Lymphocyte and granulocyte function in zinc-treated and zinc-deficient hemodialysis patients

Zinc deficiency as a possible risk factor for increased susceptibility and severe progression of Corona Virus Disease 19

The importance of Zn for human health becomes obvious during Zn deficiency. Even mild insufficiencies of Zn cause alterations in haematopoiesis and immune functions, resulting in a proinflammatory phenotype and a disturbed redox metabolism. Although immune system malfunction has the most obvious effect, the functions of several tissue cell types are disturbed if Zn supply is limiting. Adhesion molecules and tight junction proteins decrease, while cell death increases, generating barrier dysfunction and possibly organ failure. Taken together, Zn deficiency both weakens the resistance of the human body towards pathogens and at the same time increases the danger of an overactive immune response that may cause tissue damage. The case numbers of Corona Virus Disease 19 (COVID-19) are still increasing, which is causing enormous problems for health systems and economies. There is an urgent need to reduce both the number of severe cases and the resulting deaths. While therapeutic options are still under investigation, and first vaccines have been approved, cost-effective ways to reduce the likelihood of or even prevent infection, and the transition from mild symptoms to more serious detrimental disease, are highly desirable. Nutritional supplementation might be an effective option to achieve these aims. In this review, we discuss known Zn deficiency effects in the context of an infection with Severe Acute Respiratory Syndrome-Coronavirus-2 and its currently known pathogenic mechanisms and elaborate on how severe pre-existing Zn deficiency may pre-dispose patients to a severe progression of COVID-19. First published clinical data on the association of Zn homoeostasis with COVID-19 and registered studies in progress are listed.

Lessons Learned from Experimental Human Model of Zinc Deficiency

Zinc is an essential element for humans, and its deficiency was documented in 1963. Nutritional zinc deficiency is now known to affect over two billion subjects in the developing world. Conditioned deficiency of zinc in many diseases has also been observed. In zinc-deficient dwarfs from the Middle East, we reported growth retardation, delayed sexual development, susceptibility to infections, poor appetite, and mental lethargy. We never found a zinc-deficient dwarf who survived beyond the age of 25 y. In an experimental model of human mild zinc deficiency, we reported decreased thymulin (a thymopoietic hormone) activity in Th1 cells, decreased mRNAs of IL-2 and IFN-gamma genes, and decreased activity of natural killer cells (NK) and T cytotoxic T cells. The effect of zinc deficiency on thymulin activity and IL-2 mRNA was seen within eight to twelve weeks of the institution of zinc-deficient diet in human volunteers, whereas lymphocyte zinc decreased in 20 weeks and plasma zinc decreased in 24 weeks after instituting zinc-deficient diet. We hypothesized that decreased thymulin activity, which is known to proliferate Th1 cells, decreased the proliferation differentiation of Th1 cells. This resulted in decreased generation of IL-2 and IFN-gamma. We observed no effect in Th2 cell function; thus, zinc deficiency resulted in an imbalance of Th1 to Th2 function resulting in decreased cell-mediated immunity. Zinc therapy may be very useful in many chronic diseases. Zinc supplementation improves cell-mediated immunity, decreases oxidative stress, and decreases generation of chronic inflammatory cytokines in humans. Development of sensitive immunological biomarkers may be more sensitive than an assay of zinc in plasma and peripheral blood cells for diagnosis of marginal zinc deficiency in human.

Chelation of Free Zn²⁺ Impairs Chemotaxis, Phagocytosis, Oxidative Burst, Degranulation, and Cytokine Production by Neutrophil Granulocytes

