PAR-2, IL-4R, TGF-beta and TNF-alpha in bronchoalveolar lavage distinguishes extrinsic allergic alveolitis from sarcoidosis
Abstrakt
Sarcoidosis (SARC) and extrinsic allergic alveolitis (EAA) share certain markers, making a differential diagnosis difficult even with histopathological investigation. In lung tissue, proteinase-activated receptor-2 (PAR-2) is primarily investigated with regard to epithelial and inflammatory perspectives.
Varying levels of certain chemokines can be a useful tool for distinguishing EAA and SARC. Thus, in the present study, differences in the levels of transforming growth factor (TGF)-beta 1, tumor necrosis factor (TNF)-alpha, interleukin-4 receptor (IL-4R) and PAR-2 in bronchoalveolar lavage fluid (BALF) were compared, using an ELISA method, between 14 patients with EAA and six patients with SARC.
Statistically significant higher levels of IL-4R, PAR-2 and the PAR-2/TGF-beta 1 and PAR-2/TNF-alpha ratios were observed in EAA patients as compared with SARC patients. Furthermore, the ratios of TNF-alpha/total protein, TGF-beta 1/PAR-2 and TNF-alpha/PAR-2 were significantly lower in EAA patients than in SARC patients.
The results indicated a higher detection of PAR-2 in EAA samples in association with TNF-alpha and TGF-beta levels. As EAA and PAR-2 in parallel belong to the Th2-mediated pathway, the results significantly indicated an association between this receptor and etiology.
In addition, the results indicated that SARC is predominantly a granulomatous inflammatory disease, thus, higher levels of TNF-alpha are observed. Therefore, the detection of PAR-2 and investigated chemokines in BALF may serve as a useful tool in the differential diagnosis between EAA and SARC.