Safety and immunostimulatory potential evaluation of Limosilactobacillus fermentum isolated from millet-based fermented food in mice.

The present study assessed the safety and immunostimulatory potential of phytase-producing Limosilactobacillus fermentum MS005 at doses of 7, 9 and 11 log CFU/mouse/d in male Swiss albino mice (n = 5) during a 28-day subacute toxicity study. To further delineate immunostimulatory responses, an additional group of mice received 9 log CFU/mouse/d (n = 5). MS005 administration did not induce significant alteration in body weight, organ weight, hematobiochemical end-points, or hepatic antioxidant levels, confirming its safety profile. Notably, MS005 reduced the liver lipid peroxidation by 1.6-fold and preserved the epithelial barrier integrity post-pathogenic E. coli challenge, as indicated by elevated expression of Zo-1, Claudin-4 and Muc-2, key biomarkers of intestinal epithelial barrier integrity. Immunomodulatory assessment revealed a significant increase in splenic lymphocyte proliferation (2.3-fold), NK cell activity (1.59-fold), and macrophage phagocytosis (1.3-fold), alongside an insignificant increase in IL-10 expression at a dose of 9 log CFU/mouse/d. Histopathological analysis showed normal architecture of liver, spleen, ileum and colon in MS005-treated mice, with increased villi length and density along with lymphocyte infiltration within Peyer's patches in the 9 log CFU/mouse/d group relative to the control mice. Overall, the findings highlight the safety and immunostimulatory efficacy of Lmb. fermentum MS005, supporting its potential use as a functional probiotic for improving the gut barrier function, host immunity and iron bioavailability.