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Amniotic fluid neutrophils can phagocytize bacteria: A mechanism for microbial killing in the amniotic cavity
Author(s) -
GomezLopez Nardhy,
Romero Roberto,
GarciaFlores Valeria,
Xu Yi,
Leng Yaozhu,
Alhousseini Ali,
Hassan Sonia S.,
Panaitescu Bogdan
Publication year - 2017
Publication title -
american journal of reproductive immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.071
H-Index - 97
eISSN - 1600-0897
pISSN - 1046-7408
DOI - 10.1111/aji.12723
Subject(s) - amniotic fluid , microbiology and biotechnology , phagocytosis , biology , amniotic sac , fetus , pregnancy , genetics
Problem Neutrophils are capable of performing phagocytosis, a primary mechanism for microbial killing. Intra‐amniotic infection is characterized by an influx of neutrophils into the amniotic cavity. Herein, we investigated whether amniotic fluid neutrophils could phagocytize bacteria found in the amniotic cavity of women with intra‐amniotic infection. Methods Amniotic fluid neutrophils from women with intra‐amniotic infection were visualized by transmission electron microscopy (n=6). The phagocytic activity of amniotic fluid neutrophils from women with intra‐amniotic infection and/or inflammation (n=10) or peripheral neutrophils from healthy individuals (controls, n=3) was tested using ex vivo phagocytosis assays coupled with live imaging. Phagocytosis by amniotic fluid neutrophils was also visualized by confocal microscopy (n=10) as well as scanning and transmission electron microscopy (n=5). Results (i) Intra‐amniotic infection‐related bacteria including cocci (eg Streptococcus agalactiae ), bacilli (eg Bacteriodes fragilis and Prevotella spp.), and small bacteria without a cell wall (eg Ureaplasma urealyticum ) were found inside of amniotic fluid neutrophils; (ii) peripheral neutrophils (controls) rapidly phagocytized S. agalactiae , U. urealyticum , Gardnerella vaginalis , and Escherichia coli ; (iii) amniotic fluid neutrophils rapidly phagocytized S. agalactiae and G. vaginalis ; and (iv) amniotic fluid neutrophils slowly phagocytized U. urealyticum and E. coli ; yet, the process of phagocytosis of the genital mycoplasma was lengthier. Conclusion Amniotic fluid neutrophils can phagocytize bacteria found in the amniotic cavity of women with intra‐amniotic infection, namely S. agalactiae , U. urealyticum , G. vaginalis , and E. coli . Yet, differences in the rapidity of phagocytosis were observed among the studied microorganisms. These findings provide a host defense mechanism whereby amniotic fluid neutrophils can kill microbes invading the amniotic cavity.