Markers of inflammation and fibrosis in the orbital fat/connective tissue of patients with Graves' orbitopathy: clinical implications

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.

Efficacy and Safety of Teprotumumab in Patients With Thyroid Eye Disease of Long Duration and Low Disease Activity

CONTEXT

Early inflammatory thyroid eye disease (TED) can lead to symptomatic chronic disease, including disabling proptosis. Teprotumumab, an insulin-like growth factor-1 receptor (IGF-1R) inhibitor, previously demonstrated efficacy in acute, high-inflammation TED trials.

OBJECTIVE

We present data from the first placebo-controlled trial with teprotumumab in chronic/low disease activity TED.

METHODS

This randomized double-masked, placebo-controlled trial, conducted at 11 US centers, enrolled adult participants with TED duration of 2 to 10 years, Clinical Activity Score (CAS) ≤ 1 or no additional inflammation or progression in proptosis/diplopia for ≥1 year, proptosis ≥3 mm from before TED and/or from normal, euthyroid/mildly hypo/hyperthyroid, no prior teprotumumab, and no steroids within 3 weeks of baseline. Patients received (2:1) intravenous teprotumumab or placebo once every 3 weeks (total 8 infusions). The primary endpoint was proptosis (mm) improvement at Week 24. Adverse events (AEs) were assessed.

RESULTS

A total of 62 (42 teprotumumab and 20 placebo) patients were randomized. At Week 24, least squares mean (SE) proptosis improvement was greater with teprotumumab (-2.41 [0.228]) than with placebo (-0.92 [0.323]), difference -1.48 (95% CI -2.28, -0.69; P = .0004). Proportions of patients with AEs were similar between groups. Hyperglycemia was reported in 6 (15%) vs 2 (10%) and hearing impairment in 9 (22%) vs 2 (10%) with teprotumumab and placebo, respectively. AEs led to discontinuation in 1 teprotumumab (left ear conductive hearing loss with congenital anomaly) and 1 placebo patient (infusion-related). There were no deaths.

CONCLUSION

Teprotumumab significantly improved proptosis vs placebo in longstanding/low inflammation TED, demonstrating efficacy regardless of disease duration/activity. The safety profile was comparable to that previously reported.

Lutein targeting orbital fibroblasts attenuates fibrotic and inflammatory effects in thyroid-associated ophthalmopathy

Lutein (LU) is a carotenoid that has recently been implicated in multiple roles in fibrosis, inflammation, and oxidative stress. Thyroid-associated ophthalmopathy (TAO) is particularly relevant to these pathological changes. We thus aim to probe the potential therapeutic effects of TAO in an in vitro model. We used LU pre-treating OFs derived from patients with TAO or not, then treated with TGF-β1(or IL-1β)to induce fibrosis (or inflammation). We analyzed the different expressions of related genes and proteins, and the molecular mechanism pathway on TAO OFs was screened by RNA sequencing, which is identified in vitro. We found that LU attenuates fibrotic and inflammatory effects in TAO. LU inhibited ACTA2, COL1A1, FN1, and CTGF mRNA expression and suppressed α-SMA, and FN1 protein expression induced by TGF-β1. Besides, LU suppressed OFs migration. Besides, it is shown that LU suppressed inflammation-related genes, such as IL-6, IL-8, CXCL1, and MCP-1. Moreover, LU inhibited oxidative stress induced by IL-1β, which is analyzed by DHE fluorescent probe staining. RNA sequencing suggested ERK/AP-1 pathway may be the molecular mechanism of LU protective effect on TAO, which is identified by RT-qPCR and western-blot. In summary, this study provides the first evidence that LU significantly attenuates the pathogenic manifestations of TAO by inhibiting the expression of fibrotic and inflammation-related genes and ROS produced by OFs. These data suggested that LU may be a potential medicine for TAO.

Serelaxin Alleviates Fibrosis in Thyroid-Associated Ophthalmopathy via the Notch Pathway

Fibrosis is the late stage of thyroid-associated ophthalmopathy (TAO), resulting in serious complications. Effective therapeutic drugs are still lacking. We aimed to explore the mechanism of TAO fibrosis and to find a targeted drug. High-throughput RNA sequencing was performed on orbital connective tissues from twelve patients with TAO and six healthy controls. Protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) database and we identified the hub gene by Cytoscape software. Additionally, the RNA sequencing results were validated by quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatic prediction identified the functions of differentially expressed genes (DEGs). Further orbital connective tissue and serum samples of the TAO and control groups were collected for subsequent experiments. Histologic staining, Western blotting (WB), qRT-PCR, enzyme-linked immunosorbent assays (ELISAs), gene overexpression through lentiviral infection or silencing gene by short interfering RNA (siRNA) were performed. We found that the relaxin signaling pathway is an important regulatory pathway in TAO fibrosis pathogenesis. Serelaxin exerts antifibrotic and anti-inflammatory effects in TAO. Furthermore, the downstream Notch pathway was activated by serelaxin and was essential to the antifibrotic effect of serelaxin in TAO. The antifibrotic effect of serelaxin is dependent on RXFP1.

Efficacy and Safety of 6-Weekly versus 12-Weekly Intravenous Methylprednisolone in Moderate-to-Severe Active Thyroid-Associated Ophthalmopathy

PURPOSE

To compare the efficacy and safety of 6-weekly and 12-weekly intravenous methylprednisolone (IVMP) regimens in moderate-to-severe, active thyroid-associated orbitopathy (TAO) patients.

BASIC PROCEDURES

Retrospective comparative study of patients who received IVMP between January 2011 and July 2021 at the Thyroid Eye Clinic, the Chinese University of Hong Kong. Outcome measures included the 7-item clinical activity score (CAS), exophthalmos, extraocular muscle motility (EOMy), marginal reflex distance (MRD), best corrected visual acuity (BCVA), intraocular pressure (IOP), the requirement of additional treatment, and complications.

MAIN FINDINGS

A total of 65 (63% (41/65) females) moderate-to-severe, active TAO patients aged 50 ± 13 (25-74) years received 6-weekly (n = 22) or 12-weekly (n = 43) IVMP. Sex, age, smoking status, and Graves' disease status were comparable in the two groups (all p > 0.05). CAS at week 6 (p = 0.0279), 12 (p = 0.00228), and 52 (p = 0.0228) were lower at each time for the 12-weekly group. Exophthalmos improved more at week 6 (p = 0.0453) and 12 (p = 0.0347) in the 12-weekly group. The improvement of diplopia, MRD1, MRD2, and EOMy were comparable between the two groups. More patients in the 6-weekly group (p = 0.00169) required additional treatments including IVMP+/-ORT. Patients in the 6-weekly group who did not require additional treatment had a lower presenting CAS (p = 0.0193) than those who required additional treatment. The total numbers of adverse events were comparable between the two groups.

Pathophysiology of thyroid-associated orbitopathy

Thyroid-associated orbitopathy, the most common extrathyroidal manifestation of Graves' disease, is characterized by orbital inflammatory infiltration and activation of orbital fibroblasts, which mediates de novo adipogenesis, excessive production of hyaluronan, myofibroblast differentiation and ultimately tissue fibrosis. Interactions among T cells, B cells, and orbital fibroblasts result in their activation and perpetuation of orbital inflammation as well as tissue remodelling. T helper 17 cells belong to a newly identified pathogenic CD4+ T cell subset which possesses prominent pro-inflammatory and profibrotic capabilities. Thyroid stimulating hormone receptor/insulin-like growth factor-1 receptor crosstalk and the downstream signalling pathways of both receptors represent the major mechanisms leading to activation of orbital fibroblasts. Thyroid stimulating hormone receptor autoantibody is the disease specific biomarker of great clinical relevance and utility. There is growing evidence that oxidative stress, gut microbiome and epigenetics also play a role in the pathogenesis and their manipulation may represent novel therapeutic strategies.

