The role of cytokines and chemokines in severe respiratory syncytial virus infection and subsequent asthma

Respiratory syncytial virus (RSV) is the primary cause of serious lower respiratory tract illness in infants and young children worldwide. The mechanism is largely unknown. RSV stimulates airway epithelial cells and resident leukocytes to release cytokines. Cytokines and chemokines involved in host response to RSV infection are thought to play a central role in the pathogenesis. In addition, RSV infection early in life has been associated with the development of asthma in later childhood. It is likely that the persistence of cytokines and chemokines in fully recovered patients with RSV in the long term can provide a substratum for the development of subsequent asthma. This review describes the genetic factors in cytokines and chemokines associated with severity of RSV disease, cytokines and chemokines synthesis in RSV infection, and the role of these innate immune components in RSV-associated asthma.     

Involvement of toll-like receptor 4 in innate immunity to respiratory syncytial virus

The mammalian Toll-like receptor 4, TLR4, is an important component in the innate immune response to gram-negative bacterial infection. The role of TLR4 in antiviral immunity has been largely unexplored. In this study, the in vivo immune responses to respiratory syncytial virus (RSV) and influenza virus infection were examined in TLR4-deficient (C57BL/10ScNCr) and TLR4-expressing (C57BL/10Sn) mice. TLR4-deficient mice challenged with RSV, but not influenza virus, exhibited impaired natural killer (NK) cell and CD14(+) cell pulmonary trafficking, deficient NK cell function, impaired interleukin-12 expression, and impaired virus clearance compared to mice expressing TLR4. These findings suggest that Toll signaling pathways have an important role in innate immunity to RSV.     

白细胞介素23在呼吸道合胞病毒感染致Th1、Th2及Th17细胞分化中的作用及机制

本研究旨在探讨白细胞介素23(interleukin 23,IL-23)在呼吸道合胞病毒(respiratory syncytial virus,RSV)感染支气管上皮细胞BEAS-2B后对Th1、Th2和Th17细胞分化的影响及作用机制。将RSV感染BEAS-2B后的上清液与淋巴细胞共孵育,并分别阻断IL-23受体(IL-23 receptor,IL-23R)、IL-23p19亚基及p38丝裂原活化蛋白激酶(p38 mitogen-activated protein kinase,p38 MAPK)信号通路。应用酶联免疫吸附试验(enzyme-linked immunosorbent assay,ELISA)检测上清液中细胞因子γ干扰素(interferon γ,IFN-γ)、IL-4、IL-17的浓度。同时,应用实时聚合酶链反应(polymerase chain reaction,PCR)检测相关转录因子(t-bet、gata3、rorγt)和信号转导子(stat4、stat6、stat3)的表达。结果显示,RSV感染后IFN-γ、IL-4和IL-17蛋白表达上调,转录因子及信号转导子的表达也有所增加。阻断IL-23和p38 MAPK信号通路后,Th1、Th2和Th7细胞分泌的细胞因子及转录因子表达均明显下降。结果提示,阻断IL-23后可在基因转导层面抑制RSV感染上皮细胞后诱导的Th1、Th2和Th17细胞分化,此过程可能与p38 MAPK信号通路有关。     

Quantitative aspects of passive immunity to respiratory syncytial virus infection in infant cotton rats

The amount of passively acquired serum respiratory syncytial virus (RSV)-neutralizing antibodies required to protect the respiratory tract of cotton rats against infection was studied. Infant cotton rats were inoculated intraperitoneally with various dilutions of a single pool of sera derived from cotton rats convalescent from RSV infection. After 24 h, these animals were inoculated with RSV intranasally. Virus replication in the respiratory tract was suppressed in cotton rats which had a serum neutralizing antibody titer of 1:100 or greater. Resistance was greater in the lungs than in the nose. Complete or almost complete resistance in the lungs was observed in cotton rats with a serum neutralizing antibody titer of 1:380 or greater. The level of serum RSV-neutralizing antibodies required to confer significant resistance to infection in the cotton rat was similar to the level of maternally derived serum antibodies possessed by human infants less than 2 months of age, who as a group exhibit relative resistance to RSV disease compared with infants 2 to 6 months of age.     

