Analysis of isolated meninges and cerebrospinal fluid (CSF) of post-mortem MS cases has shown increased gene and protein expression for the pro-inflammatory cytokines: tumour necrosis factor (TNF) and interferon-γ (IFNγ). Here we tested the hypothesis that persistent production of these cytokines in the meningeal compartment and diffusion into underlying GM can drive chronic MS-like GM pathology. Lentiviral transfer vectors were injected into the sagittal sulcus of DA rats to deliver continuous expression of TNF + IFNγ transgenes in the meninges and the resulting neuropathology analysed after 1 and 2 months. Injection of TNF + IFNγ viral vectors, with or without prior MOG immunisation, induced extensive immune cell infiltration (CD4+ and CD8+ T-cells, CD79a + B-cells and macrophages) in the meninges by 28 dpi, which remained at 2 months. Control GFP viral vector did not induce infiltration. Subpial demyelination was seen underlying these infiltrates, which was partly dependant on prior myelin oligodendrocyte glycoprotein (MOG) immunisation. A significant decrease in neuronal numbers was seen at 28 and 56 days in cortical layers II-V that was independent of MOG immunisation. RNA analysis at 28 dpi showed an increase in expression of necroptotic pathway genes, including RIP3, MLKL, cIAP2 and Nox2. PhosphoRIP3+ and phosphoMLKL+ neurons were present in TNF + IFNγ vector injected animals, indicating activation of necroptosis. Our results suggest that persistent expression of TNF in the presence of IFNγ is a potent inducer of meningeal inflammation and can activate TNF signalling pathways in cortical cells leading to neuronal death and subpial demyelination and thus may contribute to clinical progression in MS.

中文翻译：

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鞘内促炎细胞因子的持续升高会导致多发性硬化症样皮质脱髓鞘和神经变性。

死后MS病例中分离出的脑膜和脑脊液（CSF）的分析显示促炎性细胞因子：肿瘤坏死因子（TNF）和干扰素-γ（IFNγ）的基因和蛋白质表达增加。在这里，我们测试了以下假设：这些细胞因子在脑膜区室中持续产生并扩散到潜在的GM中可以驱动慢性MS样GM病理。将慢病毒转移载体注射到DA大鼠的矢状沟中，以在脑膜中连续表达TNF +IFNγ转基因，并在1和2个月后分析所得的神经病理学。注射TNF +IFNγ病毒载体后，无论是否进行MOG免疫，在28 dpi时均可引起脑膜广泛的免疫细胞浸润（CD4 +和CD8 + T细胞，CD79a + B细胞和巨噬细胞），并持续2个月。对照GFP病毒载体不诱导浸润。在这些浸润液中发现了脊髓下脱髓鞘，这部分取决于先前的髓磷脂少突胶质细胞糖蛋白（MOG）免疫接种。在独立于MOG免疫的皮层II-V中，在28天和56天时神经元数量显着减少。28 dpi的RNA分析表明，包括RIP3，MLKL，cIAP2和Nox2在内的肾病通路基因的表达增加。注射了TNF +IFNγ载体的动物体内存在PhosphoRIP3 +和phosphoMLKL +神经元，表明坏死性肾病的激活。