Shock releases bile acid inducing platelet inhibition and fibrinolysis

Metabolic signatures of cardiorenal dysfunction in plasma from sickle cell patients as a function of therapeutic transfusion and hydroxyurea treatment

Metabolomics studies in sickle cell disease (SCD) have been so far limited to tens of samples, owing to technical and experimental limitations. To overcome these limitations, we performed plasma metabolomics analyses on 596 samples from patients with SCD enrolled in the WALK-PHaSST study (clinicaltrials gov. Identifier: NCT00492531). Clinical covariates informed the biological interpretation of metabolomics data, including genotypes (hemoglobin [Hb] SS, hemoglobin SC), history of recent transfusion (HbA%), response to hydroxyurea treatment (fetal Hb%). We investigated metabolic correlates to the degree of intravascular hemolysis, cardiorenal function, as determined by tricuspid regurgitation velocity (TRV), estimated glomerular filtration rate (eGFR), and overall hazard ratio (unadjusted or adjusted by age). Recent transfusion events or hydroxyurea treatment were associated with elevation in plasma-free fatty acids and decreases in acyl-carnitines, urate, kynurenine, indoles, carboxylic acids, and glycine- or taurine-conjugated bile acids. High levels of these metabolites, along with low levels of plasma S1P and L-arginine were identified as top markers of hemolysis, cardiorenal function (TRV, eGFR), and overall hazard ratio. We thus uploaded all omics and clinical data on a novel online portal that we used to identify a potential mechanism of dysregulated red cell S1P synthesis and export as a contributor to the more severe clinical manifestations in patients with the SS genotype compared to SC. In conclusion, plasma metabolic signatures - including low S1P, arginine and elevated kynurenine, acyl-carnitines and bile acids - are associated with clinical manifestation and therapeutic efficacy in SCD patients, suggesting new avenues for metabolic interventions in this patient population.

The proteomic and metabolomic signatures of isolated and polytrauma traumatic brain injury

BACKGROUND

The interactions of polytrauma, shock, and traumatic brain injury (TBI) on thromboinflammatory responses remain unclear and warrant investigation as we strive towards personalized medicine in trauma. We hypothesized that comprehensive omics characterization of plasma would identify unique metabolic and thromboinflammatory pathways following TBI.

METHODS

Patients were categorized as TBI vs Non-TBI, and stratified into Polytrauma or minimally injured. Discovery 'omics was employed to quantify the top differently expressed proteins and metabolites of TBI and Non-TBI patient groups.

RESULTS

TBI compared to Non-TBI showed gene enrichment in coagulation/complement cascades and neuronal markers. TBI was associated with elevation in glycolytic metabolites and conjugated bile acids. Division into isolated TBI vs polytrauma showed further distinction of proteomic and metabolomic signatures.

CONCLUSION

Identified mediators involving in neural inflammation, blood brain barrier disruption, and bile acid building leading to TBI associated coagulopathy offer suggestions for follow up mechanistic studies to target personalized interventions.

Omics Signatures of Tissue Injury and Hemorrhagic Shock in Swine

OBJECTIVE

Advanced mass spectrometry methods were leveraged to analyze both proteomics and metabolomics signatures in plasma upon controlled tissue injury (TI) and hemorrhagic shock (HS)-isolated or combined-in a swine model, followed by correlation to viscoelastic measurements of coagulopathy via thrombelastography.

BACKGROUND

TI and HS cause distinct molecular changes in plasma in both animal models and trauma patients. However, the contribution to coagulopathy of trauma, the leading cause of preventable mortality in this patient population remains unclear. The recent development of a swine model for isolated or combined TI+HS facilitated the current study.

METHODS

Male swine (n=17) were randomized to either isolated or combined TI and HS. Coagulation status was analyzed by thrombelastography during the monitored time course. The plasma fractions of the blood draws (at baseline; end of shock; and at 30 minutes, 1, 2, and 4 hours after shock) were analyzed by mass spectrometry-based proteomics and metabolomics workflows.

RESULTS

HS-isolated or combined with TI-caused the most severe omic alterations during the monitored time course. While isolated TI delayed the activation of coagulation cascades. Correlation to thrombelastography parameters of clot strength (maximum amplitude) and breakdown (LY30) revealed signatures of coagulopathy which were supported by analysis of gene ontology-enriched biological pathways.

CONCLUSION

The current study provides a comprehensive characterization of proteomic and metabolomic alterations to combined or isolated TI and HS in a swine model and identifies early and late omics correlates to viscoelastic measurements in this system.

Omics markers of platelet transfusion in trauma patients

BACKGROUND

Even in the era of the COVID-19 pandemic, trauma remains the global leading cause of mortality under the age of 49. Trauma-induced coagulopathy is a leading driver of early mortality in critically ill patients, and transfusion of platelet products is a life-saving intervention to restore hemostasis in the bleeding patient. However, despite extensive functional studies based on viscoelastic assays, limited information is available about the impact of platelet transfusion on the circulating molecular signatures in trauma patients receiving platelet transfusion.

MATERIALS AND METHODS

To bridge this gap, we leveraged metabolomics and proteomics approaches to characterize longitudinal plasma samples (n = 118; up to 11 time points; total samples: 759) from trauma patients enrolled in the Control Of Major Bleeding After Trauma (COMBAT) study. Samples were collected in the field, in the emergency department (ED), and at intervals up to 168 h (7 days) post-hospitalization. Transfusion of platelet (PLT) products was performed (n = 30; total samples: 250) in the ED through 24 h post-hospitalization. Longitudinal plasma samples were subjected to mass spectrometry-based metabolomics and proteomics workflows. Multivariate analyses were performed to determine omics markers of transfusion of one, two, three, or more PLT transfusions.

