Metabolites Associated With Malnutrition in the Intensive Care Unit Are Also Associated With 28-Day Mortality

Comparison of Mini Nutritional Assessment Tool and Geriatric Nutrition Risk Index in Predicting 12-Y Mortality Among Community-Dwelling Older Persons

BACKGROUND

Malnutrition is a common and dangerous condition in older adults, which has been associated with increased risk of mortality.

OBJECTIVES

This study aimed to evaluate and compare the abilities of Mini Nutritional Assessment short form (MNA-SF), MNA full form (MNA-FF), and geriatric nutritional risk index (GNRI) to predict all-cause and expanded cardiovascular disease (CVD)-related mortality in community-dwelling older adults.

METHODS

This research was an observational cohort study conducted in a community setting, with a 12-y follow-up involving 1001 community-living older adults aged 65 y or older who were enrolled in 2009 and followed up until 2021. Nutritional status assessment was carried out in 2009 using MNA-SF, MNA-FF, and GNRI. Multivariate Cox proportional hazards regression was applied to determine adjusted hazard ratios of mortality with 95% CIs.

RESULTS

A total of 368 deaths (36.76%) and 122 expanded CVD-related deaths (12.19%) were observed after a median follow-up of 12 y. Compared with normal nutritional status, poor nutritional status assessed by the MNA-SF, MNA-FF, and GNRI was found to be associated with an increased all-cause mortality in older persons. MNA-SF and MNA-FF, but not GNRI, were associated with expanded CVD-related mortality. The MNA-FF showed better discriminatory accuracy for all-cause (C-statistics: 0.77; 95% CI: 0.63, 0.79) and expanded CVD-related mortality (C-statistics: 0.79; 95% CI: 0.70, 0.83) than MNA-SF (C-statistics: 0.76; 95% CI: 0.73-0.79; and C-statistics: 0.76; 95% CI: 0.72-0.81, respectively) and GNRI (C-statistics: 0.75; 95% CI: 0.73-0.79; and C-statistics: 0.76; 95% CI: 0.72-0.80, respectively).

CONCLUSIONS

Our findings indicate that MNA-SF, MNA-FF, and GNRI were all independent predictors of all-cause mortality. In particular, the MNA-FF may be the best nutritional assessment tool for predicting all-cause and CVD-related mortality among older persons residing in community, compared with MNA-SF and GNRI.

Mendelian Randomization Study on Causal Association of Pyroglutamine with COVID-19

Background

Glutamine family amino acids such as glutamate, pyroglutamate, and glutamine have been shown to play important roles in COVID-19. However, it is still unclear about the role of pyroglutamate in COVID-19. Thus, we use a two-sample Mendelian randomization (MR) study to identify the genetic causal link between blood pyroglutamine levels and COVID-19 risk.

Methods

Pyroglutamine genetic instrumental variables (IVs) were chosen from the largest pyroglutamine-associated genome-wide association studies (GWAS). The largest COVID-19 GWAS dataset was employed to evaluate the causal link between blood pyroglutamine levels and COVID-19 risk using two-sample MR analysis.

Results

We found no significant pleiotropy or heterogeneity of pyroglutamine-associated genetic IVs in COVID-19 GWAS. Interestingly, we found that as pyroglutamine genetically increased, the risk of COVID-19 decreased using inverse variance weighted (IVW) (Beta = − 0.644, p = 0.003; OR = 0.525, 95% CI [0.346–0.798]) and weighted median (Beta = − 0.609, p = 0.013; OR = 0.544, 95% CI [0.337–0.878]).

Conclusion

Our analysis suggests a causal link between genetically increased pyroglutamine and reduced risk of COVID-19. Thus, pyroglutamine may be a protective factor for patients with COVID-19.

