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.

The locus of fixation in strabismic amblyopia changes with increasing effort of recognition as assessed by scanning laser ophthalmoscope.

PURPOSE: We performed a qualitative assessment of fixation behaviour in relation to the fovea in patients with strabismic amblyopia. METHODS: The fixation of 25 patients with strabismic amblyopia was examined using a scanning laser ophthalmoscope (SLO). A digital frame grabber board was programmed to scan onto the patient's retina single solid black discs of 5, 10 and 15 degrees in diameter and Landolt Cs in different orientations and corresponding to a visual acuity (VA) of 0.01-0.2 in European decimals. The relative position of the fovea was video-recorded. Fifty video fields per second were plotted as x/y (fixational positions in relation to the fovea) and x/t (motion over time) graphs. RESULTS: Three main groups of patients were seen. Group 1 (n = 6), with a VA of < 0.1, showed a grossly eccentric and unstable locus of fixation independent of size/type of test stimulus used. Group 2 (n = 15), with VA of 0.1-0.8, initially used an eccentric retinal area for fixation that, however, shifted to the fovea with decreasing size and increasing detail of the target for fixation. Group 3 (n = 4), with VA of 0.3-0.8, had stable central fixation throughout. CONCLUSIONS: We speculate that the reduced VA associated with strabismic amblyopia is due to a defective motor control of fixation that can be modulated by recognitional effort.

Mycophenolate mofetil is a highly effective and safe immunosuppressive agent for the treatment of uveitis : a retrospective analysis of 106 patients.

BACKGROUND: We evaluated the outcomes of patients with different forms of chronic uveitis treated with mycophenolate mofetil (MMF) as an immunomodulatory and steroid-sparing agent. The multi-system side effects that arise after long-term treatment with corticosteroids and other immunosuppressants prompted us to use MMF. MMF is a selective inhibitor of inosine monophosphate dehydrogenase, thus blocking purine synthesis via the de novo pathway preferentially used by T and B lymphocytes. METHODS: Between 1998 and 2003, 106 patients were treated for uveitis (anterior n=26, intermediate n=51, posterior n=23, panuveitis n=6) with MMF at a dose of 1g twice daily. Treatment duration was at least 6 months (n=10), in most cases greater than 12 months (n=77) and in 25 cases between 24 months and 41 months, when the present retrospective evaluation was undertaken. Patient charts were analysed according to a standardized evaluation protocol. RESULTS: In 95 patients MMF was combined with prednisolone at a dosage of 2.5-10 mg per day. In 8 patients MMF was used as a monotherapy, and in 3 cases one further systemic immunosuppressant was required. The number of recurrences during MMF treatment was none or one in 92 patients, two in 6 cases and three or more in 8 patients. In none of the patients had MMF been stopped at the time of data analysis. The most frequently observed side effects were gastrointestinal upset (15%), followed by headache (9.3%), fatigue (5.7%), eczema (5%), and hair loss (3.5%). Other side effects were sporadic. Most of these phenomena were transitory. Forty-two patients experienced no side effects at all. In 4 patients MMF was judged ineffective due to failure to reduce the number of recurrences of severe inflammation compared with the previous therapeutic regime, or indeed occurrence of persistent macular oedema. CONCLUSIONS: Our results show that MMF is an effective immunosuppressant in patients with uveitis. We provide evidence that MMF controls the disease in the majority of patients with an acceptable profile of side effects.

The good, the bad and the ugly--APCs of the eye.

Dendritic-cell (DC) populations throughout the body have a wide range of features in common, which are associated with their primary function in antigen presentation. The unique immune milieu of the anterior segment of the eye is characterized by a selective DC-dependent inability to develop delayed hypersensitivity responses following antigen invasion into the eye. Recent research papers provide evidence that different maturation stages of DC subsets are detectable at different corneal sites. Thus, the corneal DC, as well as the DC and the macrophages in the iris and ciliary body, have the potential of determining the outcome of immunity or tolerance within this organ.