International immunology
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International immunology · May 2014
MiR-568 inhibits the activation and function of CD4⁺ T cells and Treg cells by targeting NFAT5.
CD4(+) T cells play critical roles in orchestrating adaptive immune responses. Their activation and proliferation are critical steps that occur before they execute their biological functions. Despite the important role of this process, the underlying molecular events are not fully understood. ⋯ In addition, inhibition of NFAT5 by siRNA-mediated knockdown can inhibit the activation and differentiation of Treg cells. These findings reveal that miR-568 can inhibit the activation and function of both CD4(+) T cells and Treg cells by targeting NFAT5. Since miR-568 plays an important role in both CD4(+) T cells and Treg cells, these findings may provide leads for the development of novel treatments for human inflammatory and autoimmune diseases.
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International immunology · Aug 2012
Anti-CD3ε induces splenic B220lo B-cell expansion following anti-CD20 treatment in a mouse model of allosensitization.
Antibodies targeting T cells and B cells are increasingly used for immunosuppression in clinical transplantation. However, the impact of T-cell depletion by antibodies on B-cell homeostasis is poorly understood. Using a mouse model of allosensitization with skin allograft, we investigated whether targeting T cells by anti-CD3ε alters peripheral B-cell homeostasis and alloantibody responses following B-cell depletion by anti-CD20. ⋯ Alloantibody production increased significantly in the mice following re-immunization by donor-specific splenocytes. We conclude that anti-CD3ε can induce an expansion of B220(lo) B cells in the spleens after B-cell depletion by anti-CD20. These B cells are not producing alloantibodies, but re-immunization of the mice with alloantigen leads to risk of alloantibody response.
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International immunology · Jun 2010
Sphingosine 1-phosphate receptor type 1 regulates egress of mature T cells from mouse bone marrow.
Sphingosine 1-phosphate (S1P) and its receptor, S1P receptor type 1 (S1P(1)), are essential for lymphocyte egress from secondary lymphoid organs (SLO). Fingolimod (FTY720), the S1P receptor modulator, inhibits lymphocyte egress from SLO and decreases circulating lymphocytes; however, it also induces a significant decrease in the number of peripheral blood lymphocytes in alymphoplasia (aly/aly) mice lacking SLO. In this study, we demonstrated that the administration of FTY720 induced sequestration of mature lymphocytes, particularly T cells, into the bone marrow (BM) in aly/aly mice, implying that the reduction of circulating lymphocytes in these mice by FTY720 was due to inhibition of lymphocyte egress from the BM. ⋯ Prophylactic administration of FTY720 to ovalbumin (OVA)-immunized mice significantly inhibited footpad swelling induced by OVA challenging with a marked reduction of OVA-specific T(h) cells in the BM, indicating that immunomodulation by FTY720 is likely due to reduced circulation of antigen-specific T(h) cells. On the other hand, OVA-specific T(h) cells, like naive T cells, were also sequestered into the BM and SLO of OVA-immunized mice by a short exposure of FTY720 after OVA challenging. These results suggest that the S1P-S1P(1) axis plays a regulatory role in egress of mature T cells including antigen-specific T(h) cells from the BM.
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International immunology · Mar 2009
IL-7 and the HIV Tat protein act synergistically to down-regulate CD127 expression on CD8 T cells.
IL-7 signaling is essential for optimal CD8 T cell function, homeostasis and establishment of memory. We have previously shown decreased expression of the IL-7 receptor alpha-chain (CD127) on CD8 T cells from HIV-infected patients with active viral replication. We have also shown that soluble HIV Tat protein specifically down-regulates CD127 on the surface of CD8 T cells and impairs cell proliferation and cytolytic potential following stimulation with IL-7 in vitro. ⋯ Inhibition of Janus kinase (JAK) completely blocks IL-7's ability to down-regulate CD127 on the surface of CD8 T cells and also abolishes synergy with Tat. Interestingly, while Tat acts synergistically with IL-7 to reduce CD127 expression, it antagonizes IL-7-induced cell proliferation and Ki-67 expression and has no effect on IL-7-mediated signal transducer and activator of transcription 5 (STAT5) phosphorylation or expression of the anti-apoptotic gene Bcl-2. Thus, by affecting different IL-7 signal transduction pathways, HIV Tat protein is able to impair both CD8 T cell activation and proliferation without inducing apoptosis.
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International immunology · Apr 2008
KIR2DS1-mediated activation overrides NKG2A-mediated inhibition in HLA-C C2-negative individuals.
NK cell cytotoxicity is controlled through a balance of both activating and inhibitory signals. The HLA specificity of alloreactive NK cells has been previously shown to be controlled by inhibitory killer immunoglobulin-like receptors (KIRs). Alloreactive NK cells lyse targets that lack the HLA ligand for their inhibitory KIR. ⋯ Although this NK clone expressed NKG2A, an inhibitory receptor whose ligand is HLA-E, targets with ligands for both KIR2DS1 and NKG2A were lysed by this clone indicating that the KIR2DS1-mediated activation signal overrides the NKG2A-mediated inhibitory signal. KIR2DS1 activated NK clones in polyclonally expanded NK cultures from a donor that lacked the C2 epitope accounted for approximately 1% of all NK cells. This study highlights a potential role for NK cells controlled by activating KIR in mediating NK alloreactivity.