Antibodies targeting the calcium binding skeletal muscle protein calsequestrin are specific markers of ophthalmopathy and sensitive indicators of ocular myopathy in patients with Graves' disease

Molecular Biomarkers in Thyroid Eye Disease: A Literature Review

PURPOSE

Thyroid eye disease (TED) is the most common extrathyroidal manifestation of Graves disease. Patients may be severely affected with eyelid retraction, exophthalmos, diplopia, pain, and threatened vision. Autoantibodies against thyroid-stimulating hormone receptor and insulin-like growth factor 1 receptor have shown associations with pathophysiological and clinical traits. Autoantibodies against thyroid-stimulating hormone receptor is in current clinical use as biomarker, but not with unambiguous diagnostic performance. A biomarker with high diagnostic accuracy and/or prognostic capability would be of immense value in diagnosing TED, especially in subclinical cases or when TED precedes the thyroid dysfunction. This article is a literature review on molecular biomarkers of TED.

METHODS

A literature search was performed using PubMed and Embase. Studies on molecular biomarkers in blood, tear fluid, and urine were included in the review.

RESULTS

Forty-six papers were included, of which 30, 14, and 2 studies on biomarkers in blood, tears, and urine, respectively. Fourteen of the papers evaluated the diagnostic performance of various biomarkers, 12 in blood and 2 in tears. Most studies evaluated single biomarkers, but 3 tested a panel of several markers. Except for autoantibodies against thyroid-stimulating hormone receptor, the reported diagnostic performances for the biomarkers were not confirmed in independent cohorts. In 32 studies, no or insufficient performance data were given, but the findings indicated involvement of various biologic mechanisms in TED including inflammation, oxidative stress, fibrosis, lipid metabolism, and ocular surface microflora.

CONCLUSIONS

Currently, serum autoantibodies against thyroid-stimulating hormone receptor is the only molecular biomarker with clinical utility in patients with TED. Several potential biomarkers have been investigated, and particularly panels of multiple biomarkers in tears are promising. To improve patient care, biomarkers in TED should be studied further.

A systematic review of euthyroid Graves' disease (Review)

Euthyroid Graves' Disease (EGD) is a challenging pathology, due to its atypical clinical manifestations and the absence of abnormal thyroid function. Typically, thyroid ophthalmopathy is associated with elevated thyroid hormone levels and with the presence of thyrotropin receptor antibodies (TRAb) but a low percentage of patients remain euthyroid without developing hyperthyroidism during long-term follow-up periods. Although it is considered a different pathology, it shares a lot of similarities with Graves' disease, rendering the diagnosis more difficult. It is also important to note that ophthalmopathy may be the first clinical manifestation of Graves' disease and that thyroid function examinations do not present abnormalities over a long period. Treatment choices for euthyroid disease do not differ from those described in Graves' ophthalmopathy. However, it is considered that since euthyroid patients develop milder ophthalmic symptoms and their clinical activity score is lower, they tend to have better responses to treatment. Moreover, atypical sight-threatening cases such as exposure keratopathy and dysthyroid optic neuropathy with variable responses to therapy also exist. Disease management consists of a favorable collaboration between ophthalmologists and endocrinologists because patients with EGD can develop thyroid abnormalities over time. In conclusion, the diagnosis of EGD is difficult, clinical manifestations and evolution are variables depending on several factors, including the heterogeneity of TRAb. This review aimed to identify the characteristics of this disease by reviewing the clinical studies and case reports published in previous years.

Prognostic factors of restrictive myopathy in thyroid eye disease

To investigate the prognostic factors of extraocular muscle restriction in patients with thyroid eye disease (TED), 65 patients with TED and restrictive myopathy were evaluated. Demographics, clinical activity score (CAS), smoking status, thyroid disease status, thyroid hormone status, thyroid autoantibody status, orbital computed tomography (CT) scan at initial presentation, and treatment regimens were assessed. The movements of the most severely affected extraocular muscles were categorized into five grades. The patients were divided into the improved and the not-improved group based on the improvement in the limitation of the extraocular muscle excursion (LOM) throughout the follow-up, and the groups were compared using clinical factors. The mean LOM significantly improved from 2.3 ± 1.1 to 1.7 ± 1.2 after 1 year of follow-up. The excursion of the most restricted muscle improved in 32 patients but not in 33 patients during the follow-up. The initial concentration of the thyroid-stimulating antibody (TSAb) was significantly lower in the improved (229.3 ± 114.1) than in the not-improved group (345.0 ± 178.6) (P = 0.02) Age, sex, smoking status, CAS, thyroid status, and muscle thickness on the CT scan did not significantly differ in the groups. This study showed that the initial concentration of TSAb is a factor affecting the recovery of restrictive myopathy.

