Inhibition of LFA‐1/ICAM‐1 and VLA‐4/VCAM‐1 as a therapeutic approach to inflammation and autoimmune diseases

Abstract

This review focuses on providing insights into the structural basis and clinical relevance of LFA‐1 and VLA‐4 inhibition by peptides and small molecules as adhesion‐based therapeutic strategies for inflammation and autoimmune diseases. Interactions of cell adhesion molecules (CAM) play central roles in mediating immune and inflammatory responses. Leukocyte function‐associated antigen (LFA‐1, α_Lβ₂, and CD11a/CD18) and very late antigen (VLA‐4, α₄β₁, and CD49d/CD29) are members of integrin‐type CAM that are predominantly involved in leukocyte trafficking and extravasation. LFA‐1 is exclusively expressed on leukocytes and interacts with its ligands ICAM‐1, ‐2, and ‐3 to promote a variety of homotypic and heterotypic cell adhesion events required for normal and pathologic functions of the immune systems. VLA‐4 is expressed mainly on lymphocyte, monocytes, and eosinophils, but is not found on neutrophils. VLA‐4 interacts with its ligands VCAM‐1 and fibronectin (FN) CS1 during chronic inflammatory diseases, such as rheumatoid arthritis, asthma, psoriasis, transplant‐rejection, and allergy. Block‐ade of LFA‐1 and VLA‐4 interactions with their ligands is a potential target for immunosuppression. LFA‐1 and VLA‐4 antagonists (antibodies, peptides, and small molecules) are being developed for controlling inflammation and autoimmune diseases. The therapeutic intervention of mostly mAb‐based has been extensively studied. However, due to the challenging relative efficacy/safety ratio of mAb‐based therapy application, especially in terms of systemic administration and immunogenic potential, strategic alternatives in the forms of peptide, peptide mimetic inhibitors, and small molecule non‐peptide antagonists are being sought. Linear and cyclic peptides derived from the sequences of LFA‐1, ICAM‐1, ICAM‐2, VCAM‐1, and FN C1 have been shown to have inhibitory effects in vitro and in vivo. Finally, understanding the mechanism of LFA‐1 and VLA‐4 binding to their ligands has become a fundamental basis in developing therapeutic agents for inflammation and autoimmune diseases. © 2002 John Wiley& Sons, Inc. Med Res Rev, 22, No. 2, 146–167, 2002; DOI 10.1002/med.10001