Lactobacillus crispatus inhibits the infectivity of Chlamydia trachomatis elementary bodies, in vitro study.

Paola Nardini,Antonella Marangoni,Beatrice Vitali,Luca Laghi,Claudio Foschi,Carola Parolin,Roberto Cevenini,Rogers Alberto Ñahui Palomino

doi:10.1038/srep29024

Abstract

Lactobacillus species dominate the vaginal microbiota of healthy reproductive-age women and protect the genitourinary tract from the attack of several infectious agents. Chlamydia trachomatis, a leading cause of sexually transmitted disease worldwide, can induce severe sequelae, i.e. pelvic inflammatory disease, infertility and ectopic pregnancy. In the present study we investigated the interference of Lactobacillus crispatus, L. gasseri and L. vaginalis, known to be dominant species in the vaginal microbiome, with the infection process of C. trachomatis. Lactobacilli exerted a strong inhibitory effect on Chlamydia infectivity mainly through the action of secreted metabolites in a concentration/pH dependent mode. Short contact times were the most effective in the inhibition, suggesting a protective role of lactobacilli in the early steps of Chlamydia infection. The best anti-Chlamydia profile was shown by L. crispatus species. In order to delineate metabolic profiles related to anti-Chlamydia activity, Lactobacillus supernatants were analysed by 1H-NMR. Production of lactate and acidification of the vaginal environment seemed to be crucial for the activity, in addition to the consumption of the carbonate source represented by glucose. The main conclusion of this study is that high concentrations of L. crispatus inhibit infectivity of C. trachomatis in vitro.

Highlights

In order to investigate the potential antagonist role of vaginal lactobacilli against C. trachomatis, we evaluated the ability of seventeen Lactobacillus strains to inactivate infectivity of EBs, before they interact with cellular host receptors
These lactobacilli were previously isolated from vaginal swabs of healthy premenopausal women[25] and belong to three species highly represented in the vaginal habitat: Lactobacillus crispatus (BC1-BC8), Lactobacillus gasseri (BC9-BC14) and Lactobacillus vaginalis (BC15-BC17) (Table 1)
After the challenge with Lactobacillus cell free supernatants (CFS), the capacity of C. trachomatis EBs to infect HeLa cells was assessed by immunofluorescence

Summary

Introduction

Species L. crispatus L. crispatus L. crispatus L. crispatus L. crispatus L. crispatus L. crispatus L. crispatus L. gasseri L. gasseri L. gasseri L. gasseri L. gasseri L. gasseri L. vaginalis L. vaginalis L. vaginalis. Strain BC1 BC2 BC3 BC4 BC5 BC6 BC7 BC8 BC9 BC10 BC11 BC12 BC13 BC14 BC15 BC16 BC17. Within these vacuoles, named inclusions, EBs differentiate into RBs after several transformations. Unlike EBs, RBs are larger, less compacted, metabolically active and able to divide by binary fission. In C. trachomatis, around 18 h post-infection, RBs resulting by binary fission differentiate back into EBs that will afterwards be expelled from the cell, either by exocytosis or cellular lysis 48–72 h post-infection[21]

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