Immunomodulatory Potential of Weissella cibaria in Aged C57BL/6J Mice

Aging is associated with distinct changes in immune cells and a decline in immune function, leading to increased susceptibility to infection and reduced responses to vaccination. Certain strains of lactic acid bacteria exert beneficial effects on the immune system. Previously, we reported that Weissella cibaria JW15 isolated from kimchi possesses immune stimulatory activity in vitro. In the present study, we further investigated whether oral administration of JW15 improves immune function in aged mice. Eighteen-month-old female mice were administered JW15 daily at low (JW15-L; $1{\times}10^8CFU/mouse$) or high dosage (JW15-H; $1{\times}10^9CFU/mouse$), or with Lactobacillus rhamnosus GG (LGG) using oral gavage. Two-month-old female mice were included as healthy young mice. After 4 weeks, the mice were euthanized and immune profiles were analyzed using whole blood and spleen. In complete blood count analysis, the numbers of white and red blood cells were significantly increased in the JW15-L group compared with those in the old mouse (OM) control group. In addition, administration of either JW15 of LGG resulted in higher numbers of splenocytes in comparison with the OM group. Furthermore, proliferative potentials were higher in all probiotic groups than OM. Cytokines such as IFN-${\gamma}$ and IL-6 were secreted at higher levels in splenocytes isolated from JW15-fed mice than in OM control mice. Similarly, mRNA expression of various cytokines was altered in the JW15 groups. Collectively, these results suggest that JW15 supplementation induces immunomodulatory effects in aged mice and indicate JW15 as a potential probiotic strain to improve immune function in aged animals.