Increased sTREM-1 levels identify cirrhotic patients with bacterial infection and predict their 90-day mortality.

BACKGROUND AND AIMS: Patients with cirrhosis are susceptible to bacterial infections (BIs) that are major causes of specific complications and mortality. However, the diagnosis of BIs can often be difficult in advanced disease stage since their symptoms may overlap with the ones of acute decompensation (AD). Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is released from monocytes/macrophages and neutrophils during activation and has been reported to correlate with activity of various inflammatory processes. We investigated its diagnostic and prognostic performance in patients with cirrhosis and BI. METHODS: Sera of 269 patients were assayed for sTREM-1 by ELISA (172 outpatients and 97 patients with AD of whom 56 had BI). We investigated capacity of sTREM-1 to identify patients with BI and conducted a 90-day follow-up observational study to assess its possible association with short-term mortality. RESULTS: sTREM-1 levels were significantly higher in patients with more severe liver disease, BI, and acute-on-chronic liver failure than in patients without these conditions. sTREM-1 had similar accuracy to CRP identifying BI [sTREM-1: AUROC (95%CI) 0.804 (0.711-0.897), p < 0.0001; CRP: 0.791 (0.702-0.881), p < 0.0001)] among AD patients. The combination of these two molecules and the presence of ascites into a composite score significantly increased their discriminative power (AUROC: 0.878, 95%CI: 0.812-0.944, p < 0.0001). High sTREM-1 level (>660 pg/mL) was an independent predictor of 90-day mortality in patients with BI [HR: 2.941, (95%CI: 1.009-8.573), p = 0.048] in our multivariate model. CONCLUSIONS: Use of sTREM-1 could increase the recognition of BIs in cirrhosis and help clinicians in mortality risk assessment of these patients.

Exposure to inhomogeneous static magnetic field beneficially affects allergic inflammation in a murine model.

Previous observations suggest that static magnetic field (SMF)-exposure acts on living organisms partly through reactive oxygen species (ROS) reactions. In this study, we aimed to define the impact of SMF-exposure on ragweed pollen extract (RWPE)-induced allergic inflammation closely associated with oxidative stress. Inhomogeneous SMF was generated with an apparatus validated previously providing a peak-to-peak magnetic induction of the dominant SMF component 389 mT by 39 T m(-1) lateral gradient in the in vivo and in vitro experiments, and 192 mT by 19 T m(-1) in the human study at the 3 mm target distance. Effects of SMF-exposure were studied in a murine model of allergic inflammation and also in human provoked skin allergy. We found that even a single 30-min exposure of mice to SMF immediately following intranasal RWPE challenge significantly lowered the increase in the total antioxidant capacity of the airways and decreased allergic inflammation. Repeated (on 3 consecutive days) or prolonged (60 min) exposure to SMF after RWPE challenge decreased the severity of allergic responses more efficiently than a single 30-min treatment. SMF-exposure did not alter ROS production by RWPE under cell-free conditions, while diminished RWPE-induced increase in the ROS levels in A549 epithelial cells. Results of the human skin prick tests indicated that SMF-exposure had no significant direct effect on provoked mast cell degranulation. The observed beneficial effects of SMF are likely owing to the mobilization of cellular ROS-eliminating mechanisms rather than direct modulation of ROS production by pollen NAD(P)H oxidases.

Modulatory effects of low-dose hydrogen peroxide on the function of human plasmacytoid dendritic cells.