Correlation between thyroidal and peripheral blood total T cells, CD8+ T cells, and CD8+ T- regulatory cells and T-cell reactivity to calsequestrin and collagen XIII in patients with Graves' ophthalmopathy

Purpose/aim of the study: Graves' ophthalmopathy (GO) is closely related to the thyroid autoimmune disorder Graves' disease. Previous studies have suggested roles for thyroidal CD8⁺ T cells and autoimmunity against calsequestrin-1 (CASQ)-1 in the link between thyroidal and orbital autoimmune reactions in GO. A role for autoimmunity against CollXIII has also been suggested. In this study, we aimed to investigate correlations between some thyroidal and peripheral blood T-cell subsets and thyroidal T-cell reactivity against CASQ1 and CollXIII in patients with GO.

MATERIALS AND METHODS

Fresh thyroid tissues were processed by enzyme digestion and density gradient to isolate mononuclear cells (MNCs). Peripheral blood MNCs were also isolated using density gradient. Flow-cytometric analysis was used to identify the various T-cell subsets. T -cell reactivity to CASQ1 and CollXIII was measured by a 5-day culture of the MNCs and BrdU uptake method.

RESULTS

We found a positive correlation between thyroidal CD8⁺  T cells and CD8⁺ T-regulatory (T-reg) cells in patients with GO. Thyroidal T cells from two out of the three patients with GO tested (66.7%) showed a positive response to CASQ1, while thyroidal T cells from none of the six Graves' Disease patients without ophthalmopathy (GD) tested showed a positive response to this antigen. Thyroidal T cells from these patient groups however, showed no significant differences in their response to CollXIII.

CONCLUSIONS

Our observations provide further evidence for a possible role of thyroidal CD8⁺ T cells, CD8⁺ T-reg cells and the autoantigen CASQ1 in the link between thyroidal and orbital autoimmune reactions of GO.

A Case of Euthyroid Graves' Ophthalmopathy in a Patient Sero-Negative for TSH Receptor Autoantibody

We report of a case of Graves' ophthalmopathy presented solely with symptoms of the eyes with normal thyroid function tests and negative immunoreactive TSH receptor autoantibody. 40-year-old male was referred to our hospital due to 2-month history of ocular focusing deficit without any signs or symptoms of hyper- or hypothyroidism. Serum thyroid function tests and ^99mTc uptake were both within the normal range. Anti-thyroid autoantibodies were all negative except for the cell-based assay for serum TSH receptor stimulating activity. Since orbital CT scan and MRI gave typical results compatible with Graves' ophthalmopathy, we treated the patients with corticosteroid pulse therapy and orbital radiation therapy, leading to a partial improvement of the symptoms. This case gives insights into the potential pathophysiologic mechanism underlying Graves' ophthalmopathy and casts light upon the difficulties of establishing the diagnosis in a euthyroid case with minimal positive results for anti-thyroid autoantibodies.

99Tcm-octreotide scintigraphy and serum eye muscle antibodies in evaluation of active thyroid-associated ophthalmopathy

