Unlocking the immunological mechanisms of orbital inflammation in thyroid eye disease

Statins and thyroid eye disease (TED): a systematic review

PURPOSE

Thyroid eye disease (TED) is the foremost extrathyroidal manifestation of Graves' disease (GD). Currently, available treatments do not entirely prevent the long-term consequences of TED and have distinct disadvantages. Therefore, this systematic review explored available evidence regarding the efficacy of statins in preventing and treating TED.

METHODS

Relevant studies investigating statin usage in patients with GD or TED were identified by searching Medline (Pubmed and Ovid), Scopus, Web of Science, ProQuest, and Cochrane Library databases (from the database inception to September 2023). The review was done according to the PRISMA statement. Web searching was done independently by two investigators. Two researchers independently extracted the data, and any disagreement was adjudicated by consensus. Based on the study design, the studies' quality appraisal was done using the Newcastle-Ottawa Scale (NOS) and Version 2 of the Cochrane risk-of-bias tool (RoB2).

RESULTS

The literature search identified 145 publications, of which four met the inclusion criteria (Three retrospective cohort studies and one randomized clinical trial) and were reviewed in full text. The two retrospective cohort studies demonstrated the beneficial effects of statins on TED in newly diagnosed GD Stein et al. showed that statins, regardless of the type, prevent or delay TED (HR: 0.74 (0.65-0.84)), especially in men or treatment duration of more than one year. Nilsson et al. fascinatingly revealed that at least 60 days of statin usage in the preceding year could decrease the risk of TED development by around 40%. One RCT showed a higher treatment response for active moderate-to-severe TED in patients with hypercholesterolemia who took atorvastatin 20 mg in addition to ivGC for 24 weeks without any increase in serious side effects. The retrospective study revealed that the need for reconstructive surgery was reduced in patients with severe TED who received statin therapy.

CONCLUSION

Statin therapy could be a potential adjunctive modality for preventing and treating TED.

TRIAL REGISTRATION

PROSPERO registration number: CRD42022315522.

Immune Checkpoints and Graves' Disease, Thyroid Eye Disease, and Orbital Myopathy: A Comprehensive Review

Immune checkpoints (ICPs) are essential regulators of the immune system, ensuring a delicate balance between self-tolerance and autoimmune responses. ICP therapy is a rapidly growing cancer treatment strategy that inhibits the interaction between ICPs and their ligands. This biological interaction increases the ability of the immune system in combating cancer. However, in some cases, the use of these agents may lead to immune hyperactivity and, subsequently, autoimmune diseases. Graves' disease (GD), thyroid eye disease (TED), and orbital myopathy are complex autoimmune disorders characterized by the production of autoantibodies. The emergence of these treatment-related adverse events underscore the critical need for a deeper understanding of the immune-checkpoint axis in autoimmune diseases. In this review article, we provide a comprehensive survey of the biological mechanisms of ICPs that are most frequently targeted in cancer therapy, including CTLA-4, PD-1, PDL-1, and LAG3. Furthermore, we investigate the latest scientific findings on the adverse events associated with the inhibition of these ICPs. This paper will particularly focus on the potential risks these complications pose to ocular and orbital tissues, which are a concern in the context of cancer treatment.

Effect of orbital decompression surgery on the choroidal profile in patients with thyroid eye disease

This study aimed to investigate the effect of orbital wall decompression surgery and reduction of proptosis on the choroidal vascularity index (CVI) and subfoveal choroidal thickness (SFCT) in patients with thyroid eye disease (TED). Fifty-one eyes from 38 patients with controlled TED and proptosis were enrolled in this study. The majority of the patients (50.9%) had a clinical activity score (CAS) of zero, and none had a CAS greater than 2. The patients underwent a complete baseline ophthalmologic examination, and their choroidal profile alterations were monitored using enhanced depth imaging optical coherence tomography (EDI-OCT) before and during the three months after surgery. Changes in SFCT, luminance area (LA), total choroidal area (TCA), and the choroidal vascularity index (CVI) were measured as the ratio of LA to TCA in EDI-OCT images. The participants had an average age of 46.47 years, and 22 were female (57.9%). The SFCT of the patients exhibited a significant reduction over the follow-up period, decreasing from 388 ± 103 to 355 ± 95 µm in the first month (p < 0.001) and further decreasing to 342 ± 109 µm by the third month compared to baseline (p < 0.001). The CVI exhibited a drop from 0.685 ± 0.037 at baseline to 0.682 ± 0.035 and 0.675 ± 0.030 at 1 and 3 months post-surgery, respectively. However, these changes were not statistically significant, indicating comparable decreases in both LA and TCA. There was a significant correlation between improved proptosis and reduction in SFCT (p < 0.001) but not with CVI (p = 0.171). In conclusion, during the three months of follow-up following orbital wall decompression, CVI did not change, while SFCT reduced significantly. Additionally, SFCT was significantly correlated with proptosis reduction, whereas CVI was not.

GSDMD mediated pyroptosis induced inflammation of Graves' orbitopathy via the NF-κB/ AIM2/ Caspase-1 pathway

Gasdermin D (GSDMD) is a key executor which triggers pyroptosis as well as an attractive checkpoint in various inflammatory and autoimmune diseases but it has yet to prove its function in Graves'orbitopathy (GO). Our aim was to investigate GSDMD levels in orbital connective tissue and serum of GO patients and then assess the association between serum levels and patients' clinical activity score (CAS). Further, GSDMD-mediated pyroptosis and the underlying mechanism in inflammatory pathogenesis in the cultured orbital fibroblasts (OFs) of GO patients were examined. OFs were collected after tumor necrosis factor (TNF)-α or interferon (IFN)-γ treatment or combination treatment at different times, and the expression of GSDMD and related molecular mechanisms were analyzed. Then, we constructed the GSDMD knockout system with siRNA and the system was further exposed to the medium with or without IFN-γ and TNF-α for a specified time. Finally, we evaluated the production of interleukin (IL)-1β and IL-18. We found that serum GSDMD levels were elevated and positively correlated with the CAS in GO patients. Meanwhile, the expression of GSDMD and N-terminal domain (NT-GSDMD) in orbital connective tissue of GO patients was augmented. Also, increased expression of GSDMD and related pyroptosis factors was observed in vitro model of GO. We further demonstrated that GSDMD-mediated pyroptosis induced inflammation via the nuclear factor kB (NF-κB)/absent in melanoma-2 (AIM-2)/caspase-1 pathway. In addition, blocking GSDMD suppressed proinflammatory cytokine production in GO. We concluded that GSDMD may be a biomarker as well as a potential target for the evaluation and treatment of inflammation related with GO.

Morbihan disease misdiagnosed as senile blepharoptosis and successfully treated with short-term minocycline and ketotifen: A case report

BACKGROUND

Morbihan disease is a rare skin condition with diagnostic and therapeutic challenges. Facial nonpitting erythematous edema is usually considered to be a characteristic manifestation and diagnostic clue for the Morbihan disease. Treatment of Morbihan disease remains a dilemma due to its long course, poor response, and high recurrence rate.

