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

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.

Efficiency and Safety of Tocilizumab for the Treatment of Thyroid Eye Disease: A Systematic Review

PURPOSE

To review existing literature concerning the effectiveness and safety of tocilizumab (TCZ) for managing thyroid eye disease.

METHODS

A systematic search was conducted across the PubMed and Embase databases to identify studies on TCZ therapy, from inception to May 2023. The search included the keywords "Graves orbitopathy," "thyroid ophthalmopathy," "thyroid eye disease," "thyroid-associated orbitopathy," "thyroid-associated ophthalmopathy," "Graves ophthalmopathy," "endocrine ophthalmopathy," and "Tocilizumab." Only articles written in English, Spanish, or French were considered.

RESULTS

Among the 1,013 articles initially screened, a total of 29 fulfilled the eligibility criteria and were selected. Most studies were case reports or case series, and only one randomized clinical trial was found. TCZ has been used mainly in glucocorticoid-resistant or relapsing cases, with a dosage ranging from 4 or 8 mg/kg every 4 weeks when intravenous or a weekly subcutaneous dose of 162 mg. Treatment duration is usually adjusted to the clinical response. TCZ is mostly effective in reducing inflammatory signs during the active phase of thyroid eye disease, with an improvement of at least 3 points in clinical activity score and an overall relapsing rate of 8.2%. Numerous studies have shown marked reductions in proptosis; although the only available randomized controlled trial reported a nonstatistically significant improvement 6 months after treatment, a recent meta-analysis indicated that TCZ seems to be the most effective treatment for reducing proptosis. No severe side effects related to intravenous or subcutaneous TCZ administration were reported.

DISCUSSION

Despite these promising findings, randomized clinical trials to directly compare the efficacy and safety of TCZ and other currently available therapeutic options are needed.

Decrease in Bone Formation and Bone Resorption during Intravenous Methylprednisolone Pulse Therapy in Patients with Graves' Orbitopathy

Background: Treatment with glucocorticoids (GCs) is associated with side effects. In contrast to the well-known negative impact on bone tissue exerted by oral GCs, few data are available regarding intravenous GCs. We investigated the influence of intravenous methylprednisolone (IVMP) on bone turnover markers (BTM): amino-terminal propeptide of type I procollagen (P1NP) and the C-terminal telopeptide of type I collagen (CTX), and on calcium metabolism parameters: 1,25-dihydroxyvitamin D (1,25(OH)2D), 25-hydroxyvitamin D (25(OH)D), calcium (Ca), phosphate (P), and intact parathormone (iPTH). Methods: In a prospective study, 23 consecutive subjects with Graves’ orbitopathy were included and treated with IVMP according to the European Group on Graves’ Orbitopathy recommendations. We evaluated effects on BTM occurring during the first 7 days after 0.5 g IVMP, and after the therapy with 12 IVMP pulses with a cumulative dose of 4.5 g. Results: We observed prompt but transient decrease of P1NP (p < 0.001) and the reduction of CTX (p = 0.02) after the first IVMP pulse. Following the full course of IVMP therapy, both P1NP and CTX were found decreased (p < 0.05 and p < 0.01, respectively). Conclusions: A single pulse of 0.5 g IVMP already decreases bone formation and resorption; however, this change is transient. The full therapy is associated with suppression of bone turnover.

Thinking inside the box: Current insights into targeting orbital tissue remodeling and inflammation in thyroid eye disease

Thyroid eye disease (TED) is an autoimmune disorder that manifests in the orbit. In TED, the connective tissue behind the eye becomes inflamed and remodels with increased fat accumulation and/or increased muscle and scar tissue. As orbital tissue expands, patients develop edema, exophthalmos, diplopia, and optic neuropathy. In severe cases vision loss may occur secondary to corneal scarring from exposure or optic nerve compression. Currently there is no cure for TED, and treatments are limited. A major breakthrough in TED therapy occurred with the FDA approval of teprotumumab, a monoclonal insulin-like growth factor 1 receptor (IGF1R) blocking antibody. Yet, teprotumumab therapy has limitations, including cost, infusion method of drug delivery, variable response, and relapse. We describe approaches to target orbital fibroblasts and the complex pathophysiology that underlies tissue remodeling and inflammation driving TED. Further advances in the elucidation of the mechanisms of TED may lead to prophylaxis based upon early biomarkers as well as lead to more convenient, less expensive therapies.

