Maturation profiles of peripheral blood dendritic cells in patients with endogenous uveitis

Causal role of immune cells in uveitis: a Mendelian randomization study

Background

Uveitis refers to a group inflammation affecting the uvea, retina, retinal blood vessels as well as vitreous body, which is one of the common causes of blindness. There is growing evidence linking different types of immune cells to uveitis, although it remains uncertain if these associations imply causal relationships. Recent advancements in high-density genetic markers like SNPs or CNVs for genotyping, along with the progress in genome-wide association studies (GWAS) technologies, have improved our understanding of the immunological mechanisms involved in ocular diseases. Therefore, our objective was to investigate the potential causal link between immune cells and uveitis using a Mendelian randomization study.

Methods

The exposure and outcome GWAS data for this study were sourced from an open-access database (https://gwas.mrcieu.ac.uk/). Two-sample MR analysis was utilized to evaluate the causal relationship between 731 immune cell features and uveitis. Various MR methods were employed to reduce bias and obtain dependable estimates of the causal link between the immune cell variables and the outcomes. Instrumental variable selection criteria were carefully chosen to enhance the accuracy and efficacy of the causal relationship between different immune cell types and the risk of uveitis.

Results

Using two-sample MR, IVW modeling showed that GAD had significant effect on immunophenotypes. CD3 levels on CD45RA- CD4+ T cells (OR = 1.087, 95%CI = 1.029 ~ 1.147, p = 0.003) and CD3 levels on CM CD4+ T cells (OR = 1.086, 95%CI = 1.033 ~ 1.141, p = 0.001) were found to be elevated in cases of uveitis. HLA DR levels in CD14- CD16+ monocyte cells (OR = 0.735, 95% CI = 0.635 ~ 0.850, p < 0.001) and HLA DR levels in NK cells (OR = 0.910, 95% CI = 0.851 ~ 0.972, p = 0.005) were observed to be reduced in individuals with uveitis. Furthermore, Two cells were identified to be significantly associated with uveitis risk: HLA DR on in NK cells (OR = 0.938, 95%CI = 0.899 ~ 0.979, p = 0.003), HLA DR on CD14- CD16+ monocytes (OR = 0.924, 95%CI = 0.878 ~ 0.972, p = 0.002).

Conclusion

This study highlights the intricate relationship between immune cells and generalized anxiety disorder using genetic methods, offering valuable insights for future clinical investigations.

Decoding Behcet's Uveitis: an In-depth review of pathogenesis and therapeutic advances

Behcet's disease (BD) is a rare but globally distributed vasculitis that primarily affects populations in the Mediterranean and Asian regions. Behcet's uveitis (BU) is a common manifestation of BD, occurring in over two-thirds of the patients. BU is characterized by bilateral, chronic, recurrent, non-granulomatous uveitis in association with complications such as retinal ischemia and atrophy, optic atrophy, macular ischemia, macular edema, and further neovascular complications (vitreous hemorrhage, neovascular glaucoma). Although the etiology and pathogenesis of BU remain unclear, numerous studies reveal that genetic factors (such as HLA-B51), dysregulated immune responses of both the innate and adaptive immune systems, infections (such as streptococcus), and environmental factors (such as GDP) are all involved in its development. Innate immunity, including hyperactivity of neutrophils and γδT cells and elevated NK1/NK2 ratios, has been shown to play an essential role in this disease. Adaptive immune system disturbance, including homeostatic perturbations, Th1, Th17 overaction, and Treg cell dysfunction, is thought to be involved in BU pathogenesis. Treatment of BU requires a tailored approach based on the location, severity of inflammation, and systemic manifestations. The therapy aims to achieve rapid inflammation suppression, preservation of vision, and prevention of recurrence. Systemic corticosteroids combined with other immunosuppressive agents have been widely used to treat BU, and beneficial effects are observed in most patients. Recently, biologics have been shown to be effective in treating refractory BU cases. Novel therapeutic targets for treating BU include the LCK gene, Th17/Treg balance, JAK pathway inhibition, and cytokines such as IL-17 and RORγt. This article summarizes the recent studies on BU, especially in terms of pathogenesis, diagnostic criteria and classification, auxiliary examination, and treatment options. A better understanding of the significance of microbiome composition, genetic basis, and persistent immune mechanisms, as well as advancements in identifying new biomarkers and implementing objective quantitative detection of BU, may greatly contribute to improving the adequate management of BU patients.

Immunopathophysiology and clinical impact of uveitis in inflammatory rheumatic diseases: An update

BACKGROUND

Uveitis is one of the most frequent ophthalmologic manifestations in rheumatology. Uveal inflammation can underlie a systemic inflammatory rheumatic disease (SIRD) in approximately 30% of cases with a significant burden on the quality of life since it represents a cause of blindness in up to 20% of cases in Western countries.

