Endothelin-1 precursor peptides correlate with severity of disease and outcome in patients with community acquired pneumonia

A literature review of severity scores for adults with influenza or community-acquired pneumonia - implications for influenza vaccines and therapeutics

Influenza vaccination and antiviral therapeutics may attenuate disease, decreasing severity of illness in vaccinated and treated persons. Standardized assessment tools, definitions of disease severity, and clinical endpoints would support characterizing the attenuating effects of influenza vaccines and antivirals. We review potential clinical parameters and endpoints that may be useful for ordinal scales evaluating attenuating effects of influenza vaccines and antivirals in hospital-based studies. In studies of influenza and community-acquired pneumonia, common physiologic parameters that predicted outcomes such as mortality, ICU admission, complications, and duration of stay included vital signs (hypotension, tachypnea, fever, hypoxia), laboratory results (blood urea nitrogen, platelets, serum sodium), and radiographic findings of infiltrates or effusions. Ordinal scales based on these parameters may be useful endpoints for evaluating attenuating effects of influenza vaccines and therapeutics. Factors such as clinical and policy relevance, reproducibility, and specificity of measurements should be considered when creating a standardized ordinal scale for assessment.

Endothelium-associated biomarkers mid-regional proadrenomedullin and C-terminal proendothelin-1 have good ability to predict 28-day mortality in critically ill patients with SARS-CoV-2 pneumonia: A prospective cohort study

PURPOSE

We assessed the ability of mid-regional proadrenomedullin (MR-proADM) and C-terminal proendothelin-1 (CT-proET-1) to predict 28-day mortality in critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia.

METHODS

Biomarkers were collected during the first seven days in this prospective observational cohort study. We investigated the relationship between biomarkers and mortality in a multivariable Cox regression model adjusted for age and SOFA score.

RESULTS

In 105 critically ill patients with confirmed SARS-CoV-2 pneumonia 28-day mortality was 28.6%. MR-proADM and CT-proET-1 were significantly higher in 28-day non-survivors at baseline and over time. ROC curves revealed high accuracy to identify non-survivors for baseline MR-proADM and CT-proET-1, AUC 0.84, (95% CI 0.76-0.92), p < 0.001 and 0.79, (95% CI 0.69-0.89), p < 0.001, respectively. The AUC for prediction of 28-day mortality for MR-proADM and CT-proET-1 remained high over time. MR-proADM ≥1.57 nmol/L and CT-proET-1 ≥ 111 pmol/L at baseline were significant predictors for 28-day mortality (HR 6.80, 95% CI 3.12-14.84, p < 0.001 and HR 3.72, 95% CI 1.71-8.08, p 0.01).

CONCLUSION

Baseline and serial MR-proADM and CT-proET-1 had good ability to predict 28-day mortality in critically ill patients with SARS-CoV-2 pneumonia.

TRIAL REGISTRATION

NEDERLANDS TRIAL REGISTER, NL8460.

Association of endothelial activation assessed through endothelin-I precursor peptide measurement with mortality in COVID-19 patients: an observational analysis

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) has been linked to thrombotic complications and endothelial dysfunction. We assessed the prognostic implications of endothelial activation through measurement of endothelin-I precursor peptide (proET-1), the stable precursor protein of Endothelin-1, in a well-defined cohort of patients hospitalized with COVID-19.

METHODS

We measured proET-1 in 74 consecutively admitted adult patients with confirmed COVID-19 and compared its prognostic accuracy to that of patients with community-acquired pneumonia (n = 876) and viral bronchitis (n = 371) from a previous study by means of logistic regression analysis. The primary endpoint was all-cause 30-day mortality.

RESULTS

Overall, median admission proET-1 levels were lower in COVID-19 patients compared to those with pneumonia and exacerbated bronchitis, respectively (57.0 pmol/l vs. 113.0 pmol/l vs. 96.0 pmol/l, p < 0.01). Although COVID-19 non-survivors had 1.5-fold higher admission proET-1 levels compared to survivors (81.8 pmol/l [IQR: 76 to 118] vs. 53.6 [IQR: 37 to 69]), no significant association of proET-1 levels and mortality was found in a regression model adjusted for age, gender, creatinine level, diastolic blood pressure as well as cancer and coronary artery disease (adjusted OR 0.1, 95% CI 0.0009 to 14.7). In patients with pneumonia (adjusted OR 25.4, 95% CI 5.1 to 127.4) and exacerbated bronchitis (adjusted OR 120.1, 95% CI 1.9 to 7499) we found significant associations of proET-1 and mortality.

