Monocyte zinc and in vitro prostaglandin E2 and interleukin-1 beta production by cultured peripheral blood monocytes in patients with Crohn's disease

The value of methods to determine zinc deficiency in patients with Crohn's disease

BACKGROUND

The serum zinc concentration is frequently applied for the assessment of zinc deficiency, but this concentration is also influenced by other factors. The aim of this study was to compare various methods of assessing the zinc status in patients with Crohn' s disease.

METHODS

Serum levels of zinc, serum alkaline phosphatase activity, and zinc in various types of cells were related to factors potentially inducing zinc deficiency: the number of liquid stools, weight loss, bowel resection, and the extent and severity of inflammation.

RESULTS

Thirty-one patients with more or less active Crohn's disease were included. In 68% of these patients the serum zinc concentration was less than the reference level, and it was correlated with the extent of bowel resection and the van Hees Index but not with the Crohn's Disease Activity Index. Serum alkaline phosphatase activity was correlated with bowel resection. Zinc in blood cells was poorly correlated with factors inducing zinc deficiency.

CONCLUSION

A decrease of serum zinc concentration is frequently seen in active Crohn's disease. This study suggests that the determination of zinc in blood cells is not superior to the determination of the serum zinc concentration and serum alkaline phosphatase activity.

Effects of captopril and enalapril on zinc metabolism in hypertensive patients

OBJECTIVE

To investigate the effect of chronic captopril and enalapril treatment on zinc metabolism in hypertensive patients by assessing zinc levels in serum, urine and monocytes.

METHODS

Patients with newly diagnosed essential hypertension were randomly divided into two treatment groups: those treated with captopril only (n = 16) and those treated with enalapril only (n = 18). Ten healthy subjects served as controls. Prior to the start of treatment and again 6 months later, zinc was assessed in the serum, in urine collected over 24 hours, and in peripheral blood monocytes.

RESULTS

Significant enhancement of 24-hour urinary zinc excretion (micrograms/24 hour) after 6 months of treatment was observed only in the captopril-treated group (p < 0.01). However, intramonocytic zinc levels decreased significantly in both of the treated groups over the same period (p < 0.01 and P < 0.04 in the captopril- and enalapril-treated groups, respectively).

CONCLUSION

Treatment of hypertensive patients with captopril or enalapril may result in zinc deficiency.

Elevated interleukin 6 is induced by prostaglandin E2 in a murine model of inflammation: possible role of cyclooxygenase-2

Injection of mineral oils such as pristane into the peritoneal cavities of BALB/c mice results in a chronic peritonitis associated with high tissue levels of interleukin 6 (IL-6). Here we show that increased prostaglandin E2 (PGE2) synthesis causes induction of IL-6 and that expression of an inducible cyclooxygenase, Cox-2, may mediate this process. Levels of both PGE2 and IL-6 are elevated in inflammatory exudates from pristane-treated mice compared with lavage samples from untreated mice. The Cox-2 gene is induced in the peritoneal macrophage fraction isolated from the mice. A cause and effect relationship between increased macrophage PGE2 and IL-6 production is shown in vitro. When peritoneal macrophages are activated with an inflammatory stimulus (polymerized albumin), the Cox-2 gene is induced and secretion of PGE2 and IL-6 increases, with elevated PGE2 appearing before IL-6. Cotreatment with 1 microM indomethacin inhibits PGE2 production by the cells and reduces the induction of IL-6 mRNA but has no effect on Cox-2 mRNA, consistent with the fact that the drug inhibits catalytic activity of the cyclooxygenase but does not affect expression of the gene. Addition of exogenous PGE2 to macrophages induces IL-6 protein and mRNA synthesis, indicating that the eicosanoid stimulates IL-6 production at the level of gene expression. PGE2-stimulated IL-6 production is unaffected by addition of indomethacin. Taken together with the earlier finding that indomethacin diminishes the elevation of IL-6 in pristane-treated mice, the results show that PGE2 can induce IL-6 production in vivo and implicate expression of the Cox-2 gene in the regulation of this cytokine.

