Rhinovirus stimulation of interleukin-8 in vivo and in vitro: role of NF-kappaB

The effect of probiotic Bifidobacterium lactis Bl-04 on innate antiviral responses invitro

Consumption of certain probiotic strains may be beneficial for reducing the risk of acute upper respiratory tract infections (URTIs), however, underlying immunological mechanisms are elusive. Bifidobacterium lactis Bl-04™ has been reported in humans to significantly reduce the risk of URTIs, affect the innate immunity in the nasal mucosa, and reduce nasal lavage virus titer after a rhinovirus (RV) challenge. To study the immunological mechanisms, we investigated the effect of Bl-04 on cytokine production and transcriptomes of human monocyte-derived macrophages (Mfs) and dendritic cells (DCs), and further on RV replication and cytokine production in MRC-5 fibroblasts. The results showed that Bl-04 modulates antiviral immune responses and potentiates cytokine production during viral challenge mimic in immune cells. However, effect of Bl-04 on RV replication and cytokine production in fibroblasts was negligible. Overall, the findings suggest that Bl-04 mildly stimulates antiviral immunity in Mfs and DCs, and potentially influences viral replication in fibroblasts that however warrants further investigations.

An Overview on the Primary Factors That Contribute to Non-Allergic Asthma in Children

The prevalence of non-allergic asthma in childhood is low, peaking in late adulthood. It is triggered by factors other than allergens, like cold and dry air, respiratory infections, hormonal changes, smoke and air pollution. In the literature, there are few studies that describe non-allergic asthma in pediatric age. Even though it is a less common disorder in kids, it is crucial to identify the causes in order to keep asthma under control, particularly in patients not responding to conventional treatments. In this review, we discuss non-IgE-mediated forms of asthma, collecting the latest research on etiopathogenesis and treatment.

Relaxin Affects Airway Remodeling Genes Expression through Various Signal Pathways Connected with Transcription Factors

Fibrosis is one of the parameters of lung tissue remodeling in asthma. Relaxin has emerged as a natural suppressor of fibrosis, showing efficacy in the prevention of a multiple models of fibrosis. Therefore, the aim of this study was to analyze the aptitudes of relaxin, in the context of its immunomodulatory properties, in the development of airway remodeling. WI-38 and HFL1 fibroblasts, as well as epithelial cells (NHBE), were incubated with relaxin. Additionally, remodeling conditions were induced with two serotypes of rhinovirus (HRV). The expression of the genes contributing to airway remodeling were determined. Moreover, NF-κB, c-Myc, and STAT3 were knocked down to analyze the pathways involved in airway remodeling. Relaxin decreased the mRNA expression of collagen I and TGF-β and increased the expression of MMP-9 (p < 0.05). Relaxin also decreased HRV-induced expression of collagen I and α-SMA (p < 0.05). Moreover, all the analyzed transcription factors—NF-κB, c-Myc, and STAT3—have shown its influence on the pathways connected with relaxin action. Though relaxin requires further study, our results suggest that this natural compound offers great potential for inhibition of the development, or even reversing, of factors related to airway remodeling. The presented contribution of the investigated transcription factors in this process additionally increases its potential possibilities through a variety of its activity pathways.

ORMDL3 regulates poly I:C induced inflammatory responses in airway epithelial cells

BACKGROUND

Oroscomucoid 3 (ORMDL3) has been linked to susceptibility of childhood asthma and respiratory viral infection. Polyinosinic-polycytidylic acid (poly I:C) is a synthetic analog of viral double-stranded RNA, a toll-like receptor 3 (TLR3) ligand and mimic of viral infection.

METHODS

To investigate the functional role of ORMDL3 in the poly I:C-induced inflammatory response in airway epithelial cells, ORMDL3 knockdown and over-expression models were established in human A549 epithelial cells and primary normal human bronchial epithelial (NHBE) cells. The cells were stimulated with poly I:C or the Th17 cytokine IL-17A. IL-6 and IL-8 levels in supernatants,  mRNA levels of genes in the TLR3 pathway and inflammatory response from cell pellets were measured. ORMDL3 knockdown models in A549 and BEAS-2B epithelial cells were then infected with live human rhinovirus (HRV16) followed by IL-6 and IL-8 measurement.

RESULTS

ORMDL3 knockdown and over-expression had little influence on the transcript levels of TLR3 in airway epithelial cells. Time course studies showed that ORMDL3-deficient A549 and NHBE cells had an attenuated IL-6 and IL-8 response to poly I:C stimulation. A549 and NHBE cells over-expressing ORMDL3 released relatively more IL-6 and IL-8 following poly I:C stimulation. IL-17A exhibited a similar inflammatory response in ORMDL3 knockdown and over-expressing cells, but co-stimulation of poly I:C and IL-17A did not significantly enhance the IL-6 and IL-8 response. Transcript abundance of IFNB following poly I:C stimulation was not significantly altered by ORMDL3 knockdown or over-expression. Dampening of the IL-6 response by ORMDL3 knockdown was confirmed in HRV16 infected BEAS-2B and A549 cells.

CONCLUSIONS

ORMDL3 regulates the viral inflammatory response in airway epithelial cells via mechanisms independent of the TLR3 pathway.

Strategies for Targeting SARS CoV-2: Small Molecule Inhibitors-The Current Status

Severe Acute Respiratory Syndrome-Corona Virus-2 (SARS-CoV-2) induced Coronavirus Disease - 19 (COVID-19) cases have been increasing at an alarming rate (7.4 million positive cases as on June 11 2020), causing high mortality (4,17,956 deaths as on June 11 2020) and economic loss (a 3.2% shrink in global economy in 2020) across 212 countries globally. The clinical manifestations of this disease are pneumonia, lung injury, inflammation, and severe acute respiratory syndrome (SARS). Currently, there is no vaccine or effective pharmacological agents available for the prevention/treatment of SARS-CoV2 infections. Moreover, development of a suitable vaccine is a challenging task due to antibody-dependent enhancement (ADE) and Th-2 immunopathology, which aggravates infection with SARS-CoV-2. Furthermore, the emerging SARS-CoV-2 strain exhibits several distinct genomic and structural patterns compared to other coronavirus strains, making the development of a suitable vaccine even more difficult. Therefore, the identification of novel small molecule inhibitors (NSMIs) that can interfere with viral entry or viral propagation is of special interest and is vital in managing already infected cases. SARS-CoV-2 infection is mediated by the binding of viral Spike proteins (S-protein) to human cells through a 2-step process, which involves Angiotensin Converting Enzyme-2 (ACE2) and Transmembrane Serine Protease (TMPRSS)-2. Therefore, the development of novel inhibitors of ACE2/TMPRSS2 is likely to be beneficial in combating SARS-CoV-2 infections. However, the usage of ACE-2 inhibitors to block the SARS-CoV-2 viral entry requires additional studies as there are conflicting findings and severe health complications reported for these inhibitors in patients. Hence, the current interest is shifted toward the development of NSMIs, which includes natural antiviral phytochemicals and Nrf-2 activators to manage a SARS-CoV-2 infection. It is imperative to investigate the efficacy of existing antiviral phytochemicals and Nrf-2 activators to mitigate the SARS-CoV-2-mediated oxidative stress. Therefore, in this review, we have reviewed structural features of SARS-CoV-2 with special emphasis on key molecular targets and their known modulators that can be considered for the development of NSMIs.

Manipulation of Non-canonical NF-κB Signaling by Non-oncogenic Viruses

Nuclear factor (NF)-κB is a major regulator of antiviral response. Viral pathogens exploit NF-κB activation pathways to avoid cellular mechanisms that eliminate the infection. Canonical (classical) NF-κB signaling, which regulates innate immune response, cell survival and inflammation, is often manipulated by viral pathogens that can counteract antiviral response. Oncogenic viruses can modulate not only canonical, but also non-canonical (alternative) NF-κB activation pathways. The non-canonical NF-κB signaling is responsible for adaptive immunity and plays a role in lymphoid organogenesis, B cell development, as well as bone metabolism. Thus, non-canonical NF-κB activation has been linked to lymphoid malignancies. However, some data strongly suggest that the non-canonical NF-κB activation pathway may also function in innate immunity and is modulated by certain non-oncogenic viruses. Collectively, these findings show the importance of studying the impact of different groups of viral pathogens on alternative NF-κB activation. This mini-review focuses on the influence of non-oncogenic viruses on the components of non-canonical NF-κB signaling.