CONCLUSIONS

Compared to other types of pulmonary infection, COVID-19 shows only a mild activation of the endothelium as assessed through measurement of proET-1. Therefore, the high mortality associated with COVID-19 may not be attributed to endothelial dysfunction by the surrogate marker proET-1.

Adhesion molecules as diagnostic and severity biomarkers in pediatric community-acquired pneumonia

BACKGROUND

Discrimination of the cases with severe and mild pneumonia is crucial due to the requirement of hospitalization, additional management, and treatment protocols. We aimed to analyze the role of IL6 (Interleukin), IL8, IL10, VCAM-1 (soluble Vascular Cell Adhesion Molecule), and sSELE (soluble E-selectin) in the diagnosis and prognostic evaluation of community-acquired pneumonia (CAP).

METHODS

Pediatric patients with severe pneumonia (SP) were hospitalized and patients with mild disease (MP) were treated in the community. IL6, IL8, IL10, VCAM-1, and sSELE levels of the patients were investigated and compared with the age- and gender-matched healthy subjects.

RESULTS

A total of 113 patients fulfilling the criteria for a diagnosis of CAP were enrolled in the study, 62 (54.8%) of which had SP and 51 (45%) had MP. MP and SP groups were significantly different in terms of IL8, IL10, and sSELE levels. Patients with SP and MP had significantly different WBC, ESR, and CRP values, as well.

CONCLUSIONS

Besides classical acute phase parameters, inflammatory response parameters such as IL6 and VCAM-1 levels may be helpful in diagnosis of pneumonia. In terms of determination of disease severity in pediatric CAP, systemic inflammatory markers like IL8 and IL10 and adhesion molecules like sSELE seem useful in clinical settings.

Biomarkers in Community-Acquired Pneumonia (Cardiac and Non-Cardiac)

Community-acquired pneumonia (CAP) remains the first cause of morbidity and mortality worldwide due to infection. Several aspects such as severity and host response are related to its clinical course and outcome. Beyond the acute implications that the infection provokes in the host, pneumonia also has long-term negative consequences. Among them, cardiovascular complications and mortality are the most outstanding. Therefore, an adequate recognition and stratification of the risk of complications and mortality is crucial. Many biomarkers have been studied for these reasons, considering that each biomarker mirrors a different aspect. Moreover, the clinical application of many of them is still being deliberated because of their limitations and the heterogeneity of the disease. In this review, we examine some of the most relevant biomarkers that we have classified as cardiac and non-cardiac. We discuss some classic biomarkers and others that are considered novel biomarkers, which are mainly involved in cardiovascular risk.

Association of endothelin genetic variants and hospitalized infection complications in end-stage renal disease (ESRD) patients

BACKGROUND

Infection is the second most common cause of mortality for patients with end-stage renal disease (ESRD), accompanying with immune dysfunction. Endothelin (EDN) is known to be related to inflammation; however, it is unknown whether genetic variants of the EDN gene family are associated with increased risk of hospitalized infection events.

METHODS

Nineteen tagging single-nucleotide polymorphisms (tSNPs) of the EDN gene family were selected for genotyping a cohort of 190 ESRD patients. Patient demographics were recorded, the subtypes of infection events were identified, and association analysis between the EDN genetic variants and hospitalized infection events was performed.

RESULTS

In this study, 106 patients were hospitalized for infection events. The leading events were pneumonia, bacteremia, and cellulitis. The minor allele of rs260741, rs197173, and rs926632 SNPs of EDN3 were found to be associated with reduced risk of hospitalized bacteremia events.

CONCLUSIONS

The minor allele of rs260741, rs197173, and rs926632 in EDN3 were associated with reduced risk of hospitalized bacteremia events in ESRD patients.

Measurement of plasma endothelin-1 concentration in healthy horses and horses with cardiac disease during rest and after exercise

