Transsynaptic transport is the most accepted proposal to explain the SARS-CoV-2 infection of the CNS. Nevertheless, emerging evidence shows that neurons do not express the SARS-CoV-2 receptor ACE2, which highlights the importance of the blood-brain barrier (BBB) in preventing virus entry to the brain. In this study, we examine the presence of SARS-CoV-2 messenger ribonucleic acid (mRNA) and the cytokine profile in cerebrospinal fluids (CSF) from two patients with a brain tumor and COVID-19. To determine the BBB damage, we evaluate the Q- albumin index, which is an indirect parameter to assess the permeability of this structure. The Q-albumin index of the patient with an intraventricular brain tumor suggests that the BBB is undamaged, preventing the passage of SARS-CoV-2 and pro-inflammatory molecules. The development of brain tumors that disrupt the BBB (measured by the Q-albumin index), in this case, a petroclival meningioma (Case 1), allows the free passage of the SARS-CoV-2 virus and probably lets the free transit of pro-inflammatory molecules to the CNS, which leads to a possible activation of the microglia (astrogliosis) and an exacerbated immune response represented by IL-13, IFN-γ, and IL-2 trying to inhibit both the infection and the carcinogenic process.

中文翻译：

---

血脑屏障损伤是 SARS-CoV-2 感染中枢神经系统的关键。

跨突触转运是解释中枢神经系统 SARS-CoV-2 感染的最被接受的提议。尽管如此，新出现的证据表明神经元不表达 SARS-CoV-2 受体 ACE2，这突出了血脑屏障 (BBB) 在防止病毒进入大脑中的重要性。在这项研究中，我们检查了两名患有脑肿瘤和 COVID-19 的患者脑脊液 (CSF) 中是否存在 SARS-CoV-2 信使核糖核酸 (mRNA) 和细胞因子谱。为了确定 BBB 损伤，我们评估 Q-白蛋白指数，这是评估该结构渗透性的间接参数。脑室内肿瘤患者的 Q-白蛋白指数表明 BBB 未受损，阻止了 SARS-CoV-2 和促炎分子的通过。