RESULTS

Higher levels of tranexamic acid (TXA), inflammatory proteins, carnitines, and polyamines were detected in patients requiring PLT transfusion. Correlation of PLT units with omics data suggested sicker patients required more units and partially overlap with the population requiring transfusion of packed red blood cell products. Furthermore, platelet activation was likely increased in the most severely injured patients. Fatty acid levels were significantly lower in PLT transfusion recipients (at time of maximal transfusion: Hour 4) compared with non-recipients, while carnitine levels were significantly higher. Fatty acid levels restore later in the time course (e.g., post-PLT transfusion).

DISCUSSION

The present study provides the first multi-omics characterization of platelet transfusion efficacy in a clinically relevant cohort of trauma patients. Physiological alterations following transfusion were detected, highlighting the efficacy of mass spectrometry-based omics techniques to improve personalized transfusion medicine. More specialized clinical research studies focused on PLT transfusion, including organized pre and post transfusion sample collection and limitation to PLT products only, are required to fully understand subsequent metabolomic and proteomic alterations.

Red Blood Cell Omics and Machine Learning in Transfusion Medicine: Singularity Is Near

Background

Blood transfusion is a life-saving intervention for millions of recipients worldwide. Over the last 15 years, the advent of high-throughput, affordable omics technologies - including genomics, proteomics, lipidomics, and metabolomics - has allowed transfusion medicine to revisit the biology of blood donors, stored blood products, and transfusion recipients.

Summary

Omics approaches have shed light on the genetic and non-genetic factors (environmental or other exposures) impacting the quality of stored blood products and efficacy of transfusion events, based on the current Food and Drug Administration guidelines (e.g., hemolysis and post-transfusion recovery for stored red blood cells). As a treasure trove of data accumulates, the implementation of machine learning approaches promises to revolutionize the field of transfusion medicine, not only by advancing basic science. Indeed, computational strategies have already been used to perform high-content screenings of red blood cell morphology in microfluidic devices, generate in silico models of erythrocyte membrane to predict deformability and bending rigidity, or design systems biology maps of the red blood cell metabolome to drive the development of novel storage additives.

Key Message

In the near future, high-throughput testing of donor genomes via precision transfusion medicine arrays and metabolomics of all donated products will be able to inform the development and implementation of machine learning strategies that match, from vein to vein, donors, optimal processing strategies (additives, shelf life), and recipients, realizing the promise of personalized transfusion medicine.

Metabolic signatures of cardiorenal dysfunction in plasma from sickle cell patients, as a function of therapeutic transfusion and hydroxyurea treatment

Metabolomics studies in sickle cell disease (SCD) have been so far limited to tens of samples, owing to technical and experimental limitations. To overcome these limitations, we performed plasma metabolomics analyses on 596 samples from patients with sickle cell sickle cell disease (SCD) enrolled in the WALK-PHaSST study. Clinical covariates informed the biological interpretation of metabolomics data, including genotypes (hemoglobin SS, hemoglobin SC), history of recent transfusion (HbA%), response to hydroxyurea treatment (HbF%). We investigated metabolic correlates to the degree of hemolysis, cardiorenal function, as determined by tricuspid regurgitation velocity (TRV), estimated glomerular filtration rate (eGFR), and overall hazard ratio (unadjusted or adjusted by age). Recent transfusion events or hydroxyurea treatment were associated with elevation in plasma free fatty acids and decreases in acyl-carnitines, urate, kynurenine, indoles, carboxylic acids, and glycine- or taurine-conjugated bile acids. High levels of these metabolites, along with low levels of plasma S1P and L-arginine were identified as top markers of hemolysis, cardiorenal function (TRV, eGFR), and overall hazard ratio. We thus uploaded all omics and clinical data on a novel online portal that we used to identify a potential mechanism of dysregulated red cell S1P synthesis and export as a contributor to the more severe clinical manifestations in patients with the SS genotype compared to SC. In conclusion, plasma metabolic signatures - including low S1P, arginine and elevated kynurenine, acyl-carnitines and bile acids - are associated with clinical manifestation and therapeutic efficacy in SCD patients, suggesting new avenues for metabolic interventions in this patient population.

Importance of catecholamine signaling in the development of platelet exhaustion after traumatic injury

BACKGROUND

Impaired ex vivo platelet aggregation is common in trauma patients. The mechanisms driving these impairments remain incompletely understood, but functional platelet exhaustion due to excessive in vivo activation is implicated. Given platelet adrenoreceptors and known catecholamine surges after injury, impaired ex vivo platelet aggregation in trauma patients may be linked to catecholamine-induced functional platelet exhaustion.

OBJECTIVE

To determine the relationship of catecholamines with platelet-dependent hemostasis after injury and to model catecholamine-induced functional platelet exhaustion in healthy donor platelets.

PATIENTS/METHODS

Whole blood was collected from 67 trauma patients as part of a prospective cohort study. Platelet aggregometry and rotational thromboelastometry were performed, and plasma epinephrine (EPI) and norepinephrine (NE) concentrations were measured. The effect of catecholamines on healthy donor platelets was examined in a microfluidic model, with platelet aggregometry, and by flow cytometry examining surface markers of platelet activation.

RESULTS

In trauma patients, EPI and NE were associated with impaired platelet aggregation (both p < 0.05), and EPI was additionally associated with decreased viscoelastic clot strength, increased fibrinolysis, and mortality (all p < 0.05). In healthy donors, short duration incubation with EPI enhanced platelet aggregation, platelet adhesion under flow, and increased glycoprotein IIb/IIIa activation, while weaker effects were observed with NE. Compared with short incubation, longer incubation with EPI resulted in decreased platelet adhesion, platelet aggregation, and surface expression of glycoprotein IIb/IIIa.

