The androgen receptor gene CAG repeat in relation to 4-year changes in androgen-sensitive endpoints in community-dwelling older European men

Optimal injection interval for testosterone undecanoate treatment of hypogonadal and transgender men

OBJECTIVE

To define the optimized inter-injection interval of injectable testosterone undecanoate (TU) treatment for hypogonadal and transmen based on individual dose titration in routine clinical practice.

DESIGN AND METHODS

A prolective observational study of consecutive TU injections in men undergoing testosterone replacement therapy for pathological hypogonadism or masculinization of female-to-male transgender (transmen) subject to individual dosing titration to achieve a stable replacement regimen.

RESULTS

From 2006 to 2019, 6899 injections were given to 325 consecutive patients. After excluding the 6-week loading dose, 6300 injections were given to 297 patients who had at least three and a median of 14 injections. The optimal injection interval (mean of last three injection intervals) had a median of 12.0 weeks (interquartile range 10.4-12.7 weeks). The interval was significantly influenced by age and body size (body surface area, BSA) but not by diagnosis or trough serum LH, FSH, and SHBG. Longer (≥14 weeks; 68/297, 23%), but not shorter (≤10 weeks; 22/297, 7.4%), intervals were weakly correlated with age but not diagnosis or other covariables. Low blood hemoglobin increased with trough serum testosterone to reach plateau once testosterone was about 10 nmol/L or higher.

CONCLUSION

Optimal intervals between TU injection after individual titration resulted in the approved 12-week interval in 70% of patients with only minor influence for clinical application of BSA and not of trough serum LH, FSH, and SHBG. Individually optimized inter-injection interval did not differ between men with primary or secondary hypogonadism or transmen.

Shorter androgen receptor polyQ alleles protect against life-threatening COVID-19 disease in European males

Background

While SARS-CoV-2 similarly infects men and women, COVID-19 outcome is less favorable in men. Variability in COVID-19 severity may be explained by differences in the host genome.

Methods

We compared poly-amino acids variability from WES data in severely affected COVID-19 patients versus SARS-CoV-2 PCR-positive oligo-asymptomatic subjects.

Findings

Shorter polyQ alleles (≤22) in the androgen receptor (AR) conferred protection against severe outcome in COVID-19 in the first tested cohort (both males and females) of 638 Italian subjects. The association between long polyQ alleles (≥23) and severe clinical outcome (p = 0.024) was also validated in an independent cohort of Spanish men <60 years of age (p = 0.014). Testosterone was higher in subjects with AR long-polyQ, possibly indicating receptor resistance (p = 0.042 Mann-Whitney U test). Inappropriately low serum testosterone level among carriers of the long-polyQ alleles (p = 0.0004 Mann-Whitney U test) predicted the need for intensive care in COVID-19 infected men. In agreement with the known anti-inflammatory action of testosterone, patients with long-polyQ and age ≥60 years had increased levels of CRP (p = 0.018, not accounting for multiple testing).

Interpretation

We identify the first genetic polymorphism that appears to predispose some men to develop more severe disease. Failure of the endocrine feedback to overcome AR signaling defects by increasing testosterone levels during the infection leads to the polyQ tract becoming dominant to serum testosterone levels for the clinical outcome. These results may contribute to designing reliable clinical and public health measures and provide a rationale to test testosterone as adjuvant therapy in men with COVID-19 expressing long AR polyQ repeats.

Funding

MIUR project “Dipartimenti di Eccellenza 2018-2020” to Department of Medical Biotechnologies University of Siena, Italy (Italian D.L. n.18 March 17, 2020) and “Bando Ricerca COVID-19 Toscana” project to Azienda Ospedaliero-Universitaria Senese. Private donors for COVID-19 research and charity funds from Intesa San Paolo.

The Relation Between Steroid Secretion Patterns and the Androgen Receptor Gene Polymorphism on Physical Health and Psychological Well-Being-Longitudinal Findings From the Men's Health 40+ Study

Research is increasingly focusing on promoting healthy aging and the related extension of the health span by targeting crucial biological processes responsible for age-related conditions. While age-related gradual changes in steroid hormones such as testosterone, estradiol, or cortisol are well described in men, their interactions among each other or with genetic markers have not been sufficiently investigated with regard to physical health or psychological well-being. More specifically, the examination of age-related alterations in hormone interactions and the androgen receptor polymorphism, which modulates androgen action on target cells, in relation to physical health and psychological well-being represents a promising avenue for research on healthy aging in men. A total of 97 healthy aging men provided complete data on psychometric health measures as well as hormonal and genetic parameters at baseline and a 4-year follow-up assessment. Fasting saliva samples were taken at 8:00 am under standardized laboratory conditions, while the androgen receptor gene polymorphism was analyzed from dried blood spots. Longitudinal analyses revealed that psychological well-being and physical health remained stable over time. Analyses indicated that E2 moderated the course of psychological well-being, while the androgen receptor gene polymorphism moderated the course of physical health. Further, T was a strong predictor of physical health. These results suggest that the hypothalamic-pituitary-gonadal (HPG) axis might be important for the maintenance of psychological well-being in men, while physical health depends more on interindividual differences in the androgen receptor gene and T.

