Orbital Connective Tissue Research Articles

Insights Into Local Orbital Immunity: Evidence for the Involvement of the Th17 Cell Pathway in Thyroid-Associated Ophthalmopathy.

Unique features of local immunity in thyroid-associated ophthalmopathy (TAO) may affect disease progression. To investigate the association between the orbital immune microenvironment and TAO development. TAO and control orbital connective tissues were collected. Single-cell sequencing examined orbital lymphocytic infiltrates. Multicolor flow cytometry explored the phenotypes of different cell subsets and in vitro models for cell functional studies. Coculture experiment and western blotting assay were used to determine underlying mechanism of the enhanced T helper 17 (Th17) cell pathway. The TAO orbital microenvironment was composed of natural killer cells, dendritic cells, macrophages, T cells, plasma cells, and CD34+ orbital fibroblasts, but few B cells. Increases in CD3+CD8- IL-17A-producing and RAR-related orphan receptor (ROR)γt-expressing T cells and in CD3+CD8- IL-13-producing and GATA3-expressing T cells suggested Th17 and Th2 cell responses in TAO orbits. Increased interferon-γ (IFN-γ)-producing and RORγt+Tbet+ T cells indicated a Th1-like phenotype of orbital-infiltrating Th17 cells. Higher IL-23R and IL-1R expression and lower IL-21R expression were also observed on Th17 cells in TAO orbits. Multivariate analyses revealed that the Th17 pathway [IL-17A (P = 0.001), IFN-γ (P = 0.009), RORγt (P = 0.003), IL-23R (P = 0.033), IL-21R (P = 0.019)], and Th2 pathway [IL-13 (P = 0.015), GATA3 (P = 0.012)] were associated with TAO. IL-17A, IL-23R, and IL-1R correlated with clinical activity score and visual acuity. CD34+ orbital fibroblasts exhibited distinct cell surface marker expression and promoted IL-23R and IL-1R expression on T cells to facilitate the Th17-cell phenotype through prostaglandin E2-EP2/EP4-cAMP signaling. Our study addresses the importance of retroorbital immunity and suggests possible means of disrupting TAO pathogenesis.

Potential Roles of CD34+ Fibrocytes Masquerading as Orbital Fibroblasts in Thyroid-Associated Ophthalmopathy.

Orbital tissues in thyroid-associated ophthalmopathy exhibit particular reactivity and undergo characteristic remodeling. Mechanisms underlying these changes have remained largely unexplained. Studies have characterized orbital connective tissues and derivative fibroblasts to gain insights into local manifestations of a systemic autoimmune syndrome. A systematic search of PubMed was undertaken for studies related to thyroid-associated ophthalmopathy (TAO), orbital fibroblasts, and fibrocytes involved in pathogenesis. Orbital tissues display marked cellular heterogeneity. Fibroblast subsets, putatively derived from multiple precursors, inhabit the orbit in TAO. Among them are cells displaying the CD34+CXC chemokine receptor 4+collagen I+ phenotype, identifying them as fibrocytes, derived from the monocyte lineage. Their unique presence in the TAO orbit helps explain the tissue reactivity and characteristic remodeling that occurs in the disease. Their unanticipated expression of several proteins traditionally thought to be thyroid gland specific, including the TSH receptor and thyroglobulin, may underlie orbital involvement in Graves disease. Although no currently available information unambiguously establishes that CD34+ orbital fibroblasts originate from circulating fibrocytes, inferences from animal models of lung disease suggest that they derive from bone marrow. Further studies are necessary to determine whether fibrocyte abundance and activity in the orbit determine the clinical behavior of TAO. Evidence supports a role for fibrocytes in the pathogenesis of TAO. Recognition of their presence in the orbit now allows development of therapies specifically targeting these cells that ultimately could allow the restoration of immune tolerance within the orbit and perhaps systemically.

