Aqueous Macrophages Contribute to Conserved CCL2 and CXCL10 Gradients in Uveitis

Purpose

Uveitis is a heterogenous group of inflammatory eye disease for which current cytokine-targeted immune therapies are effective for only a subset of patients. We hypothesized that despite pathophysiologic nuances that differentiate individual disease states, all forms of eye inflammation might share common mechanisms for immune cell recruitment. Identifying these mechanisms is critical for developing novel, broadly acting therapeutic strategies.

Design

Experimental study.

Subjects

Biospecimens from patients with active or inactive uveitis and healthy controls.

Methods

Protein concentration and single cell gene expression were assessed in aqueous fluid biopsies and plasma samples from deidentified patients with uveitis or healthy controls.

Main Outcome Measures

The concentration of 31 inflammatory proteins was measured in all aqueous samples, as well as plasma samples from patients with active uveitis. Chemokine and cytokine ligand and receptor expression were assessed in individual cell types from aqueous biopsies obtained from patients with active uveitis.

Results

We identified 6 chemokines that were both elevated in active uveitis compared with controls and enriched in aqueous compared with plasma during active uveitis (C-C motif chemokine ligand [CCL]2, C-X-C motif chemokine ligand [CXCL]10, CXCL9, CXCL8, CCL3, and CCL14), forming potential gradients for migration of immune cells from the blood to the eye. Of these, CCL2 and CXCL10 were consistently enriched in the aqueous of all patients in our cohort, as well as in a larger cohort of patients from a previously published study. These data suggest that CCL2 and CXCL10 are key mediators in immune cell migration to the eye during uveitis. Next, single cell RNA sequencing suggested that macrophages contribute to aqueous enrichment of CCL2 and CXCL10 during human uveitis. Finally, using chemokine ligand and receptor expression mapping, we identified a broad signaling network for macrophage-derived CCL2 and CXCL10 in human uveitis.

Conclusions

These data suggest that ocular macrophages may play a central role, via CCL2 and CXCL10 production, in recruiting inflammatory cells to the eye in patients with uveitis.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Optic Disc Edema Is an Under-Recognized Feature of Birdshot Chorioretinitis

BACKGROUND

Optic disc edema is a feature of many ophthalmic and neurologic conditions. It remains an underappreciated feature of birdshot chorioretinitis (BSCR), leading to delay in diagnosis and treatment. The purpose of our study was to identify clinical features that are concomitant with optic disc edema and suggest a diagnosis of BSCR.

METHODS

Retrospective multicenter case series of 29 patients who were referred to a neuro-ophthalmologist or uveitis specialist for evaluation of disc edema and were ultimately diagnosed with BSCR.

RESULTS

Fifty-four eyes of 30 patients, from the practices of 15 uveitis specialists, met the eligibility criteria. In addition to disc edema, concomitant features in all patients included vitritis, chorioretinal lesions, and retinal vasculitis. Visual recovery to 20/40 or better occurred in 26 of 29 patients. Visual acuity remained 20/100 or worse in 2 patients previously diagnosed with idiopathic intracranial hypertension, 1 patient previously diagnosed with optic neuritis, and 1 patient for whom treatment was delayed for years, leading to optic disc atrophy.

CONCLUSIONS

Optic disc edema is a presenting feature in some cases of BSCR. A diagnosis of BSCR should be considered when disc edema occurs with vitritis, chorioretinal inflammation, and retinal vasculitis. Patients should be referred to a uveitis specialist for treatment.

Autoimmunity-associated T cell receptors recognize HLA-B*27-bound peptides

Human leucocyte antigen B*27 (HLA-B*27) is strongly associated with inflammatory diseases of the spine and pelvis (for example, ankylosing spondylitis (AS)) and the eye (that is, acute anterior uveitis (AAU))1. How HLA-B*27 facilitates disease remains unknown, but one possible mechanism could involve presentation of pathogenic peptides to CD8+ T cells. Here we isolated orphan T cell receptors (TCRs) expressing a disease-associated public β-chain variable region-complementary-determining region 3β (BV9-CDR3β) motif2-4 from blood and synovial fluid T cells from individuals with AS and from the eye in individuals with AAU. These TCRs showed consistent α-chain variable region (AV21) chain pairing and were clonally expanded in the joint and eye. We used HLA-B*27:05 yeast display peptide libraries to identify shared self-peptides and microbial peptides that activated the AS- and AAU-derived TCRs. Structural analysis revealed that TCR cross-reactivity for peptide-MHC was rooted in a shared binding motif present in both self-antigens and microbial antigens that engages the BV9-CDR3β TCRs. These findings support the hypothesis that microbial antigens and self-antigens could play a pathogenic role in HLA-B*27-associated disease.