Neutrophil granulocytes are the largest leukocyte population in the blood and major players in the innate immune response. Impaired neutrophil function has been reported in in vivo studies with zinc-deficient human subjects and experimental animals. Moreover, in vitro formation of neutrophil extracellular traps has been shown to depend on free intracellular Zn(2+). This study investigates the requirement of Zn(2+) for several other essential neutrophil functions, such as chemotaxis, phagocytosis, cytokine production, and degranulation. To exclude artifacts resulting from indirect effects of zinc deprivation, such as impaired hematopoietic development and influences of other immune cells, direct effects of zinc deprivation were tested in vitro using cells isolated from healthy human donors. Chelation of Zn(2+) by the membrane permeable chelator N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine (TPEN) reduced granulocyte migration toward N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLF) and IL-8, indicating a role of free intracellular Zn(2+) in chemotaxis. However, a direct action of Zn(2+) as a chemoattractant, as previously reported by others, was not observed. Similar to chemotaxis, phagocytosis, oxidative burst, and granule release were also impaired in TPEN-treated granulocytes. Moreover, Zn(2+) contributes to the regulatory role of neutrophil granulocytes in the inflammatory response by affecting the cytokine production by these cells. TPEN inhibited the lipopolysaccharide-induced secretion of chemotactic IL-8 and also anti-inflammatory IL-1ra. In conclusion, free intracellular Zn(2+) plays essential roles in multiple neutrophil functions, affecting extravasation to the site of the infection, uptake and killing of microorganisms, and inflammation.

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.

Zinc, its biological role and use in dermatology

This literature review detines the biological role ot zinc in the human body, immune homeostasis and skin physiology as well as pathophysiology ot skin diseases. It describes the current range ot systemic and topical zinc preparations and their pharmacological characteristics. The review also describes skin diseases that may be treated with the use ot zinc preparations on a grounded basis, and discloses the clinical experience ot the use ot these drugs described in the world literature. It sets out certain recommendations tor using zinc preparations in clinical practice.

Essential trace element status and clinical outcomes in long-term dialysis patients: a two-year prospective observational cohort study

BACKGROUND & AIMS

Essential trace elements are involved in many biological processes for normal cell function including immunological defense against oxidation and infection. Deficiency of these elements generally leads to illness or even death in the general population. Therefore, we investigated the predictive values of trace element status on clinical outcomes in dialysis patients, who are more prone to trace element deficiency.

METHODS

We enrolled 111 prevalent patients on maintenance dialysis from a Taipei tertiary-care referral hospital and measured serum levels of selenium, copper, and zinc. Patients were followed for 2 years or until death or withdrawal.

RESULTS

Multivariate Cox regression analysis indicated that patients with diabetes mellitus (HR, 2.162 [95% CI, 1.105-4.232], p=0.024), prior stroke (HR, 3.876 [95% CI, 1.136-13.221], p=0.030), and zinc deficiency (HR, 0.979 [95% CI, 0.966-0.992], p=0.002) were more likely to be hospitalized for infectious diseases. Furthermore, beyond traditional risk factors, such as old age and hypoalbuminemia, multivariate Cox regression also indicated that lower serum level of zinc independently predicts overall mortality (HR, 0.973 [95% CI, 0.948-0.999], p=0.046).

CONCLUSIONS

In long-term dialysis patients, the serum level of zinc was an independent predictor of future hospitalization due to infectious diseases and of overall mortality.

PREFABL: predictors of failure of antibiotic locks for the treatment of catheter-related bacteraemia

BACKGROUND

Antibiotic lock (ABL) solutions can effectively treat catheter-related bacteraemia (CRB) without the need for catheter exchange. This approach does not increase secondary infectious complications. We evaluated the risk factors that contribute to failure when CRB is treated with ABLs and systemic antibiotics in paediatric haemodialysis patients.

METHODS

A retrospective chart review of 72 children on haemodialysis between January 2004 and June 2006 was performed. We evaluated risk factors for ABL treatment using patients' characteristics, CRB/catheter characteristics and patients' biochemical profiles. The first CRB of each catheter was included in the statistical analysis. Our end points were outcome at 2 weeks of treatment and at 6 weeks following treatment. Compound symmetry covariance structure was employed for statistical analysis.

