Effectiveness of iron repletion in the diet for the optic nerve development of anaemic rats

Effects of hemoglobin concentration on retinochoroidal vascular plexuses: an optical coherence tomography angiography study

PURPOSE

To evaluate retinal and choroidal microvascular structures using optical coherence tomography angiography (OCTA) in patients with anemia and polycythemia vera (PV).

METHODS

In this prospective study, 142 patients (142 eyes) were enrolled and divided into 3 groups: the anemia (n = 56), PV (n = 46), and healthy groups (n = 40, controls). For each patient, 6- × 6-mm macular angiography images were taken using an OCTA system (optovue, Inc., Fremont). For each eye analyzed, the software automatically measured vessel density (VD) in the superficial capillary plexus (SCP), deep capillary plexus (DCP; superior, nasal, temporal, and inferior quadrants), choriocapillaris (CC), and foveal avascular zone (FAZ).

RESULTS

The OCTA analysis revealed that the VD of the DCP was significantly decreased in the superior and inferior hemispheres of the whole area, multiple quadrants of the perifovea, and CC with a 1-mm2 flow area in the anemia group compared with the PV group (p < 0.017), but the VD of the SCP did not show any significant difference in any quadrant between the two groups (p > 0.017). When compared with the healthy group, the anemia and PV groups showed a significant difference in multiple quadrants of the parafovea and temporal quadrant of the perifovea in the VD of the SCP and CC with a 2-mm2 flow area (p < 0.017). The FAZ and non-flow area did not manifest any significant difference between the groups (p > 0.017). The hemoglobin concentrations in the anemia, PV, and healthy groups were 8.11 ± 1.33, 17.5 ± 1.2, and 15.6 ± 0.73 g/dL, respectively, indicating statistically significant differences between the groups (p < 0.001).

CONCLUSION

In this study, quantitative OCTA analysis revealed a higher tendency for retinal and choroidal microvascular morphological changes in patients with anemia and PV. The outcomes of the current investigation can provide new insights into the retinal and choroidal pathophysiologies found in patients with hemoglobin abnormalities.

Brain Iron Metabolism, Redox Balance and Neurological Diseases

The incidence of neurological diseases, such as Parkinson's disease, Alzheimer's disease and stroke, is increasing. An increasing number of studies have correlated these diseases with brain iron overload and the resulting oxidative damage. Brain iron deficiency has also been closely linked to neurodevelopment. These neurological disorders seriously affect the physical and mental health of patients and bring heavy economic burdens to families and society. Therefore, it is important to maintain brain iron homeostasis and to understand the mechanism of brain iron disorders affecting reactive oxygen species (ROS) balance, resulting in neural damage, cell death and, ultimately, leading to the development of disease. Evidence has shown that many therapies targeting brain iron and ROS imbalances have good preventive and therapeutic effects on neurological diseases. This review highlights the molecular mechanisms, pathogenesis and treatment strategies of brain iron metabolism disorders in neurological diseases.

Infantile Iron Deficiency Affects Brain Development in Monkeys Even After Treatment of Anemia

A high percent of oxidative energy metabolism is needed to support brain growth during infancy. Unhealthy diets and limited nutrition, as well as other environmental insults, can compromise these essential developmental processes. In particular, iron deficiency anemia (IDA) has been found to undermine both normal brain growth and neurobehavioral development. Even moderate ID may affect neural maturation because when iron is limited, it is prioritized first to red blood cells over the brain. A primate model was used to investigate the neural effects of a transient ID and if deficits would persist after iron treatment. The large size and postnatal growth of the monkey brain makes the findings relevant to the metabolic and iron needs of human infants, and initiating treatment upon diagnosis of anemia reflects clinical practice. Specifically, this analysis determined whether brain maturation would still be compromised at 1 year of age if an anemic infant was treated promptly once diagnosed. The hematology and iron status of 41 infant rhesus monkeys was screened at 2-month intervals. Fifteen became ID; 12 met clinical criteria for anemia and were administered iron dextran and B vitamins for 1-2 months. MRI scans were acquired at 1 year. The volumetric and diffusion tensor imaging (DTI) measures from the ID infants were compared with monkeys who remained continuously iron sufficient (IS). A prior history of ID was associated with smaller total brain volumes, driven primarily by significantly less total gray matter (GM) and smaller GM volumes in several cortical regions. At the macrostructual level, the effect on white matter volumes (WM) was not as overt. However, DTI analyses of WM microstructure indicated two later-maturating anterior tracts were negatively affected. The findings reaffirm the importance of iron for normal brain development. Given that brain differences were still evident even after iron treatment and following recovery of iron-dependent hematological indices, the results highlight the importance of early detection and preemptive supplementation to limit the neural consequences of ID.

