Vaccines, Microbiota and Immunonutrition: Food for Thought

Abstract

Vaccines are among the most effective health measures and have contributed to eradicating some diseases. Despite being very effective, response rates are low in some individuals. Different factors have been proposed to explain why some people are not as responsive as others, but what appears to be of critical importance is the presence of a healthy functioning immune system. In this respect, a key factor in modulating the immune system, both in its adaptive and innate components, is the microbiota. While microbiota can be modulated in different ways (i.e., antibiotics, probiotics, prebiotics), an effective and somewhat obvious mechanism is via nutrition. The science of nutrients and their therapeutic application is called immunonutrition, and it is increasingly being considered in several conditions. Our review will focus on the importance of nutrition and microbiota modulation in promoting a healthy immune system while also discussing the overall impact on vaccination response.

Keywords: antioxidant system; immunonutrition; inflammation; microbiota; vaccines.

Figure 1

Immune response in eubiosis condition and in immuno-nutrition. Gut homeostasis is maintained through the cooperation between microbiota and several micronutrients, acting in a synergic and powerful way. Eubiosis is maintained by the specific immuno-nutrition (e.g., Vitamin E, Vitamin D, Vitamin C, Omega-3 Fatty acid as EPA and DHA, Se, Zn, Cu and Nucleotides). On the other hand, gut microbiota in eubiosis condition can cooperate with the immune system to preserve the intestinal barrier integrity. Mucosal APCs and associated lymphoid tissue can promote vaccine response, through antigen response and binding Tregs and B lymphocytes via IL-1 and IFN-α. Tregs, activated also through Vitamin E and D, can block Th17 lymphocytes and the related cytokines storm (i.e., IL-17) and suppress inflammation. At the same time, nucleotides, Se and Vitamin C can stimulate B cells to become plasma cells, and produce antigen-specific antibodies. Inside the B cell, the main intracellular signalling pathway promoted by NF-kB pathway related to inflammation is blocked via RXR/PPAR-γ heterodimer. The intracellular defence system, sustained by ROS, is balanced through SOD1 and GPx activity (with binding of Cu, Zn and Se, respectively). EPA and DHA can prevent the lipid bilayer oxidation in cooperation with Vitamin E. Vitamin D and can promote with RXR the anti-oxidant and anti-inflammation gene expression through the binding on VDREs. Abbreviation: Eicosapentaenoic acid (EPA); Docosahexaenoic acid (DHA); Selenium (Se); Zinc (Zn); Copper (Cu); Antigen presenting macrophages/dendritic cells (APCs); Interleukine-1 (IL-1); interferon alpha (IFN-α); Interleukine-17 (IL-17); Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); Retinoid X receptor (RXR); Peroxisome proliferator-activated receptor (PPAR-γ); Superoxide dismutase 1 (SOD-1); Glutathione Peroxidase (GPx); Vitamin D Responsive Elements (VDREs).