Biomedical subjects

Linda Duncan

Publications and source records attributed to Linda Duncan.

7 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

Generation of a monoclonal human single chain antibody fragment to hepatic stellate cells--a potential mechanism for targeting liver anti-fibrotic therapeutics.

BACKGROUND/AIMS: Hepatic stellate cells are pivotal to fibrogenesis in the liver and many potential anti-fibrotic therapeutics are required to act on targets within hepatic stellate cells. The aim of this study was to generate a human antibody fragment to hepatic stellate cells. METHODS: Phage display was used to generate a human monoclonal antibody fragment to a peptide sequence present on an extracellular domain of synaptophysin, a protein expressed on the surface of hepatic stellate cells. RESULTS: An antibody fragment was isolated (termed C1-3), expressed in bacteria and purified. Fluorescently-labelled C1-3 antibody associated with human hepatic stellate cells but not hepatocytes in culture. Binding of fluorescently labelled C1-3 to hepatic stellate cells was blocked by the extracellular synaptophysin peptide sequence and uptake of the antibody intracellularly was inhibited by monensin. The toxin tributyl tin-when conjugated to C1-3-retained the ability to kill hepatic stellate cells confirming that C1-3 is sequestered intracellularly. CONCLUSIONS: This antibody fragment may be an effective means to target therapeutics to human hepatic stellate cells.

Amino Acid Sequence↗

PubMed2005

Cyclosporine vs tacrolimus therapy for posterior and intermediate uveitis.

OBJECTIVES: To compare the efficacy and tolerability of tacrolimus and cyclosporine therapy for noninfectious posterior segment intraocular inflammation and to evaluate their effect on peripheral blood CD4(+) T-cell phenotype and activation status. METHODS: Thirty-seven patients who required second-line immunosuppression for posterior segment intraocular inflammation were enrolled in this prospective randomized trial of tacrolimus vs cyclosporine therapy. The main outcome measures were visual acuity, binocular indirect ophthalmoscopy score, adverse effects, and quality of life. In addition, peripheral blood CD4(+) T-cell phenotype and activation status were evaluated by flow cytometry before treatment and at 2, 4, and 12 weeks using CD69, chemokine receptor (CCR4, CCR5, and CXCR3), and intracellular cytokine (tumor necrosis factor alpha, interferon-gamma, and interleukin 10) expression. RESULTS: Thirteen patients (68%) taking tacrolimus and 12 patients (67%) taking cyclosporine responded to treatment. Cyclosporine therapy was associated with a higher incidence of reported adverse effects. Mean arterial pressure and serum cholesterol level were significantly higher at 3 months in the cyclosporine group than the tacrolimus group. No significant difference was detected with regard to effect on quality of life or CD4(+) T-cell phenotype. CONCLUSIONS: Tacrolimus and cyclosporine were similar with regard to efficacy for posterior segment intraocular inflammation, but the results suggested a more favorable safety profile for tacrolimus therapy.

Adult↗

PubMed2004

Neutralizing tumor necrosis factor activity leads to remission in patients with refractory noninfectious posterior uveitis.

OBJECTIVE: To evaluate the efficacy and safety of tumor necrosis factor (TNF) inhibition with the p55 TNF receptor fusion protein (TNFr-Ig) for severe sight-threatening noninfectious posterior segment intraocular inflammation. METHODS: Seventeen patients with refractory noninfectious posterior segment intraocular inflammation received TNFr-Ig by intravenous infusion in this nonrandomized, open-label, pilot study. The primary outcome measure was logMAR visual acuity. Secondary outcome measures were binocular indirect ophthalmoscopy score, cystoid macular edema, adverse effects, and vision-related (visual core module 1) and health-related (36-Item Short-Form Health Survey) quality of life. RESULTS: Within 1 month of TNFr-Ig therapy, 9 patients (53%) achieved at least a 2-line improvement in visual acuity, 8 (57%) of 14 patients with vitreous haze before treatment achieved an improvement in binocular indirect ophthalmoscopy score to 0, and macular edema resolved in 5 (56%) of 9 affected patients. Twelve (71%) of the patients achieved complete cessation of intraocular inflammation following TNFr-Ig therapy. A reduction in concomitant immunosuppression was possible for 11 patients (65%) following TNFr-Ig therapy. However, all but 1 patient required continuing adjuvant therapy during the response to TNFr-Ig, which had a median duration of 3 months. Adverse effects included mild infusion reactions in 3 patients and transient lymphocytopenia in 2 patients. CONCLUSION: Therapy with TNFr-Ig was safe and effective for treating patients with sight-threatening noninfectious posterior segment intraocular inflammation resistant to conventional immunotherapy, but adjuvant immunosuppression and repeat infusions would be required to maintain long-term remission.