Association Between PM2.5 Exposure Level and Primary Open-Angle Glaucoma in Taiwanese Adults: A Nested Case-Control Study

Primary open-angle glaucoma (POAG) is the most common type of glaucoma. However, little is known about POAG in adults and exposure to air pollution. The current study aims to investigate whether exposure to particulate matter with a mass median aerodynamic diameter of ≤2.5 μm (PM_2.5) is associated with POAG diagnosis. Patient data were obtained from the Longitudinal Health Insurance Database 2010 (LHID2010) of Taiwan for the 2008–2013 period. PM_2.5 concentration data, collected from the Ambient Air Quality Monitoring Network established by the Environmental Protection Administration of Taiwan, were categorized into four groups according to World Health Organization (WHO) exposure standards for PM_2.5. We estimated the odds ratios (ORs) and 95% CIs for risk factors for POAG with logistic regression. The OR of per WHO standard level increase was 1.193 (95% CI 1.050–1.356). Compared with the normal level, the OR of WHO 2.0 level was 1.668 (95% CI 1.045–2.663, P < 0.05). After excluding confounding risk factors for POAG in this study, we determined that increased PM_2.5 exposure is related to POAG risk (ORs > 1, P < 0.05). In this study, PM_2.5 was an independent factor associated with open-angle glaucoma. Further research is required to better understand the mechanisms connecting PM_2.5 and open-angle glaucoma.

Neonatal tactile stimulation reverses alterations in fine structure of small, but not large myelinated fibers, from the optic nerve of iron-deficient rats: A size-based selectivity

Iron is the most common micronutrient deficiency in the world and it is most prevalent in young children, exposing their developing brain to inadequate iron levels. The damage related to neuroanatomical parameters is not reversed after iron treatment. However, evidence suggest that tactile stimulation (TS) may offer great therapeutic efficacy in cases of nutritional disorders postnatally, since the brain is remarkably responsive to its interaction with the environment. Recently, we shown that neonatal iron deficient rats achieved some remedial effect by exposing them to TS treatment early in life, reinforcing the fact that the TS approach is a positive enriching experience, therefore, here we ask whether exposure to TS treatment, could also be employed to prevent fine structural changes in the fibers from optic nerve of rats maintained on an iron-deficient diet during brain development. To elucidate the protective effect of tactile stimulation, our methods resulted in 10,859 analyzed fibers, divided into small and large fibers. We found that iron deficiency led to a decreased axon, fiber and myelin size of small fibers, however, TS completely reversed the iron-decifiency-induced alteration on those fiber measurements. Large fibers were disproportionately affected by iron deficiency and there was no remediating effect due to tactile stimulation treatment. The present study adds new information regarding different alterations between small and large fibers due to diet and TS, which suggest a size-based selectivity. These results emphasize the concept that compromised brain development can be mitigated at an early age by environmental factors, such as tactile stimulation.

Evaluation of Iron Deficiency Anemia Frequency as a Risk Factor in Glaucoma

Purpose

Iron deficiency anemia is an important public health problem. Also it is considered to be a risk factor for many diseases. The study demonstrates the iron deficiency anemia frequency in glaucoma patients and compares with the normal subjects. We aimed to determine the iron deficiency anemia frequency in glaucoma patients.

Methods

Prospective, controlled study in a single university hospital setting. A total of 130 normal subjects (Group 1) and 131 glaucoma patients (Group 2) were included. The erythrocytes parameters, hemoglobin, red blood cell, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, and red blood cell distribution width, and iron status indicators, Fe (iron), total iron binding capacity, and ferritin of the cases, in normal subjects and glaucoma patients were compared.

Results

There was no statistically significant difference for the erythrocyte parameters between the groups (p≥0.05). The number of the patients with iron deficiency anemia in both groups was similar. No statistically significant difference was found in the comparison of erythrocyte parameters and iron status indicators values according to the number of antiglaucomatous agents and visual field changes according to the presence of anemia in Group 2 (p≥0.05). A statistically significant difference was found only in MCH when the erythrocyte parameters and iron status indicators values of the cases in glaucoma patients were compared with the glaucoma duration (p<0.05).

Conclusion

The iron deficiency anemia frequency was like the normal population in glaucoma patients.

