Elsevier

Journal of Proteomics

Volume 216, 30 March 2020, 103652
Journal of Proteomics

In-depth proteomics and natural peptidomics analyses reveal antibacterial peptides in human endometrial fluid

https://doi.org/10.1016/j.jprot.2020.103652Get rights and content
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Highlights

  • In-depth proteomics analysis of the human endometrial fluid, enhancing previous approaches.

  • Characterisation of the human endometrial fluid peptidome.

  • New insights into antimicrobial peptide activity in the human endometrial fluid.

Abstract

The composition of endometrial fluid reflects the status of the endometrium; it is a good atraumatic source of information on embryo implantation processes and possible pathological conditions. Although some attempts have been made to characterise its proteome, the catalogue of its proteins remains incomplete and little has been done to analyse the natural peptides it contains. Here, we present a comprehensive analysis of the proteins and natural peptides of the endometrial fluid. The protein content of samples from 11 individuals was analysed using the novel timsTOF Pro mass spectrometer. We identified 4694 proteins with at least one peptide with FDR < 1%, of which 2261 were found in >50% of the samples. A pooled endometrial fluid sample was used for isolation and analysis of the natural peptides. Mass spectrometry analysis identified 3899 naturally occurring peptides from 238 different proteins. Among these, there were some putative natural antibacterial peptides. Antimicrobial activity of peptides derived from elafin and Cu/Zn superoxide dismutase was confirmed using microbiological assays. Our results substantially expand the catalogue of known endometrial fluid proteins and provide extensive new information on the natural peptide content of this fluid.

Significance

The endometrial fluid contains many proteins whose clinical relevance is still unknown. Some might be merely markers of endometrial function, but others might play a role in embryo nutrition and/or implantation. Human endometrial fluid analysis might open the door to new developments in embryo transfer strategies in in-vitro fertilisation programmes and lead to improvements in the composition of embryo culture media. Here, we report, for the first time, antimicrobial activity of endometrial fluid peptides. Such peptides could play an important role in the balance of the recently described uterine microbiota.

Keywords

FASP
Human endometrial fluid
Natural peptides
Peptidome
Antimicrobial peptides

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