Novel Approaches for Immunosuppression in Graves' Hyperthyroidism and Associated Orbitopathy

Azathioprine as an adjuvant therapy in severe Graves' disease: a randomized controlled open-label clinical trial

Introduction

Azathioprine (AZA) interferes with the activation of T and B lymphocytes, which are the main cells involved in the pathogenesis of Graves' disease (GD). The aim of this study was to investigate the effectiveness of AZA as an adjuvant therapy to antithyroid drugs (ATDs) for moderate and severe GD. In addition, we conducted an incremental cost-effectiveness analysis of AZA to determine its cost-effectiveness.

Methods

We conducted a randomized, open-label, and parallel-group clinical trial. We randomized untreated hyperthyroid patients with severe GD into three groups. All patients received 45-mg carbimazole (CM) as the starting dose and propranolol 40-120 mg daily. The first group (AZA1) received an additional 1 mg/kg/day AZA, the second group (AZA2) received an additional 2 mg/kg/day AZA, and the third group (control group) received only CM and propranolol. We measured thyroid-stimulating hormone (TSH) and TSH-receptor antibody (TRAb) levels at baseline and every 3 months, while free triiodothyronine (FT3) and free thyroxine (FT4) levels were measured at the time of diagnosis, 1 month after initiation of therapy, and every 3 months thereafter until 2 years after remission. Thyroid volume (TV) was assessed by ultrasound at baseline and 1 year after remission.

Results

A total of 270 patients were included in this trial. By the end of follow-up, there was higher remission rate in the AZA1 and AZA2 groups compared with controls (87.5% and 87.5% vs. 33.4%, p = 0.002). Throughout the course of follow-up, FT3, FT4, TSH, and TRAb were significantly different between the AZA groups and the control group, but there was no significant difference regarding TV. The decline in the concentrations of FT4, FT3, and TRAb was significantly faster in the AZA2 group than in the AZA1 group. The relapse rate during the 12-month follow-up was insignificantly higher in the control group than in either the AZA1 or AZA2 group (10, 4.4, and 4.4%, p = 0.05, respectively). The median relapse time was 18 months for the control group and 24 months for the AZA1 and AZA2 groups. The incremental cost-effectiveness ratio for the AZA group compared with the conventional group was 27,220.4 Egyptian pounds per remission reduction for patients using AZA as an adjuvant for ATDs.

Conclusion

AZA could be a novel, affordable, cost-effective, and safe drug offering hope for patients with GD to achieve early and long-lasting medical remission.

Trial registry

The trial is registered at the Pan African Clinical Trial Registry (Registration number: PACTR201912487382180).

Antigen-specific immunotherapy to restore antigen-specific tolerance in Type 1 diabetes and Graves' disease

Type 1 diabetes and Graves' disease are chronic autoimmune conditions, characterized by a dysregulated immune response. In Type 1 diabetes, there is beta cell destruction and subsequent insulin deficiency whereas in Graves' disease, there is unregulated excessive thyroid hormone production. Both diseases result in significant psychosocial, physiological, and emotional burden. There are associated risks of diabetic ketoacidosis and hypoglycaemia in Type 1 diabetes and risks of thyrotoxicosis and orbitopathy in Graves' disease. Advances in the understanding of the immunopathogenesis and response to immunotherapy in Type 1 diabetes and Graves' disease have facilitated the introduction of targeted therapies to induce self-tolerance, and subsequently, the potential to induce long-term remission if effective. We explore current research surrounding the use of antigen-specific immunotherapies, with a focus on human studies, in Type 1 diabetes and Graves' disease including protein-based, peptide-based, dendritic-cell-based, and nanoparticle-based immunotherapies, including discussion of factors to be considered when translating immunotherapies to clinical practice.

Pathophysiology of thyroid-associated orbitopathy

Thyroid-associated orbitopathy, the most common extrathyroidal manifestation of Graves' disease, is characterized by orbital inflammatory infiltration and activation of orbital fibroblasts, which mediates de novo adipogenesis, excessive production of hyaluronan, myofibroblast differentiation and ultimately tissue fibrosis. Interactions among T cells, B cells, and orbital fibroblasts result in their activation and perpetuation of orbital inflammation as well as tissue remodelling. T helper 17 cells belong to a newly identified pathogenic CD4+ T cell subset which possesses prominent pro-inflammatory and profibrotic capabilities. Thyroid stimulating hormone receptor/insulin-like growth factor-1 receptor crosstalk and the downstream signalling pathways of both receptors represent the major mechanisms leading to activation of orbital fibroblasts. Thyroid stimulating hormone receptor autoantibody is the disease specific biomarker of great clinical relevance and utility. There is growing evidence that oxidative stress, gut microbiome and epigenetics also play a role in the pathogenesis and their manipulation may represent novel therapeutic strategies.

