Role of macrophage infiltration in the orbital fat of patients with Graves' ophthalmopathy

Redox mechanisms in autoimmune thyroid eye disease

Thyroid eye disease (TED) is an autoimmune condition affecting the orbit and the eye with its adnexa, often occurring as an extrathyroidal complication of Graves' disease (GD). Orbital inflammatory infiltration and the stimulation of orbital fibroblasts, triggering de novo adipogenesis, an overproduction of hyaluronan, myofibroblast differentiation, and eventual tissue fibrosis are hallmarks of the disease. Notably, several redox signaling pathways have been shown to intensify inflammation and to promote adipogenesis, myofibroblast differentiation, and fibrogenesis by upregulating potent cytokines, such as interleukin (IL)-1β, IL-6, and transforming growth factor (TGF)-β. While existing treatment options can manage symptoms and potentially halt disease progression, they come with drawbacks such as relapses, side effects, and chronic adverse effects on the optic nerve. Currently, several studies shed light on the pathogenetic contributions of emerging factors within immunological cascades and chronic oxidative stress. This review article provides an overview on the latest advancements in understanding the pathophysiology of TED, with a special focus of the interplay between oxidative stress, immunological mechanisms and environmental factors. Furthermore, cutting-edge therapeutic approaches targeting redox mechanisms will be presented and discussed.

CD169+ classical monocyte as an important participant in Graves' ophthalmopathy through CXCL12-CXCR4 axis

Patients with Graves' disease (GD) can develop Graves' ophthalmopathy (GO), but the underlying pathological mechanisms driving this development remain unclear. In our study, which included patients with GD and GO, we utilized single-cell RNA sequencing (scRNA-seq) and multiplatform analyses to investigate CD169+ classical monocytes, which secrete proinflammatory cytokines and are expanded through activated interferon signaling. We found that CD169+ clas_mono was clinically significant in predicting GO progression and prognosis, and differentiated into CD169+ macrophages that promote inflammation, adipogenesis, and fibrosis. Our murine model of early-stage GO showed that CD169+ classical monocytes accumulated in orbital tissue via the Cxcl12-Cxcr4 axis. Further studies are needed to investigate whether targeting circulating monocytes and the Cxcl12-Cxcr4 axis could alleviate GO progression.

Identification of immune-related regulatory networks and diagnostic biomarkers in thyroid eye disease

BACKGROUND

Thyroid eye disease (TED) is an orbit-associated autoimmune inflammatory disorder intricately linked to immune dysregulation. Complete pathogenesis of TED remains elusive. This work aimed to mine pathogenesis of TED from immunological perspective and identify diagnostic genes.

METHODS

Gene expression microarray data for TED patients were downloaded from Gene Expression Omnibus, immune-related genes (IRGs) were from ImmPort database, and TED-related transcription factors (TFs) were from Cirtrome Cancer database. Differential analysis, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed. Regulatory networks of TFs and IRGs were constructed with Cytoscape. Diagnostic biomarkers in TED were identified through LASSO. Immune cell infiltration analysis was performed using CIBERSORT.

RESULTS

Twenty-three immune-related DEmRNAs were revealed and were primarily enriched in humoral immune response, positive regulation of inflammatory response, IL-17, and TNF pathways. Co-expression regulatory network included four TFs and 16 immune-related DEmRNAs. Seven diagnostic genes were identified, with Area Under the Curve (AUC) of 0.993 for training set and AUC value of 0.836 for validation set. TED patients exhibited elevated infiltration levels by macrophages M2, mast cells, and CD8 T cells among 22 immune cell types, whereas macrophages M2 and mast cells resting were significantly lower than normal group.

CONCLUSIONS

The seven feature genes had high diagnostic value for TED patients. Our work explored regulatory network and diagnostic biomarkers, laying theoretical basis for TED diagnosis and treatment.

Phospholipase C-γ as a Potential Therapeutic Target for Graves' Orbitopathy

BACKGRUOUND

Phospholipase C-γ (PLC-γ) plays a crucial role in immune responses and is related to the pathogenesis of various inflammatory disorders. In this study, we investigated the role of PLC-γ and the therapeutic effect of the PLC-specific inhibitor U73122 using orbital fibroblasts from patients with Graves' orbitopathy (GO).

METHODS

The expression of phospholipase C gamma 1 (PLCG1) and phospholipase C gamma 2 (PLCG2) was evaluated using polymerase chain reaction in GO and normal orbital tissues/fibroblasts. The primary cultures of orbital fibroblasts were treated with non-toxic concentrations of U73122 with or without interleukin (IL)-1β to determine its therapeutic efficacy. The proinflammatory cytokine levels and activation of downstream signaling molecules were determined using Western blotting.

RESULTS

PLCG1 and PLCG2 mRNA expression was significantly higher in GO orbital tissues than in controls (P<0.05). PLCG1 and PLCG2 mRNA expression was significantly increased (P<0.05) in IL-1β, tumor necrosis factor-α, and a cluster of differentiation 40 ligand-stimulated GO fibroblasts. U73122 significantly inhibited the IL-1β-induced expression of proinflammatory molecules, including IL-6, IL-8, monocyte chemoattractant protein-1, cyclooxygenase-2, and intercellular adhesion molecule-1 (ICAM-1), and phosphorylated protein kinase B (p-Akt) and p38 (p-p38) kinase in GO fibroblasts, whereas it inhibited IL-6, IL-8, and ICAM-1, and p-Akt and c-Jun N-terminal kinase (p-JNK) in normal fibroblasts (P<0.05).

CONCLUSION

PLC-γ-inhibiting U73122 suppressed the production of proinflammatory cytokines and the phosphorylation of Akt and p38 kinase in GO fibroblasts. This study indicates the implications of PLC-γ in GO pathogenesis and its potential as a therapeutic target for GO.

Orbital lymphocyte populations in three states of thyroid eye disease

Purpose

We report histopathologic orbital tissue analysis from three patients with thyroid eye disease (TED) - active, chronic, and post-teprotumumab to better characterize orbital cellular populations in these varying states of TED.

Observations

Orbital tissues in TED demonstrate minimal lymphocytic infiltration in fat and Mueller's muscle. Following teprotumumab treatment, the tissues were devoid of lymphocytes with only perivascular cuffs of T-lymphocytes remaining in orbital fat.

Conclusions and importance

In active TED, post-teprotumumab treatment, and in quiescent TED, orbital fat may not show significant inflammatory infiltration. More work is warranted to characterize specific cellular effects of teprotumumab and other biologics.

