Increased plasma levels of soluble thrombomodulin in patients with sepsis and organ failure

Value of Serum Thrombomodulin as a Marker and Predictor in Patients with Sepsis-Associated Acute Kidney Injury

Objective

To investigate the serum soluble thrombomodulin (sTM) concentration in patients with sepsis-associated acute kidney injury (AKI) and to determine the value of sTM in predicting AKI and mortality in sepsis patients.

Methods

This prospective observational study was conducted on 71 patients diagnosed with sepsis according to Sepsis 3 at the Intensive Care Unit, Hue Central Hospital, Vietnam, from September 2021 to February 2023.

Results

Among 71 sepsis patients, there were 38 (53.5%) AKI cases, including 16 (22.5%) cases of stage 1 AKI, 14 (19.7%) cases of stage 2 AKI, 8 (11.3%) cases of stage 3 AKI, 16 (22.5%) cases of renal replacement therapy, 28 (39.4%) cases of septic shock, and 21 (29.6%) cases of mortality within 28 days. The concentrations of lactate and IL-6 in the AKI and mortality groups were statistically significantly greater than those in the non-AKI and survival groups (p < 0.05). The serum sTM concentration was 4.33 ng/mL, the serum sTM level in the AKI group was statistically significantly higher than that in the non-AKI group (sTM [4.71 vs 2.54 ng/mL, p < 0.001]), and the serum sTM level in the mortality group was statistically significantly higher than the survival group (sTM [4.78 vs 3.87 ng/mL, p < 0.001]). The AUC of sTM for predicting AKI was 0.864; the AUCs of sTM, IL-6, SOFA, and APACHE II for predicting mortality were 0.811, 0.671, 0.816, and 0.705, respectively.

Conclusion

AKI was a prevalent complication among sepsis patients at the ICU. In the AKI and mortality groups, sTM concentration was statistically significantly higher than that in the non-AKI and survival groups. sTM was the predictor of acute kidney injury and mortality in patients with sepsis.

Serum Thrombomodulin Level Can Predict Mortality in Patients With Sepsis?

Background

Thrombomodulin (TM) is a type-1 trans-membrane glycoprotein on endothelial cells which is known to be involved in various biochemical pathways. TM can be detected in biological fluids such as blood and urine under many forms. Soluble thrombomodulin (sTM), consist of various particles of TM, is the predominant agent which is created by enzymatic or chemical catalysis of the whole protein under divergent conditions. TM plays a vital role in protein C system and is crucial in the pathogenesis of Sepsis.

Objective

To identify the serum level of soluble thrombomodulin (sTM) in groups of patients: sepsis and septic shock including their survival and fatal in-hospital outcome; and validate the death prediction of serum sTM in patients with sepsis.

Methods

This prospective observational study was conducted in 63 patients who were diagnosed with sepsis, septic shock according to Sepsis 3 criteria at the ICU Department of Hue Central Hospital, Vietnam, from 3/2022 to 3/2023.

Results

Twenty participants developed septic shock (31.7%), morality within 28-days was 19 patients (30.2%), 22 patients complicated with acute kidney injury that necessitated renal replacement therapy (34.9%), 30 patients required mechanical ventilation (47.6%), the median length of ICU stay was 8 (3-28) days. Serum level of lactate and creatinine were significantly higher in septic shock group compared with sepsis and survival group (p<0.05). The median sTM level in septic shock group and fatal group were 4.68(3.38-6.46) ng/mL and 4.68 (1.69-6.46) ng/mL, respectively. These results were significantly higher than sepsis group [3.62 (1.51-1.94) ng/mL] and survival group [3.73 (1.51-5.9) ng/mL] (p<0.05). The death predictive power of DIC score, APACHE II score, creatinine, sTM and SOFA presented with AUC values of 0.723, 0.726, 0.777, 0.803 and 0.807, respectively. There were no significant difference of serum level IL-6 and PCT between survival and fatal group. The median DIC score in fatal group was 7 (3-7), which was significantly higher than survival group 4 (2-7) (p= 0.001).

Conclusion

Sepsis is a common diagnosis among ICU settings which links the critically ill patients to higher complications and mortalities. Serum level of sTM in septic shock and fatal groups were significantly higher than sepsis and survival groups. sTM is a reliable marker and should be used in predict severity and mortality in sepsis patients.

Circulating Thrombomodulin: Release Mechanisms, Measurements, and Levels in Diseases and Medical Procedures

Thrombomodulin (TM) is a type-I transmembrane protein that is mainly expressed on endothelial cells and plays important roles in many biological processes. Circulating TM of different forms are also present in biofluids, such as blood and urine. Soluble TM (sTM), comprised of several domains of TM, is the major circulating TM which is generated by either enzymatic or chemical cleavage of the intact protein under different conditions. Under normal conditions, sTM is present in low concentrations (<10 ng/mL) in the blood but is elevated in several pathological conditions associated with endothelial dysfunction such as cardiovascular, inflammatory, infection, and metabolic diseases. Therefore, sTM level has been examined for monitoring disease development, such as disseminated intravascular coagulation (DIC), sepsis and multiple organ dysfunction syndrome in patients with novel coronavirus disease 2019 (COVID-19) recently. In addition, microvesicles (MVs) that contain membrane TM (MV-TM) have been found to be released from activated cells which also contribute to levels of circulating TM in certain diseases. Several release mechanisms of sTM and MV-TM have been reported, including enzymatic, chemical, and TM mutation mechanisms. Measurements of sTM and MV-TM have been developed and explored as biomarkers in many diseases. In this review, we summarize all these advances in three categories as follows: (1) release mechanisms of circulating TM, (2) methods for measuring circulating TM in biological samples, and (3) correlation of circulating TM with diseases. Altogether, it provides a whole picture of recent advances on circulating TM in health and disease.

Recombinant thrombomodulin domain 1 rescues pathological angiogenesis by inhibition of HIF-1α-VEGF pathway

Pathological angiogenesis (PA) contributes to various ocular diseases, including age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity, which are major causes of blindness over the world. Current treatments focus on anti-vascular endothelial growth factor (VEGF) therapy, but persistent avascular retina, recurrent intravitreal neovascularization, and general adverse effects are reported. We have previously found that recombinant thrombomodulin domain 1 (rTMD1) can suppress vascular inflammation. However, the function of rTMD1 in VEGF-induced PA remains unknown. In this study, we found that rTMD1 inhibited VEGF-induced angiogenesis in vitro. In an oxygen induced retinopathy (OIR) animal model, rTMD1 treatment significantly decreased retinal neovascularization but spared normal physiological vessel growth. Furthermore, loss of TMD1 significantly promoted PA in OIR. Meanwhile, hypoxia-inducible factor-1α, the transcription factor that upregulates VEGF, was suppressed after rTMD1 treatment. The levels of interleukin-6, and intercellular adhesion molecule-1 were also significantly suppressed. In conclusion, our results indicate that rTMD1 not only has dual effects to suppress PA and inflammation in OIR, but also can be a potential HIF-1α inhibitor for clinical use. These data bring forth the possibility of rTMD1 as a novel therapeutic agent for PA.

Value of Thrombomodulin as a Marker for Sepsis in Critically Ill Children

OBJECTIVE

Pediatric sepsis is altered organ function in critically ill children and a main etiology of mortality for children. Therefore, the authors aimed to assess the role of serum thrombomodulin as valuable biomarker in the diagnosis and prognosis of sepsis in acutely ill pediatrics in the intensive unit.

