Concerning the role of endogenous copper in the acute inflammatory process

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.

Neutrophil behavior following exposure to in vivo or in vitro zinc in normal and acutely-inflamed rats: studies on lysozyme secretion, superoxide anion release and platelet adhesion

The mechanism was studied of the anti-inflammatory effect of oral zinc (114 mg/kg/day of elemental metal, given for 14 days) on the development of the carrageenan-induced paw oedema of the rat, and the impact of in vivo treatment on the activity of neutrophils isolated from the blood of inflamed and non-inflamed animals. The effects of the in vitro incubation with the metal on either non-inflamed or inflamed neutrophils coming from zinc-untreated rats were also examined. It was found that the administration of oral zinc inhibited markedly the process of ex vivo adhesion of the cells obtained from the inflamed rats (an observation confirmed by the in vitro experiments). In vitro release of lysozyme and superoxide anion productions were measured: in the absence of zinc, the 30' of pre-incubation carried out before stimulating with PMA did not influence the cell's reactivity of the non-inflamed neutrophils. It was, on the contrary, capable of significantly reducing that of the inflamed ones. As a consequence, it is quite difficult to properly interpret the data obtained studying the activity of the cells exposed to the metal in vitro.

Detection and investigation of the molecular nature of low-molecular-mass copper ions in isolated rheumatoid knee-joint synovial fluid

Low-molecular-mass copper(II) species have been detected and quantified in ultrafiltrates (n = 7) of rheumatoid synovial fluid (SF) by a highly-sensitive HPLC-based assay system with the ability to determine Cu(II) concentrations of < 10(-7) mol.dm-3. High field 1H NMR spectroscopy demonstrated that addition of Cu(II)(aq.) to isolated samples of RA SF ultrafiltrates resulted in complexation by histidine > alanine > formate > threonine > lactate > tyrosine > phenylalanine, their effectiveness in this context being in the given order. CD spectra of Cu(II)-treated samples of intact SF exhibited absorption bands typical of copper(II)-albumin complexes, in addition to a band attributable to a low-molecular-mass histidinate complex (lambda min 610 nm). Since both albumin and histidine are potent radical scavengers, these results indicate that any .OH radical generated from bound copper ions will be 'site-specifically' scavenged. Hence, low-molecular-mass copper complexes with the ability to promote the generation of .OH radical which can then escape from the metal ion co-ordination sphere (and in turn, cause damage to critical biomolecules) appear to be absent from inflammatory SF.

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.

Nutritional copper deficiency does not affect sponge granuloma formation in the rat

Sponge granuloma formation was compared in copper-deficient and copper-sufficient rats following feeding of respective diets for 20, 40, or 60 d. Body weight, total blood hemoglobin, and activities of ceruloplasmin and Cu, Zn-superoxide dismutase in plasma were monitored to ascertain copper deficiency. Mean granuloma weights (mg +/- SEM) in copper-deficient and copper-sufficient groups of rats, respectively, were as follows: 37 +/- 2 and 38 +/- 2 after 20 d, 22 +/- 2 and 23 +/- 2 after 40 d, and 19 +/- 1 and 21 +/- 1 after 60 d on respective diets. Thus, nutritional copper deficiency did not have an effect on sponge granuloma formation in the rat.

Effect of nutritional copper deficiency on carrageenin edema in the rat. A quantitative study

The effects of nutritional copper deficiency on carrageenin edema in the rat were investigated with emphasis on studying the correlation between the degree of copper deficiency and the degree of edema. Carrageenin paw edema in both copper-sufficient and copper-deficient groups of rats was compared after either 20, 40, or 60 d on respective diets. The degree of copper deficiency was quantitated by analyzing total copper concentrations in a number of tissues. Other copper dependent parameters were also determined. Results indicated that: (1) although copper sufficient rats showed relatively little change in the degree of edema, copper-deficient rats showed a steady and significant increase in edema from d 20 to 40 to 60; (2) paw edema in copper-deficient animals was highly and negatively correlated to the concentrations of copper in the liver; the correlation with liver Cu,Zn-superoxide dismutase activity, however, was inconsistent; (3) paw edema was not correlated either to copper concentration in tissues other than liver or to plasma ceruloplasmin activity; and (4) aggravation of carrageenin edema in copper-deficient animals seemed to be mediated via an as yet unknown secondary effect of copper deficiency.

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.

