EquineReview

Equine multinodular pulmonary fibrosis (EMPF) is a chronic, progressive, interstitial lung disease of adult horses that has a guarded to poor prognosis. Human idiopathic pulmonary fibrosis (IPF) is a prevalent interstitial lung disease that resembles EMPF in its progression and treatment response. The mainstay of treatment for both conditions is corticosteroids and the pathogenesis is poorly understood. In IPF a familial association has been identified. Holley and Medina-Torres (2021) undertook a systematic review to address the question of whether herpesvirus plays a role in the pathogenesis of either disease. Pulmonary fibrosis is likely mediated by an abnormal cytokine response to epithelial injury. An association between EMPF and equine herpesvirus 5 (EHV5) has been demonstrated in horses. Human IPF lacks an experimental model with a natural host infected with a gammaherpesvirus (γHV). A relevance screening identified 16 articles. All human studies investigated virus detection and tried to find a causal relationship between γHV and pulmonary fibrosis. Statistical differences between patients with HIPF and control groups or other lung diseases, have been found in association with Epstein-Barr virus, cytomegalovirus and human herpesvirus 8. In EMPF, a significant difference in polymerase chain reaction detection of EHV5 between diseased horses and control groups has been identified, which is not the case with EHV2. Epstein Barr virus was found frequently in patients with IPF, although there was inconsistency in its detection within lung tissue. Findings support the use of EMPF as a model to study IPF.