Novel Targets and Therapeutic Interventions against Cerebral Ischemia-Reperfusion Injury

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Project Summary/Abstract The cerebral ischemia/reperfusion (I/R) injury is a major challenge for the treatment of patients with acute ischemic stroke by intravenous (IV) thrombolysis and endovascular therapy. Currently, there is no effective intervention available to treat/prevent cerebral I/R injury. Emerging evidence suggests that thrombotic and inflammatory responses (thrombo-inflammation) and aberrant endoplasmic reticulum (ER) stress in the brain elicited by cerebral I/R contributes importantly to secondary brain injury and neurologic deterioration. In this proposal we wish to develop a novel miRNA-based therapeutic strategy to simultaneously target these pathological processes of cerebral I/R injury through distinct molecular mechanisms. Recently, decreased expression of miR-30c has been implicated in many pathological conditions in both patients and animal models. In preliminary studies, we show that miR-30c is highly expressed in blood platelets, cerebral microvessels, and cortical/hippocampal neurons in normal mice but its levels decline with age. miR-30c levels in both blood and brain are markedly decreased after ischemic stroke and elevating miR-30c by single IV injection of synthetic miR-30c mimic significantly protects against cerebral I/R injury. We further show that the increased expressions of the direct target genes of miR-30c (including PAI-1 in both blood and brain, elF2α and caspase-3 in the brain) induced by cerebral I/R injury were significantly decreased by IV miR-30c mimic treatment. Based on these exciting new findings from young adult mice, we propose the innovative hypothesis that miR-30c functions as a critical regulator of thrombo-inflammation and ER stress in the ischemic brain elicited by cerebral I/R injury, and thus targeting miR-30c represents a novel therapeutic approach for combating cerebral I/R injury. Following updated stroke Therapy Academic Industry Roundtable (STAIR) pre-clinical guidelines, we will test this hypothesis in aged male and female mice. Specifically, we will determine the efficacy and safety of IV miR-30c mimic as novel stroke therapeutics (Aim1). Using complementary approaches, i.e. the “gain-of-function” (miR- 30c mimic) and “loss-of-function” (anti-sense Morpholino oligos that are designed to specifically compete with miR-30c for binding sites of 3’UTR of each individual target gene and thus acts as a “target protector”), we will identify PAI-1 as a key molecular target of miR-30c in regulation of post-stroke thrombo-inflammation (Aim 2), and identify elF2α and caspase 3 as key molecular targets of miR-30c in regulation of post-stroke neuronal ER stress and neuronal cell death (Aim 3). The long-term goal of these studies is to evaluate if targeting miR-30c is a viable option for stroke therapy in both male and female older populations at high risk for stroke.