CONCLUSIONS

These findings suggest sympathoadrenal activation in trauma patients contributes to impaired ex vivo platelet aggregation, which mechanistically may be explained by a functionally exhausted platelet phenotype under prolonged exposure to high plasma catecholamine levels.

Gut microbiota and derived metabolomic profiling in glaucoma with progressive neurodegeneration

Glaucoma is a multifactorial, neurodegenerative disorder characterized by the loss of retinal ganglion cells (RGCs). Crosstalk between the gut microbiota and host is involved in the progression of many neurodegenerative diseases, although little is known about its role in glaucoma. To investigated the alterations of the gut microbiota and derived metabolites in glaucomatous rats, and the interaction with RGCs, we performed 16S rRNA (V1-V9) sequencing and untargeted metabolomic analyses. The microbial composition differed significantly between the two groups, and the diversity of cecal bacteria was dramatically reduced in glaucomatous rats. The Firmicutes/Bacteroidetes (F/B) ratio, Verrucomicrobia phylum, and some bacterial genera (Romboutsia, Akkermansia, and Bacteroides) were dramatically increased in the glaucomatous rat model compared with the control, which showed negative correlation with RGCs. Untargeted metabolomic analysis identified 284 differentially expressed metabolites, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed considerable enrichment mainly in bile secretion pathways. The relationships among the metabolites enriched in the bile secretion pathway, differentially expressed cecal microbiota, and RGCs were investigated, and glutathione (GSH) was found to be negatively correlated with Bacteroides and F/B and positively correlated with RGCs. Reduced GSH level in the blood of glaucoma rats is further established, and was negatively correlated with Romboutsia and the F/B ratio and positively correlated with RGCs. This finding suggests the potential role of the gut microbiota and derived metabolites in glaucoma, and GSH, a major antioxidant metabolite, was related to their effects, indicating the potential for the development of gut microbiota-targeted interventions for glaucoma.

Retention of functional mitochondria in mature red blood cells from patients with sickle cell disease

Sickle cell disease (SCD) is an inherited blood disorder characterized by sickled red blood cells (RBCs), which are more sensitive to haemolysis and can contribute to disease pathophysiology. Although treatment of SCD can include RBC transfusion, patients with SCD have high rates of alloimmunization. We hypothesized that RBCs from patients with SCD have functionally active mitochondria and can elicit a type 1 interferon response. We evaluated blood samples from more than 100 patients with SCD and found elevated frequencies of mitochondria in reticulocytes and mature RBCs, as compared to healthy blood donors. The presence of mitochondria in mature RBCs was confirmed by flow cytometry, electron microscopy, and proteomic analysis. The mitochondria in mature RBCs were metabolically competent, as determined by enzymatic activities and elevated levels of mitochondria-derived metabolites. Metabolically-active mitochondria in RBCs may increase oxidative stress, which could facilitate and/or exacerbate SCD complications. Coculture of mitochondria-positive RBCs with neutrophils induced production of type 1 interferons, which are known to increase RBC alloimmunization rates. These data demonstrate that mitochondria retained in mature RBCs are functional and can elicit immune responses, suggesting that inappropriate retention of mitochondria in RBCs may play an underappreciated role in SCD complications and be an RBC alloimmunization risk factor.

Irradiation Causes Alterations of Polyamine, Purine, and Sulfur Metabolism in Red Blood Cells and Multiple Organs

Investigating the metabolic effects of radiation is critical to understand the impact of radiotherapy, space travel, and exposure to environmental radiation. In patients undergoing hemopoietic stem cell transplantation, iron overload is a common risk factor for poor outcomes. However, no studies have interrogated the multiorgan effects of these treatments concurrently. Herein, we use a model that recapitulates transfusional iron overload, a condition often observed in chronically transfused patients. We applied an omics approach to investigate the impact of both the iron load and irradiation on the host metabolome. The results revealed dose-dependent effects of irradiation in the red blood cells, plasma, spleen, and liver energy and redox metabolism. Increases in polyamines and purine salvage metabolites were observed in organs with high oxygen consumption including the heart, kidneys, and brain. Irradiation also impacted the metabolism of the duodenum, colon, and stool, suggesting a potential effect on the microbiome. Iron infusion affected the response to radiation in the organs and blood, especially in erythrocyte polyamines and spleen antioxidant metabolism, and affected glucose, methionine, and glutathione systems and tryptophan metabolism in the liver, stool, and the brain. Together, the results suggest that radiation impacts metabolism on a multiorgan level with a significant interaction of the host iron status.

A new trauma frontier: Exploratory pilot study of platelet transcriptomics in trauma patients

BACKGROUND

The earliest measurable changes to postinjury platelet biology may be in the platelet transcriptome, as platelets are known to carry messenger ribonucleic acids (RNAs), and there is evidence in other inflammatory and infectious disease states of differential and alternative platelet RNA splicing in response to changing physiology. Thus, the aim of this exploratory pilot study was to examine the platelet transcriptome and platelet RNA splicing signatures in trauma patients compared with healthy donors.

METHODS

Preresuscitation platelets purified from trauma patients (n = 9) and healthy donors (n = 5) were assayed using deep RNA sequencing. Differential gene expression analysis, weighted gene coexpression network analysis, and differential alternative splicing analyses were performed. In parallel samples, platelet function was measured with platelet aggregometry, and clot formation was measured with thromboelastography.

RESULTS

Differential gene expression analysis identified 49 platelet RNAs to have differing abundance between trauma patients and healthy donors. Weighted gene coexpression network analysis identified coexpressed platelet RNAs that correlated with platelet aggregation. Differential alternative splicing analyses revealed 1,188 splicing events across 462 platelet RNAs that were highly statistically significant (false discovery rate <0.001) in trauma patients compared with healthy donors. Unsupervised principal component analysis of these platelet RNA splicing signatures segregated trauma patients in two main clusters separate from healthy controls.

