Neutrophil Activities in Human Ocular Toxoplasmosis: An In Vitro Study With Human Cells

Liam M Ashander, Shervi Lie, Yuefang Ma, Elise Rochet, Jennifer M Washington, Joao M Furtado, Binoy Appukuttan, Justine R Smith

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Abstract

PURPOSE. Retinal damage in ocular toxoplasmosis reflects Toxoplasma gondii-induced cell lysis and reactive inflammation. Human retinal histopathology demonstrates the presence of neutrophils, but activities of this leukocyte subset are unstudied. We conducted in vitro experiments to evaluate roles for neutrophils as retinal taxis for T. gondii and as contributors to the inflammation.
METHODS. Human neutrophils were isolated from peripheral blood. Migration to diseaserelevant chemokines was evaluated in transwells, seeded with human retinal endothelial cells for some assays, using neutrophils infected with GT-1 strain T. gondii tachyzoites. Neutrophils were cocultured with T. gondii-infected ARPE-19 and primary human retinal pigment epithelial cells, and production of reactive oxygen species (ROS) was estimated by dihydroethidium reaction. Proteins produced by T. gondii-infected ARPE-19 cells were profiled by immunoarray, and candidate neutrophil-activating proteins were targeted with
specific blocking antibody in coculture assays.
RESULTS. Infection with T. gondii arrested neutrophil migration across retinal endothelium regardless of the presence of CXCL8. Migration to CXCL1, CXCL2, and CXCL8 also was significantly inhibited in infected neutrophils. Neutrophils generated more ROS when cocultured with infected versus uninfected ARPE-19 cells and three of four primary retinal pigment epithelial cell isolates. Infected ARPE-19 cells augmented the synthesis of 12 neutrophil-activating proteins also expressed by primary retinal pigment epithelial cells. Antibody blockade of granulocyte-macrophage colony-stimulating factor, interleukin-6 (IL-6)
and IL-18 significantly reduced ROS production by neutrophils cocultured with T. gondiiinfected ARPE-19 cells.
CONCLUSIONS. Our findings support involvement of neutrophils in retinal inflammation, but not parasite transport, in the setting of ocular toxoplasmosis.
Original languageEnglish
Pages (from-to)4652-4660
Number of pages9
JournalInvestigative Ophthalmology & Visual Science
Volume60
Issue number14
DOIs
Publication statusPublished - Nov 2019

Bibliographical note

Copyright 2019 The Authors
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. CC BY-NC-ND

Keywords

  • Neutrophil
  • Retina
  • Retinal pigment epithelium
  • Toxoplasma gondii
  • Toxoplasmosis

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