Mitochondrial DNA depletion in liver tissue of patients infected with hepatitis C virus: contributing effect of HIV infection?

Objectives It has been suggested that chronic hepatitis C virus (HCV) infection depletes mitochondrial DNA (mtDNA) in the liver. Because decreased mtDNA levels were also found in humans infected with HIV, we investigated whether HIV may have aggravated hepatic mtDNA depletion in individuals with HCV infection. Methods In this cross-sectional study, liver biopsies were performed in a total of 40 individuals prior to any antiviral therapy. The individuals were recruited from the Hospital Clinic, Barcelona and the HIV Centre, Dusseldorf. Seventeen patients were negative for HIV and HCV and were biopsied for liver enzyme elevation of unknown cause (controls), 14 individuals had chronic HCV but no HIV infection, and nine subjects were coinfected with both viruses. mtDNA and liver histology were centrally assessed. Results The groups did not differ with respect to age, gender, liver function tests and HCV viral load, where applicable. mtDNA levels were decreased by 19% in the HCV-monoinfected group (P=0.03) and by 27% in the HIV/HCV-coinfected subjects (P=0.02) compared to controls. The mtDNA content, however, did not differ between individuals with HCV monoinfection and HCV/HIV coinfection (P=0.75). The degrees of liver fibrosis, inflammatory activity or steatosis did not correlate with mtDNA content. Conclusions Liver mtDNA content is reduced in both HCV-monoinfected and HIV/HCV-coinfected patients. Under the limitations of our study, we could demonstrate only a slight trend towards more pronounced mtDNA depletion in HIV/HCV-coinfected subjects.