Neutrophils Contribute to the Protection Conferred by ArtinM against Intracellular Pathogens: A Study on Leishmania major

PLoS Negl Trop Dis. 2016 Apr 8;10(4):e0004609. doi: 10.1371/journal.pntd.0004609. eCollection 2016 Apr.

Abstract

ArtinM, a D-mannose binding lectin from Artocarpus heterophyllus, has immunomodulatory activities through its interaction with N-glycans of immune cells, culminating with the establishment of T helper type 1 (Th1) immunity. This interaction protects mice against intracellular pathogens, including Leishmania major and Leishmania amazonensis. ArtinM induces neutrophils activation, which is known to account for both resistance to pathogens and host tissue injury. Although exacerbated inflammation was not observed in ArtinM-treated animals, assessment of neutrophil responses to ArtinM is required to envisage its possible application to design a novel immunomodulatory agent based on carbohydrate recognition. Herein, we focus on the mechanisms through which neutrophils contribute to ArtinM-induced protection against Leishmania, without exacerbating inflammation. For this purpose, human neutrophils treated with ArtinM and infected with Leishmania major were analyzed together with untreated and uninfected controls, based on their ability to eliminate the parasite, release cytokines, degranulate, produce reactive oxygen species (ROS), form neutrophil extracellular traps (NETs) and change life span. We demonstrate that ArtinM-stimulated neutrophils enhanced L. major clearance and at least duplicated tumor necrosis factor (TNF) and interleukin-1beta (IL-1β) release; otherwise, transforming growth factor-beta (TGF-β) production was reduced by half. Furthermore, ROS production and cell degranulation were augmented. The life span of ArtinM-stimulated neutrophils decreased and they did not form NETs when infected with L. major. We postulate that the enhanced leishmanicidal ability of ArtinM-stimulated neutrophils is due to augmented release of inflammatory cytokines, ROS production, and cell degranulation, whereas host tissue integrity is favored by their shortened life span and the absence of NET formation. Our results reinforce the idea that ArtinM may be considered an appropriate molecular template for the construction of an efficient anti-infective agent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artocarpus / chemistry
  • Cell Degranulation
  • Cell Survival
  • Cells, Cultured
  • Cytokines / metabolism
  • Humans
  • Immunologic Factors / isolation & purification
  • Immunologic Factors / pharmacology*
  • Lectins / isolation & purification
  • Lectins / pharmacology*
  • Leishmania major / immunology*
  • Leishmania major / physiology
  • Neutrophils / drug effects
  • Neutrophils / immunology*
  • Neutrophils / parasitology*
  • Neutrophils / physiology
  • Reactive Oxygen Species / metabolism

Substances

  • Cytokines
  • Immunologic Factors
  • Lectins
  • Reactive Oxygen Species

Grants and funding

This study was supported by grants from São Paulo Research Foundation (grants FAPESP #2009/60642-3, #2012/13419-7, and #2013/04088-0), and Financiadora de Estudos e Projetos (grant FINEP# 01100455900). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.