PurposeAs an autoimmune inflammatory disorder, active thyroid-associated ophthalmopathy (TAO) is managed optimally by immunosuppression. In this study, we aimed to evaluate octreotide scintigraphy and the level of serum extraocular muscle antibodies in TAO activity.Patients and methodsThis prospective study comprised 304 patients with active TAO (the clinical activity score; CAS≥3), 73 with inactive TAO (CAS<3), 128 with Graves' disease (GD) without ophthalmopathy, and 100 healthy subjects. Moderate-to-severe active TAO patients (CAS≥5) received intravenous injection of methylprednisolone; mild active patients (3≤CAS≤4) received periocular injection of triamcinolone acetonide. ⁹⁹Tc^m-octreotide scintigraphy and serum levels of calsequestrin, uveal auto-antigen with coiled-coil domains and ankyrin repeats (UACA) and G2s antibodies were detected before and after treatment.Results⁹⁹Tc^m-octreotide scintigraphy was positive in active TAO patients (97%) with elevated uptake ratio (UR) (P<0.05), and showed a significant correlation with CAS (r=0.816, P<0.01). After treatment both UR and CAS decreased significantly (P<0.05). The receiving operator characteristic curve (ROC) showed that the best UR threshold for discriminating active and inactive TAO was 1.34 (sensitivity, 100%; specificity, 89.4%). The level of serum calsequestrin antibody was higher in active TAO (P<0.05), showed a significant correlation with CAS (r=0.738, P<0.05), and also decreased after treatment (P<0.05). The best serum calsequestrin antibody threshold of the ROC curve was 138 ng/l (sensitivity, 88.4%; specificity, 89.2%). The UACA antibody was elevated in both TAO and GD patients (P<0.05), with no significant difference (P>0.05). As to G2s, no significant difference was found between all groups (P>0.05). Moreover, six GD patients (4.69%) with elevated calsequestrin developed active TAO 12 weeks later.Conclusion⁹⁹Tc^m-octreotide scintigraphy played a critical role in the evaluation of the clinical activity and therapeutic efficacy of TAO. Autoimmunity against calsequestrin in the pathogenesis of the eye muscle components may provide further objective evidence of myopathy in active TAO. Furthermore, calsequestrin antibody may predict myopathy in active TAO.

Novel single-nucleotide polymorphisms in the calsequestrin-1 gene are associated with Graves' ophthalmopathy and Hashimoto's thyroiditis

BACKGROUND

The eye disorder associated with Graves' disease, called Graves' ophthalmopathy (GO), greatly reduces the quality of life in affected patients. Expression of the calsequestrin (CASQ1) protein in thyroid tissue may be the trigger for the development of eye muscle damage in patients with GO. We determined the prevalence of rs74123279, rs3747673, and rs2275703 single-nucleotide polymorphism (SNPs) in patients with autoimmune thyroid disorders, GO, Graves' hyperthyroidism (GH), or Hashimoto's thyroiditis (HT) and control subjects with no personal or family history of autoimmune thyroid disorders. Furthermore, we measured the concentration of the CASQ1 protein in normal and Graves' thyroid tissue, correlating levels with parameters of the eye signs, CASQ1 antibody levels, and the CASQ1 gene polymorphism rs74123279 and rs2275703.

METHODS

High-quality genomic DNA was isolated from fresh blood samples, assayed for identification of rs74123279, rs3747673, and rs2275703 SNPs in CASQ1 gene by MassARRAY SNP analysis using iPLEX technology of SEQUENOM.

RESULTS

DNA samples from 300 patients and 106 control subjects (100 males, 306 females) with GO (n=74), GH (n=130), HT (n=96) and control subjects (n=106) were genotyped for the SNPs rs74123279, rs3747673 (n=405), and rs2275703 (n=407). The SNP rs74123279, rs3747673, and rs2275703 were identified as 1) common homozygous or wild type, 2) heterozygote, and 3) rare homozygous. Minor allele frequency for rs74123279, rs3747763, and rs2275703 were 21%, 40%, and 44%, respectively. Multiple comparisons of genotype frequency for rs74123279, rs3747763, and rs2275703 in the GO, GH, HT, and control groups showed P=0.06, 0.641, and 0.189, respectively. These results were substantiated by multiple comparison of alleles frequency for rs74123279, rs3838216, rs3747763, and rs2275703 in the GO, GH, HT, and control groups showed, P=0.36, 0.008, 0.66, and 0.05, respectively. Pairwise analysis of alleles frequency distribution in patients with GO showed significant probability for rs2275703, P=0.008.

CONCLUSION

Based on their evolutionary conservation and their significant prevalence, we suggest that CASQ1 gene SNPs rs74123279, rs3838216, and rs2275703 may be considered as genetic markers for GO.

Long-term follow-up of seven patients with ophthalmopathy not associated with thyroid autoimmunity: heterogeneity of autoimmune ophthalmopathy

BACKGROUND

Ophthalmopathy is the most common extrathyroidal manifestation of Graves' disease. However, in approximately 5% of cases this autoimmune eye disorder occurs in the apparent absence of Graves' hyperthyroidism: the so-called euthyroid Graves' disease (EGD).