CONCLUSION

Our findings provide evidence of finetuning of the platelet transcriptome through differential alternative splicing of platelet RNA in trauma patients and that this finetuning may have relevance to downstream platelet signaling. Additional investigations of the trauma platelet transcriptome should be pursued to improve our understanding of the platelet functional responses to trauma on a molecular level.

Changes of farnesoid X receptor and Takeda G‑protein coupled receptor 5 following biliary tract external drainage in hemorrhagic shock

Since biliary tract external drainage (BTED) is increasingly used to treat patients with shock, it is necessary to clarify pathophysiological changes following BTED in hemorrhagic shock (HS). The present study aimed to investigate the effect of BTED on farnesoid X receptor (FXR) and Takeda G-protein coupled receptor 5 (TGR-5) expression in HS. A total of 24 Sprague-Dawley rats were randomly allocated to sham, BTED, HS and HS + BTED groups. Rat models of HS were induced by drawing blood from the femoral artery until a mean arterial pressure of 40±5 mmHg was achieved and maintained for 60 min. Rat models of BTED were induced by inserting a catheter into the bile duct. The distal end of the bile duct was ligated, and the catheter was passed through the rat flank to allow external collection of bile. Reverse transcription-quantitative PCR, western blotting and immunohistochemistry were performed to detect changes in expression levels of FXR and TGR-5 in the jejunum, ileum and liver. Expression levels of FXR and TGR-5 increased significantly in jejunum and liver following HS (P<0.05). BTED significantly decreased expression levels of FXR in the liver (P<0.05) and TGR-5 in the jejunum, ileum and liver (P<0.05). In conclusion, expression levels of FXR and TGR-5 increased in HS but BTED decreased expression levels of FXR and TGR-5 in HS.

Biological and Clinical Factors Contributing to the Metabolic Heterogeneity of Hospitalized Patients with and without COVID-19

The Corona Virus Disease 2019 (COVID-19) pandemic represents an ongoing worldwide challenge. The present large study sought to understand independent and overlapping metabolic features of samples from acutely ill patients (n = 831) that tested positive (n = 543) or negative (n = 288) for COVID-19. High-throughput metabolomics analyses were complemented with antigen and enzymatic activity assays on plasma from acutely ill patients collected while in the emergency department, at admission, or during hospitalization. Lipidomics analyses were also performed on COVID-19-positive or -negative subjects with the lowest and highest body mass index (n = 60/group). Significant changes in amino acid and fatty acid/acylcarnitine metabolism emerged as highly relevant markers of disease severity, progression, and prognosis as a function of biological and clinical variables in these patients. Further, machine learning models were trained by entering all metabolomics and clinical data from half of the COVID-19 patient cohort and then tested on the other half, yielding ~78% prediction accuracy. Finally, the extensive amount of information accumulated in this large, prospective, observational study provides a foundation for mechanistic follow-up studies and data sharing opportunities, which will advance our understanding of the characteristics of the plasma metabolism in COVID-19 and other acute critical illnesses.

Biological and Clinical Factors contributing to the Metabolic Heterogeneity of Hospitalized Patients with and without COVID-19

The Corona Virus Disease 2019 (COVID-19) pandemic represents an ongoing worldwide challenge. Exploratory studies evaluating the impact of COVID-19 infection on the plasma metabolome have been performed, often with small numbers of patients, and with or without relevant control data; however, determining the impact of biological and clinical variables remains critical to understanding potential markers of disease severity and progression. The present large study, including relevant controls, sought to understand independent and overlapping metabolic features of samples from acutely ill patients (n = 831), testing positive (n = 543) or negative (n = 288) for COVID-19. High-throughput metabolomics analyses were complemented with antigen and enzymatic activity assays on 831 plasma samples from acutely ill patients while in the emergency department, at admission, and during hospitalization. We then performed additional lipidomics analyses of the 60 subjects with the lowest and highest body mass index, either COVID-19 positive or negative. Omics data were correlated to detailed data on patient characteristics and clinical laboratory assays measuring coagulation, hematology and chemistry analytes. Significant changes in arginine/proline/citrulline, tryptophan/indole/kynurenine, fatty acid and acyl-carnitine metabolism emerged as highly relevant markers of disease severity, progression and prognosis as a function of biological and clinical variables in these patients. Further, machine learning models were trained by entering all metabolomics and clinical data from half of the COVID-19 patient cohort and then tested on the other half yielding ~ 78% prediction accuracy. Finally, the extensive amount of information accumulated in this large, prospective, observational study provides a foundation for follow-up mechanistic studies and data sharing opportunities, which will advance our understanding of the characteristics of the plasma metabolism in COVID-19 and other acute critical illnesses.

Metabolic Characterization of Plasma and Cyst Fluid from Cystic Precursors to Pancreatic Cancer Patients Reveal Metabolic Signatures of Bacterial Infection

Pancreatic cancer is the seventh leading cause of cancer-related death worldwide, with a 5 year survival rate as low as 9%. One factor complicating the management of pancreatic cancer is the lack of reliable tools for early diagnosis. While up to 50% of the adult population has been shown to develop precancerous pancreatic cysts, limited and insufficient approaches are currently available to determine whether a cyst is going to progress into pancreatic cancer. Recently, we used metabolomics approaches to identify candidate markers of disease progression in patients diagnosed with intraductal papillary mucinous neoplasms (IPMNs) undergoing pancreatic resection. Here, we enrolled an independent cohort to verify the candidate markers from our previous study with orthogonal quantitative methods in plasma and cyst fluid from serous cystic neoplasm and IPMN (either low- or high-grade dysplasia or pancreatic ductal adenocarcinoma). We thus validated these markers with absolute quantitative methods through the auxilium of stable isotope-labeled internal standards in a new independent cohort. Finally, we identified novel markers of IPMN status and disease progression-including amino acids, carboxylic acids, conjugated bile acids, free and carnitine-conjugated fatty acids, purine oxidation products, and trimethylamine-oxide. We show that the levels of these metabolites of potential bacterial origin correlated with the degree of bacterial enrichment in the cyst, as determined by 16S RNA. Overall, our findings are interesting per se, owing to the validation of previous markers and identification of novel small molecule signatures of IPMN and disease progression. In addition, our findings further fuel the provoking debate as to whether bacterial infections may represent an etiological contributor to the development and severity of the disease in pancreatic cancer, in like fashion to other cancers (e.g., Helicobacter pylori and gastric cancer).

