The effect of rhinovirus on airway inflammation in a murine asthma model

Viruses and non-allergen environmental triggers in asthma

Asthma is a complex inflammatory disease with many triggers. The best understood asthma inflammatory pathways involve signals characterized by peripheral eosinophilia and elevated immunoglobulin E levels (called T2-high or allergic asthma), though other asthma phenotypes exist (eg, T2-low or non-allergic asthma, eosinophilic or neutrophilic-predominant). Common triggers that lead to poor asthma control and exacerbations include respiratory viruses, aeroallergens, house dust, molds, and other organic and inorganic substances. Increasingly recognized non-allergen triggers include tobacco smoke, small particulate matter (eg, PM2.5), and volatile organic compounds. The interaction between respiratory viruses and non-allergen asthma triggers is not well understood, though it is likely a connection exists which may lead to asthma development and/or exacerbations. In this paper we describe common respiratory viruses and non-allergen triggers associated with asthma. In addition, we aim to show the possible interactions, and potential synergy, between viruses and non-allergen triggers. Finally, we introduce a new clinical approach that collects exhaled breath condensates to identify metabolomics associated with viruses and non-allergen triggers that may promote the early management of asthma symptoms.

The association between blood eosinophil percent and bacterial infection in acute exacerbation of chronic obstructive pulmonary disease

Introduction: The use of antibiotics is based on the clinician's experience and judgment, and antibiotics may often be overused in the treatment of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Eosinophils have been studied as biomarkers of bacterial infection and prognostic factors in chronic obstructive pulmonary disease and AECOPD. Thus, the purpose of this study was to determine whether eosinophils could be used to determine bacterial infection in AECOPD events. Methods: We retrospectively analyzed the medical records of patients admitted to Korea University Guro Hospital for AECOPD between January 2011 and May 2017. Data pertaining to baseline characteristics, results of previous pulmonary function tests, treatment information during the admission period, and history of pulmonary treatment were collected before admission. Results: A total of 736 AECOPD events were eligible for inclusion and were divided into two groups based on the eosinophil count: those involving eosinophil counts of less than 2% (546 events) and those involving counts of 2% or more (190 events). In univariate analysis, the only bacterial pathogen identification events and bacterial-viral pathogen co-identification events were significantly more frequent in the group with eosinophil counts of less than 2% (P=0.010 and P=0.001, respectively). In logistic regression analysis, the rates of only bacterial pathogen identification [odds ratios =1.744; 95% confidence interval, 1.107-2.749; P=0.017] and bacterial-viral pathogen co-identification [odds ratios=2.075; 95% confidence interval, 1.081-3.984; P=0.028] were higher in the group with eosinophil count less than 2%. Conclusion: In conclusion, eosinophil counts of less than 2% are potential indicators of a bacterial infection in AECOPD events. Eosinophils could thus serve as a reference for the use of antibiotics in AECOPD treatment.

Neonatal Immunity, Respiratory Virus Infections, and the Development of Asthma

Infants are exposed to a wide range of potential pathogens in the first months of life. Although maternal antibodies acquired transplacentally protect full-term neonates from many systemic pathogens, infections at mucosal surfaces still occur with great frequency, causing significant morbidity and mortality. At least part of this elevated risk is attributable to the neonatal immune system that tends to favor T regulatory and Th2 type responses when microbes are first encountered. Early-life infection with respiratory viruses is of particular interest because such exposures can disrupt normal lung development and increase the risk of chronic respiratory conditions, such as asthma. The immunologic mechanisms that underlie neonatal host-virus interactions that contribute to the subsequent development of asthma have not yet been fully defined. The goals of this review are (1) to outline the differences between the neonatal and adult immune systems and (2) to present murine and human data that support the hypothesis that early-life interactions between the immune system and respiratory viruses can create a lung environment conducive to the development of asthma.

Antiviral activity of gemcitabine against human rhinovirus in vitro and in vivo

Rhinovirus, a major causative agent of the common cold, is associated with exacerbation of asthma and chronic obstructive pulmonary disease. Currently, there is no antiviral treatment or vaccine for human rhinovirus (HRV). Gemcitabine (2',2'-difluorodeoxycytidine, dFdC) is a deoxycytidine analog with antiviral activity against rhinovirus, as well as enterovirus 71, in vitro. However, the antiviral effects of gemcitabine in vivo have not been investigated. In the current study, we assessed whether gemcitabine mediated antiviral effects in the murine HRV infection model. Intranasal administration of gemcitabine significantly lowered pulmonary viral load and inflammation by decreasing proinflammatory cytokines, including TNF-α and IL-1β, and reduction in the number of lung-infiltrating lymphocytes. Interestingly, we found that the addition of UTP and CTP significantly attenuated the antiviral activity of gemcitabine. Thus the limitation of UTP and CTP by the addition of gemcitabine may inhibit the viral RNA synthesis. These results suggest that gemcitabine, an antineoplastic drug, can be repositioned as an antiviral drug to inhibit HRV infection.