Cardiac biomarkers are important tools for monitoring disease progress and can monitor progression of therapy. Endothelin-1 (ET-1) has been studied for its use as a cardiac biomarker in human and small animal medicine while in horses with cardiac disease it has not been evaluated yet. The objective of the present study was to determine the concentration of plasma ET-1 in healthy horses and compare it with ET-1 concentration in horses with cardiac disease during rest and after exercise. Fifty four horses admitted to the Equine Clinic of Free University of Berlin were used in the present study, of which 15 horses were clinically healthy with no evidence of cardiac disease (Group 1), 22 horses suffered from cardiac disease with normal heart dimensions (Group 2) and 17 horses with cardiac disease and enlarged heart diameters (Group 3). Clinical examination, electrocardiography and echocardiography were performed. Endothelin-1 concentration was determined using ET-1 ELISA kit. The concentration of plasma ET-1 was significantly increased in horses with cardiac disease and normal cardiac dimensions (Group 2) and in horses with cardiac disease and enlargement of the left atrium (Group 3) compared to its concentration in clinically healthy horses (Group 1). In addition, the concentration of plasma ET-1 after exercise was significantly increased in diseased horses compared to its concentration at rest. Detection of ET-1 plasma concentration in horses at rest may be useful for detecting horses with changes in left atrial cardiac dimensions.

Endothelins in inflammatory neurological diseases

Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.

Correlation between plasma endothelin-1 levels and severity of septic liver failure quantified by maximal liver function capacity (LiMAx test). A prospective study

Aim

To investigate the relationship between the degree of liver dysfunction, quantified by maximal liver function capacity (LiMAx test) and endothelin-1, TNF-α and IL-6 in septic surgical patients.

Methods

28 septic patients (8 female, 20 male, age range 35–80y) were prospectively investigated on a surgical intensive care unit. Liver function, defined by LiMAx test, and measurements of plasma levels of endothelin-1, TNF-α and IL-6 were carried out within the first 24 hours after onset of septic symptoms, followed by day 2, 5 and 10. Patients were divided into 2 groups (group A: LiMAx ≥100 μg/kg/h, moderate liver dysfunction; group B: LiMAx <100 μg/kg/h, severe liver dysfunction) for analysis and investigated regarding the correlation between endothelin-1 and the severity of liver failure, quantified by LiMAx test.

Results

Group B showed significant higher results for endothelin-1 than patients in group A (P = 0.01, d5; 0.02, d10). For TNF-α, group B revealed higher results than group A, with a significant difference on day 10 (P = 0.005). IL-6 showed a non-significant trend to higher results in group B. The Spearman's rank correlation coefficient revealed a significant correlation between LiMAx and endothelin-1 (-0.434; P <0.001), TNF-α (-0.515; P <0.001) and IL-6 (-0.590; P <0.001).

Conclusions

Sepsis-related hepatic dysfunction is associated with elevated plasma levels of endothelin-1, TNF-α and IL-6. Low LiMAx results combined with increased endothelin-1 and TNF-α and a favourable correlation between LiMAx and cytokine values support the findings of a crucial role of Endothelin-1 and TNF-α in development of septic liver failure.

Usefulness and prognostic value of biomarkers in patients with community-acquired pneumonia in the emergency department

Between all patients treated in the Emergency Department (ED), 1.35% are diagnosed with community-acquired pneumonia (CAP). CAP is the main cause of death due to infectious disease (10-14%) and the most frequent reason of sepsis-septic shock in the ED. In the last decade, the search for objective tools to help establishing an early diagnosis, bacterial aetiology, severity, suspicion of bacteremia and the prognosis of mortality has increased. Biomarkers have shown their usefulness in this matter. Procalcitonin (obtains the highest accuracy for CAP diagnosis, bacterial aetiology and the presence of bacteremia), lactate (biomarker of hypoxia and tissue hypoperfusion) and proadrenomedullin (which has the greatest accuracy to predict mortality which in combination with the prognostic severity scales obtains even better results). The aim of this review is to highlight recently published scientific evidence and to compare the utility and prognostic accuracy of the biomarkers in CAP patients treated in the ED.

The endothelin system has a significant role in the pathogenesis and progression of Mycobacterium tuberculosis infection

Tuberculosis (TB) remains a major global health problem, and although multiple studies have addressed the relationship between Mycobacterium tuberculosis and the host on an immunological level, few studies have addressed the impact of host physiological responses. Proteases produced by bacteria have been associated with important alterations in the host tissues, and a limited number of these enzymes have been characterized in mycobacterial species. M. tuberculosis produces a protease called Zmp1, which appears to be associated with virulence and has a putative action as an endothelin-converting enzyme. Endothelins are a family of vasoactive peptides, of which 3 distinct isoforms exist, and endothelin 1 (ET-1) is the most abundant and the best-characterized isoform. The aim of this work was to characterize the Zmp1 protease and evaluate its role in pathogenicity. Here, we have shown that M. tuberculosis produces and secretes an enzyme with ET-1 cleavage activity. These data demonstrate a possible role of Zmp1 for mycobacterium-host interactions and highlights its potential as a drug target. Moreover, the results suggest that endothelin pathways have a role in the pathogenesis of M. tuberculosis infections, and ETA or ETB receptor signaling can modulate the host response to the infection. We hypothesize that a balance between Zmp1 control of ET-1 levels and ETA/ETB signaling can allow M. tuberculosis adaptation and survival in the lung tissues.