METHODS

Seven patients with EGD were followed for evidence of thyroid and orbital autoimmunity, for up to 10 years. Calsequestrin and collagen XIII antibodies were measured by enzyme linked immunosorbent assay (ELISA), and TSH-receptor (TSH-r) antibodies were measured as TSH-r-binding antibody (TRAb) and thyroid-stimulating immunoglobulin (TSI). Eye signs were characterized and quantified as clinical activity score (CAS), NOSPECS classes, Nunery types 1 and 2, and margin-reflex distance (MRD).

RESULTS

Calsequestrin antibodies were detected on at least one occasion in three of the seven patients and collagen XIII antibodies were detected one or more times in five patients. In one patient with isolated congestive ophthalmopathy who was studied intensely, collagen XIII antibodies were initially positive and then became negative as the eye disease stabilized, while antibodies targeting calsequestrin were always negative. TRAb was not detected in any patient, but TSI was detected in three patients on one occasion each. Ultrasound abnormalities were found in four of the six patients for whom this was carried out, but there was no clear evidence for thyroiditis in any of these patients. For comparison, 13 patients were studied with typical Graves' ophthalmopathy. There were no significant differences compared to EGD in respect to the prevalence of positive calsequestrin or collagen XIII antibodies, but these patients included more smokers (eight out of 13 versus none out of seven).

CONCLUSIONS

Earlier studies suggesting that patients with EGD eventually develop thyroid dysfunction have not been confirmed here, although follow-up continues, and the possibility that such patients have had thyroid autoimmunity in the past, or that they will develop it in the future cannot be excluded. Overall, it is likely that the ophthalmopathy associated with Graves' hyperthyroidism is the same disease as that observed in patients - such as those reported here - in whom thyroid dysfunction and thyroid autoimmunity are not present during the period of follow- up. The role of autoimmunity against the TSH-r in euthyroid patients with ophthalmopathy has not been proven and the significance of the orbital antibodies is unclear.

Eye findings and immunological markers in probands and their euthyroid relatives from a single family with multiple cases of thyroid autoimmunity

Background

Ophthalmopathy is a common manifestation of Graves’ disease (GD) occurring in up to 50% of patients. Mild eye signs are also common in patients with Hashimoto’s thyroiditis. Whilst a genetic predisposition to GD has been demonstrated this is not the case for the ophthalmopathy which often runs a separate course.

Objective

We determined the prevalences of eye and eyelid signs and positive thyroid and orbital antibody tests in first and second degree relatives from a single family with multiple cases of Graves’ disease, ophthalmopathy and Hashimoto’s thyroiditis.

Design

The study cohort comprised 16 subjects from the same family, 4 probands namely, 3 with GD and one with Hashimoto’s thyroiditis and hypothyroidism and 12 of their euthyroid first or second degree relatives. We measured antibodies against calsequestrin (CASQ1) and collagen XIII in an enzyme-linked-immunosorbent assays and TSH-Receptor (TSH-R) antibodies as i) TSH-R binding inhibiting immunoglobulin (TBII) and ii) thyroid stimulating immunoglobulin (TSI). Eye signs were classified and quantified using the clinical activity score (CAS), NOSPECS classes, Nunery types 1 and 2 and the margin-reflex-distance (MRD) as a measure of upper eyelid retraction (UER).

Main outcomes

Whilst significant ophthalmopathy was uncommon in the relatives, mild eye signs, in particular UER, were demonstrated in about a third of them. The presence of eye signs was moderately, but not significantly, associated with the detection of CASQ1 and collagen XIII antibodies, but not TSH-R antibodies.

Conclusion

Our study demonstrates a significant prevalence of positive orbital antibody tests and ophthalmopathy in probands with thyroid autoimmunity and their euthyroid relatives, favouring a role of genetic factors in the development of ophthalmopathy in patients with thyroid autoimmunity.

Orbital fibrosis in a mouse model of Graves' disease induced by genetic immunization of thyrotropin receptor cDNA