Loss of Mir146b with aging contributes to inflammation and mitochondrial dysfunction in thioglycollate-elicited peritoneal macrophages

Macrophages undergo programmatic changes with age, leading to altered cytokine polarization and immune dysfunction, shifting these critical immune cells from protective sentinels to disease promoters. The molecular mechanisms underlying macrophage inflammaging are poorly understood. Using an unbiased RNA sequencing (RNA-seq) approach, we identified Mir146b as a microRNA whose expression progressively and unidirectionally declined with age in thioglycollate-elicited murine macrophages. Mir146b deficiency led to altered macrophage cytokine expression and reduced mitochondrial metabolic activity, two hallmarks of cellular aging. Single-cell RNA-seq identified patterns of altered inflammation and interferon gamma signaling in Mir146b-deficient macrophages. Identification of Mir146b as a potential regulator of macrophage aging provides novel insights into immune dysfunction associated with aging.

Identifying RNA Biomarkers and Molecular Pathways Involved in Multiple Subtypes of Uveitis

PURPOSE

Uveitis is a heterogeneous collection of diseases. We tested the hypothesis that despite the diversity of uveitides, there could be common mechanisms shared by multiple subtypes, and that evidence of these common mechanisms may be detected as gene expression profiles in whole blood.

DESIGN

Cohort study.

METHODS

Ninety subjects with uveitis including axial spondyloarthritis (n = 17), sarcoidosis (n = 13), inflammatory bowel disease (n = 12), tubulointerstitial nephritis with uveitis (n = 10), or idiopathic uveitis (n = 38) as well as 18 healthy controls were enrolled, predominantly at Oregon Health & Science University. RNA-Seq data generated from peripheral, whole blood identified 19,859 unique transcripts. We analyzed gene expression pathways via Kyoto Encyclopedia of Genes and Genomes and Gene Ontology (GO). We validated our list of upregulated genes by comparison to a previously published study on peripheral blood gene expression among 50 subjects with diverse forms of uveitis.

RESULTS

Both the Kyoto Encyclopedia of Genes and Genomes and GO analysis identified multiple shared pathways or GO terms with a P value of <.0001. Almost all pathways related to the immune response and/or response to an infection. A total of 119 individual transcripts were upregulated by at least 1.5-fold and false discovery rate <.05, and 61 were downregulated by similar criteria. Comparing mRNA from our study with a false discovery rate <.05 and the prior report, we identified 10 common gene transcripts: ICAM1, IL15RA, IL15, IRF1, IL10RB, GSK3A, TYK2, MEF2A, MEF2B, and MEF2D.

CONCLUSIONS

Many forms of uveitis share overlapping mechanisms. These data support the concept that a single therapeutic approach could benefit diverse forms of this disease.

Clinicomolecular Identification of Conserved and Individualized Features of Granulomatous Uveitis

Objective

To identify molecular features that distinguish individuals with shared clinical features of granulomatous uveitis.

Design

Cross-sectional, observational study.

Participants

Four eyes from patients with active granulomatous uveitis.

Methods

We performed single-cell RNA-sequencing with antigen-receptor sequence analysis to obtain an unbiased gene expression survey of ocular immune cells and identify clonally expanded lymphocytes.

Main Outcomes Measures

For each inflamed eye, we measured the proportion of distinct immune cell types, the amount of B or T cell clonal expansion, and the transcriptional profile of T and B cells.

Results

Each individual had robust clonal expansion arising from a single T or B cell lineage, suggesting distinct, antigen-driven pathogenic processes in each patient. This variability in clonal expansion was mirrored by individual variability in CD4 T cell populations, whereas ocular CD8 T cells and B cells were more transcriptionally similar between patients. Finally, ocular B cells displayed evidence of class-switching and plasmablast differentiation within the ocular microenvironment, providing additional support for antigen-driven immune responses in granulomatous uveitis.

Conclusions

Collectively, our study identified both conserved and individualized features of granulomatous uveitis, illuminating parallel pathophysiologic mechanisms, and suggesting that future personalized therapeutic approaches may be warranted.

Revising the Diagnosis of Idiopathic Uveitis by Peripheral Blood Transcriptomics

PURPOSE

To test the hypothesis that idiopathic uveitis can be categorized into subtypes based on gene expression from blood.

DESIGN

Case control study.

METHODS

We applied RNA-Seq to peripheral blood from patients with uveitis associated with 1 of 4 systemic diseases, including axial spondyloarthritis (n = 17), sarcoidosis (n = 13), inflammatory bowel disease (n = 12), tubulo-interstitial nephritis with uveitis (n = 10), or idiopathic uveitis (n = 38) as well as 18 healthy control subjects evaluated predominantly at Oregon Health and Science University. A high-dimensional negative binomial regression model implemented in the edgeR R package compared each disease group with the control subjects. The 20 most distinctive genes for each diagnosis were extracted. Of 80 genes, there were 75 unique genes. A classification algorithm was developed by fitting a gradient boosting tree with 5-fold cross-validation. Messenger RNA from subjects with idiopathic uveitis were analyzed to see if any fit clinically and by gene expression pattern with one of the diagnosable entities.

