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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 31  |  Issue : 3  |  Page : 762-771

Study of interleukin-18 during antiviral therapy for hepatitis C with sofosbuvir, ribavirin, and interferon in Menoufia hospitals


1 Department of Microbiology and Immunology, Faculty of Medicine, Menoufia University, Shebin El-Kom, Egypt
2 Department of Internal Medicine, Faculty of Medicine, Menoufia University, Shebin El-Kom, Egypt
3 Department of Microbiology and Immunology, Shebin El-Kom Fever Hospital, Shebin El-Kom, Egypt

Date of Submission25-Oct-2016
Date of Acceptance02-Jan-2017
Date of Web Publication31-Dec-2018

Correspondence Address:
Asmaa T.M Esmaeel
Shebin El-Kom, Menoufia Governorate
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_554_16

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  Abstract 


Objectives
The objectives of this study were to evaluate the role of interleukin-18 (IL-18) in liver cirrhosis caused by hepatitis C, and to determine the effect of the triple regimen treatment sofosbuvir, ribavirin, and interferon on its serum levels.
Background
IL-18 is a member of the IL-1 family. Recent studies have suggested that IL-18 plays a role in the pathogenesis of liver damage during acute and chronic hepatitis; furthermore, IL-18 may be involved in the development and progression of liver fibrosis.
Patients and methods
The present study was carried out on 27 hepatitis C patients and 15 age-matched and sex-matched healthy individuals. All patients were subjected to history taking, complete medical examination, and laboratory investigations for liver and kidney functions. Serum levels of IL-18 were measured by ELISA three times for each patient: the first one was measured before treatment initiation, the second after 1 week of treatment, and the third was measured after 3 months of treatment.
Results
The serum levels of IL-18 were highly elevated in hepatitis C patients compared with controls (P < 0.001). In addition, we found that serum IL-18 was significantly higher before initiation of treatment, decreased after 1 week of treatment, and it was markedly decreased after 3 months of treatment.
Conclusion
There is significant elevation in the serum levels of IL-18 in hepatitis C patients. IL-18 concentrations were reduced following a successful course of antiviral treatment.

Keywords: hepatitis C, interleukin-18, sofosbuvir


How to cite this article:
El-Hendawy GR, Salama AA, Abd El-Hamid AE, Esmaeel AT. Study of interleukin-18 during antiviral therapy for hepatitis C with sofosbuvir, ribavirin, and interferon in Menoufia hospitals. Menoufia Med J 2018;31:762-71

How to cite this URL:
El-Hendawy GR, Salama AA, Abd El-Hamid AE, Esmaeel AT. Study of interleukin-18 during antiviral therapy for hepatitis C with sofosbuvir, ribavirin, and interferon in Menoufia hospitals. Menoufia Med J [serial online] 2018 [cited 2019 Jan 22];31:762-71. Available from: http://www.mmj.eg.net/text.asp?2018/31/3/762/248751




  Introduction Top


Hepatitis C is a contagious disease that is caused by RNA flavivirus that infects the liver through exposure to infected blood. According to the WHO, nearly 3% of the world's population has been infected with hepatitis C virus (HCV). Therefore, more than 170 million people are chronic carriers of HCV and at high risk of developing liver cirrhosis and/or hepatocellular carcinoma[1]. Egypt has the highest prevalence of HCV in the world, estimated nationally at 14.7%[2].

Interleukin-18 (IL-18) is one of many cytokines that increases in plasma after HCV infection. Recognition of HCV by the hepatocyte pattern recognition receptor results in the induction of multifaceted innate and adaptive immune response, causing elevation in plasma levels of several proinflammatory cytokines that are elevated in patients with chronic hepatitis C (CHC), for example, increase in inducible protein-10, IL-18, macrophage inflammatory protein-1B, and macrophage chemoattractant protein-1 concentration. These proinflammatory cytokines decline in patients taking the new antiviral drugs sofosbuvir with ribavirin[3].

IL-18 is a cytokine that belongs to the IL-1 superfamily, and is produced by macrophages and other cells. It is also known as interferon γ (IFNγ)-inducing factor[4].

