Impaired contact hypersensitivity in diet-induced obese mice

Immature Persimmon (Diospyros kaki Thunb.) Ethanol Extract Ameliorates High-Fat Diet-Induced Obesity by Modulating Lipid Metabolism

In this study, immature persimmon (Diospyros kaki Thunb.) ethanol extract was administered to an obese animal model fed a high-fat diet to measure weight change, adipose tissue weight, serum lipid level, and expression level of adipose-related genes to evaluate its efficacy. Administration of D. kaki ethanol extract (DKE) (100 and 500 mg/kg/d) decreased the body weight gain, adipose tissue weight, and serum triglyceride levels in mice fed a high-fat diet. Furthermore, it improved the leptin and adiponectin levels in the blood as well as gene expression in the liver. It also inhibited the expression of sterol regulatory element-binding protein-1c, inhibiting the production of triglyceride biosynthetic enzyme fatty acid synthesis and acetyl-CoA carboxylase, and decreased the expressions of peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding proteins that induce adipocyte differentiation. Therefore, these data suggest that DKE exerts beneficial effects on high-fat diet-induced obesity by modulating lipid metabolism in mice fed a high-fat diet.

Modulation of allergic contact dermatitis via gut microbiota modified by diet, vitamins, probiotics, prebiotics, and antibiotics

Allergic contact dermatitis is one of the most common recorded occupational diseases. There are many different substances that the skin comes into contact with on a daily basis and that can cause ACD, e.g., preservatives, surfactants, and antimicrobial agents. The development of a mouse model of ACD has provided insight into the immune mechanisms involved. Drugs used in the treatment of skin diseases have many side effects. Therefore, alternative methods of suppressing the immune response to reduce the symptoms of skin diseases are being sought. In recent years, high hopes have been placed on dietary modulation and supplementation to affect the intestinal microbial composition and promote anti-inflammatory responses. In addition, other studies have shown the crucial role of intestinal microbiota in many immune-mediated diseases. Recognition and characterization of pro- and anti-inflammatory nutrients and supplements may be crucial to support the treatment of diseases such as atopic dermatitis, acne vulgaris, psoriasis, and allergic contact dermatitis.

Diet-induced obesity results in impaired oral tolerance induction

INTRODUCTION

Obesity increases the risk of several diseases, such as type 2 diabetes mellitus and cardiovascular disease. Obesity also affects the immune system. When dietary lipids are transported via the lymphatics, they pass the mesenteric lymph nodes (mLNs). In these secondary lymphoid organs, immune responses towards pathogens are generated, or tolerance against harmless antigens is induced.

METHODS

In this study, the effects of diet-induced obesity (DIO) on mLN induced oral tolerance induction were examined in C57BL/6NCrl mice. Therefore, mice were fed a high-fat or a low-fat diet for 14 weeks. After 10 weeks of feeding oral tolerance induction started, ending up in measuring the delayed-type hypersensitivity reaction, the cell subset composition and cytokine expression.

RESULTS

We detected an impaired oral tolerance induction during DIO, but changes were reversible after switching the feed to standard chow. Thus, the altered immunological function of mLNs depends on the intake of dietary lipids. Additionally, our results show an influence of the microenvironment on the development of oral tolerance during DIO as oral tolerance was induced in transplanted peripheral lymph nodes.

CONCLUSION

This indicates a functional influence of dietary lipids on stromal cells involved in immune system induction in the mLNs.

Obesity aggravates contact hypersensitivity reaction in mice

BACKGROUND

Obesity is associated with chronic, low-grade inflammation in tissues and predisposes to various complications, including inflammatory skin diseases. However, the link between obesity and contact hypersensitivity (CHS) is not fully understood.

OBJECTIVES

We sought to determine the influence of obesity on T helper 1 (Th1)-mediated CHS.

METHODS

The activity/phenotype/cytokine profile of the immune cells was tested in vivo and in vitro. Using quantitative polymerase chain reaction (qPCR) and fecal microbiota transplantation (FMT), we tested the role of a high-fat diet (HFD)-induced gut microbiota (GM) dysbiosis in increasing the effects of CHS.

RESULTS

Exacerbated CHS correlates with an increased inflammation-inducing GM in obese mice. We showed a proinflammatory milieu in the subcutaneous adipose tissue of obese mice, accompanied by proinflammatory CD4+ T cells and dendritic cells in skin draining lymph nodes and spleen. Obese interleukin (IL)-17A-/-B6 mice are protected from CHS aggravation, suggesting the importance of IL-17A in CHS aggravation in obesity.

CONCLUSIONS

Obesity creates a milieu that induces more potent CHS-effector cells but does not have effects on already activated CHS-effector cells. IL-17A is essential for the pathogenesis of enhanced CHS during obesity. Our study provides novel knowledge about antigen-specific responses in obesity, which may help with the improvement of existing treatment and/or in designing novel treatment for obesity-associated skin disorders.

