Immunoglobulin G from patients with Graves' disease induces interleukin-16 and RANTES expression in cultured human thyrocytes: a putative mechanism for T-cell infiltration of the thyroid in autoimmune disease

Long-term outcome of Graves' orbitopathy following treatment with sirolimus

OBJECTIVES

Sirolimus was found to be associated with a better outcome of Graves' orbitopathy (GO) at 24 weeks compared to methylprednisolone. We conducted a retrospective study to investigate its efficacy and safety over a longer period.

METHODS

Data from 40 consecutive patients with moderate-to-severe, active GO, 20 treated with sirolimus and 20 with methylprednisolone, were collected.

PRIMARY OUTCOME

overall outcome (composite evaluation) of GO at 48 weeks.

SECONDARY OUTCOMES

(1) GO outcome at 24 weeks, and, at 24 and 48 weeks: (2) outcome of single eye features; (3) quality of life (GO-QoL); (4) TSH-receptor antibodies; (5) GO relapse at 48 weeks; (6) adverse events.

RESULTS

The overall GO outcome at 48 weeks did not differ between the two groups (responders: 55% vs 55%). At 24 weeks, prevalence of responders was greater in sirolimus group (65% vs 25%; P = 0.01). A reduction ≥ 1 point in clinical activity score (CAS) was more frequent in sirolimus patients at 24 (85% vs 40%; P = 0.005) and 48 weeks (75% vs 60%; P = 0.03). The proportion of GO-QoL responders (appearance subscale) at 24 weeks was greater in sirolimus group (62.5% vs 26.3%; P = 0.03). No difference was observed for the remaining outcome measures.

CONCLUSIONS

Treatment with sirolimus is followed by a greater overall response of GO compared with methylprednisolone at 24 weeks, but not at 48 weeks, when only CAS is affected. A more prolonged period of treatment may be required for a better outcome to be observed over a longer period.

Causal effects of autoimmune diseases on temporomandibular disorders and the mediating pathways: a Mendelian randomization study

Background

The role of autoimmune diseases (ADs) in temporomandibular disorders (TMDs) has been emphasized in observational studies. However, whether the causation exists is unclear, and controversy remains about which specific disorder is destructive in TMDs. This Mendelian randomization (MR) study aims to estimate the causal effect of common ADs on TMDs.

Methods

Genetic data from published genome-wide association studies for fourteen common ADs, specifically multiple sclerosis (MS, N = 15,283), ankylosing spondylitis (AS, N = 22,647), asthma (N = 408,422), celiac disease (N = 15,283), Graves' disease (N = 458,620), Hashimoto thyroiditis (N = 395,640), primary biliary cirrhosis (PBC, N = 11,375), primary sclerosing cholangitis (PSC, N = 14,890), psoriasis vulgaris (N = 483,174), rheumatoid arthritis (RA, N = 417,256), systemic lupus erythematosus (SLE, N = 23,210), Type 1 diabetes (T1D, N = 520,580), inflammatory bowel disease (IBD, N = 34,652), and Sjogren's syndrome (SS, N = 407,746) were collected. Additionally, the latest summary-level data for TMDs (N = 228,812) were extracted from the FinnGen database. The overall effects of each immune traits were assessed via inverse-variance weighted (IVW), weighted median, and MR-Egger methods, and performed extensive sensitivity analyses. Finally, 731 immune cell phenotypes (N = 3,757) were analyzed for their mediating role in the significant causality.

Results

Univariable MR analyses revealed that genetically predicted RA (IVW OR: 1.12, 95% CI: 1.05-1.19, p < 0.001) and MS (IVW OR: 1.06, 95% CI: 1.03-1.10, p = 0.001) were associated with increased risk of TMDs. Two out of 731 immune cell phenotypes were identified as causal mediators in the associations of RA with TMDs, including "CD25++ CD8+ T cell % CD8+ T cell" (mediation proportion: 6.2%) and "CD3 on activated CD4 regulatory T cell" (5.4%). Additionally, "CD127 on granulocyte" mediated 10.6% of the total effect of MS on TMDs. No reverse directions, heterogeneity, and pleiotropy were detected in the analyses (p > 0.05).

Conclusion

This MR study provides new evidence regarding the causal impact of genetic predisposition to RA or MS on the increased risk of TMDs, potentially mediated by the modulation of immune cells. These findings highlight the importance for clinicians to pay more attention to patients with RA or MS when consulting for temporomandibular discomfort. The mediating role of specific immune cells is proposed but needs further investigation.

Potential role of IGF-1R in the interaction between orbital fibroblasts and B lymphocytes: an implication for B lymphocyte depletion in the active inflammatory phase of thyroid-associated ophthalmopathy

BACKGROUND

Thyroid eye disease (TED) is an inflammatory process involving lymphocyte-mediated immune response and orbital tissue damage. The anti-insulin-like growth factor-1 receptor (IGF-1R) antibodies produced by B lymphocytes are involved in the activation of orbital fibroblasts and the inflammatory process of orbital tissue damage in TED. The purpose of this study was to explore the role of IGF-1R in the mechanistic connection between orbital fibroblasts and B lymphocytes in TED.

