Nasal-secretion leukocyte populations determined by flow cytometry during acute rhinovirus infection

Untargeted analysis of the airway proteomes of children with respiratory infections using mass spectrometry based proteomics

The upper airway - which consists mainly of the naso- and oro-pharynx - is the first point of contact between the respiratory system and microbial organisms that are ubiquitous in the environment. It has evolved highly specialised functions to address these constant threats whilst facilitating seamless respiratory exchange with the lower respiratory tract. Dysregulation of its critical homeostatic and defence functions can lead to ingress of pathogens into the lower respiratory tract, potentially leading to serious illness. Systems-wide proteomic tools may facilitate a better understanding of mechanisms in the upper airways in health and disease. In this study, we aimed to develop a mass spectrometry based proteomics method for characterizing the upper airways proteome. Naso- and oropharyngeal swab samples used in all our experiments had been eluted in the Universal Transport Media (UTM) containing significantly high levels of bovine serum albumin. Our proteomic experiments tested the optimal approach to characterize airway proteome on swab samples eluted in UTM based on the number of proteins identified without BSA depletion (Total proteome: Protocol A) and with its depletion using a commercial kit; Allprep, Qiagen (cellular proteome: Protocol B, Ci, and Cii). Observations and lessons drawn from protocol A, fed into the design and implementation of protocol B, and from B to protocol Ci and finally Cii. Label free proteome quantification was used in Protocol A (n = 6) and B (n = 4) while commercial TMT 10plex reagents were used for protocols Ci and ii (n = 83). Protocols Ci and ii were carried out under similar conditions except for the elution gradient: 3 h and 6 h respectively. Swab samples tested in this study were from infants and children with and without upper respiratory tract infections from Kilifi County Hospital on the Kenyan Coast. Protocol A had the least number of proteins identified (215) while B produced the highest number of protein identifications (2396). When Protocol B was modified through sample multiplexing with TMT to enable higher throughput (Protocol Ci), the number of protein identified reduced to 1432. Modification of protocol Ci by increasing the peptide elution time generated Protocol Cii that substantially increased the number of proteins identified to 1875. The coefficient of variation among the TMT runs in Protocol Cii was <20%. There was substantial overlap in the identity of proteins using the four protocols. Our method was were able to identify marker proteins characteristically expressed in the upper airway. We found high expression levels of signature nasopharyngeal and oral proteins, including BPIFA1/2 and AMY1A, as well as a high abundance of proteins related to innate and adaptive immune function in the upper airway. We have developed a sensitive systems-level proteomic assay for the systematic quantification of naso-oro-pharyngeal proteins. The assay will advance mechanistic studies of respiratory pathology, by providing an untargeted and hypothesis-free approach of examining the airway proteome.

A Role for Neutrophils in Viral Respiratory Disease

Neutrophils are immune cells that are well known to be present during many types of lung diseases associated with acute respiratory distress syndrome (ARDS) and may contribute to acute lung injury. Neutrophils are poorly studied with respect to viral infection, and specifically to respiratory viral disease. Influenza A virus (IAV) infection is the cause of a respiratory disease that poses a significant global public health concern. Influenza disease presents as a relatively mild and self-limiting although highly pathogenic forms exist. Neutrophils increase in the respiratory tract during infection with mild seasonal IAV, moderate and severe epidemic IAV infection, and emerging highly pathogenic avian influenza (HPAI). During severe influenza pneumonia and HPAI infection, the number of neutrophils in the lower respiratory tract is correlated with disease severity. Thus, comparative analyses of the relationship between IAV infection and neutrophils provide insights into the relative contribution of host and viral factors that contribute to disease severity. Herein, we review the contribution of neutrophils to IAV disease pathogenesis and to other respiratory virus infections.

Virus infection-induced bronchial asthma exacerbation

Infection with respiratory viruses, including rhinoviruses, influenza virus, and respiratory syncytial virus, exacerbates asthma, which is associated with processes such as airway inflammation, airway hyperresponsiveness, and mucus hypersecretion. In patients with viral infections and with infection-induced asthma exacerbation, inflammatory mediators and substances, including interleukins (ILs), leukotrienes and histamine, have been identified in the airway secretions, serum, plasma, and urine. Viral infections induce an accumulation of inflammatory cells in the airway mucosa and submucosa, including neutrophils, lymphocytes and eosinophils. Viral infections also enhance the production of inflammatory mediators and substances in airway epithelial cells, mast cells, and other inflammatory cells, such as IL-1, IL-6, IL-8, GM-CSF, RANTES, histamine, and intercellular adhesion molecule-1. Viral infections affect the barrier function of the airway epithelial cells and vascular endothelial cells. Recent reports have demonstrated augmented viral production mediated by an impaired interferon response in the airway epithelial cells of asthma patients. Several drugs used for the treatment of bronchial asthma reduce viral and pro-inflammatory cytokine release from airway epithelial cells infected with viruses. Here, I review the literature on the pathogenesis of the viral infection-induced exacerbation of asthma and on the modulation of viral infection-induced airway inflammation.

Effects of Echinaforce® treatment on ex vivo-stimulated blood cells

The herb Echinacea purpurea, also called purple coneflower, is regarded as an immune modulator. This study examined changes in cytokine production in blood samples from 30 volunteers before and during 8-day oral administration with an ethanolic extract of fresh Echinacea purpurea (Echinaforce(®)). Daily blood samples were ex vivo stimulated by LPS/SEB or Zymosan and analysed for a series of cytokines and haematological and metabolic parameters. Treatment reduced the proinflammatory mediators TNF-α and IL-1β by up to 24% (p<0.05) and increased anti-inflammatory IL-10 levels by 13% (p<0.05) in comparison to baseline. This demonstrated a substantial overall anti-inflammatory effect of Echinaforce(®) for the whole group (n=28). Chemokines MCP-1 and IL-8 were upregulated by 15% in samples from subjects treated with Echinaforce(®) (p<0.05). An analysis of a subgroup of volunteers who showed low pre-treatment levels of the cytokines MCP-1, IL-8, IL-10 or IFN-γ (n=8) showed significant stimulation of these factors upon Echinaforce(®) treatment (30-49% increases; p<0.05), whereas the levels in subjects with higher pre-treatment levels remained unaffected. We chose the term "adapted immune-modulation" to describe this observation. Volunteers who reported high stress levels (n=7) and more than 2 colds per year experienced a significant transient increase in IFN-γ upon Echinaforce(®) treatment (>50%). Subjects with low cortisol levels (n=11) showed significant down-regulation of the acute-phase proteins IL1-β, IL-6, IL-12 and TNF-α by Echinaforce(®) (range, 13-25%), while subjects with higher cortisol levels showed no such down-regulation. This is the first ex vivo study to demonstrate adapted immune-modulation by an Echinacea preparation. While Echinaforce(®) did not affect leukocyte counts, we speculate that the underlying therapeutic mechanism is based on differential multi-level modulation of the responses of the different types of leukocytes. Echinaforce(®) thus regulates the production of chemokines and cytokines according to current immune status, such as responsiveness to exogenous stimuli, susceptibility to viral infection and exposure to stress.

