The Interaction between the Gut Microbiome and Bile Acids in Cardiometabolic Diseases

Cardio-metabolic diseases (CMD) are a spectrum of diseases (e.g., type 2 diabetes, atherosclerosis, non-alcohol fatty liver disease (NAFLD), and metabolic syndrome) that are among the leading causes of morbidity and mortality worldwide. It has long been known that bile acids (BA), which are endogenously produced signalling molecules from cholesterol, can affect CMD risk and progression and directly affect the gut microbiome (GM). Moreover, studies focusing on the GM and CMD risk have dramatically increased in the past decade. It has also become clear that the GM can function as a “new” endocrine organ. BA and GM have a complex and interdependent relationship with several CMD pathways. This review aims to provide a comprehensive overview of the interplay between BA metabolism, the GM, and CMD risk and progression.

Origin and Development of the Adipose Tissue, a Key Organ in Physiology and Disease

Adipose tissue is a dynamic organ, well known for its function in energy storage and mobilization according to nutrient availability and body needs, in charge of keeping the energetic balance of the organism. During the last decades, adipose tissue has emerged as the largest endocrine organ in the human body, being able to secrete hormones as well as inflammatory molecules and having an important impact in multiple processes such as adipogenesis, metabolism and chronic inflammation. However, the cellular progenitors, development, homeostasis and metabolism of the different types of adipose tissue are not fully known. During the last decade, Drosophila melanogaster has demonstrated to be an excellent model to tackle some of the open questions in the field of metabolism and development of endocrine/metabolic organs. Discoveries ranged from new hormones regulating obesity to subcellular mechanisms that regulate lipogenesis and lipolysis. Here, we review the available evidences on the development, types and functions of adipose tissue in Drosophila and identify some gaps for future research. This may help to understand the cellular and molecular mechanism underlying the pathophysiology of this fascinating key tissue, contributing to establish this organ as a therapeutic target.

An Exploration of Non-Coding RNAs in Extracellular Vesicles Delivered by Swine Anterior Pituitary

Extracellular vesicles are lipid bilayer-delimited particles carrying proteins, lipids, and small RNAs. Previous studies have demonstrated that they had regulatory functions both physiologically and pathologically. However, information remains inadequate on extracellular vesicles from the anterior pituitary, a key endocrine organ in animals and humans. In this study, we separated and identified extracellular vesicles from the anterior pituitary of the Duroc swine model. Total RNA was extracted and RNA-seq was performed, followed by a comprehensive analysis of miRNAs, lncRNAs, and circRNAs. Resultantly, we obtained 416 miRNAs, 16,232 lncRNAs, and 495 circRNAs. Furthermore, GO and KEGG enrichment analysis showed that the ncRNAs in extracellular vesicles may participate in regulating intracellular signal transduction, cellular component organization or biogenesis, small molecule binding, and transferase activity. The cross-talk between them also suggested that they may play an important role in the signaling process and biological regulation. This is the first report of ncRNA data in the anterior pituitary extracellular vesicles from the duroc swine breed, which is a fundamental resource for exploring detailed functions of extracellular vesicles from the anterior pituitary.

New Insights on the Relationship between Leptin, Ghrelin, and Leptin/Ghrelin Ratio Enforced by Body Mass Index in Obesity and Diabetes

Currently, adipose tissue is considered an endocrine organ, however, there are still many questions regarding the roles of adipokines—leptin and ghrelin being two adipokines. The purpose of the study was to assess the relationship between the adipokines and their ratio with obesity and diabetes. Methods: Sixty patients (mean age 61.88 ± 10.08) were evaluated. Cardiovascular risk factors, leptin, ghrelin, and insulin resistance score values were assessed. The patients were classified according to their body mass index (BMI) as normal weight, overweight, and obese. Results: 20% normal weight, 51.7% overweight, 28.3% obese, and 23.3% diabetic. Obese patients had higher leptin values (in obese 34,360 pg/mL vs. overweight 18,000 pg/mL vs. normal weight 14,350 pg/mL, p = 0.0049) and leptin/ghrelin ratio (1055 ± 641 vs. 771.36 ± 921 vs. 370.7 ± 257, p = 0.0228). Stratifying the analyses according to the presence of obesity and patients’ gender, differences were found for leptin (p = 0.0020 in women, p = 0.0055 in men) and leptin/ghrelin ratio (p = 0.048 in women, p = 0.004 in men). Mean leptin/BMI and leptin/ghrelin/BMI ratios were significantly higher, and the ghrelin/BMI ratio was significantly lower in obese and diabetic patients. In conclusion, obesity and diabetes are associated with changes not only in the total amount but also in the level of adipokines/kg/m2. Changes appear even in overweight subjects, offering a basis for early intervention in diabetic and obese patients.

