Importance of Fiberoptic Bronchoscopy in Identifying Asthma Phenotypes to Direct Personalized Therapy

Steven E. Lommatzsch; Richard J. Martin; James T. Good Jr

Disclosures

Curr Opin Pulm Med. 2013;19(1):42-48. 

In This Article

Abstract and Introduction

Abstract

Purpose of review This review summarizes the phenotyping of refractory asthma with an emphasis on how direct bronchoscopic observation and analysis of bronchoalveolar lavage (BAL), biopsy, and brushings of the airways helps direct specific personalized therapy. Additional testing used in phenotyping asthmatic patients is reviewed.

Recent findings Several studies and publications over the past decade have emphasized the importance of phenotyping refractory asthmatic patients to offer a better understanding of the pathobiology of disease. Bronchoscopy is a useful tool in phenotyping asthma with objective data obtained from BAL, endobronchial biopsy, and brushings. Phenotyping asthma with bronchoscopy affords personalized and successful therapy.

Summary By using fiberoptic bronchoscopy, specific asthma phenotypes can be identified: laryngopharyngeal reflux with silent aspiration; subacute bacterial infection; tissue eosinophilia; a combination of two or three of these; and nonspecific. Identifying these phenotypes and personalizing therapy with bronchoscopy leads to improved outcomes.

Introduction

Asthma is frequently defined as a single disease characterized by reversible airflow obstruction, airway inflammation, and bronchial hyperresponsiveness associated with symptoms of cough, wheeze, chest tightness, and dyspnea. Research has grown rapidly to expand the understanding of inflammation leading to this syndrome of varying airway responses. As different mechanisms have been revealed, the characterization of asthma has evolved into a more heterogeneous process leading to airway changes. Asthma appears to be a group of multiple phenotypes that represent different causes of inflammation or airway responses, and has been suggested to be a group of distinct processes.[1]

Asthma phenotypes have been defined and redefined based on the observable clinical symptoms, triggers, severity, and general inflammatory properties, but often the descriptions do not incorporate a direct relationship of the cause of these findings to the pathophysiology of the disease process. The term 'endotype' is a description of the characteristics of a phenotype along with the specific biological pathway causing the pathologic changes in the airways.[1,2] The use of biomarkers, genetic analysis, sputum samples, bronchoalveolar lavage (BAL), and airway biopsies has been utilized to understand the underlying pathophysiologic mechanisms of asthma in attempts to characterize different phenotypes and related endotypes.[2] However, most of the described asthma phenotypes have not led to significant improvements in specific or directed therapy.

Bronchoscopy has been used for years by researchers to gain further understanding into airway diseases. Past and recent studies have demonstrated the safety of bronchoscopy in studying even severe asthma patients.[3,4] A coordinated analysis from a variety of data samples would appear to be the best way to elucidate a pathologic process. The use of serum, sputum, and airway samples each provide unique and valuable insight into characterizing the multiple aspects of asthma phenotypes. A recent bronchoscopic study[5] in obese asthmatic patients identified several inflammatory mediators [interleukin (IL)-5, IL-8, IL-10, interferon γ, and tumor necrosis factor α] that may contribute to airway inflammation in this 'phenotype'. However, these findings did not help direct current patient therapy. The purpose of identifying asthma phenotypes is to provide specific individual-directed therapy that leads to improved clinical responses. A recent study by Good et al.[6] demonstrated the utility of bronchoscopy in helping to guide therapy in refractory asthmatic patients by specifically defining phenotypes. This method of phenotyping led to significant improvements in asthma control and lung function through the use of personalized therapy.

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