Correlation Between Serum Cytokines,Interferons,and Liver Functions in Hepatitis C Virus Patients

Abstract

To provide fundamental insights into the mechanism of Hepatitis C virus (HCV), we conduct the present study to improve further understanding of the interaction between HCV and cytokines. Two hundred one patients were enrolled in this study. Seventy-eight patients matching the study group in terms of age and gender with negative serology for hepatitis viruses, HIV virus, and with liver enzyme levels within normal range were selected as the control group. Patients were diagnosed with positive hepatitis C by detection of positive HCV antibodies in serum. Interferon-gamma (IFN-γ) and interleukin (IL)-10 were measured in positive and negative patients. Also liver functions (alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma glutamyl transferase [GGT], alkaline phosphatase [ALP], urea, total protein, albumin, total and direct bilirubin) were also measured. Our results indicated significant elevation in IL-10 and IFN-γ in positive hepatitis C patients. These elevations were accompanied by significant elevation in liver function biomarkers with significant regression in albumin and total protein content. Furthermore, IFN-γ significantly increased immune response of cellular immunity. IL-10 significantly decreased immune response of cellular immunity by inhibiting IFN-γ and other production of Th. Liver function levels can be used as a marker for HCV. The findings from our study recommend IL-10 pathway in HCV infection and use IFNs to increase immune response for viral hepatitis.

Introduction

HCV or Hepatitis C virus infection has over 5 million people affected in the United States (Chak and others 2011) and over 120 million people worldwide, hence a global health problem. Late estimations ascribe 700,000 passing to HCV every year (Newton and others 2015). This virus belongs to Hepacivirus genus and Flaviviridae family (Lindenbach and others 2007) with six genotypes and with more than 70 subtypes. In ∼85% infected individuals it may be unresolved, hence representing a significant hepatocellular carcinoma and liver cirrhosis cause. It is viewed as the commonest cirrhosis cause and chronic liver disease in the world. It also represents the main liver transplantation cause in United States, Europe, and Australia (Thimme and others 2001). Through HCV-RNA demonstration in blood for a minimum of 6 months after virus contamination is chronic infection proved (Chen and Morgan 2006). Those who show chronic liver disease's laboratory or clinical signs must get a chronic HCV infection diagnosis through both HCV-RNA and anti-HCV antibodies demonstration (EASL International Consensus Conference on Hepatitis C 1999). HCV transmission is caused mainly through infected blood or its products. Other risks, however, have got demonstrated for the infection of HCV, which get represented through illicit drugs, intravenous use hemodialysis, and HCV-infected organ transplantation. HCV infection, which is less frequent, has got documented as a result of contaminated blood occupational exposure. There has also been publication of HCV sporadic report due to intranasal cocaine use, unsafe sex, vertical transmission, and household exposure (Chen and Morgan 2006).

In the course of viral infection, there are various cytokines which do play their role in both tissue damage and viral clearance (Steinke and Borish 2006). There are over 100 reported cytokines, which get classified on the basis of their primary role. Cytokines, in relation to their roles, play a significant function during HCV infection pathogenesis, progression, and outcome of treatment. Multiple biomarker screening could best clarify disease immunopathogenesis and predict antiviral therapy responses because cytokine production control is highly complex and cytokine effects are spread widely through multiple networks of regulation (Nathan and others 1983). Immune response, which is conducted essentially by cytokines, may be able to play a significant function in HCV infection pathogenesis. A strong Th1 response, which is characterized by interferon-gamma (IFN-γ), tumor necrosis factor-alpha, and interleukin (IL)-2 production, is associated with clearance of HCV (Saito and Gale 2008).

Some information recommends that cytokines involved in the regulation of the immunological response might show a key role in HCV infection, contributing for HCV persistence, hepatic injury, and autoimmunity (Gramenzi and others 2005). Numerous studies have reported the impact of genetic markers on the host immune response against persistent viral infections (Assone and others 2016). Chronic HCV infection patients possess a T-cell response-activated cytokine pattern, which has elevated serum levels of IFN-γ, tumor necrosis factor alpha, IL-2, IL-4, and IL-10. Severe chronic liver cirrhosis or hepatitis C patients pose an enhanced IL-2 and IFN-γ expression compared with individuals having mild disease and healthy controls (Napoli and others 1996). Essentially, cytokine-conducted immune response plays a significant role in HCV infection pathogenesis. A strong Th1 response that is characterized by IFN-γ, tumor necrosis factor alpha, and IL-2 production does seem to have HCV clearance association (Mosmann and Sad 1996). However, they may be seen responsible for damage of the liver during a persistent infection (Saito and Gale 2008). There has been reported an important circulating and intrahepatic Th1-type cytokine correlation with liver injury degree (Elliott and others 2006; Saito and Gale 2008).