M1-Like Macrophages Modulate Fibrosis and Inflammation of Orbital Fibroblasts in Graves' Orbitopathy: Potential Relevance to Soluble Interleukin-6 Receptor

Background: Graves' orbitopathy (GO) is a disfiguring and sight-threatening autoimmune disease. Previous studies have shown the infiltration of macrophages in GO orbital connective tissues. However, the immunophenotypes of macrophages and their modulatory effects on orbital fibroblasts (OFs) have not been examined so far. In this study, we sought to determine the pathophysiology of macrophages in GO. Methods: In this case-control study, orbital connective tissues collected from 40 GO patients and 20 healthy controls were immunohistochemically stained for cytokines and macrophage cell surface antigens. The polarization of orbital-infiltrating macrophages was investigated by flow cytometry and immunofluorescence. Effects of interleukin (IL)-6 combined with soluble IL-6 receptor (sIL-6R) on the proliferation, differentiation, and inflammation of different OF subsets were examined by CCK-8, Western blotting, and Luminex assays, respectively. The antigen-presenting abilities of different OF subsets under IL-6/sIL-6R signaling were studied by proteomics. Finally, the differentiation of CD8⁺ IL-17A-producing T cells by sIL-6R was tested. Results: GO orbital connective tissues displayed increased IL-6, sIL-6R, STAT3, and IL-17A levels. CD86⁺ M1-like macrophages were predominant in active GO patients, while stable GO patients tended to have more CD163⁺ M2-like macrophages. The expression of IL-6 was higher in M1-like macrophages, and the expression of transforming growth factor-β was higher in M2-like macrophages both in GO orbital connective tissues in situ in vivo and in cell culture system in vitro. The IL-6/sIL-6R stimulation promoted the fibrosis of both CD34⁺ and CD34^- OFs. Monocyte chemoattractant protein-1 expression was also induced by IL-6/sIL-6R stimulation in both OF subsets. IL-6/sIL-6R stimulation enhanced the antigen processing of CD34⁺ OFs through upregulating the intact major histocompatibility complex I and antigen transporters. However, the protein expressions of the thyrotropin receptor and insulin-like growth factor 1 receptor could not be directly increased by IL-6/sIL-6R stimulation in CD34⁺ OFs. Furthermore, sIL-6R was conducive to the differentiation of CD8⁺ IL-17A-producing T cells. Conclusions: Our study demonstrated the immunophenotypes of orbital-infiltrating macrophages that may activate OFs depending on the IL-6/sIL-6R signaling in GO. Our preclinical findings implicate, at least in part, the molecular rationale for blocking sIL-6R as a promising therapeutic agent for GO.

The miR-103a-3p/TGFBR3 axis regulates TGF-β-induced orbital fibroblast activation and fibrosis in thyroid-eye disease

Molecular pathways that contribute to orbital fibroblast activation during thyroid-eye disease (TED) may promote TED progression. Non-coding RNAs, especially miRNAs, play a critical role in the pathogenesis of TED. In the present study, miR-103a-3p was dramatically upregulated and TGFBR3 was downregulated within TED orbital tissue samples and TGF-β-stimulated TED orbital fibroblasts. miR-103a-3p inhibition in TGF-β-stimulated TED orbital fibroblasts partially abolished TGF-β-induced fibrotic alterations, as manifested by the impaired fibroblast cell viability and decreased vimentin and fibronectin levels. miR-103a-3p directly targeted TGFBR3 in TED orbital samples and TGF-β-stimulated TED orbital fibroblasts. In TGF-β-stimulated TED orbital fibroblasts, TGFBR3 overexpression inhibited fibroblast cell viability and decreased vimentin and fibronectin levels. TGFBR3 overexpression partially attenuated the inhibitory effects of miR-103a-3p overexpression on TGFBR3 expression and the promotive effects of miR-103a-3p overexpression on TGF-β-induced fibrotic alterations. Under TGF-β stimulation, miR-103a-3p overexpression significantly promoted, whereas TGFBR3 overexpression inhibited the phosphorylation of Erk1/2, JNK, Smad2, and Smad3. TGFBR3 overexpression also partially abolished the effects of miR-103a-3p overexpression on Erk1/2, JNK, Smad2, and Smad3 phosphorylation. In conclusion, the miR-103a-3p/TGFBR3 axis regulated TGF-β-induced TED orbital fibroblast activation and fibrosis in TED, with the possible involvement of the Erk/JNK and TGF-β/Smad signaling pathways.

Macrophage-Orbital Fibroblast Interaction and Hypoxia Promote Inflammation and Adipogenesis in Graves' Orbitopathy

The inflammatory eye disease Graves' orbitopathy (GO) is the main complication of autoimmune Graves' disease. In previous studies we have shown that hypoxia plays an important role for progression of GO. Hypoxia can maintain inflammation by attracting inflammatory cells such as macrophages (MQ). Herein, we investigated the interaction of MQ and orbital fibroblasts (OF) in context of inflammation and hypoxia. We detected elevated levels of the hypoxia marker HIF-1α, the MQ marker CD68, and inflammatory cytokines TNFα, CCL2, CCL5, and CCL20 in GO biopsies. Hypoxia stimulated GO tissues to release TNFα, CCL2, and CCL20 as measured by multiplex enzyme-linked immunosorbent assay (ELISA). Further, TNFα and hypoxia stimulated the expression of HIF-1α, CCL2, CCL5, and CCL20 in OF derived from GO tissues. Immunofluorescence confirmed that TNFα-positive MQ were present in the GO tissues. Thus, interaction of M1-MQ with OF under hypoxia also induced HIF-1α, CCL2, and CCL20 in OF. Inflammatory inhibitors etanercept or dexamethasone prevented the induction of HIF-1α and release of CCL2 and CCL20. Moreover, co-culture of M1-MQ/OF under hypoxia enhanced adipogenic differentiation and adiponectin secretion. Dexamethasone and HIF-1α inhibitor PX-478 reduced this effect. Our findings indicate that GO fat tissues are characterized by an inflammatory and hypoxic milieu where TNFα-positive MQ are present. Hypoxia and interaction of M1-MQ with OF led to enhanced secretion of chemokines, elevated hypoxic signaling, and adipogenesis. In consequence, M1-MQ/OF interaction results in constant inflammation and tissue remodeling. A combination of anti-inflammatory treatment and HIF-1α reduction could be an effective treatment option.

