Effect of experimental rhinovirus 16 colds on airway hyperresponsiveness to histamine and interleukin-8 in nasal lavage in asthmatic subjects in vivo

Lassa and Mopeia virus replication in human monocytes/macrophages and in endothelial cells: different effects on IL-8 and TNF-alpha gene expression

Cells of the mononuclear and endothelial lineages are targets for viruses which cause hemorrhagic fevers (HF) such as the filoviruses Marburg and Ebola, and the arenaviruses Lassa and Junin. A recent model of Marburg HF pathogenesis proposes that virus directly causes endothelial cell damage and macrophage release of TNF-alpha which increases the permeability of endothelial monolayers [Feldmann et al. , 1996]. We show that Lassa virus replicates in human monocytes/macrophages and endothelial cells without damaging them. Human endothelial cells (HUVEC) are highly susceptible to infection by both Lassa and Mopeia (a non-pathogenic Lassa-related arenavirus). Whereas monocytes must differentiate into macrophages before supporting even low level production of these viruses, the virus yields in the culture medium of infected HUVEC cells reach more than 7 log10 PFU/ml without cellular damage. In contrast to filovirus, Lassa virus replication in monocytes/macrophages fails to stimulate TNF-alpha gene expression and even down-regulates LPS-stimulated TNF-alpha mRNA synthesis. The expression of IL-8, a prototypic proinflammatory CXC chemokine, was also suppressed in Lassa virus infected monocytes/macrophages and HUVEC on both the protein and mRNA levels. This contrasts with Mopeia virus infection of HUVEC in which neither IL-8 mRNA nor protein are reduced. The cumulative down-regulation of TNF-alpha and IL-8 expression could explain the absence of inflammatory and effective immune responses in severe cases of Lassa HF.

Experimental rhinovirus 16 infection causes variable airway obstruction in subjects with atopic asthma

Exacerbations of asthma are often associated with rhinovirus infections. However, it has not been investigated whether rhinovirus infection can induce variable airway obstruction in asthma. We examined the effect of experimental rhinovirus 16 (RV16) infection on daily home recordings of FEV(1) in 27 subjects (nonsmoking, atopic, mildly asthmatic) who participated in a parallel placebo-controlled study. The subjects used a microspirometer to record FEV(1) three times daily from 4 d before until 10 d after RV16 (n = 19) or placebo (n = 8) inoculation. In addition, symptoms of asthma and symptoms of common cold were scored. Airway hyperresponsiveness to histamine was measured 3 d before and on Days 4 and 11 after RV16/placebo administration. Home recordings of FEV(1) decreased significantly after RV16 infection, reaching a minimum 2 d after inoculation (ANOVA, p </= 0.005), which was significantly different from placebo (p </= 0.004). In the RV16 group the lowest FEV(1) (expressed as a percentage of personal best) during Days 0-3 after infection (mean +/- SEM: 78.7 +/- 2.6% versus baseline: 85.6 +/- 1.2%, p = 0.008) correlated significantly with the cold score (r = -0.47, p = 0.04), asthma score (r = -0.47, p = 0.04), and with the decrease in airway hyperresponsiveness on Day 4 as compared with baseline (r = 0.50, p = 0.03). We conclude that experimental RV16 infection augments variable airway obstruction in subjects with asthma. This favors a causative role for rhinovirus colds in asthma exacerbations, and is in keeping with rhinovirus-induced worsening of airway inflammation.

Rhinovirus-16 colds in healthy and in asthmatic subjects: similar changes in upper and lower airways

Rhinovirus (RV) infections appear to precipitate most asthma exacerbations. To investigate whether RV-16 induces different inflammatory changes in upper and lower airways of asthmatic and healthy subjects, we inoculated 10 nonatopic healthy and 11 atopic asthmatic adults with 2,000 TCID50 RV-16. Subjects recorded symptoms and peak flow daily; and they underwent spirometry, methacholine challenge (PC20), nasal lavage, and sputum induction at baseline and on Days 2, 4, 15, and 29 d after inoculation. One asthmatic subject developed an exacerbation requiring prednisone treatment 5 d after inoculation. The cold symptom severity (Jackson score) did not differ between groups. During the cold, asthma symptoms increased slightly from baseline in the asthmatic group; and PC20 decreased in the healthy group. However, peak flow, bronchodilator use, and spirometry did not change in either group. At baseline, asthmatics had higher neutrophils, eosinophils, and interleukin (IL)-6 in nasal lavage. After inoculation, both groups developed significant increases in nasal neutrophils, IL-6 and IL-8, and modest increases in sputum neutrophils and IL-6, but not IL-8. However, these changes did not differ between groups. IL-5, interferon-gamma, and RANTES were detected only in nasal lavages from two asthmatic subjects, who had the most severe colds. IL-11 was not detected in any sample. We conclude that inflammatory responses of upper and lower airways during RV-16 colds are similar in asthmatic and healthy subjects, and that RV-16 infection is not by itself sufficient to provoke clinical worsening of asthma.

