Modulation of Neuroinflammation in Glaucoma

PROJECT SUMMARY Growing information from the studies of human glaucoma and experimental models supports that glia-driven neuroinflammation creates an additional damaging force on retinal ganglion cell (RGC) somas, axons, and synapses, and its therapeutic modulation can provide widespread neuroprotection. Our accumulated data from recent studies of neuroinflammation in glaucoma led to our new hypotheses that we aim to test in this project. Evidently, cFLIP functions as a molecular switch between caspase-8-mediated cell death/survival/inflammation pathways through TNFRs, TLRs, and inflammasome, Our first Specific Aim will test whether conditional deletion of astroglial cFLIP can inhibit the inflammatory outcomes caspase-8/cFLIP interaction and prevent/reverse the inflammatory/neurotoxic astrocyte phenotype in experimental glaucoma. We expect that deletion of cFLIP in astroglia will selectively target inflammatory/neurotoxic (A1) astrocytes (because these cells are primed for inflammatory caspase-8 functions through TNF-α/TNFR, Fas/FasL, TLRs, and inflammasome) and will provide immunomodulation (without risking the glial neurosupport functions). Besides cFLIP, we will selectively target cFLIPL to also determine isoform-specific differences in inflammatory outcomes and cell fate decisions. We will analyze spatial and temporal responses to astroglial cFLIP (or cFLIPL) deletion by morphological and molecular analysis of retina and optic nerve astroglia, including inflammatory responses, A1/A2 astrocyte distribution, cell death (apoptosis/necroptosis), and neurosupport functions. Elimination of astroglia-driven inflammation can protect RGCs against inflammatory injury in experimental glaucoma. Our Specific Aim 2 will test this hypothesis by analysis of neuron survival (by RGC axon/soma counting) and function (by PERG). Astroglia and microglia closely interplay and regulate each other’s phenotype and immune functions. Our recent research findings also supported that astroglial cytokine responses may shape microglia responses in experimental glaucoma. Our Specific Aim 3 is therefore designed to test whether glial subtype-specific deletion of cFLIP (or cFLIPL) can impact individual contributions and the cross-talk between astroglia and microglia during neuroinflammation. We will analyze microglia responses (including M1/M2 conversion) to astroglial deletions, and and astroglia responses (including A1/A2 distribution) to microglial deletions at different sites/time points. Longitudinal analysis will also include oligodendrocyte and Müller glia responses. Through the analysis of cell type-specific responses (including the molecular responses of isolated glial subtypes) to glial subtype-targeting mouse models, this project will value glial cFLIP as an immunomodulatory treatment target to prevent/reverse neurodegenerative inflammation in experimental glaucoma. Outcomes of this project are also expected to be widely useful in studies of other ocular/neurodegenerative/neuroinflammatory diseases, aging, stem cell/axon regeneration, and cancer research.