RESULTS

We treated 149 CRB in 50 patients. The incidence was 3.4 CRB/1000 catheter days. Thirty CRB failed to be cleared with the use of ABL and systemic antibiotics at 2 weeks of treatment (30/149, 20 vs 80%, P < 0.001). Twenty-four of these catheters required exchange. Thirty-nine of the treated catheters got re-infected within the next 6 weeks (39/125, 31 vs 69%, P < 0.001). CRB aetiology was the only statistically significant independent variable for 2-week outcome (P = 0.033). Coagulase-negative Staphylococcus CRB had higher odds of being cleared at 2 weeks compared with other CRB aetiologies. For the 6-week outcome, the statistically significant independent variables in the final model included age (P = 0.048) and serum phosphorous level (P < 0.001). Younger age and higher serum phosphorous levels were independent risk factors for failure at 6 weeks with re-infection. Area under the receiver operating characteristic (ROC) curve for the model of the 2-week outcome was 0.736 with the percentage of correct predictions at 81.2%. Area under the ROC curve for the model of the 6-week outcome was 0.689 with the percentage of correct predictions at 75.5%.

CONCLUSIONS

CRB can effectively be treated with ABLs and systemic antibiotics. CRB aetiology is the only independent variable of early treatment failure. Younger age and higher serum phosphorous levels are independent risk factors for re-infection at 6 weeks.

Serum phosphate levels and risk of infection in incident dialysis patients

BACKGROUND AND OBJECTIVES

Hyperphosphatemia is highly prevalent in dialysis patients and may be associated with immune dysfunction. The association of serum phosphate level with infection remains largely unexamined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In an incident cohort of 1010 dialysis patients enrolled from 1995 to 1998 and treated in 80 US clinics, the association of phosphate level (low <3.5; normal 3.5 to 5.5; high >5.5 mg/dl) at baseline and during follow-up with the risk for incident inpatient and outpatient infection-related events was examined. Infectious events were identified from US Renal Data System data (mean follow-up 3.3 yr). Incidence rate ratios for all infections, sepsis, respiratory tract infections, and osteomyelitis were obtained using multivariable Poisson models, adjusting for potential confounders (age, race, gender, smoking, comorbidity, and laboratory values).

RESULTS

Infections of any type (n = 1398) were more frequent among patients with high phosphate levels at baseline, relative to normal; this association was not changed by adjustment for parathyroid hormone level. Similarly, high versus normal baseline phosphate was associated with increased risk for sepsis and osteomyelitis but not respiratory tract infections. Associations with calcium were generally NS, and results with calcium-phosphate product mirrored the phosphate results.

CONCLUSIONS

High phosphate levels may be associated with increased risk for infection, contributing further to the rationale for aggressive management of hyperphosphatemia in dialysis patients.

Intravenous iron therapy in end-stage renal disease

Intravenous iron therapy is instrumental in the management of anemia in patients with end-stage renal disease (ESRD). Iron is available in several different preparations, with slight differences in the pharmacology of each. Given the importance of intravenous iron in the management of these patients, clinicians should be aware of the potential risks associated with it. Intravenous iron has effects on host immunity that raise concerns about clinical infection risk. Iron preparations appear to increase oxidative stress in these patients, which has important implications for cardiovascular disease states. Lastly, the effects of intravenous iron on liver disease are largely unknown.

Hormonal adjuvants for the treatment of renal anaemia

Hormonal adjuvants, besides being erythropoietic agents, broaden the spectrum of therapeutic options for the treatment of the anaemia of chronic kidney disease (CKD). Lowering elevated parathyroid hormone levels by oral calcium supplementation and phosphate restriction, by varying dialysate calcium concentrations, by administration of vitamin D3 derivatives and, in the near future, by treatment with calcimimetics may prove efficient in some patients to fight extensive requirements of erythropoietic agents. Clinical evidence for a principal role of secondary hyperparathyroidism in resistance to erythropoietin, however, is lacking. Active vitamin D3 derivatives, in addition to their beneficial effects on secondary hyperparathyroidism, appear to exert a direct, stimulatory action on erythroid precursor cells and possibly also an inhibitory action on collagen synthesis by bone marrow stromal cells. Growth hormone (GH) induces insulin-like growth factor (IGF)-1, which in turn counteracts apoptosis similarly to erythropoietin, and fosters proliferation of burst- and colony-forming units-erythroid (BFU-E, CFU-E). If erythropoietic agents improve survival of CKD patients, a similar benefit should apply for strategies that increase synthesis and bioavailabilty of IGF-1. The latter appears to be reduced in CKD patients, and zinc supplementation potentially enhances it via an increase in free IGF-1. Finally, androgens also exert anti-anaemic effects. Nandrolone decanoate constitutes the only androgen currently applicable for selected male dialysis patients over the age of 50 years. It should not be given to women, however, because of serious side effects. Collectively, hormonal interventions offer the potential to reduce requirements of erythropoietic agents, and some may also improve physical performance.