Adrenergic Signaling at the Interface of Allergic Asthma and Viral Infections

Upper respiratory viral infections are a major etiologic instigator of allergic asthma, and they drive severe exacerbations of allergic inflammation in the lower airways of asthma sufferers. Rhinovirus (RV), in particular, is the main viral instigator of these pathologies. Asthma exacerbations due to RV infections are the most frequent reasons for hospitalization and account for the majority of morbidity and mortality in asthma patients. In both critical care and disease control, long- and short-acting β2-agonists are the first line of therapeutic intervention, which are used to restore airway function by promoting smooth muscle cell relaxation in bronchioles. While prophylactic use of β2-agonists reduces the frequency and pathology of exacerbations, their role in modulating the inflammatory response is only now being appreciated. Adrenergic signaling is a component of the sympathetic nervous system, and the natural ligands, epinephrine and norepinephrine (NE), regulate a multitude of autonomic functions including regulation of both the innate and adaptive immune response. NE is the primary neurotransmitter released by post-ganglionic sympathetic neurons that innervate most all peripheral tissues including lung and secondary lymphoid organs. Thus, the adrenergic signaling pathways are in direct contact with both the central and peripheral immune compartments. We present a perspective on how the adrenergic signaling pathway controls immune function and how β2-agonists may influence inflammation in the context of virus-induced asthma exacerbations.

Effect of probiotic on innate inflammatory response and viral shedding in experimental rhinovirus infection - a randomised controlled trial

Ingestion of probiotics appears to have modest effects on the incidence of viral respiratory infection. The mechanism of these effects is not clear; however, there is evidence from animal models that the probiotic may have an effect on innate immune responses to pathogens. The purpose of this randomised, placebo-controlled study was to determine the effect of administration of Bifidobacterium animalis subspecies lactis Bl-04 on innate and adaptive host responses to experimental rhinovirus challenge. The effect on the response of chemokine (C-X-C motif) ligand 8 (CXCL8) to rhinovirus infection was defined as the primary endpoint for the study. 152 seronegative volunteers who had been supplemented for 28 days, 73 with probiotic and 79 with placebo, were challenged with RV-A39. Supplement or placebo administration was then continued for five days during collection of specimens for assessment of host response, infection, and symptoms. 58 probiotic and 57 placebo-supplemented volunteers met protocol-defined criteria for analysis. Probiotic resulted in higher nasal lavage CXCL8 on day 0 prior to virus challenge (90 vs 58 pg/ml, respectively, P=0.04, ANCOVA). The CXCL8 response to rhinovirus infection in nasal lavage was significantly reduced in the probiotic treated group (P=0.03, ANCOVA). Probiotic was also associated with a reduction in nasal lavage virus titre and the proportion of subjects shedding virus in nasal secretions (76% in the probiotic group, 91% in the placebo group, P=0.04, Fisher Exact test). The administration of probiotic did not influence lower respiratory inflammation (assessed by exhaled nitric oxide), subjective symptom scores, or infection rate. This study demonstrates that ingestion of Bl-04 may have an effect on the baseline state of innate immunity in the nose and on the subsequent response of the human host to rhinovirus infection. Clinicaltrials.gov registry number: NCT01669603.

Airway Epithelial Orchestration of Innate Immune Function in Response to Virus Infection. A Focus on Asthma

Asthma is a very common respiratory condition with a worldwide prevalence predicted to increase. There are significant differences in airway epithelial responses in asthma that are of particular interest during exacerbations. Preventing exacerbations is a primary aim when treating asthma because they often necessitate unscheduled healthcare visits and hospitalizations and are a significant cause of morbidity and mortality. The most common cause of asthma exacerbations is a respiratory virus infection, of which the most likely type is rhinovirus infection. This article focuses on the role played by the epithelium in orchestrating the innate immune responses to respiratory virus infection. Recent studies show impaired bronchial epithelial cell innate antiviral immune responses, as well as augmentation of a pro-Th2 response characterized by the epithelial-derived cytokines IL-25 and IL-33, crucial in maintaining the Th2 cytokine response to virus infection in asthma. A better understanding of the mechanisms of these abnormal immune responses has the potential to lead to the development of novel therapeutic targets for virus-induced exacerbations. The aim of this article is to highlight current knowledge regarding the role of viruses and immune modulation in the asthmatic epithelium and to discuss exciting areas for future research and novel treatments.

Pathogenesis of Viral Infection in Exacerbations of Airway Disease

Chronic airway diseases are a significant cause of morbidity and mortality worldwide, and their prevalence is predicted to increase in the future. Respiratory viruses are the most common cause of acute pulmonary infection, and there is clear evidence of their role in acute exacerbations of inflammatory airway diseases such as asthma and chronic obstructive pulmonary disease. Studies have reported impaired host responses to virus infection in these diseases, and a better understanding of the mechanisms of these abnormal immune responses has the potential to lead to the development of novel therapeutic targets for virus-induced exacerbations. The aim of this article is to review the current knowledge regarding the role of viruses and immune modulation in acute exacerbations of chronic pulmonary diseases and to discuss exciting areas for future research and novel treatments.

Update on Human Rhinovirus and Coronavirus Infections

Human rhinovirus (HRV) and coronavirus (HCoV) infections are associated with both upper respiratory tract illness (“the common cold”) and lower respiratory tract illness (pneumonia). New species of HRVs and HCoVs have been diagnosed in the past decade. More sensitive diagnostic tests such as reverse transcription-polymerase chain reaction have expanded our understanding of the role these viruses play in both immunocompetent and immunosuppressed hosts. Recent identification of severe acute respiratory syndrome and Middle East respiratory syndrome viruses causing serious respiratory illnesses has led to renewed efforts for vaccine development. The role these viruses play in patients with chronic lung disease such as asthma makes the search for antiviral agents of increased importance.

The role of viral infections in exacerbations of chronic obstructive pulmonary disease and asthma

Asthma and chronic obstructive pulmonary disease (COPD) are major causes of global morbidity and mortality worldwide. The clinical course of both asthma and COPD are punctuated by the occurrence of exacerbations, acute events characterized by increased symptoms and airflow obstruction. Exacerbations contribute most of the morbidity, mortality and excess healthcare costs associated with both asthma and COPD. COPD and asthma exacerbations are frequently associated with respiratory virus infections and this has led to an intense research focus into the mechanisms of virus-induced exacerbations over the past decade. Current therapies are effective in reducing chronic symptoms but are less effective in preventing exacerbations, particularly in COPD. Understanding the mechanisms of virus-induced exacerbation will lead to the development of new targeted therapies that can reduce the burden of virus-induced exacerbations. In this review we discuss current knowledge of virus-induced exacerbations of asthma and COPD with a particular focus on mechanisms, human studies, virus-bacteria interactions and therapeutic advances.