The insulin-like growth factor-I receptor and its role in thyroid-associated ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO), an autoimmune component of Graves' disease, remains a disfiguring and potentially blinding condition. Here, the author reviews the role of insulin-like growth factor-I receptor pathway in TAO and how it might be therapeutically targeted. The recent literature is reviewed. TAO involves reactivity of orbital connective tissues and their remodeling. While many of the details concerning the pathogenesis of TAO remain to be determined, several insights have come to light recently. Among them is the apparent involvement of IGF-IR. This receptor protein, a membrane-spanning tyrosine kinase receptor can form both physical and functional complexes with the thyrotropin receptor (TSHR). This is notable because TSHR is the established primary autoantigen in Graves' disease. IGF-IR activity is critical to signaling downstream from both IGF-IR and TSHR. In addition, antibodies against IGF-IR have been detected in patients with Graves' disease and in rodent models of TAO. Evidence has been put forward that these antibodies may act directly on IGF-IR, perhaps in some manner activating the receptor. These experimental observations have led to the development of a novel therapy for active TAO, utilizing a monoclonal anti-IGF-IR inhibitory antibody which had been produced originally as treatment for cancer. The agent, teprotumumab was recently evaluated in aclinical trial and found to be highly effective and relatively well-tolerated. It is currently undergoing assessment in a follow-up trial. Should the current study yield similarly encouraging results, it is possible that teprotumumab will emerge as a paradigm-shifting medical therapy for TAO.

Inhibitory Effect of Idelalisib, a Selective Phosphatidylinositol 3-Kinase δ Inhibitor, on Adipogenesis in an In Vitro Model of Graves' Orbitopathy.

Emerging evidence indicates that the phosphatidylinositol 3-kinase (PI3K)-AKT pathway is involved in the pathogenesis of Graves' orbitopathy (GO). In this study, the therapeutic effects of idelalisib, a selective PI3Kδ inhibitor, on adipogenesis were evaluated in GO orbital fibroblasts in vitro. Orbital fibroblasts were cultured from orbital connective tissues obtained from individuals with GO and healthy control subjects. Cells were pretreated with idelalisib for 1 hour before stimulation with IL-1β. Inflammatory cytokine expression was measured by Western blotting and ELISAs. The adipogenesis-related downstream mediators of the PI3K/AKT cascade, that is, forkhead box protein O1 (FOXO1) and mammalian target of rapamycin (mTOR), also were measured by Western blotting. After adipogenic differentiation and idelalisib treatment, cells were stained with Oil Red O and the levels of peroxisome proliferator activator γ (PPARγ) and CCAAT-enhancer-binding proteins (C/EBP) α/β were determined by Western blot analyses. AKT phosphorylation decreased in a dose-dependent manner upon treatment with idelalisib in GO and non-GO orbital fibroblasts. Treatment with idelalisib inhibited the IL-1β-induced expression of IL-6 and IL-8. Idelalisib attenuated the phosphorylation of mTOR and FOXO1, downstream regulators of the PI3K pathway. Oil Red-O staining results revealed a decrease in lipid droplets and suppressed expression of PPARγ and c/EBPα/β upon treatment with idelalisib during adipose differentiation. Idelalisib inhibited proinflammatory cytokine production and adipogenesis in GO orbital fibroblasts in vitro. These results support the potential use of PI3K inhibitors in GO management.

Challenges in Orphan Drug Development: Identification of Effective Therapy for Thyroid-Associated Ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO), the ocular manifestation of Graves' disease, is a process in which orbital connective tissues and extraocular muscles undergo inflammation and remodeling. The condition seems to result from autoimmune responses to antigens shared by the thyroid and orbit. The thyrotropin receptor (TSHR), expressed at low levels in orbital tissues, is a leading candidate antigen. Recent evidence suggests that another protein, the insulin-like growth factor-I receptor (IGF-IR), is overexpressed in TAO, and antibodies against IGF-IR have been detected in patients with the disease. Furthermore, TSHR and IGF-IR form a physical and functional complex, and signaling initiated at TSHR requires IGF-IR activity. Identification of therapy for this rare disease has proven challenging and currently relies on nonspecific and inadequate agents, thus representing an important unmet need. A recently completed therapeutic trial suggests that inhibiting IGF-IR activity with a monoclonal antibody may be an effective and safe treatment for active TAO.

