Copper metabolism during acute inflammation: studies on liver and serum copper concentrations in normal and inflamed rats

Cu exposure induces liver inflammation via regulating gut microbiota/LPS/liver TLR4 signaling axis

Copper (Cu) serves as an essential cofactor in all organisms, yet excessive Cu exposure is widely recognized for its role in inducing liver inflammation. However, the precise mechanism by which Cu triggers liver inflammation in ducks, particularly in relation to the interplay in gut microbiota regulation, has remained elusive. In this investigation, we sought to elucidate the impact of Cu exposure on liver inflammation through gut-liver axis in ducks. Our findings revealed that Cu exposure markedly elevated liver AST and ALT levels and induced liver inflammation through upregulating pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and triggering the LPS/TLR4/NF-κB signaling pathway. Simultaneously, Cu exposure induced alterations in the composition of intestinal flora communities, notably increasing the relative abundance of Sphingobacterium, Campylobacter, Acinetobacter and reducing the relative abundance of Lactobacillus. Cu exposure significantly decreased the protein expression related to intestinal barrier (Occludin, Claudin-1 and ZO-1) and promoted the secretion of intestinal pro-inflammatory cytokines. Furthermore, correlation analysis was observed that intestinal microbiome and gut barrier induced by Cu were closely related to liver inflammation. Fecal microbiota transplantation (FMT) experiments further demonstrated the microbiota-depleted ducks transplanting fecal samples from Cu-exposed ducks disturbed the intestinal dysfunction, which lead to impaire liver function and activate the liver inflammation. Our study provided insights into the mechanism by which Cu exposure induced liver inflammation in ducks through the regulation of gut-liver axis. These results enhanced our comprehension of the potential mechanisms driving Cu-induced hepatotoxicity in avian species.

Impact of aging on copper isotopic composition in the murine brain

Aging is the main risk factor for Alzheimer's disease (AD). AD is linked to alterations in metal homeostasis and changes in stable metal isotopic composition can occur, possibly allowing the latter to serve as relevant biomarkers for potential AD diagnosis. Copper stable isotopes are used to investigate changes in Cu homeostasis associated with various diseases. Prior work has shown that in AD mouse models, the accumulation of 63Cu in the brain is associated with the disease's progression. However, our understanding of how the normal aging process influences the brain's isotopic composition of copper remains limited. In order to determine the utility and predictive power of Cu isotopes in AD diagnostics, we aim-in this study-to develop a baseline trajectory of Cu isotopic composition in the normally aging mouse brain. We determined the copper concentration and isotopic composition in brains of 30 healthy mice (WT) ranging in age from 6 to 12 mo, and further incorporate prior data obtained for 3-mo-old healthy mice; this range approximately equates to 20-50 yr in human equivalency. A significant 65Cu enrichment has been observed in the 12-mo-old mice compared to the youngest group, concomitant with an increase in Cu concentration with age. Meanwhile, literature data for brains of AD mice display an enrichment in 63Cu isotope compared to WT. It is acutely important that this baseline enrichment in 65Cu is fully constrained and normalized against if any coherent diagnostic observations regarding 63Cu enrichment as a biomarker for AD are to be developed.

Association between serum copper, zinc, and selenium concentrations and depressive symptoms in the US adult population, NHANES (2011-2016)

BACKGROUND

Evidence suggests that alterations in serum trace element concentrations are closely associated with mental illness. However, ​studies on the relationship between serum copper, zinc, and selenium concentrations and depressive symptoms are limited and with controversial results. We aimed to investigate the association between serum concentrations of these trace elements and depressive symptoms in US adults.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) (2011-2016) were used in this cross-sectional study. The Patient Health Questionnaire-9 Items (PHQ-9) was employed to assess depressive symptoms. Multiple logistic regression was performed to determine the relationship between the serum concentrations of copper, zinc, and selenium and depressive symptoms.

RESULTS

A total of 4552 adults were included. Subjects with depressive symptoms had higher serum copper concentrations (123.88 ± 1.87) than those without depressive symptoms (116.99 ± 0.86) (p < 0.001). In Model 2, weighted logistic regression analysis showed that the second (Q2) quartile of zinc concentrations (odds ratio [OR] = 1.534, 95% confident interval [CI]: 1.018 to 2.313) were significantly associated with an increased risk of depressive symptoms. Subgroup analysis revealed that the third (Q3) and fourth (Q4) quartiles of copper concentrations (Q3: OR = 2.699, 95% CI: 1.285 to 5.667; Q4: OR = 2.490, 95% CI: 1.026 to 6.046) were also positively associated with depressive symptoms in obese individuals after controlling for all confounders. However, no significant relationship between serum selenium concentrations and depressive symptoms was observed.