Can we predict pneumococcal bacteremia in patients with severe community-acquired pneumonia?

PURPOSE

This study aimed to evaluate the role of biomarkers as markers of pneumococcal bacteremia in severe community-acquired pneumonia (SCAP).

MATERIALS AND METHODS

A prospective, single-center, observational cohort study of 108 patients with SCAP admitted to the intensive care department of a university hospital in Portugal was conducted. Leucocytes, C-reactive protein (CRP), lactate, procalcitonin (PCT), d-dimer, brain natriuretic peptide (BNP), and cortisol were measured within 12 hours after the first antibiotic dose.

RESULTS

Fifteen patients (14%) had bacteremic pneumococcal pneumonia (BPP). They had significantly higher levels of median CRP (301 [interquartile range, or IQR], 230-350] mg/L vs 201 [IQR, 103-299] mg/L; P = .023), PCT (40 [IQR, 25-102] ng/mL vs 8 [IQR, 2-26] ng/mL; P < .001), BNP (568 [IQR, 478-2841] pg/mL vs 407 [IQR, 175-989] pg/mL; P = .027), and lactate (5.5 [IQR, 4.5-9.8] mmol/L vs 3.1 [IQR, 1.9-6.2] mmol/L; P = .009) than did patients without BPP. The discriminatory power evaluated by the area under the receiver operating characteristic curve (aROC) for PCT (aROC, 0.79) was superior to lactate (aROC, 0.71), BNP (aROC, 0.67), and CRP (aROC, 0.70). At a cutoff point of 17 ng/mL, PCT showed a sensitivity of 87%, a specificity of 67%, a positive predictive value of 30% and a negative predictive value of 97%, as a marker of pneumococcal bacteremia.

CONCLUSIONS

In this cohort, significantly higher PCT, BNP, lactate, and CRP levels were found in BPP, and PCT presented the best ability to identify pneumococcal bacteremia. A PCT serum level lower than 17 ng/mL could identify patients with SCAP unlikely to have pneumococcal bacteremia.

Endothelin-1 and its role in the pathogenesis of infectious diseases

Endothelins are potent regulators of vascular tone, which also have mitogenic, apoptotic, and immunomodulatory properties (Rubanyi and Polokoff, 1994; Kedzierski and Yanagisawa, 2001; Bagnato et al., 2011). Three isoforms of endothelin have been identified to date, with endothelin-1 (ET-1) being the best studied. ET-1 is classically considered a potent vasoconstrictor. However, in addition to the effects of ET-1 on vascular smooth muscle cells, the peptide is increasingly recognized as a pro-inflammatory cytokine (Teder and Noble, 2000; Sessa et al., 1991). ET-1 causes platelet aggregation and plays a role in the increased expression of leukocyte adhesion molecules, the synthesis of inflammatory mediators contributing to vascular dysfunction. High levels of ET-1 are found in alveolar macrophages, leukocytes (Sessa et al., 1991) and fibroblasts (Gu et al., 1991). Clinical and experimental data indicate that ET-1 is involved in the pathogenesis of sepsis (Tschaikowsky et al., 2000; Goto et al., 2012), viral and bacterial pneumonia (Schuetz et al., 2008; Samransamruajkit et al., 2002), Rickettsia conorii infections (Davi et al., 1995), Chagas disease (Petkova et al., 2000, 2001), and severe malaria (Dai et al., 2012; Machado et al., 2006; Wenisch et al., 1996a; Dietmann et al., 2008). In this minireview, we will discuss the role of endothelin in the pathogenesis of infectious processes.