Therapy With Intravenous Methylprednisolone Pulses Is Associated With Loss of Bone Microarchitecture in Trabecular Bone Score -Assessment Among Patients With Moderate-to-Severe Graves' Orbitopathy: A Pilot Study

BACKGROUND

Therapy with intravenous glucocorticoids (GCs) is associated with various side effects, however, the impact on bone remains elusive. Trabecular bone score (TBS) is a diagnostic tool providing information on bone microarchitecture based on images obtained from dual-energy X-ray absorptiometry. We investigated the influence of the intravenous methylprednisolone (IVMP) pulse administration on TBS in patients with moderate-to-severe Graves' orbitopathy (GO).

METHODS

Fifteen patients with GO were treated with 12 IVMP pulses (6x0.5g, 6x0.25 g on a weekly schedule). They received supplementation with 2000 IU of vitamin D and 1.0 g of calcium throughout the study period. TBS was assessed at baseline and after last IVMP pulse. To determine the difference between values at baseline and after treatment the least significant change (LSC) methodology was used. We compared pre- and posttreatment mean TBS values.

RESULTS

We found a significant decrease of TBS in 5 out of 15 (33%) patients. Mean TBS value decreased becoming 2.4% lower than at baseline (p<0.05).

CONCLUSIONS

IVMP pulse therapy exerts negative effect on bone microarchitecture in TBS assessment. The analysis of the clinical risk factors for osteoporosis and the evaluation of bone mineral density and TBS should be considered before initiating IVMP therapy.

Relapse of Graves' disease following SARS-CoV-2 infection: A case report and brief literature review

The interaction between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and autoimmune thyroid disease is an emerging phenomenon. The present study describes the case of a 28-year-old female who experienced a relapse of Graves' disease following SARS-CoV-2 infection. She was biochemically euthyroid for 2 years prior to COVID-19 infection. However, she began experiencing palpitations, increased sweating and tremors of the hands 9 days after being diagnosed with COVID-19-related pneumonia. In addition to presenting this case, a comparison is made of this case to similar reports and the possible mechanisms underlying the association between SARS-CoV-2 and Graves' disease are discussed. One is a direct result of viral uptake by thyroid cells, while another is a result of the hyperinflammatory 'cytokine storm' and its effects on the hypothalamic-pituitary-thyroid axis and T-cell immunity.

[Autoantibodies, immunoglobulins and cytokine profile in patients with graves' disease and Graves' orbitopathy]

BACKGROUND

Graves' Orbitopathy (GO) - also known as Thyroid Eye Disease (TED) - is an autoimmune condition in the modern sense. It is closely associated with autoimmune thyroid diseases. Cytokine-mediated mechanisms play a critical part in immunopathogenesis of autoimmune thyroid diseases including GO. Investigating cytokine profiles as well as antibodies to tissue-specific antigens is essential for explaining GO pathogenesis and developing future therapeutic strategies.

AIMS

The study examines serum levels of cytokines, autoantibodies and immunoglobulins IgG and IgG4 as mediators of autoimmune inflammation in patients with GO and Graves' Disease (GD).

MATERIALS AND METHODS

The study included 52 patients (104 orbits) aged 25-70 years (mean age 48,8±12,3) in the active phase of GO and GD verified with the international diagnostic standards. These patients did not get any treatment for GO before. The control group consisted of 14 individuals (28 orbits) aged 30-68 years without known autoimmune disease.Serum levels of IgG, IgG4,TNFα, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-17A, IL-13, sIL-6R, sTNFα- RI и TNFα- R2 IL-2R, TGFβ1, TGF β3, antibodies to TSH-receptor, free T4, free T3 and TSH were measured. A diagnostic ultrasound exam of thyroid gland, multislice computed tomography (MSCT) / magnetic resonance imaging (MRI) of orbits were performed.