CONCLUSIONS

Obese US adults with high serum copper concentrations, as well as US adults in general with low serum zinc concentrations, were susceptible to depressive symptoms. Nevertheless, the causal mechanisms underlying these relationships need to be further explored.

The Role of Copper Homeostasis in Brain Disease

In the human body, copper is an important trace element and is a cofactor for several important enzymes involved in energy production, iron metabolism, neuropeptide activation, connective tissue synthesis, and neurotransmitter synthesis. Copper is also necessary for cellular processes, such as the regulation of intracellular signal transduction, catecholamine balance, myelination of neurons, and efficient synaptic transmission in the central nervous system. Copper is naturally present in some foods and is available as a dietary supplement. Only small amounts of copper are typically stored in the body and a large amount of copper is excreted through bile and urine. Given the critical role of copper in a breadth of cellular processes, local concentrations of copper and the cellular distribution of copper transporter proteins in the brain are important to maintain the steady state of the internal environment. The dysfunction of copper metabolism or regulatory pathways results in an imbalance in copper homeostasis in the brain, which can lead to a myriad of acute and chronic pathological effects on neurological function. It suggests a unique mechanism linking copper homeostasis and neuronal activation within the central nervous system. This article explores the relationship between impaired copper homeostasis and neuropathophysiological progress in brain diseases.

Pilot Study of 64CuCl₂ for PET Imaging of Inflammation

Copper(II) ion (Cu²⁺) is the essential element for numerous pathophysiological processes in vivo. Copper transporter 1 (CTR1) is mainly responsible for maintaining Cu²⁺ accumulation in cells, which has been found to be over-expressed in inflammatory tissues. Therefore, we explored the potential application of ⁶⁴CuCl₂ for PET imaging of inflammation through targeting CTR1. The animal models of H₂O₂ induced muscle inflammation and lipopolysaccaharide induced lung inflammation were successfully established, then imaged by small animal PET (PET/CT) post-injection of ⁶⁴CuCl₂, and PET images were quantitatively analyzed. H&E and immunohistochemical (IHC) staining and western blot experiments were performed for evaluating CTR1 levels in the inflammatory and control tissues. Both inflammatory muscle and lungs can be clearly imaged by PET. PET image quantitative analysis revealed that the inflammatory muscle and lungs showed significantly higher ⁶⁴Cu accumulation than the controls, respectively (p < 0.05). Furthermore, IHC staining and western blot analysis demonstrated that compared with the controls, CTR1 expression was increased in both the inflammatory muscle and lungs, which was consistent with the levels of ⁶⁴Cu²⁺ accumulation in these tissues. ⁶⁴CuCl₂ can be used as a novel, simple, and highly promising PET tracer for CTR1 targeted imaging of inflammation.

Copper tolerance and virulence in bacteria

Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

In vivo evaluation of a Ti-based bulk metallic glass alloy bar

Ti-based bulk metallic glasses are reported with high strength, low Young modulus and high corrosion resistance, suggesting their potentials in biomedical applications. However a thorough in vivo evaluation of its biocompatibilities has not been conducted yet. In this study, we implanted bars of Ti-based bulk metallic glass in the femoral bone of rats, followed up local tissue reaction as well as its component ions' diffusion in local area and whole body. The Ti-based BMG (Ti40Zr10Cu34Pd14Sn2) alloy exhibited favorable features of both high strength and high elasticity. In vivo implant evaluation showed that it has a good tissue compatibility, equivalent bone integration and bonding ability with Ti sample. No component ion diffusion was detected up to 3 months post implantation. The possibility and efficacy of its use for bone implant is confirmed. Thus further long term implant study is recommended.

The Role of Copper and Zinc Toxicity in Innate Immune Defense against Bacterial Pathogens

Zinc (Zn) and copper (Cu) are essential for optimal innate immune function, and nutritional deficiency in either metal leads to increased susceptibility to bacterial infection. Recently, the decreased survival of bacterial pathogens with impaired Cu and/or Zn detoxification systems in phagocytes and animal models of infection has been reported. Consequently, a model has emerged in which the host utilizes Cu and/or Zn intoxication to reduce the intracellular survival of pathogens. This review describes and assesses the potential role for Cu and Zn intoxication in innate immune function and their direct bactericidal function.

