Increased Plasma Acetylcarnitine in Sepsis Is Associated With Multiple Organ Dysfunction and Mortality: A Multicenter Cohort Study

Analysis of fat oxidation capacity during cardiopulmonary exercise testing indicates long-lasting metabolic disturbance in patients with post-covid-19 syndrome

BACKGROUND & AIMS

Post-COVID-19 Syndrome (PCS) is characterized by symptoms including fatigue, reduced physical performance, dyspnea, cognitive impairment, and psychological distress. The mechanisms underlying the onset and severity of PCS point to mitochondrial dysfunction as significant contributor. This study examined fat oxidation as a function of mitochondrial capacity during exercise.

METHODS

Single-center prospective cohort study during inpatient rehabilitation. Cardiopulmonary exercise testing and assessment of fatigue using questionnaires were performed at admission and discharge. Detailed spirometric breath-by-breath data were used to calculate substrate oxidation rates.

RESULTS

Patients (N = 187; 38 % women; 49.7 ± 11.4 years) were referred to rehabilitation 253.4 ± 130.6 days after infection. Lead symptoms included fatigue/exercise intolerance (79.9 %), shortness of breath (77.0 %), and cognitive dysfunction (55.1 %). Fat oxidation capacity was disturbed in PCS patients overall (AUC: 11.3 [10.7-11.9]) compared to healthy controls (p < 0.0001), with hospitalization during acute infection predicting the level of disturbance (p < 0.0001). Low exercise capacity and high fatigue scores resulted in reduced fat oxidation (both p < 0.0001). In particular, younger males were affected by significantly reduced fat oxidation capacity (sex: p = 0.002; age: p < 0.001). Metabolic disturbance was significantly improved during exercise-based rehabilitation (AUC: 14.9 [14.4-15.4]; p < 0.0001), even for the group of younger impaired males (+44.2 %; p < 0.0001). Carbohydrate oxidation was not impaired.

CONCLUSIONS

PCS-specific restrictions in fat oxidation may indicate persistent mitochondrial dysfunction. Clinical assessment of PCS patients should include detailed breath-by-breath analysis during exercise to identify metabolic alterations especially in the group of younger males identified in this report. Exercise-based rehabilitation results in improved exercise capacity and fat oxidation and thus likely mitochondrial function.

CLINICAL TRIALS

NCT06468722.

Physiologic disruption and metabolic reprogramming in infection and sepsis

Effective responses against severe systemic infection require coordination between two complementary defense strategies that minimize the negative impact of infection on the host: resistance, aimed at pathogen elimination, and disease tolerance, which limits tissue damage and preserves organ function. Resistance and disease tolerance mostly rely on divergent metabolic programs that may not operate simultaneously in time and space. Due to evolutionary reasons, the host initially prioritizes the elimination of the pathogen, leading to dominant resistance mechanisms at the potential expense of disease tolerance, which can contribute to organ failure. Here, we summarize our current understanding of the role of physiological perturbations resulting from infection in immune response dynamics and the metabolic program requirements associated with resistance and disease tolerance mechanisms. We then discuss how insight into the interplay of these mechanisms could inform future research aimed at improving sepsis outcomes and the potential for therapeutic interventions.

The role of fatty acid metabolism in acute lung injury: a special focus on immunometabolism

Reputable evidence from multiple studies suggests that excessive and uncontrolled inflammation plays an indispensable role in mediating, amplifying, and protracting acute lung injury (ALI). Traditionally, immunity and energy metabolism are regarded as separate functions regulated by distinct mechanisms, but recently, more and more evidence show that immunity and energy metabolism exhibit a strong interaction which has given rise to an emerging field of immunometabolism. Mammalian lungs are organs with active fatty acid metabolism, however, during ALI, inflammation and oxidative stress lead to a series metabolic reprogramming such as impaired fatty acid oxidation, increased expression of proteins involved in fatty acid uptake and transport, enhanced synthesis of fatty acids, and accumulation of lipid droplets. In addition, obesity represents a significant risk factor for ALI/ARDS. Thus, we have further elucidated the mechanisms of obesity exacerbating ALI from the perspective of fatty acid metabolism. To sum up, this paper presents a systematical review of the relationship between extensive fatty acid metabolic pathways and acute lung injury and summarizes recent advances in understanding the involvement of fatty acid metabolism-related pathways in ALI. We hold an optimistic believe that targeting fatty acid metabolism pathway is a promising lung protection strategy, but the specific regulatory mechanisms are way too complex, necessitating further extensive and in-depth investigations in future studies.

Immunometabolic features of natural killer cells are associated with infection outcomes in critical illness

Immunosuppression increases the risk of nosocomial infection in patients with chronic critical illness. This exploratory study aimed to determine the immunometabolic signature associated with nosocomial infection during chronic critical illness. We prospectively recruited patients who were admitted to the respiratory care center and who had received mechanical ventilator support for more than 10 days in the intensive care unit. The study subjects were followed for the occurrence of nosocomial infection until 6 weeks after admission, hospital discharge, or death. The cytokine levels in the plasma samples were measured. Single-cell immunometabolic regulome profiling by mass cytometry, which analyzed 16 metabolic regulators in 21 immune subsets, was performed to identify immunometabolic features associated with the risk of nosocomial infection. During the study period, 37 patients were enrolled, and 16 patients (43.2%) developed nosocomial infection. Unsupervised immunologic clustering using multidimensional scaling and logistic regression analyses revealed that expression of nuclear respiratory factor 1 (NRF1) and carnitine palmitoyltransferase 1a (CPT1a), key regulators of mitochondrial biogenesis and fatty acid transport, respectively, in natural killer (NK) cells was significantly associated with nosocomial infection. Downregulated NRF1 and upregulated CPT1a were found in all subsets of NK cells from patients who developed a nosocomial infection. The risk of nosocomial infection is significantly correlated with the predictive score developed by selecting NK cell-specific features using an elastic net algorithm. Findings were further examined in an independent cohort of COVID-19-infected patients, and the results confirm that COVID-19-related mortality is significantly associated with mitochondria biogenesis and fatty acid oxidation pathways in NK cells. In conclusion, this study uncovers that NK cell-specific immunometabolic features are significantly associated with the occurrence and fatal outcomes of infection in critically ill population, and provides mechanistic insights into NK cell-specific immunity against microbial invasion in critical illness.

Occult hypoperfusion and changes of systemic lipid levels after severe trauma: an analysis in a standardized porcine polytrauma model

BACKGROUND

Occult hypoperfusion describes the absence of sufficient microcirculation despite normal vital signs. It is known to be associated with prolonged elevation of serum lactate and later complications in severely injured patients. We hypothesized that changes in circulating lipids are related to responsiveness to resuscitation. The purpose of this study is investigating the relation between responsiveness to resuscitation and lipidomic course after poly trauma.

METHODS

Twenty-five male pigs were exposed a combined injury of blunt chest trauma, liver laceration, controlled haemorrhagic shock, and femoral shaft fracture. After 1 h, animals received resuscitation and fracture stabilization. Venous blood was taken regularly and 233 specific lipids were analysed. Animals were divided into two groups based on serum lactate level at the end point as an indicator of responsiveness to resuscitation (<2 mmol/L: responder group (R group), ≧2 mmol/L: occult hypoperfusion group (OH group)).

RESULTS

Eighteen animals met criteria for the R group, four animals for the OH group, and three animals died. Acylcarnitines showed a significant increase at 1 h compared to baseline in both groups. Six lipid subgroups showed a significant increase only in R group at 2 h. There was no significant change at other time points.

CONCLUSIONS

Six lipid groups increased significantly only in the R group at 2 h, which may support the idea that they could serve as potential biomarkers to help us to detect the presence of occult hypoperfusion and insufficient resuscitation. We feel that further study is required to confirm the role and mechanism of lipid changes after trauma.

Plasma Metabolomics Reveals Distinct Biological and Diagnostic Signatures for Melioidosis

Rationale: The global burden of sepsis is greatest in low-resource settings. Melioidosis, infection with the gram-negative bacterium Burkholderia pseudomallei, is a frequent cause of fatal sepsis in endemic tropical regions such as Southeast Asia. Objectives: To investigate whether plasma metabolomics would identify biological pathways specific to melioidosis and yield clinically meaningful biomarkers. Methods: Using a comprehensive approach, differential enrichment of plasma metabolites and pathways was systematically evaluated in individuals selected from a prospective cohort of patients hospitalized in rural Thailand with infection. Statistical and bioinformatics methods were used to distinguish metabolomic features and processes specific to patients with melioidosis and between fatal and nonfatal cases. Measurements and Main Results: Metabolomic profiling and pathway enrichment analysis of plasma samples from patients with melioidosis (n = 175) and nonmelioidosis infections (n = 75) revealed a distinct immuno-metabolic state among patients with melioidosis, as suggested by excessive tryptophan catabolism in the kynurenine pathway and significantly increased levels of sphingomyelins and ceramide species. We derived a 12-metabolite classifier to distinguish melioidosis from other infections, yielding an area under the receiver operating characteristic curve of 0.87 in a second validation set of patients. Melioidosis nonsurvivors (n = 94) had a significantly disturbed metabolome compared with survivors (n = 81), with increased leucine, isoleucine, and valine metabolism, and elevated circulating free fatty acids and acylcarnitines. A limited eight-metabolite panel showed promise as an early prognosticator of mortality in melioidosis. Conclusions: Melioidosis induces a distinct metabolomic state that can be examined to distinguish underlying pathophysiological mechanisms associated with death. A 12-metabolite signature accurately differentiates melioidosis from other infections and may have diagnostic applications.

