Study Background:

This research focuses on finding reliable blood biomarkers to diagnose Interstitial Lung Disease (ILD) in patients with autoimmune diseases, specifically rheumatoid arthritis (RA) and systemic sclerosis (SSc). ILD is a serious complication in these diseases and early detection is crucial to prevent lung damage.

Key Biomarkers Investigated:

1. E-selectin
2. ICAM-1
3. ET-1

These molecules are associated with endothelial damage, which plays a significant role in developing lung fibrosis.

Study Methods:
The study involved:

• 21 RA patients with ILD (RA-ILD+)
• 21 SSc patients with ILD (SSc-ILD+)
• Comparative groups:
• 25 RA patients without ILD (RA-ILD–)
• 20 SSc patients without ILD (SSc-ILD–)
• 21 patients with idiopathic pulmonary fibrosis (IPF)

Blood levels of E-selectin, ICAM-1, and ET-1 were measured using ELISA tests.

Key Findings:

• RA-ILD+ patients had significantly higher levels of E-selectin, ICAM-1, and ET-1 compared to RA-ILD– patients.
• ROC curve analysis confirmed the ability of these biomarkers to differentiate between RA-ILD+ and RA-ILD– patients.
• E-selectin: AUC 0.78
• ICAM-1: AUC 0.72
• ET-1: AUC 0.77
• Specific cutoff values for optimal sensitivity and specificity were identified:
• E-selectin: 74.56 ng/mL
• ICAM-1: 451.70 ng/mL
• ET-1: 1.02 pg/mL
• SSc-ILD+ patients also had higher ICAM-1 levels compared to SSc-ILD– patients, with an AUC of 0.79 and a cutoff value of 484.70 ng/mL.
• Negative correlations were found between ET-1 levels and lung function (FVC and FEV1) in RA-ILD+ patients, and between E-selectin levels and lung function (FVC, FEV1, and DLCO) in SSc-ILD+ patients.

E-selectin, ICAM-1, and ET-1 can potentially serve as blood biomarkers for early detection of ILD in RA and SSc patients. Additionally, ET-1 and E-selectin may indicate worsening lung function in these patients, aiding in better management and treatment of ILD.