Biomarkers of Host Response Predict Primary End-Point Radiological Pneumonia in Tanzanian Children with Clinical Pneumonia: A Prospective Cohort Study.

BACKGROUND: Diagnosing pediatric pneumonia is challenging in low-resource settings. The World Health Organization (WHO) has defined primary end-point radiological pneumonia for use in epidemiological and vaccine studies. However, radiography requires expertise and is often inaccessible. We hypothesized that plasma biomarkers of inflammation and endothelial activation may be useful surrogates for end-point pneumonia, and may provide insight into its biological significance. METHODS: We studied children with WHO-defined clinical pneumonia (n = 155) within a prospective cohort of 1,005 consecutive febrile children presenting to Tanzanian outpatient clinics. Based on x-ray findings, participants were categorized as primary end-point pneumonia (n = 30), other infiltrates (n = 31), or normal chest x-ray (n = 94). Plasma levels of 7 host response biomarkers at presentation were measured by ELISA. Associations between biomarker levels and radiological findings were assessed by Kruskal-Wallis test and multivariable logistic regression. Biomarker ability to predict radiological findings was evaluated using receiver operating characteristic curve analysis and Classification and Regression Tree analysis. RESULTS: Compared to children with normal x-ray, children with end-point pneumonia had significantly higher C-reactive protein, procalcitonin and Chitinase 3-like-1, while those with other infiltrates had elevated procalcitonin and von Willebrand Factor and decreased soluble Tie-2 and endoglin. Clinical variables were not predictive of radiological findings. Classification and Regression Tree analysis generated multi-marker models with improved performance over single markers for discriminating between groups. A model based on C-reactive protein and Chitinase 3-like-1 discriminated between end-point pneumonia and non-end-point pneumonia with 93.3% sensitivity (95% confidence interval 76.5-98.8), 80.8% specificity (72.6-87.1), positive likelihood ratio 4.9 (3.4-7.1), negative likelihood ratio 0.083 (0.022-0.32), and misclassification rate 0.20 (standard error 0.038). CONCLUSIONS: In Tanzanian children with WHO-defined clinical pneumonia, combinations of host biomarkers distinguished between end-point pneumonia, other infiltrates, and normal chest x-ray, whereas clinical variables did not. These findings generate pathophysiological hypotheses and may have potential research and clinical utility.

Host biomarkers are associated with progression to dengue haemorrhagic fever: a nested case-control study.

OBJECTIVES: Dengue represents the most important arboviral infection worldwide. Onset of circulatory collapse can be unpredictable. Biomarkers that can identify individuals at risk of plasma leakage may facilitate better triage and clinical management. DESIGN: Using a nested case-control design, we randomly selected subjects from a prospective cohort study of dengue in Colombia (n=1582). Using serum collected within 96 hours of fever onset, we tested 19 biomarkers by ELISA in cases (developed dengue hemorrhagic fever or dengue shock syndrome (DHF/DSS); n=46), and controls (uncomplicated dengue fever (DF); n=65) and healthy controls (HC); n=15. RESULTS: Ang-1 levels were lower and angptl3, sKDR, sEng, sICAM-1, CRP, CXCL10/IP-10, IL-18 binding protein, CHI3L1, C5a and Factor D levels were increased in dengue compared to HC. sICAM-1, sEng and CXCL10/IP-10 were further elevated in subjects who subsequently developed DHF/DSS (p=0.008, p=0.028 and p=0.025, respectively). In a logistic regression model, age (odds ratio (OR) (95% CI): 0.95 (0.92-0.98), p=0.001), hyperesthesia/hyperalgesia (OR; 3.8 (1.4-10.4), p=0.008) and elevated sICAM-1 (>298ng/mL: OR; 6.3 (1.5-25.7), p=0.011) at presentation were independently associated with progression to DHF/DSS. CONCLUSIONS: These results suggest that inflammation and endothelial activation are important pathways in the pathogenesis of dengue and sICAM-1 levels may identify individuals at risk of plasma leakage.

Elevation of soluble intercellular adhesion molecule-1 levels, but not angiopoietin 2, in the plasma of human immunodeficiency virus-infected African women with clinical Kaposi sarcoma.