67Ga as a biosensor of iron needs in different organs: Study performed on male and female rats subjected to iron deficiency and exercise

The aim of the present study was to determine the iron needs in different organs and tissues using ⁶⁷Ga as a biosensor in males and females rats subjected to iron deficiency (ID) and voluntary exercise (EX). ⁶⁷Ga citrate was injected i.p. to female and male Wistar rats (n=5/sex/group). Groups: Control (sedentary conditions), Control+EX, ID and ID+EX. To determine the ⁶⁷Ga uptake, samples from the following regions of interest (ROIs) were extracted 12h post-injection: blood, liver, gonads, bone marrow, heart, adrenal glands, skeletal muscle, stomach, kidney, eyeball, sciatic nerve, small intestine and peritoneum. The total ⁶⁷Ga uptake was 412% higher in ID subjects than in control subjects, being 1011% higher in ID-males than ID-females. In ID-females, the ROIs with the greater ⁶⁷Ga uptake were blood, kidney and bone marrow, while in ID-males they were sciatic nerve, eyeball and adrenals, which demonstrates that the biodistribution differed between sexes in sedentary conditions but when subjected to EX, the biodistribution was similar in each sex group although females had a greater ⁶⁷Ga uptake. In ID+EX subjects, the ROIs that showed the highest uptake were sciatic nerve, eyeball and adrenal glands. Using ⁶⁷Ga as a biosensor, it is possible to identify the needs of iron that each organ requires to perform their functions in normal physiological conditions. In addition, a higher or lower ⁶⁷Ga uptake in a specific organ may indicate its malfunction or show damage.

Peripapillary retinal nerve fiber layer thickness in patients with iron deficiency anemia

Purpose:

To evaluate the effect of iron deficiency anemia (IDA) on peripapillary retinal nerve fiber layer (RNFL) thickness with optical coherence tomography (OCT).

Materials and Methods:

102 female patients who had IDA (hemoglobin <12 g/dl, serum transferrin saturation <15%, serum iron <50 μg/dl, and serum ferritin <15 μg/dl) were enrolled in the study. Optic disc and RNFL parameters obtained by Cirrus high-definition OCT 4000 were compared with those of 49 age and sex-matched nonanemic individuals. The time between blood analysis and OCT measurements was 3.14 ± 5.6 (range, 0–28) days in the anemia group, and 3.5 ± 6.7 (range, 0–27) days in the control group (P = 0.76).

Results:

Average ages of 102 patients and 49 control subjects were 35.76 ± 10.112 (range, 18–66) years, and 36.08 ± 8.416 (range, 19–57) years (P = 0.850), respectively. The average RNFL thickness was 94.67 ± 9.380 in the anemia group, and 100.22 ± 9.12 in the control group (P = 0.001). Temporal, nasal, and lower quadrant average RNFL thicknesses of IDA group were thinner than the control group (P = 0.001, P = 0.013, P = 0.008). Upper quadrant RNFL thicknesses in IDA and control groups were similar. Correlation analysis revealed positive correlation between mean RNFL thickness and hemoglobin (r = 0.273), iron (r = 0.177), ferritin (r = 0.163), and transferrin saturations (r = 0.185), while a negative correlation was found between total iron binding capacity (r = −0.199) and mean RNFL thickness.

Conclusions:

Peripapillary RNFL thickness measured by OCT is thinner in adult female patients with IDA. It may have a significant influence on the management of many disorders such as glaucoma and neuro-ophthalmological diseases.

Flaxseed used since pregnancy by the mother and after weaning by the offspring benefits the retina and optic nerve development in rats

OBJECTIVE

This study aimed to evaluate the influence of a diet based on flaxseed upon the development of the nervous system, more specifically, the optic nerve and retina.

METHODS

Rats were divided into three groups: Control (CG), Flaxseed (FG), and Modified Control (MCG). The analyses were performed in the offspring (n = 6/group) at the immediate postnatal period (P0), 14 d of life (P14) and 30 d of life (P30). Descriptive analysis and histomorphometry of optic nerve and retina were performed.

RESULTS

There was a great evolution in the development of the nervous fascicles, connective trabeculae, and blood vessels, when comparing the three ages studied, and these characteristics were more evident in FG at all three ages. The P0, P14, and P30 retina showed similar morphology to that described in the literature. In histomorphometry, at P14, the FG presented the retina and its layers with significant increase in thickness, except for internal granular and ganglionar, whereas MCG had greater retina and photoreceptor layers thickness, inner plexiform and external granular when compared with CG (p < .05).