Evaluation of the serum levels of soluble IL-2 receptor and endothelin-1 in children with Crimean-Congo hemorrhagic fever

We aimed to assess the association between serum levels of soluble IL-2 receptor (sIL-2r) and endothelin-1 and severe infection in children with Crimean-Congo hemorrhagic fever (CCHF). Fifty-two patients under 18 years of age with a laboratory- confirmed diagnosis of CCHF and 38 healthy controls were enrolled in the study. Patients were classified into two groups based on disease severity (severe group and non-severe group). The sIL-2r and endothelin-1 levels were observed to be significantly higher in patients with severe CCHF compared with those with non-severe CCHF and the control group (p < 0.05). In addition, those with non-severe CCHF were also found to have a significantly higher sIL-2r level relative to the control group (p < 0.001). Although there was a positive correlation between sIL-2r and endothelin-1 levels, serum levels of both sIL-2r and endothelin-1 were negatively correlated with the platelets count. In children with CCHF, serum levels of sIL-2r and endothelin-1 were increased, and this increase is related to the severity of the disease. In this study, we concluded through prognosis that serum levels of sIL-2r and endothelin-1 might be related, and that hemophagocytic lymphohistiocytosis and endothelial injury might contribute to a pathogenesis of the disease.

Lack of value of midregional pro-adrenomedullin and C-terminal pro-endothelin-1 for prediction of severe bacterial infections in infants with fever without a source

The study was performed to assess the usefulness of two new biomarkers, midregional pro-adrenomedullin (MR-pro-ADM) and C-pro-endothelin-1 (CT-pro-ET-1), in predicting bacterial infection (BI) and especially invasive bacterial infection (IBI) in well-appearing infants with fever without source (FWS). For this purpose, a multicenter prospective study was conducted between February 2008 and March 2009 including well-appearing infants less than 36 months of age with FWS. MR-pro-ADM, CT-pro-ET-1, procalcitonin (PCT), CRP, and WBC were measured and compared. Among the 1,035 infants included, a bacterial infection was diagnosed in 75 patients (7.2 %), and 16 (1.54 %) had an invasive bacterial infection (bacterial meningitis, 8; occult bacteremia, 6; and sepsis, 1). MR-pro-ADM and CT-pro-ET-1 levels were less reliable for diagnosis than the other biomarkers. The area under receiver operating characteristic curve for infants with BI and IBI was 0.59 (95 % confidence interval (CI) 0.52-0.67) and 0.63 (95 % CI 0.46-0.80) for MR-pro-ADM and 0.58 (95 % CI 0.51-0.66) and 0.62 (95 % CI 0.47-0.67) for CT-pro-ET-1, respectively. Multivariate analysis showed that PCT ≥ 0.5 ng/mL, CRP ≥ 40 mg/L, and CT-pro-ET-1 ≥ 105 pmol/mL were independent risk factors for having a BI (odds ratio (OR) 6.12, 3.61, and 2.84, respectively). PCT was the only independent risk factor for having an IBI (OR 17.53 if PCT ≥ 0.5 ng/mL).

CONCLUSION

Although baseline MR-pro-ADM and CT-pro-ET-1 levels are significantly elevated in well-appearing febrile infants with a bacterial infection, their overall performance as diagnostic markers is very poor.

Endothelium and Regulatory Inflammatory Mechanisms During Organ Rejection

Endothelial integrity is mandatory for physiologic organ function; however, endothelium dysfunction can be caused by systemic inflammation, occurring during sepsis or organ rejection after transplantation. This article will address our current understanding of endothelial involvement in organ transplantation and rejection. Overall, more detailed studies focusing on the endothelial modulation after organ transplantation would be necessary to investigate the role of endothelium activation during organ rejection.

Biomarker-enhanced triage in respiratory infections: a proof-of-concept feasibility trial

Concerns about inadequate performance and complexity limit routine use of clinical risk scores in lower respiratory tract infections. Our aim was to study feasibility and effects of adding the biomarker proadrenomedullin (proADM) to the confusion, urea >7 mmol·L⁻¹, respiratory rate ≥30 breaths·min⁻¹, blood pressure <90 mmHg (systolic) or ≤60 mmHg (diastolic), age ≥65 years (CURB-65) score on triage decisions and length of stay.

In a randomised controlled proof-of-concept intervention trial, triage and discharge decisions were made for adults with lower respiratory tract infection according to interprofessional assessment using medical and nursing risk scores either without (control group) or with (proADM group) knowledge of proADM values, measured on admission, and on days 3 and 6. An adjusted generalised linear model was calculated to investigate the effect of our intervention.

On initial presentation the algorithms were overruled in 123 (39.3%) of the cases. Mean length of stay tended to be shorter in the proADM (n=154, 6.3 days) compared with the control group (n=159, 6.8 days; adjusted regression coefficient -0.19, 95% CI -0.41–0.04; p=0.1). This trend was robust in subgroup analyses and for overall length of stay within 90 days (7.2 versus 7.9 days; adjusted regression coefficient -0.18, 95% CI -0.40–0.05; p=0.13). There were no differences in adverse outcomes or readmission.