METHODS

This prospective clinical study conducted on 140 acutely ill patients admitted to the Pediatric Intensive Care Unit (PICU) of Menoufia University Hospital and 50 apparently healthy controls from October 2018 through September 2019. All included children were subjected to clinical examination and the Pediatric Risk of Mortality (PRISM) and Pediatric Index of Mortality II (PIM II) scores were calculated. Serum thrombomodulin was measured for both patients and the control group upon admission. The children were followed for a period of 30 d.

RESULTS

Serum thrombomodulin level was increased among all the patients and those with systemic inflammatory response syndrome (SIRS), sepsis and severe sepsis compared with controls (p < 0.001). Furthermore, serum thrombomodulin was higher in patients who died than who survived (p = 0.005). Thrombomodulin had area under Receiver Operating Characteristic Curve (AUC) =0.915 for predicting sepsis, whereas C-reactive protein had AUC = 0.789. According to the prognosis, thrombomodulin had AUC = 0.711 for predicting mortality whereas PRISM and PIM scores had AUC = (0.918, 0.960) respectively.

CONCLUSIONS

Serum thrombomodulin is a promising marker for pediatric sepsis. The data showed that serum thrombomodulin had a valuable role in diagnosis of sepsis early in critically ill pediatrics.

Discriminatory plasma biomarkers predict specific clinical phenotypes of necrotizing soft-tissue infections

BACKGROUNDNecrotizing soft-tissue infections (NSTIs) are rapidly progressing infections frequently complicated by septic shock and associated with high mortality. Early diagnosis is critical for patient outcome, but challenging due to vague initial symptoms. Here, we identified predictive biomarkers for NSTI clinical phenotypes and outcomes using a prospective multicenter NSTI patient cohort.METHODSLuminex multiplex assays were used to assess 36 soluble factors in plasma from NSTI patients with positive microbiological cultures (n = 251 and n = 60 in the discovery and validation cohorts, respectively). Control groups for comparative analyses included surgical controls (n = 20), non-NSTI controls (i.e., suspected NSTI with no necrosis detected upon exploratory surgery, n = 20), and sepsis patients (n = 24).RESULTSThrombomodulin was identified as a unique biomarker for detection of NSTI (AUC, 0.95). A distinct profile discriminating mono- (type II) versus polymicrobial (type I) NSTI types was identified based on differential expression of IL-2, IL-10, IL-22, CXCL10, Fas-ligand, and MMP9 (AUC >0.7). While each NSTI type displayed a distinct array of biomarkers predicting septic shock, granulocyte CSF (G-CSF), S100A8, and IL-6 were shared by both types (AUC >0.78). Finally, differential connectivity analysis revealed distinctive networks associated with specific clinical phenotypes.CONCLUSIONSThis study identifies predictive biomarkers for NSTI clinical phenotypes of potential value for diagnostic, prognostic, and therapeutic approaches in NSTIs.TRIAL REGISTRATIONClinicalTrials.gov NCT01790698.FUNDINGCenter for Innovative Medicine (CIMED); Region Stockholm; Swedish Research Council; European Union; Vinnova; Innovation Fund Denmark; Research Council of Norway; Netherlands Organisation for Health Research and Development; DLR Federal Ministry of Education and Research; and Swedish Children's Cancer Foundation.

Platelet and Red Blood Cell Transfusions and Risk of Acute Graft-versus-Host Disease after Myeloablative Allogeneic Hematopoietic Cell Transplantation

Transfusion therapy is a critical part of supportive care early after allogeneic hematopoietic cell transplantation (allo-HCT). Platelet and RBC transfusions elicit immunomodulatory effects in the recipient, but if this impacts the risk of acute graft-versus-host disease (aGVHD) has only been scarcely investigated. We investigated if platelet and RBC transfusions were associated with the development of aGVHD following myeloablative allo-HCT in a cohort of 664 patients who underwent transplantation between 2000 and 2019. Data were further analyzed for the impact of blood donor age and sex and blood product storage time. Exploratory analyses were conducted to assess correlations between transfusion burden and plasma biomarkers of inflammation and endothelial activation and damage. Between day 0 and day +13, each patient received a median of 7 (IQR, 5 to 10) platelet transfusions and 3 (IQR, 2 to 6) RBC transfusions (Spearman's ρ = 0.49). The cumulative sums of platelet and RBC transfusions, respectively, received from day 0 to day +13 were associated with subsequent grade II-IV aGVHD in multivariable landmark Cox models (platelets: adjusted hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.06 to 1.51; RBCs: adjusted HR, 1.41; 95% CI, 1.09 to 1.82; both per 5 units; 184 events). For both platelet and RBC transfusions, we did not find support for a difference in the risk of aGVHD according to age or sex of the blood donor. Transfusion of RBCs with a storage time longer than the median of 8 days was inversely associated with aGVHD (HR per 5 units, 0.54; 95% CI, 0.30 to 0.96); however, when using an RBC storage time of ≥14 days as a cutoff, there was no longer evidence for an association with aGVHD (HR, 1.03 per 5 units; 95% CI, 0.53 to 2.00). For platelets, there was no clear association between storage time and the risk of aGVHD. The transfusion burdens of platelets and RBCs were positively correlated with plasma levels of TNF-α, IL-6, and soluble thrombomodulin at day +14. In conclusion, platelet and RBC transfusions in the first 2 weeks after myeloablative allo-HCT were associated with subsequent development of grade II-IV aGVHD. We did not find evidence of an impact of blood donor age or sex or blood product storage time on the risk of aGVHD. Our findings support restrictive transfusion strategies in allo-HCT recipients.

Protective Effects of Recombinant Human Soluble Thrombomodulin on Lipopolysaccharide-Induced Acute Kidney Injury

Thrombomodulin (TM) is a single transmembrane, multidomain glycoprotein receptor for thrombin, and is best known for its role as a cofactor in a clinically important natural anticoagulant pathway. In addition to its anticoagulant function, TM has well-defined anti-inflammatory properties. Soluble TM levels increase significantly in the plasma of septic patients; however, the possible involvement of recombinant human soluble TM (rTM) transduction in the pathogenesis of lipopolysaccharide (LPS)-induced nephrotoxicity, including acute kidney injury (AKI), has remained unclear. Mice were injected intraperitoneally with 15 mg/kg LPS. rTM (3 mg/kg) or saline was administered to the animals before the 3 and 24 h LPS-injection. At 24 and 48 h, blood urea nitrogen, the inflammatory cytokines in sera and kidney, and histological findings were assessed. Cell activation and apoptosis signal was assessed by Western blot analysis. In this study using a mouse model of LPS-induced AKI, we found that rTM attenuated renal damage by reducing both cytokine and cell activation and apoptosis signals with the accumulation of CD4+ T-cells, CD11c+ cells, and F4/80+ cells via phospho c-Jun activations and Bax expression. These findings suggest that the mechanism underlying these effects of TM may be mediated by a reduction in inflammatory cytokine production in response to LPS. These molecules might thereby provide a new therapeutic strategy in the context of AKI with sepsis.

Thrombomodulin, Plasminogen Activator Inhibitor-1 and Protein C Levels, and Organ Dysfunction in Sepsis

Since endothelial function is closely related to organ dysfunction in sepsis and the relationship among endothelial injury, organ dysfunction, and other biomarkers remains unclear, we aimed to evaluate the correlation among endothelial injury, organ dysfunction, and several biomarkers in patients with sepsis.

