Serum antibodies to collagen XIII: a further good marker of active Graves' ophthalmopathy

Risk Factors of Thyroid Eye Disease

OBJECTIVE

To examine risk factors that might be associated with thyroid eye disease (TED) in patients with Graves' disease (GD), which may guide physicians in the prevention and management of TED.

METHODS

Medline and Embase were searched for articles discussing risk factors of TED. Comparisons were made between GD patients with and without TED, and between active and inactive TED GD patients. Weighted mean differences (WMDs) and odds ratios (ORs) were determined for continuous and dichotomous outcomes, respectively. Results were pooled with random effects using the DerSimonian and Laird model.

RESULTS

Fifty-six articles were included in the analysis. Smoking, inclusive of current and previous smoking status, was a significant risk factor for TED (OR: 2.401; CI: 1.958-2.945; P < .001). Statistical significance was found upon meta-regression between male sex and the odds of smoking and TED (β = 1.195; SE = 0.436; P = .013). Other risk factors were also examined, and patients with TED were significantly older than those without TED (WMD: 1.350; CI: 0.328-2.372; P = .010). While both age (WMD: 5.546; CI: 3.075-8.017; P < .001) and male sex (OR: 1.819; CI: 1.178-2.808; P = .007) were found to be significant risk factors for active TED patients compared to inactive TED patients, no statistical significance was found for family history, thyroid status, cholesterol levels, or body mass index.

CONCLUSION

Factors such as smoking, sex, and age predispose GD patients to TED, and TED patients to active TED. A targeted approach in the management of GD and TED is required to reduce the modifiable risk factor of smoking.

Myasthenia Gravis: Autoantibody Specificities and Their Role in MG Management

Myasthenia gravis (MG) is the most common autoimmune disorder affecting the neuromuscular junction, characterized by skeletal muscle weakness and fatigability. It is caused by autoantibodies targeting proteins of the neuromuscular junction; ~85% of MG patients have autoantibodies against the muscle acetylcholine receptor (AChR-MG), whereas about 5% of MG patients have autoantibodies against the muscle specific kinase (MuSK-MG). In the remaining about 10% of patients no autoantibodies can be found with the classical diagnostics for AChR and MuSK antibodies (seronegative MG, SN-MG). Since serological tests are relatively easy and non-invasive for disease diagnosis, the improvement of methods for the detection of known autoantibodies or the discovery of novel autoantibody specificities to diminish SN-MG and to facilitate differential diagnosis of similar diseases, is crucial. Radioimmunoprecipitation assays (RIPA) are the staple for MG antibody detection, but over the past years, using cell-based assays (CBAs) or improved highly sensitive RIPAs, it has been possible to detect autoantibodies in previously SN-MG patients. This led to the identification of more patients with antibodies to the classical antigens AChR and MuSK and to the third MG autoantigen, the low-density lipoprotein receptor-related protein 4 (LRP4), while antibodies against other extracellular or intracellular targets, such as agrin, K_v1.4 potassium channels, collagen Q, titin, the ryanodine receptor and cortactin have been found in some MG patients. Since the autoantigen targeted determines in part the clinical manifestations, prognosis and response to treatment, serological tests are not only indispensable for initial diagnosis, but also for monitoring treatment efficacy. Importantly, knowing the autoantibody profile of MG patients could allow for more efficient personalized therapeutic approaches. Significant progress has been made over the past years toward the development of antigen-specific therapies, targeting only the specific immune cells or autoantibodies involved in the autoimmune response. In this review, we will present the progress made toward the development of novel sensitive autoantibody detection assays, the identification of new MG autoantigens, and the implications for improved antigen-specific therapeutics. These advancements increase our understanding of MG pathology and improve patient quality of life by providing faster, more accurate diagnosis and better disease management.

