We and others have been pioneers in targeting the transcriptional factor Nrf2, a master regulator of oxidative stress and inflammation, as a promising strategy for stroke therapy. We and others have also documented the possibility that CO and ?CO donor? can provide neuroprotection. Accumulated evidence from the PI's lab show that small molecules such as the dimethyl fumarate (DMF), a typical Nrf2 inducer being used in the clinic, and CO at low doses, contrary to the traditional view as a toxic agent, have displayed sustained neuroprotective efficacy against ischemic brain damage and functional deficits notably via the Nrf2 pathway. Consequently, we would predict that a molecule containing both a methyl fumarate and CO-releasing molecule unit (i.e. FumET-CORM) could have an intriguing and promising therapeutic potential. Our preliminary results showed that CO or DMF exposure is protective in both transient and permanent focal cerebral ischemia mouse models. FumET-CORM has already been shown to exhibit anti-inflammatory property. This prompts us to work on the hypothesis that the new FumET-CORM would be protective against neurological deficits and infarct after permanent distal middle cerebral artery occlusion (pdMCAO); and that this beneficial effect would be, at least partially, regulated by the Nrf2 cytoprotective pathway.
In AIM 1, we will determine whether FumET-CORM (vs its inactive iFumET-CORM) is protective against neurological deficits and brain damage following pdMCAO. We will test a dose response and a therapeutic window protocols to determine the optimal beneficial dose regimen in male and female adult mice. Primary outcomes will be based on neurological/cognitive changes, and various IHC staining will be performed to start exploring the implications of various putative pathways. Toxicity will also be monitored. The optimal dose/treatment regimen will be extended in the aged littermates.
In AIM 2, we will examine whether the Nrf2 pathway plays a significant role in the FumET-CORM ?dual- action drug? beneficial mechanism and start addressing which brain cell type(s) is responsible for such neuroprotection by first using a co-immunostaining approach. Using the optimal conditions from Aim 1, we will evaluate the contribution of Nrf2 pathway using global Nrf2-/- C57BL/6 mice, and also address which brain cell type(s) reveal the most profound Nrf2-related changes. This would then dictate the future test of the most appropriate inducible Nrf2 flox-cre mice ? using the latest and most selective cre mice. Together, we will test the hypothesis that some of the imputed beneficial effects of the FumET-CORM ?dual-action drug? on brain damage are attributed at least in part to Nrf2 and which cells can be most responsible for the putative neuroprotection. This could be administered to ischemic stroke patients and potentially other acute brain insults. This R21 mechanism is now necessary us to obtain the data now required to test this working hypothesis, and we have the team and expertise to accomplish this 2yr-proposal.
This 2-year research project focuses on the preclinical development of a compelling therapeutic strategy testing a ?dual-action? drug FumET-CORM that contains controlled CO-releasing molecule unit (CORM) and methyl fumarate for the treatment of cerebral ischemia and elucidating the underlying mechanism of the activated cytoprotective Nrf2 pathway. The lab has pioneered to the documentation of the Nrf2 protective effects, especially once activated, and that exposure to low CO would be protective in stroke. We will now test whether such combined FumET-CORM drug would be beneficial in brain ischemia and start addressing potential cellular mechanisms of action. There are already various reports/trials of beneficial uses of therapeutic gases and also of dimethyl fumarate being used in the clinic, but this would likely be the first time that therapeutic use of such ?dual-action? drug would be tested to limit stroke outcomes in males and females.
