Analysis of sex specific differences in glial cells affecting macrophage invasion of the fly brain

为了确保脑内适当的稳态功能，神经系统通过由神经胶质细胞或内皮细胞形成的血脑屏障（BBB）与循环系统分开。此外，血脑屏障防止病原体和免疫细胞的入侵。由于其与循环的有效分离，神经系统被认为是免疫特权器官。因此，特定的细胞防御机制已经发展到科普感染和清除CNS内的细胞碎片。在无脊椎动物中，以前认为CNS神经胶质细胞清除细胞碎片，而巨噬细胞主要在血淋巴中对抗病原体。 然而，正如我们最近所证明的，血淋巴衍生的巨噬细胞也能够侵入发炎的苍蝇脑，在那里它们穿过CNS的两个单独的屏障：由神经束膜和神经束膜下胶质细胞形成的血脑屏障和由成鞘胶质细胞形成的神经鞘周围的屏障。令人惊讶的是，我们发现巨噬细胞比女性更容易侵入男性大脑。初步数据表明，这是由于血脑屏障的性别特异性差异。在这里，我们想破译神经胶质细胞分化中性别特异性差异的潜在机制，以及这如何影响巨噬细胞的侵袭。以前的测序项目已经确定了几个候选人在这些神经胶质细胞中以性别特异性方式表达。我们将测试这些基因是否使男性大脑在神经胶质免疫诱导后更容易受到巨噬细胞入侵。为了彻底解决CNS不同胶质细胞的性别特异性差异，我们将在巨噬细胞侵袭相关的时间段进行序列分析。然后对候选基因进行分析。

To ensure proper homeostatic function within the brain, the nervous system is separated from the circulatory system by the blood-brain barrier (BBB) which is either formed by glial or endothelial cells. In addition, the BBB prevents the invasion of pathogens and immune cells. Due to its efficient separation from circulation, the nervous system is considered an immune-privileged organ. Thus, specific cellular defense mechanisms have evolved to cope with infections and the removal of cellular debris within the CNS. In invertebrates, it was previously thought that CNS glial cells clear cellular debris, whereas macrophages fight pathogens primarily in the hemolymph. However, as we recently demonstrated, hemolymph-derived macrophages are also able to invade an inflamed fly brain, where they cross two separate barriers of the CNS: The blood-brain barrier formed by perineurial and the subperineurial glial cells and an barrier around the neuropil formed by the ensheathing glia. Surprisingly, we found that macrophages invade the male brain more easily than the female brain. Preliminary data suggest that this is due to sex-specific differences in the blood-brain barrier. Here we want to decipher the mechanisms underlying sex-specific differences in glial differentiation and how this could influence macrophage invasion. Previous sequencing projects have identified several candidates expressed in a sex specific manner in these glial cells. We will test whether these genes make male brains more susceptible to macrophage invasion upon glial immunity induction. To thoroughly address sex-specific differences in the different glial cells of the CNS, we will perform sequence analyses at time periods relevant for macrophage invasion. Candidate genes will then be analyzed.