Kidney function as a key driver of the pharmacokinetic response to high-dose L-carnitine in septic shock

STUDY OBJECTIVE

Levocarnitine (L-carnitine) has shown promise as a metabolic-therapeutic for septic shock, where mortality approaches 40%. However, high-dose (≥ 6 grams) intravenous supplementation results in a broad range of serum concentrations. We sought to describe the population pharmacokinetics (PK) of high-dose L-carnitine, test various estimates of kidney function, and assess the correlation of PK parameters with pre-treatment metabolites in describing drug response for patients with septic shock.

DESIGN

Population PK analysis was done with baseline normalized concentrations using nonlinear mixed effect models in the modeling platform Monolix. Various estimates of kidney function, patient demographics, dose received, and organ dysfunction were tested as population covariates.

DATA SOURCE

We leveraged serum samples and metabolomics data from a phase II trial of L-carnitine in vasopressor-dependent septic shock. Serum was collected at baseline (T0); end-of-infusion (T12); and 24, 48, and 72 h after treatment initiation.

PATIENTS AND INTERVENTION

Patients were adaptively randomized to receive intravenous L-carnitine (6 grams, 12 grams, or 18 grams) or placebo.

MEASUREMENTS AND MAIN RESULTS

The final dataset included 542 serum samples from 130 patients randomized to L-carnitine. A two-compartment model with linear elimination and a fixed volume of distribution (17.1 liters) best described the data and served as a base structural model. Kidney function estimates as a covariate on the elimination rate constant (k) reliably improved model fit. Estimated glomerular filtration rate (eGFR), based on the 2021 Chronic Kidney Disease Epidemiology collaboration (CKD-EPI) equation with creatinine and cystatin C, outperformed creatinine clearance (Cockcroft-Gault) and older CKD-EPI equations that use an adjustment for self-identified race.

CONCLUSIONS

High-dose L-carnitine supplementation is well-described by a two-compartment population PK model in patients with septic shock. Kidney function estimates that leverage cystatin C provided superior model fit. Future investigations into high-dose L-carnitine supplementation should consider baseline metabolic status and dose adjustments based on renal function over a fixed or weight-based dosing paradigm.

Application of metabolomics in diagnostics and differentiation of meningitis: A narrative review with a critical approach to the literature

Due to its high mortality rate associated with various life-threatening sequelae, meningitis poses a vital problem in contemporary medicine. Numerous algorithms, many of which were derived with the aid of artificial intelligence, were brought up in a strive for perfection in predicting the status of sepsis-related survival or exacerbation. This review aims to provide key insights on the contextual utilization of metabolomics. The aim of this the metabolomic approach set of methods can be used to investigate both bacterial and host metabolite sets from both the host and its microbes in several types of specimens - even in one's breath, mainly with use of two methods - Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR). Metabolomics, and has been used to elucidate the mechanisms underlying disease development and metabolic identification changes in a wide range of metabolite contents, leading to improved methods of diagnosis, treatment, and prognosis of meningitis. Mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) are the main analytical platforms used in metabolomics. Its high sensitivity accounts for the usefulness of metabolomics in studies into meningitis, its sequelae, and concomitant comorbidities. Metabolomics approaches are a double-edged sword, due to not only their flexibility, but also - high complexity, as even minor changes in the multi-step methods can have a massive impact on the results. Information on the differential diagnosis of meningitis act as a background in presenting the merits and drawbacks of the use of metabolomics in context of meningeal infections.

METABOLOMIC AND PROTEOMIC CHANGES IN TRAUMA-INDUCED HYPOCALCEMIA

ABSTRACT

Background: Trauma-induced hypocalcemia is common and associated with adverse outcomes, but the mechanisms remain unclear. Thus, we aimed to characterize the metabolomic and proteomic differences between normocalcemic and hypocalcemic trauma patients to illuminate biochemical pathways that may underlie a distinct pathology linked with this clinical phenomenon. Methods: Plasma was obtained on arrival from injured patients at a Level 1 Trauma Center. Samples obtained after transfusion were excluded. Multiple regression was used to adjust the omics data for injury severity and arrival base excess before metabolome- and proteome-wide comparisons between normocalcemic (ionized Ca 2+ > 1.0 mmol/L) and hypocalcemic (ionized Ca 2+ ≤ 1.0 mmol/L) patients using partial least squares-discriminant analysis. OmicsNet and Gene Ontology were used for network and pathway analyses, respectively. Results: Excluding isolated traumatic brain injury and penetrating injury, the main analysis included 36 patients (n = 14 hypocalcemic, n = 22 normocalcemic). Adjusted analyses demonstrated distinct metabolomic and proteomic signatures for normocalcemic and hypocalcemic patients. Hypocalcemic patients had evidence of mitochondrial dysfunction (tricarboxylic acid cycle disruption, dysfunctional fatty acid oxidation), inflammatory dysregulation (elevated damage-associated molecular patterns, activated endothelial cells), aberrant coagulation pathways, and proteolytic imbalance with increased tissue destruction. Conclusions: Independent of injury severity, hemorrhagic shock, and transfusion, trauma-induced hypocalcemia is associated with early metabolomic and proteomic changes that may reflect unique pathology in hypocalcemic trauma patients. This study paves the way for future experiments to investigate mechanisms, identify intervenable pathways, and refine our management of hypocalcemia in severely injured patients.

Short and medium chain acylcarnitines as markers of outcome in diabetic and non-diabetic subjects with acute coronary syndromes

BACKGROUND

Carnitine metabolism produces numerous molecular species of short-, medium-, and long-chain acylcarnitines, which play important roles in energy homeostasis and fatty acid transport in the myocardium. Given that disturbances in the carnitine metabolism are linked to cardiometabolic disease, we studied the relationship of circulating acylcarnitines with outcomes in patients with acute coronary syndromes (ACS) and evaluated differences in circulating levels of these metabolites between diabetic and non-diabetic patients.

METHODS

Harnessing a prospective multicentre cohort study (SPUM-ACS; NCT01000701), we measured plasma levels of acylcarnitines, carnitine, and carnitine metabolites to assess their relationship with adjudicated major adverse cardiac events (MACE), defined as composite of myocardial infarction, stroke, clinically indicated revascularization, or death of any cause. The SPUM-ACS study enrolled patients presenting with ACS to Swiss University Hospitals between 2009 and 2012. Acetylcarnitine, octanoylcarnitine, proprionylcarnitine, butyrylcarnitine, pentanoylcarnitine, hexanoylcarnitine, carnitine, γ-butyrobetaine, and trimethylamine N-oxide were measured in plasma using stable isotope dilution high-performance liquid chromatography with online electrospray ionization tandem mass spectrometry.

RESULTS

A total of 1683 patients with ACS were included in the study. All measured metabolites except γ-butyrobetaine and carnitine were higher in diabetic subject (n = 294) than in non-diabetic subjects (n = 1389). On univariate analysis, all metabolites, apart from octenoylcarnitine, were significantly associated with MACE at 1 year. After multivariable adjustment for established risk factors, acetylcarnitine remained an independent predictor of MACE at 1-year (quartile 4 vs. quartile 1, adjusted hazard ratio 2.06; 95% confidence interval 1.12-3.80, P = 0.020).

CONCLUSION

Circulating levels of acetylcarnitine independently predict residual cardiovascular risk in patients with ACS.

Biomolecular map of albumin identifies signatures of severity and early mortality in acute liver failure

BACKGROUND & AIMS

Acute liver failure (ALF) is associated with high mortality. Alterations in albumin structure and function have been shown to correlate with outcomes in cirrhosis. We undertook a biomolecular analysis of albumin to determine its correlation with hepatocellular injury and early mortality in ALF.

METHODS

Altogether, 225 participants (200 patients with ALF and 25 healthy controls [HC]) were enrolled. Albumin was purified from the baseline plasma of the training cohort (ALF, n = 40; survivors, n = 8; non-survivors, n = 32; and HC, n = 5); analysed for modifications, functionality, and bound multi-omics signatures; and validated in a test cohort (ALF, n = 160; survivors, n = 53; non-survivors, n = 107; and HC, n = 20).

RESULTS

In patients with ALF, albumin is more oxidised and glycosylated with a distinct multi-omics profile than that in HC, more so in non-survivors (p <0.05). In non-survivors, albumin was more often bound (p <0.05, false discovery rate <0.01) to proteins associated with inflammation, advanced glycation end product, metabolites linked to arginine, proline metabolism, bile acid, and mitochondrial breakdown products. Increased bacterial taxa (Listeria, Clostridium, etc.) correlated with lipids (triglycerides [4:0/12:0/12:0] and phosphatidylserine [39:0]) and metabolites (porphobilinogen and nicotinic acid) in non-survivors (r2 >0.7). Multi-omics signature-based probability of detection for non-survival was >90% and showed direct correlation with albumin functionality and clinical parameters (r2 >0.85). Probability-of-detection metabolites built on the top five metabolites, namely, nicotinic acid, l-acetyl carnitine, l-carnitine, pregnenolone sulfate, and N-(3-hydroxybutanoyl)-l-homoserine lactone, showed diagnostic accuracy of 98% (AUC 0.98, 95% CI 0.95-1.0) and distinguish patients with ALF predisposed to early mortality (log-rank <0.05). On validation using high-resolution mass spectrometry and five machine learning algorithms in test cohort 1 (plasma and paired one-drop blood), the metabolome panel showed >92% accuracy/sensitivity and specificity for prediction of mortality.

CONCLUSIONS

In ALF, albumin is hyperoxidised and substantially dysfunctional. Our study outlines distinct 'albuminome' signatures capable of distinguishing patients with ALF predisposed to early mortality or requiring emergency liver transplantation.