Zinc and skin health: overview of physiology and pharmacology

BACKGROUND

Zinc is known to have a critical role in overall human physiology, which likely explains many of its therapeutic uses for the last several thousand years. The specific roles zinc plays in skin health and function are less widely known yet are likely just as critical based on the manifestations of dietary zinc deprivation, which include moderate to severe dermatitis.

OBJECTIVE

To provide a critical review of the scientific literature as to the physiologic importance of zinc to skin, the biochemical basis for these effects, and pharmacologic aspects of zinc therapeutics.

RESULTS AND CONCLUSIONS

Skin is in a continual state of renewal, placing a high demand on zinc-based enzymes and proteins that direct this process. The importance of zinc physiologically is especially evident in studies of wound healing and inflammation reduction. During these processes, the high needs for zinc can be supplemented externally, generally increasing the rates of the natural processes. Topical zinc delivery involves the pharmacologic optimization of zinc delivery, often mediated by the solubility of the zinc material and interactions within the product matrix.

Intravenous iron and the risk of infection in end-stage renal disease patients

Oral iron is typically insufficient for the iron deficiency of hemodialysis patients. Intravenous (IV) iron is well tolerated by most patients and non-dextran-containing iron preparations are associated with few allergic reactions. However, there is the potential for an increased risk of infection with IV iron that appears to increase bacterial growth as well as inhibit the host's innate immune response to bacterial infection. Clinical studies suggest a link between iron therapy and infection. Practicing nephrologists should be aware of this issue, but should not hesitate to use IV iron in iron-deficient patients while avoiding the development of iron overload and administration of iron to patients who have active infection.

Neutrophil beta(2)-microglobulin and lactoferrin content in renal failure patients

Multiple dysfunctions of polymorphonuclear leukocytes (PMNLs) contribute significantly to the increased morbidity and mortality among patients with end-stage renal disease. In the present study, we measured the PMNL content of beta(2)-microglobulin (beta(2)m) and lactoferrin in different states of renal insufficiency and after kidney transplantation. PMNLs were lysed ultrasonically and, after centrifugation, both proteins were assayed in the supernatant by enzyme-linked immunosorbent assay technique. Despite marked differences in plasma beta(2)m levels, no significant difference in PMNL content of beta(2)m and lactoferrin could be shown among the groups analyzed. There was also no correlation between plasma beta(2)m level and PMNL beta(2)m content. In control subjects, as well as in renal allograft recipients with a well-functioning graft, PMNL beta(2)m level correlated positively with PMNL lactoferrin level (pooled data, r = 0.55; P < 0.001; n = 55). Both proteins are considered to colocalize in peroxidase-negative PMNL granules. However, no correlation was found in the azotemic and uremic patient groups. Standard immunofluorescence staining of control PMNLs showed a cytoplasmic granular distribution of both granule proteins. However, in PMNLs of uremic patients, lactoferrin shifted to a perinuclear localization. PMNLs obtained from uremic individuals failed to elicit an increase in lactoferrin release after stimulation with the chemotactic peptide f-Met-Leu-Phe compared with PMNLs obtained from healthy volunteers. These data indicate abnormalities in uremic patients of PMNL granule lactoferrin content and release that are reversible after successful renal transplantation.