Rhinovirus replication causes RANTES production in primary bronchial epithelial cells

The mechanisms by which rhinovirus (RV) infections produce lower airway symptoms in asthmatic individuals are not fully established. To determine effects of RV infection on lung epithelial cells, primary human bronchial epithelial (BE) cells were infected with either RV16 or RV49, and viral replication, cell viability, and cell activation were measured. Both viral serotypes replicated in BE cells at 33 degrees C (DeltaTCID50 / ml = 2 to 2.5 log units) and at 37 degrees C (DeltaTCID50 /ml = 1.6 log units), but only high doses of RV49 (10(6) TCID50 /ml) caused cytopathic effects and reduced cell viability. In addition, regulated on activation, normal T cells expressed and secreted (RANTES) secretion was increased in epithelial cells infected with RV16 or RV49 (243 and 398 pg/ml versus 13 pg/ml uninfected control cells), and a similar pattern was seen for RANTES messenger RNA. RV infection also caused increased secretion of interleukin-8 and granulocyte macrophage colony-stimulating factor, but did not alter expression of either intercellular adhesion molecule-1 or human leukocyte-associated antigen-DR. These observations suggest that RVs can replicate in lower airway cells in vivo, and support epidemiologic studies that link RV with lower respiratory illnesses. Further, RV-induced secretion of RANTES and other cytokines could trigger antiviral immune responses in vivo, but these effects could also contribute to the pathogenesis of respiratory symptoms in subjects with asthma.

Rhinovirus infections: induction and modulation of airways inflammation in asthma

There is renewed interest in the role of respiratory virus infections in the pathogenesis of asthma and in the development of exacerbations in pre-existing disease. This is due to the availability of new molecular and experimental tools. Circumstantial evidence points towards a potentially causative role as well as to possibly protective effects of certain respiratory viruses in the cause of allergic asthma during early childhood. In addition, it now has become clear that exacerbations of asthma, in children as well as adults, are mostly associated with respiratory virus infections, with a predominant role of the common cold virus: rhinovirus. Careful human in vitro and in vivo experiments have shown that rhinovirus can potentially stimulate bronchial epithelial cells to produce pro-inflammatory chemokines and cytokines, may activate cholinergic- or noncholinergic nerves, increase epithelial-derived nitric oxide synthesis, upregulate local ICAM-1 expression, and can lead to nonspecific T-cell responses and/or virus-specific T-cell proliferation. Experimental rhinovirus infections in patients with asthma demonstrate features of exacerbation, such as lower airway symptoms, variable airways obstruction, and bronchial hyperresponsiveness, the latter being associated with eosinophil counts and eosinophilic cationic protein levels in induced sputum. This suggests that multiple cellular pathways can be involved in rhinovirus-induced asthma exacerbations. It is still unknown whether these mechanisms are a distinguishing characteristic of asthma. Because of the limited effects of inhaled steroids during asthma exacerbations, new therapeutic interventions need to be developed based on the increasing pathophysiological knowledge about the role of viruses in asthma.

Rhinovirus and respiratory syncytial virus in wheezing children requiring emergency care. IgE and eosinophil analyses

This cross-sectional emergency department study of 70 wheezing children and 59 control subjects (2 mo to 16 yr of age) examined the prevalence of respiratory viruses and their relationship to age, atopic status, and eosinophil markers. Nasal washes were cultured for respiratory viruses, assayed for respiratory syncytial virus (RSV) antigen, and tested for coronavirus and rhinovirus RNA using reverse transcription-PCR (RT-PCR). Also evaluated were eosinophil numbers and eosinophil cationic protein (ECP) in both nasal washes and serum, along with total IgE and specific IgE antibody in serum. Respiratory viruses were detected in 82% (18 of 22) of wheezing infants younger than 2 yr of age and in 83% (40 of 48) of older wheezing children. The predominant pathogens were RSV in infants (detected in 68% of wheezing subjects) and rhinovirus in older wheezing children (71%), and both were strongly associated with wheezing (p < 0.005). RSV was largely limited to wheezing children younger than 24 mo of age, but rhinovirus was detected by RT-PCR in 41% of all infants and in 35% of nonwheezing control subjects older than 2 yr of age. After 2 yr of age the strongest odds for wheezing were observed among those who had a positive RT-PCR test for rhinovirus together with a positive serum radioallergosorbent testing (RAST), nasal eosinophilia, or elevated nasal ECP (odds ratios = 17, 21, and 25, respectively). Results from this study demonstrate that a large majority of emergent wheezing illnesses during childhood (2 to 16 yr of age) can be linked to infection with rhinovirus, and that these wheezing attacks are most likely in those who have rhinovirus together with evidence of atopy or eosinophilic airway inflammation.