Rhinoviruses, allergic inflammation, and asthma

Viral infections affect wheezing and asthma in children and adults of all ages. In infancy, wheezing illnesses are usually viral in origin, and children with more severe wheezing episodes are more likely to develop recurrent episodes of asthma and to develop asthma later in childhood. Children who develop allergen-specific immunoglobulin E (allergic sensitization) and those who wheeze with human rhinoviruses (HRV) are at especially high risk for asthma. In older children and adults, HRV infections generally cause relatively mild respiratory illnesses and yet contribute to acute and potentially severe exacerbations in patients with asthma. These findings underline the importance of understanding the synergistic nature of allergic sensitization and infections with HRV in infants relative to the onset of asthma and in children and adults with respect to exacerbations of asthma. This review discusses clinical and experimental evidence of virus-allergen interactions and evaluates theories which relate immunologic responses to respiratory viruses and allergens to the pathogenesis and disease activity of asthma. Greater understanding of the relationship between viral respiratory infections, allergic inflammation, and asthma is likely to suggest new strategies for the prevention and treatment of asthma.

Lycopene enrichment of cultured airway epithelial cells decreases the inflammation induced by rhinovirus infection and lipopolysaccharide

Rhinovirus infection results in increased release of inflammatory mediators from airway epithelial cells in asthma. As an antioxidant, lycopene offers protection from adverse effects of inflammation. The aim of this study was to find an appropriate method of lycopene enrichment of airway epithelial cells and to determine the effects of lycopene enrichment on the inflammatory response of cells infected by rhinovirus or exposed to lipopolysaccharide. Lycopene enrichment of airway epithelial cells using solubilisation in tetrahydrofuran versus incorporation in liposomes was compared. After determining that solubilisation of lycopene in tetrahydrofuran was the most suitable method of lycopene supplementation, airway epithelial cells (Calu-3) were incubated with lycopene (dissolved in tetrahydrofuran) for 24 h, followed by rhinovirus infection or lipopolysaccharide exposure for 48 h. The release of interleukin-6, interleukin-8 and interferon-gamma induced protein-10 (IP-10) and their messenger RNA levels were measured using enzyme linked immunosorbent assay and reverse transcription polymerase chain reaction, respectively. Viral replication was measured by tissue culture infective dose of 50% assay. Lycopene concentration of cells and media were analysed using high-performance liquid chromatography. Preincubation of airway epithelial cells with lycopene (dissolved in tetrahydrofuran) delivered lycopene into the cells and resulted in a 24% reduction in interleukin-6 after rhinovirus-1B infection, 31% reduction in IP-10 after rhinovirus-43 infection and 85% reduction in rhinovirus-1B replication. Lycopene also decreased the release of IL-6 and IP-10 following exposure to lipopolysaccharide. We conclude that lycopene has a potential role in suppressing rhinovirus induced airway inflammation.

Human rhinoviruses: the cold wars resume

BACKGROUND

Human rhinoviruses (HRVs) are the most common cause of viral illness worldwide but today, less than half the strains have been sequenced and only a handful examined structurally. This viral super-group, known for decades, has still to face the full force of a molecular biology onslaught. However, newly identified viruses (NIVs) including human metapneumovirus and bocavirus and emergent viruses including SARS-CoV have already been exhaustively scrutinized. The clinical impact of most respiratory NIVs is attributable to one or two major strains but there are 100+ distinct HRVs and, because we have never sought them independently, we must arbitrarily divide the literature's clinical impact findings among them. Early findings from infection studies and use of inefficient detection methods have shaped the way we think of 'common cold' viruses today.

OBJECTIVES

To review past HRV-related studies in order to put recent HRV discoveries into context.

RESULTS

HRV infections result in undue antibiotic prescriptions, sizable healthcare-related expenditure and exacerbation of expiratory wheezing associated with hospital admission.

CONCLUSION

The finding of many divergent and previously unrecognized HRV strains has drawn attention and resources back to the most widespread and frequent infectious agent of humans; providing us the chance to seize the advantage in a decades-long cold war.

Upper airway viral infections

Upper airway viral infections (URI) are a major cause of absence from school and work. Although morbidity is low in most of the subjects, the complications of URI, including otitis media, sinusitis and exacerbations of asthma and chronic obstructive pulmonary disease (COPD) have an enormous health impact. Despite the major health care consequences associated with these complications, our understanding of how URI trigger upper airway symptoms and cause exacerbations of lower airway diseases remains limited. This article reviews our current understanding of the pathogenesis of URI, and of viral exacerbations of asthma and COPD, and considers host defense parameters that may regulate susceptibility to disease exacerbations. We will also consider current and potential therapeutic approaches for the treatment of URI and their lower airway complications.

Human rhinovirus induces robust IP-10 release by monocytic cells, which is independent of viral replication but linked to type I interferon receptor ligation and STAT1 activation

Human rhinovirus (HRV)-induced respiratory infections are associated with elevated levels of IFN-gamma-inducible protein 10 (IP-10), which is an enhancer of T lymphocyte chemotaxis and correlates with symptom severity and T lymphocyte number. Increased IP-10 expression is exhibited by airway epithelial cells following ex vivo HRV challenge and requires intracellular viral replication; however, there are conflicting reports regarding the necessity of type I IFN receptor ligation for IP-10 expression. Furthermore, the involvement of resident airway immune cells, predominantly bronchoalveolar macrophages, in contributing to HRV-stimulated IP-10 elaboration remains unclear. In this regard, our findings demonstrate that ex vivo exposure of human peripheral blood monocytes and bronchoalveolar macrophages (monocytic cells) to native or replication-defective HRV serotype 16 (HRV16) resulted in similarly robust levels of IP-10 release, which occurred in a time- and dose-dependent manner. Furthermore, HRV16 induced a significant increase in type I IFN (IFN-alpha) release and STAT1 phosphorylation in monocytes. Neutralization of the type I IFN receptor and inhibition of JAK or p38 kinase activity strongly attenuated HRV16-stimulated STAT1 phosphorylation and IP-10 release. Thus, this work supports a model, wherein HRV16-induced IP-10 release by monocytic cells is modulated via autocrine/paracrine action of type I IFNs and subsequent JAK/STAT pathway activity. Our findings demonstrating robust activation of monocytic cells in response to native and/or replication-defective HRV16 challenge represent the first evidence indicating a mechanistic disparity in the activation of macrophages when compared with epithelial cells and suggest that macrophages likely contribute to cytokine elaboration following HRV challenge in vivo.