METHODS

In this review, we provide a comprehensive overview of the pathophysiology of uveitis associated with SIRDs. According to our literature survey on the epidemiology of uveitis among SIRDs, spondyloarthritides, Behçet's disease and sarcoidosis get the major impact.

RESULTS

In Behçet's uveitis, the key players are highly polarized Th1 and Th17 lymphocytes, natural killer T cells and γδ T cells. All contribute to a great destructive inflammatory environment with the most serious visual damage resulting from the involvement of the posterior segment of the eye. In contrast, spondyloarthritides-related uveitis derives from a complex interaction between genetic background and extra-ocular inflammatory mediators originating from enthesitis, arthritis, psoriatic lesions and microbiome pro-inflammatory alterations. In such conditions, the immune infiltration of CD4+ T cells, Th17 and natural killer cells along with pro-inflammatory cytokines, TNF-α among all, leads to intraocular inflammation. Lastly, granuloma formation represents the primary hallmark lesion in sarcoid uveitis. This suggests a profound link between the innate system that mainly recruits activated macrophages and adaptive system involving by Th1, Th17 and Th17.1 cells.

CONCLUSIONS

Awareness among rheumatologists of a potential severe ocular involvement generates new insights into targeted therapeutic approaches and personalized treatments for each patient.

Uveitis as a potential predictor of acute myocardial infarction in patients with Behcet's disease: a population-based cohort study

OBJECTIVES

To investigate whether uveitis is a predictor of acute myocardial infarction (AMI) among patients with Behcet's disease (BD).

DESIGN

Retrospective cohort study.

SETTING

Patients with BD were retrieved from the whole population of the Taiwan National Health Insurance Research Database from 1 January 2001 to 31 December 2013.

PARTICIPANTS

Among the 6508 patients with BD, 2517 (38.7%) were in the uveitis group and 3991 were in the non-uveitis group.

PRIMARY AND SECONDARY OUTCOME MEASURES

Kaplan-Meier curves were generated to compare the cumulative hazard of AMI in the uveitis and non-uveitis groups. Multivariate Cox regression analysis was used to estimate the adjusted HRs and 95% CI of AMI, and was adjusted for age, gender, systemic comorbidities (eg, hypertension, diabetes, hyperlipidaemia, smoking) and clinical manifestation of BD (eg, oral ulcers, genital ulcers, skin lesions, arthritis and gastrointestinal involvement).

RESULTS

The mean age of the BD cohort was 38.1±15.1 years. Compared with non-uveitis patients, uveitis patients were significantly younger and male predominant. There was no significant difference between the two groups for most proportions of systemic comorbidities and clinical manifestations. The Kaplan-Meier method with the log-rank test showed that the uveitis group had a significantly higher cumulative hazard for patients with AMI compared with the non-uveitis group (p<0.0001). In the multivariable Cox regression after adjustment for confounding factors, patients with uveitis had a significantly higher risk of AMI (adjusted HR 1.87; 95% CI 1.52 to 2.29). Other significant risk factors for AMI were age, hypertension, smoking, and skin lesions.

CONCLUSIONS

Statistical analyses from the nationwide database demonstrated that uveitis is a potential predictor of AMI in patients with BD.

Activated γδ T Cells Promote Dendritic Cell Maturation and Exacerbate the Development of Experimental Autoimmune Uveitis (EAU) in Mice

Our previous study reveals that gamma delta (γδ) T cells were activated and dendritic cells (DCs) underwent maturation during the inflammation phase in experimental autoimmune uveitis (EAU) mice, and the interaction between DCs and γδ T cells may significantly exacerbate the development of EAU. However, the interactions between DCs and γδ T cells that can affect DCs maturation to influence EAU development must be further addressed. In this study we showed that mature DC numbers in TCR-δ^-/- (KO) EAU mice were lower than those in wild-type (WT) C57BL/6 (B6) mice. The γδ T cells harvested from WT EAU mice secreted more interferon-γ (IFN-γ), however, after blocking IFN-γ, the maturation of DCs was significantly downregulated. By contrast, the percentage of IFN-γ- and IL-17-producing CD4⁺ T cells in KO EAU mice decreased to a greater extent than that in WT EAU mice during the inflammatory phase. Additionally, the levels of IFN-γ/IL-17 in serum were in agreement with those of CD4⁺ T cells. Furthermore, after activated γδ T cells injection, the inflammatory symptoms of EAU mice were more aggravated. In vitro co-cultures of both cell types showed that activated γδ T cells may induce DCs to generate higher levels of intracellular cell adhesion molecule-1 (ICAM-1/CD54), CD80, CD83, and CD86. Moreover, co-culture of the two cells may induce the activation of CD4⁺ T cells. Taken together, our results demonstrated that activated γδ T cells may promote DCs maturation and further enhance the generation of Th1/Th17 cells in EAU mice, resulting in exacerbated EAU.

