Intragraft Localization of Activated Nuclear Factor B in Recurrent Hepatitis C Virus Disease Following Liver Transplantation ANDERSON S. GAWECO, 1,2 RUSSELL H. WIESNER , 4 MICHAEL PORAYKO, 5 V INOD K. RUSTGI, 6 S HERRI Y ONG, 2 RAZA HAMDANI, 1 J AMES HARIG, 1 GREGORIO CHEJFEC, 2 KENNETH D. MCCLATCHEY , 2 AND DAVID H. V AN THIEL 1,3 Nuclear factor B (NF- B) is activated during viral infection and is central to the regulation of host immune responses. The NF- B activation status and its morphologi- cal sources were assessed by immunohistochemistry in allograft biopsy specimens of orthotopic liver transplanta- tion patients with recurrent hepatitis C virus (HCV). Hepatocellular NF- B immunostaining was detected in HCV cases compared with controls (nontransplant: P F .001; transplant: P  .006), which correlated with the number of NF- B positive hepatocytes ( P  .007) and contrasted to the absent to weak staining of controls (nontransplant: P  .001; transplant: P  .009). Enhanced NF- B staining of cytokeratin 19–positive bile ducts and proliferating ductules in the HCV group was in contrast to controls. Intense NF- B immunoreactivity was detected in CD68-positive Kupffer cells and macrophages of all HCV specimens compared with a few controls (nontransplant: P F .001; transplant: P  .001) and contrasted to the weak staining of controls (nontransplant: P F .001; transplant: P  .001). NF- B–positive immunoreactivity correlated with the number of T cell receptor (TCR) /-positive lymphocytes ( P F .001), which was not observed in controls. In those HCV cases showing evidence of necroin- flammatory activity (grade) and individual features of portal inflammation, periportal inflammation/piecemeal ne- crosis, lobular inflammation, and fibrosis (stage), higher NF- B staining intensity scores within bile ducts, proliferat- ing ductules, hepatocytes (piecemeal necrosis: P  .016; stage: P  .030), and lymphocytes (stage: P  .044) and increased number of NF- B–positive cells within bile ducts, proliferating ductules (grade, lobular inflammation, piece- meal necrosis, stage: P  .022), hepatocytes, and lympho- cytes were observed. Increased staining intensity and fre- quency of NF- B–positive cells were similarly observed in HCV-positive allografts obtained from patients under tacro- limus- compared with cyclosporine-based immunosuppres- sion. These data implicate an immunoregulatory role of intragraft NF- B activation in the pathogenesis and progres- sion of posttransplantation HCV disease recurrence. (HEPA- TOLOGY 2000;31:1183-1191.) An estimated 170 million people worldwide and nearly 4 million people in the United States alone are infected with the hepatitis C virus (HCV). 1,2 Up to 85% of the individuals infected with HCV develop a chronic disease course associ- ated with an increased risk of cirrhosis and hepatocellular carcinoma. 1,3 Currently, end-stage liver disease secondary to HCV infection is the leading indication for orthotopic liver transplantation (OLTx) in the United States. 4 Recurrence of HCV infection after OLTx of HCV patients is universal and associated with HCV viremia and high intragraft HCV antigen levels. 5-9 More than half of OLTx patients trans- planted because of HCV-related disease will develop histo- pathologic evidence of chronic hepatitis 10-12 and some will develop a severe form of fibrosing cholestatic hepatitis associated with progressive allograft failure, 13,14 whereas others will develop allograft cirrhosis 15 and de novo hepatocel- lular carcinoma. 16 The specific pathogenetic mechanisms contributing to recurrent HCV infection and disease progres- sion in immunocompromised transplant patients remain ill defined. Worse yet, the limited understanding of the pathogen- esis of HCV infection in immunocompetent individuals provides little insight into the development of a successful therapeutic strategy for transplant recipients infected with the HCV. Substantial evidence has implicated a pivotal role for liver-specific immune-mediated mechanisms that include the production of inflammatory mediators and activation of host effector cells, in the development and progression of the liver injury associated with chronic HCVinfection in immunocom- petent individuals. 17-20 Moreover, recent investigations have documented a low number of apoptotic hepatocytes in HCV-infected liver tissue, 21-23 perhaps as a critical mechanism whereby uninhibited viral replication can occur. 24,25 The transcription factor nuclear factor B (NF-B), initially identified as an inducer of B-cell–specific gene expresssion, 26 is known to regulate the HCV-specific expression of several inflammatory mediator genes and inhibition of apoptotic cell death, which may influence the replication of HCV and the Abbreviations: HCV , hepatitis C virus; OLTx, orthotopic liver transplantation; NF-B, nuclear factor B; TCR, T-cell receptor; mAb, monoclonal antibody; BEC, biliary epithelial cell; KC, Kupffer cell; PBS, phosphate-buffered saline; CsA, cyclosporine A; ER, endoplasmic reticulum. From the Liver Transplant Program, Departments of 1 Medicine, 2 Pathology, and 3 Surgery, Loyola University Medical Center, Loyola University Chicago, Maywood, IL; 4 Liver Transplant Center, Department of Medicine, Mayo Clinic, Rochester, MN; 5 Liver Transplantation Center, Division of Gastroenterology and Hepatology, Thomas Jefferson University Hospital, Philadelphia, PA; and 6 Liver Transplant Program, Division of Transplant Surgery, Department of Surgery, Georgetown University Medical Center, Washington, DC. Received August 6, 1999; accepted February 7, 2000. Address reprint requests to: Anderson S. Gaweco, M.D., Ph.D., Assistant Professor of Medicine and Pathology, Liver Transplant Program, Division of Gastroenterology, Hepatology, and Nutrition, Loyola University Medical Center, Loyola University Chicago, 2160 South First Avenue, Maywood, IL 60153. E-mail: agaweco@luc.edu; fax: 708-216-0423. Copyright  2000 by the American Association for the Study of Liver Diseases. 0270-9139/00/3105-0021$3.00/0 doi:10.1053/he.2000.6983 1183