A comparative study of composite probiotic yogurt on LPS-induced acute inflammation and immunomodulation in mice

To elucidate the anti-inflammatory and immunomodulatory mechanisms of composite probiotic yogurt, this study established a lipopolysaccharide (LPS)-induced acute inflammation model using specific pathogen-free (SPF) male C57BL/6J mice to investigate the regulatory effects of different doses/forms of composite probiotic yogurt on inflammation and immunity inmice. Fifty mice were divided into 5 groups. After 4 weeks of oral intervention, all groups except the control group were intraperitoneally injected with LPS to induce the model. Indicators were measured 24 h after the LPS challenge. Results demonstrated that three interventions significantly suppressed serum expression of proinflammatory factors (TNF-α, IL-6,IFN-γ) and immunoglobulins (IgA, IgG) while promoting secretion of the anti-inflammatory factor IL-10. They maintained intestinal barrier integrity by regulating colonic cytokine levels and enhancing expression of tight junction proteins. Notably, Mix-Yogurt-L and Mix-Yogurt-H exhibited similar effects, suggesting a dose-saturation effect. The three interventions reduced serum alanine aminotransferase (ALT) levels and regulated the spleen GSH/GSSG ratio to varying degrees, alleviating secondary hepatic and splenic damage. Among them, the heat-inactivated group demonstrated outstanding efficacy in alleviating oxidative stress and Tissue damage in the spleen. This study demonstrates that different forms and doses of composite probiotic yogurt exhibit differentiated and complementary immunomodulatory functions. Thekey to achieving optimal immunomodulatory effects lies in the strategic selectionof the viable state and dosage of probiotic strains based on specific protective targets, rather than simply maximizing the number of viable bacteria. These findings provide a theoretical basis for the development of fermented dairy products.