Molecular diagnosis of orbital inflammatory disease

Metagenomic Deep Sequencing for Orbital Inflammatory Disease

PURPOSE

Orbital inflammatory disease (OID) is a heterogeneous group of immunologic disorders whose etiology is often non-specific despite routine investigation. In this proof-of-concept study, metagenomic deep sequencing (MDS) is applied to examine host gene expression in two subtypes of OID.

METHODS

Prospectively collected lacrimal gland tissue from patients with OID was processed for MDS. Differential gene expression analysis was performed to evaluate for host transcriptome signatures. Proof-of-concept comparison was made between histologically confirmed samples of idiopathic dacryoadenitis and IgG4-related disease (IgG4-RD).

RESULTS

Twelve genes were identified to be differentially expressed between idiopathic dacryoadenitis and IgG4-RD. Differences in innate humoral immunity gene expression were observed. Several additional genes of interests were also found to be upregulated in idiopathic dacryoadenitis.

CONCLUSIONS

A unique transcriptome signature was found when comparing idiopathic dacryoadenitis to IgG4-RD. This suggests that MDS can identify differentially expressed genes in OID. Such insight could potentially provide a better understanding of host gene expression and the inflammatory pathways involved in OID.

Novel insights into the pathogenesis of thyroid eye disease through ferroptosis-related gene signature and immune infiltration analysis

Thyroid eye disease (TED) has brought great physical and mental trauma to patients worldwide. Although a few potential signaling pathways have been reported, knowledge of TED remains limited. Our objective is to explore the fundamental mechanism of TED and identify potential therapeutic targets using diverse approaches. To perform a range of bioinformatic analyses, such as identifying differentially expressed genes (DEGs), conducting enrichment analysis, establishing nomograms, analyzing weighted gene correlation network analysis (WGCNA), and studying immune infiltration, the datasets GSE58331, GSE105149, and GSE9340 were integrated. Further validation was conducted using qPCR, western blot, and immunohistochemistry techniques. Eleven ferroptosis-related DEGs derived from the lacrimal gland were originally screened. Their high diagnostic value was proven, and diagnostic prediction nomogram models with high accuracy and robustness were established by using machine learning. A total of 15 hub gene-related DEGs were identified by WGCNA. Through CIBERSORTx, we uncovered five immune cells highly correlated with TED and found several special associations between these immune cells and the above DEGs. Furthermore, EGR2 from the thyroid sample was revealed to be closely negatively correlated with most DEGs from the lacrimal gland. High expression of APOD, COPB2, MYH11, and MYCN, as well as CD4/CD8 T cells and B cells, was verified in the periorbital adipose tissues of TED patients. To summarize, we discovered a new gene signature associated with ferroptosis that has a critical impact on the development of TED and provides valuable insights into immune infiltration. These findings might highlight the new direction and therapeutic strategies of TED.

Ocular Sarcoidosis

Sarcoidosis frequently affects the eye and can do so in many different ways. Sarcoidosis causing uveitis can have distinctive features that facilitate identifying sarcoidosis as the cause of the uveitis. Progress is being made in elucidating ocular sarcoidosis, as for example, by transcriptomics, genetics, therapy, and imaging.

Inflammation and Fibrosis in Orbital Inflammatory Disease: A Histopathologic Analysis

PURPOSE

The purpose of this study was to compare the histopathologic inflammation and fibrosis of orbital adipose tissue in orbital inflammatory disease (OID) specimens.

METHODS

In this retrospective cohort study, inflammation, and fibrosis in orbital adipose tissue from patients with thyroid-associated orbitopathy (TAO), granulomatosis with polyangiitis (GPA), sarcoidosis, nonspecific orbital inflammation (NSOI), and healthy controls were scored by 2 masked ocular pathologists. Both categories were scored on a scale of 0 to 3 with scoring criteria based on the percentage of specimens containing inflammation or fibrosis, respectively. Tissue specimens were collected from oculoplastic surgeons at 8 international centers representing 4 countries. Seventy-four specimens were included: 25 with TAO, 6 with orbital GPA, 7 with orbital sarcoidosis, 24 with NSOI, and 12 healthy controls.