The TSH receptor (TSHR) is the critical target for antibody production in Graves' disease (GD). Insulin-like growth factor 1 receptor (IGF1R) has been proposed as a second autoantigen in complications of GD such as orbitopathy. We attempted to induce orbital tissue remodeling in mice undergoing immunizations with plasmids encoding TSHR and IGF1R delivered by in vivo skeletal muscle electroporation, a procedure known to give a sustained, long-term antibody response. Female BALB/c mice were challenged with TSHR A-subunit or IGF1Rα subunit plasmid by injection and electroporation. Mice challenged with TSHR A-subunit plasmid resulted in high frequency (75%) of hyperthyroidism and thyroid-stimulating antibodies. But strikingly, immunization with TSHR A-subunit plasmid also elicited antibody to IGF1Rα subunit. Mice challenged in the same manner with IGF1Rα subunit plasmid produced strong antibody responses to IGF1R, but did not undergo any changes in phenotype. Simultaneous challenge by double antigen immunization with the two plasmids in distant anatomical sites reduced the incidence of hyperthyroidism, potentially as a consequence of antigenic competition. Thyroid glands from the TSHR A-subunit plasmid-challenged group were enlarged with patchy microscopic infiltrates. Histological analysis of the orbital tissues demonstrated moderate connective tissue fibrosis and deposition of Masson's trichrome staining material. Our findings imply that immunization with TSHR A-subunit plasmid leads to generation of IGF1R antibodies, which together with thyroid-stimulating antibodies may precipitate remodeling of orbital tissue, raising our understanding of its close association with GD.

Epitopes, immunoglobulin classes and immunoglobulin G subclasses of calsequestrin antibodies in patients with thyroid eye disease

A number of serum autoantibodies are associated with thyroid eye disease (TED), including those reactive against the calcium binding protein calsequestrin (CASQ). There are two isoforms of CASQ namely; CASQ1, found in skeletal, including extra ocular, muscle, and CASQ2, found in cardiac muscle. We determined (i) the reactivity profiles of CASQ1 and CASQ2 antibodies and (ii) the immunoglobulin (Ig) classes and IgG subclasses of CASQ1 antibodies, using enzyme-linked immunosorbent assay. Of the 20 patients with TED tested, 35% were positive for CASQ1 antibodies, 25% for CASQ2 antibodies and two patients (10%) were positive for both antibodies. Of the 12 patients with Hashimoto's thyroiditis and ophthalmopathy tested, 25% were positive for CASQ1 antibodies, 42% for CASQ2 antibodies and two patients (17%) were positive for both antibodies. CASQ1 antibodies were mainly of the IgG class and IgG1 and IgG3 subclasses. These results suggest that CASQ1 and CASQ2 do not share major epitopes. Because antibodies of the IgG1 and IgG3 subclasses are cytotoxic, CASQ1 antibodies may contribute to the eye muscle damage in patients with TED. Because CASQ1 antibodies were positive in only a third of patients with active TED we are unable to draw conclusions about their role in its pathogenesis. On the other hand, a possible role of CASQ2 antibodies in the aetiology of the cardiac complications of Graves' disease is a new avenue for research and appears worthy of further investigation.

Pathogenesis of thyroid-associated ophthalmopathy: does autoimmunity against calsequestrin and collagen XIII play a role?

Thyroid-associated ophthalmopathy (TAO), or thyroid eye disease, is a complex inflammatory disorder of the eye that, as its name implies, is associated with thyroid disease. TAO can be divided into three subtypes: ocular myopathy, congestive myopathy and mixed congestive and myopathic ophthalmopathy. Although the precise pathophysiology of TAO remains unclear it is likely to reflect an autoimmune reaction involving sensitized T-cells and autoantibodies directed against a thyroid and orbital tissue shared antigen. One well studied candidate in this immune reaction is the thyroid-stimulating hormone receptor (TSH-r), expressed in the orbital fibroblast and pre adipocyte. In our studies of TAO, we have investigated the nature and significance of antibodies targeting other eye muscle and orbital connective tissue (OCT) antigens. Our findings suggest that autoimmunity against the eye muscle antigen calsequestrin and the OCT antigen collagen XIII plays a role in the pathogenesis of TAO. We propose that ocular myopathy and chronic eyelid retraction are due to autoimmunity against skeletal muscle calsequestrin in the extraocular and eyelid muscles, respectively. This may be initiated in the thyroid where calsequestrin expression is upregulated, possibly due to a stimulatory effect of TSH-r antibodies. We also propose that congestive ophthalmopathy results from a reaction against the TSH-r or collagen XIII in orbital fibroblast cell membranes. Further insight into the role of eye muscle and OCT antigens in the pathogenesis of TAO may allow for the development of new therapies to treat the eye disorder and reduce patient morbidity.

Eye and eyelid abnormalities are common in patients with Hashimoto's thyroiditis

BACKGROUND

Overt ophthalmopathy is presumed to be uncommon in patients with Hashimoto's thyroiditis compared to Graves' disease, where significant eye changes are found in approximately 40% of patients. On the other hand, when observing, more subtle eye changes, particularly upper eyelid retraction (UER) and mild inflammatory signs, may be common in patients with Hashimoto's thyroiditis.

