Erythropoietin in ophthalmology: A literature review

Methanol Induced Optic Neuropathy: Molecular Mysteries, Public Health Perspective, Clinical Insights and Treatment Strategies

Methanol-induced optic neuropathy (MION) represents a critical public health issue, particularly prevalent in lower socioeconomic populations and regions with restricted alcohol access. MION, characterized by irreversible visual impairment, arises from the toxic metabolization of methanol into formaldehyde and formic acid, leading to mitochondrial oxidative phosphorylation inhibition, oxidative stress, and subsequent neurotoxicity. The pathogenesis involves axonal and glial cell degeneration within the optic nerve and potential retinal damage. Despite advancements in therapeutic interventions, a significant proportion of affected individuals endure persistent visual sequelae. The study comprehensively investigates the pathophysiology of MION, encompassing the absorption and metabolism of methanol, subsequent systemic effects, and ocular impacts. Histopathological changes, including alterations in retinal layers and proteins, Müller cell dysfunction, and visual symptoms, are meticulously examined to provide insights into the disease mechanism. Furthermore, preventive measures and public health perspectives are discussed to highlight the importance of awareness and intervention strategies. Therapeutic approaches, such as decontamination procedures, ethanol and fomepizole administration, hemodialysis, intravenous fluids, electrolyte balance management, nutritional therapy, corticosteroid therapy, and erythropoietin (EPO) treatment, are evaluated for their efficacy in managing MION. This comprehensive review underscores the need for increased awareness, improved diagnostic strategies, and more effective treatments to mitigate the impact of MION on global health.

Visual outcome of methanol toxic optic neuropathy after erythropoietin treatment in Riyadh, Saudi Arabia

PURPOSE

The purpose of this study is to evaluate the visual response of methanol-induced optic neuropathy to management with erythropoietin (EPO) along with conventional therapy.

METHODS

This retrospective case series examines the ophthalmological data of patients diagnosed with methanol-induced optic neuropathy between 2020 and 2021 at two centers, Riyadh, Saudi Arabia. Patients' characteristics and the results of initial and final ophthalmological examinations were documented and compared between patients who received EPO in addition to conventional management and those who received only conventional management.

RESULTS

A total of nine cases were reviewed, of which eight (88.9%) were males and one was female (11.1%). The mean age was 37.7 years. At presentation, funduscopic examination revealed optic disc edema in four eyes (two patients), and 14 eyes had normal appearance (seven patients). Among the nine patients who received conventional management, 5 (55.6%) additionally received intravenous EPO during the treatment course. There was no clinically or statistically significant difference in terms of visual outcome between the two groups. The mean visual acuity at the final presentation was 1.32 ± 0.79 logarithm of the minimum angle of resolution (LogMAR) in the EPO group and 1.36 ± 0.85 LogMAR in the non-EPO group. Optical coherence tomography indicated that the EPO group had an average retinal nerve fiber layer thickness of 48.13μm (±6.2), at the final assessment.

CONCLUSION

Managing the visual impairments in individuals with methanol-induced optic neuropathy using intravenous EPO resulted in similar final visual outcomes compared to conventional management.

Identification of novel biomarkers for retinopathy of prematurity in preterm infants by use of innovative technologies and artificial intelligence

Retinopathy of prematurity (ROP) is a leading cause of preventable vision loss in preterm infants. While appropriate screening is crucial for early identification and treatment of ROP, current screening guidelines remain limited by inter-examiner variability in screening modalities, absence of local protocol for ROP screening in some settings, a paucity of resources and an increased survival of younger and smaller infants. This review summarizes the advancements and challenges of current innovative technologies, artificial intelligence (AI), and predictive biomarkers for the diagnosis and management of ROP. We provide a contemporary overview of AI-based models for detection of ROP, its severity, progression, and response to treatment. To address the transition from experimental settings to real-world clinical practice, challenges to the clinical implementation of AI for ROP are reviewed and potential solutions are proposed. The use of optical coherence tomography (OCT) and OCT angiography (OCTA) technology is also explored, providing evaluation of subclinical ROP characteristics that are often imperceptible on fundus examination. Furthermore, we explore several potential biomarkers to reduce the need for invasive procedures, to enhance diagnostic accuracy and treatment efficacy. Finally, we emphasize the need of a symbiotic integration of biologic and imaging biomarkers and AI in ROP screening, where the robustness of biomarkers in early disease detection is complemented by the predictive precision of AI algorithms.