Autoantibody Specificities in Myasthenia Gravis; Implications for Improved Diagnostics and Therapeutics

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and fatiguability of skeletal muscles. It is an antibody-mediated disease, caused by autoantibodies targeting neuromuscular junction proteins. In the majority of patients (~85%) antibodies against the muscle acetylcholine receptor (AChR) are detected, while in 6% antibodies against the muscle-specific kinase (MuSK) are detected. In ~10% of MG patients no autoantibodies can be found with the classical diagnostics for AChR and MuSK antibodies (seronegative MG, SN-MG), making the improvement of methods for the detection of known autoantibodies or the discovery of novel antigenic targets imperative. Over the past years, using cell-based assays or improved highly sensitive immunoprecipitation assays, it has been possible to detect autoantibodies in previously SN-MG patients, including the identification of the low-density lipoprotein receptor-related protein 4 (LRP4) as a third MG autoantigen, as well as AChR and MuSK antibodies undetectable by conventional methods. Furthermore, antibodies against other extracellular or intracellular targets, such as titin, the ryanodine receptor, agrin, collagen Q, K_v1.4 potassium channels and cortactin have been found in some MG patients, which can be useful biomarkers. In addition to the improvement of diagnosis, the identification of the patients' autoantibody specificity is important for their stratification into respective subgroups, which can differ in terms of clinical manifestations, prognosis and most importantly their response to therapies. The knowledge of the autoantibody profile of MG patients would allow for a therapeutic strategy tailored to their MG subgroup. This is becoming especially relevant as there is increasing progress toward the development of antigen-specific therapies, targeting only the specific autoantibodies or immune cells involved in the autoimmune response, such as antigen-specific immunoadsorption, which have shown promising results. We will herein review the advances made by us and others toward development of more sensitive detection methods and the identification of new antibody targets in MG, and discuss their significance in MG diagnosis and therapy. Overall, the development of novel autoantibody assays is aiding in the more accurate diagnosis and classification of MG patients, supporting the development of advanced therapeutics and ultimately the improvement of disease management and patient quality of life.

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.

Relationship between Clinical and Immunological Features of Thyroid Autoimmunity and Ophthalmopathy during Pregnancy

Problem. Clinical features of Graves' hyperthyroidism (GH) generally improve during pregnancy and rebound in the postpartum period. It is unclear whether the ophthalmopathy that is associated with GH and, less often, Hashimoto's thyroiditis (HT) changes in parallel with the thyroid associated antibody reactions and clinical features or runs a different course. Method of Study. We retrospectively studied 19 patients with autoimmune thyroid disease over 22 pregnancies: 9 pregnancies with GH and 13 with HT. Ophthalmopathy was defined by NOSPECS class. Results. Thyroid peroxidase (TPO) and thyroglobulin (Tg) antibody titres decreased during pregnancy and rose in the postpartum period. During pregnancy, 5 patients with GH and 4 patients with HT developed mild ophthalmopathy and two patients with GH and HT developed new upper eyelid retraction (UER). In the postpartum period, eye scores improved in 3 patients with GH and 3 with HT, remained stable in two and 5 patients, respectively, and worsened in 2 patients with GH and one with HT. Conclusions. In patients with mild to moderate eye signs associated with GH and HT, the orbital and thyroid reactions ran different courses during pregnancy. Since no patient had severe ophthalmopathy, we cannot draw definitive conclusions from this preliminary study.

Thyroid-stimulating immunoglobulins as measured in a reporter bioassay are not detected in patients with Hashimoto's thyroiditis and ophthalmopathy or isolated upper eyelid retraction