Interactive effects of testosterone and the androgen receptor CAG repeat length polymorphism on cardiovascular-renal events and mortality in men with diabetes

AIM

Current evidence relating testosterone to cardiovascular disease and mortality is inconclusive. Cellular effects of testosterone are mediated by androgen receptor and longer receptor gene CAG repeat length correlates with reduced transcriptional activity. We investigated the independent and interactive association of total testosterone and CAG repeat length with incident cardiovascular disease (CVD), chronic kidney disease (CKD) and mortality in Chinese men with type 2 diabetes.

MATERIALS AND METHODS

From March 2008 and February 2009, 474 men with diabetes underwent structured clinical assessment including genotyping for CAG repeat length. Patients were followed for new-onset CVD, CKD defined by estimated glomerular filtration rate <60 mL/min/1.73m² , and death until 31 May 2015.

RESULTS

In this cohort (mean age: 58.6 years, disease duration: 15.4 years), CAG repeat number ranged from 11 to 32 with median of 23, and 9.3% had low testosterone. Over follow-up of 5.8 years, 49 (10.3%) men had CVD, 139 (29.3%) had CKD, and 43 (9.1%) died. In multivariate Cox regression adjusted for age, duration of diabetes, and cardiometabolic risk factors, both total testosterone and interaction term of total testosterone × CAG repeat were associated with all-cause death with respective hazard ratios 1.63 (P = 0.002) and 0.98 (P = 0.004). Total testosterone and CAG repeat were not related to incident CVD or CKD.

CONCLUSIONS

Among men with type 2 diabetes, high total testosterone was associated with increased mortality in the presence of shorter CAG repeat length but decreased mortality in those with long CAG repeats.

Cross-sectional association between testosterone, sex hormone-binding globulin and metabolic syndrome: The Healthy Twin Study

OBJECTIVES

This study evaluated an association between testosterone, sex hormone-binding globulin (SHBG) and metabolic syndrome (MetS).We also evaluated the genetic and environmental influences on the association.

DESIGN

Cross-sectional.

SETTING

Community-based study.

PARTICIPANTS

A total of 1098 Korean adult men including 139 monozygotic twin pairs.

MAIN OUTCOME MEASURE

MetS was defined using the National Cholesterol Education Program-Third Adult Treatment Panel (NCEP ATP III) and International Diabetes Federation (IDF) criteria. The associations between MetS and sex hormones were evaluated using linear mixed model and generalized estimating equation model.

RESULTS

After considering covariates such as smoking, alcohol consumption and physical exercises as well as SHBG or testosterone, the risk of MetS defined by NCEP ATP III criteria decreased by 31%, 29%, and 48%, respectively, with 1-standard deviation increase in total testosterone (TT), free testosterone (cFT) and SHBG. Similar findings were revealed with IDF criteria. Metabolic component specific analysis showed that sex hormones were inversely associated with several components of MetS: TT with abdominal obesity, low high-density lipoprotein cholesterol (HDL-C) and high blood pressure; cFT with abdominal obesity and high blood pressure; SHBG with all components except high blood pressure. Cotwin control analysis found an inverse correlation between within-pair differences in testosterone and SHBG levels and within-pair differences in waist circumference only.

CONCLUSION

Both testosterone and SHBG were inversely associated with MetS although the inverse associations with the sex hormones were not consistently found across individual metabolic components. Findings from cotwin analysis suggest a significant contribution of unshared unique environmental effect to the association between testosterone and SHBG and abdominal obesity.

Genomic and non-genomic effects of androgens in the cardiovascular system: clinical implications

The principle steroidal androgens are testosterone and its metabolite 5α-dihydrotestosterone (DHT), which is converted from testosterone by the enzyme 5α-reductase. Through the classic pathway with androgens crossing the plasma membrane and binding to the androgen receptor (AR) or via mechanisms independent of the ligand-dependent transactivation function of nuclear receptors, testosterone induces genomic and non-genomic effects respectively. AR is widely distributed in several tissues, including vascular endothelial and smooth muscle cells. Androgens are essential for many developmental and physiological processes, especially in male reproductive tissues. It is now clear that androgens have multiple actions besides sex differentiation and sexual maturation and that many physiological systems are influenced by androgens, including regulation of cardiovascular function [nitric oxide (NO) release, Ca²⁺ mobilization, vascular apoptosis, hypertrophy, calcification, senescence and reactive oxygen species (ROS) generation]. This review focuses on evidence indicating that interplay between genomic and non-genomic actions of testosterone may influence cardiovascular function.