Contributions of microRNAs to Peripheral Insulin Sensitivity

Adipose Tissue Dysfunction and Energy Balance Paradigms in People Living With HIV

Over the past 4 decades, the clinical care of people living with HIV (PLWH) evolved from treatment of acute opportunistic infections to the management of chronic, noncommunicable comorbidities. Concurrently, our understanding of adipose tissue function matured to acknowledge its important endocrine contributions to energy balance. PLWH experience changes in the mass and composition of adipose tissue depots before and after initiating antiretroviral therapy, including regional loss (lipoatrophy), gain (lipohypertrophy), or mixed lipodystrophy. These conditions may coexist with generalized obesity in PLWH and reflect disturbances of energy balance regulation caused by HIV persistence and antiretroviral therapy drugs. Adipocyte hypertrophy characterizes visceral and subcutaneous adipose tissue depot expansion, as well as ectopic lipid deposition that occurs diffusely in the liver, skeletal muscle, and heart. PLWH with excess visceral adipose tissue exhibit adipokine dysregulation coupled with increased insulin resistance, heightening their risk for cardiovascular disease above that of the HIV-negative population. However, conventional therapies are ineffective for the management of cardiometabolic risk in this patient population. Although the knowledge of complex cardiometabolic comorbidities in PLWH continues to expand, significant knowledge gaps remain. Ongoing studies aimed at understanding interorgan communication and energy balance provide insights into metabolic observations in PLWH and reveal potential therapeutic targets. Our review focuses on current knowledge and recent advances in HIV-associated adipose tissue dysfunction, highlights emerging adipokine paradigms, and describes critical mechanistic and clinical insights.

The regulatory role and mechanism of exosomes in hepatic fibrosis

Globally, the prevalence and fatality rates of liver disorders are on the rise. Among chronic liver conditions, hepatic fibrosis stands out as a central pathological process. Despite this, approved treatments for hepatic fibrosis are currently lacking. Exosomes, small extracellular vesicles secreted by various cell types, play a significant role in intercellular communication and have emerged as essential mediators in liver fibrosis. In this regard, this review compiles the mechanisms through which exosomes regulate hepatic fibrosis, encompassing diverse targets and signaling pathways. Furthermore, it delves into the regulatory impact of exosomes modulated by natural plant-derived, endogenous, and synthetic compounds as potential therapeutic strategies for addressing hepatic fibrosis.

Changes in subcutaneous adipose tissue microRNA expression in response to exercise training in obese African women

The mechanisms that underlie exercise-induced adaptations in adipose tissue have not been elucidated, yet, accumulating studies suggest an important role for microRNAs (miRNAs). This study aimed to investigate miRNA expression in gluteal subcutaneous adipose tissue (GSAT) in response to a 12-week exercise intervention in South African women with obesity, and to assess depot-specific differences in miRNA expression in GSAT and abdominal subcutaneous adipose tissue (ASAT). In addition, the association between exercise-induced changes in miRNA expression and metabolic risk was evaluated. Women underwent 12-weeks of supervised aerobic and resistance training (n = 19) or maintained their regular physical activity during this period (n = 12). Exercise-induced miRNAs were identified in GSAT using Illumina sequencing, followed by analysis of differentially expressed miRNAs in GSAT and ASAT using quantitative real-time PCR. Associations between the changes (pre- and post-exercise training) in miRNA expression and metabolic parameters were evaluated using Spearman's correlation tests. Exercise training significantly increased the expression of miR-155-5p (1.5-fold, p = 0.045), miR-329-3p (2.1-fold, p < 0.001) and miR-377-3p (1.7-fold, p = 0.013) in GSAT, but not in ASAT. In addition, a novel miRNA, MYN0617, was identified in GSAT, with low expression in ASAT. The exercise-induced differences in miRNA expression were correlated with each other and associated with changes in high-density lipoprotein concentrations. Exercise training induced adipose-depot specific miRNA expression within subcutaneous adipose tissue depots from South African women with obesity. The significance of the association between exercise-induced miRNAs and metabolic risk warrants further investigation.

Visceral Adipose Tissue E2F1-miRNA206/210 Pathway Associates with Type 2 Diabetes in Humans with Extreme Obesity

Objective: Up-regulated expression of transcription-factor E2F1 in human visceral adipose tissue (VAT) characterizes a dysmetabolic obesity sub-phenotype. An E2F1-miRNA network has been described in multiple cancers. Here we investigated whether elevated VAT-E2F1 in obesity is associated with VAT-miRNA alterations similar to, or distinct from, those described in cancer. Furthermore, we assessed if E2F1-associated miRNA changes may contribute to the link between high- VAT-E2F1 and a dysmetabolic obesity phenotype. Methods: We assembled a cohort of patients with obesity and high-VAT-E2F1, matched by age, sex, ±BMI to patients with low-VAT-E2F1, with and without obesity (8 patients/groupX3 groups). We performed Nanostring©-based miRNA profiling of VAT samples from all 24 patients. Candidate E2F1-related miRNAs were validated by qPCR in an independent cohort of patients with extreme obesity, with or without type-2-diabetes (T2DM) (n = 20). Bioinformatic tools and manipulation of E2F1 expression in cells were used to establish the plausibility of the functional VAT-E2F1-miRNA network in obesity. Results: Among n = 798 identified miRNAs, 17 were differentially expressed in relation to E2F1 and not to obesity itself. No evidence for the cancer-related E2F1-miRNA network was identified in human VAT in obesity. In HEK293-cells, overexpression/downregulation of E2F1 correspondingly altered the expression of miRNA-206 and miRNA-210-5p, two miRNAs with reported metabolic functions consistent with those of E2F1. In VAT from both cohorts, the expression of both miRNA-206 and 210-5p intercorrelated, and correlated with the expression of E2F1. In cohort 1 we did not detect significant associations with biochemical parameters. In cohort 2 of patients with extreme obesity, all those with high VAT-E2F1 showed a diabetes-complicated obesity phenotype and higher expression of miRNA-206 and miRNA-210-5p, which also correlated with fasting glucose levels (both miRNAs) and fasting insulin (miRNA-210-5p). Conclusions: Whilst the previously described cancer-related E2F1-miRNA network does not appear to operate in VAT in obesity, miRNAs-206 and 210-5p may link high-E2F1 expression in VAT with diabetes-complicated extreme obesity phenotype.