Cytokine and chemokine responses in pediatric patients with severe pneumonia associated with pandemic A/H1N1/2009 influenza virus

Severe pneumonia and leukocytosis are characteristic, frequently observed, clinical findings in pediatric patients with pandemic A/H1N1/2009 influenza virus infection. The aim of this study was to elucidate the role of cytokines and chemokines in complicating pneumonia and leukocytosis in patients with pandemic A/H1N1/2009 influenza virus infection. Forty‐seven patients with pandemic A/H1N1/2009 influenza virus infection were enrolled in this study. Expression of interleukin (IL)‐10 (P = 0.027) and IL‐5 (P = 0.014) was significantly greater in patients with pneumonia than in those without pneumonia. Additionally, serum concentrations of interferon‐γ (P = 0.009), tumor necrosis factor‐α (P = 0.01), IL‐4 (P = 0.024), and IL‐2 (P = 0.012) were significantly lower in pneumonia patients with neutrophilic leukocytosis than in those without neutrophilic leukocytosis. Of the five serum chemokine concentrations assessed, only IL‐8 was significantly lower in pneumonia patients with neutrophilic leukocytosis than in those without leukocytosis (P = 0.001). These cytokines and chemokines may play important roles in the pathogenesis of childhood pneumonia associated with A/H1N1/2009 influenza virus infection.     

IL-17 response mediates acute lung injury induced by the 2009 pandemic influenza A (H1N1) virus

The 2009 flu pandemic involved the emergence of a new strain of a swine-origin H1N1 influenza virus (S-OIV H1N1) that infected almost every country in the world. Most infections resulted in respiratory illness and some severe cases resulted in acute lung injury. In this report, we are the first to describe a mouse model of S-OIV virus infection with acute lung injury and immune responses that reflect human clinical disease. The clinical efficacy of the antiviral oseltamivir (Tamiflu) administered in the early stages of S-OIV H1N1 infection was confirmed in the mouse model. Moreover, elevated levels of IL-17, Th-17 mediators and IL-17-responsive cytokines were found in serum samples of S-OIV-infected patients in Beijing. IL-17 deficiency or treatment with monoclonal antibodies against IL-17-ameliorated acute lung injury induced by the S-OIV H1N1 virus in mice. These results suggest that IL-17 plays an important role in S-OIV-induced acute lung injury and that monoclonal antibodies against IL-17 could be useful as a potential therapeutic remedy for future S-OIV H1N1 pandemics.     

Influenza A: From highly pathogenic H5N1 to pandemic 2009 H1N1. Epidemiology and clinical features

The last decade has seen the emergence of two new influenza A subtypes and they have become a cause of concern for the global community. These are the highly pathogenic H5N1 influenza A virus (H5N1) and the Pandemic 2009 influenza H1N1 virus. Since 2003 the H5N1 virus has caused widespread disease and death in poultry, mainly in south East Asia and Africa. In humans the number of cases infected with this virus is few but the mortality has been about 60%. Most patients have presented with severe pneumonia and acute respiratory distress syndrome. The second influenza virus, the pandemic H1N1 2009, emerged in Mexico in March this year. This virus acquired the ability for sustained human to human spread and within a few months spread throughout the world and infected over 4 lakh individuals. The symptoms of infection with this virus are similar to seasonal influenza but it currently affecting younger individuals more often. Fortunately the mortality has been low. Both these new influenza viruses are currently circulating and have different clinical and epidemiological characteristics.     

Serum concentrations of complement anaphylatoxins and proinflammatory mediators in patients with 2009 H1N1 influenza

Anaphylatoxins (C5a, C4a, and C3a) are fragments of activated complement and are leading mediators of the inflammatory response for controlling viral infection. However, an excessive response may increase the severity of infectious diseases. Serum concentrations of proinflammatory mediators, including cytokines, high-mobility group box 1 and anaphylatoxins, were measured in pediatric 2009 H1N1 influenza patients in order to investigate the pathology of this new influenza. The concentrations of all three anaphylatoxins were significantly enhanced by 2009 H1N1 influenza infection. However, there were no significant differences in anaphylatoxin concentrations between 2009 H1N1 influenza patients with and without severe complications during the early stages of the disease. C3a concentrations dropped significantly during the recovery phase, whereas there were no significant differences between the acute and recovery phases in C5a and C4a concentrations. There was a correlation between C5a and IL-2. C4a was associated with IL-1ra, eotaxin, MCP-1, PDGFbb, and VEGF. C3a was correlated with IL-2 and IFN-γ. Taken together, these findings indicate that complement activation occurs in patients infected with 2009 H1N1 influenza virus and demonstrate that anaphylatoxins are involved in increased production of proinflammatory mediators in this new influenza.     