Differences in Expression of Human Leukocyte Antigen Class II Subtypes and T Cell Subsets in Behçet's Disease with Arthritis

It has been reported Human Leukocyte Antigen (HLA) gene polymorphism is a risk factor for the development of Behçet’s disease (BD). In this study, the association of HLA class II subtypes HLA-DP, DQ, DR, and T cell subsets in BD patients with arthritis was evaluated. Frequencies of HLA-DP, DQ, DR positive cells, and T cell subsets in peripheral blood leukocytes (PBL) were measured by flow cytometric analysis in BD, and compared to rheumatoid arthritis as disease controls and healthy controls. Frequencies of HLA-DQ were significantly decreased in whole PBL and granulocytes of BD active patients as compared to healthy controls. In monocytes populations, proportions of HLA-DR positive cells were significantly increased in BD active patients as compared to healthy controls. Proportions of CD4+CCR7+ and CD8+CCR7+ cells were significantly higher in BD active patients than in BD inactive in whole PBL. Frequencies of CD4+CD62L- and CD8+CD62L- cells in lymphocytes were significantly decreased in active BD than those in inactive BD. There were also correlations between disease activity markers and T cell subsets. Our results revealed HLA-DP, DQ, and DR expressing cell frequencies and several T cell subsets were significantly correlated with BD arthritis symptoms.

Ocular Behcet's disease is associated with aberrant methylation of interferon regulatory factor 8 (IRF8) in monocyte-derived dendritic cells

Aberrant methylation of interferon regulatory factor 8 (IRF8) has been noted in various tumors. IRF8 has also been reported to be involved in many autoimmune diseases, including Behcet's disease (BD). However, the methylation status of IRF8 in BD has not been reported. To address this issue, we investigated whether the degree of methylation of IRF8 in dendritic cells (DCs) plays a role in the development of BD. We found a lower mRNA expression and a higher methylation level of IRF8 in active ocular BD patients as compared to normal subjects and inactive patients. Treatment with a demethylation agent, 5-Aza-2'-deoxycytidine (DAC) resulted in an increase of mRNA expression and a reduction of the IRF8 methylation level. It also down-regulated the expression of the co-stimulatory molecules CD86, CD80, CD40, and reduced the production of IL-6, IL-1β, IL-23 and IL-12. An inhibition of Th1/Th17 responses was observed as evidenced by a decreased production of IFN-γ, IL-17, and a reduction of IFN-γ/IL-17- producing CD4⁺ T cells following treatment with DAC. This study shows that active ocular BD patients have an aberrant IRF8 methylation status. These findings suggest that epigenetic control of IRF8 expression may offer a future target in the treatment of ocular BD.

Role of dendritic cell subsets in immunity and their contribution to noninfectious uveitis

Dendritic cells (DCs) are a heterogeneous population. Murine DCs consist of conventional DCs (cDCs) and plasmacytoid DCs (pDCs). In humans, the analogous populations are myeloid DCs (mDCs) and pDCs. Though distinct in phenotypes and functions, studies have shown that these DC subsets may interact or "crosstalk" during immune responses. For example, cDCs may facilitate pDC maturation, and pDCs may enhance antigen presentation of cDCs in certain pathogenic conditions or even take on a cDC phenotype themselves. The role of DCs in noninfectious uveitis has been studied primarily in the experimental autoimmune uveitis mouse model and to a more limited extent in patients. Recent evidence shows that the number, phenotype, and function of DC subsets are altered in this disease. We provide an overview of selected recent developments of pDCs and cDCs/mDCs, with special attention to their interaction and the dual roles of DC subsets in noninfectious uveitis.

Increased CD1c+ mDC1 with mature phenotype regulated by TNFα-p38 MAPK in autoimmune ocular inflammatory disease

In this study we investigated the role of blood CD1c(+) myeloid dendritic cells 1 (mDC1), a key mDC subtype, in patients with autoimmune uveitis. We observed a significant increase of blood CD1c(+) mDC1 in uveitis patients. The increased CD1c(+) mDC1 exhibited high HLADR expression and less antigen uptake. CD1c(+) mDC1 were divided into two subpopulations. CD1c(hi) mDC1 subpopulation showed less antigen uptake and higher HLADR expression compared to CD1c(lo) mDC1 subpopulation. Importantly, the CD1c(hi) mDC1 subpopulation was increased in uveitis patients. In vitro, mature monocyte-derived dendritic cells (MoDCs), characterized by lower levels of antigen uptake, induced more CD4(+)CD62L(-) T helper cell proliferation. The mature phenotype and function of CD1c(+) mDC1 were regulated by TNFα via a p38 MAPK-dependent pathway. These data show that alterations in the systemic immune response are involved in the pathogenesis of autoimmune uveitis and invite the therapeutic possibility of attenuating uveitis by manipulating blood CD1c(+) mDC1.