Design

This was a retrospective observational study.

Setting

The study was conducted in a university hospital with 14 mixed ICU beds.

Patients

ICU patients with sepsis from June 2011 to December 2017 were enrolled in this study.

Interventions

Endothelial biomarkers (soluble thrombomodulin, plasminogen activator inhibitor-1, and protein C) and markers of inflammation and coagulation were evaluated during the ICU stay. Sequential Organ Failure Assessment scores were assessed for 7 days after ICU admission to determine organ dysfunction. Variables were compared among five stratified groups according to the Sequential Organ Failure Assessment score (0-2, 3-5, 6-8, 9-12, and 13-24). Regression analysis and 95% CIs were used to evaluate trends in biomarkers.

Measurements and Main Results

The patients were divided into five stratified groups (Sequential Organ Failure Assessment 0-2, n = 159 [20.5%]; Sequential Organ Failure Assessment 3-5, n = 296 [38.2%]; Sequential Organ Failure Assessment 6-8, n = 182 [23.5%]; Sequential Organ Failure Assessment 9-12, n = 75 [9.7%]; Sequential Organ Failure Assessment 13-24, n = 31 [4.0%]). Protein C activity was significantly correlated with the severity of organ dysfunction. It was lower on day 1, increased upon successful treatment, and was significantly higher in groups with lower Sequential Organ Failure Assessment scores.

Conclusions

Trends and activity of protein C were superior in predicting organ dysfunction compared with other endothelial biomarkers. Monitoring the level of protein C activity is an ideal tool to monitor organ dysfunctions in patients with sepsis.

Endothelial Damage Signals Refractory Acute Kidney Injury in Critically Ill Patients

Critically ill patients with acute kidney injury (AKI) are heterogeneous on pathophysiology and prognosis. The role of endothelial damage in the pathogenesis of refractory AKI has not been clarified. The aim was to determine if biomarkers of endothelial damage, independently of the inflammatory insult on the kidney, can predict recovery of acute kidney injury.

METHODS

From the "Procalcitonin And Survival Study" multicenter intensive care unit cohort, followed for 28 days after admission, we included patients without chronic kidney disease, who survived >24 h after admission and with plasma samples at admission available for biomarker analysis. We defined AKI by the "Kidney Disease: Improving Global Outcomes" guidelines and recovery of prior kidney function as alive for five consecutive days after admission with no need for renal replacement therapy and creatinine levels consistently below ×1.5 the level before admission. We adjusted models for age, gender, vasopressor treatment, mechanical ventilation and levels of creatinine, procalcitonin, platelets, and bilirubin at admission.

RESULTS

Of a total 213 with AKI at admission, 99 recovered prior kidney function during follow-up. Endothelial damage on admission, measured by Soluble Thrombomodulin (sTM), was the strongest predictor of a reduced chance of recovery of prior kidney function (sTM in the highest vs. three lower quartiles hazard ratio 0.39; 95% confidence interval 0.21-0.73, P = 0.003). In contrast, the degree of the initial inflammatory insult on the kidney, measured by neutrophil gelatinase-associated lipocalin (NGAL), failed to predict this outcome (NGAL in highest vs. three lower quartiles hazard ratio = 1.20; 95% CI 0.72-2.00; P = 0.48). Procalcitonin, a specific marker of bacterial infection, was also associated with the rate of recovery (PCT in highest vs. three lower quartiles hazard ratio = 0.59; 95% CI 0.36-0.98; P = 0.04).

CONCLUSION

AKI patients with high levels of sTM had a reduced chance of recovering prior renal function. Our findings support disintegration of the endothelium as a critical point in the pathogenesis of AKI that is refractory to treatment.

Markers of acute kidney injury in patients with sepsis: the role of soluble thrombomodulin

Background

Endothelial activation and damage occur early during sepsis, with activated coagulopathy and playing a major role in the pathophysiology of sepsis-induced acute kidney injury (AKI). The aim of this study was to compare the various biomarkers of endothelial injury with the biomarkers of coagulation and inflammation and to determine a significant predictor of AKI in patients with sepsis.

Methods

We conducted a single-center, retrospective, observational study on patients with sepsis fulfilling the Third International Consensus Definitions for Sepsis and Septic Shock criteria admitted to an adult intensive care unit (ICU) at a university hospital from June 2011 to December 2016. Levels of 13 biomarkers were measured on ICU admission, including markers of endothelial injury (soluble thrombomodulin [sTM], E-selectin, protein C, and plasminogen activator inhibitor-1 [PAI-1]) and markers of coagulation derangement (platelet count, fibrin degradation product [FDP], prothrombin time [PT], fibrinogen, α₂-plasminogen inhibitor [α₂-PI], antithrombin III [AT III], plasminogen, thrombin-antithrombin complex, and plasmin-α₂-plasmin inhibitor complex). All patients with sepsis were reviewed, and the development of AKI was evaluated. Multivariate logistic regression analysis was performed to identify significant independent predictive factors for AKI.

Results

Of the 514 patients admitted with sepsis, 351 (68.3%) developed AKI. Compared with the non-AKI group, all the endothelial biomarkers were significantly different in the AKI group (sTM [23.6 vs. 15.6 U/ml, P < 0.0001], E-selectin [65.5 vs. 46.2 ng/ml, P = 0.0497], PAI-1 [180.4 vs. 75.3 ng/ml, P = 0.018], and protein C [45.9 vs. 58.7 ng/ml, P < 0.0001]). Biomarkers of coagulopathy and inflammation, platelet counts, FDP, PT, α₂-PI, AT III, plasminogen, and C-reactive protein were significantly different between the two groups. Multivariable logistic regression analysis showed that sTM was an independent predictive factor of AKI, with an AUROC of 0.758 (P < 0.0001).

Conclusions

Endothelial biomarkers were significantly changed in the sepsis patients with AKI. Particularly, sTM was an independent predictive biomarker for the development of AKI that outperformed other coagulation and inflammation biomarkers as well as organ function in patients with sepsis.

Increased serum thrombomodulin level is associated with disease severity and mortality in pediatric sepsis

Background

Endothelial dysfunction plays an important role in the pathophysiology of sepsis. As previously reported, the serum thrombomodulin is elevated in diseases associated with endothelial injury.

Objective

The aim of this study was to investigate the association of serum thrombomodulin level in different pediatric sepsis syndromes and evaluate the relationship with disease severity and mortality.

Methods

We prospectively collected cases of sepsis treated in a pediatric intensive care unit from June 2012 to July 2015 at Chang Gung Children’s Hospital in Taoyuan, Taiwan. Clinical characteristics and serum thrombomodulin levels were analyzed.

