Xiaomin Lin

Upregulated IL-23 and IL-17 in Behcet Patients with Active Uveitis

PURPOSE Behçet disease (BD) is a systemic inflammatory disease presumably caused by an autoimmune response. The interleukin (IL)-23/IL-17 pathway has been demonstrated to be involved in the development and maintenance of certain inflammatory diseases. This study was designed to investigate the role of IL-23 and IL-17 in BD. METHODS IL-23p19 mRNA in peripheral blood mononuclear cells (PBMCs) was examined using RT-PCR. The levels of IL-23, IL-17, and IFN-gamma in sera or PBMCs were detected by ELISA. Flow cytometry was used to evaluate the frequencies of IL-17-producing and IFN-gamma-producing T cells and the expression of CD45RO. RESULTS Results showed that the expression of IL-23p19 mRNA, IL-23, IL-17, and IFN-gamma was markedly elevated in BD patients with active uveitis. The frequencies of IL-17-producing and IFN-gamma-producing T cells from PBMCs were significantly upregulated in BD patients with active uveitis. The increased IL-17 (3.10% +/- 0.53%) in BD patients with active uveitis was primarily produced by CD45RO(+) memory T cells. Recombinant (r) IL-23 could upregulate IL-17 production by polyclonally stimulated PBMCs, whereas interferon (IFN)-gamma downregulated IL-17 production. CONCLUSIONS These findings reveal that the levels of IL-23, IL-17, and IFN-gamma are elevated in BD patients with active uveitis, and they suggest that the IL-23/IL-17 pathway together with IFN-gamma is associated with the active intraocular inflammation in BD patients.

SUMO4 gene polymorphisms in Chinese Han patients with Behcet's disease

Small ubiquitin-like modifier 4 (SUMO4) has been shown to have the potential to down-regulate NF-kappaB signal, leading to decreased transcription of pro-inflammatory cytokines. Recently, SUMO4 polymorphisms have been shown to be associated with several autoimmune diseases. In the present study, the association of SUMO4 polymorphisms with Behcets disease (BD) was investigated. Our results showed a significantly increased frequency of the + 438 C allele and a significantly decreased frequency of the AGAT haplotype in BD patients (p=0.0002, corrected p=0.002; p=0.000015, corrected p=0.0002, respectively). Stratification analysis indicated that these significant associations only existed in the HLA-B51 negative subjects (p=0.004, corrected p=0.032; p=0.001, corrected p=0.016, respectively). The GGAC haplotype was negatively associated with HLA-B51 positive BD patients (p=0.0007, corrected p=0.011). In conclusion, SUMO4 +438 C allele is associated with susceptibility to BD in HLA-B51 negative patients, while the AGAT haplotype is protectively associated with BD in HLA-B51 negative patients. The GGAC haplotype is protectively associated with BD in HLA-B51 positive patients.

Inhibitory effect of Cyclosporin A and corticosteroids on the production of IFN-gamma and IL-17 by T cells in Vogt-Koyanagi-Harada syndrome.

Cyclosporin A (CsA) and corticosteroids are extensively used in the treatment of autoimmune diseases including Vogt-Koyanagi-Harada (VKH) syndrome. The exact immunosuppressive mechanisms of these drugs are not exactly known. Th1 and Th17 cells are important populations involved in autoimmune diseases. In this study, we investigated whether they are involved in VKH syndrome and how their function is affected by CsA and corticosteroids. The results showed that IL-17, IFN-gamma, RORgammat and T-bet were upregulated in patients with active uveitis. CsA and corticosteroids were able to downregulate all these elevated levels which correlated with the clinical improvement of the uveitis. In vitro experiments showed that CsA and dexamethasone could decrease the frequencies of Th1 and Th17 cells and inhibit IL-17 and IFN-gamma production. These data suggest that an upregulated Th1 and Th17 response is associated with active VKH syndrome. CsA and corticosteroids may exert their immunosuppressive role by downregulating Th1 and Th17 cells.

T-bet expression is upregulated in active Behçet’s disease

Aim: To investigate T-bet mRNA and protein expression on peripheral blood mononuclear cells (PBMC) in patients with Behçet’s disease with active uveitis. Methods: Blood samples were taken from 24 patients with Behçet’s disease who had active uveitis and 16 healthy individuals. PBMC were subjected to analysis of T-bet mRNA and protein expression using semiquatitative reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot, respectively. The products from PCR were sequenced. In order to determine the influence of activation on T-bet expression, the phytohaemagglutinin (PHA) stimulated PBMC from each sample were also evaluated for expression of T-bet mRNA and protein. Results: A significantly increased T-bet mRNA accumulation was detected in the samples from patients with active Behçet’s disease compared with that in controls. A 62 kDa band was detectable in patients with active Behçet’s disease, but not in controls. No difference was found between patients with Behçet’s disease who had active uveitis and normal controls concerning the expression of either T-bet mRNA or its protein after stimulation with PHA for 72 hours. Conclusion: Behçet’s disease is associated with an upregulation of T-bet expression, which supports a role for the Th1 subset of T cells in the pathogenesis of this disease.

Association of the CTLA-4 gene with Vogt-Koyanagi-Harada syndrome ☆

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), a critical negative regulator of the T cell response, has been shown to be associated with a variety of autoimmune diseases. In this study, we investigated the association of CTLA-4 gene polymorphisms (- 1661A/G; - 318C/T; + 49G/A, and CT60) with Vogt-Koyanagi-Harada (VKH) syndrome in Chinese Han patients and normal controls. The results showed that the frequency of the G allele at the + 49 site was significantly higher in VKH patients than that observed in healthy controls (71.6% versus 62.8%, P = 0.0046, Pc = 0.037). Three haplotypes were identified from the four SNPs. The frequency of haplotype - 1661A:- 318C:+ 49G:CT60G, the most prevalent haplotype both in patients and controls, was significantly higher in patients than that in controls (70.1% versus 60.0%, P= 0.0013, n= 16, Pc = 0.021). These results suggest that CTLA-4 genetic polymorphisms are associated with the susceptibility to VKH syndrome.

