Too Much of a Good Thing: Extended Duration of Gut Microbiota Depletion Reverses Protection From Experimental Autoimmune Uveitis.

Purpose: Using the model of experimental autoimmune uveitis (EAU) induced by immunization with a retinal antigen, two studies have reported contradictory results on disease development following oral antibiotic treatment (ABX). We showed that long-term ABX did not affect EAU, but another study showed that short-term ABX was protective. We therefore studied the effects of ABX on EAU, gut microbiota, and host immune responses as a function of treatment duration. Methods: EAU-susceptible mice were treated orally with broad-spectrum antibiotics starting at least 10 weeks (long-term) or 1 week (short-term) before immunization until termination of the experiment. Gut microbiota were characterized by 16S amplicon sequencing, and host gut immune elements were studied phenotypically and functionally. Results: Long-term ABX had no effect, whereas short-term ABX delayed EAU, as previously reported by us and others, respectively. Microbial sequencing revealed progressive reduction of gut microbiota that showed some differences in the two ABX groups. Interestingly, duration of ABX was associated with a gradual disappearance of the CD4+ and CD4+CD8+ subset of gut intraepithelial lymphocytes (IELs). This IEL subset is microbiota dependent and is absent in germ-free mice. Relative abundance of Lactobacillus reuteri correlated with the frequencies of CD4+CD8+ IELs. IELs suppressed antigen-specific activation of autoreactive T cells in culture. Conclusions: Gut microbiota may play dual roles in uveitis development: They promote EAU development but also help maintain IEL populations that have regulatory function against autoreactive T cells. We propose that the progressive loss of this population during long-term ABX reverses the EAU-ameliorating effects of microbiota depletion.

Effect of small extracellular vesicles derived from IL-10-overexpressing mesenchymal stem cells on experimental autoimmune uveitis.

BACKGROUND: Autoimmune uveitis is a sight-threatening intraocular inflammation mainly caused by immune dysregulation. The development of safe and effective therapeutic approaches is urgently needed. Small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) have been demonstrated to inhibit autoimmune responses; however, the immunosuppressive effect of MSC-sEVs is too weak for clinical transfer. In the current study, we investigated the therapeutic effect of IL-10-overexpressing MSC-sEVs (sEV-IL10) on experimental autoimmune uveitis (EAU) and studied the underlying mechanism. METHODS: Mice were randomly grouped and received a single tail vein injection of different sEVs (50 µg) or PBS on day 11 post-immunization. The clinical and histological scores were graded, and the percentage of T helper cell was measured. To investigate the effect of sEVs on the proliferation of T-cells and the differentiation of Th1, Th17 and Treg cells, T-cells were cocultured with sEVs under the corresponding culture conditions. After labeled with PKH-26, sEVs were traced both in vivo and in vitro. RESULTS: Compared with normal or vector sEV-treated groups, mice in the sEV-IL10-treated group had lower clinical and histological scores with lower percentages of Th1 and Th17 cells in the eyes and higher percentages of Treg cells in the spleen and draining lymph nodes (LN). Furthermore, sEV-IL10 enhanced the suppressive effect of MSC-sEVs on the proliferation of T-cells and differentiation of Th1 and Th17 cells, whereas upregulated the differentiation of Treg cells. Both in vivo and in vitro experiments demonstrated that MSC-sEVs were rapidly enriched in target tissues and internalized by T-cells. CONCLUSION: These results suggested that sEV-IL10 effectively ameliorates EAU by regulating the proliferation and differentiation of T-cells, indicating sEVs as a potential novel therapy for autoimmune uveitis or other autoimmune diseases.

Ganciclovir attenuates the onset and progression of experimental autoimmune uveitis by inhibiting infiltration of Th17 and inflammatory cells into the retina.