Quantification of cytokines and inflammatory mediators in samples of nasopharyngeal secretions with unknown dilution

In the study of inflammatory mechanisms in the upper respiratory tract, the unknown dilution of collected samples of nasal secretions poses a serious problem for interpretation of the measured concentrations of various substances in the specimens. We investigated the magnitude of the dilution problem in a true clinical research situation and determined the validity of using the levels of total protein, albumin, and secretory IgA in nasal secretions to correct for the unknown dilution. The study samples consisted of simultaneously obtained nasopharyngeal aspirates and nasal lavage specimens from 52 children with upper respiratory tract infection. The dilution factors of the nasal lavage specimens varied widely between 1.8 and 432 (median, 11.2). Of the three proteins studied, total protein had the narrowest inter-subject variation in the nasal secretions of the children and thus seemed to provide the best standardization method for comparing levels of substances between individuals. Concentrations of IL-6 standardized with total protein correlated significantly better with the true IL-6 concentrations in the nasal secretions than did IL-6 levels measured in the nasal lavage specimens without standardization (p = 0.049). These findings suggest that the most common current practice of measuring substances in nasopharyngeal specimens, i.e. measuring without correction for the dilution, may produce "false-negative" results. Potentially important information on inflammatory mechanisms may be undetected if false-negative results mask real differences between groups. The use of exogenous markers of dilution might improve the accuracy of quantifying substances in nasal secretions.

The role of oxidative stress in rhinovirus induced elaboration of IL-8 by respiratory epithelial cells

A direct correlation has been reported between the severity of symptoms associated with rhinovirus infection and the concentration of interleukin-8 in nasal secretions. The purpose of these studies was to examine the mechanism of rhinovirus-induced IL-8 elaboration. Rhinovirus infection induced oxidative stress in Beas-2b cells and the concentration of H2O2 in supernatant media from rhinovirus challenged cells was 12.5 +/- 6.1 microM 1 h after challenge compared to 0.7 +/- 0.3 microM in supernatant from control cells. N-acetyl cysteine inhibited RV-induced NF-kappaB activation and IL-8 elaboration. IL-8 concentrations were 36 +/- 2 pg/ml and 10 +/- 1 pg/ml 6 h after virus challenge in untreated and NAC-treated (30 mM NAC) cells, respectively. Despite the effects of NAC on IL-8 elaboration and NF-kappaB activation, RV stimulated increases in supernatant H2O2 were not altered by NAC. These data suggest that RV stimulation of IL-8 in respiratory epithelium is mediated through production of oxidative species and the subsequent activation of NF-kappaB.

Association of rhinovirus infections with asthma

Rhinoviruses are the most common cause of the common cold, but they can cause more severe illnesses in people with underlying lung disorders such as asthma, chronic obstructive pulmonary disease, or cystic fibrosis. Epidemiologic studies with sensitive detection methods such as PCR have identified rhinovirus infection as a major source of asthma exacerbations in both children and adults, especially during the spring and fall. Since rhinoviruses cause little tissue destruction, it is presumed that the immune response to the infection may play an important role in the pathogenesis of rhinovirus-induced exacerbations of asthma. This review examines the epidemiologic association between rhinovirus infections and exacerbations of asthma and outlines current information on immune responses to rhinovirus infection and potential connections between antiviral responses and preexisting allergic inflammation. Finally, current and future strategies for treating rhinovirus infections and virus-induced exacerbations of asthma are discussed.

Rhinoviruses: important respiratory pathogens

The most frequent viruses associated with respiratory infections are human rhinoviruses (HRVs). Although the majority of HRV infections are mild and self-limited, HRV is an important cause of respiratory disease across all age groups. Recent studies using reverse transcriptase polymerase chain reaction to detect HRV genomes have established the importance of HRVs in predisposing to or causing otitis media, sinusitis and exacerbations of asthma, as well as other lower respiratory tract disorders. Among elderly people, infants and immunocompromised hosts HRV infections are often associated with lower respiratory tract morbidity and rarely mortality. How often active viral replication occurs in the middle ear, sinuses or the lower respiratory tract remains to be determined. However, the high incidence of HRV infections and their frequent association with upper and lower respiratory tract complications highlight the need for more effective means of prevention and treatment.