METHODS

Orbital fibroblasts sampled from orbital connective tissues and peripheral B lymphocytes isolated from peripheral blood, which were obtained from 15 patients with TED and 15 control patients, were co-cultured at a ratio of 1:20. The level of IGF-1R expression in orbital fibroblasts was evaluated by flow cytometry and confocal microscopy. Transient B lymphocyte depletion was induced with anti-CD20 monoclonal antibody rituximab, while the IGF-1R pathway was blocked by the IGF-1R binding protein. The expression levels of interleukin-6 (IL-6) and regulated upon activation, normal T cell expressed and secreted (RANTES) in the co-culture model were quantified via ELISA.

RESULTS

IGF-1R expression was significantly elevated in TED orbital fibroblasts compared to that of controls. A 24-h co-culture of orbital fibroblasts with peripheral B lymphocytes induced elevated expression levels of IL-6 and RANTES in each group (TED patients and controls), with the highest levels occurring in TED patients (T + T group). Rituximab and IGF-1R binding protein significantly inhibited increased levels of IL-6 and RANTES in the co-culture model of TED patients.

CONCLUSIONS

IGF-1R may mediate interaction between orbital fibroblasts and peripheral B lymphocytes; thus, blocking IGF-1R may reduce the local inflammatory response in TED. Rituximab-mediated B lymphocyte depletion played a role in inhibiting inflammatory responses in this in vitro co-culture model, providing a theoretical basis for the clinical application of anti-CD20 monoclonal antibodies in TED.

Sirolimus as a second-line treatment for Graves' orbitopathy

OBJECTIVES

A beneficial effect of sirolimus in Graves' orbitopathy (GO) was reported, suggesting a possible use in clinical practice. We conducted an observational, single-centre, no-profit, clinical study to investigate the efficacy of sirolimus as a second-line treatment for moderate-to-severe, active GO compared with methylprednisolone.

METHODS

Data from consecutive patients given sirolimus (2 mg orally on first day, followed by 0.5 mg/day for 12 weeks) or methylprednisolone [500 mg iv/weekly (6 weeks), 250 mg/weekly (6 weeks)] as a second-line treatment were collected and compared.

PRIMARY OBJECTIVE

overall GO outcome at 24 weeks, based on a composite evaluation. Secondary objectives at 24 weeks: (1) improvement in quality of life, evaluated using a specific uestionnaire (GO-QoL); (2) reduction in proptosis; (3) reduction in the clinical activity score (CAS); (4) improvement of eye ductions; and (5) reduction in eyelid aperture.

RESULTS

Data from 30 patients (15 per group) treated between January 15, 2020, and June 15, 2021, were analysed. Proportion of GO responders (primary outcome) at 24 weeks was significantly greater in sirolimus group compared with methylprednisolone group (86.6% vs 26.6%; OR: 17.8; 95% CI from 2.7 to 116.8; P = 0.0026). GO-quality of life (GO-QoL) score was greater in sirolimus group. Proportion of proptosis responders was greater in sirolimus group, as well as proportion of clinical activity score (CAS) responders. No serious adverse events were observed, with no differences between groups.

CONCLUSIONS

Sirolimus seems to be an effective second-line treatment for GO. Further randomized clinical trials are needed to confirm our observations.

Teprotumumab (Tepezza): from the discovery and development of medicines to USFDA approval for active thyroid eye disease (TED) treatment

Teprotumumab (TPT) is a type I insulin-like growth factor receptor inhibitor, marketed as Tepezza; recently USFDA approved it for the treatment of thyroid eye disease (thyroid-associated ophthalmopathy (TAO), Graves ophthalmopathy/orbitopathy) in the USA. It is a monoclonal antibody although it was initially developed in collaboration with Genmab and Roche for the treatment of the tumour, but later it was investigated by River Vision Development Corporation and Horizon Therapeutics for its ophthalmic use. The drug has been designated as an orphan drug, breakthrough designation and fast-track designation. This review summarizes the milestones in the research and development including ongoing, clinical trial of TPT till now, foremost to this primary approval for thyroid-associated ophthalmopathy (TAO).