Noninfectious (autoimmune and immune-mediated) uveitis is one of the primary diseases leading to blindness in the world. Due to the limitation of current first-line drugs for clinical uveitis, novel drugs and targets against uveitis are urgently needed. Ganciclovir (GCV), an FDA-approved antiviral drug, is often used to treat cytomegalovirus-induced retinitis in clinical patients. Recently, GCV was found to suppress neuroinflammation via targeting STING signaling because the STING pathway plays a pivotal role in autoimmune diseases. However, until now, the effect of GCV on non-infectious uveitis has never been explored. In this work, using the rat experimental autoimmune uveitis (EAU) model, we first found STING to be highly expressed in infiltrating cells (CD68+, CD45+, and CD4+) and retinal glial cells (Iba1+ and GFAP+) of the immunized retina. More importantly, GCV treatment can significantly suppress the initiation and progression of EAU by inhibiting infiltration of Th17 and inflammatory cells into the retina. Mechanistically, we found that GCV could reverse the levels of pro-inflammatory factors (such as IL-1ß) and chemokine-related factors (such as Cxcr3), possibly via targeting the STING pathway. The present results suggest that GCV may be considered as a novel therapeutic strategy against human uveitis.

STAT3-Specific Single Domain Nanobody Inhibits Expansion of Pathogenic Th17 Responses and Suppresses Uveitis in Mice.

STAT3 activates transcription of genes that regulate cell growth, differentiation, and survival of mammalian cells. Genetic deletion of Stat3 in T cells has been shown to abrogate Th17 differentiation, suggesting that STAT3 is a potential therapeutic target for Th17-mediated diseases. However, a major impediment to therapeutic targeting of intracellular proteins such as STAT3 is the lack of efficient methods for delivering STAT3 inhibitors into cells. In this study, we developed a novel antibody (SBT-100) comprised of the variable (V) region of a STAT3-specific heavy chain molecule and demonstrate that this 15 kDa STAT3-specific nanobody enters human and mouse cells, and induced suppression of STAT3 activation and lymphocyte proliferation in a concentration-dependent manner. To investigate whether SBT-100 would be effective in suppressing inflammation in vivo, we induced experimental autoimmune uveitis (EAU) in C57BL/6J mice by active immunization with peptide from the ocular autoantigen, interphotoreceptor retinoid binding protein (IRBP651-670). Analysis of the retina by fundoscopy, histological examination, or optical coherence tomography showed that treatment of the mice with SBT-100 suppressed uveitis by inhibiting expansion of pathogenic Th17 cells that mediate EAU. Electroretinographic (ERG) recordings of dark and light adapted a- and b-waves showed that SBT-100 treatment rescued mice from developing significant visual impairment observed in untreated EAU mice. Adoptive transfer of activated IRBP-specific T cells from untreated EAU mice induced EAU, while EAU was significantly attenuated in mice that received IRBP-specific T cells from SBT-100 treated mice. Taken together, these results demonstrate efficacy of SBT-100 in mice and suggests its therapeutic potential for human autoimmune diseases.

Vaccination with circulating exosomes in autoimmune uveitis prevents recurrent intraocular inflammation.

BACKGROUND: Exosomes participate in intercellular communication and act as important molecular vehicles in the regulation of numerous physiological and pathological processes, including autoimmune development. The role of circulating exosomes in the development of autoimmune uveitis is unknown. In this study, using the rat model of experimental autoimmune uveitis, which has clinical and histological features of pan uveitis in man, we evaluated the immunoregulatory function of circulating exosomes. METHODS: Experimental autoimmune uveitis was induced in Lewis rats either immunised with interphotoreceptor retinoid-binding protein R16 peptides or injected with activated R16-specific T cells. The disease incidence and severity were examined by indirect fundoscopy and flow cytometry. Circulating exosomes were isolated from peripheral blood of naïve and Day 14 R16 immunised Lewis rats. The effect of exosomes on specific T cells was evaluated by R16-specific T cell proliferation, cytokine production and recurrent uveitis induction. RESULTS: Circulating exosomes derived from active immunised uveitis rats selectively inhibited immune responses of R16-specific T cells in vitro. Vaccination of naïve rats with these exosomes reduced the incidence of recurrent uveitis in an antigen-specific manner. Antigen-specific uveitogenic T cells reduced IFN-γ production and increased IL-10 after vaccination. CONCLUSIONS: Circulating exosomes in autoimmune uveitis have the potential to be a novel treatment for recurrent autoimmune uveitis.

Intraoperative intravitreal triamcinolone acetonide injection for prevention of postoperative inflammation and complications after phacoemulsification in patients with uveitic cataract.

