Serum amyloid A is a marker for pulmonary involvement in systemic sclerosis

Area of Science:

• Rheumatology
• Immunology
• Pulmonology

Background:

• Systemic sclerosis (SSc) involves prominent, yet poorly understood, inflammation in early disease stages.
• Serum amyloid A (SAA) is an acute phase protein and a marker of inflammation.

Purpose of the Study:

• To investigate circulating SAA levels, clinical correlations, and biological effects in SSc patients.
• To explore SAA's role in SSc, particularly its association with pulmonary involvement.

Main Methods:

• Multiplex assays were used to measure serum SAA levels in 129 SSc patients and 98 healthy controls.
• Correlations between SAA levels and clinical/laboratory features were analyzed.
• Ex vivo studies examined SAA's effects on human pulmonary fibroblasts.

Main Results:

• Elevated SAA levels were detected in 25% of SSc patients, predominantly in early diffuse cutaneous disease.
• Higher SAA levels correlated with reduced lung function (forced vital capacity, diffusion capacity) and increased dyspnea.
• SAA stimulation of lung fibroblasts increased IL-6 and IL-8 production.

Conclusions:

• Elevated serum SAA is associated with early diffuse cutaneous SSc and correlates with pulmonary involvement.
• SAA directly stimulates cytokine production in lung fibroblasts, suggesting a link to SSc-related lung disease.
• SAA may serve as a potential biomarker for pulmonary complications in SSc.