Spontaneous colitis occurrence in transgenic mice with altered B7-mediated costimulation.
ABSTRACT The B7 costimulatory molecules govern many aspects of T cell immune responses by interacting with CD28 for costimulation, but also with CTLA-4 for immune suppression. Although blockade of CTLA-4 with Ab in humans undergoing cancer immune therapy has led to some cases of inflammatory bowel disease, spontaneous animal models of colitis that depend upon modulation of B7 interactions have not been previously described. In this study, we demonstrate that mice expressing a soluble B7-2 Ig Fc chimeric protein spontaneously develop colitis that is dependent on CD28-mediated costimulation of CD4(+) T cells. We show that the chimeric protein has mixed agonistic/antagonist properties, and that it acts in part by blocking the cell intrinsic effects on T cell activation of engagement of CTLA-4. Disease occurred in transgenic mice that lack expression of the endogenous B7 molecules (B7 double knock-out mice), because of the relatively weak costimulatory delivered by the chimeric protein. Surprisingly, colitis was more severe in this context, which was associated with the decreased number of Foxp3(+) regulatory T cells in transgenic B7 double knock-out mice. This model provides an important tool for examining how B7 molecules and their effects on CTLA-4 modulate T cell function and the development of inflammatory diseases.
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ABSTRACT: The mechanism by which cell surface molecules regulate T cell production of lymphokines is poorly understood. Production of interleukin-2 (IL-2) can be regulated by signal transduction pathways distinct from those induced by the T cell antigen receptor. Stimulation of CD28, a molecule expressed on most human T cells, induced the formation of a protein complex that bound to a site on the IL-2 gene distinct from previously described binding sites and increased IL-2 enhancer activity fivefold. The CD28-responsive complex bound to the IL-2 gene between -164 and -154 base pairs from the transcription start site. The sequence of this element is similar to regions conserved in the 5' flanking regions of several other lymphokine genes.Science 02/1991; 251(4991):313-6. · 31.20 Impact Factor
Article: CD4+ T cells that express high levels of CD45RB induce wasting disease when transferred into congenic severe combined immunodeficient mice. Disease development is prevented by cotransfer of purified CD4+ T cells.[show abstract] [hide abstract]
ABSTRACT: Purified CD4+ lymph node T cells were sorted into two populations on the basis of their expression of CD45RB (CD45RBhi and CD45RBlo) and injected into congenic severe combined immunodeficient (SCID) mice. After a period of time that was dependent on the number of cells injected, the SCID mice that received CD45RBhi/CD4+ T cells developed a wasting disease that was not seen in SCID mice that received the CD4+/CD45RBlo cells or whole lymph node cells. At death, SCID mice that received the CD4+/CD45RBhi cells had increased spleen and lymph node cellularity compared with normal SCID mice and SCID mice that received the CD4+/CD45RBlo T cells. The spleen and lymph node contained CD4+ cells and neither CD8+ nor surface immunoglobulin M-positive cells, plus a population of cells that did not express any of those markers. At necropsy, the SCID mice that received the CD4+/CD45RBhi cells had significant hyperplasia of the intestinal mucosa with significant lymphoid cell accumulation in the lamina propria. Interestingly, mice that received mixtures of whole lymph node or purified CD4+ cells with CD4+/CD45RBhi cells did not develop weight loss, indicating that the unseparated CD4+ population contained cells that were capable of regulating the reactivity of the CD4+/CD45RBhi cells.Journal of Experimental Medicine 08/1993; 178(1):237-44. · 13.85 Impact Factor
Article: Conversion of peripheral CD4+CD25- naive T cells to CD4+CD25+ regulatory T cells by TGF-beta induction of transcription factor Foxp3.[show abstract] [hide abstract]
ABSTRACT: CD4+CD25+ regulatory T cells (Treg) are instrumental in the maintenance of immunological tolerance. One critical question is whether Treg can only be generated in the thymus or can differentiate from peripheral CD4+CD25- naive T cells. In this paper, we present novel evidence that conversion of naive peripheral CD4+CD25- T cells into anergic/suppressor cells that are CD25+, CD45RB-/low and intracellular CTLA-4+ can be achieved through costimulation with T cell receptors (TCRs) and transforming growth factor beta (TGF-beta). Although transcription factor Foxp3 has been shown recently to be associated with the development of Treg, the physiological inducers for Foxp3 gene expression remain a mystery. TGF-beta induced Foxp3 gene expression in TCR-challenged CD4+CD25- naive T cells, which mediated their transition toward a regulatory T cell phenotype with potent immunosuppressive potential. These converted anergic/suppressor cells are not only unresponsive to TCR stimulation and produce neither T helper cell 1 nor T helper cell 2 cytokines but they also express TGF-beta and inhibit normal T cell proliferation in vitro. More importantly, in an ovalbumin peptide TCR transgenic adoptive transfer model, TGF-beta-converted transgenic CD4+CD25+ suppressor cells proliferated in response to immunization and inhibited antigen-specific naive CD4+ T cell expansion in vivo. Finally, in a murine asthma model, coadministration of these TGF-beta-induced suppressor T cells prevented house dust mite-induced allergic pathogenesis in lungs.Journal of Experimental Medicine 01/2004; 198(12):1875-86. · 13.85 Impact Factor