Circulating levels of endothelial activation biomarkers are elevated in during infection with human immunodeficiency virus 1 (HIV-1) and may also be increased in Kaposi sarcoma (KS). We compared 23 HIV-1-seropositive women with clinically diagnosed KS with 46 randomly selected controls matched for visit year, CD4 count, and antiretroviral therapy status. Conditional logistic regression was used to identify differences between cases and controls. The odds of clinical KS increased with increasing plasma viral load and with intercellular adhesion molecule 1 (ICAM-1) levels above or equal to the median. There was a borderline association between increasing plasma angiopoietin 2 levels and KS. In multivariable modeling including plasma viral load, angiopoietin 2, and ICAM-1, plasma ICAM-1 levels above or equal to the median remained associated with clinical KS (odds ratio = 14.2, 95% confidence interval = 2.3-87.7). Circulating ICAM-1 levels should be evaluated as a potential biomarker for disease progression and treatment response among HIV-infected KS patients.

Host biomarkers distinguish dengue from leptospirosis in Colombia: a case-control study.

BACKGROUND: Dengue fever and leptospirosis have partially overlapping geographic distributions, similar clinical presentations and potentially life-threatening complications but require different treatments. Distinguishing between these cosmopolitan emerging pathogens represents a diagnostic dilemma of global importance. We hypothesized that perturbations in host biomarkers can differentiate between individuals with dengue fever and leptospirosis during the acute phase of illness. METHODS: We randomly selected subjects from a prospective cohort study of acute febrile illness in Bucaramanga, Colombia and tested 19 serum biomarkers by ELISA in dengue fever (DF, n = 113) compared to subjects with leptospirosis (n = 47). Biomarkers were selected for further analysis if they had good discriminatory ability (area under the ROC curve (AUC) >0.80) and were beyond a reference range (assessed using local healthy controls). RESULTS: Nine biomarkers differed significantly between dengue fever and leptospirosis, with higher levels of Angptl3, IL-18BP, IP-10/CXCL10, Platelet Factor 4, sICAM-1, Factor D, sEng and sKDR in dengue and higher levels of sTie-2 in leptospirosis (p < 0.001 for all comparisons). Two biomarkers, sEng and IL18BP, showed excellent discriminatory ability (AUROC >0.90). When incorporated into multivariable models, sEng and IL18BP improved the diagnostic accuracy of clinical information alone. CONCLUSIONS: These results suggest that host biomarkers may have utility in differentiating between dengue and leptospirosis, clinically similar conditions of different etiology.

Elevated CXCL10 (IP-10) in bronchoalveolar lavage fluid is associated with acute cellular rejection after human lung transplantation.

BACKGROUND: CXCL10 (IP-10) is a potent chemoattractant for T cells that has been postulated to play a role in infection and acute cellular rejection (ACR) in animal models. We measured CXCL10 (IP-10) (and other cytokines previously implicated in the pathogenesis of ACR) in the bronchoalveolar lavage (BAL) of lung transplant recipients (LTRs) to determine the association between CXCL10 (IP-10) and ACR in LTRs. METHODS: In a prospective study of 85 LTRs, expression of cytokines (tumor necrosis factor, interferon-γ, interleukin [IL]-6, IL-8, IL-15, IL-16, IL-17, CXCL10 [IP-10], and MCP-1 [CCL2]) in BAL samples (n=233) from patients with episodes of ACR (n=44), infection ("Infect"; n=25), concomitant "Infect+ACR" (n=10), and "No Infect and No ACR" (n=154) were analyzed. RESULTS: The levels of both CXCL10 (IP-10) and IL-16 were significantly increased in histologically proven ACR compared with the "No Infect and No ACR" group (CXCL10 [IP-10]: 107.0 vs. 31.9 pg/mL [P=0.001] and IL-16: 472.1 vs. 283.01 pg/mL [P=0.01]). However, in a linear mixed-effects model, significant association was found only between CXCL10 (IP-10) and ACR. A one-log increase of CXCL10 (IP-10) was associated with a 40% higher risk of ACR (odds ratio, 1.4; 95% confidence interval, 1.12-1.84). CONCLUSION: Higher values of CXCL10 (IP-10) in BAL fluid are associated with ACR in LTRs, suggesting a potential mechanistic role in the pathogenesis of ACR in LTRs. These results suggest that therapeutic strategies to inhibit CXCL10 (IP-10) and or its cognate receptor, CXCR3, warrant investigation to prevent and/or treat ACR in clinical lung transplantation.

A randomized controlled pilot trial of valacyclovir for attenuating inflammation and immune activation in HIV/herpes simplex virus 2-coinfected adults on suppressive antiretroviral therapy.