Insulin-Like Growth Factor Pathway and the Thyroid

The insulin-like growth factor (IGF) pathway comprises two activating ligands (IGF-I and IGF-II), two cell-surface receptors (IGF-IR and IGF-IIR), six IGF binding proteins (IGFBP) and nine IGFBP related proteins. IGF-I and the IGF-IR share substantial structural and functional similarities to those of insulin and its receptor. IGF-I plays important regulatory roles in the development, growth, and function of many human tissues. Its pathway intersects with those mediating the actions of many cytokines, growth factors and hormones. Among these, IGFs impact the thyroid and the hormones that it generates. Further, thyroid hormones and thyrotropin (TSH) can influence the biological effects of growth hormone and IGF-I on target tissues. The consequences of this two-way interplay can be far-reaching on many metabolic and immunologic processes. Specifically, IGF-I supports normal function, volume and hormone synthesis of the thyroid gland. Some of these effects are mediated through enhancement of sensitivity to the actions of TSH while others may be independent of pituitary function. IGF-I also participates in pathological conditions of the thyroid, including benign enlargement and tumorigenesis, such as those occurring in acromegaly. With regard to Graves' disease (GD) and the periocular process frequently associated with it, namely thyroid-associated ophthalmopathy (TAO), IGF-IR has been found overexpressed in orbital connective tissues, T and B cells in GD and TAO. Autoantibodies of the IgG class are generated in patients with GD that bind to IGF-IR and initiate the signaling from the TSHR/IGF-IR physical and functional protein complex. Further, inhibition of IGF-IR with monoclonal antibody inhibitors can attenuate signaling from either TSHR or IGF-IR. Based on those findings, the development of teprotumumab, a β-arrestin biased agonist as a therapeutic has resulted in the first medication approved by the US FDA for the treatment of TAO. Teprotumumab is now in wide clinical use in North America.

Teprotumumab Treatment for Thyroid-Associated Ophthalmopathy

BACKGROUND

Thyroid-associated ophthalmopathy (TAO), an autoimmune process affecting the tissues surrounding the eye, most commonly develops in individuals with Graves' disease. It is disfiguring, can cause vision loss, and dramatically lessens the quality of life in patients. There has been an absence of approved medical therapies for TAO with proven effectiveness and safety in multicenter, placebo-controlled, and adequately powered clinical trials.

SUMMARY

The following is a brief overview of the rationale for developing a monoclonal antibody inhibitor of the insulin-like growth factor-I receptor into a treatment for TAO. This area of fundamental research has yielded an effective and safe medication, namely teprotumumab, based on two multicenter, placebo-controlled trials. Teprotumumab, marketed as Tepezza, has been approved recently by the US Food and Drug Administration for the treatment of TAO. Given its remarkable effectiveness, Tepezza is poised to become the first-line standard of care for TAO.

KEY MESSAGES

Introduction of Tepezza into our armamentarium of therapeutic strategies for TAO represents a paradigm shift in the management of the disease. I proffer that the drug will replace glucocorticoids as a first-line treatment for TAO.

Teprotumumab as a Novel Therapy for Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) has remained a vexing and poorly managed autoimmune component of Graves' disease where the tissues surrounding the eye and in the upper face become inflamed and undergo remodeling. This leads to substantial facial disfigurement while in its most severe forms, TAO can threaten eye sight. In this brief paper, I review some of the background investigation that has led to development of teprotumumab as the first and only US FDA approved medical therapy for TAO. This novel treatment was predicated on recognition that the insulin-like growth factor I receptor plays an important role in the pathogenesis of TAO. It is possible that a similar involvement of that receptor in other autoimmune disease may lead to additional indications for this and alternative insulin-like growth factor I receptor-inhibiting strategies.

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.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Effectiveness and Mechanism of Preoperative Lugol Solution for Reducing Thyroid Blood Flow in Patients with Euthyroid Graves' Disease

BACKGROUND

To reduce intraoperative and postoperative complications, using Lugol solution to preoperatively prepare patients with Graves' disease has (1) rapidly reduced the severity of thyrotoxicosis and (2) reduced the vascularity of the thyroid gland. The vascularity reduction normally accompanies reducing the severity of thyrotoxicosis. However, the effects and mechanism of Lugol solution for reducing blood flow have not been well investigated in the patients with euthyroid (normally functioning thyroid) Graves' disease.

METHODS

Twenty-five patients with euthyroid Graves' disease being preoperatively treated with Lugol solution for 10 days were measured, at baseline and on the operative day, for (1) superior thyroid artery blood flow; (2) systemic angiogenic factor (VEGF); and (3) systemic inflammatory factor [interleukin (IL)-16].

RESULTS

All three parameters were significantly (p < 0.0001) lower after 10 days of Lugol solution treatment. The average reductions were blood flow: 60% (0.294 vs. 0.117 L/min), serum VEGF: 55% (169.8 vs. 76.7 pg/mL), and serum IL-16: 50% (427.2 vs. 214.2; pg/mL).

CONCLUSION

Lugol solution significantly reduced thyroid arterial blood flow, VEGF, and IL-16, even in patients with euthyroid Graves' disease. We recommend routine preoperative Lugol solution treatment for all patients with Graves' disease.

Drug discovery in ophthalmology: past success, present challenges, and future opportunities

BACKGROUND

Drug discovery has undergone major transformations in the last century, progressing from the recognition and refinement of natural products with therapeutic benefit, to the systematic screening of molecular libraries on whole organisms or cell lines and more recently to a more target-based approach driven by greater knowledge of the physiological and pathological pathways involved. Despite this evolution increasing challenges within the drug discovery industry are causing escalating rates of failure of development pipelines.

