Effect of the administration of probiotic fermented milk and its bacterial free supernatant on the systemic immunity and intestinal microbiota of protein-energy malnourished mice

NOVOTNY NUÑEZ IVANNA; DE MORENO DE LEBLANC ALEJANDRA; PERDIGÓN GABRIELA; CARMUEGA, ESTEBAN; WEILL, RICARDO; MALDONADO GALDEANO CAROLINA

San Miguel de Tucumán

Simposio; III Simposio Internacional de Bacterias Lácticas. II Encuentro red BAL Argentina.; 2009

The protein-energy malnutrition (PEM) is caused by the deficient ingestion of nutrients. It is related with diminution in the body growth and development, with depression of the immune system and increase of infections. Previous studies showed that the histology of the small intestine and thymus was affected in malnourished mice and  the administration of a probiotic fermented milk (PFM) during the re-nutrition period improved these histological alterations. It was also demonstrated, using the same PEM model, that the PFM exerted an adjuvant effect on the systemic and intestinal immunity. The objectives of the present work were deepen in the mechanism by which PFM or its bacterial free supernatant (BFS) stimulate the systemic immunity analyzing the phagocytic activity of macrophages isolated from spleen. We evaluated the effect of both products on the intestinal microbiota. Mice were divided in 5 groups. G1: normal control with balanced food ad-libitum and water. G2: PEM control with restriction of 25% of food. G3: Malnourished mice re-nourished with milk. G4: Malnourished mice re-nourished with PFM. G5: Malnourished mice re-nourished with BFS. Mice were sacrificed previous to the re-nourish (day 0) and 5 and 15 days after it. Spleens were removed to isolate macrophages and the phagocytic activity of them was evaluated. At the same periods of time the large intestine was removed, homogenized and plated in different growth media: Mac Conkey for enterobacteria, MRS for lactobacillus, RCA for total anaerobic bacteria and RCA containing LiCl pH 5,5 for bifidobacteria. Phagocytic activity of spleen macrophages increased after 5 days of re-nutrition in the three test groups (G3, G4, G5). The group re-nourished with BFS showed the highest percentage of phagocytosis  at this time point, but not differences between control and test groups in the last sample (15 days of re-nutrition) were found. The most remarkable effect was observed in the study of the intestinal microbiota with a significant increase of bifidobacteria count in mice that received PFM in the both samples (5 and 15 days) compared to the control and the other test groups. The mice given BFS increased bifidobacteria count compared to the control. This increase was higher in the last sample (15 days) than 5 days post re-nourished. However the counts for bifidobacteria were significantly lower than the counts obtained in mice that received PFM. The results obtained suggest that the PFM had different effect that the one obtained with the BFS. On the systemic immunity, it was observed a response more regulated in mice given PFM where, the phagocytic activity of spleen macrophages was lower than in mice that received BFS. This effect could be related to the increases of the bifidobacteria population obtained after PFM administration.