Results

Increased serum thrombomodulin levels on days 1 and 3 of the diagnosis of sepsis were found in different pediatric sepsis syndromes. Patients with septic shock had significantly increased serum thrombomodulin levels on days 1 and 3 [day 1: median, 6.9 mU/ml (interquartile range (IQR): 5.8–12.8) and day 3: median, 5.8 mU/ml (IQR: 4.6–10.8)] compared to healthy controls [median, 3.4 mU/ml (IQR: 2.3–4.2)] (p = <0.001 and 0.001, respectively) and those with sepsis [day 1: median, 2.9 mU/ml (IQR: 1.8–4.7) and day 3: median, 3 mU/ml (IQR: 1.5–3.5)] and severe sepsis [day 1: median, 3.3 mU/ml (IQR: 1.3–8.6) and day 3: median, 4.4 mU/ml (IQR: 0.5–6)] (p = <0.001 and 0.001, respectively). There was also a significant positive correlation between serum thrombomodulin level on day 1 and day 1 PRISM-II, PELOD, P-MOD and DIC scores. The patients who died had significantly higher serum thrombomodulin levels on days 1 and 3 [day 1: median, 9.9 mU/ml (IQR: 6.2–15.6) and day 3: median, 10.4 mU/ml (IQR: 9.2–11.7)] than the survivors [day 1; median, 4.4 mU/ml (IQR: 2.2–7.5) and day 3: [median, 3.5 mU/ml (IQR: 1.6–5.7)] (p = 0.046 and 0.012, respectively).

Conclusion

Increased serum thrombomodulin levels were found in different pediatric sepsis syndromes and correlated with disease severity and mortality.

Carbohydrate-binding protein CLEC14A regulates VEGFR-2- and VEGFR-3-dependent signals during angiogenesis and lymphangiogenesis

Controlled angiogenesis and lymphangiogenesis are essential for tissue development, function, and repair. However, aberrant neovascularization is an essential pathogenic mechanism in many human diseases, including diseases involving tumor growth and survival. Here, we have demonstrated that mice deficient in C-type lectin family 14 member A (CLEC14A) display enhanced angiogenic sprouting and hemorrhage as well as enlarged jugular lymph sacs and lymphatic vessels. CLEC14A formed a complex with VEGFR-3 in endothelial cells (ECs), and CLEC14A KO resulted in a marked reduction in VEGFR-3 that was concomitant with increases in VEGFR-2 expression and downstream signaling. Implanted tumor growth was profoundly reduced in CLEC14A-KO mice compared with that seen in WT littermates, but tumor-bearing CLEC14A-KO mice died sooner. Tumors in CLEC14A-KO mice had increased numbers of nonfunctional blood vessels and severe hemorrhaging. Blockade of VEGFR-2 signaling suppressed these vascular abnormalities and enhanced the survival of tumor-bearing CLEC14A-KO mice. We conclude that CLEC14A acts in vascular homeostasis by fine-tuning VEGFR-2 and VEGFR-3 signaling in ECs, suggesting its relevance in the pathogenesis of angiogenesis-related human disorders.

Efficacy and Bleeding Risk of Antithrombin Supplementation in Patients With Septic Disseminated Intravascular Coagulation: A Third Survey

INTRODUCTION

Although recent studies have reported the efficacy of antithrombin (AT) supplementation for sepsis-associated disseminated intravascular coagulation (DIC), the factors that influence AT's effect have not been sufficiently studied. The purpose of this survey was to identify factors that modulate the effects and the adverse effects of AT.

METHODS

We performed a multi-institutional survey. The data from 159 patients with septic DIC with AT ≤70% and who had undergone AT supplementation were analyzed. The patients' demographic characteristics, including the infection site, baseline sepsis-related organ failure assessment (SOFA) score, baseline DIC score, and baseline AT activity, were analyzed in relation to the 28-day mortality. Bleeding-related adverse events were also examined.

RESULTS

Overall, 116 patients survived and 43 did not (28-day mortality: 27.0%). A logistic regression analysis revealed that the baseline SOFA score (odds ratio [OR]: 0.816, P = .001), coadministration of recombinant thrombomodulin (rTM; OR: 3.989, P = .006), and respiratory tract infection (OR: 0.129, P = .000) were significantly associated with the survival. Survivors exhibited a higher peak AT activity than nonsurvivors (85.1% vs 65.0%, P = .027). Bleeding events were observed in 4.13% (major bleeding: 1.65%) of the patients, and the coadministration of rTM did not increase the risk of bleeding (with rTM: 4.11% vs without rTM: 4.17%). Heparin was concomitantly used in 22 (18.2%) cases, and its use nonsignificantly increased the bleeding risk (with heparins: 9.09% vs without heparins: 3.03%; P = .224).

CONCLUSION

The coadministration of rTM may improve survival without increasing the risk of bleeding in patients with sepsis-associated DIC treated with AT.

Host response biomarkers in the diagnosis of sepsis: a general overview

Critically ill patients who display a systemic inflammatory response syndrome (SIRS) are prone to develop nosocomial infections. The challenge remains to distinguish as early as possible among SIRS patients those who are developing sepsis. Following a sterile insult, damage-associated molecular patterns (DAMPs) released by damaged tissues and necrotic cells initiate an inflammatory response close to that observed during sepsis. During sepsis, pathogen-associated molecular patterns (PAMPs) trigger the release of host mediators involved in innate immunity and inflammation through identical receptors as DAMPs. In both clinical settings, a compensatory anti-inflammatory response syndrome (CARS) is concomitantly initiated. The exacerbated production of pro- or anti-inflammatory mediators allows their detection in biological fluids and particularly within the bloodstream. Some of these mediators can be used as biomarkers to decipher among the patients those who developed sepsis, and eventually they can be used as prognosis markers. In addition to plasma biomarkers, the analysis of some surface markers on circulating leukocytes or the study of mRNA and miRNA can be helpful. While there is no magic marker, a combination of few biomarkers might offer a high accuracy for diagnosis.

The role of soluble thrombomodulin in the risk stratification and prognosis evaluation of septic patients in the emergency department

INTRODUCTION

Soluble thrombomodulin (sTM) is a sensitive marker of endothelial damage. In this study we investigated the role of sTM in the evaluation of the severity and prognosis of septic patients in the emergency department (ED).

MATERIALS AND METHODS

A prospective, observational cohort study was performed in the ED of an urban, university hospital. Patients who had suspected infection with two or more criteria of systemic inflammatory response syndrome were consecutively enrolled. sTM, D-Dimer and procalcitonin levels were measured on enrollment, and the Mortality in Emergency Department Sepsis (MEDS) score was calculated. A 30-day follow-up was performed for all patients.

RESULTS

A total of 372 patients with sepsis, 210 patients with severe sepsis and 98 patients with septic shock were enrolled in this study. According to the disease severity, patients were divided into sepsis subgroup and severe sepsis subgroup (including septic shock). In addition, patients were divided into survivors subgroup and non-survivors subgroup according to the 30-day mortality. Plasma sTM levels in patients with severe sepsis were higher than those with sepsis (P<0.001). Compared with survivors, non-survivors has higher plasma sTM levels (P<0.001). Multivariate logistic regression analysis showed that sTM was an independent predictor of severe sepsis (odds ratio 1.11) and 30-day mortality (odds ratio 1.059). Receiver operating characteristic curve analysis showed that sTM was a useful parameter in prediction of severe sepsis (0.859) and 30-day mortality (0.78). Compared with the MEDS score alone, combination of sTM and the MEDS score can improve the accuracy in prediction of severe sepsis and 30-day mortality.

CONCLUSIONS

sTM is a valuable biomarker in the risk stratification and prognosis evaluation of ED sepsis. Furthermore, sTM can enhance the ability of the MEDS score in prediction of severe sepsis and 30-day mortality.