DISCUSSION

We review the challenges facing the drug discovery industry, and discuss what attempts are being made to increase the productivity of drug development, including a refocusing on the study of the basic biology of the disease, and an embracing of the concept of 'translational research'. We consider what ophthalmic drug discovery can learn from the sector in general and discuss strategies to overcome the present limitations. This includes advances in the understanding of the pathogenesis of disease; improvements in animal models of human disease; improvements in ophthalmic drug delivery and attempts at patient stratification within clinical trials. As we look to the future, we argue that investment in ophthalmic drug development must continue to cover the whole translational spectrum (from 'bench to bedside and back again') with recognition that both biological discovery and clinical understanding will drive drug discovery, providing safe and effective therapies for ocular disease.

IL-14 and IL-16 are expressed in the thyroid of patients with either Graves' disease or Hashimoto's thyroiditis

OBJECTIVES

Cytokines have an important role in orchestrating the pathophysiology in autoimmune thyroid disease. The aim of the current study was to analyse the expression of interleukin (IL)-14 and IL-16 in the thyroid tissue of patients with Graves' disease (GD), Hashimoto's thyroiditis (HT) or multinodular goitre (MNG) and in that of normal individuals, in patients' intrathyroidal CD4(+) and CD8(+) T cells, and in patient and normal cultured thyroid follicular cells.

METHODS

The expression of IL-14 and IL-16 mRNA and protein was investigated using reverse transcription-polymerase chain reaction (RT-PCR) amplification, and Western blotting and ELISAs, respectively.

RESULTS

IL-14 mRNA expression was detected in thyroid tissue from 8/9 GD, 3/4 HT and 3/13 MNG patients and 1/6 normal individuals, and IL-16 mRNA expression in thyroid tissue from 9/9 GD, 4/4 HT and 9/13 MNG patients and 4/6 normal individuals. IL-14 mRNA expression was detected in intrathyroidal CD4(+) and CD8(+) T cells from 2/2 GD and 2/2 HT patients, while IL-16 mRNA was detected in samples from 1/2 HT patients but not in those from either patient with GD. IL-14 and IL-16 mRNA expression was found in thyroid follicular cells derived from 2/2 patient with GD and 1/1 normal individual. IL-14 protein was detected in thyroid tissue from 6/6 GD, 1/1 HT and 0/6 MNG patients and 0/6 normal individuals, and IL-16 protein in thyroid tissue from 6/6 GD, 1/1 HT and 1/6 MNG patients and 0/6 normal individuals. Expression of IL-14 protein was stimulated in thyroid follicular cells derived from two patients with GD and one normal individual by peripheral blood mononuclear cell (PBMC)-conditioned medium. Treatment of thyrocytes from two patients with GD and one normal individual with PBMC-conditioned medium and tumour necrosis factor (TNF)-α stimulated IL-16 protein expression. In normal thyrocytes, IL-16 protein synthesis was induced also by IL-1β, IL-17A, IL-4 and transforming growth factor (TGF)-β.

CONCLUSIONS

The data provide evidence that the intrathyroidal production of IL-14 and IL-16 is associated with the pathogenesis of autoimmune thyroid disease. Thyroid follicular cells display the ability to express IL-14 and IL-16 mRNA and can be stimulated to express IL-16 protein, by a panel of cytokines, and IL-14 protein, by as yet unidentified factors.

Possible targets for nonimmunosuppressive therapy of Graves' orbitopathy

CONTEXT

Graves' orbitopathy (GO) is caused by expansion of the orbital contents by excess adipogenesis and overproduction of hyaluronan (HA). Immunosuppressive and antiinflammatory treatments of GO are not always effective and can have side effects, whereas targeting GO-associated tissue remodeling might be a more logical therapeutic strategy. Previously we reported that signaling cascades through IGF1 receptor and thyrotropin receptor within orbital preadipocytes/fibroblasts drove adipogenesis and HA production. Our current study combined the stimulation of IGF1 receptor and thyrotropin receptor increase of HA accumulation, which we hypothesize is by activation of phosphatidylinositol 3-kinase (PI3K)-1A/PI3K1B, respectively. The central aim of this study was to investigate whether PI3K/mammalian target of rapamycin complex 1 (mTORC1) inhibitors affected adipogenesis and/or HA production within orbital preadipocyte/fibroblasts.

METHODS

Human orbital preadipocytes were treated with/without inhibitors, LY294002 (PI3K1A/mTORC1), AS-605240 (PI3K1B), or PI103 (PI3K1A/mTORC1) in serum-free medium for 24 hours or cultured in adipogenic medium for 15 days. Quantitative PCR was used to measure hyaluronan synthases (HAS2) transcripts and the terminal adipogenesis differentiation marker lipoprotein lipase. HA accumulation in the medium was measured by an ELISA.