IMPACTS AND IMPLICATIONS

Here, we report that the biomolecular map of albumin is distinct and linked to severity and outcome in patients with acute liver failure (ALF). Detailed structural, functional, and albumin-omics analysis in patients with ALF led to the identification and classification of albumin-bound biomolecules, which could segregate patients with ALF predisposed to early mortality. More importantly, we found albumin-bound metabolites indicative of mitochondrial damage and hyperinflammation as a putative indicator of <30-day mortality in patients with ALF. This preclinical study validates the utility of albuminome analysis for understanding the pathophysiology and development of poor outcome indicators in patients with ALF.

Mid-Term Evolution of the Serum Acylcarnitine Profile in Critically Ill Survivors: A Metabolic Insight into Survivorship

It is unknown if the abnormal acylcarnitine (AC) profile observed early after discharge of a prolonged stay in an intensive care unit (ICU) would persist over time. This prospective observational study aimed to describe the mid-term AC profile evolution in survivors of a prolonged ICU stay (≥7 days). Adults enrolled in our post-ICU follow-up program and who attended the consultation 3 months (M3) after discharge were included. Serum AC concentrations were assessed within 7 days following ICU discharge (T0) and at M3. A total of 64 survivors were analyzed after an ICU stay of 15 (9-24) days. Free carnitine (C0) concentration decreased from 45.89 (35.80-127.5) to 28.73 (20.31-38.93) µmol/L (p < 0.001). C0 deficiency was not observed at T0 but in 7/64 (11%) survivors at M3. The total AC/C0 ratio (normal ≤ 0.4) was 0.33 (0.24-0.39) at T0 and reached 0.39 (0.30-0.56) at M3 (p = 0.001). A ratio >0.4 was observed in 16/64 (25%) at T0 and in 32/64 (50%) at M3 (p = 0.006). The short-chain ACs decreased from 1.310 (0.927-1.829) at T0 to 0.945 (0.709-1.127) µmol/L at M3 (p < 0.001). In parallel, the urea/creatinine ratio and the Sarcopenic Index, respectively, decreased and increased between T0 and M3. This AC profile is suspected to signal a mitochondrial dysfunction and was, especially for short-chain ACs, a marker of protein catabolism.

Potential effects of Ag ion on the host by changing the structure of its gut microbiota

Silver (Ag) can change the structure of the gut microbiota (GM), but how such change may affect host health is unknown. In this study, mice were exposed to silver acetate daily for 120 days. During this period, Ag accumulation in the liver was measured, its effects on GM structure were analyzed, and potential metabolic changes in liver and serum were examined. Although Ag accumulation remained unchanged in most treatments, the ratio of Firmicutes to Bacteroidetes at the phylum level increased and changes in the relative abundance of 33 genera were detected, suggesting that Ag altered the energy metabolism of mice via changes in the gut GM. In serum and liver, 34 and 72 differentially expressed metabolites were identified, respectively. The KEGG pathways thus enriched mainly included those involving the metabolism of amino acids, organic acids, lipids, and purine. Strong correlations were found between 33 % of the microorganisms with altered relative abundances and 46 % of the differentially expressed metabolites. The resulting clusters yielded two communities responsible for host inflammation and energy metabolism. Overall, these results demonstrate potential effects of Ag on the host, by changing its GM structure, and the need to consider them when evaluating the health risk of Ag.

Serum metabolomic signatures of fatty acid oxidation defects differentiate host-response subphenotypes of acute respiratory distress syndrome

BACKGROUND

Fatty acid oxidation (FAO) defects have been implicated in experimental models of acute lung injury and associated with poor outcomes in critical illness. In this study, we examined acylcarnitine profiles and 3-methylhistidine as markers of FAO defects and skeletal muscle catabolism, respectively, in patients with acute respiratory failure. We determined whether these metabolites were associated with host-response ARDS subphenotypes, inflammatory biomarkers, and clinical outcomes in acute respiratory failure.

METHODS

In a nested case-control cohort study, we performed targeted analysis of serum metabolites of patients intubated for airway protection (airway controls), Class 1 (hypoinflammatory), and Class 2 (hyperinflammatory) ARDS patients (N = 50 per group) during early initiation of mechanical ventilation. Relative amounts were quantified by liquid chromatography high resolution mass spectrometry using isotope-labeled standards and analyzed with plasma biomarkers and clinical data.

RESULTS

Of the acylcarnitines analyzed, octanoylcarnitine levels were twofold increased in Class 2 ARDS relative to Class 1 ARDS or airway controls (P = 0.0004 and < 0.0001, respectively) and was positively associated with Class 2 by quantile g-computation analysis (P = 0.004). In addition, acetylcarnitine and 3-methylhistidine were increased in Class 2 relative to Class 1 and positively correlated with inflammatory biomarkers. In all patients within the study with acute respiratory failure, increased 3-methylhistidine was observed in non-survivors at 30 days (P = 0.0018), while octanoylcarnitine was increased in patients requiring vasopressor support but not in non-survivors (P = 0.0001 and P = 0.28, respectively).

CONCLUSIONS

This study demonstrates that increased levels of acetylcarnitine, octanoylcarnitine, and 3-methylhistidine distinguish Class 2 from Class 1 ARDS patients and airway controls. Octanoylcarnitine and 3-methylhistidine were associated with poor outcomes in patients with acute respiratory failure across the cohort independent of etiology or host-response subphenotype. These findings suggest a role for serum metabolites as biomarkers in ARDS and poor outcomes in critically ill patients early in the clinical course.

Serum Acylcarnitines Profile in Critically Ill Survivors According to Illness Severity and ICU Length of Stay: An Observational Study

The acylcarnitine (AC) profile has been shown to be altered in survivors of a prolonged stay in intensive care unit (ICU), with higher short-chain derivates compared to reference ranges. The present study aimed at describing the AC profile of patients surviving a short ICU stay versus patients surviving a >7-day multiple organ dysfunction. Patients discharged from ICU after an elective and non-complicated cardiac surgery (CS) were recruited. For each CS, one to two adults, matched for gender and age, were recruited among patients enrolled in our post-ICU follow-up program after an ICU stay ≥7 days (PS). In both groups, the AC profile was determined during the week following ICU discharge. A total of 50 CS patients (SAPS II 23 (18-27)) survived an ICU stay of 2 (2-3) days and were matched to 85 PS patients (SAPS II 36 (28-51), p < 0.001) who survived an ICU stay of 11 (8-15.5) days. No carnitine deficiency was observed in either group. Their total AC/C0 ratio was similar: 0.355 (0.268-0.415) and 0.358 (0.289-0.417), respectively (p = 0.391). A ratio >0.4 representing a disturbed mitochondrial metabolism was observed in 26/85 (30.6%) PS patients and in 15/50 (30%) CS patients (p > 0.999). The long-chain ACs were elevated in both groups, with a greater increase in the CS group. The short-chain ACs were higher in the PS group: 1.520 (1.178-1.974) vs. 1.185 (0.932-1.895) μmol/L (p < 0.001). The role of the AC profile as potential marker of catabolism and/or mitochondrial dysfunction during the critical illness trajectory should be further investigated.

Predictive value of presepsin and acylcarnitines for severity and biliary drainage in acute cholangitis

BACKGROUND

Bacteremia, which is a major cause of mortality in patients with acute cholangitis, induces hyperactive immune response and mitochondrial dysfunction. Presepsin is responsible for pathogen recognition by innate immunity. Acylcarnitines are established mitochondrial biomarkers.

AIM

To clarify the early predictive value of presepsin and acylcarnitines as biomarkers of severity of acute cholangitis and the need for biliary drainage.

METHODS

Of 280 patients with acute cholangitis were included and the severity was stratified according to the Tokyo Guidelines 2018. Blood presepsin and plasma acylcarnitines were tested at enrollment by chemiluminescent enzyme immunoassay and ultra-high-performance liquid chromatography-mass spectrometry, respectively.

RESULTS

The concentrations of presepsin, procalcitonin, short- and medium-chain acylcarnitines increased, while long-chain acylcarnitines decreased with the severity of acute cholangitis. The areas under the receiver operating characteristic curves (AUC) of presepsin for diagnosing moderate/severe and severe cholangitis (0.823 and 0.801, respectively) were greater than those of conventional markers. The combination of presepsin, direct bilirubin, alanine aminotransferase, temperature, and butyryl-L-carnitine showed good predictive ability for biliary drainage (AUC: 0.723). Presepsin, procalcitonin, acetyl-L-carnitine, hydroxydodecenoyl-L-carnitine, and temperature were independent predictors of bloodstream infection. After adjusting for severity classification, acetyl-L-carnitine was the only acylcarnitine independently associated with 28-d mortality (hazard ratio 14.396; P < 0.001) (AUC: 0.880). Presepsin concentration showed positive correlation with direct bilirubin or acetyl-L-carnitine.

CONCLUSION

Presepsin could serve as a specific biomarker to predict the severity of acute cholangitis and need for biliary drainage. Acetyl-L-carnitine is a potential prognostic factor for patients with acute cholangitis. Innate immune response was associated with mitochondrial metabolic dysfunction in acute cholangitis.