The Combined Escherichia coli Nissle 1917 and Tryptophan Treatment Modulates Immune and Metabolome Responses to Human Rotavirus Infection in a Human Infant Fecal Microbiota-Transplanted Malnourished Gnotobiotic Pig Model

Human rotavirus (HRV) is a major cause of childhood diarrhea in developing countries where widespread malnutrition contributes to the decreased oral vaccine efficacy and increased prevalence of other enteric infections, which are major concerns for global health. Neonatal gnotobiotic (Gn) piglets closely resemble human infants in their anatomy, physiology, and outbred status, providing a unique model to investigate malnutrition, supplementations, and HRV infection. To understand the molecular signatures associated with immune enhancement and reduced diarrheal severity by Escherichia coli Nissle 1917 (EcN) and tryptophan (TRP), immunological responses and global nontargeted metabolomics and lipidomics approaches were investigated on the plasma and fecal contents of malnourished pigs transplanted with human infant fecal microbiota and infected with virulent (Vir) HRV. Overall, EcN + TRP combined (rather than individual supplement action) promoted greater and balanced immunoregulatory/immunostimulatory responses associated with greater protection against HRV infection and disease in malnourished humanized piglets. Moreover, EcN + TRP treatment upregulated the production of several metabolites with immunoregulatory/immunostimulatory properties: amino acids (N-acetylserotonin, methylacetoacetyl-CoA), lipids (gamma-butyrobetaine, eicosanoids, cholesterol-sulfate, sphinganine/phytosphingosine, leukotriene), organic compound (biliverdin), benzenoids (gentisic acid, aminobenzoic acid), and nucleotides (hypoxathine/inosine/xanthine, cytidine-5'-monophosphate). Additionally, the levels of several proinflammatory metabolites of organic compounds (adenosylhomocysteine, phenylacetylglycine, urobilinogen/coproporphyrinogen) and amino acid (phenylalanine) were reduced following EcN + TRP treatment. These results suggest that the EcN + TRP effects on reducing HRV diarrhea in neonatal Gn pigs were at least in part due to altered metabolites, those involved in lipid, amino acid, benzenoids, organic compounds, and nucleotide metabolism. Identification of these important mechanisms of EcN/TRP prevention of HRV diarrhea provides novel targets for therapeutics development. IMPORTANCE Human rotavirus (HRV) is the most common cause of viral gastroenteritis in children, especially in developing countries, where the efficacy of oral HRV vaccines is reduced. Escherichia coli Nissle 1917 (EcN) is used to treat enteric infections and ulcerative colitis while tryptophan (TRP) is a biomarker of malnutrition, and its supplementation can alleviate intestinal inflammation and normalize intestinal microbiota in malnourished hosts. Supplementation of EcN + TRP to malnourished humanized gnotobiotic piglets enhanced immune responses and resulted in greater protection against HRV infection and diarrhea. Moreover, EcN + TRP supplementation increased the levels of immunoregulatory/immunostimulatory metabolites while decreasing the production of proinflammatory metabolites in plasma and fecal samples. Profiling of immunoregulatory and proinflammatory biomarkers associated with HRV perturbations will aid in the identification of treatments against HRV and other enteric diseases in malnourished children.

The emerging roles of next-generation metabolomics in critical care nutrition

Critical illness leads to millions of deaths worldwide each year, with a significant surge due to the COVID-19 pandemic. Patients with critical illness are frequently associated with systemic metabolic disorders and malnutrition. The idea of intervention for critically ill patients through enteral and parenteral nutrition has been paid more and more attention gradually. However, current nutritional therapies focus on evidence-based practice, and there have been lacking holistic approaches for nutritional support assessment. Metabolomics is a well-established omics technique in system biology that enables comprehensive profiling of metabolites in a biological system and thus provides the underlying information expressed and modulated by all other omics layers. In recent years, with the development of high-resolution and accurate mass spectrometry, metabolomics entered a new "generation", promoting its broader applications in critical care nutrition. In this review, we first described the technological development and milestones of next-generation metabolomics in the past 20 years. We then discussed the emerging roles of next-generation metabolomics in advancing our understanding of critical care nutrition, such as nutritional deficiency risk evaluation, metabolic mechanisms of nutritional therapies, and novel nutrition target identification.