RESULTS

Unlike AS-605240, both LY294002 (10 μM) and PI-103 (5 μM) significantly decreased HAS2 transcripts/HA accumulation and adipogenesis. Because PI-103 and LY294002 are dual PI3K/mTOR inhibitors, we investigated the inhibition of mTORC1 (rapamycin 100 nM), which significantly decreased adipogenesis but had no effect on HAS2 transcripts/HA, implicating PI3K-1A in the latter.

CONCLUSIONS

The combined inhibition of PI3K1A and mTORC1 signaling in vitro decreased both HA accumulation and adipogenesis. Because PI3K and mTOR inhibitors are clinically used to treat other conditions, they have the potential to be repositioned to be used as an alternative nonimmunosuppressive therapy of GO.

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.

IL-1β and TSH disturb thyroid epithelium integrity in autoimmune thyroid diseases

Pro-inflammatory cytokines such as IL-1β and TNFα are known to affect thyroid function. They stimulate IL-6 secretion and modify epithelium integrity by altering junction proteins. To study the role of cytokines on thyroid epithelia tightness in autoimmune thyroid diseases (AITD), we analyzed the expression profiles of junction proteins (ZO-1, Claudin, JAM-A) and cytokines in human thyroid slices and also investigated the effect of IL-1β on the epithelium integrity in primary cultures of human thyrocytes. Junction proteins expression (ZO-1, Claudin, JAM-A) has been analyzed by immunohistochemistry on thyroid slices and by Western blot on membrane proteins extracted from thyrocytes of patients suffering from Graves and Hashimoto diseases. The high expression of junction proteins we found on Graves' disease thyroid slices as well as in cell membrane extracts acknowledges the tightness of thyroid follicular cells in this AITD. In contrast, the reduced expression of JAM and ZO-1 in thyroid cells from patients suffering from Hashimoto thyroiditis is in agreement with the loss of thyroid follicular cell integrity that occurs in this pathology. Concerning the effects on epithelium integrity of TSH and of the pro-inflammatory cytokine IL-1β in primary cultures of human thyroid cells, TSH appeared able to modify JAM-A localization but without any change in the expression levels of JAM-A, Claudin and ZO-1. Inversely, IL-1β provoked a decrease in the expression of- and a redistribution of both, Claudin and ZO-1 without modifying the expression and sub-cellular distribution patterns of JAM-A in thyroid cells. These results demonstrate (i) that Hashimoto's- and Graves' diseases display different junction proteins expression patterns with a loss of epithelium integrity in the former and (ii) that IL-1β modifies thyroid epithelial tightness of human thyrocytes by altering the expression and localization of junction proteins. Therefore, IL-1β could play a role in the pathogenesis of thyroid autoimmunity.

Role of insulin-like growth factor-1 (IGF-1) pathway in the pathogenesis of Graves' orbitopathy

The etiology of Graves' orbitopathy (GO) remains enigmatic and thus controversy surrounds its pathogenesis. The role of the thyroid stimulating hormone receptor (TSHR) and activating antibodies directed against it in the hyperthyroidism of Graves' disease (GD) is firmly established. Less well elucidated is what part the TSHR pathway might play in the development of GO. Also uncertain is the participation of other cell surface receptors in the disease. Elevated levels of insulin-like growth factor-1 receptor (IGF-1R) have been found in orbital fibroblasts as well as B and T cells from patients with GD. These abnormal patterns of IGF-1R display are also found in rheumatoid arthritis and carry functional consequences. In addition, activating IgGs capable of displacing IGF-1 from IGF-1R have also been detected in patients with these diseases. IGF-1R forms a complex with TSHR which is necessary for at least some of the non-canonical signaling observed following TSHR activation. Functional TSHR and IGF-1R have also been found on fibrocytes, CD34⁺ bone marrow-derived cells from the monocyte lineage. Levels of TSHR on fibrocytes greatly exceed those found on orbital fibroblasts. When ligated by TSH or M22, a TSHR-activating monoclonal antibody, fibrocytes produce extremely high levels of several cytokines and chemokines. Moreover, fibrocytes infiltrate both the orbit and thyroid in GD. In sum, based on current evidence, IGF-1R and TSHR can be thought of as "partners in crime". Involvement of the former probably transcends disease boundaries, while TSHR may not.

Histopathology of brow fat in thyroid-associated orbitopathy

PURPOSE

We propose that brow enlargement seen in patients with thyroid-associated orbitopathy (TAO) occurs secondary to the autoimmune process in Graves disease and that the changes in brow fat are histologically identical to those seen in orbital fat.

METHODS

With informed consent, brow and orbital fat was obtained from patients with TAO and from patients with no significant past medical history undergoing orbital decompression, blepharoplasty, and/or brow fat removal. Histologic examination was performed on the orbital and brow fat.

RESULTS

Fat histologies obtained from patients with TAO and those without known systemic disease were compared. Specimens from patients with TAO showed an increase of fibrosis and fibrous septae. Furthermore, certain biologic markers, including insulin-like growth factor 1 receptor β (IGF-1Rβ) and thyroid-stimulating hormone receptor (TSHR), were increased in the fat obtained from patients with TAO. This was identical in both the brow and the orbital fat. Fat from patients with no significant past medical history showed normal fat histology, absence of fibrous septae, and decreased marker expression.

