Epididymal White Adipose Tissue Research Articles

Metabolic effects of CCL5 deficiency in lean and obese mice.

Accumulation and activation of immunocytes in adipose tissues are essential to obesity-induced inflammation and insulin resistance. Chemokines are pivotal for the recruitment of immunocytes in adipose tissue during obesity. Chemokine (C-C motif) ligand 5 (CCL5) plays a vital role in the recruitment of immunocytes to sites of inflammation. CCL5 expression level is increased in obese adipose tissue from humans and mice. However, the role of CCL5 in obesity-induced adipose inflammation remains unclear. Our study found that the CCL5 expression level was increased in the epididymal white adipose tissue (eWAT) of obese mice, particularly in CD8+ T cells. CCL5 knockout (KO) mice exhibited better glucose tolerance than wild-type (WT) mice under lean conditions. In contrast, CCL5 KO mice were more insulin resistant and had severe hepatic steatosis than WT mice under obese conditions. Increased T cells in adipose tissue heaven adipose inflammation in obese CCL5 KO mice. The compensatory increased T cell-associated chemokines may account for increased T cell content in the eWAT of obese CCL5 KO mice. These findings imply that CCL5 deficiency exacerbates adipose inflammation and impairs insulin sensitivity in the metabolic tissues of obese mice.

Dose-Related Regulatory Effect of Raspberry Polyphenolic Extract on Cecal Microbiota Activity, Lipid Metabolism and Inflammation in Rats Fed a Diet Rich in Saturated Fats.

The amount of berry polyphenols required to exert health-promoting effects seems to be difficult to achieve by fresh fruit ingestion, so polyphenol-rich extracts could be considered a dietary alternative. In the present study, laboratory rats were fed high-fat diets supplemented with 0.1 or 0.3% raspberry polyphenols from pomace, with the former dose reflecting the amount of polyphenols consumed with a glass of fresh raspberries. It was hypothesized that beneficial changes in blood and hepatic tissue related to lipid metabolism would accompany both treatments, but the health-promoting effect would be more noticeable with the higher dose of extract. This hypothesis was confirmed, and the high dose of raspberry polyphenols was better than the low dose extract in terms of decreased epididymal white adipose tissue weight, hepatic triglyceride content, PPARγ and SREBP-1c expression in the liver, and plasma IL-6 concentration, as well as increased acetic acid concentration in the cecal digesta. These effects might be partially associated with the enhanced content of ellagitannin and anthocyanin metabolites found in the blood plasma of rats administered the high dose of the extract. The results showed that this extract could be considered a dietary vehicle to provide an amount of raspberry polyphenols that could promote health.

Independent, but not co-supplementation, with nitrate and resveratrol improves glucose tolerance and reduces markers of cellular stress in high-fat-fed male mice.

Independent supplementation with nitrate (NIT) and resveratrol (RSV) enriches various aspects of mitochondrial biology in key metabolic tissues. Although RSV is known to activate Sirt1 and initiate mitochondrial biogenesis, the metabolic benefits elicited by dietary nitrate appear to be dependent on 5'-adenosine monophosphate-activated protein kinase (AMPK)-mediated signaling events, a process also linked to the activation of Sirt1. Although the benefits of individual supplementation with these compounds have been characterized, it is unknown if co-supplementation may produce superior metabolic adaptations. Thus, we aimed to determine if treatment with combined +NIT and +RSV (+RN) could additively alter metabolic adaptations in the presence of a high-fat diet (HFD). Both +RSV and +NIT improved glucose tolerance compared with HFD (P < 0.05); however, this response was attenuated following combined +RN supplementation. Within skeletal muscle, all supplements increased mitochondrial ADP sensitivity compared with HFD (P < 0.05), without altering mitochondrial content. Although +RSV and +NIT decreased hepatic lipid deposition compared with HFD (P < 0.05), this effect was abolished with +RN, which aligned with significant reductions in Sirt1 protein content (P < 0.05) after combined treatment, in the absence of changes to mitochondrial content or function. Within epididymal white adipose tissue (eWAT), all supplements reduced crown-like structure accumulation compared with HFD (P < 0.0001) and mitochondrial reactive oxygen species (ROS) emission (P < 0.05), alongside reduced adipocyte cross-sectional area (CSA) (P < 0.05), with the greatest effect observed after +RN treatment (P = 0.0001). Although the present data suggest additive changes in adipose tissue metabolism after +RN treatment, concomitant impairments in hepatic lipid homeostasis appear to prevent improvements in whole body glucose homeostasis observed with independent treatment, which may be Sirt1 dependent.

