1. Investigación

The incidence of obesity and its related disorders has increased dramatically in recent years and has become a pandemic. Adipose tissue is a crucial regulator of these diseases due to its endocrine capacity. Thus, understanding adipose tissue metabolism is essential to finding new effective therapeutic approaches. The “omic” revolution has identified new concepts about the complexity of the signaling pathways involved in the pathophysiology of adipose tissue-associated disorders. Specifically, advances in transcriptomics have allowed its application in clinical practice and primary or secondary prevention. Long non-coding RNAs (lncRNAs) have emerged as critical regulators of adipose tissue since they can modulate gene expression at the epigenetic, transcriptional, and post-transcriptional levels. They interact with DNA, RNA, protein complexes, other noncoding RNAs, and microRNAs to regulate a wide range of physiological and pathological processes. Here, we review the emerging field of lncRNAs, including how they regulate adipose tissue biology, and discuss circulating lncRNAs, which may represent a turning point in the diagnosis and treatment of adipose tissue-associated disorders. We also highlight potential biomarkers of obesity and diabetes that could be considered as therapeutic targets.

Brown adipose tissue (BAT) dissipates energy to produce heat. Thus, it has the potential to regulate body temperature by thermogenesis. For the last decade, BAT has been in the spotlight due to its rediscovery in adult humans. This is evidenced by over a hundred clinical trials that are currently registered to target BAT as a therapeutic tool in the treatment of metabolic diseases, such as obesity or diabetes. The goal of most of these trials is to activate the BAT thermogenic program via several approaches such as adrenergic stimulation, natriuretic peptides, retinoids, capsinoids, thyroid hormones, or glucocorticoids. However, the impact of BAT activation on total body energy consumption and the potential effect on weight loss is still limited. Other studies have focused on increasing the mass of thermogenic BAT. This can be relevant in obesity, where the activity and abundance of BAT have been shown to be drastically reduced. The aim of this review is to describe pathological processes associated with obesity that may influence the correct differentiation of BAT, such as catecholamine resistance, inflammation, oxidative stress, and endoplasmic reticulum stress. This will shed light on the thermogenic potential of BAT as a therapeutic approach to target obesity-induced metabolic diseases.

The rediscovery of brown adipose tissue (BAT) in humans and its capacity to oxidize fat and dissipate energy as heat has put the spotlight on its potential as a therapeutic target in the treatment of several metabolic conditions including obesity and diabetes. To date the measurement of bioenergetics parameters has required the use of cultured cells or extracted mitochondria with the corresponding loss of information in the tissue context. Herein, we present a method to quantify mitochondrial bioenergetics directly in BAT. Based on XF Seahorse Technology, we assessed the appropriate weight of the explants, the exact concentration of each inhibitor in the reaction, and the specific incubation time to optimize bioenergetics measurements. Our results show that BAT basal oxygen consumption is mostly due to proton leak. In addition, BAT presents higher basal oxygen consumption than white adipose tissue and a positive response to b-adrenergic stimulation. Considering the whole tissue and not just subcellular populations is a direct approach that provides a realistic view of physiological respiration. In addition, it can be adapted to analyze the effect of potential activators of thermogenesis, or to assess the use of fatty acids or glucose as a source of energy.

Objective: To test whether enhancing the capability of adipose tissue to store lipids using antioxidant supplementation may prevent the lipotoxic effects and improve the metabolic profile of long-term obesity. Methods: C57BL/6J mice were randomized into three experimental groups for 28 weeks: control group (n510) fed chow diet (10% kcal from fat), obese group (O, n512) fed high-fat (HF) diet (45% kcal from fat), and obese group fed HF diet and supplemented twice a week with 150 mg of a-tocopherol (vitamin E) by oral gavage (OE, n512). Results: HF diet resulted in an obese phenotype with a marked insulin resistance, hypertriglyceridemia, and hepatic steatosis in O mice. Histological analysis of obese visceral adipose tissue (VAT) revealed smaller adipocytes surrounded by a fibrotic extracellular matrix and an increased macrophage infiltration, with the consequent release of proinflammatory cytokines. Vitamin E supplementation decreased oxidative stress and reduced collagen deposition in the VAT of OE mice, allowing a further expansion of the adipocytes and increasing the storage capability. As a result, circulating cytokines were reduced and hepatic steasosis, hypertriglyceridemia, and insulin sensitivity were improved. Conclusions: Our results suggest that oxidative stress is implicated in extracellular matrix remodeling and may play an important role in metabolic regulation.