Peritoneal molecular environment, adhesion formation and clinical implication

Whether induced by infection, inflammation, ischemia, and/or surgical injury, peritoneal adhesions are the leading cause of pelvic pain, bowel obstruction and infertility. It is clear that while postsurgical peritoneal wounds heal without adhesions in some patients, others develop severe scarring from seemingly equal procedures; in addition, in the same patient, adhesions can develop at one surgical site and not in another. The mechanisms underlying the predisposition to form adhesions as well as their site specificity are completely unknown. However, a large number of intraperitoneal surgical procedures are performed each day in the USA, and thus many patients are at risk of developing postoperative adhesions. Therefore, understanding of adhesion formation at the molecular level is essential and in the absence of such information, attempts to prevent patients from developing adhesions will remain an empirical process. The unprecedented advancement in molecular biology during the past decade has led to the identification of many biologically active molecules with the potential of regulating inflammatory and immune responses, angiogenesis and tissue remodeling, events that are central to normal peritoneal wound healing and adhesion formation. Although, the insight into their importance in the development of tissue fibrosis has substantially increased, their major roles in peritoneal biological functions and adhesion formation remain at best speculative. This article reviews the clinical implications of adhesions and attempts to highlight some of the key molecules i.e. growth factors, cytokines, chemokines, proteases and extracellular matrix, that are recognized to regulate inflammation, fibrinolysis, angiogenesis, and tissue remodeling, events that are central to peritoneal wound repair and adhesion formation. Finally, the article discusses the potential application and site specific delivery of several active compounds that are developed to alter the local inflammatory and immune response i.e., cytokine/chemokine network, targeted gene delivery and development of a new generation of biomaterials to prevent adhesion formation. Such understanding of peritoneal biology not only assist us to better manage patients with adhesion, but also those with endometriosis and malignant diseases that affect the peritoneal cavity.