Non-invasive assessment of liver fibrosis in autoimmune hepatitis

Abstract

Introduction. The degree of liver fibrosis is of great importance for prognosis and therapeutic intervention in chronic liver diseases. However, there is a relative lack of tools and technologies for non-invasive and longitudinal assessment of liver fibrosis in autoimmune hepatitis (AIH). Low sensitivity and specificity of currently available diagnostic options highlight the necessity of fibrosis biomarker identification. Aim of the study. To analyze the importance of non-invasive biomarkers for liver fibrosis assessment in AIH. Materials and methods. A scientific review have been performed using HINARI database. Based on search terms “liver fibrosis”, “non-invasive tests” and “biomarkers”, articles on this topic have been identified and the most relevant ones have been studied. Results. The extracellular matrix (ECM) may provide options for biomarker identification, as both the content and the composition of the ECM correlate with fibrosis stage. The balance between matrix metalloproteases (MMP) and tissue inhibitors of metalloproteases (TIMP) affects the turnover model of ECM, thus MMP-1, MMP-3, TIMP-1 are applied in non-invasive diagnosis as reliable fibrosis markers. The N-terminal propeptide of procollagen type III (PIIINP) reveals the intensity of ECM synthesis, but its specificity and sensitivity in fibrosis evaluation is considerable higher if associated with hyaluronic acid and MMP. Despite their high applicability and good reproducibility, biomarkers present some limitations in displaying liver fibrosis, because they are not liver specific and unable to discriminate between intermediate stages of fibrosis. On the other hand, transient elastography via liver stiffness measurement can stage hepatic fibrosis, especially with high performance for cirrhosis. However, the accuracy of this non-invasive technique in AIH is still limited due to false positive results in conditions like acute hepatitis, extrahepatic cholestasis, liver congestion, and lower applicability than serum biomarkers in case of ascites or/and obesity. Conclusions. There is increasing evidence for the prognostic value of both functional and imaging biomarkers as liver fibrosis non-invasive assessment methods in AIH. Certainly, the combination of these different tools will overcome their individual disadvantages and allow a more personalized fibrosis staging.