Alteration in Melanin Content in Retinal Pigment Epithelial Cells upon Hydroquinone Exposure

Abnormal pigmentation or depigmentation of the retinal pigment epithelium (RPE) is a precursor to neovascular age-related macular degeneration (nAMD). In this study, we evaluated the effects of hydroquinone (HQ), the most potent reductant in cigarette smoke, on the melanin production in RPE cells. Induced pluripotent stem cell (iPS)-derived RPE and adult retinal pigment epithelial (ARPE-19) cells were cultured with HQ. Real-time reverse transcription polymerase chain reaction revealed that the expression of melanin-related genes decreased due to the addition of HQ for 1 day. Enzyme-linked immunosorbent immunoassay showed that the concentration of melanin significantly decreased due to the addition of HQ for 24 h. A suspension of RPE cells with HQ for 24 h was prepared, and the absorbance was measured. The absorbance decreased particularly under blue light, suggesting that blue light may reach the choroid and cause choroidal inflammation. Additionally, melanin levels significantly decreased due to the addition of HQ for 1 week. After blue light irradiation on the RPE with HQ for 1 week, the vascular endothelial growth factor in the medium was significantly higher in the HQ group than in the control group. HQ-induced changes in melanin production may be responsible for the uneven pigmentation of the RPE, and these changes may cause nAMD.

Positive Association between Macular Pigment Optical Density and Glomerular Filtration Rate: A Cross-Sectional Study

Although decreased macular pigment density is associated with the development of age-related macular degeneration (AMD), exactly how this decrease may contribute to the development of AMD is still not fully understood. In this study, we investigated the relationship between macular pigment optical density (MPOD) and estimated glomerular filtration rate (eGFR). MPOD was measured using MPS II (Electron Technology, Cambridge, UK) in 137 participants who showed no clinical signs of AMD at 3 months after cataract surgery, and simple and multiple linear regression analyses were performed to determine the associations with age, sex, abdominal circumference, diabetes, hypertension, smoking, intraocular lens color, visual acuity before and after surgery, and eGFR. The participants were divided into two groups based on the median MPOD (0.58): the high-pigment and low-pigment groups. The mean value of eGFR in the high-pigment group was significantly higher than that in the low-pigment group (64.2 vs. 58.1, p = 0.02). The simple linear regression analysis revealed a significant positive association between MPOD and eGFR (β = 0.0034, 95% confidence interval [CI]: 0.0011-0.0056, p = 0.0038), and this association was independent of age, sex, abdominal circumference, diabetes, smoking, hypertension, best-corrected visual acuity (BCVA) before surgery, BCVA after surgery, and intraocular lens color (β = 0.0033, 95% CI: 0.00090-0.0058, p = 0.0076). These results show a strong association of renal dysfunction with the decrease in MPOD.

Development of an Eccentric Macular Hole Followed by Reopening of the Original Macular Hole as a Long-term Sequelae of Internal Limiting Membrane Peeling and Focal Laser Photocoagulation: A Case Report

A macular hole (MH) is a widely known disease among ophthalmologists. Vitrectomy with internal limiting membrane (ILM) peeling is a standard technique for full-thickness MHs. However, the recurrence of MHs is sometimes seen. In addition, an eccentric MH is known to rarely occur after vitrectomy. An eccentric MH has been considered to require no therapeutic intervention because of its lack of increase in size. This study reports a case of two MHs (a recurrent MH and an enlarged eccentric MH) developed after laser photocoagulation around the injured retina caused by ILM peeling at the initial surgery. A 56-year-old woman presented with an idiopathic MH in her left eye and best-corrected visual acuity (BCVA) was decreased to 20/80. She underwent phacoemulsification and vitrectomy combined with posterior hyaloid removal, ILM peeling, and 20% sulfur hexafluoride gas tamponade.  During the ILM peeling, we performed laser photocoagulation around the injured retina within the arcade. The MH was successfully closed and her BCVA was improved to 20/20 one month after surgery. Eight months after surgery, an eccentric MH occurred next to the photocoagulation spots. However, her BCVA remained 20/20; thus, we just followed up on her eye. Six years after surgery, her BCVA was decreased to 20/200. The eccentric MH increased in size and the original MH re-opened. The second vitrectomy was performed, but ILM had been already peeled within the arcade during the previous surgery and a usable sufficient size of ILM which could be auto-transplanted to the holes was not obtained. Thus, free flaps of the posterior lens capsule were harvested and placed within each hole. Two holes were successfully closed and her BCVA improved to 10/20 at three months after the surgery. Laser photocoagulation around the injured retina derived from ILM peeling may be a risk for recurrent MHs. .