Oyster metallothionein as an oxyradical scavenger: implications for hemocyte defense responses

In order to better understand the interplay between metallothionein (MT) and reactive oxygen species (ROS) in oyster hemocytes, studies of the hydrogen peroxide (H2O2) scavenging properties of MT were carried out in a cell-free system. Mammalian MT is involved in protection against oxidative stress by virtue of its ability to scavenge free radicals; therefore, the H2O2 scavenging potentials of Crassostrea virginica and rabbit MTS were compared. Oyster and rabbit MTs showed similar dose-dependent suppression of H2O2-stimulated, luminol-augmented chemiluminescence (CL); the EC50 for CL (25 microM H2O2) was approximately 1.0 microM MT for both species. The interaction of ROS with MT in hemocytes could play a role in protection of the cells and surrounding tissues from oxidants associated with antimicrobial responses. Mobilization of bound zinc from MT by hemocyte-derived ROS may produce aberrant regulatory effects on various cellular processes. The data suggest that MT may be involved in immunoregulatory pathways in oyster hemocytes as a result of its ability to scavenge antimicrobial ROS.

Effect of non-toxic mercury, zinc or cadmium pretreatment on the capacity of human monocytes to undergo lipopolysaccharide-induced activation

1. Metal salts can inhibit cell activity through direct toxicity to critical cellular molecules and structures. On the other hand, they can also change cell behaviour by inducing specific genes (including genes encoding members of the metallothionein [MT] gene family). Therefore, transition metals may affect cell functions either by acting as a toxin, or by transmitting or influencing signals controlling gene expression. 2. To explore the latter possibility, we measured the ability of low, non-toxic metal pretreatment to alter immune cell behaviour. We previously found that pretreatment of human monocytes with zinc induces metallothionein gene expression and alters their capacity to undergo a bacterial lipopolysaccharide-induced respiratory burst. We showed here that cadmium and mercury salts, at concentrations that exert no discernible toxicity, inhibit activation of human monocytic leukemia (THP-1) cells. CdCl2 1 microM, ZnCl2 20-40 microM or HgCl2 2 microM pretreatment for 20 h induced MT-2 mRNA and total MT protein accumulation and had no effect on proliferation potential or metabolic activity, but significantly inhibited the ability of subsequent lipopolysaccharide treatment to induce the oxidative burst, increased adhesion to plastic, and MT-2 and interleukin-1 beta (IL-1 beta) mRNA accumulation. 3. The phenomenon of metal-induced suppression of monocyte activation, at metal concentrations that have no effect on cell viability, has important implications for assessment of acceptable levels of human exposure to cadmium, zinc and mercury.

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.

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.

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.

Interest of zinc determination in leucocyte fractions for the assessment of marginal zinc status

In order to test the sensitivity of leucocyte zinc determination in the assessment of zinc status, an isolation procedure of mononuclear (MNC) and polymorphonuclear (PMNC) cell fractions was developed. Zinc concentrations in cells from healthy subjects were (mean +/- SD, in mumol/10(10) cells): 0.81 +/- 0.24 in MNC and 0.55 +/- 0.06 in PMNC. In patients suffering from several diseases known to be associated with a marginal impairment in zinc status (cirrhosis, cancer, obesity, endocrine and rheumatic diseases), these concentrations did not differ from those in controls except in rheumatic patients in whom MNC zinc was increased (1.05 +/- 0.42 mumol/10(10) cells) and correlated with erythrocyte sedimentation rate (r = 0.41, P less than 0.01). This relation was also significant in the whole study population (r = 0.39, P less than 0.01). Leucocyte zinc therefore appears to have a limited value in the assessment of marginally impaired zinc status, except in inflammatory states.

[Effect of zinc substitution on lymphocyte subsets and cellular immune function in hemodialysis patients]