Copper promotion of angiogenesis in isolated rat aortic ring: role of vascular endothelial growth factor

Copper stimulation of angiogenesis at the organ system level is vascular endothelial growth factor (VEGF) dependent, but copper stimulation of vascular endothelial cell proliferation in cultures is VEGF independent. The present study was undertaken to use isolated rat aortic rings to understand the seemly controversial observations between in vivo and in vitro studies. The thoracic aorta was isolated from Sprague Dawley rats (8-10 weeks) and sectioned into 1.0-mm thick vascular rings for culturing. Copper sulfide at a final concentration of 5, 25, 50 or 100 μM was added to the cultures and maintained for 8 days. A copper chelator, tetraethylenepentamine (TEPA) at a final concentration of 25 μM, was added to some cultures to block the effect of copper. An anti-VEGF antibody was used to determine the role of VEGF in copper promotion of angiogenesis. The data obtained showed that copper at 5 μM in cultures stimulated the vascular formation; an effect was blocked by TEPA. Copper at concentrations above 50 μM lost the proangiogenesis effect. However, copper at 5 μM did not enhance the production of VEGF, and concentrations above 50 μM significantly increased VEGF production. On the other hand, the treatment with anti-VEGF antibody completely blocked the proangiogenesis effect of 5-μM copper. This study thus demonstrates that VEGF is essential for angiogenesis but the proangiogenesis effect of copper does not act through enhanced production of VEGF.

Copper homeostasis at the host-pathogen interface

The trace element copper is indispensable for all aerobic life forms. Its ability to cycle between two oxidation states, Cu(1+) and Cu(2+), has been harnessed by a wide array of metalloenzymes that catalyze electron transfer reactions. The metabolic needs for copper are sustained by a complex series of transporters and carrier proteins that regulate its intracellular accumulation and distribution in both pathogenic microbes and their animal hosts. However, copper is also potentially toxic due in part to its ability to generate reactive oxygen species. Recent studies suggest that the macrophage phagosome accumulates copper during bacterial infection, which may constitute an important mechanism of killing. Bacterial countermeasures include the up-regulation of copper export and detoxification genes during infection, which studies suggest are important determinants of virulence. In this minireview, we summarize recent developments that suggest an emerging role for copper as an unexpected component in determining the outcome of host-pathogen interactions.

A role for the ATP7A copper-transporting ATPase in macrophage bactericidal activity

Copper is an essential micronutrient that is necessary for healthy immune function. This requirement is underscored by an increased susceptibility to bacterial infection in copper-deficient animals; however, a molecular understanding of its importance in immune defense is unknown. In this study, we investigated the effect of proinflammatory agents on copper homeostasis in RAW264.7 macrophages. Interferon-gamma was found to increase expression of the high affinity copper importer, CTR1, and stimulate copper uptake. This was accompanied by copper-stimulated trafficking of the ATP7A copper exporter from the Golgi to vesicles that partially overlapped with phagosomal compartments. Silencing of ATP7A expression attenuated bacterial killing, suggesting a role for ATP7A-dependent copper transport in the bactericidal activity of macrophages. Significantly, a copper-sensitive mutant of Escherichia coli lacking the CopA copper-transporting ATPase was hypersensitive to killing by RAW264.7 macrophages, and this phenotype was dependent on ATP7A expression. Collectively, these data suggest that copper-transporting ATPases, CopA and ATP7A, in both bacteria and macrophage are unique determinants of bacteria survival and identify an unexpected role for copper at the host-pathogen interface.

Trace micro-nutrients may affect susceptibility to bovine tuberculosis in cattle

Bovine tuberculosis (bTB) is a continuing problem in British herds. Micro-nutrients are important for the maintenance of well-functioning immune system. The aim of this study was to determine whether the selenium, copper and vitamin B12 status of cattle was associated with Mycobacterium bovis (M. bovis) infection. Between 2002 and 2005, 200 cattle (43% dairy, mean age 4.6 years), reactors according to the standard interpretation of the tuberculin test, and 200 in-contacts (41% dairy, mean age 4.4 years) non-reactors, which had been in contact with cattle with bTB, were selected from herds in England and Wales. Levels of the seleno enzyme glutathione peroxidase (GSHPx), copper and vitamin B12 were measured in blood. Confirmation of bTB infection was made by bacteriological culture and histopathology following a detailed postmortem. Levels of selenium and copper were also measured in a random sample of 63 livers. bTB was confirmed by culture/histology in 23/200 (11.5%) of in-contacts and 110/200 (55%) of reactors. In blood drawn at recruitment, GSHPx was lower in cattle with confirmed bTB compared to other cattle (geometric means 59.7 u/mL versus 78.9 u/mL red blood cells (RBC), p<0.01). Vitamin B12 was similar (geometric means 161.5 pmol/L versus 165.5 pmol/L, p=0.62) and copper was similar (geometric means 14.4 micromol/L versus 14.1 micromol/L, p=0.55). In logistic regression models including all micro-nutrients simultaneously and controlling for age, sex, animal production class, herd size, number of reactors, postmortem laboratory and seasonal trends, lower levels of GSHPx (adjusted OR 0.42, 95% CI 0.21-0.81 per 100 u/mL RBC, p=0.01) and higher levels of copper (adjusted OR 1.69, 95% CI 1.21-2.36 per 5 micromol/L, p<0.01) were associated with an increased risk of confirmed bTB but there was no association with vitamin B12. There was evidence for a stronger association between confirmed bTB and GSHPx in in-contacts (adjusted OR 0.21, 95% CI 0.06-0.79 per 100 u/mL RBC) compared to reactors (adjusted OR 0.50, 95% CI 0.21-1.23 per 100 u/mL RBC) (p=0.08 for interaction). Lower liver copper was associated with a higher risk of confirmed bTB (adjusted OR 0.15, 95% CI 0.02-1.0 per 5,000 micromol/kgdry mass, p=0.05) but there was no association between liver selenium and bTB. Trace micro-nutrient status may affect susceptibility to M. bovis infection in cattle. Further studies are needed.

