Factors influencing endothelial function in healthy pre- and post-menopausal women of the EU-RISC study

Mechanisms of leptin-induced endothelial dysfunction

PURPOSE OF REVIEW

Endothelial dysfunction is a major risk factor for many cardiovascular diseases, notably hypertension. Obesity increases the risk of endothelial dysfunction in association with increasing production of the adipokine leptin. Preclinical studies have begun to unravel the mechanisms whereby leptin leads to the development of endothelial dysfunction, which are sex-specific. This review will summarize recent findings of mechanisms of leptin-induced endothelial impairment in both male and females and in pregnancy.

RECENT FINDINGS

Leptin receptors are found in high concentrations in the central nervous system (CNS), via which leptin promotes appetite suppression and upregulates sympathetic nervous system activation. However, leptin receptors are expressed in many other tissues, including the vascular endothelial cells and smooth muscle cells. Recent studies in mice with vascular endothelial or smooth muscle-specific knockdown demonstrate that endothelial leptin receptor activation plays a protective role against endothelial dysfunction in male animals, but not necessarily in females. Clinical studies indicate that women may be more sensitive to obesity-associated vascular endothelial dysfunction. Emerging preclinical data indicates that leptin and progesterone increase aldosterone production and endothelial mineralocorticoid receptor activation, respectively. Furthermore, decades of clinical studies indicate that leptin levels increase in the hypertensive pregnancy disorder preeclampsia, which is characterized by systemic endothelial dysfunction. Leptin infusion in mice induces the clinical characteristics of preeclampsia, including endothelial dysfunction.

SUMMARY

Novel preclinical data indicate that the mechanisms whereby leptin promotes endothelial dysfunction are sex-specific. Leptin-induced endothelial dysfunction may also play a role in hypertensive pregnancy as well.

Effects of a 12-Week Web-Based Weight Loss Program for Adults With Overweight and Obesity on COVIDAge and Lifestyle-Related Cardiometabolic Risk Factors: A Randomized Controlled Trial

The coronavirus disease 2019 (COVID-19) pandemic has induced unhealthy lifestyles, particularly an increase in overweight and obesity, which have been shown to be associated with an increased risk of unfavorable COVID-19 outcomes. Web-based health programs could be a helpful measure, especially in times of severe restrictions. Therefore, the present study aimed to investigate the effects of regular attendance in a 12-week web-based weight loss program on COVIDAge, a new construct for risk assessment of COVID-19, and lifestyle-related cardiometabolic risk factors. N = 92 subjects with overweight and obesity (50.0 ± 10.8 years, 76.1% females, 30.5 ± 2.1 kg/m²) of this randomized controlled trial, which were assigned to an interactive (ONLINE: intervention group) or non-interactive (CON: control group) web-based weight loss program, were included in the data analysis. COVIDAge and cardiometabolic risk factors, including anthropometric outcomes, blood pressure, flow-mediated dilatation, and blood parameters, were assessed before and after the 12-week intervention phase. There was a significant group difference in the change of COVIDAge (ONLINE: −4.2%, CON: −1.3%, p = 0.037). The ONLINE group also showed significantly greater reductions in anthropometric outcomes and systolic blood pressure than the CON group (p < 0.05). To the authors' knowledge, this was the first study investigating the effects of regular attendance in a web-based health program on lifestyle-related risk factors for COVID-19. The results demonstrated that adults with overweight and obesity can improve their COVIDAge and specific cardiometabolic risk factors by using this interactive web-based weight loss program regularly. However, this needs to be confirmed by future studies. This study is registered at the German Clinical Trials Register (DRKS00020249, https://www.drks.de).

A review of menopause nomenclature

Menopause nomenclature varies in the scholarly literature making synthesis and interpretation of research findings difficult. Therefore, the present study aimed to review and discuss critical developments in menopause nomenclature; determine the level of heterogeneity amongst menopause definitions and compare them with the Stages of Reproductive Aging Workshop criteria. Definitions/criteria used to characterise premenopausal and postmenopausal status were extracted from 210 studies and 128 of these studies were included in the final analyses. The main findings were that 39.84% of included studies were consistent with STRAW classification of premenopause, whereas 70.31% were consistent with STRAW classification of postmenopause. Surprisingly, major inconsistencies relating to premenopause definition were due to a total lack of reporting of any definitions/criteria for premenopause (39.84% of studies). In contrast, only 20.31% did not report definitions/criteria for postmenopause. The present findings indicate that there is a significant amount of heterogeneity associated with the definition of premenopause, compared with postmenopause. We propose three key suggestions/recommendations, which can be distilled from these findings. Firstly, premenopause should be transparently operationalised and reported. Secondly, as a minimum requirement, regular menstruation should be defined as the number of menstrual cycles in a period of at least 3 months. Finally, the utility of introducing normative age-ranges as supplementary criterion for defining stages of reproductive ageing should be considered. The use of consistent terminology in research will enhance our capacity to compare results from different studies and more effectively investigate issues related to women's health and ageing.