M1-Like Macrophages Modulate Fibrosis and Inflammation of Orbital Fibroblasts in Graves' Orbitopathy: Potential Relevance to Soluble Interleukin-6 Receptor

Background: Graves' orbitopathy (GO) is a disfiguring and sight-threatening autoimmune disease. Previous studies have shown the infiltration of macrophages in GO orbital connective tissues. However, the immunophenotypes of macrophages and their modulatory effects on orbital fibroblasts (OFs) have not been examined so far. In this study, we sought to determine the pathophysiology of macrophages in GO. Methods: In this case-control study, orbital connective tissues collected from 40 GO patients and 20 healthy controls were immunohistochemically stained for cytokines and macrophage cell surface antigens. The polarization of orbital-infiltrating macrophages was investigated by flow cytometry and immunofluorescence. Effects of interleukin (IL)-6 combined with soluble IL-6 receptor (sIL-6R) on the proliferation, differentiation, and inflammation of different OF subsets were examined by CCK-8, Western blotting, and Luminex assays, respectively. The antigen-presenting abilities of different OF subsets under IL-6/sIL-6R signaling were studied by proteomics. Finally, the differentiation of CD8⁺ IL-17A-producing T cells by sIL-6R was tested. Results: GO orbital connective tissues displayed increased IL-6, sIL-6R, STAT3, and IL-17A levels. CD86⁺ M1-like macrophages were predominant in active GO patients, while stable GO patients tended to have more CD163⁺ M2-like macrophages. The expression of IL-6 was higher in M1-like macrophages, and the expression of transforming growth factor-β was higher in M2-like macrophages both in GO orbital connective tissues in situ in vivo and in cell culture system in vitro. The IL-6/sIL-6R stimulation promoted the fibrosis of both CD34⁺ and CD34^- OFs. Monocyte chemoattractant protein-1 expression was also induced by IL-6/sIL-6R stimulation in both OF subsets. IL-6/sIL-6R stimulation enhanced the antigen processing of CD34⁺ OFs through upregulating the intact major histocompatibility complex I and antigen transporters. However, the protein expressions of the thyrotropin receptor and insulin-like growth factor 1 receptor could not be directly increased by IL-6/sIL-6R stimulation in CD34⁺ OFs. Furthermore, sIL-6R was conducive to the differentiation of CD8⁺ IL-17A-producing T cells. Conclusions: Our study demonstrated the immunophenotypes of orbital-infiltrating macrophages that may activate OFs depending on the IL-6/sIL-6R signaling in GO. Our preclinical findings implicate, at least in part, the molecular rationale for blocking sIL-6R as a promising therapeutic agent for GO.

TSG6 Plays a Role in Improving Orbital Inflammatory Infiltration and Extracellular Matrix Accumulation in TAO Model Mice

Introduction

TSG-6 plays a wide anti-inflammatory and therapeutic role in a variety of autoimmune diseases as the key mediator of mesenchymal stem cells (MSCs).

Purpose

We aimed to test whether TSG-6 could exert similar effects as MSCS in TAO via establishing TAO animal model immunized by hTSHR-A subunit plasmid.

Material and Methods

We tested the expression level of TSG-6 on intraconal orbital fat from controls and patients with TAO. We established a stable thyroid-associated ophthalmopathy animal model by immunizing 6-week-old female Balb/c mice with recombination hTSHR-A subunit plasmid. After four immunizations, TSG-6 or dexamethasone was injected through the tail vein. The effects of the drugs on body weight, thyroid function, orbital inflammation, fibrosis and lipogenesis were observed.

Results

The expression of TSG-6 in the orbital tissues of TAO patient is lower than that of normal people. In our animal model, mice showed weight loss, higher TT4 and TSHR antibody levels, and ocular symptoms such as inflammation and proptosis. TSG-6 can reduce ocular fibrosis and lipogenesis by inhibiting the infiltration of CD3+ T lymphocytes and macrophages in the mouse model of thyroid associated ophthalmopathy. Compared with dexamethasone, TSG-6 showed comparable anti-inflammatory effect, moreover, it has given a better performance in inhibiting adipogenesis.

Conclusion

It was demonstrated that TSG-6 has a considerable positive impact on improving eye symptoms of TAO mice, which could be a novel candidate for the early treatment of TAO.

Macrophage-Orbital Fibroblast Interaction and Hypoxia Promote Inflammation and Adipogenesis in Graves' Orbitopathy

The inflammatory eye disease Graves' orbitopathy (GO) is the main complication of autoimmune Graves' disease. In previous studies we have shown that hypoxia plays an important role for progression of GO. Hypoxia can maintain inflammation by attracting inflammatory cells such as macrophages (MQ). Herein, we investigated the interaction of MQ and orbital fibroblasts (OF) in context of inflammation and hypoxia. We detected elevated levels of the hypoxia marker HIF-1α, the MQ marker CD68, and inflammatory cytokines TNFα, CCL2, CCL5, and CCL20 in GO biopsies. Hypoxia stimulated GO tissues to release TNFα, CCL2, and CCL20 as measured by multiplex enzyme-linked immunosorbent assay (ELISA). Further, TNFα and hypoxia stimulated the expression of HIF-1α, CCL2, CCL5, and CCL20 in OF derived from GO tissues. Immunofluorescence confirmed that TNFα-positive MQ were present in the GO tissues. Thus, interaction of M1-MQ with OF under hypoxia also induced HIF-1α, CCL2, and CCL20 in OF. Inflammatory inhibitors etanercept or dexamethasone prevented the induction of HIF-1α and release of CCL2 and CCL20. Moreover, co-culture of M1-MQ/OF under hypoxia enhanced adipogenic differentiation and adiponectin secretion. Dexamethasone and HIF-1α inhibitor PX-478 reduced this effect. Our findings indicate that GO fat tissues are characterized by an inflammatory and hypoxic milieu where TNFα-positive MQ are present. Hypoxia and interaction of M1-MQ with OF led to enhanced secretion of chemokines, elevated hypoxic signaling, and adipogenesis. In consequence, M1-MQ/OF interaction results in constant inflammation and tissue remodeling. A combination of anti-inflammatory treatment and HIF-1α reduction could be an effective treatment option.

A Multicenter, Single-Blind, Case-Control, Immunohistochemical Study of Orbital Tissue in Thyroid Eye Disease

