Management of cardiovascular complications in Klinefelter syndrome patients

Genetics of hypertension-related sex differences and hypertensive disorders of pregnancy

Background: Hypertension and hypertensive disorders of pregnancy (HDP) cause a significant burden of disease on societies and individuals by increasing cardiovascular disease risk. Environmental risk factors alone do not explain the observed sexual dimorphism in lifetime blood pressure (BP) trajectories nor inter-individual variation in HDP risk.

Methods: In this short review, we focus on the genetics of hypertension-related sex differences and HDP and discuss the importance of genetics utilization for sex-specific hypertension risk prediction.

Results: Population and twin studies estimate that 28-66% of variation in BP levels and HDP is explained by genetic variation, while genomic wide association studies suggest that BP traits and HDP partly share a common genetic background. Moreover, environmental and epigenetic regulation of these genes differ by sex and oestrogen receptors in particular are shown to convey cardio- and vasculoprotective effects through epigenetic regulation of DNA. The majority of known genetic variation in hypertension and HDP is polygenic. Polygenic risk scores for BP display stronger associations with hypertension risk in women than in men and are associated with sex-specific age of hypertension onset. Monogenic forms of hypertension are rare and mostly present equally in both sexes.

Conclusion: Despite recent genetic discoveries providing new insights into HDP and sex differences in BP traits, further research is needed to elucidate the underlying biology. Emphasis should be placed on demonstrating the added clinical value of these genetic discoveries, which may eventually facilitate genomics-based personalized treatments for hypertension and HDP.

Extragonadal function of follicle-stimulating hormone: Evidence for a role in endothelial physiology and dysfunction

AIMS

Follicle-stimulating hormone (FSH) plays a fundamental role in reproduction stimulating ovarian folliculogenesis, Sertoli cells function and spermatogenesis. However, the recent identification of FSH receptor (FSHR) also in extra-gonadal tissues has suggested that FSH activity may not be limited only to fertility regulation, with conflicting results on the possible role of FSH in endothelial cells. The aim of this study was to investigate FSH role on endothelial function in Human Umbilical Vein Endothelial Cells (HUVECs).

RESULTS

Endothelial Nitric oxide synthase (eNOS) expression, eNOS phosphorylation and Nitric Oxide (NO) production resulted increased after the stimulation of HUVEC with recombinant human FSH (rhFSH) at 3.6x103 ng/ml, with increasing Calcium release from intracellular stores. Furthermore, IP3 production increased after rhFSH stimulation despite PTX treatment and NFAT1 was observed prevalently in nucleus. We observed a statistical difference between untreated cells and cells stimulated with 0.36x103 ng/ml and between cells stimulated with 0.36x103 ng/ml and cells stimulated with 1.8x103 ng/ml at 4 and 8 h by Wound healing assay, respectively. Furthermore, a higher cellular permeability was observed in stimulated cells, with atypical VE-cadherin distribution, as well as filamentous actin.

CONCLUSIONS

Our findings suggest that FSH at high concentrations elicits a signalling that could compromise the endothelial membrane. Indeed, VE-cadherin anomalies may severely affect the endothelial barrier, resulting in an increased membrane permeability. Although NO is an important vasodilatation factor, probably an excessive production could impact on endothelial functionality, partially explaining the increased risk of cardiovascular diseases in menopausal women and men with hypogonadism.

Sex chromosome mechanisms in cardiac development and disease

Many human diseases, including cardiovascular disease, show differences between men and women in pathology and treatment outcomes. In the case of cardiac disease, sex differences are exemplified by differences in the frequency of specific types of congenital and adult-onset heart disease. Clinical studies have suggested that gonadal hormones are a factor in sex bias. However, recent research has shown that gene and protein networks under non-hormonal control also account for cardiac sex differences. In this review, we describe the sex chromosome pathways that lead to sex differences in the development and function of the heart and highlight how these findings affect future care and treatment of cardiac disease.