Elevated levels of IL-8 in dengue hemorrhagic fever

Dengue virus causes dengue fever, a mild febrile illness, and at times dengue hemorrhagic fever (DHF), a severe illness the pathogenesis of which is not fully understood. Given the crucial roles played by interleukin-8 (IL-8) as a chemoattractant cytokine and in inflammatory processes, levels of circulating IL-8 in the sera and IL-8 mRNA in the peripheral blood mononuclear cells (PBMC) were measured in 99 patients of a recent dengue epidemic that occurred in India in 1996 and in 21 normal healthy controls. Twenty-six of the patients had dengue fever (DF) and the remaining 73 were diagnosed as having different grades of DHF. All the control normal sera were negative for IL-8, so were their PBMC for IL-8 mRNA. Increased levels of IL-8 in the sera and IL-8 mRNA in their PBMC were observed in patients with severe illness of DHF grades III and IV. Only two out of 26 patients of DF and one out of 10 DHF grade I patient were positive for IL-8 and all three deteriorated to DHF grade IV within 24 hr. All six patients of DHF grade IV who died had higher serum level of IL-8 above 200 pg/ml, the highest being 5,568 pg/ml in one patient; the presence of mRNA for IL-8 was very high in all patients. A striking correlation was observed between increased levels of IL-8 and severe DHF, with greater levels in patients with increased grade of the disease and death. These results suggest that IL-8 may have an important role and may be an indicator of increasing severity of the disease and death.

Rhinovirus infection induces mucus hypersecretion

Rhinorrhea is a prominent symptom of the common cold. Although increases in vascular permeability and serous cell secretion have been demonstrated in human nasal mucus during active rhinovirus infections, changes in mucin constituents have not been quantified. Nonallergic (n = 48) and asymptomatic allergic rhinitis (n = 32) subjects were inoculated with rhinovirus type hanks before the spring allergy season. Nasal lavages were performed before inoculation (day 0), then daily for 5 days afterward. The subjects were divided into infected and noninfected groups on the basis of evidence of successful rhinovirus infection (nasal shedding of virus or fourfold increases in specific serum antibodies). Concentrations of interleukin (IL)-8, markers of vascular leak (IgG), seromucous cells (lysozyme), and mucoglycoprotein exocytosis [7F10-immunoreactive mucin (7F10-irm) and Alcian blue staining of acidic mucoglycoproteins] were measured in lavage fluids. The infected subgroup had maximal increases in nasal lavage fluid concentrations of IL-8 (sevenfold), IgG (fourfold), total protein (twofold), and gel-phase 7F10-irm (twofold) on day 3. There were no differences between infected allergic and nonallergic subjects. IL-8 and gel-phase 7F10-irm were significantly higher in infected than in noninfected subjects. In addition to promoting plasma exudation, rhinovirus hanks infection increases IL-8 and gel-phase mucin secretion. These processes may contribute to a progression from watery rhinorrhea to mucoid discharge, with mild neutrophilic infiltration during the common cold.

Effects of photochemical air pollution and allergen exposure on upper respiratory tract inflammation in asthmatics

Asthma is an inflammatory disease of the airways, and exacerbations of this disease have been associated with high levels of air pollution. The objective of this study was to examine whether ambient air pollution and/or allergen exposure induces inflammatory changes in the upper airways of asthmatics. Sixty patients with intermittent to severe persistent asthma visited the Hospital's Out Patient Clinic every 2 wk for a period of 3 mo, and on each visit a nasal lavage was obtained. Associations between nasal inflammatory parameters and seasonal allergens and/or air pollution exposures were analyzed using linear regression analysis. The study ran from July 3 to October 6, 1995, during which period ozone (8-h mean: 80 micrograms/m3) and PM10 (24-h mean: 40 micrograms/m3) were the major air pollutants; the major aeroallergen was mugwort pollen (24-h mean: 27 pollen grains/m3). Effects on both cellular and soluble markers in nasal lavage were demonstrated for both ozone and mugwort pollen, but not for PM10. Ambient ozone exposure was associated with an increase in neutrophils (112% per 100 micrograms/m3 increase in 8-h average ozone concentration), eosinophils (176%), epithelial cells (55%), IL-8 (22%), and eosinophil cationic protein (ECP) (19%). Increases in environmental mugwort pollen counts were associated with an increase in nasal eosinophils (107% per 100 pollen/m3) and ECP (23%), but not with neutrophils, epithelial cells, or lL-8. This study demonstrated that both ambient ozone and allergen exposure are associated with inflammatory responses in the upper airways of subjects with asthma, although the type of inflammation is qualitatively different.