Metabolic gene signature in white adipose tissue of oral doses raspberry ketone [4-(4-hydroxyphenyl)-2-butanone] that prevent diet-induced weight gain and induce loss of righting reflex.

Raspberry ketone (RK; [4-(4-hydroxyphenyl)-2-butanone]) is a synthetic flavoring agent and dietary supplement for weight control. This study investigated the metabolic signature of oral doses of RK that prevent weight gain or promote loss of righting reflex (LORR) in C57Bl/6J mice. Daily RK 200mg/kg prevented high-fat diet (HFD; 45% Kcal fat) fed weight gain (∼8% reduction) over 35 days. RNA-seq of inguinal white adipose tissue (WAT) performed in males revealed 12 differentially expressed genes. Apelin (Apln) and potassium voltage-gated channel subfamily C member (Kcnc3) expression were elevated with HFD and normalized with RK dosing, which was confirmed by qPCR. Acute RK 640mg/kg produced a LORR with a <5min onset with a >30min duration. Acute RK 200mg/kg increased gene expression of Apln, Kcnc3, and nuclear factor erythroid 2-related factor 2 (Nrf2), but reduced acetyl-COA carboxylase (Acc1) and NAD(P)H quinone dehydrogenase 1 (Nqo1) in inguinal WAT. Acute RK 640mg/kg elevated interleukin 6 (Il 6) and heme oxygenase 1 (Hmox1) expression, but reduced Nrf2 in inguinal and epididymal WAT. Our findings suggest that RK has a dose-dependent metabolic signature in WAT associated with either weight control or LORR.

Depot-specific adaption of adipose tissue for different exercise approaches in high-fat diet/streptozocin-induced diabetic mice.

Background: Adipose tissue pathology plays a crucial role in the pathogenesis of type 2 diabetes mellitus. Understanding the impact of exercise training on adipose tissue adaptation is of paramount importance in enhancing metabolic health. In this study, we aimed to investigate the effects of various exercise modalities on three distinct adipose tissue depots, namely, interscapular brown adipose tissue (iBAT), subcutaneous white adipose tissue (sWAT), and epididymal white adipose tissue (eWAT), in a murine model of diabetes. Methods: Male C57BL/6J mice received a 12-week high-fat diet and a single injection of streptozotocin, followed by an 8-week exercise intervention. The exercise intervention included swimming, resistance training, aerobic exercise, and high-intensity interval training (HIIT). Results: We found that exercise training reduced body weight and body fat percentage, diminished adipocyte size and increased the expression of mitochondria-related genes (PGC1, COX4, and COX8B) in three adipose tissue depots. The effects of exercise on inflammatory status include a reduction in crown-like structures and the expression of inflammatory factors, mainly in eWAT. Besides, exercise only induces the browning of sWAT, which may be related to the expression of the sympathetic marker tyrosine hydroxylase. Among the four forms of exercise, HIIT was the most effective in reducing body fat percentage, increasing muscle mass and reducing eWAT adipocyte size. The expression of oxidative phosphorylation and thermogenesis-related genes in sWAT and eWAT was highest in the HIIT group. Conclusion: When targeting adipose tissue to improve diabetes, HIIT may offer superior benefits and thus represents a more advantageous choice.

Identification and tissue distribution of fucoxanthinol and amarouciaxanthin A fatty acid esters in fucoxanthin-fed mice

Administered carotenoid fatty acid esters are thought to be hydrolyzed to their free forms and absorbed into the body, and information on the tissue distribution of carotenoid fatty acid esters has been limited. Fucoxanthin, a marine carotenoid, exhibits various health benefits, including anti-diabetic and anti-obesity effects. However, fucoxanthin metabolism in mammals remains unclear. Herein, we investigated the fatty acid esters of fucoxanthin metabolites, fucoxanthinol and amarouciaxanthin A, in the tissues of male C57BL/6J mice fed a fucoxanthin-containing diet for one week. Fucoxanthinol and amarouciaxanthin A-3-esters accumulated abundantly in the liver and epididymal white adipose tissue, respectively. These esters were less detectable in the serum and other tissues. Therefore, it is suggested that fucoxanthinol and amarouciaxanthin A are partially acylated in the liver and epididymal white adipose tissue after being transported through the body as their free forms. This study presents a novel carotenoid metabolic pathway in mammals.

