Peripheral blood monocytes reveal an activated phenotype in pediatric uveitis

Uveitis Associated with Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is the most common cause of uveitis in children. While symptoms are usually mild, persistent eye inflammation could lead to severe complications and impaired vision. It is essential that JIA patients at risk are diagnosed with uveitis early, receive adequate treatment, and avoid developing complications, such as cataract, glaucoma, and amblyopia. The purpose of this mini-review is to summarize the screening strategies and clinical management for JIA-associated uveitis (JIA-U) as well as the current state of molecular markers linked to this condition. Because glaucoma is one of the most common causes of visual loss in JIA-U, special focus will be put on this serious complication. We conclude by describing the current evidence regarding the long-standing question of whether chronic anterior uveitis without arthritis may be the same disease entity as JIA-U.

A Blood Protein Signature Stratifies Clinical Response to csDMARD Therapy in Pediatric Uveitis

PURPOSE

To identify a serum biomarker signature that can help predict response to conventional synthetic disease-modifying antirheumatic drug (csDMARD) therapy in pediatric noninfectious uveitis.

METHODS

In this case-control cohort study, we performed a 368-plex proteomic analysis of serum samples of 72 treatment-free patients with active uveitis (new onset or relapse) and 15 healthy controls. Among these, 37 patients were sampled at diagnosis before commencing csDMARD therapy. After 6 months, csDMARD response was evaluated and cases were categorized as "responder" or "nonresponder." Patients were considered "nonresponders" if remission was not achieved under csDMARD therapy. Serum protein profiles were used to train random forest models to predict csDMARD failure and compared to a model based on eight clinical parameters at diagnosis (e.g., maximum cell grade).

RESULTS

In total, 19 of 37 (51%) cases were categorized as csDMARD nonresponders. We identified a 10-protein signature that could predict csDMARD failure with an overall accuracy of 84%, which was higher compared to a model based on eight clinical parameters (73% accuracy). Adjusting for age, sex, anatomic location of uveitis, and cell grade, cases stratified by the 10-protein signature at diagnosis showed a large difference in risk for csDMARD failure (hazard ratio, 12.8; 95% confidence interval, 2.5-64.6; P = 0.002).

CONCLUSIONS

Machine learning models based on the serum proteome can stratify pediatric patients with uveitis at high risk for csDMARD failure.

TRANSLATIONAL RELEVANCE

The identified protein signature has implications for the development of clinical decision tools that integrate clinical parameters with biological data to better predict the best treatment option.

Intraocular dendritic cells characterize HLA-B27-associated acute anterior uveitis

Uveitis describes a heterogeneous group of inflammatory eye diseases characterized by infiltration of leukocytes into the uveal tissues. Uveitis associated with the HLA haplotype B27 (HLA-B27) is a common subtype of uveitis and a prototypical ocular immune-mediated disease. Local immune mechanisms driving human uveitis are poorly characterized mainly due to the limited available biomaterial and subsequent technical limitations. Here, we provide the first high-resolution characterization of intraocular leukocytes in HLA-B27-positive (n = 4) and -negative (n = 2) anterior uveitis and an infectious endophthalmitis control (n = 1) by combining single-cell RNA-sequencing with flow cytometry and protein analysis. Ocular cell infiltrates consisted primarily of lymphocytes in both subtypes of uveitis and of myeloid cells in infectious endophthalmitis. HLA-B27-positive uveitis exclusively featured a plasmacytoid and classical dendritic cell (cDC) infiltrate. Moreover, cDCs were central in predicted local cell-cell communication. This suggests a unique pattern of ocular leukocyte infiltration in HLA-B27-positive uveitis with relevance to DCs.

Targeting folate receptor beta on monocytes/macrophages renders rapid inflammation resolution independent of root causes

Provoked by sterile/nonsterile insults, prolonged monocyte mobilization and uncontrolled monocyte/macrophage activation can pose imminent or impending harm to the affected organs. Curiously, folate receptor beta (FRβ), with subnanomolar affinity for the vitamin folic acid (FA), is upregulated during immune activation in hematopoietic cells of the myeloid lineage. This phenomenon has inspired a strong interest in exploring FRβ-directed diagnostics/therapeutics. Previously, we have reported that FA-targeted aminopterin (AMT) therapy can modulate macrophage function and effectively treat animal models of inflammation. Our current investigation of a lead compound (EC2319) leads to discovery of a highly FR-specific mechanism of action independent of the root causes against inflammatory monocytes. We further show that EC2319 suppresses interleukin-6/interleukin-1β release by FRβ⁺ monocytes in a triple co-culture leukemic model of cytokine release syndrome with anti-CD19 chimeric antigen receptor T cells. Because of its chemical stability and metabolically activated linker, EC2319 demonstrates favorable pharmacokinetic characteristics and cross-species translatability to support future pre-clinical and clinical development.