Acute retinal necrosis in a patient on immunosuppressive treatment for COVID-19 pneumonia: a case report

BACKGROUND

Patients with coronavirus disease 2019 (COVID-19) occasionally develop ocular complications. We report a case of acute retinal necrosis (ARN) caused by Epstein-Barr Virus (EBV) that developed in a patient who had severe acute respiratory syndrome due to SARS-CoV-2 infection.

CASE PRESENTATION

A 68-year-old woman complained of floaters and blurred vision in her right eye as she was receiving systemic prednisolone for COVID-19 pneumonia under isolation in our hospital. The patient visited an ophthalmologist following her discharge from the hospital and after the 2 weeks of isolation had ended. At the initial examination, her best-corrected visual acuity (BCVA) was 20/100 in the right eye, and the eye showed moderate anterior segment inflammation and vitreous opacities. Treatment was initiated with topical 0.1% betamethasone and 1.5% levofloxacin. After 1 month, the inflammation in the right eye decreased and her BCVA improved to 20/40. However, on day 48 from her initial visit, the inflammation in her right eye worsened and her BCVA decreased to 20/2000 by day 80. Pars plana vitrectomy with silicone oil tamponade was performed to remove the vitreous opacities, and expanded white exudates peripherally and retinal vessels with white sheathing suggestive of acute retinal necrosis (ARN) were seen intraoperatively. Analysis of the vitreous sample revealed EBV positivity on polymerase chain reaction. The patient was diagnosed with EBV-associated ARN and treated with systemic steroids and valaciclovir. The ocular inflammation gradually decreased, and she was discharged from the hospital. However, a week later, the inflammation in the right eye markedly worsened. Despite another course of steroids, the inflammation worsened, resulting in total retinal detachment and absolute glaucoma. Because of the severe pain, the right eye was enucleated.

CONCLUSIONS

Clinicians should be aware that COVID-19 and immunosuppressive treatment can reactivate EBV in the eye.

Visual prognosis of submacular hemorrhage secondary to age-related macular degeneration: A retrospective multicenter survey

Purpose

To investigate the clinical features, treatment options, and visual outcomes of submacular hemorrhage (SMH) secondary to neovascular age-related macular degeneration (nAMD).

Design

A retrospective, observational case series.

Methods

Setting: Multicenter institutional setting. Patient Population: A total of 127 patients (127 eyes; 88 men, 39 women; (mean age, 74.2 years)) diagnosed with AMD-associated SMHs exceeding 2 disc diameters involving the fovea. Observation: The AMD types, previous treatments, treatment options, anatomic findings, and best-corrected visual acuity (BCVA) were assessed. Main Outcome Measures: Clinical features, treatment options, and visual outcomes of SMHs secondary to nAMD.

