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Leishmania amazonensis amastigotes trigger neutrophil activation but resist neutrophil microbicidal mechanisms.

ABSTRACT: Neutrophils are the first cells to infiltrate to the site of Leishmania promastigote infection, and these cells help to reduce parasite burden shortly after infection is initiated. Several clinical reports indicate that neutrophil recruitment is sustained over the course of leishmaniasis, and amastigote-laden neutrophils have been isolated from chronically infected patients and experimentally infected animals. The goal of this study was to compare how thioglycolate-elicited murine neutrophils respond to L. amazonensis metacyclic promastigotes and amastigotes derived from axenic cultures or from the lesions of infected mice. Neutrophils efficiently internalized both amastigote and promastigote forms of the parasite, and phagocytosis was enhanced in lipopolysaccharide (LPS)-activated neutrophils or when parasites were opsonized in serum from infected mice. Parasite uptake resulted in neutrophil activation, oxidative burst, and accelerated neutrophil death. While promastigotes triggered the release of tumor necrosis factor alpha (TNF-?), uptake of amastigotes preferentially resulted in the secretion of interleukin-10 (IL-10) from neutrophils. Finally, the majority of promastigotes were killed by neutrophils, while axenic culture- and lesion-derived amastigotes were highly resistant to neutrophil microbicidal mechanisms. This study indicates that neutrophils exhibit distinct responses to promastigote and amastigote infection. Our findings have important implications for determining the impact of sustained neutrophil recruitment and amastigote-neutrophil interactions during the late phase of cutaneous leishmaniasis.

SUBMITTER: Carlsen ED

PROVIDER: S-EPMC3811833 | biostudies-other | 2013 Nov

REPOSITORIES: biostudies-other

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Leishmania amazonensis amastigotes trigger neutrophil activation but resist neutrophil microbicidal mechanisms.

Carlsen Eric D ED Hay Christie C Henard Calvin A CA Popov Vsevolod V Garg Nisha Jain NJ Soong Lynn L

Infection and immunity 20130805 11

Neutrophils are the first cells to infiltrate to the site of Leishmania promastigote infection, and these cells help to reduce parasite burden shortly after infection is initiated. Several clinical reports indicate that neutrophil recruitment is sustained over the course of leishmaniasis, and amastigote-laden neutrophils have been isolated from chronically infected patients and experimentally infected animals. The goal of this study was to compare how thioglycolate-elicited murine neutrophils re ...[more]

PMID: 23918780

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Project description:In mammals, resident dermal macrophages (MÎ¦s) are subverted by Leishmania (L.) amazonensis amastigotes as host cells permissive for parasite multiplication. These Leishmania are living within a communal parasitophorous vacuole (PV) and are expected to trigger unique MÎ¦ transcriptional signatures. We performed a transcription profiling of mouse MÎ¦s harboring amastigotes to get insights into their reprogramming as host cells for parasite multiplication. BALB/c mouse bone marrow-derived MÎ¦s were either loaded or not with four amastigotes on average. Twenty four hours later, when amastigotes multiply, total RNA from MÎ¦ cultures was prepared, amplified and hybridized onto Affymetrix Mouse430_2 GeneChipsÂ®. The outcome recorded a total of 1,248 probe-sets showing significant differential expression. Comparable fold-change values for a handful of genes were obtained between Affymetrix technology and the more sensitive RTqPCR method. Ingenuity Pathway Analysis softwareÂ® pinpointed the up-regulation of the sterol biosynthesis pathway (P-value = 1.31e-02) involving several genes (1.95 to 4.30 fold-change values), and the modulation of various genes involved in polyamine synthesis and in pro/counter-inflammatory signaling. Our findings suggest that amastigotes exploit the MÎ¦ lipid and polyamine pathways to multiply efficiently, and induce a counter-inflammatory environment to expand their dermis niche. Experiment Overall Design: Mice, MÎ¦s and amastigotes: Experiment Overall Design: Swiss nu/nu and BALB/c mice were used (following National Scientific Ethics Committee guidelines) for L. amazonensis (LV79 strain, MPRO/BR/1972/M1841) amastigote propagation and to prepare bone marrow-derived MÎ¦s, respectively. Amastigotes were added at a multiplicity of 4 amastigotes per MÎ¦. Parasite-harboring MÎ¦s (>98%; samples I1, I2 and I3) and parasite-free ones (samples UI1, UI2 and UI3) were cultured at 34Â°C (LV79 permissive temperature) for 24h. Experiment Overall Design: Real-time quantitative PCR: Experiment Overall Design: Total RNA from various biological samples including those used for hybridization experiments were reverse transcribed into cDNA using random hexamers (Roche Diagnostics) and Moloney Murine Leukemia Virus Reverse Transcriptase (Invitrogen Life Technologies). RTqPCR was performed using LightCycler-480 system (Roche) with primers designed with LightCycler Probe Design 1.0 software.Target genes primer sequences, amplicon melting temperatures and amplification efficiencies are available upon request. Gene expression analysis using qBase program allowed determining the normalized relative quantities between parasite-free and parasite-harboring MÎ¦s.

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Leishmania amazonensis amastigotes trigger neutrophil activation but resist neutrophil microbicidal mechanisms.

Publications

Leishmania amazonensis amastigotes trigger neutrophil activation but resist neutrophil microbicidal mechanisms.

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