Universidade Estadual Paulista - UNESP, Departmento de Ciências Biológicas, Assis, SP, Brasil.
Universidade Estadual Paulista - UNESP, Programa de Pós-Graduação em Microbiologia, São José do Rio Preto, SP, Brasil.
Braz J Biol. 2021 Oct 11;83:e248717. doi: 10.1590/1519-6984.248717. eCollection 2021.
The human respiratory syncytial virus (hRSV) is the most common cause of severe lower respiratory tract diseases in young children worldwide, leading to a high number of hospitalizations and significant expenditures for health systems. Neutrophils are massively recruited to the lung tissue of patients with acute respiratory diseases. At the infection site, they release neutrophil extracellular traps (NETs) that can capture and/or inactivate different types of microorganisms, including viruses. Evidence has shown that the accumulation of NETs results in direct cytotoxic effects on endothelial and epithelial cells. Neutrophils stimulated by the hRSV-F protein generate NETs that are able to capture hRSV particles, thus reducing their transmission. However, the massive production of NETs obstructs the airways and increases disease severity. Therefore, further knowledge about the effects of NETs during hRSV infections is essential for the development of new specific and effective treatments. This study evaluated the effects of NETs on the previous or posterior contact with hRSV-infected Hep-2 cells. Hep-2 cells were infected with different hRSV multiplicity of infection (MOI 0.5 or 1.0), either before or after incubation with NETs (0.5-16 μg/mL). Infected and untreated cells showed decreased cellular viability and intense staining with trypan blue, which was accompanied by the formation of many large syncytia. Previous contact between NETs and cells did not result in a protective effect. Cells in monolayers showed a reduced number and area of syncytia, but cell death was similar in infected and non-treated cells. The addition of NETs to infected tissues maintained a similar virus-induced cell death rate and an increased syncytial area, indicating cytotoxic and deleterious damages. Our results corroborate previously reported findings that NETs contribute to the immunopathology developed by patients infected with hRSV.
人呼吸道合胞病毒（hRSV）是全球儿童严重下呼吸道疾病的最常见病因，导致大量住院和卫生系统的重大支出。大量中性粒细胞募集到患有急性呼吸道疾病的患者的肺组织中。在感染部位，它们释放中性粒细胞胞外诱捕网（NETs），可以捕获和/或失活包括病毒在内的不同类型的微生物。有证据表明，NETs 的积累会对内皮细胞和上皮细胞造成直接的细胞毒性作用。hRSV-F 蛋白刺激的中性粒细胞产生能够捕获 hRSV 颗粒的 NETs，从而降低其传播。然而，大量 NETs 的产生会阻塞气道并增加疾病的严重程度。因此，进一步了解 NETs 在 hRSV 感染过程中的作用对于开发新的特异性和有效的治疗方法至关重要。本研究评估了 NETs 对之前或之后与 hRSV 感染的 Hep-2 细胞接触的影响。Hep-2 细胞用不同的 hRSV 感染复数（MOI 0.5 或 1.0）感染，要么在与 NETs（0.5-16 μg/mL）孵育之前，要么之后。感染和未处理的细胞显示细胞活力降低，台盼蓝染色强烈，伴随着许多大合胞体的形成。NETs 与细胞之前的接触没有产生保护作用。单层细胞中的合胞体数量和面积减少，但感染和未处理的细胞的细胞死亡相似。将 NETs 添加到感染组织中保持了相似的病毒诱导的细胞死亡率和增加的合胞体面积，表明细胞毒性和有害损伤。我们的结果证实了先前报道的发现，即 NETs 有助于感染 hRSV 的患者发展的免疫病理学。
