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Immunol Res. 2017 Jun;65(3):706-712. doi: 10.1007/s12026-017-8905-3.

Validation of an enzyme-linked immunosorbent assay for the quantification of citrullinated histone H3 as a marker for neutrophil extracellular traps in human plasma.

Author information

1
Department of Clinical Sciences, Danderyd Hospital, Division of Internal Medicine, Karolinska Institutet, Stockholm, Sweden.
2
Department of Clinical Sciences, Danderyd Hospital, Department of Anesthesia and Intensive Care, Karolinska Institutet, Stockholm, Sweden.
3
Department of Biology, Boston University, Boston, MA, 02215, USA.
4
Stress Research Institute, Stockholm University, Stockholm, Sweden.
5
Department of Clinical Neuroscience, Division of Psychology, Karolinska Institutet, Solna, Stockholm, Sweden.
6
Department of Clinical Chemistry, Karolinska University Hospital, Stockholm, Sweden.
7
Department of Medical Biochemistry and Biophysics, Division of Translational Medicine and Chemical Biology, Karolinska Institutet, Science for Life Laboratory, Stockholm, Sweden.
8
Department of Clinical Sciences, Danderyd Hospital, Division of Cardiovascular Medicine, Karolinska Institutet, Stockholm, Sweden.
9
Department of Clinical Sciences, Danderyd Hospital, Division of Internal Medicine, Karolinska Institutet, Stockholm, Sweden. melanie.demers@ki.se.

Abstract

There is an emerging interest in the diverse functions of neutrophil extracellular traps (NETs) in a variety of disease settings. However, data on circulating NETs rely largely upon surrogate NET markers such as cell-free DNA, nucleosomes, and NET-associated enzymes. Citrullination of histone H3 by peptidyl arginine deiminase 4 (PAD4) is central for NET formation, and citrullinated histone H3 (H3Cit) is considered a NET-specific biomarker. We therefore aimed to optimize and validate a new enzyme-linked immunosorbent assay (ELISA) to quantify the levels of H3Cit in human plasma. A standard curve made of in vitro PAD4-citrullinated histones H3 allows for the quantification of H3Cit in plasma using an anti-histone antibody as capture antibody and an anti-histone H3 citrulline antibody for detection. The assay was evaluated for linearity, stability, specificity, and precision on plasma samples obtained from a human model of inflammation before and after lipopolysaccharide injection. The results revealed linearity and high specificity demonstrated by the inability of detecting non-citrullinated histone H3. Coefficients of variation for intra- and inter-assay variability ranged from 2.1 to 5.1% and from 5.8 to 13.5%, respectively, allowing for a high precision. Furthermore, our results support an inflammatory induction of a systemic NET burden by showing, for the first time, clear intra-individual elevations of plasma H3Cit in a human model of lipopolysaccharide-induced inflammation. Taken together, our work demonstrates the development of a new method for the quantification of H3Cit by ELISA that can reliably be used for the detection of NETs in human plasma.

KEYWORDS:

Elisa; H3Cit; Human plasma; LPS-induced inflammation; NETs; PAD4

PMID:
28161762
PMCID:
PMC5440486
DOI:
10.1007/s12026-017-8905-3
[Indexed for MEDLINE]
Free PMC Article

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