Submitted to: Nutrition and Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2012
Publication Date: 3/27/2013
Citation: Wang, J., Vanegas, S.M., Du, X., Noble, T., Zingg, J.A., Meydani, M., Meydani, S.N., Wu, D. 2013. Caloric Restriction reduces inflammation and improves T cell-mediated immune response in obese mice but concomitant consumption of curcumin/piperine adds no further benefit. Nutrition and Metabolism. 10:29. Interpretive Summary: Obesity is associated with low-grade inflammation and weakened response of the immune system. Restricting food intake, known as caloric restriction (CR), has been shown to inhibit inflammation and to improve the function of the immune system. Curcumin, which is a naturally occurring ingredient in the spice turmeric, is claimed to have anti-obesity and anti-inflammation properties. Since piperine, a compound present in the spice pepper, can enhance the effectiveness of curcumin, we sought to learn if combinations of curcumin and piperine might boost CR’s beneficial effect on the immune system and inflammation when obesity is induced with a high fat diet. We used a mouse model of high fat diet-induced obesity since this is currently the best parallels for human obesity. Our study demonstrated that CR has a beneficial effect on diet-induced obesity since it suppressed inflammation and improved immune function in obese mice. Contrary to our assumption, however, supplementing the CR diet with curcumin and/or piperine provided no additional benefit; instead, they actually diminished CR’s effect on certain immune system responses. Although CR is an effective approach to reducing inflammatory response and improving immune function, the presence of other food components such as those in spices could modify the effect of CR. Thus diet quality is important in the context of calorie restriction.
Technical Abstract: Obesity is associated with low-grade inflammation and impaired immune response. Caloric restriction (CR) has been shown to inhibit inflammatory response and enhance cell-mediated immune function. Curcumin, the bioactive phenolic component of turmeric spice, is proposed to have anti-obesity and anti-inflammation properties while piperine, another bioactive phenolic compound present in pepper spice, can enhance the bioavailability and efficacy of curcumin. This study sought to determine if curcumin/piperine could potentiate CR’s beneficial effect on immune and inflammatory responses in diet-induced obesity. Mice were fed a high-fat diet (HFD) for 22-wk followed by a CR diet (10 percent for 5-wk and then 20 percent for additional 33-wk), in the presence or absence of cucumin and/or piperine. Results showed that compared to HFD control group, all CR mice, regardless of the presence of curcumin and/or piperine, had fewer total spleen cells but a higher percentage of CD4 T cells. Additionally, they demonstrated lower production of pro-inflammatory cytokines IL-1beta and TNFalpha, and lipid pro-inflammatory mediator prostaglandin E2, as well as trend toward lower IL-6. Mice with CR alone had higher splenocyte proliferation and IL-2 production, but this effect of CR was blunted by spice supplementation. CR alone or in combination with cucumin and/or piperine consumption had no effect on production of cytokines IL-4, IL-10, IFN-gamma, TGF-beta, and IL-17, or the proportion of different CD4 T cell subsets. In conclusion, CR reduces inflammatory response and enhances T cell-mediated function in HFD fed mice, but the presence of curcumin and/or piperine does not amplify CR’s beneficial effects.