Expression of B7 molecules in the eye during experimental autoimmune anterior uveitis (EAAU)

Novel gene targets for miRNA146a and miRNA155 in anterior uveitis

BACKGROUND/AIMS

Anterior uveitis (AU) is the most common form of intraocular inflammation. MicroRNAs (miRNA) are small, non-coding RNAs functioning as post-transcriptional repressors of gene expression. Knowledge of miRNAs can implicate specific genes and pathogenic signalling pathways in disease. This study examines miRNA expression, function and target genes in AU pathogenesis.

METHODS

AU and healthy control (HC) peripheral blood mononuclear cells (PBMC) were initially screened for expression of five miRNAs by real-time PCR. Regulation of the aberrantly expressed miRNAs by TLR1/2, TLR3, TLR4, IL1β and TNFα was quantified by real-time PCR and paired cytokine outputs measured by ELISA. Functional effects of miRNA overexpression using transfected THP1 cells examined IL6, IL8, IL10 and IL1β cytokine outputs by ELISA. Target genes were identified using TargetScan online computational algorithm and relevant targets verified by cloning of the 3'UTR and luciferase reporter gene assays.

RESULTS

Increased expression of miRNA146a (p<0.01), miRNA155 (p<0.05) and miRNA125a5p (p<0.01) was demonstrated in AU PBMC compared with HC. miRNA155 was increased following TLR1/2 (p<0.05) and TLR4 (p<0.05) stimulation and miRNA146a increased in response to IL1β (p<0.05). In a proinflammatory environment, miRNA155 overexpression in THP1 cells yielded increased cytokine output whereas miRNA146a overexpression showed decreased cytokine output. CD80, PRKCE and VASN were confirmed as novel targets for miRNA146a and SMAD2, TYRP1 and FBXO22 for miRNA155.

CONCLUSION

This study identifies overexpression of proinflammatory miRNA155, regulatory miRNA146a and miRNA125a-5p in AU. CD80, PRKCE and VASN are novel miRNA146a targets and SMAD2, TYRP1 and FBXO22 are novel targets for miRNA155.

Cyclosporine a drug-delivery system for high-risk penetrating keratoplasty: Stabilizing the intraocular immune microenvironment

Cyclosporine A (CsA) is an essential medication used to prevent corneal allograft rejection. Our preliminary studies revealed that CsA drug-delivery system (DDS) was more effective in preventing high-risk corneal allograft rejection than topical CsA application. However, the impacts of CsA DDS on the intraocular immune microenvironment were not fully elucidated. In the present study, we investigated the effect of CsA DDS on the cornea allograft, aqueous humor, and iris-ciliary body using a rabbit model of high-risk penetrating keratoplasty. New Zealand white rabbits were divided into four groups: a normal control group, an untreated group, a CsA eye drop group and a CsA DDS group. Graft survival was monitored for 12 weeks, and the therapeutic effects of CsA DDS were evaluated at 3 and 12 weeks after high-risk keratoplasty. In the CsA DDS group, the mean graft survival time was significantly prolonged when compared with the untreated and CsA eye drop groups. At all time-points, Langerhans cell density, inflammatory cell density, and central corneal thickness in the CsA DDS group were much lower(all p < 0.01) than the untreated and CsA eye drop groups, in which their parameters were significantly higher than the normal control group (all p < 0.01). Compared with the untreated and CsA eye drop groups, an implanted CsA DDS markedly decreased the CD11b+ and CD8+ T cell infiltration in the corneal grafts. CsA DDS treatment also greatly reduced the CD4+ T cell density and the expression of interferon-gamma, interleukin-2 (IL-2), IL-6, CD80, and CD86 mRNA both in the corneal graft and iris-ciliary body (all p < 0.01). Moreover, CsA DDS significantly reduced the IL-2 level in aqueous humor (p < 0.01). Taken together, our results suggest that CsA DDS implanted into the anterior chamber create a relative immunosuppressive microenvironment in the corneal graft, iris-ciliary body, and aqueous humor. Stabilizing the intraocular immune microenvironment could partially elucidate the mechanism of CsA DDS in suppressing corneal graft rejection.

MHC class II expression and potential antigen-presenting cells in the retina during experimental autoimmune uveitis

Background

Controversy exists regarding which cell types are responsible for autoantigen presentation in the retina during experimental autoimmune uveitis (EAU) development. In this study, we aimed to identify and characterize the retinal resident and infiltrating cells susceptible to express major histocompatibility complex (MHC) class II during EAU.

Methods

EAU was induced in C57BL/6 mice by adoptive transfer of autoreactive lymphocytes from IRBP1-20-immunized animals. MHC class II expression was studied by immunostainings on eye cryosections. For flow cytometry (FC) analysis, retinas were dissected and enzymatically digested into single-cell suspensions. Three MHC class II⁺ retinal cell populations were sorted by FC, and their RNA processed for RNA-Seq.