RESULTS

For uveitis associated with a diagnosable systemic disease, gene expression profiling achieved an overall accuracy of 85% (balanced average of sensitivity plus specificity, P < .001). Although most patients with idiopathic uveitis presumably have none of these 4 associated systemic diseases, gene expression profiles helped to reclassify 11 of 38 subjects.

CONCLUSIONS

Peripheral blood gene expression profiling is a potential adjunct in accurate differential diagnosis of the cause of uveitis. Validation of these results and characterization of the gene expression profile from additional discrete diagnoses could enhance the value of these observations.

Herpetic Panophthalmitis: A Diagnostic Dilemma

Purpose: To describe an uncommon presentation of ocular infection caused by human herpes simplex virus 2 (HSV-2).Methods: Case report.Results: A 32-year-old female with no prior history of mucocutaneous herpesvirus infection presented with a minimally painful hypertensive granulomatous panophthalmitis and optic neuropathy that was initially suspected to be orbital cellulitis. Her disease progressed despite antibiotic and steroid treatment, and HSV-2 was ultimately identified in the vitreous.Conclusion: Although rare, ocular infection by human herpesvirus can present as a panophthalmitis. The case is discussed in the context of two previously reported cases of herpes simplex panophthalmitis, as well panophthalmitis caused by varicella zoster virus.

Immunologic factors may play a role in herpes simplex virus 1 reactivation in the brain and retina after influenza vaccination

Herpes simplex virus 1 (HSV-1) is a nearly ubiquitous human pathogen, remaining dormant in its human host the majority of the time. The interaction between HSV-1 and the immune system represents a complicated balance of power that allows the virus to persist in the host for a lifetime. However, disruptions in the immune system can activate the virus with the potential to cause devastating infections in the central nervous system (CNS). We present a patient who suffered three consecutive yearly HSV-1 CNS episodes (encephalitis, seizure, and retinitis), each within days of his influenza vaccination. We highlight subtle immunologic defects in this patient that may have allowed unchecked viral replication and resultant disease manifestations, as well as the potential role of influenza vaccine in tipping this balance in favor of HSV-1.

Tracking expression and subcellular localization of RNA and protein species using high-throughput single cell imaging flow cytometry

We report a high-throughput application of multispectral imaging flow cytometry (MIFC) for analyzing the expression and localization of both RNA and protein molecules in a heterogeneous population of cells. The approach was developed using polyadenylated nuclear (PAN) RNA, an abundant, noncoding RNA expressed by Kaposi's sarcoma-associated herpesvirus (KSHV) during the lytic phase of infection. High levels of PAN RNA are, in part, dependent on its interaction with poly(A)-binding protein C1 (PABPC1), which relocalizes from the cytoplasm to the nucleus of lytically infected cells. We quantitatively tracked the cytoplasmic to nuclear translocation of PABPC1 and examined how this translocation relates to the expression and localization of viral RNA and protein molecules in KSHV-infected cells. This high-throughput approach will be useful for other systems in which changes in subcellular localization of RNA and protein molecules need to be monitored simultaneously.

KSHV infects a subset of human tonsillar B cells, driving proliferation and plasmablast differentiation

Kaposi sarcoma-associated herpesvirus (KSHV; also known as HHV8) is the causative agent of two B cell tumors, multicentric Castleman disease (MCD) and primary effusion lymphoma (PEL). However, little is known about the nature of the specific B cell subtype(s) most susceptible to infection. Identifying these cells would provide direct insight into KSHV transmission and virus-induced transformation. To identify this subset and to determine whether infection alters its cellular phenotype, we exposed human tonsillar cells to KSHV and characterized infected cells using high-throughput multispectral imaging flow cytometry (MIFC). Stable expression of the virally encoded latency-associated nuclear antigen (LANA), a marker of latent KSHV infection, was observed predominantly in cells expressing the l light chain of the B cell receptor. These LANA+ B cells proliferated and exhibited similarities to the cells characteristic of MCD (IgMl-expressing plasmablasts), including blasting morphology with elevated expression of Ki67, variable expression of CD27, and high levels of IgM and IL-6 receptor. Furthermore, the proportion of infected cells showing a blasting phenotype increased upon addition of exogenous IL-6. Our data lead us to propose that oral transmission of KSHV involves the latent infection of a subset of tonsillar IgMl-expressing B cells, which then proliferate as they acquire the plasmablast phenotype characteristic of MCD.

