Forkhead Transcription Factor FOXO1 Is Regulated by Both a Stimulatory Thyrotropin Receptor Antibody and Insulin-Like Growth Factor-1 in Orbital Fibroblasts from Patients with Graves' Ophthalmopathy

Immune checkpoints: new insights into the pathogenesis of thyroid eye disease

Thyroid eye disease (TED) is a disfiguring autoimmune disease characterized by changes in the orbital tissues and is caused by abnormal thyroid function or thyroid-related antibodies. It is the ocular manifestation of Graves' disease. The expression of thyroid-stimulating hormone receptor (TSHR) and the insulin-like growth factor-1 receptor (IGF-1 R) on the cell membrane of orbital fibroblasts (OFs) is responsible for TED pathology. Excessive inflammation is caused when these receptors in the orbit are stimulated by autoantibodies. CD34+ fibrocytes, found in the peripheral blood and orbital tissues of patients with TED, express immune checkpoints (ICs) like MHC II, B7, and PD-L1, indicating their potential role in presenting antigens and regulating the immune response in TED pathogenesis. Immune checkpoint inhibitors (ICIs) have significantly transformed cancer treatment. However, it can also lead to the occurrence of TED in some instances, suggesting the abnormality of ICs in TED. This review will examine the overall pathogenic mechanism linked to the immune cells of TED and then discuss the latest research findings on the immunomodulatory role of ICs in the development and pathogenesis of TED. This will offer fresh perspectives on the study of pathogenesis and the identification of potential therapeutic targets.

Non-coding RNA-mediated epigenetic alterations in Grave's ophthalmopathy: A scoping systematic review

Background

It is becoming more and more apparent that Grave's Ophthalmopathy (GO) pathogenesis may be aided by epigenetic processes such as DNA methylation modifications, histone tail covalent modifications, and non-coding RNA (ncRNA)-based epigenetic processes. In the present study, we aimed to focus more on the miRNAs rather than lncRNAs due to lack of investigations on these non-coding RNAs and their role in GO's pathogenesis.

Methods

A six-stage methodology framework and the PRISMA recommendation were used to conduct this scoping review. A comprehensive search was conducted across seven databases to discover relevant papers published until February 2022. The data extraction separately, and quantitative and qualitative analyses were conducted.

Results

A total of 20 articles were found to meet inclusion criteria. According to the results, ncRNA were involved in the regulation of inflammation (miR-146a, LPAL2/miR-1287-5p axis, LINC01820:13/hsa miR-27b-3p axis, and ENST00000499452/hsa-miR-27a-3p axis), regulation of T cell functions (miR-146a/miR-183/miR-96), regulation of glycosaminoglycan aggregation and fibrosis (miR-146a/miR-21), glucocorticoid sensitivity (miR-224-5p), lipid accumulation and adipogenesis (miR-27a/miR-27b/miR-130a), oxidative stress and angiogenesis (miR-199a), and orbital fibroblast proliferation (miR-21/miR-146a/miR-155). Eleven miRNAs (miR-146a/miR-224-5p/miR-Let7d-5p/miR-96-5p/miR-301a-3p/miR-21-5p) were also indicated to have the capacity to be used as biomarkers.

Conclusions

Regardless of the fact that there is significant documentation of ncRNA-mediated epigenetic dysfunction in GO, additional study is needed to thoroughly comprehend the epigenetic connections concerned in disease pathogenesis, paving the way for novel diagnostic and prognostic tools for epigenetic therapies among the patients.

The Role of Adipsin, Complement Factor D, in the Pathogenesis of Graves' Orbitopathy

Purpose

Graves' orbitopathy (GO) is an orbital manifestation of autoimmune Graves' disease, and orbital fibroblast is considered a target cell, producing pro-inflammatory cytokines and/or differentiating into adipocytes. Adipose tissue has been focused on as an endocrine and inflammatory organ secreting adipokines. We investigated the pathogenic role of a specific adipokine, adipsin, known as complement factor D in Graves' orbital fibroblasts.

Methods

The messenger RNA (mRNA) expression of multiple adipokines was investigated in adipose tissues harvested from GO and healthy subjects. Adipsin protein production was analyzed in primary cultured orbital fibroblasts under insulin growth factor (IGF)-1, CD40 ligand (CD40L) stimulation, and adipogenesis. The effect of blocking adipsin with small interfering RNA (siRNA) on pro-inflammatory cytokine production and adipogenesis was evaluated using quantitative real-time PCR, Western blot, and ELISA. Adipogenic differentiation was identified using Oil Red O staining.

Results

Adipsin gene expression was significantly elevated in GO tissue and increased after the stimulation of IGF-1 and CD40L, as well as adipocyte differentiation in GO cells. Silencing of adipsin suppressed IGF-1-induced IL-6, IL-8, COX2, ICAM-1, CCL2 gene expression, and IL-6 protein secretion. Adipsin suppression also attenuated adipocyte differentiation. Exogenous treatment of recombinant adipsin resulted in the activation of the Akt, ERK, p-38, and JNK signaling pathways.