Chromatographically distinguishable heme insertion isoforms of human hemopexin

Two spectroscopically distinct, non-interconverting forms of human hemopexin have been isolated by immobilized metal ion affinity chromatography and characterized spectroscopically. Form alpha (characterized by a bisignate Soret CD spectrum) and form beta (Soret CD characterized by a positive Cotton effect) exhibit different spectroscopic responses to addition of Zn2+ or Cu2+, yet both forms exhibit the same metal ion-induced decrease in Tm for the thermally induced release of the heme prosthetic group. Far UV-CD spectra indicate that the two isoforms possess essentially identical secondary structures, but their differential retention during metal ion affinity chromatography indicates slight differences in exposure of His residues on the protein surface. We propose that these observations result from the binding of heme in form beta with an orientation that differs from the crystallographically observed binding orientation for rabbit hemopexin by rotation of the heme prosthetic group by 180 degrees about the alpha-gamma meso-carbon axis and from interaction of metal ions at two separate binding sites.

Effect of zinc, copper, and calcium on the structure and stability of serum amyloid A

Serum amyloid A (SAA) is a highly conserved acute phase reactant protein, and its concentration in serum can increase up to approximately 1000 times after an inflammatory stimuli. SAA is mainly associated with high-density lipoproteins in serum, and its main function appears to involve cholesterol transport and lipid metabolism. However, SAA has also been associated with many other functions and a number of diseases, although these potential links remain poorly understood. The three-dimensional structure of SAA is not known, but we have shown that murine SAA2.2 can exist in solution as a marginally stable hexamer, which at 37 degrees C dissociates to a monomeric species that misfolds irreversibly and self-assembles into amyloid fibrils. Thus, the structure and function of SAA in vivo appear to be modulated when it binds to other proteins or small ligands. Herein, the effect of copper (Cu2+), zinc (Zn2+), and calcium (Ca2+) on the structure and stability of SAA2.2 in aqueous solution was examined using various probes of quaternary, tertiary, and secondary structure. At different concentrations of metals, including those found in the serum, the results show that the structure and stability of SAA2.2 are differently affected depending on the metal type and concentration. Copper (10-100 microM) was found to shift the equilibrium from hexamer to monomer without affecting significantly the stability of the tertiary and secondary structure of SAA2.2. In contrast, zinc (1-10 microM) bound to SAA2.2 and stabilized its quaternary, tertiary, and secondary structure. Calcium (1-10 mM) destabilized all elements of SAA2.2 structure and induced its aggregation at 10 mM. Complete aggregation of SAA2.2 was also observed when it was incubated with 1 mM Cu2+ or Zn2+, further demonstrating the tenuous structure and stability of SAA2.2. Thus, these results suggest that the many functional and pathological roles attributed to SAA may rely on its precarious structure, modulated by its interaction with ligands under homeostasis conditions and during the acute phase response.

Serum ceruloplasmin as a diagnostic marker of cancer

The pursuit of the ideal tumor marker has generated many tests for use in the diagnosis and management of cancer, several of which are now widely available. The objective of this study was to evaluate the diagnostic utility as a cancer marker of plasmatic levels of ceruloplasmin. Ceruloplasmin is a glucoprotein that transports serum copper. A case-control design was used. Serum values were evaluated in 144 patients and 103 normal controls by receiver operating characteristic (ROC) curve analysis to define the optimal cut-off levels for the serum values of ceruloplasmin in the diagnosis of cancer. The ROC analysis showed that ceruloplasmin is considerably sensitive in men (80%) at the specificity level of 80.3% and in women the sensitivity (Se) was (63.2%) and the specificity (Sp) was (63.3%). According to this study, it would seem optimal to use the cut-off level of 358 mg/l in men and 383 mg/l in women. In conclusion, serum ceruloplasmin was significantly elevated in advanced stages of solid malignant tumors, however, locally advanced or locoregionally spreading tumors did lead to significant increases (P < 0.01). Finally, the results of ROC curve analysis suggest that the ceruloplasmin is characteristic of good diagnostic markers.

