Mitochondrial DNA and Toll-Like Receptor-9 Are Associated With Mortality in Critically Ill Patients.

OBJECTIVES: Despite underlying pathologies leading to ICU admittance are heterogeneous, many patients develop a systemic inflammatory response syndrome often in the absence of microbial pathogens. Mitochondrial DNA that shows similarities to bacterial DNA may be released after tissue damage and activates the innate immune system by binding to toll-like receptor-9 on immune cells. The aim of this study was to analyze whether levels of mitochondrial DNA are associated with 30-day survival and whether this predictive value is modified by the expression of its receptor toll-like receptor-9. DESIGN: Single-center, prospective, observational study. SETTING: A tertiary ICU in a university hospital. PATIENTS: Two hundred twenty-eight consecutive patients admitted to a medical ICU between August 2012 and August 2013. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Blood was taken within 24 hours after ICU admission, and the levels of circulating mitochondrial DNA were quantified by real-time polymerase chain reaction. Toll-like receptor-9 expression in monocytes was measured by flow cytometry. Median acute physiology and chronic health evaluation II score was 20, and 30-day mortality was 25%. Median mitochondrial DNA levels at admission were significantly higher in nonsurvivors when compared with survivors (26.9, interquartile range = 11.2-60.6 ng/mL vs 19.7, interquartile range = 9.5-34.8 ng/mL; p < 0.05). Patients with plasma levels of mitochondrial DNA in the highest quartile (mitochondrial DNA > 38.2 ng/mL) had a 2.6-fold higher risk (p < 0.001) of dying, independently of age, gender, diagnosis, and acute physiology and chronic health evaluation II score. Mitochondrial DNA improved the c-statistic of acute physiology and chronic health evaluation II score (p < 0.05) and showed enhancement in individual risk prediction indicated by a net reclassification improvement of 32.3% (p < 0.05). Stratification of patients according to toll-like receptor-9 expression above/below median demonstrated that only patients with high expression of toll-like receptor-9 showed an increased risk associated with increased mitochondrial DNA levels (odds ratio, 2.7; p < 0.01), whereas circulating mitochondrial DNA was not associated with mortality in patients with low toll-like receptor-9 expression (odds ratio, 1.1; p = 0.98). CONCLUSIONS: Circulating levels of mitochondrial DNA at ICU admission predict mortality in critically ill patients. This association was in particular present in patients with elevated toll-like receptor-9 expression.

Flow Cytometric Evaluation of Traditional and Novel Surface Markers for the Diagnosis of Plasma Cell Dyscrasias.

Increasing interest has been expressed for flow cytometric immunophenotyping for diagnosis and monitoring in plasma cell dyscrasias over the last decades. The aim of this investigation was to compare the expression strength of various cell surface markers used traditionally or currently under investigation on normal and abnormal PC populations. We enrolled 295 consecutive patients undergoing bone marrow aspiration in the workup of monoclonal gammopathies, selecting 54 normal and 241 abnormal PC populations via flow cytometry to characterize the expression of CD45, CD38, CD138, CD19, CD56, CD20, CD27, CD28, CD81, CD117 and CD200 on the cell surface of PCs. We observed significant differences in the expression strength of all assessed markers between normal and abnormal PC populations in all markers except for CD20. While none of them was conclusive on its own, the combination of CD81 positivity and CD117 negativity was present in 98.1% of normal PC populations tested. In contrast, particularly CD117 positivity, but also CD81 negativity was indicative of an abnormal PC phenotype. Our results highlight the descriptive value of CD81 and CD117 for the allocation of bone marrow PCs to a normal or abnormal phenotype.

Tranexamic acid modulates the immune response and reduces postsurgical infection rates.

Tranexamic acid (TXA) is an antifibrinolytic agent that blocks plasmin formation. Because plasmin is known to promote inflammatory and immunosuppressive responses, we explored the possibility that plasmin-mediated immunosuppression in patients undergoing cardiac surgery can be directly reversed by TXA and decrease postoperative infection rates. The modulatory effect of TXA on inflammatory cytokine levels and on innate immune cell activation were evaluated with multiplex enzyme-linked immunosorbent assay and flow cytometry, respectively. Postoperative infection rates were determined in patients undergoing cardiac surgery and randomized to TXA (ACTRN12605000557639; http://www.anzca.edu.au). We demonstrate that TXA-mediated plasmin blockade modulates the immune system and reduces surgery-induced immunosuppression in patients following cardiac surgery. TXA enhanced the expression of immune-activating markers while reducing the expression of immunosuppressive markers on multiple myeloid and lymphoid cell populations in peripheral blood. TXA administration significantly reduced postoperative infection rates, despite the fact that patients were being administered prophylactic antibiotics. This effect was independent of the effect of TXA at reducing blood loss. TXA was also shown to exert an immune-modulatory effect in healthy volunteers, further supporting the fibrin-independent effect of TXA on immune function and indicating that baseline plasmin levels contribute to the regulation of the immune system in the absence of any comorbidity or surgical trauma. Finally, the capacity of TXA to reduce infection rates, modulate the innate immune cell profile, and generate an antifibrinolytic effect overall was markedly reduced in patients with diabetes, demonstrating for the first time that the diabetic condition renders patients partially refractory to TXA.