CASE SUMMARY

We report the case of a 69-year-old man with Morbihan disease. The patient presented ptosis as the first and main symptom. There was no obvious edema or other skin lesions. The patient was misdiagnosed with senile blepharoptosis based on eyelid performance and no treatment was administered to him. After continuous progressive asthenia of eye-opening and ptosis for more than one year, a skin biopsy was recommended. Histopathological analysis showed edema in the dermis, lymphatic hyperplasia and dilatation, and perivascular lymphocytic infiltration. An obvious increase in toluidine blue-stained mast cells was observed. The patient was finally diagnosed with Morbihan disease. Minocycline and ketotifen were prescribed based on the increase of mast cells in skin tissue slices. The patient experienced rapid relief seven days later and complete remission after 40 d from the commencement of the treatment.

CONCLUSION

Ptosis without obvious swelling could be the only or main clinical manifestation of Morbihan disease in rare conditions. An increase of mast cells was an important therapeutic clue to the rapid and remarkable efficiency of the combination therapy of minocycline and antihistamine.

Cytokines as Targets of Novel Therapies for Graves' Ophthalmopathy

Graves' disease (GD) is an organ-specific autoimmune disorder of the thyroid, which is characterized by circulating TSH-receptor (TSH-R) stimulating antibodies (TSAb), leading to hyperthyroidism. Graves' ophthalmopathy (GO) is one of GD extra-thyroidal manifestations associated with the presence of TSAb, and insulin-like growth factor-1 receptor (IGF-1R) autoantibodies, that interact with orbital fibroblasts. Cytokines are elevated in autoimmune (i.e., IL-18, IL-6) and non-autoimmune hyperthyroidism (i.e., TNF-α, IL-8, IL-6), and this could be associated with the chronic effects of thyroid hormone increase. A prevalent Th1-immune response (not related to the hyperthyroidism per se, but to the autoimmune process) is reported in the immune-pathogenesis of GD and GO; Th1-chemokines (CXCL9, CXCL10, CXCL11) and the (C-X-C)R3 receptor are crucial in this process. In patients with active GO, corticosteroids, or intravenous immunoglobulins, decrease inflammation and orbital congestion, and are considered first-line therapies. The more deepened understanding of GO pathophysiology has led to different immune-modulant treatments. Cytokines, TSH-R, and IGF-1R (on the surface of B and T lymphocytes, and fibroblasts), and chemokines implicated in the autoimmune process, are possible targets of novel therapies. Drugs that target cytokines (etanercept, tocilizumab, infliximab, adalimumab) have been tested in GO, with encouraging results. The chimeric monoclonal antibody directed against CD20, RTX, reduces B lymphocytes, cytokines and the released autoantibodies. A multicenter, randomized, placebo-controlled, double-masked trial has investigated the human monoclonal blocking antibody directed against IGF-1R, teprotumumab, reporting its effectiveness in GO. In conclusion, large, controlled and randomized studies are needed to evaluate new possible targeted therapies for GO.

Usefulness of two-point Dixon T2-weighted imaging in thyroid-associated ophthalmopathy: comparison with conventional fat saturation imaging in fat suppression quality and staging performance

OBJECTIVE

To compare the two-point Dixon T₂ weighted imaging (T₂WI) with conventional fat-sat T₂WI in fat suppression (FS) quality and staging performance for patients with TAO.

METHODS

We enrolled 37 thyroid-associated ophthalmopathy (TAO) patients and 15 healthy controls who underwent both coronal two-point Dixon and fat-sat T₂WI. Qualitative (overall imaging quality, FS uniformity) and quantitative [signal intensity ratio of extraocular muscle (EOM-SIR)] parameters were assessed between the two-point Dixon T₂WI and fat-sat T₂WI. Additionally, water fraction of intraorbital fat (IF-WF) was measured on Dixon image. Dixon-EOM-SIR, Fat-sat-EOM-SIR and Dixon-IF-WF values were compared between active and inactive TAO groups, and the diagnostic efficiency for the active phase were evaluated.

RESULTS

Two-point Dixon T₂WI showed significantly higher overall image quality score, FS uniformity score as well as EOM-SIR value than fat-sat T₂WI in both TAO and control groups (all p < 0.05). Active TAOs had significantly higher Dixon-EOM-SIR (p < 0.001), Fat-sat-EOM-SIR (p < 0.001) and Dixon-IF-WF (p = 0.001) than inactive TAOs. ROC curves analyses indicated that Dixon-EOM-SIR ≥3.32 alone demonstrated the highest staging sensitivity (75.0%). When integrating Dixon-EOM-SIR ≥3.32 and Dixon-IF-WF ≥0.09, improved staging efficiency and specificity could be achieved (area under the curve, 0.872; specificity, 97.1%).

CONCLUSION

Compared with conventional fat-sat technique, two-point Dixon T₂WI offers better image quality, as well as improved staging sensitivity and specificity for TAO. Dixon T₂WI is suggested to be used to evaluate the patients with TAO in clinical practice.

ADVANCES IN KNOWLEDGE

Two-point Dixon T₂WI offers better image quality than fat-sat T₂WI. Dixon-EOM-SIR alone demonstrated the highest staging sensitivity. Combining with Dixon-IF-WF showed improved staging efficiency and specificity. Dixon T₂WI is suggested to be used to evaluate TAO patients in clinical practice.

Thyroid-Associated Orbitopathy: Evaluating Microstructural Changes of Extraocular Muscles and Optic Nerves Using Readout-Segmented Echo-Planar Imaging-Based Diffusion Tensor Imaging

Objective

We aimed to investigate the ability of readout-segmented echo-planar imaging (rs-EPI)-based diffusion tensor imaging (DTI) in assessing the microstructural change of extraocular muscles (EOMs) and optic nerves in patients with thyroid-associated orbitopathy (TAO) as well as in evaluating disease activity.

Materials and Methods

We enrolled 35 TAO patients and 22 healthy controls (HCs) who underwent pre-treatment rs-EPI-based DTI. Mean, axial, and radial diffusivity (MD, AD, and RD) and fractional anisotropy (FA) of the medial and lateral EOMs and optic nerve for each orbit were calculated and compared between TAO and HC groups and between active and inactive TAO groups. Factors such as age, sex, disease duration, mediation, and smoking history between groups were also compared. Logistic regression analysis was used to evaluate the predictive value of significant variables for disease activity.