BACKGROUND: Human immunodeficiency virus (HIV) is associated with increased systemic inflammation and immune activation that persist despite suppressive antiretroviral therapy (ART). Herpes simplex virus type 2 (HSV-2) is a common coinfection that may contribute to this inflammation. METHODS: Sixty HIV type 1 (HIV-1)/HSV-2-coinfected adults on suppressive ART were randomized 1:1:1 to 12 weeks of placebo, low-dose valacyclovir (500 mg twice daily), or high-dose valacyclovir (1 g twice daily) in this 18-week trial. Co-primary outcome measures were the percentage of activated (CD38(+)HLA-DR(+)) CD8 T cells in blood, and highly sensitive C-reactive protein, interleukin 6, and soluble intercellular adhesion molecule 1 in plasma. Secondary outcomes included additional immune, inflammatory cytokine, and endothelial activation markers. The impact of valacyclovir (both groups combined) on each outcome was estimated using treatment × time interaction terms in generalized estimating equation regression models. RESULTS: Participants were mostly white (75%) men who have sex with men (80%). Median age was 51 (interquartile range [IQR], 47-56) years, median duration of HIV infection was 15 (IQR, 8-21) years, median CD4 count at enrollment was 520 (IQR, 392-719) cells/µL, and median nadir CD4 count was 142 (IQR, 42-240) cells/µL. Valacyclovir was not associated with significant changes in any primary or secondary immunological outcomes in bivariate or multivariable models. Medication adherence was 97% by self-report, 96% by pill count, and 84% by urine monitoring. Eight patients had adverse events deemed possibly related to the study drug (5 placebo, 1 low-dose, 2 high-dose), and 6 patients reported at least 1 HSV outbreak (3 placebo, 3 low-dose, 0 high-dose). CONCLUSIONS: Valacyclovir did not decrease systemic immune activation or inflammatory biomarkers in HIV-1/HSV-2-coinfected adults on suppressive ART. CLINICAL TRIALS REGISTRATION: NCT01176409.

A prospective study of endothelial activation biomarkers, including plasma angiopoietin-1 and angiopoietin-2, in Kenyan women initiating antiretroviral therapy.

BACKGROUND: HIV-1-related inflammation is associated with increased levels of biomarkers of vascular adhesion and endothelial activation, and may increase production of the inflammatory protein angiopoietin-2 (ANG-2), an adverse prognostic biomarker in severe systemic infection. We hypothesized that antiretroviral therapy (ART) initiation would decrease endothelial activation, reducing plasma levels of ANG-2. METHODS: Antiretroviral-naïve Kenyan women with advanced HIV infection were followed prospectively. Endothelial activation biomarkers including soluble intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), and E-selectin, and plasma ANG-2 and angiopoietin-1 (ANG-1) were tested in stored plasma samples from 0, 6, and 12 months after ART initiation. We used Wilcoxon matched-pairs signed rank tests to compare endothelial activation biomarkers across time-points, generalized estimating equations to analyze associations with change in log10-transformed biomarkers after ART initiation, and Cox proportional-hazards regression to analyze associations with mortality. RESULTS: The 102 HIV-1-seropositive women studied had advanced infection (median CD4 count, 124 cells/µL). Soluble ICAM-1 and plasma ANG-2 levels decreased at both time-points after ART initiation, with concomitant increases in the beneficial protein ANG-1. Higher ANG-2 levels after ART initiation were associated with higher plasma HIV-1 RNA, oral contraceptive pill use, pregnancy, severe malnutrition, and tuberculosis. Baseline ANG-2 levels were higher among five women who died after ART initiation than among women who did not (median 2.85 ng/mL [inter-quartile range (IQR) 2.47-5.74 ng/mL] versus median 1.32 ng/mL [IQR 0.35-2.18 ng/mL], p = 0.01). Both soluble ICAM-1 and plasma ANG-2 levels predicted mortality after ART initiation. CONCLUSIONS: Biomarkers of endothelial activation decreased after ART initiation in women with advanced HIV-1 infection. Changes in plasma ANG-2 were associated with HIV-1 RNA levels over 12 months of follow-up. Soluble ICAM-1 and plasma ANG-2 levels represent potential biomarkers for adverse outcomes in advanced HIV-1 infection.

Dysregulation of angiopoietin 1 and 2 in Escherichia coli O157:H7 infection and the hemolytic-uremic syndrome.