Results

Thirty-two eyes had typical AMD, 94 eyes polypoidal choroidal vasculopathy (PCV), and one eye retinal angiomatous proliferation. Eighty-five eyes were treatment-naïve; 42 eyes were treated previously: anti-vascular endothelial growth factor (VEGF) therapy (n = 26), photodynamic therapy (n = 3), and combined therapy (n = 13). Treatment of SMHs included vitrectomy (36 eyes), pneumatic displacement (49 eyes), and anti-VEGF monotherapy (42 eyes). The final BCVA improved significantly in treatment-naïve cases from 0.86 to 0.62 logarithm of the minimal angle of resolution (logMAR) unit (Snellen equivalent from 20/145 to 20/83) and from 0.80 to 0.56 (Snellen equivalent from 20/126 to 20/73) in PCV cases. Meanwhile, the BCVA logMAR values improved from 1.15 to 0.75 (Snellen equivalent from 20/283 to 20/112) and from 0.87 to 0.63 (Snellen equivalent from 20/148 to 20/85) in eyes that underwent vitrectomy or pneumatic displacement, respectively. In eyes with BCVAs between 20/133 to 20/40 at SMH onset, the final VA in the pneumatic displacement group was better than in the anti-VEGF monotherapy group. One eye had a retinal detachment and 1 eye had a macular hole in the vitrectomy group, and 5 eyes had a vitreous hemorrhage in the pneumatic displacement group.

Conclusions

The recommended treatment for SMHs secondary to nAMD exceeding 2 disc area and with BCVA below 20/40 is vitrectomy or pneumatic displacement for visual improvement.

Treatment of diabetic macular edema in real-world clinical practice: the effect of aging

Aims/Introduction

In older patients, the management of diabetic macular edema (DME) can be complicated by comorbidities, geriatric syndrome, and socioeconomic status. This study aims to evaluate the effects of aging on the management of DME.

Materials and Methods

This is a real‐world clinical study including 1,552 patients with treatment‐naïve center‐involved DME. The patients were categorized into 4 categories by age at baseline (C1, <55; C2, 55–64; C3, 65–74; and C4, ≥75 years). The outcomes were the change in logarithm of the minimum angle of resolution best‐corrected visual acuity (logMAR BCVA) and central retinal thickness (CRT), and the number of treatments from baseline to 2 years.

Results

From baseline to 2 years, the mean changes in logMAR BCVA from baseline to 2 years were −0.01 in C1, −0.06 in C2, −0.07 in C3, and 0.01 in C4 (P = 0.016), and the mean changes in CRT were −136.2 μm in C1, −108.8 μm in C2, −100.6 μm in C3, and −89.5 μm in C4 (P = 0.008). Treatments applied in the 2 year period exhibited decreasing trends with increasing age category on the number of intravitreal injections of anti‐VEGF agents (P = 0.06), selecting local corticosteroid injection (P = 0.031), vitrectomy (P < 0.001), and laser photocoagulation outside the great vascular arcade (P < 0.001).

Conclusions

Compared with younger patients with DME, patients with DME aged ≥75 years showed less frequent treatment, a lower BCVA gain, and a smaller CRT decrease. The management and visual outcome in older patients with DME would be unsatisfactory in real‐world clinical practice.

Clinical implications of pachyvessels in polypoidal choroidal vasculopathy

Background

Polypoidal choroidal vasculopathy (PCV) is one of the disorders within the pachychoroid spectrum diseases. The presence of pachyvessels is one of the characteristics of pachychoroid disorders. However, the relationship between the presence of pachyvessels and the clinical characteristics of PCV eyes has not been determined. The purpose of this study was to determine the relationship between the presence of choroidal pachyvessels and the clinical characteristics of eyes with PCV.

Methods

The medical records of patients who were diagnosed with PCV and were treatment-naïve were reviewed. Fluorescein and indocyanine green angiography, fundus photography, spectral domain optical coherence tomography (SD-OCT), and enhanced depth imaging OCT (EDI-OCT) were used to obtain images of the choroid. The presence of pathologically dilated outer choroidal vessels, pachyvessels, was determined by ICGA images. These pachyvessels were confirmed to correspond with the large choroidal vessels in the EDI OCT images. The PCV eyes were divided into two groups based on the presence or absence of pachyvessels and clinical features and subfoveal choroidal thickness (SFCT) were evaluated between the two groups.