Results

Disease duration was significantly shorter in active TAOs than in inactive ones (p < 0.001). TAO patients showed significantly lower FA and higher MD, AD, and RD than HCs for both medial and lateral EOMs (p < 0.001), but not the AD value of lateral EOMs (p = 0.619). Active patients had significantly higher FA, MD, and AD than inactive patients for medial EOMs (p < 0.005), whereas only FA differed significantly in the lateral EOMs (p = 0.018). The MD, AD, and RD of optic nerves were significantly lower in TAO patients than HCs (p < 0.05), except for FA (p = 0.129). Multivariate analysis showed that the MD of medial EOMs and disease duration were significant predictors for disease activity. The combination of these two parameters showed optimal diagnostic efficiency for disease activity (area under the curve, 0.855; sensitivity, 68.4%; specificity, 96.9%).

Conclusion

rs-EPI-based DTI is promising in assessing microstructural changes of EOMs and optic nerves and can help to indicate the disease activity of TAO, especially through the MD of medial EOMs.

Protein tyrosine phosphatase 1B as a therapeutic target for Graves' orbitopathy in an in vitro model

Graves' orbitopathy (GO) is characterised in early stages by orbital fibroblast inflammation, which can be aggravated by oxidative stress and often leads to fibrosis. Protein tyrosine protein 1B (PTP1B) is a regulator of inflammation and a therapeutic target in diabetes. We investigated the role of PTP1B in the GO mechanism using orbital fibroblasts from GO and healthy non-GO subjects. After 24 hours of transfection with PTPN1 siRNA, the fibroblasts were exposed to interleukin (IL)-1β, cigarette smoke extract (CSE), H2O2, and transforming growth factor (TGF)-β stimulations. Inflammatory cytokines and fibrosis-related proteins were analysed using western blotting and/or enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) release was detected using an oxidant-sensitive fluorescent probe. IL-1β, tumor necrosis factor (TNF)-α, bovine thyroid stimulating hormone (bTSH), high-affinity human stimulatory monoclonal antibody of TSH receptor (M22), and insulin-like growth factor-1 (IGF-1) significantly increased PTP1B protein production in GO and non-GO fibroblasts. PTPN1 silencing significantly blocked IL-1β-induced inflammatory cytokine production, CSE- and H2O2-induced ROS synthesis, and TGF-β-induced expression of collagen Iα, α-smooth muscle actin (SMA), and fibronectin in GO fibroblasts. Silencing PTPN1 also decreased phosphorylation levels of Akt, p38, and c-Jun N-terminal kinase (JNK) and endoplasmic reticulum (ER)-stress response proteins in GO cells. PTP1B may be a potential therapeutic target of anti-inflammatory, anti-oxidant and anti-fibrotic treatment of GO.

High-Mobility Group Box 1 Is Associated with the Inflammatory Pathogenesis of Graves' Orbitopathy

Background: High-mobility group box 1 (HMGB1) has been implicated in the pathogenesis of inflammatory autoimmune diseases. This study investigated the influence and mechanisms of HMGB1 in Graves' orbitopathy (GO). Methods: HMGB1 and its receptors (receptor for advanced glycation end products [RAGE], Toll-like receptor [TLR] 2, and TLR4) mRNA levels were evaluated by real-time polymerase chain reaction (RT-PCR) in GO and non-GO orbital tissues. The mRNA expressions of HMGB1 and its receptors were evaluated in primary cultured orbital fibroblasts from six GO patients and five healthy control subjects under interleukin (IL)-1β or tumor necrosis factor (TNF)-α stimulation using RT-PCR. HMGB1 secretions under IL-1β or TNF-α stimulation were evaluated by enzyme-linked immunosorbent assay (ELISA). The effects of an anti-HMGB1 antibody, RAGE antagonist (FPS-ZM1), and anti-TLR2 antibody on the expressions of IL-1β or TNF-α induced pro-inflammatory cytokines and phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells were evaluated using ELISA and Western blot analysis, respectively. The plasma levels of HMGB1 were compared among patients with active GO (n = 51), inactive GO (n = 48), Graves' disease without GO (n = 30), and healthy control subjects (n = 46) by ELISA. Results: The genes encoding HMGB1 and its receptors, as well as HMGB1 protein expression, were increased in GO orbital tissues compared to non-GO tissues. IL-1β and TNF-α stimulation increased the mRNA levels of HMGB1, RAGE, and TLR2 and the secretion of HMGB1 protein further in GO cells. Anti-HMGB1 antibody, FPS-ZM1, and anti-TLR2 antibody reduced IL-1β- or TNF-α-induced production of pro-inflammatory cytokines and phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells. The plasma levels of HMGB1 were highly increased in patients with active GO, and were significantly correlated with the clinical activity score (r = 0.566, p = 0.002) and levels of thyrotropin binding inhibitory immunoglobulin (r = 0.506, p < 0.001). Conclusions: This study demonstrates an association of HMGB1 and its receptors in the inflammatory mechanisms of GO. HMGB1, RAGE, and TLR2 blockers reduced the production of pro-inflammatory molecules, providing a rationale for blocking the HMGB1 pathway to treat patients with GO. HMGB1 proteins were secreted further in the plasma of patients with active GO, suggesting that HMGB1 can be used as a biomarker of GO activity.

The effect of oral statin therapy on strabismus in patients with thyroid eye disease

BACKGROUND

Statins, known to possess anti-inflammatory characteristics, have recently been identified as potentially reducing the risk of developing thyroid eye disease (TED) in Graves disease patients. The current study investigates the effect of oral statin therapy on strabismus related to TED.

METHODS

This is a retrospective review of patients with a diagnosis of both TED and restrictive strabismus. Oral statin users and nonusers were analyzed for smoking status, previous radioactive iodine, thyroidectomy, number of decompressions, motility restriction, amount of strabismus, number of surgeries, surgical dose, and number of muscles involved on radiography.

RESULTS

Thirty patients (average age, 63.9 years; 50% male; 59% current/former smokers) were included: 12 statin users and 18 nonusers. Statin users averaged fewer decompressions (1.3 in users vs 2.4 in nonusers [P = 0.04]). Statin users on average had 15 mm of total strabismus surgery compared with 21.4 mm in the nonuser group (P = 0.09) and had fewer muscles involved radiographically (4.3 vs 5.1 [P = 0.08]) CONCLUSIONS: Compared to nonusers, statin users tended to have fewer decompressions, less restriction, fewer surgeries, and fewer muscles involved despite having more current smokers (36% vs 5%), more males, more RAI, and fewer thyroidectomies, all of which are associated with worse TED. In our cohort of patients with TED and strabismus, statin therapy significantly reduced the number of orbital decompressions. Oral statin therapy also trended toward reducing the number and amount of strabismus surgeries as well as radiographic indication of muscle involvement, although these did not meet statistical significance.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Orbital Fat Volumetry and Water Fraction Measurements Using T2-Weighted FSE-IDEAL Imaging in Patients with Thyroid-Associated Orbitopathy

BACKGROUND AND PURPOSE

The quantitative evaluation of orbital fat proliferation and edema and the assessment of extraocular muscles are useful for diagnosing and monitoring thyroid-associated orbitopathy. To evaluate therapy-induced quantitative changes in the orbital fat of patients with thyroid-associated orbitopathy, we performed volumetric and water fraction measurements by using T2-weighted FSE iterative decomposition of water and fat with echo asymmetry and least-squares estimation (FSE-IDEAL) imaging.