Leptin increases in Vogt-Koyanagi-Harada (VKH) disease and promotes cell proliferation and inflammatory cytokine secretion

Backgroud/aims: Leptin has recently been found to play an important role in the development of autoimmune diseases. Our study is designed to investigate the expression and possible role of leptin in the pathogenesis of Vogt–Koyanagi–Harada (VKH) disease, one of the common types of autoimmune uveitis in China. Methods: Leptin levels in serums of 20 active, 16 inactive VKH patients and 20 healthy controls were measured using ELISA. Peripheral blood mononuclear cells (PBMCs) separated from active VKH patients and healthy controls were cultured with recombinant human leptin, and cell proliferation was assayed by [3H]-TdR incorporation. Cytokine levels in the supernatant of PBMCs cultured in mixed lymphocyte reaction (MLR) upon stimulation with leptin were assayed by ELISA. Results: Our results showed that leptin was significantly increased in the serum of active VKH patients compared with that in inactive VKH patients and healthy controls. Leptin levels in active VKH patients remained markedly higher when divided by body mass index (BMI). PBMCs cultured with leptin induced a marked cell proliferation and profound secretion of IFN-γ and IL-17. Conclusion: These findings suggest that leptin may be involved in the development of VKH disease possibly by promoting an immune response.

Splenic CD8+ T cells secrete TGF-β1 to exert suppression in mice with anterior chamber-associated immune deviation

BackgroundCD8+ regulatory T cells (Treg) have been considered to be involved in a model of ocular-induced tolerance, known as anterior chamber-associated immune deviation (ACAID). The mechanisms of suppression by CD8+ T cells in ACAID remain only poorly understood. TGF-β1 is considered as an inhibitory cytokine for immunosuppression in some models. The production of TGF-β1 by CD8+ T cells in ACAID, and whether CD8+ T cells exert suppression through TGF-β1, is unknown.MethodsThe suppressive effect of CD8+ T cells in ACAID mice was determined by a local adoptive transfer (LAT) assay. The production of TGF-β1 by CD8+ T cells was measured by enzyme-linked immunosorbent assay (ELISA). Anti-TGF-β1 antibodies were used in the LAT assay to test if they could block the inhibitory effect of CD8+ T cells.ResultsCD8+ T cells from ACAID mice were shown to block the delayed-type hypersensitivity (DTH) response in an antigen-specific manner in a LAT assay. These CD8+ T cells secreted TGF-β1, and their suppression could partially be blocked by anti-TGF-β1 antibodies.ConclusionsOur study confirms that CD8+ T cells from ACAID mice possess inhibitory properties. This population exerts part of its suppressive function via the production of TGF-β1.

Increased Regulatory T Cells in Spleen during Experimental Autoimmune Uveoretinitis

Purpose: To investigate the role of Foxp3-positive regulatory T cells in the development of experimental autoimmune uveoretinitis (EAU). Methods: B10RIII mice were immunized with 50 μg IRBP161-180 in complete Freund’s adjuvant (CFA) to induce EAU. EAU was evaluated clinically and pathologically on days 0, 7, 14, 21, and 28. Foxp3 mRNA levels were detected using reverse transcription–PCR (RT-PCR) and the frequencies of CD4+Foxp3+ T cells and CD4+CD25+Foxp3+ T cells in splenocytes were assessed by flow cytometry at the aforementioned time points. Results: The first clinical signs of EAU were observed on day 8–9, worsened up to day 14, and then gradually resolved. Histopathologic results showed that inflammatory signs occurred on day 7, reached their peak on day 14, and then gradually decreased. The levels of Foxp3 mRNA and the frequencies of CD4+Foxp3+ T cells and CD4+CD25+Foxp3+ T cells in splenocytes increased on day 7, reached a peak on day 14, and then maintained at a high level until day 28. Conclusion: An upregulation of Foxp3 expression is induced in EAU and paralleled with disease activity, suggesting a role for this lymphocyte subpopulation in the regression of this experimental uveitis model.

Upregulation of CD94 on CD8+T Cells in Anterior Chamber-Associated Immune Deviation

BackgroundCD8+ regulatory T cells (Treg) have been considered to be involved in a model of ocular-induced tolerance, known as anterior chamber-associated immune deviation (ACAID). The phenotype and characteristics of CD8+Treg in ACAID remain only poorly understood. Recent studies have reported that the CD94-Qa-1 system is implicated in the induction of ACAID CD8+Treg, but the functions and characteristics of CD8+CD94+T cells remain unclear.ResultsBoth mRNA and protein of CD94 and NKG2A were markedly up-regulated on splenic CD8+T cells of ACAID mice compared with controls. Flow cytometric analysis showed that very few CD8+CD94+T cells express granzyme B, perforin and Foxp3. CD8+CD94+T cells, but not CD8+CD94-T cells, magnetically isolated from the spleens of ACAID mice, produced large amounts of TGF-beta1 and exhibited suppressive activity in vitro. Neutralization of TGF-beta1 caused reversal of suppression mediated by CD8+CD94+T cells.ConclusionCD8+CD94+T cells from ACAID mice exhibited suppressive activity in association with enhanced expression of TGF-beta1, suggesting that CD8+Treg are mainly distributed in CD94+T cell subpopulations.