*3.2. Clinical Characteristics and Airway Remodeling in Asthma Patients*

Among the 74 asthma patients included, 29 (39%) had severe disease (Table 2), and 37 (50%) had persistent airflow limitation. The median duration of asthma was 10 years, and about half of the patients were atopic. Only one-third of the subjects enrolled evaluated their asthma as well-controlled based on the asthma control test, while one-fourth had a very poorly controlled disease.

Based on the BAL cell differential count data (Table 2), 26% of asthma patients showed eosinophilic inflammation (that is, ≥2% of eosinophils), including 15% with neutrophil admixture (mixed inflammation); 28% had a pure neutrophilic (≥4% neutrophils), and 46% had a pauci-granulocytic variant.

In the Supplementary Materials, we provided the clinical characteristics of asthma patients with the division into mild, moderate, and severe disease staging.


**Table 2.** Clinical characteristics of asthmatic patients, including airway imaging and histo(cyto)logy.

dian and 0.25–0.75 quartiles, or mean and standard deviation, as appropriate. Abbreviations and references: BAL—bronchoalveolar lavage fluid, FEV1—forced expiratory volume in one second, GINA—Global Initiative for Asthma, L—liter, VC—vital capacity; § asthma symptom control (assessed based on Asthma Control Test results); # BAL cell differential data available in 67 asthma subjects; † BAL fluid levels of interleukin (IL)-4, IL-5, IL-10, and IL-17A and interferon γ were below the detection threshold (data not shown); ¥ RBM available in 45 asthma subjects.

Table 2 also summarizes essential measures of structural airway remodeling, as evidenced by CT imaging and airway biopsy specimens. Unfortunately, in this study, we did not collect those data in the control group. However, compared to control datasets in our previous report [27], which was conducted by using a similar methodology, CT imaging parameters suggest mild-to-moderate changes in airway geometry (10% difference on average, *p* < 0.05), whereas RBM thickness is ~30% thicker in asthmatics compared to controls (*p* < 0.001). In Figure 1, we depict representative pictures of RBM measures in control and asthma individuals.

**Figure 1.** Representative pictures of endobronchial biopsy specimens in a control subject (**a**) and asthma patient (**b**); the reticular basement membrane (RBM) is thicker in asthma. Other abbreviations: Epi—epithelium, Sub—subepithelium.

As expected, the referenced airway CT measures in RB1 and RB10 correlated well with each other (e.g., WTR: r = 0.4, *p* < 0.001) and with spirometry values (e.g., FEV1:r= −0.34, *p* = 0.007 and r = −0.3, *p* = 0.01, for WTR of RB1 and RB10, respectively).

At the same time, neither CT nor spirometry values were linked with RBM thickness.
