Results
Our study included 74 patients with HCV infection and 88 individuals without HCV infection. Demographic characteristics and laboratory findings of the patient and control groups are summarized in Table1. The mean HCV-RNA of patients with HCV infection was 1513297.6 ± 2898584 IU/mL, and the distribution of the genotypes (gp) was as follows: gp 1a, 10%; gp 1b, 47%; gp 1, 12%; gp 2, 20%; gp 3, 8%; and gp 5, 3%.
There was no significant difference in age, gender distribution, body mass index, smoking, or comorbidities (diabetes mellitus, hypertension, cardiovascular disease, chronic renal failure, hyperlipidemia, and asthma/chronic obstructive pulmonary disease) between the HCV patients and controls (p >0.05). ALT, AST, GGT, total protein, total bilirubin and direct bilirubin levels were significantly higher in the HCV group compared with the control group, whereas the albumin level was significantly lower (p <0.05 for all). Leukocyte and platelet counts, as well as urea, creatinine, PT, and INR values were similar in the two groups (p >0.05) (Table1).
As shown in Table 2, the NT, TT, and NT/TT levels were significantly lower in the HCV group than in the control group, whereas the DS, DS/NT, and DS/TT levels were significantly higher (p <0.05 for all). The TOS and OSI levels were significantly higher and the TAS levels were significantly lower in the HCV group than in the control group (p < 0.001 for all).
In the correlation analysis between oxidative stress markers (TAS, TOS, OSI and DTDH) and liver function tests (albumin, ALT, AST and bilirubin) in the HCV group, there was only a negative correlation between OSI and albumin (r = -0.301, p= 0.009).
DiscussionGrowing evidences suggest that oxidative stress caused by disruption of the balance between ROS and antioxidants is associated with the pathogenesis and progression of CHC.2-4 Induction of NADPH oxidases by HCV proteins, HCV protein-mediated mitochondrial dysfunction, production of various cytokines, decreased GSH output, iron overload, induced antioxidant gene expression and increased expression of HCV core protein and cytochrome P450 2E1 have been reported as the possible sources of ROS in HCV infection.16Antioxidant defense systems remove increased ROS to maintain the redox balance in the liver.5 Thiols are one of the antioxidants that protect cells and tissues against oxidative damage. Under oxidative stress, thiols can be oxidized by oxidant molecules to form reversible DS bonds and thereby resulting in altered DTDH. Therefore, DTDH is an important indicator used to evaluate the presence and intensity of oxidative stress.8
Many previous studies found that total thiol levels measured using the Ellmann’s method were significantly lower in patients with HCV infection than in those without.17-19 However, there were no data on DTDH in these studies because the level of DS, the thiol oxidation product, could not be determined with this method. Both components of the DTDH can be measured simultaneously using the automated colorimetric method developed by Erel and Neselioglu in 2014, thereby this balance can be fully evaluated.8 Prior to the availability of this technique, the thiol and disulfide levels of low molecular weight thiols (LMWTs), such as glutathione (GSH), glutathione disulfide (GSSG), cysteine (Cys) and cystine (CySS), were generally measured to evaluate the status of DTDH.8However, LMWTs constitute only a small part of the plasma thiol pool; a large part primarily comprises albumin and protein thiols.20 Therefore, we assume that the low molecular weight thiol/disulfide homeostasis such as GSG/GSSG and cys/CySS may not precisely reflect body DTDH.
Lin et al.21 found that the levels of GSH, a predominant LMWT, were low and GSSG were high in HCV group before treatment compared with the control group; however, it was observed that the GSSG level decreased after treatment. Jain et al.4showed that the plasma GSSG/(GSH + GSSG) ratio in patients with HCV infection was significantly higher than in the controls. Similarly, another study demonstrated low GSH and high GSSG levels in HCV patients, suggesting a high GSH turnover.22 Consistent with these studies, we found that NT level, TT level and NT/TT ratio were significantly lower and DS level, DS/NT ratio and DS/TT ratio were significantly higher in HCV group compared to the control group. These results indicate that DTDH is disturbed and shifts to the DS side in patients with HCV infection. This shift reveals that patients with HCV infection are exposed to high oxidative stress. This increased oxidative stress in CHC may be due to chronic inflammation and continuous production of ROS in HCV-infected cells.16 Similarly, researchers have observed that the DTDH shifted to the DS side in other infectious diseases such as chronic hepatitis B,9 and Crimean-Congo hemorrhagic fever,10brucellosis.23
In our study, we also found no correlation between DTDH parameters and albumin, ALT, AST, and bilirubin levels, which is in concordance with some previous studies.3,17,18 In contrast, some researchers reported that ALT and AST were negatively correlated with GSH and positively correlated with GSSG in HCV-infected patients.24-26 These conflicting results may be due to differences in the characteristics of the patients with HCV infection included in the studies, such as disease stage and the presence or absence of HCV-related liver disease.
Several studies have demonstrated that antioxidant therapy may have a beneficial effect on normalization of ALT, decrease in viral load and improvement of liver histology in patients with HCV infection.27,28 In that aspect, we believe that compensation for the thiol deficiency with thiol resources such as N-acetylcysteine and alpha-lipoic acid may improve the efficacy of treatment in these patients.
To assess oxidative stress, TOS and TAS measurements may provide more valuable information than individual measurements of each oxidant and antioxidant molecule.13,14 Therefore, in this study, TAS, TOS, and OSI values of the HCV and control groups were also compared. We observed that the TOS and OSI values were higher and the TAS level was lower in the HCV group compared with the control group, as in a previous study.19 These results indicate increased oxidative stress in HCV infected patients.
There are some limitations in this study. It was conducted with a small number of participants in a single center. Furthermore, the relationship between the progression of CHC disease and the DTDH status was not examined.
ConclusionTo the best of our knowledge, the present study is the first to examine the DTDH status in patients with HCV infection. DTDH shifted toward DS formation in patients with HCV infection. The TOS and OSI levels were significantly higher and TAS level was significantly lower in HCV group compared to the control group. These results indicate that patients with HCV infection are vulnerable to oxidative stress and have disturbed status of oxidant- antioxidant. This study supports the view that oxidative stress plays a role in the pathogenesis of CHC.