Good Platelets Gone Bad: The Effects of Trauma Patient Plasma on Healthy Platelet Aggregation

BACKGROUND

Altered postinjury platelet behavior is recognized in the pathophysiology of trauma-induced coagulopathy (TIC), but the mechanisms remain largely undefined. Studies suggest that soluble factors released by injury may inhibit signaling pathways and induce structural changes in circulating platelets. Given this, we sought to examine the impact of treating healthy platelets with plasma from injured patients. We hypothesized that healthy platelets treated ex-vivo with plasma from injured patients with shock would impair platelet aggregation, while treatment with plasma from injured patients with significant injury burden, but without shock, would enhance platelet aggregation.

METHODS

Plasma samples were isolated from injured patients (pretransfusion) and healthy donors at a Level I trauma center and stored at -80°C. Plasma samples from four separate patients in each of the following stratified clinical groups were used: mild injury/no shock (injury severity score [ISS] 2-15, base excess [BE]>-6), mild injury/with shock (ISS 2-15, BE≤-6), severe injury/no shock (ISS>25, BE>-6), severe injury/with shock (ISS>25, BE≤-6), minimal injury (ISS 0/1, BE>-6), and healthy. Platelets were isolated from three healthy adult males and were treated with plasma for 30 min. Aggregation was stimulated with a thrombin receptor agonist and measured via multiple-electrode platelet aggregometry. Data were normalized to HEPES Tyrode's (HT) buffer-only treated platelets. Associations of plasma treatment groups with platelet aggregation measures were tested with Mann-Whitney U tests.

RESULTS

Platelets treated with plasma from patients with shock (regardless of degree of injury) had significantly impaired thrombin-stimulated aggregation compared with platelets treated with plasma from patients without shock (P = 0.002). Conversely, platelets treated with plasma from patients with severe injury, but without shock, had amplified thrombin-stimulated aggregation (P = 0.030).

CONCLUSION

Shock-mediated soluble factors impair platelet aggregation, and tissue injury-mediated soluble factors amplify platelet aggregation. Future characterization of these soluble factors will support development of novel treatments of TIC.

Global metabolic profiling of hemorrhagic shock and resuscitation

Hemorrhagic shock (HS) is a medical emergency during trauma. Significant loss of tissue perfusion may result in cellular hypoxia, organ damage and death. The primary treatment of HS is control of the source of bleeding as soon as possible and fluid replacement (crystalloid solutions and blood transfusion). Metabolomics can identify novel biomarkers for various functional and organic diseases. Therefore, systematic exploration of the biological mechanisms of HS and blood transfusion enables the optimization of treatments for HS to reduce the occurrence of organ damage. In this study, a global metabolic profiling strategy is applied to evaluate metabolic changes in the HS rat model. A serum metabolic network with 58 significant metabolites was constructed for HS and resuscitation. Our investigation will offer insights into the pathogenesis.

Decreased Physiological Serum Total Bile Acid Concentrations in Patients with Type 2 Diabetic Peripheral Neuropathy

PURPOSE

Bile acids, amphipathic cholesterol metabolites, have been reported to have cytoprotective and neuroprotective effects in humans and animal models. The relationship of physiological serum total bile acid (TBA) levels with diabetic peripheral neuropathy (DPN), however, has not been determined. The purpose of this study was to investigate the relationship between physiological serum TBA and DPN.

PATIENTS AND METHODS

In total, 856 patients with type 2 diabetes mellitus (T2DM) aged 20-89 years were enrolled in this cross-sectional study. Serum TBA was measured, and its relationship with DPN and other parameters was analyzed.

RESULTS

T2DM patients with DPN had significantly lower serum TBA compared with those without (P<0.01). Serum TBA was negatively associated with glycated hemoglobin A1C, plateletcrit, fibrinogen, urine albumin-to-creatinine ratio, vibration perception thresholds, and prevalence of DPN, peripheral arterial disease, and diabetic foot ulceration after adjustment for age, sex, and body mass index (P<0.01 or P<0.05). A graded association with prevalence of DPN and increase in serum TBA quartiles was observed (P for trend <0.01), and there was an 48.2% decreased risk of DPN in the highest quartile of serum TBA versus the lowest quartile (95% CI 0.299-0.617; P=0.000) after multivariate adjustment. Receiver-operating characteristic analysis revealed that the optimal cutoff point of serum TBA to indicate DPN was 2.85 μmol/L (sensitivity 77.6% and specificity 45.6%).

CONCLUSION

These findings suggest that lower physiological serum TBA level may be associated with the prevalence of DPN in T2DM patients and may be a potential biomarker for DPN.