Results

Immunostainings demonstrate strong induction of MHC class II expression in EAU, especially in the inner retina at the level of inflamed vessels, extending to the outer retinal layers and the subretinal space in severely inflamed eyes. Most MHC class II⁺ cells express the hematopoietic marker IBA1. FC quantitative analyses demonstrate that MHC class II induction significantly correlates with disease severity and is associated with upregulation of co-stimulatory molecule expression. In particular, most MHC class II^hi cells express co-stimulatory molecules during EAU. Further phenotyping identified three MHC class II⁺ retinal cell populations: CD45⁻CD11b⁻ non-hematopoietic cells with low MHC class II expression and CD45⁺CD11b⁺ hematopoietic cells with higher MHC class II expression, which can be further separated into Ly6C⁺ and Ly6C⁻ cells, possibly corresponding to infiltrating macrophages and resident microglia. Transcriptome analysis of the three sorted populations leads to a clear sample clustering with some enrichment in macrophage markers and microglial cell markers in Ly6C⁺ and Ly6C⁻ cells, respectively. Functional annotation analysis reveals that both hematopoietic cell populations are more competent in MHC class II-associated antigen presentation and in T cell activation than non-hematopoietic cells.

Conclusion

Our results highlight the potential of cells of hematopoietic origin in local antigen presentation, whatever their Ly6C expression. Our work further provides a first transcriptomic study of MHC class II-expressing retinal cells during EAU and delivers a series of new candidate genes possibly implicated in the pathogenesis of retinal autoimmunity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-017-0915-5) contains supplementary material, which is available to authorized users.

Expression of MicroRNAs in the Eyes of Lewis Rats with Experimental Autoimmune Anterior Uveitis

Purpose. This study aimed to determine the dynamic changes of NF-κB-related microRNAs (miRNAs) and cytokines over the course of experimental autoimmune anterior uveitis (EAAU) and elucidate the possible immunopathogenesis. Materials and Methods. Uveitis was induced in Lewis rats using bovine melanin-associated antigen. The inflammatory activity of the anterior chamber was clinically scored, and leukocytes in the aqueous humor were quantified. RNA was extracted from the iris/ciliary bodies and popliteal lymph nodes to reveal the dynamic changes of eight target miRNAs (miR-155-5p, miR-146a-5p, miR-182-5p, miR-183-5p, miR-147b, miR-21-5p, miR-9-3p, and miR-223-3p) and six cytokine mRNAs (IFN-γ, IL-17, IL-12A, IL-1β, IL-6, and IL-10). In situ hybridization of miRNA and enzyme-linked immunosorbent assay quantification of cytokines were performed to confirm the results. Results. Disease activity and leukocyte quantification were maximum at day 15 after immunization. The profiling of miRNA revealed downregulation of miR-146a-5p, miR-155-5p, miR-223-3p, and miR-147b and upregulation of miR-182-5p, miR-183-5p, and miR-9-3p. Cytokine analysis revealed IFN-γ, IL-17, IL-12A, IL-1β, and IL-6 overexpression, with IL-10 downregulation. Conclusions. Dynamic changes of miRNAs were observed over the course of EAAU. By initiating NF-κB signaling, the expressions of downstream cytokines and effector cells from the Th17 and Th1 lineages were sequentially activated, contributing to the disease.

Requirement of CD80+ costimulation for rejection of ocular tumors and termination of immune privilege

Immune privilege in the anterior chamber of the eye is very effective at preventing elimination of ocular tumors that express weak tumor antigens. We previously demonstrated that DBA/2 mice immunized in the flank with a P815 tumor cell vaccine that expressed CD80/IL-12 was unable to terminate immune privilege and prevent tumor growth in the anterior chamber. In the present study, we determined whether expression of costimulatory signals on tumor cells injected via an ocular route would terminate immune privilege. We observed that CD80-positive tumors were always rejected from the anterior chamber. However, the pattern of tumor rejection was dramatically different depending upon whether the mice were either naïve, or immunized in flank against the tumor cells. Naïve mice that received an anterior chamber injection of CD80-positive tumors did not develop immune privilege and displayed strong delayed hypersensitivity (DH) against the tumor cells. Moreover, the ocular tumors were rejected by ischemic necrosis that induced atrophy of the eye and phthisis. When immunized mice received an identical injection of tumor cells in the anterior chamber, they also did not develop immune privilege and displayed strong DH. However, tumor rejection was considerably different and occurred without destruction of normal ocular tissue, or phthisis. To determine if immune privilege was restored in these eyes, mice received a second injection of P815 cells (CD80-negative) into the anterior chamber 2weeks after the first CD80-positive tumors were eliminated. Surprisingly, immune privilege was not restored and the P815 tumors were eliminated completely, again without phthisis. We conclude that specific rejection of ocular tumors with minimal destruction of the eye requires systemic immunization and expression of CD80 costimulatory signals on tumors within the eye.