RESULTS

Mean duration of GO prior to being admitted to the centre was 8,8±1,5 months (range: 1 - 48 months). According to the degree of thyrotoxicosis compensation: 24 patients were clinically euthyroid, TSH 3,3±0,7 mU/L, free T4 11,9±0,59 pmol/L, free T3 3,97±0,1 pmol/L; 28 patients were considered to have subclinical thyrotoxicosis: TSH 0,03±0,01 mU/L, free T4 14,2±1,0 pmol/L, free T3 5,77±0,49 pmol/L. Serum levels of sTNFα-R2 (p=0,041, p≤0,05), sIL-2R (p=0,020, p≤0,05), TGFβ1 (p=0,000, p≤0,001) were significantly higher in patients with GO compared to the control group. Serum levels of sTNFRα2 (p=0,038, p&lt;0,05) and TGFβ1 (P=0,011, p≤0,05) were positively correlated with the duration of GO. The positive correlations between the serum level of sIL-6R (p=0,034, p≤0,05) and the severity of GO as well as between the serum level of sTNFα- R 1 (P=0,012, p≤0,05) and activity of GO were observed. 54% of patients had elevated concentration level of IgG4 in IgG ( &gt;5%).

CONCLUSION

High levels of soluble cytokine receptors sTNFα-R2 and sIL-2R and cytokine TGFβ1 in patients with long-standing untreated GO and GD being euthyroid or having subclinical thyrotoxicosis indicate activation of regulatory T cells aimed at suppressing autoimmune processes. High concentration level of IgG4 in IgG and cytokine TGFβ1 can determine the development of fibrotic changes in the orbital tissues. A decrease in the concentration of cytokine TGFβ1 can indicate an unfavorable course of the disease GO.

Current Understanding of the Progression and Management of Thyroid Associated Orbitopathy: A Systematic Review

Thyroid associated orbitopathy (TAO) is a common diagnosis encountered by ophthalmologists and oculoplastic surgeons. TAO has a varying clinical presentation that can include upper eyelid retraction, restrictive strabismus, proptosis, exposure keratopathy, and optic neuropathy. In this review, we discuss the most recent literature on and the current understanding of the pathophysiology of TAO. We also review available and potential future treatment options for the management of TAO.

Thyroid Eye Disease: How A Novel Therapy May Change The Treatment Paradigm

Thyroid eye disease (TED) is a complex, debilitating autoimmune disease that causes orbital inflammation and tissue remodeling, resulting in proptosis, diplopia, and in severe cases, loss of vision. TED can lead to facial disfigurement and severely impact patients’ quality of life. Although the course of TED was identified over 60 years ago, effective treatment options have proved to be challenging. Current treatments such as glucocorticoid therapy and orbital radiation focus on reducing orbital inflammation. However, these therapies fail to modify the disease outcomes, including proptosis and diplopia. Recent advances in the understanding of the molecular basis of TED have facilitated the development of targeted molecular therapies such as teprotumumab, an insulin-like growth factor-1 receptor inhibiting monoclonal antibody. In recent phase 2 and phase 3 randomized placebo-controlled trials, teprotumumab rapidly achieved improvement in clinical endpoints defining TED, including improved proptosis and diplopia. Dramatic improvement in clinical outcomes achieved after teprotumumab therapy during active TED are heretofore singular and comparable only to surgical therapies achieved during the inactive phase of TED. The advent of effective medical therapy can lead to a paradigm shift in the clinical management of TED. This review will provide an overview of TED, its epidemiology, insight into the molecular biology of the disease, clinical characteristics and diagnosis, and current and emerging treatment modalities.

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.

The involvement of T cell pathogenesis in thyroid-associated ophthalmopathy

Thyroid-associated ophthalmoapthy (TAO) is the most common orbital disease. As an autoimmune disorder, it is caused by self-reactive lymphocytes that escape immune tolerance, but the mechanism is not fully understood. The basic process of TAO is the infiltration of immune cells in orbital tissues, the activation of orbital fibroblasts (OFs), and the proliferation and differentiation of OFs and lymphocytes. Activated OFs secrete inflammatory regulators, growth factors, and chemokines, thereby maintaining and amplifying the immune responses. The interactions between OFs and lymphocytes lead to the expansion and the remodeling of the orbital tissues, presenting the clinical manifestations of TAO. This review will focus on the role of T cell subsets (Type 1, Type 2, Type 17 helper T cells, and regulatory T cells) in the pathogenesis of TAO. However, we still need further studies to unravel the pathogenesis, to confirm current hypotheses, and to provide novel ideas for appropriate clinical treatment of TAO.