Background: Thyroid eye disease (TED) involves several pathogenic pathways and a battery of infiltrating mononuclear cells, cytokines, and chemokines in the orbit. Revealing the main molecules, which play a major role in the pathogenesis of TED, will help developing novel treatment strategies. Methods: In a multicenter, single-blind, case-control study, 60 tissue samples were collected during orbital decompression (44 TED patients) or non-TED related oculoplastic (16 controls) surgeries. Formalin-fixation and paraffin embedding preserved orbital tissue. Tissue sections were immunostained with 18 antibodies by the micro-polymer labeling technique. Immunostaining slides were scanned by Panoramic Desk and blindly evaluated by a user-independent viewer software. Results: Marked lymphocyte infiltration was observed in orbital tissue specimens of patients with clinically active TED (n = 22) and to a much lesser extent in inactive cases (n = 22), while it was absent in controls. Increased vascularity was noted in all samples, with orbital congestion in specimens of clinically active TED. Tissue fibrosis was present in TED samples but not in controls. Immunohistochemistry of orbital tissue clearly differentiated between TED and controls, as well as between active and inactive TED. In contrast to controls and with the exception of cluster of differentiation 20 (CD20), 17 out of 18 antibodies were highly expressed in orbital connective tissue of TED patients. Especially, thyrotropin receptor (TSH-R), insulin-like growth factor 1 receptor (IGF-1R), CD40, cluster of differentiation 40 ligand (CD40L), CD3, CD68, interleukin-17A (IL-17A), IL-23A, IL-1β, IL-4, regulated on activation, normal T cell expressed and secreted (RANTES), macrophage chemoattractant protein 1 (MCP-1), IL-16, and B cell activating factor (BAFF) were overexpressed in clinically active TED (all p < 0.001). Also, the expression of CD40L, IL-17A, IL-23A, IL-6, IL-1β, RANTES, and BAFF was very high (TED/control ratio >3), moderate (ratio >2), and low in active (p < 0.001), inactive TED and controls, respectively. The expression of TSH-R, IGF-1R, CD40, CD40L, CD3, CD68, CD20, IL-17A, IL-23A, RANTES, MCP-1, and BAFF positively and significantly correlated with both serum TSH-R stimulatory antibody concentrations and clinical activity scores while it negatively correlated with TED duration. Orbital irradiation decreased TSH-R (p < 0.001) and IGF-1R expression (p = 0.012); in contrast, neither smoking, age, nor gender did impact immunohistochemical staining. Conclusions: Adaptive and cell-mediated immunity, overexpression of TSH-R/IGF-1R and CD40/CD40L are the relevant pathomechanisms in TED. Targeting these key players in the active phase of the disease offers specific and novel treatment approaches.

Single-cell RNA sequencing depicts the local cell landscape in thyroid-associated ophthalmopathy

There is a specific reactivity and characteristic remodeling of the periocular tissue in thyroid-associated ophthalmopathy (TAO). However, local cell changes responsible for these pathological processes have not been sufficiently identified. Here, single-cell RNA sequencing is performed to characterize the transcriptional changes of cellular components in the orbital connective tissue in individuals with TAO. Our study shows that lipofibroblasts with RASD1 expression are highly involved in inflammation and adipogenesis during TAO. ACKR1⁺ endothelial cells and adipose tissue macrophages may engage in TAO pathogenesis. We find CD8⁺CD57⁺ cytotoxic T lymphocytes with the terminal differentiation phenotype to be another source of interferon-γ, a molecule actively engaging in TAO pathogenesis. Cell-cell communication analysis reveals increased activity of CXCL8/ACKR1 and TNFSF4/TNFRSF4 interactions in TAO. This study provides a comprehensive local cell landscape of TAO and may be valuable for future therapy investigation.

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A local transcriptional landscape of orbital connective tissue in TAO is developed

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RASD1-expressing lipofibroblasts are highly involved in adipogenesis and inflammation

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ACKR1⁺ endothelial cells contribute to inflammatory cell infiltration in TAO

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Adipose tissue macrophages engage in lipid metabolism and inflammatory response in TAO

An Early Wave of Macrophage Infiltration Intertwined with Antigen-Specific Proinflammatory T Cells and Browning of Adipose Tissue Characterizes the Onset of Orbital Inflammation in a Mouse Model of Graves' Orbitopathy

Background: Graves' orbitopathy (GO) is an autoimmune-driven manifestation of Graves' disease (GD) where pathogenic autoantibodies to the thyrotropin receptor (TSHR) activate orbital fibroblasts/preadipocytes in the orbital tissue to induce inflammation and extracellular matrix deposition. Since there are significant limitations to study immunological and proinflammatory mediator expression in early and during disease progression in GO patients, we used our experimental mouse model to elucidate early pathogenic processes. Methods: We have developed a robust mouse model of GD/GO induced by electroporation immunization of plasmid encoding human TSHR A-subunit, comprising multiple injections over a course of 15 weeks to fully recapitulate the orbital pathology. In this study, we investigated kinetics of GO development in the model by serial analyses of immunological and cellular parameters during course of orbital inflammation. Results: Pathogenic anti-TSHR antibodies with thyroid-stimulating properties developed early after the second immunization step with concomitant induction of hyperthyroidism. Examination of orbital tissue showed an early wave of macrophage infiltration followed subsequently by CD3⁺ T cells into the orbital tissue. Examination of antigen-specific T cell activity using recombinant human A-subunit protein showed high CD8⁺ T cell proliferation during this early phase of disease onset, whereas effector CD4⁺ T cells and CD25⁺FOXP3⁺ regulatory T cells (Tregs) were downregulated. The early phase of disease was also characterized by abundant presence of proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α). Moreover, as the disease progressed, there was significant increase in browning of orbital fat tissue, which may be dependent on the proinflammatory milieu and/or the increased thyroid hormone levels during the established hyperthyroid status. Conclusions: This work revealed early infiltration of macrophages in the orbital region and induction of pathogenic anti-TSHR antibodies during disease onset in the model. This was followed subsequently by influx of CD8⁺ T cells specific for TSHR coupled with reduction in Tregs and substantial increase in brown adipose tissue. These new insights into the development of orbital inflammation in the model have implications for testing new therapeutic regimens by targeting macrophage function during early phases of orbital inflammation in the model.

Leptin receptor is a key gene involved in the immunopathogenesis of thyroid-associated ophthalmopathy

Thyroid‐associated ophthalmopathy (TAO), the most common and severe manifestation of Graves' disease (GD), is a disfiguring and potentially blinding autoimmune disease. The high relapse rate (up to 20%) and substantial side effects of glucocorticoid treatment further decrease the life quality of TAO patients. To develop novel therapies, we amid to explore the immunopathogenesis of TAO. To identify the key immune‐related genes (IRGs) in TAO, we integrated the IRG expression profiles in thyrocytes from a GD patient set (GD vs healthy control) and a TAO patient set (TAO vs GD). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein‐protein interaction (PPI) and receiver operating characteristic (ROC) curve analyses identified the leptin receptor (LEPR) gene as the key IRG in TAO immunopathogenesis. Gene set enrichment analysis (GSEA) suggested enrichment of the antigen presentation pathway in TAO patients with higher LEPR. Increased LEPR expression was validated in TAO orbital tissues, and weighted gene co‐expression network analysis (WGCNA) showed that cell adhesion processes were positively correlated with LEPR. Our study revealed that LEPR is a key gene in TAO immunopathogenesis and plays different roles in thyrocytes and orbital tissues. Our findings provide new insights into diagnostic and therapeutic biomarkers for TAO.

