may serve as important upstream regulators of the transcriptomic profile of diabetic mouse fibroblasts. IPA of scRNA-seq data identified TGFB1, p53, MYC, PDGF-BB, EGFR, and WNT3A/CTNNB1 as important upstream regulators underlying fibroblast activation in db/db hearts. Comparison of the transcriptome of fibroblasts from db/db mice with fibroblast-specific Smad3 loss and db/db Smad3 fl/fl controls identified Thbs4 [encoding thrombospondin-4 (TSP-4), a marker of activated fibroblasts] as a candidate diabetes-induced fibrogenic mediator. However, in vitro experiments showed no significant activating effects of matricellular or intracellular TSP-4 on cardiac fibroblasts.

CONCLUSION

Fibroblast-specific TGF-β/Smad3 signaling mediates ventricular fibrosis, hypertrophy, and dysfunction in Type 2 diabetes.

Sex Differences in Procedural Characteristics and Clinical Outcomes Among Patients Undergoing Bifurcation PCI

BACKGROUND AND OBJECTIVES

The risk profiles, procedural characteristics, and clinical outcomes for women undergoing bifurcation percutaneous coronary intervention (PCI) are not well defined compared to those in men.

METHODS

COronary BIfurcation Stenting III (COBIS III) is a multicenter, real-world registry of 2,648 patients with bifurcation lesions treated with second-generation drug-eluting stents. We compared the angiographic and procedural characteristics and clinical outcomes based on sex. The primary outcome was 5-year target lesion failure (TLF), a composite of cardiac death, myocardial infarction, and target lesion revascularization.

RESULTS

Women (n=635, 24%) were older, had hypertension and diabetes more often, and had smaller main vessel and side branch reference diameters than men. The pre- and post-PCI angiographic percentage diameter stenoses of the main vessel and side branch were comparable between women and men. There were no differences in procedural characteristics between the sexes. Women and men had a similar risk of TLF (6.3% vs. 7.1%, p=0.63) as well as its individual components and sex was not an independent predictor of TLF. This finding was consistent in the left main and 2 stenting subgroups.

CONCLUSIONS

In patients undergoing bifurcation PCI, sex was not an independent predictor of adverse outcome.

Impact of Sex and Diabetes in Patients with Heart Failure

PURPOSE OF REVIEW

Heart failure (HF) is a complex clinical syndrome with a growing global health burden. This review explores the intersection of HF, diabetes mellitus, and sex, highlighting epidemiological patterns, pathophysiological mechanisms, and treatment implications.

RECENT FINDINGS

Despite similar HF prevalence in men and women, diabetes mellitus (DM) appears to exert a more pronounced impact on HF outcomes in women. Pathophysiological differences involve cardiovascular risk factors, severe left ventricular dysfunction, and coronary artery disease, as well as hormonal influences and inflammatory markers. Diabetic cardiomyopathy introduces a sex-specific challenge, with women experiencing common adverse outcomes related to increased fibrosis and myocardial remodeling. Treatment strategies, particularly sodium-glucose cotransporter 2 inhibitors, exhibit cardiovascular benefits, but their response may differ in women. The link between HF and DM is bidirectional, with diabetes significantly increasing the risk of HF, and vice versa. Additionally, the impact of diabetes on mortality appears more pronounced in women than in men, leading to a modification of the traditional gender gap observed in HF outcomes. A personalized approach is crucial, and further research to improve outcomes in the complex interplay of HF, diabetes, and sex is needed.

Epicardial fat and insulin resistance in healthy older adults: a cross-sectional analysis

Insulin resistance (IR) and cardiovascular diseases (CVD) are relevant concerns in the elderly population; as the world's population ages, IR and CVD are two universal public health problems. While a link between IR a CVD has been established, the mediating mechanisms are uncertain and rigorous investigations are needed to fully elucidate them. The study aimed at assessing the relationship between epicardial fat (EF), an indicator of cardiovascular risk, and IR in Italian free-living elderly (n = 89). Baseline data from a previous cohort was used. Anthropometric measurements, EF, and IR-related variables, including the HOMA-IR index and other biochemical parameters were obtained. The correlation between EF and IR was explored. Further analysis was conducted to identify significant differences regarding IR variables among EF quartiles. EF correlated positively with glucose levels in females, males and the total population. The pairwise comparison among EF quartiles showed significant differences in glucose levels, HOMA-IR index, triglycerides, and total cholesterol levels. To our knowledge, this is the only study assessing the relationship between EF and IR in healthy elderly, while most of the studies have investigated EF and IR in diseased populations. Further research with a longitudinal approach should be conducted to design concrete conclusions about this relationship.

