Sex differences in brain inflammation in experimental stroke

描述(由申请者提供)：很少有中风实验室研究雌性动物或使用特定性别的缺血性脑损伤细胞模型。在一定程度上，这是由于历史上的假设，即男性和女性的细胞/分子损伤和修复机制是相同的。两性持续缺乏临床前动物数据，这给将在女性和男性身上测试新疗法的临床试验人员带来了严重的证据差距。在这一应用中，我们验证了最重要的假设，即脑和外周免疫系统之间的缺血后炎症循环的演变受到生物性别的强烈影响，包括性二态免疫细胞亚群和影响局灶性脑缺血后脑-脾-脑的炎症细胞循环的关键炎症机制。目标1将测试 假设进行性脑缺血损伤导致脾损伤，同时伴有脑微血管和实质炎症，这一假说更为深刻，并由男性和女性不同的免疫细胞群(单核细胞和T淋巴细胞)介导。目的2确定女性脑缺血后T淋巴细胞介导的损伤是否由于T淋巴细胞中过氧化体增殖物激活受体α水平降低而加重。这些假说预测：(A)虽然脾切除通过消除在脾内滋养的免疫细胞而使受伤的男女大脑受益，但将对局灶性脑缺血敏感的女性和男性T淋巴细胞过继转移到切除脾的同性受体体内，选择性地增加了女性MCAO后的脑损伤，因此女性对T淋巴细胞介导的损伤的脆弱性部分是由于缺乏保护性PPAR信号机制。目的3将评估单核细胞从脾到脑缺血后的转运是否具有性别特异性。假设：(A)相对于雌性小鼠，雄性小鼠在脑缺血后表现出更早和更强劲的CD45HighCD11b+巨噬细胞和CD11c+树突状细胞的募集；(B)这种募集部分是由于雄性单核细胞中基质金属蛋白酶-9的高表达，从而促进了它们的迁移；(C)缺乏CD11b+(巨噬细胞“敲除”)或CD11c+髓系细胞(树突状细胞“敲除”)的雄性小鼠将比雌性小鼠在局灶性脑缺血后从这些细胞的丢失中获得更大的好处。因此，这项应用的发现可能会导致中风新疗法的发展，例如女性使用PPAR？激动剂，男性使用基质金属蛋白酶-9拮抗剂。

DESCRIPTION (provided by applicant): Few stroke laboratories study female animals or use cell models of ischemic brain injury that are sex-specific. In part, this is due to the historical assumption that cellular/molecular injury and repair mechanisms are the same in males vs. females. The persistent lack of pre-clinical animal data in both sexes poses a severe evidence gap for clinical trialists who will test new therapies in women and men. In this application, we test the overarching hypothesis that the evolution of post-ischemic inflammatory cycling between the brain and peripheral immune system is strongly influenced by biological sex, including sexually dimorphic immune cell subsets and key inflammatory mechanisms that affect brain-spleen-brain cycling of inflammatory cells after focal cerebral ischemia. Aim 1 will test the hypotheses that evolving cerebral ischemic injury elicits splenic damage in tandem with brain microvascular and parenchymal inflammation that is more profound and is mediated by different immunocyte populations (monocytes vs. T lymphocytes) in males vs. females. Aim 2 determines if T lymphocyte-mediated injury in post-ischemic brain is greater in females due to lower levels of peroxisome proliferator activated receptor alpha (PPAR¿) in T lymphocytes. These hypotheses predict that (a) while splenectomy benefits the injured brain of both sexes by eliminating immunocytes nurtured within the spleen, adoptive transfer of female vs. male T lymphocytes sensitized to focal cerebral ischemia into splenectomized same sex recipients selectively increases female cerebral damage more so than males following MCAO and that (b) female vulnerability to T lymphocyte-mediated injury is due in part to a lack of protective PPAR¿ signaling mechanisms. Aim 3 will evaluate whether monocyte trafficking from spleen to post- ischemic brain is sex-specific. The hypotheses are that (a) males exhibit an early and more robust recruitment of CD45highCD11b+ macrophages and CD11c+ dendritic cells into post-ischemic brain relative to females; (b) this recruitment is due in part to higher matrix metalloproteinase (MMP)-9 expression in male monocytes, thus facilitating their transmigration; (c) male mice deficient in CD11b+ (macrophage "knockout") or in CD11c+ myeloid cells (dendritic cell "knockout") will more greatly benefit by loss of these cells than will females following focal cerebral ischemia. Findings from this application could therefore lead to the development of new therapies for stroke such as PPAR¿ agonists for females and MMP-9 antagonists for males.