The role of zinc in acquired immunodeficiency syndrome

Paediatric HIV: Correlation between Serum Zinc Levels and CD4 Percentage on Asymptomatic Nigerian Children Living with HIV

OBJECTIVE

This study was conducted to determine the relationship between their serum zinc levels and the CD4% in a cohort children living with HIV.

METHODS

One hundred asymptomatic, anti-retroviral Therapy (ART) naïve children living with HIV (participants) aged 5-60 months who were enrolled into the Paediatric HIV clinic of The University of Nigeria Teaching Hospital were recruited in the study over a 10-month period. Blood samples were collected in the morning from non-fasting participants and serum zinc levels were analysed using Atomic Absorption Spectrophotometer. The CD4% was ascertained using the CD4% easy count kit on the Partec® Cyflow Counter machine. Data were analysed using Statistical Package for the Social Sciences version 19.

RESULT

The median (IQR) serum zinc level for the participants was 55.5 µg/dl (49.75) while their median (IQR) CD4% was 27.79% (18.67). Males had a median (IQR) CD4% of 24.29% (19.10) which was significantly lower than those of females [32% (20.59) (p = 0.047)]. No significant relationship was found between CD4% and zinc levels among the subjects (r = -0.061, p = 0.557).

CONCLUSION

Serum zinc levels of asymptomatic ART naïve children living with HIV have no relationship with their CD4%.

Effect of Human Immunodeficiency Virus on Trace Elements in the Brain

Comorbidities of human immunodeficiency virus (HIV) include HIV-associated neurocognitive disorder (HAND). Changes in the brain due to HIV include atrophy, hyperintensities, and diffusion changes. However, no research has focused on trace elements concentration changes in the brain due to HIV, as seen in other neurodegenerative diseases. Therefore, the aim of this study was to determine the concentration of several trace elements in the brains of individuals with and without HIV infection. Prior to formalin embalming, blood was drawn and tested in triplicate with Determine HIV-1/2 rapid tests and confirmed with a SD HIV Device 1/2 3.0 rapid HIV Kit. After embalming, tissue was sampled from the caudate nucleus and analyzed using inductively coupled plasma mass spectrometry. A Kruskal-Wallis test was used to determine statistically significant differences between the two groups (p < 0.05). Fifteen HIV-positive and 14 HIV-negative male cadavers were included (mean age 44, range 22 to 61). Cadmium was marginally decreased, possibly due to malnutrition or utilization by the HIV nucleocapsid. Nickel was marginally increased, perhaps due to a reduced capability to remove metals from the body. In conclusion, this article provides the first information on trace element levels in the brains from HIV-infected individuals and postulates that cadmium and nickel may play a role in the pathophysiology of HAND. This information can contribute to finding a treatment for HAND, other than the use of antiretroviral drugs. Future studies should asses the levels of cadmium and nickel in a larger cohort of HIV-infected individuals.

Role of Divalent Cations in HIV-1 Replication and Pathogenicity

Divalent cations are essential for life and are fundamentally important coordinators of cellular metabolism, cell growth, host-pathogen interactions, and cell death. Specifically, for human immunodeficiency virus type-1 (HIV-1), divalent cations are required for interactions between viral and host factors that govern HIV-1 replication and pathogenicity. Homeostatic regulation of divalent cations' levels and actions appear to change as HIV-1 infection progresses and as changes occur between HIV-1 and the host. In people living with HIV-1, dietary supplementation with divalent cations may increase HIV-1 replication, whereas cation chelation may suppress HIV-1 replication and decrease disease progression. Here, we review literature on the roles of zinc (Zn2+), iron (Fe2+), manganese (Mn2+), magnesium (Mg2+), selenium (Se2+), and copper (Cu2+) in HIV-1 replication and pathogenicity, as well as evidence that divalent cation levels and actions may be targeted therapeutically in people living with HIV-1.