Severe COVID-19 Is Characterised by Perturbations in Plasma Amines Correlated with Immune Response Markers, and Linked to Inflammation and Oxidative Stress

The COVID-19 pandemic raised a need to characterise the biochemical response to SARS-CoV-2 infection and find biological markers to identify therapeutic targets. In support of these aims, we applied a range of LC-MS platforms to analyse over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). The first publication in a series reports the results of quantitative LC-MS/MS profiling of 56 amino acids and derivatives. A comparison between samples taken from ICU and ward patients revealed a notable increase in ten post-translationally modified amino acids that correlated with markers indicative of an excessive immune response: TNF-alpha, neutrophils, markers for macrophage, and leukocyte activation. Severe patients also had increased kynurenine, positively correlated with CRP and cytokines that induce its production. ICU and ward patients with high IL-6 showed decreased levels of 22 immune-supporting and anti-oxidative amino acids and derivatives (e.g., glutathione, GABA). These negatively correlated with CRP and IL-6 and positively correlated with markers indicative of adaptive immune activation. Including corresponding alterations in convalescing ward patients, the overall metabolic picture of severe COVID-19 reflected enhanced metabolic demands to maintain cell proliferation and redox balance, alongside increased inflammation and oxidative stress.

New body mass index for predicting prognosis in patients with antineutrophil cytoplasmic antibody‐associated vasculitis

Objectives

Method

Results

Conclusion

The metabolic effects of multi-trace elements on parenteral nutrition for critically ill pediatric patients: a randomized controlled trial and metabolomic research

BACKGROUND

We investigated the efficacy and metabolic dose-effect of multi-trace element injection I [MTEI-(I)] for severe pediatric patients via a parallel, randomized control study.

METHODS

The inclusion criteria were as follows: (I) patients who required parenteral nutrition (PN) due to various diseases, and were expected to receive PN for >5 days; (II) patients aged <18 years; (III) patients with no serious cardiac, hepatic, renal, or pulmonary dysfunction; and (IV) patients with an established central venous pathway. Enrolled patients were randomly assigned into two groups using sequentially numbered, sealed, opaque envelopes: Group A (low-dose group) received MTEI-(I) at 1 mL/kg/d, and Group B (high-dose group) received MTEI-(I) at 2 mL/kg/d, up to a maximum dose of 15 mL/d. The concentrations of manganese (Mn), copper (Cu), zinc (Zn), and selenium (Se) were detected. The following indexes were measured after 5 days of treatment (T5): β-oxidation of very-long-chain fatty acids, arginine and proline metabolism, pentose phosphate metabolism, ketone body metabolism, citric acid cycle, purine metabolism, caffeine metabolism, and pyruvate metabolism. The participants, care givers, and data analysis staff were blinded to the group assignment.

RESULTS

Overall, at T5, Mn and Cu levels were decreased, while Zn and Se levels were increased. The increase of Zn levels (A: 0.170±0.479 vs. B: 0.193±0.900) and decrease of Cu levels (A: -0.240±0.382 vs. B: -0.373±0.465) of patients in Group B (n=22) were significantly higher than those in Group A (n=18). At T5, the β-oxidation of very-long-chain fatty acids, arginine and proline metabolism, pentose phosphate metabolism, ketone body metabolism, citric acid cycle, purine metabolism, caffeine metabolism, and pyruvate metabolism were variably decreased (P<0.05) in Group B compared to Group A.

CONCLUSIONS

Our results suggested that the high-dose administration of MTEI-(I) is safe for severe pediatric patients, and may alleviate inflammation and antioxidation, relieve hyperactivity caused by stress, and improve tissues-based hypoxia and renal function.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100052198.

Can feeding strategies alter immune signaling and gut sepsis in critical illness?

The insult necessitating admission to the intensive care unit propels the patient along a course involving increasing oxidative stress, immune dysregulation, and adverse outcomes. As the largest immune organ with the greatest microbial burden, the gastrointestinal tract may change the speed and direction the patient follows along this pathway. The gut's influence is mediated by a complex process of cross-talk immune signaling between the intestinal epithelium, the liver, and the microbiome. Agents which invoke this response vary from mitochondrial DNA, inflammatory cytokines, and bacterial organisms to short chain fatty acids and bile salts. The site of action of these agents again varies widely from Pattern Recognition Receptors, G protein receptors, and Farnesoid X receptors in the gut and liver to transcriptional factors in epithelial cells, hepatocytes, macrophages, and neutrophils. While the initial focus of response may be local within the gastrointestinal tract and liver, the process extends in a systemic manner to affect immune tissue and various organs at distant sites. The gut can modulate this cross-talk signaling through numerous strategies in design of nutritional therapy. The physiologic response to luminal nutrients and short chain fatty acids, and more novel approaches like use phosphorylated polyethylene glycol, bovine serum-derived immunoglobulin, and specialized pro-resolving molecules may help slow disease progression and even reverse the patient's course toward one of health and recovery. The optimal benefit to be derived from nutritional therapy may have more to do with the degree to which immune cross-talk signaling can be modified by such innovative strategies. This article is protected by copyright. All rights reserved.