Aging exacerbates microvascular endothelial damage induced by circulating factors present in the serum of septic patients

The elderly patients show a significantly elevated mortality rate during sepsis than younger patients, due to their higher propensity to microvascular dysfunction and consequential multiorgan failure. We tested whether aging renders vascular endothelial cells more susceptible to damage induced by inflammatory factors present in the circulation during sepsis. Primary microvascular endothelial cells derived from young (3 months) and aged (24 months) Fischer 344 × Brown Norway rats were treated with sera obtained from sepsis patients and healthy controls. Oxidative stress (MitoSox fluorescence), death receptor activation (caspase 8 activity), and apoptotic cell death (caspase 3 activity) induced by treatment with septic sera were exacerbated in aged endothelial cells as compared with responses obtained in young cells. Induction of heme oxygenase-1 and thrombomodulin in response to treatment with septic sera was impaired in aged endothelial cells. Treatment with septic sera elicited greater increases in tumor necrosis factor-α expression in aged endothelial cells, as compared with young cells, whereas induction of inducible nitric oxide synthase, intercellular adhesion molecule-1, and vascular cell adhesion molecule did not differ between the two groups. Collectively, aging increases sensitivity of microvascular endothelial cells (MVECs) to oxidative stress and cellular damage induced by inflammatory factors present in the circulation during septicemia. We hypothesize that these responses may contribute to the increased vulnerability of elderly patients to multiorgan failure associated with sepsis.

Therapeutic modulation of coagulation and fibrinolysis in acute lung injury and the acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are characterized by excessive intraalveolar fibrin deposition, driven, at least in part by inflammation. The imbalance between activation of coagulation and inhibition of fibrinolysis in patients with ALI/ARDS favors fibrin formation and appears to occur both systemically and in the lung and airspace. Tissue factor (TF), a key mediator of the activation of coagulation in the lung, has been implicated in the pathogenesis of ALI/ARDS. As such, there have been numerous investigations modulating TF activity in a variety of experimental systems in order to develop new therapeutic strategies for ALI/ARDS. This review will summarize current understanding of the role of TF and other proteins of the coagulation cascade as well the fibrinolysis pathway in the development of ALI/ARDS with an emphasis on the pathways that are potential therapeutic targets. These include the TF inhibitor pathway, the protein C pathway, antithrombin, heparin, and modulation of fibrinolysis through plasminogen activator- 1 (PAI-1) or plasminogen activators (PA). Although experimental studies show promising results, clinical trials to date have proven unsuccessful in improving patient outcomes. Modulation of coagulation and fibrinolysis has complex effects on both hemostasis and inflammatory pathways and further studies are needed to develop new treatment strategies for patients with ALI/ARDS.

Monocytic thrombomodulin triggers LPS- and gram-negative bacteria-induced inflammatory response

Sepsis results from the host hyperinflammatory response to bacterial infection, causing multiple organ failure and high mortality. We previously demonstrated that LPS binds to monocytic membrane-bound thrombomodulin (TM), but the role of monocytic TM in LPS-induced inflammation remains unknown. In this study, we demonstrated that TM knockdown in human monocytic cells attenuated LPS-induced signaling pathways and cytokine production. Coimmunoprecipitation and immunofluorescence assays showed that monocytic TM interacted with the LPS receptors, CD14 and TLR4/myeloid differentiation factor-2 (MD-2) complex, indicating that it binds to LPS and triggers an LPS-induced inflammatory response by interacting with the CD14/TLR4/MD-2 complex. We also found that monocytic TM knockdown reduced cytokine production induced by gram-negative bacteria Klebsiella pneumoniae, suggesting that monocytic TM plays an important role in gram-negative bacteria-induced inflammation. To further investigate the function of monocytic TM in vivo, myeloid-specific TM-deficient mice were established and were found to display improved survival that resulted from the attenuation of septic syndrome, including reduced systemic inflammatory response and resistance to bacterial dissemination, after K. pneumoniae infection or cecal ligation and puncture surgery. The inhibition of bacterial dissemination in mice with a deficiency of myeloid TM may be caused by the early increase in neutrophil infiltration. Therefore, we conclude that monocytic TM is a novel component in the CD14/TLR4/MD-2 complex and participates in the LPS- and gram-negative bacteria-induced inflammatory response.

Enhanced induction of heme oxygenase-1 suppresses thrombus formation and affects the protein C system in sepsis

Heme oxygenase-1 (HO-1) displays anti-inflammatory and cytoprotective activities in sepsis. Here, we investigated the effects of HO-1 on thrombus formation and the protein C system in a septic C57BL/6 mouse model induced by cecal ligation and perforation (CLP). Septic mice were either preinjected with the vehicle, pretreated with hemin (an HO-1 inducer) or zinc protoporphyrin IX (ZnPP, an HO-1 inhibitor), or given a combination of hemin + ZnPP. CLP increased significantly the hepatic expression of HO-1; increased thrombosis in livers, kidneys, and lungs; shortened the prothrombin time (PT) and activated partial thromboplastin time (APTT); elevated the levels of tumor necrosis factor-1α (TNF-1α), interleukin-6 (IL-6), and thrombomodulin (TM); reduced the levels of protein C (PC) and activated protein C (aPC); and downregulated hepatic expression of PC and TM. The preadministration of hemin to septic mice increased the expression and activity of HO-1; inhibited thrombosis in the preceding 3 organs; prolonged PT and APTT; inhibited the production of TNF-α and IL-6; upregulated the expression of PC and TM in livers; elevated the plasma levels of PC and aPC; and reduced the plasma levels of TM. In contrast, ZnPP showed opposite effects to hemin and reversed the effects of hemin by inhibiting the activity of HO-1. The administration of tricarbonyl dichloro ruthenium (II) dimer (CORM-2), which is a CO-releasing molecule, had a similar effect to hemin on thrombosis and the protein C system. The data indicate that the enhanced induction of HO-1 inhibits thrombus formation and affects the protein C system in sepsis.

The recombinant lectin-like domain of thrombomodulin inhibits angiogenesis through interaction with Lewis Y antigen

Lewis Y Ag (LeY) is a cell-surface tetrasaccharide that participates in angiogenesis. Recently, we demonstrated that LeY is a specific ligand of the recombinant lectin-like domain of thrombomodulin (TM). However, the biologic function of interaction between LeY and TM in endothelial cells has never been investigated. Therefore, the role of LeY in tube formation and the role of the recombinant lectin-like domain of TM-TM domain 1 (rTMD1)-in antiangiogenesis were investigated. The recombinant TM ectodomain exhibited lower angiogenic activity than did the recombinant TM domains 2 and 3. rTMD1 interacted with soluble LeY and membrane-bound LeY and inhibited soluble LeY-mediated chemotaxis of endothelial cells. LeY was highly expressed on membrane ruffles and protrusions during tube formation on Matrigel. Blockade of LeY with rTMD1 or Ab against LeY inhibited endothelial tube formation in vitro. Epidermal growth factor (EGF) receptor in HUVECs was LeY modified. rTMD1 inhibited EGF receptor signaling, chemotaxis, and tube formation in vitro, and EGF-mediated angiogenesis and tumor angiogenesis in vivo. We concluded that LeY is involved in vascular endothelial tube formation and rTMD1 inhibits angiogenesis via interaction with LeY. Administration of rTMD1 or recombinant adeno-associated virus vector carrying TMD1 could be a promising antiangiogenesis strategy.