Engagement of ICAM-1 by major group rhinoviruses activates the LFA-1/ICAM-3 cell adhesion pathway in mononuclear phagocytes

Cell-cell interactions are critical at key points of immune responses and are mediated by a complex array of adhesion receptors. One of the most important adhesion molecules on leukocytes is intercellular adhesion molecule 1 (ICAM-1, CD54). Here we demonstrate that engagement of ICAM-1 with human major group rhinoviruses (HRV) enhances adhesiveness and homotypic aggregation of human monocytes and monocyte-derived dendritic cells (DC). Cluster formation upon engagement of ICAM-1 with HRV14 represents an active process. It is temperature and energy dependent, requires divalent cations, an intact cytoskeleton and protein de novo synthesis. Homotypic interaction between monocytes induced by HRV14 can be inhibited with blocking mAbs against LFA-1 (CD11a/CD18) and ICAM-3 (CD50) as well as with a mAb against the first immunoglobulin (Ig)-domain of PECAM-1 (CD31). Induction of enhanced cytoadhesiveness by HRV14 was not accompanied with an upregulation of LFA-1, ICAM-3 or PECAM-1 expression. Binding studies with recombinant PECAM-1 proteins indicated, however, that monocyte clustering upon engagement of ICAM-1 with HRV was accompanied with increased homophilic PECAM-1 interactions. Taken together the results of our study demonstrate that signalling via ICAM-1 induces adhesiveness of mononuclear phagocytes, which critically involves PECAM-1 and is mediated via LFA-1/ICAM-3.

Human Rhinoviruses Inhibit the Accessory Function of Dendritic Cells by Inducing Sialoadhesin and B7-H1 Expression

Dendritic cells (DC) are professional APCs with an unmatched ability to interact with and activate T cells. There is accumulating evidence that DC not only efficiently stimulate T cell activation but also regulate T cell responses. However, little is known about cell surface structures on DC involved in the regulation of T cell responses. We demonstrate that human rhinoviruses (HRV) can efficiently inhibit the accessory function of DC through induction of inhibitory cell surface receptors. We observed that treatment of DC with HRV14 (R-DC), a member of the major group HRV family, diminished their T cell stimulatory capacity and induced a promiscuous and deep anergic state in cocultured T cells despite high levels of MHC molecules as well as costimulatory molecules, e.g., B7-1 (CD80) and B7-2 (CD86), and independent of inhibitory soluble factors such as IL-10. In contrast, expression of inhibitory B7-H1 molecules was up-regulated and R-DC de novo expressed sialoadhesin (Sn). Most importantly, blocking of B7-H1 and Sn on R-DC with specific mAbs against both receptors reverted the inhibitory phenotype. Thus, inhibitory signals delivered from R-DC to T cells via B7-H1 and Sn were critical for the induction of anergy. These observations suggest that an altered accessory molecule repertoire on DC upon interaction with HRV down-modulates adaptive immune responses during the viral infection.

Nitric oxide and the common cold

PURPOSE OF REVIEW

The common cold is a clinical syndrome triggered by a variety of viral pathogens, but rhinoviruses are the most frequent cause. Complications of such infections include sinusitis, otitis media, and exacerbations of asthma and chronic obstructive lung disease. There is growing interest in host innate defence responses that may regulate the severity of viral responses. We will review recent evidence that nitric oxide is an important contributor to the host response during colds.

RECENT FINDINGS

Infection of human airway epithelial cells with human rhinovirus has been shown to lead to the increased expression of inducible nitric oxide synthase both in vitro and in vivo. This increase in epithelial inducible nitric oxide synthase correlates with increased levels of nitric oxide in exhaled air. Importantly, nitric oxide can inhibit human rhinovirus-induced epithelial expression of several pro-inflammatory cytokines and can inhibit viral replication in epithelial cells in vitro. Moreover, nitric oxide can modulate several signal transduction pathways that are associated with cytokine generation. Nitric oxide can also nitrosylate viral proteases and can interact with the immune system. Consistent with these observations, pilot studies have indicated that the increased generation of nitric oxide during rhinovirus infections is associated with fewer symptoms and more rapid viral clearance.

SUMMARY

Further studies are warranted to evaluate the role of nitric oxide in colds and to determine whether the administration of nitric oxide donor compounds could be a viable therapeutic approach for viral exacerbations of airway diseases.

Human airway epithelial cells produce IP-10 (CXCL10) in vitro and in vivo upon rhinovirus infection

Human rhinovirus (HRV) infections trigger exacerbations of asthma and chronic obstructive pulmonary disease (COPD) and are associated with lymphocytic infiltration of the airways. We demonstrate that infection of primary cultures of human airway epithelial cells, or of the BEAS-2B human bronchial epithelial cell line, with human rhinovirus type 16 (HRV-16) induces expression of CXCL10 [IFN-gamma-inducible protein 10 (IP-10)], a ligand for the CXCR3 receptor found on activated type 1 T lymphocytes and natural killer cells. IP-10 mRNA reached maximal levels 24 h after HRV-16 infection then declined, whereas protein levels peaked 48 h after infection with no subsequent new synthesis. Cytosolic levels of AU-rich factor 1, a protein associated with mRNA destabilization, increased beginning 24 h after HRV-16 infection. Generation of IP-10 required virus capable of replication but was not dependent on prior induction of type 1 interferons. Transfection of synthetic double-stranded RNA into epithelial cells induced robust production of IP-10, whereas transfection of single-stranded RNA had no effect. Induction of IP-10 gene expression by HRV-16 depended upon activation of NF-kappaB, as well as other transcription factor recognition sequences further upstream in the IP-10 promoter. In vivo infection of human volunteers with HRV-16 strikingly increased IP-10 protein in nasal lavages during symptomatic colds. Levels of IP-10 correlated with symptom severity, viral titer, and numbers of lymphocytes in airway secretions. Thus IP-10 may play a role in the pathogenesis of HRV-induced colds and in HRV-induced exacerbations of COPD and asthma.

Human airway submucosal glands augment eosinophil chemotaxis during rhinovirus infection

BACKGROUND

Asthma exacerbations are frequently associated with rhinovirus (RV) infections. However, the contribution of airway submucosal gland (SMG) to exacerbations of asthma in RV respiratory infection has not been studied.

