Institute for Stroke and Dementia Research

Project description:

Stroke-induced brain injury leads to neuronal cell death, which subsequently triggers an inflammatory response critical for tissue repair but potentially detrimental if prolonged. One type of cell death, lytic cell death, involves the rupture of the cell membrane, releasing intracellular contents that act as danger signals to the immune system, intensifying neuroinflammation. Recent studies suggest that the molecule Ninjurin-1 (Ninj1) plays a role in mediating membrane rupture in lytic cell death, particularly after ischemic injury.

This project will investigate the hypothesis that Ninj1-mediated membrane rupture elicits a stronger and more sustained neuroinflammatory response post-stroke compared to less immunogenic forms of cell death. Understanding the role of Ninj1 in post-stroke inflammation and recovery could identify new targets for therapeutic interventions aimed at mitigating chronic neuroinflammation and promoting functional recovery.

Objectives of this project involve:

1. To determine the neuroinflammatory profile following Ninj1-mediated membrane rupture post-stroke using wild-type, Ninj1-deficient animal models, and Ninj1-neutralizing antibodies.
2. To assess the time course of inflammatory response at various stages post-stroke, focusing on acute, sub-acute, and chronic phases.
3. To evaluate functional recovery and inflammation resolution, investigating if Ninj1-driven neuroinflammation affects behavioral outcomes and recovery trajectories.

Experimental Design and Methods:

The experimental design involves using both wild-type and Ninj1-deficient animal models, with additional cohorts receiving neutralizing antibodies to Ninj1, to investigate its role in the neuroinflammatory response following ischemic stroke. Stroke will be induced using the middle cerebral artery occlusion (MCAO) model, and inflammation will be assessed at multiple time points (24h, 3d, 7d, 14d, and 28d) using flow cytometry, immunohistochemistry, and cytokine profiling to quantify immune cell activity and inflammatory mediators in brain tissue and serum. Advanced in vivo imaging techniques like two-photon microscopy and MRI will track inflammation and cellular responses in real-time, while behavioral tests, including rotarod, open field, and neurological scoring, will assess motor and cognitive recovery over time. Comparative analyses across wild-type, Ninj1-deficient, and antibody-treated groups will evaluate if Ninj1 modulation can reduce neuroinflammation, promote faster inflammation resolution, and improve functional recovery outcomes.

Expected Outcomes:

We expect that Ninj1-mediated membrane rupture will amplify neuroinflammatory responses post-stroke, leading to prolonged inflammation and delayed functional recovery. Reducing Ninj1 activity may lessen chronic neuroinflammation and enhance recovery outcomes. These findings could provide novel insights into therapeutic strategies aimed at modulating neuroinflammation in stroke patients.

Significance:

This research could illuminate the mechanisms by which specific forms of cell death impact post-stroke neuroinflammation and recovery. Targeting Ninj1-mediated pathways may offer a new approach to mitigating excessive inflammation, potentially reducing secondary brain damage and improving post-stroke recovery.