Although ophthalmopathy is mainly associated with Graves' hyperthyroidism, milder eye changes are also found in about 25% of patients with Hashimoto's thyroiditis (HT). The recent finding of negative thyrotropin receptor (TSHR) antibodies, as measured in the Thyretain™ thyroid-stimulating immunoglobulin (TSI) reporter bioassay, in patients with euthyroid Graves' disease raises the possibility that TSHR antibodies are not the cause of ophthalmopathy in all situations. Here, we have tested serum from patients with HT with and without ophthalmopathy or isolated upper eyelid retraction (UER) for TSHR antibodies, using the TSI reporter bioassay and collagen XIII as a marker of autoimmunity against the orbital fibroblast. Study groups were 23 patients with HT with ophthalmopathy, isolated UER, or both eye features and 17 patients without eye signs. Thyretain™ TSI results were expressed as a percentage of the sample-to-reference ratio, with a positive test being taken as a sample-to-reference ratio of more than 140%. Serum collagen XIII antibodies were measured in standard enzyme-linked immunosorbent assay. TSI tests were positive in 22% of patients with HT with no eye signs but in no patient with eye signs. In contrast, TSI tests were positive in 94% of patients with Graves' ophthalmopathy. Tests were negative in all normal subjects tested. Collagen XIII antibodies were detected in 83% of patients with ophthalmopathy, UER, or both eye features, but in only 30% of patients with no eye signs. Our findings suggest that TSHR antibodies do not play a major role in the pathogenesis of ophthalmopathy or isolated UER in patients with HT. Moreover, the role of TSHR antibodies in the development of ophthalmopathy in patients with Graves' disease remains to be proven. In contrast, collagen XIII antibodies appear to be a good marker of eye disease in patients with HT.

Serum LAIR-2 is increased in autoimmune thyroid diseases

Leukocyte-associated Ig-like receptor (LAIR) is a small family-receptor able to inhibit immune cell function via collagen binding. It exists as both membrane-bound and soluble forms. LAIR-1 functions as an inhibitory receptor on natural killer cells, T lymphocytes and monocytes. In addition to LAIR-1, the human genome encodes LAIR-2, a soluble homolog. Several studies have focused on LAIR-1, whereas few investigations concentrate on the expression and function of LAIR-2. We demonstrate the presence of high LAIR-2 levels in 74/80 sera from patients with autoimmune thyroid diseases (both Graves’ disease and autoimmune thyroiditis). LAIR-2 levels seemed not to be related to specific clinical manifestations, such as thyroid functions (hypo- or hyperthyroidism), or specific clinical features (such as ophtalmopathy). In addition, serum LAIR-2 is able, in vitro, to bind its natural ligand, collagen. Since LAIR-2 has been found to have higher affinity for collagens than LAIR-1 did, we hypothesize a potential regulating capability of serum LAIR-2 in finally regulating the inhibitory capability of LAIR-1.

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.

Collagen XIII: a type II transmembrane protein with relevance to musculoskeletal tissues, microvessels and inflammation

Collagen XIII and the homologous collagens XXIII and XXV form a subgroup of type II transmembrane proteins within the collagen superfamily. Collagen XIII consists of a short cytosolic domain, a transmembrane domain and a large extracellular ectodomain, which may be shed into the pericellular matrix. It has been proposed that collagen XIII may function as an adhesion molecule, due to its cellular localization at focal contacts, numerous interactions with basement membrane (BM) and other extracellular matrix (ECM) proteins and expression at various cell-cell and cell-matrix junctions. Recent in vivo studies highlight its involvement in the development, differentiation and maturation of musculoskeletal tissues and vessels and in maintaining tissue integrity.

Rituximab treatment in patients with active Graves' orbitopathy: effects on proinflammatory and humoral immune reactions

In active Graves' orbitopathy (GO), proinflammatory cytokines predominate. Circulating thyroid stimulating hormone (TSH)-receptor antibodies (TRAb) have been correlated with GO clinical activity and severity. In preliminary studies rituximab (RTX), an anti-CD 20 monoclonal antibody, has induced clinical improvement of active GO without a change in serum anti-thyroid antibodies. We have studied whether RTX in GO acts by affecting proinflammatory cytokines and thyroid and orbital-directed antibodies. Ten patients with GO were treated with RTX, administered twice intravenously (i.v.) (1000 mg) at days 1 and 15, and 20 with methylprednisolone, administered weekly i.v. (500 mg), for 16 weeks. Patients were studied before treatment, at B cell depletion and at 4, 8, 16, 20, 30 and 50 weeks. Peripheral lymphocytes, serum interleukin (sIL)-6, sIL-6r, chemokine (C-X-C motif) ligand 10 (CXCL10), TRAb and stimulating antibodies (TSAb) and autoantibodies against orbital calsequestrin, collagen XIII and flavoprotein subunit of succinate dehydrogenase (FP-SDH) were measured at baseline and after treatment. Serum IL-6 and sIL-6R concentrations did not change after RTX [P = not significant (n.s.)]. Serum CXCL10 increased after RTX at B cell depletion and at 30 weeks (P < 0·003). Serum TSAb did not change in relation to TRAb, nor did antibodies against orbital antigens (P = n.s.). In conclusion, this study shows that RTX in GO does not affect humoral reactions. The observed increase of serum CXCL10 concentrations at B cell depletion may result from cell lysis. We suggest that RTX may exert its effect in GO by inhibiting B cell antigen presentation.

