The Role of Epithelial to Mesenchymal Transdifferentiation in End-Stage Renal Disease

Retroperitoneal Fibrosis, Today: An Updating of Knowledges on this Subjet

Retroperitoneal fibrosis (RPF) is characterized, at first, by a replacement of the normal retroperitoneal tissue by an active granulomatosis inflammation (cellular phase), and at a later stage by a fibrous scar tissue (established fibrotic phase). The aetiology of secondary RPFs includes several drugs (notably methysergide, ergotamine, pergolide, hydralazine), both chronic atherosclerotic aortitis-periaortitis and inflammatory aortic aneurisms, autoimmune diseases such as different forms of systemic vasculitis and collagen diseases, histiocytosis such as Erdheim-Chester syndrome, desmoplastic reactions to retroperitoneal malignancy carcinoid syndrome, retroperitoneal accidentally and surgically occurred traumas, abdominal radiation therapy.

On the contrary, the causes of idiopathic RPF remain uncertain; its pathogenesis is associated to immuno-mediated mechanisms. The inflammatory process can involve retroperitoneal vessels, ureters, peri- and pararenal spaces, mesenteric small intestine, duodenum, psoas muscles, and can spread to mediastinal space. Diagnosis and characterization of the polyphase inflammatory evolution require integrated approaches including laboratory tests, morpho-functional imaging and, sometimes, histopathologic assessment. In the early stages, the management of RPF ranges from the removal of identifiable etiologic agents to the interfering with the inflammatory immuno-mediated process by means of several drugs. Unfortunately, many effective immunosuppressive drugs induce adverse reactions unrelated to their specific immunosuppressive action; this is the reason why the biopharmacology research today is struggling towards the identification of molecular targets having their expression restricted to immune cells and/or cytokines. Moreover, the progression of atheromatous aortitis to RPF could be prevented by statins which are able to interfere with the inflammatory pathway as well as to induce the well-known reduction in the levels of atherogenic lipoproteins. In the late established fibrotic stage, either open surgery or endourologic, laparoscopic procedures are performed; nevertheless neoadiuvant and adiuvant corticosteroid-immunosuppressive treatments are mandatory in order to avoid any relapse of the disease.