Immunomodulatory Properties of Multi-Strain Postbiotics on Human CD14 Monocytes.

The ability of probiotics, comprising live microbiota, to modulate the composition of intestinal microbiomes has been connected to modulation of the central nervous system (Gut-Brain axis), neuroendocrine system (Gut-Skin axis), and immune response (Gut-Immune axis). Less information is known regarding the ability of postbiotics (cell wall components and secreted metabolites derived from live organisms) to regulate host immunity. In the present study, we tested postbiotics comprising single strains of bacteria and yeast ( 16axg, 18fx, 16mxg) as well as combinations of multiple strains for their ability to stimulate cytokine production by human CD14 monocytes. We quantified cytokine gene and protein expression levels in monocytes following stimulation with postbiotics. Both heat-killed and stimulated naïve monocytes without significant differences between them. Heat-killed stimulated less cytokine production compared to postbiotic bacteria at the same concentration. Interestingly, the addition of heat-killed yeast to heat-killed and resulted in an enhancement of immune stimulation. Thus, heat-killed postbiotics have immune-modulating potential, particularly when bacteria and yeast are combined. This approach may hold promise for developing targeted interventions that can be fine-tuned to modulate host immune response with beneficial health impact.