OBJECTIVE

This study was undertaken to examine whether RV-infected human respiratory SMG cells produce pro-inflammatory cytokines and chemokines for eosinophils, and augment eosinophil transmigration across human airway epithelium.

METHODS

We infected cultured human tracheal SMG cells with RV14, collected culture media at 1, 3, and 5 days after infection, and measured the chemotactic activity for eosinophils in the culture supernatant using a 48-well microchemotaxis chamber and a (51)Cr-labelled eosinophil transmigration assay.

RESULTS

Exposing a confluent human tracheal SMG cell monolayer to RV14 consistently led to infection. Human SMG cells with RV infection secreted soluble factors activating human eosinophil chemotaxis into the culture supernatant in a time-dependent manner, and the culture supernatant significantly augmented the transmigration of (51)Cr-labelled eosinophils through human airway epithelial cell layers from the basal to mucosal side. These effects were completely abolished by a mixture of a monoclonal antibody regulated on activation, normal T cells expressed and secreted (RANTES) and an antibody to granulocyte macrophage-colony stimulating factor (GM-CSF).

CONCLUSION

These results suggest that human respiratory SMG cells may augment eosinophil transmigration across the airway epithelium through the secretion of RANTES and GM-CSF after RV infection, and may contribute to exacerbations of asthma.

Nasal mucosa in natural colds: effects of allergic rhinitis and susceptibility to recurrent sinusitis

The mechanisms of virus-induced airway hyperresponsiveness in asthma and allergy and the failure of host defence in patients suffering from secondary airway infections are still largely unknown. The aim of this study was to examine whether the presence of allergic rhinitis or susceptibility to recurrent sinusitis affects the structural and cellular changes in nasal mucosa during natural colds and convalescence. We compared the mucosal changes in biopsy samples during acute natural colds (days 2-4 of illness) and convalescence (3 weeks later) in patients with allergic rhinitis (n = 9), patients with susceptibility to sinusitis (n = 19) and healthy controls (n = 20). We saw similarly increased numbers of mucosal T and B lymphocytes and mast cells and increased vascular density during the acute colds compared to convalescence in all the three groups. The allergic subjects had elevated levels of eosinophils in the acute phase (P = 0.03), and the allergic and sinusitis-prone subjects had elevated levels of epithelial T cells (P = 0.04) and low levels of mast cells (P = 0.005) in convalescence compared to the control group. The sinusitis-prone subjects lacked intraepithelial cytotoxic cells in convalescence. In the allergic subjects, the reticular basement membrane was thicker in the acute phase compared to the convalescence (P = 0.05). These results suggest that various cells of the airways, including inflammatory and structural cells, are involved during viral respiratory infections in subjects with allergic rhinitis. The small numbers of mast cells and cytotoxic lymphocytes in the sinusitis-prone subjects may be related to their susceptibility to bacterial complications.

Rhinovirus 16 3C protease induces interleukin-8 and granulocyte-macrophage colony-stimulating factor expression in human bronchial epithelial cells

Rhinovirus (RV), a member of the Picornaviridae family, accounts for many virus-induced asthma exacerbations. RV induces airway cell chemokine expression both in vivo and in vitro. Because of the known interactions of proteases with cellular functions, we hypothesized that RV 3C protease is sufficient for cytokine up-regulation. A cDNA encoding RV16 3C protease was constructed by PCR amplification and transfected into 16HBE14o- human bronchial epithelial cells. 3C protease induced expression of both IL-8 and GM-CSF, as well as transcription from both the IL-8 and GM-CSF promoters. 3C expression also induced activator protein 1 and NF-kappaB transcriptional activation. Finally, mutation of IL-8 promoter AP-1 and NF-kappaB promoter sequences significantly reduced 3C-induced responses. Together, these data suggest expression of RV16 3C protease is sufficient to induce chemokine expression in human bronchial epithelial cells, and does so in an AP-1- and NF-kappaB-dependent manner.

Serum and low-density lipoprotein enhance interleukin-8 secretion by airway epithelial cells

Viral respiratory infections rapidly increase vascular permeability, which leads to the transudation of serum proteins into airway secretions and tissues. To determine whether this process activates airway epithelial cells, bronchial epithelial cells were incubated with serum, and interleukin (IL)-8 secretion and gene expression were examined. As little as 0.1% serum significantly enhanced IL-8 secretion, and maximal secretion (65 +/- 4 ng/ml, 48 h) was observed with 10% serum. Low-density lipoprotein, but not albumin or immunoglobulin G, augmented bronchial epithelial IL-8 secretion, which was partially blocked by a monoclonal antibody specific for the low-density lipoprotein receptor. The IL-8-inducing activity of plasma was also augmented by clotting and platelet activation. Mechanistically, serum activated nuclear factor-kappaB and increased the stability and steady state levels of IL-8 mRNA. In summary, specific components of serum are potent activators of IL-8 mRNA and secretion, and the increased IL-8 production is likely to be a result of both increased transcription and mRNA stability. This effect may represent an innate mechanism for the recruitment of neutrophils to the airway in response to noxious stimuli, such as viral infections, that increase vascular permeability.

Rhinovirus and asthma

Rhinoviruses (RVs) cause the majority of common colds, which often provoke wheezing in patients with asthma. The precise mechanisms responsible for the RV infection-induced exacerbations of bronchial asthma are still uncertain. However, several reports reveal airway hyperresponsiveness, increases in chemical mediators in airway secretions such as kinin and histamine, and airway inflammation in patients with bronchial asthma after RV infection. RV infection induces an accumulation of inflammatory cells in airway mucosa and submucosa including neutrophils, lymphocytes and eosinophils. RV affects the barrier function of airway epithelial cells, and activates the airway epithelial cells and other cells in the lung to produce pro-inflammatory cytokines, including various kinds of interleukins, GM-CSF and RANTES, and histamine. RV also stimulates the expression of intercellular adhesion molecule-1 (ICAM-1) and low-density lipoprotein receptors in the airway epithelium, receptors for major and minor RVs. On the other hand, RV infection is inhibited by treatment with soluble ICAM-1, and by reduction of ICAM-1 expression in the airway epithelial cells after treatment with erythromycin. Both soluble ICAM-1 and erythromycin were reported to reduce the frequency of common colds. Here, we review the pathogenesis and management of RV infection-induced exacerbation of bronchial asthma.

