Plasmacytoid dendritic cells appear inactive during sub-microscopic Plasmodium falciparum blood-stage infection, yet retain their ability to respond to TLR stimulation

Loughland, Jessica R., Minigo, Gabriela, Sarovich, Derek S., Field, Matt, Tipping, Peta E., Montes de Oca, Marcela, Piera, Kim A., Amante, Fiona H., Barber, Bridget E., Grigg, Matthew J., William, Timothy, Good, Michael F., Doolan, Denise L., Engwerda, Christian R., Anstey, Nicholas M., McCarthy, James S., and Woodberry, Tonia (2017) Plasmacytoid dendritic cells appear inactive during sub-microscopic Plasmodium falciparum blood-stage infection, yet retain their ability to respond to TLR stimulation. Scientific Reports, 7 (2596). pp. 1-11.

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Abstract

Plasmacytoid dendritic cells (pDC) are activators of innate and adaptive immune responses that express HLA-DR, toll-like receptor (TLR) 7, TLR9 and produce type I interferons. The role of human pDC in malaria remains poorly characterised. pDC activation and cytokine production were assessed in 59 malaria-naive volunteers during experimental infection with 150 or 1,800 P. falciparum-parasitized red blood cells. Using RNA sequencing, longitudinal changes in pDC gene expression were examined in five adults before and at peak-infection. pDC responsiveness to TLR7 and TLR9 stimulation was assessed in-vitro. Circulating pDC remained transcriptionally stable with gene expression altered for 8 genes (FDR < 0.07). There was no upregulation of co-stimulatory molecules CD86, CD80, CD40, and reduced surface expression of HLA-DR and CD123 (IL-3R-α). pDC loss from the circulation was associated with active caspase-3, suggesting pDC apoptosis during primary infection. pDC remained responsive to TLR stimulation, producing IFN-α and upregulating HLA-DR, CD86, CD123 at peak-infection. In clinical malaria, pDC retained HLA-DR but reduced CD123 expression compared to convalescence. These data demonstrate pDC retain function during a first blood-stage P. falciparum exposure despite sub-microscopic parasitaemia downregulating HLA-DR. The lack of evident pDC activation in both early infection and malaria suggests little response of circulating pDC to infection.

Item ID: 50077
Item Type: Article (Research - C1)
ISSN: 2045-2322
Additional Information:

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0. © The Author(s) 2017

Funders: Australian National Health and Medical Research Council (NHMRC)
Projects and Grants: NHMRC #1021198 & #1037304
Date Deposited: 05 Sep 2017 03:40
FoR Codes: 42 HEALTH SCIENCES > 4206 Public health > 420605 Preventative health care @ 50%
32 BIOMEDICAL AND CLINICAL SCIENCES > 3204 Immunology > 320404 Cellular immunology @ 25%
32 BIOMEDICAL AND CLINICAL SCIENCES > 3204 Immunology > 320405 Humoural immunology and immunochemistry @ 25%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 100%
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