Pan-caspase inhibitor VX-166 reduces fibrosis in an animal model of nonalcoholic steatohepatitis.
Nonalcoholic fatty liver disease (NAFLD) is a potentially progressive liver disease that culminates in cirrhosis. Cirrhosis occurs more often in individuals with nonalcoholic steatohepatitis (NASH) than in those with steatosis (nonalcoholic fatty liver [NAFL]). The difference between NAFL and NASH is the extent of hepatocyte apoptosis, which is more extensive in NASH. Because phagocytosis of apoptotic cells activates hepatic stellate cells (HSCs), we examined the hypothesis that a pan-caspase inhibitor, VX-166, would reduce progression of fibrosis in a mouse model of NASH. Male db/db mice were fed methionine/choline-deficient (MCD) diets to induce NASH and liver fibrosis. Mice were gavaged once daily with either the pan-caspase inhibitor VX-166 (6 mg/kg/d; Vertex, Abingdon, UK) or vehicle only and sacrificed at 4 or 8 weeks. Treatment with an MCD diet increased alanine aminotransferase (ALT), caspase-3 activity, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells, NASH, and fibrosis. Treatment of MCD-fed mice with VX-166 decreased active caspase-3, TUNEL-positive cells, and triglyceride content (P < 0.05). However, ALT levels were similar in VX-166-treated mice and vehicle-treated controls. Histological findings also confirmed that both groups had comparable liver injury (NAFLD activity score >or=6). Nevertheless, VX-166-treated MCD-fed mice demonstrated decreased alpha-smooth muscle actin expression (4 weeks, P < 0.05; 8 weeks, P < 0.005) and had reduced hepatic levels of collagen 1alpha1 messenger RNA (8 weeks, P < 0.05). Hydroxyproline content and Sirius red staining of VX-166-treated livers confirmed decreases in fibrosis.


CONCLUSIONS
Inhibiting hepatic apoptosis suppresses the development of fibrosis in mice with NASH. Beneficial effects on liver fibrosis were associated with reductions in hepatic steatosis, but occurred without obvious improvement in liver injury. These findings are consistent with evidence that apoptosis triggers HSC activation and liver fibrosis and suggest that caspase inhibitors may be useful as an antifibrotic NASH therapy.
Witek
Rafal P
RP
Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC, USA.
Stone
W Carl
WC
Karaca
F Gamze
FG
Syn
Wing-Kin
WK
Pereira
Thiago A
TA
Agboola
Kolade M
KM
Omenetti
Alessia
A
Jung
Youngmi
Y
Teaberry
Vanessa
V
Choi
Steve S
SS
Guy
Cynthia D
CD
Pollard
John
J
Charlton
Peter
P
Diehl
Anna Mae
AM
D000199:Actins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002796:Choline Deficiency / Q000150:complications; D048909:Diabetes Complications / Q000150:complications; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D005234:Fatty Liver / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology*; D055166:Hepatic Stellate Cells / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology*; D008297:Male; D008715:Methionine / Q000172:deficiency; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008820:Mice, Obese; D009765:Obesity / Q000150:complications
D000199:Actins; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C544013:alpha-smooth muscle actin, mouse; D008715:Methionine; D053148:Caspase 3