Purpose: To study the responses of human conjunctival fibroblasts (HCFs) to stimulation by human neutrophil defensin 1 (HNP1) and beta defensin2 (HBD2).
Methods: Defensin-stimulated gene expression in primary cultures of HCFs was analyzed by real-time PCR after exposure to various concentrations of HNP1 or HBD2. Gene and protein expression for selected collagens, matrix metalloproteinases, and tissue inhibitors of metalloproteinases were determined by real-time PCR and ELISA analysis. Activation of p42/44 mitogen-activated protein (MAP) and Akt was analyzed by Western blot.
Results: HCFs did not express significant levels of the genes for HNP1 or HBD1-3. However, HNP1 and HBD2 stimulated HCF proliferation, the activation of p42/44 MAP kinase, and Akt kinase in a dose-dependent manner. HNP1 and HBD2 were not found to be chemotoxic for HCFs. It was demonstrated with the use of U0126 and wortmannin that the activation of p42/44 MAP kinase and Akt was responsible for the increased HCF proliferation observed under HNP1 and HBD2 stimulation. HNP1 stimulated the expression of the genes for collagen I, III, VI, and VIII. In addition, it reduced the secretion of collagen I protein but increased its intracellular retention. HNP1 and HBD2 upregulated the transcription and translation of MMP1. Small increases were observed in MMP14 gene expression after HNP1 stimulation and MMP2 gene expression after HBD2 stimulation.
Conclusions: The results of this study suggest that HNP1 and HBD2 have a potential role in the biosynthetic and tissue remodeling responses of conjunctival fibroblasts.