The Glyoxalase System and Methylglyoxal-Derived Carbonyl Stress in Sepsis: Glycotoxic Aspects of Sepsis Pathophysiology

Admission Blood Glucose Associated with In-Hospital Mortality in Critically III Non-Diabetic Patients with Heart Failure: A Retrospective Study

Background

Heart failure (HF) is a primary public health issue associated with a high mortality rate. However, effective treatments still need to be developed. The optimal level of glycemic control in non-diabetic critically ill patients suffering from HF is uncertain. Therefore, this study examined the relationship between initial glucose levels and in-hospital mortality in critically ill non-diabetic patients with HF.

Methods

A total of 1159 critically ill patients with HF were selected from the Medical Information Mart for Intensive Care-III (MIMIC-III) data resource and included in this study. The association between initial glucose levels and hospital mortality in seriously ill non-diabetic patients with HF was analyzed using smooth curve fittings and multivariable Cox regression. Stratified analyses were performed for age, gender, hypertension, atrial fibrillation, CHD with no MI (coronary heart disease with no myocardial infarction), renal failure, chronic obstructive pulmonary disease (COPD), estimated glomerular filtration rate (eGFR), and blood glucose concentrations.

Results

The hospital mortality was identified as 14.9%. A multivariate Cox regression model, along with smooth curve fitting data, showed that the initial blood glucose demonstrated a U-shape relationship with hospitalized deaths in non-diabetic critically ill patients with HF. The turning point on the left side of the inflection point was HR 0.69, 95% CI 0.47-1.02, p = 0.068, and on the right side, HR 1.24, 95% CI 1.07-1.43, p = 0.003. Significant interactions existed for blood glucose concentrations (7-11 mmol/L) (p-value for interaction: 0.009). No other significant interactions were detected.

Conclusions

This study demonstrated a U-shape correlation between initial blood glucose and hospital mortality in critically ill non-diabetic patients with HF. The optimal level of initial blood glucose for non-diabetic critically ill patients with HF was around 7 mmol/L.

Is Methylglyoxal a Potential Biomarker for the Warburg Effect Induced by the Lipopolysaccharide Neuroinflammation Model?

Methylglyoxal (MG) is considered a classical biomarker of diabetes mellitus and its comorbidities. However, a role for this compound in exacerbated immune responses, such as septicemia, is being increasingly observed and requires clarification, particularly in the context of neuroinflammatory responses. Herein, we used two different approaches (in vivo and acute hippocampal slice models) to investigate MG as a biomarker of neuroinflammation and the neuroimmunometabolic shift to glycolysis in lipopolysaccharide (LPS) inflammation models. Our data reinforce the hypothesis that LPS-induced neuroinflammation stimulates the cerebral innate immune response by increasing IL-1β, a classical pro-inflammatory cytokine, and the astrocyte reactive response, via elevating S100B secretion and GFAP levels. Acute neuroinflammation promotes an early neuroimmunometabolic shift to glycolysis by elevating glucose uptake, lactate release, PFK1, and PK activities. We observed high serum and cerebral MG levels, in association with a reduction in glyoxalase 1 detoxification activity, and a close correlation between serum and hippocampus MG levels with the systemic and neuroinflammatory responses to LPS. Findings strongly suggest a role for MG in immune responses.

Molecular Assessment of Methylglyoxal-Induced Toxicity and Therapeutic Approaches in Various Diseases: Exploring the Interplay with the Glyoxalase System