Anti-inflammatory effects of the novel inhaled phosphodiesterase type 4 inhibitor CHF6001 on virus-inducible cytokines

Respiratory virus infections precipitate asthma and chronic obstructive pulmonary disease (COPD) exacerbations, with most exacerbations due to rhinovirus infection. Both asthma and COPD exacerbations are not well controlled by steroid therapies, and there is a much research interest in finding improved therapies or combinations of therapies for controlling exacerbations. CHF6001 is a new, inhaled highly potent and selective phosphodiesterase type 4 (PDE4) inhibitor. Using in vitro human bronchial epithelial cells (BEAS‐2B), we investigated the potential anti‐inflammatory effects of CHF6001 on rhinovirus (RV1B)‐induced cytokines. Cytokine mRNA was measured by real‐time PCR, while protein release was measured by ELISA. CHF6001 was used in a 7‐point dose–response curve (1000–0.001 nmol/L) as a 1.5‐h pretreatment prior to infection in comparison with roflumilast. Both roflumilast and CHF6001 reduced RV1B‐induced IL‐8, IL‐29, IP‐10, and RANTES mRNA and protein in a concentration‐dependent manner. Generally, CHF6001 was 13‐ to 16‐fold more potent (subnanomolar EC₅₀ values) than roflumilast at reducing IL‐8, IL‐29, IP‐10, and RANTES mRNA and protein release, but had similar efficacies. In combination with the steroid fluticasone propionate (1 nmol/L), CHF6001 had additive effects, significantly reducing RV‐induced cytokines when compared with steroid or CHF6001 alone. Combined low‐dose steroid and low‐dose CHF6001 had a similar efficacy as high‐dose steroid or CHF6001 alone, indicating the combination had steroid and PDE4 inhibitor sparing effects. Overall results indicate that PDE4 inhibitors have anti‐inflammatory activity against virus‐induced inflammatory mediators and that CHF6001 is more potent than roflumilast.

How does rhinovirus cause the common cold cough?

Cough is a protective reflex to prevent aspiration and can be triggered by a multitude of stimuli. The commonest form of cough is caused by upper respiratory tract infection and has no benefit to the host. The virus hijacks this natural defence mechanism in order to propagate itself through the population. Despite the resolution of the majority of cold symptoms within 2 weeks, cough can persist for some time thereafter. Unfortunately, the mechanism of infectious cough brought on by pathogenic viruses, such as human rhinovirus, during colds, remains elusive despite the extensive work that has been undertaken. For socioeconomic reasons, it is imperative we identify the mechanism of cough. There are several theories which have been proposed as the causative mechanism of cough in rhinovirus infection, encompassing a range of different processes. Those of which hold most promise are physical disruption of the epithelial lining, excess mucus production and an inflammatory response to rhinovirus infection which may be excessive. And finally, neuronal modulation, the most convincing hypothesis, is thought to potentiate cough long after the original stimulus has been cleared. All these hypotheses will be briefly covered in the following sections.

Utility of animal and in vivo experimental infection of humans with rhinoviruses in the development of therapeutic agents for viral exacerbations of asthma and chronic obstructive pulmonary disease

There is an association with acute viral infection of the respiratory tract and exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Although these exacerbations are associated with several types of viruses, human rhinoviruses (HRVs) are associated with the vast majority of disease exacerbations. Due to the lack of an animal species that is naturally permissive for HRVs to use as a facile model system, and the limitations associated with animal models of asthma and COPD, studies of controlled experimental infection of humans with HRVs have been used and conducted safely for decades. This review discusses how these experimental infection studies with HRVs have provided a means of understanding the pathophysiology underlying virus-induced exacerbations of asthma and COPD with the goal of developing agents for their prevention and treatment.

Association of interleukin-8 and neutrophils with nasal symptom severity during acute respiratory infection

Using a large data set (n = 811), the relationship between acute respiratory infection illness severity and inflammatory biomarkers was investigated to determine whether certain symptoms are correlated more closely than others with the inflammatory biomarkers, interleukin‐8 (IL‐8) and nasal neutrophils. Participants with community acquired acute respiratory infection underwent nasal lavage for IL‐8 and neutrophil testing, in addition to multiplex polymerase chain reaction (PCR) methods for the detection and identification of respiratory viruses. Information about symptoms was obtained throughout the duration of the illness episode using the well‐validated Wisconsin Upper Respiratory Symptom Survey (WURSS‐21). Global symptom severity was calculated by the area under the curve (AUC) plotting duration versus WURSS total. Of the specimens tested, 56% were positively identified for one or more of nine different respiratory viruses. During acute respiratory infection illness, both IL‐8 and neutrophils positively correlate with AUC (r_s = 0.082, P = 0.022; r_s = 0.080, P = 0.030). IL‐8 and neutrophils correlate with nasal symptom severity: runny nose (r = 0.13, P = < 0.00001; r = 0.18, P = < 0.003), plugged nose (r = 0.045, P = 0.003; r = 0.14, P = 0.058), and sneezing (r = −0.02, P = < 0.0001; r = −0.0055, P = 0.31). Neutrophils correlate with some quality of life measures such as sleeping well (r = 0.15, P = 0.026). Thus, the study demonstrates that IL‐8 and neutrophils are correlated with severity of nasal symptoms during acute respiratory infection. Further research is necessary to determine if the concentration of these or other biomarkers can predict the overall duration and severity of acute respiratory infection illness. J. Med. Virol. 87:330–337, 2015. © 2014 Wiley Periodicals, Inc.

Supportive treatment for children with the common cold

PURPOSE OF REVIEW

This review summarizes recent developments in the supportive treatment of common cold symptoms in children.

RECENT FINDINGS

Conventional common cold therapies are no longer recommended for use in young children because of safety concerns. There are no studies that convincingly demonstrate the efficacy of any therapy for treatment of common cold symptoms in children less than 6 years of age and it is unlikely studies that establish efficacy can be done. Recent studies report a significant effect of probiotics on the occurrence of common cold illnesses in children, and studies in animals provide a plausible mechanism of action. These data suggest that the use of probiotics may have promise for the prevention of common cold illnesses in children.

SUMMARY

The effect of treatment on the severity of common cold symptoms cannot be accurately assessed with current study designs. In the absence of convincing evidence of efficacy, treatment of young children with symptomatic therapies cannot be recommended. Preliminary data suggest a small, beneficial effect of probiotics for the prevention of common cold illness.

George K, Walsh TJ. Human rhinoviruses

Human rhinoviruses (HRVs), first discovered in the 1950s, are responsible for more than one-half of cold-like illnesses and cost billions of dollars annually in medical visits and missed days of work. Advances in molecular methods have enhanced our understanding of the genomic structure of HRV and have led to the characterization of three genetically distinct HRV groups, designated groups A, B, and C, within the genus Enterovirus and the family Picornaviridae. HRVs are traditionally associated with upper respiratory tract infection, otitis media, and sinusitis. In recent years, the increasing implementation of PCR assays for respiratory virus detection in clinical laboratories has facilitated the recognition of HRV as a lower respiratory tract pathogen, particularly in patients with asthma, infants, elderly patients, and immunocompromised hosts. Cultured isolates of HRV remain important for studies of viral characteristics and disease pathogenesis. Indeed, whether the clinical manifestations of HRV are related directly to viral pathogenicity or secondary to the host immune response is the subject of ongoing research. There are currently no approved antiviral therapies for HRVs, and treatment remains primarily supportive. This review provides a comprehensive, up-to-date assessment of the basic virology, pathogenesis, clinical epidemiology, and laboratory features of and treatment and prevention strategies for HRVs.

Defining critical roles for NF-κB p65 and type I interferon in innate immunity to rhinovirus

The importance of NF-κB activation and deficient anti-viral interferon induction in the pathogenesis of rhinovirus-induced asthma exacerbations is poorly understood. We provide the first in vivo evidence in man and mouse that rhinovirus infection enhanced bronchial epithelial cell NF-κB p65 nuclear expression, NF-κB p65 DNA binding in lung tissue and NF-κB-regulated airway inflammation. In vitro inhibition of NF-κB reduced rhinovirus-induced pro-inflammatory cytokines but did not affect type I/III interferon induction. Rhinovirus-infected p65-deficient mice exhibited reduced neutrophilic inflammation, yet interferon induction, antiviral responses and virus loads were unaffected, indicating that NF-κB p65 is required for pro-inflammatory responses, but redundant in interferon induction by rhinoviruses in vivo. Conversely, IFNAR1^−/− mice exhibited enhanced neutrophilic inflammation with impaired antiviral immunity and increased rhinovirus replication, demonstrating that interferon signalling was critical to antiviral immunity. We thus provide new mechanistic insights into rhinovirus infection and demonstrate the therapeutic potential of targeting NF-κB p65 (to suppress inflammation but preserve anti-viral immunity) and type I IFN signalling (to enhance deficient anti-viral immunity) to treat rhinovirus-induced exacerbations of airway diseases.

