Vaginal microbiota and immune response in pregnant women after intake of probiotics

The vaginal microbiota of healthy women consists of a wide variety of anaerobic and aerobic bacteria dominated by the genus Lactobacillus. The activity of lactobacilli is essential to protect women from genital infections and to maintain the natural healthy balance of the vaginal ecosystem. This role is particularly important during pregnancy because vaginal infection is one of the most important mechanisms for preterm birth and perinatal complications. In the present study, we characterized the impact of a dietary supplementation with the probiotic VSL#3, a mixture of Lactobacillus, Bifidobacterium and Streptococcus strains, on the vaginal microbial ecology of healthy women during late pregnancy. PCR-DGGE profiling revealed the ability of the probiotic VSL#3 to modulate the vaginal microbiota without compromising the inter-individual species variability. qPCR results suggested a role of the probiotic product in counteracting the decrease of Lactobacillus and the increase of Atopobium, that physiologically occur in late pregnancy. The modulation of the vaginal microbiota was associated with significant changes in vaginal cytokine secretion. In particular, the physiological decrease of the anti-inflammatory cytokines IL-4 and IL-10 was not observed in women treated with VSL#3. In addition, the probiotic consumption induced the decrease of the pro-inflammatory chemokine Eotaxin, showing a global anti-inflammatory effect on the vaginal immunity.