Non-response to antiviral therapy is associated with obesity and increased hepatic expression of suppressor of cytokine signalling 3 (SOCS-3) in patients with chronic hepatitis C, viral genotype 1.
BACKGROUND
Interferon alpha (IFN-alpha) activated cellular signalling is negatively regulated by inhibitory factors, including the suppressor of cytokine signalling (SOCS) family. The effects of host factors such as obesity on hepatic expression of these inhibitory factors in subjects with chronic hepatitis C virus (HCV) are unknown.


OBJECTIVE
To assess the independent effects of obesity, insulin resistance, and steatosis on response to IFN-alpha therapy and to determine hepatic expression of factors inhibiting IFN-alpha signalling in obese and non-obese subjects with chronic HCV.


METHODS
A total of 145 subjects were analysed to determine host factors associated with non-response to antiviral therapy. Treatment comprised IFN-alpha or peginterferon alpha, either alone or in combination with ribavirin. In a separate cohort of 73 patients, real time-polymerase chain reaction was performed to analyse hepatic mRNA expression. Immunohistochemistry for SOCS-3 was performed on liver biopsy samples from 38 patients with viral genotype 1 who had received antiviral treatment.


RESULTS
Non-response (NR) to treatment occurred in 55% of patients with HCV genotypes 1 or 4 and 22% with genotypes 2 or 3. Factors independently associated with NR were viral genotype 1/4 (p < 0.001), cirrhosis on pretreatment biopsy (p = 0.025), and body mass index > or = 30 kg/m2 (p = 0.010). Obese subjects with viral genotype 1 had increased hepatic mRNA expression of phosphoenolpyruvate carboxy kinase (p = 0.01) and SOCS-3 (p = 0.047), in comparison with lean subjects. Following multivariate analysis, SOCS-3 mRNA expression remained independently associated with obesity (p = 0.023). SOCS-3 immunoreactivity was significantly increased in obesity (p = 0.013) and in non-responders compared with responders (p = 0.014).


CONCLUSIONS
In patients with chronic HCV viral genotype 1, increased expression of factors that inhibit interferon signalling may be one mechanism by which obesity reduces the biological response to IFN-alpha.
Walsh
M J
MJ
School of Medicine, Southern Division, University of Queensland, Queensland, Australia.
Jonsson
J R
JR
Richardson
M M
MM
Lipka
G M
GM
Purdie
D M
DM
Clouston
A D
AD
Powell
E E
EE
D000328:Adult; D000998:Antiviral Agents / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005234:Fatty Liver / Q000150:complications; D005260:Female; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics; D019698:Hepatitis C, Chronic / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007333:Insulin Resistance / Q000502:physiology; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000627:therapeutic use*; D008099:Liver / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000032:analysis; D011092:Polyethylene Glycols / Q000627:therapeutic use*; D011994:Recombinant Proteins; D012189:Retrospective Studies; D012254:Ribavirin / Q000627:therapeutic use; D015398:Signal Transduction; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000032:analysis*; D016896:Treatment Outcome
D000998:Antiviral Agents; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011994:Recombinant Proteins; C106644:SOCS3 protein, human; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D011092:Polyethylene Glycols; D012254:Ribavirin; D010729:Phosphoenolpyruvate Carboxykinase (GTP); C100416:peginterferon alfa-2a