The Cytokine IL-17A Limits Th17 Pathogenicity via a Negative Feedback Loop Driven by Autocrine Induction of IL-24.

Dysregulated Th17 cell responses underlie multiple inflammatory and autoimmune diseases, including autoimmune uveitis and its animal model, EAU. However, clinical trials targeting IL-17A in uveitis were not successful. Here, we report that Th17 cells were regulated by their own signature cytokine, IL-17A. Loss of IL-17A in autopathogenic Th17 cells did not reduce their pathogenicity and instead elevated their expression of the Th17 cytokines GM-CSF and IL-17F. Mechanistic in vitro studies revealed a Th17 cell-intrinsic autocrine loop triggered by binding of IL-17A to its receptor, leading to activation of the transcription factor NF-κB and induction of IL-24, which repressed the Th17 cytokine program. In vivo, IL-24 treatment ameliorated Th17-induced EAU, whereas silencing of IL-24 in Th17 cells enhanced disease. This regulatory pathway also operated in human Th17 cells. Thus, IL-17A limits pathogenicity of Th17 cells by inducing IL-24. These findings may explain the disappointing therapeutic effect of targeting IL-17A in uveitis.

Transcription factor EGR2 alleviates autoimmune uveitis via activation of GDF15 to modulate the retinal microglial phenotype.

Uveitis is a vision-threatening disease primarily driven by a dysregulated immune response, with retinal microglia playing a pivotal role in its progression. Although the transcription factor EGR2 is known to be closely associated with uveitis, including Vogt-Koyanagi-Harada disease and Behcet's disease, and is essential for maintaining the dynamic homeostasis of autoimmunity, its exact role in uveitis remains unclear. In this study, diminished EGR2 expression was observed in both retinal microglia from experimental autoimmune uveitis (EAU) mice and inflammation-induced human microglia cell line (HMC3). We constructed a mice model with conditional knockout of EGR2 in microglia and found that EGR2 deficiency resulted in increased intraocular inflammation. Meanwhile, EGR2 overexpression downregulated the expression of inflammatory cytokines as well as cell migration and proliferation in HMC3 cells. Next, RNA sequencing and ChIP-PCR results indicated that EGR2 directly bound to its downstream target growth differentiation factor 15 (GDF15) and further regulated GDF15 transcription. Furthermore, intravitreal injection of GDF15 recombinant protein was shown to ameliorate EAU progression in vivo. Meanwhile, knockdown of GDF15 reversed the phenotype of EGR2 overexpression-induced microglial inflammation in vitro. In summary, this study highlighted the protective role of the transcription factor EGR2 in AU by modulating the microglial phenotype. GFD15 was identified as a downstream target of EGR2, providing a unique target for uveitis treatment.

Dimethyl itaconate inhibits antigen-specific Th17 cell responses and autoimmune inflammation via modulating NRF2/STAT3 signaling.

Pathogenic Th17 cells play a crucial role in autoimmune diseases like uveitis and its animal model, experimental autoimmune uveitis (EAU). Dimethyl itaconate (DMI) possesses potent anti-inflammatory effects. However, there is still a lack of knowledge about the role of DMI in regulating pathogenic Th17 cells and EAU. Here, we reported that intraperitoneal administration of DMI significantly inhibited the severity of EAU via selectively suppressing Th17 cell responses. In vitro antigen stimulation studies revealed that DMI dramatically decreased the frequencies and function of antigen-specific Th17, but not Th1, cells. Moreover, DMI hampered the differentiation of naive CD4+ T cells toward pathogenic Th17 cells. DMI-treated DCs produced less IL-1ß, IL-6, and IL-23, and displayed an impaired ability to stimulate antigen-specific Th17 activation. Mechanistically, DMI activated the NRF2/HO-1 pathway and suppressed STAT3 signaling, which subsequently restrains p-STAT3 nuclear translocation, leading to decreased pathogenic Th17 cell responses. Thus, we have identified an important role for DMI in regulating pathogenic Th17 cells, supporting DMI as a promising therapy in Th17 cell-driven autoimmune diseases including uveitis.