IL-18 is a proinflammatory cytokine, and it binds to a heterodimeric receptor complex containing IL-18 receptor 1 and the IL-18 receptor accessory protein. It is interesting to note that five of the six IL-1-like receptors form a closely linked gene cluster on chromosome 2[5].

IL-18 is constitutively expressed on plenty of cells and multiple tissues, such as epithelial barrier tissues, such as fibroblasts, myofibroblasts, endothelial cells, and intestinal epithelial cells, osteoblasts, adipocytes, lymphoid organs, the brain, embryos, inflamed tissues, smooth muscle cells, keratinocytes, immune cells such as macrophages, Kupffer cells, dendritic cells, microglial cells, and others[6]. IL-18 exhibits characteristics of other proinflammatory cytokines such as increasing cell adhesion molecules, nitric oxide synthesis, and chemokine production. Blocking IL-18 activity reduced metastasis in a mouse model of melanoma; this was due to a reduction in IL-18-induced expression of vascular cell adhesion molecule-1. A unique property of IL-18 is the induction of Fas ligand (FasL), which may account for the hepatic damage that takes place in macrophage activation syndrome[7].

Several human autoimmune diseases are associated with elevated production of IFNγ and IL-18, such as systemic lupus erythematosus, rheumatoid arthritis, type I diabetes, Crohn's disease, psoriasis, and graft versus host disease[8].

Recently, sofosbuvir has been used in the treatment of CHC, in combination with pegylated interferon (peg-IFN) and ribavirin; the three drugs were used for 3 months[9].

Sofosbuvir is a nucleotide analog that has been marketed since 2013. When compared with previous treatments, sofosbuvir-based regimens provide a higher cure rate, fewer side-effects, and a two-fold to four-fold reduced duration of therapy. Sofosbuvir inhibits the RNA polymerase that the HCV uses to replicate its RNA[10].


  Aim Top


The objectives of this study were as follows:

  • To determine serum levels of IL-18 in patients with CHC on sofosbuvir with IFN and ribavirin
  • To detect the relationship between serum IL-18 and degree of liver cirrhosis
  • To determine serum IL-18 in relation to severity of hepatitis C-related liver damage.



  Patients and Methods Top


Study population and selection of patients

This study was conducted at the Microbiology and Immunology Department, Faculty of Medicine, Menoufia University, in collaboration with Shebin El-Kom Fever Hospital, Menoufia Governorate, Egypt, during the period from January 2015 to October 2015. The study protocol was approved by the Local Ethics Committee of Menoufia University. All participants provided their written informed consent before inclusion into the study.

The study involved two groups: group I included 27 hepatitis C patients (13 male and 14 female) and group II included 15 age-matched and sex-matched healthy individuals.

Inclusion criteria were as follows: patients above 20 years of age, who presented with liver cirrhosis caused by hepatitis C, diagnosed by PCR.

Exclusion criteria were as follows: previous or current infection with hepatitis B or HIV, autoimmune hepatitis, hepatitis C treatment since 12 months, and other diseases that cause increased IL-18 levels, such as autoimmune thyroiditis and psoriasis.

After signing an informed consent, patients were subjected to the following:

  • Proper history taking: personal history and clinical history, including hepatic encephalopathy, jaundice, bilharziasis, fever, abdominal pain, ascites, variceal hemorrhage, and associated comorbidities (diabetes and hypertension), of all participants were obtained
  • Laboratory investigations, FibroScan, New Delhi, Delhi, India and abdominal ultrasound were performed at the local laboratory of the Shebin El-Kom Fever Hospital. Laboratory investigations included the following – alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transferase (GGT), alkaline phosphatase, α-fetoprotein, albumin, and serum bilirubin, as well as hematological parameters such as red blood cells, white blood cells, and platelets. Hepatitis B surface antigen was assessed by enzyme-linked immunosorbent assay (ELISA), and quantitative PCR for hepatitis C RNA was carried out for each patient four times. The first PCR was carried out before initiating treatment to confirm the diagnosis of hepatitis C, the second after 1 month, the third was performed after 3 months of treatment, and the fourth was performed after 6 months of treatment Laboratory investigations including liver function tests (except for prothrombin time) and kidney function tests were performed on Integra 400 Autoanalyzer (Roche Diagnostics Corporation, Indianapolis, Indiana, USA). Prothrombin time and concentration were determined using Thromborel-S (human thromboplastin containing calcium; Behring Diagnostic Inc., Oxfordshire, England). Complete blood count was obtained using autoanalyzer ADVIA 2120 Hematology System (Erlangen, Germany). HCV antibodies detection and HCV quantitative real time PCR were carried out using automated Cobas Amplicor Analyzer (Roche Diagnostic Systems, Tokyo, Japan)
  • Serum IL-18 levels were measured by ELISA before treatment initiation, after 1 week, and after 3 months of treatment.