Zinc modulates mononuclear cellular calcitriol metabolism in peritoneal dialysis patients

Zinc has long been known to play a role in maintaining immunologic function. Hypozincemia, however, is common in patients with end-stage renal disease (ESRD) treated with continuous ambulatory peritoneal dialysis (CAPD). We previously demonstrated that zinc depletion limits the ability of animals to achieve maximum circulating calcitriol levels in response to the stress of calcium or phosphorus depletion. It was unclear, however, whether changes in the circulating levels of calcitriol in these settings was associated with a direct effect on renal 1-alpha hydroxylase activity, or whether the zinc dependence of the stimulated calcitriol response involved an integrated systemic response in intact animals. In addition it was unclear whether circulating zinc levels or zinc nutritional status modified calcitriol metabolism in humans. To better understand the role zinc plays in the immune response in patients with ESRD, we studied IL-1, calcitriol and tumor necrosis factor-alpha production by mononuclear cells from blood and peritoneal effluents of 22 patients with ESRD treated with CAPD. Macrophages from peritoneal effluents and peripheral blood mononuclear cells were isolated and pulsed with phytohemagglutinin in medium to which different concentrations of zinc chloride, copper chloride, and carbonyl cyanide p-(trifluoromethoxy)-phenyl-hydrazone (FCCP), an inhibitor of mitochondrial function were added. Supernatant interleukin-1, calcitriol, and tumor necrosis factor-alpha levels were subsequently measured. We demonstrated a zinc concentration dependent increase in stimulated IL-1 alpha and -beta, and TNF-alpha release in both peripheral mononuclear cells and peritoneal macrophages from patients with ESRD treated with CAPD. The effect is zinc specific, as it is not reproduced by copper or chloride supplementation. A zinc concentration dependent increase in peritoneal macrophage calcitriol release was also noted. FCCP blocked the cellular production of IL-1 alpha, IL-1 beta, and TNF-alpha, but had little effect on zinc-induced stimulated mononuclear cell supernatant calcitriol levels. The different shape of the zinc dose response curve, and the lack of correlation between paired IL-1 and calcitriol supernatant levels suggests the effect of zinc on mononuclear cellular cytokine and calcitriol production is mediated through different pathways.

Associations among prostaglandin F2alpha, plasma zinc, copper and iron concentrations and fetal loss in cows and mares

The objective of this study was to test the hypothesis that PGF2alpha is associated with abortion and changes in plasma Zn, Cu, and Fe concentrations in cows and mares in their first trimester of pregnancy. Eleven pregnant cows were infused with endotoxin (n = 5) or endotoxin plus an inhibitor of cycloxygenase, flunixin meglumine (n = 6). Blood was collected over a 5-d period. Additionally, 4 mares were treated every 24 h with cloprostenol sodium and blood was collected hourly until abortion. Plasma Zn, Cu, and Fe were determined. Three of five cows treated with endotoxin aborted, but none of the six cows treated with endotoxin and flunixin meglumine aborted. Aborting cows had lower plasma Zn (P = 0.048) over the 5-d study period compared with the nonaborting cows. The changes in Zn corresponded to release of PGF2alpha. All 4 mares aborted and plasma Zn concentrations were lower (P = 0.008) and Cu/Zn was higher (P = 0.02) 12 h after cloprostenol treatment. Plasma Zn may be a useful biomarker for risk of spontaneous abortion, and the decline in plasma Zn may be caused by PGF2alpha.

Interleukin-1 alpha (IL-1 alpha) production by alveolar macrophages in patients with acute lung diseases: the influence of zinc supplementation

The relationship between zinc treatment and interleukin-1 alpha (IL-1 alpha) production by cultured alveolar macrophages (AM) in patients with pulmonary tuberculosis and bacterial pneumonia was investigated. AM (1 x 10(6) cells/ml) from 6 patients with pulmonary tuberculosis, 7 patients with bacterial pneumonia and 4 healthy volunteers were cultured with either two different concentrations of zinc chloride (Znl = 1 microgram/ml and Zn2 = 5 micrograms/ml) or cell culture media alone (control) for an initial period of 6 hours and then stimulated with 3 different immunomodulator agents and reincubated for a further 24 h. IL-1 alpha in culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA). In the absence of Znl or Zn2 Polyinosinic:Polycytidylic acid (Poly I:C 1 microgram/ml), Lipopolysaccharide (LPS 100 ng/ml) and Tumour necrosis factor-alpha (TNF-alpha 10 ng/ml) significantly increased the production of IL-1 alpha from AM in both patients and healthy subjects (p < 0.001) compared to control (media only). Zn1 and Zn2 significantly increased the production of IL-1 alpha (p < 0.001) in culture supernatants in the absence of either Poly I:C, LPS or TNF-alpha in patients but not in healthy group. In contrast, the presence of LPS or TNF-alpha significantly reduced Zn1 or Zn2-stimulated release of IL-1 alpha from AM in patients and healthy subjects (p < 0.01). However, Poly I:C decreased only Zn1-stimulated release of IL-1 alpha. These results suggest that zinc can regulate the production of IL-1 alpha from AM in patients with pulmonary tuberculosis or bacterial pneumonia.