Escherichia coli O157:H7-associated hemolytic-uremic syndrome (HUS) is characterized by profound prothrombotic abnormalities. Endothelial dysfunction, manifested as dysregulation of angiopoietins 1 and 2 (Ang-1/2), could underlie HUS pathophysiology. We measured Ang-1/2 in 77 children with E. coli O157:H7 infection. Ang-1, Ang-2, and the Ang-2/Ang-1 ratio were significantly different in HUS vs the pre-HUS phase of illness or uncomplicated infection. Angiopoietin dysregulation preceded HUS and worsened as HUS developed. In vitro exposure of human microvascular endothelial cells to Shiga toxin recapitulated the in vivo observations. Angiopoietin regulation is profoundly affected before and during HUS, reflecting that subclinical endothelial dysfunction precedes overt microangiopathy.

Endothelial activation biomarkers increase after HIV-1 acquisition: plasma vascular cell adhesion molecule-1 predicts disease progression.

OBJECTIVE: We aimed to determine whether endothelial activation biomarkers increase after HIV-1 acquisition, and whether biomarker levels measured in chronic infection would predict disease progression and death in HIV-1 seroconverters. DESIGN: HIV-1-seronegative Kenyan women were monitored monthly for seroconversion, and followed prospectively after HIV-1 acquisition. METHODS: Plasma levels of angiopoietin-1 and angiopoietin-2 (ANG-1, ANG-2) and soluble vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin were tested in stored samples from pre-infection, acute infection, and two chronic infection time points. We used nonparametric tests to compare biomarkers before and after HIV-1 acquisition, and Cox proportional-hazards regression to analyze associations with disease progression (CD4 < 200 cells/µl, stage IV disease, or antiretroviral therapy initiation) or death. RESULTS: Soluble ICAM-1 and VCAM-1 were elevated relative to baseline in all postinfection periods assessed (P < 0.0001). Soluble E-selectin and the ANG-2:ANG-1 ratio increased in acute infection (P = 0.0001), and ANG-1 decreased in chronic infection (P = 0.0004). Among 228 participants followed over 1028 person-years, 115 experienced disease progression or death. Plasma VCAM-1 levels measured during chronic infection were independently associated with time to HIV progression or death (adjusted hazard ratio 5.36, 95% confidence interval 1.99-14.44 per log10 increase), after adjustment for set point plasma viral load, age at infection, and soluble ICAM-1 levels. CONCLUSION: HIV-1 acquisition was associated with endothelial activation, with sustained elevations of soluble ICAM-1 and VCAM-1 postinfection. Soluble VCAM-1 may be an informative biomarker for predicting the risk of HIV-1 disease progression, morbidity, and mortality.

Host immune response in returning travellers infected with malaria.

BACKGROUND: Clinical observations suggest that Canadian-born (CB) travellers are prone to more severe malaria, characterized by higher parasite density in the blood, and severe symptoms, such as cerebral malaria and renal failure, than foreign-born travellers (FB) from areas of malaria endemicity. It was hypothesized that host cytokine and chemokine responses differ significantly in CB versus FB patients returning with malaria, contributing to the courses of severity. A more detailed understanding of the profiles of cytokines, chemokines, and endothelial activation may be useful in developing biomarkers and novel therapeutic approaches for malaria. MATERIALS AND METHODS: The patient population for the study (n = 186) was comprised of travellers returning to Toronto, Canada between 2007 and 2011. The patient blood samples' cytokine, chemokine and angiopoietin concentrations were determined using cytokine multiplex assays, and ELISA assays. RESULTS: Significantly higher plasma cytokine levels of IL-12 (p40) were observed in CB compared to FB travellers, while epidermal growth factor (EGF) was observed to be higher in FB than CB travellers. Older travellers (55 years old or greater) with Plasmodium vivax infections had significantly higher mean cytokine levels for IL-6 and macrophage colony-stimulating factor (M-CSF) than other adults with P. vivax (ages 18-55). Patients with P. vivax infections had significantly higher mean cytokine levels for monocyte chemotactic protein-1 (MCP-1), and M-CSF than patients with Plasmodium falciparum. Angiopoietin 2 (Ang-2) was higher for patients infected with P. falciparum than P. vivax, especially when comparing just the FB groups. IL-12 (p40) was higher in FB patients with P. vivax compared to P. falciparum. Il-12 (p40) was also higher in patients infected with P. vivax than those infected with Plasmodium ovale. For patients travelling to West Africa, IFN-γ and IL-6 was lower than for patients who were in other regions of Africa. CONCLUSION: Significantly higher levels of IL-12 (p40) and lower levels of EGF in CB travellers may serve as useful prognostic markers of disease severity and help guide clinical management upon return. IL-6 and M-CSF in older adults and MCP-1, IL-12 (p40) and M-CSF for P. vivax infected patients may also prove useful in understanding age-associated and species-specific host immune responses, as could the species-specific differences in Ang-2. Regional differences in host immune response to malaria infection within the same species may speak to unique strains circulating in parts of West Africa.