CONCLUSION

The use of flaxseed in the pre-and postnatal period displays favourable influence on the development of rat optic nerve and retina, probably leading to myelination.

Tactile stimulation partially prevents neurodevelopmental changes in visual tract caused by early iron deficiency

Iron deficiency has a critical impact on maturational mechanisms of the brain and the damage related to neuroanatomical parameters is not satisfactorily reversed after iron replacement. However, emerging evidence suggest that enriched early experience may offer great therapeutic efficacy in cases of nutritional disorders postnatally, since the brain is remarkably responsive to its interaction with the environment. Given the fact that tactile stimulation (TS) treatment has been previously shown to be an effective therapeutic approach and with potential application to humans, here we ask whether exposure to TS treatment, from postnatal day (P) 1 to P32 for 3min/day, could also be employed to prevent neuroanatomical changes in the optic nerve of rats maintained on an iron-deficient diet during brain development. We found that iron deficiency changed astrocyte, oligodendrocyte, damaged fiber, and myelinated fiber density, however, TS reversed the iron-deficiency-induced alteration in oligodendrocyte, damaged fiber and myelinated fiber density, but failed to reverse astrocyte density. Our results suggest that early iron deficiency may act by disrupting the timing of key steps in visual system development thereby modifying the normal progression of optic nerve maturation. However, optic nerve development is sensitive to enriching experiences, and in the current study we show that this sensitivity can be used to prevent damage from postnatal iron deficiency during the critical period.

Protective effect of etanercept, an inhibitor of tumor necrosis factor-α, in a rat model of retinal ischemia

BACKGROUND

To assess the neuroprotective effect of etanercept (Enbrel®) which is a commercialized Tumor necrosis factor-α (TNF-α) inhibitor on axonal injury in an animal model of acute ischemia.

METHODS

Acute ischemia was induced by intraocular pressure elevation in 36 rats. The treatment groups underwent subcutaneous injection of etanercept (0.3 or 1.0 mg/kg) three times per week up to 4 weeks. The control groups were treated in the same manner using the same volume of phosphate-buffered saline (PBS). Optic nerve damage was evaluated by counting the number of axons under a transmission electron microscope. Microglial cell activity was assessed using Iba1 and CD68.

RESULTS

After induction of ischemia, the ratio of preserved axons was significantly greater in the 2-week 1.0-mg/kg etanercept-treated group than in the PBS-treated group (p = 0.062). The 4-week 0.3-mg/kg and 1.0-mg/kg etanercept-treated groups also showed significantly higher ratios of preserved axons than did the PBS-treated group (p = 0.021 and 0.003, respectively). The expression of Iba1 and CD68 in the optic nerve was lower in the etanercept-treated groups than in the PBS-treated groups. Immunohistochemical staining using rabbit anti-Iba1 antibody showed that the amount of microglia at the optic nerve head was noticeably lower in the etanercept-treated groups than in the PBS-treated groups.

CONCLUSIONS

Etanercept significantly suppressed optic nerve injury in this rat model of acute ischemia. This in vivo study suggests that etanercept might be a novel neuroprotective treatment agent for TNF-α-related disease.

Peripapillary retinal nerve fibre layer thickness in women with iron deficiency anaemia

OBJECTIVE

To evaluate peripapillary retinal nerve fibre layer (RNFL) thickness in adult women with iron deficiency anaemia and healthy control subjects.

METHODS

Women with iron deficiency anaemia and age- and sex-matched healthy control subjects were sequentially recruited and underwent detailed ophthalmic examination, including spectral-domain optical coherence tomography (OCT). Serum haemoglobin (Hb), iron and ferritin concentrations, total iron-binding capacity (TIBC) and mean corpuscular volume were determined.

RESULTS

Peripapillary RNFL thicknesses in the nasal and inferior quadrants were significantly smaller in patients (n = 40) than in controls (n = 40). In the patient group, there were significant correlations between inferior quadrant RNFL thickness and Hb, and between nasal quadrant RNFL thickness and serum iron and ferritin concentrations, and TIBC.

CONCLUSION

Iron deficiency anaemia reduces RNFL thickness in adult women.

