Mechanisms of adherence of a probiotic Lactobacillus strain during and after in vivo assessment in ulcerative colitis patients

In a pilot-scale, open-label study to determine the ability of well-characterized probiotic Lactobacillus salivarius UCC118 cells to adhere to human epithelial cells in situ , the bacterial strain was administered to ulcerative colitis patients at approximately 109 CFU/day for 12 days. Microbiological analysis of biopsy specimens demonstrated that the ingested bacteria effectively adhered to both inflamed and non-inflamed mucosa of the large bowel in significant numbers. In previous reports, we have described the ability of the lactobacilli to adhere to enterocytic epithelial cells in vitro. In this study, we found that the bacteria adhered at higher levels to differentiated rather than undifferentiated epithelial monolayers; and that stationary phase lactobacilli were found to adhere to eukaryotic HT-29 and Caco-2 epithelial cells at greater levels than log phase bacterial cells. Pretreatment of the Lactobacillus cells with proteolytic enzymes abolished attachment, indicating the potential involvement of surface/exposed protein(s) as bacterial adhesin(s). SDS-PAGE (denaturing) techniques determined that the proteolytic treatment resulted in degradation of a cell wall-associated protein of approximately 84 kDa. The proteinaceous factor was purified by both anion-exchange chromatography and by gel extraction after SDS-PAGE electrophoresis, and under in vitro assay conditions proved capable of adherence and significant inhibition of bacterial attachment to enterocytic epithelial cells. Key words: probiotic, Lactobacillus, adhesin, cell-borne, proteinaceous