Antiviral role of toll-like receptors and cytokines against the new 2009 H1N1 virus infection

People are generally susceptible to the 2009 new mutate of H1N1 influenza due to lack of appropriate immunity. Influenza H1N1 2009 infection triggers a massive inflammatory response that contributes to fever, lung impairment or other tissue damage, eventually leading to death. Infection with pathogenic influenza virus H1N1 induces severe pulmonary immune pathology. To date, more than 10,000 cases worldwide have died of the disease. It still has strong infectious ability although the mortality of influenza isn’t currently high. Therefore, to explore the pathogenesis of H1N1 influenza can help with the disease prevention, diagnosis and provide a theoretical basis and the new ideas of treatment. Laboratory confirmed cases of pandemic influenza H1N1 2009 were enrolled to collect general information on pre-clinical, clinical and laboratory data for analysis. Blood samples were obtained from patients with H1N1, healthy volunteers and patients with bacterial pneumonia. Serum were separated and collected. RT–PCR and ELISA methods were applied to detect the different expression of TLRs and cytokines. The young, pregnant and postpartum women and infant are highly susceptible to influenza H1N1 2009 infection; degree of susceptibility is not associated with BMI. Biochemical changes can be seen in the patients with influenza H1N1 2009 infection: ALT, AST, CK, LDH increased in varying degrees. TLR2, TLR3, TLR9 expression increased in the patients with influenza H1N1 2009 infection; no obvious changes of TLR4, TLR7, TLR8 can be detected. In pregnant and postpartum women group, only TLR9 expression increased. The expression of IL-2, IL-6, IFN-γ, TNF-α in the patients with influenza H1N1 2009 infection was significantly increased; while IL-10 expression decreased and IL-4 expression did not change. H1N1 influenza-infected pregnant and postpartum women group, only IL-2 and TNF-α expression expression increased, other cytokines decreased or didn’t change. TLR2, TLR3, TLR9 are the major members of TLR family in the recognition of the novel H1N1 virus to start the innate immune response and adaptive immune responses. TLR9 may be the key receptor among pattern recognized receptors to recognize and bind to H1N1 virus. Cellular immune responses induced by Th1 may participate in modulating the influenza H1N1 2009.     

H5N1型禽流感病毒感染非人灵长类动物的观察

目的观察H5N1型禽流感病毒对中国非人灵长类动物的易感性并建立动物模型。方法将病毒通过滴鼻接种实验猴,观察感染后动物的临床症状,采血、咽拭子及各器官组织进行血清学、病原学及病理学检查,记录抗体变化、病毒分离情况及病理学改变。结果感染后动物表现轻度食欲下降、一过性体温升高及外周血白细胞减少,肺组织病毒分离及RT-PCR阳性,病理检查感染急性期动物肺组织表现为间质性肺炎,肺泡间隔增宽,充血出血明显,肺泡受压变形,间质及肺泡内有大量炎细胞浸润,符合病毒性肺炎的改变,感染后14 d动物血清IgG抗体水平较感染前升高4倍。结论H5N1病毒可感染非人灵长类动物,可以作为感染模型进行H5N1病毒的发病机制、疫苗评价、药物筛选等研究。     

Increased levels of cytokines and high-mobility group box 1 are associated with the development of severe pneumonia, but not acute encephalopathy, in 2009 H1N1 influenza-infected children

Background

The 2009 A(H1N1) influenza virus has caused a large outbreak, and resulted in major complications of severe pneumonia and acute encephalopathy in the pediatric population in Japan.