Predictive Biomarkers of Intensive Care Unit and Mechanical Ventilation Duration in Critically-Ill Coronavirus Disease 2019 Patients

Introduction: Detection of early metabolic changes in critically-ill coronavirus disease 2019 (COVID-19) patients under invasive mechanical ventilation (IMV) at the intensive care unit (ICU) could predict recovery patterns and help in disease management. Methods: Targeted metabolomics of serum samples from 39 COVID-19 patients under IMV in ICU was performed within 48 h of intubation and a week later. A generalized linear model (GLM) was used to identify, at both time points, metabolites and clinical traits that predict the length of stay (LOS) at ICU (short ≤ 14 days/long >14 days) as well as the duration under IMV. All models were initially trained on a set of randomly selected individuals and validated on the remaining individuals in the cohort. Further validation in recently published metabolomics data of COVID-19 severity was performed. Results: A model based on hypoxanthine and betaine measured at first time point was best at predicting whether a patient is likely to experience a short or long stay at ICU [area under curve (AUC) = 0.92]. A further model based on kynurenine, 3-methylhistidine, ornithine, p-cresol sulfate, and C24.0 sphingomyelin, measured 1 week later, accurately predicted the duration of IMV (Pearson correlation = 0.94). Both predictive models outperformed Acute Physiology and Chronic Health Evaluation II (APACHE II) scores and differentiated COVID-19 severity in published data. Conclusion: This study has identified specific metabolites that can predict in advance LOS and IMV, which could help in the management of COVID-19 cases at ICU.

Association of metabolomic markers and response to nutritional support: A secondary analysis of the EFFORT trial using an untargeted metabolomics approach

BACKGROUND & AIMS

The EFFORT trial reported a substantial risk reduction for adverse events and mortality in medical in-patients receiving a nutritional support intervention. With the use of an untargeted metabolomics approach, we investigated the prognostic and therapeutic potential of metabolomic markers to understand, whether there are distinct metabolic patterns associated with malnutrition risk as assessed by the Nutritional Risk screening (NRS 2002) score, the risk of 30-day mortality and the response to nutritional support, respectively.

METHODS

Out of the 2088 samples we randomly selected 120 blood samples drawn on day 1 after hospital admission and before treatment initiation. Samples were stratified by NRS 2002, treatment allocation (intervention vs. control), and mortality at 30 days, but not on the type of medical illness. We performed untargeted analysis by liquid chromatography mass spectrometry (LC-MS/MS).

RESULTS

We measured 1389 metabolites in 120 patients of which 81 (67.5%) survived until day 30. After filtering, 371 metabolites remained, and 200 were matched to one or more Human Metabolome Data Base (HMDB) entries. Between group analysis showed a slight distinction between the treatment groups for patients with a NRS 3, but not for those with NRS 4 and ≥ 5. C-statistic between those who died and survived at day 30 ranged from 0.49 (95% confidence interval 0.35-0.68) for a combination of 5 metabolites/predictors to 0.66 (95% confidence interval 0.53-0.79) for a combination of 100 metabolites. Pathway analysis found significant enrichment in the pathways for nitrogen, vitamin B3 (nicotinate and nicotinamide), leukotriene, and arachidonic acid metabolisms in nutritional support responders compared to non-responders.

CONCLUSION

In our heterogenous population of medical inpatients with different illnesses and comorbidities, metabolomic markers showed little prognostic and therapeutic potential for better phenotyping malnutrition and response to nutritional therapy. Future studies should focus on more selected patient populations to understand whether a metabolomic approach can advance the nutritional care of patients.

Plasma high-resolution metabolomic phenotyping of lean mass in a United States adult cohort

BACKGROUND

Rapid loss of lean mass during catabolic states is associated with impaired convalescence and increased mortality rates. An understanding of metabolic pathways related to lean mass is needed to enable future interventions designed to combat malnutrition. This study assessed the plasma metabolome in relation to lean mass in clinically stable working adults in a US cohort.

