Impact of Probiotic Treatment on the Systemic Inflammatory Response in Animals Subjected to Chronic Social Stress in the Model of Spontaneous Aggression (MSA)

Chronic social stress promotes behavioral, neuroendocrine, and immune alterations and is associated with dysregulation of the inflammatory response and cytokine production. Communication among the nervous, endocrine, and immune systems can be influenced by the gut-brain axis, while alterations in the gut microbiota may potentiate the systemic inflammatory response and interfere with neuroimmune communication. Alterations in this axis may disrupt intestinal homeostasis and contribute to systemic inflammation. In this context, probiotics may contribute to the modulation of the inflammatory response associated with stress. This study aimed to evaluate the plasma inflammatory cytokine profile in mice subjected to chronic social stress in the Model of Spontaneous Aggression (MSA). Male Swiss Webster mice were subjected to the grouping and regrouping protocol of the MSA and classified as non-regrouped (NR), harmonic (Har), attacked (AgD), and aggressive (AgR) animals. Animals were treated with Enterogermina® (Bacillus clausii) via gavage for six weeks. At week 16, following behavioral categorization, blood samples were collected to obtain plasma. The cytokine profile was determined by flow cytometry. Preliminary results from control animals showed significant differences in cytokine concentrations among MSA categories. IL-10 showed higher concentrations in AgR compared with the other groups. IL-17A differed between NR and Har. TNF-α and IFN-γ showed higher concentrations in Har compared with AgD and AgR, whereas IL-6 was higher in Har and AgD compared with NR. These results demonstrate that chronic social stress in the MSA is associated with alterations in the systemic inflammatory profile, highlighting distinct responses among behavioral profiles. These findings reinforce the relevance of the model for investigating the relationship between stress, inflammation, and immune responses and establish a basis for evaluating the modulation of this profile by probiotic treatment.