Human challenge studies: a review of adequacy of reporting methods and results

Since the 1940s, researchers have purposefully infected healthy adult humans with pathogenic organisms to study how these pathogens cause disease and can be treated and prevented. 'Challenge studies' can be safe, ethical, extremely informative and an efficient use of resources during the clinical development of vaccines, but knowledge of this form of clinical research trial is not widespread. A review of the human challenge literature was performed to determine whether common elements of challenge studies can be identified in the articles published to date. The review demonstrated incomplete reporting of study characteristics deemed necessary for the correct interpretation and application of human challenge study results and for the accurate replication of study methodology. An unofficial extension of the Consolidated Standards of Reporting Trials (CONSORT) statement is proposed.

Pellino-1 selectively regulates epithelial cell responses to rhinovirus

Pellino-1 has recently been identified as a regulator of interleukin-1 (IL-1) signaling, but its roles in regulation of responses of human cells to human pathogens are unknown. We investigated the potential roles of Pellino-1 in the airways. We show for the first time that Pellino-1 regulates responses to a human pathogen, rhinovirus minor group serotype 1B (RV-1B). Knockdown of Pellino-1 by small interfering RNA (siRNA) was associated with impaired production of innate immune cytokines such as CXCL8 from human primary bronchial epithelial cells in response to RV-1B, without impairment in production of antiviral interferons (IFN), and without loss of control of viral replication. Pellino-1 actions were likely to be independent of interleukin-1 receptor-associated kinase-1 (IRAK-1) regulation, since Pellino-1 knockdown in primary epithelial cells did not alter responses to IL-1 but did inhibit responses to poly(I·C), a Toll-like receptor 3 (TLR3) activator that does not signal via IRAK-1 to engender a response. These data indicate that Pellino-1 represents a novel target that regulates responses of human airways to human viral pathogens, independently of IRAK signaling. Neutralization of Pellino-1 may therefore provide opportunities to inhibit potentially harmful neutrophilic inflammation of the airways induced by respiratory viruses, without loss of control of the underlying viral infection.

Viruses exacerbating chronic pulmonary disease: the role of immune modulation

Chronic pulmonary diseases are a major cause of morbidity and mortality and their impact is expected to increase in the future. Respiratory viruses are the most common cause of acute respiratory infections and it is increasingly recognized that respiratory viruses are a major cause of acute exacerbations of chronic pulmonary diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. There is now increasing evidence that the host response to virus infection is dysregulated in these diseases and a better understanding of the mechanisms of abnormal immune responses has the potential to lead to the development of new therapies for virus-induced exacerbations. The aim of this article is to review the current knowledge regarding the role of viruses and immune modulation in chronic pulmonary diseases and discuss avenues for future research and therapeutic implications.

Lower respiratory tract infection induced by a genetically modified picornavirus in its natural murine host

Infections with the picornavirus, human rhinovirus (HRV), are a major cause of wheezing illnesses and asthma exacerbations. In developing a murine model of picornaviral airway infection, we noted the absence of murine rhinoviruses and that mice are not natural hosts for HRV. The picornavirus, mengovirus, induces lethal systemic infections in its natural murine hosts, but small genetic differences can profoundly affect picornaviral tropism and virulence. We demonstrate that inhalation of a genetically attenuated mengovirus, vMC₀, induces lower respiratory tract infections in mice. After intranasal vMC₀ inoculation, lung viral titers increased, peaking at 24 h postinoculation with viral shedding persisting for 5 days, whereas HRV-A01a lung viral titers decreased and were undetectable 24 h after intranasal inoculation. Inhalation of vMC₀, but not vehicle or UV-inactivated vMC₀, induced an acute respiratory illness, with body weight loss and lower airway inflammation, characterized by increased numbers of airway neutrophils and lymphocytes and elevated pulmonary expression of neutrophil chemoattractant CXCR2 ligands (CXCL1, CXCL2, CXCL5) and interleukin-17A. Mice inoculated with vMC₀, compared with those inoculated with vehicle or UV-inactivated vMC₀, exhibited increased pulmonary expression of interferon (IFN-α, IFN-β, IFN-λ), viral RNA sensors [toll-like receptor (TLR)3, TLR7, nucleotide-binding oligomerization domain containing 2 (NOD2)], and chemokines associated with HRV infection in humans (CXCL10, CCL2). Inhalation of vMC₀, but not vehicle or UV-inactivated vMC₀, was accompanied by increased airway fluid myeloperoxidase levels, an indicator of neutrophil activation, increased MUC5B gene expression, and lung edema, a sign of infection-related lung injury. Consistent with experimental HRV inoculations of nonallergic, nonasthmatic human subjects, there were no effects on airway hyperresponsiveness after inhalation of vMC₀ by healthy mice. This novel murine model of picornaviral airway infection and inflammation should be useful for defining mechanisms of HRV pathogenesis in humans.

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.

Role of Nrf2 in host defense against influenza virus in cigarette smoke-exposed mice

Influenza virus is a common respiratory tract viral infection. Although influenza can be fatal in patients with chronic pulmonary diseases such as chronic obstructive pulmonary disease, its pathogenesis is not fully understood. The Nrf2-mediated antioxidant system is essential to protect the lungs from oxidative injury and inflammation. In the present study, we investigated the role of Nrf2 in protection against influenza virus-induced pulmonary inflammation after cigarette smoke exposure with both in vitro and in vivo approaches. For in vitro analyses, peritoneal macrophages isolated from wild-type and Nrf2-deficient mice were treated with poly(I:C) and/or cigarette smoke extract. For in vivo analysis, these mice were infected with influenza A virus with or without exposure to cigarette smoke. In Nrf2-deficient macrophages, NF-κB activation and the induction of its target inflammatory genes were enhanced after costimulation with cigarette smoke extract and poly(I:C) compared with wild-type macrophages. The induction of antioxidant genes was observed for the lungs of wild-type mice but not those of Nrf2-deficient mice after cigarette smoke exposure. Cigarette smoke-exposed Nrf2-deficient mice showed higher rates of mortality than did wild-type mice after influenza virus infection, with enhanced peribronchial inflammation, lung permeability damage, and mucus hypersecretion. Lung oxidant levels and NF-κB-mediated inflammatory gene expression in the lungs were also enhanced in Nrf2-deficient mice. Our data indicate that the antioxidant pathway controlled by Nrf2 is pivotal for protection against the development of influenza virus-induced pulmonary inflammation and injury under oxidative conditions.

Common Respiratory Tract Infections as Psychological Entities: A Review of the Mood and Performance Effects of Being Ill

The clinical manifestations associated with colds and influenza overshadow the equally important mood and performance impairments. While decreased alertness and increased anxiety can be considered side effects of symptomatology, symptoms alone may not be responsible for the psychomotor and attention deficits of colds and influenza, respectively. An alternative hypothesis, as proposed in this review, suggests that the immune response, in the form of a cytokine cascade, may be responsible for both the physical and psychological symptoms. In particular, patterns of cytokine production for each infection will dictate the symptoms and performance deficits both within and between viruses. This hypothesis can be extended to incorporate infectious mononucleosis, as well as colds and influenza. The efficacy of symptom‐based overthe‐counter medications is then called into question.