Methods

This study examined six patients with acute encephalopathy, 34 patients with severe pneumonia, five patients with both pneumonia and encephalopathy, and 46 patients without severe complications. The concentrations of 27 cytokines were examined in the cerebrospinal fluid of patients with encephalopathy, and the levels of these cytokines, Cytochrome c, high-mobility group box 1 (HMGB1) were measured in the serum of all patients.

Results

Patients with severe pneumonia had higher serum concentrations of 16 cytokines, including Th1 cytokines, Th2 cytokines, chemokines, and growth factors, than patients with uncomplicated influenza. The distribution of 27 cytokines in the CSF did not parallel the serum levels in 11 patients with acute encephalopathy. HMGB1 concentrations in the serum were significantly higher in pneumonia patients with or without encephalopathy than in uncomplicated influenza patients, and were significantly associated with the upregulation of 10 cytokines.

Conclusions

Elevated levels of Th2 cytokines appear to be unique to influenza caused by 2009 H1N1 influenza virus and HMGB1 could play an important role in the pathogenesis of severe pneumonia. There appear to be different pathologic processes for encephalopathy and pneumonia.     

Highly pathogenic avian influenza H5N1 virus induces cytokine dysregulation with suppressed maturation of chicken monocyte‐derived dendritic cells

One of the major causes of death in highly pathogenic avian influenza virus (HPAIV) infection in chickens is acute induction of pro‐inflammatory cytokines (cytokine storm), which leads to severe pathology and acute mortality. DCs and respiratory tract macrophages are the major antigen presenting cells that are exposed to mucosal pathogens. We hypothesized that chicken DCs are a major target for induction of cytokine dysregulation by H5N1 HPAIV. It was found that infection of chicken peripheral blood monocyte‐derived dendritic cells (chMoDCs) with H5N1 HPAIV produces high titers of progeny virus with more rounding and cytotoxicity than with H9N2 LPAIV. Expression of maturation markers (CD40, CD80 and CD83) was weaker in both H5N1 and H9N2 groups than in a LPS control group. INF‐α, ‐β and ‐γ were significantly upregulated in the H5N1 group. Pro‐inflammatory cytokines (IL‐1β, TNF‐α and IL‐18) were highly upregulated in early mid (IL‐1), and late (IL‐6) phases of H5N1 virus infection. IL‐8 (CXCLi2) mRNA expression was significantly stronger in the H5N1 group from 6 hr of infection. TLR3, 7, 15 and 21 were upregulated 24 hr after infection by H5N1 virus compared with H9N2 virus, with maximum expression of TLR 3 mRNA. Similarly, greater H5N1 virus‐induced apoptotic cell death and cytotoxicity, as measured by terminal deoxynucleotidyl transferase‐mediated dUTP nick end labeling and lactate dehydrogenase assays, respectively, were found. Thus, both H5N1 and H9N2 viruses evade the host immune system by inducing impairment of chMoDCs maturation and enhancing cytokine dysregulation in H5N1 HPAIV‐infected cells.     

Recently emerged swine influenza A virus (H2N3) causes severe pneumonia in Cynomolgus macaques

The triple reassortant H2N3 virus isolated from diseased pigs in the United States in 2006 is pathogenic for certain mammals without prior adaptation and transmits among swine and ferrets. Adaptation, in the H2 hemagglutinin derived from an avian virus, includes the ability to bind to the mammalian receptor, a significant prerequisite for infection of mammals, in particular humans, which poses a big concern for public health. Here we investigated the pathogenic potential of swine H2N3 in Cynomolgus macaques, a surrogate model for human influenza infection. In contrast to human H2N2 virus, which served as a control and largely caused mild pneumonia similar to seasonal influenza A viruses, the swine H2N3 virus was more pathogenic causing severe pneumonia in nonhuman primates. Both viruses replicated in the entire respiratory tract, but only swine H2N3 could be isolated from lung tissue on day 6 post infection. All animals cleared the infection whereas swine H2N3 infected macaques still presented with pathologic changes indicative of chronic pneumonia at day 14 post infection. Swine H2N3 virus was also detected to significantly higher titers in nasal and oral swabs indicating the potential for animal-to-animal transmission. Plasma levels of IL-6, IL-8, MCP-1 and IFNγ were significantly increased in swine H2N3 compared to human H2N2 infected animals supporting the previously published notion of increased IL-6 levels being a potential marker for severe influenza infections. In conclusion, the swine H2N3 virus represents a threat to humans with the potential for causing a larger outbreak in a non-immune or partially immune population. Furthermore, surveillance efforts in farmed pig populations need to become an integral part of any epidemic and pandemic influenza preparedness.     

