Activity of the apoptosis-inducing ligand TRAIL in the blood of patients with chronic obstructive pulmonary disease who had COVID-19

Aim. To assess the serum level of the apoptosis-inducing ligand TRAIL in patients with chronic obstructive pulmonary disease (COPD) 12 months after COVID-19 in relationship to measures of systemic inflammation. Materials and methods. The study included 90 patients aged 46 to 79 years with stable COPD who had experienced COVID-19 (regardless of COPD and COVID-19 severity) 12 months after hospital discharge. The comparison group consisted of 43 patients with stable COPD and no history of COVID-19. The serum TRAIL level was measured by enzymelinked immunosorbent assay using specific antibodies (RayBiotech, Human, USA). Levels of interleukin (IL)-6, IL-10, vascular endothelial growth factor (VEGF) (Vector-Best, Russia), and C-reactive protein (CRP) (Biochemmack, Austria) were determined by direct serological “sandwich-type” assays with mono- and polyclonal antibodies. Results. Twelve months after COVID-19, patients with stable COPD showed intensified apoptosis and systemic inflammation, evidenced by a 33.7% increase in serum TRAIL, 71.3% in IL-6, 57.5% in CRP, and 69.0% in VEGF compared to COPD patients without a history of COVID-19. A strong association was found between TRAIL and IL-10 levels (p < 0.01), a moderate positive correlation was noted with IL-6 (p < 0.05), and a weak correlation with CRP (p > 0.05). Conclusion. This is the first report of significantly higher serum TRAIL activity 12 months after COVID-19 in patients with stable COPD compared to those without a history of COVID-19. TRAIL ligand showed a strong association with systemic inflammation markers (IL-10, IL-6), reflecting apoptosis-dependent mechanisms of inflammation in COPD. Measuring serum TRAIL levels may be useful for comprehensive evaluations of patients with COPD recovering from COVID-19.