Delayed reversal of methanol-induced blindness in an adult by a combination of erythropoietin and a high dose of methylprednisolone: a case report

BACKGROUND

The clinical manifestation following methanol toxicity accounts for a life-threatening problem that contributes to metabolic disorders, neurological complications, blindness, and even death. There is no completely effective treatment to retain the patient's vision. Herein, we apply a new therapeutic strategy for the recovery of bilateral blindness in a patient who had ingested methanol.

CASE PRESENTATION

A 27-year-old Iranian man with complete bilateral blindness was referred 3 days after accidental ingestion of methanol to the poisoning center at Jalil Hospital, Yasuj, Iran, in 2022. After taking his medical history, performing neurologic and ophthalmologic examinations, and routine laboratory tests, ordinary management was undertaken and counterpoisons were given for 4-5 days; however, the blindness did not reverse. Following the 4-5 days of unsuccessful standard management, he was given ten doses of subcutaneous erythropoietin 10,000 IU/12 hours twice daily, folinic acid 50 mg/12 hours, and methylprednisolone 250 mg/6 hours for 5 days. After five days, vision of both eyes recovered, reaching 1/10 in the left and 7/10 in the right eye. He remained under daily supervision until his release from the hospital, and he was discharged from the hospital 15 days post admission. In outpatient follow-up, his visual acuity was improved without having any side effects at 2 weeks after discharge.

CONCLUSION

A combination of erythropoietin and a high dose of methylprednisolone were useful for relieving the critical optic neuropathy and improved the optical neurological disorder following methanol toxicity.

Intravenous plus intravitreal erythropoietin for management of methanol toxicity optic neuropathy: A case report and brief review

Methanol can inhibit cellular aerobic respiration pathway and causes cell hypoxia specially in optic neurons. Despite using many drugs, methanol-induced optic neuropathy (MION) still has a poor prognosis. Here we present a case of MION which is managed by a combination of intravenous and intravitreal erythropoietin in addition to corticosteroids.

Porcine Corneas Incubated at Low Humidity Present Characteristic Features Found in Dry Eye Disease

Dry eye is a multifactorial disease that affects the ocular surface and tear fluid. Current treatment options include lubricant eye drop application several times a day. However, these eye drops often cause local side effects like ocular allergies or blurred vision after the application. To test new treatment options, a robust dry eye model is needed. Here, a porcine ex vivo model was established by means of incubation of porcine corneas in low humidity (LH) and characterized by histological damage evaluation, epithelial thickness and by relevant dry eye markers, such as interleukin 1 beta (IL-1β), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), occludin and galectin-3. In the dry eye model proposed, an increased secretion of IL-1β was observed, as well as an upregulation of NF-κB, occludin and galectin-3 mRNA expression. Moreover, the model presented a higher rate of cell death in comparison to the controls. These effects could be reversed with successful treatment of dexamethasone (dexa) and partially reversed with hyaluronic acid (HA) containing eye drops. Furthermore, medium-molecular-weight HA stimulated an increase in IL-1β in the model proposed. In conclusion, this dry eye model mimics the in vivo condition and hence allows for animal-free testing of novel dry eye treatments.

Chitosan and Hyaluronic Acid Nanoparticles as Vehicles of Epoetin Beta for Subconjunctival Ocular Delivery