Lipid peroxidation and antioxidant enzyme activity in aspirin-treated rats

1. Malondialdehyde formation and antioxidant enzyme activity after oral or intraperitoneal treatment of rats with various doses of aspirin was studied. 2. Aspirin, orally, had no effect on spontaneous, Fe(II)- or Fe(II)/ascorbate-induced malondialdehyde formation in liver homogenates; orally, ascorbate-induced malondialdehyde production was inhibited but only after 5-day treatment with 500 mg/kg aspirin; after intraperitoneal injection, the drug inhibited ascorbate- and Fe(II)/ascorbate-induced production of malondialdehyde. 3. Aspirin had no effect on malondialdehyde formation in erythrocytes, irrespective of the dose and route of drug administration. 4. Aspirin increased glutathione peroxidase activity in liver after 5-day treatment with an oral dose of 500 mg/kg and decreased enzyme activity in both liver and erythrocytes, 24 hr after a single injection of the same dose. 5. Aspirin, in vivo slightly affected lipid peroxidation and antioxidant enzyme activity.

In vitro effects of aspirin on malondialdehyde formation and on activity of antioxidant and some metal-containing enzymes

The in vitro effects of aspirin in different concentrations on malondialdehyde formation and on the activity of antioxidant and some metal-containing enzymes in rat liver homogenate and erythrocytes were studied. Aspirin showed a biphasic dependence on concentration: low concentrations (to 1.0 mM) stimulated the spontaneously formed malondialdehyde in the liver homogenate and the high concentration (5.0 mM) inhibited it; all aspirin concentrations tested had no effect on the liposomes; 5.0 mM aspirin inhibited the Fe(2+)-induced lipid peroxidation in the liver homogenate but had an opposite effect on the liposomes. Aspirin dose-dependently inhibited nitro-blue tetrazolium reduction and decreased deoxyribose degradation. The higher aspirin concentrations inhibited the activity of antioxidant and some metal-containing enzymes. It is suggested that these aspirin effects are determined by the aspirin-metal complexes formed rather than by aspirin itself.

Copper and zinc body levels in inflammation: an overview of the data obtained from animal and human studies

The development of acute and chronic inflammatory processes induces, in the laboratory animal, a net accumulation of both copper and zinc in many body compartments, the inflamed area included. In rheumatoid arthritis, as well as in animal models, only plasma zinc concentration seems to be significantly correlated with disease severity, while the increase in total plasma copper could be described as an "all or nothing" phenomenon. Moreover, in rheumatoid arthritis, it appears that the disease develops and progresses without being linked to either copper or zinc deficiency conditions. Thus, it seems reasonable to suggest that a rationale for the use of copper and/or zinc in the treatment of inflammatory disorders can only be drawn from the intrinsic pharmacological properties of such trace elements, rather than from the need for their repletion.

Is copper pro- or anti-inflammatory? A reconciling view and a novel approach for the use of copper in the control of inflammation

The anti-inflammatory role of copper is well-known although still largely unexplained. On the other hand, the capacity of copper to induce the formation of damaging .OH radicals in vivo is no longer debated. These two aspects of the physiological activity of copper have been considered to be paradoxical. Arguments developed here show that they may actually derive from a single chemical process, the type of physiological effect observed depending on the ligand bound to the copper ions involved in Fenton chemistry. Both iron and copper are Fenton catalysts. Given its intrinsic coordination properties, however, copper induces more site-specific .OH damage to the ligands bound to it. It, therefore, appears that copper complexes with specific .OH-inactivating ligands (OILs) can be used as "lures" for the Fenton reaction, .OH radicals preferentially formed on these being immediately inactivated. The hypothesis is thus put forward here that copper-OIL complexes acting as effective Fenton catalysts are potential "catalase-like" anti-inflammatory drugs.

In vivo effects of indomethacin on the activity of metal-containing enzymes

1. Indomethacin injected subcutaneously at a single "ulcerogenic" dose decreased aminooxidase and leucine aminopeptidase activity and did not change alcohol dehydrogenase and ceruloplasmin activity. 2. Indomethacin administered at an oral "therapeutic" dose inhibited aminooxidase activity in small intestinal mucosa but not in liver and did not change leucine aminopeptidase activity in blood, liver and intestinal mucosa; it, however, increased alcohol dehydrogenase and ceruloplasmin activity. 3. The decreased activity of ceruloplasmin and alcohol dehydrogenase by metal deficiency increased after oral indomethacin treatment, reaching the control values when indomethacin was chelated with copper. 4. The results suggest the participation of endogenous metals in the indomethacin effect.

