Author reply

摘要

We read with great interest the letter by O'Reilly analysing serum amyloid A (SAA) in patients affected by systemic sclerosis (SSc) with and without interstitial lung involvement.1 SAA is an acute phase protein mainly produced by the liver in response to pro-inflammatory cyto-kines from activated monocytes. It has recently been measured in biological fluids from patients with different lung diseases including lung cancer, interstitial lung diseases (ILD) such as idiopathic pulmonary fibrosis (IPF) and sarcoidosis, obstructive lung diseases and autoimmune disorders. Lipid metabolism has recently been suggested to be involved in the pathogenesis of ILD because of an imbalance of lipid metabolites (including lipoproteins) reported in IPF patients both in serum and bronchoalveolar lavage fluid.2 SAA has been correlated with prognosis and lung function and has been suggested as a biomarker of fibrotic lung diseases. Our research group reported the highest SAA concentrations in IPF patients compared with other ILD cohorts.