Department of Neuroscience, PO Box 100244, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610-0244, USA.
Brain Res. 2010 Mar 10;1319:131-41. doi: 10.1016/j.brainres.2009.12.089. Epub 2010 Jan 6.
The neuronal pathology caused by neonatal infection of rats with the PVC-211 murine leukemia virus (PVC-211 MuLV) and its underlying mechanisms are not well defined even though a loss of neurons and spongiform neurodegeneration has been reported to accompany the disease. Here we sought to identify sites of neurodegeneration using microglial reactivity as an indirect marker and to characterize microglial activation during disease progression. Using a panel of microglial antibodies including Iba1, OX-42, ED1, and anti-ferritin, we have studied the response of microglial cells to neonatal CNS infection with PVC-211 at post-infection survival times 7, 14, 21, and 28 days. We found that microglial activation occurred primarily in the spinal cord and brainstem where it gradually increased in intensity over the time course of this study. Other brain areas were relatively unremarkable in their microglial reaction to viral infection within this time frame. However, the presence of activated microglial cells was not correlated directly with the presence of viral glycoprotein (gp70), which was expressed in endothelial cells throughout the CNS. Although double-labeling of microglia with Iba1 and ED1 revealed numerous actively phagocytic microglia during disease progression, not all activated microglia were ED1-positive. In addition to the intense microglial activation, we found increased ferritin expression sporadically throughout the virus-infected brain. The ferritin-positive cells were mostly microglia that exhibited dystrophic changes and likely represented a degenerating subpopulation of microglial cells. Thus, activated microglia can co-exist with degenerating microglia in the same brain region. We attempted to localize degenerating neurons or neurites using Fluoro-Jade, anti-tau, and anti-alpha synuclein staining, but none of these procedures yielded results to indicate obvious neuronal pathology. We conclude that the visualization of microglial activation is a more sensitive measure of neuronal perturbations than direct detection of neuronal pathology which may be subtle and not produce overt degenerative changes.
尽管已有报道称，伴随该疾病会发生神经元丢失和海绵状神经退行性变，但仍不清楚大鼠感染 PVC-211 鼠白血病病毒（PVC-211 MuLV）引起的神经元病理学及其潜在机制。在这里，我们试图使用小胶质细胞反应作为间接标志物来确定神经退行性变的部位，并在疾病进展过程中表征小胶质细胞的激活。我们使用了包括 Iba1、OX-42、ED1 和抗铁蛋白在内的小胶质细胞抗体，研究了 PVC-211 对新生大鼠中枢神经系统感染后的小胶质细胞反应，感染后存活时间为 7、14、21 和 28 天。我们发现，小胶质细胞激活主要发生在脊髓和脑干，在本研究的时间过程中，其强度逐渐增加。在这个时间范围内，其他大脑区域的小胶质细胞对病毒感染的反应相对不明显。然而，激活的小胶质细胞的存在与病毒糖蛋白（gp70）的存在没有直接相关，gp70在整个中枢神经系统的内皮细胞中表达。虽然用 Iba1 和 ED1 对小胶质细胞进行双重标记显示，在疾病进展过程中有许多活跃的吞噬性小胶质细胞，但并非所有激活的小胶质细胞都是 ED1 阳性的。除了强烈的小胶质细胞激活外，我们还发现铁蛋白表达在感染病毒的大脑中散在增加。铁蛋白阳性细胞大多是表现出退行性变化的小胶质细胞，可能代表了小胶质细胞的一个退化亚群。因此，在同一脑区，激活的小胶质细胞可以与退化的小胶质细胞共存。我们试图使用 Fluoro-Jade、抗 tau 和抗 alpha 突触核蛋白染色来定位退化的神经元或神经突，但这些方法都没有产生明显的神经元病理学结果。我们得出结论，与直接检测可能微妙且不会产生明显退行性变化的神经元病理学相比，小胶质细胞激活的可视化是神经元扰动的更敏感指标。
