234 research outputs found
Estimation of hypocentral parameters of local earthquakes when crustal layers have constant P-velocities and dipping interfaces
The paper describes an algorithm for estimating the hypocentral coordinates and origin time of local earthquakes when the wave speed model to be employed is a layered one with dipping interfaces. A constrained least-squared error problem has been solved using the penalty function approach, in conjunction with the sequential unconstrained optimization technique of Fiacco and McCormick. Joint confidence intervals for the computed parameters are estimated using the approach of Bard for nonlinear problems. These results show that when a hypocentre lies outside the array of recording stations and head waves from a dipping interface are involved, then its inclination must be taken into account for dip angles exceeding 5Β°
CD4+ CD25+ FoxP3+ regulatory T cells suppress cytotoxicity of CD8+ effector T cells: implications for their capacity to limit inflammatory central nervous system damage at the parenchymal level
<p>Abstract</p> <p>Background</p> <p>CD4<sup>+ </sup>CD25<sup>+ </sup>forkhead box P3 (FoxP3)<sup>+ </sup>regulatory T cells (T reg cells) are known to suppress adaptive immune responses, key control tolerance and autoimmunity.</p> <p>Methods</p> <p>We challenged the role of CD4<sup>+ </sup>T reg cells in suppressing established CD8<sup>+ </sup>T effector cell responses by using the OT-I/II system <it>in vitro </it>and an OT-I-mediated, oligodendrocyte directed <it>ex vivo </it>model (ODC-OVA model).</p> <p>Results</p> <p>CD4<sup>+ </sup>T reg cells dampened cytotoxicity of an ongoing CD8<sup>+ </sup>T effector cell attack <it>in vitro </it>and within intact central nervous system tissue <it>ex vivo</it>. However, their suppressive effect was limited by the strength of the antigen signal delivered to the CD8<sup>+ </sup>T effector cells and the ratio of regulatory to effector T cells. CD8<sup>+ </sup>T effector cell suppression required T cell receptor-mediated activation together with costimulation of CD4<sup>+ </sup>T reg cells, but following activation, suppression did not require restimulation and was antigen non-specific.</p> <p>Conclusions</p> <p>Our results suggest that CD4<sup>+ </sup>T reg cells are capable of suppressing CD8<sup>+ </sup>T effector cell responses at the parenchymal site, that is, limiting parenchymal damage in autoimmune central nervous system inflammation.</p
Identification, frequency, activation and function of CD4+ CD25highFoxP3+Β regulatory T cells in children with juvenile idiopathic arthritis
The aim of the study was to test the frequency of CD4+Β CD25highFoxP3 regulatory T cells in JIA patients and to assess their activation status and functional activity. The study involved 12 children with JIA and 35 healthy control subjects. PBMC were stained with monoclonal antibodies (anti-CD25, anti-CD4, anti-CD127, anti-CD69, anti-CD71, and anti-FoxP3). The samples were evaluated using flow cytometer. CD4+Β CD25β and CD4+Β CD25+Β cells were isolated by negative and positive selection with magnetic microbeads. CD4+Β CD25+Β and CD4+Β CD25β cells were cultured separately and co-cultured (1:1) with or without PHA. The percentage of Tregs in JIA patients was significantly decreased in comparison with controls (median, 3.2 vs. 4.6; PΒ =Β 0.042). Relative fluorescence intensities of FoxP3 were higher in JIA patients than in controls (median, 9.1 vs. 6.8). The percentage of activated Tregs (CD71+) was significantly higher in JIA patients in comparison with controls (median, 6.5 vs. 2.8; PΒ =Β 0.00043). CD4+Β CD25+Β cells derived from JIA patients and controls were anergic upon PHA stimulation, while CD4+Β CD25β cells showed intensive proliferative response. The proliferation rate of CD4+Β CD25β cells stimulated by PHA was decreased in co-cultures. In JIA patients, the inhibition of proliferation of CD4+Β CD25β cells by CD4+Β CD25+Β cells was 37.9%, whereas in controls it was significantly lower (55.7%, PΒ =Β 0.046). JIA patients had statistically lower percentage of Tregs in peripheral blood compared to controls. CD4+Β CD25+Β cells sorted from peripheral blood of JIA patients had statistically lower ability to suppress CD4+Β CD25β cell proliferation in comparison with cells obtained from controls
Characterization of regulatory T cells in urban newborns
Β© 2009 Ly et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
A model of collaborative innovation between local government and tourism operators
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High density of FOXP3-positive T cells infiltrating colorectal cancers with microsatellite instability
High-level microsatellite instability (MSI-H) in colorectal cancer accounts for about 12% of colorectal cancers and is typically associated with a dense infiltration with cytotoxic CD8-positive lymphocytes. The role of regulatory T cells that may interfere with the host's antitumoural immune response in MSI-H colorectal cancers has not been analysed yet. Using an antibody directed against the regulatory T-cell marker transcription factor forkhead box P3 (FOXP3), regulatory T cells were examined in 70 colorectal cancers with known MSI status (MSI-H, n=37; microsatellite stable, n=33). In MSI-H colorectal cancers, we found a significantly higher intraepithelial infiltration with FOXP3-positive cells (median: 8.5 cells per 0.25βmm2 vs 3.1 cells per 0.25βmm2 in microsatellite stable, P<0.001), and a significantly elevated ratio of intraepithelial to stromal infiltration (0.05 vs 0.01 in microsatellite stable, P<0.001). CD8-positive cell counts were related positively to the number of FOXP3-positive cells (Spearman's Ο=0.56 and 0.55, respectively). Our results show that the elevated number of CD8-positive lymphocytes found in MSI-H colorectal cancers is paralleled by an enhanced infiltration with CD8-negative FOXP3-positive cells. These data suggest that FOXP3-positive cells may play a role in the regulation of the immune response directed against MSI-H colorectal cancers at the primary tumour site