Neuroprotection in glaucoma using epoetin beta (EPOβ) has yielded promising results. Our team has developed chitosan-hyaluronic acid nanoparticles (CS/HA) designed to carry EPOβ into the ocular globe, improving the drug’s mucoadhesion and retention time on the ocular surface to increase its bioavailability. In the present in vivo study, we explored the possibility of delivering EPOβ to the eye through subconjunctival administration of chitosan-hyaluronic acid-EPOβ (CS/HA-EPOβ) nanoparticles. Healthy Wistar Hannover rats (n = 21) were split into 7 groups and underwent complete ophthalmological examinations, including electroretinography and microhematocrit evaluations before and after the subconjunctival administrations. CS/HA-EPOβ nanoparticles were administered to the right eye (OD), and the contralateral eye (OS) served as control. At selected timepoints, animals from each group (n = 3) were euthanized, and both eyes were enucleated for histological evaluation (immunofluorescence and HE). No adverse ocular signs, no changes in the microhematocrits (≈45%), and no deviations in the electroretinographies in both photopic and scotopic exams were observed after the administrations (p < 0.05). Intraocular pressure remained in the physiological range during the assays (11–22 mmHg). EPOβ was detected in the retina by immunofluorescence 12 h after the subconjunctival administration and remained detectable until day 21. We concluded that CS/HA nanoparticles could efficiently deliver EPOβ into the retina, and this alternative was considered biologically safe. This nanoformulation could be a promising tool for treating retinopathies, namely optic nerve degeneration associated with glaucoma.

Erythropoietin in Lupus: Unanticipated Immune Modulating Effects of a Kidney Hormone

Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease with variable clinical presentation, typically characterized by a relapsing-remitting course. SLE has a multifactorial pathogenesis including genetic, environmental, and hormonal factors that lead to loss of tolerance against self-antigens and autoantibody production. Mortality in SLE patients remains significantly higher than in the general population, in part because of the limited efficacy of available treatments and the associated toxicities. Therefore, novel targeted therapies are urgently needed to improve the outcomes of affected individuals. Erythropoietin (EPO), a kidney-produced hormone that promotes red blood cell production in response to hypoxia, has lately been shown to also possess non-erythropoietic properties, including immunomodulatory effects. In various models of autoimmune diseases, EPO limits cell apoptosis and favors cell clearance, while reducing proinflammatory cytokines and promoting the induction of regulatory T cells. Notably, EPO has been shown to reduce autoimmune response and decrease disease severity in mouse models of SLE. Herein, we review EPO's non-erythropoietic effects, with a special focus on immune modulating effects in SLE and its potential clinical utility.

Intravitreal Injection Of The Granulocyte-Colony Stimulating Factor For The Treatment Of Non-Arteritic Anterior Ischemic Optic Neuropathy: A Pilot Study

Purpose To investigate the efficacy of intravitreal injection of granulocyte colony-stimulating factor (G-CSF) for the treatment of non-arteritic anterior ischemic optic neuropathy (NAION).Methods: Patients with acute NAION were enrolled in this prospective interventional case series. They received an intravitreal injection of 60 micrograms in 0.1 ml of G-CSF within 2 weeks of the onset of the disease. Visual acuity, visual field, intraocular pressure (IOP), corneal endothelial cell density, and peripapillary retinal nerve fiber layer (RNFL) thickness were recorded before injections and 1 week, 1 month, 3 months, 6 months, and one year after the injections. Full-field electroretinography (ERG) was obtained at the baseline, 1 month, and 12 months post- injections.Results: Fourteen eyes of 14 patients entered the study. Best-corrected visual acuity (BCVA) significantly improved in the first month following injections (p = .007), decreased subsequently, and the final BCVA showed no significant improvement (p = .278) compared to the baseline measurements. A significant decrease in RNFL thickness was observed in all quadrants compared to the baseline measurements. Also, no improvement in the visual field parameters was observed. From the toxicity aspect, no significant changes in the corneal endothelial cell density, IOP, and ERG recordings were observed.Conclusion: Intravitreal injection of G-CSF seems to be safe. The effect may last for one month and then decline.

Neuroprotective effects of exogenous erythropoietin in Wistar rats by downregulating apoptotic factors to attenuate N-methyl-D-aspartate-mediated retinal ganglion cells death