Pulmonary immune cells and inflammatory cytokine dysregulation are associated with mortality of IL-1R1-/-mice infected with influenza virus (H1 N1)

Respirovirus infection can cause viral pneumonia and acute lung injury (ALI).The interleukin-1 (IL-1) family consists of proinflammatory cytokines that play essential roles in regulating immune and inflammatory responses in vivo.IL-1 signaling is associated with protection against respiratory influenza virus infection by mediation of the pulmonary anti-viral immune response and inflammation.We analyzed the infiltration lung immune leukocytes and cytokines that contribute to inflammatory lung pathology and mortality of fatal H1N1 virus-infected IL-1 receptor 1 (IL-1R1) deficient mice.Results showed that early innate immune cells and cytokine/chemokine dysregulation were observed with significantly decreased neutrophil infiltration and IL-6,TNF-α,G-CSF,KC,and MIP-2 cytokine levels in the bronchoalveolar lavage fluid of infected IL-1R1-/-mice in comparison with that of wild type infected mice.The adaptive immune response against the H1N1 virus in IL-1R1-/-mice was impaired with downregulated anti-viral Th1 cell,CD8+ cell,and antibody functions,which contributes to attenuated viral clearance.Histological analysis revealed reduced lung inflammation during early infection but severe lung pathology in late infection in IL-1R1-/-mice compared with that in WT infected mice.Moreover,the infected IL-1R1-/-mice showed markedly reduced neutrophil generation in bone marrow and neutrophil recruitment to the inflamed lung.Together,these results suggest that IL-1 signaling is associated with pulmonary anti-influenza immune response and inflammatory lung injury,particularly via the influence on neutrophil mobilization and inflammatory cytokine/chemokine production.     

禽流感H5N1亚型病毒对五个不同品系小鼠致病性的比较(英文)

目的比较了不同遗传背景小鼠对禽流感H5N1亚型病毒的致病敏感性,为H5N1禽流感模型制作和机理研究提供依据。方法近交系BALB/c、C57BL/6和封闭群ICR、NIHSwiss和KMSwiss共五个不同品系小鼠。每个品系实验动物30只,分接毒组20只,空白对照组10只,每组雌雄各半。病毒株为A/Goose/Guangdong/NH/2003(H5N1),经测定TCID50为10-4.875/mL。接毒组通过鼻腔接种0.1mL病毒液,对照组接种正常鸡胚尿囊液。小鼠接毒后连续观察14d,观察记录临床症状、体温、体重变化,对在实验期间死亡和实验14d结束后仍然存活的小鼠均进行组织器官病理取材,进行RT-PCR病毒分离检测、HE染色及H5N1抗原特异性免疫组化染色。结果①临床症状:H5N1禽流感病毒能感染五个品系的小鼠,引起呼吸急促等症状和一过性体重、体温下降。②死亡情况:小鼠在接毒后第1天即出现死亡,死亡的高峰期集中在接毒后第3～6天。五个品系小鼠死亡率存在差异,BALB/c为70%,ICR为50%,NIHSwiss为40%,C57BL/6为25%,KMSwiss为10%;③病毒分离:各组接毒小鼠在死亡后均进行了病毒分离,死亡小鼠的肺脏均分离到病毒,其他脏器未分离到病毒。④病理变化:实验期间五个品系死亡小鼠肺脏病理改变相近。大体观:死亡小鼠肺部淤血,呈暗红色,体积增大,局部肺组织实变。镜下观:死亡小鼠的共同病理改变为间质性肺炎,具体表现为肺泡腔及间质出血、炎性细胞浸润;间质增生,肺泡隔增宽;肺泡腔中见纤维素性渗出,透明膜形成。⑤免疫组化结果 :在死亡小鼠的气管上皮细胞和肺巨噬细胞可观察到H5N1禽流感病毒阳性表达。结论小鼠作为H5N1禽流感病毒模型具有普适性,不同品系小鼠感染鹅源H5N1禽流感病毒的临床症状、病程和病理变化与人禽流感病例相似。不同品系小鼠的死亡比例有明显差别,可以根据不同的实验目的 ,选择不同品系的小鼠制作H5N1禽流感动物模型。不同品系的遗传特性对禽流感易感性产生明显的影响,遗传背景可能与H5N1禽流感病毒感染应答机理存在联系:BALB/c和C57BL/6均为近交系,其中BALB/c小鼠的品系特征之一表现为干扰素产量低,接种H5N1病毒后表现为高死亡率(70%),而C57BL/6小鼠的干扰素产量高,接种H5N1病毒后表现为低死亡率(25%),提示不同遗传背景小鼠的干扰素水平与H5N1感染致死具相关性。为进一步研究H5N1禽流感病毒易感性相关基因以及其与宿主免疫反应的关系提供了一个研究基础。     

