Biomedical subjects

Elizabeth Muckersie

Publications and source records attributed to Elizabeth Muckersie.

5 recordsLinked to original sources

PubMed2007

CD4+CD25+ T regulatory cells induced by LPS-activated bone marrow dendritic cells suppress experimental autoimmune uveoretinitis in vivo.

BACKGROUND: Tolerance-inducing DC are considered to be less mature than immunogenic DC, but the conditions promoting a less mature DC phenotype are not clear. We have previously shown that lipopolysaccharide (LPS) can have differential effects on DC function depending on the timing of DC exposure to LPS. Here, we show that early LPS-activated bone marrow derived DC (early DC, eDC), when administered subcutaneously to mice in vivo, promote tolerance to EAU induced via immunisation with interphotoreceptor retinol binding protein (IRBP) peptide 161-180. The effect correlates with the failure of eDC to secrete IL-12, and appears to be mediated in part via expansion of naturally occurring CD4+ CD25+ T regulatory cells (Tregs), which also mediate suppression of EAU on adoptive transfer to naive mice followed by immunization with autoantigen. METHODS: Immature DC were prepared from BMDC cultures. Early DC (eDC) and late DC (lDC) for tolerance experiments were obtained by differential timing of LPS addition and their cytokine secretion profile was analyzed. eDC and lDC were subcutaneously injected into mice. From the dLN CD4+ CD25+ GITR+ T regulatory cells found to express FoxP3 were isolated and transferred into mice prior to immunisation with IRBP. The immune response was scored by histopathology. Tregs were characterized in vitro by intracellular staining, cytokine secretion assay and transwell experiments. RESULTS: eDC secrete IL-10 but no IL-12 or IFNgamma. When injected subcutaneously into naive mice, they expand the population of CD4+ CD25(+high) GITR+ T cells expressing FoxP3 in the dLN, thus increasing the total number of IL-10 producing cells. eDC induced Tregs inhibit CD4+ CD25- T effector cell proliferation by a contact dependent process, and both eDC and Tregs suppress retinal damage when adoptively transferred. CONCLUSIONS: We suggest that DC maturation may be necessary for both tolerance and immunity, but differential levels of activation and/or cytokine production direct the outcome of DC-T cell interaction and this is determined by IL-12 production. T regulatory cells induced in vivo by contact with eDC are able to suppress disease in the EAU model by adoptive transfer.

Adoptive Transfer↗

PubMed2006

Interferon-alpha: a key factor in autoimmune disease?

PURPOSE: Interferon (IFN)-alpha is an effective drug for treatment of uveitis in Behçet's disease. This study was undertaken to investigate the mechanism of action of IFN-alpha in the treatment of various types of noninfectious sight-threatening uveitis. METHODS: Eleven patients with refractory uveitis, and 13 healthy individuals were enrolled. The number of circulating plasmacytoid dendritic cells (pDCs) and their capacity to produce IFN-alpha in culture on stimulation with synthetic oligodinucleotides containing the CpG-motif were studied. Peripheral blood CD4+ T-cell phenotype and activation status were evaluated by flow cytometry at 0, 2, and 8 weeks after treatment for expression of CD69, CD62L, chemokine receptors (CCR4, CXCR3, and CCR5), and intracellular cytokines (TNF-alpha, IFN-gamma, and IL-10). RESULTS: All patients experienced a positive clinical response to IFN-alpha treatment. There was no significant difference between patients and control subjects in the number of circulating pDCs, but there was a significant decrease in the capability of patients' pDCs to produce IFN-alpha in response to CpG (P < 0.001). Peripheral blood CD4+ T cells expressed reduced levels of surface CD62L (P < 0.005) as a measure of activation and higher levels of chemokine receptors CXCR3, CCR4, and CCR5 (P < 0.005, P < 0.05, and P < 0.05, respectively); in addition, intracellular T-cell IL-10 levels were increased once the treatment was initiated (P < 0.01). CONCLUSIONS: The data suggest that IFN-alpha may control uveitis by promoting induction of IL-10-producing T-cells, possibly T-regulatory cells. Dysregulation of the T-cell population in patients with uveitis may be associated with a defect in the pDCs' ability to produce IFN-alpha, which can be circumvented with administration of exogenous IFN-alpha.

Adolescent↗

PubMed2005

FTY720 in corneal concordant xenotransplantation.