This comprehensive exploration delves into the intricate interplay of methylglyoxal (MG) and glyoxalase 1 (GLO I) in various physiological and pathological contexts. The linchpin of the narrative revolves around the role of these small molecules in age-related issues, diabetes, obesity, cardiovascular diseases, and neurodegenerative disorders. Methylglyoxal, a reactive dicarbonyl metabolite, takes center stage, becoming a principal player in the development of AGEs and contributing to cell and tissue dysfunction. The dual facets of GLO I-activation and inhibition-unfold as potential therapeutic avenues. Activators, spanning synthetic drugs like candesartan to natural compounds like polyphenols and isothiocyanates, aim to restore GLO I function. These molecular enhancers showcase promising outcomes in conditions such as diabetic retinopathy, kidney disease, and beyond. On the contrary, GLO I inhibitors emerge as crucial players in cancer treatment, offering new possibilities in diseases associated with inflammation and multidrug resistance. The symphony of small molecules, from GLO I activators to inhibitors, presents a nuanced understanding of MG regulation. From natural compounds to synthetic drugs, each element contributes to a molecular orchestra, promising novel interventions and personalized approaches in the pursuit of health and wellbeing. The abstract concludes with an emphasis on the necessity of rigorous clinical trials to validate these findings and acknowledges the importance of individual variability in the complex landscape of health.

Pronounced cortisol response to acute psychosocial stress in type 2 diabetes patients with and without complications

It is increasingly recognized that psychological stress is linked with type 2 diabetes mellitus and its late complications. Thus, the aim of the current study was to investigate the psychophysiological response to acute psychosocial stress in patients with type 2 diabetes. In total, 53 type 2 diabetes patients with complications, 16 type 2 diabetes patients without complications, and 47 age and gender matched non-diabetic participants underwent the Trier Social Stress Test. Subjective as well as biological parameters (i.e., blood levels of cortisol, adrenocorticotropic hormone (ACTH), norepinephrine, methylglyoxal) were assessed repeatedly before and after stress induction. Data were analyzed by means of multilevel regression. Patients with type 2 diabetes showed an exaggerated cortisol response to acute stress as compared to age matched control participants (diabetes*T2 est. = 1.23, p < .001), while stress-induced alterations of ACTH and subjective parameters did not differ. Norepinephrine levels were lower among patients (diabetes est. = -4.36, p = .044) and tended to decrease earlier than in controls. The subjective reaction of type 2 diabetes patients with complications was stronger than that of patients without complications (complication*T2 est. = -1.83, p = .032), while their endocrine response to stress was similar. Stress had no effect on methylglyoxal level, and there were no group differences regarding methylglyoxal response. These results show that the cortisol reactivity of patients with type 2 diabetes to acute psychosocial stress is increased compared to a control group. Thus, alterations of the hypothalamus-pituitary-adrenal axis - especially regarding its dynamic regulation - are a plausible link between psychological stress and type 2 diabetes and its complications.

The aldehyde hypothesis: metabolic intermediates as antimicrobial effectors

There are many reactive intermediates found in metabolic pathways. Could these potentially toxic molecules be exploited for an organism's benefit? We propose that during certain microbial infections, the production of inherently reactive aldehydes by an infected host is a previously unappreciated innate immune defence mechanism. While there has been a significant focus on the effects of aldehydes on mammalian physiology, the idea that they might be exploited or purposefully induced to kill pathogens is new. Given that aldehydes are made as parts of metabolic programmes that accompany immune cell activation by the cytokine interferon-gamma (IFN-γ) during infections, we hypothesize that aldehydes are among the arsenal of IFN-γ-inducible effectors needed for pathogen control.

Melatonin: highlighting its use as a potential treatment for SARS-CoV-2 infection

Numerous pharmaceutical drugs have been repurposed for use as treatments for COVID-19 disease. These drugs have not consistently demonstrated high efficacy in preventing or treating this serious condition and all have side effects to differing degrees. We encourage the continued consideration of the use of the antioxidant and anti-inflammatory agent, melatonin, as a countermeasure to a SARS-CoV-2 infection. More than 140 scientific publications have identified melatonin as a likely useful agent to treat this disease. Moreover, the publications cited provide the rationale for the use of melatonin as a prophylactic agent against this condition. Melatonin has pan-antiviral effects and it diminishes the severity of viral infections and reduces the death of animals infected with numerous different viruses, including three different coronaviruses. Network analyses, which compared drugs used to treat SARS-CoV-2 in humans, also predicted that melatonin would be the most effective agent for preventing/treating COVID-19. Finally, when seriously infected COVID-19 patients were treated with melatonin, either alone or in combination with other medications, these treatments reduced the severity of infection, lowered the death rate, and shortened the duration of hospitalization. Melatonin’s ability to arrest SARS-CoV-2 infections may reduce health care exhaustion by limiting the need for hospitalization. Importantly, melatonin has a high safety profile over a wide range of doses and lacks significant toxicity. Some molecular processes by which melatonin resists a SARS-CoV-2 infection are summarized. The authors believe that all available, potentially beneficial drugs, including melatonin, that lack toxicity should be used in pandemics such as that caused by SARS-CoV-2.