Zinc enhances the cellular energy supply to improve cell motility and restore impaired energetic metabolism in a toxic environment induced by OTA

Exogenous nutrient elements modulate the energetic metabolism responses that are prerequisites for cellular homeostasis and metabolic physiology. Although zinc is important in oxidative stress and cytoprotection processes, its role in the regulation of energetic metabolism remains largely unknown. In this study, we found that zinc stimulated aspect in cell motility and was essential in restoring the Ochratoxin A (OTA)-induced energetic metabolism damage in HEK293 cells. Moreover, using zinc supplementation and zinc deficiency models, we observed that zinc is conducive to mitochondrial pyruvate transport, oxidative phosphorylation, carbohydrate metabolism, lipid metabolism and ultimate energy metabolism in both normal and toxic-induced oxidative stress conditions in vitro, and it plays an important role in restoring impaired energetic metabolism. This zinc-mediated energetic metabolism regulation could also be helpful for DNA maintenance, cytoprotection and hereditary cancer traceability. Therefore, zinc can widely adjust energetic metabolism and is essential in restoring the impaired energetic metabolism of cellular physiology.

Micronutrients and HIV infection

The immune system requires several essential micronutrients to maintain an effective immune response. HIV infection destroys the immune system and promotes nutritional deficiencies, which further impair immunity. This article reviews the role of several micronutrients (vitamins A, C, E and D, the B vitamins, and minerals, selenium, iron and zinc) that are relevant for maintaining immune function. In addition, the deficiencies of these micronutrients have been associated with faster progression of HIV-1 disease. This review examines the evidence from observational studies of an association between micronutrient status and HIV disease, as well as the effectiveness of micronutrient supplementation on HIV-disease progression, pregnancy outcomes and nutritional status, among others, utilizing randomized clinical trials. Each micronutrient is introduced with a summary of its functions in human physiology, followed by the presentation of studies conducted in HIV-infected patients in relation to this specific micronutrient. Overall findings and recommendations are then summarized.

A clinical review of micronutrients in HIV infection

This article reviews current literature on the role of micronutrients in human immunodeficiency virus (HIV) infection. Deficiencies of micronutrients are common in HIV-infected persons. They occur due to malabsorption, altered metabolism, gut infection, and altered gut barrier function. There is a compelling association of deficiencies of micronutrients in HIV-infection with immune deficiency, rapid disease progression, and mortality. Also, there is increased risk of vertical HIV transmission from mother to child with deficiency of vitamin A, and of neurological impairment with vitamin B12. The last five years have been exciting in micronutrient research, and there is promise that some micronutrients may be key factors in maintaining health in HIV immunodeficiency, and in reducing mortality. Selenium appears important in reducing virulence of HIV and slowing disease progression. Vitamin A supplementation in pregnant women with HIV may reduce maternal mortality and improve birth outcomes. Supplementation in children with HIV may accelerate growth. Carotenoid supplementation is being evaluated. Vitamin B12 may slow HIV immune deficiency disease progression, and reverse neurological compromise. Clinical benefit of supplementation with some micronutrients may be measurable in the presence of pre-existing deficiency. Apart from improved general nutrition, the impact of micronutrient supplements on health and their optimal use in HIV infection is controversial because there are so few controlled clinical trials. Further research is needed to elucidate the role of micronutrient deficiencies on the course of HIV infection, and the preventive and therapeutic role of supplementation in its clinical management. Nevertheless, current knowledge supports the use of routine multivitamin and trace element supplementation as adjuvant to conventional antiretroviral drug treatment as a relatively low-cost intervention.

Dietary zinc deficiency induced-changes in the activity of enzymes and the levels of free radicals, lipids and protein electrophoretic behavior in growing rats

