The effect of copper deficiency on the formation of hemosiderin in sprague-dawley rats

Broiler responses to copper levels and sources: growth, tissue mineral content, antioxidant status and mRNA expression of genes involved in lipid and protein metabolism

BACKGROUND

Five hundred 8-d old male broilers Cobb500 were randomly allotted into 10 treatments in factorial arrangement with 5 Cu levels (0, 4, 8, 12, and 16 mg/kg), and 2 sources (Cu proteinate, CuPro and Cu sulphate, CuSO4.5H2O) for a 10-d-experiment.

RESULTS

Feed conversion ratio (FCR) was better (P < 0.05) in CuPro fed chicks compared with CuSO4.5H2O group. Average daily feed intake (ADFI) decreased linearly (P < 0.05) as dietary Cu increased. A quadratic response (P < 0.05) to Cu levels was found for FCR, being optimized at 9.87 and 8.84 mg Cu/kg in CuPro and CuSO4.5H2O diets, respectively. Copper supplementation linearly increased liver Cu content (P < 0.05) and tended to linearly increase (P = 0.07) phosphorus (P) and copper in tibia. Manganese and zinc were higher (P < 0.05) in tibia of CuPro fed birds. Broilers fed CuPro exhibited lower liver iron (P < 0.05) content, lower activities of Cu, Zn superoxide dismutase (CuZnSOD) in breast muscle and liver, and glutathione peroxidase in liver. Glutathione peroxidase reduced linearly (P < 0.05) with CuPro levels and increased linearly (P < 0.05) with CuSO4.5H2O levels and were lower (P < 0.05) in all CuPro levels in breast muscle. Breast muscle malondialdehyde concentration tended to be higher (P = 0.08) in broilers fed CuSO4.5H2O. Copper levels linearly increased (P < 0.05) metallothionein (MT) and malate dehydrogenase (MDH) expression in liver, and six-transmembrane epithelial antigen of the prostate-1 (STEAP-1) in the intestine. Copper elicited a quadratic response (P < 0.050) in AKT-1 and mammalian target of rapamycin (mTOR) in breast muscle, CuZnSOD in liver and antioxidant 1 copper chaperone (ATOX 1) in intestine. Broilers fed CuPro exhibited higher mRNA expression of mTOR in muscle breast and lower CuZnSOD in liver and ATOX 1 in intestine. Interaction (P < 0.05) between levels and sources was found in mRNA expression for GSK-3β, MT, and CuZnSOD in breast muscle, FAS and LPL in liver and MT and CTR1 in intestine.

CONCLUSIONS

CuPro showed beneficial effects on feed conversion and bone mineralization. Organic and inorganic Cu requirements are 9.87 and 8.84 mg Cu/kg, respectively.

Impact of copper in Xenopus laevis liver: Histological damages and atp7b downregulation

Copper is an essential micronutrient but its excess in the dietary can be toxic. Both copper deficiency and abundance can occur in natural conditions and can lead to pathological dysfunctions. Many of the toxic effects of copper, such as increased lipid peroxidation in cell membranes and DNA damage, are due to its role in the generation of oxygen free radicals. Copper is released into the environment by both natural sources and human activities and it can damage organisms and ecosystems. In the present work the effects of copper has been studied on Xenopus laevis, an interesting model organism, after three weeks of exposure at 1 mg/L of CuCl, concentration allowed in the water for human use. The effects of this metal were analysed on the liver at light microscope by Hematoxylin-Eosin, Mallory, Pas and Perls stainings to evaluate the general histology, the glycogen metabolism and presence of hemosiderin. Moreover the number and area of melanomoacrophages, known as inflammation parameters, were assessment. Finally, we investigated the expression of atp7b gene and localization of respective ATP7B protein, the membrane protein involved in Cu detoxication. The achieved results showed that copper, even at a low concentration, causes serious histological alterations of liver. It induces an increase in the size and number of melanomacrophages and higher amount of hemosiderin in the treated than controls. Moreover, it alters the gene expression and localization of ATP7B protein. The data are indicative that an exposition at low and chronic concentration of copper in Xenopus laevis damages seriously the liver. For this reason it's important to consider this metal one of the pollutants involved in the decline of the amphibians and for its possible effects in other vertebrates including humans.

Ferric Citrate Supplementation Reduces Red-Blood-Cell Aggregation and Improves CD163+ Macrophage-Mediated Hemoglobin Metabolism in a Rat Model of High-Fat-Diet-Induced Obesity

SCOPE

In adults, >90% of the daily iron requirement is derived from macrophage-mediated heme iron, recycling from senescent red blood cells (RBCs) or free hemoglobin (Hb). Currently, the effects of pharmacological doses of iron supplementation on RBCs and heme iron recycling in obesity are unclear.

