Chronic progression of autoimmune disease is accompanied by the acquisition of autoreactivity to new self-determinants. Recent evidence indicates that this process, commonly referred to as determinant spreading, may be pathogenic for chronicity. Our studies on experimental autoimmune encephalomyelitis (EAE), a murine model widely used in multiple sclerosis (MS) studies, have shown that determinant spreading develops as a predictable sequential cascade of neo-autoimmunity during progression to chronic disease. By 7-8 weeks after immunization of (SWR x SJL)F1 mice with the immunodominant myelin proteolipid protein determinant (PLP 139-151), splenocytes consistently respond to the immunodominant myelin basic protein determinant (MBP 87-99). In the present study, we directly address the pathogenicity of neo-autoimmunity resulting from endogenous self-priming during the course of disease. Our results indicate that T cells responding to the spreading MBP 87-99 determinant produce a proinflammatory cytokine profile consistent with type 1 helper T cells (Th1) cells. In addition, splenocytes activated to the spreading MBP 87-99 determinant consistently transfer acute EAE in naive recipients even when T cells reactive to the priming PLP 139-151 immunogen are eliminated by bromodeoxyuridine (BUdR)-mediated photolysis.

The effects of controlled release on immune response to an immunomodulating peptide were evaluated in a murine experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). The peptide, Ac-PLP-BPI-NH(2)-2 (Ac-HSLGKWLGHPDKF-(AcpGAcpGAcp)(2)-ITDGEATDSG-NH(2); Ac = acetyl, Acp = epsilon aminocaproic acid) was designed to suppress T-cell activation in response to PLP(139-151), an antigenic peptide in MS. Poly-lactide-co-glycolide (PLGA) microparticles containing Ac-PLP-BPI-NH(2)-2 (8+/-4 microm, 1.4+/-0.2% (w/w)) were prepared by a powder-in oil-in water emulsion-solvent evaporation method, sterilized and administered subcutaneously (s.c.) to SJL/J (H-2(s)) mice in which EAE had been induced by immunization with PLP(139-151). Treatment groups received Ac-PLP-BPI-NH(2)-2: (i) in solution by repeated i.v. or s.c. injection, (ii) in solution co-administered with blank PLGA microparticles, (iii) in solution co-administered with Ac-PLP-BPI-NH(2)-2 loaded microparticles, and (iv) as Ac-PLP-BPI-NH(2)-2 loaded microparticles. Administration of Ac-PLP-BPI-NH(2)-2 as an s.c. solution produced clinical scores and maintenance of body weight comparable to i.v. solution, but with reduced overall survival, presumably due to anaphylaxis.

The objective was to optimize and evaluate the in vivo activities of our novel bifunctional peptide inhibitor (BPI), which alters immune response in autoimmune diseases by modulating the immunological synapse formation. Previously, we have designed PLP-BPI and GAD-BPI by conjugating myelin proteolipid protein (PLP)(139-151) and glutamic acid decarboxylase (GAD)(208-217), respectively, with CD11a(237-246) via a spacer peptide. PLP-BPI and GAD-BPI suppressed the disease progression in experimental autoimmune encephalomyelitis (EAE) and in type-1 diabetes, respectively. In this study, various PLP-BPI derivatives were synthesized and evaluated in the EAE model. Intravenous injections of PLP-BPI derivatives prevented the disease progression more efficiently than did unmodified PLP-BPI. Production of IL-17, a potent proinflammatory cytokine found commonly among MS patients, was significantly low in Ac-PLP-BPI-NH(2)-2-treated mice. Treatment given after the disease onset could dramatically ameliorate the disease. BPI induced anaphylactic responses at a lower incidence than PLP(139-151). In conclusion, PLP-BPI derivatives can effectively suppress the disease severity and morbidity of EAE by post-onset therapeutic treatment as well as prophylactic use.