MATERIALS AND METHODS

Orbital FSE-IDEAL images of 30 volunteers were acquired twice within 1 week. Nine patients with thyroid-associated orbitopathy underwent FSE-IDEAL imaging before and after methylprednisolone pulse therapy, and the treatment results were assessed by using their pre- and post-methylprednisolone pulse therapy clinical activity scores. We performed volumetric and water fraction measurements of orbital fat by using FSE-IDEAL imaging and evaluated interscan differences in the volunteers. In patients with thyroid-associated orbitopathy, we compared pre- and posttherapy orbital fat measurements and assessed the correlation between the pretherapy values and clinical activity score improvement.

RESULTS

The reproducibility of results obtained by the quantitative evaluation of orbital fat in volunteers was acceptable. After methylprednisolone pulse therapy, the water fraction in the orbital fat of patients with thyroid-associated orbitopathy was significantly decreased (P < .001). There was a significant positive correlation between the pretherapy water fraction and clinical activity score improvement (right, r = 0.82; left, r = 0.79) and a significant negative correlation between the pretherapy volume and clinical activity score improvement (bilateral, r = -0.84).

CONCLUSIONS

Volumetric and water fraction measurements of orbital fat by using FSE-IDEAL imaging are feasible and useful for monitoring the effects of therapy and for predicting the response of patients with thyroid-associated orbitopathy to methylprednisolone pulse therapy.

Diagnosis and stage of Graves' ophthalmopathy: Efficacy of quantitative measurements of the lacrimal gland based on 3-T magnetic resonance imaging

The aim of the present study was to determine the efficacy of quantitative measurements of the lacrimal gland based on 3-T magnetic resonance (MR) imaging in the diagnosis and staging of Graves' ophthalmopathy (GO). The study retrospectively enrolled 33 patients with GO (the GO group) and 24 healthy volunteers [the healthy control (HC) group] with orbit MR imaging performed using a 3-T MR scanner. Quantitative parameters of the lacrimal gland, including axial length, axial width, axial area, coronal length, coronal width, coronal area, volume and signal intensity ratio (SIR) of the lacrimal gland to the ipsilateral temporal muscle were measured. The difference of quantitative parameters between the GO and HC groups, or between active and inactive GO groups were evaluated using a Student's t-test. Receiver operating characteristic analyses were used to evaluate the diagnostic value of the significant parameters in discriminating patients with GO from healthy controls, or discriminating active from inactive GO. All the quantitative measurements of the GO patients were significantly larger than those of the healthy controls (P<0.05), with the exception of the coronal length (P=0.150). Axial and coronal width had the best efficacy in discriminating patients with GO from healthy controls. Only SIR was found to be different between the active and inactive GO groups (P=0.001). Setting a SIR of 2.57 as the threshold value, the optimal efficacy was achieved (area under the curve, 0.711; sensitivity, 57.7%; specificity, 77.5%) in discriminating between active and inactive GO. Quantitative measurements of the lacrimal gland based on 3-T MR imaging may assist in the diagnosis and stage of GO.

Histamine induces NF-κB controlled cytokine secretion by orbital fibroblasts via histamine receptor type-1

Mast cells and their products are likely to be involved in regulating orbital fibroblast activity in Graves' Ophthalmopathy (GO). Histamine is abundantly present in granules of mast cells and is released upon mast cell activation. However, the effect of histamine on orbital fibroblasts has not been examined so far. Orbital tissues from GO patients and controls were analyzed for the presence of mast cells using toluidine blue staining and immunohistochemical detection of CD117 (stem cell factor receptor). Orbital fibroblasts were cultured from GO patients and healthy controls, stimulated with histamine and cytokines (IL-6, IL-8, CCL2, CCL5, CCL7, CXCL10 and CXCL11) were measured in culture supernatants. Also hyaluronan levels were measured in culture supernatants and hyaluronan synthase (HAS) and hyaluronidase (HYAL) gene expression levels were determined. In addition, histamine receptor subtype gene expression levels were examined as well as the effect of the histamine receptor-1 (HRH1) antagonist loratadine and NF-κB inhibitor SC-514 on histamine-induced cytokine production. Mast cell numbers were increased in GO orbital tissues. Histamine stimulated the production of IL-6, IL-8 and CCL2 by orbital fibroblasts, while it had no effect on the production of CCL5, CCL7, CXCL10, CXCL11 and hyaluronan. Orbital fibroblasts expressed HRH1 and loratadine and SC-514 both blocked histamine-induced IL-6, IL-8 and CCL2 production by orbital fibroblasts. In conclusion, this study demonstrates that histamine can induce the production of NF-κB controlled-cytokines by orbital fibroblasts, which supports a role for mast cells in GO.

Use of MRI signal intensity of extraocular muscles to evaluate methylprednisolone pulse therapy in thyroid-associated ophthalmopathy

PURPOSE

To quantitatively evaluate the efficacy of methylprednisolone pulse therapy for extraocular muscle inflammation in thyroid-associated ophthalmopathy (TAO) using the short-tau inversion-recovery (STIR) technique of magnetic resonance imaging (MRI).

METHODS

The signal intensities of the superior rectus (SR), inferior rectus (IR), lateral rectus (LR), medial rectus (MR), and superior oblique (SO) muscles were measured using the STIR images from 34 eyes of 17 patients with TAO before and after methylprednisolone pulse therapy and 19 eyes of 19 controls. The signal intensity ratio (SIR) of the signal intensity in muscles to that in brain white matter was calculated.

RESULTS

The mean SIRs of the controls were 1.08 ± 0.26 in the SR, 1.32 ± 0.29 in the IR, 1.34 ± 0.19 in the LR, 1.47 ± 0.25 in the MR, and 1.28 ± 0.22 in the SO muscles. SIRs exceeding 2.0 were out of the normal range. The SIRs of the patients with TAO before treatment were 2.19 ± 0.64, 2.44 ± 0.58, 1.96 ± 0.43, 2.24 ± 0.47, and 1.91 ± 0.42, respectively, which was significantly (P < 0.001) higher than those of the controls; after treatment, the mean SIRs were 1.82 ± 0.57, 1.81 ± 0.49, 1.64 ± 0.35, 1.88 ± 0.43, and 1.54 ± 0.33, respectively, significantly (P < 0.001) lower in all muscles than those before treatment. However, the SIRs of some muscles remained over 2.0. Moreover, all cases that had deterioration of TAO had one or more muscles with a SIR exceeding 2.5 after treatment.

CONCLUSION

Extraocular muscle inflammation in TAO improved with treatment. However, inflammation in some muscles persisted after treatment, and a high SIR in the muscle after treatment suggested the risk of deterioration of TAO.