Co-ordinated role of TLR3, RIG-I and MDA5 in the innate response to rhinovirus in bronchial epithelium

The relative roles of the endosomal TLR3/7/8 versus the intracellular RNA helicases RIG-I and MDA5 in viral infection is much debated. We investigated the roles of each pattern recognition receptor in rhinovirus infection using primary bronchial epithelial cells. TLR3 was constitutively expressed; however, RIG-I and MDA5 were inducible by 8-12 h following rhinovirus infection. Bronchial epithelial tissue from normal volunteers challenged with rhinovirus in vivo exhibited low levels of RIG-I and MDA5 that were increased at day 4 post infection. Inhibition of TLR3, RIG-I and MDA5 by siRNA reduced innate cytokine mRNA, and increased rhinovirus replication. Inhibition of TLR3 and TRIF using siRNA reduced rhinovirus induced RNA helicases. Furthermore, IFNAR1 deficient mice exhibited RIG-I and MDA5 induction early during RV1B infection in an interferon independent manner. Hence anti-viral defense within bronchial epithelium requires co-ordinated recognition of rhinovirus infection, initially via TLR3/TRIF and later via inducible RNA helicases.

The role of viruses in acute exacerbations of asthma

Viral respiratory infections are the most common cause of an acute asthma exacerbation in both children and adults and represent a significant global health burden. An increasing body of evidence supports the hypothesis that these infections cause a greater degree of morbidity in asthmatic subjects than in the healthy population, emphasizing a discrepancy in the antiviral response of asthmatics. In this review we discuss why such a discrepancy might exist, examining the role of the bronchial epithelium as well as the main inflammatory cells, mediators, and molecular pathways that are involved in the immune response. In addition, the potential impact of virus-induced asthma exacerbations on airway remodelling is reviewed and we explore which therapeutic options might be of benefit in preventing the deterioration of asthma control seen following viral infection.

Role of double-stranded RNA pattern recognition receptors in rhinovirus-induced airway epithelial cell responses

Rhinovirus (RV), a ssRNA virus of the picornavirus family, is a major cause of the common cold as well as asthma and chronic obstructive pulmonary disease exacerbations. Viral dsRNA produced during replication may be recognized by the host pattern recognition receptors TLR-3, retinoic acid-inducible gene (RIG)-I, and melanoma differentiation-associated gene (MDA)-5. No study has yet identified the receptor required for sensing RV dsRNA. To examine this, BEAS-2B human bronchial epithelial cells were infected with intact RV-1B or replication-deficient UV-irradiated virus, and IFN and IFN-stimulated gene expression was determined by quantitative PCR. The separate requirements of RIG-I, MDA5, and IFN response factor (IRF)-3 were determined using their respective small interfering RNAs (siRNA). The requirement of TLR3 was determined using siRNA against the TLR3 adaptor molecule Toll/IL-1R homologous region-domain-containing adapter-inducing IFN-beta (TRIF). Intact RV-1B, but not UV-irradiated RV, induced IRF3 phosphorylation and dimerization, as well as mRNA expression of IFN-beta, IFN-lambda1, IFN-lambda2/3, IRF7, RIG-I, MDA5, 10-kDa IFN-gamma-inducible protein/CXCL10, IL-8/CXCL8, and GM-CSF. siRNA against IRF3, MDA5, and TRIF, but not RIG-I, decreased RV-1B-induced expression of IFN-beta, IFN-lambda1, IFN-lambda2/3, IRF7, RIG-I, MDA5, and inflammatory protein-10/CXCL10 but had no effect on IL-8/CXCL8 and GM-CSF. siRNAs against MDA5 and TRIF also reduced IRF3 dimerization. Finally, in primary cells, transfection with MDA5 siRNA significantly reduced IFN expression, as it did in BEAS-2B cells. These results suggest that TLR3 and MDA5, but not RIG-I, are required for maximal sensing of RV dsRNA and that TLR3 and MDA5 signal through a common downstream signaling intermediate, IRF3.

A rat model of picornavirus-induced airway infection and inflammation

Background

Infection of the lower airways by rhinovirus, a member of the picornavirus family, is an important cause of wheezing illnesses in infants, and plays an important role in the pathogenesis of rhinovirus-induced asthma exacerbations. Given the absence of natural rhinovirus infections in rodents, we investigated whether an attenuated form of mengovirus, a picornavirus whose wild-type form causes systemic rather than respiratory infections in its natural rodent hosts, could induce airway infections in rats with inflammatory responses similar to those in human rhinovirus infections.

Results

After inoculation with 10⁷ plaque-forming units of attenuated mengovirus through an inhalation route, infectious mengovirus was consistently recovered on days 1 and 3 postinoculation from left lung homogenates (median Log₁₀ plaque-forming units = 6.0 and 4.8, respectively) and right lung bronchoalveolar lavage fluid (median Log₁₀ plaque-forming units = 5.8 and 4.0, respectively). Insufflation of attenuated mengovirus, but not vehicle or UV-inactivated virus, into the lungs of BN rats caused significant increases (P < 0.05) in lower airway neutrophils and lymphocytes in the bronchoalveolar lavage fluid and patchy peribronchiolar, perivascular, and alveolar cellular infiltrates in lung tissue sections. In addition, infection with attenuated mengovirus significantly increased (P < 0.05) lower airway levels of neutrophil chemoattractant CXCR2 ligands [cytokine-induced neutrophil chemoattractant-1 (CINC-1; CXCL1) and macrophage inflammatory protein-2 (MIP-2; CXCL2)] and monocyte chemoattractant protein-1 (MCP-1; CCL2) in comparison to inoculation with vehicle or UV-inactivated virus.

Conclusion

Attenuated mengovirus caused a respiratory infection in rats with several days of viral shedding accompanied by a lower airway inflammatory response consisting of neutrophils and lymphocytes. These features suggest that mengovirus-induced airway infection in rodents could be a useful model to define mechanisms of rhinovirus-induced airway inflammation in humans.

Budesonide and formoterol inhibit inflammatory mediator production by bronchial epithelial cells infected with rhinovirus

BACKGROUND

Rhinoviruses (RVs) are responsible for the majority of acute asthma and chronic obstructive pulmonary disease (COPD) exacerbations. RVs infect the lower airways and induce the production of pro-inflammatory and remodelling-associated mediators. Budesonide (BUD) and formoterol (FORM) synergize in controlling asthma and COPD exacerbations; however, their effects on virus-induced inflammation and remodelling are less known.

OBJECTIVE

We investigated whether BUD and FORM synergize in suppressing RV-induced inflammation and remodelling in the airways.

METHODS

In vitro models of RV infection of BEAS-2B and primary normal human bronchial epithelial (NHBE) cells were used. We assessed the effects of individual and combined drugs administered post-infection, at a clinically relevant concentration range (10(-6)-10(-10) m), on the production of CCL5, CXCL10, CXCL8, IL-6 and the remodelling-associated VEGF and bFGF, using ELISA and RT-PCR.

RESULTS

BUD effectively suppressed RV-mediated induction of all mediators studied, in a concentration-dependent manner. FORM alone suppressed the production of CXCL8 and bFGF. The combination of BUD and FORM had concentration-dependent, additive or synergistic effects in the suppression of RV-induced CCL5, CXCL8 and CXCL10 in both cell types as well as VEGF in NHBE only. Combination treatment also resulted in an enhanced suppression of RV-induced IL-6, and CCL5 at the mRNA level as compared with BUD or FORM alone.

CONCLUSION

BUD and FORM suppress RV-induced chemokines and growth factors in bronchial epithelial cells in a concentration-dependent, synergistic or additive manner. These data further support the combined use of BUD and FORM in asthma and COPD and intensification of this therapy during exacerbations.