The cytokine, which plays a major role in angiogenesis (Szekanecz and others 1998) and collagen synthesis suppression (Reitamo and others 1994), and in Th1 cell differentiation (Tao and others 1997) enhancement, is the IFN-γ that is made by the Th1 cells (Mosmann and Sad 1996). Forty-eight weeks HCV-infected patients treated with IFN-γ lead to ∼20% sustained response rates (Shiffman and others 1997; Nelson and others 1998). Virological response-related factors include gender (McHutchison and Poynard 1999), liver biopsy degree of fibrosis, HCV ribonucleic acid level pretreatment, and HCV genotype. IFN-γ production gets controlled by antigen-presenting cells (APCs-secreted cytokines), most notably IL-15 and IL-2. These cytokines do serve as an infection link bridge with production of IFN-γ in inmate immune response (Dinarello 1999; Gołąb and others 2000). The aim of the present study is to find out the correlation between levels of some serum cytokines with HCV antibodies in diagnosed patients and to determine the severity by liver function tests.

Subjects and Methods

Study population

More than 5,000 patients came to the outpatient clinic in King Abdulaziz Hospital during March 2015 to June 2015 for various reasons, 201 patients were enrolled in this study after they had given their verbal informed consent. Exclusion criteria included patients who refused or ignore our request for additional samples; patients with chronic disease were also excluded. Patients who refused or ignored our request for additional samples were excluded. Seventy-eight patients, matching the study group in terms of age and gender with negative serology for hepatitis viruses, HIV virus, and with liver enzyme levels within normal range, were selected as the control group, whereas 78 patients matching the study group in terms of age and gender with negative serology for other hepatitis viruses (A, B, E) and HIV virus were selected as the patients group. All patients enrolled in this study were in chronic stage. In the patients group, there were 34 males (43.59%) and 44 females (56.41%). In the control group, 37 individuals were male (47.44%) and 41 female (52.56%). Available ages of control admitted to the hospital were enrolled in the study. Mean age was 43.83 ± 1.73 years in the hepatitis C group and 37.89 ± 2.19 years in the control group.

Detection of cytokines

Detection of HCV antibodies was performed by enzyme-linked immunosorbent assay (ELISA) method (according to McHutchison and Poynard 1998) using the Bio-Rad Kits. Serum levels of IL-10 and IFN-γ were also measured by ELISA (Abcam Kits) according to the manufacturer's instructions. Results were taken by using BEP III System (Siemens), absorbance was read at 450 nm within 30 min.

Determination of serum liver function tests

Liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma glutamyltransferase [GGT], and alkaline phosphatase [ALP]), serum proteins (albumin and total protein), as well as total and direct bilirubin and urea were all measured spectrophotometrically according to the manufacturer's instructions for the assay kit (Siemens) and the results were significant when P < 0.05.

Statistical analysis

All data were statistically analyzed using Statistical Package for Social Sciences (SPSS), version 18 for Windows (Microsoft). Associations between the different studied variables were evaluated with Pearson's correlation. Data are shown as mean ± standard error of mean, t-test was performed to compare between mean of groups, where (P < 0.05) was considered as a statistically significant result.

Results

Detection of anti-HCV antibody

Seventy-eight patients matching the study group in terms of age and gender with negative serology for hepatitis viruses, HIV virus, and with liver enzyme levels within normal range were selected as the control group, 37 individuals were male (47.44%) and 41 were female (52.56%) with mean age 37.89 ± 2.19. In the patient group, there were 34 males (43.59%) and 44 females (56.41%) with mean age 43.83 ± 1.73 years (Table 1).

Table 1.

Demographic Data of the Studied Groups

Parameters	Positive HCV-infected patients	Negative HCV-infected patients	Significance test (P-value)
Age (years)	43.83 ± 1.73	37.89 ± 2.19	0.035^*
Sex			—
Male	34	37
Female	44	41

Number and age of positive and negative HCV patient enrolled in the study.

P is significant if <0.05; ^*There is a significant difference between positive and negative patients by using independent t-test at P < 0.05.

HCV, hepatitis C virus.