Zinc (Zn) is an essential nutrient that is required in humans and animals for many physiological functions, including immune and antioxidant function, growth and reproduction. The present study was conducted to investigate the effects of adequate Zn level (38 mg/kg diet, as a control) and two low levels that create Zn deficiencies (19 mg/kg diet, 1/2 of the control and 3.8 mg/kg diet, 1/10 of the control) in growing male and female rats for 10 weeks. To evaluate the effects of these levels, the concentrations of thiobarbituric acid-reactive substances (TBARS), biochemical parameters and protein pattern were studied. Lipid peroxidation in liver, brain and testes of rats fed Zn-deficient diet was indicated by increased TBARS. Serum, liver, brain and testes glutathione S-transferase (GST) activities were significantly (P<0.05) increased in Zn-deficient rats, the effect was pronounced in rats fed the lowest level of Zn (1/10 of control). The activity of lactate dehydrogenase (LDH) was significantly (P<0.05) increased in liver, brain and testes, but decreased in serum in a dose-dependent manner. Zinc deficiency increased (P<0.05) liver aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in a dose-dependent manner, while there was no effect on the activity of these enzymes in testes. Zinc deficiency resulted in a significant (P<0.05) decrease in the activity of alkaline phosphatase (AlP) in serum and liver in a dose-dependent manner, but no effect in testes was found. The activity of acid phosphatase (AcP) was not affected in serum, liver and testes. Zn-deficient rats had higher liver concentrations of total lipids (TL), cholesterol, triglyceride (TG), and low density lipoprotein (LDL), while high density lipoprotein (HDL) was significantly (P<0.05) declined in a dose-dependent manner. Brain and serum acetylcholinesterase (AChE) activities were, however, not affected (P<0.05) by Zn deficiency. Protein content in liver, brain and testes showed a significant (P<0.05) decrease in rats fed the lowest level of Zn (1/10 of control). Polyacrylamide gel electrophoresis (native-PAGE) of serum proteins revealed that the intensity of immunoglobulins, serum albumin as well as several peptide bands were decreased in rats fed 1/2 or 1/10 of Zn adequate, i.e. their synthesis was affected and it was pronounced with the lowest level of Zn deficiency (1/10 of control). However, no clear effect on the transferrin was observed in both cases compared to controls. From the results of this study it can be concluded that Zn deficiency exerts numerous alterations in the studied biochemical parameters, protein pattern, and increased lipid peroxidation.

Plasma zinc, copper, copper:zinc ratio, and survival in a cohort of HIV-1-infected homosexual men

A prospective cohort study of 121 HIV-1-positive homosexual men was conducted in Miami, Florida, U.S.A. to evaluate the associations between plasma zinc and copper levels and mortality. Plasma zinc and copper levels were measured at baseline and then at semiannual visits. Zinc inadequacy and copper inadequacy were defined as plasma zinc levels <75 (microg/dl) and plasma copper levels <85 (microg/dl), respectively. HIV-1-related deaths were confirmed by review of death certificates. Cox proportional hazards regression models with time-dependent covariates were used to estimate the relative risks of zinc and copper inadequacy on mortality. Over the average course of the 3.3-year follow-up, 19 participants (16%) died of HIV-1-related causes. After adjustment for potential confounders, including low CD4+ cell counts and antiretroviral therapy, zinc inadequacy and copper:zinc ratio >1 (i.e., plasma copper level greater than plasma zinc level) were associated with increased mortality (relative risks [RRs]; 95% confidence intervals [CIs], 4.98, 1.30-19.00 and 8.28, 1.03-66.58, respectively). A negative association was also observed between plasma zinc levels and mortality (RR 0.94; 95% CI, 0.91-0.98). Plasma levels of copper were not significantly associated with mortality. These results suggest that plasma zinc inadequacy or the plasma copper:zinc ratio may be useful predictors of survival in HIV-1 infection. The latter appears to be a stronger predictor.

Zinc status in human immunodeficiency virus infection

There is substantial evidence to support an important role for zinc in immune processes. Adequate zinc status is essential for T-cell division, maturation and differentiation; lymphocyte response to mitogens; programmed cell death of lymphoid and myeloid origins; gene transcription; and biomembrane function. Lymphocytes are one of the types of cells activated by zinc. Zinc is the structural component of a wide variety of proteins, neuropeptides, hormone receptors and polynucleotides. Among the best known zinc-dependent hormones/enzymes are Cu, Zn superoxide dismutase, an enzyme component of the antioxidant defense system, and thymulin, which is essential for the formation of T-lymphocytes. In animals and humans, zinc deficiency results in rapid and marked atrophy of the thymus, impaired cell-mediated cutaneous sensitivity and lymphopenia. Primary and secondary antibody responses are reduced in zinc deficiency, particularly for those antigens that require T-cell help, such as those in heterologous red blood cells. In addition, antibody response and the generation of splenic cytotoxic T cells after immunization are reduced. Zinc also inhibits the production of tumor necrosis factor, which is implicated in the pathophysiology of cachexia and wasting in acquired immune deficiency syndrome.