Metformin Attenuates Inflammation and Fibrosis in Thyroid-Associated Ophthalmopathy

The pathogenesis of thyroid-associated ophthalmopathy (TAO) is still unclear, and therapeutic drugs have great limitations. As metformin has multiple therapeutic effects in many autoimmune diseases, we explored the effects of metformin on TAO in an in vitro fibroblast model. We used orbital connective tissues and fibroblasts that were obtained from TAO patients and normal controls. The activity of adenosine monophosphate-activated protein kinase (AMPK) and the levels of inflammatory or fibrotic factors were examined by immunofluorescence (IF) and immunohistochemistry (IHC). Quantitative real-time polymerase chain reaction (qPCR), cytokine quantification by enzyme-linked immunosorbent sssay (ELISA), IF, and western blotting (WB) were used to measure the expression of factors related to inflammation, fibrosis, and autophagy. To determine the anti-inflammatory and antifibrotic mechanisms of metformin, we pretreated cells with metformin, 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR, an AMPK activator) or compound C (CC, an AMPK inhibitor) for 24 h and used WB to verify the changes in protein levels in the AMPK/mammalian target of rapamycin (mTOR) pathway. We determined that the low activity of AMPK in the periorbital tissue of TAO patients may be closely related to the occurrence and development of inflammation and fibrosis, and metformin exerts multiple effects by activating AMPK in TAO. Furthermore, we suggest that AMPK may be a potential target of TAO therapy.

Protective Effects of One 2,4-Dihydro-3H-Pyrazol-3-one Derivative against Posterior Capsular Opacification by Regulation of TGF-β2/SMADs and Non-SMAD Signaling, Collagen I, and Fibronectin Proteins

Many elderly individuals frequently experience cataracts that interfere with vision. After cataract surgery, the left lens epithelial cell (LEC) exhibited fibrosis and posterior capsule opacification (PCO). Sometimes, there is a need for a second surgery; nevertheless, people try other methods, such as a good pharmacological agent, to treat PCO to reduce transforming growth factor-β2 (TGF-β2) amounts to avoid secondary surgery. The aim of the present study was to explore the potential anti-PCO activity of five 2,4-dihydro-3H-pyrazol-3-one (DHPO) derivatives in a TGF-β2-induced fibrogenesis SRA01/04 cell model. The 2-phenyl-5-propyl-DHPO (TSE; no. 2: TSE-2) compound showed the best activity of reduced expression levels of TGF-β2 among five derivatives and therefore was chosen to evaluate the anti-PCO activity and molecular mechanisms on the Sma and mad protein (SMAD) signaling pathway (including TGF-β2, SMADs, and the inhibition of nuclear translocation of SMADs), non-SMAD pathway proteins, including p-extracellular, regulated protein kinases (ERK) 1/2, or p-c-Jun N-terminal kinase (JUN) by Western blotting, PCR, or confocal immunofluorescence analyses. Following treatment with 10 μg/mL of the five compounds, the cells displayed great viability by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTT) assay. In this study, the result of lactate dehydrogenase (LDH) activity measurement did not affect the cytotoxicity of the five compounds. In TGF-β2-induced fibrogenesis in SRA01/04 cells, treatment with the TSE compound decreased the TGF-β2/SMAD signaling genes, including reduced mRNA or expression levels of TGF-β2, SMAD3, and SMAD4, leading to inhibition of TGF-β2-induced fibrogenesis. Our confocal immunofluorescence analyses demonstrated that TSE treatment displays a suppressive effect on SMAD2/3 or SMAD4 translocation to the nucleus. Furthermore, TSE treatment exhibits a reduction in the non-SMAD target gene expression levels of p- c-Jun N-terminal kinase (JUN), p- extracellular, regulated protein kinases (ERK)1/2, p- p38 mitogen-activated protein kinase (p38), p-phosphatidylinositol 3-kinase (PI3K), p-mammalian target of rapamycin complex (mTORC), p-Akt (Ser⁴⁷³), and p-Akt (Thr³⁰⁸). The overall effect of TSE is to reduce the expression levels of collagen I and fibrinogen (FN), thus contributing to antifibrotic effects in cell models mimicking PCO. Our findings reveal the benefits of TSE by regulating TGF-β/SMAD signaling and non-SMAD signaling-related gene proteins to display antifibrotic activity in cells for the possibility of preventing PCO after cataract surgery.

Thinking inside the box: Current insights into targeting orbital tissue remodeling and inflammation in thyroid eye disease

Thyroid eye disease (TED) is an autoimmune disorder that manifests in the orbit. In TED, the connective tissue behind the eye becomes inflamed and remodels with increased fat accumulation and/or increased muscle and scar tissue. As orbital tissue expands, patients develop edema, exophthalmos, diplopia, and optic neuropathy. In severe cases vision loss may occur secondary to corneal scarring from exposure or optic nerve compression. Currently there is no cure for TED, and treatments are limited. A major breakthrough in TED therapy occurred with the FDA approval of teprotumumab, a monoclonal insulin-like growth factor 1 receptor (IGF1R) blocking antibody. Yet, teprotumumab therapy has limitations, including cost, infusion method of drug delivery, variable response, and relapse. We describe approaches to target orbital fibroblasts and the complex pathophysiology that underlies tissue remodeling and inflammation driving TED. Further advances in the elucidation of the mechanisms of TED may lead to prophylaxis based upon early biomarkers as well as lead to more convenient, less expensive therapies.

Mechanisms in Graves Eye Disease: Apoptosis as the End Point of Insulin-Like Growth Factor 1 Receptor Inhibition

Background: Graves' eye disease, also called Graves' orbitopathy (GO), is a potentially debilitating autoimmune disease associated with retro-orbital inflammation and tissue expansion, involving both fibroblasts and adipocytes, resulting in periorbital edema, worsening proptosis, and muscle dysfunction with diplopia and may ultimately threaten sight. Accumulating evidence has indicated that autoantibodies to the thyrotropin receptor (TSHR), which induce the hyperthyroidism of Graves' disease, also help mediate the pathogenesis of the eye disease in susceptible individuals through TSHR expression on retro-orbital cells. Since it has long been known that the effects of insulin-like growth factor 1 (IGF-1) and thyrotropin are additive, recent clinical trials with a human monoclonal IGF-1 receptor blocking antibody (teprotumumab; IGF-1R-B-monoclonal antibody [mAb]) have demonstrated its ability to induce significant reductions in proptosis, diplopia, and clinical activity scores in patients with GO. However, the molecular mechanisms by which such an antibody achieves this result is unclear. Methods: We have used Li-Cor In-Cell Western, Western blot, and immunohistochemistry to define levels of different proteins in mouse and human fibroblast cells. Proteomic array was also used to define pathway signaling molecules. Using CCK-8 and BrdU cell proliferation ELISA, we have analyzed proliferative response of these cells to different antibodies. Results: We now show that a stimulating TSHR antibody was able to induce phosphorylation of the IGF-1R and initiate both TSHR and IGF-1R signaling in mouse and human fibroblasts. IGF-1R-B-mAb (1H7) inhibited all major IGF-1R signaling cascades and also reduced TSHR signaling. This resulted in the antibody-induced suppression of autophagy as shown by inhibition of multiple autophagy-related proteins (Beclin1, LC3a, LC3b, p62, and ULK1) and the induction of cell death by apoptosis as evidenced by activation of cleaved caspase 3, FADD, and caspase 8. Furthermore, this IGF-1R-blocking mAb suppressed serum-induced perkin and pink mitophagic proteins. Conclusions: Our observations clearly indicated that stimulating TSHR antibodies were able to enhance IGF-1R activity and contribute to retro-orbital cellular proliferation and inflammation. In contrast, an IGF-1R-B-mAb was capable of suppressing IGF-1R signaling leading to retro-orbital fibroblast/adipocyte death through the cell-extrinsic pathway of apoptosis. This is likely the major mechanism involved in proptosis reduction in patients with Graves' eye disease treated by IGF-1R inhibition.