The Surviving Sepsis Campaign: Basic/Translational Science Research Priorities

Objectives:

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data Sources:

Original paper, search of the literature.

Study Selection:

By several members of the original task force with specific expertise in basic/translational science.

Data Extraction:

None.

Data Synthesis:

None.

Conclusions:

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

Loganic Acid, an Iridoid Glycoside Extracted from Cornus mas L. Fruits, Reduces of Carbonyl/Oxidative Stress Biomarkers in Plasma and Restores Antioxidant Balance in Leukocytes of Rats with Streptozotocin-Induced Diabetes Mellitus

The various complications related to diabetes are due to the alteration in plasma components and functional activity of blood cells, hence the search for preventive remedies that would ameliorate the clinical condition of patients is a relevant problem today. The main aim of the present study was to examine the antidiabetic potency and antioxidant effects of loganic acid (LA) in blood of diabetic rats. LA showed a restoration of balance between functioning of antioxidant defense system and oxidative stress in leukocytes without notable effects on blood glucose levels when administered orally to rats (20 mg/kg b.w./day) for 14 days. LA ameliorated antioxidant status in leukocytes, as indicated by increasing the content of reduced glutathione and activities of catalase, glutathione peroxidase and glutathione reductase along with decreasing levels of intracellular reactive oxygen species. In addition, we observed the ability of LA to protect against formation and accumulation of glycation and oxidation protein products and malondialdehyde derivates in plasma. Therefore, LA showed antioxidant properties that may have beneficial effects under diabetes. Such results may represent LA as one of the plant components in the development of new drugs that will correct metabolic and functional disorders in leukocytes under diabetes.

Exploring plasma metabolomic changes in sepsis: a clinical matching study based on gas chromatography-mass spectrometry

Background

Sepsis is a deleterious systemic inflammatory response to infection, and despite advances in treatment, the mortality rate remains high. We hypothesized that plasma metabolism could clarify sepsis in patients complicated by organ dysfunction.

Methods

Plasma samples from 31 patients with sepsis and 23 healthy individuals of comparable age, gender, and body mass index (BMI) were collected. Plasma metabolites were detected through gas chromatography–mass spectrometry (GC–MS), and relevant metabolic pathways were predicted using the Kyoto Encyclopedia of Genes and Genomics (KEGG) pathway database. Student’s t-test was employed for statistical analysis. In addition, to explore sepsis organ dysfunction, plasma samples of sepsis patients were further analyzed by metabolomics subgroup analysis according to organ dysfunction.

Results

A total of 222 metabolites were detected, which included 124 metabolites with statistical significance between the sepsis and control groups. Among these, we found 26 were fatty acids, including 3 branched fatty acids, 10 were saturated fatty acids, and 13 were unsaturated fatty acids that were found in sepsis plasma samples but not in the controls. In addition, 158 metabolic pathways were predicted, 74 of which were significant. Further subgroup analysis identified seven metabolites in acute kidney injury (AKI), three metabolites in acute respiratory distress syndrome (ARDS), seven metabolites in sepsis-induced myocardial dysfunction (SIMD), and four metabolites in acute hepatic ischemia (AHI) that were significantly different. The results showed that the sepsis samples exhibited extensive changes in amino acids, fatty acids, and tricarboxylic acid (TCA)–cycle products. In addition, three metabolic pathways—namely, energy metabolism, amino acid metabolism, and lipid metabolism—were downregulated in sepsis patients.

Conclusions

The downregulated energy, amino acid, and lipid metabolism found in our study may serve as a novel clinical marker for the dysregulated internal environment, particularly involving energy metabolism, which results in sepsis.

