Glutathione Reductase Facilitates Host Defense by Sustaining Phagocytic Oxidative Burst and Promoting the Development of Neutrophil Extracellular Traps

Abstract

Glutathione reductase (Gsr)3 catalyzes the reduction of glutathione disulfide to glutathione, which plays an important role in the bactericidal function of phagocytes. Since Gsr has been implicated in the oxidative burst in human neutrophils and is abundantly expressed in the lymphoid system, we hypothesized that Gsr-deficient mice would exhibit marked defects during the immune response against bacterial challenge. We report here that Gsr-null mice exhibited enhanced susceptibility to Escherichia coli challenge, indicated by dramatically increased bacterial burden, cytokine storm, striking histological abnormalities, and substantially elevated mortality. Additionally, Gsr-null mice exhibited elevated sensitivity to Staphylococcus aureus. Examination of the bactericidal functions of the neutrophils from Gsr-deficient mice in vitro revealed impaired phagocytosis and defective bacterial killing activities. Although Gsr catalyzes the regeneration of glutathione, a major cellular antioxidant, Gsr-deficient neutrophils paradoxically produced far less reactive oxygen species upon activation both ex vivo and in vivo. Unlike wildtype neutrophils that exhibited a sustained oxidative burst upon stimulation with phorbol ester and fMLP, Gsr-deficient neutrophils displayed a very transient oxidative burst that abruptly ceased shortly after stimulation. Likewise, Gsr-deficient neutrophils also exhibited an attenuated oxidative burst upon encountering E. coli. Biochemical analysis revealed that the hexose monophosphate shunt was compromised in Gsr-deficient neutrophils. Moreover, Gsr-deficient neutrophils displayed a marked impairment in the formation of neutrophil extracellular traps, a bactericidal mechanism which operates after neutrophil death. Thus, Gsr-mediated redox regulation is crucial for bacterial clearance during host defense against massive bacterial challenge.

Quercetin Promotes the Expression of Genes Involved in Phagocytosis in Bovine Neutrophils

“…Slides were fixed with absolute ethanol, stained with Dip Quick and examined with a Zeiss Axio Scope A1 (Carl Zeiss, Thornwood, NY, USA). Percentage of phagocytosis with different treatments were manually counted from 5 random fields (100 cells per field) at 10× objective by three well-trained observers in a blinded technique (Yan et al, 2012).…”

049 Physiological and molecular mechanisms associated with performance, immunometabolic status, and liver function in transition dairy cows fed rumen-protected methionine or choline

“…Studies with GSH reductase-deficient mice indicated they had an impaired oxidative burst and produced less ROM due to GSH depletion (Yan et al, 2012). In agreement with this, reduced neutrophil oxidative burst in humans was detected in response to chronic oxidative stress (Amer and Fibach, 2005).…”

“…Although the intensity of the oxidative burst in monocytes stimulated by E. coli has been suggested to be lower than in PMNL (Yan et al, 2012), monocytes also have the ability to phagocytose and carry out oxidative burst (Keogh et al, 2011). The fact that CHOL supplementation lead to greater monocyte oxidative burst without elevating plasma Ca 2+ suggest existence of alternative mechanisms.…”

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“…While Sytox ® Green gives a bright green picture when excited with the 450-490 nm laser, Sytox ® Orange is excited by 520-550 nm source and gives a bright orange light [35,36]. Picogreen ® and Hoechst 33258 -based assay are also used to check the NETs-DNA [31,33,37,39]. Both dyes are ultra sensitive fluorescent nucleic acid stains for quantifying double-stranded DNA in solution.…”