Behavioral Conditioning of Immune Responses with Cyclosporine A in a Murine Model of Experimental Autoimmune Uveitis

Objective: We examined the role of behavioral conditioning of immune responses with cyclosporine A (CsA) on the development of Th1/Th17-driven experimental autoimmune uveoretinitis (EAU). Methods: Mice received a 0.2% w/v saccharin solution as conditioned stimulus combined with CsA (20 mg/kg) in 6 association trials at 72-h intervals. For evocation periods, conditioned mice were reexposed to saccharin, whereas the conditioned but not reexposed group received water only. Animals were immunized with human inter-photoreceptor- retinoid-binding protein peptide 161-180 (hIRBP p161-180) peptide in complete Freund adjuvant (CFA) and a concomitant injection of pertussis toxin. Results: In naive mice subjected to the behavioral conditioning regi- men, mitogen-induced interleukin (IL)-2 production was decreased in conditioned mice compared to conditioned but not reexposed animals. Incidence and severity of EAU were not significantly lower in behaviorally conditioned and immunized mice. ELISA analysis of splenocytes revealed a reduced interferon (IFN)-gamma/IL-17 ratio in CsA-treated, conditioned but not reexposed, and conditioned animals. The adoptive transfer of antigen-specific splenocytes from animals behaviorally conditioned with CsA to naive mice decreased the severity of EAU in recipient mice compared to the control group. In vitro activation of splenocytes isolated from immunized mice with agonists targeting TLR2 and NOD2 together with beta(2)-adrenergic activation (induced by epinephrine, norepinephrine, or salbutamol) resulted in decreased IFN-gamma but increased IL-17 immune responses. The beta(2)-adrenergic antagonist propranolol could restore IFN-gamma production, whereas only the norepinephrine-induced increase in IL-17 production was abrogated. Conclusions: We conclude that CsA conditioning in the EAU model mitigates Th1 but enhances Th17 immune responses, and does not ameliorate disease. The results imply that in EAU the mechanism of immune conditioning interacts with CFA components during active immunization, most likely via the TLR2/NOD2 pathway, and induces differentiation of Th17 cells that drive autoimmune diseases. (C) 2017 S. Karger AG, Basel