Non-invasively differentiate non-alcoholic steatohepatitis by visualizing hepatic integrin αvβ3 expression with a targeted molecular imaging modality

Abstract

Background: Non-invasive methods to diagnose non-alcoholic steatohepatitis (NASH), an inflammatory subtype of non-alcoholic fatty liver disease (NAFLD), are currently unavailable.

Aim: To develop an integrin αvβ3-targeted molecular imaging modality to differentiate NASH.

Methods: Integrin αvβ3 expression was assessed in Human LO2 hepatocytes Scultured with palmitic and oleic acids (FFA). Hepatic integrin αvβ3 expression was analyzed in rabbits fed a high-fat diet (HFD) and in rats fed a high-fat, high-carbohydrate diet (HFCD). After synthesis, cyclic arginine-glycine-aspartic acid peptide (cRGD) was labeled with gadolinium (Gd) and used as a contrast agent in magnetic resonance imaging (MRI) performed on mice fed with HFCD.

Results: Integrin αvβ3 was markedly expressed on FFA-cultured hepatocytes, unlike the control hepatocytes. Hepatic integrin αvβ3 expression significantly increased in both HFD-fed rabbits and HFCD-fed rats as simple fatty liver (FL) progressed to steatohepatitis. The distribution of integrin αvβ3 in the liver of NASH cases largely overlapped with albumin-positive staining areas. In comparison to mice with simple FL, the relative liver MRI-T1 signal value at 60 minutes post-injection of Gd-labeled cRGD was significantly increased in mice with steatohepatitis (P < 0.05), showing a positive correlation with the NAFLD activity score (r = 0.945; P < 0.01). Hepatic integrin αvβ3 expression was significantly upregulated during NASH development, with hepatocytes being the primary cells expressing integrin αvβ3.

Conclusion: After using Gd-labeled cRGD as a tracer, NASH was successfully distinguished by visualizing hepatic integrin αvβ3 expression with MRI.

Keywords: Cyclic peptides; Hepatic integrin αvβ3; Magnetic resonance imaging; Non-alcoholic steatohepatitis; Non-invasive diagnosis.