Iron chelation abrogates excessive formation of hydroxyl radicals and lipid peroxidation products in monocytes of patients with Eales' disease: direct evidence using electron spin resonance spectroscopy

DIBI, a polymeric hydroxypyridinone iron chelator, reduces ocular inflammation in local and systemic endotoxin-induced uveitis

BACKGROUND/OBJECTIVE

Non-infectious uveitis is an inflammatory disease of the eye commonly treated by corticosteroids, though important side effects may result. A main mediator of inflammation are oxygen free radicals generated in iron-dependent pathways. As such, we investigated the efficacy of a novel iron chelator, DIBI, as an anti-inflammatory agent in local and systemic models of endotoxin induced uveitis (EIU).

METHODS

Firstly, the effects of DIBI in systemic EIU in Lewis rats were established. 2 hours post intravenous LPS or LPS/DIBI injections, leukocyte activation and functional capillary density (FCD) were examined using intravital microscopy (IVM) of the iridial microcirculation. Secondly, the toxicity of DIBI was evaluated in BALB/C mice for both acute and chronic dosages through gross ocular examination, intraocular pressure measurements and hematoxylin-eosin staining of ocular tissue. Lastly, three groups of BALB/C mice, control, LPS or DIBI + LPS, were studied to evaluate the effectiveness of DIBI in treating local EIU. Five hours post-local intravitreal (i.v) injection, leukocyte activation and capillary density were examined via IVM.

RESULTS

Treatment of systemic EIU with DIBI resulted in a reduction of leukocyte activation and FCD improvement within the iridial microcirculation. Toxicity studies suggested that acute and chronic DIBI administration had no adverse effects in the eye. In the local EIU model, DIBI was shown to reduce leukocyte activation and restored the FCD/DCD ratio, providing evidence for its anti-inflammatory properties.

CONCLUSIONS

Our study has provided evidence that DIBI has anti-inflammatory effects in experimental uveitis. Additionally, no local ocular toxicity was observed.

The 88-kDa Eales' protein in serum is a complex of haptoglobin, complement C3, and galectin-1 as identified by liquid chromatography coupled mass spectrometry

PURPOSE

Eales' disease (ED), an enigmatic inflammatory disease, affects peripheral retinal veins and thereby vision in males. This study was aimed at identifying and deciphering the role of a novel 88-kDa protein reported in the serum and vitreous of patients with ED.

EXPERIMENTAL DESIGN

The purified 88-kDa protein was identified by UPLC coupled ESI-QTOF-MS. The identified proteins were quantified in the serum from 20 ED patients and controls (age and sex matched), respectively by ELISA. The interaction of these proteins was studied using co-immunoprecipitation, western blot, and MS analyses. N-glycosylation of protein was observed by MS and lectin blot.

RESULTS

The 88-kDa protein was identified to be a complex of haptoglobin, complement C3, and galectin-1. ELISA results showed a 1.5-fold increase in levels of haptoglobin (p = 0.008), with level of complement C3 unaltered and 1.2-fold decreased serum galectin-1 levels (p = 0.003) in ED patients compared to controls. Co-immunoprecipitation illustrated the interaction between haptoglobin and complement C3. Reduced sialylation and increased β-1, 6-N-acetyl-glucosamine branched N-glycans were observed in haptoglobin of ED patients.

CONCLUSION

The 88-kDa protein, a complex of haptoglobin, complement C3, and galectin-1, may play a potential role in ED pathogenesis while levels galectin-1 and haptoglobin may serve as potential biomarker of ED.

Localization of Human Copper Transporter 1 in the Eye and its Role in Eales Disease

PURPOSE

Copper (Cu) is an essential trace element; however excess is toxic due to the pro-oxidant activity. Increased intracellular Cu levels in vitreous and monocyte were reported in Eales disease (ED) previously. Copper transporter1 (CTR1) maintains copper homeostasis and hence, we studied the presence of CTR1 in ocular tissues and its role in ED.

METHODS

Real-time PCR, ELISA and Western blot experiments were performed in donor eyeballs tissues and PBMCs isolated from controls and ED. Immunostaining were performed for CTR1 from donor eyeballs and one ED case.

RESULTS

CTR1 protein was expressed in all ocular tissues. PBMCs showed a three-fold increase in CTR1 protein in ED when compared with controls. Retinal sections from ED patients also revealed increased CTR1 protein expression in retinal tissues, compared with control.

CONCLUSIONS

CTR1 was significantly increased in ED when compared with controls, indicating its considerable role in the ED pathology.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

Eales' disease - current concepts in diagnosis and management

Eales' disease, first described by the British ophthalmologist Henry Eales in 1880, is characterized by three overlapping stages of venous inflammation (vasculitis), occlusion, and retinal neovascularization. Diagnosis is mostly clinical and requires exclusion of other systemic or ocular conditions that could present with similar retinal features. In recent years, immunological, molecular biological, and biochemical studies have indicated the role of human leukocyte antigen, retinal autoimmunity, Mycobacterium tuberculosis genome, and free radical-mediated damage in the etiopathogenesis of this disease. However, its etiology appears to be multifactorial. The management depends on the stage of the disease and consists of medical treatment with oral corticosteroids in the active inflammatory stage and laser photocoagulation in the advanced retinal ischemia and neovascularization stages.