The Hook and Release Technique During Enucleation Surgery.

To describe the results and potential benefit of direct muscle release from the globe during enucleation surgery without identifying sutures in the rectus muscle insertion sites, a technique referred to as the hook and release technique. Single center, retrospective chart review of patients who underwent enucleation with direct removal of the rectus muscles without identifying sutures in their insertion sites between January 2011 and September 2015 was carried out. The inclusion criteria were primary enucleation without previous strabismus surgery, retinal detachment surgery, or orbital surgery that entered the fibrous connective tissue framework. Forty charts of enucleated patients that had direct release of their extraocular muscles without identifying sutures before releasing them from the globe were identified and reviewed. The primary outcome measure was intraoperative or immediate postoperative complications. This retrospective chart review was performed with research ethics board approval and in compliance with the Declaration of Helsinki. Data show that following the hook and release technique, the rectus muscles were easily located and reconnected to the orbital implant wrap. The oblique muscles were not reattached. In each of the 40 patients, the 4 rectus muscles were easily located by gently applying traction anteriorly at the conjunctiva/Tenons' edge using double-pronged skin hooks. There was no instance of a lost or slipped muscle following the hook and release technique. The hook and release technique is a simple and efficient method to remove the 4 rectus muscles from the globe and still easily locate them. They are not "lost" and do not "slip out of position" but held in place by the orbital connective tissue framework and the extraocular muscle pulley system. This technique has been very helpful teaching resident staff how to do enucleation surgery as it avoids the more time consuming placement of double-armed locking sutures through the rectus muscle insertions and the potential risk of globe penetration while the muscles remain attached to the eye. If the surgeon desires to attach the muscles to the orbital implant, then sutures are passed after the eye is removed, thus eliminating the worry of globe penetration and avoiding accidentally cutting preplaced extraocular muscle sutures during the remaining enucleation procedure.

Localizing the Lost Rectus Muscle Using the Connective Tissue Framework: Revisiting the Tunnel Technique.

To describe a technique for localizing a lost rectus muscle during strabismus or retinal surgery or following trauma. In this single center, retrospective chart review, 5 patients were identified between January 2012 and June 2016 with a lost rectus muscle; 3 during strabismus surgery and 2 post trauma. The inclusion criteria included a lost rectus muscle during strabismus surgery, or a disinserted/lacerated rectus muscle following ocular/orbital trauma. The primary outcome measure was successful reattachment of the rectus muscle. The lost rectus muscle was identified in each patient and reattached to the globe by gently applying traction anteriorly at the conjunctiva/Tenon edge using double-pronged skin hooks and following the path of the rectus muscle through its Tenon capsule tunnel where it remained attached by suspensory ligaments. There was no instance where orbital fat was obscuring or blocking the view of the lost rectus muscles. There were no other complications associated with the procedure. The authors describe a simple and effective method in 5 patients to localize a lost rectus muscle based on knowledge of the orbital connective tissue framework.

Thyroid-associated Ophthalmopathy.

Thyroid-associated ophthalmopathy is the most frequent extrathyroidal involvement of Graves’ disease but it sometimes occurs in euthyroid or hypothyroid patients. Thyroid-associated ophthalmopathy is an autoimmune disorder, but its pathogenesis is not completely understood. Autoimmunity against putative antigens shared by the thyroid and the orbit plays a role in the pathogenesis of disease. There is an increased volume of extraocular muscles, orbital connective and adipose tissues. Clinical findings of thyroid-associated ophthalmopathy are soft tissue involvement, eyelid retraction, proptosis, compressive optic neuropathy, and restrictive myopathy. To assess the activity of the ophthalmopathy and response to treatment, clinical activity score, which includes manifestations reflecting inflammatory changes, can be used. Supportive approaches can control symptoms and signs in mild cases. In severe active disease, systemic steroid and/or orbital radiotherapy are the main treatments. In inactive disease with proptosis, orbital decompression can be preferred. Miscellaneous treatments such as immunosuppressive drugs, somatostatin analogs, plasmapheresis, intravenous immunoglobulins and anticytokine therapies have been used in patients who are resistant to conventional treatments. Rehabilitative surgeries are often needed after treatment.