Type 1 diabetes in NOD mice unaffected by mast cell deficiency

Mast cells have been invoked as important players in immune responses associated with autoimmune diseases. Based on in vitro studies, or in vivo through the use of Kit mutant mice, mast cells have been suggested to play immunological roles in direct antigen presentation to both CD4(+) and CD8(+) T cells, in the regulation of T-cell and dendritic cell migration to lymph nodes, and in Th1 versus Th2 polarization, all of which could significantly impact the immune response against self-antigens in autoimmune disease, including type 1 diabetes (T1D). Until now, the role of mast cells in the onset and incidence of T1D has only been indirectly tested through the use of low-specificity mast cell inhibitors and activators, and published studies reported contrasting results. Our three laboratories have generated independently two strains of mast cell-deficient nonobese diabetic (NOD) mice, NOD.Cpa3(Cre/+) (Heidelberg) and NOD.Kit(W-sh/W-sh) (Leuven and Boston), to address the effects of mast cell deficiency on the development of T1D in the NOD strain. Our collective data demonstrate that both incidence and progression of T1D in NOD mice are independent of mast cells. Moreover, analysis of pancreatic lymph node cells indicated that lack of mast cells has no discernible effect on the autoimmune response, which involves both innate and adaptive immune components. Our results demonstrate that mast cells are not involved in T1D in the NOD strain, making their role in this process nonessential and excluding them as potential therapeutic targets.

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.

Mast cell regulation of the immune response

Mast cells are well known as principle effector cells of type I hypersensitivity responses. Beyond this role in allergic disease, these cells are now appreciated as playing an important role in many inflammatory conditions. This review summarizes the support for mast cell involvement in resisting bacterial infection, exacerbating autoimmunity and atherosclerosis, and promoting cancer progression. A commonality in these conditions is the ability of mast cells to elicit migration of many cell types, often through the production of inflammatory cytokines such as tumor necrosis factor. However, recent data also demonstrates that mast cells can suppress the immune response through interleukin-10 production. The data encourage those working in this field to expand their view of how mast cells contribute to immune homeostasis.

Graves' orbitopathy: extraocular muscle/total orbit area ratio is positively related to the Clinical Activity Score

BACKGROUND AND OBJECTIVE

Both extraocular muscle (EOM) and orbital fat are involved in Graves' orbitopathy (GO) but their enlargement might occur with a different temporal pattern. Two GO subtypes have been described, one with predominant EOM enlargement and the other with prevalent fat tissue involvement. We longitudinally investigated the EOM in patients with GO and their relationship with clinical activity.

PATIENTS AND METHODS

By using commercial software with a segmentation technique, we calculated from computed tomography (CT) scan EOM coronal area (CA) and total orbit coronal area (TOA) in 23 control subjects and in 32 patients with GO. The latter were studied both at presentation and 18 months later. Superior, lateral, inferior, and medial EOM areas and TOA were selected by 3 different contiguous CT slices: A, B, and C, chosen at globe pole tangent and 2 and 4 mm backward. The Clinical Activity Score (CAS) was also measured.

RESULTS

Orbital EOM CA/TOA ratio (OM/TOA ratio) after 18 months decreased in most patients with GO, indicating that EOM area decrement contributed significantly to OM/TOA ratio reduction. Clinical Activity Score decrease was significantly correlated to the OM/TOA ratio decrease.

CONCLUSIONS

An easy method to measure CA of EOM and orbit allowed us to observe that in most patients with GO the OM/TOA ratio decreases with time, suggesting that macroscopic EOM involvement occurs initially and resolves as the other clinical signs and symptoms of the disease resolve, as indicated by the significant OM/TOA ratio correlation with CAS.

Immunotherapy in miscellaneous medical disorders Graves ophthalmopathy, asthma, and regional painful syndrome

In Graves ophthalmopathy, immunotherapy is offering an opportunity of reducing bad outcomes that lead to disfigurement and impairment of vision. These therapies are not perfect; however, we now have a chance to achieve better outcomes. In asthma, immune therapy using passive immunity targeting key proinflammatory cytokine/chemokines and medications of their effects has opened an avenue of research into a safe and durable therapy. Omalizumab appears to be safe and effective in clinical use. In regional pain syndrome, immune mechanisms may be involved in sustaining long-standing pain, and IVIG may moderate pain sensitivity by reducing immune activation.

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.

Regulation of Lymphocyte Function by PPARgamma: Relevance to Thyroid Eye Disease-Related Inflammation

Thyroid eye disease (TED) is an autoimmune condition in which intense inflammation leads to orbital tissue remodeling, including the accumulation of extracellular macromolecules and fat. Disease progression depends upon interactions between lymphocytes and orbital fibroblasts. These cells engage in a cycle of reciprocal activation which produces the tissue characteristics of TED. Peroxisome proliferator-activated receptor-gamma (PPARgamma) may play divergent roles in this process, both attenuating and promoting disease progression. PPARgamma has anti-inflammatory activity, suggesting that it could interrupt intercellular communication. However, PPARgamma activation is also critical to adipogenesis, making it a potential culprit in the pathological fat accumulation associated with TED. This review explores the role of PPARgamma in TED, as it pertains to crosstalk between lymphocytes and fibroblasts and the development of therapeutics targeting cell-cell interactions mediated through this signaling pathway.

Histopathologic analysis of palpebral conjunctiva in thyroid-related orbitopathy (an american ophthalmological society thesis)

PURPOSE

To examine the histopathology of palpebral conjunctiva in patients with thyroid-related orbitopathy. Based on previously published anecdotes, the hypothesis is that conjunctiva shows increased inflammation and fibrosis.

METHODS

This was a comparative case series. Superior palpebral conjunctiva was examined from two groups. The study group consisted of 20 patients undergoing thyroid-related upper eyelid retraction surgery. The control group consisted of 18 patients undergoing ptosis repair. Specimens were processed and stained using hematoxylin and eosin and trichrome. Histopathologic grading was performed using light microscopy. Main outcome measures were degree of inflammation and fibrosis, mast cell infiltration, and fibroblast count.

RESULTS

The two groups did not differ with regard to age or gender. Mean degree of inflammation was 1.4 (95% CI: 0.9, 1.9) for the control group and 1.7 (95% CI: 1.3, 2.1) for the study group. Relative intensity of blue from trichrome staining mean was 134.3 (95% CI: 130.3, 138.3) for the control group and 138.6 (95% CI: 133.7, 143.6) for the study group. The Mann-Whitney test showed no difference between groups in inflammation (P=.17), relative blue intensity (P=.11), degree of mast cell infiltration (P=.61), and fibroblast count (P=.45). Point estimates show a trend toward greater inflammation in the study group.