In the present study, the severity of liver disease was estimated according to the model for end-stage liver disease (MELD) score. The MELD score was calculated according to the following equation: 9.57 log (creatinine, mg/dl)+3.78 log (bilirubin, mg/dl)+11.2 log [international normalized ratio (INR)]+6.43, where 6.43 is the constant for liver disease etiology.

Meanwhile, the Child–Pugh score was obtained on the basis of five variables including ascites, encephalopathy, prothrombin time, and serum levels of bilirubin and albumin. Pugh assigned scores ranging from 1 to 3 to each of the variables in the classification. Classes A, B, and C were designated by criteria applied to the sum of individual scores, allowing to categorize patients in Child–Pugh grades A (5–6 points), B (7–9 points), and C (10–15 points).

Sample collection

Venous blood samples (5 ml) were collected under sterile conditions in serum-separator tubes from all patients and controls. Patients' serum samples were collected three times – before treatment, after 1 week, and after 3 months of treatment. After clot formation, samples were centrifuged at 1000g for 15 min for serum separation.

Sample preparation and storage

Serum samples were stored in sterile Eppendorf tubes at −20°C according to serial numbers as each patient had three samples. Repeated freeze–thaw cycles were avoided.

Quantification of interleukin-18 serum levels

Serum IL-18 levels were quantified using Boster's Human IL-18 ELISA Kit according to the manufacturer's instructions (Boster Biological Technology Co. Ltd, Pleasanton, California, USA). Boster's Human IL-18 ELISA Kit isbased on standard sandwich ELISA technology. A monoclonal antibody from mouse specific for IL-18 was precoated onto 96-well plates. Standards (Escherichia coli, S112-T270) and test samples were added to the wells. A biotinylated detection polyclonal antibody from goat specific for IL-18 was added subsequently and then followed by washing with PBS. The avidin–biotin–peroxidase complex was added, and unbound conjugates were washed away with PBS. Horseradish peroxidase (HRP) substrate tetramethylbenzidine was used to visualize HRP enzymatic reaction. Tetramethylbenzidine was catalyzed by HRP to produce a blue-colored product that changed into yellow after adding acidic stop solution. The density of yellow was proportional to the amount of human IL-18 in the sample captured in the plate.

Statistical analysis

The data collected were tabulated and analyzed using statistical package for the social sciences (SPSS) software (version 20; SPSS Inc., Chicago, Illinois, USA) on an IBM compatible computer, USA.

The results are expressed by applying ranges, mean ± SD, the χ2-test, the Mann–Whitney test, the T-test, the Kruskal–Wallis test, and P values. A P value of less than 0.05 was considered to be significant. Pearson's correlation was used for normally distributed quantitative variables, whereas Spearman's correlation was used for quantitative variables that were not normally distributed or when one of the variables was qualitative.


  Results Top


The patient group included 27 hepatitis C patients treated with sofosbuvir, ribavirin, and IFN. This group included 14 (51.9%) female and 13 (48.1%) male, aged 25–65 years with a mean value of 49.19 ± 11.50 years; 37% of patients were diabetic, and 30% were hypertensive. The control group included 15 normal individuals, nine (60.0%) female and six (40.0%) male, aged 22–67 years with a mean value of 42.93 ± 12.88 years. There were no statistically significant differences between the two studied groups with regard to age and sex. According to FibroScan, nine patients were F3 and 18 patients were F4. According to the Child–Pugh classification, five patients were of class A, seven patients were of class B, and 15 were of class C. MELD scores ranged from 6.40 to 44.70 with a mean value of 16.28 ± 11.8. About 14.8% of patients had MELD scores greater than or equal to 30, and about 14.8% of patients had MELD scores ranging from 20 to 29. The majority (40.7%) had scores ranging from 10 to 19, and 29.6% had scores less than nine [Table 1].
Table 1: Classification of the studied cases according to fibrosis stage, the Child-Pugh score, and the model for end-stage liver disease score

