Experimental rhinovirus infection induces an antiviral response in circulating B cells which is dysregulated in patients with asthma

Asthma Pathogenesis: Phenotypes, Therapies, and Gaps: Summary of the Aspen Lung Conference 2023

Although substantial progress has been made in our understanding of asthma pathogenesis and phenotypes over the nearly 60-year history of the Aspen Lung Conferences on asthma, many ongoing challenges exist in our understanding of the clinical and molecular heterogeneity of the disease and an individual patient's response to therapy. This report summarizes the proceedings of the 2023 Aspen Lung Conference, which was organized to review the clinical and molecular heterogeneity of asthma and to better understand the impact of genetic, environmental, cellular, and molecular influences on disease susceptibility, heterogeneity, and severity. The goals of the conference were to review new information about asthma phenotypes, cellular processes, and cellular signatures underlying disease heterogeneity and treatment response. The report concludes with ongoing gaps in our understanding of asthma pathobiology and provides some recommendations for future research to better understand the clinical and basic mechanisms underlying disease heterogeneity in asthma and to advance the development of new treatments for this growing public health problem.

Viral infections causing asthma exacerbations in the age of biologics and the COVID-19 pandemic

PURPOSE OF REVIEW

Asthma exacerbations are associated with substantial symptom burden and healthcare costs. Viral infections are the most common identified cause of asthma exacerbations. The epidemiology of viral respiratory infections has undergone a significant evolution during the COVID-19 pandemic. The relationship between viruses and asthmatic hosts has long been recognized but it is still incompletely understood. The use of newly approved asthma biologics has helped us understand this interaction better.

RECENT FINDINGS

We review recent updates on the interaction between asthma and respiratory viruses, and we address how biologics and immunotherapies could affect this relationship by altering the respiratory mucosa cytokine milieu. By exploring the evolving epidemiological landscape of viral infections during the different phases of the COVID-19 pandemic, we emphasize the early post-pandemic stage, where a resurgence of pre-pandemic viruses with atypical seasonality patterns occurred. Finally, we discuss the newly developed RSV and SARS-CoV-2 vaccines and how they reduce respiratory infections.

SUMMARY

Characterizing how respiratory viruses interact with asthmatic hosts will allow us to identify tailored therapies to reduce the burden of asthma exacerbations. New vaccination strategies are likely to shape the future viral asthma exacerbation landscape.

Development of a nomogram to estimate the risk of community-acquired pneumonia in adults with acute asthma exacerbations

OBJECTIVE

The aim of this study is to investigate the clinical characteristics of acute asthma exacerbations (AEs) with community-acquired pneumonia (CAP) in adults and establish a CAP prediction model for hospitalized patients with AEs.

METHODS

We retrospectively collected clinical data from 308 patients admitted to Beijing Luhe Hospital, Capital Medical University, for AEs from December 2017 to August 2021. The patients were divided into CAP and non-CAP groups based on whether they had CAP. We used the Lasso regression technique and multivariate logistic regression analysis to select optimal predictors. We then developed a predictive nomogram based on the optimal predictors. The bootstrap method was used for internal validation. We used the area under the receiver operating characteristic curve (AUC), calibration curve, and decision curve analysis (DCA) to assess the nomogram's discrimination, accuracy, and clinical practicability.

RESULTS

The prevalence of CAP was 21% (65/308) among 308 patients hospitalized for AEs. Independent predictors of CAP in patients hospitalized with an AE (P < 0.05) were C-reactive protein > 10 mg/L, fibrinogen > 4 g/L, leukocytes > 10 × 109 /L, fever, use of systemic corticosteroids before admission, and early-onset asthma. The AUC of the nomogram was 0.813 (95% CI: 0.753-0.872). The concordance index of internal validation was 0.794. The calibration curve was satisfactorily consistent with the diagonal line. The DCA indicated that the nomogram provided a higher clinical net benefit when the threshold probability of patients was 3% to 89%.

CONCLUSIONS

The nomogram performed well in predicting the risk of CAP in hospitalized patients with AEs, thereby providing rapid guidance for clinical decision-making.