Moderate-Intensity and High-Intensity Interval Exercise Training Offer Equal Cardioprotection, with Different Mechanisms, during the Development of Type 2 Diabetes in Rats

Endurance exercise training is a promising cardioprotective strategy in type 2 diabetes mellitus (T2DM), but the impact of its intensity is not clear. We aimed to investigate whether and how isocaloric moderate-intensity exercise training (MIT) and high-intensity interval exercise training (HIIT) could prevent the adverse cardiac remodeling and dysfunction that develop T2DM in rats. Male rats received a Western diet (WD) to induce T2DM and underwent a sedentary lifestyle (n = 7), MIT (n = 7) or HIIT (n = 8). Insulin resistance was defined as the HOMA-IR value. Cardiac function was assessed with left ventricular (LV) echocardiography and invasive hemodynamics. A qPCR and histology of LV tissue unraveled underlying mechanisms. We found that MIT and HIIT halted T2DM development compared to in sedentary WD rats (p < 0.05). Both interventions prevented increases in LV end-systolic pressure, wall thickness and interstitial collagen content (p < 0.05). In LV tissue, HIIT tended to upregulate the gene expression of an ROS-generating enzyme (NOX4), while both modalities increased proinflammatory macrophage markers and cytokines (CD86, TNF-α, IL-1β; p < 0.05). HIIT promoted antioxidant and dicarbonyl defense systems (SOD2, glyoxalase 1; p < 0.05) whereas MIT elevated anti-inflammatory macrophage marker expression (CD206, CD163; p < 0.01). We conclude that both MIT and HIIT limit WD-induced T2DM with diastolic dysfunction and pathological LV hypertrophy, possibly using different adaptive mechanisms.

The impact of biological sex in peripheral nerve blockade: A prospective pharmacodynamic, pharmacokinetic and morphometric study in volunteers

STUDY OBJECTIVE

The impact of biological sex in peripheral regional anaesthesia is largely unknown. We therefore designed a prospective study in volunteers to investigate the impact of biological sex on pharmacodynamic, pharmacokinetic and morphometric characteristics for peripheral nerve blockade.

METHODS

The initial study plan was powered to include 90 volunteers to find a difference of 35 min in duration of sensory block (primary outcome variable) with 80% power and alpha error at 5%. After discussions in ethical review, a pilot study of 2 x 12 volunteers from each sex were studied. Female and male volunteers received ultrasound guided nerve blockade with 3.0 mL ropivacaine 7.5 mg mL-1. Sensory duration of blockade, as the primary outcome, was evaluated by pinprick testing. Secondary outcomes were sensory onset time of blockade, pharmacokinetic characteristics and the visibility of ulnar nerves using ultrasound. Analyses included Mann-Whitney U-statistics with P<0.05 (two-sided) as significant.

RESULTS

After 24 participants, the median (IQR) duration of sensory blockade was 450 (420; 503) min in women and 480 (450; 510) min in men (P = 0.49). Sensory onset time of blockade, and ultrasound visibility of nerves were also similar between the study groups. The total drug exposure across time (AUC0-infinity) was significantly higher in women (P = 0.017). After a the planned power re-analysis after these 24 study paticipants, which suggested that > 400 subjects would be required with 80% power and alpha error of 5% to find significance for the primary outcome parameter for marginal differences, we terminated the study at this point.

CONCLUSIONS

We did not detect significant differences between female and male study participants in terms of pharmacodynamic and morphometric characteristics after ultrasound guided ulnar nerve blocks. Women did show significantly greater pharmacokinetic ropivacaine exposures. The results of this study indicate that peripheral regional block pharmacodynamic characteristics are independent of the biological sex, whereas pharmacokinetic parameters are sex-dependent.

Gender differences in change of metabolic syndrome status and its components on all-cause and cause-specific mortalities: Over a decade follow-up study

BACKGROUND

Accumulating evidence suggests a close association between metabolic syndrome (MetS) and excess risk of mortality. However, whether the dynamic change of MetS and its components could affect cause-specific mortalities and how this relation could be influenced by gender is yet to be clarified.