Myokines in Acromegaly: An Altered Irisin Profile

IntroductionThe muscle is an endocrine organ controlling metabolic homeostasis. Irisin and myostatin are key myokines mediating this process. Acromegaly is a chronic disease with a wide spectrum of complications, including metabolic disturbances.PurposeTo examine the influence of acromegaly on irisin and myostatin secretion and their contribution to metabolic profile and body composition.Materials and MethodsIn 43 patients with acromegaly and 60 controls, serum levels of irisin, myostatin, growth hormone (GH), insulin-like growth factor 1 (IGF-1), parameters of glucose, and lipid metabolism were determined. Body composition was assessed with dual-energy x-ray absorptiometry.ResultsThe irisin concentration was significantly lower in patients with acromegaly compared to controls (3.91 vs. 5.09 μg/ml, p = 0.006). There were no correlations between irisin and GH/IGF-1 levels. In the study group, irisin was negatively correlated with fasting insulin (r = −0.367; p = 0.042), HOMA-IR (r = −0.510; p = 0.011), and atherogenic factors: Castelli I (r = −0.416; p = 0.005), Castelli II (r = −0.400; p = 0.001), and atherogenic coefficient (AC) (r = −0.417; p = 0.05). Irisin and myostatin concentrations were also lower in acromegalics with insulin resistance than without (2.80 vs. 4.18 μg/ml, p = 0.047; 81.46 vs. 429.58 ng/L, p = 0.018, respectively). There were no differences between study group and controls in myostatin concentration. Myostatin levels negatively correlated with GH (r = −0.306; p = 0.049), HOMA-IR (r = −0.046; p = 0.411), and insulin levels (r = −0.429; p = 0.016).ConclusionsDecreased irisin concentrations in acromegaly may suggest impaired hormonal muscle function contributing to metabolic complications in this disorder. However, learning more about the association between myostatin and GH in acromegaly requires further studies. Nevertheless, it appears that myostatin is not critical for muscle mass regulation in acromegaly.

Metabolic endotoxemia: possible causes and consequences

This review article presents data from the literature, which provide an idea of the relationship between metabolic disorders occurring against the background of obesity and endotoxinemia, as well as the effect of these conditions on the maintenance of low-grade inflammation in the body. A description of the hormonal and immune restructuring of white adipose tissue, the main routes of entry and metabolism of endotoxin is given. Particular attention is paid to the mechanisms of the mutual influence of obesity and endotoxinemia. Described by Yakovlev M.Yu. in 1988 «endotoxin aggression» and Cani P.D. et al. in 2007, «metabolic endotoxinemia», in our opinion, is one of the most important triggers for the development and progression of a whole spectrum of acute and chronic diseases. Based on the data of recent years, adipose tissue is an active endocrine organ capable of influencing both metabolic processes and the state of innate and acquired immune defense mechanisms. It has now been proven that high-calorie diets lead not only to an increase in overweight, but also to an increase in the level of endotoxin circulating in the blood. An in-depth study of the ability of obesity and endotoxinemia to potentiate the mutual pro-inflammatory effect can help both in understanding the pathogenesis of the main cardiovascular, autoimmune, allergic and infectious (including viral) diseases, and in the development of methods for non-pharmacological and drug correction of these conditions.

Discovery of Thymosin Beta-4 as a Human Exerkine and Growth Factor

Skeletal muscle is an endocrine organ secreting exercise-induced factors (exerkines), which play a pivotal role in inter-organ crosstalk. Using mass spectrometry (MS)-based proteomics, we characterized the secretome and identified thymosin beta-4 (TMSB4X) as the most upregulated secreted protein in the media of contracting C2C12 myotubes. TMSB4X was also acutely increased in plasma of exercising humans irrespective of the insulin resistance condition or exercise mode. Treatment of mice with TMSB4X did not ameliorate the metabolic disruptions associated with diet induced-obesity, nor did it enhance muscle regeneration in vivo. However, TMSB4X increased osteoblast proliferation and neurite outgrowth, consistent with its WADA-classification as a prohibited growth factor. Therefore, we report TMSB4X as a human exerkine with a potential role in cellular crosstalk.

Adrenal cortex development and maintenance; knowledge acquired from mouse models

The adrenal cortex is an endocrine organ organized into concentric zones that are specialized to produce specific steroid hormones essential for life. The development and maintenance of the adrenal cortex are complex, as a fetal adrenal is first formed from a common primordium with the gonads, followed by its separation in a distinct primordium, the invasion of the adrenal primordium by neural crest-derived cells to form the medulla, and finally its encapsulation. The fetal cortex is then replaced by a definitive cortex, which will establish zonation and be maintained throughout life by regeneration relying on the proliferation, centripetal migration and differentiation of several stem/progenitor cell populations whose activities are sex-specific. Here, we will highlight the advances made, using transgenic mouse models, to delineate the molecular mechanisms regulating these processes.

Adipokines in Insulin Resistance: Current Updates

Obesity is a chronic metabolic disease that affects both the pediatric and adult populations. Adipose tissue acts as an endocrine organ which secretes various adipokines involved in fat mass regulation and energy balance via modulating the metabolic signalling pathways. Altered secretion of adipokines promotes multiple complications, including insulin resistance. The primary mechanism of action that underlines the involvement of adipokines in the development of insulin resistance includes phosphorylation/de-phosphorylation of insulin receptor substrate-1 (IRS-1) facilitate by other signalling molecules like a suppressor of cytokine signalling 1 (SOCS-1). Adipokines mediated insulin resistance further contribute to the development of atherosclerosis, dyslipidemia, fatty liver disease, cancer etc. Thus, this review provides recent updates on the role of resistin, lipocalin-2, RBP-4, chemerin, TNF-alpha and IL-6 adipokines in the progression of insulin resistance.