Metabolic characterization of plasma and cyst fluid from cystic precursors to pancreatic cancer patients reveal metabolic signatures of bacterial infection

Pancreatic cancer is the seventh leading cause of cancer-related death worldwide, with a 5-year survival rate as low as 9%. One factor complicating the management of pancreatic cancer is the lack of reliable tools for early diagnosis. While up to 50% of the adult population has been shown to develop precancerous pancreatic cysts, limited and insufficient approaches are currently available to determine whether a cyst is going to progress into pancreatic cancer. Recently, we used metabolomics approaches to identify candidate markers of disease progression in patients diagnosed with intraductal papillary mucinous neoplasms (IPMNs) undergoing pancreatic resection. Here we enrolled an independent cohort to verify the candidate markers from our previous study with orthogonal quantitative methods in plasma and cyst fluid from serous cystic neoplasm and IPMN (either low- or high-grade dysplasia or pancreatic ductal adenocarcinoma). We thus validated these markers with absolute quantitative methods through the auxilium of stable isotope-labelled internal standards in a new independent cohort. Finally, we identified novel markers of IPMN status and disease progression - including amino acids, carboxylic acids, conjugated bile acids, free and carnitine-conjugated fatty acids, purine oxidation products and TMAO. We show that the levels of these metabolites of potential bacterial origin correlated with the degree of bacterial enrichment in the cyst, as determined by 16S RNA. Overall, our findings are interesting per se, owing to the validation of previous markers and identification of novel small molecule signatures of IPMN and disease progression. In addition, our findings further fuel the provoking debate as to whether bacterial infections may represent an etiological contributor to the development and severity of the disease in pancreatic cancer, in like fashion to other cancers (e.g., Helicobacter pylori and gastric cancer).

KEY POINTS

We identified and quantified novel markers of IPMN cyst status and pancreatic cancer disease progression - including amino acids, carboxylic acids, conjugated bile acids, free and carnitine-conjugated fatty acids, purine oxidation products and TMAO.We show that the levels of these metabolites of potential bacterial origin correlated with the degree of bacterial enrichment in the cyst, as determined by 16S RNA.

Selective organ ischaemia/reperfusion identifies liver as the key driver of the post-injury plasma metabolome derangements

BACKGROUND

Understanding the molecular mechanisms in perturbation of the metabolome following ischaemia and reperfusion is critical in developing novel therapeutic strategies to prevent the sequelae of post-injury shock. While the metabolic substrates fueling these alterations have been defined, the relative contribution of specific organs to the systemic metabolic reprogramming secondary to ischaemic or haemorrhagic hypoxia remains unclear.

MATERIALS AND METHODS

A porcine model of selected organ ischaemia was employed to investigate the relative contribution of liver, kidney, spleen and small bowel ischaemia/reperfusion to the plasma metabolic phenotype, as gleaned through ultra-high performance liquid chromatography-mass spectrometry-based metabolomics.

RESULTS

Liver ischaemia/reperfusion promotes glycaemia, with increases in circulating carboxylic acid anions and purine oxidation metabolites, suggesting that this organ is the dominant contributor to the accumulation of these metabolites in response to ischaemic hypoxia. Succinate, in particular, accumulates selectively in response to the hepatic ischemia, with levels 6.5 times spleen, 8.2 times small bowel, and 6 times renal levels. Similar trends, but lower fold-change increase in comparison to baseline values, were observed upon ischaemia/reperfusion of kidney, spleen and small bowel.

DISCUSSION

These observations suggest that the liver may play a critical role in mediating the accumulation of the same metabolites in response to haemorrhagic hypoxia, especially with respect to succinate, a metabolite that has been increasingly implicated in the coagulopathy and pro-inflammatory sequelae of ischaemic and haemorrhagic shock.

Trauma-induced coagulopathy: The past, present, and future

Trauma remains a leading cause of death worldwide, and most early preventable deaths in both the civilian and military settings are due to uncontrolled hemorrhage, despite paradigm advances in modern trauma care. Combined tissue injury and shock result in hemostatic failure, which has been identified as a multidimensional molecular, physiologic and clinical disorder termed trauma-induced coagulopathy (TIC). Understanding the biology of TIC is of utmost importance, as it is often responsible for uncontrolled bleeding, organ failure, thromboembolic complications, and death. Investigations have shown that TIC is characterized by multiple phenotypes of impaired hemostasis due to altered biology in clot formation and breakdown. These coagulopathies are attributable to tissue injury and shock, and encompass underlying endothelial, immune and inflammatory perturbations. Despite the recognition and identification of multiple mechanisms and mediators of TIC, and the development of targeted treatments, the mortality rates and associated morbidities due to hemorrhage after injury remain high. The purpose of this review is to examine the past and present understanding of the multiple distinct but highly integrated pathways implicated in TIC, in order to highlight the current knowledge gaps and future needs in this evolving field, with the aim of reducing morbidity and mortality after injury.

Increase in post-reperfusion sensitivity to tissue plasminogen activator-mediated fibrinolysis during liver transplantation is associated with abnormal metabolic changes and increased blood product utilisation

BACKGROUND

Increased systemic fibrinolytic activity can occur in liver transplant recipients after the donor graft is reperfused. However, it remains unclear whether this is related solely to tissue plasminogen activator (t-PA) levels or whether unique metabolic changes can alter t-PA activity and enhance fibrinolytic activity. We hypothesise that an increase in sensitivity to t-PA-mediated fibrinolysis (StF) following liver reperfusion is associated with specific metabolic abnormalities.

MATERIALS AND METHODS

Liver transplant recipients had serial blood samples analysed with a modified thrombelastography assay using exogenous t-PA to measure sensitivity/resistance to fibrinolysis with the lysis 30 min after maximum clot strength (tLY30). Paired plasma samples were analysed with mass spectroscopy-based metabolomics. The tLY30 was correlated to metabolites using Spearman's rho. StF was defined as a tLY30 change of >8.5% from the anhepatic phase to 30 min after reperfusion based on the distribution of tLY30 in a healthy control population.

