TIMP1 and periodontitis: In the context of chronic periodontitis, where LL-37 expression has been shown to be significantly higher than in healthy sites [6], the lack of a stimulatory effect by LL-37 on MMP activities, in addition to the increased expression of TIMP-1 by the fibroblasts, may be interpreted as a refined mechanism of controlling proteolytic activity in a bid to curb disease progression.