RESULTS

The mean inflammation and fibrosis scores for healthy controls were 0.0 and 1.1, respectively. Orbital inflammatory disease groups' inflammation (I) and fibrosis (F) scores, formatted [I, F] with respective p -values when compared to controls, were: TAO [0.2, 1.4] ( p = 1, 1), GPA [1.9, 2.6] ( p = 0.003, 0.009), sarcoidosis [2.4, 1.9] ( p = 0.001, 0.023), and NSOI [1.3, 1.8] ( p ≤ 0.001, 0.018). Sarcoidosis had the highest mean inflammation score. The pairwise analysis demonstrated that sarcoidosis had a significantly higher mean inflammation score than NSOI ( p = 0.036) and TAO ( p < 0.0001), but no difference when compared to GPA. GPA had the highest mean fibrosis score, with pairwise analysis demonstrating a significantly higher mean fibrosis score than TAO ( p = 0.048).

CONCLUSIONS

Mean inflammation and fibrosis scores in TAO orbital adipose tissue samples did not differ from healthy controls. In contrast, the more "intense" inflammatory diseases such as GPA, sarcoidosis, and NSOI did demonstrate higher histopathologic inflammation and fibrosis. This has implications in prognosis, therapeutic selection, and response monitoring in orbital inflammatory disease.

Orbital inflammatory pseudotumor: new advances in diagnosis, pathogenesis, and treatment

Orbital inflammatory pseudotumor (OIP) is a benign, non-specific inflammatory disorder that commonly occurs in middle-aged adults and is usually unilateral but can occur bilaterally. Its clinical manifestations have tremendous clinical heterogeneity and vary according to the site of infiltration and the degree of lesions, including orbital pain, swelling, diplopia, proptosis, restricted eye movement, and decreased visual acuity. Clinical features, Image characteristics and pathological examinations often need to be evaluated to confirm the diagnosis. Currently, there is no systematic research on the pathogenesis of OIP, which may be related to immunity or infection. The first-line treatment is glucocorticoids. Radiotherapy, immunosuppressants, and biologics can be considered for treatment-resistant, hormone-dependent, or intolerant patients. In this review, we aim to summarize and focus on new insights into OIP, including new diagnostic criteria, pathogenesis, and discoveries in new drugs and treatment strategies. In particular, we highlight the literature and find that T cell-mediated immune responses are closely related to the pathogenesis of OIP. Further exploration of the mechanism and signaling pathway of T cells in the immune process will help to identify their therapeutic targets and carry out targeted therapy to treat refractory OIP and reduce the side effects of traditional treatments.

Orbital inflammatory disease

Orbital inflammatory disease (OID), commonly known as orbital pseudotumour, is an inflammatory disease of unknown cause. It has different forms of presentation and different degrees of severity. Its variable nature is the main cause for this disease to be misdiagnosed and misclassified. The prognosis of OID depends on the tissues affected and the histology. OID usually responds favourably to systemic steroid treatment. However, empiric steroids may mask other underlying diseases that respond well to this treatment as well, namely, IgG4-related disease or lymphoproliferative disorders. This fact has led to controversy among various authors as some recommend performing a biopsy in most of the cases, whereas others defend that this procedure should only be performed if the patient has not responded to empiric steroid treatment. Although steroids have been the mainstream treatment of OID, the side effects, relapse rates and lack of response in some cases have resulted in them being replaced by immunosuppressive and immunomodulator therapies that currently stand as a key steroid-sparing treatment option, in addition to radiotherapy and surgery. The aim of this review is to update the evidence on the diagnosis and treatment of OID.

