Localization of the chemokine interleukin-8 and interleukin-8 receptors in human gingiva and cultured gingival keratinocytes

Interleukin-8 (lL-8) has been implicated in a wide variety of diseases. Previous studies have demonstrated the expression of IL-8 in periodontal tissues. yet little is known about the exact source(s). mechanisms and factors involved in gingival expression of IL-8. Additionally. nothing is known about the presence and distribution of IL-8 receptors (IL-8R) in gingival cells. Therefore it was hypothesized that. in vivo. periodontal pathogens induce IL-8 expression from gingival keratinocytes (GK) which enhances leukocyte, microvascular endothelial cell (MVEC) and GK migration via specific IL-8 receptors present on these cells. The objective of the present study was to determine the distribution of IL-8 and IL-8R in gingival tissues and cultured human GK in vitro. Standard immunohistochemical and immunocytochemical techniques were utilized in order to localize IL-8 and its receptors CXCR-1 and CXCR-2) in archival gingival specimens (eight periodontitis and Four non-inflamed controls) and in cultured gingival keratinocytes. It was demonstrated that. in vivo, IL-8 and IL-8R were present in gingival epithelium, MVEC and leukocytes. In vitro studies verified the above results. by showing expression of IL-8 and IL-8R in cultured gingival keratinocytes. It is concluded that IL-8 and IL-8 receptors are expressed in gingival epithelium both in vivo and in vitro. This new evidence indicates that epithelium plays a critical role in the host defense against invading pathogens and that keratinocytes can actively respond to IL-8 and other host cytokines, via specific receptors.