Airway hyperresponsiveness: first eosinophils and then neuropeptides

Airway hyperreactivity to bronchoconstrictor mediators is a main characteristic in the majority of asthmatic patients and correlates well with the severity of the disease. The airways of asthmatic patients are characterized by an inflammatory state resulting in activation of lung tissue cells and attraction and infiltration of leukocytes from the blood. The accumulation of eosinophilic leukocytes is a prominent feature of inflammatory reactions that occurs in allergic asthma. The increase in number of eosinophils is important since it correlates in time with an increase in bronchial hyperresponsiveness. Viral respiratory infections can also induce eosinophilia and airway hyperresponsiveness in humans and animals and can worsen asthmatic reactions. This report reviews current opinions on the relationship between inflammation-induced eosinophil accumulation/activation and the development of airway hyperresponsiveness and the possible role for sensory neuropeptides in this process. Firstly, CC chemokines play an important role in allergic airway inflammation and respiratory viral infections leading to eosinophil recruitment. Secondly, it can be concluded that IL5 is involved in the development in airway hyperresponsiveness. IL5 has profound effects on eosinophils as promoter of growth, differentiation and proliferation, chemoattractant, activator and primer. However, it is conceivable that in animal models for allergic asthma besides IL5 other regulatory mediators may be involved in eosinophil migration and activation in the lung, which in turn will lead to airway hyperresponsiveness. Recent data support the possible role of eotaxin and its eosinophil-specific receptor CCR-3 in eosinophil chemotaxis and activation in allergic asthma. Moreover, it is suggested that the development of airway eosinophilia in vivo involves a two-step mechanism, elicited by eotaxin and IL5. The precise mechanism by which eosinophils induce bronchial hyperresponsiveness is at present unknown. Sensory neuropeptides could be important mediators in this process, since it has been demonstrated that airway nerves are surrounded by and infiltrated with eosinophils after antigen challenge. Sensory neuropeptides could be the final, more downstream, common pathway after eosinophil infiltration and activation in inducing airway hyperresponsiveness due to allergen inhalation or respiratory viral infections. In conclusion, in the process of the development of airway hyperresponsiveness observed during viral infections or in allergic asthma, the IL5/eotaxin-induced infiltration and activation of eosinophils in the airways is evident. Following this step, eosinophil-derived inflammatory mediators will induce the release of sensory neuropeptides (possibly NK2-receptor activating tachykinins) which in turn will lead to airway hyperresponsiveness.

Experimental rhinovirus 16 infection. Effects on cell differentials and soluble markers in sputum in asthmatic subjects

Asthma exacerbations are often associated with respiratory virus infections, particularly with rhinovirus. In the present study we investigated the effect of experimental rhinovirus 16 (RV16) infection on airway inflammation as assessed by analysis of hypertonic saline-induced sputum. Twenty-seven nonsmoking atopic, mildly asthmatic subjects participated in a placebo-controlled parallel study. RV16 (n = 19) or its diluent (n = 8) was nasally administered. Sputum inductions were performed at entry and on Days 2 and 9 after inoculation, and airway responsiveness to histamine (PC20) was measured on Days 4 and 11. Cell differentials and levels of albumin, eosinophil cationic protein (ECP), IL-8, and IL-6 were determined. The cellular origin of IL-8 was investigated by intracellular staining. RV infection was confirmed by culture and/or by antibody titer rise in each of the RV16-treated subjects. There were no significant changes in the sputum differentials of nonsquamous cells (MANOVA, p > or = 0.40). In the RV16 group, there was a significant increase in the levels of ECP, IL-8, and IL-6 at Day 2 after infection (p < 0.05), whereas the albumin levels did not change (p = 0.82). The levels of IL-8 and IL-6 remained elevated for as long as 9 d after infection (p < 0.05). The increase in the percentage of IL-8 positive cells at Day 2 after infection could be attributed to the increase in IL-8 positive neutrophils (p < 0.02). There was a significant decrease in PC20 at Day 4 (p = 0.02), which was no longer significant at Day 11 (p = 0.19). The decrease in PC20 correlated significantly with the increase in ECP in the first week (r = -0.60) and with the change in the percentage eosinophils in the second week after inoculation (r = -0.58). We conclude that experimental RV16 infection in atopic asthmatic subjects increases airway hyperresponsiveness in conjunction with augmented airway inflammation, as reflected by an increase in ECP, IL-8, and IL-6 in sputum. Our results suggest that the RV16-enhanced airway hyperresponsiveness is associated with eosinophilic inflammation.