Zinc activates neutrophils’ oxidative burst

Abstract

Zinc has been shown to disturb the innate host defense response by interfering in the activation of neutrophils and subsequent oxidative burst, although the exact role of this metal, either as an activator or inhibitor, remains a matter of controversy among research groups. These apparent discrepancies may be due to experimental settings, through modification of zinc availability to neutrophils, or to inaccurate detections of reactive species. Thus, the main objective of the present study was to provide clarification on the role of zinc on the activation of human neutrophils and the subsequent oxidative burst. For that purpose, different detection methods and incubation media were used. The obtained results showed that phosphate buffers (PBS and HBSS) complex with zinc and interfere with the results obtained with this metal. By using Tris-G, it was clearly demonstrated that zinc, at low concentrations (5-12.5 microM), activates NADPH oxidase, mainly via protein kinase C, leading to the formation of superoxide radical (O(2*-). Higher concentrations of zinc results on a rapid dismutation of O2*- to oxygen and hydrogen peroxide, which in turn is used by myeloperoxidase to generate hypochlorous acid (HOCl).

Dietary zinc requirement of Siberian sturgeon (Acipenser baerii, Brandt 1869) juveniles, based on the growth performance and blood parameters

“…Previous studies illustrated that Zn may contribute to the host defense by interfering in the activation of neutrophils and subsequent oxidative burst (Finamore et al 2008;Freitas et al 2009), although the exact role of this trace element, either as an activator or inhibitor, remains a matter of contention between the researchers.…”

Modulation of human neutrophils' oxidative burst by flavonoids

“…The measurement of neutrophil burst was undertaken by fluorescence, by monitoring H 2 O 2 -induced oxidation of amplex red, according to a previously described procedure [31], with modifications. The reaction mixtures contained neutrophils (1 Â 10 6 cells/mL) and the following reagents at the indicated final concentrations (in a final volume of 250 mL): tested compounds at various concentrations (0e100 mM), amplex red (25 mM), HRP (0.25 U/mL) and PMA (160 nM).…”

“…The addition of ABAH to human neutrophils, stimulated with PMA, decreased the APF-dependent fluorescence signal to the level of the control assay, ruling out the involvement of HO and ONOO À [22]. The measurement of neutrophils' oxidative burst was undertaken by fluorescence, by monitoring HOClinduced oxidation of APF, according to a previously described procedure [31], with modifications. The reaction mixtures contained neutrophils (2 Â 10 6 cells/mL) and the following reagents at the indicated final concentrations (in a final volume of 250 mL): tested compounds at various concentrations (0e100 mM), PMA (160 nM) and APF (1 mM).…”

Oxidative Stress Pathway Driven by Inflammation in Gastric Mucosa

“…), and alkoxyl (RO·)] and certain nonradicals that are either oxidizing agents and/or are easily converted into radicals, such as hypochlorous acid (HOCl), ozone (O 3 ), singlet oxygen ( 1 O 2 ), and hydrogen peroxide (H 2 O 2 ). RNS are nitrogen-containing oxidants, such as nitric oxide (Freitas et al ,2010. The physiological generation of free radicals can occur as a byproduct of biological reactions in mitochondria, peroxisomes, cytochrome P-450.…”