Levels of aqueous humor trace elements in patients with non-exsudative age-related macular degeneration: a case-control study

Retinal toxicity of heavy metals and its involvement in retinal pathology

The objective of the present review is to discuss epidemiological evidence demonstrating the association between toxic metal (Cd, Pb, Hg, As, Sn, Ti, Tl) exposure and retinal pathology, along with the potential underlying molecular mechanisms. Epidemiological studies demonstrate that Cd, and to a lesser extent Pb exposure, are associated with age-related macular degeneration (AMD), while the existing evidence on the levels of these metals in patients with diabetic retinopathy is scarce. Epidemiological data on the association between other toxic metals and metalloids including mercury (Hg) and arsenic (As), are limited. Clinical reports and laboratory in vivo studies have shown structural alterations in different layers of retina following metal exposure. Examination of retina samples demonstrate that toxic metals can accumulate in the retina, and the rate of accumulation appears to increase with age. Experimental studies in vivo and in vitro studies in APRE-19 and D407 cells demonstrate that toxic metal exposure may cause retinal damage through oxidative stress, apoptosis, DNA damage, mitochondrial dysfunction, endoplasmic reticulum stress, impaired retinogenesis, and retinal inflammation. However, further epidemiological as well as laboratory studies are required for understanding the underlying molecular mechanisms and identifying of the potential therapeutic targets and estimation of the dose-response effects.

The Potential of Selenium-Based Therapies for Ocular Oxidative Stress

Oxidative stress plays a critical role in the development of chronic ocular conditions including cataracts, age-related macular degeneration, and diabetic retinopathy. There is a need to explore the potential of topical antioxidants to slow the progression of those conditions by mediating oxidative stress and maintaining ocular health. Selenium has attracted considerable attention because it is a component of selenoproteins and antioxidant enzymes. The application of selenium to a patient can increase selenoprotein expression, counteracting the effect of reactive oxygen species by increasing the presence of antioxidant enzymes, and thus slowing the progression of chronic ocular disorders. Oxidative stress effects at the biomolecular level for prevalent ocular conditions are described in this review along with some of the known defensive mechanisms, with a focus on selenoproteins. The importance of selenium in the eye is described, along with a discussion of selenium studies and uses. Selenium's antioxidant and anti-inflammatory qualities may prevent or delay eye diseases. Recent breakthroughs in drug delivery methods and nanotechnology for selenium-based ocular medication delivery are enumerated. Different types of selenium may be employed in formulations aimed at managing ocular oxidative stress conditions.

Ferroptosis in Glaucoma: A Promising Avenue for Therapy

Glaucoma, a blind-leading disease largely since chronic pathological intraocular high pressure (ph-IOP). Hitherto, it is reckoned incurable for irreversible neural damage and challenges in managing IOP. Thus, it is significant to develop neuroprotective strategies. Ferroptosis, initially identified as an iron-dependent regulated death that triggers Fenton reactions and culminates in lipid peroxidation (LPO), has emerged as a focal point in multiple tumors and neurodegenerative diseases. Researches show that iron homeostasis play critical roles in the optic nerve (ON) and retinal ganglion cells (RGCs), suggesting targeted treatments could be effective. In glaucoma, apart from neural lesions, disrupted metal balance and increased oxidative stress in trabecular meshwork (TM) are observed. These disturbances lead to extracellular matrix excretion disorders, known as sclerotic mechanisms, resulting in refractory blockages. Importantly, oxidative stress, a significant downstream effect of ferroptosis, is also a key factor in cell senescence. It plays a crucial role in both the etiology and risk of glaucoma. Moreover, ferroptosis also induces non-infectious inflammation, which exacerbate glaucomatous injury. Therefore, the relevance of ferroptosis in glaucoma is extensive and multifaceted. In this review, the study delves into the current understanding of ferroptosis mechanisms in glaucoma, aiming to provide clues to inform clinical therapeutic practices.

Trace Element Concentration in the Blood and Aqueous Humor of Subjects with Eye Cataract

Cataract, characterized by the opacification of the lens, is the leading cause of reversible blindness and visual impairment globally. The study aims to investigate the role of trace elements such as Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn in the development and severity of cataract. Elements were quantified by inductively coupled plasma mass spectrometry in blood and aqueous humor of 32 cataract cases and 27 controls living in the Latium region, Italy. The association between element concentration in blood and aqueous humor and cataract severity, gender, and age of subjects were also assessed. Results showed Cr levels significantly elevated in both blood and aqueous humor of cataract cases, with concentrations that increased with cataract severity. In addition, blood Pb levels were significantly higher in older cases and positively correlated with the age of cataract cases, while blood Co and Cu levels negatively correlated with cataract severity, suggesting changes in the levels of these elements. In conclusion, this study provides evidence of the involvement of specific elements in cataract development and severity, and the findings highlighted important avenues for future research. Understanding the biological mechanism underlying element-induced cataract may contribute to preventing cataractogenesis and providing targeted interventions.

Environmental exposures to cadmium and lead as potential causes of eye diseases

Humans are exposed to cadmium and lead in various regions of the world daily due to industrial development and climate change. Increasing numbers of preclinical and clinical studies indicate that heavy metals, such as cadmium and lead, play a role in the pathogenesis of eye diseases. Excessive exposure to heavy metals such as cadmium and lead can increase the risk of impaired vision. Therefore, it is essential to better characterize the role of these non-essential metals in disease etiology and progression. This article discusses the potential role of cadmium and lead in the development of age-related eye diseases, including age-related macular degeneration, cataracts, and glaucoma. Furthermore, we discuss how cadmium and lead affect ocular cells and provide an overview of putative pathological mechanisms associated with their propensity to damage the eye.

Age-Related Macular Degeneration and Mitochondria-Associated Autoantibodies: A Review of the Specific Pathogenesis and Therapeutic Strategies

Age-related macular degeneration (AMD) is a severe retinal disease that causes irreversible visual loss and blindness in elderly populations worldwide. The pathological mechanism of AMD is complex, involving the interactions of multiple environmental and genetic factors. A poor understanding of the disease leads to limited treatment options and few effective prevention methods. The discovery of autoantibodies in AMD patients provides an opportunity to explore the pathogenesis and treatment direction of the disease. This review focuses on the mitochondria-associated autoantibodies and summarizes the functional roles of mitochondria under physiological conditions and their alterations during the pathological states. Additionally, it discusses the crosstalk between mitochondria and other organelles, as well as the mitochondria-related therapeutic strategies in AMD.

