Leukocyte responses to experimental infection with human rhinovirus

A Tool for Investigating Asthma and COPD Exacerbations: A Newly Manufactured and Well Characterised GMP Wild-Type Human Rhinovirus for Use in the Human Viral Challenge Model

Background

Human Rhinovirus infection is an important precursor to asthma and chronic obstructive pulmonary disease exacerbations and the Human Viral Challenge model may provide a powerful tool in studying these and other chronic respiratory diseases. In this study we have reported the production and human characterisation of a new Wild-Type HRV-16 challenge virus produced specifically for this purpose.

Methods and Stock Development

A HRV-16 isolate from an 18 year old experimentally infected healthy female volunteer (University of Virginia Children’s Hospital, USA) was obtained with appropriate medical history and consent. We manufactured a new HRV-16 stock by minimal passage in a WI-38 cell line under Good Manufacturing Practice conditions. Having first subjected the stock to rigorous adventitious agent testing and determining the virus suitability for human use, we conducted an initial safety and pathogenicity clinical study in adult volunteers in our dedicated clinical quarantine facility in London.

Human Challenge and Conclusions

In this study we have demonstrated the new Wild-Type HRV-16 Challenge Virus to be both safe and pathogenic, causing an appropriate level of disease in experimentally inoculated healthy adult volunteers. Furthermore, by inoculating volunteers with a range of different inoculum titres, we have established the minimum inoculum titre required to achieve reproducible disease. We have demonstrated that although inoculation titres as low as 1 TCID₅₀ can produce relatively high infection rates, the optimal titre for progression with future HRV challenge model development with this virus stock was 10 TCID₅₀. Studies currently underway are evaluating the use of this virus as a challenge agent in asthmatics.

Trial Registration

ClinicalTrials.gov NCT02522832

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.

Airway inflammation and illness severity in response to experimental rhinovirus infection in asthma

Background:

The nature of bronchial mucosal inflammation and its physiologic and clinical significance in rhinovirus-induced asthma exacerbations is unclear. We investigated bronchial mucosal inflammatory response and its association with physiologic and clinical outcomes in an experimental model of rhinovirus-induced asthma exacerbations.

Methods:

We used immunohistochemistry methods to detect phenotypes of inflammatory cells infiltrating the bronchial mucosa before and after experimental rhinovirus infection in 10 subjects with asthma and 15 normal subjects.

Results:

Compared with baseline, rhinovirus infection significantly increased the number of epithelial (P = .005) and subepithelial (P = .017) neutrophils in subjects with asthma only and subepithelial CD68⁺ macrophages in both subjects with asthma (P = .009) and normal subjects (P = .018) but more so in those with asthma (P = .021). Numbers of CD45⁺, CD68⁺, and CD20⁺ cells; neutrophils; and eosinophils at day 4 postinfection were positively associated with virus load (r = 0.50-0.72, P = .016-0.03). At acute infection in subjects with asthma, CD4⁺ cells correlated with chest symptom scores (r = 0.69, P = .029), the fall in the 10% fall in FEV₁ (PC₁₀) correlated with neutrophils (r = −0.89, P = .029), the PC₁₀ correlated inversely with CD4⁺ (r = −0.67, P = .023) and CD8⁺ cells (r = −0.65, P = .03), the 20% fall in FEV₁ was inversely associated with CD20⁺ cells (r = −0.65, P = .03), and higher epithelial CD8⁺ cell counts were significantly associated with a greater maximum fall in FEV₁ (r = −0.72, P = .03), whereas higher subepithelial mast cell counts were significantly associated with a lower maximum percent fall in peak expiratory flow (r = 0.8, P = .024).

Conclusions:

In subjects with asthma, rhinovirus infection induces bronchial mucosal neutrophilia and more severe monocyte/macrophage infiltration than in normal subjects. Airway neutrophils, eosinophils, and T and B lymphocytes during infection are related to virus load and physiologic and clinical severity, whereas mast cells are related to greater lung function.

A proprietary extract from the echinacea plant (Echinacea purpurea) enhances systemic immune response during a common cold

In a previous paper, it was reported that Echinilin (Factors R & D Technologies, Burnaby, British Columbia, Canada) a formulation prepared from freshly harvested Echinacea purpurea plants and standardized on the basis of three known active components (alkamides, cichoric acid and polysaccharides) is effective for the treatment of a naturally acquired common cold. However, the mechanism by which this effect is achieved remains unknown. In the present study, Echinilin or placebo were administered to volunteers at the onset of their cold for a period of 7 days, with eight doses (5 mL/dose) on day 1 and three doses on subsequent days. Fasting blood samples were obtained before and during their colds. The decrease in total daily symptomatic score was more evident in the echinacea group than in the placebo group. These effects of echinacea were associated with a significant and sustained increase in the number of circulating total white blood cells, monocytes, neutrophils and NK cells. In the later part of the cold, the echinacea treatment suppressed the cold-related increase in superoxide production by the neutrophils. These results suggest that Echinilin, by enhancing the non-specific immune response and eliciting free radical scavenging properties, may have led to a faster resolution of the cold symptoms.

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.

Allergen challenge-induced acute exudation of IL-8, ECP and alpha2-macroglobulin in human rhinovirus-induced common colds

Rhinovirus infections cause exacerbations of eosinophilic airway disease. The acute effects of allergen‐challenge on nasal interleukin‐8 (IL‐8), eosinophil cationic protein (ECP), and α₂‐macroglobulin were examined in atopic subjects with common cold symptoms.

Twenty‐three patients with seasonal allergic rhinitis were inoculated with human rhinovirus 16 outside the pollen season. Diluent and allergen challenges, followed by nasal lavages, were carried out about 3 months before and 4 days after virus inoculation.

