Although this is still an open question, data in the literature suggest a more direct link between the intestinal microbiota composition and the development of immune reactions to particular vaccine antigens
Although this is still an open question, data in the literature suggest a more direct link between the intestinal microbiota composition and the development of immune reactions to particular vaccine antigens. mammalian immune system. Despite all the improved attention within the interface between the microbiota and sponsor immune reactions, it is still unclear whether these commensal bacteria impact the effectiveness of vaccines. Due to its effect in the development of immune function, both in the gut and additional organs, it is sensible to consider the intestinal microbiota will significantly impact how individuals respond to vaccine antigens[3],[4]. For example, segmented filamentous bacteria present in the intestinal microbiota have been shown to induce FACD maturation of intestinal T cell adaptive functions[5]. Moreover, it has been shown the intestinal microbiota exerts a serious effect on the rate of metabolism of certain medicines and toxins[1],[6], and this may also indicate that oral vaccines could be differentially processed by the body depending on variations in microbial areas between individuals. Hence, the microbiota could be an underappreciated yet important player to consider in the development of vaccines, and also may help clarify some of the discrepancies observed in vaccine effectiveness in different populations around the world. Medical trials screening the efficacy of oral vaccines against polio, rotavirus, and cholera have showed a lower immunogenicity of these vaccines in PF-04971729 individuals from developing countries when compared to individuals from the designed world[7][11]. Medical trials for any killed oral cholera vaccine in Swedish and Nicaraguan children have also demonstrated blunted antibody reactions in Nicaraguan children compared to Swedish children[11]. In a study screening a live cholera oral vaccine, Lagos and colleagues[12]shown that excessive bacterial growth in the small intestine of children in less developed countries might contribute to the low antibody response to the vaccine. Different vaccine strains ofShigella flexnerialso showed differential safety on individuals from developing countries. In a study screening Bangladeshi adults and children, no significant immune response to this vaccine was mounted, even though same antigen was reactogenic in North American individuals[13]. Completely, these data spotlight that individuals from different parts of the world can mount different immune reactions to the same vaccine. Several hypotheses that may clarify this phenomenon exist. For instance, socioeconomic conditions, nutritional status, sponsor genetics, and earlier exposure to related microorganisms are some of the elements that could contribute to the disparity in the vaccine efficacies in different populations. However, one poorly explored possibility is that the composition of the intestinal microbiota of these individuals may also be a determining element of vaccine effectiveness. In a way analogous to the hygiene hypothesis[14], which claims that reduced exposure to microorganisms at an early age may lead to improved susceptibility to allergies, it is possible the gut microbiota of individuals with an increase of exposure to microorganisms (and therefore antigens) make them more tolerant to vaccination, becoming unable to mount a proper PF-04971729 response compared to individuals living in better socioeconomic conditions. Discerning the effects of genetic and environmental factors on vaccine effectiveness is definitely a demanding task. Large clinical tests involving individuals from different areas of the world will likely be required to shed light on whether the blunt immune reactions to some of the oral vaccines pointed out herein are a result of genetic factors or environmental variations, such as the gut microbial community. Studies including immigrant volunteers could be useful in dealing with this issue by providing PF-04971729 a clear variation between the effects of genetics and the environment. Although this is still an open query, data in the literature suggest a more direct link between the intestinal microbiota composition and the development of immune reactions to particular vaccine antigens. For.