A role for the Tec family kinase ITK in regulating SEB-induced interleukin-2 production in vivo via c-jun phosphorylation.
BACKGROUND
Exposure to Staphylococcal Enterotoxin B (SEB), a bacterial superantigen secreted by the Gram-positive bacteria Staphyloccocus aureus, results in the expansion and eventual clonal deletion and anergy of Vbeta8+ T cells, as well as massive cytokine release, including Interleukin-2 (IL-2). This IL-2 is rapidly secreted following exposure to SEB and may contribute to the symptoms seen following exposure to this bacterial toxin. The Tec family kinase ITK has been shown to be important for the production of IL-2 by T cells stimulated in vitro and may represent a good target for blocking the production of this cytokine in vivo. In order to determine if ITK represents such a target, mice lacking ITK were analyzed for their response to SEB exposure.


RESULTS
It was found that T cells from mice lacking ITK exhibited significantly reduced proliferative responses to SEB exposure in vitro, as well as in vivo. Examination of IL-2 production revealed that ITK null mice produced reduced levels of this cytokine in vitro, and more dramatically, in vivo. In vivo analysis of c-jun phosphorylation, previously shown to be critical for regulating IL-2 production, revealed that this pathway was specifically activated in SEB reactive Vbeta8+ (but not non-reactive Vbeta6+) T cells from WT mice, but not in Vbeta8+ T cells from ITK null mice. However, toxicity analysis indicated that both WT and ITK null animals were similarly affected by SEB exposure.


CONCLUSIONS
These data show that ITK is required for IL-2 production induced by SEB in vivo, and may regulate signals leading IL-2 production, in part by regulating phosphorylation of c-jun. The data also suggest that perturbing T cell activation pathways leading to IL-2 does not necessarily lead to improved responses to SEB toxicity.
Ragin
Melanie J
MJ
Center for Molecular Immunology & Infectious Disease, Department of Veterinary Science, The Pennsylvania State University, University Park, PA 16802, USA. mjr306@psu.edu
Hu
Jianfang
J
Henderson
Andrew J
AJ
August
Avery
A
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D017635:Clonal Anergy / Q000187:drug effects*; D004768:Enterotoxins / Q000276:immunology / Q000494:pharmacology / Q000502:physiology* / Q000633:toxicity; D018398:Homeodomain Proteins / Q000502:physiology; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000235:genetics; D008213:Lymphocyte Activation / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D018089:Superantigens / Q000276:immunology / Q000494:pharmacology / Q000502:physiology* / Q000633:toxicity; D016176:T-Lymphocyte Subsets / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*
D004768:Enterotoxins; D018398:Homeodomain Proteins; D007376:Interleukin-2; D016755:Proto-Oncogene Proteins c-jun; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens; C064658:RAG-1 protein; C031818:enterotoxin B, staphylococcal; D011505:Protein-Tyrosine Kinases; C080813:emt protein-tyrosine kinase