METHODS

This cross-sectional study included 180 adults (mean ± SD, aged 49.7 ± 10.0 years; body mass index, 27.3 ± 5.5 kg/m² ; 64% female [n=116]). Fasting plasma was analyzed using high-resolution metabolomics (HRM) via liquid chromatography/mass spectrometry. Lean mass was assessed by dual-energy x-ray absorptiometry and expressed as lean mass index (LMI, lean mass kg/height m² ). Multiple linear regression, metabolic pathway enrichment, and module analyses were used to characterize systemic metabolism associated with LMI.

RESULTS

Of 5360 metabolites used in analyses, 593 were related to LMI, either upregulated or downregulated (P < .05). These were enriched within 11 metabolic pathways, including branched-chain amino acid degradation, metabolism of alanine and aspartate and other amino acids, butyrate, purines, and niacin metabolism. Module analysis revealed central associations between LMI and L-glutamate, L-leucine/L-isoleucine, L-valine, L-phenylalanine, L-methionine, and L-aspartate, among other validated metabolites.

CONCLUSION

These novel plasma HRM data demonstrate the wide-reaching associations of lean mass with systemic metabolism in a single snapshot. Such data may inform targeted nutrition support interventions designed to mitigate loss of lean mass and promote regaining skeletal muscle mass and function after illness or injury.

Effect of an intensified individual nutrition therapy on serum metabolites in critically ill patients - A targeted metabolomics analysis of the ONCA study

PURPOSE

The effect of medical nutrition on serum metabolomics has been poorly explored. The aim of the study was to investigate the relation between energy supply and metabolic profiles in critically ill patients.

MATERIALS AND METHODS

Twenty mechanically ventilated patients on enteral nutrition (EN) or enteral/parenteral nutrition (EN/PN) were randomized into two groups. One group received an individual energy supply based on indirect calorimetry (IC group, n = 9), the other group received a standard energy supply based on a formula, the standard care group (SC group, n = 11). Targeted metabolomics was performed in early-, late- and post-acute metabolic phase.

RESULTS

Individual versus standard care energy supply resulted in a metabolite class separation between the IC and the SC group (P < 0.001). In the SC group concentrations of four glucogenic amino acids and three biogenic amines increased between the early- and late-acute metabolic phase (P < 0.05). The metabolomics pattern differed between the routes of nutrition administration (P < 0.01).

CONCLUSIONS

The amount of energy supply by EN or PN, besides other factors, seems to modulate serum metabolites. Nutrition therapy based on individualized energy supply is associated with a reduction of metabolites reflecting catabolism. Therefore, metabolomics could be a new tool to determine metabolic phases in critically ill patients.

Pediatric Multi-Organ Dysfunction Syndrome: Analysis by an Untargeted "Shotgun" Lipidomic Approach Reveals Low-Abundance Plasma Phospholipids and Dynamic Recovery over 8-Day Period, a Single-Center Observational Study

Lipids are molecules involved in metabolism and inflammation. This study investigates the plasma lipidome for markers of severity and nutritional status in critically ill children. Children with multi-organ dysfunction syndrome (MODS) (n = 24) are analyzed at three time-points and cross-referenced to sedation controls (n = 4) for a total of N = 28. Eight of the patients with MODS, needed veno-arterial extracorporeal membrane oxygenation (VA ECMO) support to survive. Blood plasma lipid profiles are quantified by nano-electrospray (nESI), direct infusion high resolution/accurate mass spectrometry (MS), and tandem mass spectrometry (MS/MS), and compared to nutritional profiles and pediatric logistic organ dysfunction (PELOD) scores. Our results show that PELOD scores were not significantly different between MODS and ECMO cases across time-points (p = 0.66). Lipid profiling provides stratification between sedation controls and all MODS patients for total lysophosphatidylserine (lysoPS) (p-value = 0.004), total phosphatidylserine (PS) (p-value = 0.015), and total ether-linked phosphatidylethanolamine (ether-PE) (p-value = 0.03) after adjusting for sex and age. Nutrition intake over time did not correlate with changes in lipid profiles, as measured by caloric and protein intake. Lipid measurement in the intensive care environment shows dynamic changes over an 8-day pediatric intensive care unit (PICU) course, suggesting novel metabolic indicators for defining critically ill children.

