Nita-Lazar Mihai, Banerjee Aditi, Feng Chiguang, Vasta Gerardo R
Department of Microbiology and Immunology, University of Maryland School of Medicine, and Institute of Marine and Environmental Technology, Columbus Center, 701 East Pratt Street, Baltimore, MD 21202, USA.
Department of Microbiology and Immunology, University of Maryland School of Medicine, and Institute of Marine and Environmental Technology, Columbus Center, 701 East Pratt Street, Baltimore, MD 21202, USA.
Mol Immunol. 2015 Dec;68(2 Pt A):194-202. doi: 10.1016/j.molimm.2015.08.005. Epub 2015 Sep 6.
Influenza patients frequently display increased susceptibility to Streptococcus pneumoniae co-infection and sepsis, the prevalent cause of mortality during influenza pandemics. However, the detailed mechanisms by which an influenza infection predisposes patients to suffer pneumococcal pneumonia are not fully understood. A murine model for influenza infection closely reflects the observations in human patients, since if the animals that have recovered from influenza A virus (IAV) sublethal infection are challenged with S. pneumoniae, they undergo a usually fatal uncontrolled cytokine response. We have previously demonstrated both in vitro and in vivo that the expression and secretion of galectin-1 (Gal1) and galectin-3 (Gal3) are modulated during IAV infection, and that the viral neuraminidase unmasks galactosyl moieties in the airway epithelia. In this study we demonstrate in vitro that the binding of secreted Gal1 and Gal3 to the epithelial cell surface modulates the expression of SOCS1 and RIG1, and activation of ERK, AKT or JAK/STAT1 signaling pathways, leading to a disregulated expression and release of pro-inflammatory cytokines. Our results suggest that the activity of the viral and pneumococcal neuraminidases on the surface of the airway epithelial cells function as a "danger signal" that leads to rapid upregulation of SOCS1 expression to prevent an uncontrolled inflammatory response. The binding of extracellular Gal1 or Gal3 to the galactosyl moieties unmasked on the surface of airway epithelial cells can either "fine-tune" or severely disregulate this process, respectively, the latter potentially leading to hypercytokinemia.
流感患者常常表现出对肺炎链球菌合并感染和败血症的易感性增加,而这是流感大流行期间常见的死亡原因。然而,流感感染使患者易患肺炎球菌肺炎的详细机制尚未完全明确。流感感染的小鼠模型能很好地反映人类患者的情况,因为从甲型流感病毒(IAV)亚致死感染中恢复的动物若受到肺炎链球菌的攻击,会引发通常致命的不受控制的细胞因子反应。我们之前在体外和体内均已证明,在IAV感染期间,半乳糖凝集素-1(Gal1)和半乳糖凝集素-3(Gal3)的表达和分泌会受到调节,并且病毒神经氨酸酶会使气道上皮细胞中的半乳糖基部分暴露出来。在本研究中,我们在体外证明,分泌的Gal1和Gal3与上皮细胞表面的结合会调节SOCS1和RIG1的表达,以及ERK、AKT或JAK/STAT1信号通路的激活,从而导致促炎细胞因子的表达和释放失调。我们的结果表明,气道上皮细胞表面的病毒和肺炎球菌神经氨酸酶的活性作为一种“危险信号”,导致SOCS1表达迅速上调以防止不受控制的炎症反应。细胞外Gal1或Gal3与气道上皮细胞表面暴露的半乳糖基部分的结合,分别可以对这一过程进行“微调”或严重扰乱,后者可能导致细胞因子血症。