Beneficial mechanisms of dimethyl fumarate in autoimmune uveitis: insights from single-cell RNA sequencing.

BACKGROUND: Dimethyl fumarate (DMF) is a fumaric acid ester that exhibits immunoregulatory and anti-inflammatory properties. However, the function of DMF in autoimmune uveitis (AU) is incompletely understood, and studies comprehensively exploring the impact of DMF on immune cells are still lacking. METHODS: To explore the function of DMF in uveitis and its underlying mechanisms, we conducted single-cell RNA sequencing (scRNA-seq) on the cervical draining lymph node (CDLN) cells of normal, experimental autoimmune uveitis (EAU), and DMF-treated EAU mice. Additionally, we integrated scRNA-seq data of the retina and CDLNs to identify the potential impact of DMF on ocular immune cell infiltration. Flow cytometry was conducted to verify the potential target molecules of DMF. RESULTS: Our study showed that DMF treatment effectively ameliorated EAU symptoms. The proportional and transcriptional alterations in each immune cell type during EAU were reversed by DMF treatment. Bioinformatics analysis in our study indicated that the enhanced expression of Pim1 and Cxcr4 in EAU was reversed by DMF treatment. Further experiments demonstrated that DMF restored the balance between effector T (Teff) /regulatory T (Treg) cells through inhibiting the pathway of PIM1-protein kinase B (AKT)-Forkhead box O1 (FOXO1). By incorporating the scRNA-seq data of the retina from EAU mice into analysis, our study identified that T cells highly expressing Pim1 and Cxcr4 were enriched in the retina. DMF repressed the ocular infiltration of Teff cells, and this effect might depend on its inhibition of PIM1 and CXCR4 expression. Additionally, our study indicated that DMF might reduce the proportion of plasma cells by inhibiting PIM1 expression in B cells. CONCLUSIONS: DMF effectively attenuated EAU symptoms. During EAU, DMF reversed the Teff/Treg cell imbalance and suppressed the ocular infiltration of Teff cells by inhibiting PIM1 and CXCR4 expression. Thus, DMF may act as a new drug option for the treatment of AU.

CCR5-overexpressing mesenchymal stem cells protect against experimental autoimmune uveitis: insights from single-cell transcriptome analysis.

Autoimmune uveitis is a leading cause of severe vision loss, and animal models provide unique opportunities for studying its pathogenesis and therapeutic strategies. Here we employ scRNA-seq, RNA-seq and various molecular and cellular approaches to characterize mouse models of classical experimental autoimmune uveitis (EAU), revealing that EAU causes broad retinal neuron degeneration and marker downregulation, and that Müller glia may act as antigen-presenting cells. Moreover, EAU immune response is primarily driven by Th1 cells, and results in dramatic upregulation of CC chemokines, especially CCL5, in the EAU retina. Accordingly, overexpression of CCR5, a CCL5 receptor, in mesenchymal stem cells (MSCs) enhances their homing capacity and improves their immunomodulatory outcomes in preventing EAU, by reducing infiltrating T cells and activated microglia and suppressing Nlrp3 inflammasome activation. Taken together, our data not only provide valuable insights into the molecular characteristics of EAU but also open an avenue for innovative MSC-based therapy.

Small extracellular vesicle-based delivery of interleukin-10 improves treatment of experimental autoimmune uveitis.

Non-infectious uveitis is an intraocular autoimmune disease mainly characterized by immune dysregulation of the eye, which may cause blindness if not well treated. Interleukin 10 (IL-10) is a potent cytokine with multiple immunoregulatory functions. However, it's in vivo activity is unstable owing to its inherent protein instability and short plasma half-life. Therefore, our previous research tried to establish IL-10-overexpressing MSC-sEVs (sEVs-IL10) using lentiviral transfection. While this approach indeed improved drug delivery, it also suffered from tedious procedures and limited loading efficiency. Accordingly, we constructed a novel MSC-sEVs-based delivery system for IL-10 (IL-10@sEVs) by sonication. The obtained formulation (IL-10@sEVs) had relatively higher loading efficiency and exerted a more profound immunomodulatory effect than sEVs-IL10 in vitro. Furthermore, IL-10@sEVs had significant therapeutic effects in a mouse model of experimental autoimmune uveitis (EAU) by decreasing the percentage of Th17 cells, increasing regulatory T cells in the eye, and draining lymph nodes. In summary, sonication outperforms conventional transfection methods for loading IL-10 into MSC-sEVs.

