Identificação de biomarcadores pró-fibróticos em soro e líquido pleural em pacientes com derrame pleural exsudativo por tuberculose e neoplasias

Abstract

Pleural tuberculosis is the most common extrapulmonary clinical manifestation of this infection and, in about 20% of cases, is associated with active lung injury. Annually more than half a million cases of pleural effusion due to tuberculosis occur worldwide. The inflammatory reaction in response to Mycobacterium tuberculosis infection has direct and indirect action on several cell types, occuring the release of cytokines and growth factors in the serum and pleural fluid, such as VEGF-A, PDGF-BB, TGF- β1 and GAL-3, constituting important mechanisms that contribute to the fibrosis process. The analysis of biological samples is a key tool in the search for new ways of prognosing and monitoring pleural fibrosis. Considering these observations, the present study proposes to identify pro-fibrotic biomarkers present in the pleural fluid and serum of patients with pleural tuberculosis and cancer. Fifty-two samples of pleural fluid and serum were collected and analyzed from patients with exudative pleural effusion recruited from the Pleural Diseases Outpatient Clinic of the Pneumology and Phthisiology Service of the Pedro Ernesto University Hospital (HUPE/UERJ), from patients diagnosed with pleural tuberculosis (TB group, n=33) or neoplasia (NTB group, n=19). The studied biomarkers (VEGF-A, PDGF-BB, TGF-β1 and GAL-3) were measured by enzyme immunoassay (ELISA). Additionally, a histopathological analysis of pleural biopsies was carried out in the patients selected in the study. Statistical analysis was performed using the non-parametric Mann-Whitney test with Welch correction, Spearman correlation, Kruskal-Wallis test for multiple variations and ROC curve, p<0.05 was considered significant. Mean TGF-β1 levels in the pleural fluid were significantly higher in the TB group (107.5 ± 11.85 pg/mL) than in the NTB group (44.26 ± 8.44 pg/mL) with p= 0. 0078. Furthermore, the levels of this biomarker were significantly higher in the serum of the TB group when compared to the NTB group (p<000.1). The ROC curve for TGF-β1 showed 81.82% sensitivity; 84.2% specificity, AUC= 0.80 (95% CI 0.6748–0.9265); likelihood ratio 5.18; positive predictive value= 90%; negative predictive value= 72% e Accuracy= 82.69. When analyzing the VEGF-A levels individually in the TB and NTB groups, we verified increased levels of this biomarker in the pleural fluid when compared to the serum (p<0.05). The analysis of the NTB group showed increased levels of Gal-3 in the LP (2366+653.5 pg/mL) compared to the SP (1239+108.3 pg/mL), (p<0.0001). When analyzing the PDGF-BB biomarker, there was no significant difference in the levels of this biomarker in the SP of the patients studied (p= 0.4650). When comparing the cutoff point with the histopathological analysis, a possible relationship with the degree of fibrosis was verified, however, we cannot infer this due to the size of the sample and the number of fragments of analyzed biopsy samples. It is concluded that our study was able to suggest that the TGF-β1 biomarker is a strong candidate to assess in diagnose of patients with pleural tuberculosis