ABSTRACT NUMBER: ESOC2026A2027 DOUBLE-NEGATIVE T CELLS ATTENUATE POST-STROKE COGNITIVE IMPAIRMENT BY TARGETING MATURE B LYMPHOCYTES VIA THE NKG2D-RAE1 PATHWAY

Abstract Background and aims Whilst we have previously demonstrated adoptive transfer of double negative T (DNT) cells ameliorates ischaemic stroke, their role in post-stroke cognitive impairment (PSCI) remains unclear. Although antibody deposition is implicated in PSCI pathogenesis, the contribution of mature B lymphocytes has not been defined. We therefore aimed to determine whether DNT cells therapy could alleviate PSCI by modulating mature B lymphocytes. Methods PSCI was induced in mice via distal of Middle Cerebral Artery Occlusion plus hypoxia. Brain-infiltrating mature B lymphocytes and antibody deposition were assessed. A subgroup of PSCI mice received adoptive transfer of DNT cells; cognitive function and hippocampal long-term potentiation (LTP) were analysed. Direct interaction was examined in a co-culture system, where proliferation and apoptosis of mature B lymphocytes were measured after exposure to DNT cells. The specific role of the NKG2D-Rae1 pathway was validated via using NKG2D-knockout mice and Rae1-blocking antibodies. Results PSCI mice exhibited significant mature B lymphocytes infiltration into the brain parenchyma and pathological antibody deposition in the hippocampus and cortex. Adoptive transfer of DNT cells improved spatial memory and hippocampal LTP. DNT cells also promoted apoptosis and inhibited proliferation of mature B lymphocytes via NKG2D-Rae1 pathway, decreasing antibody deposition in the hippocampus and cortex. Conclusions DNT cells attenuate PSCI by suppressing mature B lymphocytes activation via the NKG2D-Rae1 pathway, reducing sustained deposition of deleterious antibodies in critical brain regions. These findings highlight adoptive transfer of DNT cells as a promising therapeutic strategy for PSCI. Conflict of interest Zhiyu Leng, Xiaoyi Jiang, Ming Yuan, Qinxue Sun, Yuhualei Pan, Gang Li:nothing to disclose Figure 1 - belongs to Conclusions