Quantitative Proteomic Study Unmasks Fibrinogen Pathway in Polycystic Liver Disease

Therapeutic opportunities in polycystic kidney and liver disease through extracellular matrix dynamics

Autosomal Dominant and Autosomal Recessive Polycystic Kidney Disease (ADPKD and ARPKD) are, respectively, common and rare forms of polycystic disorders, characterized by the formation and progressive growth of cysts from tubules in the kidneys and bile ducts in the liver. Alterations in the extracellular matrix (ECM) and in the activity of matrix metalloproteases (MMPs), both associated with fibrosis, have been shown to be important factors in cystic growth and progression of these diseases. We used tandem mass spectrometry (LC-MS/MS) to identify the most enriched proteins and pathways in an orthologous rapidly progressive mouse model of ADPKD: Pkd1flox/floxTamCre. This information was used to discover and validate novel therapeutic targets in orthologous models of ADPKD (Pkd1flox/floxTamCre) and ARPKD (Pkdh1del3-4/del3-4). ECM related pathways and expression levels of MMPs were among the most dysregulated cellular processes in polycystic kidney and liver. Selective inhibition of MMPs by marimastat (MTT) altered the ECM response and resulted in inhibition of collecting duct-derived cyst growth, delay of global kidney cyst progression and rescue of liver phenotype by normalized MMPs expression and significant reduction in fibrosis. This phenotypic improvement was further enhanced by treatment of MTT and tolvaptan, indicating an additive benefit to targeting the fibrotic and growth pathways in cysts. As conclusion, targeting of MMPs are important in ECM dysregulation and offers a new potential therapeutic strategy for both kidney and bile duct derived fibrocystic disease in ADPKD and ARPKD. Such approaches can have additive benefits with other treatment approaches, such as tolvaptan.

Polycystic Liver Disease: Pathophysiology, Diagnosis and Treatment

Polycystic liver disease (PLD) is a clinical condition characterized by the presence of more than 10 cysts in the liver. It is a rare disease Of genetic etiology that presents as an isolated disease or assoc\iated with polycystic kidney disease. Ductal plate malformation, ciliary dysfunction, and changes in cell signaling are the main factors involved in its pathogenesis. Most patients with PLD are asymptomatic, but in 2-5% of cases the disease has disabling symptoms and a significant reduction in quality of life. The diagnosis is based on family history of hepatic and/or renal polycystic disease, clinical manifestations, patient age, and polycystic liver phenotype shown on imaging examinations. PLD treatment has evolved considerably in the last decades. Somatostatin analogues hold promise in controlling disease progression, but liver transplantation remains a unique curative treatment modality.