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The serum levels of IL-18 (pg/ml) in hepatitis C patients ranged from 320.0 to 850.0, with a mean value of 592.96 ± 112.68. The serum levels of IL-18 in the control group (pg/ml) ranged from 33.0 to 112.0, with a mean value of 54.40 ± 22.46. The serum levels of IL-18 were significantly higher in hepatitis C patients as compared with the control group (P < 0.001; [Table 2]).
Table 2: Comparison between cases and controls with regard to serum levels of interleukin-18

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Regarding the effect of treatment with sofosbuvir plus ribavirin and IFN on IL-18 serum levels among the studied cases, there was a significant difference among studied cases according to time of sample collection, and the highest range of IL-18 was 320.0–850.0, with a mean value of 592.96 ± 112.68, before treatment initiation; however, after 1 week of treatment the IL-18 range was 125.0–350.0, with a mean value of 240.63 ± 56.66. The lowest range of IL-18 (95.0–160.0) with a mean value of 123.48 ± 17.14 was obtained after 3 months of treatment [Table 3] and [Figure 1].
Table 3: Effect of the triple regimen of sofosbuvir, ribavirin, and interferon on interleukin-18 serum levels among the studied cases

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Figure 1: Effect of sofosbuvir with ribavirin and interferon on interleukin-18 levels among the studied cases. ttt, treatment.

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In this study, there was a correlation between serum levels of IL-18 among the studied group of cases and liver enzymes. There was a significant correlation between IL-18 and ALT (P < 0.001), whereas no significant correlation was found for AST, GGT, and alkaline phosphatase (P > 0.05). There was a high significant correlation between IL-18 and PCR (P < 0.001; [Table 4] and [Figure 2]).
Table 4: Correlation between serum levels of interleukin-18 among the studied group of cases and laboratory parameters

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Figure 2: Relationship between serum levels of interleukin-18 (IL-18) and PCR of the studied group of cases.

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In addition, in this study, there was a correlation between serum levels of IL-18 among the studied group of cases and other assessed laboratory parameters. There were significant differences in serum bilirubin, albumin, serum creatinine, and white blood cells (P = 0.01, 0.003, 0.02, and 0.04, respectively), but no significant differences in α-fetoprotein, blood urea, hemoglobin, and platelets were found (P > 0.05; [Table 4]).

In our study, there was a positive correlation between serum levels of IL-18 among the studied group of cases and fibrosis stage. There was a significant difference (P = 0.002) – the serum level of IL-18 was 320–590 pg/ml in F3 FibroScan, whereas the serum level of IL-18 was 500–850 pg/ml in F4 FibroScan. There was also a positive relationship between the serum levels of IL-18 among the studied group of cases and the Child–Pugh classification. IL-18 serum levels showed a statistically significant association with the Child–Pugh score (P = 0.008). Serum levels of IL-18 increased from class A to class B but with no statistically significant difference (P = 0.20); IL-18 serum levels significantly increased from class A to C (P = 0.003); and IL-18 serum levels increased from class B to C with a statistically significant difference (P = 0.05).

In addition, in our study, there was a significant positive correlation between the MELD score and the serum levels of IL-18 (P = 0.001). IL-18 serum levels increased significantly from grade I to II (P = 0.01); from grade I to III (P < 0.008); and from grade I to IV (P < 0.001). IL-18 serum levels increased significantly from grade II to IV (P < 0.006) [Table 5] and [Figure 3], [Figure 4]).
Table 5: Relationship between serum levels of interleukin-18 among the studied group of cases and fibrosis stage, the Child-Pugh score, and the prognosis score (model for end-stage liver disease score)

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Figure 3: Relationship between the serum levels of interleukin-18 among the studied group of cases and the Child–Pugh classification.

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Figure 4: Receiver operating characteristic (ROC) curve of interleukin-18 in cases of chronic hepatitis C.