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Functional folate receptor beta is transiently expressed on inflammatory monocytes

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EC2319 is an enhancement of traditional dihydrofolate reductase inhibitors

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EC2319 anti-monocyte activity correlates with local/systemic therapeutic benefit

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EC2319 inhibition of cytokine release suggests emergency use for hyperinflammation

Surface AMP deaminase 2 as a novel regulator modifying extracellular adenine nucleotide metabolism

Adenine nucleotides represent crucial immunomodulators in the extracellular environment. The ectonucleotidases CD39 and CD73 are responsible for the sequential catabolism of ATP to adenosine via AMP, thus promoting an anti-inflammatory milieu induced by the "adenosine halo". AMPD2 intracellularly mediates AMP deamination to IMP, thereby both enhancing the degradation of inflammatory ATP and reducing the formation of anti-inflammatory adenosine. Here, we show that this enzyme is expressed on the surface of human immune cells and its predominance may modify inflammatory states by altering the extracellular milieu. Surface AMPD2 (eAMPD2) expression on monocytes was verified by immunoblot, surface biotinylation, mass spectrometry, and immunofluorescence microscopy. Flow cytometry revealed enhanced monocytic eAMPD2 expression after TLR stimulation. PBMCs from patients with rheumatoid arthritis displayed significantly higher levels of eAMPD2 expression compared with healthy controls. Furthermore, the product of AMPD2-IMP-exerted anti-inflammatory effects, while the levels of extracellular adenosine were not impaired by an increased eAMPD2 expression. In summary, our study identifies eAMPD2 as a novel regulator of the extracellular ATP-adenosine balance adding to the immunomodulatory CD39-CD73 system.

Next-Generation HLA Sequence Analysis Uncovers Shared Risk Alleles Between Clinically Distinct Forms of Childhood Uveitis

Purpose

Classical alleles of the human leukocyte antigen (HLA) complex have been linked to specific entities of pediatric noninfectious uveitis, yet genetic predisposition encoded by the HLA super-locus across the patient population remains understudied.

Methods

We performed next-generation full-length sequencing of HLA-A, HLA-B, HLA-C, HLA-DPB1, HLA-DQB1, and HLA-DRB1 in 280 cases. Dense genotype data from 499 Dutch controls from Genome of the Netherlands were imputed using an HLA-specific reference panel (n = 5225 samples from European ancestry). Cases and controls were compared using logistic regression models adjusting for sex.

Results

In total, 179 common and rare alleles were detected. Considering all cases and controls, HLA-DQB1*04:02 and HLA-DRB1*08:01 were identified as the principal HLA association, which was mainly driven by 92 cases with juvenile idiopathic arthritis-associated uveitis (JIA-U). The HLA-DQB1*04:02-HLA-DRB1*08:01 haplotype was also the primary association for the phenotypically similar idiopathic chronic anterior uveitis without arthritis (CAU). Also, HLA-DQB1*05:03 was an independent risk allele for CAU, but not in JIA-U. Analysis of 185 cases with other forms of uveitis revealed HLA-wide associations (P < 2.79 × 10⁻⁴) for HLA-DRB1*01:02, HLA-DRB1*04:03, and HLA-DQB1*05:03, which could be primarily attributed to cases with panuveitis. Finally, amino acid substitution modeling revealed that aspartic acid at position 57 that distinguishes the risk allele HLA-DQB1*05:03 (for CAU and panuveitis) from nonrisk alleles, significantly increased the binding capacity of naturally presented ligands to HLA-DQ.

Conclusions

These results uncovered novel shared HLA associations among clinically distinct phenotypes of pediatric uveitis and highlight genetic predisposition affecting the antigen presentation pathway.

