Autoimmune, Cholestatic and Biliary Disease

Natural killer T cell dysfunction in CD39-null mice protects against concanavalin A–induced hepatitis

Beldi, Guido^1,4; Wu, Yan¹; Banz, Yara¹; Nowak, Michael²; Miller, Lindsay¹; Enjyoji, Keiichi¹; Haschemi, Arvand¹; Yegutkin, Gennady G.³; Candinas, Daniel⁴; Exley, Mark²; Robson, Simon C.^1*

Author Information

¹Liver and Transplantation Centers, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA

²Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA

³MediCity Research Laboratory, University of Turku, National Public Health Institute, Turku, Finland

⁴Department of Visceral and Transplant Surgery, Inselspital, University Hospital, Bern, Switzerland

^* Address reprint requests to: Liver and Transplantation Centers, Room 301, Research North, Beth Israel Deaconess Medical Center, 99 Brookline Avenue, Boston, MA 02215

Email:[email protected]

Received 3 September 2007; Accepted 21 April 2008

Published online in Wiley InterScience (www.interscience.wiley.com).

Supported by National Institutes of Health; Grant Numbers: HL57307 HL63972 HL076540; Grant sponsor: Swiss National Research Foundation; Grant Numbers: PASMA-115700 PBBEB-112764 DK 066917.

This work was presented in part at Digestive Diseases Week, Washington, DC, May 17-22, 2007.

Potential conflict of interest: Nothing to report.

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Hepatology 48(3):p 841-852, September 2008. | DOI: 10.1002/hep.22401

Abstract

Concanavalin A (Con A)–induced injury is an established natural killer T (NKT) cell–mediated model of inflammation that has been used in studies of immune liver disease. Extracellular nucleotides, such as adenosine triphosphate, are released by Con A–stimulated cells and bind to specific purinergic type 2 receptors to modulate immune activation responses. Levels of extracellular nucleotides are in turn closely regulated by ectonucleotidases, such as CD39/NTPDase1. Effects of extracellular nucleotides and CD39 on NKT cell activation and upon hepatic inflammation have been largely unexplored to date. Here, we show that NKT cells express both CD39 and CD73/ecto-5′-nucleotidase and can therefore generate adenosine from extracellular nucleotides, whereas natural killer cells do not express CD73. In vivo, mice null for CD39 are protected from Con A–induced liver injury and show substantively lower serum levels of interleukin-4 and interferon-γ when compared with matched wild-type mice. Numbers of hepatic NKT cells are significantly decreased in CD39 null mice after Con A administration. Hepatic NKT cells express most P2X and P2Y receptors; exceptions include P2X3 and P2Y11. Heightened levels of apoptosis of CD39 null NKT cells in vivo and in vitro appear to be driven by unimpeded activation of the P2X7 receptor.Conclusion:CD39 and CD73 are novel phenotypic markers of NKT cells. Deletion of CD39 modulates nucleotide-mediated cytokine production by, and limits apoptosis of, hepatic NKT cells providing protection against Con A–induced hepatitis. This study illustrates a further role for purinergic signaling in NKT-mediated mechanisms that result in liver immune injury. (Hepatology 2008.)

Abbreviations: αGalCer, α-galactosylceramide; ADP, adenosine diphosphate; ALT, alanine aminotransferase; AMP, adenosine monophosphate; ATP, adenosine triphosphate; Con A, concanavalin A; FITC, fluorescein isothiocyanate; IFN-γ, interferon-γ; IL-4, interleukin-4; MNC, mononuclear cell; NKT, natural killer T; PCR, polymerase chain reaction; RT, reverse-transcription; RT-PCR, reverse-transcription polymerase chain reaction; TLC, thin layer chromatography; Treg, regulatory T cell.