Cardiotrophin-1 as a predictor of critical COVID-19, mortality, and persistence of pulmonary fibrosis after the acute phase of infection.

Pulmonary fibrosis remains a long-term complication in some COVID-19 recovered patients, particularly in those who suffered from severe disease. Cardiotrophin-1 (CT-1) is an antiapoptotic cytokine related with the progression of fibrotic disease in heart and kidney. This study examines the association between CT-1 plasma levels, COVID-19 severity, and post-COVID pulmonary fibrosis. CT-1 levels were analyzed in patients with asymptomatic/mild (n = 33), severe (n = 39), and critical (n = 57) COVID-19, as well as in those with post-COVID pulmonary fibrosis. Elevated CT-1 levels were associated with a higher risk of severe disease, mortality, and persistent pulmonary fibrosis even a year after discharge. Furthermore, CT-1 was associated with non-COVID-19-related pulmonary fibrosis, suggesting a broader role of this cytokine in chronic lung diseases. These findings propose CT-1 as a potential biomarker and therapeutic target for pulmonary fibrosis and provide new insights for its role in chronic respiratory conditions, such as idiopathic pulmonary fibrosis (IPF), post-COVID interstitial lung disease or chronic hypersensitivity pneumonitis.