Mitochondrial Dysfunction in Critical Illness: Implications for Nutritional Therapy

PURPOSE OF THE REVIEW

This paper will review the evidence for mitochondrial dysfunction in critical illness, describe the mechanisms which lead to multiple organ failure, and detail the implications of this pathophysiologic process on nutritional therapy.

RECENT FINDINGS

Mitochondria are particularly sensitive to increased oxidative stress in critical illness. The functional and structural abnormalities which occur in this organelle contribute further to the excessive production of reactive oxygen species and the reduction in generation of adenosine triphosphate (ATP). To reduce metabolic demand, mitochondrial dysfunction develops (a process likened to hibernation), which helps sustain the life of the cell at a cost of organ system failure. Aggressive feeding in the early phases of critical illness might inappropriately increase demand at a time when ATP production is limited, further jeopardizing cell survival and potentiating the processes leading to multiple organ failure. Several potential therapies exist which would promote mitochondrial function in the intensive care setting through support of autophagy, antioxidant defense systems, and the biogenesis and recovery of the organelle itself. Nutritional therapy should supplement micronutrients required in the mitochondrial metabolic pathways and provide reduced delivery of macronutrients through slower advancement of feeding in the early phases of critical illness. A better understanding of mitochondrial dysfunction in the critically ill patient should lead to more innovative therapies in the future.

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).

Clinical nutrition for the gastroenterologist: the physiologic rationale for providing early nutritional therapy to the hospitalized patient

PURPOSE OF REVIEW

Conflicting reports in the literature have been misinterpreted by clinicians, who conclude that nutritional therapy for the hospitalized patient is of marginal value. The true benefit of such therapy is derived from the provision of early enteral nutrition. This article describes the physiologic response to enteral feeding, which accounts for the outcome benefits, and illustrates how use of the gut alters immune responses and the intestinal microbiota.

RECENT FINDINGS

The provision of early enteral nutrition has been shown to reduce infection and mortality in high-risk hospitalized patients (compared with not providing such therapy). Early feeding maintains gut integrity, reduces permeability, promotes tolerance and appropriate immune responses, and supports commensalism of the intestinal microbiota. Early enteral nutrition influences cross-talk signaling between luminal bacteria and the intestinal epithelium. Failure to utilize the gut in acute illness can amplify the systemic inflammatory response syndrome and worsen disease severity, while at the same time promoting antibiotic resistance and increased septic morbidity.

SUMMARY

Appropriate nutritional therapy does change outcomes in the hospitalized patient, especially for those who are at risk on the basis of disease severity and/or poor nutritional status. Greatest benefit is seen from those therapeutic regimens that specifically target gut defenses and the intestinal microbiome.

Pyroglutamic acidosis by glutathione regeneration blockage in critical patients with septic shock

AIM

The aim of this study was to evaluate oxidative stress from glutathione depletion in critically ill patients with a septic shock through the abnormal presence of pyroglutamic acid (PyroGlu) in the urine (indirectly) and through its serum level (directly).

METHODS

This was a prospective analytical study of 28 critically ill patients with a septic shock who were monitored from admission (initial) to 3 days of stay (final) in the intensive care unit (ICU). Data collected included PyroGlu and glutamic acid (Glu) using liquid chromatography/mass spectrometry, and glutathione peroxidase (GPX) activity with a colorimetric assay. The differences in Glu, PyroGlu, and GPX activity between the septic shock group and healthy control group serving as reference values were evaluated using the Mann-Whitney test. The correlations between Glu, PyroGlu, and GPX activity and clinical outcomes were determined using Spearman's correlation coefficient.

RESULTS

In patients with septic shock, serum and urine PyroGlu levels were higher, erythrocyte GPX activity/gr Hb was lower, and urine Glu levels were lower compared to healthy control reference values, for both initial and final values. Initial serum Glu levels were also lower. Serum PyroGlu levels had a correlation with both initial and final serum Glu levels; levels also correlated in the urine. Initial serum Glu correlated with the days of mechanical ventilation (P = 0.016) and the days of ICU stay (P = 0.05). Urine Glu/mg creatinine correlated with APACHE II (P = 0.030). This positive correlation observed for serum Glu was not observed for PyroGlu.