Anmyungambi Decoction Ameliorates Obesity through Activation of Non-Shivering Thermogenesis in Brown and White Adipose Tissues.

Obesity is a burden to global health. Non-shivering thermogenesis of brown adipose tissue (BAT) and white adipose tissue (WAT) is a novel strategy for obesity treatment. Anmyungambi (AMGB) decoction is a multi-herb decoction with clinical anti-obesity effects. Here, we show the effects of AMGB decoction using high-fat diet (HFD)-fed C57BL6/J mice. All four versions of AMGB decoction (100 mg/kg/day, oral gavage for 28 days) suppressed body weight gain and obesity-related blood parameters in the HFD-fed obese mice. They also inhibited adipogenesis and induced lipolysis in inguinal WAT (iWAT). Especially, the AMGB-4 with 2:1:3:3 composition was the most effective; thus, further studies were performed with the AMGB-4 decoction. The AMGB-4 decoction displayed a dose-dependent body weight gain suppression. Serum triglyceride, total cholesterol, and blood glucose decreased as well. In epididymal WAT, iWAT, and BAT, the AMGB-4 decoction increased lipolysis markers. Additionally, the AMGB-4 decoction-fed mice showed an increased non-shivering thermogenic program in BAT and iWAT. Excessive reactive oxygen species (ROS) and suppressed antioxidative factors induced by the HFD feeding were also altered to normal levels by the AMGB-4 decoction treatment. Overall, our study supports the clinical use of AMGB decoction for obesity treatment by studying its mechanisms. AMGB decoction alleviates obesity through the activation of the lipolysis-thermogenesis program and the elimination of pathological ROS in thermogenic adipose tissues.

Modulation of PPARα-thermogenesis gut microbiota interactions in obese mice administrated with zingerone.

This study aimed to uncover the potential effects of zingerone (ZIN), one of the bioactive compounds in ginger, on the development of obesity as well as the mechanisms responsible for these effects in C57BL/6J mice fed with a high-fat diet (HFD). Supplementation with 0.2% (wt/wt) zingerone for 16 weeks significantly reduced the final body weight, liver weight, and epididymal white adipose tissue (eWAT) weight without changing the food intake of the mice when compared with the HFD group. The hyperlipidemia of HFD-fed mice was ameliorated after zingerone administration, including decreased plasma triacylglycerol (TG) and total cholesterol (TC) level. The lipid content in liver was lower and the adipocyte size in eWAT and inguinal white adipose tissue (iWAT) was smaller in HFD + ZIN-fed mice compared with HFD group. Zingerone also binds with nuclear hormone receptor peroxisome proliferator-activated receptor alpha (PPARα) with an optimal docking energy of -7.31 kJ/mol. Uncoupling protein 1 (UCP1), PPAR-γ coactivator-1α (PGC-1α), and PR domain containing 16 (PRDM16), the downstream genes of PPAR which are related to thermogenic function of adipocytes, were significantly increased in both brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT) after zingerone administration, in comparison with HFD fed mice. Zingerone intake also restructured the community composition of gut microbiota. The ratio of Firmicutes to Bacteroidetes was decreased, and the relative abundance of Akkermansia_mucinphila was increased. Zingerone can attenuate obesity and related symptoms in HFD-fed mice, probably through the modulation of PPARα-thermogenesis-gut microbiota interactions. © 2022 Society of Chemical Industry.

Garlic-derived exosomes carrying miR-396e shapes macrophage metabolic reprograming to mitigate the inflammatory response in obese adipose tissue

Low-grade chronic inflammation originating from the adipose tissue and imbalance of lipid metabolism in the liver are the main drivers of the development of obesity and its related metabolic disorders. In this work, we found that garlic-derived exosomes (GDE) supplementation improved insulin resistance, altered the levels of inflammatory cytokines in serum and epididymal white adipose tissue (eWAT) by decreasing the accumulation of macrophages in HFD-fed mice. Meanwhile, we also observed that GDE regulated the expression of 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3), one of the critical glycolytic enzymes, to shape the metabolic reprograming of macrophage induced by lipopolysaccharide (LPS) and mitigate the inflammatory response in adipocytes via macrophage-adipocyte cross-talk. Data from small RNA sequencing, bioinformatical analysis and the gene over-expression revealed that miR-396e, one of the most abundant miRNAs of GDE, played a critical role in promoting the metabolic reprogramming of macrophage by directly targeting PFKFB3. The findings of this study not only provide an in-depth understanding of GDE protecting against inflammation in obesity but supply evidence to study the molecular mechanisms associated with the interspecies communication.

