Although multiple sclerosis (MS) is classically considered a demyelinating disease, neuro-axonal loss occurs in both relapsing and progressive phases of the disease and represents the primary pathologic correlate of disa- bility. Existing therapies primarily target the peripheral immune system, preventing clinical relapses but largely failing to prevent neurodegeneration in progressive MS. Therapies with a primary neuroprotective mode of ac- tion are a major goal of current research, both to slow disability in progressive MS and to limit injury when re- lapses occur despite current therapies. Nitric oxide (NO), a toxic free radical produced by central nervous sys- tem (CNS) macrophages and microglia, contributes to neuro-axonal injury in both relapsing and progressive MS and in models of neuroinflammation, with NO-induced mitochondrial dysfunction playing a major role. Spe- cific, druggable signaling pathways that mediate this injury have not been identified. We propose to study a candidate signaling pathway involving nitrosylation of the protein GAPDH. Nitrosylated GAPDH (SNO-GAPDH) translocates to both nucleus and mitochondria, with an established role in cell death and nuclear targets, such as SIRT1 and PGC-1?, critical for mitochondrial bioenergetics. Moreover, SNO-GAPDH signaling can be blocked by CGP3466, a highly specific, oral CNS-penetrant drug with an established safety profile in humans and a low threshold for clinical translation. We have preliminary evidence that SNO-GAPDH signaling is active in an experimental autoimmune encephalomyelitis (EAE) mouse model of neuroinflammation, and in white matter tissue obtained post-mortem from MS patients. We have found that systemic administration of CGP3466 attenuates neurologic disability in C57BL/6 MOG35-55/CFA EAE and prevents impairment of neuronal mitochondrial respiration in cultured neurons exposed to NO. In the proposed studies, we plan to fully charac- terize SNO-GAPDH pathway activity in MOG35-55/CFA EAE and post-mortem human MS tissue. We will deter- mine whether the protective effects of CGP3466 in EAE derive from a primary neuroprotective mechanism in- dependent of peripheral immune effects, differentiating it from current therapies and establishing its pre-clinical potential. Finally, we will seek mechanistic insights by evaluating the effects of SNO-GAPDH on neuronal mito- chondrial function. Positive results from this mechanistic and pre-clinical therapeutic research will establish a new therapeutic approach for MS and neuroinflammatory disease more broadly. The PI's career development plan will provide new training opportunities in immunology, models of neuroinflammation, and mitochondrial bioenergetics, providing a foundation for future independent studies of inflammatory neurodegeneration.
Multiple sclerosis (MS) is a chronic, inflammatory disease of the central nervous system that produces disabil- ity through immune-mediated demyelination and subsequent neuro-axonal injury. Neuroprotective therapies that prevent neuro-axonal loss independent of peripheral immune effects are a major goal of current research, both to complement current therapies and to slow disability in the progressive phase of MS, which is no longer driven by peripheral immune activation. This proposal evaluates a candidate signaling pathway that may pro- mote neuro-axonal injury in neuroinflammation, while establishing the pre-clinical potential of a brain-penetrant drug that selectively blocks this pathway.