METHODS AND RESULTS

In this longitudinal cohort, we entered 4904 Iranian adults>30 years (2820 women) from March-1999 and followed up until December-2018. MetS was determined using the joint interim societies (JIS) criteria. Due to change in MetS status over three years, we divided individuals into MetS-free, MetS-recovery, MetS-developed, and MetS-persistent groups. The same categories were defined for each MetS component. Multivariate Cox regression models were employed to compute the adjusted hazard ratios (HRs) and female-to-male relative HRs (F/M-RHRs) for risk of all-cause, cardiovascular (CV), non-CV, and cancer mortalities. To resolve reverse causation, mortalities during the first three years of follow-up were excluded. Subgroup analysis was conducted for non-diabetic and non-hypertensive participants. During 12.5 years of follow-up, 357 all-cause, 112 CV-, and 79 cancer-mortalities occurred. Compared to MetS-free, MetS-persistent raised all-cause- and CV-mortalities in both genders. Same association was found for non-diabetic (HR = 1.66 (1.03-3.00)) or non-hypertensive (HR = 1.89 (1.09-3.64)) women. Moreover, MetS-persistent women with neither hypertension nor diabetes had increased all-cause mortality risk by 88% (F/M-RHR = 3.99 (1.53-5.58)). Women with stable MetS had excess risk of cancer-mortality by 40% (F/M-RHR = 1.63 (1.02-5.06)). Generally, among both genders, recovery from MetS declined risk of mortality events. Regarding MetS components, persistent elevated fasting plasma glucose (FPG) was related to all-cause mortality in both genders, but with stronger association in women (F/M-RHR = 1.41 (1.11-2.49), and CV-mortality only in women (F/M-RHR = 3.04 (1.02-5.96). Both development and stable status of high blood pressure (BP) increased the risk of CV-mortality merely in women (F/M-RHR = 3.10 (0.60-6.87) and F/M-RHR = 3.24 (1.26-6.11), respectively). Development or recovery from each Triglyceride, HDL-C, and waist circumference variables did not solely affect risk of mortality events in both genders.

CONCLUSION

Stable status of MetS could increase risk of mortalities with an overall stronger association in women. Although elevated BP and FPG are the main drivers for mortality risk, MetS among women could carry the corresponding effect even in absence of hypertension and diabetes.

SGLT2 inhibitor ertugliflozin decreases elevated intracellular sodium, and improves energetics and contractile function in diabetic cardiomyopathy

BACKGROUND

Elevated myocardial intracellular sodium ([Na+]i) was shown to decrease mitochondrial calcium ([Ca2+]MITO) via mitochondrial sodium/calcium exchanger (NCXMITO), resulting in decreased mitochondrial ATP synthesis. The sodium-glucose co-transporter 2 inhibitor (SGLT2i) ertugliflozin (ERTU) improved energetic deficit and contractile dysfunction in a mouse model of high fat, high sucrose (HFHS) diet-induced diabetic cardiomyopathy (DCMP). As SGLT2is were shown to lower [Na+]i in isolated cardiomyocytes, we hypothesized that energetic improvement in DCMP is at least partially mediated by a decrease in abnormally elevated myocardial [Na+]i.

METHODS

Forty-two eight-week-old male C57BL/6J mice were fed a control or HFHS diet for six months. In the last month, a subgroup of HFHS-fed mice was treated with ERTU. At the end of the study, left ventricular contractile function and energetics were measured simultaneously in isolated beating hearts by 31P NMR (Nuclear Magnetic Resonance) spectroscopy. A subset of untreated HFHS hearts was perfused with vehicle vs. CGP 37157, an NCXMITO inhibitor. Myocardial [Na+]i was measured by 23Na NMR spectroscopy.

RESULTS

HFHS hearts showed diastolic dysfunction, decreased contractile reserve, and impaired energetics as reflected by decreased phosphocreatine (PCr) and PCr/ATP ratio. Myocardial [Na+]i was elevated > 2-fold in HFHS (vs. control diet). ERTU reversed the impairments in HFHS hearts to levels similar to or better than control diet and decreased myocardial [Na+]i to control levels. CGP 37157 normalized the PCr/ATP ratio in HFHS hearts.

CONCLUSIONS

Elevated myocardial [Na+]i contributes to mitochondrial and contractile dysfunction in DCMP. Targeting myocardial [Na+]i and/or NCXMITO may be an effective strategy in DCMP and other forms of heart disease associated with elevated myocardial [Na+]i.