Mechanism of MicroRNA-146a/Notch2 Signaling Regulating IL-6 in Graves Ophthalmopathy

We intended to investigate the significance of microRNA-146a, Notch2 and IL-6 on Graves ophthalmopathy (GO) and the relationships among them. About 27 GO patients were incorporated in this study, including 13 patients with inactive GO and14 patients with active GO. Another 15 patients who had previously received strabismus orthopedics or ophthalmectomy due to trauma were selected as the control population. QRT-PCR assay was used to detect microRNA-146a and Notch2 expression levels in plasma. MTT assay and flow cytometry were respectively used to assess the viability and mitosis of the fibroblasts isolated from orbital connective tissue. Double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was employed to detect serum IL-6 levels. The dual luciferase reporter gene assay was used to verify the targeting relationship between microRNA-146a and Notch2. Compared with the control group, the relative expression of miR-146a was significantly increased whereas the relative expression of Notch2 was significantly decreased (all P < 0.05) in GO patients compare with the control. Notch2 can be directly targeted by microRNA-146a. The over-expression of miR-146a markedly facilitated Orbital Fibroblasts (OFs) viability and mitosis whereas markedly suppressed cell apoptosis (all P < 0.05). Exogenous microRNA-146a mimics could down-regulat the expression of Notch2 and up-regulate IL-6 (P < 0.05). The inhibition of microRNA-146 resulted in the elevated expression of Notch2 and decreased expression of IL-6 (P < 0.05). MicroRNA-146a may increase the IL-6 levels and exacerbate GO by directly targeting Notch2.

Elevated Serum Tetrac in Graves Disease: Potential Pathogenic Role in Thyroid-Associated Ophthalmopathy.

The sources and biological impact of 3,3',5,5' tetraiodothyroacetic acid (TA4) are uncertain. CD34+ fibrocytes express several proteins involved in the production of thyroid hormones. They infiltrate the orbit in Graves disease (GD), an autoimmune process known as thyroid-associated ophthalmopathy. It appears that the thyrotropin receptor plays an important role in the pathogenesis of thyroid-associated ophthalmopathy. To quantify levels of TA4 in healthy participants and those with GD, determine whether fibrocytes generate this thyroid hormone analogue, and determine whether TA4 influences the actions of thyroid-stimulating hormone and thyroid-stimulating immunoglobulins in orbital fibroblasts. Patients with GD and healthy donors in an academic medical center clinical practice were recruited. Liquid chromatography-tandem mass spectrometry, autoradiography, real-time polymerase chain reaction, hyaluronan immunoassay. Serum levels of TA4 are elevated in GD. TA4 levels are positively correlated with those of thyroxine and negatively correlated with serum levels of triiodothyronine. Several cell types in culture generate TA4 from ambient thyroxine, including fibrocytes, HELA cells, human Müller stem cells, and retinal pigmented epithelial cells. Propylthiouracil inhibits TA4 generation. TA4 enhances the induction by thyrotropin and thyroid-stimulating immunoglobulins of several participants in the pathogenesis of thyroid-associated ophthalmopathy, including interleukin 6, hyaluronan synthase 1, prostaglandin endoperoxide H synthase 2, and haluronan production. TA4 may be ubiquitously generated in many tissues and enhances the biological impact of thyrotropin and thyroid-stimulating immunoglobulins in orbital connective tissue. These findings may identify a physiologically important determinant of extrathyroidal thyroid-stimulating hormone action.