In vivo effects of indomethacin--II. Antioxidant enzymes in metal-deficient rats

1. The in vivo effects of indomethacin on the activity of antioxidant enzymes in erythrocytes, liver and small intestinal mucosa of rats fed a metal-deficient diet were studied. 2. Metal deficiency led to a significant decrease in the activity of the enzymes studied. 3. Neither with the "ulcerogenic" nor with the "therapeutic" dose of indomethacin significant alterations in the enzyme activity were observed. 4. The oral treatment of metal-deficient rats with a copper complex of indomethacin caused a significant increase in the activity of the enzymes studied. 5. The results suggest the participation of indomethacin in the regulation and redistribution of metals in the organism, which is probably effected through in vivo chelation of endogenous metals.

Effects of acute prednisolone administration on plasma and liver copper in rats with adjuvant arthritis

Several studies in animals and humans have shown that copper metabolism could be affected by inflammation or by corticosteroids. The relative importance of these two factors, often imbedded in clinical practice, was assessed by investigating the effects of acute prednisolone administration (30 mg/kg, ip) on healthy and adjuvant arthritis rats. Plasma copper levels were significantly higher in arthritic rats compared to healthy animals, whereas there was a slight, but nonsignificant increase in liver copper. Acute prednisolone administration in healthy rats resulted in a significant increase in plasma copper (10-15%) as early as 4 h after corticosteroid administration, which was maintained for 12 h. In arthritic rats, the response was much higher (25-40%), but somewhat delayed and shorter. Liver copper was not clearly modified by prednisolone treatment in both groups. This time-controlled study showed that acute prednisolone administration increased plasma copper in both healthy and arthritic rats, but in different ways, indicating that inflammation and corticosteroids may act synergistically.

Effects of copper aspirinate and aspirin on tissue copper, zinc, and iron concentrations following chronic oral treatment in the adjuvant arthritic rat

Concentrations of copper, zinc, and iron were analyzed and compared in a number of tissues of adjuvant arthritic rats following 22 d of chronic treatment (per os) with either vehicle, aspirin or copper aspirinate, at doses of 100 mg/kg, 200 mg/kg, or 400 mg/kg. Such chronic treatment resulted in a negative balance in copper, zinc, and iron in many tissues. Among the tissues examined, liver and kidney exhibited the greatest changes in metal concentrations; brain and skeletal muscle exhibited the least. Arthritis-induced changes in the concentrations of all three metals in the liver were reversed upon treatment with aspirin. Treatment with copper aspirinate, on the other hand, resulted in an extremely high accumulation of copper in the liver. Arthritis-induced changes in copper, zinc, and iron concentrations in the pancreas and copper concentration in the plasma were generally not reversed upon treatment with either aspirin or copper aspirinate. Among the three metals examined, the degree of change observed as a result of drug treatments was greatest for iron and least for zinc. Finally, it appeared that the effects of aspirin and copper aspirinate on tissue metal concentrations were independent of the antiarthritic effects of these compounds.

Serum copper concentration as an index of clinical lung injury

The purpose of this ongoing study is to determine whether thoracic radiotherapy for lung cancer produces an early increase in serum copper (Cu) concentration, an increase which might predict clinical outcome. Copper and iron concentrations were measured in serum obtained from nonsmall cell lung cancer patients at 0, 1, 2, 4, and 6 weeks after the start of radiotherapy. Control groups included patients irradiated for breast cancer (low dose of radiation to the lung), for endometrial, cervical or prostatic cancer (no dose to lung), and patients with congestive heart failure, pulmonary hypertension, chronic obstructive pulmonary disease (COPD), and cutaneous burns with or without smoke inhalation (no irradiation). Serum Cu concentration increased at least 10 micrograms/dl from the pretreatment level in approximately 75% of the adenocarcinoma and squamous cell lung cancer patients, but in only 1 of 4 undifferentiated lung cancer cases. In virtually all of these responders, serum Cu increased to a maximum at 2 weeks after the start of therapy, then plateaued or decreased slightly despite continuing irradiation. Within the subset of squamous cell lung cancers, there was a direct correlation between the degree of histologic differentiation and both baseline serum Cu concentration and the probability of an early increase therein. In contrast, only 33% of breast cancer patients and 15% of endometrial, cervical and prostate cancer patients exhibited an increase in serum Cu concentration at 2 weeks after the start of radiotherapy. Serum Cu concentration was within normal limits in virtually all patients with congestive heart failure, pulmonary hypertension, and COPD. Burn patients exhibited a significant reduction in serum Cu, although concomitant smoke inhalation increased serum Cu back to low-normal levels. Serum iron concentration did not change significantly in any category of patients. These data suggest that thoracic radiotherapy for well differentiated non-small cell lung cancer is accompanied by an early increase in serum Cu concentration. This increase is partly but not wholly related to lung dose in particular rather than tissue dose in general, and specifically reflects radiation-induced lung injury rather than pneumopathy in general. In lung cancer patients, the change in serum Cu concentration during the first 2 weeks of radiotherapy exhibits a sufficiently broad range (+60 to -13 micrograms/dl) to permit testing this parameter as a predictor of tumor response and pulmonary complications.