Traditional Chinese medicine in thyroid-associated orbitopathy

PURPOSE

Orbital fibroblasts (OF) are considered the central target cells in the pathogenesis of thyroid-associated orbitopathy (TAO), which comprises orbital inflammation, orbital tissue edema, adipogenesis, fibrosis, oxidative stress and autophagy. Certain active ingredients of traditional Chinese medicine (TCM) demonstrated inhibition of TAO-OF in pre-clinical studies and they could be translated into novel therapeutic strategies.

METHODS

The pertinent and current literature of pre-clinical studies on TAO investigating the effects of active ingredients of TCM was reviewed using the NCBI PubMed database.

RESULTS

Eleven TCM compounds demonstrated inhibition of TAO-OF in-vitro and three of them (polydatin, curcumin, and gypenosides) resulted in improvement in TAO mouse models. Tanshinone IIA reduced inflammation, oxidative stress and adipogenesis. Both resveratrol and its precursor polydatin displayed anti-oxidative and anti-adipogenic properties. Celastrol inhibited inflammation and triptolide prevented TAO-OF activation, while icariin inhibited autophagy and adipogenesis. Astragaloside IV reduced inflammation via suppressing autophagy and inhibited fat accumulation as well as collagen deposition. Curcumin displayed multiple actions, including anti-inflammatory, anti-oxidative, anti-adipogenic, anti-fibrotic and anti-angiogenic effects via multiple signaling pathways. Gypenosides reduced inflammation, oxidative stress, tissue fibrosis, as well as oxidative stress mediated autophagy and apoptosis. Dihydroartemisinin inhibited OF proliferation, inflammation, hyaluronan (HA) production, and fibrosis. Berberine attenuated inflammation, HA production, adipogenesis, and fibrosis.

CONCLUSIONS

Clinical trials of different phases with adequate power and sound methodology will be warranted to evaluate the appropriate dosage, safety and efficacy of these compounds in the management of TAO.

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.

Current concepts regarding Graves' orbitopathy

Graves' orbitopathy (GO) is an orbital autoimmune disorder and the main extrathyroidal manifestation of Graves' disease, the most common cause of hyperthyroidism. GO affects about 30% of Graves' patients, although fewer than 10% have severe forms requiring immunosuppressive treatments. Management of GO requires a multidisciplinary approach. Medical therapies for active moderate-to-severe forms of GO (traditionally, high-dose glucocorticoids) often provide unsatisfactory results, and subsequently surgeries are often needed to cure residual manifestations. The aim of this review is to provide an updated overview of current concepts regarding the epidemiology, pathogenesis, assessment, and treatment of GO, and to present emerging targeted therapies and therapeutic perspectives. Original articles, clinical trials, systematic reviews, and meta-analyses from 1980 to 2021 were searched using the following terms: Graves' disease, Graves' orbitopathy, thyroid eye disease, glucocorticoids, orbital radiotherapy, rituximab, cyclosporine, azathioprine, teprotumumab, TSH-receptor antibody, smoking, hyperthyroidism, hypothyroidism, thyroidectomy, radioactive iodine, and antithyroid drugs. Recent studies suggest a secular trend toward a milder phenotype of GO. Standardized assessment at a thyroid eye clinic allows for a better general management plan. Treatment of active moderate-to-severe forms of GO still relies in most cases on high-dose systemic-mainly intravenous-glucocorticoids as monotherapy or in combination with other therapies-such as mycophenolate, cyclosporine, azathioprine, or orbital radiotherapy-but novel biological agents-including teprotumumab, rituximab, and tocilizumab-have achieved encouraging results.

Efficacy and safety of mycophenolate mofetil in the treatment of moderate to severe Graves' orbitopathy: a meta-analysis

The role of mycophenolate mofetil (MMF) in the treatment of Graves’ orbitopathy (GO) has attracted much attention. This study is to evaluate the benefit and safety of MMF in moderate-to-severe GO. A meta-analysis of clinical control trials comparing MMF (with or without glucocorticoid (GC)) for the treatment of GO with GC was conducted. We searched the databases, including PubMed, EMBASE, the Cochrane Library, Web of Science, Wanfang, and China National Knowledge Infrastructure (CNKI), for articles published up to 15 June 2022. The primary outcome is referred to the improvement in overall response, and secondary outcomes included the change in clinical activity score (CAS) and adverse events (AEs). Of the 289 articles initially searched, 6 studies were finally eligible for inclusion. The results showed that MMF (with or without GC) was superior to GC in the treatment of GO (OR 3.34, 95% CI 2.17–5.14; p < 0.00001). Subgroup analyses also showed that MMF monotherapy was more effective than GC (OR 4.46, 95% CI 2.52–7.87; p < 0.00001). Compared to methylprednisolone (MP) monotherapy, a combination of MP and MMF was more effective. CAS decreased even more significantly (WMD 0.29, 95% CI 0.10–0.48; p = 0.002) and fewer AEs occurred (OR 0.2, 95% CI 0.06–0.72; p = 0.01) in patients receiving MMF. The pooled data suggested that MMF treatment in GO might be promising. Compared with GC therapy, MMF is safer and more effective. However, more large-sample and high-quality studies targeting MMF use in GO patients and long-term surveillance of prognosis are urgently needed.