Macrophage migration inhibitory factor induces ICAM-1and thrombomobulin expression in vitro

Macrophage migration inhibitory factor (MIF) is an important cytokine in the modulation of inflammatory and immune responses, but its role in coagulation remains to be elucidated. In this study, we investigated the potential role of MIF in coagulation through its influence on two factors, thrombomodulin (TM) and intercellular adhesion molecule-1 (ICAM-1). Recombinant human MIF was added to human microvascular endothelial cell line (HMEC-1) to investigate its influence on the expression of TM and ICAM-1. The results showed that both TM and ICAM-1 were induced with MIF addition in a dose-dependent and time-dependent manner. The expression of ICAM-1 and TM was increased as MIF doses were increased, with the highest expression seen at 12 hr after 400 ng/ml of MIF treatment. Besides, anti-MIF antibody treatment reduced the TM expression in HMEC-1 cells. In conclusion, our data support a role of MIF as an important factor in the regulation of coagulation.

A review of pulmonary coagulopathy in acute lung injury, acute respiratory distress syndrome and pneumonia

Enhanced bronchoalveolar coagulation is a hallmark of many acute inflammatory lung diseases such as acute lung injury, acute respiratory distress syndrome and pneumonia. Intervention with natural anticoagulants in these diseases has therefore become a topic of interest. Recently, new data on the role of pulmonary coagulation and inflammation has become available. The aim of this review is to summarize these findings. Furthermore, the results of anticoagulant therapeutic interventions in these disorders are discussed.

Detection and quantification of thrombomodulin in human semen

The presence of fibrin degradation products, thrombin-like enzyme, prothrombin fragments, thrombin-activatable fibrinolysis inhibitor, plasmin and other active components of blood coagulation and fibrinolysis in seminal plasma has been reported. In the present study we investigate the presence of thrombomodulin in human semen. Using an Imubind thrombomodulin enzyme-linked immunosorbent assay (American Diagnostica Inc., Stamford, Connecticut, USA), seminal thrombomodulin levels were measured in 47 semen specimens obtained from subfertile individuals, normally fertile individuals, semen donors as well as vasectomized individuals, and in a further group defined by normality in several parameters derived from the World Health Organization fertility criteria. Conventional semen parameters were analysed in all semen samples. Thrombomodulin is quantifiable in human semen at a concentration lower than that normally found in citrated blood plasma samples. Slightly higher levels were seen for fertile stratifications compared with infertile individuals but without significant difference, given the numbers accrued. A vasectomized group showed the lowest value. In conclusion, our results establish the presence of thrombomodulin in human semen and suggest its production both upstream and downstream from the level of a vasectomy lesion.

Plasma level of thrombomodulin is an early indication of pancreatic necrosis in patients with acute pancreatitis

BACKGROUND

The potential to predict pancreatic necrosis within the first 48 h by using plasma soluble thrombomodulin (sTM) in 104 patients with acute pancreatitis (AP) was analyzed in a prospective 5-year investigation performed at a single institution.

METHODS

According to Balthazar CT grade, pancreatitis was classified as no necrosis in 72 patients, one-third necrotic in 18 patients, one-half necrotic in 10 patients and more than one-half necrotic in 4 patients. Blood was collected at the first 48 hours after the onset of pain and analyzed for sTM.

RESULTS

In the healthy volunteers, plasma levels of TM were 16.49+/-5.24 microg/L. By comparison, the mean plasma levels of TM in each group of pancreatitis patients were as follows: CT grade A group, 34.21+/-10.73 microg/L; CT grade B group, 36.18+/-12.50 microg/L; CT grade C group, 49.39+/-18.38 microg/L; CT grade D group, 114.46+/-39.44 microg/L; CT grade E group, 100.22+/-15.97 microg/L (p<0.01). And for the patients, the Pearson correlation coefficient between the CT grade and TM values was 0.784 (p<0.01). No necrosis group, 39.22+/-13.75 microg/L; one-third necrotic group, 71.44+/-18.02 microg/L; one-half necrotic group, 123.50+/-28.57 microg/L; more than one-half necrotic group, 129.00+/-33.28 microg/L (p<0.01); And for the patients, the Pearson correlation coefficient between the degree of necrosis and TM values was 0.888 (p<0.01). ROC analysis indicated the area under the ROC curve (AUC +/- SE) for sTM was 0.949+/-0.020, clearly supportive of the high accuracy of this index in predicting the necrosis of AP.

CONCLUSION

Plasma soluble thrombomodulin (sTM) is a potential marker to predict pancreatic necrosis within the first 48 h, and further investigation in a multicentre study is necessary.

Novel role of the human alveolar epithelium in regulating intra-alveolar coagulation

Intra-alveolar fibrin deposition is a common response to localized and diffuse lung infection and acute lung injury (ALI). We hypothesized that the alveolar epithelium modulates intra-alveolar fibrin deposition through activation of protein C. Our objectives [corrected] were to determine whether components of the protein C activation pathway are present in the alveolar compartment in ALI and whether alveolar epithelium is a potential source. In patients with ALI, pulmonary edema fluid levels of endothelial protein C receptor (EPCR) were higher than plasma, suggesting a source in the lung. To determine whether alveolar epithelial cells are a potential source, protein C activation by A549, small airway epithelial, and primary human alveolar epithelial type II cells was measured. All three cell types express thrombomodulin (TM) and EPCR, and activate protein C on the cell surface. Activation of protein C was inhibited by cytomix (TNF-alpha, IL-1beta, and IFN-gamma). Release of EPCR and TM into the conditioned medium was inhibited by the metalloproteinase inhibitors tumor necrosis factor protease inhibitor (TAPI) and GM6001, indicating that the shedding of EPCR and TM from the alveolar epithelium is mediated by a metalloproteinase. These findings provide new evidence that the alveolar epithelium can modulate the protein C pathway and thus could be an important determinant of alveolar fibrin deposition. Local fibrin deposition may be a fundamental mechanism for the lung to localize and confine injury, thus limiting the risk of dissemination of injury or infection to the systemic circulation.

Burn Injury Exacerbates Hemodynamic and Metabolic Responses in Rats with Polymicrobial Sepsis

The most common and life-threatening complication of severe burn injury is infection, which often results in multiple organ failure (MOF). However, the mechanism of development of MOF after burn injury associated with infection is not fully understood. Our previous studies showed that when polymorphonuclear neutrophils (PMNs) are depleted, burn injury-induced increase in microvascular permeability to albumin is markedly attenuated. Thus, we hypothesized that the combination of burn injury and polymicrobial infection exacerbates PMN activation, increases intestinal microvascular permeability to albumin, and alters hemodynamics and metabolism more than burn injury or infection alone. Sprague-Dawley rats (250-275 g) were divided into four groups. In the burn group, rats were subjected to a 30% TBSA burn injury. In the cecal-ligation puncture (CLP) group, CLP was performed using a 22-gauge needle with one puncture. In burn+CLP group, rats were subjected to CLP immediately after burn procedure. In sham group, rats were subjected to sham procedures. Transient polymicrobial bacteremia and persistent polymicrobial bacteremia were induced in the CLP group and burn+CLP group, respectively. Microvascular permeability, myeloperoxidase, and PMN production of elastase and reactive oxygen species increased in the burn group and CLP group and further increased in the burn+CLP group. Hemodunamic and metabolic alterations on day 1 and 3 after injury correlated with those alterations. Although there was only a low mortality in the burn group and CLP group, there was a high mortality in burn+CLP group (79%). The mechanism of MOF that leads to high mortality in burn injury complicated by infection may involve uncontrolled microvascular damage mediated by PMN activation.