Serum copper concentration as an index of experimental lung injury

Serum copper (Cu) concentration was evaluated as an index of lung injury in two rat models of pneumotoxicity: hemithoracic irradiation and monocrotaline ingestion. In both models there was a dose- and time-dependent increase in serum Cu concentration. This hypercupremia paralleled the development of pulmonary endothelial dysfunction (decreased lung plasminogen activator activity and increased prostacyclin production) and pulmonary fibrosis (hydroxyproline accumulation). In the radiation model, lung injury and hypercupremia persisted for at least 6 months, and were spared similarly when the total dose was delivered in multiple daily fractions as compared to single doses. In irradiated rats, the elevated serum Cu concentration was accompanied by increases in plasma ceruloplasmin, lung Cu concentration, and lung Cu/Zn superoxide dismutase (SOD) activity. In monocrotaline-treated rats, lung damage and hypercupremia also were accompanied by a reduction in liver Cu concentration, and by a direct correlation between the concentrations of Cu and SGOT in the serum. In both models, some but not all modifiers of lung damage (penicillamine, angiotensin converting enzyme inhibitors, pentoxifylline) also partially prevented the insult-induced hypercupremia. In contrast, serum iron concentration was largely independent of treatment in all experiments. These data suggest that elevated serum copper concentration is an accurate and minimally invasive index of lung injury in irradiated and monocrotaline-treated rats.

Changes in zinc, copper and selenium status during adjuvant-induced arthritis in rats

Trace elements such as zinc, copper and selenium are involved in the pathogenesis of inflammatory diseases. In order to obtain more information about the overall movements of these minerals during the evolution of an experimental chronic inflammatory process, trace element levels were determined in five body compartments of the rat at several time intervals after induction of adjuvant arthritis. Rapid and significant changes in plasma zinc and copper levels and in liver zinc levels were observed. These modifications occurred as early as those in biochemical parameters of inflammation such as serum fibrinogen and ceruloplasmin, and preceded the appearance of any clinical symptom of the disease. Inverse correlations were found between plasma zinc levels and these two biochemical indices. Other modifications in trace element levels were observed two weeks after disease induction, the most important being a considerable increase in liver copper levels. Although food intake of affected animals decreased with the progression of the disease, there was no evidence of depletion in zinc and copper levels over the study period. A redistribution of body zinc between different biological compartments (mainly plasma and liver) occurred simultaneously with an accumulation of copper in several organs. The decreasing selenium status of animals was not clearly related to the inflammatory process.

Copper and zinc status in rats with acute inflammation: focus on the inflamed area

Status of copper and zinc in plasma, blood cells, liver and hind paws (sectioned at the tibio-tarsal joint) were evaluated in rats with carrageenan-induced paw-oedema; moreover, concentrations of copper and zinc in the supernatant and cell fractions obtained from exudates pooled from rats with carrageenan-induced pleurisy were also determined. The evaluation of copper and zinc status in the blood and in the liver of rats with carrageenan-induced paw oedema, showed that only minor variations differentiated this experimental pathology from the previously studied carrageenan-induced pleurisy in rat. In inflammatory exudates withdrawn from pleural cavity, copper concentrations were found to be higher than the basal values measured in the whole paw, whereas zinc concentrations were found to be dramatically lower. Thus, the induction of the carrageenan paw-oedema determined an increase in copper and a decrease in zinc concentrations in the inflamed paw; however, in the inflamed paw, the total amounts of both copper and zinc were found to be significantly increased.