METHODS

We have determined the prevalence and characteristics of eye signs in recently diagnosed patients with Hashimoto's thyroiditis studied prospectively since 2004 till date in Sydney (Australia). We measured serum orbital antibodies in 20 of the patients in enzyme-linked immunosorbent assay.

RESULTS

The overall prevalence of eye signs in patients with Hashimoto's thyroiditis was 34%, of whom about a quarter had chronic UER, determined as a margin-reflex distance of >5 mm, as the main sign. There was no correlation between eye signs and cigarette smoking. Overall, there was only a modest correlation between eye signs and positive antibody tests, and 40% of patients with no eye signs at the time of study were antibody positive.

CONCLUSION

Eye changes, in particular UER, are common in patients with Hashimoto's thyroiditis. Since thyroid stimulating hormone-receptor antibodies are not usually associated with Hashimoto's thyroiditis, autoimmune mediated damage of the levator palpebrae superioris (eyelid) muscle cannot be due to these antibodies. Although eyelid abnormalities may be a minor problem for most patients, for some there are major cosmetic implications requiring surgical management.

Update on the medical treatment of Graves' ophthalmopathy

PURPOSE

To review recent advances in the understanding of Graves' ophthalmopathy (GO) pathogenesis as well as discuss current and future medical management strategies.

DESIGN

Interpretive essay.

METHODS

Literature review and interpretation.

RESULTS

Medical treatment of GO has slowly evolved during the past few decades and has been hampered by a poor understanding of the disease at a cellular and molecular level. Current treatment recommendations and guidelines therefore focus on nonspecific immuno-suppression. Newer classes of treatment agents hold promise to more selectively target underlying cellular and molecular alterations in GO.

CONCLUSION

Cooperation between individual patients, physicians and between differing medical centers, together with a refined understanding of the pathogenesis of GO, will lead to newer more-effective treatments for the disease and improve patient quality of life.

Peripheral blood T lymphocyte sensitisation against calsequestrin and flavoprotein in patients with Graves' ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is an orbital autoimmune disorder of the extraocular and eyelid muscles and surrounding connective and adipose tissue. Although mononuclear cell infiltration of orbital tissue is a characteristic feature of TAO the likely role of T lymphocyte reactivity against eye muscle antigens in the initiation of eye muscle damage in TAO has not been explored in detail. Therefore, we tested for T lymphocyte sensitisation to three eye muscle antigens namely, calsequestrin, G2s and flavoprotein (Fp), in patients with Graves' ophthalmopathy (GO), Graves' hyperthyroidism (GH) without ophthalmopathy and age and sex matched normal subjects. T lymphocyte reactivity was determined in a proliferation assay, results being expressed as stimulation index (SI). Mean ( +/- SE) SI for patients with GO, but not GH without ophthalmopathy, were significantly greater than that for normal subjects for calsequestrin and Fp, but not G2s. Mean ( +/- SE) SI was also significantly increased in patients with active ophthalmopathy, but not chronic ophthalmopathy, compared to normal subjects, for calsequestrin and Fp, but not G2s. Overall, positive lymphocyte proliferation to calsequestrin was demonstrated in 59% of patients with GO and 33% of patients with GH, which was significantly greater than in normals for both groups. In conclusion, we have demonstrated significant T lymphocyte reactivity to calsequestrin and, to a lesser extent, Fp in patients with GO. Because calsequestrin is located in the cell membranes of the eye muscle cell during the myotubular stage of the cell cycle, its targeting might be the primary reaction which leads to extraocular muscle inflammation in patients with GH.

Eye signs and serum eye muscle and collagen XIII antibodies in patients with transient and progressive thyroiditis

BACKGROUND

There have been reports of the development of ophthalmopathy in patients with subacute thyroiditis (SAT) in the absence of Graves' disease and thyroid-stimulating hormone receptor (TSH-r) antibodies.

OBJECTIVE

The aim of the study was to determine the prevalences of eye and eyelid signs and positive eye muscle and collagen XIII antibody tests in patients with SAT and silent thyroiditis (ST) and in patients with Hashimoto's thyroiditis (HT) as chronic thyroiditis controls.

