284-OR: Hepatocyte-Specific CCN2 Gene Deletion Prevents NASH Fibrosis in a Mouse Model of High-Fat Feeding and Diabetes

Introduction: CCN2, formerly known as CTGF, is a pro-fibrotic protein that is implicated in several diabetes-related complications. The role of CCN2 in mediating NASH fibrosis in diabetes has not been fully elucidated. We hypothesize that targeting liver CCN2 can prevent NASH fibrosis in diabetes.

Aim: To examine whether hepatocyte specific homozygous gene deletion of CCN2 leads to less severe liver fibrosis compared with control mice exposed to high fat feeding and diabetes.

Methods: Male control mice (B6.Cg-Tg(AlbCre)21Mgn/J (AlbCre) and homozygous CCN2^fl/fl (CCN2^fl/fl)), and hepatocyte specific CCN2 knockout mice (CCN2^flxB6.Cg-Tg(AlbCre)21Mgn/J (CCN2KO)) were fed either standard chow or high fat diet (HFD; 45% kCal fat). HFD mice were rendered diabetic (HFD+DM) after 15 wks with low dose streptozotocin (2-3 x 0.65 mg/kg ip) then maintained for a further 10 wks. Liver fibrosis was assessed histologically with Picro Sirius Red (PSR) staining. Gene expression of fibrosis markers were measured by RT-qPCR. Biochemical assays were undertaken.

Results: There was less fibrosis by PSR staining in the HFD+DM CCN2KO mice at the central vein (24% reduction, 2.20±0.84 controls vs. 1.66±0.82 CCN2-KO, p=0.03, one tailed Mann-Whitney test) and portal tract (18% reduction, 2.51±0.85 controls vs. 2.06±0.84 CCN2KO, p=0.04) compared with HFD+DM control mice. In HFD+DM CCN2KO mice, there were significant reductions in gene expression of collagen-I (44%, p=0.04), -III (44%, p=0.04) and -IVα1 (40%, p=0.01) but not in collagen-VI or fibronectin. Compared with chow fed mice, HFD+DM mice had higher body weight, BGLs, insulin levels, fat mass and AST and ALT activity but there was no difference in metabolic outcomes between control strains and CCN2KO mice.

Conclusion: Our study has shown partial prevention of NASH fibrosis in diabetes in a novel model with hepatocyte specific CCN2 knockout mice. CCN2 is increasingly a potential target for limiting progression of NASH fibrosis in diabetes.