BACKGROUND: We aimed to evaluate the efficacy and safety of phacoemulsification with intravitreal 3 mg triamcinolone acetonide injection in preventing postoperative inflammation and complications in patients with non-infectious anterior uveitis and panuveitis complicated cataract. METHOD: In this retrospective cohort study, 140 uveitic cataract patients who received phacoemulsification and intraocular lens implantation in Shanxi Eye hospital from January 2018 to January 2020 were reviewed. The IVTA group (51 eyes of 41 patients) received intravitreal injection of 3 mg triamcinolone acetonide (TA) at the end of surgery, and the control group (51 eyes of 41 patients) without injection matched by propensity score matching were enrolled. Outcome measures were best corrected visual acuity (BCVA), anterior chamber inflammation, intraocular pressure, corneal endothelial cell density, central macular thickness and complications within 3 months follow-up. RESULTS: The degree of postoperative anterior chamber inflammation in the IVTA group was lighter than that in the control group (P < 0.05). The postoperative logMAR BCVA of anterior uveitis was better and improved more quickly in the IVTA group(P < 0.05). Postoperative time of using corticosteroids was shorter in the IVTA group as compared to the control group (P < 0.05). The central macular thickness at postoperative month 1 was statistically significantly lower in the IVTA group (P < 0.05). There were no statistically significant differences between the two groups in postoperative corneal endothelial cell density and intraocular pressure (P > 0.05). Two of 51 eyes (3.9%) in the IVTA group and 8 of 51 eyes (15.7%) in the control group had recurrence of uveitis; 6 of 45 eyes (13.3%) in the control group developed cystoid macular edema but none in the IVTA group; 11 of 51 eyes (21.6%) in the IVTA group and 22 of 51 eyes (43.1%) in the control group developed posterior synechiae postoperatively. CONCLUSIONS: Intraoperative Intravitreal injection of 3 mg TA is an effective and safe adjunctive therapy for preventing postoperative inflammation and complications to promote early recovery for anterior uveitis or panuveitis complicated cataract patients following phacoemulsification. TRIAL REGISTRATION: This retrospective cohort study was in accordance with the tenets of the Helsinki Declaration and was approved by the Shanxi Eye Hospital Ethics Committee. Written informed consent was obtained from all participants for their clinical records to be used in this study.

Various Spectrum Of Ocular Tuberculosis.

Mycobacterium Tuberculosis may infect any organ in the body, when it affects ocular tissue symptoms are vague and hence diagnosis is challenging, through a number of cases reported in our clinic it is emphasized to make quantiferon test as part of routine investigation for cases of presenting with uveitis thus leading to timely diagnosis and accurate treatment.

Polymer-free corticosteroid dimer implants for controlled and sustained drug delivery.

Polymeric drug carriers are widely used for providing temporal and/or spatial control of drug delivery, with corticosteroids being one class of drugs that have benefitted from their use for the treatment of inflammatory-mediated conditions. However, these polymer-based systems often have limited drug-loading capacity, suboptimal release kinetics, and/or promote adverse inflammatory responses. This manuscript investigates and describes a strategy for achieving controlled delivery of corticosteroids, based on a discovery that low molecular weight corticosteroid dimers can be processed into drug delivery implant materials using a broad range of established fabrication methods, without the use of polymers or excipients. These implants undergo surface erosion, achieving tightly controlled and reproducible drug release kinetics in vitro. As an example, when used as ocular implants in rats, a dexamethasone dimer implant is shown to effectively inhibit inflammation induced by lipopolysaccharide. In a rabbit model, dexamethasone dimer intravitreal implants demonstrate predictable pharmacokinetics and significantly extend drug release duration and efficacy (>6 months) compared to a leading commercial polymeric dexamethasone-releasing implant.

Protective effect of filgotinib in rat endotoxin-induced uveitis model.

PURPOSE: To investigate the protective effect of filgotinib in endotoxin-induced uveitis model in rats. MATERIALS AND METHOD: This study used 24 Wistar Albino rats. Group I (control group) included the healthy controls; in Group II (sham group), only 300 µg/kg intraperitoneal (ip) lipopolysaccharide (LPS) was administered; and in Group III (treatment group), 3 mg/kg/day filgotinib was administered orally for 10 days followed by 300 µg/kg ip LPS. In all groups, clinical activity scores were evaluated after 24 h. Moreover, histopathological and immunological examinations were performed. RESULTS: In Groups I, II, and III, the mean clinical activity and histopathological examination scores were 0.00, 3.25 ± 0.70, and 1.89 ± 0.60 and 0.00, 2.88 ± 1.12, and 1.44 ± 0.52, respectively. The clinical activity and histopathological examination scores were significantly increased in the sham group compared to the control group (p < 0.05); these findings were significantly reduced in the treatment group (p < 0.05). The mean TNF-α and IL-6 ELISA levels in all groups were 50.20 ± 3.24, 59.87 ± 2.98, and 54.34 ± 4.62 and 30.88 ± 1.79, 36.77 ± 1.21, and 33.66 ± 1.86, respectively. The TNF-α and IL-6 ELISA levels were significantly decreased in the treatment group compared to the sham group (p < 0.05); there was no significant difference between the treatment group and the control group (p = 0.105, p = 0.067, respectively) CONCLUSION: Filgotinib may be an alternative treatment option in preventing the development of noninfectious uveitis.