Epigenetics effect on pathogenesis of thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disease. Recent studies have found the aberrant epigenetics in TAO, including DNA methylation, non-coding RNAs, and histone modification. Many genes have an aberrant level of methylation in TAO. For example, higher levels are found in CD14, MBP, ANGLE1, LYAR and lower levels in DRD4 and BOLL. Non-coding RNAs are involved in the immune response (miR-146a, miR-155, miR-96, miR-183), fibrosis regulation (miR-146a, miR-21, miR-29), adipogenesis (miR-27) and are thought to play roles in TAO. MicroRNA is also related to the clinical activity score (miR-Let7d-5p) and may be a predictor of glucocorticoid therapy (miR-224-5p). The quantities of H4 in TAO are increased compared with euthyroid control subjects, and the role of histone modifications in Graves' disease may lead to better understanding of its role in TAO. More studies are needed to explain the role of epigenetics in TAO and provide potential therapeutic strategies.

Suspected orbital myositis associated with COVID-19

A 44-year-old male patient developed proptosis, edema, and erythema progressing to complete ptosis and supraduction deficit 2 days after positive COVID-19 test. He failed to improve on systemic antibiotics. MRI showed thickening and T2 enhancement of the superior rectus/levator complex consistent with orbital myositis. He improved on intravenous corticosteroids and experienced continued gradual improvement on oral steroids.

Enrichment of IGF-1R and PPARγ signalling pathways in orbital inflammatory diseases: steps toward understanding pathogenesis

BACKGROUND

Orbital inflammatory disease (OID) encompasses a wide range of pathology including thyroid-associated orbitopathy (TAO), granulomatosis with polyangiitis (GPA), sarcoidosis and non-specific orbital inflammation (NSOI), accounting for up to 6% of orbital diseases. Understanding the underlying pathophysiology of OID can improve diagnosis and help target therapy.

AIMS

To test the hypothesis that shared signalling pathways are activated in different forms of OID.

METHODS

In this secondary analysis, pathway analysis was performed on the previously reported differentially expressed genes from orbital adipose tissue using patients with OID and healthy controls who were characterised by microarray. For the original publications, tissue specimens were collected from oculoplastic surgeons at 10 international centres representing four countries (USA, Canada, Australia and Saudi Arabia). Diagnoses were independently confirmed by two masked ocular pathologists (DJW, HEG). Gene expression profiling analysis was performed at the Oregon Health & Science University. Eighty-three participants were included: 25 with TAO, 6 with orbital GPA, 7 with orbital sarcoidosis, 25 with NSOI and 20 healthy controls.

RESULTS

Among the 83 subjects (mean (SD) age, 52.8 (18.3) years; 70% (n=58) female), those with OID demonstrated perturbation of the downstream gene expressions of the IGF-1R (MAPK/RAS/RAF/MEK/ERK and PI3K/Akt/mTOR pathways), peroxisome proliferator-activated receptor-γ (PPARγ), adipocytokine and AMPK signalling pathways compared with healthy controls. Specifically, GPA samples differed from controls in gene expression within the insulin-like growth factor-1 receptor (IGF-1R, PI3K-Akt (p=0.001), RAS (p=0.005)), PPARγ (p=0.002), adipocytokine (p=0.004) or AMPK (p=<0.001) pathways. TAO, sarcoidosis and NSOI samples were also found to have statistically significant differential gene expression in these pathways.

CONCLUSIONS

Although OID includes a heterogenous group of pathologies, TAO, GPA, sarcoidosis and NSOI share enrichment of common gene signalling pathways, namely IGF-1R, PPARγ, adipocytokine and AMPK. Pathway analyses of gene expression suggest that other forms of orbital inflammation in addition to TAO may benefit from blockade of IGF-1R signalling pathways.