The levels of 12 cytokines and growth factors in tears: hyperthyreosis vs euthyreosis

PURPOSE

Simultaneous analyses of the contents and ratios of 12 cytokines and growth factors in single samples of human tears were performed, and the results were compared between a group of healthy subjects and a group of patients with Graves' hyperthyreosis (GH) without thyroid-associated orbitopathy (TAO).

METHODS

Determinations and concentration measurements of interleukins (IL-2, IL4, IL-6, IL-8, IL-10, IL-1α, and IL-1β) interferon (IFN-γ), tumor necrosis factor (TNF-α), monocyte chemoattractant protein (MCP-1), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) were performed with single tear samples from 21 patients with hyperthyreosis and 22 healthy subjects. The analyses were performed using a Randox microchip with an Evidence Biochip Array Analyzer.

RESULTS

We found significant differences between the healthy donor group and the hyperthyreosis group in the levels of IL-6, IL-10, VEGF, IL-1α, and MCP-1. The concentration of IL-6 was considerably higher in the hyperthyreosis group, IL-10 was higher in the healthy donor group, and VEGF and MPC-1 were higher in the hyperthyreosis group. The IL-8 and IFN-γ levels were higher in the hyperthyreosis group. The ratios of all of the cytokines to anti-inflammatory IL-10 were significantly elevated in the hyperthyreosis group.

CONCLUSION

There are clear differences in the levels of cytokines and growth factors in the tears of healthy subjects and patients with GH without TAO. Tear cytokine changes and related dysfunctional tear syndrome (DTS) could be an early sign of occult TAO in Graves' hyperthyreosis patients.

Update on thyroid-associated Ophthalmopathy with a special emphasis on the ocular surface

Thyroid-associated ophthalmopathy (TAO) is a condition associated with a wide spectrum of ocular changes, usually in the context of the autoimmune syndrome, Graves’ disease. In this topical review, we attempted to provide a roadmap of the recent advances in current understanding the pathogenesis of TAO, important aspects of its clinical presentation, its impact on the ocular surface, describe the tissue abnormalities frequently encountered, and describe how TAO is managed today. We also briefly review how increased understanding of the disease should culminate in improved therapies for patients with this vexing condition.

Orbital Radiation Therapy in Thyroid Eye Disease

PURPOSE

To review the current literature summarizing the state of knowledge on the use of orbital radiation therapy (ORT) in thyroid eye disease.

METHODS

A systematic review and analysis of the literature were performed. MEDLINE/PubMed, Cochrane Library databases, SCOPUS, and recent relevant journal articles were searched.

RESULTS

Thyroid eye disease is an autoimmune disorder that has the propensity to affect multiple orbital tissues and can cause permanent vision loss. In moderate to severe disease, treatment may be warranted and can include multiple therapeutic modalities. Orbital radiation therapy is frequently used in this setting and may act to break the inflammatory cycle of glycosaminoglycan production and deposition. There has been a wealth of data regarding the effectiveness of ORT in thyroid eye disease resulting in the publication of treatment algorithms and management guidelines; however, there continues to be a lack of conformity among experts on the exact role of ORT in thyroid eye disease.

CONCLUSION

The multiple different thyroid eye disease classification schemes and the concurrent use of other therapeutic modalities challenge the interpretation of studies evaluating the effectiveness of thyroid eye disease. Despite these limitations, the current literature indicates that ORT is generally safe and well tolerated. Orbital radiation therapy may have a modest effect on motility and proptosis early in the disease process. It is unclear whether ORT leads to improved quality of life. There are some data to support the use of ORT to prevent compressive optic neuropathy.

IL-17A Exacerbates Fibrosis by Promoting the Proinflammatory and Profibrotic Function of Orbital Fibroblasts in TAO

CONTEXT

The development of thyroid-associated ophthalmopathy (TAO) is associated with self-immune dysfunction. Recent findings in TAO and Graves' disease indicate that IL-17A may also be involved in the autoimmunity of TAO.