CONCLUSION

Graves disease is a systemic autoimmune disease that affects patients in a variety of ways. In addition to the orbital changes seen in these patients, we have observed an increase in the brow fat compartment. We are intrigued to find that the histologic changes are identical in both the orbital and the brow fat of patients with TAO. The increased IGF-1Rβ and TSHR expression in both the brow and the orbital fat further support their role as putative markers in patients with Graves disease.

Adipose tissue depot-specific differences in the regulation of hyaluronan production of relevance to Graves' orbitopathy

CONTEXT

Graves' orbitopathy (GO) is associated with Graves' disease, in which anti-TSH receptor (TSHR) autoantibodies (thyroid-stimulating antibodies) increase cAMP causing hyperthyroidism. Excess adipogenesis and hyaluronan (HA) overproduction [HA synthase 2 (HAS2) is the major source] expand the orbital contents causing GO. TSHR activation participates in both processes but an anti-TSHR monoclonal without TSAB activity also increased HA, suggesting the involvement of other cascades. OBJECTIVE AND PATIENTS STUDIED: We investigated using in vitro models in which preadipocytes/fibroblasts from human orbital (n = 12) and sc (n = 10) adipose tissues were treated with IGF-I (to probe the pAkt pathway, recently identified as a positive regulator of HAS2), TSH, and/or various inhibitors. Changes in HA during in vitro-induced adipogenesis were also evaluated.

MAIN OUTCOME AND RESULTS

Adipogenesis in orbital preadipocytes was accompanied by significantly increased HAS2 transcripts and HA accumulation in contrast to sc cells in which differentiation significantly decreased HAS2 mRNA and secreted HA. Surprisingly, IGF-I alone did not increase HAS2 levels, despite significantly increasing the ratio of phosphorylated to total Akt; furthermore, an Akt inhibitor increased orbital (but not sc) HAS2 transcripts. A stimulatory effect of IGF-I on HAS2 transcripts was revealed by addition of rapamycin in sc but by a MAPK kinase inhibitor in orbital fibroblasts.

CONCLUSIONS

The results have several possible explanations including a phosphorylation-dependent repressor of HAS2 transcript accumulation, exclusively in the orbit. The difference in control of HAS2 expression allows the activation of one of the mechanisms underlying GO, adipogenesis, to be linked biologically with the second, HA overproduction.

Fibroblasts expressing the thyrotropin receptor overarch thyroid and orbit in Graves' disease

CONTEXT

Graves' disease (GD) is a systemic autoimmune syndrome comprising manifestations in thyroid and orbital connective tissue. The link between these two tissues in GD eludes our understanding. Patients with GD have increased frequency of circulating monocyte lineage cells known as fibrocytes. These fibrocytes infiltrate orbital connective tissues in thyroid-associated ophthalmopathy and express functional TSH receptor (TSHR).

OBJECTIVE

The aim of the study was to identify and characterize CD34(+) fibrocytes in thyroid tissue.

DESIGN/SETTING/PARTICIPANTS

Patients undergoing surgical thyroidectomy at two academic medical centers were recruited to the study.

MAIN OUTCOME MEASURES

We performed immunohistochemistry, flow cytometry, real-time PCR, cytokine-specific ELISA, and cell differentiation.

RESULTS

CD34(+)ColI(+)CXCR4(+)TSHR(+) cells can be identified in situ in thyroid tissue from donors with GD, Hashimoto's thyroiditis, or in normal-appearing tissue. Thyroid fibroblasts cultivated from these glands express a CD34(-)ColI(+)CXCR4(+)TSHR(+) phenotype. TSHR levels are higher than those in orbital fibroblasts. When treated with TSH, thyroid fibroblasts generate IL-6 and IL-8. The induction of IL-6 can be blocked by dexamethasone, a chemical inhibitor of Akt/Pkb, and by knocking down Akt with a specific small interfering RNA. When treated with TGF-β or rosiglitazone, thyroid fibroblasts differentiate into myofibrocytes or adipocytes, respectively.

CONCLUSIONS

ColI(+)CXCR4(+)TSHR(+) thyroid fibroblasts resemble orbital fibroblasts and circulating fibrocytes. CD34(+) fibrocytes appear to infiltrate both tissues in GD. Thyroid fibroblasts lose CD34 display in culture, unlike orbital fibroblasts and circulating fibrocytes. Fibrocytes and their fibroblast derivatives may participate in the pathogenesis of thyroid autoimmunity after TSHR activation. They could represent a therapeutic target for these diseases.

Insulin-like growth factor-I regulation of immune function: a potential therapeutic target in autoimmune diseases?

