LACTIN-V (Lactobacillus crispatus CTV-05) leads to microbial and immune modulation in pregnant women at risk of spontaneous preterm birth:FLIP-1 study

Abstract Preterm birth (PTB) remains a leading cause of neonatal morbidity and mortality, with no new preventive therapeutics introduced since the 1970s. Evidence increasingly implicates adverse vaginal microbiome-immune interactions in its aetiology. We report the effects of the live biotherapeutic, Lactobacillus crispatus CTV-05 (LACTIN-V), in an observational study of pregnant individuals at high-risk of PTB (n=61). LACTIN-V treatment was associated with a shift towards L. crispatus-dominated microbiota, which was sustained at eight weeks post-cessation and confirmed to be viable CTV-05. Engraftment of LACTIN-V was accompanied by significant reductions in cervicovaginal fluid concentrations of IL-1β, IL-6, C3a, C3b/iC3b, C4, and Factor H, changes not seen in untreated time-matched controls. We also highlight the utility of metabolic profiling by Desorption Electrospray Ionisation in identifying individuals most likely to benefit from treatment and for assessing therapeutic response. The reduced PTB rate observed with LACTIN-V administration supports its use in preventing microbiome–immune–mediated PTB.