DESIGN

Ophthalmopathy was classified as Nunery type 1 (orbital inflammation, proptosis, without restrictive myopathy) or Nunery type 2 (with restrictive myopathy). We tested for antibodies against calsequestrin, flavoprotein (Fp), G2s, and collagen XIII in 5 patients with SAT, 6 with ST, and 11 with HT, and in 12 age- and sex-matched healthy subjects, using an optimized and standardized enzyme-linked immunosorbent assay (ELISA).

MAIN OUTCOME

At the first visit, eye signs were found in two patients with SAT, one with type 1 ophthalmopathy and one with type 2 ophthalmopathy, and in three patients with ST, two with type 1 ophthalmopathy and one with dominant upper eyelid retraction only. Later in the course of their illness, one other patient with ST developed mild type 1 disease, giving an overall prevalence of any eye signs of 50% in patients with TT. Five patients with HT had mild type 1 ophthalmopathy and dominant upper eyelid retraction. One or more eye muscle antibodies were detected in three patients with SAT, four with ST, and seven with HT, of which calsequestrin and Fp antibodies were the most commonly found. TSH-r antibodies were detected in only one patient with ST, at the time when she developed Graves' hyperthyroidism following an episode of ST.

CONCLUSION

The development of mild, but definite, ophthalmopathy or dominant upper eyelid retraction in patients with TT and chronic (Hashimoto's) thyroiditis in the absence of TSH-r antibodies or Graves' hyperthyroidism is an interesting observation that should be further addressed in larger groups of patients, including those with postpartum thyroiditis. These preliminary findings also raise questions about the mechanism for the link between ophthalmopathy and thyroid autoimmunity.

Antibodies against calsequestrin and type XIII collagen are good markers for chronic upper eyelid retraction

PURPOSE

Chronic upper eyelid retraction is a common manifestation of thyroid-associated ophthalmopathy (TAO) but can occur as a dominant feature of ophthalmopathy in patients with Graves' hyperthyroidism and in association with Hashimoto's thyroiditis in the absence of other eye signs except mild proptosis.

METHODS

We measured antibodies against calsequestrin, flavoprotein (Fp), G2s, and collagen XIII in an enzyme-linked immunosorbent assay (ELISA) in 15 patients with chronic upper eyelid retraction.

RESULTS

Calsequestrin antibodies were detected in 67% of patients with upper eyelid retraction, Fp antibodies in 47%, G2s antibodies in 20%, and collagen XIII antibodies were detected in 40% of these patients at the first visit. These prevalences were significantly greater than normal for calsequestrin and collagen XIII, but not for Fp and G2s antibodies. On follow-up, calsequestrin antibodies were detected in two more patients, for an overall prevalence of 80%. Levels of the four antibodies remained fairly constant over the study period and generally correlated with the presence and severity of upper eyelid signs.

CONCLUSIONS

These findings support the notion that autoimmune attack against calsequestrin and collagen XIII in the levator palpebrae superioris (LPS) muscle may play a role in the pathogenesis of upper eyelid retraction and that lid retraction may be the dominant feature of ophthalmopathy in patients with Hashimoto's thyroiditis and non-autoimmune thyroid disease. Because calsequestrin is an intracellular protein, the corresponding autoantibodies probably do not initiate LPS muscle inflammation but may contribute to its damage. The mix of antibodies against calsequestrin and collagen XIII may shed light on the diverse presentations found in thyroid-associated ophthalmopathy.

Susceptibility genes in Graves' ophthalmopathy: searching for a needle in a haystack?

The variety of clinical presentations of eye changes in patients with Graves' disease suggests that complex interactions between genetic, environmental, endogenous and local factors influence the development/severity of Graves' ophthalmopathy (GO). At present, the role of genetic factors in the development of GO remains unknown. Based on small case-control association studies with candidate genes, several susceptibility loci in GO have been proposed. These are human leucocyte antigen (HLA, 6p21.3), cytotoxic T-lymphocyte antigen-4 (CTLA-4, 2q33), tumour necrosis factor (TNF, 6p21.3), interferon-gamma (IFN-gamma, 12q14), intercellular adhesion molecule-1 (ICAM-1, 19p13), and thyroid stimulating hormone receptor gene (TSH-R, 14q31). Unfortunately, these results were either not confirmed or require replication in larger studies. There are many reasons for the lack of reproducibility of association studies in GO, including poor characterization of the studied groups and small sample sizes, which may result in both false positive and negative results. Thus, the genetic background of GO remains to be elucidated in future research. However, the possibility that GO may be a genetically heterogeneous disorder, or that the development of GO may be predominantly influenced by environmental factors such as cigarette smoking, can not be disregarded.