CONCLUSIONS

While there is a trend toward higher inflammation in the study group, the superior palpebral conjunctiva of patients with thyroid-related orbitopathy is largely spared from autoimmune changes. This has implications in surgical approaches to eyelid retraction repair.

Orbital fibroblasts from patients with thyroid-associated ophthalmopathy overexpress CD40: CD154 hyperinduces IL-6, IL-8, and MCP-1

PURPOSE

Fibroblast diversity represents an emerging concept critical to our understanding of tissue inflammation, repair, and remodeling. Orbital fibroblasts heterogeneously display Thy-1 and exhibit unique phenotypic attributes that may explain the susceptibility of the human orbit to thyroid-associated ophthalmopathy (TAO). In the present study the authors investigated the role of CD40 ligation on macrophage chemoattractant protein-1 (MCP-1), IL-6, and IL-8 expression in fibroblasts from patients with TAO.

METHODS

Human orbital fibroblasts were cultured from tissues obtained with informed consent from patients with TAO and from patients undergoing surgery for other noninflammatory conditions. The fibroblasts were then examined by flow cytometry, microscopy, and cytokine assays.

RESULTS

The authors report that orbital fibroblasts from patients with TAO expressed elevated levels of CD40. Surface CD40 could be further upregulated by IFN-gamma in TAO and control fibroblasts. This upregulation was mediated through Jak2 and could be blocked by dexamethasone and AG490, a powerful and specific inhibitor of tyrosine kinase. Treatment with CD154, the ligand for CD40, upregulated the expression of IL-6, IL-8, and MCP-1 in TAO fibroblasts but failed to do so in control cultures. Thy-1(+) fibroblasts displayed higher CD40 levels than did their Thy-1(-) counterparts and were largely responsible for this cytokine production. IL-1beta also induced MCP-1, IL-6, and IL-8 more vigorously in TAO-derived fibroblasts.

CONCLUSIONS

Characterization of orbital fibroblasts and their differential expression of cytokines and receptors should prove invaluable in understanding the site-specific nature of TAO and the development of specific therapies.

The master switch: the role of mast cells in autoimmunity and tolerance

There are many parallels between allergic and autoimmune responses. Both are considered hypersensitivity responses: pathologies that are elicited by an exuberant reaction to antigens that do not pose any inherent danger to the organism. Although mast cells have long been recognized as central players in allergy, only recently has their role in autoimmunity become apparent. Because of the commonalities of these responses, much of what we have learned about the underlying mast cell-dependent mechanisms of inflammatory damage in allergy and asthma can be used to understand autoimmunity. Here we review mast cell biology in the context of autoimmune disease. We discuss the huge diversity in mast cell responses that can exert either proinflammatory or antiinflammatory activity. We also consider the myriad factors that cause one response to predominate over another in a particular immune setting.

Modulation of expression of somatostatin receptor subtypes in Graves' ophthalmopathy orbits: relevance to novel analogs

Apart from evaluating orbital inflammation in Graves' ophthalmopathy (GO), somatostatin (SST) analogs have been proposed as a therapy, but recent trials were disappointing. We aimed to measure somatostatin receptor (SSTR) expression in orbital tissues ex vivo and determine whether the new broad-affinity analog SOM230 might be of therapeutic use. Orbital adipose/connective tissues from 29 GO patients and 10 normal individuals were analyzed. Transcripts were quantified using SYBR Green and a light cycler. In vitro models were used to investigate whether thyrotropin receptor activation (as occurs via thyroid stimulating antibodies) or adipogenesis affected SSTR expression in primary preadipocytes and to compare the biological activity of octreotide and SOM230 in their modulation. The expression of SSTR1 was significantly higher in GO patients than normal controls (P = 0.024). Although differences in the expression of SSTR2 were not significant, 39% of GO samples had levels above the 97th percentile of the controls. SSTR3, -4, and -5 were at or below the limit of detection (LOD). The lymphocyte contribution was minimal, since CD3alpha transcripts were at the LOD. TSH receptor activation did not modulate SSTR expression. An in vitro model of adipogenesis indicated upregulation of SSTR1 and SSTR2 during differentiation. SOM230 produced significantly greater inhibition of orbital preadipocyte proliferation than octreotide. Ex vivo analysis of orbital tissues reveals upregulation of SSTR1 and -2 in a group of GO patients. Adipogenesis, a process occurring in GO orbits, provides one possible explanation for some of the observed increase.

Efficacy and safety of orbital decompression in treatment of thyroid-associated ophthalmopathy: long-term follow-up of 78 patients

OBJECTIVE

To study the long-term results of decompression surgery in patients with thyroid-associated ophthalmopathy (TAO).

DESIGN AND METHODS

Retrospective analysis and clinical re-examination of TAO patients with comparison to healthy controls in Helsinki University Central Hospital.

PATIENTS

Seventy-eight patients who had undergone orbital decompression due to TAO by transantral or endonasal technique between the years 1985 and 2000 were invited for re-examination. For comparison, 79 healthy age- and sex-matched controls underwent a similar examination.

RESULTS

In comparison to the patients' preoperative state, proptosis was reduced by 4.7 (2.6) mm (mean (SD)) in the right and 4.4 (2.9) mm in the left globe (P < 0.0001) but did not reach the level of the controls' globe (P < 0.0001). In the right and left eye of patients, visual acuity improved in 44-55%, remained stable in 27-36% and worsened in 18-20%, but remained significantly worse than in controls (P =0.02-0.001). Prevalence of diplopia was high at the re-examination (N = 39, 50%), but 54% of those patients considered it less difficult than before the surgery. Among patients and controls, maxillary sinusitis and facial neuralgias were equally common. Sensory disturbances were significantly more frequent in patients (P < 0.0001). In assessment of overall satisfaction with present eye status, the median of the visual analogue scale (VAS) was lower for the patients than the controls (P < 0.0001). The majority of the patients considered the operation very helpful regardless of the technique used.

CONCLUSION

For patients with TOA, orbital decompression seems to be an effective and safe treatment.

Biological effects of thyrotropin receptor activation on human orbital preadipocytes

PURPOSE

Thyrotropin receptor (TSHR) expression is upregulated in the orbits of patients with Graves ophthalmopathy (GO), most of whom have TSHR-stimulating antibodies. The authors investigated the biological effects of TSHR activation in vitro in adipose tissue, the site of orbital TSHR expression.

METHODS

Activating mutant TSHR (TSHR*) or wild-type (WT) was introduced into human orbital preadipocytes using retroviral vectors. Their proliferation (Coulter counting), basal cAMP accumulation (radioimmunoassay), and spontaneous and peroxisome proliferator-activated receptor (PPARgamma)-induced adipogenesis (quantitative oil red O staining) were assessed and compared with those of nonmodified cells. QRT-PCR was used to measure transcripts of CCAT/enhancer binding protein (C/EBP)beta, PPARgamma, and lipoprotein lipase (LPL; early, intermediate, and late markers of adipogenesis) and for uncoupling protein (UCP)-1 (brown adipose tissue [BAT]).

