Abstract
Abstract: :
Purpose: Living organisms tend to adapt effective mechanisms to similar functions in different organs. Osteoblasts and osteoclasts interact in the maintenance and repair of bone. Osteoclasts are derived from monocytes through cytokine-mediated differentiation requiring juxtacrine- and paracrine -mediated input from osteoblasts. This osteoblast interaction involves specific cytokines and receptors (receptor activator of NF kappa B (RANK), RANK ligand (RANKL), osteoprotegerin (OPG), and macrophage colony stimulating factor (mCSF). Large numbers of monocytes migrate into the cornea within 12 to 24 hours of epithelial injury, even in the absence of microbial infection. In this study, RT-PCR and immunoprecipitation-western blotting were used to determine if corneal fibroblasts express the mRNAs and proteins of the necessary cytokines and receptors to direct transformation of monocytes in the cornea. Methods: Complementary DNA was generated from primary mouse corneal fibroblasts. PCR primers for mouse OPG, mCSF, and RANK ligand were used to amplify corneal fibroblast cDNA. PCR products were evaluated for size and confirmed by nucleic acid sequencing. Immunoprecipitation and western blotting were performed with lysates from primary mouse corneal fibroblasts. Results: Primary corneal fibroblasts express mRNAs coding for RANKL, OPG, and OPG. Amplified sequences were of the appropriate size and amplified sequences were confirmed by sequencing. mCSF and OPG proteins were detected in mouse stromal fibroblasts. Experiments are ongoing to detect RANKL protein in mouse stromal fibroblasts. Conclusion: Corneal fibroblasts express OPG (soluble receptor for RANKL) and mCSF mRNA and protein. They also express mRNA coding for RANKL. These are the critical cytokines and receptors produced by osteoblasts to regulate monocyte differentiation into osteoclasts in bone. We hypothesize that cells (keratoclasts) involved in maintenance and wound healing-associated remodeling of corneal stroma are derived from monocytes via cytokine-mediated interactions with keratocytes. Further studies will be needed to confirm protein expression and the transformation of monocytes into cells involved in stromal remodeling in the cornea.
Keywords: cornea: basic science • wound healing • cornea: stroma and keratocytes