RESULTS

StF occurred in 53% of patients. Cohorts had similar MELD scores (18 vs 16, p=0.876) and tLY30 at baseline (p=0.867) and anhepatic phase of surgery (p=0.463). Thirty min after reperfusion, the tLY30 was 73% in patient with StF vs 33% in those without StF 33% (p=0.006). StF was associated with increased red blood cell transfusions (p=0.035), during the first 2 hours of reperfusion. Nine metabolites demonstrated a correlation with tLY30 (p<0.05).

DISCUSSION

StF is a transient event that resolves within 2 hours of graft reperfusion and is associated with increased blood product use. This phenomenon correlates with derangements in citric acid cycle, purine and amino acid metabolism. Future research is needed to determine whether these metabolites are biomarkers or mechanistically linked to increased sensitivity to t-PA-mediated fibrinolytic activity following graft reperfusion.

Hemorrhagic shock and tissue injury drive distinct plasma metabolome derangements in swine

BACKGROUND

Tissue injury and hemorrhagic shock induce significant systemic metabolic reprogramming in animal models and critically injured patients. Recent expansions of the classic concepts of metabolomic aberrations in tissue injury and hemorrhage opened the way for novel resuscitative interventions based on the observed abnormal metabolic demands. We hypothesize that metabolic demands and resulting metabolic signatures in pig plasma will vary in response to isolated or combined tissue injury and hemorrhagic shock.

METHODS

A total of 20 pigs underwent either isolated tissue injury, hemorrhagic shock, or combined tissue injury and hemorrhagic shock referenced to a sham protocol (n = 5/group). Plasma samples were analyzed by UHPLC-MS.

RESULTS

Hemorrhagic shock promoted a hypermetabolic state. Tissue injury alone dampened metabolic responses in comparison to sham and hemorrhagic shock, and attenuated the hypermetabolic state triggered by shock with respect to energy metabolism (glycolysis, glutaminolysis, and Krebs cycle). Tissue injury and hemorrhagic shock had a more pronounced effect on nitrogen metabolism (arginine, polyamines, and purine metabolism) than hemorrhagic shock alone.

CONCLUSION

Isolated or combined tissue injury and hemorrhagic shock result in distinct plasma metabolic signatures. These findings indicate that optimized resuscitative interventions in critically ill patients are possible based on identifying the severity of tissue injury and hemorrhage.

Red blood cells in hemorrhagic shock: a critical role for glutaminolysis in fueling alanine transamination in rats

Red blood cells (RBCs) are the most abundant host cell in the human body and play a critical role in oxygen transport and systemic metabolic homeostasis. Hypoxic metabolic reprogramming of RBCs in response to high-altitude hypoxia or anaerobic storage in the blood bank has been extensively described. However, little is known about the RBC metabolism following hemorrhagic shock (HS), the most common preventable cause of death in trauma, the global leading cause of total life-years lost. Metabolomics analyses were performed through ultra-high pressure liquid chromatography-mass spectrometry on RBCs from Sprague-Dawley rats undergoing HS (mean arterial pressure [MAP], <30 mm Hg) in comparison with sham rats (MAP, >80 mm Hg). Steady-state measurements were accompanied by metabolic flux analysis upon tracing of in vivo-injected ¹³C¹⁵N-glutamine or inhibition of glutaminolysis using the anticancer drug CB-839. RBC metabolic phenotypes recapitulated the systemic metabolic reprogramming observed in plasma from the same rodent model. Results indicate that shock RBCs rely on glutamine to fuel glutathione (GSH) synthesis and pyruvate transamination, whereas abrogation of glutaminolysis conferred early mortality and exacerbated lactic acidosis and systemic accumulation of succinate, a predictor of mortality in the military and civilian critically ill populations. Glutamine is here identified as an essential amine group donor in HS RBCs, plasma, liver, and lungs, providing additional rationale for the central role glutaminolysis plays in metabolic reprogramming and survival following severe hemorrhage.

Rationale for the selective administration of tranexamic acid to inhibit fibrinolysis in the severely injured patient

Postinjury fibrinolysis can manifest as three distinguishable phenotypes: 1) hyperfibrinolysis, 2) physiologic, and 3) hypofibrinolysis (shutdown). Hyperfibrinolysis is associated with uncontrolled bleeding due to clot dissolution; whereas, fibrinolysis shutdown is associated with organ dysfunction due to microvascular occlusion. The incidence of fibrinolysis phenotypes at hospital arrival in severely injured patients is: 1) hyperfibrinolysis 18%, physiologic 18%, and shutdown 64%. The mechanisms responsible for dysregulated fibrinolysis following injury remain uncertain. Animal work suggests hypoperfusion promotes fibrinolysis, while tissue injury inhibits fibrinolysis. Clinical experience is consistent with these observations. The predominant mediator of postinjury hyperfibrinolysis appears to be tissue plasminogen activator (tPA) released from ischemic endothelium. The effects of tPA are accentuated by impaired hepatic clearance. Fibrinolysis shutdown, on the other hand, may occur from inhibition of circulating tPA, enhanced clot strength impairing the binding of tPA and plasminogen to fibrin, or the inhibition of plasmin. Plasminogen activator inhibitor -1 (PAI-1) binding of circulating tPA appears to be a major mechanism for postinjury shutdown. The sources of PAI-1 include endothelium, platelets, and organ parenchyma. The laboratory identification of fibrinolysis phenotype, at this moment, is best determined with viscoelastic hemostatic assays (TEG, ROTEM). While D-dimer and plasmin antiplasmin (PAP) levels corroborate fibrinolysis, they do not provide real-time assessment of the circulating blood capacity. Our clinical studies indicate that fibrinolysis is a very dynamic process and our experimental work suggests plasma first resuscitation reverses hyperfibrinolysis. Collectively, we believe recent clinical and experimental work suggest antifibrinolytic therapy should be employed selectively in the acutely injured patient, and optimally guided by TEG or ROTEM.

