Osteopontin regulates interleukin-17 production in hepatitis Hongyan Diao a , Xiangdong Liu b , Zhongwen Wu a , Lei Kang a , Guangying Cui a , Junko Morimoto c , David T. Denhardt d , Susan Rittling e , Yoichiro Iwakura f , Toshimitsu Uede c , Lanjuan Li a,⇑ a State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang 310003, China b College of Materials and Textile, Zhejiang Sci–Tech University, Hangzhou 310018, China c Molecular Immunology, Institute for Genetic Medicine, Hokkaido University, Sapporo 0600815, Japan d Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, United States e The Forsyth Institute, The Fenway, Boston, MA 02115, United States f Center for Experimental Medicine, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan article info Article history: Received 8 September 2011 Received in revised form 19 June 2012 Accepted 21 June 2012 Available online 19 July 2012 Keywords: Osteopontin IL-17 Chronic hepatitis B Concanavalin A-induced hepatitis abstract The overexpression of osteopontin is associated with various inflammatory liver diseases. Interestingly, each of these diseases is also associated with IL-17 expression. Therefore, we sought to determine whether there is any mechanistic link between osteopontin and IL-17. Herein we show that IL-17 and osteopontin levels were significantly increased in patients with chronic hepatitis B. We found that IL-17 and osteopontin levels increased similarly in mice with concanavalin A-induced hepatitis. Both osteopontin- and IL-17-deficient mice were resistant to concanavalin A-induced hepatic injury. In addi- tion, osteopontin markedly induced IL-17 expression by leukocytes (from humans and mice). This effect could be blocked by a specific antibody against osteopontin. b3 integrin (one of the osteopontin recep- tors) was critically involved in the induction of IL-17 production by osteopontin. Osteopontin-induced IL-17 expression was mediated through the p38, JNK, and NF-jB pathways. These findings suggest that osteopontin regulates IL-17 production during the pathogenesis of hepatitis and provide new evidence for the critical roles of osteopontin and IL-17 in hepatitis. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction More than 350 million people worldwide suffer from infection with hepatitis B virus (HBV) and are at risk of developing cirrhosis of the liver and hepatocellular carcinoma [1]. HBV itself is noncytopathic, but immune-mediated liver damage often occurs in patients with either acute or chronic HBV infection. It has been demonstrated that HBV-specific cytotoxic T lymphocytes (CTL) and CD4+ T lymphocytes are essential for the control of HBV infection [2,3]. Activation of CD4+ T cells produces antigen-specific T helper 1 (Th1), T helper 2 (Th2), and T regulatory (Treg) cells. These cell populations generate cytokines, which regulate each other to cre- ate a dynamic balance among these regulatory molecules. Thus, the role of the coordinated adaptive immune response is to gener- ate and regulate complementary effector mechanisms that lead to the elimination of HBV-infected cells [4,5]. Newly identified CD4+ T effector cells have been named Th17 cells. These cells have been characterized as preferentially produc- ing interleukin (IL)-17A (also known as IL-17), IL-17F, IL-21, IL-22, and IL-26 in humans [6]. Th17 cells and their effector cytokines are increasingly being recognized as key determinants in the patho- genesis of autoimmune diseases, malignant tumors, and alcoholic liver disease [7–9]. Recently, two studies have reported that the percentage of Th17 cells in peripheral blood was significantly in- creased in patients with chronic hepatitis B (CHB) and correlated positively with the severity of liver damage in these patients [10,11]. However, the relationships among cytokines derived from Th1, Th2, and Th17 cells in HBV-associated acute or chronic liver disease remain to be clarified. Concanavalin A (Con A)-induced hepatitis has been widely used to investigate the molecular mechanisms underlying T-cell-medi- ated liver injury. In this murine model, a single injection of Con A rapidly induces liver necrosis and inflammation together with elevated levels of a wide variety of cytokines, including Th1- (inter- feron (IFN)-c), Th2- (IL-4) and Th17-derived cytokines (IL-17 and IL-22) [12–14]. However, the role of IL-17 in Con A-induced hepa- titis remains to be elucidated. Osteopontin (OPN) is known not only as an extracellular matrix protein, supporting the adhesion and migration of inflammatory cells, but also as an immunoregulatory cytokine [15,16]. Upregu- lated expression of OPN has been associated with a variety of inflammatory and autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (RA), and atherosclerosis [17,18]. We demonstrated that OPN was also associated with 1043-4666/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cyto.2012.06.287 ⇑ Corresponding authors. Tel./fax: +86 571 87236459 (L. Li). E-mail addresses: toshi@igm.hokudai.ac.jp (T. Uede), ljli@zju.edu.cn (L. Li). Cytokine 60 (2012) 129–137 Contents lists available at SciVerse ScienceDirect Cytokine journal homepage: www.journals.elsevier.com/cytokine