Effect of iron on the probiotic properties of the vaginal isolate Lactobacillus jensenii CECT 4306

The vaginal microbiota of healthy, fertile women is dominated by lactobacilli. As a defence mechanism, these bacteria produce H₂O₂ to discourage colonization of the vagina by undesirable micro-organisms. In particular, Lactobacillus jensenii CECT 4306 is a strong producer of H₂O₂ and has been found to protect itself from the bactericidal effects of this compound through the activity of extracellular peroxidases. However, this peroxidase activity is dependent on the presence of Fe(3+), which is found in elevated concentrations in the vaginal mucosa as a consequence of the menstrual discharge. The aim of the present work was to evaluate whether Fe(3+) is able to modulate other potential probiotic properties of strain 4306. We found that Fe(3+) enhances the adhesion of L. jensenii CECT 4306 to mucin and to HT-29 and HT-29 MTX cells, and, in addition, improves the anti-inflammatory profile, as judged by an increase in the ratio of IL-10/IL-12p70 that were secreted by macrophages. A comparison of total, secreted and surface proteins produced in the presence and absence of Fe(3+) revealed significant differences in the concentration of the moonlighting protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In conclusion, Fe(3+) seems to improve the probiotic characteristics of L. jensenii CECT 4306, and future research of the interactions of this strain with its vaginal environment may reveal further information about different aspects of its probiotic potential.