Rhinovirus infection in murine chronic allergic rhinosinusitis model

BACKGROUND

Patients with chronic rhinosinusitis (CRS) commonly experience aggravation of their symptoms after viral upper respiratory infection (URI). Rhinovirus (RV) is the most common URI-causing virus. However, there is a lack of a mouse model of RV infection and in vivo studies investigating the effect of RV infection on CRS.

METHODS

A mouse model of chronic allergic rhinosinusitis (CARS) was established by sensitizing to ovalbumin (OVA) through intraperitoneal injection followed by nasal challenges with OVA for 5 weeks. Both control and CARS mice were euthanized at 48 hours after infection with minor group RV serotype 1B (RV1B). Sinonasal complex samples were evaluated histologically; and interleukin (IL)-6, macrophage inflammatory protein (MIP)-2, IL-13, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ were measured in the nasal lavage fluid. The RV1B-infected areas in control and CARS mice were identified using immunofluorescence.

RESULTS

In the infected control mice group, RV1B increased secretory hyperplasia in the sinonasal mucosa and the production of proinflammatory cytokines including INF-γ, MIP-2, and IL-13. Immunohistochemical analysis of nasal mucosa from RV1B-infected mice presented abundant RV1B staining, which was distributed between the epithelium and the lamina propria. In the CARS group, the RV1B-infected area per unit was significantly higher than that in control mice. However, RV1B infection neither increased the proinflammatory cytokine secretion nor worsened the histology significantly.

CONCLUSION

We successfully established a mouse model of upper airway RV infection by nasal inoculation with RV1B. Although there was histologically-proven increased RV infection in the CARS model, the infection did not intensify sinonasal inflammation.

Therapeutic and prophylactic activity of itraconazole against human rhinovirus infection in a murine model

Human rhinovirus (HRV) is the most common viral infectious agent in humans and is the predominant cause of the common cold. There is a need for appropriate vaccines or therapeutic agents to treat HRV infection. In this study, we investigated whether itraconazole (ICZ) can protect cells from HRV-induced cytotoxicity. Replication of HRV1B was reduced by ICZ treatment in the lungs of HRV1B- as compared to vehicle-treated mice. The numbers of immune cells, including granulocytes and monocytes, were reduced in bronchoalveolar lavage fluid (BALF) by ICZ administration after HRV1B infection, corresponding to decreased pro-inflammatory cytokine and chemokine levels in BALF. A histological analysis of lung tissue showed that ICZ suppressed inflammation caused by HRV1B infection. Interestingly, pretreatment of mice with ICZ in the form of a nasal spray had potent prophylactic antiviral activity. Cholesterol accumulation in the plasma membrane was observed upon HRV infection; ICZ blocked cholesterol trafficking to the plasma membrane, as well as resulted in its accumulation in subcellular compartments near the nucleus. These findings suggest that ICZ is a potential antiviral agent for the treatment of HRV infection, which can be adopted preventatively as well as therapeutically.

Mouse models of acute exacerbations of allergic asthma

Most of the healthcare costs associated with asthma relate to emergency department visits and hospitalizations because of acute exacerbations of underlying chronic disease. Development of appropriate animal models of acute exacerbations of asthma is a necessary prerequisite for understanding pathophysiological mechanisms and assessing potential novel therapeutic approaches. Most such models have been developed using mice. Relatively few mouse models attempt to simulate the acute-on-chronic disease that characterizes human asthma exacerbations. Instead, many reported models involve relatively short-term challenge with an antigen to which animals are sensitized, followed closely by an unrelated triggering agent, so are better described as models of potentiation of acute allergic inflammation. Triggers for experimental models of asthma exacerbations include (i) challenge with high levels of the sensitizing allergen (ii) infection by viruses or fungi, or challenge with components of these microorganisms (iii) exposure to environmental pollutants. In this review, we examine the strengths and weaknesses of published mouse models, their application for investigation of novel treatments and potential future developments.