Calpain Inhibition Attenuates Adipose Tissue Inflammation and Fibrosis in Diet-induced Obese Mice.
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ABSTRACT:
SUBMITTER: Muniappan L
PROVIDER: S-EPMC5663911 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Exercise has been recommended as an important strategy to improve glucose metabolism in obesity. Adipose tissue fibrosis is associated with inflammation and is implicated in glucose metabolism disturbance and insulin resistance in obesity. However, the effect of exercise on the progression of adipose tissue fibrosis is still unknown. The aim of the present study was to investigate whether exercise retarded the progression of adipose tissue fibrosis and ameliorated glucose homeostasis in diet-induced obese mice. To do so, obesity and adipose tissue fibrosis in mice were induced by high-fat diet feeding for 12 weeks and the mice subsequently received high-fat diet and exercise intervention for another 12 weeks. Exercise alleviated high-fat diet-induced glucose intolerance and insulin resistance. Continued high-fat diet feeding exacerbated collagen deposition and further increased fibrosis-related gene expression in adipose tissue. Exercise attenuated or reversed these changes. Additionally, PPARγ, which has been shown to inhibit adipose tissue fibrosis, was observed to be increased following exercise. Moreover, exercise decreased the expression of HIF-1α in adipose fibrosis, and adipose tissue inflammation was inhibited. In conclusion, our data indicate that exercise attenuates and even reverses the progression of adipose tissue fibrosis, providing a plausible mechanism for its beneficial effects on glucose metabolism in obesity.
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Project description:Exercise promotes weight loss and improves insulin sensitivity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Obesity correlates with increased production of inflammatory cytokines, which in turn, contributes to systemic insulin resistance. To test the hypothesis that exercise mitigates this inflammatory response, thereby improving insulin sensitivity, we developed a model of voluntary exercise in mice made obese by feeding of a high fat/high sucrose diet (HFD). Over four wk, mice fed chow gained 2.3 +/- 0.3 g, while HFD mice gained 6.8 +/- 0.5 g. After 4 wk, mice were subdivided into four groups: chow-no exercise, chow-exercise, HFD-no exercise, HFD-exercise and monitored for an additional 6 wk. Chow-no exercise and HFD-no exercise mice gained an additional 1.2 +/- 0.3 g and 3.3 +/- 0.5 g respectively. Exercising mice had higher food consumption, but did not gain additional weight. As expected, GTT and ITT showed impaired glucose tolerance and insulin resistance in HFD-no exercise mice. However, glucose tolerance improved significantly and insulin sensitivity was completely normalized in HFD-exercise animals. Furthermore, expression of TNF-alpha, MCP-1, PAI-1 and IKKbeta was increased in adipose tissue from HFD mice compared with chow mice, whereas exercise reversed the increased expression of these inflammatory cytokines. In contrast, expression of these cytokines in liver was unchanged among the four groups. These results suggest that exercise partially reduces adiposity, reverses insulin resistance and decreases adipose tissue inflammation in diet-induced obese mice, despite continued consumption of HFD.
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Project description:BACKGROUND:Obesity and adipose tissue expansion is characterized by a chronic state of systemic inflammation that contributes to disease. The neuropeptide, oxytocin, working through its receptor has been shown to attenuate inflammation in sepsis, wound healing, and cardiovascular disease. The current study examined the effects of chronic oxytocin infusions on adipose tissue inflammation in a murine model of obesity, the leptin receptor-deficient (db/db) mouse. METHODS:The effect of obesity on oxytocin receptor protein and mRNA expression in adipose tissue was evaluated by Western blotting and real-time polymerase chain reaction. Mice were implanted with osmotic minipumps filled with oxytocin or vehicle for 8?weeks. At study endpoint adipose tissue inflammation was assessed by measurement of cytokine and adipokine mRNA tissue levels, adipocyte size and macrophage infiltration via histopathology, and plasma levels of adiponectin and serum amyloid A as markers of systemic inflammation. RESULTS:The expression of adipose tissue oxytocin receptor was increased in obese db/db mice compared to lean controls. In adipose tissue oxytocin infusion reduced adipocyte size, macrophage infiltration, IL-6 and TNF? mRNA expression, and increased the expression of the anti-inflammatory adipokine, adiponectin. In plasma, oxytocin infusion reduced the level of serum amyloid A, a marker of systemic inflammation, and increased circulating adiponectin. CONCLUSIONS:In an animal model of obesity and diabetes chronic oxytocin treatment led to a reduction in visceral adipose tissue inflammation and plasma markers of systemic inflammation, which may play a role in disease progression.