Feeding of a fat-enriched diet causes the loss of resistance to contact hypersensitivity

BACKGROUND

Low-molecular weight chemicals or metal ions can cause allergic contact dermatitis, an inflammatory skin disease. Mice lacking Toll-like receptors 2 and 4 (TLR2/4 mice) are resistant to contact hypersensitivity (CHS). In the Western population obesity is increasing, which is known to have a proinflammatory impact.

OBJECTIVES

The aim of this study was to investigate the impact of a high-fat diet (HFD) on the sensitization and elicitation of CHS. We hypothesized that a proinflammatory micromilieu can be caused by an increase in adipose tissue, which might be sufficient to break the resistance of TLR2/4 mice.

METHODS

Four weeks prior to sensitization, wild-type (wt) or TLR2/4 mice were fed normal chow (NC), control diet (CD), or HFD. The effects on CHS and inflammation were analysed by measuring the ear swelling response, using flow cytometry and enzyme-linked immunosorbent assay.

RESULTS

The reaction of wt mice to 2,4,6-trinitro-1-chlorobenzene (TNCB) was increased by HFD. While NC-fed TLR2/4 mice were still resistant to CHS, HFD and, unexpectedly, CD feeding broke the resistance of TLR2/4 mice to TNCB.

CONCLUSIONS

These experiments suggest that the increased fat content or the different fatty acid composition of the diets increases inflammation and, therefore, the likelihood of developing CHS.

Diet-induced obesity aggravates NK cell-mediated contact hypersensitivity reaction in Rag1-/- mice

BACKGROUND

Previous studies showed that natural killer (NK) cells mediate contact hypersensitivity (CHS) reaction. Many reports are showing that obesity promotes several inflammatory diseases. It was shown that diet-induced obesity (DIO) aggravates classical T cell-mediated CHS in mice.

OBJECTIVES

To determine whether the high-fat diet (HFD)-induced obesity modulates antigen-specific NK cell-mediated response.

METHODS

We evaluated the effect of DIO on NK cell-mediated CHS reaction using a model of dinitrofluorobenzene (DNFB)-induced CHS in Rag1-/- mice.

RESULTS

Rag1-/- mice fed HFD for 8 but not for 4 weeks developed aggravated CHS reaction determined by ear swelling measurement when compared to animals kept on normal diet (ND) prior to DNFB sensitization. The obese Rag1-/- mice presented the adipose tissue inflammation. Furthermore, in vitro analysis showed that feeding with HFD significantly increases interferon γ (IFN-γ) and interleukin (IL)-12p70 and decreases adiponectin concentration in liver mononuclear cell (LMNC) culture supernatants. The flow cytometry analysis of LMNC revealed that HFD treatment prior to DNFB sensitization increases the percentage of NK1.1+ IFN-γ+ cell population and affects the development and maturation of NK1.1+ cells.

CONCLUSIONS

In summary, current results suggest that the DIO significantly modulates the local and systemic inflammatory response, contributing to exacerbation of the CHS response mediated by liver NK cells.

Taeumjowi-tang, a Traditional Korean Sasang Remedy, Improves Obesity-Atopic Dermatitis Comorbidity by Regulating Hypoxia-Inducible Factor 1 Alpha

Atopic dermatitis (AD) is an inflammatory disease of the skin, resulting from an immune dysfunction, that often occurs as a comorbidity of obesity. This investigation evaluated the capacity of Taeumjowi-tang (TJT), a Korean herbal formulation from the Sasang medical tradition to influence prognostic features of AD and obesity in a mouse model. Here, obesity and AD were induced by a high-fat diet (HFD) and 1-fluoro-2,4-dinitrobenzene (DNFB). Following an 8-week HFD regimen and 4 weeks of DNFB administration, the comorbid (CO) group manifested increased body weight and AD-like lesions, as compared to normal control (NC) mice, while TJT administration diminished these symptoms of obesity and AD. Specifically, TJT treatment reduced epidermal thickness and eosinophil/mast cell infiltration, along with reduction in immunoglobulin E, interleukin (IL)-4, IL-6, and tumor necrosis factor-alpha (TNF-α). It was additionally demonstrated that TJT suppresses HFD/DNFB-associated increase of the inflammation-related nuclear factor-kappa beta (NF-κB) and mitogen activated protein kinase. Moreover, significantly increased levels of hypoxia inducible factor-1 alpha (HIF-1α) protein was observed in CO group versus controls, an increase significantly down-regulated by TJT-treatment. These outcomes suggest that TJT may prove useful in clinical management of obesity-AD comorbidity treatment, an effect that may be due to regulation of HIF-1α expression.

