title: Mechanisms of action of cyclosporine and effects on connective tissues.
abstract: Cyclosporine is a potent immunomodulatory agent with an increasing number of clinical applications. Its major mode of action is inhibition of the production of cytokines involved in the regulation of T-cell activation. In particular, cyclosporine inhibits the transcription of interleukin 2. Although cyclosporine's major actions are on T cells, there is some evidence that it produces direct effects on other cell types. Its immunosuppressive action is closely linked to its binding of cyclophilin, a member of a family of high-affinity cyclosporine-binding proteins widely distributed in different cell types and in different species. The cyclophilins have been shown to have peptidyl-prolyl cis-trans isomerase enzyme activity that is blocked by cyclosporine. Although this may be a factor in cyclosporine's selective inhibition of cytokine gene transcription, it is still unclear whether inhibition of this activity is the mechanism through which cyclosporine exerts its effects on target cells. The ubiquitous presence of cyclophilins raises the question of why cyclosporine has major effects on T cells. Perhaps the critical proteins affected are transcriptional regulators restricted in their tissue distribution. The effects of cyclosporine on T cells and, directly or indirectly, on connective tissue cells, all of which can produce a range of cytokines, are of interest in relation to the tissue changes that occur in such inflammatory conditions as rheumatoid arthritis.
authors.affiliation: Department of Human Metabolism and Clinical Biochemistry, University of Sheffield Medical School, England.
authors.forename: G
authors.initials: G
authors.lastname: Russell
authors.forename: R
authors.initials: R
authors.lastname: Graveley
authors.forename: J
authors.initials: J
authors.lastname: Seid
authors.forename: A K
authors.initials: AK
authors.lastname: al-Humidan
authors.forename: H
authors.initials: H
authors.lastname: Skjodt
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D003238:Connective Tissue / Q000187:drug effects* / Q000378:metabolism; D016572:Cyclosporine / Q000737:chemistry / Q000494:pharmacology*; D016207:Cytokines / Q000096:biosynthesis; D006801:Humans; D007107:Immune System / Q000502:physiology
chemical_list: D016207:Cytokines; D016572:Cyclosporine