IFN-γ and IL-10

Our results showed significant increase in the secretion of IFN-γ and IL-10 in serum-positive HCV-infected patient's compared with negative HCV-infected patients (Table 2).

Table 2.

Levels of Interferon-IFN-γ and Interleukin IL-10 Secreted in Positive Hepatitis C Virus-Infected Patients and Negative Hepatitis C Virus Patients as Determined by ELISA Techniques

	Positive HCV-infected patients	Negative HCV-infected patients
Parameters	Mean ± SE	Mean ± SE	t-Value	Significance test (P-value)
IL-10 (pg/mL)	9.31 ± 1.29	4.88 ± 0.35	3.29	0.001^*
IFN-γ (pg/mL)	26.38 ± 4.63	16.25 ± 1.49	2.08	0.039^*

P is significant if <0.05; ^*There is a significant difference between positive and negative patients by using independent t-test at P < 0.05.

SE, standard error of mean; IL, interleukin; IFN, interferon; ELISA, enzyme linked immunosorbent assay.

Liver function results

It is clear from the present study that levels of serum ALT, AST, and ALP were significantly higher in positive HCV-infected patient's compared with negative HCV patients, whereas GGT was not significantly increased, data are shown in Table 3.

Table 3.

Levels of Liver Enzymes in Positive Hepatitis C Virus-Infected Patients and Negative Hepatitis C Virus Patients

	Positive HCV-infected patients	Negative HCV patients
Parameters	Mean ± SE	Mean ± SE	t-Value	Significance test (P-value)
ALT (uL)	60.16 ± 5.74	38.29 ± 1.05	3.74	0.000^*
AST (uL)	38.67 ± 3.49	25.14 ± 1.20	3.67	0.000^*
GGT (U/L)	58.29 ± 12.79	42.46 ± 0.19	1.24	0.220
ALP (U/L)	114.11 ± 13.88	84.52 ± 0.83	2.13	0.036^*

P is significant if <0.05; ^*There is a significant difference between positive and negative by using independent t-test at P < 0.05.

ALT, alanine aminotransferase; AST, aspartate aminotransferase; GGT, gamma glutamyltransferase; ALP, alkaline phosphatase.

Data in Table 4 shows that serum albumin and total protein levels were significantly decreased in positive HCV-infected patients compared with negative HCV patients. The secretion of total and direct bilirubin in the serum was significantly higher in positive HCV-infected patient's compared with negative HCV patients. The level of serum urea showed a significant increase in the HCV-infected patient's when compared with negative HCV patients (Table 5).

Table 4.

Levels of Liver Proteins in Positive Hepatitis C Virus-Infected Patients and Negative Hepatitis C Virus Patients

	Positive HCV-infected patients	Negative HCV patients
Parameters	Mean ± SE	Mean ± SE	t-Value	Significance test (P-value)
Albumin (g/L)	31.28 ± 0.70	34.00 ± 1.02	2.201	0.030^*
Total protein (g/L)	65.43 ± 0.49	70.76 ± 1.70	3.010	0.003^*

P is significant if <0.05; ^*There is a significant difference between positive and normal by using independent t-test at P < 0.05.

Table 5.

Levels of Liver End Products in Positive Hepatitis C Virus-Infected Patients and Negative Hepatitis C Virus Patients

	Positive HCV-infected patients	Negative HCV patients
Parameters	Mean ± SE	Mean ± SE	t-Value	Significance test (P-value)
Total bilirubin (μmol/L)	17.86 ± 3.47	7.25 ± 0.19	3.053	0.003^*
Direct Bilirubin (μmol/L)	6.96 ± 1.90	1.87 ± 0.03	2.644	0. 010^*
Urea (mmol/L)	5.71 ± 0.71	3.39 ± 0.42	2.813	0.006^*

P is significant if <0.05; ^*There is a significant difference between positive and normal by using independent t-test at P < 0.05.

Correlation of cytokines

To determine the severity of HCV infection, we studied the correlation between levels of serum cytokines in patients group and control group according to age and liver function tests.

Correlation between cytokines and age in positive HCV-infected patients

The correlation between age and serum levels of IFN-γ and IL-10 in HCV-positive group according to age is illustrated in (Table 6). No correlation was detected between age and IFN-γ (r = −0.068, P = 0.555) or between age and IL-10 (r = −0.033, P = 0.777), although such correlation was not detected between IFN-γ and IL-10 (r = −0.049, P = 0.669).

Table 6.