Radiologic imaging shows variable accuracy in diagnosing orbital inflammatory disease and assessing its activity

Radiologic orbital imaging provides important information in the diagnosis and management of orbital inflammation. However, the diagnostic value of orbital imaging is not well elucidated. This study aimed to investigate the diagnostic accuracy of orbital imaging to diagnose orbital inflammatory diseases and its ability to detect active inflammation. We collected 75 scans of 52 patients (49 computed tomography (CT) scans; 26 magnetic resonance (MR) imaging scans). Clinical diagnoses included thyroid eye disease (TED) (41 scans, 31 patients), non-specific orbital inflammation (NSOI) (22 scans, 14 patients), sarcoidosis (4 scans, 3 patients), IgG4-related ophthalmic disease (IgG4-ROD) (5 scans, 3 patients), and granulomatosis with polyangiitis (GPA) (3 scans, 1 patient). Two experienced neuroradiologists interpreted the scans, offered a most likely diagnosis, and assessed the activity of inflammation, blinded to clinical findings. The accuracy rate of radiological diagnosis compared to each clinical diagnosis was evaluated. Sensitivity and specificity in detecting active inflammation were analyzed for TED and NSOI. The accuracy rate of radiologic diagnosis was 80.0% for IgG4-ROD, 77.3% for NSOI, and 73.2% for TED. Orbital imaging could not diagnose sarcoidosis. Orbital CT had a sensitivity of 50.0% and a specificity of 75.0% to predict active TED using clinical assessment as the gold standard. The sensitivity/specificity of orbital MR was 83.3/16.7% for the detection of active NSOI. In conclusion, orbital imaging is accurate for the diagnosis of IgG4, NSOI, and TED. Further studies with a large number of cases are needed to confirm this finding, especially with regard to uncommon diseases. Orbital CT showed moderate sensitivity and good specificity for identifying active TED.

Non-specific orbital inflammation: Current understanding and unmet needs

Non-specific orbital inflammation (NSOI) is a noninfectious inflammatory condition of the orbit. Although it is generally considered the most common diagnosis derived from an orbital biopsy, it is a diagnosis of exclusion, meaning that the diagnosis requires exclusion of a systemic process or another identifiable etiology of orbital inflammation. The clinical diagnosis of NSOI is ill-defined, but it is typically characterized by acute orbital signs and symptoms, including pain, proptosis, periorbital edema, chemosis, diplopia, and less commonly visual disturbance. NSOI poses a diagnostic and therapeutic challenge: The clinical presentations and histological findings are heterogeneous, and there are no specific diagnostic criteria or treatment guidelines. The etiology and pathogenesis of NSOI are poorly understood. Here we recapitulate our current clinical understanding of NSOI, with an emphasis on the most recent findings on clinical characteristics, imaging findings, and treatment outcomes. Furthermore, gene expression profiling of NSOI and its implications are presented and discussed.

cDC2 and plasmacytoid dendritic cells diminish from tissues of patients with non-Hodgkin orbital lymphoma and idiopathic orbital inflammation

Non-Hodgkin orbital lymphoma (NHOL) and idiopathic orbital inflammation (IOI) are common orbital conditions with largely unknown pathophysiology. To investigate the immune cell composition of these diseases, we performed standardized 29 parameter flow cytometry phenotyping in peripheral blood mononuclear cells of 18 NHOL patients, 21 IOI patients, and 41 unaffected controls. Automatic gating by FlowSOM revealed decreased abundance of meta-clusters containing dendritic cells in patients, which we confirmed by manual gating. A decreased percentage of (HLA-DR⁺ CD303⁺ CD123⁺ ) plasmacytoid dendritic cells (pDC) in the circulation of IOI patients and decreased (HLA-DR⁺ CD11c⁺ CD1c⁺ ) conventional dendritic cells (cDC) type-2 for IOI patients were replicated in an independent cohort of patients and controls. Meta-analysis of both cohorts demonstrated that pDCs are also decreased in blood of NHOL patients and highlighted that the decrease in blood cDC type-2 was specific for IOI patients compared to NHOL or controls. Deconvolution-based estimation of immune cells in transcriptomic data of 48 orbital biopsies revealed a decrease in the abundance of pDC and cDC populations within the orbital microenvironment of IOI patients. Collectively, these data suggest a previously underappreciated role for dendritic cells in orbital disorders.

