Obesity and statins are both independent predictors of enhanced coronary arteriolar dilation in patients undergoing heart surgery

Role of Caveolae in the Development of Microvascular Dysfunction and Hyperglycemia in Type 2 Diabetes

In type 2 diabetes (T2D) microvascular dysfunction can interfere with tissue glucose uptake thereby contributing to the development of hyperglycemia. The cell membrane caveolae orchestrate signaling pathways that include microvascular control of tissue perfusion. In this study, we examined the role of caveolae in the regulation of microvascular vasomotor function under the condition of hyperglycemia in T2D patients and rodent models. Human coronary arterioles were obtained during cardiac surgery from T2D patients, with higher perioperative glucose levels, and from normoglycemic, non-diabetic controls. The coronary arteriole responses to pharmacological agonists bradykinin and acetylcholine were similar in T2D and non-diabetic patients, however, exposure of the isolated arteries to methyl-β-cyclodextrin (mβCD), an agent known to disrupt caveolae, reduced vasodilation to bradykinin selectively in T2D subjects and converted acetylcholine-induced vasoconstriction to dilation similarly in the two groups. Dilation to the vascular smooth muscle acting nitric oxide donor, sodium nitroprusside, was not affected by mβCD in either group. Moreover, mβCD reduced endothelium-dependent arteriolar dilation to a greater extent in hyperglycemic and obese db/db mice than in the non-diabetic controls. Mechanistically, when fed a high-fat diet (HFD), caveolin-1 knockout mice, lacking caveolae, exhibited a significantly reduced endothelium-dependent arteriolar dilation, both ex vivo and in vivo, which was accompanied by significantly higher serum glucose levels, when compared to HFD fed wild type controls. Thus, in T2D arterioles the role of caveolae in regulating endothelium-dependent arteriole dilation is altered, which appears to maintain vasodilation and mitigate the extent of hyperglycemia. While caveolae play a unique role in microvascular vasomotor regulation, under the condition of hyperglycemia arterioles from T2D subjects appear to be more susceptible for caveolae disruption-associated vasomotor dysfunction and impaired glycemic control.

Evaluation of glycemic status among hypercholesterolemic patients on atorvastatin in a tertiary care hospital - A retrospective study

INTRODUCTION

Statins are effective in reducing low-density lipoprotein cholesterol and are favorable in primary and secondary prevention of cardiovascular disease. Recent large trials have linked the use of statins and increased incidence of new-onset diabetes mellitus, the possibility of worsening of glucose level in individuals with diabetes following statin therapy, and this possibility is increased with the use of atorvastatin. This study was undertaken to analyze the possibility of the diabetogenic potential of atorvastatin among hypercholesterolemic patients.

MATERIALS AND METHODS

This retrospective cohort study was conducted in the cardiology department from July 2019 to December 2019. Patients on atorvastatin for more than 6 months with normoglycemia on commencement of therapy were included. The occurrence of prediabetes or new-onset diabetes mellitus after atorvastatin therapy is the outcome of the study. Adverse drug effects to atorvastatin were also recorded and WHO-UMC causality assessment was performed. Descriptive statistics were performed for baseline and demographic characteristics.

RESULTS

Sixty study participants were included in the study. Eighteen (30%) study participants developed prediabetes with an HbA1c value of 5.97 ± 0.22 and 17 (28%) of participants developed new-onset diabetes mellitus with an HbA1c value of 7.24 ± 0.50. Atorvastatin at dose of 40 mg was found to be the most frequently prescribed dose.

CONCLUSION

Atorvastatin has a dose-dependent risk of developing new-onset diabetes mellitus. Hence, the following statin therapy glycemic status should be periodically monitored especially in patients with a large dose of atorvastatin and also in patients with higher risk factors for diabetes.

Analysis of glycemic status in diabetes-naïve patients on statins: A hospital-based cross-sectional study

INTRODUCTION:

Randomized controlled trials, observational studies, and meta-analysis suggest risk of hyperglycemia in patients on statins, and this association is being viewed with renewed interest globally. The present study has tried to explore the possible diabetogenic effect of statins, the mechanism of this effect, and various comorbidities associated with this causation.

MATERIALS AND METHODS:

This cross-sectional study was carried out at the Department of Cardiology from October 2015 to March 2017. Patients on statins for at least 1 year and normoglycemic at the time of statin initiation were recruited in the study. The outcome of the present study was development of new-onset diabetes mellitus (NODM). Blood glucose levels and insulin levels were estimated. Other adverse reactions of statins and associated comorbidities in the patients were recorded. Descriptive statistics were used to analyze adverse drug reactions.

RESULTS:

A total of 104 patients met the inclusion criteria, of which eight patients (7.7%) developed NODM and 4 (3.8%) developed prediabetes. Atorvastatin 40 mg was most commonly prescribed statin. About 25% of patients taking atorvastatin 80 mg developed diabetes

CONCLUSION:

Statins have a mild-to-moderate risk of developing NODM. The dose of statins is an important factor that increases the risk of diabetes in statin users

Role of Adipose Tissue Endothelial ADAM17 in Age-Related Coronary Microvascular Dysfunction

OBJECTIVE

A disintegrin and metalloproteinase ADAM17 (tumor necrosis factor-α [TNF]-converting enzyme) regulates soluble TNF levels. We tested the hypothesis that aging-induced activation in adipose tissue (AT)-expressed ADAM17 contributes to the development of remote coronary microvascular dysfunction in obesity.

APPROACH AND RESULTS

Coronary arterioles (CAs, ≈90 µm) from right atrial appendages and mediastinal AT were examined in patients (aged: 69±11 years, BMI: 30.2±5.6 kg/m²) who underwent open heart surgery. CA and AT were also studied in 6-month and 24-month lean and obese mice fed a normal or high-fat diet. We found that obesity elicited impaired endothelium-dependent CA dilations only in older patients and in aged high-fat diet mice. Transplantation of AT from aged obese, but not from young or aged, mice increased serum cytokine levels, including TNF, and impaired CA dilation in the young recipient mice. In patients and mice, obesity was accompanied by age-related activation of ADAM17, which was attributed to vascular endothelium-expressed ADAM17. Excess, ADAM17-shed TNF from AT arteries in older obese patients was sufficient to impair CA dilation in a bioassay in which the AT artery was serially connected to a CA. Moreover, we found that the increased activity of endothelial ADAM17 is mediated by a diminished inhibitory interaction with caveolin-1, owing to age-related decline in caveolin-1 expression in obese patients and mice or to genetic deletion of caveolin-1.

CONCLUSIONS

The present study indicates that aging and obesity cooperatively reduce caveolin-1 expression and increase vascular endothelial ADAM17 activity and soluble TNF release in AT, which may contribute to the development of remote coronary microvascular dysfunction in older obese patients.