Correlations Between Cytokines and the Age in Positive Hepatitis C Virus-Infected Patients

		Cytokines
Cytokines	Age	IL-10 (pg/mL)	IFN-γ (pg/mL)
IL-10 (pg/mL)
R	−0.033	—	0.049
P	0.777		0.669
IFN-γ (pg/mL)
R	0.068	0.049	—
P	0.555	0.669

P is significant if P < 0.05.

Correlation between cytokines and age in negative HCV-infected patients

Table 7 shows the correlation between age and serum levels of IFN-γ and IL-10 in HCV-negative group according to age. No correlation was detected between age and IFN-γ (r = −0.127, P = 0.270). However, age was significantly correlated with IL-10 (r = 0.261*, P = 0.021**), although such correlation was not detected between IFN-γ and IL-10 (r = −0.007, P = 0.949).

Table 7.

Correlations Between Cytokines and the Age in Negative Hepatitis C Virus-Infected Patients

		Cytokines
Cytokines	Age	IL-10 (pg/mL)	IFN-γ (pg/mL)
IL-10 (pg/mL)
R	0.261^*	—	−0.007
P	0.021		0.949
IFN-γ (pg/mL)
R	−0.127	−0.007	—
P	0.270	0.949

P is significant if P < 0.05; ^*significantly correlated.

Correlation between cytokines and liver enzymes in positive HCV-infected patients

The correlation between serum ALT, AST, GGT, ALP, IFN-γ, and IL-10 in positive HCV-infected patients is shown (Table 8). There was a significant correlation between AST and IFN-γ (r = 0.300, P = 0.008*), whereas no correlation was detected between ALT, GGT, ALP and IFN-γ, ALT and IFN-γ (r = −0.060, P = 0.602), GGT and IFN-γ (r = −0.104, P = 0.529), ALP and IFN-γ (r = −0.128, P = 0.357), although such correlation was not detected between ALT, AST, GGT, ALP, and IL-10, ALT, and IL-10 (r = −0.028, P = 0.810), AST and IL-10 (r = −0.003, P = 0.981), GGT and IL-10 (r = −0.068, P = 0.680), and ALP and IL-10 (r = 0.032, P = 0.817).

Table 8.

Correlation Between Cytokines and Liver Enzymes in Positive Hepatitis C Virus-Infected Patients

	Cytokines
Liver enzymes	IL-10 (pg/mL)	IFN-γ (pg/mL)
ALT (uL)
R	−0.028	0.060
P	0.810	0.602
AST (uL)
R	0.003	0.300
P	0.981	0.008^*
GGT (U/L)
R	−0.068	−0.104
P	0.680	0.529
ALP (U/L)
R	0.032	−0.128
P	0.817	0.357

P is significant if P < 0.05; ^*significantly correlated; ^** P is significant.

The positive correlation between AST and IFN-γ highlighted the correlation between serum cytokines and liver function test.

Correlation between cytokines and liver proteins in positive HCV-infected patients

Table 9 shows the correlation between serum albumin, total protein, IFN-γ and IL-10 in positive HCV-infected patients. No correlation was detected between albumin, total protein and IFN-γ, albumin and IFN-γ (r = 0.078, P = 0.580), and total protein and IFN-γ (r = −0.051, P = 0.712). Also, such correlation was not detected between albumin, total protein and IL-10, albumin and IL-10 (r = −0.182, P = 0.198), and total protein and IL-10 (r = −0.105, P = 0.451).

Table 9.

Correlation Between Cytokines and Liver Proteins in Positive Hepatitis C Virus-Infected Patients

	Cytokines
Liver proteins	IL-10 (pg/mL)	IFN-γ (pg/mL)
Albumin (g/L)
R	−0.182	0.078
P	0.198	0.580
Total protein (g/L)
R	−0.105	−0.051
P	0.451	0.712

P is significant if P < 0.05.

Correlation between cytokines and liver end products in positive HCV-infected patients

Table 10 shows the correlation between serum total bilirubin, direct bilirubin, urea, IFN-γ, and IL-10 in positive HCV-infected patients. No correlation was detected between total bilirubin, direct bilirubin, urea and IFN-γ, total bilirubin and IFN-γ (r = 0.027, P = 0.836), direct bilirubin and IFN-γ (r = −0.017, p = 0.909), and urea and IFN-γ (r = −0.141, P = 0.272). Also, such correlation was not detected between total bilirubin, direct bilirubin, urea and IL-10, total bilirubin and IL-10 (r = −0.020, P = 0.882), direct bilirubin and IL-10 (r = −0.033, P = 0.826), and urea and IL-10 (r = −0.125, P = 0.328).

