Lactobacillus crispatus modulates epithelial cell defense against Candida albicans through Toll-like receptors 2 and 4, interleukin 8 and human β-defensins 2 and 3.

Abstract

Lactobacilli are members of the normal mucosal microflora of most animals. Probiotic bacteria, such as Lactobacilli, play a major role in the maintenance of a healthy urogenital tract by preventing the colonization of pathogenic bacteria. The potentially probiotic strain Lactobacillus crispatus (ATCC 33820) was investigated for its capacity to influence the innate immune response of HeLa epithelial cells to Candida albicans. In addition, its capacity to modulate the toll-like receptor (TLR) expression of HeLa cells was investigated by Western blot. When HeLa cells were pre-treated with the L. crispatus and infected with C. albicans, the interleukin-8 levels were significantly lower than without pre-treatment. Also, the effect of L. crispatus on innate immunity was enhanced by its capacity to increase the effect of human β-defensin 3 against C. albicans growth. Pre-treating HeLa cells with L. crispatus attenuated the yeast's virulence, as demonstrated by its reduced adhesion and growth on human epithelial cells. Our findings indicated, also, that after contact with C. albicans, epithelial cells expressed more TLR2/4 than non-infected cells, whereas pre-treatment with L. crispatus downregulated the TLR2/4 expression by epithelial cells stimulated with C. albicans. In conclusion, our results show that L. crispatus promotes epithelial cell defense against C. albicans infection through the involvement of TLR2/4, IL-8 and human β-defensin 2 and 3, thus suggesting a probiotic potential of this Lactobacillus as an anti-infective agent against C. albicans.

Keywords: Candida albicans; Defensins; Lactobacillus crispatus; Toll-like receptors.