BACKGROUND: : Currently, there are no effective treatments for the control of corneal xenograft rejection. We evaluated the efficacy and mode of action of a novel immunosuppressant, FTY720, in a model of corneal xenograft transplantation. METHODS: : Rat-to-mouse corneal xenografts were performed and the effects of treatment with daily intraperitoneal injections of FTY720 (0.5 or 3.0 mg/kg/day) or saline from 2 days pretransplantation were assessed clinically. Immunohistochemical studies of the grafts and flow cytometry of the draining lymph node subpopulations were performed at the time of clinical rejection. RESULTS: : Treatment with FTY720 delayed the onset of corneal rejection, from 8 days postgraft in saline-treated mice to 12.0 +/- 0.89 days for low-dose FTY720 treatment and 15.6 +/- 3.1 days for high-dose FTY720 treatment (both P<0.001). Histologically, FTY-treated animals had a markedly reduced inflammatory response in the anterior chamber and cornea after replacement of the xenograft epithelium with normal healthy host epithelium. In contrast, saline-treated xenografts had persisting corneal epithelial defects and ulceration. In the draining lymph nodes, FTY720 not only inhibited the increase in the cell number observed in saline-treated recipients of xenografts, but also reduced the expression of activation markers on B cells (MHC class II and CD86). CONCLUSIONS: : FTY720 treatment significantly delayed rejection and decreased its severity in a dose-dependent manner in a rat-to-mouse model of corneal xenotransplantation. Since corneal xenograft rejection is mediated not by natural antibodies or CD8+ T cells directly, but by CD4+ T cells, the data from these experiments imply that FTY720 mediated its effect via CD4+ T cells.

Animals↗

PubMed2003

Antigen-specific inhibition of experimental autoimmune uveoretinitis by bone marrow-derived immature dendritic cells.

PURPOSE: To investigate the effect of maturation status of bone marrow-derived dendritic cells (BMDCs) on the in vivo immune response to interphotoreceptor retinoid-binding protein (IRBP) 161-180 peptide in experimental autoimmune uveoretinitis (EAU). METHODS: Immature and mature BMDCs were generated without or with the stimulation by lipopolysaccharide (LPS), and their mRNA cytokine profile and phenotype were analyzed by RNase protection assay and flow cytometry. The effect of immature and mature DCs in inducing antigen-specific T-cell proliferation and cytokine profile was further investigated in an IRBP peptide-induced model of EAU. RESULTS: BMDCs generated in granulocyte-macrophage-colony-stimulating factor (GM-CSF) were relatively immature (i)DCs, as determined by flow cytometry and cytokine profile. However, stimulation with LPS induced these cells to become mature (m)DCs with higher levels of surface major histocompatibility complex (MHC)-II and costimulatory molecules and higher mRNA expression of IL-1alpha, -1beta, -6, and -12. Subcutaneous administration of iDCs induced a state of relative tolerance to the peptide induced-EAU, and the effect was lost after the DCs underwent maturation induced by in vitro exposure to LPS. In vitro, both iDCs and mDCs induced typical peptide-specific T-cell proliferation, but IFN-gamma production by uveitogenic T cells was markedly inhibited by iDCs. In vivo, peptide-loaded iDCs induced draining lymph node (DLN) cells to secrete a distinct pattern of cytokine: namely, increased IL-10 and IL-5 and decreased IFN-gamma and IL-2, indicating an altered immune responses to a low T-helper (Th) cell type 1 profile and a high Th2 profile after uveitogenic challenge. CONCLUSIONS: The data suggest that induction of tolerance to an autoantigen by peptide-loaded DCs requires presentation of antigen by iDCs and involves the generation of a high-level IL-10 and IL-5 immune response in DLN cells.

Adoptive Transfer↗

PubMed2002

Secretion of interleukin-10 or interleukin-12 by LPS-activated dendritic cells is critically dependent on time of stimulus relative to initiation of purified DC culture.

Dendritic cells (DC) are key regulators of adaptive immunity with the potential to induce T cell activation/immunity or T cell suppression/tolerance. DC are themselves induced by "maturation" signals such as bacterial lipopolysaccharide (LPS). We demonstrate here that LPS can stimulate DC to display similar maturation phenotypes but to differentiate toward an interleukin (IL)-10(high)- or IL-12(high)-secretor profile depending on the timing of maturation signal induction. Immediate/early administration of LPS induced purified bone marrow-derived DC (BMDC) to differentiate as IL-10(high)IL-12(low)-secreting cells, termed early DC (eDC). Conversely, delayed administration of LPS altered the DC cytokine profile to IL-10(low)IL-12(high), termed later DC (lDC). The presence of IL-4 enhanced the yield and maturation of BMDC but inhibited LPS-induced IL-10 production by eDC. In contrast, interferon-gamma reduced the yield of DC but promoted the level of LPS-induced IL-10 production by lDC. Our data provide new evidence that ex vivo manipulation and the cytokine environment regulate DC maturation status and cytokine-secretor phenotype with implications for the control of T cell differentiation and function via DC-based immunotherapeutic strategies.

Animals↗