Serum Metabolomic Profiles in Critically Ill Patients with Shock on Admission to the Intensive Care Unit

Inflammatory processes are common in intensive care (ICU) patients and can induce multiple changes in metabolism, leading to increased risks of morbidity and mortality. Metabolomics enables these modifications to be studied and identifies a patient’s metabolic profile. The objective is to precise if the use of metabolomics at ICU admission can help in prognostication. This is a prospective ex-vivo study, realized in a university laboratory and a medico-surgical ICU. Metabolic profiles were analyzed by proton nuclear magnetic resonance. Using multivariable analysis, we compared metabolic profiles of volunteers and ICU patients divided into predefined subgroups: sepsis, septic shock, other shock and ICU controls. We also assessed possible correlations between metabolites and mortality. One hundred and eleven patients were included within 24 h of ICU admission, and 19 healthy volunteers. The ICU mortality rate was 15%. Metabolic profiles were different in ICU patients compared to healthy volunteers (p < 0.001). Among the ICU patients, only the subgroup of patients with septic shock had significant differences compared to the ICU control patients in several metabolites: pyruvate, lactate, carnitine, phenylalanine, urea, creatine, creatinine and myo-inositol. However, there was no correlation between these metabolite profiles and mortality. On the first day of ICU admission, we observed changes in some metabolic products in patients with septic shock, suggesting increased anaerobic glycolysis, proteolysis, lipolysis and gluconeogenesis. These changes were not correlated with prognosis.

Sustained Perturbation of Metabolism and Metabolic Subphenotypes Are Associated With Mortality and Protein Markers of the Host Response

Perturbed host metabolism is increasingly recognized as a pillar of sepsis pathogenesis, yet the dynamic alterations in metabolism and its relationship to other components of the host response remain incompletely understood. We sought to identify the early host-metabolic response in patients with septic shock and to explore biophysiological phenotyping and differences in clinical outcomes among metabolic subgroups.

DESIGN

We measured serum metabolites and proteins reflective of the host-immune and endothelial response in patients with septic shock.

SETTING

We considered patients from the placebo arm of a completed phase II, randomized controlled trial conducted at 16 U.S. medical centers. Serum was collected at baseline (within 24 hr of the identification of septic shock), 24-hour, and 48-hour postenrollment. Linear mixed models were built to assess the early trajectory of protein analytes and metabolites stratified by 28-day mortality status. Unsupervised clustering of baseline metabolomics data was conducted to identify subgroups of patients.

PATIENTS

Patients with vasopressor-dependent septic shock and moderate organ dysfunction that were enrolled in the placebo arm of a clinical trial.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Fifty-one metabolites and 10 protein analytes were measured longitudinally in 72 patients with septic shock. In the 30 patients (41.7%) who died prior to 28 days, systemic concentrations of acylcarnitines and interleukin (IL)-8 were elevated at baseline and persisted at T24 and T48 throughout early resuscitation. Concentrations of pyruvate, IL-6, tumor necrosis factor-α, and angiopoietin-2 decreased at a slower rate in patients who died. Two groups emerged from clustering of baseline metabolites. Group 1 was characterized by higher levels of acylcarnitines, greater organ dysfunction at baseline and postresuscitation (p < 0.05), and greater mortality over 1 year (p < 0.001).

CONCLUSIONS

Among patients with septic shock, nonsurvivors exhibited a more profound and persistent dysregulation in protein analytes attributable to neutrophil activation and disruption of mitochondrial-related metabolism than survivors.

Circulating protein and lipid markers of early sepsis diagnosis and prognosis: a scoping review

PURPOSE OF REVIEW

Sepsis is the extreme response to infection associated with high mortality, yet reliable biomarkers for its identification and stratification are lacking.

RECENT FINDINGS

Our scoping review of studies published from January 2017 to September 2022 that investigated circulating protein and lipid markers to inform non-COVID-19 sepsis diagnosis and prognosis identified interleukin (IL)-6, IL-8, heparin-binding protein (HBP), and angiopoietin-2 as having the most evidence. Biomarkers can be grouped according to sepsis pathobiology to inform biological data interpretation and four such physiologic processes include: immune regulation, endothelial injury and coagulopathy, cellular injury, and organ injury. Relative to proteins, the pleiotropic effects of lipid species' render their categorization more difficult. Circulating lipids are relatively less well studied in sepsis, however, low high-density lipoprotein (HDL) is associated with poor outcome.

SUMMARY

There is a lack of robust, large, and multicenter studies to support the routine use of circulating proteins and lipids for sepsis diagnosis or prognosis. Future studies will benefit from standardizing cohort design as well as analytical and reporting strategies. Incorporating biomarker dynamic changes and clinical data in statistical modeling may improve specificity for sepsis diagnosis and prognosis. To guide future clinical decisions at the bedside, point-of-care circulating biomarker quantification is needed.

Serum Acylcarnitine and Long-Term Functional Prognosis after Traumatic Brain Injury with Intracranial Injury: A Multi-Center Prospective Study

Serum biomarkers have potential to help predict prognosis of traumatic brain injury (TBI). The objective of this study was to evaluate the association between serum acylcarnitine levels and functional outcomes at 1 month/6 months after injury for TBI patients with intracranial hemorrhage or diffuse axonal injury. This study is a multi-center prospective cohort study in which adult TBI patients with intracranial injury visiting the emergency departments (EDs) from December 2018 to June 2020 were enrolled. Serum acylcarnitine levels at the time of ED arrival were categorized into four groups: low (1.2-5.5 μmol/L), low-normal (5.6-10.0 μmol/L), high-normal (10.1-14.5 μmol/L), and high (1.4.6-56.6 μmol/L). The study outcome was set as poor functional recovery at 1 month/6 months after injury (Glasgow Outcome Scale score, 1-3). Multi-level logistic regression analyses were conducted to estimate association between serum acylcarnitine and functional outcomes. Among total of 549 patients, poor functional recovery at 1 month and 6 months after injury were observed in 29.1% (160/549) and 29.1% (158/543, follow-up loss n = 6). The odds for 1-month poor functional outcome increased in the high-normal and the high groups [adjusted odds ratios, AORs (95% confidence intervals, CIs): 1.56 (1.09-2.23) and 2.47 (1.63-3.75)], compared with the low-normal group) and also as a continuous variable [1.05 (1.03-1.07) for each 1 μmol/L]. Regarding 6-month mortality, the high group had significantly higher odds when compared with the low-normal group [AOR (95% CI): 2.16 (1.37-3.40)]. Higher serum acylcarnitine levels are associated with poor functional outcomes at 1 month/6 months after injury for TBI patients with intracranial injury.

The correlation study between blood urea nitrogen to serum albumin ratio and prognosis of patients with sepsis during hospitalization

BACKGROUND

Sepsis is a common critical illness in intensive care unit (ICU) and seriously threatens the life of patients. Therefore, to identify a simple and effective clinical indicator to determine prognosis is essential for the management of sepsis patients. This study was mainly based on blood urea nitrogen to albumin ratio (B/A), a comprehensive index, to explore its correlation with the prognosis of sepsis patients during hospitalization.

METHODS

Totally, adult patients in ICU who were diagnosed with sepsis in Medical Information Mart for Intensive Care IV(MIMIC-IV) database from 2008 to 2019 were involved in this study. The study population were divided into survivors group and non-survivors group based on the prognosis during hospitalization. Restricted cubic spline (RCS) was utilized to analyze the association between B/A level and the risk of ICU all-cause mortality in patients with sepsis and determine the optimal cut-off value of B/A. The study population was divided into low B/A group and high B/A group based on the optimal cut-off value. The survival curve of ICU cumulative survival rate was draw through Kaplan-Meier method. The correlation between B/A and the prognosis of patients was conducted by multivariate Cox regression analysis. Furthermore, we performed sensitivity analyses to assess the robustness of the results.

RESULTS

A total of 10,578 patients with sepsis were enrolled, and the ICU all-cause mortality was 15.89%. The patients in the non-survivors group had higher B/A values and more comorbidities than those in the survivors group. RCS showed that the risk of ICU all-cause mortality increased with the B/A level, showing a non-linear trend (χ2 = 66.82, p < 0.001). The mortality rate in the high B/A group was significantly higher than that in the low B/A group (p < 0.001). Kaplan-Meier curves revealed that compared with the low B/A group, the ICU cumulative survival rate of patients with sepsis was significantly lower in the high B/A group (log-rank test, χ2 = 148.620, p < 0.001). Further analysis of multivariate Cox proportional hazards regression showed that an elevated B/A (≥ 7.93) was an independent factor associated with ICU mortality among patients with sepsis.

CONCLUSIONS

An elevated B/A might be a useful prognostic indicator in patients with sepsis. This study could offer a deeper insight into treating sepsis.

Signatures of Mitochondrial Dysfunction and Impaired Fatty Acid Metabolism in Plasma of Patients with Post-Acute Sequelae of COVID-19 (PASC)

Exercise intolerance is a major manifestation of post-acute sequelae of severe acute respiratory syndrome coronavirus infection (PASC, or "long-COVID"). Exercise intolerance in PASC is associated with higher arterial blood lactate accumulation and lower fatty acid oxidation rates during graded exercise tests to volitional exertion, suggesting altered metabolism and mitochondrial dysfunction. It remains unclear whether the profound disturbances in metabolism that have been identified in plasma from patients suffering from acute coronavirus disease 2019 (COVID-19) are also present in PASC. To bridge this gap, individuals with a history of previous acute COVID-19 infection that did not require hospitalization were enrolled at National Jewish Health (Denver, CO, USA) and were grouped into those that developed PASC (n = 29) and those that fully recovered (n = 16). Plasma samples from the two groups were analyzed via mass spectrometry-based untargeted metabolomics and compared against plasma metabolic profiles of healthy control individuals (n = 30). Observational demographic and clinical data were retrospectively abstracted from the medical record. Compared to plasma of healthy controls or individuals who recovered from COVID-19, PASC plasma exhibited significantly higher free- and carnitine-conjugated mono-, poly-, and highly unsaturated fatty acids, accompanied by markedly lower levels of mono-, di- and tricarboxylates (pyruvate, lactate, citrate, succinate, and malate), polyamines (spermine) and taurine. Plasma from individuals who fully recovered from COVID-19 exhibited an intermediary metabolic phenotype, with milder disturbances in fatty acid metabolism and higher levels of spermine and taurine. Of note, depletion of tryptophan-a hallmark of disease severity in COVID-19-is not normalized in PASC patients, despite normalization of kynurenine levels-a tryptophan metabolite that predicts mortality in hospitalized COVID-19 patients. In conclusion, PASC plasma metabolites are indicative of altered fatty acid metabolism and dysfunctional mitochondria-dependent lipid catabolism. These metabolic profiles obtained at rest are consistent with previously reported mitochondrial dysfunction during exercise, and may pave the way for therapeutic intervention focused on restoring mitochondrial fat-burning capacity.

