Signaling from central nervous system (CNS)-infiltrating lymphocytes and macrophages is critical to activate microglia and cause tissue damage in multiple sclerosis (MS). We combined laser microdissection with high-throughput real time RT-PCR to investigate separately the CNS exogenous and endogenous inflammatory components in postmortem brain tissue of progressive MS cases. A previous analysis of immune infiltrates isolated from the white matter (WM) and the meninges revealed predominant expression of genes involved in antiviral and cytotoxic immunity, including IFNγ and TNF. Here, we assessed the expression of 71 genes linked to IFN and TNF signaling and microglia/macrophage activation in the parenchyma surrounding perivascular cuffs at different stages of WM lesion evolution and in gray matter (GM) lesions underlying meningeal infiltrates. WM and GM from non-neurological subjects were used as controls. Transcriptional changes in the WM indicate activation of a classical IFNγ-induced macrophage defense response already in the normal-appearing WM, amplification of detrimental (proinflammatory/pro-oxidant) and protective (anti-inflammatory/anti-oxidant) responses in actively demyelinating WM lesions and persistence of these dual features at the border of chronic active WM lesions. Transcriptional changes in chronic subpial GM lesions indicate skewing toward a proinflammatory microglia phenotype. TNF receptor 2 (TNFR2) mediating TNF neuroprotective functions was one of the genes upregulated in the MS WM. Using immunohistochemistry we show that TNFR2 is highly expressed in activated microglia in the normal-appearing WM, at the border of chronic active WM lesions, and in foamy macrophages in actively demyelinating WM and GM lesions. In lysolecithin-treated mouse cerebellar slices, a model of demyelination and remyelination, TNFR2 RNA and soluble protein increased immediately after toxin-induced demyelination along with transcripts for microglia/macrophage-derived pro- and anti-inflammatory cytokines. TNFR2 and IL10 RNA and soluble TNFR2 protein remained elevated during remyelination. Furthermore, myelin basic protein expression was increased after selective activation of TNFR2 with an agonistic antibody. This study highlights the key role of cytotoxic adaptive immunity in driving detrimental microglia activation and the concomitant healing response. It also shows that TNFR2 is an early marker of microglia activation and promotes myelin synthesis, suggesting that microglial TNFR2 activation can be exploited therapeutically to stimulate CNS repair.

来自中枢神经系统（CNS）浸润的淋巴细胞和巨噬细胞的信号对于激活小胶质细胞并引起多发性硬化症（MS）的组织损害至关重要。我们将激光显微切割技术与高通量实时RT-PCR结合起来，分别研究进行性MS患者死后脑组织中的CNS外源性和内源性炎症成分。先前对从白质（WM）和脑膜分离出的免疫浸润液进行的分析表明，与抗病毒和细胞毒性免疫有关的基因主要表达，包括IFNγ和TNF。在这里，我们评估了71个与IFN和TNF信号以及小胶质细胞/巨噬细胞活化相关的基因在WM病变发展的不同阶段以及在脑膜浸润的灰质（GM）病变周围血管周围的薄壁组织中的表达。来自非神经科受试者的WM和GM用作对照。WM中的转录变化表明在正常出现的WM中已经存在经典的IFNγ诱导的巨噬细胞防御反应的激活，在主动脱髓鞘WM中有害（促炎/抗氧化剂）反应和保护性（抗炎/抗氧化）反应的扩增。病灶和这些双重特征在慢性活动性WM病灶的边界处持续存在。慢性鼻下GM病变的转录变化表明其趋向于促炎性小胶质细胞表型。介导TNF神经保护功能的TNF受体2（TNFR2）是MS WM中上调的基因之一。使用免疫组织化学，我们显示TNFR2在正常出现的WM中处于活化的小胶质细胞中的高度表达，处于慢性活动性WM病变的边界，并在泡沫巨噬细胞中使WM和GM病变主动脱髓鞘。在溶血卵磷脂处理过的小鼠小脑切片中，脱髓鞘和再髓鞘形成的模型，毒素诱导的脱髓鞘后，TNFR2 RNA和可溶性蛋白随小胶质细胞/巨噬细胞衍生的促炎和抗炎细胞因子的转录本增加。在髓鞘再生过程中，TNFR2和IL10 RNA和可溶性TNFR2蛋白保持升高。此外，在用激动性抗体选择性激活TNFR2后，髓磷脂碱性蛋白表达增加。这项研究强调了细胞毒性适应性免疫在驱动有害小胶质细胞活化和伴随的愈合反应中的关键作用。它还表明TNFR2是小胶质细胞活化的早期标志物，并促进髓磷脂的合成，