Increased expression of VLA-5 adhesion molecules on synovial fluid T lymphocytes in chronic polyarthritis: a consequence of T-cell activation

Novel Functions of Integrins as Receptors of CD154: Their Role in Inflammation and Apoptosis

CD154, an inflammatory mediator also known as CD40 ligand, has been identified as a novel binding partner for some members of the integrin family. The αIIbβ3, specifically expressed on platelets, was the first integrin to be described as a receptor for CD154 after CD40. Its interaction with soluble CD154 (sCD154) highly contributes to thrombus formation and stability. Identifying αIIbβ3 opened the door for investigating other integrins as partners of CD154. The αMβ2 expressed on myeloid cells was shown capable of binding CD154 and contributing as such to cell activation, adhesion, and release of proinflammatory mediators. In parallel, α5β1 communicates with sCD154, inducing pro-inflammatory responses. Additional pathogenic effects involving apoptosis-preventing functions were exhibited by the CD154–α5β1 dyad in T cells, conferring a role for such interaction in the survival of malignant cells, as well as the persistence of autoreactive T cells. More recently, CD154 receptors integrated two new integrin members, αvβ3 and α4β1, with little known as to their biological significance in this context. This article provides an overview of the novel role of integrins as receptors of CD154 and as critical players in pro-inflammatory and apoptotic responses.

Pathogenesis of degenerative joint disease in the human temporomandibular joint

The wide range of disease prevalences reported in epidemiological studies of temporomandibular degenerative joint disease reflects the fact that diagnoses are frequently guided by the presence or absence of non-specific signs and symptoms. Treatment is aimed at alleviating the disease symptoms rather than being guided by an understanding of the underlying disease processes. Much of our current understanding of disease processes in the temporomandibular joint is based on the study of other articular joints. Although it is likely that the molecular basis of pathogenesis is similar to that of other joints, additional study of the temporomandibular joint is required due to its unique structure and function. This review summarizes the unique structural and molecular features of the temporomandibular joint and the epidemiology of degenerative temporomandibular joint disease. As is discussed in this review, recent research has provided a better understanding of the molecular basis of degenerative joint disease processes, including insights into: the regulation of cytokine expression and activation, arachidonic acid metabolism, neural contributions to inflammation, mechanisms of extracellular matrix degradation, modulation of cell adhesion in inflammatory states, and the roles of free radicals and heat shock proteins in degenerative joint disease. Finally, the multiple cellular and molecular mechanisms involved in disease initiation and progression, along with factors that may modify the adaptive capacity of the joint, are presented as the basis for the rational design of new and more effective therapy.