The intestine and its microflora are partners for the protection of the host: report on the Danone Symposium “The Intelligent Intestine,” held in Paris, June 14, 2002

Abstract

The intestine is an extremely complex living system that participates in the protection of the host through a strong defense against aggressions from the external environment. This defensive task is based on 3 constituents that are in permanent contact and dialog with each other: the microflora, mucosal barrier, and local immune system. We review herein current knowledge about these important functions. The gut microflora play a major role against exogenous bacteria through colonization resistance, but the mechanism of action is not yet established, although it is linked to the bacteria colonizing the gut. This colonization involves bacteria-bacteria dialog, bacteria-mucins interactions, and bacteria-colonocytes cross-talk associated with environmental factors. The intestinal mucosa is a cellular barrier and the main site of interaction with foreign substances and exogenous microorganisms. It is a complex physicochemical structure consisting of a mucous layer linked to cellular and stromal components that participate in the defense of the host through mucosal blood flow, mucosal secretions, epithelial cell functionals, surface hydrophobicity, and defensin production. The intestine is the primary immune organ of the body represented by the gut-associated lymphoid tissue through innate and acquired immunity. This immune system can tolerate dietary antigens and the gut-colonizing bacteria and recognizes and rejects enteropathogenic microorganisms that may challenge the body's defenses. In cooperation with these endogenous barriers, some in-transit bacteria, such as probiotics, can act as partners of the defense system of the intestine.

Effect of the probiotic 'Lactina' on some biological parameters and nonspecific resistance in neonatal pigs

“…The obvious beneficial effect of Lactina on complement activity at 5 d of age supports the view that piglets intestinal flora at that age is not stable and it is known that the quality of resident flora has a crucial effect on the intestinal immune system (Bourlioux et al, 2003).…”

Campylobacter jejuni adhere to and invade chicken intestinal epithelial cells in vitro

“…The present view is that the intestinal microbiota are maintained in a dynamic relationship with the host involving a complex 'trialogue' between micro-organism, epithelium and mucosal immune system (Bourlioux et al, 2003;Falk et al, 1998). Recent work has started to uncover some important bacterial factors necessary for successful avian colonization by C. jejuni (Hendrixson & DiRita, 2004;Jones et al, 2004;Karlyshev et al, 2004;Nachamkin et al, 1993).…”

Histoplanimetrical Study on the Spatial Relationship of Distribution of Indigenous Bacteria with Mucosal Lymphatic Follicles in Alimentary Tract of Rat

“…The microflora consists of 10 14 bacteria of 400 different species that generate intense metabolic activity and play important physiologic roles in the adult human alimentary tract [3,21]. In general, the amount of bacteria in the alimentary tract increases toward the distal end, reaching up to 10 12 /g bacteria in feces [10,15] during the transit time of the chyme, which is 4-6 hr in the small intestine and 54-56 hr in the large intestine of healthy human [9].…”