This topically limited review explores the relationship between the immune system and insulin-like growth factors (IGF-I and IGF-II) and the proteins through which they act, including IGF-I receptor (IGF-IR) and the IGF-I binding proteins. The IGF/IGF-IR pathway plays important and diverse roles in tissue development and function. It regulates cell cycle progression, apoptosis, and the translation of proteins. Many of the consequences ascribed to IGF-IR activation result from its association with several accessory proteins that are either identical or closely related to those involved in insulin receptor signaling. Relatively recent awareness that IGF-I and IGF-IR regulate immune function has cast this pathway in an unexpected light; it may represent an important switch governing the quality and amplitude of immune responses. IGF-I/IGF-IR signaling may also participate in the pathogenesis of autoimmune diseases, although its relationship with these processes seems complex and relatively unexplored. On the one hand, IGF-I seems to protect experimental animals from developing insulin-deficient diabetes mellitus. In contrast, activating antibodies directed at IGF-IR have been detected in patients with Graves' disease, where the receptor is overexpressed by multiple cell types. The frequency of IGF-IR+ B and T cells is substantially increased in patients with that disease. Potential involvement of IGF-I and IGF-IR in the pathogenesis of autoimmune diseases suggests that this pathway might constitute an attractive therapeutic target. IGF-IR has been targeted in efforts directed toward drug development for cancer, employing both small-molecule and monoclonal antibody approaches. These have been generally well-tolerated. Recognizing the broader role of IGF-IR in regulating both normal and pathological immune responses may offer important opportunities for therapeutic intervention in several allied diseases that have proven particularly difficult to treat.

Evidence for an association between thyroid-stimulating hormone and insulin-like growth factor 1 receptors: a tale of two antigens implicated in Graves' disease

Thyroid-stimulating hormone receptor (TSHR) plays a central role in regulating thyroid function and is targeted by IgGs in Graves' disease (GD-IgG). Whether TSHR is involved in the pathogenesis of thyroid-associated ophthalmopathy (TAO), the orbital manifestation of GD, remains uncertain. TSHR signaling overlaps with that of insulin-like grow factor 1 receptor (IGF-1R). GD-IgG can activate fibroblasts derived from donors with GD to synthesize T cell chemoattractants and hyaluronan, actions mediated through IGF-1R. In this study, we compare levels of IGF-1R and TSHR on the surfaces of TAO and control orbital fibroblasts and thyrocytes and explore the physical and functional relationship between the two receptors. TSHR levels are 11-fold higher on thyrocytes than on TAO or control fibroblasts. In contrast, IGF-1R levels are 3-fold higher on TAO vs control fibroblasts. In pull-down studies using fibroblasts, thyrocytes, and thyroid tissue, Abs directed specifically against either IGF-1Rbeta or TSHR bring both proteins out of solution. Moreover, IGF-1Rbeta and TSHR colocalize to the perinuclear and cytoplasmic compartments in fibroblasts and thyrocytes by confocal microscopy. Examination of orbital tissue from patients with TAO reveals similar colocalization to cell membranes. Treatment of primary thyrocytes with recombinant human TSH results in rapid ERK phosphorylation which can be blocked by an IGF-1R-blocking mAb. Our findings suggest that IGF-1R might mediate some TSH-provoked signaling. Furthermore, they indicate that TSHR levels on orbital fibroblasts are considerably lower than those on thyrocytes and that this receptor associates with IGF-1R in situ and together may comprise a functional complex in thyroid and orbital tissue.

Recent insights into the pathogenesis and management of thyroid-associated ophthalmopathy

PURPOSE OF REVIEW

To identify and critique the most recent experimental findings regarding the pathogenesis and therapy of thyroid-associated ophthalmopathy.

RECENT FINDINGS

Much of the recent work in this field has focused on identifying genetic alterations associated with the phenotypes of Graves' disease and thyroid-associated ophthalmopathy and investigating their functional consequences. Identified candidate genes include CD40, cytotoxic T-lymphocyte antigen-4, protein tyrosine phosphatase-22, human leukocyte antigen-major histocompatibility complex and those associated with the X-chromosome. Efforts to generate a complete rodent model of Graves' disease continue with little progress. These uniformly involve the immunization of animals with the thyrotropin receptor. Studies conducted in vitro have focused on the actions of cytokines in orbital fibroblasts, the potential role of the insulin-like growth factor-1 receptor and activating antibodies directed against it as a fibroblast and T cell activation pathway. Reports continue to appear examining the potential relationship between the thyrotropin receptor and orbital adipogenesis. Regarding therapy for thyroid-associated ophthalmopathy, small molecules and antibodies disrupting cytokine pathways and lymphocyte function are currently under examination and have yielded promising albeit preliminary results.

SUMMARY

Thyroid-associated ophthalmopathy remains a vexing medical problem, the pathogenesis of which remains uncertain. A number of obstacles continue to plague major advances, not least of which is the absence of a robust animal model. A few new insights seem to represent departure from traditional thinking about this disease and may herald important innovation.