Under normal conditions, plasmacytoid dendritic cells (pDCs) are located in peripheral lymphoid organs or circulate in the blood, from where they can migrate to sites of infection or inflammation. In inflamed tissues, pDCs can be exposed to elevated levels of reactive oxygen species produced by inflammatory cells and we presume that oxidative stress could affect the cellular responses of pDCs to microenvironmental stimuli. To explore this possibility, human pDCs isolated from peripheral blood of healthy donors were treated with H(2)O(2) and R837 (a Toll-like receptor 7 ligand), separately and in combination. Our results demonstrate that treatment with a low concentration (0.01 µM) of H(2)O(2) resulted in only slight changes in the expression of CD40, CD80, CD86, and CD83; however, low-dose H(2)O(2) markedly decreased the expression of HLA-DQ on pDCs. Exposure to H(2)O(2) did not trigger the release of IL-6, TNF-α, IL-8, or IFN-α from pDCs. Although addition of H(2)O(2) did not modify the capacity of pDCs to activate allogeneic IL-17- or IFN-γ-producing T cells, it significantly increased the ability of pDCs to stimulate IL-4-secreting T cells. Exposure of pDCs to H(2)O(2) before cocultivation with naïve autologous T cells significantly lowered IL-10 production by T cells, but did not affect IL-17 release. It was also observed that H(2)O(2)-exposed pDCs provided stronger stimuli for Th2 than for Th1 differentiation upon autologous activation, compared to untreated pDCs, possibly because of elevated surface expression of OX40-L. Most importantly, when pDCs were stimulated with R837 in the presence of H(2)O(2), decreased phenotypic activation, decreased chemokine and cytokine release, and impaired allo- and autostimulatory functions of pDCs were detected, indicating that pDCs exposed to oxidative stress in vivo may have an anti-inflammatory or tolerogenic role in regulating adaptive immune responses.

Pollen-induced oxidative stress influences both innate and adaptive immune responses via altering dendritic cell functions.

It has been demonstrated that pollen grains contain NAD(P)H oxidases that induce oxidative stress in the airways, and this oxidative insult is critical for the development of allergic inflammation in sensitized mice. On the basis of this observation, we have examined whether pollen grain exposure triggers oxidative stress in dendritic cells (DCs), altering their functions. To test this hypothesis, human monocyte-derived DCs were treated with ragweed pollen grains. Our findings show that exposure to pollen grains induces an increase in the intracellular levels of reactive oxygen species in DCs. Our data also indicate that besides the NAD(P)H oxidases, other component(s) of pollen grains contributes to this phenomenon. Elevated levels of intracellular reactive oxygen species triggered the production of IL-8 as well as proinflammatory cytokines, such as TNF-alpha and IL-6. Treatment with pollen grains initiated the maturation of DCs, strongly upregulated the membrane expression of CD80, CD86, CD83, and HLA-DR, and caused only a slight increase in the expression of CD40. The pollen-treated DCs induced the development of naive T lymphocytes toward effector T cells with a mixed profile of cytokine production. Antioxidant inhibited both the phenotypic and functional changes of DCs, underlining the importance of oxidative stress in these processes. Collectively, these data show that pollen exposure-induced oxidative stress may contribute to local innate immunity and participate in the initiation of adaptive immune responses to pollen Ags.

Identification of plasmacytoid pre-dendritic cells by one-color flow cytometry for phenotype screening.

Plasmacytoid pre-dendritic cells (pDCs) are able to prime and polarize naive T-cells, while also having an important effector function in antiviral immunity through the rapid and robust production of interferon-alpha. The main setback of pDCs investigation is the rarity and ex vivo fragility of these cells. Relative simple, reliable, and accurate methods for phenotypic analysis and functional studies of pDCs without isolation would be a great deal of interest. Fresh whole blood samples were analyzed by two-color and one-color flow cytometric pDC-identification assays. The changes in the surface expression of CD62L and HLA-DQ on pDCs in whole blood samples after 24-h treatment with imiquimod, a toll-like receptor 7 agonist, were analyzed. Our data demonstrate that the identification of pDCs in peripheral blood samples can be achieved by using only one fluorescent channel for blood dendritic cell antigen (BDCA)-4 staining combined with the light scatter parameters, thus leaving the other channels open for further phenotypic and/or functional analysis. Recently, several lines of evidence supported the involvement of pDCs in the development of several human diseases, so our new one-color identification approach may provide a useful tool for investigation of the pathomechanism of the relevant diseases by using common, 2-laser benchtop cytometers.