Lymphocyte and mast cell counts are increased in the nasal mucosa in symptomatic natural colds

Knowledge of the virus-induced immune response is important in understanding the pathophysiology of respiratory virus infections. Data on the cellular immune response is still limited and based mainly on experimental studies. Natural colds may differ in their pathophysiology from experimentally induced ones. To evaluate the inflammatory cell responses in the upper respiratory tract during natural colds we counted the number of lymphocytes, mast cells and macrophages in the nasal mucosa. Nasal biopsies were taken from 22 adult volunteers during the acute (2-4 days of symptoms) and convalescent phases (day 21) of the cold, and the numbers of cells were counted with immunohistochemical methods. Viral aetiology was identified in 14 (64%) subjects by using viral isolation, antigen detection and rhino-polymerase chain reaction assays. The number of T lymphocytes was increased in the nasal epithelium and that of T and B lymphocytes and mast cells in the subepithelial layer in the acute phase compared to the convalescent phase. Intraepithelial T lymphocyte counts were significantly higher in the subjects who had a proven viral infection or a finding of pathogenic bacteria in the nasopharynx compared to the subjects without such findings (P = 0.005 and P = 0.04, respectively). Contrary to the earlier experimental studies, we found that viruses cause accumulation of T and B lymphocytes and mast cells during the first days of a symptomatic naturally acquired respiratory infection.

Relationships among specific viral pathogens, virus-induced interleukin-8, and respiratory symptoms in infancy

Both virus-mediated damage to airway tissues and induction of pro-inflammatory cytokines such as interleukin-8 (IL-8) could contribute to symptom severity during viral respiratory infections in children. To test the hypothesis that IL-8 contributes to the pathogenesis of respiratory symptoms during naturally acquired respiratory viral infections in children, nasal wash samples collected from infants with acute viral infections (n = 198) or from healthy uninfected infants (n = 31) were analysed for IL-8. Nasal wash IL-8 was positively related to age in uninfected children (rs = 0.36, p < 0.05). Respiratory syncytial virus (RSV) infection caused more severe respiratory symptoms compared to infections with influenza A, parainfluenza viruses, or rhinoviruses. In addition, RSV, parainfluenza and rhinovirus infections increased levels of IL-8 in nasal lavage fluid, and there were some differences in the ability of the viruses to induce IL-8 production (RSV>influenza, p < 0.05). Finally, there were significant correlations between nasal wash IL-8 levels and symptom scores during infections with rhinovirus (rs = 0.56, p < 0.001) or influenza A (rs = 0.45, p < 0.05), but not with parainfluenza virus or RSV. These findings provide evidence of a close relationship between the generation of IL-8 and symptoms during acute community-acquired infections with rhinovirus or influenza A. In contrast, for RSV and parainfluenza infections, factors in addition to IL-8 production appear to contribute to the generation of clinical symptoms.

Effects of rhinovirus infection on histamine and cytokine production by cell lines from human mast cells and basophils

To understand the biochemical events that occur in the airways after rhinovirus (RV) infection, we developed for the first time a model in which the cell lines from human mast cells (HMC-1) and basophils (KU812) can be infected with RV14, a major group RV. Viral infection was confirmed by demonstrating that viral titers in culture supernatants, and RV RNA increased with time. RV14 infection alone and a combination of PMA plus calcium ionophore A23187, did not increase histamine production by these cells, although IgE plus anti-IgE increased the histamine production. However, histamine content in the supernatants increased in response to PMA plus A23187, or IgE plus anti-IgE after RV14 infection. PMA plus A23187 or IgE plus anti-IgE induced the production of IL-8 and GM-CSF in supernatants of HMC-1 cells and IL-4 and IL-6 in supernatants of KU812 cells. RV14 infection further increased the production of the cytokines, whereas RV14 infection alone did not alter the production of the cytokines by these cells. An Ab to ICAM-1 inhibited RV14 infection of the cells and decreased the production of cytokines and histamine after RV14 infection. RV14 infection enhanced the increases in intracellular calcium concentration and activation of NF-kappaB by PMA plus A23187 in the cells. These findings suggest that RV14 infection may prime the cytokine and histamine production from mast cells and basophils and may cause airway inflammation in asthma.

Pathogenesis and management of virus infection-induced exacerbation of senile bronchial asthma and chronic pulmonary emphysema

The number of senile patients with therapy resistant bronchial asthma, chronic pulmonary emphysema increases due to the habit of smoking and increased number of older people, and these inflammatory pulmonary diseases are the leading causes of death worldwide. Rhinoviruses cause the majority of common colds, and provoke exacerbations of bronchial asthma and chronic pulmonary emphysema. Here, I review the pathogenesis and management of rhinovirus infection-induced exacerbation of senile bronchial asthma and chronic pulmonary emphysema.

Rhinovirus respiratory infections and asthma

Viral infections, particularly respiratory illnesses caused by rhinovirus, are the most common cause of asthma exacerbations in children and contribute in large part to asthma morbidity in adults. Epidemiologic studies and increasingly sophisticated viral detection methodologies have helped to define the role of rhinovirus as a potential causative agent in asthma exacerbations. Rhinovirus-induced lung disease is multifaceted and can be characterized in terms of a variety of physiologic, immunologic, and viral processes. The precise direct and indirect mechanisms of viral contribution to exacerbations must still be elucidated. Understanding them will have an impact on the design of future treatment modalities.

Effect of experimental influenza A infection on systemic immune and inflammatory parameters in allergic and nonallergic adult subjects

BACKGROUND

The economic impact and medical complication rate of viral upper respiratory infections are well documented, but many of the physiologic, inflammatory, and immune responses to respiratory viruses have only recently been investigated. A previous study demonstrated differential systemic immune and inflammatory responses in allergic rhinitis (AR) and nonallergic rhinitis (NAR) subjects during experimental infection with rhinovirus-39.

OBJECTIVE

The purpose of this study was to compare selected systemic immune and inflammatory responses to experimental influenza A virus (FLU) challenge in seronegative AR and NAR subjects.

METHODS

Peripheral blood was obtained at baseline (study day 0) and 3, 6, 18, and 31 days after intranasal FLU challenge and assayed for leukocyte histamine release, serum immunoglobulins, and plasma histamine.

RESULTS

All subjects were infected, as manifested by viral shedding in nasal secretions and/or seroconversion. FLU infection induced decreases in spontaneous leukocyte histamine release and increases in anti-immunoglobulin E-induced leukocyte histamine release, which were evident at least 1 month after infection, but caused no significant changes in serum immunoglobulins or plasma histamine. There were no differences between AR and NAR subjects for any of the study parameters.

CONCLUSIONS

The results show that intranasal challenge with FLU induces changes in leukocyte histamine release, but not other systemic immune and inflammatory responses.

Prolonged nasal eosinophilia in allergic patients after common cold

BACKGROUND

Viral respiratory tract infections may cause both harmless common colds and severe asthma exacerbations; the differences in disease expression probably depend on the allergic status of the patient. To determine whether altered immunologic mechanisms underlie these differences, we investigated nasal inflammation during naturally acquired common cold.