The surviving sepsis campaign: basic/translational science research priorities

Objectives

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data sources

Original paper, search of the literature.

Study selection

This study is selected by several members of the original task force with specific expertise in basic/translational science. Data extraction and data synthesis are not available.

Conclusions

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

Extracellular glucose is crucially involved in the fate decision of LPS-stimulated RAW264.7 murine macrophage cells

Pyroptosis, a type of inflammatory cell death, is dependent on the inflammatory caspase-mediated cleavage of gasdermin D (GSDMD), and the subsequent pore formation on plasma membranes through which interleukin (IL)-1β and IL-18 are released from cells. During proinflammatory activation, macrophages shift their metabolism from aerobic oxidative phosphorylation to anaerobic glycolysis. Hypoxia-inducible factor (HIF)1α is involved in the induction of IL-1β gene expression as well as the metabolic shift towards glycolysis. However, the relationships between pyroptosis and glycolysis, as well as between pyroptosis and HIF1α are poorly investigated. Here we show that lipopolysaccharide (LPS) stimulation of RAW264.7 murine macrophage cells results in pyroptosis when cells are cultured in high glucose medium. During pyroptosis, HIF1α activation occurs transiently followed by downregulation to sub-basal levels. HIF1α downregulation and pyroptosis are observed when cells are stimulated with LPS under high glucose conditions. We also found that intracellular levels of methylglyoxal (MGO), a side product of glycolysis, increase when cells are stimulated with LPS under high glucose conditions. The addition of glycolysis inhibitor and rapamycin suppresses HIF1α downregulation and pyroptosis. These results show that glycolysis plays a crucial role not only in pro-inflammatory activation, but also in pyroptosis in LPS-stimulated RAW264.7 macrophages.

Blood Glucose Levels and Mortality in Patients With Sepsis: Dose-Response Analysis of Observational Studies

BACKGROUND

We undertook a systematic review and meta-analysis to investigate the relationship between blood glucose levels and mortality in patients with sepsis.

METHODS

Medline and EMBASE were searched from inception to April 8, 2018. Cohort studies or case-control studies reported the association between blood glucose and mortality in patients with sepsis were selected. Study characteristics, baseline characteristics, definition of hyperglycemia, and outcomes of interest were extracted. We performed a dose-response meta-analysis to assess the effect of blood glucose level on mortality. We also conducted meta-analysis for patients with or without diabetes separately.

RESULTS

Ten cohort studies involving 26 429 patients were included, of which 5 were prospective studies and 5 retrospective studies. Dose-response analysis showed that the effect of blood glucose on mortality may differ in patients with versus without diabetes. There was a U-shaped relationship for patients with diabetes and a J-shaped relationship for patients without diabetes, with blood glucose at 145 to 155 mg/dL corresponding to lowest mortality both in patients with and without diabetes.

CONCLUSIONS

Current evidence suggested U-shaped relationship between blood glucose and mortality in all patients irrespective of their diabetes status. Diabetic patients with blood glucose below 145 mg/dL may have poorer prognosis compared to patients without established diabetes.

Surviving Sepsis Campaign: Research Priorities for Sepsis and Septic Shock

OBJECTIVE

To identify research priorities in the management, epidemiology, outcome and underlying causes of sepsis and septic shock.

DESIGN

A consensus committee of 16 international experts representing the European Society of Intensive Care Medicine and Society of Critical Care Medicine was convened at the annual meetings of both societies. Subgroups had teleconference and electronic-based discussion. The entire committee iteratively developed the entire document and recommendations.

METHODS

Each committee member independently gave their top five priorities for sepsis research. A total of 88 suggestions (Supplemental Table 1, Supplemental Digital Content 2, http://links.lww.com/CCM/D636) were grouped into categories by the committee co-chairs, leading to the formation of seven subgroups: infection, fluids and vasoactive agents, adjunctive therapy, administration/epidemiology, scoring/identification, post-intensive care unit, and basic/translational science. Each subgroup had teleconferences to go over each priority followed by formal voting within each subgroup. The entire committee also voted on top priorities across all subgroups except for basic/translational science.

