Beneficial Effect of Zinc Supplementation on Oxidative Stress, Cytokines, and NF-κB DNA Binding in Sickle Cell Disease Patients.

Abstract

Zinc deficiency is common in adult sickle-cell disease (SCD) patients, due to continued hemolysis and hyperzincuria. Growth retardation, hypogonadism, and immune dysfunctions due to zinc deficiency have been described in SCD patients. Our studies show that zinc has not only anti-inflammatory functions, but is also an antioxidant. We have previously shown that zinc supplementation to adult SCD patients decreased the incidences of infection and hospital admissions. We hypothesize that zinc supplementation improves T-helper cell and vascular endothelial cell activation, and decreases oxidative stress and NF-κB activation in SCD patients. To test this hypothesis, we recruited 36 ambulatory SCD (homozygous) patients (ages 18–47 years, 11 males and 7 females in each group) and randomly divided these into 2 groups. One group (n=18) received 25 mg zinc as acetate orally thrice a day for 3 months. The other group (n=18) received placebo. All these patients were free of pain crisis for 3 months and were not receiving hydroxyurea. The results indicate that zinc supplemented group had decreased incidence of infection in comparison to the placebo group (Chi square analysis: p=0.017). After 3 months of zinc supplementation, the plasma zinc level increased. The anti-oxidant power increased and the plasma levels of NO, lipid peroxidation products (MDA+HAE), DNA oxidation product (8-OHdG), and sVCAM-1 decreased in the zinc supplemented group, compared to the placebo group (p<0.05), as shown in the Table.ParameterGroupPrePostp valueΔp valueZn (μM)Placebo88.8±9.989.3±8.50.8930.0001Zn Supp.85.6±9.3104.2±15.00.0005MDA+HAE (μM)Placebo1.62±0.311.75±0.270.9230.004Zn Supp.1.60±0.241.28±0.240.009NO (μM)Placebo78.5±12.676.7±11.80.2560.051Zn Supp.75.2±11.260.9±17.10.0218-OHdG (ng/ml)Plecebo0.75±0.230.79±0.350.4270.036Zn Supp.0.81±0.250.63±0.210.093Antioxidant power (u/ml)Placebo6.89±1.656.61±1.500.2780.002Zn Supp.7.36±7.210.52±2.330.001sVCAM-1 (ng/ml)Placebo1587±3591495±4540.2630.008Zn Supp.1434±4551251±3530.023p value: Paired T-test; Pre (baseline) vs Post (6 m of supplementation). Δp value: T-test of the differences (pre vs post) between placebo vs Zn group)Relative levels of TNF-α, IL-1β, VCAM-1 mRNAs by RT-PCR were reduced in LPS-stimulated MNC isolated from zinc supplemented group, compared to placebo. In vitro zinc addition to the MNC isolated from placebo decreased TNF-α and IL-1β mRNAs. Zinc supplementation decreased TNF-induced NF-κB DNA binding (a biomarker of oxidative stress) by EMSA in isolated MNC, compared to placebo. Zinc supplementation also increased the relative level of IL-2 mRNA in PHA-stimulated MNC, compared to placebo. Our results showed that zinc supplementation to SCD patients decreased incidence of infection, and decreased oxidative stress markers. The mRNAs of TNF-α, IL-1β, and sVCAM-1, as well as TNF-induced NF-κB activation were also decreased in the zinc-supplemented subjects, suggesting that zinc supplementation may be beneficial to in SCD patients.