Abstract WMP74: Inhibition of T Cell Receptor Activation Improves Neurological Outcomes After Intracerebral Hemorrhage

Abstract

Purpose: We previously reported that activated T cells accumulate in the perihematomal regions after Intracerebral hemorrhage (ICH) and aggravate hemorrhagic brain injury. However, brain-infiltrating T cells precise activation mechanisms and resulting pathological impacts remain largely unexplored. This study aims to address these knowledge gaps. Methodology: ICH was induced via standard collagenase injection in male C57BL/6J mice (10 weeks old). Activation pathways of T cells were analyzed through single-cell RNA data (GSE230414). We assessed T cell receptor (TCR) activation, pro-inflammatory cytokines expression, and immune cell infiltration via flow cytometry and immunostaining at 1- and 3-days post-ICH. Neurobehavioral evaluations were conducted at 1-, 3-, 7-, and 14-days post-ICH. TCR activation was pharmacologically inhibited using the TCR-specific inhibitor AX-024, administered (10 mg/kg, i.p.) one hour after ICH. Results: Single-cell transcriptomic analysis revealed an upregulation of the TCR pathway in activated T cells following ICH in mice. Flow cytometry and immunostaining validated TCR activation markers (p-CD3, p-Zap70) in ICH mouse models. These findings suggest that TCR activation likely plays a central role in the activation of brain-infiltrating T cells. In the subsequent experiment, we explored the pathological implications of TCR activation on T cell activation, leukocyte brain infiltration, and neurological outcomes post-ICH. We found that administration of AX-024 substantially inhibited TCR activation (CD69 expression) and expression of pro-inflammatory cytokines (IL-17, IL-1β) in brain-infiltrating T cells at 1- and 3-days post-ICH. Notably, AX-024 administration also significantly decreased the infiltration of other leukocytes and remarkably enhanced long-term sensorimotor and cognitive function up to 14 days after ICH. Discussion: This study underscores TCR activation as a pivotal mechanism driving activation of brain-infiltrating T cells following ICH. Inhibiting TCR activation through AX-024 proves beneficial for improving neurological outcomes after ICH. However, further investigations are warranted to comprehensively elucidate the intricate underlying pathological mechanisms.