Grade of inflammation in boys with type 1 diabetes depends on the IVS1 -397T>C estrogen receptor α polymorphism

Sex-dependent effects on the gut microbiota and host metabolome in type 1 diabetic mice

Sexual dimorphism exists in the onset and development of type 1 diabetes (T1D), but its potential pathological mechanism is poorly understood. In the present study, we examined sex-specific changes in the gut microbiome and host metabolome of T1D mice via 16S rRNA gene sequencing and nuclear magnetic resonance (NMR)-based metabolomics approach, and aimed to investigate potential mechanism of the gut microbiota-host metabolic interaction in the sexual dimorphism of T1D. Our results demonstrate that female mice had a greater shift in the gut microbiota than male mice during the development of T1D; however, host metabolome was more susceptible to T1D in male mice. The correlation network analysis indicates that T1D-induced host metabolic changes may be regulated by the gut microbiota in a sex-specific manner, mainly involving short-chain fatty acids (SCFAs) metabolism, energy metabolism, amino acid metabolism, and choline metabolism. Therefore, our study suggests that sex-dependent "gut microbiota-host metabolism axis" may be implicated in the sexual dimorphism of T1D, and the link between microbes and metabolites might contribute to the prevention and treatment of T1D.

Effect of Estrogen Receptor- Alpha Gene Polymorphism (IVS1-397 T>C) on Microvascular Complications of Type 1 Diabetes Mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is an autoimmune disease whose etiology involves genetic predisposition as well as environmental factors. Polymorphisms of some genes are among the most important genetic factors that influence autoimmunity. Gender is another important factor affecting autoimmunity. Females are more susceptible to autoimmune diseases which may be due to the effect of sex hormones on the immune system activity. The metabolic effects of estrogen are mediated through its receptor - alpha. The exact mechanism is not well understood. A number of polymorphisms have been reported in the Estrogen Receptor- alpha (ER-alpha) IVS1 397 T>C gene which may be involved in the pathogenesis of diabetes.

OBJECTIVES

To assess the influence of Estrogen Receptor- alpha gene [IVS1-397 T>C] polymorphism on vascular complications of type1 diabetes mellitus in pubertal females and on the glycemic control.

METHODS

This cross-sectional case-control study included 40 pubertal regularly menstruating girls less than 18 years with type 1 diabetes mellitus recruited from the Pediatric Diabetes Clinic, Children's Hospital, Ain-Shams University and 20 healthy age-and sex-matched controls. Estrogen receptor alpha genotypes were analyzed by Restriction Fragment Length PCR and correlated with both clinical and laboratory parameters in the studied cases. ER-alpha was chosen as it might play a role in diabetes pathogenesis.

RESULTS

The study revealed the TC genotype was the most prevalent genotype of the estrogen receptor. The TT genotype patients had a younger age of onset of T1DM. The prevalence of obesity was higher among TC and TT than in CC bearing patients. In addition, CC genotype patients had the least prevalence of microalbuminuria and had better glycemic control than other genotypes.

CONCLUSION

Our findings suggest that Estrogen receptor- alpha gene may be affecting the age of onset of Type1 diabetes mellitus in pubertal girls as well as the glycemic control of these patients, where CC bearing girls had better glycemic control than other genotypes and less incidence of microalbuminuria.

Estrogen receptor α gene polymorphism and vascular complications in girls with type 1 diabetes mellitus

The effect of estrogens is mediated by activation of estrogen receptors (ERs). Because ER-α gene polymorphisms may exert different effects in childhood, we analyzed the associations between the IVS1 −397T>C (PvuII) polymorphism and systemic inflammatory state, proangiogenic factors, frequency of monocyte subsets, lipid profile, blood pressure, and vascular complications in girls with type 1 diabetes mellitus (DM1). We examined 180 young girls with DM1 and 120 healthy age-matched controls. The analysis concerned PvuII polymorphism of the ER-α gene as well as the levels of serum inflammatory markers (CRP, IL-6, TNF-α), proangiogenic factors (VEGF, angiogenin), 17β-estradiol, values of monocyte subsets (CD14⁺⁺CD16⁻ and CD14⁺CD16⁺), lipid profile, and blood pressure. In our study, girls with CC genotype had lower level of inflammatory and angiogenic factors and lower frequencies of CD14⁺CD16⁺ monocytes in comparison to CT or TT carriers. Simultaneously, the CC carriers had a greater population of CD14⁺⁺CD16⁻ monocytes, increased blood pressure, and serum levels of: estrogen, total cholesterol, triglycerides, and low-density lipoprotein cholesterol than girls bearing CT or TT genotype. Our study suggests a pleiotropic effect of PvuII polymorphic CC variant on diabetic vasculopathies. Although the CC genotype carriers demonstrate less inflammatory and angiogenic activity, they seem to display less favorable cardiometabolic features. Based on our study, we cannot distinguish PvuII ER-α genotype that could be useful in identification of DM1 girls that are more prone to develop of late vascular complications, before the occurrence of first clinical symptoms.

Genetic Mechanisms Leading to Sex Differences Across Common Diseases and Anthropometric Traits

Common diseases often show sex differences in prevalence, onset, symptomology, treatment, or prognosis. Although studies have been performed to evaluate sex differences at specific SNP associations, this work aims to comprehensively survey a number of complex heritable diseases and anthropometric traits. Potential genetically encoded sex differences we investigated include differential genetic liability thresholds or distributions, gene-sex interaction at autosomal loci, major contribution of the X-chromosome, or gene-environment interactions reflected in genes responsive to androgens or estrogens. Finally, we tested the overlap between sex-differential association with anthropometric traits and disease risk. We utilized complementary approaches of assessing GWAS association enrichment and SNP-based heritability estimation to explore explicit sex differences, as well as enrichment in sex-implicated functional categories. We do not find consistent increased genetic load in the lower-prevalence sex, or a disproportionate role for the X-chromosome in disease risk, despite sex-heterogeneity on the X for several traits. We find that all anthropometric traits show less than complete correlation between the genetic contribution to males and females, and find a convincing example of autosome-wide genome-sex interaction in multiple sclerosis (P = 1 × 10^-9). We also find some evidence for hormone-responsive gene enrichment, and striking evidence of the contribution of sex-differential anthropometric associations to common disease risk, implying that general mechanisms of sexual dimorphism determining secondary sex characteristics have shared effects on disease risk.