Purpose: To examine the short- and long-term consequences of verteporfin photodynamic therapy (PDT) on inflammation with regard to infiltration of macrophages and leukocytes and expression of thy-1 in human choroidal neovascularization membranes (CNV) secondary to age-related macular degeneration (AMD).
Methods: Retrospective review of an interventional case series of 43 patients who underwent removal of CNV. Twenty patients were treated with PDT 3 to 246 days preoperatively. Twenty-three CNV without previous treatment were used as control. CNV were stained for CD34, CD105, cytokeratin 18, Ki-67, thy-1, an endothelial cell glycoprotein known to be upregulated only by inflammatory cytokines, CD68 (macrophages), and CD45 (common leukocyte antigen).
Results: Specimens treated by PDT 3 days previously showed significantly reduced endothelial thy-1 expression (P = 0.008), leukocyte (P=0.04) and macrophage (P=0.0063) infiltration, and proliferative activity (P=0.02) compared to control CNV. Specimens at longer intervals after PDT, in contrast, disclosed a significantly increased expression of thy-1 (P=0.004), infiltration with leukocytes (P=0.044) and macrophages (P=0.01), and proliferative activity (P=0.03) compared to CNV excised 3 days after PDT.
Conclusions: The rebound effect after PDT seems to be based on an inflammatory response that contributes to enhanced proliferation. These data support the need for an anti-inflammatory therapy as adjuvant to PDT.