Microarray Data of Lacrimal Gland Implicates Dysregulated Protein Processing in Endoplasmic Reticulum in Graves' Ophthalmopathy

Graves' ophthalmopathy (GO) has become one of the most common orbital diseases. Although some evidences announced the potential mechanism of pathological changes in extraocular muscle and orbital adipose tissue, little is known about that in lacrimal enlargement of GO patients. Thus, gene expression profiles of lacrimal gland derived from GO patients and normal controls were investigated using the microarray datasets of GSE105149 and GSE58331. The raw data and annotation files of GSE105149 and GSE58331 were downloaded from Gene Expression Omnibus (GEO) database. Bioinformatics including differentially expressed genes (DEGs), Gene Ontology, Kyoto Encyclopedia of Gene and Genome (KEGG) pathway, protein-protein interaction (PPI) network construction, hub gene identification, and gene set variation analysis (GSVA) were successively performed. A total of 173 overlapping DEGs in GSE105149 and GSE58331 were screened out, including 20 up-regulated and 153 down-regulated genes. Gene Ontology, KEGG and GSVA analyses of these DEGs showed that the most significant mechanism was closely associated with endoplasmic reticulum (ER). Moreover, we identified 40 module genes and 13 hub genes which were also enriched in the ER-associated terms and pathways. Among the hub genes, five genes including HSP90AA1, HSP90B1, DNAJC10, HSPA5, and CANX may be involved in the dysfunction of protein processing in ER. Taken together, our observations revealed a dysregulated gene network which is essential for protein processing in ER in GO patients. These findings provided a potential mechanism in the progression of lacrimal enlargement in GO patients, as a new insight into GO pathogenesis.

Orbital Vasculitides-Differential Diagnosis

PURPOSE OF REVIEW

The orbit is subject to a variety of vascular insults that manifest with both specific and nonspecific patterns of vision compromise. The aim of the following review is to highlight the ophthalmic clinical features of systemic vasculitides that most frequently involve the orbit and differentiate them from the most common non-vasculitic orbital disorders.

RECENT FINDINGS

New studies continue to explore the autoimmune nature of vasculitic disease and seek to determine optimal use of newer therapies such as biologic agents. The pattern of ocular involvement in the context of clinical history allows the knowledgeable physician to distill a differential diagnosis into a specific or likely cause. Establishing a diagnosis in a timely fashion allows for a custom-tailored approach to therapy.

Gene Expression Profiling and Heterogeneity of Nonspecific Orbital Inflammation Affecting the Lacrimal Gland

Importance

Although a variety of well-characterized diseases, such as sarcoidosis and granulomatosis with polyangiitis, affect the lacrimal gland, many patients with dacryoadenitis are diagnosed as having nonspecific orbital inflammation (NSOI) on the basis of histology and systemic disease evaluation. The ability to further classify the disease in these patients should facilitate selection of effective therapies.

Objective

To test the a priori hypothesis that gene expression profiles would complement clinical and histopathologic evaluations in identifying well-characterized diseases and in subdividing NSOI into clinically relevant groups.

Design, Setting, and Participants

In this cohort study, gene expression levels in biopsy specimens of inflamed and control lacrimal glands were measured with microarrays. Stained sections of the same biopsy specimens were used for evaluation of histopathology. Tissue samples of patients were obtained from oculoplastic surgeons at 7 international centers representing 4 countries (United States, Saudi Arabia, Canada, and Taiwan). Gene expression analysis was done at Oregon Health & Science University. Participants were 48 patients, including 3 with granulomatosis with polyangiitis, 28 with NSOI, 7 with sarcoidosis, 4 with thyroid eye disease, and 6 healthy controls. The study dates were March 2012 to April 2017.

Main Outcomes and Measures

The primary outcome was subdivision of biopsy specimens based on gene expression of a published list of approximately 40 differentially expressed transcripts in blood, lacrimal gland, and orbital adipose tissue from patients with sarcoidosis. Stained sections were evaluated for inflammation (none, mild, moderate, or marked), granulomas, nodules, or fibrosis by 2 independent ocular pathologists masked to the clinical diagnosis.