Longdan Xiegan Decoction alleviates experimental autoimmune uveitis in rats by inhibiting Notch signaling pathway activation and Th17 cell differentiation.

This study aimed to investigate the dynamic effects of the traditional Chinese medicine compound Longdan Xiegan Decoction (LXD) on the inhibition of Notch signaling pathway activation and T helper (Th) cell differentiation in rats with experimental autoimmune uveitis (EAU). Based on a network pharmacology strategy, we conducted protein interaction network analysis to construct an active ingredient-disease treatment network. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were further used to screen out the possible signaling pathways regulated by LXD in the treatment of uveitis. In the subsequent functional studies, we established an EAU rat model and investigated the regulatory role of LXD in the Notch signaling pathway and Th cell differentiation in rats with EAU. Female Lewis rats were randomly divided into a normal control (NC) group, an EAU group, and an LXD group. After the induction of EAU, the ocular inflammation and pathological changes in the rats in each group were observed; for documentation, a scanning laser ophthalmoscope (SLO) was used to observe fundus inflammation on day 12 after immunization. Additionally, quantitative polymerase chain reaction (Q-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression of Notch1, DLL4, IL-10 and IL-17A in the spleen, lymph nodes and ocular tissues of each group at 0, 6, 9, 12, 15 and 18 days after immunization. In addition, the dynamic frequencies of the CD4+, CD8+, Th17 and Treg cell subsets in the spleen, lymph nodes and ocular tissues were measured by flow cytometry. We found that the Notch signaling pathway was activated and the Th17 frequency was elevated in rats with EAU, leading to disrupted CD4+/CD8+ and Th17/Treg balance. The expression of Notch1, DLL4 and IL-17 mRNA and proteins in the EAU and LXD groups reached a peak on day 12, and then gradually decreased (all P < 0.05), and the ratios of the CD4+/CD8+ and Th17/Treg also peaked on day 12. However, after treatment with LXD, the expression of Notch1, DLL4 and IL-17 mRNA and proteins was significantly decreased (all P < 0.05), and the CD4+/CD8+ and Th17/Treg ratios significantly gradually returns to balance. LXD can efficiently inhibit Th17 cell differentiation, decrease inflammatory cytokine expression, and restore the CD4+/CD8+ and Th17/Treg balance by inhibiting the activation of the Notch signaling pathway in rats with EAU, thus effectively alleviating eye inflammation, protecting eye tissue structures, and positively regulating the immune state of the whole body and the intraocular microenvironment.

The protective function of invariant natural killer T cells in the relapse of experimental autoimmune uveoretinitis.

Experimental autoimmune uveoretinitis (EAU) in mice provides a useful platform to study the pathogenesis and experimental therapeutics of human uveitis. One often used EAU model employs C57BL/6 (B6) mice sensitized with a peptide residue having 1 to 20 amino acids of human interphotoreceptor retinoid binding protein (hIRBP1-20). The model using the B6 background has permitted a liberal use of genetically engineered strains and has provided insights for understanding uveoretinitis. However, this is usually acute/monophasic and does not represent human uveoretinitis that is characterized as a chronic/recurrent disease. Several chronic/recurrent EAU models have been developed; of these, we employed administration of staphylococcal enterotoxin B (SEB) for relapse in the present study, and found that recurrence was induced at day 24 after primary immunization, which is thought to be the convalescent phase. We reported the activation of invariant natural killer T (iNKT)-cells upon primary immunization of the EAU model mice with the ligand RCAI-56, which was found to mitigate the disease in our previous study. Here, we first attempted to ameliorate EAU in the relapse model using a preventive regimen by activating iNKT cells at the same time relapse induction (day 24) or in a regimen after 3 days of relapse induction (day 27). The preventive as well as post-inductive regimens were successful in reducing histopathological scores by inhibiting the Ag-specific Th17-biased response. Collectively, activation of iNKT cells may be useful to mitigate the relapse response of EAU induced with SEB.

