Serum calprotectin as new biomarker for disease severity in idiopathic pulmonary fibrosis: a cross-sectional study in two independent cohorts.

BACKGROUND: Non-invasive biomarkers for the assessment of disease severity in idiopathic pulmonary fibrosis (IPF) are urgently needed. Calprotectin belongs to the S-100 proteins produced by neutrophils, which likely contribute to IPF pathogenesis. Calprotectin is a well-established biomarker in inflammatory bowel diseases. In this cross-sectional study, we aimed to establish the potential role of calprotectin as a biomarker in IPF. Specifically, we hypothesised that patients with IPF have higher serum calprotectin levels compared with healthy controls, and that calprotectin levels are associated with disease severity. METHODS: Blood samples were obtained from healthy volunteers (n=26) and from two independent IPF cohorts (derivation cohort n=26, validation cohort n=66). Serum calprotectin levels were measured with a commercial kit adapted for that purpose and compared between healthy controls and patients with IPF. Clinical parameters, including forced vital capacity, diffusing capacity for carbon monoxide (DLCO) and the Composite Physiologic Index (CPI), were correlated with calprotectin serum levels. RESULTS: The IPF derivation cohort showed increased serum calprotectin levels compared with healthy controls (2.47±1.67 vs 0.97±0.53 µg/mL, p<0.001). In addition, serum calprotectin levels correlated with DLCO% predicted (r=-0.53, p=0.007) and with CPI (r=0.66, p=0.007). These findings were confirmed in an independent IPF validation cohort. CONCLUSION: Serum calprotectin levels are significantly increased in patients with IPF compared with healthy controls and correlate with DLCO and CPI. Calprotectin might be a potential new biomarker for disease severity in IPF.

Mapping IPF helps identify geographic regions at higher risk for disease development and potential triggers.

BACKGROUND AND OBJECTIVE: The relationship between IPF development and environmental factors has not been completely elucidated. Analysing geographic regions of idiopathic pulmonary fibrosis (IPF) cases could help identify those areas with higher aggregation and investigate potential triggers. We hypothesize that cross-analysing location of IPF cases and areas of consistently high air pollution concentration could lead to recognition of environmental risk factors for IPF development. METHODS: This retrospective study analysed epidemiological and clinical data from 503 patients registered in the Observatory IPF.cat from January 2017 to June 2019. Incident and prevalent IPF cases from the Catalan region of Spain were graphed based on their postal address. We generated maps of the most relevant air pollutant PM2.5 from the last 10 years using data from the CALIOPE air quality forecast system and observational data. RESULTS: In 2018, the prevalence of IPF differed across provinces; from 8.1 cases per 100 000 habitants in Barcelona to 2.0 cases per 100 000 in Girona. The ratio of IPF was higher in some areas. Mapping PM2.5 levels illustrated that certain areas with more industry, traffic and shipping maintained markedly higher PM2.5 concentrations. Most of these locations correlated with higher aggregation of IPF cases. Compared with other risk factors, PM2.5 exposure was the most frequent. CONCLUSION: In this retrospective study, prevalence of IPF is higher in areas of elevated PM2.5 concentration. Prospective studies with targeted pollution mapping need to be done in specific geographies to compile a broader profile of environmental factors involved in the development of pulmonary fibrosis.

Predictive factors and prognostic effect of telomere shortening in pulmonary fibrosis.

BACKGROUND AND OBJECTIVE: The abnormal shortening of telomeres is a mechanism linking ageing to idiopathic pulmonary fibrosis (IPF) that could be useful in the clinical setting. The objective of this study was to identify the IPF patients with higher risk for telomere shortening and to investigate the outcome implications. METHODS: Consecutive Spanish patients were included at diagnosis and followed up for 3 years. DNA blood samples from a Mexican cohort were used to validate the results found in Spanish sporadic IPF. Prior to treatment, telomere length was measured through quantitative polymerase chain reaction (qPCR) and Southern blot. Outcome was assessed according to mortality or need for lung transplantation. A multivariate regression logistic model was used for statistical analysis. RESULTS: Family aggregation, age of <60 years and the presence of non-specific immunological or haematological abnormalities were associated with a higher probability of telomere shortening. Overall, 66.6% of patients younger than 60 years with telomere shortening died or required lung transplantation, independent of functional impairment at diagnosis. By contrast, in patients older than 60 years with telomere shortening, the negative impact of telomere shortening in outcome was not significant. CONCLUSION: Our data indicate that young sporadic IPF patients (<60 years) with some non-specific immunological or haematological abnormalities had higher risk of telomere shortening, and furthermore, they presented a poorer prognosis.

Serum AGE/RAGEs as potential biomarker in idiopathic pulmonary fibrosis.

BACKGROUND: The soluble receptor for advanced glycation end-products (sRAGE) has been suggested that it acts as a decoy for capturing advanced glycation end-products (AGEs) and inhibits the activation of the oxidative stress and apoptotic pathways. Lung AGEs/sRAGE is increased in idiopathic pulmonary fibrosis (IPF). The objective of the study was to evaluate the AGEs and sRAGE levels in serum as a potential biomarker in IPF. METHODS: Serum samples were collected from adult patients: 62 IPF, 22 chronic hypersensitivity pneumonitis (cHP), 20 fibrotic non-specific interstitial pneumonia (fNSIP); and 12 healthy controls. In addition, 23 IPF patients were re-evaluated after 3-year follow-up period. Epidemiological and clinical features were recorded: age, sex, smoking habits, and lung function. AGEs and sRAGE were evaluated by ELISA, and the results were correlated with pulmonary functional test values. RESULTS: IPF and cHP groups presented a significant increase of AGE/sRAGE serum concentration compared with fNSIP patients. Moreover, an inverse correlation between AGEs and sRAGE levels were found in IPF, and serum sRAGE at diagnosis correlated with FVC and DLCO values. Additionally, changes in serum AGEs and sRAGE correlated with % change of FVC, DLCO and TLC during the follow-up. sRAGE levels below 428.25 pg/ml evolved poor survival rates. CONCLUSIONS: These findings demonstrate that the increase of AGE/sRAGE ratio is higher in IPF, although the levels were close to cHP. AGE/sRAGE increase correlates with respiratory functional progression. Furthermore, the concentration of sRAGE in blood stream at diagnosis and follow-up could be considered as a potential prognostic biomarker.