Differential Expression of Chemokines, Chemokine Receptors and Proteinases by Foreign Body Giant Cells (FBGCs) and Osteoclasts

Abstract

Osteoclasts are derived from the fusion of monocyte / macrophage lineage and are responsible for bone homeostasis1. Macrophages in the presence of a foreign body can also fuse to form Foreign body giant cells2. One of the important chemotactic factor for macrophages is CCL23, that binds to its primary receptor CCR24. Here we test the differential expression of chemokines, their receptors and proteinases by these cells to identify potential and specific targets. Osoteoclasts and FBGC were cultured from the bone marrow cells were divided into two groups. One group of cultures were fixed and subsequently TRAP stained while the second group was used for gene expresssioin analysis. FBGCs are associated with inflammatory conditions (i.e. foreign body reactions) hence the inflammatory chemokines were more expressed by these cells compared to osteoclasts. Intrestingly, the expression of chemokine receptors were highly expressed by osteoclasts compared to FBGCs. Furthermore, FBGCs exibited a significantly lower expression of osteoclast related genes (i.e.RANK, NFATc1, MMP9 TRAP etc) and were not able to resorb bone,