Bacterial vaginosis (BV), the most common genital infection in reproductive-aged women, is associated with increased risk\nof sexually transmitted infections. Its etiology remains unclear, especially the role of Gardnerella (G.) vaginalis, an anaerobic\nbacterium characteristic of the BV-alteration of the vaginal ecosystem. In the genital mucosa, dendritic cells (DCs) sense bacteria\nof the microenvironment via receptors and then orchestrate the immune response by induction of different T cell subtypes. We\ninvestigated the interactions between G. vaginalis and humanmonocyte-derivedDCs using a wide range of bacterial concentrations\n(multiplicity of infection from0.01 to 100), and the effects of this pathogen on PHA-induced lymphocyte proliferation. As observed\nby electron microscopy and cytometry, G. vaginalis reduced the internalization ability of DCs by forming extracellular clusters and\ninduced neither DC maturation, nor DC secretion of cytokines, except at the highest dose with a very early DC maturation state.\nThe same profile was observed on lymphocytes with significant increases of proliferation and cytokine secretion only at the highest\nbacterial concentration. Our findings indicate that G. vaginalis possesses slight immune-stimulating activities against DCs and T\ncells, reflecting thus a defective inflammatory response and giving rise to the atypical, non- or low-grade, inflammatory clinical\ndisease profile.
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