Mechanisms of illness during respiratory syncytial virus infection: the lungs, the virus and the immune response

Multiple factors, including cardiopulmonary anatomy, direct viral effects and the immune response can affect the severity of lower respiratory tract disease caused by respiratory syncytial virus (RSV). RSV is the most frequent viral respiratory cause of hospitalization in infants and young children in the world. In this review, we discuss the mechanisms of illness associated with severe RSV lower respiratory tract disease. A better understanding of the factors affecting the course of illness and their interplay should allow development of effective therapies in the future.     

Immunomodulatory effects of sensory nerves during respiratory syncytial virus infection in rats

Respiratory syncytial virus (RSV) infection is associated with exaggerated neurogenic inflammation in the airways. This study sought to determine whether irritation of the mucosal sensory fibers affects the recruitment of lymphocytes and monocytes to RSV-infected airways. Pathogen-free rats were inoculated with RSV or with virus-free medium and were injected 5 days later with capsaicin to stimulate airway sensory nerves. Bronchoalveolar lavage was performed 1, 5, or 10 days after nerve stimulation, and samples were analyzed by differential cell count and flow cytometry. Without nerve stimulation, RSV caused a minimal increase in the number of lymphocytes and monocytes above pathogen-free control levels. After nerve stimulation, numerous lymphocytes, predominantly CD4+ T cells, and monocytes were recruited in the airways of infected rats, whereas no difference was found in pathogen-free controls. RSV induced overexpression of the neurokinin 1 (NK1) receptor for substance P on discrete lymphocyte subpopulations within the bronchial-associated lymphoid tissue (BALT), and treatment with a specific NK1 receptor antagonist abolished the recruitment of both lymphocytes and monocytes to infected airways. Our data suggest that airborne irritants stimulating mucosal sensory fibers during RSV infection exert important immunomodulatory effects by attracting to the infected airways selected lymphocyte subpopulations from the local BALT as well as monocytes.     

Circulating Th1 and Th2 cytokines in patients with hepatitis C virus infection.

The imbalance of T-helper (Th) lymphocyte cytokine production may play an important role in immunopathogenesis of persistent hepatitis C virus (HCV) infection. To know whether an imbalance between Th1 and Th2 cytokines is present in chronic HCV infection, serum levels of Th1 cytokines, interferon gamma (IFN-gamma) and interleukin (IL)-2, and Th2 cytokines, IL-4 and IL-10, were measured using enzyme-linked immunosorbent assay in this study. Eighteen individuals with chronic HCV infection, 11 healthy subjects as normal controls and 10 chronic HBV infected patients as disease controls were observed. The results showed that the levels of Th2 cytokines (IL-4 and IL-10) were significantly increased in chronic HCV infected patients compared with normal controls (IL-4: 30.49+/-17.55 vs. 14.94+/-13.73, pg/ml, P<0.025; IL-10: 50.30+/-19.59 vs. 17.87+/-9.49, pg/ml, P<0.001). Similarly, the levels of Th1 cytokine, IL-2, was also elevated in individuals with chronic HCV infection when compared with normal controls (IL-2: 118.53+/-95.23 vs. 61.57+/-28.70, pg/ml, P<0.05). However, Th1 cytokine IFN-gamma level was not significantly changed during HCV infection (IFN-gamma: 28.09+/-15.65 vs. 24.10+/-15.61, pg/ml, P>0.05). Furthermore, the elevated levels of Th2 cytokines are greater than Th1 cytokines in HCV infection. Thus, the study indicates that an enhanced Th2 responses are present during chronic HCV infection, which may partly be responsible for the persistence of HCV infection.     

NK cell immunophenotypic and genotypic analysis of infants with severe respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the leading cause of severe lower respiratory tract infection in infants. Reduced numbers of NK cells have been reported in infants with severe RSV infection; however, the precise role of NK cells during acute RSV infection is unclear. In this study the NK and T cell phenotypes, LILRB1 gene polymorphisms and KIR genotypes of infants hospitalized with RSV infection were analyzed. Compared to controls, infants with acute RSV infection showed a higher proportion of LILRB1+ T cells; in addition, a subgroup of infants with RSV infection showed an increase in LILRB1+ NK cells. No differences in NKG2C, NKG2A, or CD161 expression between RSV infected infants and controls were observed. LILRB1 genotype distribution of the rs3760860 A>G, and rs3760861 A>G single nucleotide polymorphisms differed between infants with RSV infection and healthy donors, whereas no differences in any of the KIR genes were observed. Our results suggest that LILRB1 participates in the pathogenesis of RSV infection. Further studies are needed to define the role of LILRB1+ NK in response to RSV and to confirm an association between LILRB1 polymorphisms and the risk of severe RSV infection.     