Therapeutic application of zinc in human immunodeficiency virus against opportunistic infections

The relevance of zinc in resistance to infections by virus, fungi and bacteria is recognized because of its pivotal role in the efficiency of the entire immune system, in particular in conferring biological activity to a thymic hormone called thymulin, which has differentiation properties on T-cell lines. In infection with human immunodeficiency virus (HIV), the zinc-bound form of thymulin (active thymulin, ZnFTS) is strongly reduced in stage IV of the disease (Centers for Disease Control and Prevention classification) with concomitant decrements in CD4(+) cell count and zincemia values. The zinc-unbound form of thymulin (inactive thymulin, FTS) is, in contrast, very high. The in vitro addition of zinc to plasma samples induces a recovery of the thymulin active form, suggesting low zinc bioavailability as the cause of impaired thymic functions with consequent CD4(+) depletion. An analysis of risk factors for the incidence of recidivism opportunistic infections shows CD4(+) depletion and zinc deficiency to have significant scores. Supplementation with zinc for 1 mo (45 mg Zn(2+)/d) associated with zidovudine (AZT) therapy in stage IV induces recovery of active zinc-bound thymulin, of zincemia, of CD4(+) cells with concomitant reduction (50%) of recidivism opportunistic infections compared with the AZT-treated group. Complete disappearance of recidivism by Candida aesophagea or Pneumocystis carinii is observed after supplementation with zinc. The relative risk factors (CD4(+) depletion and zinc-deficiency) have lower scores in the HIV-positive zinc-treated group, confirming, as such, the relevance of zinc in opportunistic infections that involve extracellular matrix. Such an assumption is indirectly confirmed with new HAART, where no opportunistic infections occur. Indeed, HIV RNA is inversely correlated with both CD4(+) and zincemia values (r = -0.73, P<0.01) in HAART-treated subjects. Lower scores for the same relative factors for the appearance of opportunistic infections are present in HAART-treated subjects compared with those treated with AZT. These findings, on the one hand, show the poor efficacy of AZT therapy compared with HAART therapy for the progression of HIV, but on the other hand, they suggest that the lack of occurrence of opportunistic infections by HAART may also result from major zinc bioavailability. This further supports the key role played by zinc against opportunistic infections in HIV with a possible independent effect by either HIV or the pathogens involved.

