Evaluation of the relationship between lung involvement and serum latent transforming growth factor binding protein 2 (LTBP2) level in scleroderma patients

Scleroderma (SSc) is a multisystemic connective tissue disease which vasculopathy, inflammation, autoimmunity and fibrosis play a role in its pathogenesis. Skin involvement is the most common clinical feature. Development of fibrotic process with lung involvement is an important cause of mortality and morbidity of the disease. It is known that many cytokines, especially transforming growth factor beta (TGF-β), play a role in the fibrosis process. LTBP2 from the family of latent TGF-β binding proteins (LTBP) released to the ECM (extra cellular matrix) together with the large latent complex (LLC), where the latent form of TGF-β forms a complex, is found to be excessively released from elastic tissues such as the aorta and lungs and known to be associated with fibrosis. In this study, we examined the association of LTBP2 with lung involvement in scleroderma patients. We included 44 patients with scleroderma (6 diffuse cutaneous SSc, 31 limited cutaneous SSc, 7 overlap SSc), diagnosed according to 2013 ACR/EULAR classification criteria, between the ages of 18-65, and 41 healthy individuals as the control group. Hemogram, liver, kidney and thyroid function tests, spot urine proteinuria, pro-NT BNP values were noted at the patients' routine outpatient clinic admissions, and after an eight-hour fasting, an extra tube of blood was drawn simultaneously and then separated for LTBP2 study by ELISA method. For lung evaluation, we looked at pulmonary function tests (PFT), carbon monoxide diffusion test (DLCO), six-minute walk test, GAP score and Warrick score. We measured systolic pulmonary artery pressures by taking echocardiography. The LTBP2 levels of scleroderma patients were higher than the healthy control group, but there was no statistically significant difference (3.51 ng/ml, 2.89 ng/ml, p=0.223). In terms of lung involvement, we could not find a statistically significant difference between Warrick score, GAP score, PFT parameters, DLCO test, 6-minute walk test and serum LTBP2. We did not find any significant difference between modified Rodnan score, systolic pulmonary artery pressure and LTBP2 levels. In our study, we revealed that there is no relationship between serum LTBP2 levels and lung involvement of scleroderma patients. KEYWORDS: Scleroderma, latent transforming growth factor binding protein 2, fibrosis, lung involvement