The aim of this study was to investigate whether exogenous erythropoietin (EPO) administration attenuates N-methyl-D-aspartate (NMDA)-mediated excitotoxic retinal damage in Wistar rats. The survival rate of retinal ganglion cells (RGCs) were investigated by flat mount analysis and flow cytometry. A total of 125 male Wistar rats were randomly assigned to five groups: negative control, NMDA80 (i.e., 80 nmoles NMDA intravitreally injected), NMDA80 + 10ng EPO, NMDA80 + 50ng EPO, and NMDA80 + 250ng EPO. The NMDA80 + 50ng EPO treatment group was used to evaluate various administrated points (pre-/co-/post- administration of NMDA80). Meanwhile, the transferase dUTP Nick-End Labeling (TUNEL) assay of RGCs, the inner plexiform layer (IPL) thickness and the apoptotic signal transduction pathways of μ-calpain, Bax, and caspase 9 were assessed simultaneously using an immunohistochemical method (IHC). When EPO was co-administered with NMDA80, attenuated cell death occurred through the downregulation of the apoptotic indicators: μ-calpain was activated first (peak at ~18hrs), followed by Bax and caspase 9 (peak at ~40hrs). Furthermore, the images of retinal cross sections have clearly demonstrated that thickness of the inner plexiform layer (IPL) was significantly recovered at 40 hours after receiving intravitreal injection with NMDA80 and 50ng EPO. Exogenous EPO may protect RGCs and bipolar cell axon terminals in IPL by downregulating apoptotic factors to attenuate NMDA-mediated excitotoxic retinal damage.

Serum erythropoietin concentration and its correlation with stage of diabetic retinopathy

BACKGROUND

Erythropoietin (EPO) is one of the systemic angiogenic factors, and its role in ocular angiogenesis and in diabetic retinopathy (DR) is not yet fully understood. The latest research data reveal a possible correlation of higher erythropoietin concentrations in the blood and in the eye with the development of more advanced stages of DR. The main aim of this work was to examine the possible influence of serum concentrations of erythropoietin on the development of diabetic retinopathy in patients with diabetes mellitus type 2.

METHODS

The research involved 90 patients examined at the University Eye Clinic of the Clinical Center of Vojvodina, Novi Sad, Serbia. The first group comprised 60 patients with diabetes mellitus lasting for 10 years or more, with diabetic retinopathy. The second, control group consisted of 30 healthy individuals. In the first group of 60 patients with diabetes, 30 of them had non-proliferative diabetic retinopathy (NPDR), and 30 had proliferative diabetic retinopathy (PDR). Laboratory EPO serum levels were determined, and they were correlated to the stage of DR. Concentration of EPO was assessed by ELISA method.

RESULTS

The highest average concentration of EPO in serum (9.95 mIU/ml) was determined in the group of people with diabetes with PDR. The lowest average concentration of EPO in the serum (6.90 mIU/ml) was found in the control group. The average concentration of EPO in serum in the group of patients with diabetes with NPDR was 7.00 mIU/ml. The EPO concentration in serum was elevated in the group of PDR, and it was directly proportional to the level of the clinical stadium of PDR, being significantly higher in the moderate and severe subgroup of PDR comparing to the control healthy subjects, NPDR and mild PDR (p = 0.007).

CONCLUSIONS

Significantly elevated serum concentration of EPO in the advanced stages of DR, and positive correlation between EPO serum concentration and clinical stages of PDR, suggest that erythropoietin represents an important growth factor from blood, which plays a significant role in retinal ischemia and angiogenesis in diabetic retinopathy, especially in the proliferative stage of this disease.

Visual Outcomes of Adding Erythropoietin to Methylprednisolone for Treatment of Retrobulbar Optic Neuritis

Purpose

To compare the short-term visual function results and safety of erythropoietin as an add-on to the standard corticosteroid therapy in retrobulbar optic neuritis (RON).

Methods

In this prospective pilot study, adult patients with isolated RON with less than 10 days of onset were enrolled. Patients were consecutively assigned to standard intravenous methylprednisolone treatment either in combination with intravenous erythropoietin (20,000 units/day for three days) (group-1) or intravenous methylprednisolone alone (group-2). Primary outcome measure was best-corrected visual acuity (BCVA), which was assessed up to 120 days from the day the treatment was begun. Systemic evaluations were performed during and after treatment.

Results

Sixty-two patients with RON (mean age = 26.6 ± 5.77 years; range = 18–40 years) were enrolled into the study (group-1, n = 35; group-2, n = 27). BCVA three months after the treatment was 0.19 ± 0.55 logMAR and 0.11 ± 0.32 logMAR in group-1 and group-2, respectively (95% CI: -0.61 - 0.16; P = 0.62). Change in BCVA after three months was 2.84 ± 3.49 logMAR in group-1 and 2.46 ± 1.40 logMAR in group-2 (95% CI: -0.93-1.91; P = 0.57). Pace of recovery was not significantly different between the groups. No complications were detected among patients.

