Concentrations of copper, zinc and various elements in serum of patients with bronchial asthma

J. Trace Elements Med. Biol. 14, pp. 88 - 91

ournal o

June 2000

Trace Elements

Clinical Study

© 2000 Urban & Fischer

Concentrations of copper, zinc and various elements in serum of patients with bronchial asthma H. Vural, K. Uzun*, E. Uz**, A. Kowigit, A. (~igli** and O. Akyol **,1 Department of Biochemistry, Harran University School of Medicine, Urfa, Turkey *Department of Pulmonary Disease, YQz0ncQ Yil University, Faculty of Medicine, Van, Turkey **Department of Biochemistry, In6nQ University Faculty of Medicine, Turgut Ozal Medical Center 44069 Malatya, Turkey

Summary

In this study, serum copper, zinc, magnesium, iron and calcium concentrations were investigated in 40 patients with bronchial asthma (BA) and in 43 healthy subjects. Copper and calcium levels were found to be increased in patients with BA compared to the control group (p<0.001 and p<0.001 respectively). On the other hand, the serum zinc level was significantly lower in healthy subjects (p<0.01). No changes were found in serum magnesium and iron levels in patients with BA compared to controls. In addition to various elements, certain serum proteins such as albumin, transferrin and ferritin were also assessed to determine whether there was a relationship between the elements and proteins in patients with BA. There was only a significant decrease in albumin concentration in patients with BA (p<0.05). Keyword$: Bronchial asthma, copper, zinc, magnesium, iron, calcium.

(Received JuDy 1998/May 1999)

Introduction

Bronchial asthma (BA) is a the major health problem. It is characterized by chronic inflammation of the bronchi. Several factors have been implicated in the disease pathology and many studies have been carried out to elucidate the possible mechanisms leading to hypersensitivity, reversible obstruction of the airways, the activation of the inflammatory cells, the synthesis of biological mediators and epithelial cell damage. Trace elements exist in very low concentrations in the body, consisting of 0.01% of the total body weight (1). In the case of insufficient intake of these trace elements with the diet, besides 1Reprint requests to: Prof. Dr. OmerAkyol, In6nLi University, Faculty of Medicine, Department of Biochemistry, Turgut Ozal Tip Merkezi, 44069 Malatya, Turkey (E-maih [email protected])

various insignificant pathologic findings, other life-threatening pathologic results may also appear. Magnesium and calcium play multiple dynamic roles in the pulmonary structure and function. When magnesium is deficient, the action of calcium is enhanced. In contrast, an excess of magnesium blocks calcium and vice versa. These interactions are important for patients with respiratory tract diseases because the intracellular influx of calcium causes bronchial smooth-muscle contraction (2). In this way, magnesium deficiency might be associated with increased contractility of smooth muscle cells. Since contractility of bronchial smooth muscle is important in patients with asthma, magnesium deficiency might negatively influence the clinical condition (3). There is increasing evidence that reactive oxygen species can be of particular importance in the pathophysiology of several lung diseases. Reactive oxygen species can even induce an autonomic imbalance between muscarinic receptor-mediated contraction and the beta-adrenergic-mediated relaxation of the pulmonary smooth muscles (4). Therefore, dietary, environmental, and genetic factors which diminish the cellular reducing capacity will increase tissue vulnerability to oxidant stress and are likely to increase the risk of asthma (5). Superoxide dismutases (SODs) are metalloenzymes that efficiently catalyse the dismutation of superoxide ions (02-) into oxygen and hydrogen peroxide. It is widely recognized that these enzymes, which ever present in almost all living organisms, provide a defence system that is essential for their survival under aerobic conditions (6). SOD exists in several different compartments of the cell. The cytosolic enzyme is composed of two similar subunits, both of which contain one equivalent of Cu +2and Zn +2, whereas the mitochondrial enzyme contains Mn +2, similar to the enzyme found in bacteria (7). Catalase is a hemoprotein containing four heme groups (each heme group also has iron in either the ferrous form or ferric). In addition to possessing peroxidase activity, it is able to use one molecule of hydrogen peroxide (H202)

Serum zinc, copper and other related elements in brochial asthma

as a substrate electron donor and another molecule of H202from

89

Statistical calculations

water (8). In addition, iron forms the prosthetic group of catalase, free iron (in Fe +2form) has a potentially oxidant effect because it transfers an electron to molecular oxigen to form superoxide radical (O[) or to H202 to form the hydroxyl radical (OH). This reaction is called the Fenton reaction. All the mechanisms mentioned above suggest that copper, zinc and iron are important metals in oxidant/antioxidant pathways of patients with BA, who are exposed to more free oxygen radicals than normal individuals. This study investigates the hypothesis that, since oxidative injury is a likely contributor to BA, patients

Mean + standard deviation values of all parameters in serum were calculated for patient and control subjects. Student's t-test was used for comparison of means with p<0.05 being considered significant. Linear correlation coefficients for element concentrations were calculated with respect to their mutual relations in sera.

