Abnormal calcium and magnesium stores in erythrocytes and granulocytes from patients with inflammatory connective tissue diseases. Relationship to inflammatory activity and effect of corticosteroid therapy

Metal exposure from amalgam alters the distribution of trace elements in blood cells and plasma

Twenty-seven consecutive patients with health problems associated with dental amalgam were recruited. In spite of thorough medical examinations, there were no diagnoses available. The patient group was dominated by women. A healthy age- and sex-matched control group with dental amalgams without symptoms was also recruited. Metal level monitoring in plasma and nuclear microscopy of isolated individual blood cells were carried out. Significant increases of copper, iron, zinc and strontium were found in patient plasma. There was no significant difference in plasma selenium between the groups. Mercury was significantly increased in patient plasma, although there was overlap between the groups. In erythrocytes a significant increase in calcium and a significant decrease in magnesium, copper, manganese and zinc were found. Calcium, magnesium, manganese and copper increased in patient neutrophil granulocytes. A significant decrease was found for zinc. A conspicuous finding was the presence of measurable mercury in a few of the cells from the patient but not in the control group. Thus, nuclear microscopy of isolated individual blood cells might provide a better diagnostic tool for metal exposure than blood plasma measurements.

Modulation of cytokine production by human mononuclear cells following impairment of Na, K-ATPase activity

Cytokines, including TNF alpha and IL-l beta, are central to the chronic inflammatory process and tissue damage that characterises diseases such as rheumatoid arthritis. The mechanisms responsible for long-term generation of these molecules are poorly understood. We have previously demonstrated impaired activity of Na, K-ATPase, a key enzyme regulating intracellular cation levels, on rheumatoid mononuclear cells. Mimicking this 'defect' on normal mononuclear cells with ouabain has been shown to induce TNF alpha and, in particular, IL-l beta production, whereas IL-6 synthesis was suppressed. A similar pattern of cytokine generation was noted when mononuclear cells were treated with the sodium ionophore, monensin. Induction of cytokine production was related to up-regulation of the appropriate mRNA, although enhanced secretion of processed IL-l beta was also observed. The mechanism underlying these cellular responses appears to involve sodium/calcium exchange across the cell membrane. Impaired Na,K-ATPase activity might promote pro-inflammatory cytokine secretion in patients with rheumatoid arthritis.

Impaired secretion of parathyroid hormone in patients with rheumatoid arthritis: relationship to inflammatory activity

Hypocalcaemic tests, employing infusion of EDTA over 1 h, were performed in 22 patients with rheumatoid arthritis (RA) and 14 healthy controls. The basal levels of calcium and parathyroid hormone (PTH) were not significantly different in the two groups. The RA patients displayed a markedly impaired PTH response during infusion of EDTA compared with the controls although the reduction of plasma ionized calcium was similar. The PTH response was furthermore significantly, inversely, related to the inflammatory activity measured as sedimentation rate (r = 0.65; P less than 0.01), i.e. the more pronounced the inflammation, the less the capacity to secrete PTH. Since secretion of PTH is related to the intracellular calcium concentration of the parathyroid cells, these findings are in line with previous observations of a higher intracellular calcium content in inflammatory disease. They also support the earlier indications of reduced bone turnover in inflammatory arthritides. An insufficient parathyroid function could be one factor contributing to bone disease in these conditions.

Cyclosporin effect on sodium and potassium transport across erythrocytes in rheumatoid arthritis

The aim of the present work was to evaluate the action of cyclosporin (CsA) both in vivo and in vitro on the active sodium transport across the erythrocyte membrane of rheumatoid arthritis (RA) patients. The in vivo study was performed on 20 patients affected by refractory RA and treated with CsA (5 mg/kg/die) or with azathioprine (2 mg/kg/die) before and after 7 days' therapy. The control group was formed of 25 healthy subjects. RA patients before treatment showed increased intra-erythrocyte Na+ concentration and decreased Na+, K+ ATPase activity in comparison with normal subjects. A rise in the activity of the sodium pump and a reduction in the intra-erythrocyte Na+ concentration were observed after cyclosporin treatment, but not after azathioprine. The in vitro study was performed on intact RBCs and on erythrocyte membranes from 15 healthy subjects and from 12 patients affected by classical RA, in the presence or absence of CsA (0.5-1-2 micrograms/ml). CsA (0.5 micrograms/ml) increased the Na+, K+ ATPase activity in intact RBCs and in erythrocyte membranes from both groups of subjects. Intracellular Na+ was decreased only in erythrocytes from RA patients after addition of 0.5 micrograms/ml CsA. A direct action of CsA on the membrane hydrophobic environment of the Na+, K+ ATPase is hypothesized on the basis of the present results.