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In our study, the receiver operating characteristic curve was used to detect the best cutoff point of IL-18 in cases of CHC. IL-18 level at a cutoff of 82.50 had a sensitivity of 89%, specificity of 90%, positive predictive value of 92%, negative predictive value of 85%, and accuracy of 89% in HCV detection. There was a highly significant difference in the area under the curve (P < 0.001) at 95% confidence interval of 0.98–1.0 [Table 6] and [Figure 5].
Table 6: Clinical performance of interleukin-18 in chronic hepatitis C patients

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Figure 5: Relationship between the serum levels of interleukin-18 among the studied group of cases and the prognosis score (model for end-stage liver disease).

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In the present study, the HCV virological response measured by quantitative PCR during and after treatment with sofosbuvir, ribavirin, and IFN was slightly different. After 3 months of treatment, 100% of cases were PCR negative, whereas after 6 months of treatment 24 (88.9%) patients remained PCR negative but three (11.1%) patients became PCR positive – that is, they had a relapse of HCV [Table 7].
Table 7: Hepatitis C virus virological response during and after treatment with sofosbuvir, ribavirin, and interferon

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  Discussion Top


This study was performed on patients from Shebin El-Kom Fever Hospital to determine the role of IL-18 in hepatitis C patients and to correlate its levels with hepatitis C treatment (sofosbuvir, ribavirin, and IFN). In addition, this study aimed to determine the relationship between IL-18 serum levels and severity of liver fibrosis.

The present study was conducted over the period from January 2015 to October 2015 and included 27 patients. We measured their serum IL-18 three times – the first sample was collected before treatment initiation; the second sample was collected after 1 week of treatment; and the third sample was collected after 3 months of treatment. Moreover, serum levels of IL-18 were measured in 15 age-matched and sex-matched healthy controls. In the present study, the mean age of hepatitis C patients was 49.19 ± 11.50 years. This was in agreement with the result of the study conducted by Salama et al.[11], in Egypt, where the mean age of liver cirrhosis patients was 47.08 ± 12.9. In this study, 48.1% of liver cirrhosis patients were male and 51.9% were female. On the other hand, results reported by El-Ansary et al.[12], in Egypt, 73.3% were male and 26.7% were female. This finding may be explained by the fact that male may be more frequently exposed to HCV infection, which is the major cause of liver cirrhosis in Egypt, as they have more risk factors including schistosomal infection, shaving accidents, and exposure to operations, accidents, and blood transfusions. In this study, about 37% of patients were diabetic. Schuppan and Afdhal[13] reported that type II diabetes is one of the clinical features of liver cirrhosis and occurs in 15–30% of cirrhosis patients, and this was explained by disturbed glucose utilization.

In the present study, about 30% of liver cirrhosis patients were hypertensive. However, Henriksen and Moller[14]stated that the prevalence of arterial hypertension in patients with chronic liver disease (cirrhosis) is much lower (only 3–7%). The same author explained these findings in patients with cirrhosis by vasodilatation with low overall systemic vascular resistance.

In the present study, all CHC patients had fibrosis grade 3 and grade 4 (33.3 and 66.7%, respectively). This was in agreement with the results of the study conducted by Cacopardo et al.[15], where most CHC patients had fibrosis grade 3 and grade 4 (33.3 and 33.3%, respectively).

According to the Child–Pugh classification, about 18.5% of patients were class A, 25.9% of patients were class B, and 55.6% were class C. In line with a study conducted by Attia et al.[16], about 60% of patients had a Child–Pugh score stage C that amounts to severe liver disease. This could be attributed to the fact that most of our patients were admitted at a late stage of the disease.

In the present study, the severity of liver disease was estimated according to the MELD score. The range of the MELD score in patients was 6.40–44.70, with a mean value of 16.28 ± 11.87, in agreement with the results ofSharawey et al.[17], in Egypt, with a mean value of the MELD score of 18.09 ± 4.7.