Role of ceruloplasmin in inflammation: increased serum ceruloplasmin levels during inflammatory conditions and its possible relationship with anti-inflammatory agents

Serum ceruloplasmin (CPN) levels under different types of acute and chronic experimentally-induced inflammatory conditions in rats and the effect of anti-inflammatory drugs viz. oxyphenylbutazone and hydrocortisone on serum CPN levels were investigated. Significant increase of serum CPN levels was observed in all experimental animal models with induced inflammatory conditions. Treatment with oxyphenylbutazone and hydrocortisone failed to inhibit the raised serum CPN levels. The concurrent increase of serum CPN level during induced inflammatory conditions suggest the involvement of serum CPN as one of the body's inbuilt defensive mechanism against noxious responses or inflammation. It is suggested that the increased serum CPN levels may be a complimentary factor associated with inflammatory conditions.

Inhibition of prostaglandin action and bone resorption by copper

Mouse calvaria were maintained in organ culture without serum additives. The effects of Cu2+ on bone resorption and on the synthesis and action of prostaglandins were studied. Non-toxic concentrations of copper sulphate (5 microM) were found to decrease active resorption, measured by 45Ca release, to 54% control values (p less than 0.001), while prostaglandin F (PGF), prostaglandin E2 (PGE2), and 6-keto-prostaglandin F1 alpha, (6-keto-PGF1 alpha), determined by radioimmunoassay, were increased above controls (p less than 0.05). These effects of Cu2+ on prostaglandin synthesis were confirmed by the isolation and quantitation of [3H]-labelled metabolites released from calvaria which had been pre-labelled with [3H]-arachidonic acid. PGE2, PGF2 alpha, 6-keto-PGF1 alpha, and thromboxane B2 (TxB2) were all higher in copper-exposed calvaria, but their relative amounts remained unchanged. There was no evidence that Cu2+ influenced the mobilisation of [3H]-arachidonic acid from prelabelled calvaria. The stimulation of bone resorption by exogenous prostaglandins was decreased in the presence of Cu2+ (p less than 0.005), while parathormone-mediated bone resorption was virtually unaffected. Cu2+ also increased the inhibition of bone resorption seen with indomethacin (p less than 0.05). In addition to the effects of the metal on prostaglandin action Cu2+ also decreased beta-glucuronidase activity in the media to 86% of the control values (p less than 0.001). The action of Cu2+ in inhibiting bone resorption in vitro appears complex but does not involve inhibition of prostaglandin synthesis. It is likely that Cu2+ has more than one inhibitory locus.

Serum copper and ceruloplasmin levels in rheumatoid arthritis and degenerative joint disease and their pharmacological implications

Serum copper concentration and ceruloplasmin activity were measured in patients with clinically established rheumatoid arthritis (R.A.) during the active phase, in patients with degenerative joint disease (D.J.D.) and in normal subjects. Copper and ceruloplasmin serum levels are significantly increased (P less than 0.01) in the arthritic group, but not in the degenerative joint disease group. Copper and ceruloplasmin levels are high significantly correlated in all the groups. This parallel enhancement of serum copper and ceruloplasmin in R.A. is commented in view of a possible protective role of endogenous copper and/or ceruloplasmin in inflammation.

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

1 The concentration of copper in serum and liver was determined by atomic absorption spectrophotometry in a study performed on normal rats of either sex and in female rats with carrageenan-induced pleurisy. 2. In the normal animal, total serum copper concentration is significantly higher in female rats, and appears to be higher in mature animals in females. 3 In normal rats of either sex, liver copper concentration undergoes daily variations which are inversely related to the weight of the organ and which leave constant the total amount of metal in the liver. Moreover a day to day non-cyclic variability of liver copper concentration and liver weight was observed. 4 This first set of data showed that comparison with time control was essential. 5 In the inflamed rat, a significant rise of total serum copper at 22, 48 and 72 h after the induction of inflammation was observed. From 96 h up to 240 h post-injection no significant differences were evident. 6 Total liver copper content did not change in the inflamed rats. 7 During acute inflammation in the rat, the copper needed for the increased synthesis of caeruloplasmin is supplied without depletion of liver copper stores.

Copper and ceruloplasmin (Cp) concentrations during the acute inflammatory process in the rat

We have measured the concentration of copper and ceruloplasmin in serum of rats with carrageenan foot-oedema and in serum and exudate of rats with carrageenan pleurisy. Both serum copper and ceruloplasmin were found to increase in both models of inflammation. In these experimental conditions we have shown a strong positive correlation between copper and ceruloplasmin, in the serum of both normal and inflamed rats.

Anti-inflammatory properties of copper implants in the rat paw edema: a preliminary study

Metallic copper has been shown to possess anti-inflammatory activity in the carrageenan foot paw edema of the rat, when applied in the form of an implant. The implant was installed two months before the edema was induced. It is postulated that the anti-inflammatory activity is due to dissolved copper from the implant.