A study on the establishment of co-culture system of peripheral blood mononuclear cells with orbital fibroblasts and the secretion of IL-6 and IL-17A induced by phytagglutinin in thyroid associated ophthalmopathy

Background The pathogenic mechanism of thyroid associated ophthalmopathy (TAO) is still unclear, which is considered to be an autoimmune disease.It is confirmed that interleukin-17A (IL-17A) plays an important role in the occurrence and development of many autoimmune diseases.It is unclear that whether IL-17A participates in the pathogenesis of TAO. Objective This study was to explore whether IL-17A secreted by co-culture system of peripheral blood mononuclear cells (PBMCs) and orbital fibroblasts (OFs) participates in the pathogenesis of TAO and its possible mechanism. Methods Periphery blood and orbital connective tissue were obtained from 12 patients with TAO and 8 patients who received prosthesis implantation for eyeball atrophy in Xiangya Hospital during April to December 2014.PBMCs were isolated by density gradient centrifugation, and OFs were cultured by explant culture method.The purity of T leukomonocyte in PBMCs was tested by flow cytometry, and OFs were identified by Giemsa staining and immunochemistry.OFs and PMBCs were incubated into 96-well plate in a 1∶20 proportion to establish co-culture system.Different concentrations of phytagglutinin (PHA) (0, 1.0, 2.5, 5.0, 10.0 μg/ml) was added for 72 hours, and IL-6, IL-17A levels in the co-culture system supernatant and IL-17A receptor (IL-17RA) of the total cell membranes in the co-culture system were assayed by ELISA.The differences of IL-6, IL-17A, IL-17RA levels in co-culture system were compared between the TAO group and control group. Results The mean purity of T leukomonocyte in PBMCs was (81.10±0.21)% in the TAO group and (80.05±0.38)% in the control group respectively, with no significant difference between them(t=0.923, P>0.05). Cultured OFs showed the positive response for Vimentin expression and Giemsa staining.After stimulated by 1.0 μg/ml PHA, the proliferation of both PBMCs and OFs were increased in the co-culture system.Apoptosis exist in PBMCs and the number of OFs decreased when PHA was higher than 1.0 μg/ml.The growth of PBMCs and OFs was faster in the TAO group than that in the control group in the same concentration of PHA.The contents of IL-6, IL-17A and IL-17RA in co-culture system were significantly different among various concentrations of PHA subgroups (IL-6: Fgroup=12.561, P=0.000; Fconcentration=23.356, P=0.001.IL-17A: Fgroup= 12.037, P=0.000; Fconcentration =19.206, P=0.000.IL-17RA: Fgroup=16.216, P=0.000; Fconcentration=4.627, P=0.018). The production of IL-6, IL-17A and IL-17RA reached peak in both TAO group and the control group after 1.0 μg/ml PHA stimulated.However, the concentrations of IL-6, IL-17A and IL-17RA reduced with the increase of PHA concentration.The concentrations of IL-6, IL-17A and IL-17RA in co-culture system were significantly higher in the TAO group than those in the control group under the stimulation of the same concentration of PHA (all at P<0.05). Conclusions The co-culture system of PBMCs and OFs stimulated with PHA can be the imitation of TAO pathogenesis in vitro, and PHA can amplify its immune reaction to imitate TAO pathogenic processes intuitively.The IL-6, IL-17A and IL-17RA secreted by PBMCs and induced by PHA are increased in TAO patients, implying that IL-17A participates in the pathogenesis of TAO through magnifying cellular immune response and inflammatory reaction. Key words: Cell culture; Thyroid-associated ophthalmopathy; Peripheral blood mononuclear cells; Orbital fibroblasts; T lymphocytes; Interleukin-6; Interleukin-17A; Human

Does autoimmunity against thyroglobulin play a role in the pathogenesis of Graves' ophthalmopathy: a review.

While most authors believe that autoimmunity against the TSH receptor expressed in the orbital connective tissue cells is the main reaction that leads to the development of ophthalmopathy in patients with Graves’ hyperthyroidism, an older hypothesis that deserves fresh consideration is based on the notion that thyroglobulin (Tg) in the thyroid gland passes in a retrograde fashion to the orbit where it is recognized by Tg autoantibodies, leading to inflammation. Here, we review new evidence that supports a role of Tg and propose a new hypothesis based on the notion that Tg is targeted in the orbit leading to a complex cascade of reactions that leads to Graves’ ophthalmopathy.