Targeted biological therapies for Graves' disease and thyroid-associated ophthalmopathy. Focus on B-cell depletion with Rituximab

Based on experience from the treatment of other autoimmune diseases and because of the limitations imposed by existing therapeutic options for Graves' disease (GD) and thyroid-associated ophthalmopathy (TAO), rituximab (RTX) was recently proposed as a novel therapy option. Here, we summarize the rationale for using RTX; give an overview of the possible mechanisms of action; and give an account of its effects and side-effects when used in GD and TAO. Scant evidence, originating from only a few methodologically inhomogeneous studies, suggests that RTX may prolong remission for hyperthyroidism over that seen with antithyroid drugs, at least in mild GD. Furthermore, in patients with TAO, who are unresponsive to conventional immunosuppressive therapy, RTX seems efficacious. As we wait for larger-scale randomized studies, RTX, should be considered experimental and reserved for patients who do not respond favourably to conventional therapy. It is the first in what is likely to be a series of new and emerging treatments specifically targeting relevant components of the immune system. Further studies will hopefully lead to improved and better tailored, individualized therapy for GD and especially TAO.

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.

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.

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.

Collagen XXIII expression is associated with prostate cancer recurrence and distant metastases

PURPOSE

We had previously identified a new transmembrane collagen, type XXIII, in metastatic rat prostate carcinoma cells. The purpose of this study was to determine the expression of collagen XXIII in human prostate cancer and investigate its relationship with disease progression.

EXPERIMENTAL DESIGN

We investigated collagen XXIII expression in prostate cancer tissue and did a retrospective analysis of association with prostate-specific antigen (PSA)-defined disease recurrence. The presence of collagen XXIII in prostate cancer patient urine was also assessed before and after prostatectomy.

RESULTS

Collagen XXIII protein was detected at very low levels in benign prostate tissue and was significantly increased in prostate cancer. Distant metastases exhibited significantly higher collagen XXIII levels compared with either localized prostate cancer or regional (lymph node) metastases. Patients with high collagen XXIII levels had a 2.8-fold higher risk of PSA failure with median time to failure of 8.1 months, compared with low collagen XXIII patients with a median time to failure of 5 years. Multivariate Cox regression showed that the presence of collagen XXIII was significantly associated with time to PSA recurrence, independent of other clinical variables. Collagen XXIII was also detected in prostate cancer patient urine, with reduced levels after prostatectomy, indicating potential as a noninvasive fluid biomarker.

CONCLUSIONS

We present the first report demonstrating increased collagen XXIII expression in prostate cancer tissue. We show that collagen XXIII level is a significant independent predictor of PSA-defined disease recurrence, suggesting a potential role as a molecular biomarker of prostate cancer progression and metastasis.

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.

Immunohistochemical studies using immunized Guinea pig sera with features of anti-human thyroid, eye and skeletal antibody and Graves' sera

