Protein glutathionylation increases in the liver of patients with non-alcoholic fatty liver disease.
OBJECTIVE
Oxidative stress is an important pathophysiological mechanism in non-alcoholic steatohepatitis, where hepatocyte apoptosis is significantly increased correlating with disease severity. Protein glutathionylation occurs as a response to oxidative stress, where an increased concentration of oxidized glutathione modifies post-translational proteins by thiol disulfide exchange. In this study, we analyzed the protein glutathionylation in non-alcoholic fatty liver disease (NAFLD) and evaluated a potential association between glutathionylation, fibrosis, and vitamin E treatment.


METHODS
Protein glutathionylation was studied in the livers of 36 children (mean age 12.5 years, range 4-16 years) subdivided into three groups according to their NAFLD activity score (NAS) by Western blot analysis and immunohistochemistry, using a specific monoclonal antibody. In addition, we identified the hepatocyte ultrastructures involved in glutathionylation by immunogold electron microscopy.


RESULTS
Our findings showed that protein glutathionylation increases in the livers of patients with NAFLD and it is correlated with steatohepatitis and liver fibrosis. Its increase appears mainly in nuclei and cytosol of hepatocytes, and it is reversed by antioxidant therapy with reduced fibrosis.


CONCLUSIONS
Protein glutathionylation significantly increases in livers with NAFLD, strongly suggesting that oxidative injury plays a crucial role in this disease. Furthermore, the marked increase of protein glutathionylation, in correlation with collagen VI immunoreactivity, suggests a link between the redox status of hepatic protein thiols and fibrosis.
Piemonte
Fiorella
F
Molecular Medicine Unit, Chemistry Laboratory, Bambino Gesù Children's Hospital and Research Institute, Rome, Italy. piemonte@opbg.net
Petrini
Stefania
S
Gaeta
Laura Maria
LM
Tozzi
Giulia
G
Bertini
Enrico
E
Devito
Rita
R
Boldrini
Renata
R
Marcellini
Matilde
M
Ciacco
Enzo
E
Nobili
Valerio
V
D000293:Adolescent; D000975:Antioxidants / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D024142:Collagen Type VI / Q000378:metabolism; D005234:Fatty Liver / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008103:Liver Cirrhosis / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy; D008297:Male; D018384:Oxidative Stress; D011506:Proteins / Q000378:metabolism*; D014810:Vitamin E / Q000627:therapeutic use
D000975:Antioxidants; D024142:Collagen Type VI; D011506:Proteins; D014810:Vitamin E; D005978:Glutathione