Deep immune profiling of whole blood to identify early immune signatures that correlate to patient outcome after major trauma.

BACKGROUND: Major injury results in an early cascade of immunologic responses that increase susceptibility to infection and multiorgan dysfunction. Detailed immune profiling by mass cytometry has the potential to identify immune signatures that correspond to patient outcomes. Our objective was to determine the prognostic value of immune signatures early after major trauma injury. METHODS: Trauma patients (n = 17) were prospectively enrolled between September 2018 and December 2019. Serial whole blood samples were obtained from trauma patients (mean Injury Severity Score, 26.2; standard error of the mean, 3.7) at Days 1 and 3 after injury, and from age- and sex-matched uninjured controls using a standardized protocol for fixation, storage, and labeling. Computational analyses including K-nearest neighbor automated clustering of immune cells and Spearman's correlation analysis were used to identify correlations between cell populations, clinical measures, and patient outcomes. RESULTS: Analysis revealed nine immune cell clusters that correlated with one or more clinical outcomes. On Days 1 and 3 postinjury, the abundance of immature neutrophil and classical monocytes exhibited a strong positive correlation with increased intensive care unit and hospital length of stay. Conversely, the abundance of CD4 T-cell subsets, namely Th17 cells, is associated with improved patient outcomes including decreased ventilator days (r = -0.76), hospital-acquired pneumonia (r = -0.69), and acute kidney injury (r = -0.73). CONCLUSION: Here, we provide a comprehensive multitime point immunophenotyping analysis of whole blood from patients soon after traumatic injury to determine immune correlates of adverse outcomes. Our findings indicate that alterations in myeloid-origin cell types may contribute to immune dysfunction after injury. Conversely, the presence of effector T cell populations corresponds with decreased hospital length of stay and organ dysfunction. Overall, these data identify novel immune signatures following traumatic injury that support the view that monitoring of immune (sub)-populations may provide clinical decision-making support for at-risk patients early in their hospital course. LEVEL OF EVIDENCE: Prognostic/Epidemiologic, Level IV.

Procalcitonin and C-reactive protein perform better than the neutrophil/lymphocyte count ratio in evaluating hospital acquired pneumonia.

BACKGROUND: The relationship between biomarkers and hospital-acquired pneumonia (HAP) is understudied, especially in severe cases admitted to the intensive care unit (ICU). Compared with community-acquired pneumonia (CAP), HAP might have different traits regarding biomarkers due to the previous history in hospitals. METHODS: A total of 593 adult patients were enrolled in this retrospective cohort study to determine the neutrophil/lymphocyte count ratio (NLCR), procalcitonin (PCT), C-reactive protein (CRP) and serum lactate level upon admission to the ICU. According to diagnosis, patients were divided into two groups: non-infection and HAP. Discriminant analysis was performed based on better outcomes of diagnostic performance and severity evaluation. The diagnostic performance of each individual biomarker was assessed by constructing receiver operating characteristic (ROC) curves and calculating the area under each ROC curve (AUROC). Multivariable analysis was also applied to determine the most appropriate prognostic factors. RESULTS: NLCR, PCT and CRP were markedly different between the non-infection and HAP groups. NLCR had a worse ability to discriminate severe infection (AUROC 0.626; 95% CI 0.581-0.671) than conventional markers such as CRP (0.685, 95% CI 0.641-0.730) and PCT (0.661, 95% CI 0.615-0.707). In addition, the AUROC of composite biomarkers, especially the combination of NLCR, CRP and WBC, was significantly greater than that of any single biomarker. CONCLUSIONS: NLCR was not comparable to conventional single biomarkers, such as CRP and PCT, for diagnosing or evaluating the severity of HAP. Composite biomarkers that have good accessibility, especially the combination of NLCR, CRP and WBC, could help with early diagnosis and severity evaluation.

