Circulating mononuclear cells from euthyroid patients with thyroid-associated ophthalmopathy exhibit characteristic phenotypes

Effect of systemic steroid therapy in Graves' orbitopathy on regulatory T cells and Th17/Treg ratio

PURPOSE

Glucocorticoids are a mainstay treatment for Graves' orbitopathy, yet their exact mechanisms of action remain unclear. We aimed to determine whether the therapeutic effects of systemic steroid therapy in Graves' orbitopathy are mediated by changes in regulatory T lymphocytes (Tregs) and T helper 17 lymphocytes (Th17).

METHODS

We assessed Treg and Th17 levels in the peripheral blood of 32 patients with active, moderate-to-severe Graves' orbitopathy who received 12 weekly pulses of methylprednisolone, and determined their association with disease severity, disease activity, and treatment outcomes. The acute orbitopathy phase was confirmed based on clinical evaluation and magnetic resonance imaging, and assessed using the clinical activity score (CAS). The severity of the disease was classified according to ETA/EUGOGO guidelines, and quantified based on the total eye score. Treatment response was determined based on specific criteria (e.g., changes in CAS score, diplopia grade, visual acuity, etc.). Treg and Th17 cells were identified using flow cytometry.

RESULTS

Methylprednisolone treatment improved the activity of the disease and altered the Th17/Treg balance (i.e., the percentage of Tregs decreased while the number of Th17 cells remained unchanged). There was no association between the Treg/Th17 ratio and the activity and severity of the disease or the treatment response.

CONCLUSIONS

Therapeutic effects of steroid therapy in Graves' orbitopathy are not mediated by Treg and Th17 alterations in the peripheral blood. The decrease in peripheral Treg percentage is likely a consequence of the non-specific effects of steroids and does not impact clinical outcome.

Orbital inflammatory disorders: new knowledge, future challenges

PURPOSE OF REVIEW

This review aims to bring together recent advances in basic, translational and clinical research on the pathogenesis and treatment of orbital inflammatory conditions.

RECENT FINDINGS

Basic science studies provide mechanistic insights into why the orbit is targeted for inflammation by autoimmune inflammatory disorders. Using Graves' disease as a test case reveals that endocrine pathways, such as the TSH and IGF1 receptor pathways play important roles in stimulating orbital inflammation. Furthermore, orbital tissues contain high concentrations of retinoids - byproducts of the visual pathway that diffuse across the sclera and can activate de novo transcription of inflammatory cytokines. Such cytokine expression places the orbit in a hyper-inflammatory 'resting' state, prone to respond to any additional systemic or local pro-inflammatory signals. The HIF2A--LOX pathway appears important for orbital tissue fibrosis. Lastly, bench-to-bedside studies of the IGF1R pathway have led to an FDA-approved drug, teprotumumab that represents a novel treatment approach for Graves' orbitopathy. Unfortunately, high drug costs and misplaced insurance company 'step-therapy' policies may block patients from receiving therapy that can protect vision and improve quality of life.

SUMMARY

Improved understanding of orbital inflammatory conditions has led to a new drug and promises additional breakthroughs. Translational research is successful, but requires time, resources, and patience.

Efficacy and safety of mycophenolate mofetil in patients with active moderate-to-severe Graves' orbitopathy

CONTEXT

Graves' orbitopathy (GO) is a potentially sight-threatening disease for which currently available medical therapy is not reliably successful. Mycophenolate mofetil (MMF) is a selective immunosuppressant used widely in many autoimmune diseases. Preliminary studies have shown that MMF is effective in the treatment of active GO.

OBJECTIVE

To evaluate the efficacy and safety of MMF in patients with active moderate-to-severe GO.

PATIENTS

One hundred and 74 patients with active moderate-to-severe GO were randomized to receive either MMF or glucocorticoids (GC).

MAIN OUTCOME MEASURES

The primary outcome was overall response at the 12th and 24th weeks; the outcome assessments included clinical activity score (CAS), soft tissue involvement, pain, visual acuity, proptosis, diplopia and reduction in eye movements. The secondary outcome was changes in those individual parameters. Adverse effects were recorded at each visit.