Role of CCL11 in eosinophilic lung disease during respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a major viral pathogen of infants and the elderly. Significant morbidity is caused by an overexuberant mixed lung cell infiltrate, which is thought to be driven by chemokines. One of the main chemotactic mediators responsible for the movement of eosinophils is CCL11 (eotaxin). Using a mouse model of eosinophilic bronchiolitis induced by RSV, we show here that treatment in vivo with a blocking antibody to CCL11 greatly reduces lung eosinophilia and disease severity. In addition, anti-CCL11 caused a striking inhibition of CD4-T-cell influx and shifted cytokine production away from interleukin-5 without reducing the resistance to viral replication. These results suggest that in addition to influencing eosinophil diapedesis and survival, anti-CCL11 has an action on T cells. These studies strengthen the case for anti-CCL11 treatment of Th2-driven diseases.     

呼吸道合胞病毒肺炎患儿血清NRAV水平及临床意义

探讨呼吸道合胞病毒（RSV）肺炎患儿血清中抗病毒应答负性调节因子（NRAV）的表达水平及临床意义。

选取我院收治的RSV肺炎患儿100例作为RSV组,并将RSV肺炎患儿根据肺炎严重指数（PSI）分为低危组（62例）、中危组（24例）及高危组（14例）。另选取同期于本院体检的102例健康儿童作为对照组。采用荧光定量PCR法检测血清NRAV水平,用肺功能仪检测受试儿童肺功能,采用Pearson法分析血清NRAV水平与RSV肺炎患儿肺功能的相关性;采用Logistics回归分析RSV肺炎患儿病情严重程度的影响因素;采用ROC曲线分析血清NRAV水平对RSV肺炎的诊断价值。

RSV组患儿血清NRAV水平高于对照组,第1秒用力呼气容积占预计值百分比（FEV₁%）及FEV₁/用力肺活量（FVC）均低于对照组（均P＜0.05）。不同严重程度RSV肺炎患儿血清NRAV水平、FEV₁%及FEV₁/FVC比较差异有统计学意义（均P＜0.05）。低危组、中危组、高危组RSV肺炎患儿血清NRAV水平依次升高,FEV₁%及FEV₁/FVC均依次下降,组间两两比较差异有统计学意义（均P＜0.05）。RSV肺炎患儿血清NRAV水平与FEV₁%及FEV₁/FVC均呈负相关（均P＜0.05）。Logistics分析显示,血清NRAV水平升高、FEV₁%及FEV₁/FVC水平下降均是影响RSV肺炎严重程度的独立危险因素（均P＜0.05）。ROC曲线分析显示,血清NRAV水平诊断RSV肺炎的曲线下面积为0.843,敏感度为76.0%,特异度为88.2%,最佳截断值为1.14。

RSV肺炎患儿血清NRAV水平升高且随着疾病严重程度的加重而升高,其水平可反映肺功能,对RSV肺炎具有一定诊断价值。

     

Role of human beta-defensin-2 during tumor necrosis factor-alpha/NF-kappaB-mediated innate antiviral response against human respiratory syncytial virus

Human respiratory syncytial virus (RSV) constitutes a highly pathogenic virus that infects lung epithelial cells to cause a wide spectrum of respiratory diseases. Our recent studies have revealed the existence of an interferon-alpha/beta-independent, innate antiviral response against RSV that was dependent on activation of NF-kappaB. We demonstrated that NF-kappaB inducing pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF) confers potent antiviral function against RSV in an NF-kappaB-dependent fashion, independent of interferon-alpha/beta. During our efforts to study this pathway, we identified HBD2 (human beta-defensin-2), a soluble secreted cationic protein as an antiviral factor induced during NF-kappaB-dependent innate antiviral activity in human lung epithelial cells. Our results demonstrated that HBD2 is induced by TNF and RSV in an NF-kappaB-dependent manner. Induction of HBD2 in infected cells was mediated by the paracrine/autocrine action of TNF produced upon RSV infection. HBD2 plays a critical role during host defense, because purified HBD2 drastically inhibited RSV infection. We also show that the antiviral mechanism of HBD2 involves blocking of viral cellular entry possibly because of destabilization/disintegration of the viral envelope. The important role of HBD2 in the innate response was also evident from loss of antiviral activity of TNF upon HBD2 silencing by short interfering RNA. The in vivo physiological relevance of HBD2 in host defense was apparent from induction of murine beta-defensin-4 (murine counterpart of HBD2) in lung tissues of RSV-infected mice. Thus, HBD2 functions as an antiviral molecule during NF-kappaB-dependent innate antiviral immunity mediated by the autocrine/paracrine action of TNF.     