A clinical prediction model for estimating the risk of developing uveitis in patients with juvenile idiopathic arthritis

OBJECTIVE

To build a prediction model for uveitis in children with JIA for use in current clinical practice.

METHODS

Data from the international observational Pharmachild registry were used. Adjusted risk factors as well as predictors for JIA-associated uveitis (JIA-U) were determined using multivariable logistic regression models. The prediction model was selected based on the Akaike information criterion. Bootstrap resampling was used to adjust the final prediction model for optimism.

RESULTS

JIA-U occurred in 1102 of 5529 JIA patients (19.9%). The majority of patients that developed JIA-U were female (74.1%), ANA positive (66.0%) and had oligoarthritis (59.9%). JIA-U was rarely seen in patients with systemic arthritis (0.5%) and RF positive polyarthritis (0.2%). Independent risk factors for JIA-U were ANA positivity [odds ratio (OR): 1.88 (95% CI: 1.54, 2.30)] and HLA-B27 positivity [OR: 1.48 (95% CI: 1.12, 1.95)] while older age at JIA onset was an independent protective factor [OR: 0.84 (9%% CI: 0.81, 0.87)]. On multivariable analysis, the combination of age at JIA onset [OR: 0.84 (95% CI: 0.82, 0.86)], JIA category and ANA positivity [OR: 2.02 (95% CI: 1.73, 2.36)] had the highest discriminative power among the prediction models considered (optimism-adjusted area under the receiver operating characteristic curve = 0.75).

CONCLUSION

We developed an easy to read model for individual patients with JIA to inform patients/parents on the probability of developing uveitis.

Update on noninfectious uveitis in children and its treatment

PURPOSE OF REVIEW

To give an overview of recently published articles covering risk factors, novel biomarkers and treatment for noninfectious uveitis in children.

RECENT FINDINGS

In the last few years, several genetic markers, serum biomarkers, aqueous humor markers, tear biomarkers and clinical factors have been identified, which are associated with childhood noninfectious uveitis. We describe the most important reports in this field that may help to tailor the screening and monitoring of this population in the future and might become the target of novel therapies. The advances in the biologic therapy of paediatric uveitis, thanks to evidence provided by the SYCAMORE, ADJUVITE and APTITUDE trials, offer new possibilities for the treatment of patients who fail methotrexate with adalimumab and tocilizumab. We discuss the importance of comprehensive outcome measures as proposed by the Multinational Interdisciplinary Working Group for Uveitis in Childhood (MIWGUC).

SUMMARY

Paediatric noninfectious uveitis is a sight-threatening condition and the identification of risk factors and novel biomarkers is critical for tailored management. Biologic therapies are revolutionizing the outcomes of patients resistant to conventional therapy. Increasing our knowledge of disease pathogenesis is crucial to improve targeting of screening to those at highest risk and stratification of treatments.

Whole Transcriptome Analysis Reveals Heterogeneity in B Cell Memory Populations in Patients With Juvenile Idiopathic Arthritis-Associated Uveitis

Purpose

Patients with juvenile idiopathic arthritis (JIA) are prone to developing chronic anterior uveitis (JIA-U+). Although several risk factors for JIA-U+ have been identified, the underlying etiology is poorly understood. Histopathological studies demonstrate B cell infiltrates in eye tissues of patients with JIA-U+.

Methods

We performed transcriptome profiling of peripheral blood CD19-positive B cells taken from 14 cases with JIA-U+, 13 JIA cases without uveitis (JIA-U-), and five healthy controls. Deconvolution-based estimation was used to determine the immune cell fractions for each sample.

Results

Deconvolution results revealed that naive B cells made up on average 71% of the CD19-positive cell fractions analyzed. Differential expression analysis identified 614 differentially expressed genes (DEGs) between the groups at nominal significance and six genes at a false discovery rate of 5% (FDR < 0.05). Head-to-head comparison of all JIA-U- versus JIA-U+ revealed no DEGs in the CD19+ B cell pool (FDR < 0.05). However, principal component analysis based on a panel of key genes for B cell subsets revealed that JIA-U+ cases bifurcate into distinct clusters, characterized by markedly disparate expression for genes associated with specific memory B cell populations. CIBERSORT analysis of the overall transcriptome of the new uveitis cluster identified an increased proportion of memory B cells.