Results

Among 48 patients (mean [SD] age, 41.6 [19.0] years; 32 [67%] female), the mclust algorithm segregated the biopsy specimens into 4 subsets, with the differences illustrated by a heat map and multidimensional scaling plots. Most of the sarcoidosis biopsy specimens were in subset 1, which had the highest granuloma score. Three NSOI biopsy specimens in subset 1 had no apparent granulomas. Thirty-two percent (9 of 28) of the NSOI biopsy specimens could not be distinguished from biopsy specimens of healthy controls in subset 4, while other examples of NSOI tended to group with gene expression resembling granulomatosis with polyangiitis or thyroid eye disease. The 4 subsets could also be partially differentiated by their fibrosis, granulomas, and inflammation pathology scores but not their lymphoid nodule scores.

Conclusions and Relevance

Gene expression profiling discloses clear heterogeneity among patients with lacrimal inflammatory disease. Comparison of the expression profiles suggests that a subset of patients with nonspecific dacryoadenitis might have a limited form of sarcoidosis, while other patients with NSOI cannot be distinguished from healthy controls.

Systemic vasculitis and the eye

PURPOSE OF REVIEW

The primary systemic vasculitides represent a spectrum of rare but life-threatening conditions that may also affect the eye in various forms. This article reviews recently published data on ocular manifestations of systemic vasculitis.

RECENT FINDINGS

Early diagnosis and timely treatment has led to better visual outcomes in giant cell arteritis (GCA). Gene expression from orbital tissues could distinguish granulomatosis with polyangiitis (GPA) from sarcoidosis and Graves disease, but not from idiopathic orbital inflammation. Rituximab was an effective therapeutic option in ocular GPA. An ocular attack severity scoring system, flare levels, fluorescein angiography and optical coherence tomography parameters have been suggested as predictors of visual prognosis in Behçet disease. Efficacy of tumor necrosis factor-alpha inhibitors, interferon α and anti-interleukin-1 agents was shown in noncontrolled studies of ocular Behçet disease.

SUMMARY

Widely used fast-track pathway care as well as ocular imaging to detect subclinical involvement may enable earlier diagnosis of GCA and prevention of permanent visual loss. Orbital inflammation may not remain idiopathic with advances in gene expression profiling of orbital tissues. With an increased availability and the use of biologic agents, visual prognosis will improve in patients with severe ocular complications of systemic vasculitides.

Bilateral dacryoadenitis as initial presentation of a locally aggressive and unresponsive limited form of orbital granulomatosis with polyangiitis

Limited orbital granulomatosis with polyangiitis (GPA) is uncommon and its diagnosis may be delayed, especially when isolated lacrimal involvement is the initial presentation, because clinical manifestations are non-specific and systemic diagnostic criteria are not applicable. Making an early diagnosis despite the absence of systemic progression is extremely important because in some cases the disease is locally destructive, with irreversible visual and functional loss, and it can be refractory to corticosteroids and conventional immunosuppressive drugs to induce remission. The authors report an unusual limited form of orbital GPA in a 35-year-old woman presenting with bilateral dacryoadenitis, evolving later to locally aggressive bilateral orbital pseudotumour leading to proptosis, extraocular myositis, diplopia and medial deviation of the nasal septum. She had never had systemic manifestations but her disease was persistently active and unresponsive to corticosteroids and immunosuppressors. The aim of this paper is to provide further evidence of aggressive and refractory limited forms of GPA.

Diagnosing sarcoidosis

PURPOSE OF REVIEW

The usual diagnostic criteria for sarcoidosis include the documentation of a compatible clinicoradiologic scenario, biopsy proof of granulomas, and exclusion of alternate causes for the findings. Establishing the presence of multisystem disease, and longitudinal assessment for the emergence of potential sarcoidosis mimics both strengthen the diagnosis. These principles have constituted a 'diagnostic modus operandi' for several decades, but the emergence of several new technologies has begun to transform their application.

