Page 117 - Škrgat, Sabina, ed. 2022. Severe Asthma - Basic and Clinical Views. Koper: University of Primorska Press. Severe Asthma Forum, 1
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relation to the types of cellular airway in- patients for targeted type 2 asthma treatment. 117
filtration. Although the stratification of asth- Blood eosinophils due to its high predictive
ma phenotypes by blood eosinophils is rela- value of ≥300/µL is used as an initial bio- eosinophilic and allergic asthma phenotype and therapeutic possibilities
tively easy, it does not allow a deeper/more marker to predict treatment responses target-
detailed identification of clinical phenotypes. ing IL-4, IL-5, and IL-13.15,23
Therefore, cluster analysis is used to identify
groups of patients with asthma who share spe- Consistent with its central role in the de-
cific clinical characteristics, e.g., cluster anal- velopment of allergic asthma, serum value
ysis using clinical characteristics of patients of IgE is a good biomarker of an atopic sta-
such as asthma onset age, lung function value, tus. Serum IgE levels are positively correlated
bronchodilator reversibility and demograph- with the severity of asthma in adults and chil-
ics. The Severe Asthma Research Program dren. Serum total IgE is used to predict re-
(SARP) identified five clinical groups of asth- sponses to anti-IgE therapy, but is not useful
ma in adults, in which four groups showed eo- for monitoring responses.15,24
sinophilia of varying degrees.18
The role of periostin and FENO in tai-
In order to identify severe asthma phe- loring the biologic therapy targeting type 2
notypes, ADEPT study19 was conducted asthma is less clear. Periostin is an extracellu-
and identified four clusters of asthma, which lar matrix protein secreted from IL-4 and IL-
were also present in the UBIOPRED study.20 13-induced airway epithelial cells, but has not
Three of these four asthma clusters were asso- been shown to be a good biomarker in routine
ciated with eosinophilia. use. Changes in FENO after dupilumab ther-
apy (anti IL-13/IL-4) correlate well with im-
In the evolution of knowledge of clinical provement in FEV1.25-27
phenotypes, Saly Wenzel and her co-workers
have made a definition as follows: early-on- Allergic and Eosinophilic Asthma
set allergic, late-onset eosinophilic and exer- Phenotype
cise-induced phenotype, all identified by bio-
markers of Th2 asthma; and three phenotypes The decision to choose biological therapy is
of non-Th2 asthma, obesity- related, neutro- preceded by a process of asthma phenotyping
philic and asthma in smokers. No biomarkers based on the identification of clinical charac-
of non-Th2 asthma have been identified so far teristics and driving mechanisms of inflam-
as a basis for new biologics and markers of a mation. Biomarkers help us in the rational
positive response to that treatment.21,15 This is choice of biological and predict a positive re-
due to the lack of knowledge of the non-T2- sponse of patients to the selected treatment:
High (T2-Low) immune response associat-
ed with the activation of Th1 and/or Th17 1. The “Early-onset allergic asthma” phe-
cells and IL-17, IL-8 cytokines and the mech- notype usually begins before the age of
anisms underlying the recruitment and main- 12. Triggers are allergens and other al-
tenance of neutrophilic inflammation.22 lergic diseases, and/or a positive fam-
ily history is associated too. Specific
Biological Agents Targeting Airway biomarkers are elevated total IgE, spe-
Inflammation in Asthma: cific IgE and cytokines of T2 inflamma-
The Rational Choice tion.9,10,13, 21

Biomarkers can warn of the severity of the dis- 2. In the “Late-onset persistent eosinophil-
ease and predict the response to a particular ic asthma” phenotype, symptoms begin
treatment. Some of the biomarkers, alone or in adulthood, often are associated with
in combination, will be useful in ­identifying chronic sinusitis and nasal polyposis. Bi-
omarkers of this phenotype are elevat-
ed eosinophils of peripheral blood and
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