Maternal Supplementation with a Cocoa Extract during Lactation Deeply Modulates Dams’ Metabolism, Increases Adiponectin Circulating Levels and Improves the Inflammatory Profile in Obese Rat Offspring

High-flavonoid cocoa consumption has been associated with beneficial properties. However, there are scarce data concerning the effects of maternal cocoa intake on dams and in their progeny. Here, we evaluated in rats whether maternal supplementation with a high-flavan-3-ol cocoa extract (CCX) during lactation (200 mg.kg-1.day-1) produced beneficial effects on dams and in their normoweight (STD-CCX group) and cafeteria-fed obese (CAF-CCX group) adult male offspring. Maternal intake of CCX significantly increased the circulating levels of adiponectin and decreased the mammary gland lipid content of dams. These effects were accompanied by increased energy expenditure and circulating free fatty acids, as well as by a higher expression of lipogenic and adiponectin-related genes in their mammary glands, which could be related to a compensatory mechanism to ensure enough lipid supply to the pups. CCX consumption programmed both offspring groups towards increased plasma total adiponectin levels, and decreased liver weight and lean/fat ratio. Furthermore, CAF-CCX progeny showed an improvement of the inflammatory profile, evidenced by the significant decrease of the monocyte chemoattractant protein-1 (MCP-1) circulating levels and the mRNA levels of the gene encoding the major histocompatibility complex, class II invariant chain (Cd74), a marker of M1 macrophage phenotype, in the epididymal white adipose tissue. Although further studies are needed, these findings can pave the way for using CCX as a nutraceutical supplement during lactation.

Timing of Medium-Chain Triglyceride Consumption Modulates Effects in Mice with Obesity Induced by a High-Fat High-Sucrose Diet

The prevalence of obesity is increasing worldwide, and obesity can cause type 2 diabetes, atherosclerosis, hypertension, cardiovascular disease, and cancer. Intake of medium-chain triglycerides (MCTs) containing medium-chain fatty acids reduces body fat and insulin resistance in rodents and humans. This study aimed to determine how the timing of MCT consumption affects obesity and metabolic dysfunction induced in mice by a high-fat high-sucrose diet (HFHSD). Mice received an HFHSD with or without MCT (M-HFHSD) during either the active or rest phase for 9 weeks. Significant reduction in body weight, white adipose tissue (WAT) weight, and adipocyte size in epididymal WAT (eWAT) and improved insulin sensitivity in mice fed with M-HFHSD during the active but not the rest phase were observed. The consumption of M-HFHSD during both active and rest phases increased glucose tolerance. Phosphorylated Akt was more abundant in the gastrocnemius muscles and eWAT of M-HFHSD-fed mice than in those fed HFHSD during the active phase. The mRNA and protein expression of lipogenic genes increased in the eWAT of mice fed M-HFHSD compared with those fed HFHSD. Feeding with M-HFHSD during the active phase significantly increased the abundance of phosphorylated Ser563 and 660 of hormone-sensitive lipase and its upstream protein kinase A in eWAT. These results indicated that the timing of consumption modulates the effects of MCT on eWAT hypertrophy and glucose and lipid metabolism in mice.

[Impact and mechanism of CHL1 in insulin resistant adipocytes and insulin resistant mouse model induced by high glucose and high fat].

