Ethnic differences in regional adipose tissue oestrogen receptor gene expression

The Relationship between Time, Race, and Estrogen Receptor Alpha in Estradiol-Induced Dermal Fibrosis

In the skin, estradiol (E2) promotes profibrotic and proinflammatory cytokines, contributing to extracellular matrix (ECM) deposition. However, the magnitude of the response differs. Using the human skin organ culture model, we evaluated donor characteristics and correlations that contribute to E2-induced interleukin-6 (IL-6), transforming growth factor beta 1 and 2 (TGFB1 and TGFB2), collagen IA2 (Col IA2), collagen IIIA1 (Col IIIA1), and fibronectin (FN) expressions. In vehicle- and E2-treated dermal skin tissue transcripts, we confirm differences in the magnitude; however, there were positive correlations between profibrotic mediators and ECM components 48 h after E2 treatment. Also, positive correlations exist between baseline and E2-induced TGFB1, IL-6, Col IIIA1, and FN transcripts. Since estrogen receptor alpha (ERA) can propagate E2's signal, we measured and detected differences in its baseline and fold change transcript levels, with a significant decline in baseline levels 48 h after incubation and an increase 48 h after E2 treatment. There was a trend to higher transcript levels in African American donors 24 h earlier. Finally, E2-induced ERA transcript levels negatively correlated with its own baseline levels and positively correlated with FN, TGFB1, and Col IA2 transcript levels. Therefore, our data suggest ERA, E2 exposure time, and race/ethnicity contribute to E2-induced dermal fibrosis.

Genetics of Body Fat Distribution: Comparative Analyses in Populations with European, Asian and African Ancestries

Preferential fat accumulation in visceral vs. subcutaneous depots makes obese individuals more prone to metabolic complications. Body fat distribution (FD) is regulated by genetics. FD patterns vary across ethnic groups independent of obesity. Asians have more and Africans have less visceral fat compared with Europeans. Consequently, Asians tend to be more susceptible to type 2 diabetes even with lower BMIs when compared with Europeans. To date, genome-wide association studies (GWAS) have identified more than 460 loci related to FD traits. However, the majority of these data were generated in European populations. In this review, we aimed to summarize recent advances in FD genetics with a focus on comparisons between European and non-European populations (Asians and Africans). We therefore not only compared FD-related susceptibility loci identified in three ethnicities but also discussed whether known genetic variants might explain the FD pattern heterogeneity across different ancestries. Moreover, we describe several novel candidate genes potentially regulating FD, including NID2, HECTD4 and GNAS, identified in studies with Asian populations. It is of note that in agreement with current knowledge, most of the proposed FD candidate genes found in Asians belong to the group of developmental genes.

Effect of Breast Cancer and Adjuvant Therapy on Adipose-Derived Stromal Cells: Implications for the Role of ADSCs in Regenerative Strategies for Breast Reconstruction

Tissue engineering using Adipose Derived Stromal Cells (ADSCs) has emerged as a novel regenerative medicine approach to replace and reconstruct soft tissue damaged or lost as a result of disease process or therapeutic surgical resection. ADSCs are an attractive cell source for soft tissue regeneration due to the fact that they are easily accessible, multipotent, non-immunogenic and pro-angiogenic. ADSC based regenerative strategies have been successfully translated to the clinical setting for the treatment of Crohn's fistulae, musculoskeletal pathologies, wound healing, and cosmetic breast augmentation (fat grafting). ADSCs are particularly attractive as a source for adipose tissue engineering as they exhibit preferential differentiation to adipocytes and support maintenance of mature adipose graft volume. The potential for reconstruction with an autologous tissue sources and a natural appearance and texture is particularly appealing in the setting of breast cancer; up to 40% of patients require mastectomy for locoregional control and current approaches to post-mastectomy breast reconstruction (PMBR) are limited by the potential for complications at the donor and reconstruction sites. Despite their potential, the use of ADSCs in breast cancer patients is controversial due to concerns regarding oncological safety. These concerns relate to the regeneration of tissue at a site where a malignancy has been treated and the impact this may have on stimulating local disease recurrence or dissemination. Pre-clinical data suggest that ADSCs exhibit pro-oncogenic characteristics and are involved in stimulating progression, and growth of tumour cells. However, there have been conflicting reports on the oncologic outcome, in terms of locoregional recurrence, for breast cancer patients in whom ADSC enhanced fat grafting was utilised as an alternative to reconstruction for small volume defects. A further consideration which may impact the successful translation of ADSC based regenerative strategies for post cancer reconstruction is the potential effects of cancer therapy. This review aims to address the effect of malignant cells, adjuvant therapies and patient-specific factors that may influence the success of regenerative strategies using ADSCs for post cancer tissue regeneration.

Pathogenesis of type 2 diabetes risk in black Africans: a South African perspective

The prevalence of type 2 diabetes (T2D) is higher in black Africans than their European counterparts. This review summarizes the research exploring the pathogenesis of T2D in populations of African ancestry compared to white Europeans and shows that the pathogenesis differs by ethnicity. Black Africans present with a phenotype of low insulin sensitivity and hyperinsulinaemia as a result of increased insulin secretion and reduced hepatic insulin clearance. Whether hyperinsulinaemia precedes insulin resistance or is merely a compensatory mechanism is yet to be determined. Black Africans have lower visceral adipose tissue and ectopic fat deposition and greater peripheral (gluteo-femoral) fat deposition than their European counterparts. This suggests that black Africans are more sensitive to the effects of ectopic fat deposition, or alternatively, that ectopic fat is not an important mediator of T2D in black Africans. Importantly, ethnic disparities in T2D risk factors may be confounded by differences in sociocultural and lifestyle factors. Future longitudinal and dietary intervention studies, in combination with genetic analyses, are needed for a better understanding of the pathophysiology of T2D in black Africans. This will be key for effective prevention and management strategies.

Sex differences on adipose tissue remodeling: from molecular mechanisms to therapeutic interventions

Sexual dimorphism greatly influences adipose tissue remodeling, which is characterized by changes in the activity, number, and/or size of adipocytes in response to distinct stimuli, including lifestyle and anti-obesity drugs. This sex dependence seems to be due to the anatomical and endocrine disparities between men and women. At the molecular level, sex hormones are believed to mediate such differences and involve estrogen and androgen receptor-induced gene expression. The signaling pathways that regulate adipose tissue metabolism and function include peroxisome proliferator-activated receptor gamma, uncoupling protein 1 (UCP1), 5' adenosine monophosphate-activated protein kinase (AMPK), and mitochondrial oxidative phosphorylation (OXPHOS), among other molecular players. Sex hormone-related pathways also interplay with adrenergic signaling, probably the most well-characterized molecular mechanism implicated in the remodeling of white adipose tissue. This review overviews and integrates the signaling pathways behind sexual dimorphism in adipose tissue remodeling, hoping to increase the knowledge on the pathogenesis of diseases, such as obesity and related comorbidities, and consequently, to drive future studies to investigate the regulation of this tissue homeostasis, either in men or women.