Disulfiram Exerts Antiadipogenic, Anti-Inflammatory, and Antifibrotic Therapeutic Effects in an In Vitro Model of Graves' Orbitopathy

Background: Adipogenesis, glycosaminoglycan hyaluronan (HA) production, inflammation, and fibrosis are the main pathogenic mechanisms responsible for Graves' orbitopathy (GO). We hypothesized that disulfiram (DSF), an aldehyde dehydrogenase (ALDH) inhibitor used to treat alcoholism, would have therapeutic effects on orbital fibroblasts (OFs) in GO. This study aimed at determining the therapeutic effects and underlying mechanisms of DSF on these parameters. Methods: Primary cultures of OFs from six GO patients and six control subjects were established. The OFs were allowed to differentiate into adipocytes and treated with various concentrations of DSF. Lipid accumulation within the cells was evaluated by Oil Red O staining. Real-time polymerase chain reaction (RT-PCR) and Western blotting were used to measure the expression of key adipogenic transcription factors, ALDH1A1, ALDH2, and mitogen-activated protein kinase (MAPK) signaling proteins. Apoptosis assays and reactive oxygen species levels were evaluated by flow cytometry. HA production was measured by using an enzyme-linked immunosorbent assay (ELISA) kit. The mRNA levels of proinflammatory molecules were measured by using RT-PCR after interleukin (IL)-1β stimulation with or without DSF. The mRNA expression of markers associated with fibrosis was examined by using RT-PCR after transforming growth factor (TGF)-β1 stimulation with or without DSF. The wound-healing assay was assessed by phase-contrast microscopy. Results: Under identical adipogenesis conditions, GO OFs effectively differentiated, while normal control (NC) OFs did not. DSF dose dependently suppressed lipid accumulation during adipogenesis in GO OFs. The expression of key adipogenic transcription factors, such as perilipin-1 (PLIN1), PPARγ (PPARG), FABP4, and c/EBPα (CEBPA), was downregulated. Further, DSF inhibited the phosphorylation of ERK by inhibiting ALDH1A1. In addition, DSF attenuated HA production and suppressed inflammatory molecule expression induced by IL-1β in GO OFs and NC OFs. The antifibrotic effects of DSF on TGF-β1 were also observed in GO OFs. Conclusions: In the current study, we provide evidence of the inhibitory effect of DSF on GO OFs adipogenesis, HA production, inflammation, and fibrosis in vitro. The results of this study are noteworthy and indicate the potential use of DSF as a therapeutic agent for the treatment of GO.

An Early Wave of Macrophage Infiltration Intertwined with Antigen-Specific Proinflammatory T Cells and Browning of Adipose Tissue Characterizes the Onset of Orbital Inflammation in a Mouse Model of Graves' Orbitopathy

Background: Graves' orbitopathy (GO) is an autoimmune-driven manifestation of Graves' disease (GD) where pathogenic autoantibodies to the thyrotropin receptor (TSHR) activate orbital fibroblasts/preadipocytes in the orbital tissue to induce inflammation and extracellular matrix deposition. Since there are significant limitations to study immunological and proinflammatory mediator expression in early and during disease progression in GO patients, we used our experimental mouse model to elucidate early pathogenic processes. Methods: We have developed a robust mouse model of GD/GO induced by electroporation immunization of plasmid encoding human TSHR A-subunit, comprising multiple injections over a course of 15 weeks to fully recapitulate the orbital pathology. In this study, we investigated kinetics of GO development in the model by serial analyses of immunological and cellular parameters during course of orbital inflammation. Results: Pathogenic anti-TSHR antibodies with thyroid-stimulating properties developed early after the second immunization step with concomitant induction of hyperthyroidism. Examination of orbital tissue showed an early wave of macrophage infiltration followed subsequently by CD3⁺ T cells into the orbital tissue. Examination of antigen-specific T cell activity using recombinant human A-subunit protein showed high CD8⁺ T cell proliferation during this early phase of disease onset, whereas effector CD4⁺ T cells and CD25⁺FOXP3⁺ regulatory T cells (Tregs) were downregulated. The early phase of disease was also characterized by abundant presence of proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α). Moreover, as the disease progressed, there was significant increase in browning of orbital fat tissue, which may be dependent on the proinflammatory milieu and/or the increased thyroid hormone levels during the established hyperthyroid status. Conclusions: This work revealed early infiltration of macrophages in the orbital region and induction of pathogenic anti-TSHR antibodies during disease onset in the model. This was followed subsequently by influx of CD8⁺ T cells specific for TSHR coupled with reduction in Tregs and substantial increase in brown adipose tissue. These new insights into the development of orbital inflammation in the model have implications for testing new therapeutic regimens by targeting macrophage function during early phases of orbital inflammation in the model.

Dihydroartemisinin Exerts Antifibrotic and Anti-Inflammatory Effects in Graves' Ophthalmopathy by Targeting Orbital Fibroblasts

Graves' ophthalmopathy (GO) is a common orbital disease that threatens visual function and appearance. Orbital fibroblasts (OFs) are considered key target and effector cells in GO. In addition, hyaluronan (HA) production, inflammation, and orbital fibrosis are intimately linked to the pathogenesis of GO. In this study, we explored the therapeutic effects of dihydroartemisinin (DHA), an antimalarial drug, on GO-derived, primary OFs. CCK8 and EdU assays were applied to evaluate the antiproliferative effect of DHA on OFs. Wound healing assays were conducted to assess OF migration capacity, while qRT-PCR, western blotting, ELISA, and immunofluorescence were used to determine the expression of fibrosis-related and pro-inflammatory markers in these cells. Moreover, RNA sequencing was conducted to identify differentially expressed genes (DEGs) in DHA-treated OFs, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs was performed to explore potential mechanisms mediating the antifibrotic effect of DHA on GO-derived OFs. Results showed that DHA dose-dependently inhibited OF proliferation and downregulated, at the mRNA and protein levels, TGF-β1-induced expression of fibrosis markers, including alpha smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF). Furthermore, DHA inhibited TGF-β1 induced phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3), which suggested that DHA exerted antifibrotic effects via suppression of the ERK and STAT3 signaling pathways. In addition, DHA suppressed the expression of pro-inflammatory cytokines and chemokines, including IL-6, IL-8, CXCL-1, MCP-1, and ICAM-1, and attenuated HA production induced by IL-1β in GO-derived OFs. In conclusion, our study provides first-time evidence that DHA may significantly alleviate pathogenic manifestations of GO by inhibiting proliferation, fibrosis- and inflammation-related gene expression, and HA production in OFs. These data suggest that DHA may be a promising candidate drug for treatment of GO.

Interleukin-16 rs4072111 Polymorphism is Associated with the Risk of Peri-Implantitis in the Chinese Population

Purpose

Peri-implantitis (PI) is a major contributor to dental implant failure. Genetic predisposition plays an essential role in the development of PI. The purpose of this study was to investigate the correlation of IL-16 gene single nucleotide polymorphisms (SNPs), rs11556218 and rs4072111, with PI at the gene level.

Patients and Methods

A total of 162 patients with PI and 162 cases with healthy implants were recruited as the case and control groups, respectively. The genotypes were analysed using direct sequencing. The genotype and allele proportion between the case and control groups were compared using the chi-square test. The periodontal status of patients carrying different genotypes was analysed, including gingival index, plaque index, calculus index, peri-implant pocket depth (PPD), and clinical attachment level (CAL).

