Increased expression of collagen prolyl 4-hydroxylases in Chinese patients with hereditary gingival fibromatosis

ObjectivesHereditary gingival fibromatosis (HGF) is characterized by excess accumulation of interstitial collagen. However, until now, there has been controversy about the mechanism of collagen accumulation in HGF gingivae. The present study aimed to clarify the pathogenic mechanisms potentially involved.DesignGingival fibroblasts from three Chinese HGF patients and three healthy subjects were cultured. Cell proliferation was assessed by MTT assay. The mRNA levels of type I collagen, MMP-1, MMP-3, TIMP-1, prolyl 4-hydroxylase (P4H)α(I), α(II), α(III) and P4Hβ were analyzed in gingival fibroblasts by RT-PCR. The protein production of type I collagen and P4H was examined respectively by ELISA and Western blot.ResultsIn culture, HGF gingival fibroblasts showed similar growth characteristics to fibroblasts isolated from control gingivae. The mRNA and protein levels of type I collagen and P4Hα in HGF fibroblasts were higher than those in controls. There were no detected differences in mRNA expression levels of MMP-1, MMP-3, TIMP-1, P4Hα(II), α(III) and P4Hβ between HGF and control fibroblasts.ConclusionsThese data suggest that increased collagen post-translational modification by P4H may be one mechanism by which increased collagen accumulation occurs in some forms of HGF.