Disruption of CD40/CD40-Ligand Interactions in a Retinal Autoimmunity Model Results in Protection without Tolerance

Abstract

We examined the role of CD40/CD40L interactions on the development of experimental autoimmune uveoretinitis (EAU), a cell-mediated, Th1-driven autoimmune disease that serves as a model for autoimmune uveitis in humans. EAU-susceptible B10.RIII mice immunized with the retinal autoantigen interphotoreceptor retinoid binding protein in CFA and treated with anti-CD40L Ab (MR1) had reduced incidence and severity of disease. Real-time PCR analysis revealed that the innate and adaptive responses of protected mice were reduced, without an obvious shift toward a Th2 cytokine profile. In contrast to some other reports, no evidence was found for regulatory cells in adoptive transfer experiments. To determine whether CD40L blockade resulted in long-term tolerance, mice protected by treatment with MR1 Ab were rechallenged for uveitis after circulating MR1 Ab levels dropped below the detection limit of ELISA. MR1-treated mice developed severe EAU and strong cellular responses to interphotoreceptor retinoid binding protein, comparable to those of control mice. These responses were higher than in mice that had not received the primary immunization concurrently with anti-CD40L treatment. We conclude that 1) CD40/CD40L interaction is required for EAU and its disruption prevents disease development; 2) CD40L blockade inhibits the innate response to immunization and reduces priming, but does not result in immune deviation; and 3) protection is dependent on persistence of anti-CD40L Abs, and long-term tolerance is not induced. Furthermore, immunological memory develops under cover of CD40L blockade causing enhanced responses upon rechallenge. Taken together, our data suggest that ongoing CD40/CD40L blockade might be required to maintain a therapeutic effect against uveitis.

Abrogation of Anti-Retinal Autoimmunity in IL-10 Transgenic Mice Due to Reduced T Cell Priming and Inhibition of Disease Effector Mechanisms

“…For Ag-specific lymphocyte proliferation and cytokine production, spleen and draining lymph nodes (LNs; inguinal and iliac) of individual mice (4 -5 per group) were collected 3 wk after immunization. Cells were pooled within the group and were stimulated with graded concentrations of Ag in triplicate cultures of 0.2 ml, essentially as described (22). Proliferation of LN cells was determined by [ 3 H]thymidine incorporation.…”

CD40 Mediates Retinal Inflammation and Neurovascular Degeneration

“…CD40 is a regulator of inflammatory disorders, and studies using nonocular cells revealed that the CD40 induces NOS2 and COX-2, triggers chemokine production (MCP-1, IL-8, and MIP-2), and up-regulates ICAM-1 (14 -19). Immunization with retinal Ag results in the generation of a T cell response in peripheral lymphoid tissues, a process that is dependent on CD40 and leads to T cell-mediated experimental autoimmune uveoretinitis (20,21). However, whether CD40 in the retina is involved in other retinopathies is unknown.…”

An Essential Role for Death Receptor 3 in Experimental Autoimmune Uveoretinitis

“…CD40L blockade inhibited innate responses to immunization and reduced priming. 13 Fas (gld; TNFRSF6) or FasL (lpr) deficient mice developed lower incidence and severity following EAU induction compared with wild-type controls. The underlying mechanisms for this resistance were not defined, but bone marrow chimaeras demonstrated that normal expression of Fas and FasL on hemopoietic cells of the immune system, but not on ocular tissue, was required for the induction.…”

“…Perhaps of greatest significance, all of our findings highlight the differences between DR3 and other members of the TNFR superfamily in the induction of ocular inflammation. Apart from the role of TNFR1 described above, Fas, 11 CD40L, 13 and 4-1BBL 14 have also been implicated in the pathogenesis of EAU. Mice deficient in 4-1BB (TNFRSF9) are susceptible to EAU, however, treatment with agonistic anti-4-1BB mAb alleviated disease through the expansion of IFNγ-producing CD11c + CD8 + T cells.…”

“…Spleens were removed and splenocytes were extracted, seeded at 1 × 10 6 /mL, and stimulated with a range of concentrations of IRBP [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] (0.01-1 µg/mL) for 72 h. For the last 16 h, cells were pulsed with 0.5 µCi 3 [H]thymidine (Amersham Biosciences) and uptake was measured using a beta counter (Wallac, Perkinelmer). PBS/2% DMSO and 2.5 µg/ mL Con A (Concavalin A, Sigma) were used as negative and positive controls, respectively.…”