Using human genetics to understand the disease impacts of testosterone in men and women

Stress, Sex, and Sugar: Glucocorticoids and Sex-Steroid Crosstalk in the Sex-Specific Misprogramming of Metabolism

Early-life exposures to environmental insults can misprogram development and increase metabolic disease risk in a sex-dependent manner by mechanisms that remain poorly characterized. Modifiable factors of increasing public health relevance, such as diet, psychological stress, and endocrine-disrupting chemicals, can affect glucocorticoid receptor signaling during gestation and lead to sex-specific postnatal metabolic derangements. Evidence from humans and animal studies indicate that glucocorticoids crosstalk with sex steroids by several mechanisms in multiple tissues and can affect sex-steroid-dependent developmental processes. Nonetheless, glucocorticoid sex-steroid crosstalk has not been considered in the glucocorticoid-induced misprogramming of metabolism. Herein we review what is known about the mechanisms by which glucocorticoids crosstalk with estrogen, androgen, and progestogen action. We propose that glucocorticoid sex-steroid crosstalk is an understudied mechanism of action that requires consideration when examining the developmental misprogramming of metabolism, especially when assessing sex-specific outcomes.

The Potential Effect of Aberrant Testosterone Levels on Common Diseases: A Mendelian Randomization Study

Testosterone has historically been linked to sexual dysfunction; however, it has recently been shown to affect other physical and mental attributes. We attempted to determine whether changes in serum testosterone could play a role in chronic or degenerative diseases. We used two separate genetic instruments comprising of variants from JMJD1C and SHBG regions and conducted a two-sample Mendelian randomization for type II diabetes (T2D), gout, rheumatoid arthritis (RA), schizophrenia, bipolar disorder, Alzheimer's disease and depression. For the JMJD1C locus, one unit increase in log transformed testosterone was significantly associated with RA (OR = 1.69, p = 0.02), gout (OR = 0.469, p = 0.001) and T2D (OR = 0.769, p = 0.048). Similarly, one unit increase in log transformed testosterone using variants from the SHBG locus was associated with depression (OR = 1.02, p < 0.0001), RA (OR = 1.254, p < 0.0001) and T2D (OR = 0.88, p < 0.0001). Our results show that low levels of serum testosterone levels may cause gout and T2D, while higher than normal levels of testosterone may result in RA and depression. Our findings suggest that fluctuations in testosterone levels may have severe consequences that warrant further investigation.

The role of testosterone in chronic kidney disease and kidney function in men and women: a bi-directional Mendelian randomization study in the UK Biobank

BACKGROUND

Chronic kidney disease (CKD) has an apparent sex disparity, with a more rapid progress in men than in women. Whether the well-established sex-specific evolutionary biology trade-off between reproduction and longevity might inform CKD has not previously been considered. Relevant evidence from randomized controlled trials (RCTs) is not available.

METHODS

We used a bi-directional Mendelian randomization study to obtain unconfounded estimates using the UK Biobank. Single nucleotide polymorphisms (SNPs) that strongly (p value < 5 × 10^-8) predicted testosterone in a sex-specific manner were applied to 179,916 white British men (6016 CKD cases) and 212,079 white British women (5958 CKD cases) to obtain sex-specific associations with CKD, albuminuria, and estimated glomerular filtration rate (eGFR). We also used multivariable MR to control for sex hormone binding globulin (SHBG). For validation, we similarly examined their role in hemoglobin and high-density lipoprotein cholesterol (HDL-c). We also assessed the role of kidney function in serum testosterone, by applying eGFR-related SNPs to testosterone in the UK Biobank.

RESULTS

Genetically predicted testosterone was associated with CKD in men (odds ratio (OR) for bioavailable testosterone 1.17 per standard deviation, 95% confidence interval (CI) 1.03 to 1.33) based on 125 SNPs but not in women (OR 1.02, 95% CI 0.92 to 1.14 for total testosterone) based on 254 SNPs. Multivariable MR allowing for SHBG showed consistent patterns. Genetically predicted bioavailable testosterone in men and women and genetically predicted total testosterone in women increased hemoglobin and lowered HDL-c, as seen in RCTs. Genetically predicted eGFR was not related to serum testosterone in men or in women.