Gestational iron deficiency differentially alters the structure and function of white and gray matter brain regions of developing rats

Gestational iron deficiency (ID) has been associated with a wide variety of central nervous system (CNS) impairments in developing offspring. However, a focus on singular regions has impeded an understanding of the CNS-wide effects of this micronutrient deficiency. Because the developing brain requires iron during specific phases of growth in a region-specific manner, we hypothesized that maternal iron deprivation would lead to region-specific impairments in the CNS of offspring. Female rats were fed an iron control (Fe+) or iron-deficient (Fe-) diet containing 240 or 6 μg/g iron during gestation and lactation. The corpus callosum (CC), hippocampus, and cortex of the offspring were analyzed at postnatal day 21 (P21) and/or P40 using structural and functional measures. In the CC at P40, ID was associated with reduced peak amplitudes of compound action potentials specific to myelinated axons, in which diameters were reduced by ∼20% compared with Fe+ controls. In the hippocampus, ID was associated with a 25% reduction in basal dendritic length of pyramidal neurons at P21, whereas branching complexity was unaffected. We also identified a shift toward increased proximal branching of apical dendrites in ID without an effect on overall length compared with Fe+ controls. ID also affected cortical neurons, but unlike the hippocampus, both apical and basal dendrites displayed a uniform decrease in branching complexity, with no significant effect on overall length. These deficits culminated in significantly poorer performance of P40 Fe- offspring in the novel object recognition task. Collectively, these results demonstrate that non-anemic gestational ID has a significant and region-specific impact on neuronal development and may provide a framework for understanding and recognizing the presentation of clinical symptoms of ID.

Retinal fiber layer thickness in children with thalessemia major and iron deficiency anemia

PURPOSE

We aimed to measure peripapillary retinal nerve fiber layer (RNFL) thickness in children with thalassemia major (tha-major), children with iron deficiency anemia (IDA), and children in a healthy control group.

MATERIALS AND METHODS

A total of 47 children with tha-major and 22 children with IDA were selected from two pediatric hematology outpatient clinics as our experimental groups, while 35 healthy children were randomly selected from a primary school to act as a control group. After a complete eye examination was conducted and intraocular pressure measurements were obtained, RNFL measurements were performed using optical coherence tomography, and the information was recorded for statistical analysis.

RESULTS

The mean age of the participants was 9.65 ± 4.13 years in the tha-major group, 9.14 ± 2.53 years in the IDA group, and 9.13 ± 3.29 years in the control group, respectively, with no statistically significant difference among the three groups (p > 0.05). Mean peripapillary RNFL thickness was 119.38 ± 35.49 microns in the tha-major group, 184.00 ± 31.14 microns in the IDA group, and 187.73 ± 27.36 microns in the control group. It was significantly thinner in all quadrants in the tha-major group vs. the other two groups (p < 0.01), and in only the inferior quadrant in the IDA group (p < 0.05). Average RNLF thickness correlated positively with mean hemoglobin value (r = 0.488; p < 0.001) and negatively with mean ferritin level (r = -0.544; p < 0.001), but no correlations with mean number of transfusions and mean visual acuity were observed (p > 0.05).

CONCLUSION

The study revealed that peripapillary RNFL is thinner in tha-major in all quadrants and in only the inferior quadrant in IDA. Thinning of the RNLF correlated with hemoglobin value and ferritin level, but not with number of transfusions and visual acuity.

Peripapillary Retinal Nerve Fiber Layer Thickness in Children with Iron Deficiency Anemia

Purpose.

To evaluate peripapillary retinal nerve fiber layer (RNFL) thickness in children with iron deficiency anemia (IDA) in comparison with healthy controls and to investigate the correlation between peripapillary RNFL thicknesses and the hematologic parameters in these subjects.

Methods.

Forty eyes of 40 children with a diagnosis of IDA (anemic group) and 40 eyes of 40 age- and sex-matched healthy children (control group) were enrolled in this study. Peripapillary RNFL thickness measurements were performed using Cirrus HD optical coherence tomography (OCT).

Results.

Mean age of each group was 11.3±2.7 years. Average RNFL and RNFLs of superior and inferior quadrants were significantly thinner in the anemic group than in the control group (p=0.006, p=0.005, and p=0.005, respectively). In addition, average peripapillary RNFL thickness and RNFL thicknesses of superior, inferior, and temporal quadrants were correlated with hemoglobin levels (r1=0.734, p1<0.001, r2=0.456, p2=0.005, r3=0.598, p3<0.001, r4=0.349, p4=0.037, respectively) in anemic group.

Conclusions.

We found that children with IDA had different peripapillary RNFL profile measured by Cirrus HD spectral-domain OCT. We caution ophthalmologists when they measure RNFL thickness in children to diagnose glaucoma or other neuro-ophthalmic disorders.