RESULTS

The Surviving Sepsis Research Committee provides 26 priorities for sepsis and septic shock. Of these, the top six clinical priorities were identified and include the following questions: 1) can targeted/personalized/precision medicine approaches determine which therapies will work for which patients at which times?; 2) what are ideal endpoints for volume resuscitation and how should volume resuscitation be titrated?; 3) should rapid diagnostic tests be implemented in clinical practice?; 4) should empiric antibiotic combination therapy be used in sepsis or septic shock?; 5) what are the predictors of sepsis long-term morbidity and mortality?; and 6) what information identifies organ dysfunction?

CONCLUSIONS

While the Surviving Sepsis Campaign guidelines give multiple recommendations on the treatment of sepsis, significant knowledge gaps remain, both in bedside issues directly applicable to clinicians, as well as understanding the fundamental mechanisms underlying the development and progression of sepsis. The priorities identified represent a roadmap for research in sepsis and septic shock.

Methylglyoxal Disrupts Paranodal Axoglial Junctions via Calpain Activation

Nodes of Ranvier and associated paranodal and juxtaparanodal domains along myelinated axons are essential for normal function of the peripheral and central nervous systems. Disruption of these domains as well as increases in the reactive carbonyl species methylglyoxal are implicated as a pathophysiology common to a wide variety of neurological diseases. Here, using an ex vivo nerve exposure model, we show that increasing methylglyoxal produces paranodal disruption, evidenced by disorganized immunostaining of axoglial cell-adhesion proteins, in both sciatic and optic nerves from wild-type mice. Consistent with previous studies showing that increase of methylglyoxal can alter intracellular calcium homeostasis, we found upregulated activity of the calcium-activated protease calpain in sciatic nerves after methylglyoxal exposure. Methylglyoxal exposure altered clusters of proteins that are known as calpain substrates: ezrin in Schwann cell microvilli at the perinodal area and zonula occludens 1 in Schwann cell autotypic junctions at paranodes. Finally, treatment with the calpain inhibitor calpeptin ameliorated methylglyoxal-evoked ezrin loss and paranodal disruption in both sciatic and optic nerves. Our findings strongly suggest that elevated methylglyoxal levels and subsequent calpain activation contribute to the disruption of specialized axoglial domains along myelinated nerve fibers in neurological diseases.

Increased oxidative stress and coenzyme Q10 deficiency in centenarians

Aging populations are expanding worldwide, and the increasing requirement for nursing care has become a serious problem. Furthermore, successful aging is one of the highest priorities for individuals and societies. Centenarians are an informative cohort to study and inflammation has been found to be a key factor in predicting cognition and physical capabilities. Inflammation scores have been determined based on the levels of cytokines and C-reactive protein, however, serum antioxidants and lipid profiles have not been carefully examined. We found that the redox balance of coenzyme Q10 significantly shifted to the oxidized form and levels of strong antioxidants, such as ascorbic acid and unconjugated bilirubin, decreased significantly compared to 76-year-old controls, indicating an increased oxidative stress in centenarians. Levels of uric acid, an endogenous peroxynitrite scavenger, remained unchanged, suggesting that centenarians were experiencing moderate, chronic inflammatory conditions. Centenarians exhibited a hypocholesterolemic condition, while an increase in the ratio of free cholesterol to cholesterol esters suggests some impairment of liver function. Serum free fatty acids and monoenoic acid composition, markers of tissue oxidative damage, were significantly decreased in centenarians, indicating an impairment in the tissue repair system. Despite an elevation of the coenzyme Q10 binding protein Psap, serum total coenzyme Q10 levels decreased in centenarians. This suggests a serious deficiency of coenzyme Q10 in tissues, since tissue levels of coenzyme Q10 significantly decrease with age. Therefore, coenzyme Q10 supplementation could be beneficial for centenarians.