Infection is a major cause of morbidity and mortality in patients undergoing hemodialysis for end stage renal disease. Low plasma zinc levels have been associated with immunodepression in these patients. In a randomized, placebo controlled double-blind cross over study, plasma zinc levels, delayed hypersensivity to 7 Antigens (Merieux-Multitest), absolute lymphocyte counts, T- and B-lymphocytes, suppressor-T and helper T-cells and natural killer cells were studied in 25 hemodialysis patients before, during and after intravenous zinc supplementation for 8 weeks. The hemodialysis patients had significantly lower predialysis plasma zinc concentrations compared to 76 healthy controls (74 +/- 12 vs. 126 +/- 28 mcg/dl, p less than 0.001). The plasma zinc concentrations increased to the normal range during the treatment period. Lymphocyte subtype analysis showed a significant decrease of suppressor-T cells and an increase of the helper-T/suppressor-T ratio (2.09 +/- 0.26 vs. 3.18 +/- 0.48, p less than 0.05) after zinc supplementation. Delayed hypersensivity to intradermal antigens increased significantly only after zinc treatment (2.0 +/- 0.7 vs. 5.8 +/- 1.7, p less than 0.05), not after placebo. The changes were reversible after finishing the zinc treatment. It is concluded, that plasma zinc levels are reduced in hemodialysis patients and that the substitution of zinc restores some of the depressed immune functions in these patients.

An inverse relationship between serum zinc and C-reactive protein levels in acutely ill elderly hospital patients

Serum zinc and C-reactive protein (CRP) levels were measured in two groups of acutely ill geriatric hospital in-patients. Serum CRP levels were greater than 10 mg/l in 62% of the first group and 47% of the second. There was a significant negative correlation between zinc and CRP in both groups (r = -0.33, P less than 0.001, n = 103) and (r = -0.29, P less than 0.001, n = 135 respectively). The serum CRP was raised in 30% of long stay patients (n = 50) and 23% of a control group of elderly hospital patients with a normal serum albumin (n = 71), but there was no correlation between zinc and CRP in these patient groups. The results indicate that an acute phase response influences serum zinc levels in acutely ill geriatric patients. There is reason to believe that a distinction should be made between true zinc deficiency and a low serum zinc secondary to acute zinc redistribution during an inflammatory response. Measurement of CRP may help to distinguish between these two situations. We advise that if the serum zinc is low and CRP is significantly raised, zinc supplements should be avoided and a source of infection should be sought. Following recovery from severe infection low serum zinc levels return to normal while elevated CRP levels fall.

Zinc monoglycerolate: a slow-release source of zinc with anti-arthritic activity in rats

Zinc repletion by parental administration of zinc monoglycerolate (ZMG) or certain other lipophilic zinc complexes, suppressed the development of adjuvant-induced polyarthritis in rats. While ZMG was effective when given parenterally over various limited time schedules (immunosuppressant, therapeutic, singledose), it was not effective given orally. The complex showed no acute anti-inflammatory activity in the carrageenan paw oedema assay and little gastric-intestinal or other organ toxicity. When injected s.c. it caused very much less local irritation than most zinc salts. Being lubrous, ZMG could be applied as the dry powder for rubbing into the skin and by this route was found to have anti-arthritic activity. 65Zn was shown to be absorbed and excreted in the faeces (biliary excretion) after applying 65Zn-ZMG dermally to shaved dorsal skin of rats. ZMG showed consistent anti-arthritic activity in rats under conditions in which 2 gold drugs (aurothiomalate, Auranofin) exhibited variable effects, depending on the strain of rat. The role of zinc and its availability in chronic inflammation are discussed on the basis of these studies.

Serum trace element levels in HIV-infected subjects

The absolute number of T4 cells and the serum concentrations of Ca, Cu, Fe, K, Mg, P, Se, and Zn were determined in 59 Walter-Reed staged, HIV-infected men, compared to healthy controls, serum levels of Ca, Cu, and Fe were significantly higher, those of P and Se significantly lower in the HIV-infected subjects. In the HIV-infected cases, but not in the controls, the concentrations of Se and Zn, of Ca with Cu and Fe, and of Fe with P, were directly correlated. In the controls, the correlation between the levels of K and Mg was direct, and inverse between those of Zn and P. Trace element levels did not significantly correlate with WR-stage. However, the absolute number of T4 cells was directly correlated with the serum Mg concentration.

