B Cells Directly Alter Adaptive Plasticity to Support Functional Recovery After Stroke

R 01更新的中心假设集中在B细胞亚群上，该亚群提供神经营养支持以对抗缺血性卒中后的认知障碍并改善运动功能，这是血管对认知障碍和痴呆（VCID）发展的关键风险因素。这些神经营养性B细胞分泌脑源性神经营养因子（BDNF），可能是对抗VCID发展的关键。不幸的是，中风风险最高的患者群体和VCID老年人的B细胞发育和生长因子分泌受损，这可能会限制对中风后抑郁和痴呆的保护。性别也是一个因素，因为中风后痴呆的老年女性循环BDNF水平最低，尽管之前没有研究将神经营养免疫细胞群的丧失与VCID的发展直接联系起来。基于我们的试验数据，我们将测试：中风后B细胞的子集（即B细胞BDNF+）是否在遇到谷氨酸后上调BDNF; B细胞BDNF+是否限制VCID的发展并支持运动恢复;以及老年女性中B细胞来源的BDNF是否受损。我们将使用4个MOS。（“年轻”）和16个月。（“老年”）雌性和雄性小鼠以测试B细胞BDNF+是否支持中风后的神经元功能、可塑性、运动和多领域认知恢复。目的1将测试中风后，（1A）谷氨酸是否与B细胞结合以增加BDNF的产生并驱动与性别和年龄依赖性的恢复相关的细胞内Ca 2+信号传导。我们将（1 B）在体外使用B细胞Ntrk 2 tm 1 Ddg/J来测试BDNF受体Trk B是否是BDNF产生和体外神经保护所必需的。目的2将测试B细胞BDNF+是否支持远距离可塑性，以及初级运动皮层（M1）光血栓中风模型中的认知和运动恢复。在年轻和老年雌性hCD 20 TamCre/BDNF fl/fl小鼠和同窝对照中，（2A）所有B细胞或（2B）特异性B细胞衍生的BDNF的诱导性耗竭将发生急性（第0天）或延迟（中风后第7天开始）。主要结局将包括1）在自动触摸屏任务上保留巴甫洛夫刺激-学习器学习，2）改善前肢精确到达，以及3）梗死周围和对侧病灶M1可塑性。目标3将测试B细胞衍生的BDNF是否增强长期的认知和运动恢复。从中风后第7天开始，老年C57 BL/6 J雌性小鼠将接受tMCAo或假手术和（3A）过表达BDNF或（3B）缺乏BDNF的B细胞的过继转移，后者来源于hCD 20 TamCre/BDNF fl/fl供体小鼠。主要结局将包括1）通过触摸屏模式分离测试的大脑特异性认知缺陷改善，2）熟练触及的精确度提高，以及3）通过全脑连续双光子断层扫描确定的B细胞的局部同病灶和对病灶渗出，其与脑回路特异性认知功能和运动恢复的动物内幅度相关。这些研究将证实，在发生VCID的女性中，一种新的B细胞亚群（B细胞BDNF+）的年龄依赖性损失。他们还将证实，治疗靶向B细胞可以对抗中风后痴呆和运动缺陷，这是一种潜在的治疗方法，支持任何中枢神经系统损伤或疾病后基于可塑性的恢复。

The central hypothesis of this R01 renewal focuses on a subset of B cells that provide neurotrophic support to counter cognitive impairment and improve motor function after ischemic stroke, a key risk factor for the development of vascular contributions to cognitive impairment and dementia (VCID). These neurotrophic B cells secrete brain-derived neurotrophic factor (BDNF) and may be critical to countering the development of VCID. Unfortunately, the patient population most at risk for stroke and VCID aged individuals have impaired B cell development and secretion of growth factors that could limit protection from post-stroke depression and dementia. Sex is also a factor, as elderly women with post-stroke dementia have the lowest levels of circulating BDNF, though no prior studies have directly linked a loss of neurotrophic immune cell populations and the development of VCID. Based on our pilot data, we will test: if a subset of post-stroke B cells (i.e. B cellsBDNF+) upregulate BDNF after encountering glutamate; if B cellsBDNF+ limit the development of VCID and support motor recovery; and if B cell-derived BDNF is impaired in aged females. We will use 4 mos. (“young”) and 16 mos. (“aged”) female and male mice to test if B cellsBDNF+ support neuronal function, plasticity, motor, and multi-domain cognitive recovery post-stroke. Aim 1 will test if after stroke, (1A) glutamate binds to B cells to increase BDNF production and drive recovery-linked intracellular Ca2+ signaling that is sex- and age-dependent. We will (1B) use B cellsNtrk2tm1Ddg/J in vitro to test if the BDNF receptor TrkB is required for BDNF production and in vitro neuroprotection. Aim 2 will test if B cellsBDNF+ support remote plasticity, as well as cognitive and motor recovery in a primary motor cortex (M1) photothrombosis stroke model. Inducible depletion of (2A) all B cells or (2B) specific B cell-derived BDNF in young and aged female hCD20TamCre/ BDNFfl/fl mice and littermate controls will occur either acute (day 0) or delayed (beginning day 7 post-stroke). Primary outcomes will include 1) preservation of Pavlovian stimulus-reinforcer learning on an automated touchscreen task, 2) improved forelimb precision reaching, and 3) peri-infarct and contralesional M1 plasticity. Aim 3 will test if B cell-derived BDNF augments long-term cognitive and motor recovery. Aged C57BL/6J female mice will receive tMCAo or sham surgery and adoptive transfer of B cells that (3A) overexpress BDNF or (3B) lack BDNF, the latter derived from hCD20TamCre/BDNFfl/fl donor mice, beginning day 7 post-stroke. Primary outcomes will include 1) ameliorated hippocampal-specific cognitive deficits tested via touchscreen pattern separation, 2) improved precision skilled reaching, and 3) regional ipsi- and contralesional diapedesis of B cells, as determined via whole brain serial two-photon tomography, that correlates to within-animal magnitude of brain circuit-specific cognitive function and motor recovery. These studies will confirm an age-dependent loss of a novel subset of B cells, B cellsBDNF+, in females that develop VCID. They will also confirm that therapeutically targeting B cells can counter post-stroke dementia and motor deficits a potential treatment supporting plasticity-based recovery after any CNS injury or disease.