Effects of restricting perioperative use of intravenous chloride on kidney injury in patients undergoing cardiac surgery: the LICRA pragmatic controlled clinical trial.

PURPOSE: The administration of chloride-rich intravenous (IV) fluid and hyperchloraemia have been associated with perioperative renal injury. The aim of this study was to determine whether a comprehensive perioperative protocol for the administration of chloride-limited IV fluid would reduce perioperative renal injury in adults undergoing cardiac surgery. METHODS: From February 2014 through to December 2015, all adult patients undergoing cardiac surgery within a single academic medical center received IV fluid according to the study protocol. The perioperative protocol governed all fluid administration from commencement of anesthesia through to discharge from the intensive care unit and varied over four sequential periods, each lasting 5 months. In periods 1 and 4 a chloride-rich strategy, consisting of 0.9% saline and 4% albumin, was adopted; in periods 2 and 3, a chloride-limited strategy, consisting of a buffered salt solution and 20% albumin, was used. Co-primary outcomes were peak delta serum creatinine (∆SCr) within 5 days after the operation and KDIGO-defined stage 2 or stage 3 acute kidney injury (AKI) within 5 days after the operation. RESULTS: We enrolled and analysed data from 1136 patients, with 569 patients assigned to a chloride-rich fluid strategy and 567 to a chloride-limited one. Compared with a chloride-limited strategy and adjusted for prespecified covariates, there was no association between a chloride-rich perioperative fluid strategy and either peak ∆S Cr, transformed to satisfy the assumptions of multivariable linear regression [regression coefficient 0.03, 95% confidence interval (CI) -0.03 to 0.08); p = 0.39], or stage 2 or 3 AKI (adjusted odds ratio 0.97, 95% CI 0.65-1.47; p = 0.90]. CONCLUSIONS: A perioperative fluid strategy to restrict IV chloride administration was not associated with an altered incidence of AKI or other metrics of renal injury in adult patients undergoing cardiac surgery. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT02020538.

Monocyte subset distribution is associated with mortality in critically ill patients.

Although patients admitted to an intensive care unit (ICU) suffer from various pathologies, many develop a systemic inflammatory response syndrome (SIRS). As key regulators of innate immunity, monocytes may be crucially involved in SIRS development. Monocytes can be distinguished into three subsets: Classical monocytes (CD14++CD16-; CM), non-classical monocytes (CD14+CD16++CCR2-; NCM) and intermediate monocytes (CD14++CD16+CCR2+; IM). The aim of this prospective, observational study was to analyse whether monocyte subset distribution is associated with 30-day survival in critically ill patients. A total of 195 consecutive patients admitted to a cardiac ICU at a tertiary-care centre were enrolled, blood was taken at admission and after 72 hours and monocyte subset distribution was analysed. Mean APACHE II score was 19.5 ± 8.1 and 30-day mortality was 25.4 %. At admission, NCM were significantly lower in non-survivors as compared to survivors [2.7 (0.4-5.5) vs 4.2 (1.6-7.5)%; p=0.012] whereas CM and IM did not differ according to 30-day survival. In contrast, 72 hours after admission, monocyte subset distribution shifted towards an increased proportion of IM [8.2 (3.9-13.2) vs 4.2 (2.3-7.9)%; p=0.003] with a concomitant decrease of CM [86.9 (78.6-89.2) vs 89.6 (84.9-93.1)%; p=0.02] in non-survivors vs survivors, respectively. NCM at day 3 were not associated with death at 30 days. These results were independent from age, gender, CRP, APACHE II score and primary diagnosis. In conclusion, circulating monocyte subsets are associated with 30-day mortality in critically ill patients. The innate immune system as reflected by monocyte subset distribution may play a major role in ICU outcome despite varying admittance pathologies.