Tear-Derived Exosome Proteins Are Increased in Patients with Thyroid Eye Disease

Exosomes contain proteins, lipids, RNA, and DNA that mediate intercellular signaling. Exosomes can contribute to the pathological processes of various diseases, although their roles in ocular diseases are unclear. We aimed to isolate exosomes from tear fluids (TF) of patients with Thyroid eye disease (TED) and analyze the exosomal proteins. TFs were collected from eight patients with TED and eight control subjects. The number of TF exosomes were measured using nanoparticle-tracking analysis. The expression of specific proteins in the purified exosome pellets were analyzed using a Proteome Profiler Array Kit. Cultured normal orbital fibroblasts were incubated with TF exosomes from patients with TED and control subjects, and changes in inflammatory cytokine levels were compared. TF exosomes from TED patients showed more exosomes than the control subjects. The expression levels of exosomal proteins vitamin D-binding (VDB) protein, C-reactive protein (CRP), chitinase 3-like 1 (CHI3L1), matrix metalloproteinase-9 (MMP-9), and vascular adhesion molecule-1 (VCAM-1) were significantly increased in patients with TED, compared to those of controls. Orbital fibroblasts exposed to TF exosomes from patients with TED showed significantly higher levels of interleukin (IL)-6, IL-8, and monocyte chemoattractant protein-1 (MCP-1) production than those treated with control TF exosomes. Specific proteins showed higher expression in exosomes from TED patients, implying that they may play keys roles in TED pathogenesis.

Retinoic Acid Potentiates Orbital Tissues for Inflammation Through NF-κB and MCP-1

Purpose

The orbit displays unique vulnerability to inflammatory conditions. The most prevalent of these conditions, thyroid eye disease (TED), occurs in up to 50% of patients with Graves’ disease (GD). Whereas the pathology of both TED and GD is driven by autoantibodies, it is unclear why symptoms manifest specifically in the orbit.

Methods

We performed retinoic acid treatment on both normal and TED patient–derived orbital fibroblasts (OFs) followed by mRNA and protein isolation, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay, RNA sequencing, and Western blot analyses.

Results

Both normal and TED patient–derived OFs display robust induction of monocyte chemoattractant protein 1 (MCP-1) upon retinoid treatment; TED OFs secrete significantly more MCP-1 than normal OFs. In addition, pretreatment of OFs with thiophenecarboxamide (TPCA-1) inhibits retinoid-induced MCP-1 induction, suggesting an NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells)–dependent mechanism. We also found that treatment with cholecalciferol (vitamin D₃) mitigates MCP-1 induction, likely because of competition between retinoic acid receptors (RARs) and vitamin D receptors (VDR) for their common binding partner retinoid nuclear receptors (RXRs).

Conclusions

Retinoids that naturally accumulate in orbital adipose tissue can act on orbital fibroblasts to induce the expression of inflammation-associated genes. These data suggest a potential role for retinoids in sensitizing the orbit to inflammation.

Cytokines as Targets of Novel Therapies for Graves' Ophthalmopathy

Graves' disease (GD) is an organ-specific autoimmune disorder of the thyroid, which is characterized by circulating TSH-receptor (TSH-R) stimulating antibodies (TSAb), leading to hyperthyroidism. Graves' ophthalmopathy (GO) is one of GD extra-thyroidal manifestations associated with the presence of TSAb, and insulin-like growth factor-1 receptor (IGF-1R) autoantibodies, that interact with orbital fibroblasts. Cytokines are elevated in autoimmune (i.e., IL-18, IL-6) and non-autoimmune hyperthyroidism (i.e., TNF-α, IL-8, IL-6), and this could be associated with the chronic effects of thyroid hormone increase. A prevalent Th1-immune response (not related to the hyperthyroidism per se, but to the autoimmune process) is reported in the immune-pathogenesis of GD and GO; Th1-chemokines (CXCL9, CXCL10, CXCL11) and the (C-X-C)R3 receptor are crucial in this process. In patients with active GO, corticosteroids, or intravenous immunoglobulins, decrease inflammation and orbital congestion, and are considered first-line therapies. The more deepened understanding of GO pathophysiology has led to different immune-modulant treatments. Cytokines, TSH-R, and IGF-1R (on the surface of B and T lymphocytes, and fibroblasts), and chemokines implicated in the autoimmune process, are possible targets of novel therapies. Drugs that target cytokines (etanercept, tocilizumab, infliximab, adalimumab) have been tested in GO, with encouraging results. The chimeric monoclonal antibody directed against CD20, RTX, reduces B lymphocytes, cytokines and the released autoantibodies. A multicenter, randomized, placebo-controlled, double-masked trial has investigated the human monoclonal blocking antibody directed against IGF-1R, teprotumumab, reporting its effectiveness in GO. In conclusion, large, controlled and randomized studies are needed to evaluate new possible targeted therapies for GO.

Mechanisms That Underly T Cell Immunity in Graves' Orbitopathy

Graves' orbitopathy (GO), also known as thyroid-associated ophthalmopathy, is the most common ocular abnormality of Graves' disease. It is a disfiguring, invalidating, and potentially blinding orbital disease mediated by an interlocking and complicated immune network. Self-reactive T cells directly against thyroid-stimulating hormone receptor-bearing orbital fibroblasts contribute to autoimmune inflammation and tissue remodeling in GO orbital connective tissues. To date, T helper (Th) 1 (cytotoxic leaning) and Th2 (antibody leaning) cell subsets and an emerging role of Th17 (fibrotic leaning) cells have been implicated in GO pathogenesis. The potential feedback loops between orbital native residential CD34^- fibroblasts, CD34⁺ infiltrating fibrocytes, and effector T cells may affect the T cell subset bias and the skewed pattern of cytokine production in the orbit, thereby determining the outcomes of GO autoimmune reactions. Characterization of the T cell subsets that drive GO and the cytokines they express may significantly advance our understanding of orbital autoimmunity and the development of promising therapeutic strategies against pathological T cells.

Therapeutic Effect of Guggulsterone in Primary Cultured Orbital Fibroblasts Obtained From Patients with Graves' Orbitopathy

Purpose

Inflammation, hyaluronan production, and adipogenesis are the main pathological events leading to Graves' orbitopathy (GO). Guggulsterone (GS), a phytosterol found in the resin of the guggul plant, is a well-known treatment for several inflammatory disorders, such as arthritis, obesity, and hyperlipidemia. Here we investigated the effects of GS treatment on GO pathology.

Methods

Using primary cultures of orbital fibroblasts from GO patients and non-GO controls, we examined the effects of GS on hyaluronan production and the production of proinflammatory cytokines induced by interleukin (IL)-1β, using real-time reverse transcription-polymerase chain reaction analysis, western blots, and enzyme-linked immunosorbent assays. Further, adipogenic differentiation was evaluated by quantification of Oil Red O staining and assessment of protein levels of peroxisome proliferator activator gamma (PPARγ), CCAAT-enhancer-binding proteins (C/EBP) α and β, and sterol regulatory element-binding protein-1 (SREBP-1).

Results

Treatment with noncytotoxic concentrations of GS resulted in the dose-dependent inhibition of IL-1β-induced inflammatory cytokines, including IL-6, IL-8, MCP-1, and COX-2, at both mRNA and protein levels. The hyaluronan level was also significantly suppressed by GS. Moreover, GS significantly decreased the formation of lipid droplets and expression of PPARγ, C/EBP α/β, and SREBP-1 in a dose-dependent manner. GS pretreatment attenuated the phosphorylation of nuclear factor-kappa B induced by IL-1β.

Conclusions

Our data show significant inhibitory effects of GS on inflammation, production of hyaluronan, and adipogenesis in orbital fibroblasts. To our knowledge, this is the first in vitro preclinical evidence of the therapeutic effect of GS in GO.

