The candidate is a retina clinician-scientist whose primary career goal is to advance the care of patients with age-related macular degeneration (AMD) by (1) elucidating disease mechanisms, with a specific focus on macrophages; and (2) identifying novel disease biomarkers and targets for therapy. In addition to clinical training, he has completed a clinical research fellowship and has spent two years in a Departmental K12 Career Development Program. In the first year, he rotated through various laboratories and in the second year, he has pursued a novel project investigating the role of activated macrophages in neovascular remodeling (NVR), the transformation of nascent capillaries into branching arterioles with perivascular fibrosis, and a major cause of treatment-resistant neovascular AMD (NVAMD). His immediate career development goals in the current proposal are to further understanding of NVR pathobiology by identifying the specific blood monocyte subset(s) that give rise to NVR-promoting macrophages and by characterizing mechanisms that regulate macrophage effector function in the setting of NVR. The candidate plans an R01 submission in early year three on an innovative translational project to characterize the biology of macrophage-mediated NVR in experimental CNV and NVAMD, correlating monocyte subset frequencies and activation states with CNV morphology and treatment-resistant NVAMD. Additional didactic training in immunology, molecular biology, microscopy, departmental research seminars, and advanced responsible conduct of research will be obtained during the award period, and the candidate will present his findings at national meetings and submit his work for publication. Environment: The mentorship and expertise of the advisory committee, the extensive resources of the Duke Departments of Ophthalmology and Pharmacology / Cancer Biology, and the significant institutional commitment will provide the support needed for this candidate to complete the proposed research project and transition successfully to an independent research career. Research: Although intravitreal anti-VEGF therapies have improved vision outcomes, 40-50% of patients exhibit treatment-resistant NVAMD / PDA. PDA occurs more frequently in patients with CNV morphology that reflects NVR. The candidate and his primary mentor have established macrophages as a driver of NVR, and preliminary data suggests that low-grade systemic exposure to three different pathogen-associated molecular patterns (PAMPs) promotes NVR in a murine model of laser-induced CNV. In spite of each PAMP having a distinct activating receptor, all three PAMP-activated signaling cascades are known to mobilize calcium and activate the calcium-binding protein, calmodulin. Accordingly, preliminary data suggests that mice null for calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2), an intermediate kinase known to amplify PAMP-activated effector pathways in macrophages, demonstrate reduced NVR. The central hypothesis is that PAMP-stimulation regulates NVR through activation of CaMKK2-mediated macrophage effector function. Specifically, low-grade PAMP stimulation is hypothesized to (1) increase the frequency of circulating nonclassical Ly6Clo monocytes in blood; and (2) promotes activation of Ly6Clo monocyte-derived macrophages, increasing expression of fibrogenic growth factors, (3) via activation of CaMKK2 signaling (Fig. 2). Fibrogenic factors recruit and activate vascular smooth muscle cells and myofibroblasts, leading to development of NVR.
Aim 1 will address the hypothesis that PAMP-stimulated NVR in experimental neovascularization is mediated by activated macrophages arising from nonclassical Ly6Clo blood monocytes.
Aim 2 will address the hypothesis that CaMKK2 regulates macrophage-mediated NVR.
This research project is trying to understand the causes of the severe form of neovascular, or 'wet,' macular degeneration, which does not respond well to available medications that block the molecule vascular endothelial growth factor, or VEGF. Thus, severe wet macular degeneration remains a significant cause of vision loss. Macrophages are cells in the body that fight off infection, but in some cases, can cause damage to tissue in the body. This research is focused on determining how macrophages make wet macular degeneration harder to treat with available medicines. Understanding the role of macrophages will provide new knowledge about the disease that may allow the development of new treatments for affected patients who continue to lose vision in spite of current treatments.