Objective: To investigate the role and mechanism of cell adhesion molecule L1 like (CHL1) in insulin resistant adipocytes and insulin resistant mouse model induced by high glucose and high fat. Methods: The 3T3-L1 preadipocytes were randomly divided into control group (transfected with empty vector) and CHL1 overexpression group (transfected with CHL1 vector), cells were then induced to mature adipocytes by insulin, and insulin resistance was then induced by high sugar and high fat. The glucose content was measured to determine the glucose consumption of cells from the two groups. Protein expression levels of CHL1 and glucose transporter 4 (GLUT4), serine/threonine protein kinase (AKT) phosphorylation levels were detected by Western blot (WB), the mRNA expression levels of TNF-α and IL-6 were detected by real-time quantitative PCR (RT-qPCR). 24 C57BL/6 adult male mouse were randomly divided into conventional diet group (regular group), high-fat diet group (high-fat group), empty vector overexpression+high-fat group and CHL1 overexpression+high-fat group (n=6 each group). CHL1 overexpression was induced by tail vein injection of lentivirus. Four months later, mice were sacrificed, body weight was determined, and the epididymal white adipose tissue was collect. Hematoxylin-eosin staining (HE) was used to observe the pathology of mouse epididymal white adipose tissue, the expression of CHL1 was evaluated by immunohistochemical staining(IHC), RT-qPCR was used to detect the mRNA expression levels of CHL1, TNF-α and IL-6 in mouse epididymal white adipose tissue. Results: In vitro, glucose consumption was significantly higher in the CHL1 overexpression group than in the control group (P<0.05), and the protein expressions of CHL1 and GLUT4 were higher in the CHL1 overexpression group than those in the control group (P<0.01), and the mRNA expressions levels of TNF-α and IL-6 were lower in the CHL1 overexpression group than those in the control group (P<0.01). In vivo, the body weight and epididymal white adipose tissue of mouse were higher in the high-fat group and the empty vector overexpression+high-fat group than those in the conventional group (P<0.01), which were lower in the CHL1 overexpression+high fat group than in the empty vector overexpression+high fat group (P<0.01). HE results showed that the volume of epididymal white adipocytes was larger in the high-fat group and the overexpression control+high-fat group than that in the conventional group, which was smaller in the CHL1 overexpression+high fat group than in the empty vector overexpression+high fat group (P<0.01). The mRNA expression levels of IL-6 and TNF-α in epididymal white adipose tissue of mice were higher in the high-fat group and the empty vector overexpression+high-fat group than those in the conventional group (P<0.01), which were lower in the CHL1 overexpression+high fat group than in the empty vector overexpression+high fat group (P<0.05). IHC results showed that protein expression of CHL1 in epididymal white adipose tissue was lower in the high-fat group and the empty vector overexpression+high-fat group than in regular group, which was upregulated in the CHL1 overexpression+high fat group than in the empty vector overexpression+high-fat group (P<0.01). RT-qPCR results showed that mRNA expression of CHL1 in epididymal white adipose tissue was lower in the high-fat group and the empty vector overexpression+high-fat group than in regular group (P<0.01), which was higher in the CHL1 overexpression+high fat group than in the empty vector overexpression+high fat group (P<0.01). Conclusion: Overexpression of CHL1 can improve insulin resistance in adipocytes and mouse insulin resistance model induced by high glucose and high fat, and the beneficial effects might be mediated by the inhibition of AKT activation and the reduction of related inflammatory responses.

Brevibacillus laterosporus BL1, a promising probiotic, prevents obesity and modulates gut microbiota in mice fed a high-fat diet.

Probiotics are a potential preventive strategy for obesity. However, with discrete efficacy and limited species of probiotics, there is a demand for novel strains with excellent anti-obesity properties. This study aimed to investigate the effects of Brevibacillus laterosporus BL1 on preventing obesity in high-fat diet (HFD)-fed mice. C57BL/6 male mice were randomly assigned to four groups (n = 10) and fed a control diet, HFD, HFD plus B. laterosporus BL1, and HFD plus supernatant of B. laterosporus BL1, respectively for 8 weeks. The results showed that prophylactic B. laterosporus BL1 treatment reduced body weight gain by 41.26% in comparison to the HFD group, and this difference was accompanied by a reduction in body fat mass and the weight of inguinal white adipose tissues and epididymal white adipose tissue (-33.39%, -39.07%, and -43.75%, respectively). Moreover, the B. laterosporus BL1-mediated improvements in lipid profile, insulin resistance, and chronic inflammation were associated with the regulation of gene expression related to lipid metabolism and enhancement of brown adipose tissue thermogenesis. Particularly, B. laterosporus BL1 intervention significantly improved HFD-induced gut flora dysbiosis, as evidenced by a reverse in the relative abundance of Bacillota and Bacteroidota, as well as an increase in the relative abundance of bacteria that produce short-chain fatty acids (SCFAs), which in turn increased SCFAs levels. Our findings found for the first time that B. laterosporus BL1 may be a promising probiotic for prevention of obesity associated with the regulation of gut microbiota.

Nomegestrol acetate ameliorated adipose atrophy in a rat model of cisplatin‑induced cachexia.