Host immune responses to rhinovirus: mechanisms in asthma

Viral respiratory infections can have a profound effect on many aspects of asthma including its inception, exacerbations, and, possibly, severity. Of the many viral respiratory infections that influence asthma, the common cold virus, rhinovirus, has emerged as the most frequent illness associated with exacerbations and other aspects of asthma. The mechanisms by which rhinovirus influences asthma are not fully established, but current evidence indicates that the immune response to this virus is critical in this process. Many airway cell types are involved in the immune response to rhinovirus, but most important are respiratory epithelial cells and possibly macrophages. Infection of epithelial cells generates a variety of proinflammatory mediators to attract inflammatory cells to the airway with a subsequent worsening of underlying disease. Furthermore, there is evidence that the epithelial airway antiviral response to rhinovirus may be defective in asthma. Therefore, understanding the immune response to rhinovirus is a key step in defining mechanisms of asthma, exacerbations, and, perhaps most importantly, improved treatment.

Attenuated P2X7 pore function as a risk factor for virus-induced loss of asthma control

RATIONALE

Upper respiratory tract infection is a guideline accepted risk domain for the loss of asthma control. The ionotrophic nucleotide receptor P2X(7) regulates compartmentalized acute inflammation and the immune response to airway pathogens.

OBJECTIVES

We hypothesized that variability in P2X(7) function contributes to neutrophilic airway inflammation during a cold and thereby is linked to acute asthma.

METHODS

Research volunteers with asthma were enrolled at the onset of a naturally occurring cold and monitored through convalescence, assessing symptoms, lung function, and airway inflammation. P2X(7) pore activity in whole blood samples was measured using a genomically validated flow cytometric assay.

MEASUREMENTS AND MAIN RESULTS

Thirty-five participants with mild to moderate allergic asthma were enrolled and 31 completed all visits. P2X(7) pore function correlated with the change in nasal lavage neutrophil counts during the cold (R(s) = 0.514, P = 0.004) and was inversely related to the change in asthma symptoms (R(s) = -0.486, P = 0.009). The change in peak expiratory flow recordings, precold use of inhaled corticosteroids, and P2X(7) pore function were multivariate predictors of asthma symptoms (P = 0.001, < 0.001 and = 0.003 respectively). Attenuated P2X(7) activity was associated with the risk of losing asthma control (crude odds ratio, 11.0; 95% confidence interval, 1.1-106.4) even after adjustment for inhaled corticosteroids and rhinovirus (odds ratio, 15.0).

CONCLUSIONS

A whole blood P2X(7) pore assay robustly identifies participants with loss-of-function genotypes. Using this assay as an epidemiologic tool, attenuated P2X(7) pore activity may be a novel biomarker of virus-induced loss of asthma control.

Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease are inflammatory lung disorders responsible for significant morbidity and mortality worldwide. While the importance of allergic responses in asthma is well known, respiratory viral and bacterial infections and pollutants especially cigarette smoke are important factors in the pathogenesis of both diseases. Corticosteroid treatment remains the first preference of treatment in either disease, however these therapies are not always completely effective, and are associated with side effects and steroid resistance. Due to such limitations, development of new treatments represents a major goal for both the pharmaceutical industry and academic researchers. There are now excellent reasons to promote NF-kappaB signalling intermediates and Rel family proteins as potential therapeutic targets for both asthma and chronic obstructive pulmonary disease. This notion is supported by the fact that much of the underlying inflammation of both diseases independent of stimuli, is mediated at least in part, by NF-kappaB mediated signalling events in several cell types. Also, a range of inhibitors of NF-kappaB signalling intermediates are now available, including DNA oligonucleotides and DNA-peptide molecules that act as NF-kappaB decoy sequences, small molecule inhibitors such as IKK-beta inhibitors, and proteasome inhibitors affecting NF-kappaB signalling, that have either shown promise in animal models or have begun clinical trials in other disorders. This review will focus on the role of NF-kappaB in both diseases, will discuss its suitability as a target, and will highlight recent key studies that support the potential of NF-kappaB as a therapeutic target in these two important inflammatory lung diseases.

Human rhinovirus infection enhances airway epithelial cell production of growth factors involved in airway remodeling

BACKGROUND

Childhood human rhinovirus (HRV) infections are associated with an increased risk of asthma. We reasoned that HRV infections might be important in the pathogenesis of airway remodeling, thereby providing a mechanism by which these children are at risk of asthma.

OBJECTIVE

We sought to determine whether HRV infection of airway epithelial cells regulates production of growth factors associated with airway remodeling and to determine whether vascular endothelial growth factor (VEGF) was upregulated in airways during HRV-induced natural colds.

METHODS

Cultured human airway epithelial cells were infected with HRV. Amphiregulin, activin A, and VEGF protein levels were assayed by means of ELISA, and VEGF mRNA was quantified by using real-time RT-PCR. Pharmacologic inhibitors were used to assess the role of mitogen-activated protein kinase and nuclear factor kappaB pathways. Nasal lavage samples from subjects with confirmed natural HRV infections were assayed for VEGF protein and compared with baseline levels and with control levels.

RESULTS

HRV infection upregulated amphiregulin, activin A, and VEGF protein levels compared with control media (P < .05). VEGF gene expression was maximally induced 3 hours after infection. HRV-induced generation of VEGF was regulated by p38 mitogen-activated protein kinase and extracellular signal-regulated kinase 1/2 pathways but did not depend on nuclear factor kappaB activation. In subjects with HRV infections, VEGF levels during peak cold symptoms were significantly higher than at baseline (P = .005) or in control subjects (P < .01).

CONCLUSION

HRV-16 infection upregulates amphiregulin, activin A, and VEGF in airway epithelial cells, and HRV infections in vivo upregulate airway VEGF production.

Pathogen-directed therapy in acute exacerbations of chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the natural history of this chronic lung disorder. These events can be caused by a large number of infectious and noninfectious agents and are associated with an increased local and systemic inflammatory response. Their frequency and severity have been linked to progressive deterioration in lung function and health status. Infectious pathogens ranging from viral to atypical and typical bacteria have been implicated in the majority of episodes. Most therapeutic regimens to date have emphasized broad, nonspecific approaches to bronchoconstriction and pulmonary inflammation. Increasingly, therapy that targets specific etiologic pathogens has been advocated. These include clinical and laboratory-based methods to identify bacterial infections. Further additional investigation has suggested specific pathogens within this broad class. As specific antiviral therapies become available, better diagnostic approaches to identify specific pathogens will be required. Furthermore, prophylactic therapy for at-risk individuals during high-risk times may become a standard therapeutic approach. As such, the future will likely include aggressive diagnostic algorithms based on the combination of clinical syndromes and rapid laboratory modalities to identify specific causative bacteria or viruses.

Rat coronaviruses infect rat alveolar type I epithelial cells and induce expression of CXC chemokines

We analyzed the ability of two rat coronavirus (RCoV) strains, sialodacryoadenitis virus (SDAV) and Parker's RCoV (RCoV-P), to infect rat alveolar type I cells and induce chemokine expression. Primary rat alveolar type II cells were transdifferentiated into the type I cell phenotype. Type I cells were productively infected with SDAV and RCoV-P, and both live virus and UV-inactivated virus induced mRNA and protein expression of three CXC chemokines: CINC-2, CINC-3, and LIX, which are neutrophil chemoattractants. Dual immunolabeling of type I cells for viral antigen and CXC chemokines showed that chemokines were expressed primarily by uninfected cells. Virus-induced chemokine expression was reduced by the IL-1 receptor antagonist, suggesting that IL-1 produced by infected cells induces uninfected cells to express chemokines. Primary cultures of alveolar epithelial cells are an important model for the early events in viral infection that lead to pulmonary inflammation.

