Aikaterini Pistiki

Oxidative stress is considered pivotal in the pathophysiology of sepsis. Oxidants modulate heat shock proteins (Hsp), interleukins (IL), and cell death pathways, including apoptosis. This multicenter prospective observational study was designed to ascertain whether an oxidant/antioxidant imbalance is an independent sepsis discriminator and mortality predictor in intensive care unit (ICU) patients with sepsis (n = 145), compared to non-infectious critically ill patients (n = 112) and healthy individuals (n = 89). Serum total oxidative status (TOS) and total antioxidant capacity (TAC) were measured by photometric testing. IL-6, -8, -10, -27, Hsp72/90 (ELISA), and selected antioxidant biomolecules (Ζn, glutathione) were correlated with apoptotic mediators (caspase-3, capsase-9) and the central anti-apoptotic survivin protein (ELISA, real-time PCR). A wide scattering of TOS, TAC, and TOS/TAC in all three groups was demonstrated. Septic patients had an elevated TOS/TAC, compared to non-infectious critically ill patients and healthy individuals (p = 0.001). TOS/TAC was associated with severity scores, procalcitonin, IL-6, -10, -27, IFN-γ, Hsp72, Hsp90, survivin protein, and survivin isoforms -2B, -ΔΕx3, -WT (p < 0.001). In a propensity probability (age-sex-adjusted) logistic regression model, only sepsis was independently associated with TOS/TAC (Exp(B) 25.4, p < 0.001). The AUC_TOS/TAC (0.96 (95% CI = 0.93–0.99)) was higher than AUC_TAC (z = 20, p < 0.001) or AUC_TOS (z = 3.1, p = 0.002) in distinguishing sepsis. TOS/TAC, TOS, survivin isoforms -WT and -2B, Hsp90, IL-6, survivin protein, and repressed TAC were strong predictors of mortality (p < 0.01). Oxidant/antioxidant status is impaired in septic compared to critically ill patients with trauma or surgery and is related to anti-apoptotic, inflammatory, and innate immunity alterations. The unpredicted TOS/TAC imbalance might be related to undefined phenotypes in patients and healthy individuals.

Evidence on the changes in the absolute counts of monocyte subpopulations in sepsis is missing. Firstly, absolute counts of circulating CD14pos/HLA-DRpos/CD45pos monocytes were measured by flow cytometry in 70 patients with Gram-negative sepsis and in 10 healthy volunteers. In the second phase, immunophenotyping was performed and the absolute count of circulating inflammatory monocytes and of circulating CD14dim/CD16pos/CD45pos patrolling monocytes were measured in another 55 patients and 10 healthy volunteers. Measurements were repeated on days 3, 7, and 10. Results were correlated with survival after 28 days. Greater numbers of CD14pos/HLA-DRpos/CD45pos monocytes were found on day 1 in survivors compared to nonsurvivors (p = 0.030). Receiver operating characteristic (ROC) analysis showed that a cutoff higher than 337 cells/mm3 on day 1 could discriminate between survivors and nonsurvivors with a positive predictive value (PPV) of 91.1%. Logistic regression including Sequential Organ Failure Assessment (SOFA) score and Acute Physiology and Chronic Health Evaluation (APACHE) II score showed that an absolute count greater than 337 cells/mm3 was independently associated with unfavorable outcome (odds ratio (OR) 0.19, p = 0.050). The absolute counts of inflammatory and of CD14dim/CD16pos/CD45pos monocytes were greater in patients than healthy controls during the entire 10 days of follow-up. The absolute counts on day 3 of CD14dim/CD16pos/CD45pos monocytes were greater in survivors than nonsurvivors (p = 0.027). ROC analysis revealed that the cutoff at 27 cells/mm3 could discriminate between survivors and nonsurvivors with PPV of 94.1%. Logistic regression including age, SOFA score, and APACHE II score showed that an absolute count greater than 27 cells/mm3 was independently associated with unfavorable outcome (OR 0.06, p = 0.033). Logistic regression analysis showed that intra-abdominal infection on day 1 was predictive of low CD14dim/ CD16pos/CD45pos count on day 3. Circulating counts of inflammatory and patrolling monocytes are greatly increased in Gram-negative sepsis. Absolute counts of CD14pos/HLA-DRpos/CD45pos monocytes on day 1 and CD14dim/CD16pos/CD45pos monocytes on day 3 are independently associated with final outcome. ClinicalTrials.gov, NCT01223690 . Registered retrospectively on 18 October 2010.

Platelet activation mediates systemic inflammatory response during infection. However, data on platelet reactivity (PR) varies among different settings. We assessed PR along different stages of sepsis and tried to predict for determinants of its variance. In parallel, we evaluated it as an early bedside diagnostic biomarker. This was an observational prospective cohort study. Incoming patients were assorted to distinct groups of uncomplicated infection, sepsis, and severe sepsis/septic shock. A control group of healthy volunteers was used as comparison. PR was assessed using the bedside point-of-care VerifyNow assay, in P2Y₁₂ reaction units (PRU) alongside with levels of major inflammatory markers and whole blood parameters. A total of 101 patients and 27 healthy volunteers were enrolled. PR significantly and reversibly increases during sepsis compared to uncomplicated infection and healthy controls (244 ± 66.7 vs 187.33 ± 60.98, p < 0.001 and 192.17 ± 47.51, p < 0.001, respectively). In severe sepsis, PR did not significantly differ compared to other groups. Sepsis stage uniquely accounts for 15.5% of PR in a linear regression prediction model accounting for 30% of the variance of PR (F = 8.836, p < 0.001). PRU >253 had specificity of 91.2% and sensitivity of 40.8% in discriminating septic from non-septic patients. The addition of PRU to SOFA and qSOFA scores significantly increased their c-statistic (AUC SOFA + PRU, 0.867 vs SOFA, 0.824, p < 0.003 and AUC qSOFA + PRU, 0.842 vs qSOFA, 0.739, p < 0.001), making them comparable (AUC SOFA + PRU vs qSOFA + PRU, p = 0.4). PR significantly and reversibly increases early in sepsis, but seems to exhaust while disease progresses. Bedside assessment of PR can provide robust discriminative accuracy in the early diagnosis of septic patients.