Zinc in kidney disease

Abnormalities of Zn metabolism are well documented in patients with chronic renal disease, especially those with nephrotic disease and uremia. The causes of Zn deficiency in kidney disease are not clear. Decreased dietary Zn intake and intestinal absorption, increased endogenous Zn secretion, and increased urinary Zn excretion (as in the nephrotic syndrome and in renal transplant recipients) all may contribute to altered Zn metabolism. Zn depletion may account for decreased taste, sexual and gonadal dysfunction, hyperprolactinemia, glucose intolerance, hyperlipidemia, growth retardation in children, neuropathy, anemia, abnormalities of neutrophil and lymphocyte function, and delayed wound healing. The benefit of pharmacologic doses of Zn, in the treatment of such manifestations, requires further evaluation under controlled conditions. Before use of Zn routinely for therapeutic purposes in uremic subjects, the cause(s) of abnormal Zn metabolism should be identified.

Zinc concentrations in pure populations of peripheral blood neutrophils, lymphocytes and monocytes

It is doubtful if the measurement of plasma or serum zinc is of value in assessing zinc status. Leucocyte zinc has been suggested as an alternative since it may be representative of tissue zinc stores; but in many studies poorly defined cell populations make interpretation difficult. This paper describes detailed techniques for the isolation and analysis of pure populations of neutrophils, lymphocytes and monocytes. Zinc concentrations (+/- 1SD) in normal subjects were 1.26 +/- 0.27 nmol/mg protein, 1.85 +/- 0.32 nmol/mg protein and 2.58 +/- 0.65 nmol/mg protein in neutrophils, lymphocytes and monocytes respectively. Fasting caused a significant decrease in neutrophil and lymphocyte zinc, and an increase in monocyte zinc. Supplementation of zinc-replete subjects with 135 mg zinc/day for 3 weeks had no significant effect on cellular zinc concentrations.

Zinc absorption in haemodialysis patients

The gastrointestinal absorption of zinc by haemodialysis patients has been investigated. Subnormal plasma zinc responses were observed in nine haemodialysis patients during oral zinc tolerance tests. These patients also had reduced leucocyte zinc concentrations which did not respond when 50 mg (0.77 mmol) of zinc was given daily by mouth for a period of 4 months. White cell zinc concentrations measured in another group of 10 haemodialysis patients were reduced initially, but rose to normal levels over 4 months when zinc was added to the fluid used for dialysis. These data suggest that the intestinal absorption of zinc was defective in the dialysis patients participating in this investigation.

Neutrophil and monocyte alterations in chronic dialysis patients

Chronic renal failure patients maintained on dialysis have an increased risk for infection. This article summarizes research that has been done on the function of neutrophils (PMNs) and monocytes from chronic hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. The studies involving the HD patients showed that there is a decreased PMN in vitro chemotactic response, decreased C5a receptors on both PMNs and monocytes, and decreased oxidative metabolic responses of PMNs and monocytes to the chemotactic stimuli C5a and formyl-met-leu-phe (fMLP), but not to nonchemotactic factors. The results of studies involving phagocytosis have been conflicting and are discussed in this paper. Due to the basic principles of peritoneal dialysis, this treatment approach depletes the peritoneum of phagocytic cells, adversely affects the function of peritoneal WBCs, dilutes the existing opsonins, and alters the physiologic environment of the peritoneal cavity. Studies of peripheral PMN and monocyte function in CAPD patients have shown that, similar to HD patients, they also have decreased C5a receptors and decreased oxidative metabolic responses to the chemotactic factors C5a and fMLP. Although the factors contributing to the risk of infection in chronic dialysis patients are multifaceted, there are definitely alterations in PMN and monocyte function.

Appraisal of the methodology and applications for measurement of the zinc content of blood components as indicators of zinc status

Methods for the measurement of the zinc content of blood components (plasma, erythrocytes, platelets, mononuclear leukocytes, and polymorphonuclear neutrophils) as indicators of the zinc status of animals have been reviewed and evaluated. The values of plasma or serum zinc concentrations as indicators of zinc status in experimental animals or humans is questionable. Consequently, the zinc content of blood cellular components has been suggested as better indicators of zinc status. Methodological problems, such as incomplete cellular separation or zinc contamination, occur in some of the procedures applied to the quantitation of blood cellular component zinc. Specialized microprobe procedures involving, for example, proton-induced X-ray fluorescence, scanning ion technology, mass spectrometery, or laser microprobe mass analysis might be used to measure the absolute zinc level in individual cells subjected to minimal handling. Then, more conventional methods can be tested against the true standard. Nevertheless, there appears to be species differences in regard to the response of blood cellular zinc concentrations to dietary zinc deficiency. Blood cellular component zinc is conserved during severe zinc deficiency in the rat. In contrast, the zinc content of blood cellular components in humans may reflect the whole body zinc status.

