The Effect of High Fat Diet on Marrow Adipocytes from C57BL/6J (B6) Mice

In mice models, the administration of a high fat diet (HFD) is an accelerating factor for metabolic syndrome, impaired glucose tolerance, and early type 2 diabetes mellitus (T2DM) (1)https://knowledgeconnection.mainehealth.org/lambrew-retreat-2021/1049/thumbnail.jp

The natural triterpene maslinic acid induces apoptosis in HT29 colon cancer cells by a JNK-p53-dependent mechanism

[Background] Maslinic acid, a pentacyclic triterpene found in the protective wax-like coating of the leaves and fruit of Olea europaea L., is a promising agent for the prevention of colon cancer. We have shown elsewhere that maslinic acid inhibits cell proliferation to a significant extent and activates mitochondrial apoptosis in colon cancer cells. In our latest work we have investigated further this compound's apoptotic molecular mechanism. [Methods] We used HT29 adenocarcinoma cells. Changes genotoxicity were analyzed by single-cell gel electrophoresis (comet assay). The cell cycle was determined by flow cytometry. Finally, changes in protein expression were examined by western blotting. Student's t-test was used for statistical comparison. [Results] HT29 cells treated with maslinic acid showed significant increases in genotoxicity and cell-cycle arrest during the G0/G1 phase after 72 hours' treatment and an apoptotic sub-G0/G1 peak after 96 hours. Nevertheless, the molecular mechanism for this cytotoxic effect of maslinic acid has never been properly explored. We show here that the anti-tumoral activity of maslinic acid might proceed via p53-mediated apoptosis by acting upon the main signaling components that lead to an increase in p53 activity and the induction of the rest of the factors that participate in the apoptotic pathway. We found that in HT29 cells maslinic acid activated the expression of c-Jun NH2-terminal kinase (JNK), thus inducing p53. Treatment of tumor cells with maslinic acid also resulted in an increase in the expression of Bid and Bax, repression of Bcl-2, release of cytochrome-c and an increase in the expression of caspases -9, -3, and -7. Moreover, maslinic acid produced belated caspase-8 activity, thus amplifying the initial mitochondrial apoptotic signaling. [Conclusion] All these results suggest that maslinic acid induces apoptosis in human HT29 colon-cancer cells through the JNK-Bid-mediated mitochondrial apoptotic pathway via the activation of p53. Thus we propose a plausible sequential molecular mechanism for the expression of the different proteins responsible for the intrinsic mitochondrial apoptotic pathway. Further studies with other cell lines will be needed to confirm the general nature of these findings.This study was supported by grants BIO157 from the Andalucian regional government; SAF2008-00164 and ISCIII-RTICC (RD06/0020/0046) grants from the Spanish national government and & European Regional Development Fund (ERDF) "Una manera de hacer Europa" and by AGAUR-Generalitat de Catalunya grant 2009SGR1308, 2009 CTP 00026 and Icrea Academia award 2010 granted to M. Cascante)

Bone marrow adipose tissue in metabolic health

Recent studies have highlighted the role of bone marrow adipose tissue (BMAT) as a regulator of skeletal homeostasis and energy metabolism. While long considered an inert filler, occupying empty spaces from bone loss and reduced hematopoiesis, BMAT is now considered a secretory and metabolic organ that responds to nutritional challenges and secretes cytokines, which indirectly impact energy and bone metabolism. The recent advances in our understanding of the function of BMAT have been enabled by novel noninvasive imaging techniques, which allow longitudinal assessment of BMAT in vivo following interventions. This review will focus on the latest advances in our understanding of BMAT and its role in metabolic health. Imaging techniques to quantify the content and composition of BMAT will be discussed

The dynamics of human bone marrow adipose tissue in response to feeding and fasting

The administration of a high fat content diet (HFD) is an accelerating factor for metabolic syndrome, impaired glucose tolerance, and early type 2 diabetes. The present study aims to assess the impact of a high fat diet or acute weight gain on human marrow adipose tissue. Adipose tissues secrete numerous active substances termed adipokines, including adiponectin, leptin, resistin, interleukin-6 (IL-6), etc. Adipokines physiologically regulate development, metabolism, eating behavior, fat storage, insulin sensitivity, hemostasis, blood pressure, immunity, and inflammation. Our objective is to determine the effect of HFD on adipokines from marrow adipose tissue, as well as, the effect of HFD on resistin, TNF?, RCAN2 and SEMA3E/PLXND1 gene expression. Marrow serum, peripheral blood serum as well as marrow adipocytes from healthy adult human who underwent either 10 days of fasting or 10 days of HFD, were collected according to published protocols. To analyze the expression of resistin, IL-6, TNF? and adiponectin in human serum from marrow and peripheral blood, we used DuoSet ELISA kit (R&D systems) respectively. To analyze the gene expression of resistin, TNF?, RCAN2 and SEMA3E/PLXND1 on marrow adipocytes, qRT-PCR were performed. All primers were synthesized by Integrated DNA Technologies (Coralville, IA). Results were normalized to GAPDH and all samples were run in duplicate. Our results show that in paired aspirates, resistin increased markedly with a HFD, but not with fasting, and not in the circulation, without significant changes on adiponectin neither IL-6 levels. Resistin is a cytokine produced in WAT (adipocytes in rodents, macrophages in human) and is thought to mediate type 2 diabetes mellitus (T2DM) and cardiovascular disease and to mark macrophage activation and TLR4 signaling. In our previous studies with mouse models, PLXND1 is highly expressed on marrow stromal cells and has been linked to adiposity and type 2 diabetes. Also, inhibition of the SEMA3E(ligand)/PLXND1(receptor) axis markedly reduced adipose tissue inflammation and improved systemic insulin resistance in mouse model. PLXND1 also was one of the most highly expressed genes in a MSCs from a mouse with high marrow adiposity and consistent with our findings noted in human volunteers. RCAN2, one of the three main regulators of calcineurin, is located 43.7 Mb on mouse chromosome 17 and in a QTL study of marrow fat from DO strains, that region gave the highest LOD score. Our data show that expression of SEMA3E/PLXND1, RCAN2 and TNF? were increased on marrow adipocytes from the HFD volunteers. Also we identified up-regulation of the macrophage gene marker, EMR-1 (homologous to F4/80 in mice), suggestive of an inflammatory response in the marrow of normal volunteers on a HFD but not fasting. The bone microenviroment can be modulated by various factors including aging, obesity, and inflammation. Stress signal could be modulated by SEMA3E/PLXND1 axis as a chemoattractant for macrophages, provoking adipose tissue inflammation, and also by RCAN2, through calcineurin activity, which is indispensable for osteoclast differentiation, creating less bone resorption and impaired normal bone homeostasis. Further analysis are needed to understanding the immune response in the context of marrow adiposity in humans and mouse models