Cachexia, a complex disorder that results in depletion of adipose tissue and skeletal muscle, is driven by anorexia, metabolic abnormalities and inflammation. There are limited therapeutic options for this syndrome. Previous evidence has demonstrated that increasing adipose tissue may improve quality of life and survival outcomes in cachexia. Cisplatin, as a chemotherapy drug, also causes cachexia during antitumor therapy due to its adverse effects. To establish a rat model of cachexia, the animals were intraperitoneally treated with cisplatin at doses of 1, 2 and 3 mg/kg, and the rats that responded to cisplatin at the optimal dose were used to test the effect of nomegestrol acetate (NOMAc). Rats that were assessed to be sensitive to cisplatin were randomly grouped and intragastrically administered vehicle, 5 or 10 mg/kg megestrol acetate (MA) or 2.5, 5 or 10 mg/kg NOMAc. The body weights and food consumption of the rats were assessed. Serum IL-6 and TNF-α levels were assessed using ELISA. The protein expression levels of adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), peroxisome proliferator activated receptor γ (PPARγ), fatty acid synthase (FASN) and sterol regulatory element-binding protein-1 (SREBP-1) from inguinal white adipose tissue (iWAT) and epididymal white adipose tissue (eWAT) were evaluated using western blotting. The optimal way to establish a chemotherapy-induced rat model of cachexia demonstrated in the present study was to intraperitoneally administer the rats with 2 mg/kg cisplatin for 3 consecutive days. NOMAc (2.5, 5 mg/kg) and MA (10 mg/kg) were able to significantly ameliorate the loss of body weight in the cisplatin-induced cachectic rats. NOMAc significantly reduced the serum levels of TNF-α at 10 mg/kg. Morphologically, iWAT atrophy, with a remarkable reduction in adipocyte volume, was observed in the cisplatin-induced cachectic rats, but the effects were reversed by administering 5, 10 mg/kg NOMAc or 10 mg/kg MA. Furthermore, 2.5 mg/kg NOMAc markedly reduced the protein expression levels of the lipolysis genes HSL and ATGL, and 5 mg/kg NOMAc markedly enhanced the protein expression levels of adipogenesis genes, including FASN, SREBP-1 and PPARγ in iWAT but not in eWAT. NOMAc was demonstrated to improve cachexia at lower doses compared with MA. Overall, NOMAc is likely to be a promising candidate drug for ameliorating cancer cachexia induced by cisplatin.

Adipose Tissue-Derived CCL5 Enhances Local Pro-Inflammatory Monocytic MDSCs Accumulation and Inflammation via CCR5 Receptor in High-Fat Diet-Fed Mice.

The C-C chemokine motif ligand 5 (CCL5) and its receptors have recently been thought to be substantially involved in the development of obesity-associated adipose tissue inflammation and insulin resistance. However, the respective contributions of tissue-derived and myeloid-derived CCL5 to the etiology of obesity-induced adipose tissue inflammation and insulin resistance, and the involvement of monocytic myeloid-derived suppressor cells (MDSCs), remain unclear. This study used CCL5-knockout mice combined with bone marrow transplantation (BMT) and mice with local injections of shCCL5/shCCR5 or CCL5/CCR5 lentivirus into bilateral epididymal white adipose tissue (eWAT). CCL5 gene deletion significantly ameliorated HFD-induced inflammatory reactions in eWAT and protected against the development of obesity and insulin resistance. In addition, tissue (non-hematopoietic) deletion of CCL5 using the BMT method not only ameliorated adipose tissue inflammation by suppressing pro-inflammatory M-MDSC (CD11b+Ly6G-Ly6Chi) accumulation and skewing local M1 macrophage polarization, but also recruited reparative M-MDSCs (CD11b+Ly6G-Ly6Clow) and M2 macrophages to the eWAT of HFD-induced obese mice, as shown by flow cytometry. Furthermore, modulation of tissue-derived CCL5/CCR5 expression by local injection of shCCL5/shCCR5 or CCL5/CCR5 lentivirus substantially impacted the distribution of pro-inflammatory and reparative M-MDSCs as well as macrophage polarization in bilateral eWAT. These findings suggest that an obesity-induced increase in adipose tissue CCL5-mediated signaling is crucial in the recruitment of tissue M-MDSCs and their trans-differentiation to tissue pro-inflammatory macrophages, resulting in adipose tissue inflammation and insulin resistance.

Acetylation of PPARγ in macrophages promotes visceral fat degeneration in obesity.

