Immunomodulatory Properties of Live and Thermally-Inactivated Food-Origin Lactic Acid Bacteria—In Vitro Studies

The study investigates the strain-specific immunomodulatory properties of live and thermally-inactivated (TI) lactic acid bacteria (LAB) derived from traditional Polish fermented foods, focusing on their potential as probiotics and postbiotics. LAB strains, known for their role in food fermentation, were assessed for their ability to influence cytokine production in THP-1 macrophages, maintain intestinal epithelial barrier integrity in Caco-2 monolayers, exhibit antioxidant activity, and produce specific organic acids and sugars. The research demonstrated that live LAB strains significantly upregulated the anti-inflammatory cytokine IL-10, particularly under inflammatory conditions, while TI strains exhibited notable antioxidant and anti-inflammatory properties. TI strains showed a greater ability to protect epithelial barrier function and reduce pro-inflammatory cytokine secretion than live strains, suggesting a promising role for postbiotics. The findings underscore the potential of LAB from fermented foods, demonstrating that postbiotic derivatives can differently influence inflammation compared to live bacteria, highlighting their potential as immune-enhancing agents, capable of modulating immune responses and offering therapeutic benefits against inflammation-related disorders. However, the limitations of in vitro models highlight the need for further in vivo and clinical studies to validate these effects and fully uncover the health benefits of these LAB strains for humans.