Digest

This month's selection from the July to September 1995 issues of Surgery Today (The Japanese Journal of Surgery) is written by Professor K. Sugimachi. A digest of the BJS for the same period, written by Mr Colin Johnson, appears in the Japanese journal.

Association between the severity of sepsis and the changes in hemostatic molecular markers and vascular endothelial damage markers

It is well known that disorders of coagulation and fibrinolysis play a major role in the development of organ dysfunction during sepsis. Furthermore, the importance of the early initiation of anticoagulation therapy for severe cases has been emphasized based on the success of recent clinical trials. The purpose of this study is to search for useful markers for predicting organ dysfunction. Plasma samples were prospectively collected from 78 patients within 48 h after the onset of sepsis. Hemostatic markers and endothelial damage markers were compared between the patients with and without organ dysfunction. The WBC and platelet counts were not different between the groups. In contrast, fibrin/fibrinogen degradation products, D-dimer, thrombin-antithrombin complex, plasmin alpha2-antiplasmin complex, soluble fibrin, and total plasminogen activator inhibitor-1 were significantly higher, and the antithrombin activity and protein C levels were lower in the patients with organ dysfunction. Thus, the changes in the hemostatic molecular markers were associated with organ dysfunction from an early stage of sepsis, and antithrombin and protein C activities were found to be the most reliable markers.

Coagulation and fibrinolysis in human acute lung injury-New therapeutic targets?

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common, life-threatening causes of acute respiratory failure that arise from a variety of local and systemic insults. The need for new specific therapies has led a number of investigators to examine the role of altered coagulation and fibrinolysis in the pathogenesis of ALI/ARDS. This review summarizes our current understanding of coagulation and fibrinolysis in human ALI/ARDS with an emphasis on pathways that could be potential therapeutic targets including the tissue factor pathway, the protein C pathway and modulation of fibrinolysis via plasminogen activator inhibitor-1. The available data suggest that clinical ALI and ARDS are characterized by profound alterations in both systemic and intra-alveolar coagulation and fibrinolysis. Fibrin deposition in the airspaces and lung microvasculature likely results from both activation of the coagulation cascade and impaired fibrinolysis, triggered by inflammation. Modulation of fibrin deposition in the lung through targeting activation and modulation of coagulation as well as fibrinolysis may be an important therapeutic target in clinical ALI/ARDS that deserves further exploration.

Leukocyte and endothelial cell interactions in sepsis: relevance of the protein C pathway

OBJECTIVE

To give an overview of leukocyte and endothelial cell interactions in sepsis and to explore the role of the protein C pathway in modulating the innate immune response via its anti-inflammatory properties.

DATA SOURCE

Novel in vitro data and a MEDLINE search for the terms "activated protein C," "recombinant human activated protein C," "inflammation," "leukocyte adhesion," and "sepsis" were used, along with clinical trial databases from the PROWESS trial and a phase I human endotoxin trial evaluating recombinant human activated protein C (drotrecogin alfa [activated]).

DATA EXTRACTION AND SYNTHESIS

The protein C pathway is positioned at the interface between the endothelium and the leukocyte response of the innate immune system. Activated protein C (APC) possesses profibrinolytic, anti-inflammatory, and anti-apoptotic properties, acting as an endothelial cell and microvascular modulator in opposition to thrombin and the proinflammatory cytokines. Distribution of the receptor for APC, endothelial protein C receptor, was detected on effector cells of the innate immune response. This suggests a further role for the protein C pathway in regulating inflammation. In neutrophils and eosinophils, an endothelial protein C receptor-mediated APC response leads to reduced migration in response to cytokine gradients. Endothelial protein C receptor may also suppress the apoptotic response in monocytes and enhance the expression of the adhesion integrin CD11b in granulocytes. The microvascular, anti-inflammatory influence of APC in sepsis is supported by suppression of endothelial cell adhesion molecules and the ability of APC to protect the endothelium from inflammatory insult.

CONCLUSIONS

The coordinated effects of the protein C pathway on the endothelium and the leukocyte response of the innate immune system are supported by potential restriction of endothelial protein C receptor expression to cells of the innate immune system and by suppression of adhesion molecule expression on the endothelium by APC. Reduced neutrophil migration in response to cytokines is also mediated by endothelial protein C receptor. Further clinical studies will be needed to define the intrinsic role of the protein C pathway in coordinating the innate immune response in endothelium-based inflammation.

Plasma protein C levels in patients with acute lung injury: Prognostic significance

Decreased circulating protein C is a marker of a prothrombotic state that has been associated with poor clinical outcomes in sepsis. However, protein C has not been measured in patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS). In this study, we measured circulating and intra-alveolar concentrations of protein C in 45 patients with ALI/ARDS from septic and nonseptic causes. Plasma protein C levels were lower in ALI/ARDS compared with normal controls. Lower levels of plasma protein C were associated with worse clinical outcomes, including death, fewer ventilator-free days, and more nonpulmonary organ failures, even when only patients without sepsis were analyzed. In summary, the protein C system is markedly disrupted in patients with ALI/ARDS from both septic and nonseptic causes. The protein C system may be a therapeutic target in patients with ALI/ARDS.

Protein C and thrombomodulin in human acute lung injury

Decreased circulating protein C and increased circulating thrombomodulin are markers of the prothrombotic, antifibrinolytic state associated with poor outcomes in sepsis but have not been measured in patients with ALI (acute lung injury)/ARDS (acute respiratory distress syndrome). We measured circulating and intra-alveolar protein C and thrombomodulin in 45 patients with ALI/ARDS from septic and nonseptic causes and correlated the levels with clinical outcomes. Plasma protein C levels were lower in ALI/ARDS compared with normal. Lower levels of protein C were associated with worse clinical outcomes, including death, fewer ventilator-free days, and more nonpulmonary organ failures, even when only patients without sepsis were analyzed. Levels of thrombomodulin in pulmonary edema fluid from ALI/ARDS patients were >10-fold higher than normal plasma and 2-fold higher than ALI/ARDS plasma. Higher edema fluid thrombomodulin levels were associated with worse clinical outcomes. The higher levels in edema fluid compared with plasma suggest local release of soluble thrombomodulin in the lung, possibly from a lung epithelial source. To determine whether lung epithelial cells can release thrombomodulin, A549 cells and primary isolates of human alveolar type II cells were exposed to H2O2 or inflammatory cytokines. Both epithelial cell types released thrombomodulin into the media. In summary, the protein C system is markedly disrupted in patients with ALI/ARDS from both septic and nonseptic causes. The protein C system may be a potential therapeutic target in patients with ALI/ARDS.

Relationship between the inflammation and coagulation pathways in patients with severe sepsis: implications for therapy with activated protein C

In patients with severe sepsis, thrombin has been implicated in the interrelationship between the coagulation and inflammation pathways. Thrombin is responsible for conversion of fibrinogen to fibrin (thrombus formation). Thrombin also activates endothelial cells, white blood cells and platelets. Regulation of both the coagulation and inflammation pathways is in part through the interaction of thrombin and activated protein C. Activated protein C has particular attributes that may inhibit microvascular thrombi, promote fibrinolysis and directly dampen the pro-inflammatory aspect of infection. In patients with severe sepsis, many investigators have demonstrated an active coagulopathic state, with low protein C levels. A phase III clinical trial has now demonstrated reduced mortality in patients with severe sepsis receiving activated protein C.

