Role of serum AGE/RAGEs in the differential diagnosis of pulmonary fibrosis

Abstract

Background: Previous reports showed an imbalance of the soluble receptor for advanced glycation end-products (sRAGE), an immunoglobulin implicated in the maintenance of alveolar structures, with its ligand (AGE), in lung samples from idiopathic pulmonary fibrosis (IPF). The finding of a non-invasive serum biomarker would help in the early diagnosis and prognosis of IPF and would distinguish it from other fibrotic interstitial lung diseases, such as fibrotic nonspecific interstitial pneumonia (fNSIP) or chronic hypersensitivity pneumonitis (cHP). Aims: We analysed the role of AGE and RAGE levels and the ratio of both molecules in serum samples as possible biomarkers that distinguish different fibrotic interstitial lung entities. Method: Serum samples were collected from 48 IPF patients, 15 cHP, 15 fNSIP, and 12 healthy age matched controls. Patient characteristics (age, sex, smoke habits, and pulmonary functional test (PFT)) were recorded. AGEs and sRAGE level were assessed by ELISA following the manufacture’s recommendation. Patient’s data and serum determinations were analysed with SPSS statistic software. Results: Our study demonstrated a decrease in sRAGE together with an increment of AGEs levels in serum in IPF and cHP samples compared with control and fNSIP, which did not show significant differences between them. AGEs levels resulted negative correlated with sRAGE in IPF samples. Moreover, low levels of sRAGE correlates with worse PFT (FVC and DLCO). Conclusions: This findings demonstrate that the imbalance in AGE/sRAGE levels in serum samples could differentiate IPF and cHP from NSIP. Furthermore, the correlation between sRAGE measurements and patient’s PFT could reflect the severity of the disease.