Quantification of Metal(loid)s in Lubricating Eye Drops Used in the Treatment of Dry Eye Disease

The aim of the study was to evaluate the presence of metal(loid)s in lubricating eye drops used in the treatment of dry eye disease. The concentrations of Al, As, Ba, Cd, Co, Cu, Cr, Pb, Fe, Mg, Mn, Mo, Ni, Se, V, and Zn were determined in 19 eye drop samples using inductively coupled plasma optical emission spectrometry (ICP OES). The limit of detection (LOD) and limit of quantification (LOQ) values for the quantified elements ranged from 0.0002-0.0363 (mg/L) and 0.0007-0.1211 (mg/L), respectively. High values of concentrations of Al (2.382 µg/g), As (0.204 µg/g), Ba (0.056 µg/g), Cd (0.051 µg/g), Co (1.085 µg/g), Cr (0.020 µg/g), Cu (0.023 µg/g), Fe (0.453 µg/g), Mg (24.284 µg/g), Mn (0.014 µg/g), Mo (0.046 µg/g), Ni (0.071 µg/g), Pb (0.049 µg/g), Se (0.365 µg/g), V (0.083 µg/g), and Zn (0.552 µg/g) were quantified in samples of eye drops with and without preservatives. The concentrations of As (5 samples) and Cd (3 samples) were higher than those allowed by the Brazilian Pharmacopoeia for impurities (parenteral use). The value of Co content (µg/g) in a sample was higher than the value established by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH Q3D (R2)) in the parenteral route. The daily eye drop instillation exposure (µg/day) was below the values from the parenteral-permitted daily exposure (PDE) set by the ICH Q3D guideline (R2). The presence of heavy metals in eye drops is an alert to regulatory agencies in several countries so that control and inspections can be carried out.

Multiomic Mass Spectrometry Imaging to Advance Future Pathological Understanding of Ocular Disease

Determining the locations of proteins within the eye thought to be involved in ocular pathogenesis is important to determine how best to target them for therapeutic benefits. However, immunohistochemistry is limited by the availability and specificity of antibodies. Additionally, the perceived role of both essential and non-essential metals within ocular tissue has been at the forefront of age-related macular degeneration (AMD) pathology for decades, yet even key metals such as copper and zinc have yet to have their roles deconvoluted. Here, mass spectrometry imaging (MSI) is employed to identify and spatially characterize both proteomic and metallomic species within ocular tissue to advance the application of a multiomic imaging methodology for the investigation of ocular diseases.

Research progress of ferroptosis in glaucoma and optic nerve damage

Unlike other death forms, such as autophagy, necrosis, and apoptosis, ferroptosis is a novel type of programmed cell death with iron-dependent properties. Esteroxygenase affects the content of unsaturated fatty acids and promotes lipid peroxidation. In addition, GSH can cause the reduction of GPX4, which can cause ferroptosis. P53 and its signaling pathways also regulate ferroptosis. Recent studies have confirmed that ferroptosis also promotes the death of RGC. The progressive loss of RGC is one of the pathological features of glaucoma, indicating that ferroptosis may be related to the onset of glaucoma. Down-regulation of GPX4 leads to the loss of nerve cells, which suggests that ferroptosis may also be related to diseases related to optic nerve damage. At present, ferroptosis has been extensively researched and advanced in systemic diseases, such as cardiovascular diseases, gastrointestinal tumors such as stomach, liver, and pancreas, and brain diseases. This review focuses on the research progress of ferroptosis in ophthalmic diseases, especially glaucoma and optic nerve damage.

Targeted Analysis of Tears Revealed Specific Altered Metal Homeostasis in Age-Related Macular Degeneration

Purpose

Specific altered metal homeostasis has been investigated in the tear film of age-related macular degeneration (AMD) patients considering that metal dyshomeostasis contributes to the production of free radicals, inflammation, and apoptosis and results in conformational changes of proteins.

Methods

A multitargeted approach based on spectrophotometry and mass spectrometry techniques has been implemented to the multiplexed quantitation of lactoferrin (LF), S100 calcium binding protein A6 (S100A6), metallothionein 1A (MT1A), complement factor H (CFH), clusterin (CLU), amyloid precursor protein (APP), Mg, P, Na, Fe, Cu, Zn, and Ca, in the tear film from 60 subjects, 31 patients diagnosed with the dry form of AMD, and 29 healthy individuals

Results

Significant up-regulations of MT1A (1.9-fold) and S100A6 (1.4-fold) and down-regulations of LF (0.7-fold), Fe (0.6-fold), Mg (0.7-fold), and Cu (0.7-fold) were observed in AMD patients, when compared to control subjects. Of all the studied variables, only APP showed negative correlation with age in the AMD group. Also, positive correlations were observed for the variables Mg and Na, Cu and Mg, and P and Mg in both the AMD and control groups, whereas positive correlations were exclusively determined in the AMD group for Cu and LF, Na and Ca, and Mg and Ca. The panel constituted of MT1A, Na, and Mg predicts AMD disease in 73% of cases.

Conclusions

The different levels of target metals and (metallo-)proteins in the tear film suggest altered metal homeostasis in AMD patients. These observed pathophysiological changes may be related with the anomalous protein aggregation in the macula.

Nanoprotection Against Retinal Pigment Epithelium Degeneration via Ferroptosis Inhibition

Lethal oxidative stress and ferrous ion accumulation-mediated degeneration/death in retinal pigment epithelium (RPE) exert an indispensable impact on retinal degenerative diseases with irreversible visual impairment, especially in age-related macular degeneration (AMD), but corresponding pathogenesis-oriented medical intervention remains controversial. In this study, the potent iron-binding nanoscale Prussian blue analogue KCa[Fe^III (CN)₆ ] (CaPB) with high biocompatibility is designed to inhibit RPE death and subsequently photoreceptor cell degeneration. In mice, CaPB effectively prevents RPE degeneration and ultimately fulfills superior therapeutic outcomes upon a single intravitreal injection: significant rescue of retinal structures and visual function. Through high-throughput RNA sequencing and sophisticated biochemistry evaluations, the findings initially unveil that CaPB nanoparticles protect against RPE degradation by inhibiting ferroptotic cell fate. Together with the facile, large-scale preparations and in vivo biosafety, it is believed that the synthesized CaPB therapeutic nanoparticles are promising for future clinical treatment of diverse retinal diseases involving pathological iron-dependent ferroptosis, including AMD.

Hemodialysis Effect on the Composition of the Eye Fluid of Cataract Patients

Numerous reports have proven that dialysis patients experience disturbances in the levels of elements in biological fluids. Disturbances in the homeostasis of essential elements or the appearance of highly toxic elements are serious problems also in clinical ophthalmology. The purpose of this study was to investigate the influence of hemodialysis (HD) on the elemental composition of anterior chamber aqueous humor (AH) in patients undergoing cataract surgery. The study involved 22 patients. The control group enrolled 16 patients (age 75.68 ± 9.67, female 54.55%, male 45.45%) with cataract and normal kidney function (control), and the second group included six patients (age 70.33 ± 12.74, female 33.33%, male 66.67%) with cataract undergoing HD treatment. The elements quantification was established using an inductively coupled plasma optical emission spectrometer (ICP-MS). In the eye fluid of dialysis patients, there were increased levels of manganese (Mn) and mercury (Hg) and decreased levels of vanadium (V) and zinc (Zn). In addition, a statistically significant increase in the Hg/Zn and Hg/selenium (Se) ratios and a lowering of the iron (Fe)/Mn ratio were observed in the studied group in comparison to the control. The obtained results indicated the need for Zn and Se supplementation in order to eliminate the hazards caused by Hg toxicity. A lower level of V in the eye fluid of dialysis patients may have a positive effect on maintaining a calcium and phosphorus homeostasis. Our study gives a deep insight into changes of elements concentrations in AH induced by HD.

