Macrophage-derived interleukin-6 is necessary and sufficient for choroidal angiogenesis
Steven Droho, Carla M. Cuda, Harris Perlman, Jeremy A. Lavine
Abstract
Abstract Neovascular age-related macular degeneration (nAMD) commonly causes vision loss from aberrant angiogenesis, termed choroidal neovascularization (CNV). Interleukin-6 (IL6) is a pro-inflammatory and pro-angiogenic cytokine that is correlated with AMD progression and nAMD activity. We hypothesize that anti-IL6 therapy is a potential nAMD therapeutic. We found that IL6 levels were increased after laser injury and expressed by macrophages. Il6 -deficiency decreased laser-induced CNV area and exogenous IL6 addition increased choroidal sprouting angiogenesis. Il6 -null mice demonstrated equally increased macrophage numbers as wildtype mice. At steady state, IL6R expression was detected on peripheral blood and ocular monocytes. After laser injury, the number of IL6R + Ly6C + monocytes in blood and IL6R + macrophages in the eye were increased. In human choroid, macrophages expressed IL6 , IL6R , and IL6ST . Furthermore, IL6R + macrophages displayed a transcriptional profile consistent with STAT3 (signal transducer and activator of transcription 3) activation and angiogenesis. Our data show that IL6 is both necessary and sufficient for choroidal angiogenesis. Macrophage-derived IL6 may stimulate choroidal angiogenesis via classical activation of IL6R + macrophages, which then stimulate angiogenesis. Targeting IL6 or the IL6R could be an effective adjunctive therapy for treatment-resistant nAMD patients.