Seventeen patients developed significant common cold symptoms with increased nasal lavage fluid levels of α₂‐macroglobulin, IL‐8, and ECP at baseline (p<0.001–0.05 versus before inoculation), and were further increased by allergen challenge (p<0.001–0.05); IL‐8 and ECP levels were correlated (r=0.63, p<0.001). Before inoculation, the six patients who later did not develop common cold symptoms had high levels of IL‐8 and myeloperoxidase (MPO), and exhibited strong allergen‐induced plasma exudation responses (α₂‐macroglobulin). After inoculation, IL‐8 and ECP did not increase in these symptomless subjects.

In conclusion, high nasal interleukin‐8 and myeloperoxidase levels and exudative hyperresponsiveness may protect against infection. The association between nasal interleukin‐8 and eosinophil cationic protein in common cold, particularly that observed in nasal lavage fluids after allergen‐induced acute exudation of plasma, suggests the involvement of interleukin‐8 in exacerbation of airway mucosal eosinophil activity.

Allergen challenge-induced acute exudation of IL-8, ECP and alpha2-macroglobulin in human rhinovirus-induced common colds

Rhinovirus infections cause exacerbations of eosinophilic airway disease. The acute effects of allergen-challenge on nasal interleukin-8 (IL-8), eosinophil cationic protein (ECP), and alpha2-macroglobulin were examined in atopic subjects with common cold symptoms. Twenty-three patients with seasonal allergic rhinitis were inoculated with human rhinovirus 16 outside the pollen season. Diluent and allergen challenges, followed by nasal lavages, were carried out about 3 months before and 4 days after virus inoculation. Seventeen patients developed significant common cold symptoms with increased nasal lavage fluid levels of alpha2-macroglobulin, IL-8, and ECP at baseline (p<0.001-0.05 versus before inoculation), and were further increased by allergen challenge (p< 0.001-0.05); IL-8 and ECP levels were correlated (r = 0.63, p<0.001). Before inoculation, the six patients who later did not develop common cold symptoms had high levels of IL-8 and myeloperoxidase (MPO), and exhibited strong allergen-induced plasma exudation responses (alpha2-macroglobulin). After inoculation, IL-8 and ECP did not increase in these symptomless subjects. In conclusion, high nasal interleukin-8 and myeloperoxidase levels and exudative hyperresponsiveness may protect against infection. The association between nasal interleukin-8 and eosinophil cationic protein in common cold, particularly that observed in nasal lavage fluids after allergen-induced acute exudation of plasma, suggests the involvement of interleukin-8 in exacerbation of airway mucosal eosinophil activity.

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

Neutrophil infiltration is a well-documented early event in the pathogenesis of rhinovirus (RV) infections. To further understand the mechanisms responsible for this neutrophilia, we determined whether interleukin (IL)-8 was present at sites of experimental RV infection in vivo and characterized the mechanism(s) by which RV stimulates IL-8 production in vitro. IL-8 was readily detectable in the nasal washings of all normal volunteers and did not increase with sham nasal inoculation. In contrast, RV infection caused a significant additional increase in nasal IL-8, the levels of which peaked 48-72 h after virus inoculation. RV was a potent stimulator of IL-8 protein production by A549 epithelial-like cells, MRC-5 fibroblasts, and normal human bronchial epithelial cells in vitro. This induction was associated with a significant increase in IL-8 mRNA accumulation and gene transcription. RV also stimulated IL-8 promoter-driven luciferase activity. This stimulation was significantly decreased by mutation of the nuclear factor (NF)-IL-6 site and was completely abrogated by mutation of the NF-kappaB site in this promoter. In addition, NF-kappaB-DNA binding activity was rapidly induced in RV-infected cells. This inducible binding was made up of p65 and, to a lesser extent, p50 NF-kappaB moieties. These studies demonstrate that IL-8 is present in normal nasal secretions and that the levels of IL-8 are further increased after RV infection. They also demonstrate that RVs are potent stimulators of IL-8 production and that this induction is mediated, at least in part, by an NF-kappaB-dependent transcriptional activation pathway. IL-8 may contribute to the pathogenesis of RV infection, and NF-kappaB activation may be a central event in RV-induced pathologies.

Histopathological changes in the upper respiratory tract of F344 rats following infection with a rat-adapted influenza virus

The present study determined the morphogenesis of upper respiratory tract disease in rats following infection with a rat-adapted influenza virus. Sixty-eight 60-day-old, male F344 rats were infected by intranasal inoculation and necropsied at days 1, 2, 4, 7, 14, and 28 post-inoculation (PI). Responses to infection were studied by routine light microscopy for histopathologic changes and immunocytochemistry for localization of viral antigen. Severe infection-induced changes involved the respiratory epithelium and underlying lamina propria, and the nasal-associated lymphoid tissue, with minimal involvement of the transitional epithelium. The lesions were most severe on the septum and the medial aspect of the nasoturbinates. Viral antigen, located in the respiratory epithelium of affected regions at days 1 and 2 PI, was associated with neutrophilic infiltration and epithelial necrosis and erosion. At day 4 PI, an infiltrate of lymphocytes, macrophages, and fewer neutrophils was present, often accompanied by epithelial regeneration. Changes in the nasal-associated lymphoid tissue were evaluated using morphometric analysis and consisted of hyperplasia (days 4 to 7 PI) followed by progressive involution (days 14 to 28 PI). Mild lesions associated with foci of viral antigen were also observed in the nasal olfactory epithelium on days 1, 2, and 4 PI. The changes observed in the present study indicate the potential value of rat-adapted influenza virus infection as a model of human influenza.