HTLV-1 modulates the frequency and phenotype of FoxP3+CD4+T cells in virus-infected individuals
APC Activation Restores Functional CD4+CD25+ Regulatory T Cells in NOD Mice that Can Prevent Diabetes Development
BACKGROUND: Defects in APC and regulatory cells are associated with diabetes development in NOD mice. We have shown previously that NOD APC are not effective at stimulating CD4(+)CD25(+) regulatory cell function in vitro. We hypothesize that failure of NOD APC to properly activate CD4(+)CD25(+) regulatory cells in vivo could compromise their ability to control pathogenic cells, and activation of NOD APC could restore this defect, thereby preventing disease. METHODOLOGY/PRINCIPAL FINDINGS: To test these hypotheses, we used the well-documented ability of complete Freund's adjuvant (CFA), an APC activator, to prevent disease in NOD mice. Phenotype and function of CD4(+)CD25(+) regulatory cells from untreated and CFA-treated NOD mice were determined by FACS, and in vitro and in vivo assays. APC from these mice were also evaluated for their ability to activate regulatory cells in vitro. We have found that sick NOD CD4(+)CD25(+) cells expressed Foxp3 at the same percentages, but decreased levels per cell, compared to young NOD or non-NOD controls. Treatment with CFA increased Foxp3 expression in NOD cells, and also increased the percentages of CD4(+)CD25(+)Foxp3(+) cells infiltrating the pancreas compared to untreated NOD mice. Moreover, CD4(+)CD25(+) cells from pancreatic LN of CFA-treated, but not untreated, NOD mice transferred protection from diabetes. Finally, APC isolated from CFA-treated mice increased Foxp3 and granzyme B expression as well as regulatory function by NOD CD4(+)CD25(+) cells in vitro compared to APC from untreated NOD mice. CONCLUSIONS/SIGNIFICANCE: These data suggest that regulatory T cell function and ability to control pathogenic cells can be enhanced in NOD mice by activating NOD APC
HTLV-1 bZIP Factor Induces T-Cell Lymphoma and Systemic Inflammation In Vivo
Human T-cell leukemia virus type 1 (HTLV-1) is the causal agent of a neoplastic disease of CD4+ T cells, adult T-cell leukemia (ATL), and inflammatory diseases including HTLV-1 associated myelopathy/tropical spastic paraparesis, dermatitis, and inflammatory lung diseases. ATL cells, which constitutively express CD25, resemble CD25+CD4+ regulatory T cells (Treg). Approximately 60% of ATL cases indeed harbor leukemic cells that express FoxP3, a key transcription factor for Treg cells. HTLV-1 encodes an antisense transcript, HTLV-1 bZIP factor (HBZ), which is expressed in all ATL cases. In this study, we show that transgenic expression of HBZ in CD4+ T cells induced T-cell lymphomas and systemic inflammation in mice, resembling diseases observed in HTLV-1 infected individuals. In HBZ-transgenic mice, CD4+Foxp3+ Treg cells and effector/memory CD4+ T cells increased in vivo. As a mechanism of increased Treg cells, HBZ expression directly induced Foxp3 gene transcription in T cells. The increased CD4+Foxp3+ Treg cells in HBZ transgenic mice were functionally impaired while their proliferation was enhanced. HBZ could physically interact with Foxp3 and NFAT, thereby impairing the suppressive function of Treg cells. Thus, the expression of HBZ in CD4+ T cells is a key mechanism of HTLV-1-induced neoplastic and inflammatory diseases
Cell-Intrinsic NF-ΞΊB Activation Is Critical for the Development of Natural Regulatory T Cells in Mice
regulatory T (Treg) cells develop in the thymus and represent a mature T cell subpopulation critically involved in maintaining peripheral tolerance. The differentiation of Treg cells in the thymus requires T cell receptor (TCR)/CD28 stimulation along with cytokine-promoted Foxp3 induction. TCR-mediated nuclear factor kappa B (NF-ΞΊB) activation seems to be involved in differentiation of Treg cells because deletion of components of the NF-ΞΊB signaling pathway, as well as of NF-ΞΊB transcription factors, leads to markedly decreased Treg cell numbers in thymus and periphery. thymic Treg precursors and their further differentiation into mature Treg cells. Treg cell development could neither be completely rescued by the addition of exogenous Interleukin 2 (IL-2) nor by the presence of wild-type derived cells in adoptive transfer experiments. However, peripheral NF-ΞΊB activation appears to be required for IL-2 production by conventional T cells, thereby participating in Treg cell homeostasis. Moreover, pharmacological NF-ΞΊB inhibition via the IΞΊB kinase Ξ² (IKKΞ²) inhibitor AS602868 led to markedly diminished thymic and peripheral Treg cell frequencies.Our results indicate that Treg cell-intrinsic NF-ΞΊB activation is essential for thymic Treg cell differentiation, and further suggest pharmacological NF-ΞΊB inhibition as a potential therapeutic approach for manipulating this process
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