Immunohistochemical analysis of human orbital tissue in Graves' orbitopathy

PURPOSE

Immunohistochemistry of orbital tissues offers a correlation between the microscopic changes and macroscopic clinical manifestation of Graves' orbitopathy (GO). Summarizing the participation of different molecules will help us to understand the pathogenesis of GO.

METHODS

The pertinent and current literature on immunohistochemistry of human orbital tissue in GO was reviewed using the NCBI PubMed database.

RESULTS

33 articles comprising over 700 orbital tissue samples were included in this review. The earliest findings included the demonstration of HLA-DR and T cell (to a lesser extent B cell) markers in GO orbital tissues. Subsequent investigators further contributed by characterizing cellular infiltration, confirming the presence of HLA-DR and TSHR, as well as revealing the participation of cytokines, growth factors, adhesion molecules and miscellaneous substances. HLA-DR and TSHR are over-expressed in orbital tissues of GO patients. The inflammatory infiltration mainly comprises CD4 + T cells and macrophages. Cytokine profile suggests the importance of Th1 (especially in early active phase) and Th17 immunity in the pathogenesis of GO. Upregulation of proinflammatory/profibrotic cytokines, adhesion molecules and growth factors finally culminate in activation of orbital fibroblasts and perpetuation of orbital inflammation. The molecular status of selected parameters correlates with the clinical presentation of GO.

CONCLUSION

Further investigation is warranted to define precisely the role of different molecules and ongoing search for new players yet to be discovered is also important. Unfolding the molecular mechanisms behind GO will hopefully provide insights into the development of novel therapeutic strategies and optimize our clinical management of the disease.

The potential markers involved in newly diagnosed graves' disease and the development of active graves' orbitopathy

BACKGROUND

Graves' disease (GD) patients experience two major issues: one is the severe hyperthyroidism associated with newly diagnosed GD, and the other involves the disfiguring and dysfunctional features of active Graves' orbitopathy (GO). Therefore, the aim of our study was to identify potential markers involved in the initial phase of GD dysfunction and the development of active GO.

METHODS

Seventy-eight subjects were recruited: 40 with newly diagnosed GD, 20 with inactive GO and 18 with active GO. GO activity was evaluated by the clinical activity score (CAS, active GO = CAS ≥ 3), and severity was assessed according to the NOSPECS classification. Plasma selenium concentrations were determined by dual channel hydride generation atomic fluorescence photometry. A liquid chip assay was used to measure plasma Th1 cytokines IFN-γ and TNF-α; Th2 cytokines IL4, IL5 and IL6; Th17 cytokine IL23; Treg cytokines IL10 and TGF-β; and two chemokines, CCL2 (Th2 chemokine) and CXCL10 (Th1 chemokine).

RESULTS

Among the three groups, newly diagnosed GD patients showed significantly elevated plasma levels of CXCL10 and IL-23 (all p < 0.05). Both CXCL10 and IL23 were significantly correlated with hyperthyroidism severity, specifically, increasing FT3 and FT4 and decreasing TSH. Notably, a very strong positive relationship between IL23 and CXCL10 was revealed (adjusted R square = 0.795; p < 0.001). Moreover, the selenium level was lower, while that of CCL2 was higher, in active GO than in inactive GO (p = 0.007, p < 0.001, respectively). Likewise, we also discovered that increasing CCL2 levels and decreasing selenium levels were associated with high CAS. Remarkably, after adjusting for potential confounding factors, selenium (OR, 0.919) and CCL2 (OR, 1.042) were still independent predictors for the diagnosis of active GO, and similar conclusions were drawn by receiver operating characteristic (ROC) curve analysis.

CONCLUSION

Pro-inflammatory cytokines, especially Th17-associated cytokines (e.g., IL23) and Th1 chemokines (e.g., CXCL10), appear to be involved in the initial phase of GD dysfunction. Moreover, we revealed for the first time that decreased plasma selenium levels and increased concentrations of Th2 chemokines (e.g., CCL2) may reflect GO disease activity, shedding light on the diagnosis and evaluation of active GO.

The role of cell mediated immunopathogenesis in thyroid-associated ophthalmopathy

Currently, thyroid-associated ophthalmopathy (TAO) lacks effective treatment due to our lack of clarity in its immunopathogenesis. Orbital fibroblasts play a key role in altering inflammation and immune response in TAO, and are considered as the key target and effector cells in its pathogenesis. The orbit infiltrating CD34+ fibrocytes add on to the process by expressing high levels of autoantigens and inflammatory cytokines, while also differentiating into myofibroblasts or adipocytes. This review focuses on the role of orbital fibroblasts and CD34+ fibrocytes in the pathogenesis of TAO, highlighting the basis of emerging treatments.

Macrophages promote a profibrotic phenotype in orbital fibroblasts through increased hyaluronic acid production and cell contractility

Graves’ orbitopathy (GO) is an autoimmune inflammatory disease affecting the orbit. Orbital fibroblasts are a key component in GO pathogenesis, which includes inflammation, adipogenesis, hyaluronic acid (HA) secretion, and fibrosis. Macrophages are thought to participate in the immunological stage of GO, but whether they can directly affect the fibroblasts phenotype and modulate disease progression is unknown. We previously showed that GO adipogenic and fibrotic phenotypes could be modelled in a pseudo-physiological 3D environment in vitro. Here, we introduced macrophages in this 3D culture model to investigate role for macrophages in modulating adipogenesis, HA production, and contractility in orbital fibroblasts. Macrophages had a minimal effect on lipid droplet formation in fibroblasts, but significantly increased HA production and cell contractility, suggesting that they may promote the fibrotic phenotype. This effect was found to be mediated at least in part through phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) activation and linked to an increase in actin polymerization and protrusive activity in fibroblasts. Overall our work shows for the first time a direct role for macrophages in modulating the fibroblasts’ phenotype in GO, supporting a role for macrophages in the progression of the fibrotic phenotype through induction of HA production and stimulation of the contractile phenotype in orbital fibroblasts.

RNA-Sequencing Gene Expression Profiling of Orbital Adipose-Derived Stem Cell Population Implicate HOX Genes and WNT Signaling Dysregulation in the Pathogenesis of Thyroid-Associated Orbitopathy

Purpose

The purpose of this study was to characterize the intrinsic cellular properties of orbital adipose-derived stem cells (OASC) from patients with thyroid-associated orbitopathy (TAO) and healthy controls.

Methods

Orbital adipose tissue was collected from a total of nine patients: four controls and five patients with TAO. Isolated OASC were characterized with mesenchymal stem cell–specific markers. Orbital adipose-derived stem cells were differentiated into three lineages: chondrocytes, osteocytes, and adipocytes. Reverse transcription PCR of genes involved in the adipogenesis, chondrogenesis, and osteogenesis pathways were selected to assay the differentiation capacities. RNA sequencing analysis (RNA-seq) was performed and results were compared to assess for differences in gene expression between TAO and controls. Selected top-ranked results were confirmed by RT-PCR.