The Multi-Elemental Composition of the Aqueous Humor of Patients Undergoing Cataract Surgery, Suffering from Coexisting Diabetes, Hypertension, or Diabetic Retinopathy

The aim of the study was the multi-elemental analysis of aqueous humor (AH) collected from patients undergoing cataract surgery. The study included: 16 patients with age-related macular degeneration AMD (99 controls), 10 patients with retinopathy (105 controls), 61 patients with hypertension (54 controls), and 33 patients with coexisting diabetes (82 controls). The control groups were recruited from patients with a lack of co-existing disease characterizing the specified studied group. The measurements were performed by the use of inductively coupled plasma optical emission spectrometry (ICP-OES). The statistical analysis was carried out using non-parametric testing (Mann–Whitney U). The level of significance was set at p = 0.05. The data obtained revealed substantial variations in elemental composition between the test groups in comparison to the controls. However, the significant variations concerned only a few elements. The phosphorous (P) level and the ratio of P/Ca were significant in retinopathy and diabetes, whereas cobalt (0.091 ± 0.107 mg/L vs. 0.031 ± 0.075 mg/L; p = 0.004) was significant in AMD. In co-existing hypertension, the levels of tin (0.293 ± 0.409 mg/L vs. 0.152 ± 0.3 mg/L; p = 0.031), titanium (0.096 ± 0.059 mg/L vs. 0.152 ± 0.192 mg/L; p = 0.045), and ruthenium (0.035 ± 0.109 mg/L vs. 0.002 ± 0.007 mg/L; p = 0.006) varied in comparison to the controls. The study revealed inter-elemental interactions. The correlation matrices demonstrated the domination of the positive correlations, whereas negative correlations mainly concerned sodium.

Role of biometals in activation of immune cum inflammatory response in ovine ageing eye: a potential model for understanding human geriatric eye diseases

The present study was designed to evaluate the age-related changes in biometal and antimicrobial peptide (cathelicidin) concentration and their role in oxidative cum pro-inflammatory cascade in an ovine animal model. Clinically healthy ovine (n = 126) were grouped as Group I (n = 55, age = up to 3 years), Group II (n = 52, age = above 3-below 6 years) and Group III (n = 19, age = 6 years above). Samples (aqueous humour and lens of the eye) were collected stored at - 80 °C till further analysis. In aqueous humour, the concentration of zinc (p < 0.001 in group III), copper (p < 0.05 in group II and p < 0.001 group III) and iron (p < 0.05 in group III) were significantly increased compared to group I. While as the concentration of magnesium were significantly decreased in group II (p < 0.001) and group III (p < 0.05) compared to group I. Similarly in eye lens the level of copper remained uniform as no significant change was observed across different age groups, while as significantly elevated levels of iron were observed in group III (p < 0.001) compared to group I. whereas, levels of lens Zinc (p < 0.05 in group II) and magnesium (p < 0.05 in group III and p < 0.001 in group II) were significantly decreased compared to group I. Age-dependent increase in levels of oxidation products which include advanced oxidation protein products (AOPP) in aqueous humour and lenses of group II and group III (p < 0.001) and MDA in aqueous humour of group III (p < 0.05) were found compared to levels recorded in group I. In contrast, levels of antioxidants which include lens vitamin C in group II and group III (p < 0.01) and lens superoxide dismutase (SOD) in group III (p < 0.001) were significantly increased compared to group I. Levels of pro-inflammatory cytokines in aqueous humour revealed significantly (p < 0.001) age-dependent increase in IL-1, IL-6 and TNF-α elevated in group III, and group II as compared to group I, However, cathelicidin level in aqueous humour of group III and group II were significantly (p < 0.001) lower as compared to groups I. Furthermore,the present study observed significant (p < 0.05) metal-metal positive interaction between copper levels in lens with levels of (iron and magnesium) in aqueous humour, levels of Zn in lens with levels of Zn in aqueous humour, levels of Mg in lens with levels of (Cu, Zn and Mg) in aqueous humour. In addition,the present study reports significantly negative interaction between levels of lens Fe with levels of lens magnesium level, aqueous humour magnesium level and levels of copper in aqueous humour. A significantly positive correlation was observed between oxidative markers and pro-inflammatory cytokine levels, while a significant negative correlation was observed between antioxidant defence markers and pro-inflammatory cytokine. These results suggest the essential role of age-related changes in biometal levels, oxidative stress and pro-inflammatory cytokines. These changes might help understand age-related changes in pathogenesis and effective targeting of pathogenetic pathways in ocular diseases.

Trace elements exposure and risk in age-related eye diseases: a systematic review of epidemiological evidence

This systematic review aimed to evaluate existing evidence on the associations between trace elements exposure and age-related eye diseases. PubMed and Google scholar databases were searched for epidemiological and postmortem studies on the relationship between exposure to trace elements and Age-related eye diseases such as age-related macular degeneration (AMD), cataract, glaucoma and diabetic retinopathy (DR), in population groups aged 40 years and above. Available evidence suggests that cadmium (Cd) exposure may be positively associated with the risks of AMD and cataract. There is also evidence that exposure to lead (Pb) may be positively associated with higher risk of cataract and glaucoma. There is limited number of relevant studies and lack of prospective studies for most of the investigated associations. Evidence for other trace elements is weak and inconsistent, and the number of available studies is small. Likewise, there are very few relevant studies on the role of trace elements in DR. Chemical elements that affect the distribution and absorption of other trace elements have never been investigated. The suggestive but limited evidence motivates large and quality prospective studies to fully characterize the impact of exposure to trace (toxic and essential) elements on age-related eye diseases.

Potential of Application of Iron Chelating Agents in Ophthalmic Diseases

The investigations discussed in this review indicate that iron may exacerbate different eye diseases. Therefore, it is plausible that reducing cellular or body iron stores could influence disease pathogenesis, so it is logical to consider the iron chelators' potential protective role in the various ophthalmic diseases in the form of topical eye drops or slow releasing injectable compounds as an adjuvant treatment.