METHODS

In a group of 16 patients (eight allergic), nasal brush samples were taken, and nasal symptoms were recorded during common cold, 2 weeks later (convalescence), and at baseline (>4 weeks without nasal symptoms). Nasal brush cells were stained immunohistochemically for Langerhans cells, T cells, monocytes, neutrophils, B cells, macrophages, natural killer (NK) cells, mast cells, eosinophils, eotaxin, and RANTES.

RESULTS

Four rhinovirus, four coronavirus, three RSV, one Mycoplasma pneumoniae, and one influenza A/enterovirus double infection were confirmed. Increased numbers of T cells, monocytes, macrophages, NK cells, eosinophils, and RANTES- and eotaxin-positive cells, but not neutrophils, were observed during common cold in allergic and nonallergic patients, and increased numbers of mast cells in allergic patients. Compared to nonallergic patients, in allergic patients eosinophil influx persisted into convalescence.

CONCLUSION

Prolonged nasal eosinophil influx was observed in allergic patients after common cold. What immunologic factors can induce prolonged eosinophil influx and whether this may increase the risk of subsequent allergen-induced hypersensitivity reactions must be studied further.

Relationship of upper and lower airway cytokines to outcome of experimental rhinovirus infection

To test the hypothesis that rhinovirus (RV)-induced immune responses influence the outcome of RV infections, we inoculated 22 subjects with allergic rhinitis or asthma with RV16. Nasal secretions and induced sputum were repeatedly sampled over the next 14 d. RV16 infection increased nasal granulocyte colony-stimulating factor (G-CSF) and interleukin (IL)-8, which was accompanied by neutrophilia in blood and nasal secretions. Nasal G-CSF correlated closely with increased blood neutrophils (r(s) = 0.69, p < 0.005), whereas nasal neutrophils correlated with both G-CSF (r(s) = 0.87, p < 0.001) and IL-8 (r(s) = 0.75, p < 0.001). Although similar relationships were present in sputum, changes in sputum neutrophils and G-CSF with RV16 infection were relatively modest. In addition, virus-induced changes in the sputum interferon-gamma-to-IL-5 messenger RNA ratio were inversely related to both peak cold symptoms (r(s) = -0.60, p < 0.005) and the time to viral clearance (undetectable picornavirus RNA). These results indicate that airway IL-8 and G-CSF are closely associated with virus-induced neutrophilic inflammation during an experimental RV infection in atopic volunteers. In addition, the balance of airway T-helper cell type 1 (Th1)- and Th2-like cytokines induced by RV infection may help determine the clinical outcome of common cold infections, raising the possibility that the individual subject's immune response, rather than atopic status per se, is important in this regard.

Role of NF-kappa B in cytokine production induced from human airway epithelial cells by rhinovirus infection

Infection of human epithelial cells with human rhinovirus (HRV)-16 induces rapid production of several proinflammatory cytokines, including IL-8, IL-6, and GM-CSF. We evaluated the role of NF-kappaB in HRV-16-induced IL-8 and IL-6 production by EMSA using oligonucleotides corresponding to the binding sites for NF-kappaB in the IL-6 and IL-8 gene promoters. Consistent with the rapid induction of mRNA for IL-8 and IL-6, maximal NF-kappaB binding to both oligonucleotides was detected at 30 min after infection. NF-kappaB complexes contained p65 and p50, but not c-Rel. The IL-8 oligonucleotide bound recombinant p50 with only about one-tenth the efficiency of the IL-6 oligonucleotide, even though epithelial cells produced more IL-8 protein than IL-6. Neither the potent glucocorticoid, budesonide (10-7 M), nor a NO donor inhibited NF-kappaB binding to either cytokine promoter or induction of mRNA for either IL-8 or IL-6. Sulfasalazine and calpain inhibitor I, inhibitors of NF-kappaB activation, blocked HRV-16-induced formation of NF-kappaB complexes with oligonucleotides from both cytokines, but did not inhibit mRNA induction for either cytokine. By contrast, sulfasalazine clearly inhibited HRV-16 induction of mRNA for GM-CSF in the same cells. Thus, HRV-16 induces epithelial expression of IL-8 and IL-6 by an NF-kappaB-independent pathway, whereas induction of GM-CSF is at least partially dependent upon NF-kappaB activation.

The common cold at the turn of the millennium

Upper respiratory tract infections are one of the most common infectious diseases in man and are characterized by transient, relatively mild symptoms. Human rhinoviruses are known to be the major causative agent in adult common colds and their relative importance has further increased with the use of the sensitive RT-PCR technique. Characteristic for a common cold is the selective neutrophil recruitment and time-limited increase in mediator, cytokine, and chemokine concentrations that orchestrate chemotaxis, transmigration, and activation of inflammatory and immunocompetent cells. Common cold symptoms are found to correlate to rhinovirus-induced IL-8 elaboration and neutrophil activation. Treatment of rhinoviral upper respiratory tract infections consists of an inhibition of viral infection by antiviral agents and/or a reduction of symptoms by damping the host inflammatory response.

The role of viral infections in the natural history of asthma

Viral infections have been related to the inception of recurrent wheezing illnesses and asthma in infants and are probably the most frequent cause of exacerbations of established disease in older children and adults. The well-recognized clinical effects of viral infections are mainly caused by virus-induced immune responses. Clinical studies of natural and experimentally induced viral infections have led to the identification of mechanisms of inflammation that could be involved in producing airway obstruction and lower airway symptoms. In addition, host factors that are associated with more vigorous viral replication or severe clinical illness are beginning to be identified. Advances in molecular virology and our understanding of immune responses to viral infections may lead to the development of new strategies for the prevention and treatment of virus-induced respiratory disorders.

The effect of an experimental rhinovirus 16 infection on bronchial lavage neutrophils

BACKGROUND

Viral respiratory tract infections are the most frequent cause of asthma exacerbations. Of the respiratory viruses associated with these exacerbations, rhinovirus (RV) is the most common. It is proposed that these RV infections may enhance airway inflammation and thus provoke asthma.

OBJECTIVE

It is our hypothesis that RV infections generate nasal proinflammatory mediators that are associated with an initial increase in circulating leukocytes and may contribute to later development of neutrophilic airway inflammation.

METHODS

To evaluate this hypothesis, subjects with a history of allergic asthma were experimentally inoculated with strain 16 RV (RV16). The effect of this experimental infection was evaluated on circulating leukocytes, nasal-derived mediators, and markers of bronchial inflammation that were obtained by bronchoscopy and lavage.