Dichloroacetate improves systemic energy balance and feeding behavior during sepsis

Sepsis is a life-threatening organ dysfunction caused by dysregulated host response to an infection. The metabolic aberrations associated with sepsis underly an acute and organism-wide hyperinflammatory response and multiple organ dysfunction; however, crosstalk between systemic metabolomic alterations and metabolic reprogramming at organ levels remains unknown. We analyzed substrate utilization by the respiratory exchange ratio, energy expenditure, metabolomic screening, and transcriptional profiling in a cecal ligation and puncture model to show that sepsis increases circulating free fatty acids and acylcarnitines but decreases levels of amino acids and carbohydrates, leading to a drastic shift in systemic fuel preference. Comparative analysis of previously published metabolomics from septic liver indicated a positive correlation with hepatic and plasma metabolites during sepsis. In particular, glycine deficiency was a common abnormality of the plasma and liver during sepsis. Interrogation of the hepatic transcriptome in septic mice suggested that the septic liver may contribute to systemic glycine deficiency by downregulating genes involved in glycine synthesis. Interestingly, intraperitoneal injection of the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate reversed sepsis-induced anorexia, energy imbalance, inflammation, dyslipidemia, hypoglycemia, and glycine deficiency. Collectively, our data indicated that PDK inhibition rescued systemic energy imbalance and metabolic dysfunction in sepsis partly through restoration of hepatic fuel metabolism.

Patient Stratification in Sepsis: Using Metabolomics to Detect Clinical Phenotypes, Sub-Phenotypes and Therapeutic Response

Infections are common and need minimal treatment; however, occasionally, due to inappropriate immune response, they can develop into a life-threatening condition known as sepsis. Sepsis is a global concern with high morbidity and mortality. There has been little advancement in the treatment of sepsis, outside of antibiotics and supportive measures. Some of the difficulty in identifying novel therapies is the heterogeneity of the condition. Metabolic phenotyping has great potential for gaining understanding of this heterogeneity and how the metabolic fingerprints of patients with sepsis differ based on survival, organ dysfunction, disease severity, type of infection, treatment or causative organism. Moreover, metabolomics offers potential for patient stratification as metabolic profiles obtained from analytical platforms can reflect human individuality and phenotypic variation. This article reviews the most relevant metabolomic studies in sepsis and aims to provide an overview of the metabolic derangements in sepsis and how metabolic phenotyping has been used to identify sub-groups of patients with this condition. Finally, we consider the new avenues that metabolomics could open, exploring novel phenotypes and untangling the heterogeneity of sepsis, by looking at advances made in the field with other -omics technologies.

Managing sepsis in the era of precision medicine: challenges and opportunities

INTRODUCTION

Precision medicine is a medical model in which decisions, practices, interventions and therapies are tailored to the individual patient based on their predicted response or risk of disease. Sepsis is a life-threatening condition characterized by immune system dysregulation whose pathophysiology remains incompletely understood. There is much hope that precision medicine can lead to better outcomes in patients with sepsis.

AREAS COVERED

In this review from a comprehensive literature search in PubMed for English-language studies conducted in adults, we highlight recent advances in the diagnosis and treatment of sepsis of bacterial origin in adults using precision medicine approaches including rapid diagnostic tests, predictive biomarkers, genomic methods, rapid antimicrobial susceptibility testing, and monitoring cell mediated immunity. Challenges and directions for future research are also discussed.

EXPERT OPINION

Current diagnostic testing in sepsis relies primarily on conventional cultures (e.g. blood cultures), which are time-consuming and may delay critical therapeutic decisions. Nonculture-based techniques including nucleic acid amplification technologies (NAAT), other molecular methods (biomarkers), and genomic sequencing offer promise to overcome some of the inherent limitations seen with culture-based techniques.

Serum Levels of Acylcarnitines and Amino Acids Are Associated with Liberation from Organ Support in Patients with Septic Shock

Sepsis-induced metabolic dysfunction is associated with mortality, but the signatures that differentiate variable clinical outcomes among survivors are unknown. Our aim was to determine the relationship between host metabolism and chronic critical illness (CCI) in patients with septic shock. We analyzed metabolomics data from mechanically ventilated patients with vasopressor-dependent septic shock from the placebo arm of a recently completed clinical trial. Baseline serum metabolites were measured by liquid chromatography-mass spectrometry and ¹H-nuclear magnetic resonance. We conducted a time-to-event analysis censored at 28 days. Specifically, we determined the relationship between metabolites and time to extubation and freedom from vasopressors using a competing risk survival model, with death as a competing risk. We also compared metabolite concentrations between CCI patients, defined as intensive care unit level of care ≥ 14 days, and those with rapid recovery. Elevations in two acylcarnitines and four amino acids were related to the freedom from organ support (subdistributional hazard ratio < 1 and false discovery rate < 0.05). Proline, glycine, glutamine, and methionine were also elevated in patients who developed CCI. Our work highlights the need for further testing of metabolomics to identify patients at risk of CCI and to elucidate potential mechanisms that contribute to its etiology.

The supplementation of L-carnitine in septic shock patients: Systematic review and meta-analysis

BACKGROUND

Sepsis and septic shock are severe and difficult-to-treat conditions with high lethality. There is interest in identifying new adjunct therapies that are effective in reducing mortality. In this context, L-carnitine has been investigated in trials as a potentially beneficial drug. Therefore, the aim of this systematic review was to assess the clinical evidence to support the use of L-carnitine in septic shock patients to reduce the risk of mortality. The objective of this review was to evaluate the effect of L-carnitine compared to placebo or Usual Care (UC) on the mortality rate in hospitalized adult septic shock patients.

METHODS

The authors exclusively included randomized clinical trials that compared the use of L-carnitine versus placebo in adult (> 18 years old) septic shock patients. The outcome was a mortality rate of 28 days. This systematic review and meta-analysis were performed following the PRISMA guidelines and registered in PROSPERO with the ID CRD42020180499.

RESULTS

Following the initial search, 4007 citations were identified, with 2701 remaining after duplicate removal. Eight citations were selected for body text reading, and two were selected for inclusion. The studies enrolled 275 patients, with 186 in the carnitine arm and 89 in the placebo arm. The effect of L-carnitine uses in septic shock patients showed a difference risk of -0.03 (95% Confidence Interval: -0.15-0.10, I² = 77%, p = 0.69) compared to placebo/in mortality rate with low quality of evidence.

CONCLUSIONS

There is low-quality evidence that the use of L-carnitine has no significant effect on reducing 28-day mortality in septic shock patients.

Past Experiences for Future Applications of Metabolomics in Critically Ill Patients with Sepsis and Septic Shocks

A disruption of several metabolic pathways in critically ill patients with sepsis indicates that metabolomics might be used as a more precise tool for sepsis and septic shock when compared with the conventional biomarkers. This article provides information regarding metabolomics studies in sepsis and septic shock patients. It has been shown that a variety of metabolomic pathways are altered in sepsis and septic shock, including amino acid metabolism, fatty acid oxidation, phospholipid metabolism, glycolysis, and tricarboxylic acid cycle. Based upon this comprehensive review, here, we demonstrate that metabolomics is about to change the world of sepsis biomarkers, not only for its utilization in sepsis diagnosis, but also for prognosticating and monitoring the therapeutic response. Additionally, the future direction regarding the establishment of studies integrating metabolomics with other molecular modalities and studies identifying the relationships between metabolomic profiles and clinical characteristics to address clinical application are discussed in this article. All of the information from this review indicates the important impact of metabolomics as a tool for diagnosis, monitoring therapeutic response, and prognostic assessment of sepsis and septic shock. These findings also encourage further clinical investigations to warrant its use in routine clinical settings.

Gender-specific association of oxidative stress and immune response in septic shock mortality using NMR-based metabolomics

Background: Sepsis and septic shock are still associated with a high mortality rate. The early-stage prediction of septic shock outcomes would be helpful to clinicians for designing their treatment protocol. In addition, it would aid clinicians in patient management by understanding gender disparity in terms of clinical outcomes of septic shock by identifying whether there are sex-based differences in sepsis-associated mortality. Objective: This study aimed to test the hypothesis that gender-based metabolic heterogeneity is associated with sepsis survival and identify the biomarkers of mortality for septic shock in an Indian cohort. Method: The study was performed in an Indian population cohort diagnosed with sepsis/septic shock within 24 hours of admission. The study group was 50 patients admitted to intensive care, comprising 23 females and 27 males. Univariate and multivariate analysis were performed to identify the biomarkers for septic shock mortality and the gender-specific metabolic fingerprint in septic shock-associated mortality. Results: The energy-related metabolites, ketone bodies, choline, and NAG were found to be primarily responsible for differentiating survivors and non-survivors. The gender-based mortality stratification identified a female-specific association of the anti-inflammatory response, innate immune response, and β oxidation, and a male-specific association of the pro-inflammatory response to septic shock. Conclusion: The identified mortality biomarkers may help clinicians estimate the severity of a case, as well as predict the outcome and treatment efficacy. The study underlines that gender is one of the most significant biological factors influencing septic shock metabolomic profiles. This understanding can be utilized to identify novel gender-specific biomarkers and innovative targets relevant for gender medicine.