Inhibitory effects of dexamethasone on proliferation of fibroblasts derived by idiopathic orbital inflammatory pseudotumor

Background Idiopathic orbital inflammatory pseudotumor (IOIP) is a common orbital disease, but its etiology is still unclear, so the effect of glucocorticoid treatment is unsatisfied. Objective This study was to investigate the effects of dexamethasone on orbital fibroblasts from IOIP patients and explore the action machanism. Methods Six pieces of IOIP tissues from 6 IOIP patients and 3 pieces of normal orbital connective tissues from lacrimal gland prolapse patients were obtained during the surgery in Beijing Tongren Hospital from November 2011 to January 2012.The orbital fibroblasts were cultured using explant culture method.The morphology of the cells were observed under the optical microscope, and biomarks of the cells were detected by immunochemistry.The growth and proliferation of the cells were assayed using WST-8.The expression of ICAM-1 in the cells in both the control group and the IOIP group was detected by immunochemistry.The fibroblasts were incubated in 96-well plates, and different concentrations of dexamethasone (0, 1×10-3, 1×10-4, 1×10-5 and 1×10-6 mol/L) were respectively added into the medium for 24, 48 and 72 hours, and then the proliferation of the cells was detected by WST-8 assay.The contents of ICAM-1 in different concentrations of dexamethasone groups were assayed by ELISA. Results The characteristics of the cells were similar between the control group and the IOIP group with the spindle shape and long protructions.The cells showed the positive response for vimentin and absent response for desmin, S-100, cytokeratin (CK). Compared with the control group, the growth speed of fibroblasts was fast in the IOIP group.The proliferative values of the cells (absorbancy) were gradually reduced with the increase of dexamethasone concentrations (Fconcentration=36.27, P=0.00) and the lapse of acting time (Ftime=3.69, P=0.00). In cultured cells without dexamethasone for 24, 48 and 72 hours, the mean expression levels of ICAM-1 were 0.298±0.008, 0.312±0.003 and 0.319±0.011, showing a gradually increasing trend.However, the expression of ICAM-1 was gradually reduced with the increases of concentrations and the lapse of acting time of dexamethasone (Fconcentration=75.17, P=0.00; Ftime=3.11, P=0.00). Conclusions Occurrence and development of IOIP is probably associated with the over-expression of ICAM-1 in orbital fibroblasts.Dexamethasone plays anti-inflammation and treating effects on IOIP by down-regulating the expression of ICAM-1 and inhibiting the proliferation of orbital fibroblasts. Key words: Orbital pseudotumor/drug therapy; Fibroblasts/drug effects; Glucocorticoids/pharmacology; Dexamethasone; Intercellular adhesion molecule-1; Down-regulation; Cell culture

Therapeutic Effect of Resveratrol on Oxidative Stress in Graves' Orbitopathy Orbital Fibroblasts.

Multiple causative factors complicate the pathogenesis in Graves' orbitopathy (GO). It has been suggested that oxidative stress contributes to the development and progression of GO. Therefore, we investigated the therapeutic effect of resveratrol, a potent antioxidant, upon oxidative stress levels in GO orbital fibroblasts in vitro. Orbital fibroblasts were cultured from orbital connective tissues obtained from GO patients. Intracellular reactive oxygen species (ROS) levels and the expression of heme oxygenase-1 (HO-1), superoxide dismutase (SOD), catalase, and thioredoxin (Trx), were measured after resveratrol treatment. Adipogenesis was induced, and ROS levels were examined during adipogenic differentiation. Western blot assay was performed to evaluate the effects of resveratrol on the expression of antioxidants levels and transcriptional regulators. Treatment with 30 or 50 μM resveratrol reduced ROS production and HO-1 level induced by oxidative stress. Levels of Cu/Zn-SOD, catalase, and Trx were also reduced, while Mn-SOD increased with 50 μM resveratrol treatment. Resveratrol suppressed adipogenesis, reducing the number of adipocytes and suppressing the accumulation of lipid droplets. Treatment with 50 μM resveratrol also decreased ROS levels during adipogenesis. Expression of the transcriptional regulators phosphor-extracellular signal-regulated kinase and phospho-c-Jun NH(2)-terminal kinase significantly increased after treatment with 50 μM resveratrol, and decreased in response to inhibitors of each protein. Phosphonuclear factor kappa-light-chain-enhancer of activated B cells p65 levels also increased after treatment with 50 μM resveratrol. Resveratrol reduced ROS levels and inhibited adipogenesis in GO orbital fibroblasts in vitro. This study supports the potential use of resveratrol in GO treatment.