Cooperative effects of rhinovirus and TNF-{alpha} on airway epithelial cell chemokine expression

Rhinovirus (RV) infections trigger exacerbations of airways disease, but underlying mechanisms remain unknown. We hypothesized that RV and cytokines present in inflamed airways combine to induce augmented airway epithelial cell chemokine expression, promoting further inflammation. To test this hypothesis in a cellular system, we examined the combined effects of RV39 and TNF-alpha, a cytokine increased in asthma and chronic obstructive pulmonary disease, on airway epithelial cell proinflammatory gene expression. Costimulation of 16HBE14o- human bronchial epithelial cells and primary mucociliary-differentiated tracheal epithelial cells with RV and TNF-alpha induced synergistic increases in IL-8 and epithelial neutrophil attractant-78 production. Similar synergism was observed for IL-8 promoter activity, demonstrating that the effect is transcriptionally mediated. Whereas increases in ICAM-1 expression and viral load were noted 16-24 h after costimulation, cooperative effects between RV39 and TNF-alpha were evident 4 h after stimulation and maintained despite incubation with blocking antibody to ICAM-1 given 2 h postinfection or UV irradiation of virus, implying that effects were not solely due to changes in ICAM-1 expression. Furthermore, RV39 infection induced phosphorylation of ERK and transactivation of the IL-8 promoter AP-1 site, which functions as a basal level enhancer, leading to enhanced TNF-alpha responses. We conclude that RV infection and TNF-alpha stimulation induce cooperative increases in epithelial cell chemokine expression, providing a cellular mechanism for RV-induced exacerbations of airways disease.

Interleukin-17A modulates human airway epithelial responses to human rhinovirus infection

Human rhinovirus (HRV) infections are associated with exacerbations of asthma and chronic obstructive pulmonary disease that are characterized by a selective neutrophil infiltration. IL-17A, a cytokine derived primarily from activated T cells, has been linked to neutrophilic inflammation of the airways. We hypothesized that IL-17A alters the response of HRV-infected epithelial cells to modulate airway inflammatory cell populations. IL-17A synergistically enhanced HRV-16-induced epithelial production of the neutrophil chemoattractant, IL-8, as well as human beta-defensin-2 (HBD-2), a chemoattractant for immature dendritic cells and memory T cells, but suppressed viral production of the eosinophil chemoattractant, RANTES. These effects were not due to alterations of viral uptake or replication by IL-17A. The synergy between HRV-16 and IL-17A for IL-8 protein production was both dose- and time-dependent. IL-8 induction by IL-17A or HRV-16, alone and in combination, was reduced by inhibitors of the p38 and p44/42 MAPK pathways. By contrast, induction of HBD-2 depended on the activation of the p38 and JNK pathways. The ability of IL-17A to synergistically enhance HRV-induced IL-8 is mediated posttranscriptionally, since IL-8 promoter activation by the combination of the two stimuli was merely additive, whereas the combination of IL-17A and HRV-16 led to stabilization of IL-8 mRNA. Similarly, stimulation of HBD-2 promoter constructs by the combination of IL-17A and HRV-16 was no more than the sum of the individual responses. Further studies are needed to examine HBD-2 mRNA stability. Taken together, these data represent the first demonstration that IL-17A can modify epithelial responses to HRV in a manner that would be expected to favor the recruitment of neutrophils, immature dendritic cells, and memory T cells to the airways.

Rhinovirus activates interleukin-8 expression via a Src/p110beta phosphatidylinositol 3-kinase/Akt pathway in human airway epithelial cells

Rhinovirus (RV) is responsible for the majority of common colds and triggers exacerbations of asthma and chronic obstructive lung disease. We have shown that RV serotype 39 (RV39) infection activates phosphatidylinositol 3 (PI 3)-kinase and the serine threonine kinase Akt minutes after infection and that the activation of PI 3-kinase and Akt is required for maximal interleukin-8 (IL-8) expression. Here, we further examine the contributions of Src and PI 3-kinase activation to RV-induced Akt activation and IL-8 expression. Confocal fluorescent microscopy of 16HBE14o- human bronchial epithelial cells showed rapid (10-min) colocalization of RV39 with Src, p85alpha PI 3-kinase, p110beta PI 3-kinase, Akt and Cit-Akt-PH, a fluorescent Akt pleckstrin homology domain which binds PI(3,4,5)P(3). The chemical Src inhibitor PP2 {4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo [3,4-d]pyrimidine} and the PI 3-kinase inhibitor LY294002 each inhibited Akt phosphorylation and the colocalization of RV39 with Akt. Digoxigenin-tagged RV coprecipitated with a Crosstide kinase likely to be Akt, and inhibition of Src blocked kinase activity. Digoxigenin-tagged RV39 colocalized with the lipid raft marker ceramide. In 16HBE14o- and primary mucociliary differentiated human bronchial epithelial cells, inhibition of Src kinase activity with the Src family chemical inhibitor PP2, dominant-negative Src (K297R), and Src small interfering RNA (siRNA) each inhibited RV39-induced IL-8 expression. siRNA against p110beta PI 3-kinase also inhibited IL-8 expression. These data demonstrate that, in the context of RV infection, Src and p110beta PI 3-kinase are upstream activators of Akt and the IL-8 promoter and that RV colocalizes with Src, PI 3-kinase, and Akt in lipid rafts.

The anti-inflammatory effect of glucocorticoids is mediated by glucocorticoid-induced leucine zipper in epithelial cells

BACKGROUND

Nuclear factor kappaB (NF-kappaB) plays a key role in the pathogenesis of asthma, being linked to the production of inflammatory cytokines that drive inflammation. A recently described anti-inflammatory protein, glucocorticoid-induced leucine zipper (GILZ), interferes with NF-kappaB-mediated gene transcription in T cells and macrophages.

OBJECTIVE

We sought to analyze the regulation of GILZ expression in airway epithelial cells and determine whether GILZ mediates part of the anti-inflammatory effect of corticosteroids.

METHODS

GILZ expression was assessed by means of PCR and immunoblotting in human epithelial cells at baseline and after stimulation with dexamethasone or cytokines (IL-1beta, TNF-alpha, and IFN-gamma). The effect of GILZ on LPS-, IL-1beta-, and polyinosinic:polycytidylic acid-induced NF-kappaB activation was assessed in BEAS-2B cells overexpressing GILZ. The requirement for GILZ in the inhibitory action of dexamethasone was assessed by knocking down GILZ expression by means of small interfering RNA (siRNA) technology.

RESULTS

GILZ is constitutively expressed by human airway epithelial cells, and its levels are increased by dexamethasone and decreased by inflammatory cytokines. Overexpression of GILZ in BEAS-2B cells significantly inhibited the ability of IL-1beta, LPS, and polyinosinic:polycytidylic acid to activate NF-kappaB, whereas knockdown of GILZ inhibited the ability of dexamethasone to suppress IL-1beta-induced chemokine expression.

CONCLUSION

This study demonstrates the expression of GILZ in human airway epithelial cells, its induction by dexamethasone, its suppression by inflammatory cytokines, and its role in mediating the anti-inflammatory effects of dexamethasone.

CLINICAL IMPLICATIONS

Therapeutic upregulation of GILZ may be a novel strategy for the treatment of asthma.

Respiratory viral infections drive chemokine expression and exacerbate the asthmatic response

A number of investigations have linked respiratory vial infections and the intensity and subsequent exacerbation of asthma through host response mechanisms. For example, it is likely that the immune-inflammatory response to respiratory syncytial virus can cause a predisposition toward an intense inflammatory reaction associated with asthma, and adenovirus might cause exacerbation of the immune response associated with chronic obstructive pulmonary disease. In each of these situations, the host's immune response plays a critical mechanistic role through the production of certain cytokines and chemokines. Specific aspects of these augmented immune responses are determined by the biology of the virus, the genetic variability of the host, and the cytokine-chemokine phenotype of the involved tissue. For instance, the type 1/type 2 cytokine ratio in the airways during infection with rhinovirus determines how long the viral infection endures. By this same theory, it has been demonstrated that chemokine levels produced during respiratory syncytial virus infection determine host responses to later immune stimuli in the lung, with the potential to augment the asthmatic response. Further research in this area will clarify cytokines, chemokines, or cell targets, which will provide the basis for next-generation therapies.