Results

The case and control groups were age- and gender-matched. In the case group, the rs4072111 CT genotype was majorly observed, and the T allele carriers showed a high PI risk. Patients with the rs4072111 CT genotype had worse periodontal status, which was reflected by the higher levels of the gingival index, plaque index, calculus index, PPD and CAL. The distribution of the rs11556218 genotype and T allele showed no significant difference between the case and control groups (P > 0.05).

Conclusion

The CT genotype of IL-16 gene rs4072111 SNP can be used as a factor assessing PI risk. Therefore, IL-16 genetic variation may be related to PI susceptibility in the Chinese Han population.

Effect of Pirfenidone on TGF-β1-Induced Myofibroblast Differentiation and Extracellular Matrix Homeostasis of Human Orbital Fibroblasts in Graves' Ophthalmopathy

Pirfenidone is a pyridinone derivative that has been shown to inhibit fibrosis in animal models and in patients with idiopathic pulmonary fibrosis. Its effect on orbital fibroblasts remains poorly understood. We investigated the in vitro effect of pirfenidone in transforming growth factor-β1 (TGF-β1)-induced myofibroblast transdifferentiation and extracellular matrix (ECM) homeostasis in primary cultured orbital fibroblasts from patients with Graves' ophthalmopathy (GO). The expression of fibrotic proteins, including α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), fibronectin, and collagen type I, was determined by Western blots. The activities of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) responsible for the ECM homeostasis were examined. After pretreating the GO orbital fibroblasts with pirfenidone (250, 500, and 750 μg/mL, respectively) for one hour followed by TGF-β1 for another 24 h, the expression of α-SMA, CTGF, fibronectin, and collagen type I decreased in a dose-dependent manner. Pretreating the GO orbital fibroblasts with pirfenidone not only abolished TGF-β1-induced TIMP-1 expression but recovered the MMP-2/-9 activities. Notably, pirfenidone inhibited TGF-β1-induced phosphorylation of p38 and c-Jun N-terminal kinase (JNK), the critical mediators in the TGF-β1 pathways. These findings suggest that pirfenidone modulates TGF-β1-mediated myofibroblast differentiation and ECM homeostasis by attenuating downstream signaling of TGF-β1.

Association of fibroblast growth factor 10 with the fibrotic and inflammatory pathogenesis of Graves' orbitopathy

Purpose

The role of fibroblast growth factor (FGF) in orbital fibroblasts (OFs) is rarely known. In this study, we investigated the effect of FGF10 on fibrosis and the inflammation mechanism of Graves′ orbitopathy (GO).

Methods

Orbital tissue from GO (n = 15) and non-GO (n = 15) was obtained for this study. The mRNA and protein expression levels of FGF10 and FGF receptor 2b (FGFR2b) in orbital tissue were determined by real-time polymerase chain reaction, western blot analysis, and confocal microscopy. The effects of FGF10 on transforming growth factor (TGF)-β1 induced fibrotic proteins and interleukin (IL)-1β- or tumor necrosis factor (TNF)-α- induced inflammatory proteins were investigated using recombinant human (rh) FGF10 and small interfering (si) RNA transfection against FGF10.

Results

FGF10 and FGFR2b mRNA expression levels were significantly lower in GO orbital tissues than in non-GO orbital tissues (p = 0.009 and 0.005, respectively). Immunostaining of FGF10 in orbital adipose tissues showed differences in FGF10 expression between GO and control samples. Immunostaining of FGF10 was very weak in the orbital tissues of GO patients. TGF-β1-induced fibronectin, collagen Iα, α-smooth muscle actin protein expression in GO OFs was attenuated by rhFGF10 treatment and increased by knockdown of FGF10 via siFGF10 transfection. Similarly, IL-1β- or TNF-α-induced IL-6, IL-8, and cyclooxygenase-2 protein production in GO OFs was either blocked by rhFGF10 treatment or further upregulated by inhibition of FGF10 via siFGF10 transfection.

Conclusions

Our data demonstrate that FGF10 has beneficial effects on the inflammatory and fibrotic mechanisms of GO in primary cultured OFs, providing new insights into GO pathology and the discovery of FGF10 as a promising novel therapeutic application for the treatment of GO.

Curcumin Suppresses TGF-β1-Induced Myofibroblast Differentiation and Attenuates Angiogenic Activity of Orbital Fibroblasts

Orbital fibrosis, a hallmark of tissue remodeling in Graves’ ophthalmopathy (GO), is a chronic, progressive orbitopathy with few effective treatments. Orbital fibroblasts are effector cells, and transforming growth factor β1 (TGF-β1) acts as a critical inducer to promote myofibroblast differentiation and subsequent tissue fibrosis. Curcumin is a natural compound with anti-fibrotic activity. This study aims to investigate the effects of curcumin on TGF-β1-induced myofibroblast differentiation and on the pro-angiogenic activities of orbital fibroblasts. Orbital fibroblasts from one healthy donor and three patients with GO were collected for primary cell culture and subjected to myofibroblast differentiation under the administration of 1 or 5 ng/mL TGF-β1 for 24 h. The effects of curcumin on TGF-β1-induced orbital fibroblasts were assessed by measuring the cellular viability and detecting the expression of myofibroblast differentiation markers, including connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA). The pro-angiogenic potential of curcumin-treated orbital fibroblasts was evaluated by examining the transwell migration and tube-forming capacities of fibroblast-conditioned EA.hy926 and HMEC-1 endothelial cells. Treatment of orbital fibroblasts with curcumin inhibited the TGF-β1 signaling pathway and attenuated the expression of CTGF and α-SMA induced by TGF-β1. Curcumin, at the concentration of 5 μg/mL, suppressed 5 ng/mL TGF-β1-induced pro-angiogenic activities of orbital fibroblast-conditioned EA hy926 and HMEC-1 endothelial cells. Our findings suggest that curcumin reduces the TGF-β1-induced myofibroblast differentiation and pro-angiogenic activity in orbital fibroblasts. The results support the potential application of curcumin for the treatment of GO.

JNK and p38 Inhibitors Prevent Transforming Growth Factor-β1-Induced Myofibroblast Transdifferentiation in Human Graves' Orbital Fibroblasts

Transforming growth factor-β1 (TGF-β1)-induced myofibroblast transdifferentiation from orbital fibroblasts is known to dominate tissue remodeling and fibrosis in Graves’ ophthalmopathy (GO). However, the signaling pathways through which TGF-β1 activates Graves’ orbital fibroblasts remain unclear. This study investigated the role of the mitogen-activated protein kinase (MAPK) pathway in TGF-β1-induced myofibroblast transdifferentiation in human Graves’ orbital fibroblasts. The MAPK pathway was assessed by measuring the phosphorylation of p38, c-Jun N-terminal kinase (JNK), and extracellular-signal-regulated kinase (ERK) by Western blots. The expression of connective tissue growth factor (CTGF), α-smooth muscle actin (α-SMA), and fibronectin representing fibrogenesis was estimated. The activities of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) responsible for extracellular matrix (ECM) metabolism were analyzed. Specific pharmacologic kinase inhibitors were used to confirm the involvement of the MAPK pathway. After treatment with TGF-β1, the phosphorylation levels of p38 and JNK, but not ERK, were increased. CTGF, α-SMA, and fibronectin, as well as TIMP-1 and TIMP-3, were upregulated, whereas the activities of MMP-2/-9 were inhibited. The effects of TGF-β1 on the expression of these factors were eliminated by p38 and JNK inhibitors. The results suggested that TGF-β1 could induce myofibroblast transdifferentiation in human Graves’ orbital fibroblasts through the p38 and JNK pathways.

