66. Environmental conditions perceived by the brain alter CD8+ T cells responses

• Published in: Brain, behavior, and immunity Vol. 40; p. e20
• Main Authors: Canali, M.M, Soria, J.A, Guyot, M, Murris, E, Daudlarian, D, Chabry, J, Mougneau, E, Blancou, P, Glaichenhaus, N
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2014
• Subjects: Allergy and Immunology; Psychiatry
• ISSN: 0889-1591; 1090-2139
• DOI: 10.1016/j.bbi.2014.06.086

We are interested in elucidating how the brain controls the immune system. To this aim, we have established and validated an environmental enriched (EE) paradigm in which C57BL/6 mice experience higher levels of sensory, motor, social, and cognitive stimuli, compared to animals housed in a standard environment (SE). In agreement with previous studies, we found that EE increased hippocampal neurogenesis and synaptogenesis, decreased anxiety and increases exploratory activity. EE housing did not result in gross alterations in the frequency of neutrophils, dendritic cells (DC), macrophages, T cells and B lymphocytes in immunologically naïve animals. In contrast, upon immunization with ovalbumin (OVA), the number of OVA-specific CD8+ T cells in spleen was higher in EE mice compared to SE mice. Because the activation of CD8+ T cells is known to be dependent on antigen cross-presentation by lymphoid CD8+ DCs, we compared the phenotype of these DCs in SE and EE mice and found that lymphoid CD8+ DCs from EE mice expressed reduced levels of PD-L1, a molecule that regulate the activation of CD8+ T cells. PDL-1 down-regulation in EE mice was associated with altered serum levels of corticosterone, therefore providing a possible link between the environment, the Hypothalamo–Pituitary–Adrenal (HPA) axis and DC function. Altogether, our results suggest that environment conditions could impact adaptive immune responses and therefore the ability of the host to deal with pathogens.