Metabolomic Characterization of Cerebrospinal Fluid from Intracranial Bacterial Infection Pediatric Patients: A Pilot Study

Intracranial bacterial infection remains a major cause of morbidity and mortality in neurosurgical cases. Metabolomic profiling of cerebrospinal fluid (CSF) holds great promise to gain insights into the pathogenesis of central neural system (CNS) bacterial infections. In this pilot study, we analyzed the metabolites in CSF of CNS infection patients and controls in a pseudo-targeted manner, aiming at elucidating the metabolic dysregulation in response to postoperative intracranial bacterial infection of pediatric cases. Untargeted analysis uncovered 597 metabolites, and screened out 206 differential metabolites in case of infection. Targeted verification and pathway analysis filtered out the glycolysis, amino acids metabolism and purine metabolism pathways as potential pathological pathways. These perturbed pathways are involved in the infection-induced oxidative stress and immune response. Characterization of the infection-induced metabolic changes can provide robust biomarkers of CNS bacterial infection for clinical diagnosis, novel pathways for pathological investigation, and new targets for treatment.

Group IIA secreted phospholipase A2 is associated with the pathobiology leading to COVID-19 mortality

There is an urgent need to identify the cellular and molecular mechanisms responsible for severe COVID-19 that results in death. We initially performed both untargeted and targeted lipidomics as well as focused biochemical analyses of 127 plasma samples and found elevated metabolites associated with secreted phospholipase A2 (sPLA2) activity and mitochondrial dysfunction in patients with severe COVID-19. Deceased COVID-19 patients had higher levels of circulating, catalytically active sPLA2 group IIA (sPLA2-IIA), with a median value that was 9.6-fold higher than that for patients with mild disease and 5.0-fold higher than the median value for survivors of severe COVID-19. Elevated sPLA2-IIA levels paralleled several indices of COVID-19 disease severity (e.g., kidney dysfunction, hypoxia, multiple organ dysfunction). A decision tree generated by machine learning identified sPLA2-IIA levels as a central node in the stratification of patients who died from COVID-19. Random forest analysis and least absolute shrinkage and selection operator-based (LASSO-based) regression analysis additionally identified sPLA2-IIA and blood urea nitrogen (BUN) as the key variables among 80 clinical indices in predicting COVID-19 mortality. The combined PLA-BUN index performed significantly better than did either one alone. An independent cohort (n = 154) confirmed higher plasma sPLA2-IIA levels in deceased patients compared with levels in plasma from patients with severe or mild COVID-19, with the PLA-BUN index-based decision tree satisfactorily stratifying patients with mild, severe, or fatal COVID-19. With clinically tested inhibitors available, this study identifies sPLA2-IIA as a therapeutic target to reduce COVID-19 mortality.

Pharmacometabolomics identifies candidate predictor metabolites of an L-carnitine treatment mortality benefit in septic shock

Sepsis‐induced metabolic dysfunction contributes to organ failure and death. L‐carnitine has shown promise for septic shock, but a recent phase II study of patients with vasopressor‐dependent septic shock demonstrated a non‐significant reduction in mortality. We undertook a pharmacometabolomics study of these patients (n = 250) to identify metabolic profiles predictive of a 90‐day mortality benefit from L‐carnitine. The independent predictive value of each pretreatment metabolite concentration, adjusted for L‐carnitine dose, on 90‐day mortality was determined by logistic regression. A grid‐search analysis maximizing the Z‐statistic from a binomial proportion test identified specific metabolite threshold levels that discriminated L‐carnitine responsive patients. Threshold concentrations were further assessed by hazard ratio and Kaplan‐Meier estimate. Accounting for L‐carnitine treatment and dose, 11 ¹H‐NMR metabolites and 12 acylcarnitines were independent predictors of 90‐day mortality. Based on the grid‐search analysis numerous acylcarnitines and valine were identified as candidate metabolites of drug response. Acetylcarnitine emerged as highly viable for the prediction of an L‐carnitine mortality benefit due to its abundance and biological relevance. Using its most statistically significant threshold concentration, patients with pretreatment acetylcarnitine greater than or equal to 35 µM were less likely to die at 90 days if treated with L‐carnitine (18 g) versus placebo (p = 0.01 by log rank test). Metabolomics also identified independent predictors of 90‐day sepsis mortality. Our proof‐of‐concept approach shows how pharmacometabolomics could be useful for tackling the heterogeneity of sepsis and informing clinical trial design. In addition, metabolomics can help understand mechanisms of sepsis heterogeneity and variable drug response, because sepsis induces alterations in numerous metabolite concentrations.

The lipid biology of sepsis

Sepsis, defined as the dysregulated immune response to an infection leading to organ dysfunction, is one of the leading causes of mortality around the globe. Despite the significant progress in delineating the underlying mechanisms of sepsis pathogenesis, there are currently no effective treatments or specific diagnostic biomarkers in the clinical setting. The perturbation of cell signaling mechanisms, inadequate inflammation resolution, and energy imbalance, all of which are altered during sepsis, are also known to lead to defective lipid metabolism. The use of lipids as biomarkers with high specificity and sensitivity may aid in early diagnosis and guide clinical decision making. In addition, identifying the link between specific lipid signatures and their role in sepsis pathology may lead to novel therapeutics. In this review, we discuss the recent evidence on dysregulated lipid metabolism both in experimental and human sepsis focused on bioactive lipids, fatty acids, and cholesterol as well as the enzymes regulating their levels during sepsis. We highlight not only their potential roles in sepsis pathogenesis but also the possibility of using these respective lipid compounds as diagnostic and prognostic biomarkers of sepsis.

Association Between Red Cell Distribution Width and Hospital Mortality in Patients with Sepsis

Objective

Sepsis is the leading cause of death in patients admitted to adult intensive care units (ICUs). We aimed to determine the predictive value of red blood cell distribution width (RDW) in patients with sepsis in a large cohort.

Methods

This retrospective observational study used data from the eICU Collaborative Research Database. The prognostic value of RDW was investigated using the receiver operating characteristic (ROC) curve, multiple logistic regression model, integrated discriminatory index (IDI), and net reclassification index (NRI).

Results

In total, 9743 patients were included. The area under the ROC curve of the RDW for predicting hospital mortality was 0.631 (95% confidence interval [CI]: 0.616–0.645). Based on the multiple logistic regression model, an RDW of ≥14.5% was correlated with hospital mortality, regardless of Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation IV (APACHE IV) scores (odds ratio [OR]: 1.838, 95% CI: 1.598–2.119). Using SOFA and APACHE IV scores as reference, the IDI and continuous NRI of RDW for hospital mortality was about 0.3 and 0.014, respectively.

Conclusions

The RDW may be useful in predicting hospital mortality in patients with sepsis, offering extra prognostic value beyond SOFA and APACHE IV scores.

Metabolome and lipidome derangements during a severe mast cell activation event in a patient with indolent systemic mastocytosis

BACKGROUND

The number of mast cells in various organs is elevated manifold in individuals with systemic mastocytosis. Degranulation can lead to life-threatening symptomatology. No data about the alterations of the metabolome and lipidome during an attack have been published.

OBJECTIVE

Our aim was to analyze changes in metabolomics and lipidomics during the acute phase of a severe mast cell activation event.

METHODS

A total of 43 metabolites and 11 lipid classes comprising 200 subvariants from multiple plasma samples in duplicate, covering 72 hours of a severe mast cell activation attack with nausea and vomiting, were compared with 2 baseline samples by using quantitative liquid chromatography-mass spectrometry.

RESULTS

A strong enterocyte dysfunction reflected in an almost 20-fold reduction in the functional small bowel length was extrapolated from strongly reduced ornithine and citrulline concentrations and was very likely secondary to severe endothelial cell dysfunction with hypoperfusion and extensive vascular leakage. Highly increased histamine and lactate concentrations accompanied the peak in clinical symptoms. Elevated asymmetric and symmetric dimethylarginine levels combined with reduced arginine levels compromised endothelial nitric oxide synthase activity and nitric oxide signaling. Specific and extensive depletion of many lysophosphatidylcholine variants indicates localized autotaxin activation and lysophosphatidic acid release. A strong correlation of clinical parameters with histamine concentrations and symptom reduction after 100-fold elevated plasma diamine oxidase concentrations implies that histamine is the key driver of the acute phase.

CONCLUSIONS

Rapid elimination of elevated histamine concentrations through use of recombinant human diamine oxidase, supplementation of lysophosphatidylcholine for immunomodulation, inhibition of autotaxin activity, and/or blockade of lysophosphatidic acid receptors might represent new treatment options for life-threatening mast cell activation events.