In the present study, serum levels of IL-18 in hepatitis C patients were significantly higher with a mean value of 592.96 ± 112.68 when compared with the control group. This result was in agreement with the study conducted by Sharma et al.[18], with a mean value of serum IL-18 (pg/ml) of 865.4 ± 283.4 (P < 0.005) when compared with the control groups (297.6 ± 88.6). Our data confirmed the proinflammatory role of IL-18 in HCV infection, and IL-18 levels were found to reflect HCV-induced inflammation and hepatic injury. It is possible that upregulation of IL-18 production has a role in the development of chronicity and accelerates the evolution of chronic hepatitis toward cirrhosis. As Th1 cells have been implicated in the pathogenesis of HCV infection, IL-18 may be involved in the mechanisms of tissue injury in hepatitis C.

In the present study, there were significant differences in serum levels of IL-18 (pg/ml) in the studied group of patients, because of the effect of the antiviral drug sofosbuvir – the mean value of serum IL-18 before treatment was 592.96 ± 112.68, the mean value after 1 week of treatment was 240.63 ± 56.66, and the mean value of serum IL-18 after 3 months of treatment was 123.48 ± 17.14. Our data are in agreement with the study conducted by Vecchiet et al.[19], as in this study pretreatment IL-18 serum levels were significantly higher than post-treatment values (362 ± 66 vs. 191 ± 39 pg/ml, P < 0.01). They explained this finding by the fact that patients whose post-treatment samples showed improvement in liver histology also showed a significant reduction in serum IL-18 levels (from 388 ± 101 to 101 ± 56 pg/ml, P < 0.001).

The present study showed that the concentrations of serum IL-18 in CHC patients were positively correlated with the level of HCV RNA (r = 0.90, P < 0.001). This was in agreement with Hegazy and Henawy[20], who revealed that the concentrations of serum IL-18 in CHC patients were positively correlated with the serum level of HCV RNA (r = 0.76, P < 0.0001), and also the study by Elsherif et al.[21], who showed a strong, significant, positive correlation between serum IL-18 and results of PCR (r = 0.6, P < 0.001), and this may suggest that IL-18 is an early marker for HCV infection even before ALT elevation.

Our study revealed that the concentrations of serum IL-18 in CHC patients were positively correlated with the levels of serum ALT (r = 0.90, P < 0.05). Similarly, Wang et al.[22] showed that the concentrations of serum IL-18 in CHC patients were positively correlated with the levels of serum ALT and AST (r = 0.388, P < 0.001; r = 0.400, P < 0.001, respectively). Moreover, Hegazy and Henawy[20] found that the concentrations of serum IL-18 in CHC patients were positively correlated with the levels of serum ALT and AST (r = 0.8, P < 0.0001; r = 0.82, P < 0.0001, respectively). In addition, in a study conducted by Cacopardo et al.[15], serum IL-18 levels were significantly lower along with normal ALT and AST levels in comparison with hyper-ALT and hyper-AST levels, respectively (P < 0.05). As IL-18 appears to act at a very early stage of T-lymphocyte activation, triggering one of the earliest steps of the cytokine cascade should have the most pronounced and long-lasting effects on T-lymphocyte responses. IL-18 may also induce macrophages to produce tumor necrosis factor-α and nitric oxide and accounts for the induction of cell death. Furthermore, it enhances FasL-mediated killing by natural killer and cytotoxic T cells; hence, is expected to have positive effects against viral infections. IL-18 directly induces FasL expression in the liver and also exhibits antitumor effects through activation of natural killer cells leading to hepatocyte death and elevation of ALT and AST.

In the present study, serum IL-18 levels were significantly associated with the Child–Pugh classification of chronic liver disease (P < 0.008). Serum levels of IL-18 (pg/ml) increased from class A to B (the mean value of serum levels of IL-18 in class A was 484.0 ± 96.07 compared with 557.14 ± 92.14 in class B, P < 0.2). IL-18 serum levels were significantly increased from class B to C (the mean value of serum levels of IL-18, in pg/ml, in class B was 557.14 ± 92.14 compared with 646.50±97.01 in class C, P < 0.05). Sun et al.[23] documented that the serum concentration of IL-18 increased with Child–Pugh scores (P < 0.001) – the levels of IL-18 in Child–Pugh score B and C patients were increased compared with Child–Pugh score A patients, whereas there was no significant difference between Child–Pugh score B and C patients. In addition, Zhao et al.[24] agreed with our study and explained that IL-18 production by Kupffer cells and macrophages was higher in liver cirrhosis patients with Child–Pugh C scores compared with those with Child–Pugh A or B scores.

