Upon viral exposure, myeloid and plasmacytoid dendritic cells produce 3 waves of distinct chemokines to recruit immune effectors - PubMed (original) (raw)

Upon viral exposure, myeloid and plasmacytoid dendritic cells produce 3 waves of distinct chemokines to recruit immune effectors

Bernard Piqueras et al. Blood. 2006.

Abstract

Host response to viral infection involves distinct effectors of innate and adaptive immunity, whose mobilization needs to be coordinated to ensure protection. Here we show that influenza virus triggers, in human blood dendritic-cell (DC) subsets (ie, plasmacytoid and myeloid DCs), a coordinated chemokine (CK) secretion program with 3 successive waves. The first one, occurring at early time points (2 to 4 hours), includes CKs potentially attracting effector cells such as neutrophils, cytotoxic T cells, and natural killer (NK) cells (CXCL16, CXCL1, CXCL2, and CXCL3). The second one occurs within 8 to 12 hours and includes CKs attracting effector memory T cells (CXCL8, CCL3, CCL4, CCL5, CXCL9, CXCL10, and CXCL11). The third wave, which occurs after 24 to 48 hours, when DCs have reached the lymphoid organs, includes CCL19, CCL22, and CXCL13, which attract naive T and B lymphocytes. Thus, human blood DC subsets carry a common program of CK production, which allows for a coordinated attraction of the different immune effectors in response to viral infection.

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Figures

Figure 1.

Transcription of CK genes in blood DC subsets exposed to influenza virus. (A) Total RNA was extracted from pDCs and mDCs of 6 healthy donors after sort (before), and of 6 other donors 24 hours after culture with influenza virus (after). Amplified cRNA was hybridized on Affymetrix HG-U133 chips. Gene expression was analyzed with GeneSpring 6.1 software. Each probe set was normalized with a per chip normalization to the 50th percentile, and a per gene normalization to the median of each gene. Within the most differentially expressed probe sets (P < .05 with Bonferroni multiple testing correction, or > 2 fold-change), we identified a set of 20 chemokine probes. (B) Transcription of 44 different chemokines. After per-chip normalization to the 50th percentile, the normalized intensity values of each probe set were used as a measurement of its expression. (C) Normalized expression of the most significantly transcribed chemokines (3-fold over the 50th percentile). Each bar is representative of mean normalized intensity plus or minus standard error for chemokine's gene expression in pDCs and mDCs from 6 healthy donors before infection or 6 healthy donors after infection.

Figure 2.

Kinetics of CK expression. Blood DCs isolated from 4 donors were exposed to influenza virus. Total RNA was processed and gene expression was analyzed after per chip normalization as in Figure 1 (left). Protein expression was evaluated by multiplex cytokine analysis (Luminex; CCL2, CCL3, CCL4, CCL5, CXCL8, CXCL9, and CXCL10) or by ELISA (CXCL16, CCL19, CCL22, and CXCL13) (right). CXCL16 and CXCL4 are expressed before infection and their expression constantly decreases upon viral stimulation (A-D). CXCL1, CXCL2, CXCL3, and CXCL8 are transiently expressed between 2 and 8 hours, longer for CXCL8 (E-H). Inflammatory chemokines (CCL3, CCL4, CCL5) and interferon-dependent chemokines (CXCL9, CXCL10, CXCL11) expression is up-regulated between 2 and 8 hours and then decreases progressively (I-P). CCL19, CCL22, and CXCL13 are significantly expressed after 8 to 24 hours (Q-T). Finally, CCL2 and CCL8 are expressed only by infected mDCs (U-X).

Figure 3.

Migration of PBMCs toward supernatants of blood DC subsets exposed to influenza virus. Purified blood DCs from 4 donors were exposed to influenza virus for 24 hours and supernatants were used in a migration assay. Supernatant (30 μL) was added to the lower part of a migration chamber and 7.5 × 105 PBMCs were added on top of a 3-μm–diameter pore filter. After a 45-minute incubation at 37°C, with 5% CO2, migrating cells were harvested, counted, and stained for flow cytometry. Migration of each cell subset in the different conditions is expressed as absolute cell number ×103 in the lower well after a 45-minute incubation. Paired t test. Blue bars indicate medium + virus; red, pDC SN; and green, mDC SN. (A) Total cell counts by trypan blue exclusion. (B-D) Counts of CD14+ monocytes (B); CD16+CD56+ NK cells (C); and CD4+ effector memory T cells (D). BC = buffy coat.

Figure 4.

Model of DC migration and sequential effector-cell attraction. Blood DCs expressing, at the steady state, CXCR4 and CXCR3, can migrate through virally infected tissues, expressing CXCL12, CXCL9, CXCL10, and CXCL11. There, they can penetrate the tissues. Upon encountering the virus, they start to release at the first step CXCL16, CXCL1, CXCL2, CXCL3, CXCL7, and CXCL8. These CKs attract Th1 effectors cells expressing CXCR6 and neutrophils expressing CXCR2 (no. 1 in figure). Later, activated DCs secrete CCL2, CCL3, CCL4, CCL5, and CCL8, which essentially attract CCR5-expressing memory T lymphocytes and monocytes (no. 2). Upon maturation, DCs up-regulate CCR7 and down-regulate CXCR4, allowing, with

-selectin expression, their migration to high endothelial venules expressing CCL21 in lymphoid organs. In the T-cell area, activated pDCs secrete CCL19 and CXCL13, which respectively attract CCR7-expressing naive T cells and CXCR5-expressing naive B cells (no. 3). They also secrete CCL22, attracting CCR4-expressing Th2 and CD4+CD25+ regulatory cells (no. 3).

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Upon viral exposure, myeloid and plasmacytoid dendritic cells produce 3 waves of distinct chemokines to recruit immune effectors - PubMed (original) (raw)