RESULTS

Expression of TSHR* significantly inhibited the proliferation of preadipocytes and produced an increase in unstimulated cAMP of 200% to 600%. Basal lipid levels were significantly increased in TSHR* (127%-275%) compared with nonmodified (100%) or WT-expressing (104%-187%) cells. This was accompanied by 2- to 10-fold increases in early-intermediate markers and UCP-1 transcripts (2- to 8-fold); LPL was at the limit of detection. In nonmodified cells, adipogenesis produced significant increases in transcripts of all markers, including LPL (approximately 30-fold). This was not the case in TSHR*-expressing cells, which also displayed 67% to 84% reductions in lipid levels.

CONCLUSIONS

TSHR activation stimulates early differentiation (favoring BAT formation?) but renders preadipocytes refractory to PPARgamma-induced adipogenesis. In neither case did lipid-containing vacuoles accumulate, suggesting that terminal stages of differentiation were inhibited.

Avoiding surgery for thyroid eye disease

In thyroid eye disease, autoimmune inflammation of orbital musculature and fat increases the bulk of the orbital contents. Orbital tension rises and patients stratify according to the ease with which their globes can proptose. Restriction of proptosis is associated with optic nerve compression and visual loss; exophthalmos, with corneal damage. Ocular motility is affected, initially by muscle inflammation; late in the disease, by fibrosis. Extraocular factors, including thyroid endocrine disturbance, antigen release, infections, malignancies, and smoking, may trigger and drive the orbital myopathy. The management of thyroid eye disease by the identification and treatment of drives, followed by immunomodulatory therapy, is discussed. Fourteen patients with compressive optic neuropathy were treated with immunomodulation using intravenous methylprednisolone, oral prednisolone, and cyclosporin A, and followed up for a minimum of three years. All recovered their pre-morbid visual acuities and visual fields in both eyes. Severe disturbances of ocular motility also recovered in 30 patients, treated with the same regime. In one subject, ocular motility normalised with intravenous steroids and cyclosporin A, but no oral prednisolone. Morbidity from the treatment was low. Immunomodulation is a rational and successful method for managing optic nerve compression and disordered motility in this condition.

Signal intensity, clinical activity and cross-sectional areas on MRI scans in thyroid eye disease

The signal intensity from inflamed extra-ocular muscles on short tau inversion recovery (STIR)-sequence magnetic resonance imaging (MRI) is known to correlate with clinical scores of thyroid eye disease (TED) severity. Twenty-one patients who had undergone repeated MRI scanning for TED were studied retrospectively. Signal intensity of extra-ocular muscles (from STIR-sequence MRI) and cross-sectional area (from STIR and T1 MRI) were correlated with Mourits' clinical activity score (CAS). The area of highest signal intensity within the most inflamed extra-ocular muscle, and the average cross-sectional signal intensity of the most inflamed extra-ocular muscle reliably correlated with CAS, and this was maintained as disease activity changed over time. In contrast, isolated measures of muscle cross-sectional area did not correlate with CAS. The extra-ocular muscle cross-sectional area calculated from STIR-sequence MR images was greater than that measured on T1 images. This suggests that muscle area from STIR-sequence MRI may also detect peri-muscular inflammation. We conclude that the peak signal intensity from the most inflamed extra-ocular muscle remains the most reliable correlate of clinical disease activity obtained from these images. STIR-sequence MRI scans provide a number of useful measures of disease activity in TED.

Insight into Graves' hyperthyroidism from animal models

Graves' hyperthyroidism can be induced in mice or hamsters by novel approaches, namely injecting cells expressing the TSH receptor (TSHR) or vaccination with TSHR-DNA in plasmid or adenoviral vectors. These models provide unique insight into several aspects of Graves' disease: 1) manipulating immunity toward Th1 or Th2 cytokines enhances or suppresses hyperthyroidism in different models, perhaps reflecting human disease heterogeneity; 2) the role of TSHR cleavage and A subunit shedding in immunity leading to thyroid-stimulating antibodies (TSAbs); and 3) epitope spreading away from TSAbs and toward TSH-blocking antibodies in association with increased TSHR antibody titers (as in rare hypothyroid patients). Major developments from the models include the isolation of high-affinity monoclonal TSAbs and analysis of antigen presentation, T cells, and immune tolerance to the TSHR. Studies of inbred mouse strains emphasize the contribution of non-MHC vs. MHC genes, as in humans, supporting the relevance of the models to human disease. Moreover, other findings suggest that the development of Graves' disease is affected by environmental factors, including infectious pathogens, regardless of modifications in the Th1/Th2 balance. Finally, developing immunospecific forms of therapy for Graves' disease will require painstaking dissection of immune recognition and responses to the TSHR.

Structural and functional aspects of thyroid peroxidase

Thyroperoxidase (TPO) is the enzyme involved in thyroid hormone synthesis. Although many studies have been carried out on TPO since it was first identified as being the thyroid microsomal antigen involved in autoimmune thyroid disease, previous authors have focused more on the immunological than on the biochemical aspects of TPO during the last few years. Here, we review the latest contributions in the field of TPO research and provide a large reference list of original publications. Given this promising background, scientists and clinicians will certainly continue in the future to investigate the mechanisms whereby TPO contributes to hormone synthesis and constitutes an important autoantigen involved in autoimmune thyroid disease, and the circumstances under which the normal physiological function of this enzyme takes on a pathological role.

Disease associations and altered immune function in CD45 138G variant carriers

The CD45 antigen is a haemopoietic cell specific tyrosine phosphatase essential for antigen receptor mediated signalling in lymphocytes. Expression of different patterns of alternatively spliced CD45 isoforms is associated with distinct functions. We recently identified a polymorphism in exon 6 (A138G) of the gene encoding CD45 (PTPRC) that results in altered CD45 splicing. The 138G allele is present at a high frequency among Japanese (23.7%), with 5.1% individuals homozygous for the G allele. In this study we show that the A138G polymorphism is the cause of altered CD45 isoform expression, promoting splicing towards low molecular weight CD45 isoforms. We further report that the frequency of A138G heterozygotes is significantly reduced in number in cohorts of patients with autoimmune Graves' disease or hepatitis B infection, whereas G138G homozygotes are absent from a cohort of Hashimoto's thyroiditis patients. We also show that 138G individuals exhibit altered cytokine production in vitro and an increased proportion of memory T cells. These data suggest that the 138G variant allele strongly influences these diseases by modulation of immune mechanisms and may have achieved its high frequency as a result of a natural selection probably related to pathogen resistance.

Dry eye syndrome in thyroid-associated ophthalmopathy: lacrimal expression of TSH receptor suggests involvement of TSHR-specific autoantibodies

PURPOSE

We evaluated the relationship between ocular surface damage, elevated lid aperture/impaired Bell's phenomenon and reduced tear production in thyroid-associated ophthalmopathy (TAO). Suspecting a possible role of autoantibodies specific for TSH receptor (TSHR), we further investigated TSHR expression in the healthy lacrimal gland (LG).