Eales' disease: the great masquerader

BACKGROUND

Eales' disease, also known as idiopathic retinal periphlebitis, is a diagnosis of exclusion, mainly affecting men in the second through fourth decades of life. Although less common in the United States, Eales' disease is widespread in India and certain areas of the Middle East.

CASE REPORT

A healthy, 42-year-old Filipino man presented with reduced vision in the right eye of 2 days' duration and had recently had a nonrhegmatogenous retinal detachment diagnosed. Clinical findings included angle neovascularization, posterior vitritis, intraretinal hemorrhages, and retinal vascular sheathing in that eye. Systemic evaluation did not disclose an underlying etiology. Eales' disease was diagnosed. Treatment included topical steroids and cycloplegia, along with intravitreal triamcinolone acetonide injection, which yielded an improvement in the vasculitis and vitritis with subsequent visual improvement and stabilization.

CONCLUSION

Eales' disease should be considered as a differential diagnosis in patients with vasculitis and vitritis.

Ratio of the vitreous vascular endothelial growth factor and pigment epithelial-derived factor in Eales disease

Eales disease (ED) is an idiopathic inflammatory venous occlusion of the peripheral retina. As neovascularization is prominent in ED, this study attempts to look at the ratio of VEGF, the angiogenic factor, and PEDF, an anti-angiogenic factor in the vitreous of ED patients in comparison with the macular hole (MH) and Proliferative Diabetic Retinopathy (PDR). Vitreous levels of VEGF and PEDF were determined in the undiluted vitreous specimen obtained from 26 ED cases, 17 PDR, and seven patients with MH. The vitreous levels of VEGF and PEDF were estimated by ELISA. The immunohistochemistry (IHC) for VEGF and PEDF were done in the epiretinal membrane of ED and PDR case. The VEGF/PEDF ratio was found to be significantly increased in ED (p = 0.014) and PDR (p = 0.000) compared to MH. However the ratio was 3.5-fold higher in PDR than ED (p = 0.009). The IHC data on the ERM specimen from ED showed the presence of VEGF and PEDF similar to PDR. The high angiogenic potential seen as the ratio of VEGF/PEDF correlates with the peak clinical onset of the disease in the age group 21–30 years and the diseases usually self-resolves above the age of 40, which is reflected by the low ratio of VEGF/PEDF. The study shows that the VEGF/PEDF ratio is significantly increased in ED though the angiogenic potential is higher in PDR than in ED. Clinically Eales Disease is known as a self-limiting disease, while PDR is a progressive disease.

Increase in Fe3+/Fe2+ ratio and iron-induced oxidative stress in Eales disease and presence of ferrous iron in circulating transferrin

Eales disease was shown to be associated with oxidant stress and weak antioxidant defense. Total iron, ferrous iron, thiobarbituric acid reactive substances (TBARS), and ceruloplasmin were estimated in the blood samples of patients with inflammation, perivasculitis, and venous insufficiency. Levels of ferric iron were determined from the difference in those of total iron and ferrous iron. All biochemical parameters were estimated in age and sex-matched controls. Fe3+/Fe2+ ratio was greater in patients with Eales disease than in normal controls. Similar increase in TBARS and ceruloplasmin levels were noted. The patients were treated with prednisone and vitamins E and C, then Fe3+/Fe2+ ratios and TBARS decreased progressively; the active state of the disease was reduced to 16%. So Fe3+/Fe2+ ratio in addition to TBARS levels could be considered an index of the active state of the disease. Circulating transferrin in blood did contain ferrous iron. Binding of ferrous iron to transferrin was confirmed by estimating iron-binding capacity using ferrous ammonium sulphate.

Deferiprone, an orally deliverable iron chelator, ameliorates experimental autoimmune encephalomyelitis

The iron chelator, Desferal, suppressed disease activity of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), and it has been tested in pilot trials for MS. The administration regimen of Desferal is cumbersome and prone to complications. Orally-deliverable, iron chelators have been developed that circumvent these difficulties, and the objective of this study was to test an oral chelator in EAE. SJL mice with active EAE were randomly assigned to receive deferiprone (150 mg/kg) or vehicle (water) 2×/day via gavage. EAE mice given deferiprone had significantly less disease activity and lower levels of inflammatory cell infiltrates (revealed by H&E staining) than EAE mice administered vehicle. T-cell infiltration, assessed by anti-CD3 immunohistochemical staining, also was reduced, although not significantly. Splenocytes cultured from naïve SJL mice were stimulated with anti-CD3 and anti-CD28 with or without 250 μM deferiprone. While ~39% of costimulated splenocytes without deferiprone underwent division, only ~2.8% of costimulated splenocytes with deferiprone divided and the latter cells were only 53% as viable as the former. Deferiprone had no effect on proliferation or viability of cells that were not costimulated. In summary, deferiprone effectively suppressed active EAE disease and it inhibited T-cell function. Multiple Sclerosis 2007; 13: 1118—1126. http://msj.sagepub.com