TNFR1-Dependent Regulation of Myeloid Cell Function in Experimental Autoimmune Uveoretinitis

Experimental autoimmune uveoretinitis is an autoimmune disease induced in mice, which involves the infiltration of CD11b(+) macrophages and CD4(+) T cells into the normally immune-privileged retina. Damage is produced in the target organ following the activation of Th1 and Th17 T cells and by the release of cytotoxic mediators such as NO by activated macrophages. The majority of immune cells infiltrating into the retina are CD11b(+) myeloid cells, but, despite the presence of these APCs, relatively limited numbers of T cells are observed in the retina during the disease course. These T cells do not proliferate when leukocytes are isolated from the retina and restimulated in vitro, although they do produce both IFN-gamma and IL-17. T cell proliferation was restored by depleting the myeloid cells from the cultures and furthermore those isolated myeloid cells were able to regulate the proliferation of other T cells. The ability of macrophages to regulate proliferation depends on activation by T cell-produced IFN-gamma and autocrine TNF-alpha signaling in the myeloid cells via TNFR1. In the absence of TNFR1 signaling, relative T cell expansion in the retina is increased, indicating that regulatory myeloid cells may also act in vivo. However, TNFR1 signaling is also required for macrophages, but not T cells, to migrate into the target organ. Thus, in TNFR1 knock out mice, the amplification of autoimmunity is limited, leading to resistance to experimental autoimmune uveoretinitis induction

The Clinical Time-Course of Experimental Autoimmune Uveoretinitis Using Topical Endoscopic Fundal Imaging with Histologic and Cellular Infiltrate Correlation

PURPOSE: EAU is an established preclinical model for assessment of immunotherapeutic efficacy toward translation of therapy for posterior uveitis. Reliable screening of clinical features that correlate with underlying retinal changes and damage has not been possible to date. This study was undertaken to describe, validate, and correlate topical endoscopic fundus imaging (TEFI) with histologic features of murine experimental autoimmune uveoretinitis (EAU), with the intent of generating a rapid noninvasive panretinal assessment of ocular inflammation. METHODS: EAU was induced in B10.RIII mice by immunization with the peptide RBP-3(161-180). The clinical disease course (days 0-63) was monitored and documented using TEFI. Disease severity and pathology were confirmed at various time points by histologic assessment. The composition of the cell infiltrate was also examined and enumerated by flow cytometry. RESULTS: TEFI demonstrated the hallmark features of EAU, paralleling many of the clinical features of human uveitis, and closely aligned with underlying histologic changes, the severity of which correlated significantly with the number of infiltrating retinal leukocytes. Leukocytic infiltration occurred before manifestation of clinical disease and clinically fulminant disease, as well as cell infiltrate, resolved faster than histologic scores. During the resolution phase, neither the clinical appearance nor number of infiltrating retinal leukocytes returned to predisease levels. CONCLUSIONS: In EAU, there is a strong correlation between histologic severity and the number of infiltrating leukocytes into the retina. TEFI enhances the monitoring of clinical disease in a rapid and noninvasive fashion. Full assessment of preclinical immunotherapeutic efficacy requires the use of all three parameters: TEFI, histologic assessment, and flow cytometric analysis of retinal infiltrate