Exploring the Probiotic Potential and Immunomodulatory Capacity of Lactococcus lactis NCDO 2118 Against Bacterial...

Probiotic microorganisms capable of modulating the immune response and exerting antimicrobial activity represent promising tools in host-pathogen control. This study aimed to evaluate the probiotic potential and immunomodulatory capacity of Lactococcus lactis NCDO 2118 (L. lactis NCDO 2118) and the cell-free supernatant (CFS) against pathogenic bacteria and Trypanosoma cruzi (T. cruzi). We assessed acid and bile salt resistance, adhesion to abiotic surfaces, inhibition of bacterial growth, cytotoxicity, and immunomodulatory activity in vitro using RAW 264.7, THP-1, and BMDC cell lines. In vivo, C57BL/6 mice were treated orally to investigate systemic immunomodulatory responses. The strain exhibited tolerance to pH 3.5 and 0.3% bile salts, also showed adhesion capacity on polystyrene surface, and inhibited the growth of Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, and Enterococcus gallinarum. Neither the bacterium nor its CFS exhibited cytotoxic effects. In vitro, assays showed modulation of cytokine production, especially increased IL-10 in BMDCs (bone marrow-derived dendritic cells) and reduced IL-4 in T. cruzi-infected macrophages, while in vivo assays revealed increased IL-10 levels in spleens and TNF-α in livers of treated mice. These findings highlight L. lactis NCDO 2118 as a promising probiotic candidate with dual antimicrobial and immunomodulatory actions. To our knowledge, this is the first study to demonstrate the ability of L. lactis NCDO 2118 to modulate cytokine profiles and antiparasitic responses relevant to Chagas disease.