Long-lived autoreactive memory CD4+ T cells mediate the sustained retinopathy in chronic autoimmune uveitis.

Chronic uveitis comprises heterogeneous clinical entities characterized by sustained and recurrent intraocular inflammation that is believed to be driven by autoimmune responses. The management of chronic uveitis is challenging with the limited availability of efficacious treatments, and the underlying mechanisms mediating disease chronicity remain poorly understood as the majority of experimental data are derived from the acute phase of the disease (the first 2-3 weeks post-induction). Herein, we investigated the key cellular mechanisms underlying chronic intraocular inflammation using our recently established murine model of chronic autoimmune uveitis. We demonstrate unique long-lived CD44hi IL-7R+ IL-15R+ CD4+ memory T cells in both retina and secondary lymphoid organs after 3 months postinduction of autoimmune uveitis. These memory T cells functionally exhibit antigen-specific proliferation and activation in response to retinal peptide stimulation in vitro. Critically, these effector-memory T cells are capable of effectively trafficking to the retina and accumulating in the local tissues secreting both IL-17 and IFN-γ upon adoptively transferred, leading to retinal structural and functional damage. Thus, our data reveal the critical uveitogenic functions of memory CD4+ T cells in sustaining chronic intraocular inflammation, suggesting that memory T cells can be a novel and promising therapeutic target for treating chronic uveitis in future translational studies.

Fine particulate matter potentiates Th17-cell pathogenicity in experimental autoimmune uveitis via ferroptosis.

The effect of fine particulate matter (PM2.5) on the development of uveitis remains unclear. Therefore, this study was designed to investigate the role of PM2.5 in experimental autoimmune uveitis (EAU) and its potential mechanism. Our results showed that PM2.5 could exacerbate the activity of EAU, as evidenced by severer clinical and pathological changes, correlated with elevated Th17 cells frequency and IL-17A expression. Proteomic analysis revealed ferroptosis was the most significant pathway. In vivo, the levels of Fe2+, ROS, lipid ROS, and malondialdehyde, as well as the expression of TFRC, HMOX1, FTH1, and FTL1 in CD4+ T cells were increased, while GSH/GSSG ratio and the expression of ACSL1 and GPX4 were decreased after PM2.5 exposure. In vitro, the expression of TFRC and HMOX1 were increased, while the expression FTH1, FTL1, ACSL1, and GPX4 were decreased after PM2.5 exposure. Ferrostatin-1 effectively alleviated PM2.5-induced intraocular inflammation and suppressed the frequency of Th17 cells. These results suggest that PM2.5 could aggravate intraocular inflammation and immune response in EAU mice through ferroptosis. Ferroptosis could be a potential marker for the prevention and treatment of uveitis.

CD83+ B cells alleviate uveitis through inhibiting DCs by sCD83.

Soluble CD83 (sCD83) exerts immunosuppressive functions in many autoimmune diseases, including experimental autoimmune uveitis (EAU), but the cells and mechanisms involved are unclear. This study showed that CD83+ B cells were the main sources of sCD83. They alleviated the symptoms of EAU and decreased the percentage of T cells and DCs in the eyes and lymph nodes. These CD83+ B cells decreased IL-1ß, IL-18 and IFN-γ secretion by DCs through sCD83. sCD83 interacted with GTPase Ras-related protein (Rab1a) in DCs to promote Rab1a accumulation in autolysosomes and inhibit mTORC1 phosphorylation and NLRP3 expression. Hence, CD83+ B cells play a regulatory role in EAU by secreting sCD83. The lack of regulation of CD83+ B cells might be an important factor leading to hyperimmune activation in patients with autoimmune uveitis. CD83+ B cells suppress activated DCs in uveitis, indicating the potential therapeutic role of CD83+ B cells in uveitis.

Pertussis toxin-induced inhibition of Wnt/ß-catenin signaling in dendritic cells promotes an autoimmune response in experimental autoimmune uveitis.

