Scaffold Implant Into the Epididymal Adipose Tissue Protects Mice From High Fat Diet Induced Ectopic Lipid Accumulation and Hyperinsulinemia

Transplantation of committed pre-adipocytes from brown adipose tissue improves whole-body glucose homeostasis

Obesity and its co-morbidities including type 2 diabetes are increasing at epidemic rates in the U.S. and worldwide. Brown adipose tissue (BAT) is a potential therapeutic to combat obesity and type 2 diabetes. Increasing BAT mass by transplantation improves metabolic health in rodents, but its clinical translation remains a challenge. Here, we investigated if transplantation of 2-4 million differentiated brown pre-adipocytes from mouse BAT stromal fraction (SVF) or human pluripotent stem cells (hPSCs) could improve metabolic health. Transplantation of differentiated brown pre-adipocytes, termed "committed pre-adipocytes" from BAT SVF from mice or derived from hPSCs improves glucose homeostasis and insulin sensitivity in recipient mice under conditions of diet-induced obesity, and this improvement is mediated through the collaborative actions of the liver transcriptome, tissue AKT signaling, and FGF21. These data demonstrate that transplantation of a small number of brown adipocytes has significant long-term translational and therapeutic potential to improve glucose metabolism.

Hypercaloric Diet Promotes Metabolic Disorders and Impaired Kidney Function

Poor dietary habits such as overconsumption of hypercaloric diets characterized by a high content of fructose and fat are related to metabolic abnormalities development such as obesity, diabetes, and dyslipidemia. Accumulating evidence supports the hypothesis that if energy intake gradually exceeds the body's ability to store fat in adipose tissue, the prolonged metabolic imbalance of circulating lipids from endogenous and exogenous sources leads to ectopic fat distribution in the peripheral organs, especially in the heart, liver, and kidney. The kidney is easily affected by dyslipidemia, which induces lipid accumulation and reflects an imbalance between fatty acid supply and fatty acid utilization. This derives from tissue lipotoxicity, oxidative stress, fibrosis, and inflammation, resulting in structural and functional changes that lead to glomerular and tubule-interstitial damage. Some authors indicate that a lipid-lowering pharmacological approach combined with a substantial lifestyle change should be considered to treat chronic kidney disease (CKD). Also, the new therapeutic target identification and the development of new drugs targeting metabolic pathways involved with kidney lipotoxicity could constitute an additional alternative to combat the complex mechanisms involved in impaired kidney function. In this review article, we first provide the pathophysiological evidence regarding the impact of hypercaloric diets, such as high-fat diets and high-fructose diets, on the development of metabolic disorders associated with impaired renal function and the molecular mechanisms underlying tissue lipid deposition. In addition, we present the current progress regarding translational strategies to prevent and/or treat kidney injury related to the consumption of hypercaloric diets.

Metformin ameliorates skeletal muscle atrophy in Grx1 KO mice by regulating intramuscular lipid accumulation and glucose utilization

Skeletal muscle is the largest tissue in the body, and plays a remarkable role in energy and metabolic homeostasis. Disorder in lipid metabolism and glucose utilization could impair the quality and function of skeletal muscle. Glutaredoxin-1 (Grx1) acts as a vital metabolic regulator of redox homeostasis. Recent studies have shown that Grx1 regulates hepatic lipid metabolism. The skeletal muscle also contains abundant Grx1, but the role of Grx1 in skeletal muscle remains unknown. Therefore, we investigated the effect of Grx1 on skeletal muscle. In this study, we found that Grx1-deficient mice (Grx1^-/-) spontaneously developed muscle atrophy by 3 months of age. And the p-AMPK activity and Sirt1 activity were inhibited in Grx1^-/- mice, which led to intramuscular lipid deposition and glucose utilization disorder in skeletal muscle. However, intraperitoneal injection of metformin for 15 consecutive days ameliorated skeletal muscle atrophy caused by Grx1 deficiency to a certain extent. Taken together, these findings indicate that Grx1 deficiency might induce skeletal muscle atrophy by regulating the intramuscular lipid deposition and glucose utilization, which could be attenuated by metformin. Therefore, the expression or activity of Grx1 may be a pharmacological approach to ameliorate muscle atrophy diseases, such as sarcopenia.