Lactobacillus crispatus mediates anti-inflammatory cytokine interleukin-10 induction in response to Chlamydia trachomatis infection in vitro.

Chlamydia trachomatis, a human pathogen, is a Gram-negative bacillus and a compulsory intracellular parasite. It is the most common cause of bacterial sexually transmitted infections in both industrialized and developing countries. In women, untreated genital infections can result in devastating consequences such as pelvic inflammatory disease, ectopic pregnancy, and even infertility. Lactobacillus crispatus is an important urogenital species that is routinely found in the vagina of healthy women. Lactobacilli are involved in the maintenance of the normal vaginal microbiota and their dominance in the vagina suggests that they play a crucial role in protecting the genitourinary tract against pathological conditions. Lactobacilli can act through the activation of the immune system, but C. trachomatis is able to effectively evade immune surveillance in some individuals. The aim of our study was to investigate the immunomodulatory efficacy of the potential probiotic strain L. crispatus in HeLa and J774 cells subjected to C. trachomatis infection by studying the expression of the inflammatory cytokines IL-6, IL-8, TNF-α and IL-10. Our results demonstrated, firstly, the lack of any cytotoxic effect on the epithelial cells and macrophages when treated with L. crispatus and its supernatant; in addition, L. crispatus and its supernatant inhibited C. trachomatis adhesion and infectivity in human epithelial cells and macrophages. Our study then showed that L. crispatus and its supernatant reduced IL-6, IL-8 and TNF-α production in C. trachomatis-infected HeLa and J774 cells. In contrast, a significant upregulation of the IL-10 expression in HeLa and J774 cells by L. crispatus and supernatant was also demonstrated. Our data indicate that L. crispatus specifically enhances the production of the IL-10 anti-inflammatory cytokine in contrast to the inhibitory effect of L. crispatus on the pro-inflammatory cytokines.

Antimicrobial effect of natural polyphenols with or without antibiotics on Chlamydia pneumoniae infection in vitro.

Chlamydia pneumoniae is a human pathogen that causes multiple diseases worldwide. Despite appropriate therapy with antichlamydial antibiotics, chronic exacerbated diseases often occur and lead to serious sequelae. The use of the macrolide clarithromycin and the fluoroquinolone ofloxacin has improved the treatment of chlamydial infection, but therapy failure is still a major problem. In this work, we studied the pretreatment with natural polyphenols and subsequent treatment with clarithromycin or ofloxacin. The phenolic compounds resveratrol and quercetin improved the antichlamydial effect of clarithromycin and ofloxacin. In particular, resveratrol at 40 µM and quercetin at 20 µM exhibited significant growth inhibition on C. pneumoniae in presence of clarithromycin or ofloxacin compared to controls. In addition, we demonstrated that both resveratrol and quercetin decreased IL-17 and IL-23 production in a time-dependent manner in C. pneumoniae-infected cells. The results showed a particularly strong inhibition of the IL-23 levels released with combined treatment of resveratrol or quercetin and ofloxacin or clarithromycin, suggesting that the combined treatment may afford a synergistic effect in controlling Chlamydia infections.

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

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 ß-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 ß-defensin 2 and 3, thus suggesting a probiotic potential of this Lactobacillus as an anti-infective agent against C. albicans.

Lactobacillus plantarum reduces Streptococcus pyogenes virulence by modulating the IL-17, IL-23 and Toll-like receptor 2/4 expressions in human epithelial cells.

Streptococcus pyogenes is a common colonizer of the mucosal layers in the mouth, nose, and pharynx but it is also a major Gram-positive human pathogen that causes infections ranging from pharyngitis to severe systemic diseases. The lactobacilli colonize the oral tracts and are known to protect against colonization by many pathogens. Epithelial cells participate in the innate host defense by expressing a variety of proinflammatory cytokines and TLRs in the interaction with microorganisms. The potentially probiotic strain Lactobacillus plantarum was investigated for its capacity to influence the innate immune response of HEp-2 and A549 epithelial cells to S. pyogenes infection. In both epithelial cell types, pre-treatment with L. plantarum showed inhibition of S. pyogenes growth and a greater decrease in IL-17 and IL-23 levels compared to the control. Pre-treatment with the anti-TLR2/4 antibody abolished the inhibitory effects of L. plantarum on IL-17 and IL-23 production following S. pyogenes infection, indicating that L. plantarum downregulates TLR2/4-dependent IL-17 and IL-23 production. Overall, our findings suggest that in epithelial cell cultures with S. pyogenes, cytokine responses are modulated by the presence of L. plantarum through the induction of TLR2/TLR4.