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Project description:The innate immune system is associated with the development of local inflammation. Neutrophils play an essential role in the development of the adipose tissue (AT) inflammation associated with obesity by producing elastase, which can promote the activation and infiltration of macrophages. Exercise training attenuates AT inflammation via suppression of macrophage infiltration. However, the mechanisms driving this phenomenon remains to be elucidated. Here, we evaluated the effects of exercise training on the infiltration of neutrophils and elastase expression in an obese mouse model. Four-week-old male C57BL/6J mice were randomly assigned to one of three groups that either received a normal diet (ND) plus sedentary activity (n = 15), a high-fat diet (HFD) plus sedentary activity (n = 15), or a HFD plus exercise training (n = 15). Mice were fed the ND or HFD from the age of 4 weeks until 20 weeks. Mice in the exercise group ran on a treadmill for 60 min/day, 5 days/week over the same experimental period. Mice fed with the HFD had increased content of macrophages in the AT and increased inflammatory cytokine mRNA levels, which were reduced by exercise training. Similarly, AT from the HFD sedentary mice contained more neutrophils than AT from the ND mice, and the amount of neutrophils in this tissue in HFD-fed mice was lowered by exercise training. The mRNA levels of neutrophil elastase in AT were lower in the HFD exercise-trained mice than those in the HFD sedentary mice. These results suggest that exercise training plays a critical role in reducing macrophage infiltration and AT inflammation by regulating the infiltration of neutrophils.
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Project description:Background:Juxtaposed with another zinc finger gene 1 (JAZF1) affects gluconeogenesis, insulin sensitivity, lipid metabolism, and inflammation, but its exact role in chronic inflammation remains unclear. This study aimed to examine JAZF1 overexpression in vivo on adipose tissue macrophages (ATMs). Methods:Mouse models of high-fat diet- (HFD-) induced insulin resistance were induced using C57BL/6J and JAZF1-overexpressing (JAZF1-OX) mice. The mice were randomized (8-10/group) to C57BL/6J mice fed regular diet (RD) (NC group), C57BL/6J mice fed HFD (HF group), JAZF1-OX mice fed RD (NJ group), and JAZF1-OX mice fed HFD (HJ group). Adipose tissue was harvested 12 weeks later. ATMs were evaluated by flow cytometry. Inflammatory markers were evaluated by ELISA. Results:JAZF1-OX mice had lower blood lipids, blood glucose, body weight, fat weight, and inflammatory markers compared with HF mice (all P < 0.05). JAZF1 overexpression decreased ATM number and secretion of proinflammatory cytokines. JAZF1 overexpression decreased total CD4+ T cells, active T cells, and memory T cells and increased Treg cells. JAZF1 overexpression downregulated IFN-? and IL-17 levels and upregulated IL-4 levels. JAZF1 overexpression decreased MHCII, CD40, and CD86 in total ATM, CD11c+ ATM, and CD206+ ATM. Conclusions:JAZF1 limits adipose tissue inflammation by limiting macrophage populations and restricting their antigen presentation function.
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Project description:Red rice bran extract (RRBE) has been reported to have the potential for in vitro metabolic modulation and anti-inflammatory properties. However, little is known about the molecular mechanisms of these potentials in adipose tissue. This study aimed to evaluate the in vivo anti-adipogenic, anti-hypertrophic, and anti-inflammatory activities of RRBE and its major bioactive compounds in mice. After six weeks of consuming either a low-fat diet or a high-fat diet (HFD), 32 mice with initial body weights of 20.76 ± 0.24 g were randomly divided into four groups; the four groups were fed a low-fat diet, a HFD, a HFD plus 0.5 g/kg of RRBE, or a HFD plus 1 g/kg of RRBE, respectively. The 6-week treatment using RRBE reduced HFD-induced adipocyte hypertrophy, lipid accumulation, and inflammation in intra-abdominal epididymal white adipose tissue (p < 0.05) without causing significant changes in body and adipose tissue weight, which reductions were accompanied by the down-regulated expression of adipogenic and lipid metabolism genes, including CCAAT/enhancer-binding protein-alpha, sterol regulatory element-binding protein-1c, and hormone-sensitive lipase (p < 0.05), as well as inflammatory genes, including macrophage marker F4/80, nuclear factor-kappa B p65, monocyte chemoattractant protein-1, tumor necrosis factor-alpha, and inducible nitric oxide synthase (p < 0.05), in adipose tissue. Furthermore, RRBE significantly decreased serum tumor necrosis factor-alpha levels (p < 0.05). Bioactive compound analyses revealed the presence of phenolics, flavonoids, anthocyanins, and proanthocyanidins in these extracts. Collectively, this study demonstrates that RRBE effectively attenuates HFD-induced pathological adipose tissue remodeling by suppressing adipogenesis, lipid dysmetabolism, and inflammation. Therefore, RRBE may emerge as one of the alternative food products to be used against obesity-associated adipose tissue dysfunction.