Table 10.

Correlation Between Cytokines and Liver End Products in Positive Hepatitis C Virus-Infected Patients

	Cytokines
Liver end products	IL-10 (pg/mL)	IFN-γ (pg/mL)
Total bilirubin (μmol/L)
R	−0.020	0.027
P	0.882	0.836
Direct bilirubin (μmol/L)
R	−0.033	−0.017
P	0.826	0.909
Urea (mmol/L)
R	−0.125	−0.141
P	0.328	0.272

P is significant if P < 0.05.

Discussion

Immune response, which is conducted by cytokines, plays a significant HCV infection pathogenesis role. A strong Th1 response that is characterized by IFN-γ, tumor necrosis factor alpha, and IL-2 production does seem to have HCV clearance association (Saito and Gale 2008). IL-10, IL-13, IL-5, and IL-4 are produced by Th2 cells that limit Th1 response and facilitate antibody production (Nelson 2001). Our analysis of cytokine showed that adaptive immunity is able to promote significantly Th2 and Th1 cells to secrete IL-10 and IFN-γ elevated levels in positive patients with HCV infection (Szekanecz and others 1998). Th1 lymphocytes, which are characterized by tumor necrosis factor alpha, IFN-γ, and IL-2 predominant secretion, are involved in cytotoxic T-lymphocyte responses and cellular immunity, Th2 cells that modulate humoral responses through IL-13, IL-10, IL-5, and IL-4 production (Del Prete and others 1994).

In this study, the highest human IFN-γ serum levels got observed in positive patients with HCV infection (P < 0.05). The IFN-γ increase was observed in positive patients of HCV infection; it is as a result of replication of HCV virus, and progression of the disease, according to the observation in the previous reports (Post and others 2009). The important cd4+ helper T cells' role in spontaneous mediation of viral clearance was demonstrated through several observations. Proliferation of CD4+ helper T cell loss responses in the context of acute HCV had an association with chronic infection development and viral recurrence, in one of them (Gerlach and others 1999). This reason explains the IL-10 concentration and this study's result was found to be significantly lower compared with the concentration of IFN-γ in positive patients of HCV infection. On the other hand, there was a revelation by cytokine analysis that humoral immunity according to the age of patient was significantly able to promote Th2 into secretion of IL-10-elevated levels in positive patients with HCV infection. In addition, there was direct correlation seen between high IL-10 levels and age, as found in this particular project.

Being consistent with the previous reports in this study showed that AST enzyme activity got increased significantly with IFN-γ in positive patients with HCV infection compared with the control group (Missiha and others 2008). The higher AST levels of serum observed in the positive patient with HCV infection suggests a chronic HCV coinfection synergistic effect in the damage of liver cells. Some results were also reported for HCV (Petrova and others 2010).

Some authors suggested that ALT/AST ratio is correlated strongly with portal fibrosis level in HCV patients who are nonuremic (Sheth and others 1998). It is also stated that this ratio has no correlation with liver's necroinflammatory activity, and a ratio, which is <1, does exclude cirrhosis and severe fibrosis patients (Sheth and others 1998). In this study ALT/AST was an important marker in patients having HCV infection. HCV infection's natural outcome varies among individuals dramatically. In a fortunate minority, HCV infection seems self-limited, whereas in the majority, subjects do develop the persistent chronic infection (Seeff 1997). Although HCV infection in adults does progress in about (Terrault and others 2008) 5% to chronic stage (Vildózola Gonzales and Salinas 2009), in persistent infection of HCV individuals, majority do develop liver cancer, progressive fibrosis, and even coronary heart disease. However, other cases will not progress significantly to any liver disease (Kenny-Walsh 1999).

Cytokines have a crucial function to regulate inflammatory and immune responses. IL-10 and IFN-γ are Th1 cytokines and have powerful effect of immunoregulation on activation and proliferation stimulation of most B lymphocytes, natural killer cells, and T lymphocytes (Seder and Paul 1994). According to some evidence, IL-10, IFN-γ, and IL-2 patients' levels with severe or moderate cirrhosis and coronary heart disease are significantly decreased compared with those of the controls, which are healthy (Pawłowska and others 2005). Other author's observation is that increased IL-10, IFN-γ, and IL-2 expression has correlation with the staging or grading of chronic hepatitis (Napoli and others 1996). IL-10 and IFN-γ in this study increased significantly in positive patients with HCV infection (P < 0.05). HCV is usually a chronic viral infection, which is unusual in individuals despite its treatment clearing the virus. Differing viremia control rates with treatment has enabled some human immunological questions which are interesting to be addressed, like those pertaining to CD4+ T-cell response nature and relationship and the antigen clearance kinetics.

