Concomitant Inhibition of Janus Kinase 3 and Calcineurin-Dependent Signaling Pathways Synergistically Prolongs the Survival of Rat Heart Allografts

• Published in: The Journal of immunology (1950) Vol. 166; no. 6; pp. 3724 - 3732
• Main Authors: Behbod, Fariba, Erwin-Cohen, Rebecca A, Wang, Mou-Er, Trawick, Barton W, Qu, Xienui, Verani, Regina, Kahan, Barry D, Stepkowski, Stanislaw M, Kirken, Robert A
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 15.03.2001
• Subjects: Animals; Calcineurin - physiology; Calcineurin Inhibitors; Cell Division - drug effects; Cell Division - immunology; Cell Line; Cell Movement - drug effects; Cell Movement - immunology; Cell Nucleus - drug effects; Cell Nucleus - immunology; Cell Nucleus - metabolism; Cells, Cultured; DNA - metabolism; DNA-Binding Proteins - antagonists & inhibitors; DNA-Binding Proteins - metabolism; Enzyme Activation - drug effects; Enzyme Activation - immunology; Enzyme Inhibitors - administration & dosage; Enzyme Inhibitors - pharmacology; Graft Enhancement, Immunologic - methods; Graft Survival - drug effects; Graft Survival - immunology; Heart Transplantation - immunology; Heart Transplantation - pathology; Humans; Immunosuppressive Agents - administration & dosage; Immunosuppressive Agents - pharmacology; Injections, Intraperitoneal; interleukin 2 receptors; Interleukin-2 - antagonists & inhibitors; Interleukin-2 - physiology; Jak3 kinase; Janus Kinase 3; Leukocytes, Mononuclear - drug effects; Leukocytes, Mononuclear - immunology; Milk Proteins; Phosphorylation - drug effects; Protein Binding - drug effects; Protein Binding - immunology; Protein-Tyrosine Kinases - antagonists & inhibitors; Protein-Tyrosine Kinases - metabolism; Rats; Rats, Inbred ACI; Rats, Inbred Lew; Receptors, Interleukin-2 - antagonists & inhibitors; Receptors, Interleukin-2 - biosynthesis; Serine - metabolism; Signal Transduction - drug effects; Signal Transduction - immunology; STAT5 Transcription Factor; T-Lymphocytes - cytology; T-Lymphocytes - drug effects; T-Lymphocytes - immunology; T-Lymphocytes - metabolism; Trans-Activators - antagonists & inhibitors; Trans-Activators - metabolism; Tumor Suppressor Proteins; Tyrosine - metabolism; Tyrphostins - administration & dosage; Tyrphostins - pharmacology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.166.6.3724

The cytoplasmic localized Janus tyrosine kinase 3 (Jak3) is activated by multiple cytokines, including IL-2, IL-4, and IL-7, through engagement of the IL-2R common gamma-chain. Genetic inactivation of Jak3 is manifested as SCID in humans and mice. These findings have suggested that Jak3 represents a pharmacological target to control certain lymphoid-derived diseases. Using the rat T cell line Nb2-11c, we document that tyrphostin AG-490 blocked in vitro IL-2-induced cell proliferation (IC(50) approximately 20 microM), Jak3 autophosphorylation, and activation of its key substrates, Stat5a and Stat5b, as measured by tyrosine/serine phosphorylation analysis and DNA-binding experiments. To test the notion that inhibition of Jak3 provides immunosuppressive potential, a 7-day course of i.v. therapy with 5-20 mg/kg AG-490 was used to inhibit rejection of heterotopically transplanted Lewis (RT1(l)) heart allografts in ACI (RT1(a)) recipients. In this study, we report that AG-490 significantly prolonged allograft survival, but also acted synergistically when used in combination with the signal 1 inhibitor cyclosporin A, but not the signal 3 inhibitor, rapamycin. Finally, AG-490 treatment reduced graft infiltration of mononuclear cells and Stat5a/b DNA binding of ex vivo IL-2-stimulated graft infiltrating of mononuclear cells, but failed to affect IL2R alpha expression, as judged by RNase protection assays. Thus, inhibition of Jak3 prolongs allograft survival and also potentiates the immunosuppressive effects of cyclosporin A, but not rapamycin.