Genetic, Molecular, and Cellular Determinants of Sex-Specific Cardiovascular Traits

Despite the well-known sex dimorphism in cardiovascular disease traits, the exact genetic, molecular, and cellular underpinnings of these differences are not well understood. A growing body of evidence currently points at the links between cardiovascular disease traits and the genome, epigenome, transcriptome, and metabolome. However, the sex-specific differences in these links remain largely unstudied due to challenges in bioinformatic methods, inadequate statistical power, analytic costs, and paucity of valid experimental models. This review article provides an overview of the literature on sex differences in genetic architecture, heritability, epigenetic changes, transcriptomic signatures, and metabolomic profiles in relation to cardiovascular disease traits. We also review the literature on the associations between sex hormones and cardiovascular disease traits and discuss the potential mechanisms underlying these associations, focusing on human studies.

In-vivo skeletal muscle mitochondrial function in Klinefelter syndrome

Klinefelter syndrome (XXY) occurs in 1 in 600 males, resulting in testosterone deficiency and a high prevalence of insulin resistance. Testosterone deficiency in men is a known cause of insulin resistance, and mitochondrial dysfunction is hypothesized to mediate this relationship. The aim of this cross-sectional study was to evaluate muscle mitochondrial function in XXY compared with male controls. Twenty-seven boys with XXY (age 14.7±1.8 years) were compared with 87 controls (age 16.9±0.9). In-vivo calf muscle mitochondrial function was assessed via phosphorus magnetic resonance spectroscopy (³¹P-MRS) following 90 s of isometric 70% maximal exercise. Multiple linear regression was used to compare ³¹P-MRS outcomes (ADP and phosphocreatine (PCr) time constants, rate of oxidative phosphorylation (Oxphos), and Q_max or the maximal mitochondrial function relative to mitochondrial density) between groups after adjusting for age differences. There were no statistically significant differences in the mitochondrial outcomes of ADP, Oxphos, PCr, and Q_max between the groups. There were also no differences in a sensitivity analysis within the XXY group by testosterone treatment status. In this study, in-vivo postexercise skeletal muscle mitochondrial function does not appear to be impaired in adolescents with XXY compared with controls and is not significantly different by testosterone treatment status in XXY.

Considering Sex as a Biological Variable in Basic and Clinical Studies: An Endocrine Society Scientific Statement

In May 2014, the National Institutes of Health (NIH) stated its intent to "require applicants to consider sex as a biological variable (SABV) in the design and analysis of NIH-funded research involving animals and cells." Since then, proposed research plans that include animals routinely state that both sexes/genders will be used; however, in many instances, researchers and reviewers are at a loss about the issue of sex differences. Moreover, the terms sex and gender are used interchangeably by many researchers, further complicating the issue. In addition, the sex or gender of the researcher might influence study outcomes, especially those concerning behavioral studies, in both animals and humans. The act of observation may change the outcome (the "observer effect") and any experimental manipulation, no matter how well-controlled, is subject to it. This is nowhere more applicable than in physiology and behavior. The sex of established cultured cell lines is another issue, in addition to aneuploidy; chromosomal numbers can change as cells are passaged. Additionally, culture medium contains steroids, growth hormone, and insulin that might influence expression of various genes. These issues often are not taken into account, determined, or even considered. Issues pertaining to the "sex" of cultured cells are beyond the scope of this Statement. However, we will discuss the factors that influence sex and gender in both basic research (that using animal models) and clinical research (that involving human subjects), as well as in some areas of science where sex differences are routinely studied. Sex differences in baseline physiology and associated mechanisms form the foundation for understanding sex differences in diseases pathology, treatments, and outcomes. The purpose of this Statement is to highlight lessons learned, caveats, and what to consider when evaluating data pertaining to sex differences, using 3 areas of research as examples; it is not intended to serve as a guideline for research design.