A novel CD4+ CTL subtype characterized by chemotaxis and inflammation is involved in the pathogenesis of Graves' orbitopathy

Graves' orbitopathy (GO), the most severe manifestation of Graves' hyperthyroidism (GH), is an autoimmune-mediated inflammatory disorder, and treatments often exhibit a low efficacy. CD4+ T cells have been reported to play vital roles in GO progression. To explore the pathogenic CD4+ T cell types that drive GO progression, we applied single-cell RNA sequencing (scRNA-Seq), T cell receptor sequencing (TCR-Seq), flow cytometry, immunofluorescence and mixed lymphocyte reaction (MLR) assays to evaluate CD4+ T cells from GO and GH patients. scRNA-Seq revealed the novel GO-specific cell type CD4+ cytotoxic T lymphocytes (CTLs), which are characterized by chemotactic and inflammatory features. The clonal expansion of this CD4+ CTL population, as demonstrated by TCR-Seq, along with their strong cytotoxic response to autoantigens, localization in orbital sites, and potential relationship with disease relapse provide strong evidence for the pathogenic roles of GZMB and IFN-γ-secreting CD4+ CTLs in GO. Therefore, cytotoxic pathways may become potential therapeutic targets for GO.

FGF/FGFR signaling in health and disease

Growing evidences suggest that the fibroblast growth factor/FGF receptor (FGF/FGFR) signaling has crucial roles in a multitude of processes during embryonic development and adult homeostasis by regulating cellular lineage commitment, differentiation, proliferation, and apoptosis of various types of cells. In this review, we provide a comprehensive overview of the current understanding of FGF signaling and its roles in organ development, injury repair, and the pathophysiology of spectrum of diseases, which is a consequence of FGF signaling dysregulation, including cancers and chronic kidney disease (CKD). In this context, the agonists and antagonists for FGF-FGFRs might have therapeutic benefits in multiple systems.

Characteristics of Hyaluronan Synthesis Inhibition by 4-Methylumbelliferone in Orbital Fibroblasts

Purpose

Hyaluronan (HA) overproduction by orbital fibroblasts (OFs) is a major factor in the pathogenesis of Graves' orbitopathy (GO). 4-methylumbelliferone (4-MU) is an inhibitor of HA synthesis in different cell types in vitro and has beneficial effects in animal models of autoimmune diseases.

Methods

HA production and mRNA expression of HA synthases (HAS1, HAS2, and HAS3) and hyaluronidases (HYAL1 and HYAL2) were measured in the presence and absence of 4-MU in unstimulated and transforming growth factor-β-stimulated fibroblasts from GO orbital (n = 4), non-GO orbital (n = 4), and dermal origin (n = 4).

Results

The 4-MU treatment (1 mM) for 24 hours resulted in an average 87% reduction (P < 0.001) of HA synthesis, decreased the expression of the dominant HAS isoform (HAS2) by 80% (P < 0.0001), and increased the HYAL2 expression by 2.5-fold (P < 0.001) in control OFs, GO OFs, and dermal fibroblasts (DFs) regardless of the origin of the cells. The proliferation rate of all studied cell lines was reduced to an average 16% by 4-MU (P < 0.0001) without any effects on cell viability. HA production stimulated by transforming growth factor-β was decreased by 4-MU via inhibition of stimulated HAS1 expression in addition to the observed effects of 4-MU in unstimulated cases. Characteristics of HA synthesis inhibition by 4-MU did not differ in OFs compared with DFs.

Conclusions

4-MU has been found to inhibit the HA synthesis and the proliferation rate in OFs in vitro, adding it to the list of putative therapeutic agents in a disease the cure of which is largely unresolved.

Immunohistochemical analysis of human orbital tissue in Graves' orbitopathy

PURPOSE

Immunohistochemistry of orbital tissues offers a correlation between the microscopic changes and macroscopic clinical manifestation of Graves' orbitopathy (GO). Summarizing the participation of different molecules will help us to understand the pathogenesis of GO.

METHODS

The pertinent and current literature on immunohistochemistry of human orbital tissue in GO was reviewed using the NCBI PubMed database.

RESULTS

33 articles comprising over 700 orbital tissue samples were included in this review. The earliest findings included the demonstration of HLA-DR and T cell (to a lesser extent B cell) markers in GO orbital tissues. Subsequent investigators further contributed by characterizing cellular infiltration, confirming the presence of HLA-DR and TSHR, as well as revealing the participation of cytokines, growth factors, adhesion molecules and miscellaneous substances. HLA-DR and TSHR are over-expressed in orbital tissues of GO patients. The inflammatory infiltration mainly comprises CD4 + T cells and macrophages. Cytokine profile suggests the importance of Th1 (especially in early active phase) and Th17 immunity in the pathogenesis of GO. Upregulation of proinflammatory/profibrotic cytokines, adhesion molecules and growth factors finally culminate in activation of orbital fibroblasts and perpetuation of orbital inflammation. The molecular status of selected parameters correlates with the clinical presentation of GO.

CONCLUSION

Further investigation is warranted to define precisely the role of different molecules and ongoing search for new players yet to be discovered is also important. Unfolding the molecular mechanisms behind GO will hopefully provide insights into the development of novel therapeutic strategies and optimize our clinical management of the disease.

New insights into the pathogenesis and nonsurgical management of Graves orbitopathy

Graves orbitopathy, also known as thyroid eye disease or thyroid-associated orbitopathy, is visually disabling, cosmetically disfiguring and has a substantial negative impact on a patient's quality of life. There is increasing awareness of the need for early diagnosis and rapid specialist input from endocrinologists and ophthalmologists. Glucocorticoids are the mainstay of treatment; however, recurrence occurs frequently once these are withdrawn. Furthermore, in >60% of cases, normal orbital anatomy is not restored, and skilled rehabilitative surgery is required. Clinical trials have shown that considerable benefit can be derived from the addition of antiproliferative agents (such as mycophenolate or azathioprine) in preventing deterioration after steroid cessation. In addition, targeted biologic therapies have shown promise, including teprotumumab, which reduces proptosis, rituximab (anti-CD20), which reduces inflammation, and tocilizumab, which potentially benefits both of these parameters. Other strategies such as orbital radiotherapy have had their widespread role in combination therapy called into question. The pathophysiology of Graves orbitopathy has also been revised with identification of new potential therapeutic targets. In this Review we provide an up-to-date overview of the field, outline the optimal management of Graves orbitopathy and summarize the research developments in this area to highlight future research questions and direct future clinical trials.

Macrophages promote a profibrotic phenotype in orbital fibroblasts through increased hyaluronic acid production and cell contractility

Graves’ orbitopathy (GO) is an autoimmune inflammatory disease affecting the orbit. Orbital fibroblasts are a key component in GO pathogenesis, which includes inflammation, adipogenesis, hyaluronic acid (HA) secretion, and fibrosis. Macrophages are thought to participate in the immunological stage of GO, but whether they can directly affect the fibroblasts phenotype and modulate disease progression is unknown. We previously showed that GO adipogenic and fibrotic phenotypes could be modelled in a pseudo-physiological 3D environment in vitro. Here, we introduced macrophages in this 3D culture model to investigate role for macrophages in modulating adipogenesis, HA production, and contractility in orbital fibroblasts. Macrophages had a minimal effect on lipid droplet formation in fibroblasts, but significantly increased HA production and cell contractility, suggesting that they may promote the fibrotic phenotype. This effect was found to be mediated at least in part through phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) activation and linked to an increase in actin polymerization and protrusive activity in fibroblasts. Overall our work shows for the first time a direct role for macrophages in modulating the fibroblasts’ phenotype in GO, supporting a role for macrophages in the progression of the fibrotic phenotype through induction of HA production and stimulation of the contractile phenotype in orbital fibroblasts.