Results

are best able to cope with oxidative stress through inactivation of free radicals. Our aim was to understand whether serum copper, zinc, iron, calcium and magnesium levels change in BA, as those metals are important factors contributing in different ways to bronchial asthma.

Mean serum calcium, magnesium, zinc, copper and iron values of the patients and controls together with p values are given in Table 1. There was no significant difference in the values of magnesium and iron between the BA and the control group (p>0.05 and p>0.05, respectively). The mean concentrations of calcium and copper were found to be significantly high-

Materials and Methods

er (p<0.001 and p<0.001, respectively) and that of zinc lower in BA in comparison to controls (p<0.01). Albumin, transferrin

Patients

and ferritin levels are shown in Table 2. Although there was a significant decrease in serum albumin levels in patients with

The study included 40 patients with BA and 43 healthy peo-

BA (p<0.05), the transferrin and ferritin levels were found to be

ple as controls. The BA group consisted of 22 women and 18 men, the ages of the patients ranged from 18 to 70 years (mean

unchanged (p>0.05 and p>0.05, respectively). In the intracorrelation analysis, only a negative significant correlation was

+ SD; 37.8 + 14.2 years). The control group consisted of 25 women and 19 men; their ages ranged from 21 to 68 years (36.2

found between serum copper and zinc levels in patients with BA (r= - 0.822, p<0.05). This correlation coefficient suggests that

+ 11.7 years). Patients with BA were chosen from among people followed-up by the Department of Pulmonary Diseases of

these two metals interact with each other negatively.

S anliurfa State Hospital. All of the patient's diagnosis were confirmed by clinically and respiratory function examinations as well as biochemical assessments. None of the patients had diabetes mellitus, liver or kidney diseases, infection or thyroid disfunction.

Discussion and Conclusion Recent studies draw attention to the endogenous mediators and functional proteins that might be involved in both inflam-

Sample preparation and analytical methods: Blood samples were taken from subjects in the morning, they were centrifuged

matory and trace metal metabolism. It is clear that profound

at 3000xg for 15 minutes at room temperature. Serum samples

acute and chronic inflammation such as rheumatoid arthritis

were stored at -70°C for the measurement of copper, zinc, iron,

and BA. Zinc, iron and magnesium are important elements in the preservation of immune resistance (10) and both zinc and

magnesium and calcium. All of the materials (glass and plastic) used were throughly cleaned with a hot solution of nitric acid (20%, v/v) for 48 hours and rinsed six times with demineralized water. Serum samples were diluted with deionized, double-dis-

variations in copper and zinc status occur during the course of

copper are required for numerous biochemical functions and for optimal activity of the immune system (11). Zinc also forms the prosthetic group of more than 80 metalloenzymes which play

tilled water for element measurements when needed. For copper, iron and zinc analysis, an Spestr AA 250 Plus Zeeman atomic absorption spectrophotometer (Varian, Australia) was used with a deuterium background correction and additional standard techniques (9). Serum copper, zinc and iron values were expressed in gg/L. Serum calcium, magnesium, albumin, transferrin and ferritin were measured with an automatic bio-

Table 1. Element concentrations (mean + SD) in serum from patients with bronchial asthma Bronchial asthma Control group group (n=40) (n=43)

chemistry analyzer (Hitachi 911 Analyzer, Boehringer Mannheim, Mannheim, Germany) using commercial kits, as recom-

Calcium (mg/L) 100.5 + 3.6 Magnesium (mg/L) 22.0+ 3.0 Zinc (gg/L) 707.0 + 92.3 Copper (gg/L) 1167.6 + 281.2 Iron (gg/L) 816.9 + 441.2

mended by the manufacturer (Boehringer Mannheim). Calcium and magnesium values were expressed as mg/L.

n.s.: non-significant (p>O.05)

94.6 22.5 816.5 855.4 831.8

+ 4.8 + 4.5 + 164.4 +_ 158.2 + 354.1

P values <0.001 n.s. <0.01 <0.001 n.s.