Obesity is characterized by chronic, low-grade inflammation, which is driven by macrophage infiltration of adipose tissue. PPARγ is well established to have an anti-inflammatory function in macrophages, but the mechanism that regulates its function in these cells remains to be fully elucidated. PPARγ undergoes post-translational modifications (PTMs), including acetylation, to mediate ligand responses, including on metabolic functions. Here, we report that PPARγ acetylation in macrophages promotes their infiltration into adipose tissue, exacerbating metabolic dysregulation. We generated a mouse line that expresses a macrophage-specific, constitutive acetylation-mimetic form of PPARγ (K293Qflox/flox:LysM-cre, mK293Q) to dissect the role of PPARγ acetylation in macrophages. Upon high-fat diet feeding to stimulate macrophage infiltration into adipose tissue, we assessed the overall metabolic profile and tissue-specific phenotype of the mutant mice, including responses to the PPARγ agonist Rosiglitazone. Macrophage-specific PPARγ K293Q expression promotes proinflammatory macrophage infiltration and fibrosis in epididymal white adipose tissue, but not in subcutaneous or brown adipose tissue, leading to decreased energy expenditure, insulin sensitivity, glucose tolerance, and adipose tissue function. Furthermore, mK293Q mice are resistant to Rosiglitazone-induced improvements in adipose tissue remodeling. Our study reveals that acetylation is a new layer of PPARγ regulation in macrophage activation, and highlights the importance and potential therapeutic implications of such PTMs in regulating metabolism.

Dopaminergic and adrenergic receptors synergistically stimulate browning in 3T3-L1 white adipocytes.

The browning of white adipose tissue (WAT) has attracted considerable attention in the scientific community as a popular strategy for enhancing energy expenditure to combat obesity. As a part of this strategy, β3-adrenergic receptor (β3-AR) is the most widely studied receptor that mediates thermogenesis. Parenthetically, further studies in search for additional receptors expressed in adipocytes that can mediate thermogenesis has been appearing, and this paper reports that dopaminergic receptor 1 (DRD1) and β3-AR synergistically stimulate browning in 3T3-L1 white adipocytes. qRT-PCR and immunoblot analysis methods were applied to evaluate the effects of DRD1 on the target proteins downstream of β3-AR and other markers involved in lipid metabolism, mitochondrial biogenesis, and browning events. These results show that DRD1 is expressed in epididymal WAT (eWAT), brown adipose tissue (BAT), and inguinal WAT (iWAT) of normal and high-fat-fed mice, and a deficiency of DRD1 downregulates the expression of brown adipocyte-specific proteins. Silencing of DRD1 affected lipid metabolic activity in 3T3-L1 adipocytes by reducing mitochondrial biogenesis as well as levels of lipolytic and fat oxidative marker proteins in a similar pattern to β3-AR. Moreover, mechanistic studies showed that the depletion of DRD1 downregulates β3-AR and its downstream molecules, suggesting both receptors might synergistically stimulate browning. Parallel to the UCP1-dependent thermogenesis, the depletion of DRD1 also downregulates the expression of core proteins responsible for UCP1-independent thermogenesis. Overall, DRD1 mediates β3-AR-dependent 3T3-L1 browning and UCP1-independent thermogenesis.

Deficiency of exchange protein directly activated by cAMP (EPAC)-1 in mice augments glucose intolerance, inflammation, and gut dysbiosis associated with Western diet

BackgroundGut microbiota (GM) dysregulation, known as dysbiosis, has been proposed as a crucial driver of obesity associated with “Western” diet (WD) consumption. Gut dysbiosis is associated with increased gut permeability, inflammation, and insulin resistance. However, host metabolic pathways implicated in the pathophysiology of gut dysbiosis are still elusive. Exchange protein directly activated by cAMP (Epac) plays a critical role in cell-cell junction formation and insulin secretion. Here, we used homozygous Epac1-knockout (Epac1–/–), Epac2-knockout (Epac2–/–), and wild-type (WT) mice to investigate the role of Epac proteins in mediating gut dysbiosis, gut permeability, and inflammation after WD feeding.ResultsThe 16S rRNA gene sequencing of fecal DNA showed that the baseline GM of Epac2–/–, but not Epac1–/–, mice was represented by a significantly higher Firmicutes to Bacteroidetes ratio and significant alterations in several taxa compared to WT mice, suggesting that Epac2–/– mice had gut dysbiosis under physiological conditions. However, an 8-week WD led to a similar gut microbiome imbalance in mice regardless of genotype. While Epac1 deficiency modestly exacerbated the WD-induced GM dysbiosis, the WD-fed Epac2–/– mice had a more significant increase in gut permeability than corresponding WT mice. After WD feeding, Epac1–/–, but not Epac2–/–, mice had significantly higher mRNA levels of tumor necrosis factor-alpha (TNF-α) and F4/80 in the epididymal white adipose tissue (EWAT), increased circulating lipocalin-2 protein and more severe glucose intolerance, suggesting greater inflammation and insulin resistance in WD-fed Epac1–/– mice than corresponding WT mice. Consistently, Epac1 protein expression was significantly reduced in the EWAT of WD-fed WT and Epac2–/– mice.ConclusionDespite significantly dysregulated baseline GM and a more pronounced increase in gut permeability upon WD feeding, WD-fed Epac2–/– mice did not exhibit more severe inflammation and glucose intolerance than corresponding WT mice. These findings suggest that the role of gut dysbiosis in mediating WD-associated obesity may be context-dependent. On the contrary, we demonstrate that deficiency of host signaling protein, Epac1, drives inflammation and glucose intolerance which are the hallmarks of WD-induced obesity.2Aidzb_xKQhqE4JPFGVMhLVideo abstract