Basic Fibroblast Growth Factor Induces Adipogenesis in Orbital Fibroblasts: Implications for the Pathogenesis of Graves' Orbitopathy

BACKGROUND

Basic fibroblast growth factor (bFGF) has been implicated in the pathogenesis of Graves' orbitopathy (GO). It stimulates several processes, including hyaluronan synthesis, involved in orbital tissue volume expansion and may act synergistically with platelet-derived growth factor (PDGF)-BB. PDGF-BB is known to stimulate adipogenesis in orbital fibroblasts, but the effect of bFGF on adipogenesis in orbital fibroblasts is so far unknown. This study was conducted to determine whether (i) bFGF induces adipogenesis in orbital fibroblasts, (ii) bFGF and PDGF-BB together exert an additive or synergistic effect on adipogenesis, and (iii) treatment directed at bFGF- and PDGF-BB signaling may potentially be of interest for the treatment of GO.

METHODS

Orbital fibroblasts from GO patients and controls were cultured in adipocyte differentiation medium with or without bFGF and/or PDGF-BB at different concentrations. Adipogenesis was determined by Oil Red O staining and messenger RNA expression of the late adipocyte differentiation markers cell death-inducing DFFA-like effector C (CIDEC) and adiponectin (ADIPOQ). To demonstrate involvement of FGF-receptor and PDGF-receptor signaling, experiments were also conducted in the presence of dasatinib (inhibitor of PDGF-receptor) or nintedanib (inhibitor of PDGF-receptor and FGF-receptor).

RESULTS

bFGF significantly stimulated adipogenesis by orbital fibroblasts, as shown by increased Oil Red O staining and CIDEC and ADIPOQ expression after 14 days of differentiation. Furthermore, an additive effect of bFGF/PDGF-BB co-stimulation on adipogenesis was observed at the lowest concentration (12.5 ng/mL) of the growth factors tested. Nintedanib completely inhibited bFGF-, PDGF-BB-, and bFGF/PDGF-BB-induced adipogenesis, while dasatinib only fully abrogated PDGF-BB-induced adipogenesis.

CONCLUSION

bFGF induces adipogenesis in orbital fibroblasts and as such may contribute to GO. The additive effect of bFGF and PDGF-BB on adipogenesis, along with the observed inhibitory effects of dasatinib and nintedanib, point at independent receptor-mediated effects. This supports the hypothesis that multi-target directed therapy might be more efficient in the treatment of GO.

Endothelial Cell Growth Promoting Activity in Graves' Disease Sera is Neutralized by Anti-Basic Fibroblast Growth Factor Antibodies in Patients with Fat Expansive but Not Infiltrative Orbitopathy

PURPOSE

To report a case of orbital fat expansion leading to globe prolapse in a Graves' disease patient undergoing high-dose glucocorticoid therapy. To evaluate the growth factor receptor specificities of plasma autoantibodies in Graves' disease patients who exhibited contrasting subtypes of thyroid-associated ophthalmopathy, i.e. orbital fat expansion-type vs. infiltrative.

METHODS

Sera from Graves' orbitopathy and control patients with or without Graves' disease were subjected to protein-A affinity chromatography to obtain immunoglobulin G. A (1/50th to 1/1600th) range in dilutions of the protein-A eluate fraction was incubated for four days at 37 degrees C with bovine pulmonary artery endothelial cells to test for endothelial cell inhibition or stimulation. Growth stimulatory autoantibodies were co-incubated with specific neutralizing anti-insulin like growth factor 1 receptor antibodies or anti-basic fibroblast growth factor antibodies to assess autoantibody specificity in contrasting Graves' orbitopathy subtypes.

RESULTS

We observed increased mean endothelial cell growth promoting activity in the protein-A eluates of serum from eighteen patients with active Graves' disease (117 ± 28%, n = 18) compared to mean endothelial cell activity (89 ± 10%, n = 13, P = 0.003) in thirteen adults without Graves' disease. The protein-A eluate fraction in acute infiltrative-type Graves' orbitopathy contained a high titer (> 1:1000) of endothelial cell stimulatory activity which was significantly neutralized by specific monoclonal anti-human insulin-like growth factor 1 receptor antibodies. The protein-A eluate fraction in fat expansion-type Graves' orbitopathy contained endothelial cell inhibitory activity (at low titers) and stimulatory activity (at high titers), and the latter stimulatory activity was completely neutralized by specific anti-basic fibroblast growth factor antibodies.

CONCLUSION

Graves' disease suffering globe prolapse secondary to marked orbital fat-expansion had coexisting plasma fibroblast growth factor-inhibitory and -stimulatory autoantibodies. The latter was completely neutralized by anti-basic fibroblast growth factor antibodies.

Molecular biomarkers of Graves' ophthalmopathy

Graves' ophthalmopathy (GO), a complication of Graves' disease (GD), is typified by orbital inflammation, ocular tissue expansion and remodeling and, ultimately, fibrosis. Orbital fibroblasts are key effectors of GO pathogenesis exhibiting exaggerated inflammatory and fibroproliferative responses to cytokines released by infiltrating immune cells. Activated orbital fibroblasts also produce inflammatory mediators that contribute to disease progression, facilitate the orbital trafficking of monocytes and macrophages, promote differentiation of matrix-producing myofibroblasts and stimulate accumulation of a hyaluronan-rich stroma, which leads to orbital tissue edema and fibrosis. Proteomic and transcriptome profiling of the genomic response of ocular and non-ocular fibroblasts to INF-γ and TGF-β1 focused on identification of translationally-relevant therapeutic candidates. Induction of plasminogen activator inhibitor-1 (PAI-1, SERPINE1), a clade E member of the serine protease inhibitor (SERPIN) gene family and a prominent regulator of the pericellular proteolytic microenvironment, was one of the most highly up-regulated proteins in INF-γ- or TGF-β1-stimulated GO fibroblasts as well as in severe active GD compared to patients without thyroid disease. PAI-1 has multifunctional roles in inflammatory and fibrotic processes that impact tissue remodeling, immune cell trafficking and survival as well as signaling through several receptor systems. This review focuses on the pathophysiology of the GO fibroblast and possible targets for effective drug therapy.