Human rhinovirus attenuates the type I interferon response by disrupting activation of interferon regulatory factor 3

The type I interferon (IFN) response requires the coordinated activation of the latent transcription factors NF-kappaB, interferon regulatory factor 3 (IRF-3), and ATF-2, which in turn activate transcription from the IFN-beta promoter. Synthesis and subsequent secretion of IFN-beta activate the Jak/STAT signaling pathway, resulting in the transcriptional induction of the full spectrum of antiviral gene products. We utilized high-density microarrays to examine the transcriptional response to rhinovirus type 14 (RV14) infection in HeLa cells, with particular emphasis on the type I interferon response and production of IFN-beta. We found that, although RV14 infection results in altered levels of a wide variety of host mRNAs, induction of IFN-beta mRNA or activation of the Jak/STAT pathway is not seen. Prior work has shown, and our results have confirmed, that NF-kappaB and ATF-2 are activated following infection. Since many viruses are known to target IRF-3 to inhibit the induction of IFN-beta mRNA, we analyzed the status of IRF-3 in infected cells. IRF-3 was translocated to the nucleus and phosphorylated in RV14-infected cells. Despite this apparent activation, very little homodimerization of IRF-3 was evident following infection. Similar results in A549 lung alveolar epithelial cells demonstrated the biological relevance of these findings to RV14 pathogenesis. In addition, prior infection of cells with RV14 prevented the induction of IFN-beta mRNA following treatment with double-stranded RNA, indicating that RV14 encodes an activity that specifically inhibits this innate host defense pathway. Collectively, these results indicate that RV14 infection inhibits the host type I interferon response by interfering with IRF-3 activation.

Combination therapy: Synergistic suppression of virus-induced chemokines in airway epithelial cells

Viruses are associated with the majority of exacerbations of asthma and chronic obstructive pulmonary disease. Virus induction of neutrophil and lymphocyte chemokines in bronchial epithelium is important in exacerbation pathogenesis. Combined corticosteroid/beta2 agonists synergistically suppress airway smooth muscle chemokine production. Because bronchial epithelium expresses glucocorticoid and beta2 receptors, we investigated whether combination therapy can synergistically suppress rhinovirus-induced bronchial epithelial cell neutrophil (CXCL5, CXCL8) and lymphocyte (CCL5, CXCL10) chemokine production. We investigated modulation of rhinovirus- and IL-1beta-induced bronchial epithelial cell chemokine production by salmeterol and fluticasone propionate, used at therapeutic concentrations, alone and in combination. After 1 h pretreatment, combined treatment significantly inhibited rhinovirus 16, 1B, and IL-1beta-induced CCL5 and CXCL8 protein and mRNA production in BEAS-2B cells compared with fluticasone alone. When used 4 h after treatment, the combination significantly reduced virus-induced CCL5 but not CXCL8. Salmeterol alone had no effect; therefore, this inhibition was synergistic. Kinetic analysis demonstrated that combination therapy reduced by 5-fold the concentration of corticosteroid required to inhibit CXCL8 mRNA expression. In primary cells, salmeterol alone reduced rhinovirus-induced CCL5 and CXCL10 and increased CXCL5 production in a dose-dependent manner but had no effect on CXCL8. Fluticasone alone reduced CCL5, CXCL8, and CXCL10 but had no effect on CXCL5. Combination therapy augmented inhibition of CXCL8, CCL5, and CXCL10 but had no effect on CXCL5. Corticosteroids and beta2 agonists suppress rhinovirus-induced chemokines in bronchial epithelial cells through synergistic and additive mechanisms. This effect was greater for lymphocyte- than for neutrophil-related chemokines.

New treatment regimes for virus-induced exacerbations of asthma

This review will focus on the role of viruses as causes of asthma exacerbations. The article will briefly review the current literature supporting this view, with a special focus on human rhinovirus (RV), the main virus associated with exacerbations of asthma. The review will then refer to possible strategies for treatment, and will include discussion on treatment with specific anti-viral therapy and type I interferon as a treatment for RV. The review will also include a discussion on current therapies for asthma, such as glucocorticosteroid and beta(2) agonist therapy alone and in combination and why this may be relevant to virus-induced exacerbations of asthma. Finally, the potential for future anti-inflammatory/immunomodulatory therapies with a focus on NF-kappaB inhibition will be discussed.

Toll-like receptor 3 is induced by and mediates antiviral activity against rhinovirus infection of human bronchial epithelial cells

Rhinoviruses (RV) are the major cause of the common cold and acute exacerbations of asthma and chronic obstructive pulmonary disease. Toll-like receptors (TLRs) are a conserved family of receptors that recognize and respond to a variety of pathogen-associated molecular patterns. TLR3 recognizes double-stranded RNA, an important intermediate of many viral life cycles (including RV). The importance of TLR3 in host responses to virus infection is not known. Using BEAS-2B (a human bronchial epithelial cell-line), we demonstrated that RV replication increased the expression of TLR3 mRNA and TLR3 protein on the cell surface. We observed that blocking TLR3 led to a decrease in interleukin-6, CXCL8, and CCL5 in response to poly(IC) but an increase following RV infection. Finally, we demonstrated that TLR3 mediated the antiviral response. This study demonstrates an important functional requirement for TLR3 in the host response against live virus infection and indicates that poly(IC) is not always a good model for studying the biology of live virus infection.

Nasal cytokines as mediators of illness during the common cold

Identification of a pharmacologically targeted mediator of the common cold is a desirable, but, to date, elusive goal of current research. The roles of various mediators, such as histamine, leukotrienes, bradykinin, and, more recently, chemokines and cytokines, in the pathophysiology and development of complications of the common cold are the subject of previous and current investigations. Establishing causality of a mediator in the common cold has been difficult for a number of reasons, including the limitations of our research tools and protocols and the complexity of the inflammatory and immune pathways that participate during the common cold. The available evidence for mediation of the common cold is the subject of this manuscript.

Development of rhinovirus study model using organ culture of turbinate mucosa

To better understand the pathophysiology of rhinovirus (RV) infection, a development of a study model using organ culture of turbinate mucosa was sought. Inferior turbinate mucosal tissues were cultured using air-liquid interface methods, on a support of gelfoam soaked in culture media. RV-16 was applied to the mucosal surface and washed off, and histological changes were evaluated. The success of RV infection was assayed by semi-nested RT-PCR of the mucosal surface fluid taken 48h after incubation. Intracellular RVs were visualized by in situ hybridization (ISH). Secretion of the cytokines, IL-6 and IL-8, into the culture media was quantitated by ELISA. After 7 days of culture, the turbinate mucosae did not show significant damage. A PCR product indicating successful RV infection was detected in 5 out of 10 mucosal tissues. ISH showed a very small number of positively stained cells focally located in the epithelial layer. In the beginning 24h after infection, secretion of IL-6 and IL-8 into the culture media of infected mucosae was significantly greater than into the media of control mucosae. Our results indicate that the air-liquid interface organ culture of turbinate mucosa could serve as an acceptable in vitro model for studying RV infection.

Mechanisms of rhinovirus-induced asthma

Several epidemiological studies using sensitive detection methodologies have confirmed that the majority of acute asthma exacerbations follow upper respiratory tract infections--common colds. Most of these colds are due to human rhinoviruses (RVs). RVs are able to reach and replicate in epithelial cells of the lower airways and can activate these cells to produce pro-inflammatory mediators. Under some circumstances, RVs can also become cytotoxic to the epithelium. Atopic asthmatic individuals produce less interferon-gamma and more interleukin-10 than normal subjects in response to RV infection. Symptom severity as well as viral shedding after experimental RV infection, is inversely correlated with 'atopic' status, expressed as the interferon-gamma to interleukin-5 ratio. Expression of co-stimulatory molecules on immune cells is also affected in atopic asthmatics, suggesting an aberrant immune response to RV that may lead to suboptimal viral clearance and viral persistence. Some of the above effects can be reversed in vitro by corticosteroids, second-generation antihistamines or anti-oxidants; however, the optimal strategy for treating acute asthma exacerbations requires further research at both mechanistic and clinical levels.