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Project description:Consumption of a high-fat diet (HFD) promotes the development of obesity, a disease resulting from an imbalance between energy intake and energy expenditure. Brown adipose tissue (BAT) has thermogenic capacity that burns calories to produce heat, and it is a potential target for the treatment and prevention of obesity. There is limited information regarding the impact of HFD on the BAT transcriptome. We hypothesized that HFD-induced obesity would lead to transcriptional regulation of BAT genes. RNA sequencing was used to generate global transcriptome profiles from BAT of lean mice fed with a low-fat diet (LFD) and obese mice fed with a HFD. Gene Ontology (GO) analysis identified increased expression of genes involved in biological processes (BP) related to immune responses, which enhanced molecular function (MF) in chemokine activity; decreased expression of genes involved in BP related to ion transport and muscle structure development, which reduced MF in channel and transporter activity and structural binding. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional pathway analysis indicated that pathways associated with innate immunity were enhanced by HFD, while pathways associated with muscle contraction and calcium signaling were suppressed by HFD. Collectively, these results suggest that diet-induced obesity changes transcriptomic signatures of BAT, leading to dysfunction involving inflammation, calcium signaling, ion transport, and cell structural development.
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Project description:Adenosine 2A receptor (A2AR) exerts anti-inflammatory effects. However, the role of A2AR in obesity-associated adipose tissue inflammation remains to be elucidated. The present study examined the expression of A2AR in adipose tissue of mice with diet-induced obesity and determined the effect of A2AR disruption on the status of obesity-associated adipose tissue inflammation. WT C57BL/6J mice and A2AR-disrupted mice were fed a high-fat diet (HFD) for 12 weeks to induce obesity and adipose tissue inflammation. In vitro, bone marrow-derived macrophages from A2AR-disrupted mice and WT control mice were treated with palmitate and examined for macrophage proinflammatory activation. Compared with that of low-fat diet (LFD)-fed WT mice, A2AR expression in adipose tissue of HFD-fed WT mice was increased significantly and was present predominantly in adipose tissue macrophages. The increase in adipose tissue A2AR expression in HFD-fed mice was accompanied with increased phosphorylation states of c-Jun N-terminal kinase 1 p46 and nuclear factor kappa B p65 and mRNA levels of interleukin (Il)-1beta, Il6 and tumor necrosis factor alpha. In A2AR-disrupted mice, HFD feeding induced significant increases in adipose tissue inflammation, indicated by enhanced proinflammatory signaling and increased proinflammatory cytokine expression, and adipose tissue insulin resistance, indicated by a decrease in insulin-stimulated Akt phosphorylation relative to those in WT mice. Lastly, A2AR disruption enhanced palmitate-induced macrophage proinflammatory activation. Taken together, these results suggest that A2AR plays a protective role in obesity-associated adipose tissue inflammation, which is attributable to, in large part, A2AR suppression of macrophage proinflammatory activation.
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Project description:ObjectiveAdrenomedullin (ADM) possesses therapeutic potential for inflammatory diseases. Consequently, the effects of ADM on inflammation in visceral white adipose tissue (vWAT) of obese rats or in adipocytes were explored in this study.MethodsMale rats were fed a high-fat diet for 12 weeks to induce obesity, and obese rats were implanted with osmotic minipumps providing constant infusion of ADM (300 ng/kg per hour) and continued to be fed a high-fat diet for 4 weeks.ResultsWhen compared with the control group, endogenous protein expression of ADM and ADM receptors in vWAT and in lipopolysaccharide (LPS)-treated adipocytes was markedly increased. ADM significantly decreased the protein expression of the inflammatory mediators TNF?, IL-1?, cyclooxygenase-2, and inducible nitric oxide synthase in vWAT of obese rats and in adipocytes stimulated by LPS. It also inhibited the activation of the inflammatory signaling pathways MAPK and NF-?B induced by LPS in adipocytes. These effects of ADM in adipocytes were inhibited by the administration of ADM receptor antagonist and cAMP-dependent protein kinase (PKA) activation inhibitor.ConclusionsADM can inhibit inflammation in WAT in obesity, which may be mediated by the activation of ADM receptors and PKA.
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