Vaccine-induced immunopathology during bovine respiratory syncytial virus infection: exploring the parameters of pathogenesis

The bovine and human respiratory syncytial viruses cause severe lower respiratory tract infections. Effective vaccines against the respiratory syncytial viruses have been lacking since vaccine failures in the 1960s and 1970s. In this report, we describe a bovine respiratory syncytial virus (bRSV) challenge model in which both classical bRSV respiratory infection and vaccine-enhanced immune pathology were reproduced. The classical, formalin-inactivated (FI) bRSV vaccine that has been associated with vaccine failure was efficient in inducing high antibody titers and reducing viral loads but also primed calves for a far more serious enhanced respiratory disease after a bRSV challenge, thereby mimicking the enhanced clinical situation in FI human RSV (hRSV)-immunized and hRSV-infected infants in the 1960s. We show that immunization with FI-bRSV mainly primes a Th2-like inflammatory response that is characterized by a significant eosinophilic influx in the bronchial alveolar lung fluid and lung tissues and high levels of immunoglobulin E serum antibodies. The current model may be useful in the evaluation of new bRSV candidate vaccines for potency and safety.     

婴幼儿呼吸道合胞病毒感染严重程度与基因分型及血清炎症因子水平的相关性

目的 探讨婴幼儿呼吸道合胞病毒(respiratory syncytial virus,RSV)感染严重程度与病毒基因分型及血清IL10、IL17、IL27水平的相关性。 方法 选取2017年3月1日至2018年3月1日我院收治的77例呼吸道合胞病毒感染患儿作为研究对象,对患儿鼻咽部位的分泌物进行取样,对呼吸道合胞病毒亚型和基因型进行检测,按照病情的严重程度,将患者分为轻度组、中度组和重度组。对各组患儿病情程度,RSV亚型分布及血清IL10、IL17、IL27水平进行比较。 结果 轻度组患儿病情评分为(1.22±0.11)分,中度组为(4.89±0.98)分,重度组为(7.08±0.97)分。77份RSV阳性标本共检出A亚型48例,B亚型29例,其中轻度组、中度组及重度组患者中的A亚型感染人数比例分别为52.17%,60.00%,78.95%。A亚型病毒中NA1型为优势基因型。重度组患儿中NA1型的比例显著高于中度组和轻度组。B亚型病毒中BA9为优势基因型。轻度组患儿BA9型比例显著高于中度组和重度组。轻度组患儿血清IL10、IL17、IL27水平最低,重度组IL10、IL17、IL27的水平最高(均P结论 不同病情程度呼吸道合胞病毒感染患儿其病毒基因型分布及血清炎症因子的水平存在显著差异,病毒基因型与疾病的严重程度具有相关性。病毒基因型及血清炎症因子的水平可以作为判断此类患儿病程的标志物。     

Immunoprophylaxis of respiratory syncytial virus infection in the infant ferret.

Infant ferrets can be protected from respiratory syncytical virus challenge at 3 days of age by gestational infection of their mothers. Ferrets acquire their immunity to respiratory syncytial virus postpartum via immunizing products of lactation. The level of protection against viral replication correlates with the maternal serum neutralizing titer or a concomitant factor. Passive administration of adult ferret serum with a neutralizing titer of 1:1024 or greater, either i.p. or orally does not confer immunity. A nonantibody-mediated protective mechanism appears to play an important role in protecting the infant ferret from respiratory syncytial virus replication. Our findings allow the testing of the efficacy of future human vaccines before human clinical trial.