Anti-LFA-1 antibody postpones T-cell receptor triggering while preserving generation of regulatory T cells in T-cell receptor anti-HY transgenic mice

Structural modifications of ICAM-1 cyclic peptides to improve the activity to inhibit heterotypic adhesion of T cells

Lymphocyte function-associated antigen-1 (LFA-1)/intercellular adhesion molecule-1 (ICAM-1) interaction plays an important role in the formation of the immunological synapse between T cells and antigen-presenting cells. Blocking of LFA-1/ICAM-1 interactions has been shown to suppress the progression of autoimmune diseases. cIBR peptide (cyclo(1,12)PenPRGGSVLVTGC) inhibits ICAM-1/LFA-1 interaction by binding to the I-domain of LFA-1. To increase the bioactivity of cIBR peptide, we systemically modified the structure of the peptide by (i) replacing the Pen residue at the N-terminus with Cys, (ii) cyclization using amide bond formation between Lys-Glu side chains, and (iii) reducing the peptide size by eliminating the C-terminal residue. We found that the activity of cIBR peptide was not affected by replacing Phe with Cys. Peptide cyclization by forming the Lys-Glu amide bond also increased the activity of cIBR peptide, presumably due to the resistance of the amide bond to the reducing nature of glutathione in plasma. We also found that a reduced derivative of cIBR with eight residues (cyclo(1,8)CPRGGSVC) has a bioactivity similar to that of the larger cIBR peptides. Our findings suggest that, by systemically modifying the structure of cIBR peptide, the biological activity of these derivatives can be optimized for future use to inhibit T-cell adhesion in in vivo models of autoimmune diseases.

Suppression of established experimental autoimmune uveitis by anti-LFA-1alpha Ab

PURPOSE

To identify costimulatory molecules that are important in the effector phase of experimental autoimmune uveitis (EAU).

METHODS

EAU was induced in C57BL/6 (B6) mice by transfer of activated T cells specific for the interphotoreceptor-binding protein (IRBP) 1-20 peptide. The animals were then treated with and without anti-leukocyte function associated antigen (LFA)-1alpha mAb, at day 0 or 10 (disease onset) after T-cell transfer. Clinical signs of inflammation, ocular histology, and infiltrated inflammatory cells in the eye were compared. The primary and secondary proliferative responses of uveitogenic CD4 and CD8 T cells were tested after treatment with costimulatory blockers in vivo and in vitro. Moreover, the abilities of uveitogenic T cell trafficking and their interaction with retinal astrocytes were examined.

RESULTS

Anti-LFA-1alpha Abs caused significant suppression of disease when administered either at the time of effector uveitogenic T cell transfer or at disease onset. Studies of the mechanisms by which anti-LFA-1alpha Ab inhibits the effector phase of uveitis demonstrated that it blocks multiple pathogenic events of uveitis mediated by IRBP-specific uveitogenic T cells, including the activation of T cells outside and inside the eye and the trafficking of activated autoreactive T cells into the inflammatory site. In addition, Ab treatment selectively suppressed the activation and expansion of pathogenic, but not regulatory, T cells in vivo.

CONCLUSIONS

Anti-LFA-1alpha Abs are potent inhibitors of established autoimmune uveitis and that such treatment may be applicable not only for the prevention, but also the treatment, of T-cell-mediated autoimmune diseases.