B cells: The many facets of B cells in allergic diseases

B cells play a key role in our immune system through their ability to produce antibodies, suppress a proinflammatory state, and contribute to central immune tolerance. We aim to provide an in-depth knowledge of the molecular biology of B cells, including their origin, developmental process, types and subsets, and functions. In allergic diseases, B cells are well known to induce and maintain immune tolerance through the production of suppressor cytokines such as IL-10. Similarly, B cells protect against viral infections such as severe acute respiratory syndrome coronavirus 2 that caused the recent coronavirus disease 2019 pandemic. Considering the unique and multifaceted functions of B cells, we hereby provide a comprehensive overview of the current knowledge of B-cell biology and its clinical applications in allergic diseases, organ transplantation, and cancer.

Update on virus-induced asthma exacerbations

INTRODUCTION

Viral infections are common triggers for asthma exacerbation. Subjects with asthma are more susceptible to viral infections and develop more severe or long-lasting lower respiratory tract symptoms than healthy individuals owing to impaired immune responses. Of the many viruses associated with asthma exacerbation, rhinovirus (RV) is the most frequently identified virus in both adults and children.

AREAS COVERED

We reviewed epidemiological and clinical links and mechanistic studies on virus-associated asthma exacerbations. We included sections on severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), the latest evidence of coronavirus disease 2019 (COVID-19) in asthma patients, and past and future searches for therapeutic and prevention targets.

EXPERT OPINION

Early treatment or prevention of viral infections might significantly reduce the rate of asthma exacerbation, which is one of the key points of disease management. Although it is hypothetically possible nowadays to interfere with every step of the infectious cycle of respiratory tract viruses, vaccination development has provided some of the most encouraging results. Future research should proceed toward the development of a wider spectrum of vaccines to achieve a better quality of life for patients with asthma and to reduce the economic burden on the healthcare system.

New Data on Anti-Inflammatory and Wound Healing Potential of Transgenic Senna obtusifolia Hairy Roots: In Vitro Studies

Asthma is an inflammatory disease whose etiology remains unclear. Its characteristics encompass a wide range of clinical symptoms, inflammatory processes, and reactions to standard therapies. Plants produce a range of constitutive products and secondary metabolites that may have therapeutic abilities. The aim of this study was to determine the effects of Senna obtusifolia transgenic hairy root extracts on virus-induced airway remodeling conditions. Three cell lines were incubated with extracts from transformed (SOA4) and transgenic (SOPSS2, with overexpression of the gene encoding squalene synthase 1) hairy roots of Senna obtusifolia in cell lines undergoing human rhinovirus-16 (HRV-16) infection. The effects of the extracts on the inflammatory process were determined based on the expression of inflammatory cytokines (IL-8, TNF-α, IL-1α and IFN-γ) and total thiol content. The transgenic Senna obtusifolia root extract reduced virus-induced expression of TNF, IL-8 and IL-1 in WI-38 and NHBE cells. The SOPSS2 extract reduced IL-1 expression only in lung epithelial cells. Both tested extracts significantly increased the concentration of thiol groups in epithelial lung cells. In addition, the SOPPS2 hairy root extract yielded a positive result in the scratch test. SOA4 and SOPPS2 Senna obtusifolia hairy root extracts demonstrated anti-inflammatory effects or wound healing activity. The SOPSS2 extract had stronger biological properties, which may result from a higher content of bioactive secondary metabolites.

The role of hypoxia in the pathophysiology of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal cavity characterized by excessive nasal mucus secretion and nasal congestion. The development of CRS is related to pathological mechanisms induced by hypoxia. Under hypoxic conditions, the stable expression of both Hypoxia inducible factor-1 (HIF-1) α and HIF-2α are involved in the immune response and inflammatory pathways of CRS. The imbalance in the composition of nasal microbiota may affect the hypoxic state of CRS and perpetuate existing inflammation. Hypoxia affects the differentiation of nasal epithelial cells such as ciliated cells and goblet cells, induces fibroblast proliferation, and leads to epithelial-mesenchymal transition (EMT) and tissue remodeling. Hypoxia also affects the proliferation and differentiation of macrophages, eosinophils, basophils, and mast cells in sinonasal mucosa, and thus influences the inflammatory state of CRS by regulating T cells and B cells. Given the multifactorial nature in which HIF is linked to CRS, this study aims to elucidate the effect of hypoxia on the pathogenic mechanisms of CRS.

