What is all the fuss over the microbiome and immunity?

It is more than bugs, guts and tears

Abstract

The interaction of the gastrointestinal tract (GIT) and the microbiome (all the microbes in the lumen of the GIT) has become an increasing area of interest in terms of the effect on the immune system and overall health of cattle. Feed changes (including feed restriction) and dehydration (including water restriction), let alone the use antimicrobials, plus the normal stressors (weather, density, weaning, etc.) all effect both the mucosal epithelial (ME) cells of the GIT and the microbiome. The ME maintain a kill zone barrier to keep out pathogens in concert with the commensal microorganisms (microbiome) and other cells of the immune system. The microbiome functions best when it is in a stable condition resulting in immune homeostasis. Immunoregulation by the ME and microbiome results in the establishment of a mucosal firewall. Disruptions in the microbiome result in dysbiosis, which decreases the kill zone, allows leaky gut, and increases inflammation. This increased inflammation is seen as an important part of pathogenesis of infectious diseases of the GIT, respiratory, and reproductive tract. This inflammation often results in a “cytokine storm”- a perfect storm that involves a physiological component of the GIT along with microbiome changes in the gut (diet change), triggering systemic changes which result in enhanced disease. By improving mucosal barriers and the decreasing stressors, overall health and productivity of the cattle can be enhanced.