Conclusions

Adipsin, secreted by orbital fibroblasts, may play a distinct role in the pathogenesis of GO. Inhibition of adipsin ameliorated the production of pro-inflammatory cytokines and adipogenesis in orbital fibroblasts. Our study provides an in vitro basis suggesting adipsin as a potential therapeutic target for GO treatment.

A review of TSHR- and IGF-1R-related pathogenesis and treatment of Graves' orbitopathy

Graves' orbitopathy (GO) is an organ-specific autoimmune disease, but its pathogenesis remains unclear. There are few review articles on GO research from the perspective of target cells and target antigens. A systematic search of PubMed was performed, focusing mainly on studies published after 2015 that involve the role of target cells, orbital fibroblasts (OFs) and orbital adipocytes (OAs), target antigens, thyrotropin receptor (TSHR) and insulin-like growth factor-1 receptor (IGF-1R), and their corresponding antibodies, TSHR antibodies (TRAbs) and IGF-1R antibodies (IGF-1R Abs), in GO pathogenesis and the potentially effective therapies that target TSHR and IGF-1R. Based on the results, OFs may be derived from bone marrow-derived CD34+ fibrocytes. In addition to CD34+ OFs, CD34- OFs are important in the pathogenesis of GO and may be involved in hyaluronan formation. CD34- OFs expressing Slit2 suppress the phenotype of CD34+ OFs. β-arrestin 1 can be involved in TSHR/IGF-1R crosstalk as a scaffold. Research on TRAbs has gradually shifted to TSAbs, TBAbs and the titre of TRAbs. However, the existence and role of IGF-1R Abs are still unknown and deserve further study. Basic and clinical trials of TSHR-inhibiting therapies are increasing, and TSHR is an expected therapeutic target. Teprotumumab has become the latest second-line treatment for GO. This review aims to effectively describe the pathogenesis of GO from the perspective of target cells and target antigens and provide ideas for its fundamental treatment.

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.

Physiologic Mechanical Stress Directly Induces Bone Formation by Activating Glucose Transporter 1 (Glut 1) in Osteoblasts, Inducing Signaling via NAD+-Dependent Deacetylase (Sirtuin 1) and Runt-Related Transcription Factor 2 (Runx2)

Mechanical stress is an important factor affecting bone tissue homeostasis. We focused on the interactions among mechanical stress, glucose uptake via glucose transporter 1 (Glut1), and the cellular energy sensor sirtuin 1 (SIRT1) in osteoblast energy metabolism, since it has been recognized that SIRT1, an NAD+-dependent deacetylase, may function as a master regulator of the mechanical stress response as well as of cellular energy metabolism (glucose metabolism). In addition, it has already been demonstrated that SIRT1 regulates the activity of the osteogenic transcription factor runt-related transcription factor 2 (Runx2). The effects of mechanical loading on cellular activities and the expressions of Glut1, SIRT1, and Runx2 were evaluated in osteoblasts and chondrocytes in a 3D cell-collagen sponge construct. Compressive mechanical loading increased osteoblast activity. Mechanical loading also significantly increased the expression of Glut1, significantly decreased the expression of SIRT1, and significantly increased the expression of Runx2 in osteoblasts in comparison with non-loaded osteoblasts. Incubation with a Glut1 inhibitor blocked mechanical stress-induced changes in SIRT1 and Runx2 in osteoblasts. In contrast with osteoblasts, the expressions of Glut1, SIRT1, and Runx2 in chondrocytes were not affected by loading. Our present study indicated that mechanical stress induced the upregulation of Glut1 following the downregulation of SIRT1 and the upregulation of Runx2 in osteoblasts but not in chondrocytes. Since SIRT1 is known to negatively regulate Runx2 activity, a mechanical stress-induced downregulation of SIRT1 may lead to the upregulation of Runx2, resulting in osteoblast differentiation. Incubation with a Glut1 inhibitor the blocked mechanical stress-induced downregulation of SIRT1 following the upregulation of Runx2, suggesting that Glut1 is necessary to mediate the responses of SIRT1 and Runx2 to mechanical loading in osteoblasts.

Prostaglandin F2α and EP2 agonists, and a ROCK inhibitor modulate the formation of 3D organoids of Grave's orbitopathy related human orbital fibroblasts