Essential role of connective tissue growth factor (CTGF) in transforming growth factor-β1 (TGF-β1)-induced myofibroblast transdifferentiation from Graves' orbital fibroblasts

Connective tissue growth factor (CTGF) associated with transforming growth factor-β (TGF-β) play a pivotal role in the pathophysiology of many fibrotic disorders. However, it is not clear whether this interaction also takes place in GO. In this study, we investigated the role of CTGF in TGF-β-induced extracellular matrix production and myofibroblast transdifferentiation in Graves’ orbital fibroblasts. By Western blot analysis, we demonstrated that TGF-β1 induced the expression of CTGF, fibronectin, and alpha-smooth muscle actin (α-SMA) in Graves’ orbital fibroblasts. In addition, the protein levels of fibronectin and α-SMA in Graves’ orbital fibroblasts were also increased after treatment with a recombinant human protein CTGF (rhCTGF). Moreover, we transfected the orbital fibroblasts with a small hairpin RNA of CTGF gene (shCTGF) to knockdown the expression levels of CTGF, which showed that knockdown of CTGF significantly diminished TGF-β1-induced expression of CTGF, fibronectin and α-SMA proteins in Graves’ orbital fibroblasts. Furthermore, the addition of rhCTGF to the shCTGF-transfected orbital fibroblasts could restore TGF-β1-induced expression of fibronectin and α-SMA proteins. Our findings demonstrate that CTGF is an essential downstream mediator for TGF-β1-induced extracellular matrix production and myofibroblast transdifferentiation in Graves’ orbital fibroblasts and thus may provide with a potential therapeutic target for treatment of GO.

Regulation of Orbital Fibrosis and Adipogenesis by Pathogenic Th17 Cells in Graves Orbitopathy

CONTEXT

T helper (Th)17 cells are correlated with many human autoimmune disorders, including Graves disease, and may play key roles in the pathogenesis of Graves orbitopathy (GO).

OBJECTIVE

To study the phenotype of Th17 cells in patients with GO and healthy subjects, investigate the fibrosis and adipogenesis in orbital fibroblasts (OFs) modulated by interleukin (IL)-17A, and determine the interaction between Th17 cells and OFs.

DESIGN/SETTING/PARTICIPANTS

Blood samples and orbital tissues from GO patients and healthy controls were collected.

MAIN OUTCOME MEASURES

We conducted multicolor flow cytometry, immunohistochemical and immunofluorescent stainings, Western blotting, a PathScan intracellular signaling assay, Luminex and enzyme-linked immunosorbent assays, and protein mass spectrum.

RESULTS

Interferon-γ- and IL-22-expressing Th17 cells are increased in GO patients, which are positively related to clinical activity score. Costimulatory molecules are highly expressed in GO orbits and most GO OFs are CD90+. IL-17A promotes TGF-β-induced fibrosis in CD90+ OFs but impedes 15-deoxy-Δ12,14-prostaglandin J2-induced adipogenesis in CD90- OFs. Th17 cells promote proinflammatory cytokine secretion in both CD90+ and CD90- OFs. Meanwhile, both CD90+ and CD90- OFs contribute to Th17 cell differentiation through prostaglandin E2 production, which can be attenuated by indomethacin. Furthermore, Th17 cells upregulate costimulatory molecule expression on OFs.

CONCLUSION

Our findings unravel the pathogenicity of IL-17A in the initiation and progression of GO. In-depth interpretation of the molecular basis of OFs delineated by CD90 and Th17-OF interaction will help to afford a novel approach to better therapeutic strategies for GO.

Orbital fibroblasts of Graves' orbitopathy stimulated with proinflammatory cytokines promote B cell survival by secreting BAFF

The success of rituximab for the treatment of active Graves' orbitopathy (GO) suggests that B cells play a critical role in intraorbital inflammation. B cell activating factor (BAFF) and its homolog a proliferation-inducing ligand (APRIL) are critical for B cell survival. However, the contribution of BAFF/APRIL to GO remains unclear. We sought to determine the role of BAFF/APRIL in the orbits of GO, and found that BAFF was markedly upregulated, while APRIL was not. Additionally, cultured GO orbital fibroblasts (GO-OFs)² expressing BAFF were induced to produce a large amount of BAFF. In contrast, a weak APRIL expression was detected in the OFs, and they exhibited a slight response to stimulation. Notably, pretreated GO-OFs promoted B cell survival, and this effect was significantly inhibited by a BAFF-R neutralizing antibody. This study indicates that OFs from GO can express BAFF and mediate the intraorbital survival of B cells via BAFF mechanism.

Basic FGF and PDGF-BB synergistically stimulate hyaluronan and IL-6 production by orbital fibroblasts

Orbital fibroblast activation is a central pathologic feature of Graves' Ophthalmopathy (GO). Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) have been proposed to contribute to GO, but their effects on orbital fibroblasts are largely unknown. We found that bFGF stimulated proliferation and hyaluronan production, but not IL-6 production by orbital fibroblasts, while VEGF hardly affected orbital fibroblast activity. Remarkably, co-stimulation of orbital fibroblasts with bFGF and PDGF-BB synergistically enhanced IL-6 and hyaluronan production and displayed an additive effect on proliferation compared to either bFGF or PDGF-BB stimulation. Nintedanib, a FGF- and PDGF-receptor targeting drug, more efficiently blocked bFGF + PDGF-BB-induced IL-6 and hyaluronan production than dasatinib that only targets PDGF-receptor. In conclusion, bFGF may contribute to orbital inflammation and tissue remodeling in GO, especially through synergistic interaction with PDGF-BB. Multi-target therapy directed at the bFGF and PDGF pathways may potentially be of interest for the treatment of GO.

Overexpression of collagen XIII in extraocular fat affected by active thyroid-associated ophthalmopathy: A crucial piece of the puzzle?

Thyroid-associated ophthalmopathy (TAO) causes irreversible increase in extraocular fat volume that contributes to the risk of exophthalmos and compressive optic neuropathy. Collagen XIII is implicated in uncontrolled cell growth in some tumours, but we are not aware of any studies of collagen XIII in TAO-affected solid tissue to date. We conducted immunohistochemical staining for collagen XIII alpha 1 (COL13A1), present in both the transmembrane and cleaved forms of collagen XIII, in consecutive prospectively collected human extraocular tissue specimens from patients with TAO and controls. We identified overexpression of collagen XIII in active TAO-affected fat. We discuss how species and cell-type specific responses of collagen XIII to stressors may help explain the different phenotypes of TAO.

Cell density-dependent stimulation of PAI-1 and hyaluronan synthesis by TGF-β in orbital fibroblasts

During the course of Graves' orbitopathy (GO), orbital fibroblasts are exposed to factors that lead to proliferation and extracellular matrix (ECM) overproduction. Increased levels of tissue plasminogen activator inhibitor type 1 (PAI-1 (SERPINE1)) might promote the accumulation of ECM components. PAI-1 expression is regulated by cell density and various cytokines and growth factors including transforming growth factorβ(TGF-β). We examined the effects of increasing cell densities and TGF-β on orbital fibroblasts obtained from GO patients and controls. Responses were evaluated by the measurement of proliferation, PAI-1 expression, and ECM production. There was an inverse correlation between cell density and the per cell production of PAI-1. GO orbital, normal orbital, and dermal fibroblasts behaved similarly in this respect. Proliferation rate also declined with increasing cell densities. Hyaluronan (HA) production was constant throughout the cell densities tested in all cell lines. In both GO and normal orbital fibroblasts, but not in dermal fibroblasts, TGF-β stimulated PAI-1 production in a cell density-dependent manner, reaching up to a five-fold increase above baseline. This has been accompanied by increased HA secretion and pericellular HA levels at high cell densities. Increasing cell density is a negative regulator of proliferation and PAI-1 secretion both in normal and GO orbital fibroblasts; these negative regulatory effects are partially reversed in the presence of TGF-β. Cell density-dependent regulation of PAI-1 expression in the orbit, together with the local cytokine environment, may have a regulatory role in the turnover of the orbital ECM and may contribute to the expansion of orbital soft tissue in GO.