Results

Orbital adipose-derived stem cells isolated from orbital fat expressed high levels of mesenchymal stem cell markers, but low levels of the pluripotent stem cell markers. Orbital adipose-derived stem cells isolated from TAO patients exhibited an increase in adipogenesis, and a decrease in chondrogenesis and osteogenesis. RNA-seq disclosed 54 differentially expressed genes. In TAO OASC, expression of early neural crest progenitor marker (WNT signaling, ZIC genes and MSX2) was lost. Meanwhile, ectopic expression of HOXB2 and HOXB3 was found in the OASC from TAO.

Conclusion

Our results suggest that there are intrinsic genetic and cellular differences in the OASC populations derived from TAO patients. The upregulation in adipogenesis in OASC of TAO may be is consistent with the clinical phenotype. Downregulation of early neural crest markers and ectopic expression of HOXB2 and HOXB3 in TAO OASC demonstrate dysregulation of developmental and tissue patterning pathways.

Quantitative Analysis of Inflammation in Orbital Fat of Thyroid-associated Ophthalmopathy Using MRI Signal Intensity

We quantitatively analyzed inflammation in orbital fat from cases of thyroid-associated ophthalmopathy (TAO) using short-tau inversion recovery (STIR) sequences from magnetic resonance imaging. The signal intensity ratios (SIRs) of orbital fat as well as the superior rectus (SR), inferior rectus (IR), lateral rectus (LR), medial rectus (MR), and superior oblique (SO) muscles on STIR images were measured in 70 eyes from 70 treatment-naive TAO patients (active TAO group, 19 patients; inactive TAO group, 51 patients) and 20 eyes from 20 controls. The mean SIR in the active TAO group was significantly higher than that in the inactive TAO group and controls (P < 0.001). The SIR of orbital fat in all TAO patients was significantly (P < 0.001) positively correlated with that of the extraocular muscles: SR (r = 0.64), IR (r = 0.55), LR (r = 0.58), MR (r = 0.71), and SO (r = 0.65). The SIR of orbital fat had a significant positive correlation with the CAS (r = 0.53, P < 0.001). The measurements of SIRs in orbital fat may be useful in evaluating the activity in tissues of TAO patients.

Histamine induces NF-κB controlled cytokine secretion by orbital fibroblasts via histamine receptor type-1

Mast cells and their products are likely to be involved in regulating orbital fibroblast activity in Graves' Ophthalmopathy (GO). Histamine is abundantly present in granules of mast cells and is released upon mast cell activation. However, the effect of histamine on orbital fibroblasts has not been examined so far. Orbital tissues from GO patients and controls were analyzed for the presence of mast cells using toluidine blue staining and immunohistochemical detection of CD117 (stem cell factor receptor). Orbital fibroblasts were cultured from GO patients and healthy controls, stimulated with histamine and cytokines (IL-6, IL-8, CCL2, CCL5, CCL7, CXCL10 and CXCL11) were measured in culture supernatants. Also hyaluronan levels were measured in culture supernatants and hyaluronan synthase (HAS) and hyaluronidase (HYAL) gene expression levels were determined. In addition, histamine receptor subtype gene expression levels were examined as well as the effect of the histamine receptor-1 (HRH1) antagonist loratadine and NF-κB inhibitor SC-514 on histamine-induced cytokine production. Mast cell numbers were increased in GO orbital tissues. Histamine stimulated the production of IL-6, IL-8 and CCL2 by orbital fibroblasts, while it had no effect on the production of CCL5, CCL7, CXCL10, CXCL11 and hyaluronan. Orbital fibroblasts expressed HRH1 and loratadine and SC-514 both blocked histamine-induced IL-6, IL-8 and CCL2 production by orbital fibroblasts. In conclusion, this study demonstrates that histamine can induce the production of NF-κB controlled-cytokines by orbital fibroblasts, which supports a role for mast cells in GO.

Pathogenesis of thyroid eye disease: review and update on molecular mechanisms

Orbital changes in thyroid orbitopathy (TO) result from de novo adipogenesis, hyaluronan synthesis, interstitial oedema and enlargement of extraocular muscles. Cellular immunity, with predominantly CD4+ T cells expressing Th1 cytokines, and overexpression of macrophage-derived cytokines, perpetuate orbital inflammation. Orbital fibroblasts appear to be the major effector cells. Orbital fibroblasts express both thyrotropin receptor (TSHR) and insulin-like growth factor-1 receptor (IGF-1R) at higher levels than normal fibroblasts. TSHR expression increases in adipogenesis; TSHR agonism enhances hyaluronan production. IGF-1R stimulation leads to adipogenesis, hyaluronan synthesis and production of the chemokines, interleukin (IL)-16 and Regulated on Activation, Normal T Cell Expression and Secreted, which facilitate lymphocyte trafficking into the orbit. Immune activation uses a specific CD40:CD154 molecular bridge to activate orbital fibroblasts, which secrete pro-inflammatory cytokines including IL-1β, IL-1α, IL-6, IL-8, macrophage chemoattractant protein-1 and transforming growth factor-β, to perpetuate orbital inflammation. Molecular pathways including adenylyl cyclase/cyclic adenosine monophosphate, phophoinositide 3 kinase/AKT/mammalian target of rapamycin, mitogen-activated protein kinase are involved in TO. The emergence of a TO animal model and a new generation of TSHR antibody assays increasingly point towards TSHR as the primary autoantigen for extrathyroidal orbital involvement. Oxidative stress in TO resulting from imbalances of the oxidation-reduction state provides a framework of understanding for smoking prevention, achieving euthyroidism and the use of antioxidants such as selenium. Progress has been made in the understanding of the pathogenesis of TO, which should advance development of novel therapies targeting cellular immunity, specifically the CD40:CD40 ligand interaction, antibody-producing B cells, cytokines, TSHR and IGF-1R and its signalling pathways. Further studies in signalling networks and molecular triggers leading to burnout of TO will further our understanding of TO.

Markers of inflammation and fibrosis in the orbital fat/connective tissue of patients with Graves' orbitopathy: clinical implications

Purpose. To assess FGF-β, TGF-β, and COX2 expression and immunocompetent cells in the orbital tissue of patients with severe and mild Graves' orbitopathy. Patients and Methods. Orbital tissue was taken from 27 patients with GO: (1) severe GO (n = 18), the mean clinical activity score (CAS) being 8.5 (SD 2.5); and (2) mild GO (n = 9), the mean CAS being 2.2 (SD 0.8), and from 10 individuals undergoing blepharoplasty. The expression of CD4+, CD8+, CD20+, and CD68 and FGF-β, TGF-β, and COX2 in the orbital tissue was evaluated by immunohistochemical methods. Results. We demonstrated predominant CD4+ T cells in severe GO. CD68 expression was observed in the fibrous connective area of mild GO and was robust in severe GO, while the prominent TGF-β expression was seen in all GO. Increased FGF-β expression was observed in the fibroblasts and adipocytes of severe GO. No expression of COX2 was found in patients with GO. Conclusions. Macrophages and CD4 T lymphocytes are both engaged in the active/severe and long stage of inflammation in the orbital tissue. FGF-β and TGF-β expression may contribute to tissue remodeling, fibrosis, and perpetuation of inflammation in the orbital tissue of GO especially in severe GO.

