Journal of Experimental and Integrative Medicine DOI: 10.5455/jeim.150514.or.105 www.jeim.org J Exp Integr Med ● Jul-Sep 2014 ● Vol 4 ● Issue 3 175 INTRODUCTION Hepatitis B virus (HBV) infection is a majority problem of public health in the world. An estimated 350-400 million people worldwide are chronically infected with HBV [1,2]. Wang et al. [3] have reported approximately 250,000 deaths to happen each year as a consequence of hepatic failure, cirrhosis and hepatocellular carcinoma. The cytokine-mediated immunity plays a crucial role in determining of hepatitis infections overcome. The variations in cytokine production may influence the outcome of cytokine- based immunotherapy [4,5]. Cytokine gene polymorphisms were associated with the severity of the liver disease in patients with HBV infection [6]. Interleukin (IL)-18 is a pleiotropic pro- inflammatory cytokine. It is a member of the IL-1 family and was first identified as interferon-gamma inducing factor [7-9]. IL-18 is synthesized as a 24-kDa proform which is activated to the bioactive 18-kDa mature IL-18 [10]. It is produced mainly by monocytes, macrophages, Kupffer cells, and intestinal epithelial cells [11,12]. The human IL-18 (hIL-18) gene is located on chromosome 11q22.2-q22.3 and is composed of six exons and five introns [13]. Furthermore, IL-18 has a key role in the induction of both Th1 and Th2 cytokines and, thereby, modulates their immune responses. Hence, IL-18 has been shown to play a protective role in the host defense towards different sources of infection or to have a pathological role in HBV [14]. Many polymorphisms in the promoter region of the IL-18 gene have been identified. These polymorphisms have attracted widespread attention. In this study, we analyzed IL-18 single- nucleotide polymorphisms (SNP) and identified an SNP in the promoter region of the IL-18 gene that is associated with the infected HBV formalin-fixed paraffin-embedded liver tissues. Investigation of interleukin-18 polymorphisms in hepatitis B virus carriers, chronic hepatitis, and cirrhosis patients Serap Yalcin 1 , Seref Demirbas 2 , Onder Onguru 3 Original Research 1 Department of Food Engineering, Faculty of Engineering and Architecture, Ahi Evran University, Faculty of Engineering and Architecture, Kirsehir, Turkey, 2 Department of Internal Medicine, Gulhane Military Medical Academy, Ankara, Turkey, 3 Department of Pathology, Gulhane Military Medical Academy, Ankara, Turkey Address for correspondence: Address for correspondence: Serap Yalcin, Ahi Evran University, Faculty of Engineering and Architecture, Kirsehir, Turkey. E-mail: serapyalcin1982@ gmail.com; syalcin@ ahievran.edu.tr Received: Received: April 25, 2014 Accepted: Accepted: May 15, 2014 Published: Published: August 27, 2014 ABSTRACT Objective: Interleukin-18 (IL-18) has been shown to play a protective role in the host defense towards different sources of infection or to have a pathological role in hepatitis B virus (HBV). Methods: For the purposes of this study, we analyzed IL-18 single-nucleotide polymorphisms in HBV carrier, chronic hepatitis, cirrhosis, and noninfected individuals. Presence of the IL-18 genotyping was performed using the polymerase chain reaction amplification and DNA sequencing. Results: Significant associations were detected between the IL-18 rs187238 (G/C) polymorphism and infected patients. Conclusion: Based on our data, there were no significant associations between the IL-18 rs61667799(G/T), rs5744227(C/G), rs5744228(A/G) polymorphism in Turkish HBV-infected and noninfected individuals with HBV. KEY WORDS: Chronic hepatitis, cirrhosis, hepatitis B, interleukin-18, polymorphism