How the Pediatric Microbiome has a Net Non-Inflammatory Effect on Children

Abstract Recent technological advances have precipitated a great deal of growth toward a better understanding of the human microbiome. This review will highlight some important recent findings in this area of research, specifically as it pertains to the pediatric population. Research has been conducted on the structural and functional capacity of the bacterial microbiome in the healthy state as well as in a variety of diseases. Emerging technologies derived largely from the Human Genome Project and the NIH-funded Human Microbiome Project (HMP) have been applied over the past few years to evaluate the interstitial microbiota. As the functional interactions between the host and its microbiome are analyzed in more detail, we are starting to better understand these interactions and how they impact overall health. A better understanding of the role of the microbiome in health and disease will be achieved with ongoing study to further characterize the functions of the microbiome and the host-microbe mechanistic interactions (Shreiner, Kao & Young, 2015). Keywords: Microbiome Microbiota Pediatric Inflammation Introduction The host/intestinal microbiota relationship is typically symbiotic in nature. It is an intricate system promoting health and modulating the immune response (Torrazza and Neu, 2011). The human microbiome is composed of bacteria, viruses, archaea, and eukaryotic microbes which contribute to metabolic functions, protect against pathogens, and educate the immune system. In recent years, the human microbiome has been found to play a significant role on the physiology of health and disease (Shreiner, Kao & Young, 2015). Discussion Functions of the intestinal microbiota The important roles of the intestinal microbiota include: metabolism, nutrition, immunological functions, and defense against pathogens. Thus, it is easy to understand that alterations in the microbiota can often lead to dysbiosis and disease in both infancy, as well as late in childhood (Table 1) (Torrazza and Neu, 2011). Intestinal bacterial play a key role in promoting the early development of the gut’s mucosal immune system, in terms of its physical components and function, as well as in continued role in later life. Gut-associated lymphoid tissue (GALT) is stimulated by bacteria to produce antibodies to pathogens. These antibodies then allow the immune system to recognize and fight against the harmful bacteria, without reacting against the helpful bacteria species. Toll-like receptors (TLRs) have been recently found to be expressed by gut bacteria via the various intestinal cell types, including the gut epithelium (Torrazza and Neu, 2011). TLRs are pattern recognition receptors that provide the intestine with the ability to discriminate between pathogenic and beneficial bacteria. Once these TLRs identify the pathogen that has crossed the mucosal barrier, they then trigger a set of responses that take action against the pathogen. Efforts are ongoing to better understand the effects of the intestinal microbiota specific to secretory IgA, TLRs, and other Pattern Recognition Receptors (PRR). The continued study of the presence and activation of the human microbiota will assist in better understanding the inflammatory cascade that leads to diseases such as necrotizing enterocolitis (NEC) or systemic inflammation associated with multiple organ dysfunction (Torrazza and Neu, 2011). The development of the gut microbiome is intrinsically vital to the maturation of the intestinal immune system. The function of the immune system is to maintain an anti-inflammatory state in the gut, especially during exposure to the considerable number of innocuous antigens from commensals, hormones, and food. In order for the immune system to effectively carry out its complex function, the diverse cell types must interact. The pattern of recognition that the intestinal flora has developed allows the “good” bacterial to not normally activate the immunological response. Oral tolerance is a phenomenon that bacteria can influence, which indicates that the immune system is less sensitive to an antigen once it has been ingested. This oral tolerance is mediated in part by the gastrointestinal immune system and in part by the liver. Oral tolerance can mean a reduction in the immune response, preventing an over-reactive immune response such as response seen in allergies and autoimmune disease (Torrazza and Neu, 2011). Table 1: Intestinal microbiota in the neonate (Torrazza and Neu, 2011) Healthy microbiota Alterations of microbiota or dysbiosis Early in the neonate Later in childhood Stimulates the GALT and antibody production Metabolize nutrients NEC (Necrotizing enterocolitis) Obesity Defense and barrier against pathogens Sepsis Diabetes Modulation of inflammatory response and intestinal permeability Diarrhea/Malnutrition Allergies, asthma, Metabolic syndrome Microbiota of the fetus and newborn An individual’s microbiome has been shown to be somewhat stable over...