Extra-ocular muscle cells from patients with Graves' ophthalmopathy secrete α (CXCL10) and β (CCL2) chemokines under the influence of cytokines that are modulated by PPARγ

To our knowledge, no study has evaluated the involvement of T helper (Th)1- and Th2-chemokines in extra-ocular muscle (EOM) myopathy in "patients with thyroid-associated ophthalmopathy" (TAO-p). We tested the effects of interferon (IFN)γ and tumor necrosis factor (TNF)α stimulation, and of increasing concentrations of peroxisome proliferator-activated receptor (PPAR)γ agonists (pioglitazone or rosiglitazone; 0.1 μM-20 μM), on Th1-chemokine [C-X-C motif ligand (CXCL)10] and Th2-chemokine [C-C motif ligand (CCL)2] secretion in primary EOM cultures from TAO-p vs. control myoblasts. Moreover, we evaluated serum CXCL10 and CCL2 in active TAO-p with prevalent EOM involvement (EOM-p) vs. those with prevalent orbital fat expansion (OF-p). Serum CXCL10 was higher in OF-p and EOM-p vs. controls, while serum CCL2 was not significantly different in controls, or in OF-p and EOM-p. We showed the expression of PPARγ in EOM cells. In primary EOM cultures from TAO-p: a) CXCL10 was undetectable in the supernatant, IFNγ dose-dependently induced it, whereas TNFα did not; b) EOM produced basally low amounts of CCL2, TNFα dose-dependently induced it, whereas IFNγ did not; c) the combination of TNFα and IFNγ had a significant synergistic effect on CXCL10 and CCL2 secretion; and d) PPARγ agonists have an inhibitory role on the modulation of CXCL10, while they stimulate CCL2 secretion. EOM participates in the self-perpetuation of inflammation by releasing both Th1 (CXCL10) and Th2 (CCL2) chemokines under the influence of cytokines, in TAO. PPARγ agonist activation plays an inhibitory role on CXCL10, but stimulates the release of CCL2.

Hypoxia increases adipogenesis and affects adipocytokine production in orbital fibroblasts-a possible explanation of the link between smoking and Graves' ophthalmopathy

AIM

To assess the effects of hypoxia on human orbital fibroblasts (OF) on adipogenesis and adipocytokine production.

METHODS

Human OF were derived from tissues obtained from patients with Graves' ophthalmopathy (GO) and from patients without known thyroid diseases undergoing blepharoplasty. The OF were cultured separately under normoxic and hypoxic conditions. Comparisons of adipocytokine concentrations using multiplex ELISA and lipid accumulation in the cells using Oil Red O staining were subsequently performed.

RESULTS

There was increased adipogenesis in OF from GO subject when exposed to hypoxic culture conditions. This was not observed in OF from normal controls. Hypoxia led to an increase in leptin and a decrease in MCP-1 secretion in OF cultures.

CONCLUSION

Hypoxia induces adipogenesis in OF and may represent a mechanism by which smoking contributes to deterioration of GO. We also found novel changes to leptin and MCP-1 production in OF cultures exposed to hypoxia suggesting important roles of these cytokines in the disease process.

Current concepts in the molecular pathogenesis of thyroid-associated ophthalmopathy

Graves' disease (GD) is a common autoimmune condition. At its core, stimulatory autoantibodies are directed at the thyroid-stimulating hormone receptor (TSHR), resulting in dysregulated thyroid gland activity and growth. Closely associated with GD is the ocular condition known as thyroid-associated ophthalmopathy (TAO). The pathogenesis of TAO remains enigmatic as do the connections between the thyroid and orbit. This review highlights the putative molecular mechanisms involved in TAO and suggests how these insights provide future directions for identifying therapeutic targets. Genetic, epigenetic, and environmental factors have been suggested as contributory to the development of GD and TAO. Thyroid-stimulating hormone receptor and insulin-like growth factor receptor (IGF-1R) are expressed at higher levels in the orbital connective tissue from individuals with TAO than in healthy tissues. Together, they form a functional complex and appear to promote signaling relevant to GD and TAO. Orbital fibroblasts display an array of cell surface receptors and generate a host of inflammatory molecules that may participate in T and B cell infiltration. Recently, a population of orbital fibroblasts has been putatively traced to bone marrow-derived progenitor cells, known as fibrocytes, as they express CD45, CD34, CXCR4, collagen I, functional TSHR, and thyroglobulin (Tg). Fibrocytes become more numerous in GD and we believe traffic to the orbit in TAO. Numerous attempts at developing complete animal models of GD have been largely unsuccessful, because they lack fidelity with the ocular manifestations seen in TAO. Better understanding of the pathogenesis of TAO and development of improved animal models should greatly accelerate the identification of medical therapy for this vexing medical problem.

β (CCL2) and α (CXCL10) chemokine modulations by cytokines and peroxisome proliferator-activated receptor-α agonists in Graves' ophthalmopathy

No data are present in the literature about the effect of cytokines on the prototype β chemokine (C-C motif) ligand 2 (CCL2) or of peroxisome proliferator-activated receptor α (PPARα (PPARA)) activation on CCL2 and CXCL10 chemokines secretion in fibroblasts or preadipocytes in Graves' ophthalmopathy (GO). We have tested the effect of interferon γ (IFNγ (IFNG)) and tumor necrosis factor α (TNFα) on CCL2, and for comparison on the prototype α chemokine (C-X-C motif) ligand 10 (CXCL10), and the possible modulatory role of PPARα activation on secretion of these chemokines in normal and GO fibroblasts or preadipocytes in primary cell cultures. This study shows that IFNγ alone, or in combination with TNFα, stimulates the secretion of CCL2 in primary orbital fibroblasts or preadipocytes from patients with GO at levels similar to those observed in controls. IFNγ and TNFα also stimulated CXCL10 chemokine secretion as expected. The presence of PPARα and PPARγ (PPARG) in primary fibroblasts or preadipocytes of patients with GO has been confirmed. PPARα activators were able to inhibit the secretion of CXCL10 and CCL2, while PPARγ activators were confirmed to be able to inhibit CXCL10 but had no effect on CCL2. PPARα activators were stronger inhibitors of chemokine secretions than PPARγ agonists. In conclusion, CCL2 and CXCL10 are modulated by IFNγ and TNFα in GO. PPARα activators inhibit the secretion of the main prototype α (CXCL10) and β (CCL2) chemokines in GO fibroblasts or preadipocytes, suggesting that PPARα may be involved in the modulation of the immune response in GO.

