EFFECTS OF INTERLEUKINS ON CROUZON FIBROBLAST PHENOTYPE IN-VITRO - RELEASE OF CYTOKINES AND IL-6 MESSENGER-RNA EXPRESSION

In Crouzon's syndrome, the cranial morphogenic processes are altered d ue to the early fusion of the facial and basal cranial bones, Evidence that Crouzon fibroblasts have an altered phenotype which is modulated by interleukin 1 (IL-1) and interleukin 6 (IL-6) is provided, [H-3]Th ymidine incorporation and cell count studies showed that Crouzon fibro blasts have an accelerated proliferation rate, [H-3]Glucosamine incorp oration studies, followed by chromatography analysis of culture medium samples, revealed that the various classes of glycosaminoglycans (GAG ) secreted into the medium were differently distributed in Crouzon and normal fibroblasts, Crouzon fibroblasts secreted less total GAG, part icularly hyaluronic acid (HA) and heparan sulfate (HS), but a relative ly greater quantity of chondroitin sulfate, Type I and III collagen we re raised in Crouzon fibroblast medium whereas the concentration of fi bronectin was lower than in normal cells, Interleukin treatment induce d changes in cell growth and neosynthesis of extracellular matrix macr omolecules. Both IL-1 and IL-6 stimulated proliferation of Crouzon fib roblasts, whereas only IL-6 increased [H-3]thymidine incorporation in normal cells, IL-1 provided a drop in HA and a rise in GAG sulfates in normal fibroblasts, but caused an opposite effect in Crouzon fibrobla sts, Type I collagen and fibronectin secretions are differently modula ted by the cytokines in the two populations, Moreover, level of IL-I a ble to stimulate [H-3]thymidine incorporation into mouse thymocytes, a nd level of IL-1 receptor antagonist (IL-1ra), as determined by ELISA, were higher in pathological than in normal fibroblasts. Also evidence that levels of IL-lcr and IL-6 proteins measured by ELISA and also IL -6 mRNA expression are enhanced in Crouzon fibroblasts is provided, Th ese novel data suggested that, in Crouzon's syndrome, the modification s in the relative concentrations of the extracellular matrix (ECM) com ponents associated with the abnormal cytokine networks may alter the b alance of the microenvironment where the morphogenic events take place . (C) 1996 Academic Press Limited