Increased oxidative stress and renal injury in patients with sepsis

Sepsis remains one of the leading causes of death in intensive care units. The early phase of sepsis is characterized by a massive formation of reactive oxygen and nitrogen species such as superoxide and nitric oxide. However, few comprehensive studies on plasma antioxidants have been reported. Increased oxidative stress was confirmed in sepsis patients (n = 18) at the time of hospitalization by a significant decrease in plasma ascorbic acid and a significant increase in the percentage of oxidized form of coenzyme Q10 in total coenzyme Q10 compared to age-matched healthy controls (n = 62). Tissue oxidative damage in patients was suggested by a significant decrease in polyunsaturated fatty acid contents and a significant increase in oleic acid contents in total free fatty acids. Thus, it is reasonable that plasma uric acid (end product of purines) would be significantly elevated. However, uric acid levels were continuously decreased during hospitalization for 7 days, indicating a continuous formation of peroxynitrite. A greater decrease in free cholesterol (FC) compared to cholesterol esters (CE) was observed. Thus, the FC/CE ratio significantly increased, suggesting deficiency of lecithin-cholesterol acyltransferase secreted from the liver. Plasma levels of prosaposin, a coenzyme Q10 binding protein, significantly decreased as compared to healthy controls. This may be correlated with renal injury in sepsis patients, since the kidney is thought to be a major secretor of prosaposin.

Surviving sepsis campaign: research priorities for sepsis and septic shock

Objective

To identify research priorities in the management, epidemiology, outcome and underlying causes of sepsis and septic shock.

Design

A consensus committee of 16 international experts representing the European Society of Intensive Care Medicine and Society of Critical Care Medicine was convened at the annual meetings of both societies. Subgroups had teleconference and electronic-based discussion. The entire committee iteratively developed the entire document and recommendations.

Methods

Each committee member independently gave their top five priorities for sepsis research. A total of 88 suggestions (ESM 1 - supplemental table 1) were grouped into categories by the committee co-chairs, leading to the formation of seven subgroups: infection, fluids and vasoactive agents, adjunctive therapy, administration/epidemiology, scoring/identification, post-intensive care unit, and basic/translational science. Each subgroup had teleconferences to go over each priority followed by formal voting within each subgroup. The entire committee also voted on top priorities across all subgroups except for basic/translational science.

Results

The Surviving Sepsis Research Committee provides 26 priorities for sepsis and septic shock. Of these, the top six clinical priorities were identified and include the following questions: (1) can targeted/personalized/precision medicine approaches determine which therapies will work for which patients at which times?; (2) what are ideal endpoints for volume resuscitation and how should volume resuscitation be titrated?; (3) should rapid diagnostic tests be implemented in clinical practice?; (4) should empiric antibiotic combination therapy be used in sepsis or septic shock?; (5) what are the predictors of sepsis long-term morbidity and mortality?; and (6) what information identifies organ dysfunction?

Conclusions

While the Surviving Sepsis Campaign guidelines give multiple recommendations on the treatment of sepsis, significant knowledge gaps remain, both in bedside issues directly applicable to clinicians, as well as understanding the fundamental mechanisms underlying the development and progression of sepsis. The priorities identified represent a roadmap for research in sepsis and septic shock.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5175-z) contains supplementary material, which is available to authorized users.

Dietary Advanced Glycosylation End-Products (dAGEs) and Melanoidins Formed through the Maillard Reaction: Physiological Consequences of their Intake

The main purpose of this review is to clarify whether the consumption of food rich in melanoidins and dietary advanced glycosylation end-products (dAGEs) is harmful or beneficial for human health. There are conflicting results on their harmful effects in the literature, partly due to a methodological issue in how dAGEs are determined in food. Melanoidins have positive functions particularly within the gastrointestinal tract, whereas the intake of dAGEs has controversial physiological consequences. Most of the in vivo intervention trials were done comparing boiled versus roasted diet (low and high dAGE, respectively). However, these studies can be biased by different lipid oxidation and by different calorie density of foods in the two conditions. The attraction that humans have to cooked foods is linked to the benefits they have had during mankind's evolution. The goal for food technologists is to design low-energy-dense products that can satisfy humans' attraction to rewarding cooked foods.