Metal content of neutrophil granules is altered in chronic inflammation

The mass fraction of certain elements was measured in isolated granulocytes and isolated granulocyte granule fractions from patients with active inflammatory arthritides (N = 6) and healthy controls (N = 6). The patients had significantly increased amounts of Ca in the granulocytes, in the specific and light azurophil granules, but normal Ca amounts in the dense azurophil granules. Sr was below the detection limit in the granulocytes and granule fraction from controls, but it appeared in high concentrations in the granulocytes and all granule fractions from the patients. The patients had considerably increased granulocyte amounts of Mn but only slightly increased Mn concentrations in the specific granules. Mn was not detectable in azurophil granules from patients and controls. A prominent accumulation of Fe was seen in the granulocytes from the patients, together with an Fe accumulation in the specific granules. Fe was below the detection limit in azurophil granules from patients and controls. The patients had reduced granulocyte Zn and reduced amounts of Zn in the dense and light azurophil granules but normal Zn amounts in the specific granules. The results obtained indicate that the granulocyte accumulation of Ca, Sr, and Fe observed during chronic inflammation is associated with corresponding granule accumulation of these metals; the considerable Mn accumulation in granulocytes during inflammation is not localized in their granules; and the granule subpopulations differ in their capacity to store certain metals.

Chemiluminescence of polymorphonuclear leukocytes and whole blood during acute bacterial infection

The purpose of this study was to follow the changes in oxidative metabolism of polymorphonuclear leukocytes (PMN) and whole blood, during and after an acute bacterial infection, in otherwise healthy individuals, with the hypothesis that the majority of the subnormal activities found at clinical investigation of PMN functions in this respect, as part of the investigation of individuals with increased susceptibility to bacterial infections, is explained by subclinical infections or consequences of recent infections. 10 patients were followed from the day of admission and up to 80 days after the acute illness. Luminol- but not lucigenin-enhanced chemiluminescence (CL) of PMN was increased during the febrile period and normalized in parallel with normalization in body temperature. Both luminol- and lucigenin-enhanced CL were enhanced in whole blood during the period of fever. Subnormal activities of luminol- or lucigenin-enhanced CL were only seen sporadically. We conclude that the oxidative metabolism of PMN, as measured by lucigenin-enhanced CL, is virtually unaffected cause of the increased luminol-enhanced CL during the acute illness is suggested to be due to the increase mobilization of myeloperoxidase.

Decreased NA+, K+-ATPase activity in erythrocyte membrane from rheumatoid arthritis patients

The activity of the plasma membrane Na+/K+-ATPase and cellular sodium (Nai) and potassium (Ki) content were analysed in RBCs from 15 rheumatoid arthritis (RA) and 30 reference subjects (11 healthy controls, 12 osteoarthritis and 7 gouty patients). Na+/K+-ATPase activity was determined by measuring the inorganic phosphate (Pi) released by incubation in a reaction medium in the presence and absence of K ions or ouabain. Nai and Ki were measured with an ion-selective electrode analyser on the hemolysates, after washing the RBCs in 110 mM MgCl2. The Na/K-ATPase activity was significantly lower in RA patients than in both healthy controls and patients with osteoarthritis or gout. A slight but significant increase in Nai was observed in rheumatoid subjects. It is hypothesized that the decrease in the Na+/K+-ATPase activity in RA may be the result of a defective expression of membrane proteins, which is probably related to the altered cell sensitivity observed.

Increase of adenylate cyclase catalytic-unit activity by dexamethasone in rat osteoblast-like cells

Glucocorticoids are known to increase the cyclic AMP response to parathyroid hormone (PTH) in cultured bone organs or bone cells. Using the osteoblast-like cell line ROS 17/2.8, which possesses receptors for both PTH and glucocorticoids, we investigated which component of the complex hormone receptor-guanine nucleotide regulatory unit--adenylate cyclase was affected by dexamethasone treatment. In response to PTH, isoproterenol or forskolin, a compound that is supposed to act directly on the catalytic unit, cyclic AMP production by intact cells and adenylate cyclase activity in purified plasma membrane were markedly increased by dexamethasone. Whereas NaF, guanosine 5'-[beta gamma-imido]triphosphate and Mn/ stimulated adenylate cyclase activity were similarly enhanced in membranes isolated from glucocorticoid-treated cells, the activity of the stimulatory guanine nucleotide regulatory unit, as assessed by reconstitution into membranes from the CYC- clone, which is genetically devoid of this component, was not altered. Thus in osteoblast-like cells dexamethasone appears to increase cyclic AMP synthesis by influencing the catalytic unit. Moreover, since it has been reported that glucocorticoids may produce changes in cell calcium metabolism, we evaluated cytoplasmic free Ca2+ concentration ([Ca2+]i) and intracellular Ca2+ stores mobilizable by the bivalent-cationophore ionomycin, by using the intracellular fluorescent indicator Quin-2. The results indicated that dexamethasone treatment did not influence [Ca2+]i but markedly decreased ionomycin-releasable Ca2+ stores.

Reduced zinc in peripheral blood cells from patients with inflammatory connective tissue diseases

By the use of the nuclear microprobe technique, the concentrations of zinc in isolated erythrocytes, platelets, and granulocytes were measured in patients with rheumatoid arthritis, other inflammatory arthritides, and scleroderma. Markedly reduced cellular zinc values were found compared to those measured in healthy subjects. No relation was found to inflammatory activity or disease duration. Plasma zinc was reduced in the majority of the patients and was negatively correlated to the inflammatory activity estimated by ESR and serum orosomucoid. No relation was found between total zinc values in plasma or cells or disease duration. Corticosteroid therapy was instituted in a number of the patients with inflammatory arthritides and induced a significant elevation of total zinc in all cell types, although normalization was not achieved. Plasma zinc values remained unchanged during the treatment.