Project 1: In recent years, evidence has been presented which posits a key role for the IL-12R beta2 chain in Th1/Th2 T cell differentiation. In particular, it has been suggested that down-regulation of this receptor and consequent cessation of IL-12 signaling is a prerequisite of Th2 T cell development. In the present study we examined this proposition by determining the effect of IL-12R beta2 chain signaling on beta2-chain transfected Th2 T cell lines and on Th2 T cells derived from mice bearing an IL-12R beta2 chain transgene. Using the first approach, we showed that D10.G4.1 T cells, a well-established Th2 T cell line, can be transfected with a vector containing an IL-12R beta2 chain cDNA under the control of a CD2 promotor and locus control region. Such T cells express an IL-12R composed of the beta1 and beta2 chains and transduce a STAT4 signal. However, when stimulated by antigen in the presence of IL-12, they do not produce significant amounts of IFN-gamma or manifest reduced IL-4 production. Using the second approach, we showed initially that double transgenic mice bearing both a transgene for the OVA TCR and a gene for the IL-12R beta2 chain do in fact overexpress IL-2R beta2 chains upon stimulation with OVA. We then showed that Th2 T cell lines derived from such mice and expressing the IL-12R beta2 chain produce minimal amounts of IFN- gamma upon restimulation with IL-12 and do not manifest reduced production of IL-4. Taken together, these studies show that Th2 T cells, cannot be made to revert to a Th1 phenotype even when re- stimulated through a competent IL-12 receptor. It is thus evident that down-regulation of the IL-12R beta2 chain is not the controlling factor in the switch to Th2 T cell development. Project 2: The role of TGF- beta1 in the regulation of T cell responses continues to be perplexing, possibly because its role is influenced by the type of T cell being regulated and the presence or absence of modifying cytokines in the microenvironment. In the present study, we attempted to overcome such problems by assessing TGF-beta1 effects under highly defined conditions. In initial studies we showed that TGF-beta1 has a profound inhibitory effect on na?ve CD4+ T cell responses whether the cells are stimulated under neutral, Th1 and Th2 priming conditions. In addition, if naive T cells are primed in the presence of TGF-beta1 they exhibit secondary anti-CD3/anti-CD28-induced and antigen-specific immune responses even in the absence of TGF-beta during secondary stimulation; thus, TGF-beta1 has an imprinting on ?carry-over? inhibitory effect. The impaired secondary immune response was not reversed by the addition of IL-2 and is not due to reduced expression of co-stimulatory molecules such as CD25, CD28, or CD80. A different pattern of TGF- beta1-mediated immune regulation was observed in relation to fully differentiated antigen-specific memory CD4+ T cells. Here we observed that antigen-specific activation of memory Th1 T cells is inhibited by TGF-beta1, but required higher levels of TGF-beta1 than observed for inhibition of na?ve T cells. This inhibition was associated with partial inhibition of STAT4 phosphorylation. In contrast, memory Th2 T cells are not subjected to TGF-beta1-mediated suppression, and STAT6 activation is not affected by TGF-beta1. These studies reveal that TGF- beta1 is a powerful negative regulatory of the primary immune response of CD4+ T cells, but only Th1 T cells are subject to such regulation after the memory stage of T cell differentiation has been reached. Thus, these studies define the potential regulatory role of TGF- beta1 in Th1 and Th2 T cell-mediated host defense and autoimmunity. - IL-12, IL-12R, Th1/Th2 differentiation, IFN-gamma, IL-4, TGF-beta1, T cell priming, STAT4, STAT6. - Human Subjects

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Intramural Research (Z01)
Project #
1Z01AI000354-17
Application #
6288836
Study Section
Special Emphasis Panel (LCI)
Project Start
Project End
Budget Start
Budget End
Support Year
17
Fiscal Year
1999
Total Cost
Indirect Cost
City
State
Country
United States
Zip Code
Meng, Guangxun; Zhang, Fuping; Fuss, Ivan et al. (2009) A mutation in the Nlrp3 gene causing inflammasome hyperactivation potentiates Th17 cell-dominant immune responses. Immunity 30:860-74
Yang, Zhiqiong; Fuss, Ivan J; Watanabe, Tomohiro et al. (2007) NOD2 transgenic mice exhibit enhanced MDP-mediated down-regulation of TLR2 responses and resistance to colitis induction. Gastroenterology 133:1510-21
Strober, Warren; Fuss, Ivan; Mannon, Peter (2007) The fundamental basis of inflammatory bowel disease. J Clin Invest 117:514-21
Mannon, Peter J; Fuss, Ivan J; Dill, Susie et al. (2006) Excess IL-12 but not IL-23 accompanies the inflammatory bowel disease associated with common variable immunodeficiency. Gastroenterology 131:748-56
Fuss, Ivan J; Becker, Christoph; Yang, Zhiqiong et al. (2006) Both IL-12p70 and IL-23 are synthesized during active Crohn's disease and are down-regulated by treatment with anti-IL-12 p40 monoclonal antibody. Inflamm Bowel Dis 12:9-15
Strober, Warren; Fuss, Ivan J (2006) Experimental models of mucosal inflammation. Adv Exp Med Biol 579:55-97
Leon, Francisco; Contractor, Nikhat; Fuss, Ivan et al. (2006) Antibodies to complement receptor 3 treat established inflammation in murine models of colitis and a novel model of psoriasiform dermatitis. J Immunol 177:6974-82
Watanabe, Tomohiro; Kitani, Atsushi; Murray, Peter J et al. (2006) Nucleotide binding oligomerization domain 2 deficiency leads to dysregulated TLR2 signaling and induction of antigen-specific colitis. Immunity 25:473-85
Strober, Warren; Murray, Peter J; Kitani, Atsushi et al. (2006) Signalling pathways and molecular interactions of NOD1 and NOD2. Nat Rev Immunol 6:9-20
Strober, Warren (2006) Immunology. Unraveling gut inflammation. Science 313:1052-4

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