Zinc metabolism in the brain: relevance to human neurodegenerative disorders

Zinc is an important trace element in biology. An important pool of zinc in the brain is the one present in synaptic vesicles in a subgroup of glutamatergic neurons. In this form it can be released by electrical stimulation and may serve to modulate responses at receptors for a number of different neurotransmitters. These include both excitatory and inhibitory receptors, particularly the NMDA and GABA(A) receptors. This pool of zinc is the only form of zinc readily stained histochemically (the chelatable zinc pool), but constitutes only about 8% of the total zinc content in the brain. The remainder of the zinc is more or less tightly bound to proteins where it acts either as a component of the catalytic site of enzymes or in a structural capacity. The metabolism of zinc in the brain is regulated by a number of transport proteins, some of which have been recently characterized by gene cloning techniques. The intracellular concentration may be mediated both by efflux from the cell by the zinc transporter ZrT1 and by complexing with apothionein to form metallothlonein. Metallothionein may serve as the source of zinc for incorporation into proteins, including a number of DNA transcription factors. However, zinc is readily released from metallothionein by disulfides, increasing concentrations of which are formed under oxidative stress. Metallothionein is a very good scavenger of free radicals, and zinc itself can also reduce oxidative stress by binding to thiol groups, decreasing their oxidation. Zinc is also a very potent inhibitor of nitric oxide synthase. Increased levels of chelatable zinc have been shown to be present in cell cultures of immune cells undergoing apoptosis. This is very reminiscent of the zinc staining of neuronal perikarya dying after an episode of ischemia or seizure activity. Thus a possible role of zinc in causing neuronal death in the brain needs to be fully investigated. intraventricular injections of calcium EDTA have already been shown to reduce neuronal death after a period of ischemia. Pharmacological doses of zinc cause neuronal death, and some estimates indicate that extracellular concentrations of zinc could reach neurotoxic levels under pathological conditions. Zinc is released in high concentrations from the hippocampus during seizures. Unfortunately, there are contrasting observations as to whether this zinc serves to potentiate or decrease seizure activity. Zinc may have an additional role in causing death in at least some neurons damaged by seizure activity and be involved in the sprouting phenomenon which may give rise to recurrent seizure propagation in the hippocampus. In Alzheimer's disease, zinc has been shown to aggregate beta-amyloid, a form which is potentially neurotoxic. The zinc-dependent transcription factors NF-kappa B and Sp1 bind to the promoter region of the amyloid precursor protein (APP) gene. Zinc also inhibits enzymes which degrade APP to nonamyloidogenic peptides and which degrade the soluble form of beta-amyloid. The changes in zinc metabolism which occur during oxidative stress may be important in neurological diseases where oxidative stress is implicated, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). Zinc is a structural component of superoxide dismutase 1, mutations in which give rise to one form of familiar ALS. After HIV infection, zinc deficiency is found which may be secondary to immune-induced cytokine synthesis. Zinc is involved in the replication of the HIV virus at a number of sites. These observations should stimulate further research into the role of zinc in neuropathology.

Zinc levels and infections in hospitalized patients with AIDS

Impaired cellular and humoral immunity and phagocytic function have been attributed to zinc deficiency. This study examined the association between low serum zinc concentration and opportunistic infections in hospitalized patients with the acquired immune deficiency syndrome (AIDS). We examined the records from all 505 inpatient consultations performed by our Nutrition Service from May 1992 through June 1994. The medical records from all 228 patients with AIDS with known serum zinc levels (determined by atomic absorption spectrophotometry) were reviewed. The length of HIV seropositivity, most recent CD4 count, presence of diarrhea, and degree of malnutrition were noted. The principal diagnosis accounting for the admission was grouped according to the type of infection: Pneumocystis carinii pneumonia (PCP), viral, fungal, bacterial, and other. Sixty-seven patients (29%) had abnormally low serum zinc levels (LSZ < 55 micrograms/dL), 49 patients (21%) had borderline low serum zinc (BSZ > or = 55 and < or = 65 microgram/dL), and 112 (49%) patients had normal serum zinc levels (NSZ > 65 micrograms/dL). There was no significant difference among the groups in CD4 count, length of HIV seropositivity, presence of diarrhea, or severity of malnutrition. Patients with zinc deficiency (LSZ) had a significantly higher incidence of bacterial infection than did patients with normal zinc. Patients with borderline zinc levels had an intermediate incidence of bacterial infection. There were no significant differences among the three groups in the incidence of PCP, viral, or fungal infections. Severe zinc deficiency was noted in 29% and borderline levels in an additional 21% of hospitalized AIDS patients. A low zinc level was not associated with the length of HIV seropositivity, CD4 count, or degree of malnutrition. Hypozincemia was associated with an increased incidence of concomitant systemic bacterial infections.

Serum zinc and protein levels: lack of a correlation in hospitalized patients with AIDS