The Protective Effects of VVN001 on LPS-Induced Inflammatory Responses in Human RPE Cells and in a Mouse Model of EIU.

To investigate protective effects of VVN001 on lipopolysaccharide (LPS)-induced inflammatory response in human retinal pigment epithelial (RPE) cells and in a mouse model of endotoxin-induced uveitis (EIU), and to explore the underlying mechanisms. Human primary RPE (hRPE) and ARPE-19 cells were pretreated with or without VVN001 for 1 h followed by 10 µg/mL LPS stimulation for 24 h. mRNA, and protein levels of inflammatory cytokines were analyzed with real-time PCR, western blotting, and ELISA. EIU was induced by intravitreal injection of 125 ng LPS in female BALB/c mice. VVN001 eye drops (1%) were locally administrated every 4 h for 24 h after LPS injection. Clinical scores were assessed with a slit lamp. mRNA and protein levels of inflammatory cytokines were investigated simultaneously. Compared with the LPS group, VVN001 pretreatment significantly reduced mRNA expressions of intercellular adhesion molecule-1 (ICAM-1), IL-6, IL-8, TNF-α, IL-1ß, IL-18, caspase-1 in hRPE, and ARPE-19 cells. Protein overproduction of ICAM-1, TNF-α, IL-1ß, NLRP3, caspase-1 P20, and p-IκBα/IκBα stimulated by LPS was suppressed by VVN001 pretreatment. In vivo, VVN001 significantly reduced the average clinical score from 5.0 to 1.3 in EIU mice. Furthermore, overproduction of ICAM-1, IL-1ß, NLRP3, caspase-1 P20, and p-IκBα/IκBα at mRNA and protein levels were remarkably suppressed by VVN001. VVN001 alleviated the inflammatory response induced by LPS both in vitro and in vivo. The effect of anti-inflammation is associated with inhibiting the overproduction of ICAM-1 and blocking the activation of NLRP3 inflammasome and the NF-κB signaling pathway.

Post-surgical management of cataract: Light and dark in the 2020s.

Cataract surgery is the most frequently performed elective surgery worldwide. Although considered a safe procedure, potentially sight-threatening adverse events are possible. Among these, post-surgical inflammation and infections are the most relevant. Anti-inflammatory drugs, such as corticosteroids, and topical antibiotics are the pillars for the treatment of inflammation and for the prevention of infections. However, uncertainties remain regarding the duration of both topical antibiotic prophylaxis and corticosteroid treatment. LEADER7, a recent international clinical study conducted with the new fixed combination of levofloxacin and dexamethasone eye drops in patients undergoing uncomplicated cataract surgery, found that 1-week topical antibiotic prophylaxis is just as effective as the 2-week course commonly used in clinical practice. The study also showed that treatment for 1 week with dexamethasone results in complete resolution of inflammatory signs and symptoms in over 85% of patients, for whom further prolongation of corticosteroid treatment is, therefore, not necessary. This new treatment strategy can represent a significant step forward to reduce the unjustified use of prophylactic antibiotics after cataract surgery, limiting the emergence of bacterial resistance, as well as representing an opportunity to optimize the use and safety of the corticosteroid treatment.

Dracocephalum heterophyllum (DH) Exhibits Potent Anti-Proliferative Effects on Autoreactive CD4+ T Cells and Ameliorates the Development of Experimental Autoimmune Uveitis.

