Application of clinical proteomics in diagnosis and management of trauma patients

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

BACKGROUND

The endotheliopathy of trauma (EoT) is associated with increased mortality following injury. Herein, we describe the plasma proteome related to EoT in order to provide insight into the role of the endothelium within the systemic response to trauma.

METHODS

99 subjects requiring the highest level of trauma activation were included in the study. Enzyme-linked immunosorbent assays of endothelial and catecholamine biomarkers were performed on admission plasma samples, as well as untargeted proteome quantification utilizing high-performance liquid chromatography and tandem mass spectrometry.

RESULTS

Plasma endothelial and catecholamine biomarker abundance was elevated in EoT. Patients with EoT (n = 62) had an increased incidence of death within 24 h at 21% compared to 3% for non-EoT (n = 37). Proteomic analysis revealed that 52 out of 290 proteins were differentially expressed between the EoT and non-EoT groups. These proteins are involved in endothelial activation, coagulation, inflammation, and oxidative stress, and include known damage-associated molecular patterns (DAMPs) and intracellular proteins specific to several organs.

CONCLUSIONS

We report a proteomic profile of EoT suggestive of a surge of DAMPs and inflammation driving nonspecific activation of the endothelial, coagulation, and complement systems with subsequent end-organ damage and poor clinical outcome. These findings support the utility of EoT as an index of cellular injury and delineate protein candidates for therapeutic intervention.

Metabolomics based predictive biomarker model of ARDS: A systemic measure of clinical hypoxemia

Despite advancements in ventilator technologies, lung supportive and rescue therapies, the outcome and prognostication in acute respiratory distress syndrome (ARDS) remains incremental and ambiguous. Metabolomics is a potential insightful measure to the diagnostic approaches practiced in critical disease settings. In our study patients diagnosed with mild and moderate/severe ARDS clinically governed by hypoxemic P/F ratio between 100-300 but with indistinct molecular phenotype were discriminated employing nuclear magnetic resonance (NMR) based metabolomics of mini bronchoalveolar lavage fluid (mBALF). Resulting biomarker prototype comprising six metabolites was substantiated highlighting ARDS susceptibility/recovery. Both the groups (mild and moderate/severe ARDS) showed distinct biochemical profile based on 83.3% classification by discriminant function analysis and cross validated accuracy of 91% using partial least squares discriminant analysis as major classifier. The predictive performance of narrowed down six metabolites were found analogous with chemometrics. The proposed biomarker model consisting of six metabolites proline, lysine/arginine, taurine, threonine and glutamate were found characteristic of ARDS sub-stages with aberrant metabolism observed mainly in arginine, proline metabolism, lysine synthesis and so forth correlating to diseased metabotype. Thus NMR based metabolomics has provided new insight into ARDS sub-stages and conclusively a precise biomarker model proposed, reflecting underlying metabolic dysfunction aiding prior clinical decision making.

Polytrauma – new horizons for management

The management of polytrauma has evolved considerably in the last century. Advances have been made in all disciplines involved in trauma care from pre-hospital care and resuscitation protocols to diagnostics, surgical techniques, administration of novel pharmacological agents and late reconstruction procedures. Improved understanding of the altered physiology and the induced response at the molecular level offers the potential for novel management strategies and prevention of post-traumatic complications.

Personalized medicine: genetic variation and loss of physiologic complexity are associated with mortality in 644 trauma patients

OBJECTIVE

Personalized medicine merges genetics, physiology, and patient outcome. Loss of physiologic complexity (heart rate [HR] variability) is a bedside biomarker for autonomic nervous system (ANS) dysfunction. We hypothesized that variability in ANS receptor proteins (genetics) and loss of complexity (physiology) are independently associated with mortality in critical illness.

SUMMARY BACKGROUND DATA

Decreased HR complexity has been associated with increased mortality and morbidity in trauma and other critically ill populations. Genetic variations in alpha-1A and beta-2 adrenergic receptors (ADRA1A, ADRB2) have been associated with changes in smooth muscle tone in various tissues, and implicated in bronchial hyper-responsiveness, metabolic syndrome, and other disorders.