Logistic obstacles and overruling are major challenges to implement biomarker-enhanced algorithms in clinical settings and need to be addressed to shorten length of stay.

Proof-of-concept trial: how to shorten LOS in patients with LRTIs by reducing medically unnecessary days in the hospitalhttp://ow.ly/nI7z4

Biomarkers of endothelial dysfunction: can they help us deciphering systemic inflammation and sepsis?

The endothelial integrity, as mechanical barrier against microorganisms and as natural "anticoagulant", is crucial for physiologic organ function. Systemic activation of the endothelium upon inflammation, sepsis, and septic shock is always ending in blood-tissue barrier disruption. With increasing dysfunction, uncontrolled clotting activation, capillary microthrombi formation, tissue edema, local hypoxia, and ischemia are initiated. This in turn enhances a vicious circle leading to multiple organ failure and death. Therefore, biomarkers reflecting this special compartment may help in the early detection of systemic inflammation and its complications. This review provides an overview of the most important endothelial biomarkers and their possible use in sepsis.

Aspiration-induced lung injury

OBJECTIVE

Aspiration of oropharyngeal or gastric contents into the lower respiratory tract is a common event in critically ill patients and can lead to pneumonia or pneumonitis. Aspiration pneumonia is the leading cause of pneumonia in the intensive care unit and is one of the leading risk factors for acute lung injury and acute respiratory distress syndromes. Despite its frequency, it remains largely a disease of exclusion characterized by ill-defined infiltrates on the chest radiograph and hypoxia. An accurate ability to diagnose aspiration is paramount because different modalities of therapy, if applied early and selectively, could change the course of the disease. This article reviews definitions, diagnosis, epidemiology, pathophysiology, including animal models of aspiration-induced lung injury, and evidence-based clinical management. Additionally, a review of current and potential biomarkers that have been tested clinically in humans is provided.

DATA SOURCES

Data were obtained from a PubMed search of the medical literature. PubMed "related articles" search strategies were used.

SUMMARY AND CONCLUSIONS

Aspiration in the intensive care unit is a clinically relevant problem requiring expertise and awareness. A definitive diagnosis of aspiration pneumonitis or pneumonia is challenging to make. Advances in specific biomarker profiles and prediction models may enhance the diagnosis and prognosis of clinical aspiration syndromes. Evidence-based management is supportive, including mechanical ventilation, bronchoscopy for particulate aspiration, consideration of empiric antibiotics for pneumonia treatment, and lower respiratory tract sampling to define pathogenic bacteria that are causative.

Triggering receptor (TREM-1) expressed on myeloid cells predicts bacteremia better than clinical variables in community-acquired pneumonia

BACKGROUND AND OBJECTIVE

Some clinical variables are associated with bacteremia in patients with community-acquired pneumonia (CAP). The aim of this study was to analyse the accuracy of the soluble form of triggering receptor expressed on myeloid cells-1 (sTREM-1) to predict positive blood cultures in comparison with established clinical prognostic variables.

METHODS

In addition to collecting clinical and laboratory information, a commercially available immunoassay kit was used to measure the serum sTREM-1 levels on the first day of admit ion in patients with CAP. Receiver operating characteristic (ROC) curves were used to compare the ability of sTREM-1 and commonly used clinical variables to identify bacteremia.

RESULTS

Blood cultures yielded a pathogen in 13 (10.4%) out of 124 patient samples. The microorganisms isolated were Streptococcus pneumoniae (11 patients) and Klebsiella pneumoniae (2 patients). The presence of pleuritic chest pain, tachycardia and extreme white cell count (WCC) were associated with bacteremia. However, ROC curve analysis showed an accuracy of sTREM-1 (area under the receiver operating characteristic curve (AUC) 0.84, 95% CI: 0.72-0.95), which was higher than pleuritic chest pain (AUC 0.71, 95% CI: 0.57-0.84), tachycardia (AUC 0.73, 95% CI: 0.58-0.88) and extreme WCC (AUC 0.70, 95% CI: 0.55-0.85) for predicting positive blood cultures. Low admission sTREM-1 serum values had a high negative predictive value for excluding bacteremia (sTREM-1 <120 pg/mL = 98.8%).

CONCLUSIONS

This preliminary study suggests that the determination of sTREM-1 serum levels on admission may be more accurate than clinical variables for identifying bacteremic patients.