BACKGROUND: Previous reports have indicated that disrupting the Wnt/ß-catenin pathway in dendritic cells (DCs) may affect the progression of autoimmune inflammation; however, the factors and timing that regulate Wnt/ß-catenin signaling have not been clearly understood. METHODS: Experimental autoimmune uveitis (EAU) mice and Vogt-Koyanagi-Harada disease (VKH) patient samples were used to detect the expression of Wnt/ß-catenin pathway genes. Western blot, real-time PCR, flow cytometry, and ELISA were performed to examine the expression of components of the Wnt/ß-catenin pathway and inflammatory factors. DC-specific ß-catenin knockout mice and 6-bromoindirubin-3'-oxime (BIO) administered mice were used to observe the effect of disrupting the Wnt pathway on EAU pathogenesis. RESULTS: Wnt/ß-catenin signaling was inhibited in DCs during the induction phase of EAU. The inhibition was mediated by pertussis toxin (PTX), which promoted DC maturation, in turn promoting pathogenic T cell proliferation and differentiation. In vivo experiments confirmed that deleting ß-catenin in DCs enhanced EAU severity, and pre-injection of PTX advanced EAU onset. Administration of a Wnt activator (BIO) limited the effects of PTX, in turn ameliorating EAU. CONCLUSIONS: Our results demonstrate that PTX plays a key role as a virulence factor in initiating autoimmune inflammation via DCs by inhibiting Wnt/ß-catenin signaling in EAU, and highlight the potential mechanism by which infection can trigger apparent autoimmunity.

Progesterone attenuates Th17-cell pathogenicity in autoimmune uveitis via Id2/Pim1 axis.

BACKGROUND: Autoimmune uveitis (AU) is the most common ophthalmic autoimmune disease (AD) and is characterized by a complex etiology, high morbidity, and high rate of blindness. AU remission has been observed in pregnant female patients. However, the effects of progesterone (PRG), a critical hormone for reproduction, on the treatment of AU and the regulatory mechanisms remain unclear. METHODS: To this end, we established experimental autoimmune uveitis (EAU) animal models and constructed a high-dimensional immune atlas of EAU-model mice undergoing PRG treatment to explore the underlying therapeutic mechanisms of PRG using single-cell RNA sequencing. RESULTS: We found that PRG ameliorated retinal lesions and inflammatory infiltration in EAU-model mice. Further single-cell analysis indicated that PRG reversed the EAU-induced expression of inflammatory genes (AP-1 family, S100a family, and Cxcr4) and pathological processes related to inflammatory cell migration, activation, and differentiation. Notably, PRG was found to regulate the Th17/Treg imbalance by increasing the reduced regulatory functional mediators of Tregs and diminishing the overactivation of pathological Th17 cells. Moreover, the Id2/Pim1 axis, IL-23/Th17/GM-CSF signaling, and enhanced Th17 pathogenicity during EAU were reversed by PRG treatment, resulting in the alleviation of EAU inflammation and treatment of AD. CONCLUSIONS: Our study provides a comprehensive single-cell map of the immunomodulatory effects of PRG therapy on EAU and elaborates on the possible therapeutic mechanisms, providing novel insights into its application for treating autoimmune diseases.

Interleukin-17 receptor C is essential for the pro-inflammatory pathogenicity of granulocyte-macrophage-colony-stimulating factor-producing T helper cells in experimental autoimmune uveitis.