RESULTS

RV16 inoculation was associated with an initial increase in circulating neutrophils. Paralleling these acute changes in circulating neutrophils was an increase in nasal concentrations of IL-8 and granulocyte-colony-stimulating factor (G-CSF). The RV16-associated changes in circulating and nasal G-CSF correlated with increases in peripheral blood neutrophils (r(s) = 0.874, P <. 001 and r(s) = 0.898, P <.001, respectively). Bronchial lavage samples showed no increase in neutrophils 48 hours after RV16 inoculation; however, 96 hours after RV inoculation there was a significant increase in bronchial neutrophils compared with preinoculation values.

CONCLUSIONS

These results suggest that the production of nasal mediators associated with the RV infection, particularly G-CSF, may be important to the eventual development of neutrophilic bronchial inflammation and thus contribute to asthma exacerbations.

Rhinovirus-induced PBMC responses and outcome of experimental infection in allergic subjects

BACKGROUND

The immune response to rhinovirus (RV) infections is considered to contribute to upper respiratory symptoms and may also be an important contributor to lower airway dysfunction in patients with asthma.

OBJECTIVE

This study was conducted to determine the relationship of RV-specific responses in PBMCs to the outcome of experimentally induced infection with RV16.

METHODS

Twenty-two subjects with either allergic rhinitis or asthma were inoculated with RV16: virus-induced proliferation and cytokine production were determined on PBMCs obtained before and then again 7 and 28 days after inoculation.

RESULTS

Several subjects had proliferative responses to RV16 before inoculation, and precold RV-specific proliferative responses were inversely correlated (r(s) = -0.62, P <. 005) with RV shedding after inoculation. In addition, there was a negative correlation (r(s) = -0.58, P = 0.01) between precold RV-induced IFN-gamma secretion ex vivo and peak RV shedding during the cold.

CONCLUSIONS

Certain RV-specific lymphocyte responses before the cold (vigorous proliferation or IFN-gamma secretion) were associated with reduced viral shedding after inoculation. These findings suggest that variations in mononuclear cell responses to RV could contribute to the individual variability in viral shedding during experimentally induced, and perhaps naturally acquired, RV infections in subjects with respiratory allergy or asthma.

Viral and bacterial infections in the development and progression of asthma

Viral respiratory infections produce wheezing illnesses in patients of all ages. In infancy, infections with respiratory syncytial virus and parainfluenza virus are the major cause of bronchiolitis and croup, whereas infections with common cold viruses such as rhinoviruses are the principal triggers for wheezing in older children and adults with asthma. In addition to causing increased wheezing in asthma, there is mounting evidence that infections early in childhood can affect the development of the immune system and thereby modify the risk for the subsequent development of allergies and asthma. Both of these effects appear to be mediated by virus-induced immune responses. Early during the course of viral infection, resident cells in the airway are activated in an antigen-independent fashion, triggering antiviral responses but also activating and recruiting cells to the airway that could contribute to airway obstruction and respiratory symptoms. Virus-specific T- and B-cell responses may also have dual effects in the presence of preexisting airway inflammation. Finally, there is evidence of synergistic interactions between allergen- and virus-induced airway inflammation. It is likely that greater definition of mechanisms of virus-induced inflammation will provide therapeutic targets for the treatment and possibly the prevention of allergies and asthma.

Human major group rhinoviruses downmodulate the accessory function of monocytes by inducing IL-10

Human rhinoviruses (HRVs) are the predominant cause of the common cold. Although this disease is per se rather harmless, HRV infection is considered to set the stage for more dangerous pathogens in vivo. Here we demonstrate that HRV-14, a member of the major group HRV family, can efficiently inhibit antigen-induced T-cell proliferation and T-cell responses to allogeneic monocytes. HRV-14 triggered a significant downregulation of MHC class II molecules on monocytes. Moreover, supernatants from monocytes cultured in the presence of HRV-14 strongly reduced the allogeneic T-cell stimulatory property of untreated monocytes and monocyte-derived dendritic cells (md-DCs), whereas Epstein Barr virus-transformed B-lymphoblastoid cells were not sensitive. Analysis of the supernatant revealed that HRV-14 induced the production of significant amounts of the immunosuppressive cytokine IL-10. The important T-cell stimulatory cytokine IL-12 or the proinflammatory cytokines IL-1beta or TNF-alpha were not detected or were only minimally detected. Finally, monocytes pretreated with HRV-14 were greatly inhibited in their production of IL-12 upon stimulation with IFN-gamma/LPS. These observations suggest that altered cytokine production in mononuclear phagocytes upon interaction with HRV downmodulates appropriate immune responses during the viral infection.

Infection of human respiratory submucosal glands with rhinovirus: effects on cytokine and ICAM-1 production

To further understand the early biochemical events that occur in infected surface epithelium, we developed for the first time a model in which a respiratory submucosal gland cell population can be infected with rhinovirus (RV). Viral infection was confirmed by demonstrating with PCR that viral titers in supernatants and lysates from infected cells increased with time. Infection by RV14 upregulated the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, the major RV receptor, on submucosal gland cells, and it increased production of interleukin (IL)-1alpha, IL-1beta, IL-6, IL-8, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor in supernatants. Antibodies to ICAM-1 inhibited RV infection of submucosal gland cells and decreased the production of cytokines after RV infection. Both IL-1alpha and IL-1beta upregulated ICAM-1 mRNA expression and increased susceptibility to RV infection, whereas other cytokines failed to alter ICAM-1 mRNA expression. Furthermore, neutralizing antibodies to IL-1alpha and IL-1beta significantly decreased the viral titers in supernatants and ICAM-1 mRNA expression after RV infection, but a neutralizing antibody to tumor necrosis factor-alpha was without effect. These findings suggest that respiratory submucosal gland cells play an important role in the initial stages of inflammation and provide useful insights into the pathogenesis of RV infection.

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 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.

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.

Low Grade Rhinovirus Infection Induces a Prolonged Release of IL-8 in Pulmonary Epithelium

Rhinoviruses are important respiratory pathogens implicated in asthma exacerbations. The mechanisms by which rhinoviruses trigger inflammatory responses in the lower airway are poorly understood, in particular their ability to infect the lower airway. Bronchial inflammatory cell (lymphocyte and eosinophil) recruitment has been demonstrated. IL-8 is a potent proinflammatory chemokine that is chemotactic for neutrophils, lymphocytes, eosinophils, and monocytes and may be important in the pathogenesis of virus-induced asthma. Increased levels of IL-8 have been found in nasal samples in natural and experimental rhinovirus infections. In these studies we therefore examine the ability of rhinovirus to infect a transformed lower airway epithelial cell line (A549) and to induce IL-8 protein release and mRNA induction. We observed that rhinovirus type 9 is able to undergo full viral replication in A549 cells, and peak viral titers were found 24 h after inoculation. Rhinovirus infection induced a dose- and time-dependent IL-8 release up to 5 days after infection and an increase in IL-8 mRNA expression that was maximal between 3 and 24 h after infection. UV inactivation of the virus completely inhibited replication, but only reduced IL-8 protein production and mRNA induction by half, while prevention of virus-receptor binding completely inhibited virus-induced IL-8 release, suggesting that part of the observed effects was due to viral replication and part was due to virus-receptor binding. These studies demonstrate that rhinoviruses are capable of infecting a pulmonary epithelial cell line and inducing IL-8 release. These findings may be important in understanding the pathogenesis of rhinovirus-induced asthma exacerbations.