Clinical Characteristics and Outcomes in Hospitalized Patients with Respiratory Viral Co-Infection during the 2009 H1N1 Influenza Pandemic

Background

The clinical consequences of co-infection with two or more respiratory viruses are poorly understood. We sought to determine if co-infection with pandemic 2009–2010 influenza A H1N1 (pH1N1) and another respiratory virus was associated with worse clinical outcomes.

Methods

A retrospective cohort study was performed of all hospitalized patients with a positive respiratory viral panel (RVP) for two or more viruses within 72 hours of admission at our institution from October 2009 to December 2009. We compared patients infected with one respiratory virus to those with respiratory viral co-infection.

Results

We identified 617 inpatients with a positive RVP sample with a single virus and 49 inpatients with a positive RVP sample for two viruses (i.e. co-infection). Co-infected patients were significantly younger, more often had fever/chills, tachypnea, and they more often demonstrated interstitial opacities suggestive of viral pneumonia on the presenting chest radiograph (OR 7.5, 95% CI 3.4–16.5). The likelihood of death, length of stay, and requirement for intensive care unit level of care were similar in both groups, but patients with any respiratory virus co-infection were more likely to experience complications, particularly treatment for a secondary bacterial pneumonia (OR 6.8, 95% CI 3.3–14.2). Patients co-infected with pH1N1 and another respiratory virus were more likely to present with chest radiograph changes suggestive of a viral pneumonia, compared to mono-infection with pH1N1 (OR 16.9, 95% CI 4.5–62.7). By logistic regression using mono-infection with non-PH1N1 viruses as the reference group, co-infection with pH1N1 was the strongest independent predictor of treatment for a secondary bacterial pneumonia (OR 17.8, 95% CI 6.7–47.1).

Conclusion

Patients with viral co-infection, particularly with pH1N1, were more likely to have chest radiograph features compatible with a viral pneumonia and complications during their hospital course, particularly treatment for secondary bacterial pneumonia. Despite this, co-infection was not associated with ICU admission.     

2005～2006年湖南省人感染高致病性禽流感(H5N1)实验室诊断及病毒基因特性研究

为了对2005~2006年湖南省2例不明原因肺炎病例进行实验室诊断,确定病因以及对其进行病原学研究,采集病例呼吸道标本和血清标本,对呼吸道标本采用实时荧光定量逆转录聚合酶链式反应(Real-time RT-PCR)和逆转录聚合酶链式反应(RT-PCR)方法检测H5亚型禽流感病毒核酸,对血清标本采用血凝抑制试验检测特异性抗体,并对其中1例死亡病例(病例2)的肺穿刺物标本进行病毒分离,所获毒株予以测序及同源性分析。结果显示,2例病例H5亚型禽流感病毒核酸检测均为阳性,病例1恢复期血清H5N1特异性抗体阳性,并且较急性期血清呈4倍以上增长;病例2急性期血清特异性抗体阴性,2例均为人感染高致病性禽流感病毒(H5N1)确诊病例。从病例2分离得到毒株A/Hunan/1/2006,测序及分子特性分析表明,其8个基因片段均为禽源,且与湖南本地禽类分离的病毒相似,并未与人流感病毒发生基因重组或产生显著变异。     