A musculoskeletal model of low grade connective tissue inflammation in patients with thyroid associated ophthalmopathy (TAO): the WOMED concept of lateral tension and its general implications in disease

Background

Low level connective tissue inflammation has been proposed to play a role in thyroid associated ophthalmopathy (TAO). The aim of this study was to investigate this postulate by a musculoskeletal approach together with biochemical parameters.

Methods

13 patients with TAO and 16 controls were examined. Erythrocyte levels of Zn, Cu, Ca²⁺, Mg, and Fe were determined. The musculoskeletal evaluation included observational data on body posture with emphasis on the orbit-head region. The angular foot position in the frontal plane was quantified following gait observation. The axial orientation of the legs and feet was evaluated in an unloaded supine position. Functional propioceptive tests based on stretch stimuli were done by using foot inversion and foot rotation.

Results

Alterations in the control group included neck tilt in 3 cases, asymmetrical foot angle during gait in 2, and a reaction to foot inversion in 5 cases. TAO patients presented facial asymmetry with displaced eye fissure inclination (mean 9.1°) as well as tilted head-on-neck position (mean 5.7°). A further asymmetry feature was external rotation of the legs and feet (mean 27°). Both foot inversion as well as foot rotation induced a condition of neuromuscular deficit. This condition could be regulated by gentle acupressure either on the lateral abdomen or the lateral ankle at the acupuncture points gall bladder 26 or bladder 62, respectively. In 5 patients, foot rotation produced a phenomenon of moving toes in the contra lateral foot. In addition foot rotation was accompanied by an audible tendon snapping. Lower erythrocyte Zn levels and altered correlations between Ca²⁺, Mg, and Fe were found in TAO.

Conclusion

This whole body observational study has revealed axial deviations and body asymmetry as well as the phenomenon of moving toes in TAO. The most common finding was an arch-like displacement of the body, i.e. eccentric position, with foot inversion and head tilt to the contra lateral side and tendon snapping. We propose that eccentric muscle action over time can be the basis for a low grade inflammatory condition. The general implications of this model and its relations to Zn and Se will be discussed.

Study of serum antibodies against three eye muscle antigens and the connective tissue antigen collagen XIII in patients with Graves' disease with and without ophthalmopathy: correlation with clinical features

OBJECTIVE

The extraocular muscles are one of the primary tissues implicated in the autoimmune-mediated inflammation of thyroid-associated ophthalmopathy (TAO). Our aim was to determine the prevalence and level of antibodies against three candidate eye muscle antigens and the orbital fibroblast membrane antigen collagen XIII, in well-characterized patient groups.

STUDY DESIGN AND PATIENTS

The study cohort consisted of patients with Graves' hyperthyroidism with and without ophthalmopathy, controls patients with other thyroid or other autoimmune disorders and healthy subjects. The presence of eye muscle antibodies was determined using an optimized and standardized enzyme-linked immunosorbent assay. We measured antibodies against (i) the 67-kDa flavoprotein (Fp) subunit of the mitochondrial enzyme succinate dehydrogenase; (ii) G2s, a 141 amino acid fragment of the winged-helix transcription factor FOXP1; (iii) calsequestrin, a 63-kDa calcium-binding protein; and (iv) collagen XIII, a connective tissue protein that is closely linked to the congestive ophthalmopathy subtype of TAO. Eye muscle antibody levels were correlated with clinical diagnosis and presence or not of ophthalmopathy.

RESULTS

Prevalences of positive antibody tests to calsequestrin (75.0%) and collagen XIII (43.8%) were significantly greater in Graves' disease (GD) patients with ophthalmopathy than in healthy subjects, whereas modest significance was demonstrated with antibodies against Fp, but not G2s. Significantly greater serum levels of antibodies against calsequestrin, G2s, and collagen XIII, but not Fp, were found in GD patients with ophthalmopathy compared to control patients without eye disease and healthy subjects.

CONCLUSIONS

Calsequestrin and collagen XIII antibodies are the most specific to TAO, whereas antibodies against G2s, and to a lesser extent Fp, are also markers of ophthalmopathy, but less reliable. These results are unique in that it is the first time the significance of a panel of three candidate eye muscle antibodies and a connective tissue antibody have been evaluated in the same patients with ophthalmopathy.