OBJECTIVE

We sought to investigate the pathogenic function of IL-17A-producing T cells in TAO.

DESIGN/SETTING/PARTICIPANTS

Blood samples and orbital fibroblasts (OFs) were collected from TAO patients and healthy subjects.

MAIN OUTCOME MEASURES

Flow cytometry, real-time PCR, cytokine-specific ELISA, and Western blotting were performed.

RESULTS

Here, we showed a significantly higher proportion of IL-17A-producing T cells in TAO patients and the recruitment of both CD4(+) and CD8(+) T cells in TAO orbits. TAO orbital tissues expressed more IL-17A receptor, IL-17A, and its related cytokines, with severe fibrotic change compared with normal controls. Furthermore, we validated that IL-17A could enhance the proinflammatory function of OFs and stimulate the production of extracellular matrix proteins in OFs but not eyelid fibroblasts. The mechanisms involved in this enhancement mainly relied on MAPK activation. Finally, we observed that the deubiquitinase inhibitor vialinin A could down-regulate retinoic acid receptor-related orphan receptor-γt expression and decrease IL-17A level in TAO patients.

CONCLUSION

Our observations illustrate the potential pathogenic role of IL-17A-producing T cells in the inflammatory response and fibrosis of TAO. The effect of vialinin A on the reduction of retinoic acid receptor-related orphan receptor-γt level implicates its potential role as a novel therapeutic agent for TAO and other autoimmune disorders in the future.

T regulatory (Treg) and T helper 17 (Th17) lymphocytes in thyroid autoimmunity

Different immune cell subsets have a relevant role in the pathogenesis of and tissue damage seen in autoimmune thyroid diseases (AITD), including T regulatory (Treg) lymphocytes and T helper (Th) 17 cells. There are several types of CD4+ Treg cells (Foxp3+, CD69+, Tr1), which are able to prevent the appearance of autoimmune diseases, down regulating the immune response and the inflammatory phenomenon. However, despite their presence in peripheral blood and thyroid tissue from patients with AITD, these cells are apparently unable to put down the autoimmune process. Moreover, many reports indicate the involvement of Th17 cells in chronic inflammatory diseases, including AITD. Nevertheless, it is now evident that these lymphocytes show a remarkable plasticity, giving rise to anti-inflammatory (including Treg lymphocytes) and pro-inflammatory cell subtypes. Nowadays, both Treg and Th17 cells must be considered as key elements in the pathogenesis of AITD as well as plausible potential targets for the next generation of therapeutic options of this condition.

Genetic Associations of Interleukin-related Genes with Graves' Ophthalmopathy: a Systematic Review and Meta-analysis

Graves’ ophthalmopathy (GO) is the commonest extra-thyroidal manifestation of Graves’ disease (GD). Associations between interleukin-related (IL) gene polymorphisms and GO have been reported in different populations. We aim to confirm such associations by conducting a meta-analysis. Totally 382 publications were retrieved in MEDLINE and EMBASE up to 25/2/2015. After removing the duplicates and assessing the studies, we retrieved 16 studies that met the selection criteria for meta-analysis, involving 12 polymorphisms in 8 IL-related genes, and 1650 GO cases and 2909 GD controls. The summary odds ratio (OR) and 95% confidence intervals (CI) were estimated. We found one polymorphism in IL1A (rs1800587, c.-889C>T) showing a suggestive association with GO in the meta-analysis (allelic model [T vs. C]: OR = 1.62, 95% CI: 1.00–2.62, P = 0.050, I² = 53.7%; recessive model [TT vs. TC + CC]: OR = 2.39, 95% CI: 1.07–5.37, P = 0.039, I² = 23.6%; heterozygous model [TC vs. CC]: OR = 1.52, 95% CI: 1.04–2.22, P = 0.034, I² = 37.0%). No association with GO was detected for the other 7 genes (IL1B, IL1RA, IL4, IL6, IL12B, IL13 and IL23R). Our results thus indicate that IL1A is likely to be a genetic biomarker for GO. Further studies with larger sample sizes are warranted to confirm the associations of IL1A and other IL-related genes with GO.