Results

Eighty-six eyes of 84 patients with PCV were evaluated. Pachyvessels were detected in 48 eyes (55.8%). The mean SFCT was 203.9 ± 83.9 μm in all 86 eyes, and it was significantly thinner in eyes with pachyvessels (+) than without pachyvessels (−) (183.2 ± 58.4 μm vs 230.2 ± 103.1 μm; P = 0.01). The differences in the incidence of subretinal fluid, pigment epithelial detachments, and hemorrhages between the two groups were not significant. However, the PCV eyes in pachyvessels (+) group with hemorrhage had the thinnest choroid (P = 0.047). The choroidal features of the fellow eyes were similar to those of the PCV affected eyes, that is, the fellow eyes in pachyvessels (+) group had pachyvessels and the fellow eyes in pachyvessels (−) group did not have pachyvessels.

Conclusions

Pachyvessels were presented 55.8% in eyes with PCV, and these eyes had the thin SFCT. The presence of pachyvessels and attenuation of the inner choroid were probably due to the pathological changes in the eyes with PCV.

Real-world management of treatment-naïve diabetic macular oedema: 2-year visual outcome focusing on the starting year of intervention from STREAT-DMO study

Background/aims

To investigate the yearly change of real-world outcomes for best corrected visual acuity (BCVA) after 2-year clinical intervention for treatment-naïve diabetic macular oedema (DMO).

Methods

Retrospective analysis of aggregated, longitudinal medical records obtained from 27 retina specialised institutions in Japan from Survey of Treatment for DMO database. A total of 2049 treatment-naïve centre involving DMO eyes of which the initial intervention started between 2010 and 2015, and had been followed for 2 years, were eligible. As interventions, antivascular endothelial growth factor (VEGF) agents, local corticosteroids, macular photocoagulation and vitrectomy were defined. In each eye, baseline and final BCVA, the number of each intervention for 2 years was extracted. Each eye was classified by starting year of interventional treatment.

Results

Although baseline BCVA did not change by year, 2-year improvement of BCVA had been increased, and reached to +6.5 letters in the latest term. There is little difference among starting year about proportions of eyes which BCVA gained >15 letters, in contrast to those which lost >15 letters were decreased by year. The proportion of eyes receiving anti-VEGF therapy was dramatically increased, while those receiving the other therapies were gradually decreased. The proportion of eyes which maintained socially good vision of BCVA>20/40 has been increased and reached to 59.0% in the latest term.

Conclusion

For recent years, treatment patterns for DMO have been gradually but certainly changed; as a result, better visual gain, suppression of worsened eyes and better final BCVA have been obtained. Anti-VEGF therapy has become the first-line therapy and its injection frequency has been increasing.

Sustained delivery of acriflavine from the suprachoroidal space provides long term suppression of choroidal neovascularization

Hypoxia-inducible factor-1 (HIF-1) has been implicated in the pathogenesis of choroidal neovascularization (NV) and is an appealing target because it increases multiple pro-angiogenic proteins and their receptors. Acriflavine (ACF) binds HIF-1α and HIF-2α preventing binding to HIF-1β and inhibiting transcriptional activity of HIF-1 and HIF-2. Delivery of ACF to the eye by multiple routes strongly, but transiently, suppresses choroidal NV. We overcame design challenges and loaded highly water soluble ACF into poly(lactic-co-glycolic acid) (PLGA) microparticles (PLGA-ACF MPs) that release ACF in vitro for up to 60 days. Intravitreous injection of PLGA-ACF MPs in mice suppressed choroidal NV for at least 9 weeks and suprachoroidal injection of PLGA-ACF in rats suppressed choroidal NV for at least 18 weeks. Intravitreous, but not suprachoroidal injection, of PLGA-ACF MPs containing 38 μg of ACF in rabbits resulted in modest reduction of full-field electroretinogram (ERG) function. Over the span of 28 days after suprachoroidal injection of PLGA-ACF MP, rabbits had normal appearing retinas on fundus photographs, normal electroretinogram scotopic a- and b-wave amplitudes, no increase in intraocular pressure, and normal retinal histology. The active component of ACF, trypaflavine, had steady-state levels in the low nM range in RPE/choroid > retina for at least 16 weeks with a gradient from the side of the eye where the injection was done to the opposite side. These data suggest that suprachoroidal injection of PLGA-ACF MPs has the potential to provide a durable new treatment for retinal and choroidal vascular diseases.