METHODS

A total of 48 patients with active TAO and 26 controls were examined for basal tear secretion, Rose Bengal and fluorescein staining, impression cytology (IPC), break-up time (BUT), and blinking (lid width, lid closure, ocular surface, upward excursion). Healthy LGs were investigated immunohistochemically for expression of TSHR.

RESULTS

Thyroid-associated ophthalmopathy patients showed significant ocular surface damage (Rose Bengal staining score: TAO: 2.0 [0-5] versus controls: 0 [0-0.4]; IPC score: TAO 3.0 [0-8] versus controls: 0 [0-1], and BUT: TAO: 3.0 seconds [0-9 seconds] versus controls: 19.5 seconds [13-35.4 seconds]), and significantly reduced tear secretion (TAO: 10 mm [3-20 mm] versus controls: 17 mm [10-27 mm]). Ocular surface damage correlated significantly with tear secretion (r = - 0.35) but not significantly with mechanical alterations (impaired upgaze [r = - 0.34] and ocular surface increase [r = 0.32]). We firstly demonstrate that lacrimal acinar cells physiologically express TSHR.

CONCLUSIONS

As ocular surface damage in TAO significantly correlates with reduced tear production, LG impairment appears to be a major cause of ocular surface drying. Intriguingly, physiological expression of TSHR by LG suggests that, in thyroid disease, autoantibodies may bind to lacrimal TSHR and, perhaps via aberrant signal transduction, contribute to LG impairment and, hence, dry eye syndrome.

Inducing Graves' ophthalmopathy

The majority of patients with Graves' disease (GD) have some degree of ocular involvement and this requires surgical or medical intervention in about 5% of cases. There are autoimmune and inflammatory processes operating in Graves' ophthalmopathy (GO), which together induce glycosaminoglycan production, edema and adipogenesis resulting in an increase in the volume of the orbital contents. GO is a heterogeneous disorder, i.e.: 1) whilst usually associated with hyperthyroidism it may occur in euthyroid (and even hypothyroid) patients; 2) expansion of orbital tissues may be due to 'big-fat' or 'big muscles'. The heterogeneity is further exemplified by the spectrum of protocols which have succeeded in inducing aspects of the disease both in animal models and in humans including: 1) Production of severe hypothyroidism in guinea pigs by thyroidectomy and administration of pituitary extract (TSH); 2) Induction of T cells autoreactive to the thyrotropin receptor (TSHR) in mice; 3) Depletion of regulatory T cells in humans susceptible to autoimmunity; 4) Modulation of adipose tissue metabolism in mice and men. In addition, identical induction protocols result in different pathological features depending on the environment, e.g. TSHR primed T cells produce thyroiditis and ocular pathology in BALBc mice in Brussels but thyroid stimulating antibodies accompanied by elevated thyroxine in these animals (from the same supplier) in Cardiff. Thus, experiences in the induction of GO have confirmed the polygenic, multifactorial nature of the disorder and highlight the importance of careful disease classification to promote further progress in understanding.

Relationship between cigarette smoking and Graves' ophthalmopathy

Environmental triggers in the development of Graves' disease (GD) have been suggested from the very first description of the disease. Since 1987 a number of studies from various countries, have assessed the risk for Graves' ophthalmopathy (GO) associated with smoking, and found an odds-ratio of approximately 4 associated with smoking. Smokers have a higher risk for more advanced GO and a dose response relation is evident. Temporality is suggested by a few prospective studies, as is reversibility since former smokers had a lower risk of developing GO than current smokers, even with a comparable lifetime tobacco consumption. In view of the biological plausibility of the association (suggested mechanisms include tissue hypoxia, modulation of circulating pro- and anti-inflammatory cytokines and accentuation of fibroblast HLA-DR expression) it seems that the association is, indeed, causal. Treatment effect of GD/GO is also influenced by cigarette smoking. It is an independent risk factor for relapse of GD after antithyroid drug treatment. Furthermore, it attenuates the effect of orbital radiotherapy and high-dose systemic glucocorticoids in GO and causes a higher rate of progression of eye disease after radioiodine therapy. The possibility of hindering GO or attenuating its course suggests that counselling on smoking cessation should be an integral part of the treatment of any patient with GD.

A transgenic mouse with a deletion in the collagenous domain of adiponectin displays elevated circulating adiponectin and improved insulin sensitivity

Adiponectin is a plasma protein expressed exclusively in adipose tissue. Adiponectin levels are linked to insulin sensitivity, but a direct effect of chronically elevated adiponectin on improved insulin sensitivity has not yet been demonstrated. We identified a dominant mutation in the collagenous domain of adiponectin that elevated circulating adiponectin values in mice by 3-fold. Adiponectinemia raised lipid clearance and lipoprotein lipase activity, and suppressed insulin-mediated endogenous glucose production. The induction of adiponectin during puberty and the sexual dimorphism in adult adiponectin values were preserved in these transgenic animals. As a result of elevated adiponectin, serum PRL values and brown adipose mass both increased. The effects on carbohydrate and lipid metabolism were associated with elevated phosphorylation of 5'-AMP-activated protein kinase in liver and elevated expression of peroxisomal proliferator-activated receptor gamma2, caveolin-1, and mitochondrial markers in white adipose tissue. These studies strongly suggest that increasing endogenous adiponectin levels has direct effects on insulin sensitivity and may induce similar physiological responses as prolonged treatment with peroxisomal proliferator-activated receptor gamma agonists.

Mast cells in autoimmune disease

Mast cells are known to be the primary responders in allergic reactions, orchestrating strong responses to minute amounts of allergens. Several recent observations indicate that they may also have a key role in coordinating the early phases of autoimmune diseases, particularly those involving auto-antibodies.

Thyroid and the eye

Any thyroid cancer can metastasize to the uveal tract, even after decades; medullary thyroid cancer can be part of multiple endocrine neoplasia syndrome. Superior limbic keratoconjunctivitis and lagophthalmos are prognostic markers for more severe thyroid-associated ophthalmopathy (TAO). The restrictive ophthalmopathy of TAO may be associated with more sustained ocular hypertension and require topical therapy. Several new studies address the therapy of TAO, ranging from retrobulbar to oral to intravenous glucocorticoids, alone or combined with radiotherapy. Endonasal decompression of the posterior orbit can be done well for severe optic nerve compression; however, leaving the anterior orbital septum intact can minimize postoperative diplopia. Smoking increases the risk and relapse rate for ophthalmopathy. Thyrotropin receptor antigen on fibroblasts diffusely in the body is causative in TAO and pretibial myxedema with even increased urinary secretion of glycosaminoglycans. Corticosteroid-responsive patients show a sustained up-regulation of the Th1/Th2 profile.