A central regulatory role for eosinophils and the eotaxin/CCR3 axis in chronic experimental allergic airway inflammation

To clarify the role and regulation of eosinophils, we subjected several key eosinophil-related genetically engineered mice to a chronic model of allergic airway inflammation aiming to identify results that were independent of the genetic targeting strategy. In particular, mice with defects in eosinophil development (Deltadbl-GATA) and eosinophil recruitment [mice deficient in CCR3 (CCR3 knockout) and mice deficient in both eotaxin-1 and eotaxin-2 (eotaxin-1/2 double knockout)] were subjected to Aspergillus fumigatus-induced allergic airway inflammation. Allergen-induced eosinophil recruitment into the airway was abolished by 98%, 94%, and 99% in eotaxin-1/2 double knockout, CCR3 knockout, and Deltadbl-GATA mice, respectively. Importantly, allergen-induced type II T helper lymphocyte cytokine production was impaired in the lungs of eosinophil- and CCR3-deficient mice. The absence of eosinophils correlated with reduction in allergen-induced mucus production. Notably, by using global transcript expression profile analysis, a large subset (29%) of allergen-induced genes was eosinophil- and CCR3-dependent; pathways downstream from eosinophils were identified, including in situ activation of coagulation in the lung. In summary, we present multiple lines of independent evidence that eosinophils via CCR3 have a central role in chronic allergic airway disease.

Persistent effects induced by IL-13 in the lung

IL-13 overexpression in the lung induces inflammatory and remodeling responses that are prominent features of asthma. Whereas most studies have concentrated on the development of IL-13-induced disease, far fewer studies have focused on the reversibility of IL-13-induced pathologies. This is particularly important because current asthma therapy appears to be poor at reversing lung remodeling. In this manuscript, we used an externally regulatable transgenic system that targets expression of IL-13 to the lung with the aim of characterizing the reversibility process. After 4 wk of doxycycline (dox) exposure, IL-13 expression resulted in mixed inflammatory cell infiltration, mucus cell metaplasia, lung fibrosis, and airspace enlargement (emphysema). After withdrawal of dox, IL-13 protein levels were profoundly reduced by 7 d and below baseline by 14 d. During this time frame, the level of lung eosinophils returned to near normal, whereas macrophages, lymphocytes, and neutrophils remained markedly elevated. IL-13-induced mucus cell metaplasia significantly decreased (91%) 3 wk after withdrawal of dox, showing strong correlation with reduced eosinophil levels. In contrast, IL-13-induced lung fibrosis did not significantly decline 4 wk after dox withdrawal. Importantly, IL-13-induced emphysema persisted, but modestly declined 4 wk after dox. Examination of transcript expression profiles identified a subset of genes that remained increased weeks after transgene expression was no longer detected. Notably, numerous IL-13-induced cytokines and enzymes were reversible (IL-6 and cathepsins), whereas others were sustained (CCL6 and chitinases) after IL-13 withdrawal, respectively. Thus, several hallmark features of IL-13-induced lung pathology persist and are dissociated from eosinophilia after IL-13 overexpression ceases.

Pulmonary chemokine expression is coordinately regulated by STAT1, STAT6, and IFN-gamma

The expression of distinct chemokines within the asthmatic lung suggests that specific regulatory mechanisms may mediate various stages of asthmatic disease. Global transcript expression profiling was used to define the spectrum and kinetics of chemokine involvement in an experimental murine model of asthma. Seventeen chemokines were induced in the lungs of allergen-inoculated mice, as compared with saline-treated mice. Two (CXCL13 and CCL9) of the 17 identified chemokines have not previously been associated with allergic airway disease. Seven (7 of 17; CCL2, CCL7, CCL9, CCL11, CXCL1, CXCL5, CXCL10) of the allergen-induced chemokines were induced early after allergen challenge and remained induced throughout the experimental period. Three chemokines (CXCL2, CCL3, and CCL17) were induced only during the early phase of the inflammatory response after the initial allergen challenge, while seven chemokines (CCL6, CCL8, CCL12, CCL22, CXCL9, CXCL12, and CXCL13) were increased only after a second allergen exposure. Unexpectedly, expression of only three chemokines, CCL11, CCL17, and CCL22, was STAT6 dependent, and many of the identified chemokines were overexpressed in STAT6-deficient mice, providing an explanation for the enhanced neutrophilic inflammation seen in these mice. Notably, IFN-gamma and STAT1 were shown to contribute to the induction of two STAT6-independent chemokines, CXCL9 and CXCL10. Taken together, these results show that only a select panel of chemokines (those targeting Th2 cells and eosinophils) is positively regulated by STAT6; instead, many of the allergen-induced chemokines are negatively regulated by STAT6. Collectively, we demonstrate that allergen-induced inflammation involves coordinate regulation by STAT1, STAT6, and IFN-gamma.