Real-world management of treatment-naïve diabetic macular oedema in Japan: two-year visual outcomes with and without anti-VEGF therapy in the STREAT-DME study

Background/Aims

To investigate real-world outcomes for best-corrected visual acuity (BCVA) after 2-year clinical intervention for treatment-naïve, centr-involving diabetic macular oedema (DME).

Methods

Retrospective analysis of longitudinal medical records obtained from 27 institutions specialising in retinal diseases in Japan. A total of 2049 eyes with treatment-naïve DME commencing intervention between 2010 and 2015 who were followed for 2 years were eligible. Interventions for DME included anti-vascular endothelial growth factor (VEGF) therapy, local corticosteroid therapy, macular photocoagulation and vitrectomy. Baseline and final BCVA (logMAR) were assessed. Eyes were classified by the treatment pattern, depending on whether anti-VEGF therapy was used, into an anti-VEGF monotherapy group (group A), a combination therapy group (group B) and a group without anti-VEGF therapy (group C).

Results

The mean 2-year improvement of BCVA was −0.04±0.40 and final BCVA of >20/40 was obtained in 46.3% of eyes. Based on the treatment pattern, there were 427 eyes (20.9%) in group A, 807 eyes (39.4%) in group B and 815 eyes (39.8%) in group C. Mean improvement of BCVA was −0.09±0.39, –0.02±0.40 and −0.05±0.39, and the percentage of eyes with final BCVA of >20/40 was 49.4%, 38.9%, and 52.0%, respectively.

Conclusion

Following 2-year real-world management of treatment-naïve DME in Japan, BCVA improved by 2 letters. Eyes treated by anti-VEGF monotherapy showed a better visual prognosis than eyes receiving combination therapy. Despite treatment for DME being selected by specialists in consideration of medical and social factors, a satisfactory visual prognosis was not obtained, but final BCVA remained >20/40 in half of all eyes.

Effects of concentration of amyloid β (Aβ) on viability of cultured retinal pigment epithelial cells

Background

Amyloid beta (Aβ) is a constituent of drusen that is a common sign of age-related macular degeneration (AMD). The purpose of this study was to investigate the effect of Aβ on human retinal pigment epithelial (RPE) cells in culture.

Methods

Cells from a human RPE cell line (ARPE-19) were exposed to 0 to 25 μM of Aβ 1–40 for 48 h, and the number of living cells was determined by WST-8 cleavage. Replicative DNA synthesis was measured by the incorporation of 5′-bromo-2′-deoxyuridine. The cell death pathway was investigated by the WST-8 cleavage assay after the addition of caspase-9 inhibitor, an anti-apoptotic factor. Real-time qRT-PCR was performed using Aβ-exposed cellular RNA to determine the level of vascular endothelial growth factor (VEGF)-A and pigment epithelium derived factor (PEDF). To determine the effect of receptor-for-advanced glycation end products (RAGE), the siRNA for RAGE was inserted into ARPE-19 treated with Aβ, and the levels of expression of VEGF-A and PEDF were determined.