Nitric oxide inhibits rhinovirus-induced cytokine production and viral replication in a human respiratory epithelial cell line

To better understand the early biochemical events that occur in human rhinovirus (HRV) infections, we examined the kinetics and mechanisms of interleukin-8 (IL-8) and IL-6 production from infected epithelial cells. Several HRV strains caused IL-8 and IL-6 production, but HRV-16 induced maximal IL-8 and IL-6 mRNA expression and protein production more rapidly than did HRV-14, despite similar rates of replication of the two viral strains. Viral induction of cytokine mRNA does not require new protein synthesis, since it was unaffected by cycloheximide treatment. The potent glucocorticoid budesonide did not affect viral replication or cytokine mRNA induction but modestly inhibited cytokine protein production. Interestingly, the nitric oxide donor 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (NONOate) inhibited both rhinovirus replication and cytokine production in a dose-dependent fashion without reducing levels of cytokine mRNA. The NONOate effects were due to release of nitric oxide, because NONOate that had been depleted of its nitric oxide content had no effect. Thus, nitric oxide may play an important anti-inflammatory and antiviral role in colds and nitric oxide donors may represent a novel therapeutic approach.

Rhinovirus infection of primary cultures of human tracheal epithelium: role of ICAM-1 and IL-1beta

Exacerbations of asthma are often associated with respiratory infection caused by rhinoviruses. To study the effects of rhinovirus infection on respiratory epithelium, a primary target for respiratory viruses, human rhinovirus (HRV)-2 and HRV-14 were infected to primary cultures of human tracheal epithelial cells. Viral infection was confirmed by showing that viral titers of supernatants and lysates from infected cells increased with time and by polymerase chain reaction. HRV-2 and HRV-14 infections upregulated the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, the major rhinovirus receptor, on epithelial cells, and they increased the production of interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha in supernatants. Antibodies to ICAM-1 inhibited HRV-14 infection of epithelial cells and decreased the production of cytokines after HRV-14 infection, but they did not alter HRV-2 infection-induced production ofcytokines. IL-1beta upregulated ICAM-1 mRNA expression and increased susceptibility to HRV-14 infection, whereas other cytokines failed to alter ICAM-1 mRNA expression. Furthermore, a neutralizing antibody to IL-1beta significantly decreased viral titers of supernatants and ICAM-1 mRNA expression after HRV-14 infection, but a neutralizing antibody to TNF-alpha was without effect. Immunohistochemical studies revealed that both HRV-14 infection and IL-1beta increased ICAM-1 expression on cultured epithelial cells. These findings imply that HRV-14 infection upregulated ICAM-1 expression on epithelial cells through increased production of IL-1beta, thereby increasing susceptibility to infection. These events may be important for amplification of airway inflammation after viral infection in asthma.

Epidemiology, pathogenesis, and treatment of the common cold

OBJECTIVE

Reading this article will reinforce the reader's knowledge of the pathogenesis of the common cold. The rationale for current and potential therapies for the common cold are reviewed in the context of current concepts of the pathogenesis of these illnesses.

DATA SOURCES AND STUDY SELECTION

A MEDLINE literature search was done using the search terms common cold, rhinovirus, and viral respiratory infection. The search was restricted to the English language. Articles were selected for review if the title and/or abstract suggested the content was relevant to the subject of this review. The bibliographies of selected articles were used as a source of additional literature.

RESULTS

Recent studies suggest that the host response to the virus is an important contributor to the pathogenesis of the common cold. Inflammatory mediators, especially the pro-inflammatory cytokines, appear to be an important component of this response and present an attractive target for new interventions for common cold therapies. Currently available treatments for the common cold have limited efficacy against specific symptoms. These therapies should be selected to treat the specific symptoms that are perceived to be the most bothersome by the patient.

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

Background Asthma exacerbations are closely associated with respiratory virus infections. However, the pathophysiological consequences of such infections in asthma are largely unclear.

Objective To examine the effect of rhinovirus 16 (RV16) infection on airway hypersensitivity to histamine. and on interleukin‐8 (IL‐8) in nasal lavage.

Objective Twenty‐seven non‐smoking atopic, mildly asthmatic subjects participated in a placebo‐controlled, parallel study. A dose of 0.5–2.9 ± 10⁴ TCID50 RV16 or placebo was nasally administered. Cold symptoms were recorded by questionnaire throughout the study. Histamine challenges were performed at entry, and on days 4 and 11 after inoculation. Nasal lavages were obtained at entry, and on days 2 and 9. The response to histamine was measured by PC₂₀ (changes expressed as doubling doses: DD). IL‐8 levels were obtained by ELISA, and were expressed in ng/ml.

Results RV infection was confirmed by culture of nasal lavage and/or by antibody titre rise in each of the RV16‐treated subjects. Among the 19 RV16‐treated subjects, eight developed severe cold symptoms. Baseline FEV₁ did not change significantly during the study in either treatment group (P= 0.99). However, in the RV16‐treated subjects there was a decrease in PC₂₀ at day 4, which was most pronounced in those with a severe cold (mean change ± SEM: –1.14 ± 0.28 DD, P= 0.01). In addition. IL‐8 levels increased in tbe RV16 group at days 2 and 9 (P < 0.001). The increase in nasal IL‐8 at day 2 correlated significantly with the change in PC₂₀ at day 4 (r=–0.48, P= 0.04).

Conclusion We conclude that the severity of cold, as induced by experimental RV16 infection, is a determinant of the increase in airway hypersensitivity to histamine in patients with asthma. Our results suggest that this may be mediated by an infiammatory mechanism, involving the release of chemokines such as IL‐8.

Problems and prospects of developing effective therapy for common cold viruses

No effective treatment for common colds has yet been developed. Combination antiviral and anti-inflammatory therapies are the best hope for intervention after the onset of symptoms. Prophylaxis, especially in the form of vaccination, would have a major impact in disease prevention. These approaches offer new avenues for treating populations at risk and are of particular significance to those with asthma or chronic bronchitis.