Selection of New Probiotics for Endometrial Health

Abstract

Microbiota is a crucial player in gynecologic health, in which bacteria can shift to a dysbiotic state triggering a pathogenic process. Based on an ecological understanding of the problem, the aim of this study is to select a potential probiotic strain to improve female reproductive tract based on its capacity to initially lower pH and to promote the reduction of pathogenic bacteria. Based on this rationale, strain <i>Lactobacillus rhamnosus</i> BPL005 was initially selected for its capacity to reduce <i>in vitro</i> pH levels and produce organic acids. Subsequently, strain <i>L. rhamnosus</i> BPL005 (CECT 8800) was demonstrated to have a protective role on endometrial infections in an <i>in vitro</i> model of bacterial colonization of primary endometrial epithelial cells with <i>Atopobium vaginae, Gardnerella vaginalis, Propionibacterium acnes</i>, and <i>Streptococcus agalactiae</i>. In this model, BPL005 when co-cultured with those pathogens was shown to lower pH and to produce organic acids, being lactic acid the most relevant. The co-cultivation of strain <i>L. rhamnosus</i> BPL005 with tested reference pathogens produced a significant reduction in <i>P. acnes</i> and <i>St. agalactiae</i> levels and a non-significant reduction in <i>A. vaginae</i> and <i>G. vaginalis</i>. The colonization of <i>L. rhamnosus</i> BPL005 in the culture decreased IL-6, IL-8, and MCP-1, heightened in the presence of pathogens, and increased IL-1RA and IL-1 beta. Finally, safety was evaluated showing no signs of cytotoxicity, irritation in vaginal tests, or allergic contact dermatitis potential through the Local Lymph Node Assay. Overall, these results show the potential of <i>L. rhamnosus</i> BPL005 strain as a probiotic in gynecological health.