Cathepsin S inhibitor reduces high-fat-induced adipogenesis, inflammatory infiltration, and hepatic lipid accumulation in obese mice.

Obesity, which results from a caloric intake and energy expenditure imbalance, is highly prevalent worldwide. Cathepsin S (CTSS), which is a cysteine protease, is elevated in obesity and may regulate a variety of physiological processes. This study sought to investigate the functional role of CTSS in obesity. Mice were administrated 60 mg/kg of RO5444101 in vivo and fed a high-fat diet (HFD) to induce obesity. The weights of the mice fed a normal-chow diet and a HFD were measured. The expression levels of total triglycerides (TG), total cholesterol (TC), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and monocyte chemoattractant protein-1 (MCP-1) were assessed using appropriate corresponding assay kits. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to estimate the messenger ribonucleic acid (mRNA) expression of CTSS in the serum and the release of M1- and M2-type cytokines, and western blot was used to measure the phosphorylated-nuclear factor kappaB (NF-kappaB) p65 and NF-κB p65 proteins. The mRNA and protein expressions of sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FASN), leptin, and adiponectin were also evaluated by RT-qPCR and western blot. Further, hematoxylin and eosin (H&E), immunohistochemical, and red oil O staining were employed to detect the pathological changes of the epididymal white adipose tissue (eWAT), the macrophage infiltration in the eWAT, and lipid accumulation, respectively. We found that CTSS was elevated in the plasma, visceral adipose, and liver tissues of the obese mice. After the administration of 60 mg/kg of RO5444101, the weight of the obese mice decreased, insulin resistance was inhibited, and adipocyte formation was suppressed. The CTSS inhibitor also decreased the level of macrophage infiltration in the eWAT, MCP-1 expression, and the release of M1- and M2-type cytokines in the HFD-induced mice. The CTSS inhibitor appeared to improve the hepatic function parameters and lipid accumulation of the HFD-induced mice. The CTSS inhibitor also appeared to improve the inflammatory damage in the HFD-induced mice. CTSS inhibitor helped to protect against HFD-induced adipogenesis, inflammatory infiltration, and hepatic lipid accumulation in obese mice.

UCP2 KO mice exhibit ameliorated obesity and inflammation induced by high-fat diet feeding

Uncoupling protein 2 (Ucp2) was first introduced as a member of Uncoupling protein family and a regulator of ROS formation; however, its role in adipose tissue is not fully understood. In the present study, we have investigated the role of Ucp2 against high-fat diet (HFD)-induced obesity in epididymal white adipose tissue (eWAT) and browning of inguinal white adipose tissue (iWAT). Diet-induced obesity is closely related to macrophage infiltration and the secretion of pro-inflammatory cytokines. Macrophages surround adipocytes and form a crown-like-structure (CLS). Some reports have suggested that CLS formation requires adipocyte apoptosis. After 12 weeks of HFD challenge, Ucp2 knockout (KO) mice maintained relatively lean phenotypes compared to wild-type (WT) mice. In eWAT, macrophage infiltration, CLS formation, and inflammatory cytokines were reduced in HFD KO mice compared to HFD WT mice. Surprisingly, we found that apoptotic signals were also reduced in the Ucp2 KO mice. Our study suggests that Ucp2 deficiency may prevent diet-induced obesity by regulating adipocyte apoptosis. However, Ucp2 deficiency did not affect the browning capacity of iWAT. [BMB Reports 2022; 55(10): 500-505].