METHODS

A cohort of 644 trauma intensive care unit (ICU) admissions had complexity data and genetic samples. Two ANS receptor polymorphisms (rs1048101, Alpha ADRA1A and rs1042714, Beta ADRB2) were genotyped. Physiologic complexity at various points in the ICU stay was measured using previously-studied integer HR multiscale entropy (MSE) over 6-hour intervals (~21,600 HR data points/interval/patient). Logistic regression assessed the concurrent relationship of genotypes, complexity, and probability of survival, an acuity score incorporating age, injury mechanism/severity, and admission vitals, to risk of death.

RESULTS

Of total, 96 patients (15%) died. Nonsurvivors had lower complexity at early, middle, and late portions of ICU stay (median MSE at least 25% less in nonsurvivors, P < 0.001) and lower incidence of the GG ADRB2 genotype (7.5% vs. 18.3%, P < 0.001). In multivariable logistic regression, the GG ADRB2 genotype carried ~3-fold decrease in mortality odds (odd ratio [OR] = 0.33, P = 0.01), independent of significant effects in HR MSE (OR = 0.93, P < 0.001), and probability of survival (OR = 0.22, P < 0.001).

CONCLUSIONS

This first study to simultaneously examine ANS genetics, the biomarker complexity, and mortality concludes: (1) ANS genetics and physiologic complexity are independently related to mortality; (2) Genetics and complexity add information over traditional acuity scoring (probability of survival); and (3) Simultaneous assessment of ANS physiology and genetics may yield novel research, diagnostic, and therapeutic opportunities in critical illness.

Randomized prospective clinical trial comparing reamer irrigator aspirator (RIA) to standard reaming (SR) in both minimally injured and multiply injured patients with closed femoral shaft fractures treated with reamed intramedullary nailing (IMN)

PURPOSE

To investigate whether inflammatory markers are improved among patients with traumatic femur fractures who undergo RIA reamed intramedullary nailing (IMN) prior to fixation when compared to patients treated with standard reamed (SR) IMN.

METHODS

A prospective, randomized, single-blind trial was conducted on patients who had a closed femoral shaft fracture amenable to reamed IMN. Patients were randomized to undergo IMN with standard reaming or IMN with the RIA in a 1:1 ratio. Patients were stratified by Injury Severity Score (ISS) and by presence or absence of chest injury with AIS > 3. Patients had blood samples and bronchioalveolar lavage samples taken at specified time points pre- and postoperatively. Specimens from SR and RIA cohorts were compared for the presence of IL-2, IL-6, IL-8, TNF, and IL-10 in plasma and IL-1b and IL-8 in bronchioalveolar lavage (BAL) samples to determine the relationship between inflammatory markers and intramedullary reaming.

RESULTS

Nineteen consecutive patients participated in the study with 9 assigned in the RIA group and 10 in SR group. Significant differences existed for ISS between SR and RIA groups (p=0.04). Bronchial lavage data showed no statistical significant differences when RIA and standard reamers were compared and when ISS >16 and <16 were compared, however there were differences for the bronchial IL-8 change when those with chest injury were compared to those without chest injury. Plasma samples showed a trend towards increased IL-6 and IL-10 levels after reaming consistent with the second hit impact. A trend towards higher levels for IL-6 in the SR group was noted at 24 hours post-operatively whereas the IL-10 levels at the post-reaming time point were higher in the RIA group.

CONCLUSIONS

This prospective study of reamer type indicates that RIA may be protective of systemic inflammation. This is supported by data showing decreased levels of IL-8 in the bronchial washings and increased level of IL-10 in the serum. Reaming and intramedullary fixation may cause an increase in IL-6 levels regardless of reamer type. Further investigations with a larger cohort of patients are desirable.

Mass spectrometry based targeted protein quantification: methods and applications

The recent advance in technology for mass spectrometry-based targeted protein quantification has opened new avenues for a broad range of proteomic applications in clinical research. The major breakthroughs are highlighted by the capability of using a "universal" approach to perform quantitative assays for a wide spectrum of proteins with minimum restrictions and the ease of assembling multiplex detections in a single measurement. The quantitative approach relies on the use of synthetic stable isotope labeled peptides or proteins, which precisely mimic their endogenous counterparts and act as internal standards to quantify the corresponding candidate proteins. This report reviews recently developed platform technologies for emerging applications of clinical proteomics and biomarker development.