Adoptive transfer of antithyrotropin receptor (TSHR) autoimmunity from TSHR knockout mice to athymic nude mice

We have recently shown that wild type mice are highly tolerant, whereas thyrotropin receptor (TSHR) knockout (KO) mice are susceptible to immunization with the mouse TSHR, the autoantigen in Graves' disease. However, because TSHR KO mice lack the endogenous TSHR, Graves-like hyperthyroidism cannot be expected to occur in these mice. We therefore performed adoptive transfer of splenocytes from TSHR KO mice into nude mice expressing the endogenous TSHR. Anti-TSHR autoantibodies were detected in approximately 50 % recipient mice 4 wk after adoptive transfer of splenocytes (5 × 10⁷/mouse) from TSHR KO mice immunized with adenovirus expressing mTSHR A subunit and persisted for 24 wk. Depletion of regulatory T cells by anti-CD25 antibody in the donor mice increased successful transfer rates without increasing antibody levels. Some recipient mice showed transient increases in thyroid-stimulating antibodies and T₄ levels 4-8 wk after transfer, but many became thyroid-blocking antibody positive and hypothyroid 24 wk later. Adoptive transfer of splenocytes from naïve TSHR KO mice transiently induced very low antibody titers when the recipient mice were treated with anticytotoxic lymphocyte antigen 4 and antiprogrammed cell death 1 ligand 1 antibodies for 8 wk after transfer. Histologically, macrophages infiltrated the retrobulbar adipose tissues and extraocular muscles in a small fraction of the recipients. Our findings demonstrate successful adoptive transfer of anti-TSHR immune response from TSHR KO mice to nude mice. Although the recipient mice developed only transient and infrequent hyperthyroidism, followed by eventual hypothyroidism, induction of orbital inflammation suggests the possible role of anti-TSHR immune response for Graves' orbitopathy.

Orbit-infiltrating mast cells, monocytes, and macrophages produce PDGF isoforms that orchestrate orbital fibroblast activation in Graves' ophthalmopathy

PURPOSE

Platelet-derived growth factors (PDGF) are regulators of fibroblast activity that may be involved in the pathophysiology of Graves' ophthalmopathy (GO). We unraveled the expression and origin of PDGF family members in GO orbital tissue and investigated the effect of PDGF isoforms on IL-6 and hyaluronan production and proliferation by orbital fibroblasts.

METHODS

PDGF-A, PDGF-B, PDGF-C, PDGF-D, PDGF-Rα, and PDGF-Rβ expression was determined by real-time quantitative PCR and PDGF-A and PDGF-B protein expression was determined by Western blot in orbital tissues. Orbital tissues were immunohistochemically stained for PDGF-A and PDGF-B expression, together with stainings for T cells, monocytes, B cells, macrophages, and mast cells. Effects of PDGF-AA, PDGF-AB, and PDGF-BB on orbital fibroblast proliferation and IL-6 and hyaluronan production were examined. Finally, effects of PDGF-BB- and PDGF-AA-neutralizing antibodies on IL-6 and hyaluronan production in GO whole orbital tissue cultures were tested.

RESULTS

GO orbital tissue showed increased PDGF-A and PDGF-B mRNA and protein levels. Increased numbers of PDGF-A- and PDGF-B-positive monocytes, macrophages, and mast cells were present in GO orbital tissue. PDGF-BB stimulated proliferation and hyaluronan and IL-6 production by orbital fibroblasts the most, followed by PDGF-AB and PDGF-AA. Finally, in particular imatinib mesylate and PDGF-BB-neutralizing antibodies reduced IL-6 and hyaluronan production by whole orbital tissue cultures from GO patients.

CONCLUSIONS

In GO, mast cells, monocytes, and macrophages may activate orbital fibroblasts via secretion of especially PDGF-AB and PDGF-BB. Preclinical studies with whole orbital tissue cultures show that blocking PDGF-B chain containing isoforms can be a promising treatment for GO.

Medical management of thyroid eye disease

Thyroid eye disease (TED) is the most common cause of orbital disease in adults. The immunologic pathogenesis of TED has been an area of active research and considerable progress has resulted in an expansion of therapeutic options. Although surgical intervention may be required, a majority of TED patients can be managed with medical therapies. Of medical therapies, glucocorticoids remain the agent of choice in the control of TED activity. The objective of this review is to discuss the paradigm and options in medical management of TED.

Orbital fibroblasts from patients with thyroid-associated ophthalmopathy overexpress CD40: CD154 hyperinduces IL-6, IL-8, and MCP-1

PURPOSE

Fibroblast diversity represents an emerging concept critical to our understanding of tissue inflammation, repair, and remodeling. Orbital fibroblasts heterogeneously display Thy-1 and exhibit unique phenotypic attributes that may explain the susceptibility of the human orbit to thyroid-associated ophthalmopathy (TAO). In the present study the authors investigated the role of CD40 ligation on macrophage chemoattractant protein-1 (MCP-1), IL-6, and IL-8 expression in fibroblasts from patients with TAO.

METHODS

Human orbital fibroblasts were cultured from tissues obtained with informed consent from patients with TAO and from patients undergoing surgery for other noninflammatory conditions. The fibroblasts were then examined by flow cytometry, microscopy, and cytokine assays.

RESULTS

The authors report that orbital fibroblasts from patients with TAO expressed elevated levels of CD40. Surface CD40 could be further upregulated by IFN-gamma in TAO and control fibroblasts. This upregulation was mediated through Jak2 and could be blocked by dexamethasone and AG490, a powerful and specific inhibitor of tyrosine kinase. Treatment with CD154, the ligand for CD40, upregulated the expression of IL-6, IL-8, and MCP-1 in TAO fibroblasts but failed to do so in control cultures. Thy-1(+) fibroblasts displayed higher CD40 levels than did their Thy-1(-) counterparts and were largely responsible for this cytokine production. IL-1beta also induced MCP-1, IL-6, and IL-8 more vigorously in TAO-derived fibroblasts.

CONCLUSIONS

Characterization of orbital fibroblasts and their differential expression of cytokines and receptors should prove invaluable in understanding the site-specific nature of TAO and the development of specific therapies.

The eye and thyroid disease

PURPOSE OF REVIEW

The pathophysiology and optimal management of thyroid eye disease (TED) have not yet been elucidated. Recent studies have increased our knowledge of the disease process and different diagnostic and therapeutic options. This review highlights the recent progress in TED research and identifies areas requiring further advancements.

RECENT FINDINGS

The pathophysiology of TED likely involves genetic and environmental factors, which may potentiate cellular and humoral-mediated inflammation within the orbit. Despite progress in TED research, a target antigen has not been established with certainty. New diagnostic methods and questionnaires are being developed that potentially provide information regarding inflammatory activity of TED. Corticosteroids alone or in combination with orbital radiation may be effective in improving TED symptoms. New immunomodulating therapies may also have a role TED management. Surgery is highly effective for treatment of TED-induced optic nerve compression and for managing the chronic soft tissue changes of TED.

SUMMARY

A unifying hypothesis of TED pathophysiology is elusive. Further bench research into the autoimmune process is needed. In addition, large, prospective, randomized clinical trials based on the inflammatory activity of disease, while difficult to design, are essential to develop a consensus regarding the proper timing and use of anti-inflammatory medications.