In the present study, IL-18 serum levels were significantly correlated with the MELD score (P < 0.001). This indicates that high IL-18 serum levels may reflect the severity of liver disease and is associated with deterioration of liver function and subsequent mortality of CHC patients. This was in agreement with the results of Bingold et al.[25], in Germany, and those of Kronenberger et al.[26] and Park et al.[27] who reported a positive correlation between serum IL-18 and liver injury in a mouse model of T-cell hepatitis.

We also investigated whether the individual parameters of the MELD score were correlated with serum IL-18 levels in our patients, and we found that creatinine, INR, and bilirubin were correlated with serum IL-18 levels. There were significant positive correlations between serum levels of IL-18, bilirubin (P < 0.01), INR (P < 0.02), as well as serum creatinine (P < 0.02). This was in agreement with the results of Kronenberger et al.[26]. IL-18 serum levels may reflect the severity of liver disease in which liver synthetic capacity is reduced, providing an explanation for increased INR with increased IL-18 serum levels. In addition, renal affection may occur in advanced liver disease (hepatorenal syndrome), explaining the positive correlation between serum IL-18 levels and creatinine.

We also observed that serum IL-18 levels differed significantly among patients with different stages of fibrosis with higher levels in advanced fibrosis stages (P < 0.001). The serum IL-18 level in CHC patients with fibrosis score F3 was 503.33 ± 76.32 and it increased to 637.77 ± 101.49 in F4 fibrosis stage with a P value of 0.002. The same findings were demonstrated by Cacopardo et al.[15], who studied the correlation between serum IL-18 levels and severity of liver fibrosis; they reported that patients with fibrosis score F1–F2 had significantly lower IL-18 concentrations than patients with a more advanced fibrosis score (F3–F4) (268 ± 59 vs. 431 ± 111 pg/ml, P < 0.01). In addition, study by Hegazy and Henawy[20] revealed that IL-18 levels were significantly elevated in patients with higher fibrosis than those with lower fibrosis stages. Serum levels of IL-18 in CHC patients with fibrosis score F3 were significantly higher than CHC patients with fibrosis score F2 and F1 (P = 0.0013). Serum IL-18 levels in CHC patients with fibrosis score F2 were significantly higher than CHC patients with fibrosis score F1 (P < 0.0001). Marvie et al.[28] revealed that IL-18 overexpression was associated with the development of HCV-related liver fibrosis, and showed that IL-18 is upregulated in human and murine fibrosis, and is mainly produced by sinusoidal endothelial cells and activated hepatic stellate cells.

In addition, Hammerich and Tacke[29] found that overexpression of IL-18 specifically in the liver was sufficient to induce fibrosis without administration of chemicals, demonstrating the powerful profibrotic role of IL-18.

In our study, we found that three (11.1%) patients among the studied cases had relapse and became PCR positive; this is in agreement with Lawitz et al.[30], who found that about 13% of cases had relapse after 6 months of treatment. In addition, Rutter et al.[31] revealed that about 13% of cases had relapse after 8 months of treatment. They explained that there are theoretical concerns regarding the durability of HCV eradication after successful direct-acting antiviral-based triple therapy. During direct-acting antiviral treatment, resistance-associated variants with reduced replication fitness compared with the wild type virus may emerge. If these resistance-associated variants cannot be eliminated by the required peg-IFN/ribavirin backbone, strains with reduced replication fitness may persist in low concentrations and may account for late relapses.

Moreover, a study conducted by Hartman et al.[32] explained relapse due to cirrhosis, previously failed dual therapy (peg-IFN/ribavirin) and HCV viral load over 1 million IU/ml; however, Pawlotsky[33] explained that the presence of more than 15% of HCV variants with resistance to NS5A inhibitors in the patient's quasispecies population at baseline affects the chances for an sustained virological response, especially in specific groups of patients such as those with genotype 1a or 3 infection and cirrhosis and/or previous nonresponders to peg-IFN-based treatment. At virological failure, drug-resistant viruses dominate.


  Conclusion Top


From this study, we can conclude that hepatitis C patients have significant elevation in serum levels of IL-18 when compared with healthy people, and the severity of disease was directly associated with higher serum levels of IL-18.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

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