Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
Mod Pathol. 2012 Jan;25(1):1-13. doi: 10.1038/modpathol.2011.125. Epub 2011 Aug 26.
Twenty autopsy cases with 2009 pandemic influenza A (2009 H1N1) virus infection, performed between August 2009 and February 2010, were histopathologically analyzed. Hematoxylin-eosin staining, immunohistochemistry for type A influenza nucleoprotein antigen, and real-time reverse transcription-PCR assay for viral RNA were performed on formalin-fixed and paraffin-embedded specimens. In addition, the D222G amino acid substitution in influenza virus hemagglutinin, which binds to specific cell receptors, was analyzed in formalin-fixed and paraffin-embedded trachea and lung sections by direct sequencing of PCR-amplified products. There were several histopathological patterns in the lung according to the most remarkable findings in each case: acute diffuse alveolar damage (DAD) with a hyaline membrane (four cases), organized DAD (one case), acute massive intra-alveolar edema with variable degrees of hemorrhage (three cases), neutrophilic bronchopneumonia (five cases) and tracheobronchitis with limited histopathological changes in alveoli (four cases). In two cases, the main findings were due to preexisting disease. Influenza virus antigen was only detected in the respiratory tract in 10 cases by immunohistochemistry. The antigen was detected in type II pneumocytes (three cases) in the epithelial cells of the trachea, bronchi and glands (six cases), and in the epithelial cells in both of the above (one case). The four cases with acute DAD presented with antigen-positive type II pneumocytes. In one case, the D222G substitution was detected in the lung as a major sequence, although 222D was prominent in the trachea, suggesting that selection of the viral clones occurred in the respiratory tract. In five cases, the pathogenesis of 2009 H1N1 was confirmed to be viral infection in pneumocytes, which caused severe alveolar damage and fatal viral pneumonia. Further studies on both host and viral factors in autopsy or biopsy materials will be essential to elucidate the other pathogenic factors involved in influenza virus infection.
2009 年甲型 H1N1 流感病毒感染的 20 例尸检病例，于 2009 年 8 月至 2010 年 2 月进行了组织病理学分析。对福尔马林固定和石蜡包埋的标本进行了苏木精-伊红染色、甲型流感核蛋白抗原免疫组化染色和病毒 RNA 的实时逆转录-PCR 检测。此外，还通过直接测序 PCR 扩增产物，分析了与特定细胞受体结合的流感病毒血凝素中的 D222G 氨基酸取代，该取代存在于福尔马林固定和石蜡包埋的气管和肺切片中。根据每个病例中最显著的发现，肺部有几种组织病理学模式：伴有透明膜的急性弥漫性肺泡损伤（DAD）（四例）、有组织的 DAD（一例）、伴有不同程度出血的急性弥漫性肺泡内水肿（三例）、中性粒细胞性细支气管炎和支气管肺炎（五例）以及肺泡内组织病理学改变有限的气管支气管炎（四例）。在两例病例中，主要发现是由先前存在的疾病引起的。免疫组织化学仅在 10 例病例的呼吸道中检测到流感病毒抗原。抗原在气管、支气管和腺体的上皮细胞中（六例）和上述两种上皮细胞中（一例）的 II 型肺泡细胞中检测到。四例急性 DAD 病例的 II 型肺泡细胞呈抗原阳性。在一例病例中，在肺部检测到主要序列的 D222G 取代，尽管在气管中 222D 更突出，表明病毒克隆的选择发生在呼吸道中。在五例病例中，通过尸检或活检材料证实了 2009 年 H1N1 的发病机制是病毒感染肺细胞，导致严重的肺泡损伤和致命的病毒性肺炎。进一步研究尸检或活检材料中的宿主和病毒因素对于阐明流感病毒感染涉及的其他致病因素至关重要。