RESULTS

A greater overall response rate was found in the MMF group compared with the GC group at the 24th week (91·3% vs 67·9%, P = 0·000). MMF therapy showed a better CAS response than GC (92·5% vs 70·5% improved, P < 0·05). Patients treated with MMF showed a significantly improved rate of diplopia and proptosis than patients treated with GC at the 24th week (90·4% and 68·8% improved, respectively). Disease reactivation was not observed in the patients treated with MMF but was observed in five patients after GC therapy. Adverse events occurred in 4 of 80 patients treated with MMF (5%), all of which were mild to moderate. A severe adverse event was only observed in one patient treated with GC but not at all in patients treated with MMF.

CONCLUSION

Compared with GC treatment, MMF therapy is more effective and safer for patients with active moderate-to-severe GO.

Implications of FoxP3-positive and -negative CD4(+) CD25(+) T cells in Graves' ophthalmopathy

Graves' ophthalmopathy (GO) is a common manifestation of Graves' disease (GD); however, its pathogenesis is not well understood. Recently, the dysregulation of regulatory T cells (Tregs) has been thought to be closely associated with the pathogenesis and clinical symptoms of autoimmune disease. We therefore evaluated whether T cell subsets, including Tregs, are associated with GO pathogenesis and clinical symptoms. In this observational study we evaluated 35 GD patients with overt ophthalmopathy (GOs) and 28 patients without ophthalmopathy (non-GOs). Fifteen healthy euthyroid patients served as healthy controls (HCs). Peripheral blood mononuclear cells from GOs, non-GOs and HCs were analyzed for CD4, CD25, and FoxP3 expression using flow cytometry. We also evaluated their correlation with disease activity according to the clinical activity score (CAS) and magnetic resonance imaging (MRI) findings. Disease severity was evaluated using the NOSPECS score, and clinical progression of GO was followed for 24 weeks. The main outcome measures were the frequencies of FoxP3-positive and -negative CD4(+) CD25(+) T cells at study outset, namely Tregs and effector T cells (Teffs), respectively. GOs had higher frequencies of Teffs (30.8±8.4%) than non-GOs (19.4±7.1%) and HCs (22.7±7.9%). Notably, patients with improved GOs had lower frequencies of Tregs (5.8±1.1%) than patients with stable or deteriorated GOs (7.3±1.2%), although ophthalmic and radiological parameters were not significantly different at the start of the study. In conclusion, an expanded Teff population may be associated with GO pathogenesis. Additionally, decreased Tregs in peripheral blood may predict a good clinical outcome.

Treatment of active corticosteroid-resistant graves' orbitopathy

PURPOSE

To assess the efficacy of Tocilizumab, a humanized monoclonal antibody against the interleukin-6 receptor, in thyroid eye disease patients refractory to multiple intravenous steroids.

METHODS

Prospective interventional nonrandomized study including active GO defined by Clinical Activity Score (CAS) ≥4 patients resistant to previous intravenous steroids treated with Tocilizumab was conducted from February 2010 to September 2012. Snellen visual acuity, Hertel exophthalmometry, CAS evaluation, TSI levels, ocular motility, and side effects were registered at a 4-week interval.

RESULTS

Eighteen patients were included with a mean age of 47.9 ± 8.63 years. All patients had a significant progressive CAS improvement (mean CAS score reduction 5.89 ± 1.41 points, p< 0.00027). Mean TSI levels were significantly lower at the end of the treatment (mean -76.18% ± 17.80%, p = 0.00007). Thirteen patients (72.22%) reduced proptosis a mean of -3.92 ± 1.54 mm (p = 0.002). Fifteen patients (83.33%) had an improvement in extraocular motility, and 7 patients of 13 resolved their diplopia (53.85%). No severe side effects or relapse of active GO were observed at the end of follow up.