Farnesoid X Receptor and Its Ligands Inhibit the Function of Platelets

OBJECTIVE

Although initially seemingly paradoxical because of the lack of nucleus, platelets possess many transcription factors that regulate their function through DNA-independent mechanisms. These include the farnesoid X receptor (FXR), a member of the superfamily of ligand-activated transcription factors, that has been identified as a bile acid receptor. In this study, we show that FXR is present in human platelets and FXR ligands, GW4064 and 6α-ethyl-chenodeoxycholic acid, modulate platelet activation nongenomically.

APPROACH AND RESULTS

FXR ligands inhibited the activation of platelets in response to stimulation of collagen or thrombin receptors, resulting in diminished intracellular calcium mobilization, secretion, fibrinogen binding, and aggregation. Exposure to FXR ligands also reduced integrin α_IIbβ₃ outside-in signaling and thereby reduced the ability of platelets to spread and to stimulate clot retraction. FXR function in platelets was found to be associated with the modulation of cyclic guanosine monophosphate levels in platelets and associated downstream inhibitory signaling. Platelets from FXR-deficient mice were refractory to the actions of FXR agonists on platelet function and cyclic nucleotide signaling, firmly linking the nongenomic actions of these ligands to the FXR.

CONCLUSIONS

This study provides support for the ability of FXR ligands to modulate platelet activation. The atheroprotective effects of GW4064, with its novel antiplatelet effects, indicate FXR as a potential target for the prevention of atherothrombotic disease.

Acute Fibrinolysis Shutdown after Injury Occurs Frequently and Increases Mortality: A Multicenter Evaluation of 2,540 Severely Injured Patients

BACKGROUND

Fibrinolysis is a physiologic process that maintains microvascular patency by breaking down excessive fibrin clot. Hyperfibrinolysis is associated with a doubling of mortality. Fibrinolysis shutdown, an acute impairment of fibrinolysis, has been recognized as a risk factor for increased mortality. The purpose of this study was to assess the incidence and outcomes of fibrinolysis phenotypes in 2 urban trauma centers.

STUDY DESIGN

Injured patients included in the analysis were admitted between 2010 and 2013, were 18 years of age or older, and had an Injury Severity Score (ISS) > 15. Admission fibrinolysis phenotypes were determined by the clot lysis at 30 minutes (LY30): shutdown ≤ 0.8%, physiologic 0.9% to 2.9%, and hyperfibrinolysis ≥ 3%. Logistic regression was used to adjust for age, arrival blood pressure, ISS, mechanism, and facility.

RESULTS

There were 2,540 patients who met inclusion criteria. Median age was 39 years (interquartile range [IQR] 26 to 55 years) and median ISS was 25 (IQR 20 to 33), with a mortality rate of 21%. Fibrinolysis shutdown was the most common phenotype (46%) followed by physiologic (36%) and hyperfibrinolysis (18%). Hyperfibrinolysis was associated with the highest death rate (34%), followed by shutdown (22%), and physiologic (14%, p < 0.001). The risk of mortality remained increased for hyperfibrinolysis (odds ratio [OR] 3.3, 95% CI 2.4 to 4.6, p < 0.0001) and shutdown (OR 1.6, 95% CI 1.3 to 2.1, p = 0.0003) compared with physiologic when adjusting for age, ISS, mechanism, head injury, and blood pressure (area under the receiver operating characteristics curve 0.82, 95% CI 0.80 to 0.84).

CONCLUSIONS

Fibrinolysis shutdown is the most common phenotype on admission and is associated with increased mortality. These data provide additional evidence of distinct phenotypes of coagulation impairment and that individualized hemostatic therapy may be required.

Viscoelastic measurements of platelet function, not fibrinogen function, predicts sensitivity to tissue-type plasminogen activator in trauma patients

BACKGROUND

Systemic hyperfibrinolysis is a lethal phenotype of trauma-induced coagulopathy. Its pathogenesis is poorly understood. Recent studies have support a central role of platelets in hemostasis and in fibrinolysis regulation, implying that platelet impairment is integral to the development of postinjury systemic hyperfibrinolysis.

OBJECTIVE

The objective of this study was to identify if platelet function is associated with blood clot sensitivity to fibrinolysis. We hypothesize that platelet impairment of the ADP pathway correlates with fibrinolysis sensitivity in trauma patients.

METHODS

A prospective observational study of patients meeting the criteria for the highest level of activation at an urban trauma center was performed. Viscoelastic parameters associated with platelet function (maximum amplitude [MA]) were measured with native thrombelastography (TEG), and TEG platelet mapping of the ADP pathway (ADP-MA). The contribution of fibrinogen to clotting was measured with TEG (angle) and the TEG functional fibrinogen (FF) assay (FF-MA). Another TEG assay containing tissue-type plasminogen activator (t-PA) (75 ng mL(-1) ) was used to assess clot sensitivity to an exogenous fibrinolytic stimulus by use of the TEG lysis at 30 min (LY30) variable. Multivariate linear regression was used to identify which TEG variable correlated with t-PA-LY30 (quantification of fibrinolysis sensitivity).

RESULTS

Fifty-eight trauma patients were included in the analysis, with a median injury severity score of 17 and a base deficit of 6 mEq L(-1) . TEG parameters that significantly predicted t-PA-LY30 were related to platelet function (ADP-MA, P = 0.001; MA, P < 0.001) but not to fibrinogen (FF-MA, P = 0.773; angle, P = 0.083). Clinical predictors of platelet ADP impairment included calcium level (P = 0.001), base deficit (P = 0.001), and injury severity (P = 0.001).

RESULTS AND CONCLUSIONS

Platelet impairment of the ADP pathway is associated with increased sensitivity to t-PA. ADP pathway inhibition in platelets may be an early step in the pathogenesis of systemic hyperfibrinolysis.