Expression of mRNA coding for TNF alpha, IL-1 beta and IL-6 by cells infiltrating retinal membranes.

Abstract

Cellular mechanisms of inflammation are thought to be involved in the pathogenesis of proliferative vitreoretinopathy, and cytokines, which are products of cell activation, are known to play an important role in the development and maintainance of inflammatory reactions. It was the aim of this work to investigate the presence of cells expressing cytokine mRNA within retinal membranes. The presence of mRNA coding for the cytokines interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF alpha) was investigated in 19 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by proliferative vitreoretinopathy. Cells expressing mRNA for IL-1 beta were observed in 7 membranes, cells positive for IL-6 mRNA were seen in 12 membranes, and cells exhibiting mRNA for TNF alpha were present in 9 specimens. Only three membranes contained cells expressing mRNA for all the cytokines investigated. Four membranes possessed positive cells for IL-6 and TNF alpha, two contained cells expressing mRNA for IL-6 and IL-1 beta, and two others exhibited cells expressing mRNA for TNF alpha and IL-1 beta. Five membranes contained IL-6 mRNA-positive cells only, whilst two exhibited cells expressing mRNA for IL-1 beta or TNF alpha only. The present findings indicate that cellular activation may occur during the development of PVR, and suggest that these cytokines may be locally produced by cells infiltrating epiretinal membranes. The presence of IL-1 beta, IL-6 and TNF alpha mRNA-positive cells within retinal membranes provides further evidence of a pathogenic role of these cytokines in proliferative vitreoretinopathy.