Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, People's Republic of China.
PLoS One. 2010 Jan 15;5(1):e8713. doi: 10.1371/journal.pone.0008713.
Influenza H5N1 virus continues to be enzootic in poultry and transmits zoonotically to humans. Although a swine-origin H1N1 virus has emerged to become pandemic, its virulence for humans remains modest in comparison to that seen in zoonotic H5N1 disease. As human respiratory epithelium is the primary target cells for influenza viruses, elucidating the viral tropism and host innate immune responses of influenza H5N1 virus in human bronchial epithelium may help to understand the pathogenesis. Here we established primary culture of undifferentiated and well differentiated normal human bronchial epithelial (NHBE) cells and infected with highly pathogenic influenza H5N1 virus (A/Vietnam/3046/2004) and a seasonal influenza H1N1 virus (A/Hong Kong/54/1998), the viral replication kinetics and cytokine and chemokine responses were compared by qPCR and ELISA. We found that the in vitro culture of the well differentiated NHBE cells acquired the physiological properties of normal human bronchi tissue which express high level of alpha2-6-linked sialic acid receptors and human airway trypsin-like (HAT) protease, in contrast to the low expression in the non-differentiated NHBE cells. When compared to H1N1 virus, the H5N1 virus replicated more efficiently and induced a stronger type I interferon response in the undifferentiated NHBE cells. In contrast, in well differentiated cultures, H5N1 virus replication was less efficient and elicited a lower interferon-beta response in comparison with H1N1 virus. Our data suggest that the differentiation of bronchial epithelial cells has a major influence in cells' permissiveness to human H1N1 and avian H5N1 viruses and the host innate immune responses. The reduced virus replication efficiency partially accounts for the lower interferon-beta responses in influenza H5N1 virus infected well differentiated NHBE cells. Since influenza infection in the bronchial epithelium will lead to tissue damage and associate with the epithelium regeneration, the data generated from the undifferentiated NHBE cultures may also be relevant to disease pathogenesis.
H5N1 流感病毒在禽类中持续存在，并通过动物源性途径传播给人类。尽管一种源自猪的 H1N1 病毒已经出现并成为大流行，但与动物源性 H5N1 疾病相比，其对人类的毒力仍然较低。由于人类呼吸道上皮细胞是流感病毒的主要靶细胞，阐明流感 H5N1 病毒在人支气管上皮细胞中的病毒嗜性和宿主固有免疫反应可能有助于了解发病机制。在这里，我们建立了未分化和分化良好的正常人类支气管上皮（NHBE）细胞的原代培养，并感染了高致病性流感 H5N1 病毒（A/Vietnam/3046/2004）和季节性流感 H1N1 病毒（A/Hong Kong/54/1998），通过 qPCR 和 ELISA 比较了病毒复制动力学和细胞因子及趋化因子反应。我们发现，分化良好的 NHBE 细胞的体外培养获得了正常人类支气管组织的生理特性，表达高水平的α2-6 连接唾液酸受体和人气道胰蛋白酶样（HAT）蛋白酶，而未分化的 NHBE 细胞表达水平较低。与 H1N1 病毒相比，H5N1 病毒在未分化的 NHBE 细胞中更有效地复制，并诱导更强的 I 型干扰素反应。相比之下，在分化良好的培养物中，与 H1N1 病毒相比，H5N1 病毒的复制效率较低，诱导的干扰素-β反应较低。我们的数据表明，支气管上皮细胞的分化对细胞对人 H1N1 和禽源 H5N1 病毒的易感性和宿主固有免疫反应有重大影响。病毒复制效率的降低部分解释了流感 H5N1 病毒感染分化良好的 NHBE 细胞中干扰素-β反应较低的原因。由于支气管上皮细胞中的流感感染会导致组织损伤，并与上皮细胞再生相关，因此未分化的 NHBE 培养物产生的数据也可能与疾病发病机制相关。
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