Time course of TLR-induced production of TNF-α and IL-12 in circulating mDCs from patients with aneurysmal subarachnoid hemorrhage.

<p>Intracellular cytokine measurement was performed in circulating mDCs from SAH patients (N = 21) on days 2, 5 and 10 and from HC (N = 11). The percentages of mDCs expressing TNF-α or IL-12 were assessed after a 3.5-hour <i>ex vivo</i> stimulation with (<b>A</b>) polyIC (TLR-3 agonist), (<b>B</b>) lipopolysaccharide (TLR-4 agonist) or (<b>C</b>) CL097 (TLR-7/8 agonist). The percentage of positive DCs without TLR-stimulation was below 1% (data not shown). The results are presented as percentages of mDCs expressing TNF-α (%TNF-α⁺) or IL-12 (% IL-12⁺). Plots represent median (Interquartile ranges). HC: healthy controls. mDCs: myeloid dendritic cells. SAH: aneurysmal subarachnoid hemorrhage. TNF-α: tumour necrosis factor -α. IL-12: intreleukin-12. * <i>P</i><0.05.</p

Gating strategy used to identify blood DC subsets and intracellular cytokines production in DCs in whole blood stimulated with TLR ligands.

<p>Whole blood samples were incubated with TLR3, 4, 7/8 or 9 ligands for 3.5-hour and then stained for identification of myeloid DC (HLA-DR+, Lin-, CD11c+, CD123-) and plasmacytoid DC (HLA-DR+, lin−, CD11c−, CD123+) together with intracellular cytokine production (TNFα, IL-12, IFNα).</p

Time course of circulating mDCs and pDCs numbers in patients with aneurysmal subarachnoid hemorrhage.

<p>Comparison of circulating (A) myeloid DC and (B) plasmacytoid DC counts in SAH patients (N = 21) on days 2, 5 and 10 compared with HC (N = 11). Plots represent median (Interquartile ranges). HC: healthy controls. SAH: aneurysmal subarachnoid hemorrhage. DCs: dendritic cells. * <i>P</i><0.05, ** <i>P</i><0.01.</p

Exploratory comparison of mDC and pDC status on day 2 in survivors and non-survivors.

<p>(<b>A</b>) The number of circulating myeloid DCs and plasmacytoid DCs were compared on day 2 between 13 survivors and 8 non-survivors. On day 2, mDCs and pDCs were stimulated <i>ex vivo</i> with polyIC (TLR-3 agonist), lipopolysaccharide (TLR-4 agonist), CL097 (TLR-7/8 agonist) and CpG (TLR-9 agonist) for 3.5 hours. (B) The percentages of mDCs expressing TNF-α or IL-12 and (C) the percentages of pDCs expressing TNF-α or IFN-α were compared between survivors and non-survivors. The percentage of positive DCs without TLR stimulation was below 1% (data not shown). The results are presented as percentages of DCs expressing TNF-α (%TNF-α⁺), IL-12 (%IL-12⁺) or IFN-α (%IFN-α⁺). Plots represent median (Interquartile ranges). * <i>P</i><0.05.</p

Characteristics of the study population.

<p>ARDS: acute respiratory distress syndrome, ICU: intensive care unit, SAH: subarachnoid hemorrhage, SAPS: simplified acute physiological score, WFNS: World Federation of Neurological Surgeons.</p

Time course of TLR-induced productions of TNF-α and IFN-α in circulating pDCs from patients with aneurysmal subarachnoid hemorrhage.

<p>Intracellular cytokine measurement was performed in circulating pDCs from SAH patients (N = 21) on days 2, 5 and 10 after brain injury and from HC (N = 11). The percentages of pDCs expressing TNF-α or IFN-α were assessed after a 3.5-hour <i>ex vivo</i> stimulation with (<b>A</b>) CL097 (TLR-7/8 agonist) or (<b>B</b>) CpG (TLR-9 agonist). The percentage of positive pDCs without TLR-stimulation was below 1% (data not shown). The results are presented as percentages of pDCs expressing TNF-α (%TNF-α⁺) or IFN-α (%IFN-α⁺). Plots represent median (Interquartile ranges). HC: healthy controls. IFN-α: interferon. pDCs: plasmacytoid dendritic cells. SAH: aneurysmal subarachnoid hemorrhage. TNF-α: tumour necrosis factor -α. *<i>P</i><0.05.</p

Impaired blood dendritic cell numbers and functions after aneurysmal subarachnoid hemorrhage.

PREVIOUS PRESENTATION: Portions of this study were presented at the Annual Congress of Société Française d'Anesthésie et de Réanimation in Paris, September 2012. BACKGROUND: Toll-like receptor (TLR) agonists are promising therapy for the prevention of nosocomial infections in critical ill patients. We aimed to analyze the TLR-reactivity of circulating dendritic cells (DC) as assessed by cytokine production after an ex vivo challenge with TLR agonists in aneurysmal subarachnoid hemorrhage (SAH) patients. METHODS AND FINDINGS: A single-center prospective observational study took place in one intensive care unit of a teaching hospital. Blood samples were harvested on days 2, 5 and 10 in 21 severe SAH patients requiring mechanical ventilation and 17 healthy controls. DC production of cytokines (Tumour Necrosis Factor, TNF-α; Interleukin, IL-12; and Interferon, IFN-α) was assessed by intracellular immunostaining on TLR-3, 4, 7/8 and 9 stimulations. SAH patients had decreased numbers of blood myeloid (mDCs) and plasmacytoid DCs (pDCs) on days 2, 5 and 10. Compared with the healthy controls, the frequency of mDCs producing TNF-α after TLR-3 stimulation was decreased in the SAH patients. The frequency of myeloid DCs producing IL-12 after TLR-3 and 4 stimulations was also decreased in the SAH patients. In contrast, the mDCs response to TLR-7/8 was not impaired in the SAH patients. The frequency of pDCs producing TNF-α(+) and IFN-α(+) on TLR-7/8 stimulation were reduced at all of the tested times in the SAH patients, whereas reactivity to TLR-9 was preserved. On day 2, the pDCs from non-survivor patients (n=8) had a decreased ability to produce IFN-α on TLR-9 stimulation compared with the survivors. CONCLUSIONS: These data suggest functional abnormalities of circulating pDCs and mDCs that could be important for immunomodulation after SAH