CONCLUSIONS

The current study found that septic patients have higher levels of PyroGlu, lower levels of Glu, and lower erythrocyte GPX activity, suggesting that these biomarkers could be used as an indicator of glutathione depletion. In addition, Glu is related to severity parameters. This study can guide future studies on the importance of monitoring the levels of pyroglutamic acidosis in critical patients with septic shock in order to preserve the oxidative status and its evolution during the stay in the ICU.

Untargeted Metabolomics Differentiates l-Carnitine Treated Septic Shock 1-Year Survivors and Nonsurvivors

l-Carnitine is a candidate therapeutic for the treatment of septic shock, a condition that carries a ≥40% mortality. Responsiveness to l-carnitine may hinge on unique metabolic profiles that are not evident from the clinical phenotype. To define these profiles, we performed an untargeted metabolomic analysis of serum from 21 male sepsis patients enrolled in a placebo-controlled l-carnitine clinical trial. Although treatment with l-carnitine is known to induce changes in the sepsis metabolome, we found a distinct set of metabolites that differentiated 1-year survivors from nonsurvivors. Following feature alignment, we employed a new and innovative data reduction strategy followed by false discovery correction, and identified 63 metabolites that differentiated carnitine-treated 1-year survivors versus nonsurvivors. Following identification by MS/MS and database search, several metabolite markers of vascular inflammation were determined to be prominently elevated in the carnitine-treated nonsurvivor cohort, including fibrinopeptide A, allysine, and histamine. While preliminary, these results corroborate that metabolic profiles may be useful to differentiate l-carnitine treatment responsiveness. Furthermore, these data show that the metabolic signature of l-carnitine-treated nonsurvivors is associated with a severity of illness (e.g., vascular inflammation) that is not routinely clinically detected.

Association between Modified Body Mass Index and 30-Day and 1-Year Mortality after Intensive Care Unit Admission: A Retrospective Cohort Study

Because conventional body mass index (cBMI) does not reflect fluid accumulation, modified BMI (mBMI, serum albumin multiplied by cBMI) is a more accurate measure of malnutrition status. This study aimed to determine whether mortality after intensive care unit (ICU) admission was associated with cBMI, mBMI, and/or serum albumin levels. The medical records of patients who were admitted to a tertiary hospital ICU between 1 January 2012 and 31 July 2016 were retrospectively reviewed. In total, 6169 ICU-admitted patients were included in the analyses. Multivariate Cox regression analyses revealed that low cBMI, mBMI and albumin level were significantly associated with 30-day and 1-year mortality after ICU admission (hazard ratio < 1.0, p < 0.05). The adjusted area under the curve (AUC) of mBMI for 1-year mortality was significantly higher than that of cBMI (p < 0.001), but not significantly different from that of albumin level (p = 0.098). Low values of mBMI, cBMI and albumin were independently associated with 30-day and 1-year mortality after ICU admission. Combining cBMI and albumin (mBMI) did not increase the validity of the AUC of albumin for 1-year mortality after ICU admission. Our study showed that serum albumin alone, rather than mBMI (combining cBMI), is recommended in predicting mortality among ICU patients.

Nutritional metabolomics in critical illness

PURPOSE OF REVIEW

Disruption of metabolic homeostasis is universal in the critically ill. Macronutrients and micronutrients are major environmental regulators of metabolite production through their gene regulation effects. The study of large numbers of circulating metabolites is beginning to emerge through the comprehensive profiling of the critically ill. In the critically ill, metabolomic studies consistently show that changes in fatty acids, lipids and tryptophan metabolite pathways are common and are associated with disease state and outcomes.

RECENT FINDINGS

Metabolomics is now being applied in research studies to determine the critical illness response to nutrient deficiency and delivery. Nutritional metabolomics approaches in nutrient deficiency, malnutrition and nutrient delivery have included single time point studies and dynamic studies of critically ill patients over time. Integration of metabolomics and clinical outcome data may create a more complete understanding of the control of metabolism in critical illness.

SUMMARY

The integration of metabolomic profiling with transcription and genomic data may allow for a unique window into the mechanism of how nutrient deficiency and delivery alters cellular homeostasis during critical illness and modulates the regain of cellular homeostasis during recovery. The progress and the challenges of the study of nutritional metabolomics are reviewed here.