Impact of Sex and Gender on Clinical Management of Patients with Advanced Chronic Liver Disease and Type 2 Diabetes

Gender differences in the epidemiology, pathophysiological mechanisms and clinical features in chronic liver diseases that may be associated with type 2 diabetes (T2D) have been increasingly reported in recent years. This sexual dimorphism is due to a complex interaction between sex- and gender-related factors, including biological, hormonal, psychological and socio-cultural variables. However, the impact of sex and gender on the management of T2D subjects with liver disease is still unclear. In this regard, sex-related differences deserve careful consideration in pharmacology, aimed at improving drug safety and optimising medical therapy, both in men and women with T2D; moreover, low adherence to and persistence of long-term drug treatment is more common among women. A better understanding of sex- and gender-related differences in this field would provide an opportunity for a tailored diagnostic and therapeutic approach to the management of T2D subjects with chronic liver disease. In this narrative review, we summarized available data on sex- and gender-related differences in chronic liver disease, including metabolic, autoimmune, alcoholic and virus-related forms and their potential evolution towards cirrhosis and/or hepatocarcinoma in T2D subjects, to support their appropriate and personalized clinical management.

Sex Differences in Cardiovascular Consequences of Hypertension, Obesity, and Diabetes: JACC Focus Seminar 4/7

It has long been recognized that there are significant differences between the sexes affecting prevalence, incidence, and severity over a broad range of diseases. Until the early 1990s, the limited research conducted on women's health focused primarily on diseases affecting fertility and reproduction, and women were excluded from most clinical trials. For these reasons, the prevention, diagnosis, and treatment of serious chronic diseases such as cardiovascular disease in women continue to be based primarily on findings in men, and sex-specific clinical guidelines are mostly lacking. Hypertension, obesity, and diabetes, interrelated risk factors for cardiovascular disease, differ by sex in terms of prevalence and adverse effects as well as by genetics and biology. Research is needed to understand sex differences in hypertension, obesity, and diabetes to optimally inform sex-specific prevention, diagnosis, and treatment strategies for women and men. In this way, sex-specific clinical guidelines can be developed where warranted.

Cellular interplay between cardiomyocytes and non-myocytes in diabetic cardiomyopathy

Patients with Type 2 diabetes mellitus (T2DM) frequently exhibit a distinctive cardiac phenotype known as diabetic cardiomyopathy. Cardiac complications associated with T2DM include cardiac inflammation, hypertrophy, fibrosis and diastolic dysfunction in the early stages of the disease, which can progress to systolic dysfunction and heart failure. Effective therapeutic options for diabetic cardiomyopathy are limited and often have conflicting results. The lack of effective treatments for diabetic cardiomyopathy is due in part, to our poor understanding of the disease development and progression, as well as a lack of robust and valid preclinical human models that can accurately recapitulate the pathophysiology of the human heart. In addition to cardiomyocytes, the heart contains a heterogeneous population of non-myocytes including fibroblasts, vascular cells, autonomic neurons and immune cells. These cardiac non-myocytes play important roles in cardiac homeostasis and disease, yet the effect of hyperglycaemia and hyperlipidaemia on these cell types are often overlooked in preclinical models of diabetic cardiomyopathy. The advent of human induced pluripotent stem cells provides a new paradigm in which to model diabetic cardiomyopathy as they can be differentiated into all cell types in the human heart. This review will discuss the roles of cardiac non-myocytes and their dynamic intercellular interactions in the pathogenesis of diabetic cardiomyopathy. We will also discuss the use of sodium-glucose cotransporter 2 inhibitors as a therapy for diabetic cardiomyopathy and their known impacts on non-myocytes. These developments will no doubt facilitate the discovery of novel treatment targets for preventing the onset and progression of diabetic cardiomyopathy.

Focus on today's evidence while keeping an eye on the future: lessons derived from hypertension in women

While evidence-based medicine has contributed enormously to the uniformity and rationale of patient care, it is necessary that we anticipate changes in order to implement their rapid translation to practice. The purpose of this review is to expose three issues regarding cardiovascular health in women, including milestones to reflect the pace at which these are incorporated into public policies. Two of these matters, as changes in the thresholds of normal blood pressure in gestation and in nonpregnant women, need further evidence and deserve to be retrospectively analyzed in high-quality databases. The third subject derives from the association of remote cardiovascular complications of hypertensive pregnancies, an example of the unnecessary delay of more than two decades to install a wide prevention strategy when the health system is not on the watch.