Alzheimer's Disease and Retinal Degeneration: A Glimpse at Essential Trace Metals in Ocular Fluids and Tissues

BACKGROUND

Life expectancy is increasing all over the world, although neurodegenerative disorders might drastically affect the individual activity of aged people. Of those, Alzheimer's Disease (AD) is one of the most social-cost age-linked diseases of industrialized countries. To date, retinal diseases seem to be more common in the developing world and characterize principally aged people. Agerelated Macular Degeneration (AMD) is a late-onset, neurodegenerative retinal disease that shares several clinical and pathological features with AD, including stress stimuli such as oxidative stress, inflammation and amyloid formations.

METHODS

In both diseases, the detrimental intra/extra-cellular deposits have many similarities. Aging, hypercholesterolemia, hypertension, obesity, arteriosclerosis and smoking are risk factors to develop both diseases. Cellular aging routes have similar organelle and signaling patterns in retina and brain. The possibility to find out new research strategies represent a step forward to disclose potential treatment for both of them. Essential trace metals play critical roles in both physiological and pathological condition of retina, optic nerve and brain, by influencing metabolic processes chiefly upon complex multifactorial pathogenesis.

CONCLUSION

Hence, this review addresses current knowledge about some up-to-date investigated essential trace metals associated with AD and AMD. Changes in the levels of systemic and ocular fluid essential metals might reflect the early stages of AMD, possibly disclosing neurodegeneration pathways shared with AD, which might open to potential early detection.

Retinal Degeneration and Alzheimer's Disease: An Evolving Link

Age-related macular degeneration (AMD) and glaucoma are degenerative conditions of the retina and a significant cause of irreversible blindness in developed countries. Alzheimer’s disease (AD), the most common dementia of the elderly, is often associated with AMD and glaucoma. The cardinal features of AD include extracellular accumulation of amyloid β (Aβ) and intracellular deposits of hyper-phosphorylated tau (p-tau). Neuroinflammation and brain iron dyshomeostasis accompany Aβ and p-tau deposits and, together, lead to progressive neuronal death and dementia. The accumulation of Aβ and iron in drusen, the hallmark of AMD, and Aβ and p-tau in retinal ganglion cells (RGC), the main retinal cell type implicated in glaucoma, and accompanying inflammation suggest overlapping pathology. Visual abnormalities are prominent in AD and are believed to develop before cognitive decline. Some are caused by degeneration of the visual cortex, while others are due to RGC loss or AMD-associated retinal degeneration. Here, we review recent information on Aβ, p-tau, chronic inflammation, and iron dyshomeostasis as common pathogenic mechanisms linking the three degenerative conditions, and iron chelation as a common therapeutic option for these disorders. Additionally discussed is the role of prion protein, infamous for prion disorders, in Aβ-mediated toxicity and, paradoxically, in neuroprotection.

Transferrin Non-Viral Gene Therapy for Treatment of Retinal Degeneration

Dysregulation of iron metabolism is observed in animal models of retinitis pigmentosa (RP) and in patients with age-related macular degeneration (AMD), possibly contributing to oxidative damage of the retina. Transferrin (TF), an endogenous iron chelator, was proposed as a therapeutic candidate. Here, the efficacy of TF non-viral gene therapy based on the electrotransfection of pEYS611, a plasmid encoding human TF, into the ciliary muscle was evaluated in several rat models of retinal degeneration. pEYS611 administration allowed for the sustained intraocular production of TF for at least 3 and 6 months in rats and rabbits, respectively. In the photo-oxidative damage model, pEYS611 protected both retinal structure and function more efficiently than carnosic acid, a natural antioxidant, reduced microglial infiltration in the outer retina and preserved the integrity of the outer retinal barrier. pEYS611 also protected photoreceptors from N-methyl-N-nitrosourea-induced apoptosis. Finally, pEYS611 delayed structural and functional degeneration in the RCS rat model of RP while malondialdehyde (MDA) ocular content, a biomarker of oxidative stress, was decreased. The neuroprotective benefits of TF non-viral gene delivery in retinal degenerative disease models further validates iron overload as a therapeutic target and supports the continued development of pEY611 for treatment of RP and dry AMD.

Placental distribution of endogenous and exogenous substances: A pilot study utilizing cryo-sampled specimen off delivery room

INTRODUCTION

Reliability in the use of placentome (including placenta, umbilical cord, and cord blood) biomarkers requires an understanding of their distributions. Here we aim to develop a simple and proper placenta sampling scheme, and to evaluate the placental distributions of biomarkers.

METHODS

We developed a continuous cooling chain protocol off delivery room and cryo-subsampling method for placenta sampling. The levels of thyroid hormones (THs), elements, persistent organic pollutants (POPs), monoamines, and vitamin E were measured using UPLC-Q-TOF-MS, HPLC-ICP-MS, HPLC-EcD, and HRGC-HRMS, respectively. The distributions of biomarkers were assessed.

RESULTS

In human placentome, _l-thyroxine (T₄), Cd, Se, Zn, Cu, Fe, Ca, K, Mg, α-tocopherol, β-tocopherol, and β-tocotrienol levels were higher in placenta than in umbilical cord, while Pb and Mn were concentrated in human cord. In porcine placentome, T₄, 3,3',5'-triiodo-_l-thyronine (rT₃), 3,3'-diiodo-_l-thyronine, Cd, Pb, Zn, K, and Al levels were higher in the cord. The intraclass correlation coefficient (ICC) was <0.4 for 3,3',5-triiodo-_l-thyronine, rT₃, α-tocopherol, and 7 elements in human basal plate, indicating low reliability. rT₃, Cd, Zn, Mn, and Cu were significantly concentrated in the central region in human placenta, while higher levels of As, Cd, Cr, and Al were found in the periphery region in porcine placenta. Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) showed moderate reliability (ICC: 0.40-0.98) except PCB-81, -126, and BDE-208, while polychlorinated dibenzo-p-doixins/furans (PCDD/Fs) showed poor reliability (ICC: 0.07-0.31).

DISCUSSION

These results highlight the complexity of placenta sampling. This study provides a novel and simple sampling approach in investigating placental exposomics.

Characterization of an i.p. D-galactose-induced cataract model in rats

Cataracts have been identified as a main cause of global visual impairment and blindness; in addition, diabetic and aging cataracts are the most common types. The aim of this project was to develop a suitable animal model and investigate the key points of the mechanisms by which intraperitoneal (i.p.) injection of D-galactose forms cataracts. We optimized a method to investigate the safest and effective method and dosage; rats in Group H were treated with 50% D-galactose 15 g/kg i.p. twice daily based on the 11 different treatment methods. The simple oral group showed considerable differences in the same observed time, while the i.p. group showed relatively uniform cataracts due to intake of the same dose of D-galactose. The data suggest that i.p. injection of galactose is a relatively more successful and stable cataract-inducing method with a low mortality rate. Based on this model, we found that Na⁺/K⁺ ratios had important relevance for galactose cataract formation, and we used scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), enzyme-linked immunosorbent assay (ELISA) and immunofluorescence examinations to test and verify this.

