Pathogen exclusion and immunomodulatory effects of the S-layer protein of Lactobacillus acidophilus

FINA MARTÍN, JOAQUINA; PRADO ACOSTA, MARIANO; RUZAL, SANDRA; BARQUERO, ANDREA

Mar del Plata

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigación Bioquímica (SAIB); 2015

SAIB

Lactobacilli are found in human intestine and some strains are considered probiotic. Surface layer (S-layer) protein constitute in some species their outermost cell envelope and have been considered to be involved in modulating the host immune system and inhibit pathogenic bacteria adhesion which has recently gained attention as a way to prevent infection. Here, we investigate L.acidophilus ATCC4356 adherence to epithelial cell lines and ability to interfere with Pseudomonas aeruginosa by plate counts. The S-layer modulation of cytokines production in the murine macrophage cell line J774A.1 and Caco-2 cells was also studied by ELISA and qRT-PCR.Interaction with mucins, immobilized on a PVDF membrane was assayed.Lactobacilli showed lower adherence to lung A549 cells than intestinal Caco-2 cells ranging from 0.5 to 10% depending on the number of input bacteria and day-old Caco-2 monolayers. We found that S-layer protein was also able to produce pathogen exclusion against Pseudomas when added purified; however, live lactobacilli with or without S-layer did not. Moreover, in macrophages co-incubated for 24 h with purified S-layer, IL-6 and TNF-α secretion was significantly increased. Likewise, purified S-layer led to an elevated expression peak of TNF-α; at 4h of incubation in Caco-2 cells. Interaction with mucins was detected with both protein and cells.