Liquid facets-related (lqfR) is required for egg chamber morphogenesis during Drosophila oogenesis.

Clathrin interactor 1 [CLINT1] (also called enthoprotin/EpsinR) is an Epsin N-terminal homology (ENTH) domain-containing adaptor protein that functions in anterograde and retrograde clathrin-mediated trafficking between the trans-Golgi network and the endosome. Removal of both Saccharomyces cerevisiae homologs, Ent3p and Ent5p, result in yeast that are viable, but that display a cold-sensitive growth phenotype and mistrafficking of various vacuolar proteins. Similarly, either knock-down or overexpression of vertebrate CLINT1 in cell culture causes mistrafficking of proteins. Here, we have characterized Drosophila CLINT1, liquid-facets Related (lqfR). LqfR is ubiquitously expressed throughout development and is localized to the Golgi and endosome. Strong hypomorphic mutants generated by imprecise P-element excision exhibit extra macrochaetae, rough eyes and are female sterile. Although essentially no eggs are laid, the ovaries do contain late-stage egg chambers that exhibit abnormal morphology. Germline clones reveal that LqfR expression in the somatic follicle cells is sufficient to rescue the oogenesis defects. Clones of mutant lqfR follicle cells have a decreased cell size consistent with a downregulation of Akt1. We find that while total Akt1 levels are increased there is also a significant decrease in activated phosphorylated Akt1. Taken together, these results show that LqfR function is required to regulate follicle cell size and signaling during Drosophila oogenesis.

Combinations of host biomarkers predict mortality among Ugandan children with severe malaria: a retrospective case-control study.

BACKGROUND: Severe malaria is a leading cause of childhood mortality in Africa. However, at presentation, it is difficult to predict which children with severe malaria are at greatest risk of death. Dysregulated host inflammatory responses and endothelial activation play central roles in severe malaria pathogenesis. We hypothesized that biomarkers of these processes would accurately predict outcome among children with severe malaria. METHODOLOGY/FINDINGS: Plasma was obtained from children with uncomplicated malaria (n = 53), cerebral malaria (n = 44) and severe malarial anemia (n = 59) at time of presentation to hospital in Kampala, Uganda. Levels of angiopoietin-2, von Willebrand Factor (vWF), vWF propeptide, soluble P-selectin, soluble intercellular adhesion molecule-1 (ICAM-1), soluble endoglin, soluble FMS-like tyrosine kinase-1 (Flt-1), soluble Tie-2, C-reactive protein, procalcitonin, 10 kDa interferon gamma-induced protein (IP-10), and soluble triggering receptor expressed on myeloid cells-1 (TREM-1) were determined by ELISA. Receiver operating characteristic (ROC) curve analysis was used to assess predictive accuracy of individual biomarkers. Six biomarkers (angiopoietin-2, soluble ICAM-1, soluble Flt-1, procalcitonin, IP-10, soluble TREM-1) discriminated well between children who survived severe malaria infection and those who subsequently died (area under ROC curve>0.7). Combinational approaches were applied in an attempt to improve accuracy. A biomarker score was developed based on dichotomization and summation of the six biomarkers, resulting in 95.7% (95% CI: 78.1-99.9) sensitivity and 88.8% (79.7-94.7) specificity for predicting death. Similar predictive accuracy was achieved with models comprised of 3 biomarkers. Classification tree analysis generated a 3-marker model with 100% sensitivity and 92.5% specificity (cross-validated misclassification rate: 15.4%, standard error 4.9%). CONCLUSIONS: We identified novel host biomarkers of pediatric severe and fatal malaria (soluble TREM-1 and soluble Flt-1) and generated simple biomarker combinations that accurately predicted death in an African pediatric population. While requiring validation in further studies, these results suggest the utility of combinatorial biomarker strategies as prognostic tests for severe malaria.

Angiopoietin-1 and angiopoietin-2 as clinically informative prognostic biomarkers of morbidity and mortality in severe sepsis.