Comparison of Methodologies to Estimate Dietary Cadmium Intake in an Italian Population

Cadmium is a metal that is toxic to humans, and the major source of cadmium exposure in the non-smoking general population is diet. To identify major food sources and lower exposure from diet, an accurate estimate of dietary cadmium intake is needed. Hence, the objectives of this study are to develop a method to assess dietary cadmium intake using a biomarker measurement and to improve the estimation of dietary cadmium intake when using a food frequency questionnaire (FFQ). In a random sample of an Italian population, we collected dietary habits by FFQ and measured cadmium in foods and beverages. These data were used to compute the estimated weekly dietary intake (WDI) of cadmium (µg) by kilogram (kg) of body weight (bw) (WDIFFQ). We also measured fasting serum cadmium levels by inductively-coupled plasma mass spectrometry. We used these data to develop a model for the estimation of the biomarker-derived dietary cadmium intake (WDIbio). In the 51 subjects recruited, the median level of serum cadmium was 0.041 µg/L (interquartile range (IQR): 0.030-0.054). The median WDIFFQ and WDIbio were 1.34 µg/kg bw/week (IQR: 0.86-1.70) and 0.72 µg/kg bw/week (IQR: 0.55-1.11), respectively. The correlation between the two estimates was low-to-moderate (r = 0.291). In exploratory analyses, the correlation was slightly higher in women and participants ages <50 years, and markedly higher in participants with body mass index <25 kg/m2 and smokers. Our approach allows for the dietary contribution to be isolated from the overall cadmium exposure measured with a biomarker; the estimated dietary cadmium intake was roughly similar to that estimated using the FFQ, especially in select subgroups. Future refinements to the biomarker-derived dietary cadmium intake approach should take into consideration additional sources of cadmium exposure, as well as factors affecting its absorption and metabolism.

From Rust to Quantum Biology: The Role of Iron in Retina Physiopathology

Iron is essential for cell survival and function. It is a transition metal, that could change its oxidation state from Fe²⁺ to Fe³⁺ involving an electron transfer, the key of vital functions but also organ dysfunctions. The goal of this review is to illustrate the primordial role of iron and local iron homeostasis in retinal physiology and vision, as well as the pathological consequences of iron excess in animal models of retinal degeneration and in human retinal diseases. We summarize evidence of the potential therapeutic effect of iron chelation in retinal diseases and especially the interest of transferrin, a ubiquitous endogenous iron-binding protein, having the ability to treat or delay degenerative retinal diseases.

H2 O2 induces oxidative stress damage through the BMP-6/SMAD/hepcidin axis

Age-related macular degeneration (AMD) is one of the leading causes of blindness in elderly individuals worldwide. Oxidative stress injury to retinal pigment epithelial (RPE) cells plays a major role in the pathogenesis of AMD. The purpose of this study was to observe the correlation between Hepcidin and neovascular age-related macular degeneration (nAMD) and to further observe whether oxidative stress can inhibit Hepcidin expression through relevant signaling pathways to produce oxidative damage. We compared the concentrations of Hepcidin in the aqueous humor of nAMD patients and a control group and found that the concentration of Hepcidin was lower in nAMD patients. Through PCR and western blotting, we observed that H₂ O₂ can significantly inhibit the expression of Bone morphogenetic protein-6 (BMP-6) and Hepcidin and increase the intracellular iron concentration in RPE cells, while BMP-6 can reverse the inhibition of Hepcidin and the increase in iron concentration caused by H₂ O₂ . In addition, alterations in smad1 and smad5 expression were examined, and pretreatment with BMP-6 was demonstrated to reduce H₂ O₂ -induced activation of smad1 and smad5. The effects of BMP-6 were attenuated by smad1 and smad5 siRNA, further verifying that oxidative stress inhibits the expression of Hepcidin by inhibiting activation of the BMP/SMAD signaling pathway. To some extent, this study verified that oxidative stress injury plays a role in nAMD by affecting the level of hepcidin, which lays a foundation for exploring new methods to treat nAMD.

Levels of Trace Elements in the Aqueous Humor of Cataract Patients Measured by the Inductively Coupled Plasma Optical Emission Spectrometry

Trace elements play an important role in the pathogenesis of several serious ophthalmological disorders, such as glaucoma, age-related macular degeneration (AMD), diabetic retinopathy, cataract, etc. This study aimed to measure alterations of chemical elements' (67) levels in the aqueous humor of patients undergoing cataract surgery. The pilot study included 115 patients, (age 74 ± 7.27, female 64.35%, male 35.65%). The aqueous levels of elements were measured by the use of the inductively coupled plasma optical emission spectrometry (ICP-OES), quality controlled with certified standards. The classification of elements based on their concentration was achieved by hierarchical cluster analysis. This is the first screening study that quantifies over 60 elements which are present in the fluid from the anterior chamber of the eye of cataract patients. The obtained results can be suitable for understanding and identifying the causes that may play a role in the initiation and progression of lens opacity.

Pilot study of homeostatic alterations of mineral elements in serum of patients with age-related macular degeneration via elemental and isotopic analysis using ICP-mass spectrometry

Age-related macular degeneration (AMD), the main cause of irreversible blindness in people over 60 years of age, is an eye disease that evolves with loss of central vision. Although AMD manifests itself in the eye, blood is continuously flowing through the macular region, such that potential alterations in this region could be reflected in the composition of whole blood or plasma/serum. Therefore, the potential clinical relevance of analysis of serum samples was assessed because of the low degree of invasiveness of blood sampling. 40 initial samples (20 from controls and 20 from patients with the dry form of AMD) have been analysed in this work to investigate the possible occurrence of homeostatic alterations of essential mineral elements caused by the disease. Both major (Na, Mg, P and K) and trace (Fe, Cu and Zn) essential mineral elements were determined in blood serum using single-collector ICP-mass spectrometry. Also, the isotopic composition of Cu (an element proposed to be directly involved in the onset of AMD) was determined using multi-collector ICP-mass spectrometry. Unexpected light Cu isotopic compositions in three individuals assumed as controls, resulted in a re-evaluation of their clinical information and a later exclusion due to pathologies initially not accounted for. In this pilot study, a significant alteration in the δ⁶⁵Cu value has been found between the two final cohorts (AMD patients: n = 20; controls n = 17), with lower δ⁶⁵Cu values (i.e. an enrichment in the light ⁶³Cu isotope) in the case of AMD. Also, higher serum concentrations of the elements P and Zn were established in AMD at a systemic level.

Abnormal levels of aqueous humor trace elements in patients with cytomegalovirus retinitis

PURPOSE

To investigate the alterations of trace elements levels in aqueous humor of patients with cytomegalovirus retinitis (CMVR).

