Evaluation of a bi-modal therapy in a model of cerebral ischemia




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Purpose: Ischemic strokes are a significant contributor to cardiovascular-related deaths in the U.S. Currently, pharmacological interventions are limited to alteplase, an FDA-approved thrombolytic agent, or a surgical procedure known as a thrombectomy. However, their effectiveness is limited by a narrow therapeutic window and incomplete reperfusion rates. Our research explores an alternative strategy centered around PNU-120596 (PNU), a positive allosteric modulator of the alpha7 nicotinic acetylcholine receptor (a7 nAChR), which has shown promise in previous studies in a male rat stroke model. The a7 nAChR is expressed in various central nervous system cells, and studies suggest that PNU directly promotes neuroprotection in these cells. Furthermore, research indicates increased expression of the a7 nAChR in immune cells, specifically in activated inflammatory CD4 T-cells, a cell crucial in stroke studies. We hypothesize that PNU is a bi-modal therapeutic agent, addressing neuronal loss and inflammatory responses, presenting a unique advantage.

Methods: This study aims to provide insight into PNU's efficacy and regulatory role in stroke-induced inflammatory CD4 T-cells. The study will assess PNU treatment's efficacy in promoting stroke recovery in transient middle cerebral artery (tMCAO) mice, a murine stroke model, and investigate how PNU modulates stroke-induced inflammatory CD4 T-cells, examining their suppression, neuronal survival, and alleviation of the disease using mixed cortical cultures. Mice that had undergone the tMCAO procedure were administered 20mg/kg of PNU immediately after reperfusion, and brain tissue was collected 24 and 72 hours post-tMCAO for infarct analysis. Spleen and cervical lymph nodes were collected at the same time points for flow cytometry analysis.

Results: PNU reduces stroke infarct when administered immediately after tMCAO, and brain tissue is collected 24 hours post-tMCAO. However, protection is lost when the same dose is administered, and brain tissue is collected 72 hours post-tMCAO. No significant changes in levels of CD4 T-cell percentages were seen in the spleen or cervical lymph nodes at both time points.

Conclusion: This study suggests that PNU reduces infarct volume immediately 24 hours post-tMCAO, but the protection is lost at 72 hours post-tMCAO. However, subsequent studies are necessary to assess the efficacy of PNU at longer time points with different dosages.