2 Proteins Suggested as Lung Disease Biomarkers in Diffuse Systemic Sclerosis
Increased levels of two proteins produced during acute inflammation can help predict pulmonary involvement in patients with diffuse systemic sclerosis, a study shows.
Patients with diffuse systemic sclerosis who also have developed lung disease were found to have significantly higher levels of C-reactive protein (CRP) and serum amyloid A (SAA) in the blood.
The finding was reported in the study “High acute phase protein levels correlate with pulmonary and skin involvement in patients with diffuse systemic sclerosis,” published in the Journal of International Medical Research.
CRP and SAA are two proteins that are produced naturally in the body during inflammation and in response to acute situations, such as infections. In autoimmunity, these proteins have been linked to disease severity and progression.
In the study, Polish researchers aimed to investigate the involvement of both CRP and SAA in diffuse systemic sclerosis, also known as diffuse systemic scleroderma.
The study enrolled 33 patients with diffuse systemic sclerosis and 15 healthy volunteers. Patients had the disease from three months up to 191 months (almost 16 years); 18 of the patients were at early disease stage while 15 had more advanced disease. Approximately 36 percent of patients already had developed lung disease at the time of the study.
Analysis of CRP and SAA levels in the blood revealed they both were elevated significantly in patients compared to healthy people used as controls for the study. Diffuse systemic sclerosis patients had about three or five times more SAA and CRP, respectively. This increase was found to be independent of disease stage or duration. No major differences were detected between early- and late-stage patients, or with more or less than three years of disease duration.
When researchers looked for the levels of these proteins in the subgroup of patients with lung disease, they found they were even higher. They had 1.3 and 6.1 times higher levels of SAA and CRP compared to patients without lung disease.
In fact, the increased levels of both proteins were found to be significantly correlated with a decreased lung function.
The levels of CRP, but not of SAA, also were found to be significantly connected to greater skin involvement, as determined by the modified Rodnan skin score.
Collectively, these findings suggest that both inflammatory proteins can be biomarkers of the underlying mechanism of systemic sclerosis and associated lung disease. They also may be active contributors for disease progression.
“Further studies are needed to evaluate the role of CRP and SAA in patients with dSSc [diffuse systemic sclerosis] and their impact on clinical and other biomarker correlations,” the researchers wrote.