CONCLUSIONS

This study suggests that intravenous Tocilizumab may be effective on reducing activity in patients with thyroid eye disease refractory to intravenous steroids.

Cytokines are both villains and potential therapeutic targets in thyroid-associated ophthalmopathy: From bench to bedside

The pathophysiology underlying Graves' disease and its ocular manifestation, thyroid associated ophthalmopathy (TAO) is incompletely understood. Characterization of the mononuclear cells driving the disease and the cytokines they produce has led to significant advances in our understanding of TAO. This in turn has resulted in the identification of potentially attractive drug targets. For instance, development of inhibitors of specific cytokine pathways for use in other autoimmune diseases now presents an opportunity for their application in TAO. In this paper, we review the rationale for considering anti-cytokine therapy in TAO, evidence linking specific cytokines such as interleukin-6, tumor necrosis factor-α, and interleukin-17 pathways to TAO, and explore the potential for targeting of these pathways as therapy.

Increased microRNA-155 and decreased microRNA-146a may promote ocular inflammation and proliferation in Graves' ophthalmopathy

Graves' ophthalmopathy is an inflammatory autoimmune disease of the orbit, characterized by inflammation and proliferation of the orbital tissue caused by CD4+T cells and orbital fibroblasts. Despite recent substantial findings regarding its cellular and molecular foundations, the pathogenesis of Graves' ophthalmopathy remains unclear. Accumulating data suggest that microRNAs play important roles in the pathophysiology of autoimmunity and proliferation. Specifically, microRNA-155 (miR-155) can promote autoimmune inflammation by enhancing inflammatory T cell development. In contrast to miR-155, microRNA-146a (miR-146a) can inhibit the immune response by suppressing T cell activation. Furthermore, miR-155 and miR-146a are involved in cell proliferation, differentiation, and many other life processes. Thus, miR-155 and miR-146a, with opposite impacts on inflammatory responses carried out by T lymphocytes, appear to have multiple targets in the pathogenesis of Graves' ophthalmopathy. Our previous work showed that the expression of miR-146a was significantly decreased in peripheral blood mononuclear cells from Graves' ophthalmopathy patients compared with normal subjects. Accordingly, we proposed that the expression of miR-155 increased and the expression of miR-146a decreased in the target cells (CD4+T cells and orbital fibroblasts), thus promoting ocular inflammation and proliferation in Graves' ophthalmopathy. The proposed hypothesis warrants further investigation of the function of the differentially expressed microRNAs, which may shed new light on the pathogenesis of Graves' ophthalmopathy and lead to new strategies for its management.

Regulation of Lymphocyte Function by PPARgamma: Relevance to Thyroid Eye Disease-Related Inflammation

Thyroid eye disease (TED) is an autoimmune condition in which intense inflammation leads to orbital tissue remodeling, including the accumulation of extracellular macromolecules and fat. Disease progression depends upon interactions between lymphocytes and orbital fibroblasts. These cells engage in a cycle of reciprocal activation which produces the tissue characteristics of TED. Peroxisome proliferator-activated receptor-gamma (PPARgamma) may play divergent roles in this process, both attenuating and promoting disease progression. PPARgamma has anti-inflammatory activity, suggesting that it could interrupt intercellular communication. However, PPARgamma activation is also critical to adipogenesis, making it a potential culprit in the pathological fat accumulation associated with TED. This review explores the role of PPARgamma in TED, as it pertains to crosstalk between lymphocytes and fibroblasts and the development of therapeutics targeting cell-cell interactions mediated through this signaling pathway.

Potential role for bone marrow-derived fibrocytes in the orbital fibroblast heterogeneity associated with thyroid-associated ophthalmopathy

Fibroblast heterogeneity has been recognized for decades, but the basis for multiple phenotypes among these cells has been investigated only recently. More than 15 years ago, Bucalla and his colleagues described for the first time a population of fibroblast-like cells among circulating mononuclear blood cells. Subsequently these mesenchymal cells, termed fibrocytes, have been characterized and found to participate in normal and pathological tissue remodelling. In this review, I have attempted to present the evidence generated thus far suggesting that fibrocytes are participants in autoimmune diseases where tissues are injured and undergo remodelling. Aspects of their phenotype suggest that they are well suited to help orchestrate immune responses through mononuclear cell recruitment and their ability to produce inflammatory mediators and extracellular matrix molecules. These attributes also raise the possibility that they might be useful targets against which therapeutic agents might be aimed.