Type 2 5' deiodinase enzyme was observed in both thyroid and eye muscle tissues, highlighting its possible role as a common antigen in thyroid-associated ophthalmopathy. Sera of 105 Graves' patients and 40 controls, and immunized guinea pig sera against TCSS peptide, showing homology to the amino acid sequence from 132 to 152 of type 2 5' deiodinase, were investigated to demonstrate the binding effects to human thyroid, eye and skeletal muscle tissues. Twenty-two Graves' patients were positive for anti-TCSS peptide antibodies, of whom 18 cases had ophthalmopathy. The levels of anti-TCSS peptide antibodies were higher not only in Graves' patients with (P<0.0001) and without (P<0.036) eye symptoms compared to controls but also the difference was significant between patients with and without ophthalmopathy (P<0.049). In Western blot, immunized sera showed binding reactions to the supernatant fractions of human thyroid, eye and skeletal muscle tissues at the range of 29 kDa. Patient sera with Graves' ophthalmopathy resulted in positive reactions directed to membrane areas in thyroid follicular cells, and to fibers in eye and skeletal muscles using immunohistochemical method, while no positive staining was present after adding control sera. The binding features of immunized guinea pig sera exhibited similar staining in all human tissues but could be blocked with Graves' sera. Our results suggest that type 2 5' deiodinase enzyme protein could play a role as an antigen in Graves' disease. Immunized guinea pig sera against TCSS peptide exhibited similar binding reactions and stainings to human thyroid, eye and skeletal muscle tissues as patient sera with Graves' ophthalmopathy.

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.

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

We have identified several eye muscle antigens and studied the significance of the corresponding serum autoantibodies in patients with Graves' disease. Of these antigens, only calsequestrin is expressed more in eye muscle than other skeletal muscles, which could explain at least partly the specific involvement of eye muscle in patients with Graves' disease. Earlier, we found a modest relationship between anti-calsequestrin antibodies and ophthalmopathy, but in that study we used calsequestrin prepared from rabbit heart muscle and measured antibodies by immunoblotting. We have reinvestigated the prevalences of anti-calsequestrin antibodies in larger groups of well-characterized patients with thyroid autoimmunity with and without ophthalmopathy and control patients and healthy subjects, using standard enzyme-linked immunosorbent assay incorporating highly purified rabbit skeletal muscle calsequestrin, which has a 97% homology with human calsequestrin, as antigen. Anti-calsequestrin antibodies were detected in 78% of patients with active congestive ophthalmopathy, in 92% of those with active inflammation and eye muscle involvement, but in only 22% of patients with chronic, 'burnt out' disease. Tests were also positive in 5% of patients with Graves' hyperthyroidism without evident ophthalmopathy (two patients) and one patient with 'watery eyes' but no other clear signs of congestive ophthalmopathy and IgA nephropathy and no known thyroid disease, but in no patient with Hashimoto's thyroiditis, toxic nodular goitre, non-toxic multi-nodular goitre or diabetes, or age- and sex-matched healthy subjects. In serial studies of all 11 patients with Graves' hyperthyroidism who had active ophthalmopathy at the time of the first clinic visit, or developed eye signs during the first 6 months, and positive anti-calsequestrin antibodies in at least one sample, anti-calsequestrin antibodies correlated with the onset of ocular myopathy in six patients. Antibodies targeting calsequestrin appear to be specific markers for ophthalmopathy and sensitive indicators of the ocular myopathy subtype of ophthalmopathy in patients with thyroid autoimmunity. However, these results must be considered preliminary until a large prospective study of patients with newly diagnosed Graves' hyperthyroidism, in which serum levels of calsequestrin antibodies are correlated with clinical changes and orbital eye muscle and connective tissue/fat volumes, has been carried out.

New insights into antibody-mediated hyperthyroidism

The most common cause of hyperthyroidism is Graves' disease, which represents a typical example of an organ-specific autoimmune condition. The exact triggers for the disease remain unknown, but are likely to involve a complex interaction between multiple environmental factors in a genetically predisposed individual. The main feature of the condition is the presence of thyroid-stimulating antibodies, which activate the thyroid- stimulating hormone receptor, resulting in hyperthyroidism. These antibodies may also be involved in the extrathyroidal complications of the disease. The recent generation of thyroid-stimulating antibodies in animal models and the isolation of monoclonal thyroid-stimulating antibodies from a patient with Graves' disease should allow the detailed study of thyroid-stimulating antibodies-thyroid-stimulating hormone receptor interactions. This will help to shed more light on disease pathogenesis and may offer new treatment strategies in difficult cases, particularly in patients with extrathyroidal complications.