Vaginal Lactic Acid Bacteria Isolated from Healthy Algerian Women Display Distinct Immunomodulatory Profiles Across Macrophage Models

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The vaginal microbiota contributes to mucosal immune homeostasis, yet the immunomodulatory properties of individual vaginal lactic acid bacteria (LAB) strains remain poorly characterized. In this study, eight LAB strains previously isolated from healthy Algerian women and selected based on their probiotic-related properties were evaluated for their capacity to modulate macrophage immune responses. Seven Lactiplantibacillus plantarum strains (N1, N2, N7, N11, N17, 87JG8, and 87BG2) and one Limosilactobacillus fermentum strain (70BJ2) were initially screened using porcine alveolar macrophages (PAM cells) under basal conditions and following lipopolysaccharide (LPS) challenge. Distinct strain-dependent cytokine profiles were observed. Hierarchical clustering separated the strains into two major groups: N1, N2, N7, and N11 were characterized mainly by stronger inflammatory responses, whereas N17, 87BG2, 87JG8, and 70BJ2 displayed comparatively lower inflammatory responses together with enhanced IL-6 and IL-27 expression at later time points. Based on these profiles, N17, 87JG8, and 70BJ2 were selected for further characterization in porcine intestinal macrophages (IPIM cells) and RAW 264.7 murine macrophages (RAW cells). In IPIM cells, 70BJ2 reduced LPS-induced TNF-α and IL-6 expression, while N17 enhanced IL-10 and IL-27 expression following LPS challenge. In RAW cells, N17 and 87JG8 enhanced several inflammatory and chemokine responses, whereas all three strains increased IFN-γ, IL-12, CSF3, IL-10, and IL-27, with 70BJ2 inducing the strongest IL-10 and IL-27 responses and uniquely increasing CSF2. Overall, vaginal LAB displayed distinct strain- and macrophage-dependent immunomodulatory profiles rather than uniformly suppressing or enhancing LPS-induced inflammation. Among the selected strains, Lmb. fermentum 70BJ2 exhibited particularly prominent regulatory properties across macrophage models. These findings extend the functional characterization of vaginal LAB and support their strain-level evaluation for the identification of candidate immunobiotics capable of modulating mucosal immune responses.