B Cell Abnormalities in Wegener’s Granulomatosis and Microscopic Polyangiitis: Role of CD25+-expressing B Cells

Objective.

The use of rituximab in vasculitis has increased interest in B cell biology. A subpopulation of B cells expressing CD25 shows antigen-presenting properties and may have regulatory functions. We assessed subpopulations of B cell maturation (Bm) and markers related to activity and antigen presentation, and related the findings to disease activity.

Methods.

Multiparameter flow cytometry was used to assess numbers and proportions of circulating lymphocytes from 34 patients with vasculitis (16 remission, 18 active) and 20 controls.

Results.

Active vasculitis samples showed decreased proportions of Bm1 (7.8% vs 11%; p = 0.041), Bm2’ (0.2% vs 0.7%; p = 0.002), and Bm3/Bm4 (0.1% vs 0.3%; p = 0.006), compared with controls; Bm2 cells were the most frequently occurring B cells but they were not significantly different in active vasculitis (74% vs 62%; p = 0.083). In patients with remission the proportion of CD25+ B cells was increased compared to controls (48% vs 29%, respectively; p = 0.006) and also compared to active vasculitis (23%; p = 0.006). The proportion of CD86+ B cells was also increased (31%) compared to active vasculitis (8%; p = 0.001), and to controls (6%; p = 0.0003). In multivariate analysis, Bm2’ cells and CD25+27– B cells were independently influencing the patient group.

Conclusion.

In active vasculitis, a lower proportion of Bm1 cells may indicate activated B cells. Patients in remission had higher proportions of CD25+ (α-chain of interleukin 2 receptor) and CD86+ (costimulatory molecule) B cells. We suggest that these B cells may have a regulatory role, or alternatively may result from previous treatment.

Rituximab treatment of patients with severe, corticosteroid-resistant thyroid-associated ophthalmopathy

PURPOSE

To study the effectiveness of anti-CD20 (rituximab [RTX]; Rituxan; Genentech, Inc., South San Francisco, CA) therapy in patients with severe, corticosteroid (CS)-resistant thyroid-associated ophthalmopathy (TAO).

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Six consecutive subjects with severe, progressive TAO unresponsive to CS.

METHODS

Electronic medical record review of consecutive patients receiving RTX during the previous 18 months. Responses to therapy were graded using standard clinical assessment and flow cytometric analysis of peripheral lymphocytes.

MAIN OUTCOME MEASURES

Clinical activity score (CAS), proptosis, strabismus, treatment side effects, and quantification of regulatory T cells.

RESULTS

Six patients were studied. Systemic CS failed to alter clinical activity in all patients (mean CAS+/-standard deviation, 5.3+/-1.0 before vs. 5.5+/-0.8 during therapy for 7.5+/-6.4 months; P = 1.0). However, after RTX treatment, CAS improved from 5.5+/-0.8 to 1.3+/-0.5 at 2 months after treatment (P<0.03) and remained quiescent in all patients (CAS, 0.7+/-0.8; P<0.0001) at a mean follow-up of 6.2+/-4.5 months. Vision improved bilaterally in all 4 patients with dysthyroid optic neuropathy (DON). None of the 6 patients experienced disease relapse after RTX infusion, and proptosis remained stable (Hertel measurement, 24+/-3.7 mm before therapy and 23.6+/-3.7 mm after therapy; P = 0.17). The abundance of T regulatory cells, assessed in 1 patient, increased within 1 week of RTX and remained elevated at 18 months of follow-up.

CONCLUSIONS

In progressive, CS-resistant TAO, rapid and sustained resolution of orbital inflammation and DON followed treatment with RTX.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.