Drug safety in thyroid eye disease - a systematic review

INTRODUCTION

The autoimmune-induced thyroid eye disease (TED) is a frequent extrathyroidal manifestation of Graves' disease and less frequently of Hashimoto's thyroiditis. Pathognomonic clinical signs, i.e. exophthalmos, double vision, and inflammation of the orbital tissue cause physical, ophthalmic, and socio-psychological limitations.

AREAS COVERED

PubMed and MeSH database were searched for specific guidelines, randomized controlled trials, prospective clinical studies, systematic reviews and meta-analyses pertaining to the safety profile of currently administered immunosuppressive agents for the treatment of TED. Occurred adverse events (AE), severe AE (SAE), side effects (SE), and severe SE (SSE) were classified according to the standardized medical dictionary for regulatory activities (MedDRA).

EXPERT OPINION

This novel systematic analysis offers an overview of potential AE, SAE and SE for currently recommended immunosuppressive drugs for the treatment of TED. Non-specific, anti-inflammatory drugs and more specific, targeted biologicals are treatment options for active and severe TED. Critical evaluation of the pertinent literature confirms an evidence-based, beneficial efficacy/risk ratio of the current first-line and second-line treatment recommendations endorsed by the European Society of Endocrinology. However, further large, well-conceived trials are mandatory to enhance our knowledge and experience with novel specific small molecules and/or monoclonal antibodies targeting the key autoantigens in TED.

A cyclic peptide significantly improves thyroid function, thyrotropin-receptor antibodies and orbital mucine /collagen content in a long-term Graves' disease mouse model

BACKGROUND

BALB/c mice which received long-term immunizations of adenovirus (Ad) expressing thyrotropin receptor A-subunits (TSHR) developed stable Graves' disease (GD). TSHR-derived cyclic peptide 19 (P19) was identified as effective therapy in this model.

METHODS

In Ad-TSHR mice, we investigated shorter disease intervals up to 4 months for histological alterations of the orbits, fine tuning of anti-TSHR antibodies (Ab) and free thyroxine (fT4) hormone levels by using novel detection methods in an independent laboratory. Therapy (0.3 mg/kg P19 or vehicle) was given intravenously after the fourth Ad-TSHR immunization (week 11) and continued until week 19.

RESULTS

Thyrotropin binding inhibitory immunoglobulins (TBII, bridge immunoassay), blocking (TBAb) and stimulating (TSAb) TSHR-Ab (both cell-based bioassays) and serum levels of fT4 were significantly elevated at week 11 in Ad-TSHR-immunized mice versus none in control mice. For the first time, TSAb, TBAb, and thyroperoxidase-Ab were detected in 17 of 19, 12/19 and 6/19 Ad-TSHR immunized mice, respectively at week 21. Also, for the first time, this study showed that P19 treatment markedly reduced serum TBII (p < 0.0001), serum fT4 (p = 0.02), and acidic mucins and collagen content in the orbital tissue of Ad-TSHR-immunized mice.

CONCLUSION

P19 significantly improved thyroid function, confirming previous results in an independent second laboratory. A relevant shift of anti-TSHR antibody subpopulations in response to P19 therapy may help explain its immunological effects. Moreover, P19 exerted a beneficial effect on mucine and collagen content of orbital tissue. Hence, P19 offers a potential novel therapeutic approach for GD and associated orbitopathy.

Graves' Disease and Rheumatoid Arthritis: A Bidirectional Mendelian Randomization Study

BACKGROUND

The frequent coexistence of Graves' disease (GD) and rheumatoid arthritis (RA) has been cited and discussed in observational studies, but it remains a question as to whether there is a causal effect between the two diseases.

METHODS

We retrieved genome-wide association study (GWAS) summary data of GD and RA from BioBank Japan (BBJ). Single nucleotide polymorphisms (SNPs) associated with diseases of interest were selected as instrumental variables (IVs) at a genome-wide significance level (P < 5.0 × 10^-8). The random-effects inverse variance weighted method (IVW) was used to combine the causal effect of IVs. The horizontal pleiotropy effect was analyzed by MR-Egger and weighted median method sensitivity test. A leave-one-out analysis was conducted to avoid bias caused by a single SNP. The statistical power of our MR result was calculated according to Brion's method.

RESULTS

Our study discovered a bidirectional causal effect between GD and RA. The presence of RA may increase the risk of GD by 39% (OR 1.39, 95% CI 1.10-1.75, P = 0.007). Similarly, the existence of GD may increase the risk of RA by 30% (OR 1.30, 95% CI 0.94-1.80, P = 0.112). Our study provides 100% power to detect the causal effect of RA on GD risk, and vice versa.

CONCLUSIONS

We found a bidirectional causal effect between GD and RA in an Asian population. Our study supported the clinical need for screening GD in RA patients, and vice versa. The potential benefit of sound management of RA in GD patients (or GD in RA patients) merits excellent attention. Moreover, novel satisfactory medicine for RA may be applicable to GD and such potential is worthy of further investigation.