Levels of blood CD1c+ mDC1 and CD1chi mDC1 subpopulation reflect disease activity in noninfectious uveitis

PURPOSE

Myeloid dendritic cells (mDCs) play an important role in autoimmune diseases. However, the role of blood CD1c(+) myeloid dendritic cells 1 (mDC1s), the subset of human blood mDCs, is not well understood in noninfectious uveitis.

METHODS

Fresh peripheral blood samples from human noninfectious uveitis patients (n = 32) and healthy controls (HCs) (n = 64) were stained with FITC-Lineage 1 (Lin1), PERCP-HLADR, and PE-CD1c antibodies. The levels of mDC1 were quantified by using flow cytometric analysis. Longitudinal data from patients (n = 16) were analyzed to correlate the levels of mDC1 with disease activity.

RESULTS

Blood CD1c(+) mDC1 and its subpopulation, CD1c(hi) mDC1, were increased in uveitis patients compared with HCs. Longitudinal data demonstrated that both the CD1c(+) mDC1 and CD1c(hi) mDC1 subpopulation reflected a dynamic change in clinical uveitis activity: CD1c expression was increased in active uveitis but decreased when uveitis became inactive.

CONCLUSIONS

Given these observations, an alteration in blood CD1c(+) mDC1 and the CD1c(hi) mDC1 subpopulation could be a potential biomarker to monitor clinical uveitis activity within patients.

Immunopathogenesis of ocular Behçet's disease

Behçet's disease (BD) is a chronic recurrent systemic inflammatory disorder of unknown etiology characterized by oral and genital ulcerations, skin lesions, and uveitis. The ocular involvement of BD, or Behçet's uveitis (BU), is characterized by panuveitis or posterior uveitis with occlusive retinal vasculitis and tends to be more recurrent and sight threatening than other endogenous autoimmune uveitides, despite aggressive immunosuppression. Although pathogenesis of BD is unclear, researches have revealed that immunological aberrations may be the cornerstone of BD development. General hypothesis of BD pathogenesis is that inflammatory response is initiated by infectious agents or autoantigens in patients with predisposing genetic factors and perpetuated by both innate and acquired immunity. In addition, a network of immune mediators plays a substantial role in the inflammatory cascade. Recently, we found that the immunopathogenesis of BU is distinct from other autoimmune uveitides regarding intraocular effector cell profiles, maturation markers of dendritic cells, and the cytokine/chemokine environment. In addition, accumulating evidence indicates the involvement of Th17 cells in BD and BU. Recent studies on genetics and biologics therapies in refractory BU also support the immunological association with the pathogenesis of BU. In this review, we provide an overview of novel findings regarding the immunopathogenesis of BU.

Evaluation of the IL2/IL21, IL2RA and IL2RB genetic variants influence on the endogenous non-anterior uveitis genetic predisposition

BACKGROUND

Recently, different genetic variants located within the IL2/IL21 genetic region as well as within both IL2RA and IL2RB loci have been associated to multiple autoimmune disorders. We aimed to investigate for the first time the potential influence of the IL2/IL21, IL2RA and IL2RB most associated polymorphisms with autoimmunity on the endogenous non-anterior uveitis genetic predisposition.

METHODS

A total of 196 patients with endogenous non-anterior uveitis and 760 healthy controls, all of them from Caucasian population, were included in the current study. The IL2/IL21 (rs2069762, rs6822844 and rs907715), IL2RA (2104286, rs11594656 and rs12722495) and IL2RB (rs743777) genetic variants were genotyped using TaqMan® allelic discrimination assays.

RESULTS

A statistically significant difference was found for the rs6822844 (IL2/IL21 region) minor allele frequency in the group of uveitis patients compared with controls (P(-value)=0.02, OR=0.64 CI 95%=0.43-0.94) although the significance was lost after multiple testing correction. Furthermore, no evidence of association with uveitis was detected for the analyzed genetic variants of the IL2RA or IL2RB loci.

CONCLUSION

Our results indicate that analyzed IL2/IL21, IL2RA and IL2RB polymorphisms do not seem to play a significant role on the non-anterior uveitis genetic predisposition although further studies are needed in order to clear up the influence of these loci on the non-anterior uveitis susceptibility.