Immunomodulatory effects of <i>Lactiplantibacillus paraplantarum</i> BAL-28-ITTG paraprobiotics and postbiotics

Intracellular paraprobiotics (PP) and postbiotics (PB) derived from lactic acid bacteria are being increasingly explored as alternatives to conventional probiotics. We examined the immunomodulatory effects of PP and PB obtained from Lactiplantibacillus paraplantarum BAL-28-ITTG using human intestinal epithelial (HIEC-6) and dendritic (NHDC) cell lines. PP and PB were obtained by thermal and thermal-sonication treatments and characterized by scanning electron microscopy, fatty acid profiling (GC-MS), and SDS‒PAGE. Cellular responses were assessed through metabolic activity (MTT), catalase/caspase activity, and multiplex cytokine quantification. Statistical analyses were performed using ANOVA and appropriate post hoc tests. PP and PB did not induce cytotoxic effects in HIEC-6 or NHDC cells. PP treatment increased cellular metabolic activity in a dose-dependent manner and modulated the secretion of cytokines, particularly IL-1β, IL-4, IL-6, IL-10, and TNF-α. Interestingly, PP-2 enhanced cytokine production under basal conditions while attenuating cytokine responses in lipopolysaccharide-stimulated cultures. These findings demonstrate that BAL-28-ITTG-derived paraprobiotics and postbiotics modulate cytokine responses in human intestinal and immune cell models in vitro, warranting further investigation to determine their biological relevance in vivo.