Research Communications of the 24th ECVIM-CA Congress

No conflicts of interest reported. Activins are cytokines belonging to the transforming growth factor (TGF)-b superfamily. It is thought that activins may be the key intermediary in TGF-b1 mediated fibrotic response. Activin A has been suggested to participate in the pathogenesis of human idiopathic pulmonary fibrosis (IPF), but studies regarding the role of activin B are still spares. Canine IPF (CIPF) is a chronic, incurable interstitial lung disease occurring particularly in West Highland White Terriers (WHWTs). During the disease course, acute exacerbations (AEs), with poor prognosis, can occur. Histopathologically AEs of CIPF are featured by diffuse alveolar damage, which is also a key feature in acute respiratory distress syndrome (ARDS). Our objective was to study the expression of activin A and B by immunohistochemistry in the lung tissue of CIPF WHWTs (n = 5), CIPF WHWTs with concurrent AE (n = 4), and dogs of various breeds with ARDS (n = 4), and to compare these findings to healthy WHWTs (n = 3). In addition, western blot analysis of activin B from bronchoalveolar lavage fluid (BALF) of CIPF WHWTs (n = 6) and healthy WHWTs (n = 6) was conducted. We demonstrated that activin B, but not activin A, is strongly expressed in the altered alveolar epithelium in lungs of diseased WHWTs as well as in ARDS lungs. Furthermore, activin B was detected in BALF of CIPF WHWTs, most notably in samples from dogs with AE, but not in BALF of healthy WHWTs. This novel finding suggests that activin B participates in the pathophysiology of CIPF and might act as a potential marker of alveolar epithelial damage.