Changes in serum cortisol levels after 10 days of overfeeding and fasting

Chronic caloric deprivation and obesity are complicated by hypercortisolemia. The effects of acute overfeeding and fasting on circulating free cortisol levels and conversion of cortisone to free cortisol are unknown. We hypothesized that serum-free cortisol and free cortisol-to-cortisone ratio would increase after both overfeeding and fasting. This is a prospective study of 22 healthy volunteers who completed a 10-day high-calorie protocol followed by a 10-day fast, separated by a 2-wk washout. Morning free and total cortisol and free cortisone levels (LC/MS) were measured at baseline and after 10 days of each intervention. Both high-calorie feeding and fasting increased total and free cortisol and the free cortisol-to-free cortisone ratio ( = 0.001 to = 0.046). There were sex interactions, with significant effects in men ( \u3c 0.001), but not in women ( = 0.898 and 1.000, respectively) in subset analyses examining the effects of fasting on free cortisol and the free-to-total cortisol ratio. Overfeeding and fasting both increase circulating free cortisol levels and appear to alter the balance between cortisol and its inactive metabolite, cortisone. Further study is warranted to determine whether elevated cortisol levels contribute to complications of starvation and obesity, such as bone fragility. Overfeeding and fasting both increase circulating free cortisol levels and appear to alter the balance between cortisol and its inactive metabolite, cortisone. The effect of fasting on free cortisol levels is modified by sex. Further study is needed to determine the mechanisms driving the increases in cortisol

Obesity Determines the Immunophenotypic Profile and Functional Characteristics of Human Mesenchymal Stem Cells From Adipose Tissue.

Adipose tissue is a major source of mesenchymal stem cells (MSCs), which possess a variety of properties that make them ideal candidates for regenerative and immunomodulatory therapies. Here, we compared the immunophenotypic profile of human adipose-derived stem cells (hASCs) from lean and obese individuals, and explored its relationship with the apparent altered plasticity of hASCs. We also hypothesized that persistent hypoxia treatment of cultured hASCs may be necessary but not sufficient to drive significant changes in mature adipocytes. hASCs were obtained from subcutaneous adipose tissue of healthy, adult, female donors undergoing abdominal plastic surgery: lean (n=8; body mass index [BMI]: 23±1 kg/m2) and obese (n=8; BMI: 35±5 kg/m2). Cell surface marker expression, proliferation and migration capacity, and adipogenic differentiation potential of cultured hASCs at two different oxygen conditions were studied. Compared with lean-derived hASCs, obese-derived hASCs demonstrated increased proliferation and migration capacity but decreased lipid droplet accumulation, correlating with a higher expression of human leukocyte antigen (HLA)-II and cluster of differentiation (CD) 106 and lower expression of CD29. Of interest, adipogenic differentiation modified CD106, CD49b, HLA-ABC surface protein expression, which was dependent on the donor's BMI. Additionally, low oxygen tension increased proliferation and migration of lean but not obese hASCs, which correlated with an altered CD36 and CD49b immunophenotypic profile. In summary, the differences observed in proliferation, migration, and differentiation capacity in obese hASCs occurred in parallel with changes in cell surface markers, both under basal conditions and during differentiation. Therefore, obesity is an important determinant of stem cell function independent of oxygen tension. The obesity-related hypoxic environment may have latent effects on human adipose tissue-derived mesenchymal stem cells (hASCs) with potential consequences in mature cells. This study explores the immunophenotypic profile of hASCs obtained from lean and obese individuals and its potential relationship with the altered plasticity of hASCs observed in obesity. In this context, an altered pattern of cell surface marker expression in obese-derived hASCs in both undifferentiated and differentiated stages is demonstrated. Differences in proliferation, migration, and differentiation capacity of hASCs from obese adipose tissue correlated with alterations in cell surface expression. Remarkably, altered plasticity observed in obese-derived hASCs was maintained in the absence of hypoxia, suggesting that these cells might be obesity conditioned