Practical Formulation-Associated Immunomodulatory Responses of Lacticaseibacillus paracasei Yb in an Ovalbumin-Induced Allergic Airway Inflammation Mouse Model

This study evaluated the immunomodulatory activity of live Lacticaseibacillus paracasei Yb in vitro and compared response patterns associated with practical L. paracasei Yb formulation formats in an ovalbumin (OVA)-induced allergic airway inflammation mouse model. In vitro, live L. paracasei Yb increased TNF-α production in RAW 264.7 macrophages at 2 × 106 to 5 × 107 CFU/mL, increased IL-1β only at 5 × 107 CFU/mL, and increased IL-10 at 1 × 107 and 5 × 107 CFU/mL. In splenocytes, L. paracasei Yb increased TNF-α, IFN-γ, and IL-10 compared with untreated controls, although these responses did not show a simple concentration-dependent pattern. In vivo, BALB/c mice received fresh L. paracasei Yb yogurt (YG), freeze-dried yogurt (YG-FD), or bacterial powder (BP) for 53 days. Compared with the OVA-sensitized Negative control group, YG and BP did not significantly reduce serum total IgE or OVA-specific IgE, and airway responsiveness and BALF eosinophils showed limited or non-significant changes. In contrast, YG and BP significantly reduced lung inflammation scores (Negative control, 6.86 ± 1.57; YG, 5.13 ± 0.83; BP, 4.50 ± 0.55) and ConA-stimulated splenocyte IL-4 secretion (Negative control, 1168.43 ± 553.34 pg/mL; YG, 589.84 ± 233.54 pg/mL; BP, 472.28 ± 186.44 pg/mL). These findings suggest that practical formulation conditions may shape selected preclinical immunological and histopathological responses to L. paracasei Yb. Further studies incorporating CFU-matched dosing, probiotic-free yogurt controls, and mechanistic validation are required before clinical relevance in asthma can be inferred.