Copper and zinc status in adjuvant-arthritic rat: studies on blood, liver, kidneys, spleen and inflamed paws

The status of copper and zinc in plasma, blood cells, kidneys, spleen and hind paws was evaluated in tail-injected adjuvant-arthritic rats, during both the asymptomatic (3 and 7 days after the inoculum) and symptomatic (14, 21 and 30 days after the inoculum) phases of the experimental disease. During the symptomatic phase, inflamed rats were studied divided into two groups on the basis of their arthritic scores (low-score L.S. and high-score H.S. arthritic rats). Copper (both in concentration and total amount) was found significantly increased in plasma, blood cells, liver, spleen and arthritic paws, whereas, in the kidneys, it was found to be lower than normal. Zinc was found to be remarkably increased in the liver. In blood, zinc was found to be decreased in plasma, but almost unchanged in the cellular fraction. Zinc total amount (but not concentration) was increased in the spleen, most likely because of a significant increase in spleen weight. As previously described in the case of acute inflammation, zinc concentration was found to be significantly decreased in arthritic paws, whereas the total amount of the metal present in these inflamed tissues was higher than normal. The status of copper and zinc may well differentiate L.S. from H.S. arthritic rats, especially during the latest phase of the experimental disease, and particularly because of a normalization of the considered parameters in the low-score group. Many of the changes observed in the status of both metals were seen prior the appearance of arthritis. The overall accumulation of copper and zinc which is induced in rat by the development of adjuvant arthritis, is suggested to further sustain the hypothesis of increased body requirements for both metals during inflammation.

Effects of repetitive immunogen injections and fasting versus feeding on iron, zinc, and copper metabolism in chicks

Most investigations on the effect of immunogenic challenge on trace-mineral metabolism use a single immunogen injection in fasted animals. Because these investigations are not representative of realistic situations in which animals are constantly exposed to immunogens and still consume feed, the following studies were done. In Expt. 1, chicks were injected ip with sheep red blood cells (SRBC), Sephadex, SRBC+Sephadex, or saline. Chicks were then fasted or fed equal amounts of feed (equal fed) for 16 h. Immunogen injection decreased serum Fe and Zn and increased serum Cu within each feeding program. Differences in Cu, and to a lesser extent Zn, concentrations between immunogen- and saline-injected chicks were more pronounced in fasted than in equal-fed chicks. In Expt. 2, equalfed chicks were injected ip every 48 h for 6 d with SRBC+Sephadex or saline. Two days after each injection, tissues were taken. An additional group of chicks was injected once and subsequently fasted 16 h, whereupon tissues were taken. Changes in plasma Fe, Zn, Cu, and ceruloplasmin; hepatic Fe, Zn, Cu, and metallothionein; pancreatic Fe and Zn; and splenic Fe in repetitively injected chicks were different from changes observed in chicks injected once. The results indicate that the trace-mineral response to immunogenic challenge is dependent upon the number of immunogen injections and the nutritional state of the animal.

Copper and zinc status during acute inflammation: studies on blood, liver and kidneys metal levels in normal and inflamed rats

The concentrations of copper and zinc in plasma, blood cells, liver and kidneys were determined in a study performed on normal female rats, and in female rats with carrageenan induced pleurisy. In the normal rat, the total amount of both metals increases, from 51 to 79 days of age, in all the compartments examined. This increase was mostly, and in some case exclusively, dependent upon the growth of the animal, although high individual and day to day variations in both copper and zinc values were observed in all the compartments studied. In the blood of inflamed rats a statistically significant increase in copper was measured during the crucial hours of the experiment (i.e. from 6 to 72 h); over 90% of the increase found was attributable to variations in plasma copper concentration values. In the liver of inflamed rats a statistically significant increase in zinc was measured at 6, 22 and 48 h after the carrageenan injection. The induction of the acute non-infective inflammatory process did not cause quantitative changes of both copper and zinc in all the other compartments considered in the present study. These results seem to suggest that, during acute inflammation, the organism increases its requirement for copper and zinc, and that this demand is fulfilled by enhanced intestinal absorption and/or decreased intestinal excretion of both metals.

Copper and inflammation--a possible rationale for the pharmacological manipulation of inflammatory disorders

Acute and chronic inflammations are characterized, among other features, by changes in the metabolism of copper and by a widespread responsiveness to the therapy with copper-containing molecules. The exact map of inflammation-induced copper movements as well as the role played by the metal in the pathogenesis of inflammatory disorders are, however, far from being clear, and this is especially true in the case of chronic processes. Nevertheless the present knowledge suggests that the "copper approach' may provide a new way for coping with the problem of anti-inflammatory/anti-arthritic therapies. The administration of exogenous copper, and the in vivo manipulation of the endogenous metal levels are proposed as two possible therapeutic strategies, not necessarily mutually exclusive. For a better understanding of the value of such an approach, further research work is needed, especially to attain a more detailed know-how on the involved chemical forms, distribution and functions of copper in both normal as well as inflamed organisms.