Defining the contribution from endothelial cell sphingolipid metabolism to outcomes of acute ischemic stroke in mice - Project Summary Acute ischemic stroke (AIS) is a leading cause of death worldwide, and survivors experience neurological and motor deficits that impair their quality of life. Here we leverage innovative murine models and novel ceramide biosynthesis inhibitors to (i) determine whether interventions that target cerebral endothelial cells might improve stroke outcomes (Aim 1) and (ii) test a novel therapeutic strategy for lowering ceramides to mitigate the tissue injury, neurological impairments, motor deficits that accompany AIS (Aim 2). AIS increases plasma ceramides that correlate with the prevalence and severity of neural damage and motor deficits in patients. Mice undergoing AIS display heightened ceramides in plasma and ipsilesional (ischemic) hemispheres, as well as neurological and motor deficits, relative to sham-operated controls. To assess the contribution from cerebral ECs to AIS-induced ceramide generation, we obtained EC- and non-EC- enriched fractions from ipsilesional hemispheres. Compared to sham-operated mice, AIS elevates ceramide generation selectively in the EC-enriched fraction. Based on rationale provided by our published and preliminary data, together with findings from others, we hypothesize that AIS-induced, EC-derived ceramides induce arteriolar and mitochondrial dysfunction, ultimately leading to tissue injury, neurological deficits, and motor defects. Aim 1 will discern whether AIS-induced cerebral EC ceramide generation drives pathology by dysregulating arteriolar and mitochondrial function in lean and obese mice. To accomplish this, we generated mice allowing for inducible, brain-selective, EC-specific gain or loss of ceramides. The brief time-window during which approved treatments for AIS must be initiated limits their implementation. New intervention strategies are needed. The enzyme dihydroceramide desaturase 1 (DES1) catalyzes the insertion of a double-bond into inert dihydroceramides to produce toxic ceramides. Centaurus Therapeutics developed small molecule inhibitors of DES1 that are nearing phase 1A human trials. Centaurus completed in vitro absorption, distribution, metabolism, and excretion studies, with several compounds exhibiting good solubility, permeability, and metabolic stability in vitro and outstanding pharmacokinetics in vivo. In Aim 2 we will test the hypotheses that DES1 inhibition, which protects against ischemic damage in other disease contexts, can effectively attenuate AIS-induced infarct volume and neurological and motor deficits. Results from Aims 1 and 2 could uncover new sites of intervention (i.e., ECs) and provide pre-clinical validation of a novel therapeutic strategy (i.e., DES1 inhibition) for combating the debilitating complications of AIS.