Conclusion

Intravenous erythropoietin as an add-on did not significantly improve the visual outcome in terms of visual acuity, visual field, and contrast sensitivity compared to traditional intravenous corticosteroid. This pilot study supports the safety profile of intravenous human recombinant erythropoietin, and it may help formulate future investigations with a larger sample size.

Combination of intravitreal bevacizumab and erythropoietin versus intravitreal bevacizumab alone for refractory diabetic macular edema: a randomized double-blind clinical trial

PURPOSE

To evaluate the effect of three intravitreal bevacizumab (IVB) injections alone or in combination with intravitreal erythropoietin (EPO) in the treatment of refractory diabetic macular edema (DME).

METHODS

In a randomized double-blind clinical trial, 48 eyes of 34 diabetic patients with refractory DME were enrolled. Eyes were randomly assigned to receive either 3 monthly injections of 0.05 cc (1.25 mg) IVB plus 0.05 cc (1000 unit) EPO or 0.05 cc (1.25 mg) IVB alone. Main outcome was best-corrected visual acuity (BCVA) changes and secondary outcome was central macular thickness (CMT). The patients were followed for 6 months.

RESULTS

Mean BCVA changes up to 4 and 6 months were insignificant in both groups. It changed from 0.72 ± 0.56 logMAR at baseline to 0.74 ± 0.5 (P = 0.85) and 0.71 ± 0.44 (P = 0.40) in the combination group and from 0.48 ± 0.39 logMAR to 0.47 ± 0.35 (P = 0.48) and 0.52 ± 0.33 (P = 0.69) in the IVB alone group, at 4 and 6 months, respectively. The difference of mean BCVA changes between the groups was insignificant at both 4 and 6 months (P = 0.07 and P = 0.36, respectively). Within the group changes of mean CMT were significant only in the combination group at 4 and 6 months, from 518 ± 134 μ at baseline to 472 ± 151 to 475 ± 167 μ, respectively (P = 0.01 and P = 0.05). Corresponding changes were not significant in the IVB alone group. However, the difference between the groups was not significant at all visits (P = 0.51 and P = 0.71, respectively).

CONCLUSIONS

This clinical trial demonstrated that intravitreal erythropoietin had no additional effect to IVB in the treatment of refractory DME in the short term.

TRIAL REGISTRATION

Clinical trials.gov identifier: NCT03821168.

Visual-Evoked-Response-Supported Outcome of Intravitreal Erythropoietin in Management of Indirect Traumatic Optic Neuropathy

PURPOSE

Investigating the efficacy of intravitreal injection of erythropoietin (EPO) in managing indirect traumatic optic neuropathy (ITON) of different durations.

METHODS

A case series that included two groups of ITON patients: recent ITON group (<3 months trauma duration; 7 eyes) and old duration ITON group (3-36 months; 7 eyes). Diagnostic computerized tomography (CT) and baseline flash visual evoked response (VER) were performed at the presentation time. At the initial visit and each follow-up, all patients had undergone assessment of best-corrected visual acuity (BCVA), pupil reaction, and anterior and posterior segments. VER was repeated 1 and 3 months after injection. All patients received an intravitreal injection of 2000 IU EPO in 0.2 ml of commercially available sterile EPREX 4000 solution, Jansen Cilag, Zug, Switzerland. Five patients had received a second injection 3 months later.

RESULTS

Significant improvement was found in BCVA, VER amplitude, and latency (P < 0.0001, 0.0154, and 0.0291, respectively). Initial values of BCVA, VER amplitude, and latency correlated significantly to the final values. Differences between recent and old trauma groups were insignificant in the three parameters. In patients who received second injection, further clinical but statistically insignificant improvement was noted in BCVA in 60% of patients, VER amplitude in 50% of patients, and in VER latency in 100% of patients. No complications were recorded.

CONCLUSION

Intravitreal injection of EPO may be effective and safe in treatment of recent and old indirect traumatic optic neuropathy.