CONCLUSIONS

Genetically predicted testosterone was associated with CKD and worse kidney function in men, whilst not affected by kidney function. Identifying drivers of testosterone and the underlying pathways could provide new insights into CKD prevention and treatment.

Androgen sensitivity gateway to COVID-19 disease severity

In this communication, we present arguments for androgen sensitivity as a likely determinant of COVID‐19 disease severity. The androgen sensitivity model explains why males are more likely to develop severe symptoms while children are ostensibly resistant to infection. Further, the model explains the difference in COVID‐19 mortality rates among different ethnicities. Androgen sensitivity is determined by genetic variants of the androgen receptor. The androgen receptor regulates transcription of the transmembrane protease, serine 2 (TMPRSS2), which is required for SARS‐CoV‐2 infectivity. TMPRSS2 primes the Spike protein of the virus, which has two consequences: diminishing viral recognition by neutralizing antibodies and activating SARS‐CoV‐2 for virus‐cell fusion. Genetic variants that have been associated with androgenetic alopecia, prostate cancer, benign prostatic hyperplasia and polycystic ovary syndrome could be associated with host susceptibility. In addition to theoretical epidemiological and molecular mechanisms, there are reports of high rates of androgenetic alopecia of from hospitalized COVID‐19 patients due to severe symptoms. Androgen sensitivity is a likely determinant of COVID‐19 disease severity. We believe that the evidence presented in this communication warrants the initiation of trials using anti‐androgen agents.

Endogenous Testosterone Levels Are Associated with Risk of Type 2 Diabetes in Women without Established Comorbidity

Purpose

The impact of endogenous androgen levels on the risk of type 2 diabetes in women remains uncertain. The objective was to investigate associations between endogenous androgen levels and risk of type 2 diabetes in young women without established comorbidity.

Methods

In this retrospective cohort study, women aged 18 to 50 years who underwent measurement of plasma testosterone, dehydroepiandrosterone-sulfate (DHEA-S), dihydrotestosterone (DHT), and sex hormone-binding globulin (SHBG) for the first time from January 2007 to December 2015 were included. Androgens were analyzed using tandem liquid chromatography mass spectrometry. Women with established comorbidity were excluded, using Danish healthcare registries. We calculated incidence rate ratios (IRRs, 95% confidence intervals) of type 2 diabetes according to quartiles of plasma androgens using multivariate Poisson regression models.

Results

A total of 8876 women, with a mean ± SD age of 38.5 ± 4.6 years and a median (interquartile range [IQR]) follow-up duration of 8.1 (6.6-9.4) years, were eligible for analyses. During 69 728 person-years, 69 women were diagnosed with type 2 diabetes. Women in the highest quartile of plasma total testosterone and calculated free testosterone displayed increased risk of type 2 diabetes compared with the lowest quartile: IRR 1.97 (1.01; 3.85), P = .048 and IRR 7.32 (2.84; 18.83), P < .001. SHBG was inversely associated with type 2 diabetes, Q4 versus Q1; IRR 0.06 (0.02; 0.21), P < .001. Plasma DHEA-S and DHT were not associated with incident type 2 diabetes.

Conclusions

Higher levels of plasma total and free testosterone were associated with increased risk of type 2 diabetes among women.

Implicating androgen excess in propagating metabolic disease in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) has been traditionally perceived as a reproductive disorder due to its most common presentation with menstrual dysfunction and infertility. However, it is now clear that women with PCOS are at increased risk of metabolic dysfunction, from impaired glucose tolerance and type 2 diabetes mellitus to nonalcoholic fatty liver disease and cardiovascular disease. PCOS is characterised by androgen excess, with cross-sectional data showing that hyperandrogenism is directly complicit in the development of metabolic complications. Recent studies have also shown that C11-oxy _C19 androgens are emerging to be clinically and biochemically significant in PCOS, thus emphasising the importance of understanding the impact of both classic and C11-oxy _C19 androgens on women's health. Here we discuss androgen metabolism in the context of PCOS, and dissect the role played by androgens in the development of metabolic disease through their effects on metabolic target tissues in women.