Abnormally low serum zinc levels are associated with advanced states of malnutrition. Zinc levels are thought to parallel serum albumin, and repletion of zinc has reportedly led to increased albumin. We examined the correlation between zinc deficiency and serum proteins in hospitalized patients with AIDS. Over 500 inpatient consultations were performed by our Gastroenterology-Nutrition Consult Service from May 1992 to June 1994. We reviewed the medical records from all 228 AIDS patients in whom a serum zinc level was measured (by atomic absorption spectrophotometry). The correlation between serum zinc, albumin, prealbumin, and transferrin drawn on the same hospital day was analyzed by linear regression. The patients were stratified by the level of albumin, group A albumin < 2.0 g/dL, group B albumin 2.0-2.9 g/dL, and group C albumin > 3.0 g/dL, to allow comparison of the incidence of diarrhea and mean zinc level by chi square. Thirty-four patients had more than one serum zinc and albumin determination; the change over time was compared by linear regression. Serum zinc and albumin, prealbumin, and transferrin levels did not correlate strongly (r2 < or = 0.01). Furthermore, changes in zinc over time did not correlate with parallel changes in serum albumin (r2 < or = 0.01). In patients grouped by albumin, the proportion of patients with diarrhea did not differ significantly. The mean zinc levels were also not statistically significantly different. Serum zinc levels do not strongly correlate with serum proteins in hospitalized patients with AIDS. Serial measures of zinc over time also do not correlate strongly with changes in albumin. The incidence of diarrhea was not significantly different in patients with hypoalbuminemia or hypozincemia when compared with patients with near normal albumin or zinc. The relationship between zinc and serum proteins in AIDS patients is not linear. Zinc deficiency should be assessed in patients independent of the serum albumin.

Zinc acetate and lyophilized aloe barbadensis as vaginal contraceptive

Twenty samples of fresh ejaculate, donated by healthy volunteers ranging in age from 20-30 years, were obtained from the Center for Fertility & Cryobiology, University of Missouri, Columbia, Missouri. Average semen volume was 2.49 ml; average sperm motility was 71.32%; and average sperm density was 113.71 x 10(6) /ml. Testing for spermicidal effectiveness of a 1% concentration of zinc acetate, zinc sulfate, zinc chloride, and zinc gluconate proved that only zinc acetate was spermicidal. It appears this is due to the acetate in zinc acetate which may decrease oxygen utilization by sperm. Zinc acetate in vitro was antiviral while lyophilized aloe barbadensis was not. Lyophilized aloe barbadensis at concentrations of 7.5% and 10% proved to be spermicidal due to the multiple micro elements (boron, barium, calcium, chromium, copper, iron, potassium, magnesium, manganese, phosphorus, and zinc) which were toxic to the tail causing instant immobilization. The two compounds did not irritate or cause ulceration of rabbit vaginal epithelium. These results suggest the possibility of using zinc acetate and lyophilized aloe barbadensis as a new, effective and safe vaginal contraceptive.

Antioxidant status and lipid peroxidation in patients infected with HIV

Deficiency in antioxidant micronutrients have been observed in patients with AIDS. These observations concerning only some isolated nutrients demonstrate a defect in zinc, selenium, and glutathione. An increase in free radical production and lipid peroxidation has been also found in these patients, and takes a great importance with recent papers presenting an immunodeficiency and more important an increase in HIV-1 replication secondary to free radicals overproduction. We have assessed different studies, trying to obtain a global view of the antioxidant status of these patients. In adults we observe a progressive decrease for zinc, selenium, and vitamin E with the severity of disease, except that selenium remains normal at stage II. However, the main dramatic decrease concerns carotenoids whose level at stage II is only half the normal value. To understand if these decreases in antioxidant and increases in oxidative stress occur secondary to the aggravation of the disease or, conversely, are responsible for it, we undertook a longitudinal survey of asymptotic patients. The preliminary results of this evaluation are presented. Paradoxically, lipid peroxidation is higher at stage II than at stage IV. This may be consecutive to a more intense overproduction of oxygen free radicals by more viable polymorphonuclear (PMN) at the asymptomatic stage. The free radicals production and lipid peroxidation seem secondary to a direct induction by the virus of PMN stimulation and cytokines secretion. N-Acetyl cysteine or ascorbate have been demonstrated in cell culture to be capable of blocking the expression of HIV-1 after oxidative stress and N-acetyl cysteine inhibits in vitro TNF-induced apoptosis of infected cells. In regard to all these experimental data, few serious and large trials of antioxidants have been conducted in HIV-infected patients, although some preliminary studies using zinc or selenium have been performed. In our opinion it is now time to evaluate in humans the beneficial effect of antioxidants. The more promising candidates for presenting synergistic effects when associated with N-acetyl cysteine seem to be beta-carotene, selenium and zinc.