Introduction: Asthma is a heterogeneous disease; therefore, it is believed that biologically active substances involved in the pathogenesis of asthma could be used as biomarkers for recognizing asthma phenotype. We hypothesized that inflammatory and blood oxidative stress markers, extracellular matrix proteinases and degradation products could be used as potential biomarkers.

Aim: To investigate the circulating I C-telopeptide of Type I collagen (ICTP), Autotaxin (ATX), soluble interleukin 5 receptor subunit alpha (sIL-5Rα), and thioredoxin-1 (TRX1) as serological biomarkers in allergic and non-allergic asthma.

Research methods. We included 10 severe non-allergic eosinophil asthma (SNEA) 10 steroid-naïve allergic asthma (AA) patients, and 10 healthy control subjects (HS). Fractional exhaled nitric oxide (FeNO) analysis was performed with electrochemical assay (NIOX VERO®, Circassia, UK). Blood levels of selected analytes were measured by the enzyme-linked immunosorbent assay (ELISA).

Results: In the patients with AA, sIL-5Rα and TRX1 levels were increased compared to SNEA and HS (p<0.05), while ICTP levels were found significantly decreased (p<0.05); moreover, blood sIL-5Rα concentration significantly correlates with FeNO levels, p<0.05, r = 0.61. ATX level in SNEA group was significantly increased compared with HS (p<0.05), while blood levels of TRX1 was decreased compared to AA and HS; moreover, it significantly correlates with SNEA patients FeNO levels, p<0.05, r = -0.65.

Conclusions: Combination of FeNO levels with decreased blood levels of TRX1 in SNEA patients and elevated blood sIL-5Rα levels in AA patients might act as biomarkers for phenotype identification.