Experimental autoimmune uveitis (EAU) is a CD4+ T cell-mediated organ-specific autoimmune disease and has been considered as a model of human autoimmune uveitis. Dracocephalum heterophyllum (DH) is a Chinese herbal medicine used in treating hepatitis. DH suppressed the production of inflammatory cytokines through the recruitment of myeloid-derived suppressor cells (MDSCs) to the liver. However, it remains elusive whether DH can directly regulate CD4+ T cell biology and hence ameliorates the development of CD4+ T cell-mediated autoimmune disease. In the current study, we found that DH extract significantly suppressed the production of pro-inflammatory cytokines by CD4+ T cells. Further study showed that DH didn't affect the activation, differentiation, and apoptosis of CD4+ T cells. Instead, it significantly suppressed the proliferation of conventional CD4+ T cells both in vitro and in vivo. Mechanistic study showed that DH-treated CD4+ T cells were partially arrested at the G2/M phase of the cell cycle because of the enhanced inhibitory phosphorylation of Cdc2 (Tyr15). In addition, we demonstrated that treatment with DH significantly ameliorated EAU in mice through suppressing the proliferation of autoreactive antigen specific CD4+ T cells. Taken together, the current study indicates that DH-mediated suppression of CD4+ T cell proliferation may provide a promising therapeutic strategy for treating CD4+ T cell-mediated diseases.

T cell-intrinsic role for Nod2 in protection against Th17-mediated uveitis.

Mutations in nucleotide-binding oligomerization domain-containing protein 2 (NOD2) cause Blau syndrome, an inflammatory disorder characterized by uveitis. The antimicrobial functions of Nod2 are well-established, yet the cellular mechanisms by which dysregulated Nod2 causes uveitis remain unknown. Here, we report a non-conventional, T cell-intrinsic function for Nod2 in suppression of Th17 immunity and experimental uveitis. Reconstitution of lymphopenic hosts with Nod2-/- CD4+ T cells or retina-specific autoreactive CD4+ T cells lacking Nod2 reveals a T cell-autonomous, Rip2-independent mechanism for Nod2 in uveitis. In naive animals, Nod2 operates downstream of TCR ligation to suppress activation of memory CD4+ T cells that associate with an autoreactive-like profile involving IL-17 and Ccr7. Interestingly, CD4+ T cells from two Blau syndrome patients show elevated IL-17 and increased CCR7. Our data define Nod2 as a T cell-intrinsic rheostat of Th17 immunity, and open new avenues for T cell-based therapies for Nod2-associated disorders such as Blau syndrome.

Kallistatin Attenuates Experimental Autoimmune Uveitis by Inhibiting Activation of T Cells.

Experimental autoimmune uveoretinitis (EAU) is a mouse model of human autoimmune uveitis. EAU spontaneously resolves and is marked by ocular autoantigen-specific regulatory immunity in the spleen. Kallikrein binding protein (KBP) or kallistatin is a serine proteinase inhibitor that inhibits angiogenesis and inflammation, but its role in autoimmune uveitis has not been explored. We report that T cells activation is inhibited and EAU is attenuated in human KBP (HKBP) mice with no significant difference in the Treg population that we previously identified both before and after recovery from EAU. Moreover, following EAU immunization HKBP mice have potent ocular autoantigen specific regulatory immunity that is functionally suppressive.

Tetramethylpyrazine attenuates endotoxin-induced retinal inflammation by inhibiting microglial activation via the TLR4/NF-κB signalling pathway.

Ocular inflammation is a common pathological condition of a series of retinal degenerative diseases. Tetramethylpyrazine (TMP), a Chinese herbal extraction, is widely used in the treatment of several ocular diseases in Eastern countries. However, the exact mechanisms correlating the vision protective effects of TMP have not been elucidated. Thus, this study aimed to investigate TMP's molecular targets in anti-inflammatory activity in endotoxin lipopolysaccharide (LPS)-induced retinal inflammation both in vitro and in vivo. The primary cultured retinal microglial cells were pretreated with TMP and then activated by LPS. We found pretreatment with TMP significantly inhibited LPS-induced upregulation of CD68, a marker of mononuclear microglia activation. The morphological changes induced by LPS were also inhibited by the TMP pretreatment. Moreover, Toll like receptor 4 (TLR4), phosphorylation of inhibitor of NF-κB alpha (p-IκB-α) and the translocation of nuclear factor kappa B p65 (NF-κB p65) were significantly downregulated in retinal microglial cells with TMP pretreatment, which indicated that TMP might suppress LPS-induced retinal microglial activation through TLR4/NF-κB signalling pathway. And these results were confirmed in vivo. Pretreatment with TMP inhibited microglial activation, migration and regeneration, especially in ganglion cell layer (GCL). In addition to the inhibition of TLR4, TMP significantly inhibited the translocation of NF-κB p-65 to the nucleus in vivo. The downstream genes of NF-κB, such as the pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and interleukin-1ß (IL-1ß), were significantly downregulated by TMP pretreatment in the retina. Accordingly, the increased expression of cleaved caspase-3 and the decreased ratio of B-cell lymphoma-2 (Bcl-2) to Bcl-2 associated X Protein (Bax) were significantly attenuated by TMP. TUNEL assay also demonstrated that TMP exerted neuroprotective effects in the retina. Therefore, this study elucidated a novel mechanism that TMP inhibits retinal inflammation by inhibiting microglial activation via a TLR4/NF-κB signalling pathway.