Autoimmune uveitis is an inflammatory disorder of the eye triggered by the responses of autoreactive T cells to ocular autoantigens. This study aims to understand the role of granulocyte-macrophage-colony-stimulating factor (GM-CSF)-producing T helper (ThGM) cells in the pathophysiology of mouse experimental autoimmune uveitis (EAU). We established an EAU model by immunizing mice with interphotoreceptor retinoid-binding protein (IRBP) 651-670. Splenic or eye-infiltrating ThGM cells were analyzed and enriched by flow cytometry according to the levels of an array of surface markers, transcription factors, and cytokines. Lentiviral transduction was conducted to silence or overexpress the target gene in differentiated ThGM cells. The adoptive transfer was applied to determine the pathogenicity of ThGM cells in vivo. We found that ThGM cells were present in the spleen and the eye after EAU induction. Both splenic and eye-infiltrating ThGM cells were phenotypically CD4+CCR7-CXCR3-CCR6-CCR10hi. Eye-infiltrating ThGM cells up-regulated interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and IL-17 receptor C (IL-17RC) relative to splenic ThGM cells. IL-17RC overexpression enabled interleukin-17A (IL-17A)-induced up-regulation of IL-1ß and IL-6 production in ThGM cells. Adoptive transfer of IL-17RC overexpressing ThGM cells exacerbated EAU severity, as evidenced by a higher histology score as well as increased pro-inflammatory cytokines and inflammatory cells in the eye. However, IL-17RC-silenced ThGM cells did not impact EAU. Therefore, for the first time, this study unveils the essential pro-inflammatory role of IL-17RC-expressing ThGM cells in EAU pathophysiology. We discovered a novel mechanism underlying the pathophysiology of autoimmune uveitis.

Galectin-3 regulates microglial activation and promotes inflammation through TLR4/MyD88/NF-kB in experimental autoimmune uveitis.

Galectin-3, an attractive molecule of innate immunity, has been reported to be involved in the neuroinflammatory diseases. However, the role of Galectin-3 in autoimmune uveitis is still unclear. The purpose of this study was to investigate the effect and mechanism of Galectin-3 on microglial activation and inflammation of experimental autoimmune uveitis (EAU). We immunized female C57BL/6 J mice with IRBP651-670 to induce EAU and the specific inhibitor was intravitreally injected in EAU mice. Disease severity was evaluated by clinical and histopathological scores. Immunofluorescence, western blot, qRT-PCR analysis and immunoprecipitation were used to detect the functional phenotypes and mechanisms on microglia after Galectin-3 inhibition. Our results showed that the expression of Galectin-3 was conspicuously increased in microglia of EAU retinas. The specific inhibitor of Galectin-3, TD139 was found to ameliorate the clinical and histological manifestations of EAU mice. In addition, TD139 reduced the expression of proinflammatory factors in vivo and vitro, which are related to the severity of uveitis. In mechanism, TD139 down-regulated the expression of TLR4 and MyD88, and then inhibited the activation of NF-κB p65 in microglia. In conclusion, Galectin-3 may play important roles in a variety of immune related diseases including autoimmune uveitis. Additionally, the inhibition of Galectin-3 may attenuate the microglial activation and inflammatory response through TLR4/MyD88/NF-κB pathway, highlighting a potential therapeutic target of Galectin-3 for autoimmune uveitis.

N6-methyladenosine demethylase FTO regulates inflammatory cytokine secretion and tight junctions in retinal pigment epithelium cells.

OBJECTIVE: Uveitis is an intraocular inflammatory disease. Epigenetics has been associated with its pathogenesis. However, the role of N6-methyladenosine (m6A) in uveitis has not been reported. We aimed to examine the role of m6A and its regulatory mechanism in experimental autoimmune uveitis (EAU). METHODS: The mRNA expression of m6A-related methylase and demethylase of retinal pigment epithelium (RPE) between mice with EAU and control mice was detected by RT-qPCR. The overall m6A level of ARPE-19 cells was detected by an m6A quantitative detection kit. Cell proliferation was observed by CCK-8 assays, and ELISA was used to test the secretion of inflammatory factors. The expression of tight junction proteins and the target genes of FTO were examined by western blotting and MeRIP-PCR. RESULTS: A decreased expression of FTO in RPE cells was found in mice with EAU. Increased overall m6A%, proliferation of cells and secretion of IL-6, IL-8 and MCP-1 were found after FTO knockdown in ARPE-19 cells. However, ZO-1 and occludin protein expression was decreased. ATF4 protein expression was decreased in the FTO knockdown (shFTO) group as compared with the control (shNC) group. In contrast, the m6A level of ATF4 was elevated, as shown by MeRIP-PCR. Functional analysis showed that p-STAT3 expression was increased in the shFTO group, and the change in occludin expression was reversed in ATF4 rescue experiment. CONCLUSION: FTO may affect the translation of ATF4 by regulating its m6A level, resulting in the increased expression of p-STAT3 and inflammatory factors, and leading to uveitis.

