Introduction
Chronic hepatitis C (CHC) infection is a liver disease caused by the
hepatitis C virus (HCV). It is a major public health problem, affecting
approximately 71 million people worldwide, and is one of the leading
causes of cirrhosis, hepatocellular cancer, and liver-related deaths. It
is estimated that approximately 400,000 people died in 2015 from
complications related to CHC.1 Although the mechanism
of how HCV induces liver damage is not fully understood to date, it has
been suggested that oxidative stress plays an important role in the
pathogenesis of CHC.2-4 Oxidative stress, caused by
the deterioration of homeostasis between reactive oxygen species (ROS)
and antioxidants, triggers liver damage by inducing DNA damage, lipid
peroxidation, and protein oxidation in the organism. The increased
oxidative stress in HCV infection induces hepatic stellate cell
activation, DNA damage, and gene mutation, which progresses toward liver
fibrosis/cirrhosis and hepatocellular carcinoma.5
Thiols containing the sulfhydryl (SH) group are part of the antioxidant
defense system as they are metal chelators, free radical scavengers, and
thiol/disulfide redox buffer components. The thiol groups of
sulfur-containing compounds, the main targets of ROS, react with oxidant
molecules to form disulfide bonds (S-S). This process is reversible;
disulfide bonds can be reduced to obtain the thiol
groups.6 The redox cycle between thiol groups and
disulfide bonds maintains a dynamic thiol–disulfide homeostasis (DTDH),
which plays an important role in many physiological processes such as
cellular growth, cell signaling, protein conformation, detoxification of
xenobiotics, apoptosis, and the antioxidant defense
system.7 While the thiol side of the thiol–disulfide
system has been measured since 1979, it was only in 2014 that Erel and
Neselioğlu developed a reliable way to measure the level of both
components of this system quickly and cheaply.8Previous studies have reported that impaired DTDH plays a role in the
pathogenesis of various diseases such as chronic hepatitis
B,9 Crimean-Congo hemorrhagic
fever,10 diabetes11 and familial
Mediterranean fever.12 However, DTDH, an alternative
indicator of oxidative stress, has not yet been investigated using the
new method in HCV-infected patients. Therefore, the objective of this
study was to examine the DTDH as well as total antioxidant status (TAS)
and total oxidant status (TOS) in patients with HCV infection.