Results

The number of living ARPE-19 cells was increased by exposure to 5 μM Aβ but was decreased by exposure to 25 μM of Aβ. Replicative DNA synthesis by ARPE-19 cells exposed to 25 μM of Aβ was significantly decreased indicating that 25 μM of Aβ inhibited cell proliferation. Real-time RT-PCR showed that the level of the mRNA of PEDF was increased by exposure to 5 μM Aβ, and the levels of the mRNAs of PEDF and VEGF-A were also increased by exposure to 25 μM Aβ. The addition of an inhibitor of caspase-9 blocked the decrease the number of ARPE-19 cells exposed to 25 μM Aβ. Exposure to si-RAGE attenuated the increase of VEGF-A and PEDF mRNA expression in ARPE-19 exposed to Aβ.

Conclusions

Exposure of ARPE-19 cells to low concentrations of Aβ increases the level of PEDF which then inhibits the apoptosis of ARPE-19 cells leading to RPE cell proliferation. Exposure to high concentrations of Aβ induces RPE cell death and enhances the expression of the mRNA of VEGF-A in RPE cells. The Aβ-RAGE pathway may lead to the expression VEGF-A and PEDF in RPE cells. These results suggest that Aβ is strongly related to the pathogenesis of choroidal neovascularization.

Statins decrease vascular epithelial growth factor expression via down-regulation of receptor for advanced glycation end-products

Aims

Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, possess pleiotropic effects that have been extended to modulation of various cellular behaviors. This study aimed to examine whether statins modulate vascular endothelial growth factor A (VEGF-A) expression in human retinal pigment epithelium (RPE) cells.

Main methods

Human RPE cells (h1RPE7), damaged by hydroquinone (HQ) + advanced glycation endproducts (AGE) in an in vitro AMD model, were treated with atorvastatin or lovastatin for 24 h. The expression of VEGF-A and receptor for AGE (RAGE) was evaluated by real-time RT-PCR. VEGF-A secretion was measured by ELISA. To investigate the impact of RAGE on VEGF-A expression, small interfering RNA (siRNA) for RAGE (siRAGE) was introduced into h1RPE7 cells and VEGF-A expression was measured by real-time RT-PCR. Deletions of VEGF-A and RAGE promoters were performed and transcriptional activities were measured after the addition of statins to HQ + AGE-damaged RPE cells.

Key findings

The mRNA levels of VEGF-A and RAGE and the levels of VEGF-A in the culture medium were increased by HQ + AGE. Both atorvastatin and lovastatin attenuated HQ + AGE-induced VEGF-A and RAGE expression. These statins also decreased VEGF-A levels in the culture medium. RNA interference of RAGE attenuated the up-regulation of VEGF-A in the HQ + AGE treated cells. The deletion analysis demonstrated that these statins attenuated RAGE promoter activation in HQ + AGE-damaged RPE cells.

Significance

Statins attenuated HQ + AGE-induced VEGF expression by decreasing RAGE expression. As VEGF is an important factor in developing wet AMD, statins could decrease the risk of wet-type AMD and be used as preventive medicines.

Human retinal pigment epithelial cell proliferation by the combined stimulation of hydroquinone and advanced glycation end-products via up-regulation of VEGF gene

Although recent research showed that advanced glycation endproduct (AGE) and hydroquinone (HQ) are related to the pathogenesis of age-related macular degeneration (AMD), the mechanism how AGE and HQ induce or accelerate AMD remains elusive. In the present study, we examined the effects of AGE and HQ on changes of human retinal pigment epithelial (RPE) cell numbers and found that the viable cell numbers were markedly reduced by HQ by apoptosis and that AGE prevented the decreases of HQ-treated cell numbers by increased replicative DNA synthesis of RPE cells without changing apoptosis. Real-time RT-PCR revealed that vascular endothelial growth factor (VEGF)-A mRNA was increased by HQ treatment and the addition of HQ+AGE resulted in a further increment. The increase of VEGF secretion was confirmed by ELISA, and inhibition of VEGF signaling by chemical inhibitors and small interfering RNA decreased the HQ+AGE-induced increases in RPE cell numbers. The deletion analysis demonstrated that -102 to -43 region was essential for the VEGF-A promoter activation. Site-directed mutaions of specificity protein 1 (SP1) binding sequences in the VEGF-A promoter and RNA interference of SP1 revealed that SP1 is an essential transcription factor for VEGF-A expression. These results indicate that HQ induces RPE cell apoptosis, leading to dry AMD, and suggest that AGE stimulation in addition to HQ enhances VEGF-A transcription via the AGE-receptor for AGE pathway in HQ-damaged cells. As a result, the secreted VEGF acts as an autocrine/paracrine growth factor for RPE and/or adjacent vascular cells, causing wet AMD.