It is widely accepted that CD4+ T-cell responses do have a major function in the noncytopathic virus control (Godkin and others 2008). CD4+ T-cell responses, which are HCV specific by IFN-γ production, have the ability to proliferate in HCV infection. T-cell role is marked by other cytokine productions, such as IL-17 or IL-2, the vast antiviral T-cell majority appear to produce and/or proliferate IFN-γ (Bes and others 2012), this agree with our IFN-γ result that is increased significantly in positive patients of HCV infection. Therefore, as it seems, other immune mechanisms should get activated through high-dose IFN-γ exposure which is significant for clearance of the virus (Su and others 2002) by numerous cell types, which include dendritic cells, monocytes, macrophages, natural killer cells (De Maria and others 2007), and IL-10 may downregulate the processing of antigen by transporter associated having antigen processing, expression of mean corpuscular hemoglobin and production of IL-2 by antigen presenting cells or antigen-presenting cells (Mocellin and others 2003), hence resulting in impaired T-cell proliferation, memory and effector function (Shibata and others 1998).

Additionally, serum changes or levels of T-cell IL-10 have association with the antiviral therapy efficacy in some studies (Barnes and others 2002). In this study, the IFN-γ response, which is HCV-specific strength, is correlated with immunological, virological, and clinical parameters during the acute infection. Direct association of viremia and serum alanine aminotransferase (sALT) levels, and IFN-γ, which is HCV-specific, as well as proliferation of CD4+ T-cell, which is suppressed in this context of acute infection, does suggest IL-10 response to be induced as a mechanism of compensation to dampen inflammation that is ongoing.

A study by Luik and others 2004, identified IFN-γ response, which is HCV-specific observed with HCV resolved infection. According to this suggestion, T-cells, which are HCV-specific, are maintained on a similar antigenic hierarchy, scope, and frequency in HCV infection, which is chronic just like those found in recovered HCV infection, although they are polarized toward production of IL-10 instead of production of IFN-γ characteristic of spontaneous clearance of HCV. The finding's explanation includes the T-cell maturation alteration as a result of antigen-presenting cell virus-induced dysfunction (Yakushijin and others 2006).

In conclusion, the interaction between HCV and cytokines are complex and just beginning to be understood. Improved understanding of the interaction between HCV and cytokines will provide fundamental insights into the mechanism of HCV escape. Our results indicated the following: IFN-γ significantly increased immune response of cellular immunity. IL-10 significantly decreased immune response of cellular immunity by inhibiting IFN-γ and other production of Th. Liver function levels can be used as a marker for HCV. Our study finding recommends study of IL-10 pathway in HCV infection and use IFNs to increase immune response for viral hepatitis. We also recommended the investigation of the effect of IL-4, IL-5, IL-10, and IL-13 in viral clearness and their role in IFNs inhibition during the viral infection.

Footnotes

Acknowledgment

This project was supported by King Abdulaziz City for Science and Technology, KSA under grant number (PS-36-312).

Author Disclosure Statement

No competing financial interests exist.

References

Assone

, Paiva

, Fonseca

, Casseb

. 2016. Genetic Markers of the host in persons living with HTLV-1, HIV and HCV infections. Viruses, 8(2):38.

Barnes

, Harcourt

, Brown

, Lucas

, Phillips

, Dusheiko

, Klenerman

. 2002. The dynamics of T‐lymphocyte responses during combination therapy for chronic hepatitis C virus infection. Hepatology, 36(3):743–754.

Bes

, Sauleda

, Casamitjana

, Piron

, Campos-Varela

, Quer

, et al. 2012. Reversal of nonstructural protein 3-specific CD4(+) T cell dysfunction in patients with persistent hepatitis C virus infection. J Viral Hepat, 19(4):283–294.

Chak

, Talal

, Sherman

, Schiff

, Saab

. 2011. Hepatitis C virus infection in USA: an estimate of true prevalence. Liver Int, 31(8):1090–1101.