Advances in molecular acute lung injury/acute respiratory distress syndrome and ventilator-induced lung injury: the role of genomics, proteomics, bioinformatics and translational biology

PURPOSE OF REVIEW

To discuss emerging technologies and their application to translation biology research in the field of acute lung injury/acute respiratory distress syndrome and ventilator-induced lung injury.

RECENT FINDINGS

Significant advances in the field of innovative therapeutics rely on our ability to identify and validate targets derived from biomedical breakthrough discoveries. The review considers recent studies that have creatively applied and integrated genomics, bioinformatics and/or proteomics to identifying novel candidate molecular targets. The focus is to present how innovative strategies have been exploited and combined with elegant translational biology experiments to advance the field of molecular acute respiratory distress syndrome/acute lung injury and ventilator-induced lung injury.

SUMMARY

Renewed efforts to define the clinical phenotype have coincided with the availability of novel technology that has the potential to address critical molecular aspects of the syndrome. Convergence of these two approaches is expected to bring about a better understanding of acute lung injury and consequently further advances in treatment.

Growth factor release following femoral nailing

The aim of this study was to investigate whether growth factors essential for fracture healing are substantially increased in the immediate aftermath following reaming of the intramedullary cavity for stabilisation of femoral shaft fractures. Consecutive adult patients whose femoral shaft fractures stabilised with either reamed (10 patients) or unreamed (10 patients) intramedullary nailing were studied. Peripheral blood samples and samples from the femoral canal before and after reaming and nail insertion were collected. Serum was extracted and using Elisa colorimetric assays the concentration of Platelet Derived Growth Factor-BetaBeta (PDGF), Vascular Endothelial Growth Factor (VEGF), Insulin-like Growth Factor-I (IGF-I), Transforming Growth Factor beta 1 (TGF-beta1) and Bone Morphogenetic Protein-2 (BMP-2) was measured. The mean age of the twenty patients who participated in the study was 38 years (range 20-63). Reaming substantially increased all studied growth factors (p<0.05) locally in the femoral canal. VEGF and PDGF were increased after reaming by 111.2% and 115.6% respectively. IGF-I was increased by 31.5% and TGF-beta1 was increased by 54.2%. In the unreamed group the levels of PDGF-BB, VEGF, TGF-beta1 remained unchanged while the levels of IGF-I decreased by 10%. The levels of these mediators in the peripheral circulation were not altered irrespectively of the nail insertion technique used. BMP-2 levels during all time points were below the detection limit of the immunoassay. This study indicates that reaming of the intramedullary cavity is associated with increased liberation of growth factors. The osteogenic effect of reaming could be secondary not only to grafting debris but also to the increased liberation of these molecules.

[Developments in polytrauma management. Priority-based strategy]

The acute and early phase of polytrauma management is decisive for determining and implementing priority-based operative strategy. The patient's general condition and pattern of injury have to be considered. The highest priorities in the acute phase of operative treatment are control of mass bleeding and the release of body cavities (life-saving surgery). In the primary phase of surgical management (day 1 surgery), selected injuries are treated in the order of their urgency. Conceptual damage control surgery is distinguished from early total care. Damage control surgery should be performed only in patients meeting certain instability and risk criteria to avoid additionally burdening their condition.

Quantification and characterisation of endothelial injury after trauma

The microenvironment theory has become very popular for providing mechanisms which explain the development of often lethal posttraumatic complications such as systemic inflammatory response syndrome (SIRS), adult respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS). With the recent advances in molecular biology and the ever-expanding understanding of trauma pathophysiology, immunomonitoring in trauma patients attempts to characterise and quantify novel molecules in order to predict patients at risk. This review article assesses the existing evidence on the biomarkers of endothelial injury and their potential utility as quantification parameters of endothelial dysfunction in trauma patients.