Graves’ orbitopathy in pediatrics

Graves’ orbitopathy (GO) is rare in pediatric patients, however is the most common extrathyroid manifestation of Graves’ disease (GD), being present in 30-67% of patients. GO is an autoimmune inflammatory disorder involving orbital connective and fatty tissues as well as the extraocular muscles. In children, GO is less common and less severe than in adults. The most common symptoms are upper eyelid retraction, conjunctival injection, and proptosis and periorbital edema. Severe complications include dysthyroid optic neuropathy, corneal ulceration and eyeball subluxation. The diagnosis is established by clinical, laboratory and imaging findings. There are no management guidelines for GO in children but adult recommendations include the assessment of clinical activity and its severity, to implement the best treatment. Supportive therapies are intended to relieve symptoms and prevent corneal damage in mild cases. Tobacco exposure should also be avoided. The first line of treatment is systemic administration of corticosteroids in active and severe cases. Other options as somatostatin use and retrobulbar radiation have not been used in children, therefore their use is not recommended.

Recent advances clarifying the etiologies of strabismus.

Strabismus is commonly encountered in neuro-ophthalmology practice. Adult patients may present with symptoms including disabling diplopia and decreased quality of life. Although presentation to the neuro-ophthalmologist often prompts a thorough workup for a neurologic basis of ocular misalignment, advances in orbital imaging and understanding of orbital mechanics have revealed novel mechanical causes. A goal of this review is to clarify mechanical mechanisms of strabismus that were formerly assumed be neurologic in origin. The authors combine their own research and clinical experience with a literature review using PubMed. Aberrant paths of the extraocular muscles can lead to strabismus. The extraocular muscles have connective tissue pulleys that control muscle paths and are, in turn, influenced by the extraocular muscle orbital layers. Orbital connective tissues, including the pulleys, constrain extraocular muscle paths. Abnormalities of these tissues may lead to strabismus that is not due to neurologic pathology. Some extraocular muscles are divided into independent neuromuscular compartments, so that partial motor nerve lesions may manifest as selective denervation of only 1 compartment, complicating the presentation of neuropathic strabismus. Strabismus in adults due to nonneurologic causes can result from recently described abnormalities of the orbital connective tissue pulley system. Advances in understanding of compartmental extraocular muscle anatomy and innervation can explain cyclovertical strabismus in partial nerve palsies. Recognition of the underlying pathogenesis of the strabismus can lead to improved treatments.

Post enucleation socket syndrome - new and established surgical solutions

The orbital volume after enucleation or evisceration might shrink over time due to atrophy of the orbital fat and connective tissue. This can lead to prosthesis misfit and an unsatisfactory cosmetic result. This so-called post enucleation socket syndrome (PESS) needs a secondary orbital volume augmentation. The techniques for orbital volume augmentation are secondary orbital implants or implant exchange, orbital floor implants or injectable augmentation. The surgical possibilities are described and discussed with special attention to indications and chances.