Time-dependent changes in hypoxia- and gliosis-related factors in experimental diabetic retinopathy

Diabetes causes various biochemical changes in the retina; long-term changes in the factors associated with hypoxia and gliosis have rarely been reported. The present study was conducted to explore the changes in these factors in a time-dependent manner in experimental diabetic retinopathy (DR). Diabetes was induced in Sprague-Dawley rats by intraperitoneal injection of streptozotocin. The expression of the following factors was examined using immunofluorescence and western blot analysis at 0.5, 1, 2, 4 and 6 months after diabetes onset: hypoxia-inducible factor-1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF), erythropoietin (EPO), erythropoietin receptor (EPOR), glial fibrillary acidic protein (GFAP), vimentin, glutamate-aspartate transporter (GLAST) and glutamine synthase (GS). The expression of factors such as HIF-1alpha, VEGF, EPO, EPOR, GFAP and vimentin, was up-regulated with the progression of diabetes in the diabetic rat retinas compared to the expression in normal control retinas, whereas the expression of GS and GLAST was down-regulated. Changes in EPO and EPOR appeared 2 weeks after diabetes onset. HIF-1alpha, VEGF and GFAP started to increase at 1 month and vimentin at 4 months after diabetes onset. GS and GLAST started to decrease at 1 month after diabetes onset. The expression of these factors, which are involved in the processes of hypoxia and gliosis, varied at different stages of DR. The time-course change may be helpful in the evaluation of the progression of DR, and it may indicate the optimal intervention time points for DR.

Functional and Structural Effects of Erythropoietin Subconjunctival Administration in Glaucomatous Animals

Purpose

The present study aimed to assess functional and structural benefits of erythropoietin (EPO) when administered subconjunctivally in the retina of glaucomatous rats using electroretinography (ERG) and retinal thickness (RT) measurements.

Methods

Glaucoma was experimentally induced in 26 Wistar Hannover albino rats. Animals were divided into 2 groups of 13 animals each: a treated group receiving a unique subconjunctival injection of 1,000 IU of EPO and a control group receiving a saline solution. In each group, 7 animals were used for retinal function evaluation (ERG) and 6 animals were used for retinal structural evaluation (histology). RT was measured, dorsally and ventrally, at 500 μm (RT1) and at 1,500 μm (RT2) from the optic nerve.

Results

Retinal function evaluation: for both scotopic and photopic conditions, ERG wave amplitudes increased in the treated group. This increase was statistically significant (p < 0.05) in photopic conditions. Structural evaluation: for both locations RT1 and RT2, the retinas were significantly (p < 0.05) thicker in the treated group.

Conclusion

Subconjunctival EPO administration showed beneficial effects both on retinal structure and on retinal function in induced glaucoma in albino rats. This neuroprotective effect should be applied in other animal species.

Neuroprotective effects of erythropoietin on rat retinas subjected to oligemia

OBJECTIVES

Erythropoietin may have neuroprotective potential after ischemia of the central nervous system. Here, we conducted a study to characterize the protective effects of erythropoietin on retinal ganglion cells and gliotic reactions in an experimentally induced oligemia model.

METHODS

Rats were subjected to global oligemia by bilateral common carotid artery occlusion and then received either vehicle or erythropoietin via intravitreal injection after 48 h; they were euthanized one week after the injection. The densities of retinal ganglion cells and contents of glial fibrillary acidic protein (astrocytes/Müller cells) and cluster of differentiation 68 clone ED1 (microglia/macrophages), assessed by fluorescence intensity, were evaluated in frozen retinal sections by immunofluorescence and epifluorescence microscopy.

RESULTS

Retinal ganglion cells were nearly undetectable one week after oligemia compared with the sham controls; however, these cells were partially preserved in erythropoietin-treated retinas. The contents of glial fibrillary acidic protein and cluster of differentiation 68 clone ED1, markers for reactive gliosis, were significantly higher in retinas after bilateral common carotid artery occlusion than those in both sham and erythropoietin-treated retinas.

CONCLUSIONS

The number of partially preserved retinal ganglion cells in the erythropoietin-treated group suggests that erythropoietin exerts a neuroprotective effect on oligemic/ischemic retinas. This effect could be related to the down-modulation of glial reactivity, usually observed in hypoxic conditions, clinically observed during glaucoma or retinal artery occlusion conditions. Therefore, glial reactivity may enhance neurodegeneration in hypoxic conditions, like normal-tension glaucoma and retinal ischemia, and erythropoietin is thus a candidate to be clinically applied after the detection of decreased retinal blood flow.

