b-thymosins and interstitial lung disease: study of a scleroderma cohort with a one-year follow-up

Background: b-thymosins play roles in cytoskeleton rearrangement, angiogenesis, fibrosis and reparative process, thus suggesting a possible involvement in the pathogenesis of systemic sclerosis. The aim of the study was to investigate the presence of thymosins b4, b4 sulfoxide, and b10 in bronchoalveolar lavage fluid of scleroderma patients with interstitial lung disease and the relation of these factors with pulmonary functional and radiological parameters. Methods: b-thymosins concentrations were determined by Reverse Phase-High Performance Liquid Chromatography-Electrospray-Mass Spectrometry in the bronchoalveolar lavage fluid of 46 scleroderma patients with lung involvement and of 15 controls. Results: Thymosin b4, b4 sulfoxide, and b10 were detectable in bronchoalveolar lavage fluid of patients and controls. Thymosin b4 levels were significantly higher in scleroderma patients than in controls. In addition, analyzing the progression of scleroderma lung disease at one-year follow-up, we have found that higher thymosin b4 levels seem to have a protective role against lung tissue damage. Thymosin b4 sulfoxide levels were higher in the smokers and in the scleroderma patients with alveolitis. Conclusions: We describe for the first time b-thymosins in bronchoalveolar lavage fluid and their possible involvement in the pathogenesis of scleroderma lung disease. Thymosin b4 seems to have a protective role against lung tissue damage, while its oxidation product mirrors an alveolar inflammatory status. Background b-thymosins are a family of G-actin sequestering peptides involved in cytoskeleton rearrangement, intracellular signaling, cell-cell adhesion, motility, survival, differentiation, and malignant transformation [1]. While in mammalian tissues thymosin b4 is usually the main peptide, representing about 70-80% of the total b-thymosins content [2], thymosin b10 is usually detectable at concentrations about 5-10-fold lower compared to thymosin b4. However, in preneoplastic and neoplastic tissues and in activated lymphocytes the ratio thymosin b10/b4 seems to increase [3,4]. The oxidation product of thymosin b4 at the Methionine6 residue, thymosin b4 sulfoxide, was also detectable in many body fluids [5]. Although the secretion pathway is not fully understood, recent studies highlighted various extra-cellular roles for these peptides [1]. Thymosin b4 is essential for platelet-clot formation and wound healing [6]. Moreover, while thymosin b10 seems to have anti-angiogenic properties, significantly decreasing mRNA levels of vascular endothelial growth factor (VEGF) and of VEGF receptor-1, thymosin b4 promotes angiogenesis [7,8]. Of interest thymosin b4 can up-regulate the expression of hepatocyte growth factor and down-regulate the expression of platelet derived growth factor-beta receptor in a model of liver fibrosis, thus suggesting an anti-fibrotic potential role of thymosin b4 [9]. Furthermore, both thymosin b4 and thymosin b4 sulfoxide seem to have antiinflammatory properties [10,11]. The role of b-thymosins in cytoskeleton rearrangement, angiogenesis, fibrosis and reparative process * Correspondence: [email protected] Department of Rheumatology, Catholic University, Rome, Italy Full list of author information is available at the end of the article De Santis et al. Respiratory Research 2011, 12:22 http://respiratory-research.com/content/12/1/22 © 2011 De Santis et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. suggests a possible involvement of these peptides in the pathogenesis of systemic sclerosis, a multi-organ connective tissue disease characterized by skin and internal organ fibrosis and microvascular abnormalities. The cytokines and paracrine factors underlying fibrosis and vasculopathy in scleroderma are not completely characterized yet. The presence of thymosin b4 and thymosin b10 in body fluids, such as saliva, has been recently demonstrated using a number of immunological [12] and proteomic [5] techniques, but not in bronchoalveolar lavage fluid (BALF). Therefore, the present study has been carried out with the aim to demonstrate the presence of b-thymosins in BALF of normal subjects and of scleroderma patients with interstitial lung disease and to correlate their levels with the biologic, functional and radiological parameters of lung involvement, through Reverse Phase-High Performance Liquid Chromatography-Electrospray-Mass Spectrometry analysis (RPHPLC-ESI-MS) of the naturally occurring peptides. In this study we have described for the first time b-thymosins in human BALF. Moreover, we have hypothesized a possible involvement of these factors in the pathogenesis of scleroderma lung disease. In fact, we have found higher concentrations of thymosin b4 in the BALF of scleroderma patients with lung involvement compared to the normal counterpart and of thymosin b4 sulfoxide in the subset of scleroderma patients with alveolitis. In addition, analyzing the progression of scleroderma lung disease at one-year follow-up, we have found that higher thymosin b4 levels seem to have a protective role against lung tissue damage.