Research Article Metalloproteinases and Their Tissue Inhibitors in Comparison between Different Chronic Pneumopathies in the Horse Ann Kristin Barton, 1 Tarek Shety, 1 Angelika Bondzio, 2 Ralf Einspanier, 2 and Heidrun Gehlen 1 1 Equine Clinic, Veterinary Faculty, Freie Universitaet Berlin, Oertzenweg 19b, 14163 Berlin, Germany 2 Institute of Veterinary Biochemistry, Veterinary Faculty, Freie Universitaet Berlin, Oertzenweg 19b, 14163 Berlin, Germany Correspondence should be addressed to Ann Kristin Barton; ann-kristin.barton@fu-berlin.de Received 30 July 2015; Revised 13 November 2015; Accepted 17 November 2015 Academic Editor: Kang-Yun Lee Copyright © 2015 Ann Kristin Barton et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In chronic respiratory disease, matrix metalloproteinases (MMPs) contribute to pathological tissue destruction when expressed in excess, while tissue inhibitors of metalloproteinases (TIMPs) counteract MMPs with overexpression leading to fbrosis formation. Tey may be out of balance in equine pneumopathies and serve as biomarkers of pulmonary infammation. We hypothesized that MMPs and TIMPs correlate to clinical fndings and bronchoalveolar lavage fuid cytology in diferent equine chronic pneumopathies. Using a scoring system, 61 horses were classifed controls as free of respiratory disease ( = 15), recurrent airway obstruction (RAO,  = 17), infammatory airway disease (IAD,  = 18), or chronic interstitial pneumopathy (CIP,  = 11). Zymography and equine MMP and TIMP assays were used to detect MMP-2, MMP-8, MMP-9 as well as TIMP-1, and TIMP-2 in BALF supernatant. MMP-2, TIMP-1, and TIMP-2 concentrations were signifcantly increased in RAO and IAD compared to controls. MMP-9 concentration and MMP-8 activity evaluated by fuorimetry were signifcantly increased in RAO, IAD, and CIP. Tese results were confrmed by zymography for MMP-2 and MMP-9 activity in 52 horses. In conclusion, MMPs and TIMPs correlate well with clinical and cytologic fndings. Tese fndings support the usefulness of MMPs, TIMPs, and their ratios to evaluate the severity of respiratory disease and may help to identify subclinical cases. 1. Introduction Te extracellular matrix (ECM) represents the scafold that supports the alveolar wall and has a major impact on lung architecture, homeostasis, and function. Te pulmonary ECM underlays a continuous turnover; a dynamic equilib- rium between synthesis and degradation of the ECM is main- tained for physiological balance. Tis balance is controlled by synthesis and deposition of ECM components, proteolytic degradation of ECM by matrix metalloproteinases (MMPs), and inhibition of MMP activity by specifc tissue inhibitors of matrix metalloproteinases (TIMPs) [1–3]. In health, MMPs degrade the ECM to allow normal tissue repair, but in chronic infammation they contribute to pathological tissue destruction when expressed in excess [4]. Tus, it has been suggested that MMPs can either protect against or contribute to pathology in infammatory processes by exacerbation of aberrant lung remodeling [5–7]. ECM degradation results in destruction of interstitial collagen and release of degraded collagen fragments, which results in neutrophil infux with the production of chemoattractants [8]. In chronic res- piratory disease, remodeling results in decreasing airway lumen, increased smooth muscle mass, peribronchial fbrosis, epithelial cell hyperplasia, and impaired airway function [9– 11]. Regulation of remodeling may be a key for developing new therapeutics and disease management [2]. Matrix metalloproteinases (MMPs) were frst described over 50 years ago by Gross and Lapiere [12]. Collagenolytic MMP-8 was increased in tracheal epithelium lining fuid (TELF) of RAO afected horses [13]. Immunoreactivity of collagenases MMP-8 and MMP-13 was signifcantly increased in TELF of horses with RAO, compared to healthy horses, and was positively correlated with the amount of degradation of type-I collagen [14]. Hindawi Publishing Corporation Mediators of Inflammation Volume 2015, Article ID 569512, 9 pages http://dx.doi.org/10.1155/2015/569512