Abnormal wound healing responses in pulmonary fibrosis: focus on coagulation signalling

The normal response of tissue to injury involves a sequence of overlapping events, which need to occur in a timely and controlled manner for successful tissue repair and restoration of normal function. Failure to control the healing process can lead to considerable tissue remodelling and the replacement of functional tissue with permanent fibrous scar tissue. It is proposed that pulmonary fibrosis arises from repetitive, widespread epithelial injury. However, the nature of the insult for the most common and most fatal form of pulmonary fibrosis, idiopathic pulmonary fibrosis (IPF), is currently unknown and the pathogenetic pathways leading to IPF remain to be fully elucidated. Increasing evidence suggests that abnormalities in a number of pathways involved in the wound healing response may play central roles. The present article will briefly review the pathways involved in wound healing focusing on the control of fibroblast/myofibroblast function and the coagulation cascade acting via the family of signalling receptors, the proteinase activated receptors, which influence a range of cellular responses implicated in the development of pulmonary fibrosis. Understanding the involvement of these pathways in the aberrant wound repair-response in pulmonary fibrosis may lead to the identification of new targets and strategies for therapeutic intervention.