Markers of endothelial damage in organ dysfunction and sepsis

OBJECTIVES

To review the literature on direct and indirect markers of endothelial activation and damage in patients with sepsis and systemic inflammation and to assess their clinical usefulness for diagnosis and outcome. Various markers derived from or activated by endothelial cells are described, such as adhesion molecules, thrombomodulin, von Willebrand factor, parameters of the coagulation system, and interleukin-6. Furthermore, the association of these markers with the severity of sepsis, systemic inflammation, and outcome is evaluated.

DATA EXTRACTION AND SYNTHESIS

Published research and review articles related to these parameters, with special emphasis on clinical studies.

CONCLUSIONS

Endothelial activation and damage occur early during sepsis and play a major role in the pathophysiology of systemic inflammation. Various markers of endothelial activation are increased during sepsis and systemic inflammation, and in most studies, the level of markers such as soluble intercellular adhesion molecule, vascular cell adhesion molecule, and E selectin correlate well with the severity of inflammation and the course of the disease. However, to date, it remains unclear whether adhesion molecules and coagulation parameters are superior in this respect to interleukin-6 and procalcitonin, as direct comparisons are lacking. In addition, it is evident that markers of endothelial activation and coagulation parameters lack specificity for infection-induced endothelial damage and organ dysfunction.

Soluble thrombomodulin plasma levels are an early indication of a lethal course in human acute pancreatitis

BACKGROUND

The potential to predict severe disease and lethality by using plasma soluble thrombomodulin (sTM) and C-reactive protein (CRP) levels in 73 patients with acute pancreatitis was analyzed in a prospective 5-year investigation performed at a single institution.

METHODS

According to the Atlanta criteria, pancreatitis was classified as mild in 23 patients and as severe in 50 patients. Blood was collected on days 1, 3, 5, 7, 10, 14, 21, and 28 after the onset of pain and analyzed for sTM and CRP.

RESULTS

During the period between days 3 and 10 of acute pancreatitis when most of the admissions occurred, sTM levels at a cutoff of 75 ng/mL on day 3 (sensitivity, 100%; specificity, 77%; positive predictive value, 38%; negative predictive value, 100%) and 71 ng/mL on day 10 (sensitivity, 100%; specificity, 77%; positive predictive value, 41%; negative predictive value, 100%) were predictive of a lethal outcome. With sTM levels, it was not possible to differentiate patients with mild pancreatitis from those with severe pancreatitis (Atlanta classification). In contrast, CRP levels at a cutoff of 113 mg/L on day 3 differentiated severe from mild courses with a diagnostic sensitivity of 84%, a specificity of 60%, a positive predictive value of 78%, and a negative predictive value of 69%. CRP levels at a cutoff of 122 mg/L on day 10 differentiated mild from severe courses (nonsurvivors) with a diagnostic sensitivity of 72%, a specificity of 72%, a positive predictive value of 86%, and a negative predictive value of 53%. In contrast, differentiation of mild forms of acute pancreatitis from severe pancreatitis (survivors) on day 10 was not possible.

CONCLUSIONS

CRP is a valuable marker of disease severity in acute pancreatitis especially in the first period of pancreatitis, whereas sTM identifies early those patients with the most severe courses and a high risk of dying (negative predictive value, 100%). Determination of sTM in addition to CRP offers the opportunity of identifying early those patients who require intensive care most urgently. Of course, further investigations of sTM in acute pancreatitis are indicated to confirm our results.

Dysfunction of endothelial protein C activation in severe meningococcal sepsis

BACKGROUND

Impairment of the protein C anticoagulation pathway is critical to the thrombosis associated with sepsis and to the development of purpura fulminans in meningococcemia. We studied the expression of thrombomodulin and the endothelial protein C receptor in the dermal microvasculature of children with severe meningococcemia and purpuric or petechial lesions.

METHODS

We assessed the integrity of the endothelium and the expression of thrombomodulin and the endothelial protein C receptor in biopsy specimens of purpuric lesions from 21 children with meningococcal sepsis (median age, 41 months), as compared with control skin-biopsy specimens.

RESULTS

The expression of endothelial thrombomodulin and of the endothelial protein C receptor was lower in the patients with meningococcal sepsis than in the controls, both in vessels with thrombosis and in vessels without thrombosis. On electron microscopical examination, the endothelial cells were generally intact in both thrombosed and nonthrombosed vessels. Plasma thrombomodulin levels in the children with meningococcal sepsis (median, 6.4 ng per liter) were higher than those in the controls (median, 3.6 ng per liter; P=0.002). Plasma levels, protein C antigen, protein S antigen, and antithrombin antigen were lower than those in the controls. In two patients treated with unactivated protein C concentrate, activated protein C was undetectable at the time of admission, and plasma levels remained low.

CONCLUSIONS

In severe meningococcal sepsis, protein C activation is impaired, a finding consistent with down-regulation of the endothelial thrombomodulin-endothelial protein C receptor pathway.

Circulating thrombomodulin during radiation therapy of lung cancer

The endothelial cell glycoprotein, thrombomodulin (TM), is an important physiological anticoagulant. TM is downregulated and released from the cell membrane into the circulation by ionizing radiation and during inflammation. The present study measured plasma TM in 17 patients before, during, and after radiation therapy of lung cancer: nine patients developed radiation pneumonitis, whereas eight matched patients did not. Plasma TM did not change significantly in patients who developed radiation pneumonitis. In contrast, patients who did not develop pneumonitis exhibited a moderate, but statistically significant, decrease in plasma TM antigen during the initial 1-2 weeks, with complete normalization towards the end of treatment. Our study suggests that decreased release of TM during the early phase of radiation therapy may be associated with reduced pulmonary toxicity. The use of plasma TM as a marker of pulmonary toxicity needs further study.

Increased circulating thrombomodulin in children with septic shock

OBJECTIVES

To test the hypothesis that children diagnosed with septic shock have increased plasma thrombomodulin values as a manifestation of microcirculatory dysfunction and endothelial injury; to determine whether plasma thrombomodulin concentrations are associated with the extent of multiple organ system failure and mortality.

DESIGN

Prospective, cohort study.

SETTING

Pediatric intensive care unit.

PATIENTS

Twenty-two children with septic shock and ten, healthy, control children.

INTERVENTIONS

Blood samples were obtained for plasma thrombomodulin determinations every 6 hrs for 72 hrs in septic shock patients and once in healthy control patients.

MEASUREMENTS AND MAIN RESULTS

Thirty-two children (22 septic shock, and 10 healthy controls) were enrolled in the study. Thrombomodulin concentrations were determined by an enzyme-linked immunosorbent assay. Septic shock nonsurvivors had significantly greater mean thrombomodulin concentrations (10.6 +/- 2.2 ng/mL) than septic shock survivors (5.5 +/- 0.6 ng/mL) (p < .05) and healthy control patients (3.4 +/- 0.2 ng/mL) (p < .01). Mean thrombomodulin values increased as the number of organ system failures increased.

CONCLUSIONS

Pediatric survivors and nonsurvivors of septic shock have circulating thrombomodulin concentrations 1.5 and 3 times greater than healthy control patients. These findings likely represent sepsis-induced endothelial injury. Patients with multiple organ system failure have circulating thrombomodulin concentrations which are associated with the extent of organ dysfunction. We speculate that measurement of plasma thrombomodulin concentrations in septic shock may be a useful indicator of the severity of endothelial damage and the development of multiple organ system failure.