AAV9-Mediated Cardiac CNTF Overexpression Exacerbated Adverse Cardiac Remodeling in Streptozotocin-Induced Type 1 Diabetic Models

Ciliary neurotrophic factor (CNTF), which is a neural peptide, has been reported to confer cardioprotective effects. However, whether CNTF-based gene delivery could prevent cardiac remodeling in diabetes mellitus remains unknown. In this study, we used adeno-associated viral vector serotype 9 (AAV9)-based cardiac gene delivery to test the effects of CNTF overexpression on adverse ventricular remodeling in streptozotocin-induced type 1 diabetic mice models. Postnatal (P3-P10) mice were peritoneally injected with AAV9 recombinant virus carrying the CNTF gene or EGFP gene. Then, type 1 diabetic models were established by peritoneal injection of streptozotocin (200 mg/kg) in 7-week-old female mice injected with AAV9. 4 weeks later after the establishment of type 1 diabetes mellitus, mouse hearts were removed to assess the degree of cardiac remodeling. We found that CNTF overexpression in mouse cardiomyocytes exacerbated cell apoptosis and cardiac fibrosis coupled with an increased inflammatory response in the heart tissue of diabetic female mice. Taken together, our results suggested that cardiac CNTF gene delivery may not be beneficial in alleviating adverse cardiac remodeling in type 1 diabetes female mice.

Why the diabetic heart is energy inefficient: a ketogenesis and ketolysis perspective

Lack of glucose uptake compromises metabolic flexibility and reduces energy efficiency in the diabetes mellitus (DM) heart. Although increased use of fatty acid to compensate glucose substrate has been studied, less is known about ketone body metabolism in the DM heart. Ketogenic diet reduces obesity, a risk factor for T2DM. How ketogenic diet affects ketone metabolism in the DM heart remains unclear. At the metabolic level, the DM heart differs from the non-DM heart because of altered metabolic substrate and the T1DM heart differs from the T2DM heart because of insulin levels. How these changes affect ketone body metabolism in the DM heart are poorly understood. Ketogenesis produces ketone bodies by using acetyl-CoA, whereas ketolysis consumes ketone bodies to produce acetyl-CoA, showing their opposite roles in the ketone body metabolism. Cardiac-specific transgenic upregulation of ketogenesis enzyme or knockout of ketolysis enzyme causes metabolic abnormalities leading to cardiac dysfunction. Empirical evidence demonstrates upregulated transcription of ketogenesis enzymes, no change in the levels of ketone body transporters, very high levels of ketone bodies, and reduced expression and activity of ketolysis enzymes in the T1DM heart. Based on these observations, I hypothesize that increased transcription and activity of cardiac ketogenesis enzyme suppresses ketolysis enzyme in the DM heart, which decreases cardiac energy efficiency. The T1DM heart exhibits highly upregulated ketogenesis compared with the T2DM heart because of the lack of insulin, which inhibits ketogenesis enzyme.

Male and Female Rats Have Different Physiological Response to High-Fat High-Sucrose Diet but Similar Myocardial Sensitivity to Ischemia-Reperfusion Injury

Prediabetes is a strong predictor of type 2 diabetes and its associated cardiovascular complications, but few studies explore sexual dimorphism in this context. Here, we aim to determine whether sex influences physiological response to high-fat high-sucrose diet (HFS) and myocardial tolerance to ischemia-reperfusion injury. Male and female Wistar rats were subjected to standard (CTRL) or HFS diet for 5 months. Then, ex-vivo experiments on isolated perfused heart model were performed to evaluate tolerance to ischemia-reperfusion injury. HFS diet induced fasting hyperglycemia and increased body fat percent to a similar level in both sexes. However, glucose intolerance was more pronounced in female HFS. Cholesterol was increased only in female while male displayed higher level of plasmatic leptin. We observed increased heart weight to tibia length ratio only in males, but we showed a similar decrease in tolerance to ischemia-reperfusion injury in female and male HFS compared with respective controls, characterized by impaired cardiac function, energy metabolism and coronary flow during reperfusion. In conclusion, as soon as glucose intolerance and hyperglycemia develop, we observe higher sensitivity of hearts to ischemia-reperfusion injury without difference between males and females.