3D organoid cultures were used to elucidate the periocular effects of several anti-glaucoma drugs including a prostaglandin F2α analogue (bimatoprost acid; BIM-A), EP2 agonist (omidenepag; OMD) or a Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor (ripasudil; Rip) on Grave's orbitopathy (GO) related orbital fatty tissue. 3D organoids were prepared from GO related human orbital fibroblasts (GHOFs) obtained from patients with GO. The effects of either 100 nM BIM-A, 100 nM OMD or 10 μM Rip on the 3D GHOFs organoids were examined with respect to organoid size, physical properties by a micro-squeezer, and the mRNA expression of extracellular matrix (ECM) proteins including collagen (COL) 1, COL 4, COL 6, and fibronectin (FN), ECM regulatory genes including lysyl oxidase (LOX), Connective Tissue Growth Factor (CTGF) and inflammatory cytokines including interleukin-1β (IL1β) and interleukin-6 (IL6). The size of the 3D GHOFs organoids decreased substantially in the presence of BIM-A, but also increased substantially in the presence of the others (OMD or Rip). The physical stiffness of the 3D GHOFs organoids was significantly decreased by Rip. BIM-A caused significantly the down-regulation of three ECM genes, Col 1, Col 6 and Fn, and two ECM regulatory genes and the up-regulation of IL6. In the presence of OMD, two ECM genes, Col 1 and Fn, and LOX were significantly down-regulated but IL1β and IL6 were significantly up-regulated. In the case of Rip, Col 1, FN and CTGF were significant down-regulated. Our present findings indicate that anti-glaucoma drugs modulate the structures and physical properties 3D GHOFs organoids in different manners by modifying the gene expressions of ECM, ECM regulatory factors and inflammatory cytokines. The results indicate that the benefits and demerits of anti-glaucoma medications need to be scrutinized carefully, in cases of patients with GO.

MicroRNA-146a downregulates the production of hyaluronic acid and collagen I in Graves' ophthalmopathy orbital fibroblasts

The present study aimed to investigate the effect of microRNA (miR)-146a on the secretion of hyaluronic acid (HA) and collagen I in Graves' ophthalmopathy (GO) orbital fibroblasts, and identify potential novel targets for the clinical treatment of GO. Orbital fibroblasts were extracted from orbital connective tissue, and primary cells were identified via immunohistochemistry. The levels of HA and collagen I in orbital fibroblasts of non-GO controls and patients with GO were examined via reverse transcription-quantitative PCR (RT-qPCR). miR-146a was overexpressed or inhibited in primary orbital fibroblasts via lentiviral infection, and the levels of HA and collagen I following miR-146a overexpression or inhibition were detected via ELISA and RT-qPCR. The results indicated that the mRNA expression of HA and collagen I was higher in orbital fibroblasts from patients with GO compared with the non-GO cohort. Overexpression of miR-146a reduced, and inhibition of miR-146a increased the production of HA and collagen I in GO orbital fibroblasts. In conclusion, it was demonstrated that miR-146a downregulated the secretion of HA and collagen I in GO orbital fibroblasts in vitro, which may affect glycosaminoglycan aggregation and collagen deposition in GO.

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.

MiR-142-3p functions as an oncogene in prostate cancer by targeting FOXO1

Prostate cancer (PCa) is a heterogeneous malignancy, and is a primary cause of cancer-related death in males. Forkhead box transcription factor O1 (FOXO1) exerts antitumor effects in various cancers, including PCa. However, the regulatory mechanism of miR-142-3p on FOXO1 expression in human PCa has not been characterized. In this study, we showed that FOXO1 protein levels were downregulated in PCa tissues and cells. Moreover, FOXO1 expression was a predictor of disease-free survival in patients with PCa and was a predictor of prognosis. Increased expression of FOXO1 suppressed cellular proliferation and induced cell cycle arrest at G0/G1 in vitro. However, FOXO1 mRNA and protein levels were inconsistent in human PCa tissues and cell lines. We showed that miR-142-3p levels were negatively correlated with FOXO1 protein levels in PCa. We also showed that miR-142-3p suppressed FOXO1 expression by directly targeting its 3′-untranslated region. Furthermore, suppression of miR-142-3p inhibited cell proliferation and induced cell cycle arrest, and these effects were blocked by FOXO1 knockdown. In vivo experiments showed that miR-142-3p knockout impaired tumor growth. Our results validate that FOXO1 acted as a tumor suppressor in PCa and demonstrated that FOXO1 was regulated by miR-142-3p, and miR-142-3p may be a potential target for treatment of PCa.

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

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

Predictive factors of prognosis after radiation and steroid pulse therapy in thyroid eye disease

To identify predictive factors of prognosis after radiotherapy with concurrent steroid pulse therapy for thyroid eye disease, retrospective analyses were performed among 77 patients. Clinical activity score and magnetic resonance imaging were used to evaluate degrees of orbital inflammation. As a pre-treatment work-up, the thyroid-stimulating antibody (TSAb) level was measured. During a median follow-up of 25.0 months, the 2-year cumulative relapse-free rate (CRFR) was 80.9%. In the univariate analysis, a worse 2-year CRFR was significantly associated with the presence of optic neuropathy (P = 0.001), a higher TSAb rate (P = 0.001), and lower standard deviation (SD) of signal intensity at the extraocular muscle in T2-weighted images (P = 0.006). In the multivariate analysis, TSAb rate and SD affected the CRFR independently. When TSAb activity of 2800% was set as a cut-off at 2 years after treatment, the predictive sensitivity and specificity of relapse were 81.2% and 90.6%, respectively. With regard to SD, the respective sensitivity and specificity values were 81.2% and 82.7% when 100 was set as a cut-off. In conclusion, high TSAb and low SD were significant risk factors for cumulative relapse in orbital radiotherapy. Cut-off values of 2800% for TSAb and 100 for SD may be suitable.