Hyaluronidase expression in human skin fibroblasts

Hyaluronidase activity has been detected for the first time in normal human dermal fibroblasts (HS27), as well as in fetal fibroblasts (FF24) and fibrosarcoma cells (HT1080). Enzymatic activity was secreted predominantly into the culture media, with minor amounts of activity associated with the cell layer. In both classes of fibroblasts, hyaluronidase expression was confluence-dependent, with highest levels of activity occurring in quiescent, post-confluent cells. However, in the fibrosarcoma cell cultures, expression was independent of cell density. The enzyme had a pH optimum of 3.7 and on hyaluronan substrate gel zymography, activity occurred as a single band corresponding to an approximate molecular size of 57 kDa. The enzyme could be immunoprecipitated in its entirety using monoclonal antibodies raised against Hyal-1, human plasma hyaluronidase. PCR confirmed that fibroblast hyaluronidase was identical to Hyal-1. The conclusion by previous investigators using earlier technologies that fibroblasts do not contain hyaluronidase activity should be reevaluated.