Pandemic Influenza (H1N1) 2009 Pneumonia: CURB-65 Score for Predicting Severity and Nasopharyngeal Sampling for Diagnosis Are Unreliable

Background

From the first case reports of pandemic influenza (H1N1) 2009 it was clear that a significant proportion of infected individuals suffered a primary viral pneumonia. The objective of this study was twofold; to assess the utility of the CURB-65 community acquired pneumonia (CAP) severity index in predicting pneumonia severity and ICU admission, and to assess the relative sensitivity of nasopharyngeal versus lower respiratory tract sampling for the detection of pandemic influenza (H1N1) CAP.

Methods

A retrospective cohort study of 70 patients hospitalised for pandemic influenza (H1N1) 2009 in an adult tertiary referral hospital. Characteristics evaluated included age, pregnancy status, sex, respiratory signs and symptoms, smoking and alcohol history, CURB-65 score, co-morbidities, disabling sequelae, length of stay and in-hospital mortality outcomes. Laboratory features evaluated included lymphocyte count, C-reactive protein (CRP), nasopharyngeal and lower respiratory tract pandemic influenza (H1N1) 2009 PCR results.

Results

Patients with pandemic (H1N1) 2009 influenza CAP differed significantly from those without pneumonia regarding length of stay, need for ICU admission, CRP and the likelihood of disabling sequelae. The CURB-65 score did not predict CAP severity or the need for ICU admission (only 2/11 patients admitted to ICU had CURB-65 scores of 2 or 3). Nasopharyngeal specimens for PCR were only 62.9% sensitive in CAP patients compared to 97.8% sensitivity for lower respiratory tract specimens.

Conclusions

The CURB-65 score does not predict severe pandemic influenza (H1N1) 2009 CAP or need for ICU admission. Lower respiratory tract specimens should be collected when pandemic (H1N1) 2009 influenza CAP is suspected.     

Clinical and Epidemiologic Characteristics of Hospitalized Patients with Laboratory-Confirmed Respiratory Syncytial Virus Infection in Eastern China between 2009 and 2013: A Retrospective Study

Respiratory syncytial virus (RSV) is a leading cause of morbidity and mortality worldwide in children aged <5 years and older adults with acute lower respiratory infections (ALRIs). However, few studies regarding the epidemiology of hospitalizations for RSV infection have been performed previously in China. Here, we aimed to describe the clinical and epidemiologic characteristics of hospitalized patients with laboratory-confirmed RSV infection in eastern China. Active surveillance for hospitalized ALRI patients using a broad case definition based on symptoms was performed from 2009–2013 in 12 sentinel hospitals in eastern China. Clinical and epidemiologic data pertaining to hospitalized patients of all ages with laboratory-confirmed RSV infection by PCR assay were collected and analyzed in this study. From 2009 to 2013, 1046 hospitalized patients with laboratory-confirmed RSV infection were enrolled in this study, and 14.7% of patients had subtype A, 24.2% of patients had subtype B, 23.8% of patients with subtype not performed, and 37.3% of patients had RSV coinfections with other viruses. RSV and influenza coinfections (33.3%) were the most common coinfections noted in this study. Moreover, young children aged <5 years (89.1%, 932/1046), particularly young infants aged <1 year (43.3%, 453/1046), represented the highest proportion of patients with RSV infections. In contrast, older adults aged ≥60 years (1.1%, 12/1046) represented the lowest proportion of patients with RSV infections among enrolled patients. The peak RSV infection period occurred mainly during autumn and winter, and 57% and 66% of patients exhibited symptoms such as fever (body temperature ≥38°C) and cough separately. Additionally, only a small number of patients were treated with broad-spectrum antiviral drugs, and most of patients were treated with antimicrobial drugs that were not appropriate for RSV infection. RSV is a leading viral pathogen and a common cause of viral infection in young children aged <5 years with ALRIs in eastern China. Effective vaccines and antiviral agents targeting RSV are needed to mitigate its large public health impact.     