Erythropoietin promoted the proliferation of hepatocellular carcinoma through hypoxia induced translocation of its specific receptor

Background

Erythropoietin (EPO) is a hypoxia-inducible stimulator of erythropoiesis. Besides its traditional application in anemia therapy, it offers an effective treatment in the cancer patients, especially those who receive chemotherapy. Several reports indicated that it could promote the tumor cell proliferation through its specific receptor (EPOR). Unfortunately, the role of EPO/EPOR in hepatocellular carcinoma (HCC) progressing is still uncertain.

Methods

Protein in tumor tissue from HCC patients or H22 tumor-bearing mice was detected with immunohistochemistry. Cells were cultured under 1% oxygen to establish hypoxia. RT-PCR and western blotting were used to measure mRNA and protein of EPO/EPOR, respectively. MTT, flow cytometry and PCNA staining were used to detect cell proliferation. Immunofluorescence staining was applied to study the expression and location of cellular EPOR. The EPOR binding studies were performed with ¹²⁵I-EPO radiolabeling assay.

Results

EPO and EPOR protein were up-regulated in HCC tissue of patients and H22-bearing mice. These were positively correlated with hypoxia-inducible factor -1 α and ki-67. Hypoxia up-regulated the expression of EPO and EPOR in HepG2 cells. It also induced the proliferation and increased the percentage of divided cells after 24, 48 and 72 h treatment. These were inhibited in cells pre-treated with 0.5 μg/mL soluble-EPOR. Immunofluorescence staining presented that EPOR was obviously translocated from nucleus to cytoplasm and membrane under hypoxia. EPOR binding activity was also increased after exposure to hypoxia. Recombinant human erythropoietin obviously elevated cell proliferation rate and the percentage of divided under hypoxia but not normoxia, which were also inhibited by soluble-EPOR.

Conclusions

Our result indicated for the first time that EPO promoted the proliferation of HCC cells through hypoxia induced translocation of it specific receptor.

Trial registration TJC20141113, retrospectively registered

Association between macular degeneration and mild to moderate chronic kidney disease: A nationwide population-based study

Chronic kidney disease (CKD) and macular degeneration (MD) are 2 grave diseases leading to significant disability secondary to renal failure and blindness. The 2 diseases share not only common risk factors but also similar pathogenic mechanisms to renal and retinal injuries. Previous epidemiological studies indicated association between these 2 diseases. However, this concept is challenged by recent investigations. Patients with mild to moderate CKD (n = 30,696) between January 1, 1995 and December 31, 2005 were selected from the Taiwan National Health Insurance Database. Controls (n = 122,784) were matched by age, gender, diabetes mellitus type 2, and hypertension status (1:4 ratios). The risk of MD was compared between the 2 groups. The mean age of patients was 54.9 ± 15.7 years. The proportion of MD was 2.7% in mild to moderate CKD patients and 1.9% in normal controls (P < 0.001); and, 0.39% and 0.26% (P < 0.001) in advanced MD. Mild to moderate CKD patients had higher risk for MD [adjusted odds ratio (OR), 1.301; 95% confidence interval (CI), 1.200-1.411; P < 0.001] than normal renal function subjects. The association was more pronounced for advanced MD. From all age strata (10 years increase), the presence of CKD in those patients aged less than 40 years had highest OR for all MD (OR = 2.125, 95% CI: 1.417-3.186, P < 0.001). The results were consistent in interaction terms, highlighting the importance of CKD in young age patient for risk of MD. The high risk for MD in mild to moderate CKD patients remains significant after adjustment for personal habits (alcohol drinking and smoking, model 1; OR: 1.371; 95% CI: 1.265-1.486; P < 0.001), comorbidities (dyslipidemia, cerebrovascular disease, and peripheral vascular disease, model 2; OR: 1.369; 95% CI: 1.264-1.484; P < 0.001) and all these factors (model 3; OR: 1.320, 95% CI: 1.218-1.431, P < 0.001). This association was consistent in the subanalysis, excluding those patients with diabetic retinopathy. Proper diagnosis and timely intervention should be warranted to retard visual loss of these patients.