Rhinovirus-Induced Cytokine Alterations With Potential Implications in Asthma Exacerbations: A Systematic Review and Meta-Analysis

Background

Rhinovirus (RV) infections are a major cause of asthma exacerbations. Unlike other respiratory viruses, RV causes minimal cytotoxic effects on airway epithelial cells and cytokines play a critical role in its pathogenesis. However, previous findings on RV-induced cytokine responses were largely inconsistent. Thus, this study sought to identify the cytokine/chemokine profiles induced by RV infection and their correlations with airway inflammatory responses and/or respiratory symptoms using systematic review, and to determine whether a quantitative difference exists in cytokine levels between asthmatic and healthy individuals via meta-analysis.

Methods

Relevant articles were obtained from PubMed, Scopus, and ScienceDirect databases. Studies that compared RV-induced cytokine responses between asthmatic and healthy individuals were included in the systematic review, and their findings were categorized based on the study designs, which were ex vivo primary bronchial epithelial cells (PBECs), ex vivo peripheral blood mononuclear cells (PBMCs), and human experimental studies. Data on cytokine levels were also extracted and analyzed using Review Manager 5.4.

Results

Thirty-four articles were included in the systematic review, with 18 of these further subjected to meta-analysis. Several studies reported the correlations between the levels of cytokines, such as IL-8, IL-4, IL-5, and IL-13, and respiratory symptoms. Evidence suggests that IL-25 and IL-33 may be the cytokines that promote type 2 inflammation in asthmatics after RV infection. Besides that, a meta-analysis revealed that PBECs from children with atopic asthma produced significantly lower levels of IFN-β [Effect size (ES): -0.84, p = 0.030] and IFN-λ (ES: -1.00, p = 0.002), and PBECs from adult atopic asthmatics produced significantly lower levels of IFN-β (ES: -0.68, p = 0.009), compared to healthy subjects after RV infection. A trend towards a deficient production of IFN-γ (ES: -0.56, p = 0.060) in PBMCs from adult atopic asthmatics was observed. In lower airways, asthmatics also had significantly lower baseline IL-15 (ES: -0.69, p = 0.020) levels.

Conclusion

Overall, RV-induced asthma exacerbations are potentially caused by an imbalance between Th1 and Th2 cytokines, which may be contributed by defective innate immune responses at cellular levels. Exogenous IFNs delivery may be beneficial as a prophylactic approach for RV-induced asthma exacerbations.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=184119, identifier CRD42020184119.

Rhinovirus Infections and Their Roles in Asthma: Etiology and Exacerbations

Rhinovirus infections can cause wheezing illnesses in all age groups. In preschool children, rhinovirus infections frequently initiate acute wheezing illnesses. Children who wheeze with rhinoviruses are at increased risk to go on to develop asthma. Once asthma is established, rhinovirus infections are potent triggers for acute airway obstruction and exacerbations in children and adults. Paradoxically, for most individuals, rhinovirus infections commonly cause cold symptoms with little or no involvement of the lower airways. This paradox has led investigators to identify specific risk factors and mechanisms for rhinovirus wheezing, and this review will outline progress in 3 main areas. First, the 3 species of rhinoviruses have different patterns of infection and virulence. Second, personal factors such as lung function and immunity influence lower respiratory outcomes of rhinovirus infection. The mucosal immune response is critical, and the quality of the interferon response and allergic inflammation interacts to determine the risk for rhinovirus wheezing. Finally, rhinovirus infections can promote pathogen-dominated airway microbiota that increase the risk for wheezing. Although specific antivirals for rhinovirus are still not available, identifying risk factors for wheezing illnesses has provided several other potential targets and strategies for reducing the risk of rhinovirus-induced wheezing and exacerbations of asthma.