“Intestinal Microbiota. Interactions with the epithelial cells"

PÉREZ CHAIA, ADRIANA; ZÁRATE, GABRIELA; LORENZO PISARELLO, MARÍA JOSÉ

Tucumán - Argentina

Simposio; III Simposio Internacional de Bacterias Lácticas. II Encuentro Red BAL - Mesa Redonda III. Bacterias Lácticas Probióticas; 2009

CERELA - CONICET

Presentación en mesa Redonda III - Bacterias Lácticas Probióticas Resumen de la Presentación: The microbial genera that inhabit the intestine are responsible of metabolic conversions which necessarily affect the functions of the epithelium with consequences on the host health and nutrition. The microbiota participates actively in the degradation of complex nutrients of the diet, carbohydrate fermentation and metabolism of xenobiotics. Some populations have the ability to capture toxic compounds and potential carcinogens, linking them to specific structures located on the cell wall, and prevent harmful effects on the epithelial cells. On the other hand, the main products of the bacterial fermentation of carbohydrates are short chain fatty acids (SCFA) that contributes to the control of pathogens in the intestine, absorption of electrolytes and water from the lumen, nutrition of the colonocytes and influences the cellular cycle and the mucus synthesis and secretion. There is increasing evidence that many human diseases are related to lifestyle. The stress and reduced physical activity of modern life and the high consumption of processed foods, antinutritional factors and chemicals are risk factors of different diseases that may be in some extent prevented by the activity of a stable microbiota. Attempts have been made to manipulate the microbiota composition and improve the host health status by promoting the development of some beneficial bacteria. For this purpose, dietary supplementation with non-digestible carbohydrates has been extensively evaluated. In the intestinal ecosystem, a limited number of bacteria have the ability to utilize specific glycoside hydrolases to breakdown complex carbohydrates but they release more simple molecules that are, in turns, fermented by a higher number of microorganisms. Therefore, fermentation of non-digestible carbohydrates conduces to a global change in the ecosystem with impact on the production of SCFA and on intestinal functions that are affected by the concentration of these organic acids. The microbiota composition, fermentation profile and development of the intestinal epithelium may be also modified by consumption of SCFA producers.  The complex interactions that exist among the different populations are important factors that determine the total number of microorganisms and the ratio of the different populations in such a way that the increment on one genus necessarily conduces to the reduction of other. Therefore, the introduction of dairy propionibacteria in the ecosystem, a propionic and acetic acid producer, conduces to the inhibition of genera that utilise similar substrates or metabolise sugars by similar pathways. The development these bacteria in the intestinal environment may contribute to the control of anaerobic genera like Bacteroides and Clostridium which include species frequently associated to human diseases and risk factors of cancer and reinforce the structural barrier of the intestinal epithelium and the mucus layer. An additional benefit of the consumption of dairy propionibacteria is the removal of some dietary lectins, toxic for the intestinal epithelial cells. This behaviour may avoid changes in the architecture and physiological function of the intestinal mucosa induced by the diet.