Fat mass changes during menopause: a metaanalysis

OBJECTIVE

Data: Fat mass has been shown to increase in aging women; however, the extent to which menopausal status mediates these changes remains unclear. The purpose of this review was to determine (1) how fat mass differs in quantity and distribution between premenopausal and postmenopausal women, (2) whether and how age and/or menopausal status moderates any observed differences, and (3) which type of fat mass measure is best suited to the detection of differences in fat mass between groups.

STUDY

This review with metaanalyses is reported according to Metaanalysis of Observational Studies in Epidemiology guidelines.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies (published up to May 2018) were identified via PubMed to provide fat mass measures in premenopausal and postmenopausal women. We included 201 cross-sectional studies in the metaanalysis, which provided a combined sample size of 1,049,919 individuals and consisted of 478,734 premenopausal women and 571,185 postmenopausal women. Eleven longitudinal studies were included in the metaanalyses, which provided a combined sample size of 2472 women who were premenopausal at baseline and postmenopausal at follow up.

RESULTS

The main findings of this review were that fat mass significantly increased between premenopausal and postmenopausal women across most measures, which included body mass index (1.14 kg/m²; 95% confidence interval, 0.95-1.32 kg/m²), bodyweight (1 kg; 95% confidence interval, 0.44-1.57 kg), body fat percentage (2.88%; 95% confidence interval, 2.13-3.63%), waist circumference (4.63 cm; 95% confidence interval, 3.90-5.35 cm), hip circumference (2.01 cm; 95% confidence interval, 1.36-2.65 cm), waist-hip ratio (0.04; 95% confidence interval, 0.03-0.05), visceral fat (26.90 cm²; 95% confidence interval, 13.12-40.68), and trunk fat percentage (5.49%; 95% confidence interval, 3.91-7.06 cm²). The exception was total leg fat percentage, which significantly decreased (-3.19%; 95% confidence interval, -5.98 to -0.41%). No interactive effects were observed between menopausal status and age across all fat mass measures.

CONCLUSION

The change in fat mass quantity between premenopausal and postmenopausal women was attributable predominantly to increasing age; menopause had no significant additional influence. However, the decrease in total leg fat percentage and increase in measures of central fat are indicative of a possible change in fat mass distribution after menopause. These changes are likely to, at least in part, be due to hormonal shifts that occur during midlife when women have a higher androgen (ie, testosterone) to estradiol ratio after menopause, which has been linked to enhanced central adiposity deposition. Evidently, these findings suggest attention should be paid to the accumulation of central fat after menopause, whereas increases in total fat mass should be monitored consistently across the lifespan.

Insulin resistance is associated with lower acetylcholine-induced microvascular reactivity in nondiabetic women

BACKGROUND

The association between insulin resistance and microvascular dysfunction is well established in obese individuals with type 2 diabetes. It is unclear whether this relationship is dependent on obesity and body fat in insulin-resistant persons. This study investigated acetylcholine (ACh)-induced microvascular reactivity in apparently healthy women (n=37, 20-45 years), with and without insulin resistance.

METHODS

Body fat mass (dual X-ray absorptiometry), waist circumference (WC), blood pressure, fasting glucose, insulin, and free fatty acid concentrations were measured. Insulin resistance was estimated using homeostasis model assessment of insulin resistance (HOMA-IR), and subjects were divided into insulin-resistant (IR, n=16) and insulin-sensitive (IS, n=21) groups. ACh-induced forearm microvascular reactivity was measured by laser Doppler imagery using iontophoresis of ACh and compared between groups adjusting for WC and skin resistance (SR).

RESULTS

The IR group had a higher body mass index (BMI) (30.7 ± 6.4 vs. 22.9 ± 7.3 kg/m(2), P < 0.01), fat mass (34.7 ± 11.9 vs. 19.7 ± 9.6 kg, P < 0.01), WC (89.9 ± 13.6 vs. 74.4 ± 9.7 cm, P < 0.01), and a lower SR (0.24 ± 0.08 vs. 0.32 ± 0.08 Ω, P < 0.05) than the IS group. Microvascular reactivity, expressed as percentage increase in perfusion from baseline, was significantly lower in IR subjects after adjusting for differences in WC and SR (420.9 ± 166.5 vs. 511.6 ± 214.8%, P < 0.05). There were associations between microvascular reactivity and SR (r=-0.34, P < 0.05) and systolic blood pressure (r=-0.36, P < 0.05), but not BMI, body fat mass, WC, or HOMA-IR.

CONCLUSION

ACh-induced microvascular reactivity was different between IR and IS apparently healthy, nondiabetic women once differences in WC and SR were accounted for.