Group IIA Secreted Phospholipase A 2 Plays a Central Role in the Pathobiology of COVID-19

There is an urgent need to identify cellular and molecular mechanisms responsible for severe COVID-19 disease accompanied by multiple organ failure and high mortality rates. Here, we performed untargeted/targeted lipidomics and focused biochemistry on 127 patient plasma samples, and showed high levels of circulating, enzymatically active secreted phospholipase A ₂ Group IIA (sPLA ₂ -IIA) in severe and fatal COVID-19 disease compared with uninfected patients or mild illness. Machine learning demonstrated that sPLA ₂ -IIA effectively stratifies severe from fatal COVID-19 disease. We further introduce a PLA-BUN index that combines sPLA ₂ -IIA and blood urea nitrogen (BUN) threshold levels as a critical risk factor for mitochondrial dysfunction, sustained inflammatory injury and lethal COVID-19. With the availability of clinically tested inhibitors of sPLA ₂ -IIA, our study opens the door to a precision intervention using indices discovered here to reduce COVID-19 mortality.

Plasma Vanin-1 as a Novel Biomarker of Sepsis for Trauma Patients: A Prospective Multicenter Cohort Study

Introduction

Vanin-1 plays a pivotal role in oxidative stress and the inflammatory response. However, its relationship with traumatic sepsis remains unknown. The aim of our study was to evaluate whether plasma vanin-1 could be used for the early prediction of traumatic sepsis.

Methods

In this three-stage prospective cohort study, severe trauma patients admitted from January 2015 to October 2018 at two hospitals were enrolled. Plasma vanin-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). The associations among variables and traumatic sepsis were identified by logistic regression models and the receiver operating characteristic (ROC) curve was analyzed to evaluate the diagnostic efficiency.

Results

A total of 426 trauma patients (22 in the discovery cohort, 283 in the internal test cohort, and 121 in the external validation cohort) and 16 healthy volunteers were recruited. The plasma vanin-1 of trauma patients was significantly higher than that of healthy volunteers (P < 0.05). Patients with sepsis had higher plasma vanin-1 than patients without sepsis in the discovery trauma cohort (P < 0.05). In the internal test cohort, plasma vanin-1 at day 1 after trauma was significantly associated with the incidence of sepsis (OR = 3.92, 95% CI 2.68–5.72, P = 1.62 × 10⁻¹²). As a predictive biomarker, vanin-1 afforded a better area under the curve (AUC) (0.82, 95% CI 0.77–0.87) than C-reaction protein (CRP) (0.62, 95% CI 0.56–0.68, P < 0.0001), procalcitonin (PCT) (0.66, 95% CI 0.60–0.71, P < 0.0001), and Acute Physiology and Chronic Health Evaluation II (APACHE II) (0.71, 95% CI 0.65–0.76, P = 6.70 × 10⁻³). The relevance was further validated in the external validation cohort (OR = 4.26, 95% CI 2.22–8.17, P = 1.28 × 10⁻⁵), with an AUC of 0.83 (95% CI 0.75–0.89). Vanin-1 could also improve the diagnostic efficiency of APACHE II (AUC = 0.85).

Conclusions

Our study demonstrated that plasma vanin-1 increased among trauma patients and was independently associated with the risk of sepsis. Vanin-1 might be a potential biomarker for the early prediction of traumatic sepsis.

Trial Registration

Clinicaltrials.gov Identifier, NCT01713205.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00414-w.

L-Carnitine and Acylcarnitines: Mitochondrial Biomarkers for Precision Medicine

Biomarker discovery and implementation are at the forefront of the precision medicine movement. Modern advances in the field of metabolomics afford the opportunity to readily identify new metabolite biomarkers across a wide array of disciplines. Many of the metabolites are derived from or directly reflective of mitochondrial metabolism. L-carnitine and acylcarnitines are established mitochondrial biomarkers used to screen neonates for a series of genetic disorders affecting fatty acid oxidation, known as the inborn errors of metabolism. However, L-carnitine and acylcarnitines are not routinely measured beyond this screening, despite the growing evidence that shows their clinical utility outside of these disorders. Measurements of the carnitine pool have been used to identify the disease and prognosticate mortality among disorders such as diabetes, sepsis, cancer, and heart failure, as well as identify subjects experiencing adverse drug reactions from various medications like valproic acid, clofazimine, zidovudine, cisplatin, propofol, and cyclosporine. The aim of this review is to collect and interpret the literature evidence supporting the clinical biomarker application of L-carnitine and acylcarnitines. Further study of these metabolites could ultimately provide mechanistic insights that guide therapeutic decisions and elucidate new pharmacologic targets.

Metabolomics: An emerging potential approach to decipher critical illnesses

Critical illnesses contribute to the maximum morbidity and mortality of hospitalized patients. Acute respiratory distress syndrome (ARDS) and sepsis/septic shock are the two most common acute illnesses associated with intensive care unit (ICU) admission. Once triggered, both have an identical underlying mechanism, portrayed by inflammation and endothelial dysfunction. The diagnosis of ARDS is based on clinical findings, laboratory tests, and radiological imaging. Blood cultures remain the gold standard for the diagnosis of sepsis, with the limitation of time delay and low positive yield. A combination of biomarkers has been proposed to diagnose and prognosticate these acute disorders with strengths and limitations, but still, the gold standard has been elusive to clinicians. In this review article, we illustrate the potential of metabolomics to unravel biomarkers that can be clinically utilized as a rapid prognostic and diagnostic tool associated with specific patient populations (ARDS and sepsis/septic shock) based on the available scientific data.

Ultrahigh throughput beehive-like device for blood plasma separation

We report here a low-cost, rapid-prototyping, and beehive-like multilayer polymer microfluidic device for ultrahigh-throughput blood plasma separation. To understand the device physics and optimize the device structure, the effect of cross-sectional dimension and operational parameter on particle focusing behavior was explored using a single spiral microchannel device. Then, the blood plasma separation performance of the determined channel structure was validated using the blood samples with different hematocrits (HCTs). It was found that a high separation efficiency of 99% could be achieved using the blood sample with an HCT of 0.5% at a high throughput of 1 mL/min. Finally, a multilayer microfluidic device with a novel beehive-like multiplexing channel arrangement was developed for ultrahigh-throughput blood plasma separation. The prototype device could be fabricated within ∼1 hour utilizing the laser cutting and thermal lamination methods. The total processing throughput could reach up to 72 mL/min for 0.5% HCT sample with a plasma separation ratio close to 90%. Our device may hold potentials for the ultrahigh-throughput separation of blood plasma from large volume blood samples for downstream disease diagnosis.

Title NMR-based metabolic profiling provides diagnostic and prognostic information in critically ill children with suspected infection

Sepsis, defined as life-threatening organ dysfunction caused by infection is difficult to distinguish clinically from infection or post-operative inflammation. We hypothesized that in a heterogeneous group of critically ill children, there would be different metabolic profiles between post-operative inflammation, bacterial and viral infection and infection with or without organ dysfunction. 1D ¹H nuclear magnetic resonance spectra were acquired in plasma samples from critically ill children. We included children with bacterial (n = 25) and viral infection (n = 30) and controls (n = 58) (elective cardiac surgery without infection). Principal component analysis was used for data exploration and partial least squares discriminant analysis models for the differences between groups. Area under receiver operating characteristic curve (AUC) values were used to evaluate the models. Univariate analysis demonstrated differences between controls and bacterial and viral infection. There was excellent discrimination between bacterial and control (AUC = 0.94), and viral and control (AUC = 0.83), with slightly more modest discrimination between bacterial and viral (AUC = 0.78). There was modest discrimination (AUC = 0.73) between sepsis with organ dysfunction and infection with no organ dysfunction. In critically ill children, NMR metabolomics differentiates well between those with a post-operative inflammation but no infection, and those with infection (bacterial and viral), and between sepsis and infection.

Using l-Carnitine as a Pharmacologic Probe of the Interpatient and Metabolic Variability of Sepsis

OBJECTIVE

The objective of this review is to discuss the therapeutic use and differential treatment response to Levo-carnitine (l-carnitine) treatment in septic shock, and to demonstrate common lessons learned that are important to the advancement of precision medicine approaches to sepsis. We propose that significant interpatient variability in the metabolic response to l-carnitine and clinical outcomes can be used to elucidate the mechanistic underpinnings that contribute to sepsis heterogeneity.

METHODS

A narrative review was conducted that focused on explaining interpatient variability in l-carnitine treatment response. Relevant biological and patient-level characteristics considered include genetic, metabolic, and morphomic phenotypes; potential drug interactions; and pharmacokinetics (PKs).

MAIN RESULTS

Despite promising results in a phase I study, a recent phase II clinical trial of l-carnitine treatment in septic shock showed a nonsignificant reduction in mortality. However, l-carnitine treatment induces significant interpatient variability in l-carnitine and acylcarnitine concentrations over time. In particular, administration of l-carnitine induces a broad, dynamic range of serum concentrations and measured peak concentrations are associated with mortality. Applied systems pharmacology may explain variability in drug responsiveness by using patient characteristics to identify pretreatment phenotypes most likely to derive benefit from l-carnitine. Moreover, provocation of sepsis metabolism with l-carnitine offers a unique opportunity to identify metabolic response signatures associated with patient outcomes. These approaches can unmask latent metabolic pathways deranged in the sepsis syndrome and offer insight into the pathophysiology, progression, and heterogeneity of the disease.

CONCLUSIONS

The compiled evidence suggests there are several potential explanations for the variability in carnitine concentrations and clinical response to l-carnitine in septic shock. These serve as important confounders that should be considered in interpretation of l-carnitine clinical studies and broadly holds lessons for future clinical trial design in sepsis. Consideration of these factors is needed if precision medicine in sepsis is to be achieved.

