Biomarkers in Different Asthma Phenotypes

Abstract

Asthma is the most common respiratory disease. It has multiple phenotypes thatcan be partially differentiated by measuring the disease’s specific characteristics—biomarkers. The pathogenetic mechanisms are complex, and it is still a challenge to choose suitable biomarkers to adequately stratify patients, which became especially important with the introduction of biologicals in asthma treatment. Usage of biomarkers and an understanding of the underlying pathobiological mechanisms lead to the definition of endotypes. Asthma can be broadly divided into two endotypes, T2-high and T2-low. The right combination of various biomarkers in different phenotypes is under investigation, hoping to help researchers and clinicians in better disease evaluation since theindividual approach and personalized medicine are imperative. Multiple biomarkers are superior to a single biomarker.

Approaches to studying the pathogenesis of asthma

“…Increased temperature can be a sign of the inflammation that occurs in asthma, but research is still trying to determine a value for the normal range. 1 Patients with asthma have different spectra of exhaled breath condensates than healthy controls, and this approach offers the possibility of identifying underlying endotypes in patients with asthma. 14,15 Studies involving the measurement of leukotrienes, prostanoids, and nitric oxide derived chemicals in exhaled air have the potential to clarify the pathogenesis of chronic asthma, acute exacerbations in asthma, and drug effects in asthma.…”

“…Despite the high prevalence of asthma in the United States and the knowledge that different asthma phenotypes exist, endotypes to explain the varying phenotypes have only recently begun to be a focus of study. 1 A phenotype is defined as a group of patients that present similar clinically observable characteristics, without establishing a direct etiologic relationship with a distinct pathophysiologic mechanism. An endotype, on the other hand, describes a subgroup that shares the same pathophysiologic processes that lead to the development, the progression, and the presentation of a disease.…”

“…3 Currently, there are two generally accepted endotypes of asthma: T-2 high (eosinophilic airway inflammation) and T-2 low (consisting of neutrophilic or paucigranulocytic inflammation). 1,4 T2-high asthma is remarkable for the presence of a high number of type 2 cytokines. These cells produce an inflammatory response which leads to severe bronchospasm.…”

“…It is predominantly mediated by neutrophils and typically has more resistance to steroid treatment. 1,4 Current studies on the pathogenesis of asthma present multiple problems, including but not limited to their invasive nature. Understanding the characteristics of the underlying inflammation requires lung biopsies and/or bronchoalveolar lavage studies.…”

Metabolic Phenotypes in Asthmatic Adults: Relationship with Inflammatory and Clinical Phenotypes and Prognostic Implications

“…Several previously described asthma “phenotypes” have subsequently been proposed as “endotypes”, and examples of these include adult allergic asthma, aspirin-sensitive asthma, late-onset hypereosinophilic asthma, obesity-related asthma, neutrophilic asthma, T2-high or T2-low (non-Th2-high) asthma [ 5 , 85 , 86 ]. In fact, as is the case of T2-high and T2-low asthma, underlying immunopathophysiological mechanisms (involving cytokines) have been identified and there is even effective medication targeted at these mechanisms (e.g., anti-IgE, anti-IL-5, anti-IL-5 receptor or anti-IL4/IL3 receptor α-chain) [ 87 ].…”