OBJECTIVE: To determine the utility of angiopoietin-1 and angiopoietin-2 as potentially novel biomarkers of morbidity and mortality in patients with severe sepsis. DESIGN: Multicenter longitudinal cohort study. SETTING: Three tertiary hospital intensive care units in Hamilton, Ontario, Canada. PATIENTS: A total of 70 patients with severe sepsis were enrolled within 24 hrs of meeting the inclusion criteria for severe sepsis and followed until day 28, hospital discharge, or death. INTERVENTIONS: Clinical data and plasma samples were obtained at intensive care unit admission for all 70 patients and then daily for 1 wk and weekly thereafter for a subset of 43 patients. Levels of angiopoietin-1 and angiopoietin-2 in stored plasma samples were measured and compared with clinical characteristics, including the primary outcomes of 28-day mortality and morbidity measured by the Multiple Organ Dysfunction score. MEASUREMENTS AND MAIN RESULTS: Lower angiopoietin-1 plasma levels (≤ 5.5 ng/mL) at admission were associated with increased likelihood of death (relative risk 0.49 [95% confidence interval of 0.25-0.98], p = .046). Lower angiopoietin-1 levels remained a significant predictor of 28-day mortality in a multiple logistic regression model (adjusted odds ratio of 0.282 [95% confidence interval of 0.086-0.93], p = .037). Analysis of serial data using linear mixed models confirmed that sepsis survivors had higher levels of angiopoietin-1 (p = .012) and lower daily levels of angiopoietin-2 (p = .022) than nonsurvivors. Furthermore, survivors had higher peak angiopoietin-1 levels (median 13 vs. 10 ng/mL, p = .019) and lower nadir angiopoietin-2 levels (median 2.8 vs. 6.2 ng/mL, p = .013) than nonsurvivors. A score incorporating angiopoietin-1 and angiopoietin-2 and three other markers of endothelial activation discriminated with high accuracy between fatal and nonfatal cases (c-index of 0.80 [95% confidence interval of 0.69-0.90], p < .001). Plasma levels of angiopoietin-2 correlated with clinical markers of organ dysfunction and molecular markers of endothelial cell activation. CONCLUSIONS: Angiopoietin-1 levels at admission and both angiopoietin-1 and angiopoietin-2 levels measured serially correlated with 28-day mortality in severe sepsis. Angiopoietin-2 levels also correlated with organ dysfunction/injury and a validated clinical sepsis score. These results suggest the use of angiopoietins as clinically informative biomarkers of disease severity and patient outcome in severe sepsis.

Serum angiopoietin-1 and -2 levels discriminate cerebral malaria from uncomplicated malaria and predict clinical outcome in African children.

BACKGROUND: Limited tools exist to identify which individuals infected with Plasmodium falciparum are at risk of developing serious complications such as cerebral malaria (CM). The objective of this study was to assess serum biomarkers that differentiate between CM and non-CM, with the long-term goal of developing a clinically informative prognostic test for severe malaria. METHODOLOGY/PRINCIPAL FINDINGS: Based on the hypothesis that endothelial activation and blood-brain-barrier dysfunction contribute to CM pathogenesis, we examined the endothelial regulators, angiopoietin-1 (ANG-1) and angiopoietin-2 (ANG-2), in serum samples from P. falciparum-infected patients with uncomplicated malaria (UM) or CM, from two diverse populations--Thai adults and Ugandan children. Angiopoietin levels were compared to tumour necrosis factor (TNF). In both populations, ANG-1 levels were significantly decreased and ANG-2 levels were significantly increased in CM versus UM and healthy controls (p<0.001). TNF was significantly elevated in CM in the Thai adult population (p<0.001), but did not discriminate well between CM and UM in African children. Receiver operating characteristic curve analysis showed that ANG-1 and the ratio of ANG-2:ANG-1 accurately discriminated CM patients from UM in both populations. Applied as a diagnostic test, ANG-1 had a sensitivity and specificity of 100% for distinguishing CM from UM in Thai adults and 70% and 75%, respectively, for Ugandan children. Across both populations the likelihood ratio of CM given a positive test (ANG-1<15 ng/mL) was 4.1 (2.7-6.5) and the likelihood ratio of CM given a negative test was 0.29 (0.20-0.42). Moreover, low ANG-1 levels at presentation predicted subsequent mortality in children with CM (p = 0.027). CONCLUSIONS/SIGNIFICANCE: ANG-1 and the ANG-2/1 ratio are promising clinically informative biomarkers for CM. Additional studies should address their utility as prognostic biomarkers and potential therapeutic targets in severe malaria.