Chen

, Morgan

. 2006. The natural history of hepatitis C virus (HCV) infection. Int J Med Sci, 3(2):47–52.

De Maria

, Fogli

, Mazza

, Basso

, Picciotto

, Costa

, Moretta

. 2007. Increased natural cytotoxicity receptor expression and relevant IL‐10 production in NK cells from chronically infected viremic HCV patients. Eur J Immunol, 37(2):445–455.

Del Prete

, Maggi

, Romagnani

. 1994. Human Th1 and Th2 cells: functional properties, mechanisms of regulation, and role in disease. Lab Invest, 70(3):299–306.

Dinarello

. 1999. IL-18: a TH1-inducing, proinflammatory cytokine and new member of the IL-1 family. J Allergy ClinImmunol, 103(1):11–24.

EASL International Consensus Conference on Hepatitis C. Paris, 26–28, February 1999. Consensus statement. European Association for the study of the liver. J Hepatol, 30(5):956–961.

10.

Elliott

, Lloyd

, Ziegler

, Ffrench

. 2006. Protective immunity against hepatitis C virus infection. Immunol Cell Biol, 84(3):239–249.

11.

Gerlach

, Diepolder

, Jung

, Gruener

, Schraut

, Zachoval

, Pape

. 1999. Recurrence of hepatitis C virus after loss of virus-specific CD4+ T-cell response in acute hepatitis C. Gastroenterology, 117(4):933–941.

12.

Godkin

, Ng

, Gallagher

, Betts

, Thomas

, Lechler

. 2008. Expansion of hepatitis C—specific CD4+ CD25+ regulatory T cells after viral clearance: a mechanism to limit collateral damage?. J Allergy Clin Immunol, 121(5):1277–1284.

13.

Gołąb

, Zagożdżon

, Stokłosal

, Kamiński

, Kozar

, Jakóbisiak

. 2000. Direct stimulation of macrophages by IL-12 and IL-18—a bridge too far?. Immunol Lett, 72(3):153–157.

14.

Gramenzi

, Andreone

, Loggi

, Foschi

, Cursaro

, Margotti

, Bernardi

. 2005. Cytokine profile of peripheral blood mononuclear cells from patients with different outcomes of hepatitis C virus infection. J Viral Hepat, 12(5):525–530.

15.

Kenny-Walsh

. 1999. Clinical outcomes after hepatitis C infection from contaminated anti-D immune globulin. N Engl J Med, 340(16):1228–1233.

16.

Lindenbach

, Thiel

, Rice

. 2007. Flaviviridae: the viruses and their replication. In: Knipe

, Howley

, eds. Fields Virology. Philadelphia (PA): Lippincott-Raven. pp 1101–1152.

17.

Luik

, Knapp

, Thursz

, Thomas

, Schlaak

. 2004. Auto regulatory role of interleukin-10 in hepatitis C patients treated with IFN-α. J Interferon Cytokine Res, 24(10):585–593.

18.

McHutchison

, Poynard

. 1998. Combination therapy with interferon plus ribavirin for the initial treatment of chronic hepatitis C. Semin Liver Dis, 19:57–65.

19.

McHutchison

, Poynard

, Gordo

, Dienstag

, Morgan

, Yao

, Albrecht

. 1999. The impact of race on response to anti-viral therapy in patients with chronic hepatitis C. Hepatology, 30(4):302A.

20.

Missiha

, Ostrowski

, Heathcote

. 2008. Disease progression in chronic hepatitis C: modifiable and no modifiable factors. Gastroenterology, 134(6):1699–1714.

21.

Mocellin

, Panelli

, Wang

, Nagorsen

, Marincola

. 2003. The dual role of IL-10. Trends Immunol, 24(1):36–43.

22.

Mosmann

, Sad

. 1996. The expanding universe of T-cell subsets: Th1, Th2 and more. Immunol Today, 17(3):138–146.

23.

Napoli

, Bishop

, McGuinness

, Painter

, McCaughan

. 1996. Progressive liver injury in chronic hepatitis C infection correlates with increased intrahepatic expression of Th1‐associated cytokines. Hepatology, 24(4):759–765.

24.

Nathan

, Murray

, Wiebe

, Rubin

. 1983. Identification of interferon-gamma as the lymphokine that activates human macrophage oxidative metabolism and antimicrobial activity. J Exp Med, 158(3):670–689.

25.

Nelson

. 2001. The immunopathogenesis of hepatitis C virus infection. Clin Liver Dis, 5(4):931–953.

26.