TSH-receptor-expressing fibrocytes and thyroid-associated ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO) is a vexing and undertreated ocular component of Graves disease in which orbital tissues undergo extensive remodelling. My colleagues and I have introduced the concept that fibrocytes expressing the haematopoietic cell antigen CD34 (CD34(+) fibrocytes), which are precursor cells of bone-marrow-derived monocyte lineage, express the TSH receptor (TSHR). These cells also produce several other proteins whose expression was traditionally thought to be restricted to the thyroid gland. TSHR-expressing fibrocytes in which the receptor is activated by its ligand generate extremely high levels of several inflammatory cytokines. Acting in concert with TSHR, the insulin-like growth factor 1 receptor (IGF-1R) expressed by orbital fibroblasts and fibrocytes seems to be necessary for TSHR-dependent cytokine production, as anti-IGF-1R blocking antibodies attenuate these proinflammatory actions of TSH. Furthermore, circulating fibrocytes are highly abundant in patients with TAO and seem to infiltrate orbital connective tissues, where they might transition to CD34(+) fibroblasts. My research group has postulated that the infiltration of fibrocytes into the orbit, their unique biosynthetic repertoire and their proinflammatory and profibrotic phenotype account for the characteristic properties exhibited by orbital connective tissues that underlie susceptibility to TAO. These insights, which have emerged in the past few years, might be of use in therapeutically targeting pathogenic orbit-infiltrating fibrocytes selectively by utilizing novel biologic agents that interfere with TSHR and IGF-1R signalling.

Teprotumumab, an IGF-1R blocking monoclonal antibody inhibits TSH and IGF-1 action in fibrocytes.

Thyroid-associated ophthalmopathy (TAO) is the component of Graves' disease characterized by orbital inflammation and connective tissue remodeling. The IGF-1 receptor (IGF-1R) and TSH receptor (TSHR) form a physical and functional complex in orbital fibroblasts. A subset of these fibroblasts is derived from infiltrating CD34(+) fibrocytes. Teprotumumab (RV 001, R1507) is a human monoclonal anti-IGF-1R blocking antibody currently undergoing a phase 2 clinical trial in patients with active TAO. To determine whether teprotumumab inhibits the induction by TSH of IL-6 and IL-8 in fibrocytes. Fibrocytes were treated without or with teprotumumab in combination with IGF-1 or TSH. IL-6 and IL-8 mRNA expression and protein production were analyzed by real-time PCR and Luminex, respectively. Phosphorylated Akt (S473) levels were analyzed by Western blot. TSHR and IGF-1R display was assessed by flow cytometry. Fibrocyte display of IGF-1R and TSHR was reduced with teprotumumab, as were IGF-1- and TSH-dependent phosphorylated Akt levels. TSH induction of IL-6 and IL-8 mRNA and protein was also reduced by the monoclonal antibody. Teprotumumab attenuates the actions of both IGF-1 and TSH in fibrocytes. Specifically, it blocks the induction of proinflammatory cytokines by TSH. These results provide, at least in part, the molecular rationale for interrogating the therapeutic efficacy of this antibody in TAO.

Imaging appearance of the lateral rectus-superior rectus band in 100 consecutive patients without strabismus.

The lateral rectus-superior rectus band is an orbital connective tissue structure that has been implicated in a form of strabismus termed sagging eye syndrome. Our purpose was to define the normal MR imaging and CT appearance of this band in patients without strabismus. Orbital MR imaging and CT examinations in 100 consecutive patients without strabismus were evaluated. Readers graded the visibility of the lateral rectus-superior rectus band on coronal T1WI, coronal STIR, and coronal CT images. Readers determined whether the band demonstrated superotemporal bowing or any discontinuities and whether a distinct lateral levator aponeurosis was seen. Reader agreement was assessed by κ coefficients. Association between imaging metrics and patient age/sex was calculated by using the Fisher exact test. The lateral rectus-superior rectus band was visible in 95% of coronal T1WI, 68% of coronal STIR sequences, and 70% of coronal CT scans. Ninety-five percent of these bands were seen as a continuous, arc-like structure extending from the superior rectus/levator palpebrae muscle complex to the lateral rectus muscle; 24% demonstrated superotemporal bowing; and in 82% of orbits, a distinct lateral levator aponeurosis was visible. Increasing patient age was negatively associated with lateral rectus-superior rectus band visibility (P=.03), positively associated with lateral rectus-superior rectus band superotemporal bowing (P=.03), and positively associated with lateral levator aponeurosis visibility (P=.01). The lateral rectus-superior rectus band is visible in most patients without strabismus on coronal T1WI. The age effect with respect to its visibility and superotemporal bowing could represent age-related connective tissue degeneration.