Human pulmonary microvascular endothelial cells support productive replication of highly pathogenic avian influenza viruses: possible involvement in the pathogenesis of human H5N1 virus infection

Highly pathogenic avian influenza (HPAI) H5N1 viruses continue to cause sporadic human infections with a high fatality rate. Respiratory failure due to acute respiratory distress syndrome (ARDS) is a complication among hospitalized patients. Since progressive pulmonary endothelial damage is the hallmark of ARDS, we investigated host responses following HPAI virus infection of human pulmonary microvascular endothelial cells. Evaluation of these cells for the presence of receptors preferred by influenza virus demonstrated that avian-like (α2-3-linked) receptors were more abundant than human-like (α2-6-linked) receptors. To test the permissiveness of pulmonary endothelial cells to virus infection, we compared the replication of selected seasonal, pandemic (2009 H1N1 and 1918), and potentially pandemic (H5N1) influenza virus strains. We observed that these cells support productive replication only of HPAI H5N1 viruses, which preferentially enter through and are released from the apical surface of polarized human endothelial monolayers. Furthermore, A/Thailand/16/2004 and A/Vietnam/1203/2004 (VN/1203) H5N1 viruses, which exhibit heightened virulence in mammalian models, replicated to higher titers than less virulent H5N1 strains. VN/1203 infection caused a significant decrease in endothelial cell proliferation compared to other subtype viruses. VN/1203 virus was also found to be a potent inducer of cytokines and adhesion molecules known to regulate inflammation during acute lung injury. Deletion of the H5 hemagglutinin (HA) multibasic cleavage site did not affect virus infectivity but resulted in decreased virus replication in endothelial cells. Our results highlight remarkable tropism and infectivity of the H5N1 viruses for human pulmonary endothelial cells, resulting in the potent induction of host inflammatory responses.     

Systems-Level Comparison of Host-Responses Elicited by Avian H5N1 and Seasonal H1N1 Influenza Viruses in Primary Human Macrophages

Human disease caused by highly pathogenic avian influenza (HPAI) H5N1 can lead to a rapidly progressive viral pneumonia leading to acute respiratory distress syndrome. There is increasing evidence from clinical, animal models and in vitro data, which suggests a role for virus-induced cytokine dysregulation in contributing to the pathogenesis of human H5N1 disease. The key target cells for the virus in the lung are the alveolar epithelium and alveolar macrophages, and we have shown that, compared to seasonal human influenza viruses, equivalent infecting doses of H5N1 viruses markedly up-regulate pro-inflammatory cytokines in both primary cell types in vitro. Whether this H5N1-induced dysregulation of host responses is driven by qualitative (i.e activation of unique host pathways in response to H5N1) or quantitative differences between seasonal influenza viruses is unclear. Here we used microarrays to analyze and compare the gene expression profiles in primary human macrophages at 1, 3, and 6 h after infection with H5N1 virus or low-pathogenic seasonal influenza A (H1N1) virus. We found that host responses to both viruses are qualitatively similar with the activation of nearly identical biological processes and pathways. However, in comparison to seasonal H1N1 virus, H5N1 infection elicits a quantitatively stronger host inflammatory response including type I interferon (IFN) and tumor necrosis factor (TNF)-α genes. A network-based analysis suggests that the synergy between IFN-β and TNF-α results in an enhanced and sustained IFN and pro-inflammatory cytokine response at the early stage of viral infection that may contribute to the viral pathogenesis and this is of relevance to the design of novel therapeutic strategies for H5N1 induced respiratory disease.     

2009流行性感冒患者血清细胞因子的变化特点

本文旨在通过比较30例2009甲型H1N1流行性感冒(简称流感)患者经奥司他韦治疗前、后血清中细胞因子的变化特点,探讨其可能的发病机制.30例患者分为奥司他韦治疗前组和治疗后组,另选取健康志愿者20例为对照组.采用酶联免疫吸附试验,检测患者血清白细胞介素10(IL-10)、IL-2、IL-8及γ干扰素(IFN-γ)水平...