METHODS AND RESULTS

Sprague Dawley rats are fed a standard diet or a 50% high-fat diet (HFD) with (0.25, 1, and 2 g of ferric iron per kg diet) or without ferric citrate supplementation for 12 weeks. Ferric iron increases hepatic iron accumulation in macrophages and hepatocyte-like cells. Compared with rats that received the standard diet, HFD-fed rats exhibit higher RBC aggregation and serum-free Hb levels but lower LVV-hemorphin-7 levels. These effects are reversed by ferric citrate supplementation. Immunofluorescent staining reveals that ferric iron increases the expression of hepatic CD163+ macrophages and heme oxygenase (HO)-1. A further analysis reveals the dose-related effects of ferric iron on hepatic globin degradation proteins (cathepsin D and glyoxalase 1), cytochrome p450 reductase expression, and HO-1 enzyme activity.

CONCLUSIONS

Ferric citrate supplementation reduces RBC aggregation and improves CD163+ macrophage-mediated Hb metabolism in HFD-induced obese rats. These findings suggest that ferric citrate may be explored as an alternative treatment method for RBC dysfunction.

The Loss of Myocardial Benefit following Ischemic Preconditioning Is Associated with Dysregulation of Iron Homeostasis in Diet-Induced Diabetes

Whether the diabetic heart benefits from ischemic preconditioning (IPC), similar to the non-diabetic heart, is a subject of controversy. We recently proposed new roles for iron and ferritin in IPC-protection in Type 1-like streptozotocin-induced diabetic rat heart. Here, we investigated iron homeostasis in Cohen diabetic sensitive rat (CDs) that develop hyperglycemia when fed on a high-sucrose/low-copper diet (HSD), but maintain normoglycemia on regular-diet (RD). Control Cohen-resistant rats (CDr) maintain normoglycemia on either diet. The IPC procedure improved the post-ischemic recovery of normoglycemic hearts (CDr-RD, CDr-HSD and CDs-RD). CDs-HSD hearts failed to show IPC-associated protection. The recovery of these CDs-HSD hearts following I/R (without prior IPC) was better than their RD controls. During IPC ferritin levels increased in normoglycemic hearts, and its level was maintained nearly constant during the subsequent prolonged ischemia, but decayed to its baseline level during the reperfusion phase. In CDs-HSD hearts the baseline levels of ferritin and ferritin-saturation with iron were notably higher than in the controls, and remained unchanged during the entire experiment. This unique and abnormal pattern of post-ischemic recovery of CDs-HSD hearts is associated with marked changes in myocardial iron homeostasis, and suggests that iron and iron-proteins play a causative role/s in the etiology of diabetes-associated cardiovascular disorders.

Speciation of iron in mouse liver during development, iron deficiency, IRP2 deletion and inflammatory hepatitis

The iron content of livers from (57)Fe-enriched C57BL/6 mice of different ages were investigated using Mössbauer spectroscopy, electron paramagnetic resonance (EPR), electronic absorption spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS). About 80% of the Fe in an adult liver was due to blood; thus removal of blood by flushing with buffer was essential to observe endogenous liver Fe. Even after exhaustive flushing, ca. 20% of the Fe in anaerobically dissected livers was typical of deoxy-hemoglobin. The concentration of Fe in newborn livers was the highest of any developmental stage (∼1.2 mM). Most was stored as ferritin, with little mitochondrial Fe (consisting primarily of Fe-S clusters and haems) evident. Within the first few weeks of life, about half of ferritin Fe was mobilized and exported, illustrating the importance of Fe release as well as Fe storage in liver function. Additional ferritin Fe was used to generate mitochondrial Fe centres. From ca. 4 weeks of age to the end of the mouse's natural lifespan, the concentration of mitochondrial Fe in liver was essentially invariant. A minor contribution from nonhaem high-spin Fe(II) was observed in most liver samples and was also invariant with age. Some portion of these species may constitute the labile iron pool. Livers from mice raised on an Fe-deficient diet were highly Fe depleted; they were devoid of ferritin and contained 1/3 as much mitochondrial Fe as found in Fe-sufficient livers. In contrast, brains of the same Fe-deficient mice retained normal levels of mitochondrial Fe. Livers from mice with inflammatory hepatitis and from IRP2(-/-) mice hyper-accumulated Fe. These livers had high ferritin levels but low levels of mitochondrial Fe.

Avian iron storage disease: variations on a common theme?

Many frugivorous avian species kept in captivity develop iron storage disease (ISD) as indicated by high concentrations of hepatic iron and hemosiderin deposits in hepatocytes or phagocytes. In several susceptible species fed diets containing moderate levels of iron, ISD develops because of an inability to match rates of iron absorption to tissue needs. Evidence suggests that the pathophysiologic basis of excess iron absorption is due to high levels of expression of divalent metal transporter-1 that transports iron into enterocytes in the proximal intestine, and ferroportin that exports iron to the circulation. The regulatory basis for this inability to sufficiently down-regulate iron absorption is unknown, but disruptions in the hepcidin-ferroportin axis are likely candidates based on recent research in humans and laboratory rodents. It is likely that ISD-susceptible avian species evolved on foods that were very low in bioavailable iron, so there was strong selection pressure for the efficient capture of the small amount of dietary iron but low selection pressure for preventing iron toxicities. Thus, the transporters and regulatory networks for iron absorption seem to be heavily skewed toward iron storage even when food items that are high in iron are consumed. Infections, trauma and neoplasias that trigger an acute phase response may exacerbate ISD in susceptible species and may be the primary cause in species that are normally resistant to ISD (i.e., those that are normally able to shut down intestinal iron absorption when iron stores are replete). The evolutionary basis that resulted in some avian species to be susceptible to ISD (e.g., dietary cause) seems to differ from many inherited ISD disorders in humans that are thought to have evolved to bolster protection against infectious diseases. However the evolutionary basis of ISD in other mammalian species might be more similar to that in ISD-susceptible avian species.