Effect of oral zinc supplementation on metallothionein and superoxide dismutase concentrations in patients with inflammatory bowel disease

Oxygen-derived free radicals may contribute to intestinal tissue damage in inflammatory bowel disease. The concentrations of metallothionein and superoxide dismutase, two copper and zinc containing proteins involved in the scavenging of free radicals; were previously found to be decreased in the intestinal mucosa of patients with this disorder. The plasma zinc concentration is often decreased also in these patients. Since zinc is reported to be an efficient inducer of metallothionein synthesis, and probably of superoxide dismutase, we evaluated the effect of oral zinc supplementation on metallothionein and superoxide dismutase levels in patients with inflammatory bowel disease. Fourteen patients with inactive to moderately active inflammatory bowel disease received oral zinc supplementation (300 mg zinc aspartate, equal to 60 mg elemental zinc per day) for 4 weeks in a placebo-controlled double-blind cross-over trial. The plasma zinc concentration of these patients was low at the start of the study (12.2 +/- 1.7 mumol/L, P < 0.05), when compared to that of 22 healthy controls (13.6 +/- 2.3 mumol/L), but increased (P < 0.05) towards the levels of controls during the supplementation period (13.3 +/- 2.5 mumol/L). The concentrations of metallothionein and superoxide dismutase in plasma and in erythrocytes did not change in relation to the supplementation. The metallothionein concentration in both inflamed and non-inflamed intestinal mucosa was slightly higher after zinc supplementation but the superoxide dismutase concentration in the tissue was not altered. The histological inflammation score of intestinal biopsies, plasma albumin levels, and the disease activity index of the patients did not change during the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of zinc therapy on natural killer cell activity in inflammatory bowel disease

Disturbances in zinc metabolism have been documented in patients with inflammatory bowel disease. In this study we evaluated the effect of in vivo treatment with zinc on the in vitro natural killer cell activity in thirteen inflammatory bowel disease patients, with stable disease and mild-moderate disease activity, in a double-blind randomized cross-over trial. The results of our study show a long-lasting effect of in vivo zinc administration, which decreased peripheral blood natural killer cell activity in inflammatory bowel disease.

Correction of cellular zinc depletion by oral zinc supplementation in elderly subjects

Immune function declines with age, and has been implicated in the increased incidence of cancer and infections in the elderly. In this hospital, many elderly patients have evidence of zinc depletion. In the present study, we supplemented those elderly patients who had depressed polymorphonuclear cell (PMNC) zinc levels with 135 mg oral zinc sulphate for 4 weeks. Plasma and PMNC zinc increased markedly but the percentage of peripheral blood T-lymphocytes expressing the surface markers CD3, CD4 and CD8 were unchanged. Plasma concentrations of vitamins A and E also remained constant. This study confirms the 25-30% incidence of cellular zinc depletion in this patient population, and demonstrates that zinc concentrations can be brought back to within normal limits by oral zinc supplements, but with no effect on T-cell phenotypes.

The effect of dietary vitamin E deficiency on plasma zinc and copper concentrations

Vitamin E and zinc have a number of functions in common, including membrane stabilisation, antioxidant function and modulation of prostaglandin metabolism. Previous studies have shown vitamin E malabsorption during zinc depletion and it appears that there is an interaction between the two nutrients. In this study we have investigated whether vitamin E deficiency affects zinc and copper concentrations in experimental animals. Male Wistar rats were maintained on a vitamin E deficient diet for either 6 or 10 months. At the end of the experimental period all animals had undetectable plasma vitamin E levels and increased red cell fragility. Plasma zinc concentrations were significantly reduced in all vitamin E deficient animals compared to control rats (p<0.002) and copper levels were reciprocally elevated (p<0.002). It appears likely that decreased zinc levels may represent redistribution of circulating zinc to tissues and cells as a secondary antioxidant, or for membrane stabilisation or prostaglandin synthesis.