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Gut. 2017 Mar;66(3):519-529. doi: 10.1136/gutjnl-2015-310378. Epub 2016 Feb 9.

Defective monocyte oxidative burst predicts infection in alcoholic hepatitis and is associated with reduced expression of NADPH oxidase.

Author information

1
Department of Hepatology and Gastroenterology, Imperial College, London, UK.
2
Department of Hepatology, King's College Hospital, Institute of Liver Studies, London, UK.
3
Department of Hepatology, University College, London, UK.
4
Chelsea and Westminster Hospital, London, UK.
5
Department of Hepatology, Royal Free Hospital, London, UK.
6
Department of Gastroenterology, Royal London Hospital, London, UK.

Abstract

OBJECTIVE:

In order to explain the increased susceptibility to serious infection in alcoholic hepatitis, we evaluated monocyte phagocytosis, aberrations of associated signalling pathways and their reversibility, and whether phagocytic defects could predict subsequent infection.

DESIGN:

Monocytes were identified from blood samples of 42 patients with severe alcoholic hepatitis using monoclonal antibody to CD14. Phagocytosis and monocyte oxidative burst (MOB) were measured ex vivo using flow cytometry, luminometry and bacterial killing assays. Defects were related to the subsequent development of infection. Intracellular signalling pathways were investigated using western blotting and PCR. Interferon-γ (IFN-γ) was evaluated for its therapeutic potential in reversing phagocytic defects. Paired longitudinal samples were used to evaluate the effect of in vivo prednisolone therapy.

RESULTS:

MOB, production of superoxide and bacterial killing in response to Escherichia coli were markedly impaired in patients with alcoholic hepatitis. Pretreatment MOB predicted development of infection within two weeks with sensitivity and specificity that were superior to available clinical markers. Accordingly, defective MOB was associated with death at 28 and 90 days. Expression of the gp91 phox subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was reduced in patients with alcoholic hepatitis demonstrating defective MOB. Monocytes were refractory to IFN-γ stimulation and showed high levels of a negative regulator of cytokine signalling, suppressor of cytokine signalling-1. MOB was unaffected by 7 days in vivo prednisolone therapy.

CONCLUSIONS:

Monocyte oxidative burst and bacterial killing is impaired in alcoholic hepatitis while bacterial uptake by phagocytosis is preserved. Defective MOB is associated with reduced expression of NADPH oxidase in these patients and predicts the development of infection and death.

KEYWORDS:

ALCOHOLIC LIVER DISEASE; BACTERIAL INFECTION; IMMUNOLOGY IN HEPATOLOGY

PMID:
26860769
PMCID:
PMC5534772
DOI:
10.1136/gutjnl-2015-310378
[Indexed for MEDLINE]
Free PMC Article

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