RECENT FINDINGS

The widespread availability of high-resolution chest computed tomography, endobronchial ultrasound-guided transbronchial needle aspiration, rapid on-site cytopathology and to a lesser degree, fluorodeoxyglucose positron emission tomography have facilitated more convenient diagnosis. They also have identified possibilities for biopsy-less diagnosis in appropriate clinical contexts, similar to idiopathic pulmonary fibrosis, and allowed for more comprehensive assessment of the extent and activity of disease. Nonetheless, these new technologies cannot replace the central role of the clinician, whose judgment and circumspection are keys to accurate diagnosis.

SUMMARY

The diagnosis of sarcoidosis and the assessment of its extent should be tailored to the clinical situation. The application of new technologies may permit some evolution of the diagnostic approach in many patients.

Molecular diagnosis: Implications for ophthalmology

The effort to subdivide diseases and to individualize therapies based on characteristics of the patient has been labeled precision medicine. Jameson and Longo define precision medicine as "treatments targeted to the needs of individual patients on the basis of genetic, biomarker, phenotypic or psychosocial characteristics that distinguish a given patient from other patients with similar clinical presentations" (Jameson and Longo, 2015). We illustrate how molecular diagnosis can be applied to orbital inflammatory disease to achieve the goals of precision medicine.

Orbital pseudotumor can be a localized form of granulomatosis with polyangiitis as revealed by gene expression profiling

Biopsies and ANCA testing for limited forms of granulomatosis with polyangiitis (GPA) are frequently non-diagnostic. We characterized gene expression in GPA and other causes of orbital inflammation. We tested the hypothesis that a sub-set of patients with non-specific orbital inflammation (NSOI, also known as pseudotumor) mimics a limited form of GPA. Formalin-fixed, paraffin-embedded orbital biopsies were obtained from controls (n=20) and patients with GPA (n=6), NSOI (n=25), sarcoidosis (n=7), or thyroid eye disease (TED) (n=20) and were divided into discovery and validation sets. Transcripts in the tissues were quantified using Affymetrix U133 Plus 2.0 microarrays. Distinct gene expression profiles for controls and subjects with GPA, TED, or sarcoidosis were evident by principal coordinate analyses. Compared with healthy controls, 285 probe sets had elevated signals in subjects with GPA and 1472 were decreased (>1.5-fold difference, false discovery rate adjusted p<0.05). The immunoglobulin family of genes had the most dramatic increase in expression. Although gene expression in GPA could be readily distinguished from gene expression in TED, sarcoidosis, or controls, a comparison of gene expression in GPA versus NSOI found no statistically significant differences. Thus, forms of orbital inflammation can be distinguished based on gene expression. NSOI/pseudotumor is heterogeneous but often may be an unrecognized, localized form of GPA.

The Role of the Immune Response in the Pathogenesis of Thyroid Eye Disease: A Reassessment

Background

Although thyroid eye disease is a common complication of Graves’ disease, the pathogenesis of the orbital disease is poorly understood. Most authorities implicate the immune response as an important causal factor. We sought to clarify pathogenesis by using gene expression microarray.

Methods

An international consortium of ocular pathologists and orbital surgeons contributed formalin fixed orbital biopsies. RNA was extracted from orbital tissue from 20 healthy controls, 25 patients with thyroid eye disease (TED), 25 patients with nonspecific orbital inflammation (NSOI), 7 patients with sarcoidosis and 6 patients with granulomatosis with polyangiitis (GPA). Tissue was divided into a discovery set and a validation set. Gene expression was quantified using Affymetrix U133 Plus 2.0 microarrays which include 54,000 probe sets.

Results

Principal component analysis showed that gene expression from tissue from patients with TED more closely resembled gene expression from healthy control tissue in comparison to gene expression characteristic of sarcoidosis, NSOI, or granulomatosis with polyangiitis. Unsupervised cluster dendrograms further indicated the similarity between TED and healthy controls. Heat maps based on gene expression for cytokines, chemokines, or their receptors showed that these inflammatory markers were associated with NSOI, sarcoidosis, or GPA much more frequently than with TED.

Conclusion

This is the first study to compare gene expression in TED to gene expression associated with other causes of exophthalmos. The juxtaposition shows that inflammatory markers are far less characteristic of TED relative to other orbital inflammatory diseases.