Nelson

, Marousis

, Ohno

, Davis

, Lau

. 1998. Intrahepatic hepatitis C virus—specific cytotoxic T lymphocyte activity and response to interferon alfa therapy in chronic hepatitis C. Hepatology, 28(1):225–230.

27.

Newton

, Briggs

, Murray

, Dicker

, et al. 2015. Changes in health in England, with analysis by English regions and areas of deprivation, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet, 386(10010):2257–2274.

28.

Pawłowska

, Halota

, Smukalska

, Grabczewska

. 2005. Serum IL-2 and sIL-2R concentration in children with chronic hepatitis B. Polski merkuriusz lekarski: organ Polskiego Towarzystwa Lekarskiego, 18(103):33–35.

29.

Petrova

, Kamburov

, Nikolovska

, Kosseva

, Nikolova

, Krastev

. 2010. Epstein–Barr virus: is there any contribution to chronic hepatitis B and C?. Liver Int, 30(3):488–489.

30.

Post

, Ratnarajah

, Lloyd

. 2009. Immunological determinants of the outcomes from primary hepatitis C infection. Cell Mol Life Sci, 66(5):733–756.

31.

Reitamo

, Remitz

, Tamai

, Uitto

. 1994. Interleukin-10 modulates type I collagen and matrix metalloprotease gene expression in cultured human skin fibroblasts. J Clin Invest, 94(6):2489.

32.

Saito

, Gale

. 2008. Regulation of innate immunity against hepatitis C virus infection. Hepatol Res, 38(2):115–122.

33.

Seder

, Paul

. 1994. Acquisition of lymphokine-producing phenotype by CD4+ T cells. Annu Rev Immunol, 12(1):635–673.

34.

Seeff

. 1997. The natural history of chronic hepatitis C virus infection. Clin Liver Dis, 1(3):587–602.

35.

Sheth

. Flamm

, Gordon

, Chopra

. 1998. AST/ALT ratio predicts cirrhosis in patients with chronic hepatitis C virus infection. Am J Gastroenterol, 93(1):44–48.

36.

Shibata

, Foster

, Kurimoto

, Okamura

, Nakamura

, Kawajiri

, Metzger

. 1998. Immunoregulatory roles of IL-10 in innate immunity: IL-10 inhibits macrophage production of IFN-γ-inducing factors but enhances NK cell production of IFN-γ. J Immunol, 161(8):4283–4288.

37.

Shiffman

, Hofmann

, Thompson

, Ferreira‐Gonzalez

, Contos

, Koshy

, Garrett

. 1997. Relationship between biochemical, virological, and histological response during interferon treatment of chronic hepatitis C. Hepatology, 26(3):780–785.

38.

Steinke

, Borish

. 2006. Cytokines and chemokine's. J Allergy Clin Immunol, 117(2):S441–S445.

39.

, Pezacki

, Wodicka

, Brideau

, Supekova

, Thimme

, Chisari

. 2002. Genomic analysis of the host response to hepatitis C virus infection. Proc Natl Acad Sci U S A, 99(24):15669–15674.

40.

Szekanecz

. Szegedi

, Koch

. 1998. Angiogenesis in rheumatoid arthritis: pathogenic and clinical significance. J Invest Med, 46(2):27.

41.

Tao

, Grant

, Constant

, Bottomly

. 1997. Induction of IL-4-producing CD4+ T cells by antigenic peptides altered for TCR binding. J Immunol, 158(9):4237–4244.

42.

Terrault

. A, Im

, Boylan

, Bacchetti

, Kleiner

, Fontana

, Virahep-C Study Group. 2008. Fibrosis progression in African Americans and Caucasian Americans with chronic hepatitis C. Clin Gastroenterol Hepatol, 6(12):1403–1411.

43.

Thimme

, Oldach

, Chang

, Steiger

, Ray

, Chisari

. 2001. Determinants of viral clearance and persistence during acute hepatitis C virus infection. J Exp Med, 194(10):1395–1406.

44.

Vildózola Gonzales

, Salinas

. 2009. Historia natural de la infección crónica por el virus hepatitis B. Revista de Gastroenterología del Perú, 29(2):147–157.

45.

Yakushijin

, Kanto

, Inoue

, Oze

, Miyazaki

, Itose

, Takehara

. 2006. Reduced expression and functional impairment of toll-like receptor 2 on dendritic cells in chronic hepatitis C virus infection. Hepatol Res, 34(3):156–162.