Immunorestorative effects of Limosilactobacillus reuteri LR6 in protein-energy malnourished mice under pathogen and allergen challenge.

Protein-energy malnutrition (PEM) is the most severe form of malnutrition, often linked with impaired immunity and increased susceptibility to infections. In this study, mice were initially fed a normal semi-synthetic well-nourished diet for one week and then divided into five groups. The animals in Group C (control) continued on the normal well-nourished diet, while Groups M (malnourished), SM (skim milk), PFM (probiotic fermented milk), and BS (probiotic suspension) received a protein- and energy-restricted diet (2% casein, 315.2 kcal) until PEM was established. Later, the groups SM, PFM and BS were fed with well-renourished diet supplemented with skim milk, probiotic fermented milk and probiotic suspension during renourishment period of 7 days. However, group C and group M continued with well-nourished and restricted diet respectively. Each group was then challenged with a pathogen or allergen in separate trials. Post-sacrifice samples were analyzed for immunological, microbiological, and molecular markers. Mice fed Limosilactobacillus reuteri LR6, especially in fermented form (PFM group), showed improved body weight and spleen index. Enhanced phagocytic activity, maturation, and function of bone marrow-derived dendritic cells were also observed. Moreover, PFM-fed mice revealed increased serum IgA and anti-OVA IgG levels, together with reduced IgE levels, indicating immune system restoration. Probiotic administration favorably modulated gene expression levels of Toll-like receptors (TLR2 and TLR4), suggesting reinforcement of intestinal barrier function. In conclusion, our findings highlighted the immunorestorative potential of L. reuteri LR6, thereby supporting its use as a functional adjunct in nutritional rehabilitation strategies towards immune homeostasis during PEM.