90

H. Vural, K. Uzun, E. Uz, A. Kogyigit, A. (~igli and O. Akyol

Table 2. Concentration (mean + SD) of proteins which are related to Cu, Zn Ca and Mg in patients with bronchial asthma Bronchial asthma Control group group (n=40) (n=43) Albumin (g/dL) 4.62 + 0.30 Transferrin (mg/dL) 205.64 + 58.36 Ferritin (ng/mL) 86.73 + 30.25

4.88_+ 0.21 211.29_+ 55.47 89.12_+23.57

P values

decreased copper availabi.ity to the enzyme pool, reduced synthesis of the enzyme or enzyme inactivation unrelated to the copper cofactor. Human erythrocyte SOD activity was reduced by intentionally feeding a high fructose, marginal-copper diet to

<0.05 n.s. n.s.

men from a wide age range (26). SOD activity than increased again after a period of supplementation (26). Human erythro-

n.s.: non-significant (p>0.05)

cyte SOD activity was also depressed by oral supplementation with zinc, an element that can antagonize copper absorbtion

roles in many metabolic pathways. Similarly, magnesium is the

inflammatory condition and the levels of copper and zinc may

cofactor of approximately 300 cellular enzymes. Zinc plays a crucial role in maintaining cell membrane structure and func-

exist in solid tissues such as the liver and at the sites of inflam-

(27). Although a direct relationship between the severity of the

tion and influences the complement system (12), lysosomal enzyme release and macrophage function (13). A striking decrease in plasma zinc has been reported in various specific conditions

mation, the assay of these trace elements in serum or plasma also has a diagnostic value. Epidemiological evidence suggests that a low dietary intake

such as infections (14), chronic disease of the liver (15) and

of magnesium is associated with impaired lung function, bronchial hyperreactivity and wheezing. It was found that a high

rheumatoid arthritis(16). It has been suggested that the dismutation of superoxide

magnesium intake was associated with improvement in symptom scores, though not in objective measures of airflow or air-

ions, as well as of many metal compounds and non-metal compounds, is catalyzed via a "ping-pong" mechanism in which the metal or the non-metal compound oscillates between two oxidation states (17). In this case, Cu +2 may oscillate between Cu +2 and Cu ~ or between Cu +2 and Cu +3. In the current study, serum copper was found to be elevated while serum zinc levels were found to be lowered. As both metals form the prosthetic group of SOD, any alterations in their level effects activity of the en-

way reactivity, in stable asthmatic subjects (28). We found significantly higher calcium and a nonsignificant decrease in the magnesium levels in patients with BA. Although it is nonsignificant, the latter may aggravate asthmatic symptoms. Recently, there have been a large number of findings obtained on the therapeutic effects of magnesium in asthmatic patients (29, 30). Falker et al found that serum magnesium levels in asthmatics are not significantly different from those of a control nonasth-

zyme. It is debatable whether an increase in the copper level has an impact upon SOD absolption; however, it is clear that a de-

matic population (31). The serum magnesium levels are not clinically useful for predicting the severity of disease. An anoth-

crease in this element impairs the enzyme activity. Such a condition may cause oxidative stress or may further increase the

er research study of different types of asthma in 50 patients re-

existing stress.

ported no significant change in serum magnesium and calcium levels (32). This study is partly in agreement with our study.

In a recent study, plasma copper concentrations were found

As a result, besides many metabolic changes, it can also be

to be significantly elevated in patients with intrinsic asthma as

concluded that changes in the level of trace elements are impor-

compared to healthy controls (18). These results are in agree-

tant for many metabolic processes in bronchial asthma. Further

ment with the data found in the previous studies (19, 20). On the other hand, chronic inflammation events cause a characteristic

studies of the above-mentioned enzyme and trace element relations are needed to understand the details of these processes.

decline in plasma or serum zinc levels in experimental studies (2 I). The explanation of this hypozincemia is the redistribution of pasma zinc in the body. Activation of the phagocytic cells occurs in IgE-mediated allergic reactions, leading to the release of Leucocyte Endogenous Mediator which increases the movement of zinc from plasma to the hepatocytes, decreasing its serum level (22). It appears that hypozincemia plays a role in producing, or at least exacerbating, the allergic diseases (20). Finally, it is well known that zinc deficiency affects the regulation of T-cell lymphocytes, which may play some part in the development of allergies (23). The increase in serum copper associated with a decrease in serum zinc may be explained by their competition either for the same absorbtive binding sites on the intestinal mucosal cells (24) or for a similar protein carrier system. The activity levels of one copper and zinc enzyme, serum extracellular SOD, are known to be decreased with inflammation in rats. It is not known whether this depression results from

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