Obesity-induced lymphatic dysfunction is reversible with weight loss

KEY POINTS

Obesity induces lymphatic leakiness, decreases initial lymphatic vessel density, impairs collecting vessel pumping and decreases transport of macromolecules. Obesity results in perilymphatic inducible nitric oxide synthase (iNOS) expression and accumulation of T cells and macrophages. Deleterious effects of obesity on the lymphatic system correlate with weight gain. Weight loss restores lymphatic function in obese animals and decreases perilymphatic iNOS and inflammatory cell accumulation.

ABSTRACT

Although clinical and experimental studies have shown that obesity results in lymphatic dysfunction, it remains unknown whether these changes are permanent or reversible with weight loss. In the current study, we used a mouse model of diet-induced obesity to identify putative cellular mechanisms of obesity-induced lymphatic dysfunction, determine whether there is a correlation between these deleterious effects and increasing weight gain, and finally examine whether lymphatic dysfunction is reversible with diet-induced weight loss. We report that obesity is negatively correlated with cutaneous lymphatic collecting vessel pumping rate (r = -0.9812, P < 0.0005) and initial lymphatic vessel density (r = -0.9449, P < 0.005). In addition, we show a significant positive correlation between weight gain and accumulation of perilymphatic inflammatory cells (r = 0.9872, P < 0.0005) and expression of inducible nitric oxide synthase (iNOS; r = 0.9986, P < 0.0001). Weight loss resulting from conversion to a normal chow diet for 8 weeks resulted in more than a 25% decrease in body weight and normalized cutaneous lymphatic collecting vessel pumping rate, lymphatic vessel density, lymphatic leakiness, and lymphatic macromolecule clearance (all P < 0.05). In addition, weight loss markedly decreased perilymphatic inflammation and iNOS expression. Taken together, our findings show that obesity is linearly correlated with lymphatic dysfunction, perilymphatic inflammation and iNOS expression, and that weight loss via dietary modification effectively reverses these deleterious effects.

Allomyrina dichotoma (Arthropoda: Insecta) larvae confer resistance to obesity in mice fed a high-fat diet

To clarify the anti-obesity effect of Allomyrina dichotoma larvae (ADL), we previously reported that ADL block adipocyte differentiation on 3T3-L1 cell lines through downregulation of transcription factors, such as peroxisome proliferator-activated receptor-γ (PPARG) and CCAAT/enhancer binding protein-α (CEBPA). In this study, we tested whether ADL prevent obesity in mice fed a high-fat diet (HFD) and further investigated the mechanism underlying the effects of ADL. All mice were maintained on a normal-fat diet (NFD) for 1 week and then assigned to one of five treatment groups: (1) NFD; (2) HFD; (3) HFD and 100 mg·kg(-1)·day(-1) ADL; (4) HFD and 3000 mg·kg(-1)·day(-1) ADL; or (5) HFD and 3000 mg·kg(-1)·day(-1) yerba mate (Ilex paraguariensis, positive control). ADL and yerba mate were administered orally daily. Mice were fed experimental diets and body weight was monitored weekly for 6 weeks. Our results indicated that ADL reduced body weight gain, organ weight and adipose tissue volume in a dose-dependent manner. Body weight gain was approximately 22.4% lower compared to mice fed only HFD, but the difference did not reach the level of statistical significance. Real-time polymerase chain reaction (PCR) analysis revealed that gene expression levels of PPARG, CEBPA and lipoprotein lipase (LPL) in the epididymal fat tissue of HFD-fed mice receiving 3000 mg·kg(-1)·day(-1) ADL were reduced by 12.4-, 25.7-, and 12.3-fold, respectively, compared to mice fed HFD only. Moreover, mice administered ADL had lower serum levels of triglycerides and leptin than HFD-fed mice that did not receive ADL. Taken together our results suggest that ADL and its constituent bioactive compounds hold potential for the treatment and prevention of obesity.

Prevention of diet-induced hyperlipidemia and obesity by caffeic acid in C57BL/6 mice through regulation of hepatic lipogenesis gene expression

