AAV2-Mediated Combined Subretinal Delivery of IFN-α and IL-4 Reduces the Severity of Experimental Autoimmune Uveoretinitis

We previously showed that adeno-associated virus 2 (AAV2) mediated subretinal delivery of human interferon-alpha (IFN-α) could effectively inhibit experimental autoimmune uveoretinitis (EAU). In this study we investigated whether subretinal injection of both AVV2.IFN-α and AAV2.IL-4 had a stronger inhibition on EAU activity. B10RIII mice were subretinally injected with AAV2.IFN-α alone (1.5×107 vg), AAV2.IL-4 alone (3.55×107 vg), and AAV2.IFN-α combined with AAV2.IL-4. PBS, AAV2 vector encoding green fluorescent protein (AAV2.GFP) (5×107 vg) was subretinally injected as a control. IFN-α and IL-4 were effectively expressed in the eyes from three weeks to three months following subretinal injection of AAV2 vectors either alone or following combined administration and significantly attenuated EAU activity clinically and histopathologically. AAV2.IL-4 showed a better therapeutic effect as compared to AAV2.IFN-α. The combination of AAV2.IL-4 and AAV2.IFN-α was not significantly different as compared to AAV2.IL-4 alone. There was no difference concerning DTH (delayed-type hypersensitivity) reaction, lymphocyte proliferation and IL-17 production among the investigated treatment groups, suggesting that local retinal gene delivery did not affect the systemic immune response

Acquired and Congenital Ocular Toxoplasmosis Experimentally Induced in Calomys callosus (Rodentia, Cricetidae)

An experimental model for acquired and congenital ocular toxoplasmosis as well as a model to induce experimental autoimmune uveitis (EAU) was investigated in Calomys callosus. Toxoplasma gondii, ME-49 strain, was used to infect males and pregnant- and not pregnant-females while S-antigen, a major glycoprotein of the retinal photoreceptor cell, was used to induce EAU. The ocular lesions elicited by T. gondii were characterized by the presence of cysts, free tachyzoites and inflammatory cells in the retina or related tissues. In the congenital form, 40% of the fetus presented ocular lesions, i.e., presence of cysts in the retina, vitreous, and extra-retinal tissues. In the acquired form, 75% of the females and 50% of the males presented unilateral ocular cysts both at 21 and 47 days post-infection. It was also demonstrated that S-antigen was not uveitogenic in the C. callosus model. No lesion was observed in the animals exclusively immunized with this retinal component, even when jacalin was used as additional adjuvant for polyclonal response to the retinal antigen. It can be concluded that C. callosus may constitute in a promising model for study both acquired and congenital ocular toxoplasmosis, particularly when it is important to make sure that a non autoimmune process is involved in the genesis of the ocular infection

Apoptosis of CD4+ T cells occurs in experimental autoimmune anterior uveitis (EAAU)

To investigate the spontaneous turning off mechanism of endogenous uveitis, EAAU was induced in Lewis rats. Immunohistochemical and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) stains revealed that CD4+ T cells were predominant in the uveal tissue of EAAU and that the apoptosis of these cells had occurred and progressed throughout the inflammatory period in EAAU eyes. The immunohistochemistry and in situ hybridization for Fas ligand (FasL) expression showed that the expression of Fas ligand was increased in the EAAU eyes compared with control eyes. These results suggest that the apoptosis of CD4+ T cells may play a key role in the spontaneous turning off mechanism of intra-ocular inflammation and that the induction of apoptosis may be mediated by the Fas–FasL system in EAAU