The pro-inflammatory effect of triglyceride on human CD4+ T cells and experimental autoimmune uveitis.

Aberrant lipid metabolism plays a role in inflammation and progression of autoimmune diseases but the definite mechanism remains unclear. In this study we investigate lipidomic profiles in Behçet's disease (BD) and the role of triglyceride (TAG) in the pathogenesis of autoimmune uveitis. Lipidomics revealed a distinct lipid metabolite profile including increased TAG metabolites in plasma of active BD patients. TAG could stimulate the proliferation, IL-17 and IFN-γ expression by CD4+ T cells and Th1, Th17 cell differentiation in vitro, but did not influence neutrophils. A922500 inhibited the TAG generation, ameliorated the EAU severity, decreased Th17 frequency and IL-17 expression by CD4+ T cells in vivo. The proteomocis analysis showed an up-regulation of apoptosis-related protein, Pik3r2, in CD4+ T cells from A922500-treated mice. In conclusion, TAG can stimulate human CD4+ T cells and the inhibition of its generation could significantly ameliorate EAU activity in association with down-regulated Th17 cell response.

Melatonin, an endogenous hormone, modulates Th17 cells via the reactive-oxygen species/TXNIP/HIF-1α axis to alleviate autoimmune uveitis.

BACKGROUND: Melatonin, an indoleamine produced by the pineal gland, plays a pivotal role in maintaining circadian rhythm homeostasis. Recently, the strong antioxidant and anti-inflammatory properties of melatonin have attracted attention of researchers. We evaluated the therapeutic efficacy of melatonin in experimental autoimmune uveitis (EAU), which is a representative animal model of human autoimmune uveitis. METHODS: EAU was induced in mice via immunization with the peptide interphotoreceptor retinoid binding protein 1-20 (IRBP1-20). Melatonin was then administered via intraperitoneal injection to induce protection against EAU. With EAU induction for 14 days, clinical and histopathological scores were graded to evaluate the disease progression. T lymphocytes accumulation and the expression of inflammatory cytokines in the retinas were assessed via flow cytometry and RT-PCR, respectively. T helper 1 (Th1), T helper 17 (Th17), and regulatory T (Treg) cells were detected via flow cytometry for both in vivo and in vitro experiments. Reactive-oxygen species (ROS) from CD4 + T cells was tested via flow cytometry. The expression of thioredoxin-interacting protein (TXNIP) and hypoxia-inducible factor 1 alpha (HIF-1α) proteins were quantified via western blot. RESULTS: Melatonin treatment resulted in notable attenuation of ocular inflammation in EAU mice, evidenced by decreasing optic disc edema, few signs of retinal vasculitis, and minimal retinal and choroidal infiltrates. Mechanistic studies revealed that melatonin restricted the proliferation of peripheral Th1 and Th17 cells by suppressing their transcription factors and potentiated Treg cells. In vitro studies corroborated that melatonin restrained the polarization of retina-specific T cells towards Th17 and Th1 cells in addition to enhancing the proportion of Treg cells. Pretreatment of retina-specific T cells with melatonin failed to induce EAU in naïve recipients. Furthermore, the ROS/ TXNIP/ HIF-1α pathway was shown to mediate the therapeutic effect of melatonin in EAU. CONCLUSIONS: Melatonin regulates autoimmune T cells by restraining effector T cells and facilitating Treg generation, indicating that melatonin could be a hopeful treatment alternative for autoimmune uveitis.

Parental uveitis causes elevated hair loss in offspring of C57BL/6J mice.