Clinical, endocrinological and biochemical effects of zinc deficiency

The essentiality of zinc for humans was recognized in the early 1960s. The causes of zinc deficiency include malnutrition, alcoholism, malabsorption, extensive burns, chronic debilitating disorders, chronic renal disease, certain diuretics, the use of chelating agents such as penicillamine for Wilson's disease, and genetic disorders such as acrodermatitis enteropathica and sickle cell disease. The requirement of zinc is increased in pregnancy and during the growing age period. The clinical manifestations in severe cases of zinc deficiency included bullous-pustular dermatitis, alopecia, diarrhoea, emotional disorder, weight loss, intercurrent infections, hypogonadism in males and it is fatal if untreated. A moderate deficiency of zinc is characterized by growth retardation and delayed puberty in adolescents, hypogonadism in males, rough skin, poor appetite, mental lethargy, delayed wound healing, taste abnormalities and abnormal dark adaptation. In mild cases of zinc deficiency in human subjects, we have observed oligospermia, slight weight loss and hyperammonaemia. Zinc is a growth factor. As a result of its deficiency, growth is affected adversely in many animal species and in man. Inasmuch as zinc is needed for protein and DNA synthesis and cell division, it is believed that the growth effect of zinc is related to its effect on protein synthesis. Testicular functions are affected adversely as a result of zinc deficiency in both humans and experimental animals. This effect of zinc is at the end organ level and the hypothalamic--pituitary axis is intact in zinc-deficient subjects. Inasmuch as zinc is intimately involved in a cell division, its deficiency may adversely affect testicular size and thus its function. In mice, the incidence of degenerate oocytes, and hypohaploidy and hyperhaploidy in metaphase II oocytes were increased due to zinc deficiency. Zinc at physiological concentrations reduced prolactin secretion from the pituitary in vitro and it has been suggested that this trace element may have a role in the in vivo regulation of prolactin release. Thymopoietin, a hormone needed for T-cell maturation, has also been shown to be zinc dependent. It is clear that zinc may have several roles in biochemical and hormonal functions of various endocrine organs. Future research in this area is very much needed.

Determination of zinc in erythrocytes, granulocytes and serum by flame atomic absorption spectrophotometry

Zinc was determined in granulocytes, erythrocytes and serum by flame atomic absorption spectrophotometry. Using a Teflon sampling cup, the sample volume for a single granulocyte zinc determination was reduced to 100 microliter. Zinc in serum and erythrocytes was measured by aspirating the sample at a rate of 5 ml/min. The total volume of blood used was 23-28 ml. The intra-assay coefficient of variation of the method for granulocytes was 0.01 and of the method for serum and erythrocytes 0.018. The corresponding inter-assay coefficient of variation was 0.037 and 0.03, respectively. Recovery of zinc determined by the method of aspirating the small volume (100 microliter) was 103% and by the method of aspirating 5 ml/min 97%. The coefficient of correlation between the two methods was r = 0.9968.

Changes in zinc and zinc-dependent enzymes in rheumatoid patients during penicillamine treatment

Zinc in granulocytes, erythrocytes, serum, urine and zinc-dependent enzymes (alkaline phosphatase in serum and granulocytes, carbonic anhydrase in erythrocytes) were measured in patients with rheumatoid arthritis before and during penicillamine therapy for 6 months. The zinc concentration in serum, urine and erythrocytes increased, while granulocyte zinc decreased. Alkaline phosphatase activity in plasma remained unchanged, while alkaline phosphatase in granulocytes decreased. Carbonic anhydrase activity in erythrocytes decreased. None of the changes could be related to the activity of the disease.