Current knowledge suggests that small intestinal overgrowth participates in the pathogenesis of irritable bowel syndrome. It is questionable if this association is modulated by intake of proton pump inhibitors (PPIs). In a prospective study, quantitative cultures of duodenal aspirates were performed for aerobic species in 897 consecutive patients undergoing upper GI tract endoscopy. SIBO was defined as equal to or more than 103 cfu/ml. The effect of PPI intake on the relationship between SIBO and IBS was the primary endpoint. Analysis among patients without any history of PPI intake (n = 713) showed that odds ratio (OR) for IBS in the event of SIBO was 5.63 (3.73–8.51, p < 0.0001); this was 4.16 (1.91–9.06) when analysis was done among patients with history of PPI intake (n = 184, p: 0.498 between patients without and with PPI intake). Multiple logistic regression analysis found that factors independently associated with SIBO were age above or equal to 60 years (OR: 2.36), body mass index more than or equal to 22 kg/m2 (OR: 0.60), presence of IBS (OR: 6.29), type 2 diabetes mellitus (OR: 1.59) and gastritis (OR: 0.47). The association between IBS and SIBO was completely independent from PPI intake. Although gastritis was protective against SIBO, results show that PPI intake cannot prime SIBO.

Objectives To investigate the effect of dexamethasone on triggering receptor expressed on myeloid cells-1 (TREM-1). Methods Lethal infection was induced by Pseudomonas aeruginosa in 96 mice, both wild-type and TNF-/-; mice were pre-treated either with saline or with dexamethasone/hydrocortisone. TREM-1 on neutrophil membranes was measured after sacrifice. Monocytes of the U937 human cell line were challenged by LPS and heat-killed P.aeruginosa with the sequential addition of dexamethasone, hydrocortisone, TNFα and anti-TNF. Expression of TREM-1 and release of soluble TREM-1 (sTREM-1) in supernatants were measured. Results Pre-treatment with dexamethasone prolonged animal survival; this was not shown with hydrocortisone pre-treatment. Mice pre-treated with dexamethasone showed decreased expression of TREM-1 on neutrophils. LPS and P.aeruginosa induced the expression of TREM-1 and the release of sTREM-1 by U937 monocytes; that was decreased upon addition of dexamethasone but not of hydrocortisone. The effect of dexamethasone was enhanced upon addition of TNFα and lost in the presence of anti-TNF. The effect was also lost in TNF-/- mice. Gene expression of TREM-1 by U937 monocytes was decreased after treatment with dexamethasone. Conclusions TREM-1/sTREM-1 is a novel site of action of dexamethasone. This action is related with down-regulation of gene expression and is modulated by TNFα.

Introduction: Monosodium urate monohydrate (MSU) crystals synergize with various toll-like receptor (TLR) ligands to induce cytokine production via activation of the NOD-like receptor (NLR) family, pyrin domain-containing 3 (NLPR3) inflammasome. This has been demonstrated in vitro using human cell lines or monocytes of healthy volunteers. In the present study, we have investigated the effect of MSU crystals and of their combination with TLR ligands in peripheral blood mononuclear cells (PBMC) of patients with gout. Methods: PBMCs from 18 patients with primary gout and 12 healthy donors were exposed to MSU crystals in the presence or absence of saturated fatty acid C18:0 (free fatty acid, TLR2 ligand), palmitoyl-3-cystein (Pam₃Cys, TLR1/2 ligand) and fibroblast stimulating factor-1 (FSL-1, TLR 2/6 ligand). Production of IL-1β, IL-6, IL-8, IL-17 and tumor necrosis factor alpha (TNFα) was determined by ELISA. mRNA transcripts of IL-1β were measured by real-time PCR. Results: MSU crystals alone failed to induce IL-1β, IL-6 or TNFα in both patients and control groups, but a stronger synergy between MSU/Pam₃Cys and MSU/C18:0 for the induction of IL-1β was found in patients with gout compared to healthy controls. IL-6, but not IL-8, followed the kinetics of IL-1β. No production of the neutrophil-recruiting IL-17 was detectable after stimulation of the patients' PBMCs with MSU in both the presence or absence of TLR ligands. No change of gene transcripts of IL-1β after stimulation with MSU and Pam₃Cys or with MSU and C18:0 was found. A positive correlation was found between synergy in IL-1β production from PBMCs of patients between C18:0 and MSU crystals, as well as the annual number of attacks of acute gouty arthritis (r_s: +0.649, P: 0.022). Conclusions: The synergy between MSU crystals and TLR-2 ligands is more prominent in patients with gout than in controls. This is likely mediated by the enhanced maturation of pro-IL-1β into IL-1β.

Apoptosis of lymphocytes is considered a late sequelum in the sepsis cascade. The role of apoptosis of lymphocytes as a driver of final outcome was investigated.

Current knowledge on the exact ligand causing expression of TREM-1 on neutrophils and monocytes is limited. The present study aimed at the role of underlying infection and of the causative pathogen in the expression of TREM-1 in sepsis.