Glycosylphosphatidylinositol-linked ceruloplasmin is expressed in multiple rodent organs and is lower following dietary copper deficiency

Ceruloplasmin (Cp), a multicopper ferroxidase, is expressed as both a secreted (sCp) plasma enzyme from the liver and a membrane-bound glycosylphosphatidylinositol-anchored (GPI-Cp) splice variant protein. Cp is thought to be essential for iron mobilization as selective iron overload occurs in aceruloplasminemia in humans and in Cp null mice. Dietary copper-deficient (CuD) rodents have near total loss of Cp activity, severe loss of Cp protein and develop anemia. Hepatic iron augmentation is often observed, suggesting that loss of Cp function may be correlated with anemia. The impact of CuD treatment on GPI-Cp has not previously been evaluated. Our hypothesis was that CuD rodents would have lower levels of GPI-Cp and this would correlate with higher tissue iron retention. In these studies, GPI-Cp was detected in purified membranes of multiple organs of rats and mice but not Cp −/− mice. Immunoreactive Cp protein was released with phosphatidylinositol phospholipase C treatment and expressed ferroxidase activity. Following perinatal and postnatal copper restriction, GPI-Cp was markedly lower in the spleen and modestly lower in the liver of CuD rats and mice, when compared with copper-adequate (CuA) rodents. However, spleen non-heme iron (NHI) was lower in CuD than CuA rats, and not different in CuD mice. Hepatic iron was higher only in CuD mice. Spleen and liver membranes of CuD rats expressed augmented levels of ferroportin, the iron efflux transporter, which may explain lower NHI content in the spleen of CuD rats despite a greater than 50% lower level of the multicopper ferroxidase GPI-Cp. Spleen and liver levels of GPI-Cp mRNA were not impacted in CuD rats, suggesting that turnover rather than biosynthesis may explain the lower steady-state levels of GPI-Cp following dietary copper restriction. Lower GPI-Cp did not correlate with tissue iron retention and thus the role, if any, of Cp in anemia of copper deficiency is unknown.

Metabolic crossroads of iron and copper

Interactions between the essential dietary metals, iron and copper, have been known for many years. This review highlights recent advances in iron-copper interactions with a focus on tissues and cell types important for regulating whole-body iron and copper homeostasis. Cells that mediate dietary assimilation (enterocytes) and storage and distribution (hepatocytes) of iron and copper are considered, along with the principal users (erythroid cells) and recyclers of red cell iron (reticuloendothelial macrophages). Interactions between iron and copper in the brain are also discussed. Many unanswered questions regarding the role of these metals and their interactions in health and disease emerge from this synopsis, highlighting extensive future research opportunities.

Copper availability contributes to iron perturbations in human nonalcoholic fatty liver disease

BACKGROUND & AIMS

Iron perturbations are frequently observed in nonalcoholic fatty liver disease (NAFLD). We aimed to investigate a potential association of copper status with disturbances of iron homeostasis in NAFLD.

METHODS

We retrospectively studied 140 NAFLD patients and 25 control subjects. Biochemical and hepatic iron and copper parameters were analyzed. Hepatic expression of iron regulatory molecules was investigated in liver biopsy specimens by reverse-transcription polymerase chain reaction and Western blot analysis.

RESULTS

NAFLD patients had lower hepatic copper concentrations than control subjects (21.9 +/- 9.8 vs 29.6 +/- 5.1 microg/g; P = .002). NAFLD patients with low serum and liver copper concentrations presented with higher serum ferritin levels (606.7 +/- 265.8 vs 224.2 +/- 176.0 mg/L; P < .001), increased prevalence of siderosis in liver biopsy specimens (36/46 vs 10/47 patients; P < .001), and with elevated hepatic iron concentrations (1184.4 +/- 842.7 vs 319.9 +/- 451.3 microg/g; P = .020). Lower serum concentrations of the copper-dependent ferroxidase ceruloplasmin (21.7 +/- 4.1 vs 30.4 +/- 6.4 mg/dL; P < .001) and decreased liver ferroportin (FP-1; P = .009) messenger RNA expression were found in these patients compared with NAFLD patients with high liver or serum copper concentrations. Accordingly, in rats, a reduced dietary copper intake was paralleled by a decreased hepatic FP-1 protein expression.

CONCLUSIONS

A significant proportion of NAFLD patients should be considered copper deficient. Our results indicate that copper status is linked to iron homeostasis in NAFLD, suggesting that low copper bioavailability causes increased hepatic iron stores via decreased FP-1 expression and ceruloplasmin ferroxidase activity thus blocking liver iron export in copper-deficient subjects.