The effect of blue-blocking intraocular lenses on circadian biological rhythm: protocol for a randomised controlled trial (CLOCK-IOL colour study)

INTRODUCTION

Blue light information plays an important role in synchronising internal biological rhythm within the external environment. Circadian misalignment is associated with the increased risk of sleep disturbance, obesity, diabetes mellitus, depression, ischaemic heart disease, stroke and cancer. Meanwhile, blue light causes photochemical damage to the retina, and may be associated with age-related macular degeneration (AMD). At present, clear intraocular lenses (IOLs) and blue-blocking IOLs are both widely used for cataract surgery; there is currently a lack of randomised controlled trials to determine whether clear or blue-blocking IOLs should be used.

METHODS AND ANALYSIS

This randomised controlled trial will recruit 1000 cataract patients and randomly allocate them to receive clear IOLs or blue-blocking IOLs in a ratio of 1:1. The primary outcomes are mortality and the incidence of cardiovascular disease, cancer and AMD. Secondary outcomes are fasting plasma glucose, triglycerides, cholesterol, glycated haemoglobin, sleep quality, daytime sleepiness depressive symptoms, light sensitivity, the circadian rhythm of physical activity, wrist skin temperature and urinary melatonin metabolite. Primary outcomes will be followed until 20 years after surgery, and secondary outcomes will be assessed at baseline and 1 year after surgery.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Institutional Review Board of Nara Medical University (No. 13-032). The findings of this study will be communicated to healthcare professionals, participants and the public through peer-reviewed publications, scientific conferences and the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) home page.

TRIAL REGISTRATION NUMBER

UMIN000014680.

Synergistic activations of REG I α and REG I β promoters by IL-6 and Glucocorticoids through JAK/STAT pathway in human pancreatic β cells

Reg (Regenerating gene) gene was originally isolated from rat regenerating islets and its encoding protein was revealed as an autocrine/paracrine growth factor for β cells. Rat Reg gene is activated in inflammatory conditions for β cell regeneration. In human, although five functional REG family genes (REG Iα, REG Iβ, REG III, HIP/PAP, and REG IV) were isolated, their expressions in β cells under inflammatory conditions remained unclear. In this study, we found that combined addition of IL-6 and dexamethasone (Dx) induced REG Iα and REG Iβ expression in human 1.1B4 β cells. Promoter assay revealed that a signal transducer and activator of transcription- (STAT-) binding site in each promoter of REG Iα (TGCCGGGAA) and REG Iβ (TGCCAGGAA) was essential for the IL-6+Dx-induced promoter activation. A Janus kinase 2 (JAK2) inhibitor significantly inhibited the IL-6+Dx-induced REG Iα and REG Iβ transcription. Electrophoretic mobility shift assay and chromatin immunoprecipitation revealed that IL-6+Dx stimulation increased STAT3 binding to the REG Iα promoter. Furthermore, small interfering RNA-mediated targeting of STAT3 blocked the IL-6+Dx-induced expression of REG Iα and REG Iβ. These results indicate that the expression of REG Iα and REG Iβ should be upregulated in human β cells under inflammatory conditions through the JAK/STAT pathway.