目的：观察下呼吸道流感嗜血杆菌定植对哮喘小鼠气道炎症的影响,并研究其信号通路。方法：采用C57/B6和TLR4^-/-小鼠,分别用卵清蛋白（ovalbumin,OVA）致敏和激发制备慢性哮喘小鼠模型,用流感嗜血杆菌琼脂菌珠制作气道定植模型（注菌组为2组,注菌后第7天和第21天组）,同时设置对应时间（第7天和第21天）的0.9%NaCl溶液注射组及单纯流感定植组、单纯哮喘组,每种小鼠各8组,共16组。在哮喘小鼠气道注菌之后的第7、21天处死小鼠,检测血清中肿瘤坏死因子α（tumor necrosis factor α,TNF-α）含量,采用免疫组织化学法检测小鼠肺组织髓样分化因子88（myeloid differentiation factor 88, MyD88）和核因子κB（nuclear factor κB, NF-κB）的表达,并分别与相同时间的单纯流感定植及0.9%NaCl溶液注射、单纯哮喘对照小鼠相比较;再将C57/B6与TLR4^-/-小鼠的实验结果进行比较,同时比较各组小鼠支气管肺泡灌洗液（bronchoalveolar lavage fluid,BALF）中的细胞总数。结果：与相同时间的单纯流感定植及0.9%NaCl溶液注射的对照小鼠相比,有流感嗜血杆菌呼吸道定植的C57/B6和TLR4^-/-哮喘小鼠血清中TNF-α含量、肺组织中MyD88和NF-κB的表达以及BALF中的细胞总数均升高（P均<0.05）;与同时间对应组C57/B6小鼠相比,合并流感嗜血杆菌呼吸道定植的TLR4^-/-哮喘小鼠血清中TNF-α含量、肺组织中MyD88和NF-κB的表达以及BALF中的细胞总数均降低P均<0.05）。结论：流感嗜血杆菌在下呼吸道定植可以通过激活TLR4-MyD88通路,促进转录因子NF-κB的表达,加重哮喘的气道炎症,这可能是哮喘发病的重要机制之一。

Objective: To observe the effect of Haemophilus influenzae colonizing lower respiratory tract on airway inflammation in asthmatic mice and study the related signaling pathway. Methods: Thirty-two C57/B6 mice were sensitized and challenged with ovalbumin (OVA) to establish a mice model of chronic asthma (AC group), and then half of them received intratracheal injection of Haemophilus influenza coated in agar beads to built a mice model of chronic asthma with airway Haemophilus influenza colonization (AS group). Besides, 16 C57/B6 mice were treated with intratracheal injection of Haemophilus influenza (NS group) and 16 C57/B6 mice received intratracheal injection of 0.9% NaCl (NC group). Sixty-four TLR4^-/- mice were treated and grouped as C57/B6 mice. Mice including C57/B6 and TLR4^-/- mice were sacrificed at 7 and 14 days after intratracheal injection, and serum tumor necrosis factor α(TNF-α) content, total number of cells in bronchoalveolar lavage fluid( BALF), and the expression of MyD88 and NF-κB in lung tissue were measured. The indice in AS group were compared with those in the control groups (AC, NS and NC) at corresponding time. Results: The serum level of TNF-α, total number of cells in BALF, and expression of MyD88 and NF-κB in lung tissue were higher in AS group than those in NC and NS group (both in C57/B6 mice and TLR4^-/- mice). Compared with C57/B6 wild-type mice, TLR4^-/- mice in AS group had lower levels of serum TNF-α, decreased numbers of cells in BALF, and down-regulated expression of MyD88 and NF-κB in lung tissue. Conclusions: Lower airway colonization with Haemophilus influenzae may aggravate airway inflammation of asthma by activating the TLR4-MyD88 pathway and promoting expression of NF-κB, which may be one of the important mechanisms of asthma.