Our previous study demonstrated that parental uveitis in a susceptible population can cause hair loss and increase the susceptibility to experimental autoimmune uveitis (EAU) in offspring. However, it is unclear whether parental uveitis affects the development of offspring in an EAU-moderate-susceptible population. Herein, moderate-susceptible C57BL/6J mice were immunized with inter-photoreceptor retinoid binding protein (IRBP) 651-670 to develop EAU and were kept together for mating. Gross examination and histopathological changes of the offspring gestated with parental uveitis were observed to evaluate the impact of parental uveitis on the development of the offspring. Differentially expressed genes (DEGs) were screened by RNA sequencing in the affected skin and eyeball of the offspring on postnatal day 27. Adult offspring were injected 75 µg IRBP651-670 to evaluate their susceptibility to EAU. Gross examination in the offspring revealed hair loss on postnatal days 11-31. Histopathological observation showed increased melanin granules and hair follicles of skin in the affected offspring with hair loss. Gene Ontology (GO) analysis in the skin revealed differential expression of genes involved in the mitotic cell cycle, response to endogenous stimulus, hair follicle development, and hair cycle. The DEGs in the skin were predominately associated with the cell cycle and peroxisome proliferator-activated receptor (PPAR) signaling pathway. The GO enrichment analysis in the eyeball showed differential expression of genes involved in the nervous system development, camera-type eye photoreceptor cell differentiation, neuron projection morphogenesis, axon development, and calcium-induced calcium release activity; enriched pathways included the circadian entrainment and glutamatergic synapses. No increased susceptibility to EAU in offspring gestated from parental remitting EAU was observed at a low-dose 75 µg IRBP induction. These results suggested that parental uveitis in a moderate-susceptible population could affect the skin development and DEG profiles of skin and eyeball related to the response to endogenous stimulus, the PPAR signaling pathway, and glutamatergic synapse, which provides the molecular evidence to explain the influence of parental uveitis on offspring development.

Gut Microbes and Eye Disease.

Microbial symbionts in the gut are increasingly recognized as having important effects on health and disease, but have only recently begun to be linked to diseases of the eye. We review current research on the intestinal microbiota's relationship to ocular disease, focusing on autoimmune uveitis, diabetic retinopathy, age-related macular degeneration, and primary-open angle glaucoma. We discuss findings and limitations of this exciting new area of ophthalmology research and explore possible future disease-modifying treatments.

Retinal microglia initiate neuroinflammation in ocular autoimmunity.

Autoimmune uveitis is a sight-threatening ocular inflammatory condition in which the retina and uveal tissues become a target of autoreactive immune cells. While microglia have been studied extensively in autoimmune uveitis, their exact function remains uncertain. The objective of the current study was to determine whether resident microglia are necessary and sufficient to initiate and amplify retinal inflammation in autoimmune uveitis. In this study, we clearly demonstrate that microglia are essential for initiating infiltration of immune cells utilizing a murine model of experimental autoimmune uveoretinitis (EAU) and the recently identified microglia-specific marker P2ry12. Initiating disease is the primary function of microglia in EAU, since eliminating microglia during the later stages of EAU had little effect, indicating that the function of circulating leukocytes is to amplify and sustain destructive inflammation once microglia have triggered disease. In the absence of microglia, uveitis does not develop, since leukocytes cannot gain entry through the blood-retinal barrier, illustrating that microglia play a critical role in regulating infiltration of inflammatory cells into the retina.

Comprehensive analysis of a mouse model of spontaneous uveoretinitis using single-cell RNA sequencing.

Autoimmune uveoretinitis is a significant cause of visual loss, and mouse models offer unique opportunities to study its disease mechanisms. Aire-/- mice fail to express self-antigens in the thymus, exhibit reduced central tolerance, and develop a spontaneous, chronic, and progressive uveoretinitis. Using single-cell RNA sequencing (scRNA-seq), we characterized wild-type and Aire-/- retinas to define, in a comprehensive and unbiased manner, the cell populations and gene expression patterns associated with disease. Based on scRNA-seq, immunostaining, and in situ hybridization, we infer that 1) the dominant effector response in Aire-/- retinas is Th1-driven, 2) a subset of monocytes convert to either a macrophage/microglia state or a dendritic cell state, 3) the development of tertiary lymphoid structures constitutes part of the Aire-/- retinal phenotype, 4) all major resident retinal cell types respond to interferon gamma (IFNG) by changing their patterns of gene expression, and 5) Muller glia up-regulate specific genes in response to IFN gamma and may act as antigen-presenting cells.