Phenotypic Differences in Primary Murine Microglia Treated with NOD1, NOD2, and NOD1/2 Agonists.

The purpose of the study was studying the influence of different NOD agonists on the morphological phenotype of primary murine microglia and to examine their influence on characteristic cytokines. Primary CD11b-positive cells were isolated from the brain of neonatal mice. The microglial phenotype of the cells was examined by ionized calcium-binding adapter molecule (Iba)1 staining. After14 days in culture, these cells were stimulated by iE-DAP, L18-MDP, or M-TriDAP as NOD1, NOD2, and NOD1/2 agonists, respectively. The cellular morphology was recorded and compared to the phenotype of cells cultured in medium alone or after LPS stimulation. The cells developed a specific phenotype only after treatment with the NOD2 agonist L18-MDP. These cells were characterized by straight extensions carrying tiny spikes and had a high ramification index. This was in sharp contrast to all other treatments, which always resulted in an amoeboid phenotype typically shown by activated microglia in vivo and by cultured microglia in vitro. The staining intensity of IL-6 and TNF-α did not reveal any clear difference independent of the NOD agonist treatment. In contrast, an increased staining intensity was observed for IL-10 after L18-MDP treatment. The NOD2 agonist L18-MDP induced a morphologically distinct phenotype characterized by microspike-decorated dendritiform extensions and a high degree of ramification in primary murine microglia. Increased ramification index and elevated staining intensity of anti-inflammatory IL-10 as hallmarks suggest that a M2-like phenotype of microglia was induced.

Novel everolimus-loaded nanocarriers for topical treatment of murine experimental autoimmune uveoretinitis (EAU).

In the present study, therapeutic effect of topically applied everolimus (EV)-loaded methoxy-poly(ethylene-glycol)-hexyl substituted poly (lactic acid) (mPEGhexPLA) nanocarriers on experimental autoimmune uveoretinitis (EAU) were investigated. EAU was induced in B10.RIII mice via immunization with human interphotoreceptor retinoid-binding protein peptide 161-180 (hIRBPp161-180) in complete Freund's adjuvant. Everolimus-loaded mPEGhexPLA (EV/mPEGhexPLA) nanocarriers were prepared by using a solvent evaporation method. On days 12-21 postimmunization (p.i.), the right eyes were treated five times daily either with 10 µl of 0.5% everolimus formulation or PBS (control). The EAU score of the eyes was determined histologically. On day 21 p.i., the peripheral immune responses were measured in serum, cervical lymph nodes (LN), and spleens via hIRBPp161-180-specific serum antibodies, cytokine secretion (ELISA), lymphocyte proliferation, and FoxP3+ regulatory T cells (Treg; flow cytometry). Compared to the PBS-treated mice, unilateral topical everolimus treatment significantly reduced EAU severity in both eyes (p < .05). The treatment reduced the antigen (Ag)-specific hIRBPp161-180-induced proliferation (p < .05), IL-2, IL-17, and IFN-γ secretion from cells isolated from the left and right cervical LN (p < .05). Under everolimus treatment, IL-10 secretion and CD4+CD25+FoxP3+ Treg frequency from cervical LN were enhanced. The proliferative response and cytokine secretion as well as the frequency of splenic Treg were almost unchanged. Topical administration of an everolimus formulation improved EAU in both eyes. The effect might also be related to systemic immunosuppressive effects, as several systemic cellular immune responses were influenced.

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 interphotoreceptor-retinoid-binding protein peptide 161-180 (hIRBPp161-180) peptide in complete Freund adjuvant (CFA) and a concomitant injection of pertussis toxin. RESULTS: In naïve mice subjected to the behavioral conditioning regimen, 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)-γ/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 naïve 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 ß2-adrenergic activation (induced by epinephrine, norepinephrine, or salbutamol) resulted in decreased IFN-γ but increased IL-17 immune responses. The ß2-adrenergic antagonist propranolol could restore IFN-γ 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.