Elevated Systemic IL-10 Levels Indicate Immunodepression Leading to Nosocomial Infections after Aneurysmal Subarachnoid Hemorrhage (SAH) in Patients.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (SAH) is a highly complex disease with very high mortality and morbidity. About one-third of SAH patients suffer from systemic infections, predominantly pneumonia, that can contribute to excess mortality after SAH. Immunodepression is probably the most important mechanism leading to infections. Interleukin-10 (IL-10) is a master regulator of immunodepression, but it is still not clear if systemic IL-10 levels contribute to immunodepression, occurrence of infections and clinical outcome after SAH. METHODS: This explorative study included 76 patients with SAH admitted to our neurointensive care unit within 24 h after ictus. A group of 24 patients without any known intracranial pathology were included as controls. Peripheral venous blood was withdrawn on day 1 and day 7 after SAH. Serum was isolated by centrifugation and stored at -80 °C until analysis. Serum IL-10 levels were determined by enzyme-linked immunoassay (ELISA). Patient characteristics, post-SAH complications and clinical outcome at discharge were retrieved from patients' record files. RESULTS: Serum IL-10 levels were significantly higher on day 1 and day 7 in SAH patients compared to controls. Serum IL-10 levels were significantly higher on day 7 in patients who developed any kind of infection, cerebral vasospasm (CVS) or chronic hydrocephalus. Serum IL-10 levels were significantly higher in SAH patients discharged with poor clinical outcome (modified Rankin Scale (mRS) 3-6 or Glasgow Outcome Scale (GOS) 1-3). CONCLUSION: Serum IL-10 might be an additional useful parameter along with other biomarkers to predict post-SAH infections.

The association between serum magnesium levels and community-acquired pneumonia 30-day mortality.

BACKGROUND: Community acquired pneumonia (CAP) is a common illness affecting hundreds of millions worldwide. Few studies have investigated the relationship between serum magnesium levels and outcomes of these patients. We aimed to study the association between serum magnesium levels and 30-day mortality among patients with CAP. METHODS: Retrospective overview of patients hospitalized with CAP between January 1, 2010 and December 31, 2016. Participants were analyzed retrospectively in order to identify the risk factors for a primary endpoint of 30-day mortality. Normal levels of magnesium levels in our laboratory varies between 1.35 and 2.4 mg/dl. RESULTS: 3851 patients were included in our cohort. Age > 75 years, blood urea nitrogen (BUN) > 20 mg/dl, hypoalbuminemia, and abnormal levels of magnesium were all associated with increased risk of 30-day mortality. Normal magnesium levels were associated with the lowest mortality rate (14.7%). Notably, within the normal levels, high normal magnesium levels (2-2.4 mg/dl) were correlated with higher mortality rates (30.3%) as compared to levels that ranged between 1.35-2 mg/dl (12.9%). Hypomagnesemia and hypermagnesemia were both associated with excess of 30-day mortality, 18.4 and 50%, respectively. CONCLUSION: Hypomagnesemia and hypermagnesemia on admission were associated with an increased rate of 30-day mortality among adult patients hospitalized with CAP. Interestingly, magnesium levels within the upper normal limits were associated with higher mortality.

Do we need biomarkers for the follow-up and shortening of antibiotic treatment duration?

PURPOSE OF REVIEW: Clinical and laboratory parameters are useful tools for the diagnosis, follow-up and evaluation of resolution, and to predict outcomes when measured at different time-points onset and serially during follow-up in patients with hospital-acquired pneumonia and/or ventilator-associated pneumonia (HAP/VAP). RECENT FINDINGS: Both, the 2017 ERS/ESICM/ESCMID/Asociación Latino Americana de Tórax (EEEAG) and the 2016 IDSA/ATS guidelines (IAG) for the management of HAP/VAP recommend using clinical criteria alone, rather than biomarkers for diagnosis. Several studies were conducted to assess the value of serum biomarker concentration and kinetics for predicting the outcome in HAP/VAP, including C-reactive protein and procalcitonin (PCT). Although the EEEAG do not recommend routinely performing biomarker determinations in addition to bedside clinical assessment in patients receiving antibiotic treatment for VAP or HAP to predict adverse outcomes and clinical response, the IAG recommend that routine bedside clinical assessment should be accompanied by measurements of PCT to guide antimicrobial therapy. Additionally, the 2016 Surviving Sepsis Campaign also suggests that PCT levels can be used to support the shortening of antibiotic therapy. SUMMARY: Current evidence indicate that there is no recommendation to use biomarkers systematically to guide every decision. However, in some circumstances they might add some relevant information to our everyday practice.