Cytokines, Graves' disease, and thyroid-associated ophthalmopathy

Graves' disease, an autoimmune process associated with thyroid dysfunction, can also manifest as remodeling of orbital connective tissue. Affected tissues exhibit immune responses that appear to be orchestrated by resident cells and those recruited from the bone marrow through their expression and release of cytokines and surface display of cytokine receptors. Cytokines are small molecules produced by many types of cells, including those of the "professional" immune system. Aberrant cytokine expression appears to play an important role in the pathogenesis of many human diseases, including thyroid autoimmunity. The skewed pattern of cytokine expression in the thyroid, including the T helper cell bias, may condition the response to apoptotic signals and determine the characteristics of an autoimmune reaction. Furthermore, chemoattractant cytokines, including IL16, RANTES, and CXCL10, elaborated by resident cells in the thyroid and orbit may provoke mononuclear cell infiltration. Other cytokines may drive cell activation and tissue remodeling. Thus cytokines and the signaling pathways they activate represent attractive therapeutic targets. Interruption of these might alter the natural course of Graves' disease and its orbital manifestations.

Chemokine orchestration of autoimmune thyroiditis

Chemokines are low-molecular-weight proteins that attract leukocytes and other cell types, via interaction with G protein-coupled receptors. Chemokines control leukocyte migration not only during inflammatory processes, but also throughout ontogeny and differentiation of lymphoid tissues. They have been involved in the pathogenesis of numerous diseases, such as human immunodeficiency virus infection, allergy, atherosclerosis, cancer, and autoimmunity. The number of studies focusing on chemokine biology is expanding exponentially. For example, searching PubMed for the terms "thyroid" and "chemokine" retrieved 1 article in 1980s, 18 articles in 1990s, and 81 articles from 2000 to July 2007. This review will focus on studies analyzing the role of chemokine in autoimmune thyroiditis (Graves' disease and Hashimoto's thyroiditis), performed in both patients and experimental animals. The goal is to emphasize how a better understanding of chemokine biology has advanced our knowledge of the pathogenesis of autoimmune thyroiditis.

Rapamycin for treatment of refractory dysthyroid compressive optic neuropathy

We report a patient with dysthyroid optic neuropathy refractory to steroids and orbital decompression treated with rapamycin, a fibroblast and T cell inhibitor. Symptoms, visual acuity, color plate testing, and visual fields improved. Aside from hypercholesterolemia, no complication related to this therapy was observed. By addressing the pathogenesis of thyroid eye disease, rapamycin may represent an alternative when standard treatments fail. Further investigation of rapamycin for treatment of dysthyroid orbitopathy is warranted.

Aberrant expression of the insulin-like growth factor-1 receptor by T cells from patients with Graves' disease may carry functional consequences for disease pathogenesis

Graves' disease (GD), an autoimmune process involving thyroid and orbital tissue, is associated with lymphocyte abnormalities including expansion of memory T cells. Insulin-like growth factor receptor-1 (IGF-1R)-bearing fibroblasts overpopulate connective tissues in GD. IGF-1R on fibroblasts, when ligated with IgGs from these patients, results in the expression of the T cell chemoattractants, IL-16 and RANTES. We now report that a disproportionately large fraction of peripheral blood T cells express IGF-1R (CD3+IGF-R+). CD3+IGF-1R+ T cells comprise 48 +/- 4% (mean +/- SE; n = 33) in patients with GD compared with 15 +/- 3% (n = 21; p < 10(-8)) in controls. This increased population of IGF-1R+ T cells results, at least in part, from an expansion of CD45RO+ T cells expressing the receptor. In contrast, the fraction of CD45RA+IGF-1R+ T cells is similar in GD and controls. T cells harvested from affected orbital tissues in GD reflect similar differences in the proportion of IGF-1R+CD3+ and IGF-1R+CD4+CD3+ cells as those found in the peripheral circulation. GD-derived peripheral T cells express durable, constitutive IGF-1R expression in culture and receptor levels are further up-regulated following CD3 complex activation. IGF-1 enhanced GD-derived T cell incorporation of BrdU (p < 0.02) and inhibited Fas-mediated apoptosis (p < 0.02). These findings suggest a potential role for IGF-1R displayed by lymphocytes in supporting the expansion of memory T cells in GD.

Pharmacological Treatments for Thyroid Eye Disease

Thyroid eye disease (TED), which affects the majority of patients with Grave's disease, is associated with significant ophthalmic morbidity. In patients with mild disease, supportive treatment with lubricating medication can be sufficient. However, in patients with severe TED and disfiguring proptosis or sight-threatening neuropathy, more aggressive medical or surgical interventions are necessary. Corticosteroids remain the preferred pharmacological treatment modality in the majority of patients with an active inflammatory component. Other immunosuppressive drugs in combination with corticosteroids may be helpful in patients with corticosteroid-resistant TED. Newer agents such as somatostatin analogues have not shown to be of significant clinical benefit; however, initial studies on the use of antioxidants and cytokine antagonists are encouraging.