This study investigated the influence of phenolic caffeic acid on obesity in mice fed a high fat diet and its underlying mechanisms base on adipose and hepatic lipid lipogenesis. C57BL/6 mice were fed a normal diet or a HFD (20% fat, w/w) with or without caffeic acid (0.02% and 0.08%, w/w) for 6 weeks. The effects of caffeic acid on hyperlipidemia, hyperglycemia, visceral fat accumulation, and related enzyme activities in HFD-mice are examined. The supplementation of caffeic acid significantly lowered body weight, visceral fat mass, plasma GOT and GPT levels, FAS activity, and free fatty acid compared to the HFD group. Caffeic acid also lowered triglyceride and cholesterol concentrations in plasma and liver. Furthermore, we showed that caffeic acid efficiently inhibited cholesterol biosynthesis as evidenced by 3-hydroxy-3-methylglutaryl CoA reductase in the liver. Caffeic acid supplementation suppressed the activity of lipogenesis via sterol regulatory element-binding protein 1 c and its target enzyme fatty acid synthase. In addition, caffeic acid resulted in increased phosphorylation of AMP-activated protein kinase and decreased acetyl carboxylase, a downstream target of AMPK, which are related to fatty acid β-oxidation in the liver. In conclusion, these results indicate that caffeic acid exhibits a significant potential as an antiobesity agent by suppression of lipogenic enzymes and hepatic lipid accumulation.

Immature Citrus sunki peel extract exhibits antiobesity effects by β-oxidation and lipolysis in high-fat diet-induced obese mice

The peel of Citrus sunki HORT. ex TANAKA has been widely used in traditional Asian medicine for the treatment of many diseases, including indigestion and bronchial asthma. In this study, we investigated the antiobesity activity of immature C. sunki peel extract (designated CSE) using high-fat diet (HFD)-induced obese C57BL/6 mice and mature 3T3-L1 adipocytes. In the animal study, body weight gain, adipose tissue weight, serum total cholesterol, and triglyceride in the CSE-administered group decreased significantly compared to the HFD group. Also, CSE supplementation reduced serum levels of glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, and lactate dehydrogenase. Moreover, it significantly decreased the accumulation of fatty droplets in liver tissue, suggesting a protective effect against HFD-induced hepatic steatosis. Dietary supplementation with CSE reversed the HFD-induced decrease in the phosphorylation levels of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), which are related to fatty acid β-oxidation, in the epididymal adipose tissue. Also, CSE increased AMPK and ACC phosphorylation in mature 3T3-L1 adipocytes. CSE also enhanced lipolysis by phosphorylation of cAMP-dependent protein kinase (PKA) and hormone-sensitive lipase (HSL) in mature 3T3-L1 adipocytes. These results suggest that CSE had an antiobesity effect via elevated β-oxidation and lipolysis in adipose tissue.

Impact of adiposity on immunological parameters

Studies evaluating immune function in obese humans and experimental animals indicate that the excess adiposity is associated with impaired in immune responses. Obesity is related to a higher rate of infections and to some types of cancer. Nutritional, metabolic and endocrine factors are implicated in the immunological changes. The adipose tissue directly produces substances with various functions related to immune system. Furthermore, some investigations suggest that certain types of weight reduction strategies can alter the immune function. Nevertheless, long-term studies should be carried out to address whether these changes positively affects the ability of these obese individuals to control infections and tumor development.

Feeding long-chain n-3 polyunsaturated fatty acids to obese leptin receptor-deficient JCR:LA- cp rats modifies immune function and lipid-raft fatty acid composition

Dietary EPA and DHA modulate immunity and thereby may improve the aberrant immune function in obese states. To determine the effects of feeding fish oil (FO) containing EPA and DHA on splenocyte phospholipid (PL) and lipid-raft fatty acid composition, phenotypes and cytokine production, 14-week-old obese, leptin receptor-deficient JCR:LA-cp rats (cp/cp; n 10) were randomised to one of three nutritionally adequate diets for 3 weeks: control (Ctl, 0 % EPA+DHA); low FO (LFO, 0.8 % (w/w) EPA+DHA); high FO (HFO, 1.4 % (w/w) EPA+DHA). Lean JCR:LA-cp (+/ - or +/+) rats (n 5) were fed the Ctl diet. Obese Ctl rats had a higher proportion of n-3 PUFA in splenocyte PL than lean rats fed the same diet (P < 0.05). The lower n-6:n-3 PUFA ratio of splenocyte PL was consistent with the lower mitogen-stimulated interferon (IFN)-gamma and IL-1beta production by cells from obese rats (P < 0.05). Obese rats fed the FO diet had lower mitogen-stimulated Th1 (IFN-gamma) and Th2 (IL-4) cytokine responses, but IL-2 production (concanavalin A; ConA) did not differ (P < 0.05). The HFO diet was more effective in lowering IL-1beta and increasing IL-10 production (ConA, P < 0.05). This lower IL-1beta production was accompanied by a lower proportion of major histocompatability complex class II-positive cells and a higher incorporation of DHA into lipid rafts. This is the first study to demonstrate impaired responses to mitogen stimulation and altered fatty acid incorporation into the membrane PL of JCR:LA-cp rats. Feeding FO lowered the ex vivo inflammatory response, without altering IL-2 production from ConA-stimulated splenocytes which may occur independent of leptin signalling.