Biomarkers in the management of pneumonia

A novel approach to improve diagnosis and prognosis of pneumonia is the use of biomarkers. An ideal diagnostic biomarker for pneumonia should allow an early diagnosis and differential diagnosis from other, noninfectious conditions. Procalcitonin (PCT) has emerged as a reliable diagnostic marker in pneumonia, and is better when compared with other markers, namely C-reactive protein, leukocyte count and proinflammatory cytokines. A PCT-based diagnostic and therapeutic strategy can reduce antibiotic usage in patients with pneumonia, mainly by reducing the duration of antibiotic courses. However, PCT should not be used as a substitute for a careful clinical assessment. PCT levels may remain low in localized infections in the context of pneumonia, especially in patients with localized empyema. An ideal prognostic biomarker should be informative about the course and outcome of a disease. Various biomarkers, namely pro-adrenomedullin, natriuretic peptides, endothelin-1 precursor peptides, as well as copeptin and cortisol levels, are promising in this respect. Future studies will show whether an assessment with those novel biomarkers is able to guide prognostic decision-making and improve the allocation of healthcare resources and hospitalization costs.

Prohormones for prediction of adverse medical outcome in community-acquired pneumonia and lower respiratory tract infections

INTRODUCTION

Measurement of prohormones representing different pathophysiological pathways could enhance risk stratification in patients with community-acquired pneumonia (CAP) and other lower respiratory tract infections (LRTI).

METHODS

We assessed clinical parameters and five biomarkers, the precursor levels of adrenomedullin (ADM), endothelin-1 (ET1), atrial-natriuretic peptide (ANP), anti-diuretic hormone (copeptin), and procalcitonin in patients with LRTI and CAP enrolled in the multicenter ProHOSP study. We compared the prognostic accuracy of these biomarkers with the pneumonia severity index (PSI) and CURB65 (Confusion, Urea, Respiratory rate, Blood pressure, Age 65) score to predict serious complications defined as death, ICU admission and disease-specific complications using receiver operating curves (ROC) and reclassification methods.

RESULTS

During the 30 days of follow-up, 134 serious complications occurred in 925 (14.5%) patients with CAP. Both PSI and CURB65 overestimated the observed mortality (X2 goodness of fit test: P = 0.003 and 0.01). ProADM or proET1 alone had stronger discriminatory powers than the PSI or CURB65 score or any of either score components to predict serious complications. Adding proADM alone (or all five biomarkers jointly) to the PSI and CURB65 scores, significantly increased the area under the curve (AUC) for PSI from 0.69 to 0.75, and for CURB65 from 0.66 to 0.73 (P < 0.001, for both scores). Reclassification methods also established highly significant improvement (P < 0.001) for models with biomarkers if clinical covariates were more flexibly adjusted for. The developed prediction models with biomarkers extrapolated well if evaluated in 434 patients with non-CAP LRTIs.

CONCLUSIONS

Five biomarkers from distinct biologic pathways were strong and specific predictors for short-term adverse outcome and improved clinical risk scores in CAP and non-pneumonic LRTI. Intervention studies are warranted to show whether an improved risk prognostication with biomarkers translates into a better clinical management and superior allocation of health care resources.

TRIAL REGISTRATION

NCT00350987.

Community acquired bacterial pneumonia

IMPORTANCE OF THE FIELD

Community-acquired pneumonia (CAP) is a common and potentially life-threatening illness that continues to be a major medical problem. Among infectious diseases, CAP is the leading cause of death in the world and is associated with a substantial economic burden to health are systems around the globe.

AREAS COVERED IN THIS REVIEW

Recently identified clinical and biochemical tools promise to improve the assessment of CAP severity. Various prognostic scoring systems and predictive biomarkers have been proposed as tools to aid clinicians in key management decisions. This review provides a summary of current evidence about the use of prognostic scoring systems and biomarkers in the management of patients presenting with CAP. According to the existing guidelines, until more accurate and rapid diagnostic methods are available, the initial treatment for most patients with CAP will remain empirical. Some novel antibiotic and nonantibiotic therapies have recently been tested; some empirical antimicrobial regimens are still being debated. This review summarizes the recent advances in the field of therapy and novel approaches. We searched PubMed for English-language references published from 1997 to 2009 using combinations of the following terms: 'community acquired pneumonia', 'community acquired bacterial pneumonia', 'therapy', 'antibiotics', 'antimicrobials', 'prognostic scoring systems', 'biomarkers', 'diagnostic testing', 'guidelines' 'etiological diagnosis'.

