Abstract
Abstract: :
Purpose: We previously demonstrated the presence of phagocytic/microglial cells in the inner retina after retinal ischemia-reperfusion injury in rats. To explore the role of these cells, we studied their cytokines after the insult. Methods: Cannulas, connected to a saline column that generated a pressure of 110 mmHg, were inserted into the anterior chambers of Adult Lewis albino rats and the elevated pressure was maintained for 1 hour. After 1 hour, the cannulas were removed to restore retinal reperfusion. Animals were euthanized at 0, 2, 4, 8, 18, 24 and 48 hours post reperfusion and their eyes enucleated. The retinas of some eyes were dissected and homogenized for dot blot analysis of four cytokines: 3 inflammatory cytokines - Interleukin-1α (IL-1α), Tumor Necrosis Factor-α (TNF-α), and Interleukin-6 (IL-6) and one anti-inflammatory cytokine, Interleukin-10 (IL-10). Some eyes were fixed, processed, embedded in paraffin and sectioned. Immunohistochemistry was also performed. Results: : Dot blot analysis shows different temporal changes for the four cytokines after the insult. Levels of IL-6 and TNF-α become elevated between 2 and 4 hours, peak at 8 hours post reperfusion, and then return back to normal between 24 and 48 hours post reperfusion while the levels of IL-1α rise in a steady manner between 0 and 24 hours, peak at 24 hours and return to levels similar to control between 24 and 48 hours. IL-10, on the other hand, is markedly decreased between 0 and 4 hours post reperfusion, returns to normal around 8 hours, and becomes slightly elevated between 18 and 48 hours post reperfusion. Immunohistochemistry localizes IL-6 positive cells to the inner retina and colocalization studies reveal that these IL-6 positive cells are also positive for ED-1, a marker of phagocytic cells. Conclusion: Phagocytic cells may modulate the tissue responses through different cytokines at different times after retinal ischemia-reperfusion injury.