METHODS

A total of 15 eyes of 11 patients with CMVR and 24 eyes of 24 patients with senile cataract as control group were enrolled. Aqueous humor samples were assessed for calcium (Ca), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), selenium (Se), strontium (Sr), and lead (Pb) by using inductively coupled-plasma-mass-spectrometry. Meanwhile, we examined the concentration of the CMV DNA load by using PCR and the concentration of interleukin (IL)-8 by using a cytometric bead array.

RESULTS

In patients with CMVR, the aqueous humor levels of P and Cu were significantly higher than those of controls (p < 0.001, p < 0.001, respectively). However, levels of K and Mg were significantly lower in patients with CMVR (p < 0.001, p < 0.001, respectively). The Spearman correlation test showed that the concentration of IL-8 in the aqueous humor was significantly associated with the aqueous level of Cu (p = 0.009, r = 0.646) and Se (p = 0.031, r = 0.558). In addition, the concentration of CMV DNA load in the aqueous humor was significantly associated with the aqueous level of Ca (p = 0.027, r = -0.568), Mn (p = 0.020, r = 0.593), and Cu (p = 0.043, r = 0.527).

CONCLUSIONS

Our preliminary results demonstrated that the abnormal aqueous levels of trace elements (P and Cu) in CMVR patients. Thus, the roles of trace element changes in the development of CMVR and the influence of intraocular trace element for the prognosis of CMVR warrant further investigations.

Potential Treatment of Retinal Diseases with Iron Chelators

Iron is essential for life, while excess iron can be toxic. Iron generates hydroxyl radical, which is the most reactive free radical, causing oxidative stress. Since iron is absorbed through the diet but not excreted from the body, it accumulates with age in tissues, including the retina, consequently leading to age-related toxicity. This accumulation is further promoted by inflammation. Hereditary diseases such as aceruloplasminemia, Friedreich’s ataxia, pantothenate kinase-associated neurodegeneration, and posterior column ataxia with retinitis pigmentosa involve retinal degeneration associated with iron dysregulation. In addition to hereditary causes, dietary or parenteral iron supplementation has been recently reported to elevate iron levels in the retinal pigment epithelium (RPE) and promote retinal degeneration. Ocular siderosis from intraocular foreign bodies or subretinal hemorrhage can also lead to retinopathy. Evidence from mice and humans suggests that iron toxicity may contribute to age-related macular degeneration pathogenesis. Iron chelators can protect photoreceptors and RPE in various mouse models. The therapeutic potential for iron chelators is under investigation.

Oxidative stress induces ferroptotic cell death in retinal pigment epithelial cells

The dysfunction and cell death of retinal pigment epithelial (RPE) cells are hallmarks of late-stage dry (atrophic) age-related macular degeneration (AMD), for which no effective therapy has yet been developed. Previous studies have indicated that iron accumulation is a source of excess free radical production in RPE, and age-dependent iron accumulation in RPE is accelerated in patients with dry AMD. Although the pathogenic role of oxidative stress in RPE in the development of dry AMD is widely accepted, the mechanisms of oxidative stress-induced RPE cell death remain elusive. Here, we show that ferroptotic cell death, a mode of regulated necrosis mediated by iron and lipid peroxidation, is implicated in oxidative stress-induced RPE cell death in vitro. In ARPE-19 cells we observed that the ferroptosis inhibitors ferrostatin-1 and deferoxamine (DFO) rescued tert-butyl hydroperoxide (tBH)-induced RPE cell death more effectively than inhibitors of apoptosis or necroptosis. tBH-induced RPE cell death was accompanied by the three characteristics of ferroptotic cell death: lipid peroxidation, glutathione depletion, and ferrous iron accumulation, which were all significantly attenuated by ferrostatin-1 and DFO. Exogenous iron overload enhanced tBH-induced RPE cell death, but this effect was also attenuated by ferrostatin-1 and DFO. Furthermore, mRNA levels of numerous genes known to regulate iron metabolism were observed to be influenced by oxidative stress. Taken together, our observations suggest that multiple modes of cell death are involved in oxidative stress-induced RPE cell death, with ferroptosis playing a particularly important role.

Blood lead and cadmium in age related macular degeneration in a Turkish urban population

PURPOSE

To evaluate the blood lead (Pb) and cadmium (Cd) levels in age related macular degeneration (AMD) in a turkish urban population.

METHODS

Blood Pb and Cd levels of 31 AMD patients and 24 age and gender matched controls with no sign of AMD were measured using dual atomic absorption spectrophotometer system (AAS). History of hypertension, diabetes mellitus, cigarette smoking, myocardial infarction and stroke were obtained from all subjects. Degree of AMD was grade 4 according to the Age-Related Eye Disease Study grading system. Median blood Pb and Cd levels were compared by using Students' t-test.

RESULTS

Demographic properties like smoking status, presence of diabetes mellitus or hypertension, cerebrovascular occlusion history, serum cholesterol and lipid levels were not significantly different between groups except history of ischemic heart disease (3.22% vs 25% in AMD and control groups respectively, p = .022). Overall in AMD group blood Pb level was 2.83 ± 0.15 μg/l and it was 2.63 ± 0.23 μg/l in control group (p = .36). The Cd level was 3.25 ± 0.20 μg/l in AMD group and 3.11 ± 0.25 μg/l in control group (p = .67). The mean Pb (2.38 ± 0.88 μg/l vs 2.91 ± 1.37 μg/l for AMD vs control, p = .61) and Cd levels (3.06 ± 1.34 μg/l vs 3.35 ± 1.26 μg/l for AMD vs control, p = .56) in current and previous smokers with AMD were not significantly different from those of the current and previous smokers in control group.

CONCLUSION

Blood Pb and Cd levels which reflect short term exposure were not significantly different in AMD patients and the control group. The difference was not significant either after involvement of previous or current smoker subjects.

Lead, cadmium and mercury in cerebrospinal fluid and risk of amyotrophic lateral sclerosis: A case-control study

Exposure to neurotoxic chemicals such as pesticides, selenium, and heavy metals have been suggested to play a role in the etiology of amyotrophic lateral sclerosis (ALS). We assessed exposure to lead, cadmium, and mercury in 38 ALS patients (16 men and 22 females) and 38 hospital-admitted controls by using their cerebrospinal fluid (CSF) content as biomarker. We determined CSF heavy metal levels with inductively coupled plasma sector field mass spectrometry, according to a methodology specifically developed for this biological matrix. ALS patients had higher median values for Pb (155 vs. 132ng/L) but lower levels for Cd (36 vs. 72ng/L) and Hg (196 vs. 217ng/L). In the highest tertile of exposure, ALS odds ratio was 1.39 (95% CI 0.48-4.25) for Pb, 0.29 (0.08-1.04) for Cd and 3.03 (0.52-17.55) for Hg; however, no dose-response relation emerged. Results were substantially confirmed after conducting various sensitivity analyses, and after stratification for age and sex. Though interpretation of these results is limited by the statistical imprecision of the estimates, and by the possibility that CSF heavy metal content may not reflect long-term antecedent exposure, they do not lend support to a role of the heavy metals cadmium, lead and mercury in ALS etiology.

Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration

Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice.

Determinants of serum manganese levels in an Italian population

Manganese (Mn) is both essential and toxic for humans, mainly depending on the total levels and its species. Main sources of exposure include food and air pollution, particularly motorized traffic. We sought to determine the potential influence of these sources on serum total levels of Mn and Mn species. We selected a random sample of municipality residents from an Italian urban municipality, from whom we collected detailed personal information, dietary habits and a blood sample for serum Mn determination. We also assessed outdoor air Mn exposure, by modeling levels of particulate matter ≤10 µm (PM10) from motorized traffic at the residence of geocoded subjects. Serum Mn species generally showed higher levels in males and positive correlation with age, while no such differences were found according to smoking habits or use of dietary supplements. Among nutrients, only iron intake showed a relation with Mn [an inverse correlation with Mn‑ferritin (Mn‑Fer) and a direct one with inorganic‑Mn (Inorg‑Mn)]. Meat consumption directly correlated and fish and seafood inversely correlated with total Mn, Mn‑transferrin (Mn‑Tf) and Mn-citrate (Mn-Cit). Fruits and vegetables, including legumes and nuts, generally showed a positive correlation with all Mn species, especially Mn‑Cit, and an inverse one with Inorg‑Mn. Odds ratios (ORs) of having serum Mn levels above median value increased with increasing PM10 tertiles, with an OR for highest‑to‑lowest tertile of 7.40 (1.36‑40.25) in multivariate analysis. Analyses for Mn species did not highlight a clear comparable pattern. In conclusion, our results seem to demonstrate that PM10 exposure positively influences total Mn serum levels, while single Mn species show conflicting results.

Cadmium and lead exposure and risk of cataract surgery in U.S. adults

Cataract is a major cause of visual dysfunction and the leading cause of blindness. Elevated levels of cadmium and lead have been found in the lenses of cataract patients, suggesting these metals may play a role in cataract risk. This study aimed to examine the associations of blood lead, blood cadmium and urinary cadmium with cataract risk. We identified 9763 individuals aged 50 years and older with blood lead and cadmium levels, and a randomly selected subgroup of 3175 individuals with available urinary cadmium levels, from the National Health and Nutrition Examination Surveys (NHANES) from 1999 to 2008 (mean age=63years). Participants were considered to have cataract if they self-reported prior cataract surgery in NHANES's vision examination. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using survey logistic regression models. We identified 1737 cataract surgery cases (the weighted prevalence=14.1%). With adjustment for age, race/ethnicity, gender, education, diabetes mellitus, body mass index, cigarette smoking (serum cotinine and pack-years) and urine hydration, every 2-fold increase in urinary cadmium was associated with a 23% higher risk of cataract surgery (OR=1.23, 95% CI: 1.04, 1.46, p=0.021). We found no associations of cataract surgery with blood cadmium (OR=0.97, 95% CI: 0.89, 1.07) and blood lead (OR=0.97, 95% CI: 0.88, 1.06). Mediation analysis showed that for the smoking-cadmium-cataract pathway, the ratio of smoking's indirect effect to the total effect through cadmium was more than 50%. These results suggest that cumulative cadmium exposure may be an important under-recognized risk factor for cataract. However, these findings should be interpreted with a caution because of inconsistent results between urinary cadmium and blood cadmium.

Determinants of serum cadmium levels in a Northern Italy community: A cross-sectional study

INTRODUCTION

Cadmium (Cd) is a heavy metal and a serious environmental hazard to humans. Some uncertainties still exist about major sources of Cd exposure in non-occupationally exposed subjects in addition to cigarette smoking, such as diet and outdoor air pollution. We sought to determine the influence of these sources on a biomarker of exposure, serum Cd concentration.

METHODS

We recruited 51 randomly selected residents from an Italian urban community, from whom we obtained detailed information about dietary habits and smoking habits, and a blood sample for serum Cd determination. We also assessed outdoor air Cd exposure, by modeling outdoor air levels of particulate matter ≤10µm (PM10) from motorized traffic at geocoded subjects' residence.

RESULTS

In crude analysis, regression beta coefficients for dietary Cd, smoking and PM10 on serum Cd levels were 0.03 (95% CI -0.83 to 0.88), 6.96 (95% CI -0.02 to 13.95) and 0.62 (95% CI -0.19 to 1.43), respectively. In the adjusted analysis, regression beta coefficients were -0.34 (95% CI -1-40 to 0.71), 5.81 (95% CI -1.43 to 13.04) and 0.47 (95% CI -0.35 to 1.29), respectively.

CONCLUSION

Cigarette smoking was the most important factor influencing serum Cd in our non-occupationally exposed population, as expected, while dietary Cd was not associated with this biomarker. Outdoor air pollution, as assessed through exposure to particulate matter generated by motorized traffic, was an additional source of Cd exposure.

Age and Smoking Related Changes in Metal Ion Levels in Human Lens: Implications for Cataract Formation

Age-related cataract formation is the primary cause of blindness worldwide and although treatable by surgical removal of the lens the majority of sufferers have neither the finances nor access to the medical facilities required. Therefore, a better understanding of the pathogenesis of cataract may identify new therapeutic targets to prevent or slow its progression. Cataract incidence is strongly correlated with age and cigarette smoking, factors that are often associated with accumulation of metal ions in other tissues. Therefore this study evaluated the age-related changes in 14 metal ions in 32 post mortem human lenses without known cataract from donors of 11 to 82 years of age by inductively coupled plasma mass spectrometry; smoking-related changes in 10 smokers verses 14 non-smokers were also analysed. A significant age-related increase in selenium and decrease in copper ions was observed for the first time in the lens tissue, where cadmium ion levels were also increased as has been seen previously. Aluminium and vanadium ions were found to be increased in smokers compared to non-smokers (an analysis that has only been carried out before in lenses with cataract). These changes in metal ions, i.e. that occur as a consequence of normal ageing and of smoking, could contribute to cataract formation via induction of oxidative stress pathways, modulation of extracellular matrix structure/function and cellular toxicity. Thus, this study has identified novel changes in metal ions in human lens that could potentially drive the pathology of cataract formation.