WHAT THE READER WILL GAIN

A thorough description about recent advances in the field of therapy and novel approaches of CAP, as well as a summary of current evidence about the use of prognostic scoring systems and biomarkers in the management of patients presenting with CAP, is presented.

TAKE HOME MESSAGE

Recent developments have made significant contributions to the management of CAP patients. However, various hot topics remain open and urgently require prospective studies in order to optimize the outcomes of CAP.

Biomarkers in the diagnosis of aspiration syndromes

Recognizing and managing the different types of aspiration events remain a challenging task due to the lack of distinguishing clinical or laboratory characteristics. Numerous biomarkers in serum, sputum and bronchoalveolar lavage have been studied, and their role in the recognition of aspiration remains controversial at this time. Recent animal investigations using an array of biomarkers based on distinct pathogenic features of each aspiration event have produced promising results; however, they have not been validated in humans. Newer markers are being introduced as diagnostic and prognostic tools in conditions such as community-acquired pneumonia and sepsis, but they have not been examined in aspiration. The present review summarizes the different biomarkers that have been studied in aspiration and those who might have a potential clinical use in the future.

Biomarkers: a definite plus in pneumonia

During the past few years, biomarkers have emerged as an indispensible tool in the diagnosis of pneumonia. To find an ideal diagnostic biomarker for pneumonia is not an easy task. Not only should it allow an early diagnosis of the condition, but it should also allow differential diagnosis from other noninfectious conditions. Ongoing research is being done in this field so as to put an array of biomarkers at the disposal of doctors to improve the diagnosis of pneumonia when patients present to them with cough or nonspecific symptoms which could easily be misinterpreted as symptoms of other conditions. Procalcitonin and soluble triggering receptor expressed on myeloid cells-1 have emerged as reliable diagnostic markers in pneumonia, and are better when compared to other markers, namely, C-reactive protein, leukocyte count, and proinflammatory cytokines. Many other biomarkers are being studied for their probable use in diagnosing pneumonia but have yet to prove their benefit.

Sepsis biomarkers: a review

INTRODUCTION

Biomarkers can be useful for identifying or ruling out sepsis, identifying patients who may benefit from specific therapies or assessing the response to therapy.

METHODS

We used an electronic search of the PubMed database using the key words "sepsis" and "biomarker" to identify clinical and experimental studies which evaluated a biomarker in sepsis.

RESULTS

The search retrieved 3370 references covering 178 different biomarkers.

CONCLUSIONS

Many biomarkers have been evaluated for use in sepsis. Most of the biomarkers had been tested clinically, primarily as prognostic markers in sepsis; relatively few have been used for diagnosis. None has sufficient specificity or sensitivity to be routinely employed in clinical practice. PCT and CRP have been most widely used, but even these have limited ability to distinguish sepsis from other inflammatory conditions or to predict outcome.

Opposed circulating plasma levels of endothelin-1 and C-type natriuretic peptide in children with Plasmodium falciparum malaria

Background

Molecular mechanisms involved in the pathogenesis of severe Plasmodium falciparum malaria (SM), are not yet fully understood. Both endothelin-1 (ET-1) and C-type natriuretic peptide (CNP) are produced by vascular endothelium and act locally as paracrine regulators of vascular tone, ET-1 being a potent vasoconstrictor and CNP having strong vasorelaxant properties.

Methods

Plasma levels of ET-1 and N-terminal fragments of CNP (NT-proCNP) were studied on admission and after 24 hours of treatment, using enzyme-linked-immunosorbent-assay (ELISA) technique, in Gabonese children with severe falciparum malaria (SM, n = 50), with uncomplicated malaria (UM, n = 39) and healthy controls (HC, n = 25).

Results

Compared to HC, malaria patients had significantly higher plasma levels of ET-1 and significantly lower levels of NT-proCNP (p < 0.001 and p < 0.024 respectively). Plasma levels of NT-proCNP were additionally decreased in SM patients compared to HC (p = 0.034), whereas UM was not significantly different to HC. In the SM group we found a trend towards lower ET-1 levels compared to UM (p = 0.085).

Conclusion

In the present study, an imbalance between the vasoconstricitve and vasorelaxant endothelium-derived substances ET-1 and CNP in the plasma of children with falciparum malaria is demonstrated, presumably in favor of vasoconstrictive and pro-inflammatory effects. These results may indicate involvement of ET-1 and CNP in malaria pathogenesis. Furthermore, results of lower ET-1 and CNP levels in SM may reflect endothelial cell damage.