Conclusion

These data show that JIA-U- and JIA-U+ have a globally similar transcriptome considering the global peripheral CD19-positive B cell pool. However, heterogeneity in B cell memory genes among cases with uveitis suggests a role for specific memory B cell subsets in the etiology of JIA-U+.

Phenotype of Innate Immune Cells in Uveitis Associated with Axial Spondyloarthritis- and Juvenile Idiopathic Arthritis-associated Uveitis

Purpose: To analyze circulating immune cells in patients with anterior uveitis (AU) associated to axial spondyloarthritis (SpA), or juvenile idiopathic arthritis (JIA).Methods: Venous blood samples were collected from healthy controls (n = 16), and either SpA (n = 19) or JIA (n = 23) patients with associated anterior uveitis (AU) during active flare, or after ≥3 months of inactivity. Frequencies of CD56⁺, MHC-I⁺, and S100A9⁺ monocytes, CCR7⁺ dendritic cells, CD56^+dim natural killer (NK) cells and CD3⁺CD56^bright T-cells were analyzed via flow cytometry. Serum S100A8/A9 levels were determined via ELISA.Results: SpA patients showed a reduced frequency of CD56^+dim NK cells during uveitis activity, a constitutively activated monocyte phenotype, and elevated S100A8/A9 serum levels. In contrast, JIAU patients showed elevated frequencies of CD56⁺ monocytes and CCR7⁺ DC.Conclusion: Phenotype of peripheral immune cells differ between patients, probably contributing to different courses of acute onset AU in SpA and insidious onset AU in JIAU patients.Abbreviations: AU: anterior uveitis, AR: arthritis, JIA: juvenile idiopathic arthritis, SpA: axial spondyloarthritis.

Can the CRP/albumin Ratio be Used as a New Indicator of Activation in Patients with Uveitis?

Purpose: To evaluate whether the C-reactive protein (CRP)/albumin ratio (CAR) in patients with uveitis during an attack is a marker that can give information about the activity, severity and prognosis of the disease.Methods: This study included 35 patients with an uveitis attack and 35 healthy volunteers. The localization and severity of uveitis were recorded. Patients' complete blood count (CBC) during the attack, CRP, CAR, erythrocyte sedimentation rate(ESR), neutrophil/lymphocyte ratio(NLR), and platelet/lymphocyte ratio(PLR) were recorded.Results: The mean age was 34.1 ± 12.5 years for the 35 uveitis cases and 30.1 ± 4.1 years for the healthy volunteers. CRP and CAR were significantly higher in uveitis patients (p = .015 and 0.011, respectively). While CRP and CAR were significantly higher in severe anterior uveitis than mild anterior uveitis (p = .036 and 0.022, respectively), only CAR was significantly higher in severe posterior and panuveitis than mild ones(p = .017).Conclusion: CAR may be an important parameter in determining the activation of the uveitis.

The Phenotype of Monocytes in Anterior Uveitis Depends on the HLA-B27 Status

HLA-B27 is the allele most frequently associated with human anterior uveitis. The majority of HLA-B27-positive [acute anterior uveitis (AAU)] patients develop clinically distinct symptoms with acute symptomatic onset of flare and a recurrent disease course characterized by a massive cellular ocular infiltrate during uveitis relapse. By contrast, uveitis in HLA-B27-negative [idiopathic anterior uveitis (IAU)] patients tends to develop a clinically less fulminant, more chronic, and typically asymptomatic disease course. To analyze systemic immune responses in the different uveitis entities, we analyzed peripheral blood cells by flow cytometry. In addition, as a pro-inflammatory biomarker serum, S100A8/A9 levels were quantified by ELISA from patients with AAU (n = 27) and IAU (n = 21), and in healthy controls (n = 30). Data were obtained either during active uveitis flare or after 3 months of inactivity. IAU patients showed a transiently increased frequency of CD56- and CD163-positive monocytes and of both granulocytic myeloid-derived suppressor cells and Th17 cells during active uveitis. By contrast, AAU patients showed an elevated frequency of monocytes, activated T cells, and elevated S100A8/A9 serum levels during clinically quiescent disease. The differentially regulated response of both innate and adaptive immune cells in the blood may be related to the clinically distinct characteristics of the two different uveitis entities.