The Effect of Combined Systemic Erythropoietin and Steroid on Non-arteritic Anterior Ischemic Optic Neuropathy: A Prospective Study

BACKGROUND

To investigate the effect of combined intravenous (IV) erythropoietin (EPO) and corticosteroid as well as systemic steroid alone for the treatment of non-arteritic anterior ischemic optic neuropathy (NAION).

METHODS

In this prospective interventional comparative case series, 113 consecutive patients diagnosed with recent onset (less than 14 days) NAION were included. Patients were categorized into three groups. 40 patients received systemic IV corticosteroid combined with recombinant human erythropoietin (rhEPO) (group 1), 43 patients received systemic corticosteroid alone (group 2), and 30 patients were enrolled as the control group (group 3). Functional and structural outcomes were analyzed 3 and 6 months after treatment. Best corrected visual acuity (BCVA) was the main outcome, and mean deviation (MD) and peripaillary retinal nerve fiber layer thickness (PRNFLT) were secondary outcome measures.

RESULTS

The mean BCVA at the time of presentation was 0.98 (±0.65), 0.96 (±0.67), and 1.02 (±0.63) log MAR in groups 1, 2, and 3, respectively (P = 0.95). At month 3, the corresponding values were 0.73 (±0.45), 0.76 (±0.49), and 0.8 (±0.45) log MAR (P = 0.80), and at the 6-month follow-up, they were 0.76 (±0.45), 0.71 (±0.4), and 0.71 (±0.46) log MAR, respectively (P = 0.87). There was no statistically significant difference in BCVA between months 3 and 6, which implies stabilization of the visual acuity by month 3. Considering the visual field, within 6 months of follow-up after disease onset, the MD index improved in all groups with no statistically significant differences between them (P = 0.82). PRNFLT at presentation was 178 (±60), 186 (±59), and 166 (±57) micrometers in groups 1, 2, and 3, respectively (P= 0.99), which decreased to 77 (±16), 83 (±22), and 73 (±11), respectively, at final visit (P = 0.14) Conclusion: We found no beneficial effect of either systemic steroid alone or combined with EPO in the visual outcome of NAION patients.

Erythropoietin promoted the proliferation of hepatocellular carcinoma through hypoxia induced translocation of its specific receptor

BACKGROUND

Erythropoietin (EPO) is a hypoxia-inducible stimulator of erythropoiesis. Besides its traditional application in anemia therapy, it offers an effective treatment in the cancer patients, especially those who receive chemotherapy. Several reports indicated that it could promote the tumor cell proliferation through its specific receptor (EPOR). Unfortunately, the role of EPO/EPOR in hepatocellular carcinoma (HCC) progressing is still uncertain.

METHODS

Protein in tumor tissue from HCC patients or H22 tumor-bearing mice was detected with immunohistochemistry. Cells were cultured under 1% oxygen to establish hypoxia. RT-PCR and western blotting were used to measure mRNA and protein of EPO/EPOR, respectively. MTT, flow cytometry and PCNA staining were used to detect cell proliferation. Immunofluorescence staining was applied to study the expression and location of cellular EPOR. The EPOR binding studies were performed with ¹²⁵I-EPO radiolabeling assay.

RESULTS

EPO and EPOR protein were up-regulated in HCC tissue of patients and H22-bearing mice. These were positively correlated with hypoxia-inducible factor -1 α and ki-67. Hypoxia up-regulated the expression of EPO and EPOR in HepG2 cells. It also induced the proliferation and increased the percentage of divided cells after 24, 48 and 72 h treatment. These were inhibited in cells pre-treated with 0.5 μg/mL soluble-EPOR. Immunofluorescence staining presented that EPOR was obviously translocated from nucleus to cytoplasm and membrane under hypoxia. EPOR binding activity was also increased after exposure to hypoxia. Recombinant human erythropoietin obviously elevated cell proliferation rate and the percentage of divided under hypoxia but not normoxia, which were also inhibited by soluble-EPOR.

CONCLUSIONS

Our result indicated for the first time that EPO promoted the proliferation of HCC cells through hypoxia induced translocation of it specific receptor. Trial registration TJC20141113, retrospectively registered.