Department of Molecular Cell Mechanisms, Medical University of Lodz, Mazowiecka Str. 6/8, Lodz, 92- 215, Poland.
Department of Structural Biology, Medical University of Lodz, Żeligowskiego Str. 7/9, Lodz, 90-752, Poland.
Cell Commun Signal. 2024 May 28;22(1):296. doi: 10.1186/s12964-024-01665-z.
The SARS-CoV-2 virus causes severe COVID-19 in one-fifth of patients. In addition to high mortality, infection may induce respiratory failure and cardiovascular complications associated with inflammation. Acute or prolonged inflammation results in organ fibrosis, the cause of which might be endothelial disorders arising during the endothelial-mesenchymal transition (EndMT).
HUVECs and HMEC-1 cells were stimulated with SARS-CoV-2 S (Spike) and N (Nucleocapsid) proteins, and EndMT induction was evaluated by studying specific protein markers via Western blotting. Wound healing and tube formation assays were employed to assess the potential of SARS-CoV-2 to stimulate changes in cell behaviour. MRTF nuclear translocation, ROS generation, TLR4 inhibitors, TGF-β-neutralizing antibodies, and inhibitors of the TGF-β-dependent pathway were used to investigate the role of the TGF-β-MRTF signalling axis in SARS-CoV-2-dependent EndMT stimulation.
Both viral proteins stimulate myofibroblast trans-differentiation. However, the N protein is more effective at EndMT induction. The TGF-β-MRTF pathway plays a critical role in this process. The N protein preferentially favours action through TGF-β2, whose secretion is induced through TLR4-ROS action. TGF-β2 stimulates MRTF-A and MRTF-B nuclear translocation and strongly regulates EndMT. In contrast, the Spike protein stimulates TGF-β1 secretion as a result of ACE2 downregulation. TGF-β1 induces only MRTF-B, which, in turn, weakly regulates EndMT. Furthermore, aspirin, a common nonsteroidal anti-inflammatory drug, might prevent and reverse SARS-CoV-2-dependent EndMT induction through TGF-β-MRTF pathway deregulation.
The reported study revealed that SARS-CoV-2 infection induces EndMT. Moreover, it was demonstrated for the first time at the molecular level that the intensity of the EndMT triggered by SARS-CoV-2 infection may vary and depend on the viral protein involved. The N protein acts through TLR4-ROS-TGF-β2-MRTF-A/B, whereas the S protein acts through ACE2-TGF-β1-MRTF-B. Furthermore, we identified aspirin as a potential anti-fibrotic drug for treating patients with SARS-CoV-2 infection.
SARS-CoV-2 病毒可导致五分之一的 COVID-19 患者出现重症。除了高死亡率外，感染还可能导致与炎症相关的呼吸衰竭和心血管并发症。急性或长期炎症会导致器官纤维化，其原因可能是内皮-间充质转化（EndMT）过程中出现的内皮障碍。
用 SARS-CoV-2 的 S（刺突）和 N（核衣壳）蛋白刺激 HUVECs 和 HMEC-1 细胞，通过 Western blot 研究特定的蛋白标记物来评估 EndMT 诱导情况。采用划痕愈合和管形成实验来评估 SARS-CoV-2 刺激细胞行为改变的潜力。使用 MRTF 核易位、ROS 生成、TLR4 抑制剂、TGF-β中和抗体和 TGF-β 依赖途径抑制剂来研究 TGF-β-MRTF 信号轴在 SARS-CoV-2 依赖的 EndMT 刺激中的作用。
两种病毒蛋白都能刺激成纤维细胞向肌成纤维细胞的转分化，但 N 蛋白在诱导 EndMT 方面更有效。TGF-β-MRTF 途径在此过程中起着关键作用。N 蛋白优先通过 TLR4-ROS 作用诱导 TGF-β2 分泌，从而发挥作用。TGF-β2 刺激 MRTF-A 和 MRTF-B 核易位，并强烈调节 EndMT。相比之下，S 蛋白下调 ACE2 后会刺激 TGF-β1 分泌。TGF-β1 仅诱导 MRTF-B，进而弱调节 EndMT。此外，常用的非甾体抗炎药阿司匹林可能通过 TGF-β-MRTF 途径失调控来预防和逆转 SARS-CoV-2 依赖的 EndMT 诱导。
该研究表明，SARS-CoV-2 感染可诱导 EndMT。此外，该研究还首次从分子水平上证明，SARS-CoV-2 感染引发的 EndMT 强度可能有所不同，并取决于所涉及的病毒蛋白。N 蛋白通过 TLR4-ROS-TGF-β2-MRTF-A/B 发挥作用，而 S 蛋白则通过 ACE2-TGF-β1-MRTF-B 发挥作用。此外，我们发现阿司匹林可能是治疗 SARS-CoV-2 感染患者的一种潜在抗纤维化药物。