Targeting iron-mediated retinal degeneration by local delivery of transferrin

Iron is essential for retinal function but contributes to oxidative stress-mediated degeneration. Iron retinal homeostasis is highly regulated and transferrin (Tf), a potent iron chelator, is endogenously secreted by retinal cells. In this study, therapeutic potential of a local Tf delivery was evaluated in animal models of retinal degeneration. After intravitreal injection, Tf spread rapidly within the retina and accumulated in photoreceptors and retinal pigment epithelium, before reaching the blood circulation. Tf injected in the vitreous prior and, to a lesser extent, after light-induced retinal degeneration, efficiently protected the retina histology and function. We found an association between Tf treatment and the modulation of iron homeostasis resulting in a decrease of iron content and oxidative stress marker. The immunomodulation function of Tf could be seen through a reduction in macrophage/microglial activation as well as modulated inflammation responses. In a mouse model of hemochromatosis, Tf had the capacity to clear abnormal iron accumulation from retinas. And in the slow P23H rat model of retinal degeneration, a sustained release of Tf in the vitreous via non-viral gene therapy efficently slowed-down the photoreceptors death and preserved their function. These results clearly demonstrate the synergistic neuroprotective roles of Tf against retinal degeneration and allow identify Tf as an innovative and not toxic therapy for retinal diseases associated with oxidative stress.

Bacterial polysaccharide levan as stabilizing, non-toxic and functional coating material for microelement-nanoparticles

Levan, fructose-composed biopolymer of bacterial origin, has potential in biotechnology due to its prebiotic and immunostimulatory properties. In this study levan synthesized by levansucrase from Pseudomonas syringae was thoroughly characterized and used as multifunctional biocompatible coating material for microelement-nanoparticles (NPs) of selenium, iron and cobalt. Transmission electron microscopy (TEM), hydrodynamic size measurements (DLS) and X-ray photoelectron spectroscopy (XPS) showed the interaction of levan with NPs. Levan stabilized the dispersions of NPs, decreased their toxicity and had protective effect on human intestinal cells Caco-2. In addition, levan attached to cobalt NPs remained accessible as a substrate for the colon bacteria Bacteroides thetaiotaomicron. We suggest that the combination of levan and nutritionally important microelements in the form of NPs serves as a first step towards a novel "2 in 1" approach for food supplements to provide safe and efficient delivery of microelements for humans and support beneficial gut microbiota with nutritional oligosaccharides.

Association between Blood Lead Levels and Age-Related Macular Degeneration

Purpose

To investigate the association between blood lead levels and prevalence of age-related macular degeneration (AMD).

Methods

A nationwide population-based cross-sectional study included 4,933 subjects aged over 40 years who participated in the 2008–2012 Korean National Health and Nutrition Examination Survey, and for whom fundus photographs were available. All participants underwent a standardized interview, evaluation of blood lead concentration, and a comprehensive ophthalmic examination. Digital fundus photographs (45°) were taken of both eyes under physiological mydriasis. All fundus photographs were graded using an international classification and grading system.

Results

Mean blood lead levels were 3.15 μg/dL in men and 2.27 μg/dL in women (P < 0.001). After adjusting for potential confounders including age, gender, smoking status, total cholesterol levels, triglyceride levels, heart problems and strokes, the adjusted odds ratio (OR) in women for any AMD was 1.86 (95% Confidence Interval [CI], 1.03–3.36) and for early AMD was 1.92 (95% CI, 1.06–3.48), for those in the highest quintile of lead level compared with the lowest quintile. In men, however, blood lead level was not significantly associated with AMD.

Conclusions

Blood lead levels were higher in men, but were only associated with AMD in women. Increased levels of blood lead may be involved in the pathogenesis of AMD development in women.

Iron Toxicity in the Retina Requires Alu RNA and the NLRP3 Inflammasome

Excess iron induces tissue damage and is implicated in age-related macular degeneration (AMD). Iron toxicity is widely attributed to hydroxyl radical formation through Fenton's reaction. We report that excess iron, but not other Fenton catalytic metals, induces activation of the NLRP3 inflammasome, a pathway also implicated in AMD. Additionally, iron-induced degeneration of the retinal pigmented epithelium (RPE) is suppressed in mice lacking inflammasome components caspase-1/11 or Nlrp3 or by inhibition of caspase-1. Iron overload increases abundance of RNAs transcribed from short interspersed nuclear elements (SINEs): Alu RNAs and the rodent equivalent B1 and B2 RNAs, which are inflammasome agonists. Targeting Alu or B2 RNA prevents iron-induced inflammasome activation and RPE degeneration. Iron-induced SINE RNA accumulation is due to suppression of DICER1 via sequestration of the co-factor poly(C)-binding protein 2 (PCBP2). These findings reveal an unexpected mechanism of iron toxicity, with implications for AMD and neurodegenerative diseases associated with excess iron.

Role of antioxidant enzymes and small molecular weight antioxidants in the pathogenesis of age-related macular degeneration (AMD)

Cells in aerobic condition are constantly exposed to reactive oxygen species (ROS), which may induce damage to biomolecules, including proteins, nucleic acids and lipids. In normal circumstances, the amount of ROS is counterbalanced by cellular antioxidant defence, with its main components—antioxidant enzymes, DNA repair and small molecular weight antioxidants. An imbalance between the production and neutralization of ROS by antioxidant defence is associated with oxidative stress, which plays an important role in the pathogenesis of many age-related and degenerative diseases, including age-related macular degeneration (AMD), affecting the macula—the central part of the retina. The retina is especially prone to oxidative stress due to high oxygen pressure and exposure to UV and blue light promoting ROS generation. Because oxidative stress has an established role in AMD pathogenesis, proper functioning of antioxidant defence may be crucial for the occurrence and progression of this disease. Antioxidant enzymes play a major role in ROS scavenging and changes of their expression or/and activity are reported to be associated with AMD. Therefore, the enzymes in the retina along with their genes may constitute a perspective target in AMD prevention and therapy.

Retinal iron homeostasis in health and disease

Iron is essential for life, but excess iron can be toxic. As a potent free radical creator, iron generates hydroxyl radicals leading to significant oxidative stress. Since iron is not excreted from the body, it accumulates with age in tissues, including the retina, predisposing to age-related oxidative insult. Both hereditary and acquired retinal diseases are associated with increased iron levels. For example, retinal degenerations have been found in hereditary iron overload disorders, like aceruloplasminemia, Friedreich's ataxia, and pantothenate kinase-associated neurodegeneration. Similarly, mice with targeted mutation of the iron exporter ceruloplasmin and its homolog hephaestin showed age-related retinal iron accumulation and retinal degeneration with features resembling human age-related macular degeneration (AMD). Post mortem AMD eyes have increased levels of iron in retina compared to age-matched healthy donors. Iron accumulation in AMD is likely to result, in part, from inflammation, hypoxia, and oxidative stress, all of which can cause iron dysregulation. Fortunately, it has been demonstrated by in vitro and in vivo studies that iron in the retinal pigment epithelium (RPE) and retina is chelatable. Iron chelation protects photoreceptors and retinal pigment epithelial cells (RPE) in a variety of mouse models. This has therapeutic potential for diminishing iron-induced oxidative damage to prevent or treat AMD.