The Effect of L-Carnitine on Mortality Rate in Septic Patients: A Systematic Review and Meta-Analysis on Randomized Clinical Trials

BACKGROUND

Recent clinical trial studies have reported that L-carnitine supplementation can reduce the mortality rate in patients with sepsis, but there are no definitive results in this context. The current systematic review and meta-analysis aimed to evaluate the effect of L-carnitine supplementation on 28-day and one-year mortality in septic patients.

METHODS

A systematic search conducted on Pubmed, Scopus and Cochrane Library databases up to June 2019 without any language restriction. The publications were reviewed based on the Cochrane handbook and preferred reporting items for systematic reviews and meta-analyses (PRISMA). To compare the effects of L-carnitine with placebo, Risk Ratio (RR) with 95% confidence intervals (CI) were pooled according to the random effects model.

RESULTS

Across five enrolled clinical trials, we found that L-carnitine supplementation reduce one-year mortality in septic patients with SOFA> 12 (RR: 0.68; 95% CI: 0.49 to 0.96; P= 0.03) but had no significant effect on reducing 28-day mortality ((RR: 0.93; 95% CI: 0.68 to 1.28; P= 0.65) compared to placebo. Finally, we observed that based on current trials, L-carnitine supplementation may not have clinically a significant effect on mortality rate.

CONCLUSION

L-carnitine patients with higher SOFA score can reduce the mortality rate. However, the number of trials, study duration and using a dosage of L-carnitine are limited in this context and further large prospective trials are required to clarify the effect of L-carnitine on mortality rate in septic patients.

Prediction of sepsis mortality using metabolite biomarkers in the blood: a meta-analysis of death-related pathways and prospective validation

BACKGROUND

Sepsis is a leading cause of death in intensive care units (ICUs), but outcomes of individual patients are difficult to predict. The recently developed clinical metabolomics has been recognized as a promising tool in the clinical practice of critical illness. The objective of this study was to identify the unique metabolic biomarkers and their pathways in the blood of sepsis nonsurvivors and to assess the prognostic value of these pathways.

METHODS

We searched PubMed, EMBASE, Cochrane, Web of Science, CNKI, Wangfang Data, and CQVIP from inception until July 2019. Eligible studies included the metabolomic analysis of blood samples from sepsis patients with the outcome. The metabolic pathway was assigned to each metabolite biomarker. The meta-analysis was performed using the pooled fold changes, area under the receiver operating characteristic curve (AUROC), and vote-counting of metabolic pathways. We also conducted a prospective cohort metabolomic study to validate the findings of our meta-analysis.

RESULTS

The meta-analysis included 21 cohorts reported in 16 studies with 2509 metabolite comparisons in the blood of 1287 individuals. We found highly limited overlap of the reported metabolite biomarkers across studies. However, these metabolites were enriched in several death-related metabolic pathways (DRMPs) including amino acids, mitochondrial metabolism, eicosanoids, and lysophospholipids. Prediction of sepsis death using DRMPs yielded a pooled AUROC of 0.81 (95% CI 0.76-0.87), which was similar to the combined metabolite biomarkers with a merged AUROC of 0.82 (95% CI 0.78-0.86) (P > 0.05). A prospective metabolomic analysis of 188 sepsis patients (134 survivors and 54 nonsurvivors) using the metabolites from DRMPs produced an AUROC of 0.88 (95% CI 0.78-0.97). The sensitivity and specificity for the prediction of sepsis death were 80.4% (95% CI 66.9-89.4%) and 78.8% (95% CI 62.3-89.3%), respectively.

CONCLUSIONS

DRMP analysis minimizes the discrepancies of results obtained from different metabolomic methods and is more practical than blood metabolite biomarkers for sepsis mortality prediction.

TRIAL REGISTRATION

The meta-analysis was registered on OSF Registries, and the prospective cohort study was registered on the Chinese Clinical Trial Registry (ChiCTR1800015321).

Association of acyl carnitines and mortality in out-of-hospital-cardiac-arrest patients: Results of a prospective observational study

PURPOSE

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality, yet the prediction of its outcome remains challenging. Serum Acyl Carnitines (ACs), a biomarker of beta-oxidation, have been associated with cardiovascular events. We evaluated the association of different AC species with mortality and neurological outcome in a cohort of OHCA patients.

MATERIAL AND METHODS

We consecutively included OHCA patients in this prospective observational study upon admission to the intensive care unit. We studied the association of thirty-nine different ACs measured at admission and 30-day mortality (primary endpoint), as well as neurological outcome at hospital discharge (secondary endpoint) using the Cerebral Performance Category scale. Multivariate models were adjusted for age, gender, comorbidities and shock markers.

RESULTS

Of 281 included patients, 137 (48.8%) died within 30 days and of the 144 survivors (51.2%), 15 (10.4%) had poor neurological outcome. While several ACs were associated with mortality, AC C2 had the highest prognostic value for mortality (fully-adjusted odds ratio 4.85 (95%CI 1.8 to 13.06, p < .01), area under curve (AUC) 0.65) and neurological outcome (fully-adjusted odds ratio 3.96 (95%CI 1.47 to 10.66, p < .01), AUC 0.63).

CONCLUSIONS

ACs are interesting surrogate biomarkers that are associated with mortality and poor neurological outcome in patients after OHCA and may help to improve the understanding of pathophysiological mechanisms and risk stratification.

A Multivariate Metabolomics Method for Estimating Platelet Mitochondrial Oxygen Consumption Rates in Patients with Sepsis

BACKGROUND

Sepsis-induced alterations in mitochondrial function contribute to organ dysfunction and mortality. Measuring mitochondrial function in vital organs is neither feasible nor practical, highlighting the need for non-invasive approaches. Mitochondrial function may be reflected in the concentrations of metabolites found in platelets and whole blood (WB) samples. We proposed to use these as alternates to indirectly estimate platelet mitochondrial oxygen consumption rate (mOCR) in sepsis patients.

METHODS

We determined the relationships between platelet mOCR and metabolites in both platelets and WB, as measured by quantitative 1H-NMR metabolomics. The associations were identified by building multiple linear regression models with stepwise forward-backward variable selection. We considered the models to be significant with an ANOVA test (p-value ≤ 0.05) and a positive predicted-R2.

RESULTS

The differences in adjusted-R2 and ANOVA p-values (platelet adj-R2: 0.836 (0.0003), 0.711 (0.0004) vs. WB adj-R2: 0.428 (0.0079)) from the significant models indicate the platelet models were more associated with platelet mOCR.

CONCLUSIONS

Our data suggest there are groups of metabolites in WB (leucine, acetylcarnitine) and platelets (creatine, ADP, glucose, taurine) that are associated with platelet mOCR. Thus, WB and platelet metabolites could be used to estimate platelet mOCR.

Simultaneous quantification of free fatty acids and acylcarnitines in plasma samples using dansylhydrazine labeling and liquid chromatography-triple quadrupole mass spectrometry

Free fatty acid (FFA) and acylcarnitine (AcCar) are key elements of energy metabolism. Dysregulated levels of FFA and AcCar are associated with genetic defects and other metabolic disorders. Due to differences in the physicochemical properties of these two classes of compounds, it is challenging to quantify FFA and AcCar in human plasma using a single method. In this work, we developed a chemical isotope labeling (CIL)-based liquid chromatography-multiple reaction monitoring (LC-MRM) method to simultaneously quantify FFA and AcCar. Dansylhydrazine (DnsHz) was used to label the carboxylic acid moiety on FFA and AcCar. This resulted in the formation of a permanently charged ammonium ion for facile ionization in positive ionization mode and higher hydrophobicity for enhanced retention of short-chain analogs on reversed-phase LC columns and enabled absolute quantification by using heavy labeled DnsHz analogs as internal standards. Labeling conditions including the concentration and freshness of cross-linker, reaction time, and temperature were optimized. This method can successfully quantify all short-, medium- and long-chain FFAs and AcCars with greatly enhanced sensitivity. Using this method, 25 FFAs and 13 AcCars can be absolutely quantified and validated in human plasma samples within 12 min. Simultaneous quantification of FFA and AcCar enabled by this CIL-based LC-MRM method facilitates the investigation of fatty acid metabolism and has potential in clinical applications.

Host Metabolic Response in Early Lyme Disease

Lyme disease is a tick-borne bacterial illness that occurs in areas of North America, Europe, and Asia. Early infection typically presents as generalized symptoms with an erythema migrans (EM) skin lesion. Dissemination of the pathogen Borrelia burgdorferi can result in multiple EM skin lesions or in extracutaneous manifestations such as Lyme neuroborreliosis. Metabolic biosignatures of patients with early Lyme disease can potentially provide diagnostic targets as well as highlight metabolic pathways that contribute to pathogenesis. Sera from well-characterized patients diagnosed with either early localized Lyme disease (ELL) or early disseminated Lyme disease (EDL), plus healthy controls (HC), from the United States were analyzed by liquid chromatography-mass spectrometry (LC-MS). Comparative analyses were performed between ELL, or EDL, or ELL combined with EDL, and the HC to develop biosignatures present in early Lyme disease. A direct comparison between ELL and EDL was also performed to develop a biosignature for stages of early Lyme disease. Metabolic pathway analysis and chemical identification of metabolites with LC-tandem mass spectrometry (LC-MS/MS) demonstrated alterations of eicosanoid, bile acid, sphingolipid, glycerophospholipid, and acylcarnitine metabolic pathways during early Lyme disease. These metabolic alterations were confirmed using a separate set of serum samples for validation. The findings demonstrated that infection of humans with B. burgdorferi alters defined metabolic pathways that are associated with inflammatory responses, liver function, lipid metabolism, and mitochondrial function. Additionally, the data provide evidence that metabolic pathways can be used to mark the progression of early Lyme disease.