Adult↗

PubMed2004

Anti-TNFalpha therapy modulates the phenotype of peripheral blood CD4+ T cells in patients with posterior segment intraocular inflammation.

PURPOSE: Posterior segment intraocular inflammation (PSII) is a putative Th1 CD4+ cell mediated autoimmune disorder. In experimental autoimmune uveoretinitis, neutralization of tumor necrosis factor (TNF)-alpha induces suppression of Th1 cells, macrophage activation, and target organ damage. Previous studies implicated an efficacy of anti-TNFalpha therapies in patients with PSII. This study investigated the immunomodulatory effect of anti-TNFalpha therapy to find predictors of effective immunosuppression in PSII. METHODS: Fifteen patients with PSII refractory to conventional immunosuppressive therapy received a single infusion of a recombinant protein generated by fusing the p55 TNFalpha receptor with human IgG1. During 17 treatment periods, visual acuity (logarithm of the minimum angle of resolution [logMAR]) was monitored as a response criterion. Phenotype markers of CD4+ T cells were analyzed before and 2, 4, and 12 weeks after therapy. Expression of intracellular cytokines (interferon [IFN]-gamma, interleukin [IL]-10, and TNFalpha) and Th1/Th2-specific chemokine receptors (CXCR3, CCR4, and CCR5) on peripheral blood CD4+ T cells was determined using flow cytometry. RESULTS: The fraction of IL-10-expressing CD4+ T cells was increased during 12 of 17 treatment periods within 2 weeks after treatment. During eight treatment periods, this increase was associated with an improvement of visual acuity of at least 0.2 logMAR within 4 weeks (P = 0.029). The ratio between IL-10- and IFNgamma-expressing CD4+ T cells was significantly increased 2 weeks after therapy (P = 0.015). There was no significant change of CXCR3, CCR4, or CCR5 expression. CONCLUSIONS: Neutralizing TNFalpha activity in PSII increases the fraction of peripheral blood CD4+ T cells expressing IL-10, which correlates with a recovery of visual function.

Adult↗

PubMed2002

The immune response to corneal allograft requires a site-specific draining lymph node.

BACKGROUND: Recent studies have shown that head-neck draining lymph nodes (DLN) are required for priming the immune response during corneal allograft rejection. In this study we have investigated further the role of the DLN and spleen in corneal graft rejection in mice. METHODS: Individual DLN (submandibular [SM]; superficial cervical [SC]; and internal jugular) or their combinations were removed in mice undergoing corneal allografting (C57BL/10, H2(b) to BALB/c, H2(d)). In some mice, DLN from syngeneic mice were retransplanted, whereas other mice underwent removal of the spleen before corneal allografting. In a high-risk group of mice, removal of the DLN before a second corneal graft procedure was performed. RESULTS AND CONCLUSIONS: The data show that a single specific lymph node, i.e., the SM node, is the major DLN involved in corneal graft rejection whereas its nearest neighbor, the SC DLN, not only cannot substitute for the SM node in priming the immune response but may be involved with the spleen in immune privilege. Retransplantation studies of syngeneic LN indicate that the site of the DLN is more important to the process of graft rejection than the specific DLN tissue. This applies to the DLN whether it contains naive or memory allospecific T cells as shown in experiments in which removal of the SM DLN from mice who had already been primed by a previous corneal graft, prevented rejection of a second corneal graft in the same strain combination.

Animals↗