Aminooxy-Acetic Acid Inhibits Experimental Autoimmune Uveitis by Modulating the Balance between Effector and Regulatory Lymphocyte Subsets.

PURPOSE: A small molecular compound, aminooxy-acetic acid (AOA), has been shown to modulate experimental autoimmune encephalomyelitis (EAE). The current study was designed to investigate whether AOA has a similar effect on the development of experimental autoimmune uveitis (EAU) and to further explore underlying mechanisms of this drug. METHODS: EAU was induced in C57BL/6J mice by immunization with interphotoreceptor retinoid-binding protein peptide 651-670 (IRBP 651-670). AOA (500µg or 750µg) or vehicle was administered by intraperitoneal injection from day 10 to 14 after EAU induction. The severity was assessed by clinical and histological scores. The integrity of the blood retinal barrier was detected with Evans Blue. Frequencies of splenic Th1, Th17 and Foxp3+ Treg cells were examined by flow cytometry. The production of cytokines was tested by ELISA. The mRNA expression of IL-17, IFN-γ and IL-10 was detected by RT-PCR. The expression of p-Stat1 and NF-κB was detected by Western Blotting. RESULTS: AOA was found to markedly inhibit the severity of EAU, as determined by clinical and histopathological examinations. AOA can relieve the leakage of blood retinal barrier (BRB). Functional studies found a decreased frequency of Th1 and Th17 cells and an increased frequency of Treg cells in EAU mice as compared with controls. Further studies showed that AOA not only downregulated the production of the proinflammatory cytokines including IFN-γ and IL-17 but also upregulated the expression of an anti-inflammatory cytokine such as IL-10, which might be caused by inhibiting the expressions of p-Stat1 and NF-κB. CONCLUSION: This study shows that AOA inhibits the severity and development of EAU by modulating the balance between regulatory and pathogenic lymphocyte subsets.

A20 Inhibits Intraocular Inflammation in Mice by Regulating the Function of CD4+T Cells and RPE Cells.

A20 is a negative regulator of inflammation and immunity and plays a role in several autoimmune and inflammatory diseases. Here, we demonstrate that A20 overexpression significantly ameliorates severity of EAU by inhibiting the infiltration of Th1 and Th17 cells, and by protecting integrity of the blood retinal barrier. In vitro studies showed that A20 silencing could promote CD4+T cells toward a Th1 and Th17 phenotype. A decreased expression of A20 in CD4+T cells was noticed in active BD patients but not in VKH patients. Furthermore, silencing of A20 in hRPE cells induced the production of IL-6, IL-8, and MCP-1 and downregulated ZO-1 and occludin expression which is mediated by inhibition of MAPK and NF-κB pathways. This study reveals a mechanism by which A20 prevents autoimmune uveitis.

Resolution of uveitis.

Autoimmune uveitis is a sight-threatening, rare disease, potentially leading to blindness. Uveitis is a synonym for intraocular inflammation, presenting as various clinical phenotypes with different underlying immune responses in patients, whereas different animal models usually represent one certain clinical and immunological type of uveitis due to genetic uniformity and the method of disease induction. T cells recognizing intraocular antigens initiate the disease, recruiting inflammatory cells (granulocytes, monocytes/macrophages) to the eyes, which cause the damage of the tissue. The treatment of uveitis so far aims at downregulation of inflammation to protect the ocular tissues from damage, and at immunosuppression to stop fueling T cell reactivity. Uveitis is usually prevented by specific mechanisms of the ocular immune privilege and the blood-eye-barriers, but once the disease is induced, mechanisms of the immune privilege as well as a variety of novel regulatory features including new Treg cell populations and suppressive cytokines are induced to downregulate the ocular inflammation and T cell responses and to avoid relapses and chronicity. Here we describe mechanisms of regulation observed in experimental animal models as well as detected in studies with peripheral lymphocytes from patients.