Angiogenic T Cells: Potential Biomarkers for the Early Diagnosis of Interstitial Lung Disease in Autoimmune Diseases?

E-Selectin, ICAM-1, and ET-1 Biomarkers Address the Concern of the Challenging Diagnosis of Interstitial Lung Disease in Patients with Autoimmune Diseases

Interstitial lung disease (ILD) constitutes the most critical comorbidity in autoimmune diseases (ADs) and its early diagnosis remains a challenge for clinicians. Accordingly, we evaluated whether E-selectin, ICAM-1, and ET-1, key molecules in endothelial damage, could be useful biomarkers for the detection of AD-ILD+. We recruited patients with rheumatoid arthritis (RA)-ILD+ (n = 21) and systemic sclerosis (SSc)-ILD+ (n = 21). We included comparison groups of patients: RA-ILD- (n = 25), SSc-ILD- (n = 20), and idiopathic pulmonary fibrosis (IPF) (n = 21). Serum levels of these proteins were determined by ELISA. E-selectin, ICAM-1, and ET-1 serum levels were increased in RA-ILD+ and IPF patients in comparison to RA-ILD- patients. Additionally, SSc-ILD+ and IPF patients exhibited higher ICAM-1 levels than those with SSc-ILD-. The ability of E-selectin, ICAM-1, and ET-1 to discriminate RA-ILD+ from RA-ILD- patients, and ICAM-1 to distinguish SSc-ILD+ from SSc-ILD- patients was confirmed using ROC curve analysis. Furthermore, elevated levels of ET-1 and E-selectin correlated with lung function decline in RA-ILD+ and SSc-ILD+ patients, respectively. In conclusion, our findings support the relevant role of E-selectin, ICAM-1, and ET-1 in RA-ILD+ patients as well as of ICAM-1 in SSc-ILD+ patients, constituting potential screening blood biomarkers of ILD in AD. Moreover, this study suggests ET-1 and E-selectin as possible indicators of worsening lung function in RA-ILD+ and SSc-ILD+ patients, respectively.

Endothelin-1 as a Biomarker of Idiopathic Pulmonary Fibrosis and Interstitial Lung Disease Associated with Autoimmune Diseases

The aim of this study was to determine the role of endothelin-1 (ET-1), a molecule involved in multiple vascular and fibrosing abnormalities, as a biomarker of interstitial lung disease (ILD), as well as its use for the differential diagnosis between idiopathic pulmonary fibrosis (IPF) and ILD associated with autoimmune diseases (AD-ILD), using a large and well-defined cohort of patients with ILD. A total of 112 patients with IPF, 91 patients with AD-ILD (28 rheumatoid arthritis (RA), 26 systemic sclerosis, 20 idiopathic inflammatory myositis and 17 interstitial pneumonia with autoimmune features) and 44 healthy controls were included. ET-1 serum levels were determined by enzyme-linked immunosorbent assay. A significant increase in ET-1 levels was found in patients with IPF compared to controls. Likewise, AD-ILD patients also showed higher ET-1 levels than controls when the whole cohort was stratified by the type of AD. Similar ET-1 levels were found in IPF and AD-ILD patients, regardless of the underlying AD. Interestingly, increased ET-1 levels were correlated with worse lung function in IPF and RA-ILD patients. Our study supports that serum ET-1 may be useful as a biomarker of ILD, although it could not help in the differential diagnosis between IPF and AD-ILD. Moreover, ET-1 levels may be associated with ILD severity.

Elevated VCAM-1, MCP-1 and ADMA serum levels related to pulmonary fibrosis of interstitial lung disease associated with rheumatoid arthritis

Introduction: Early diagnosis of interstitial lung disease (ILD) associated with rheumatoid arthritis (RA) constitutes a challenge for the clinicians. Pulmonary vasculopathy is relevant in the development of interstitial lung disease. Accordingly, we aimed to explore the role of vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1) and asymmetric dimethylarginine (ADMA), key molecules in the vasculopathy, as potential biomarkers of pulmonary fibrosis in RA-ILD⁺. Methods: We included 21 RA-ILD⁺ patients and two comparative groups: 25 RA-ILD^- patients and 21 idiopathic pulmonary fibrosis (IPF) patients. Serum levels of the molecules were determined by ELISA, and mRNA expression was quantified by qPCR. Results: VCAM-1, MCP-1 and ADMA serum levels were increased in RA-ILD⁺ patients in relation to RA-ILD^- and IPF patients. Additionally, RA-ILD⁺ patients exhibited increased CCL2 (gene encoding MCP-1) and decreased PRMT1 (gene related to ADMA synthesis) mRNA expression in relation to RA-ILD^- patients. A lower expression of VCAM1, CCL2, and PRMT1 was observed in RA-ILD⁺ patients when compared with those with IPF. Furthermore, MCP-1 serum levels and PRMT1 mRNA expression were positively correlated with RA duration, and ADMA serum levels were positively associated with C-reactive protein in RA-ILD⁺ patients. Conclusion: Our study suggests that VCAM-1, MCP-1 and ADMA could be considered as useful biomarkers to identify ILD in RA patients, as well as to discriminate RA-ILD⁺ from IPF, contributing to the early diagnosis of RA-ILD⁺.