Mechanisms of Hemolysis During Sepsis

A practical predictive model to predict 30-day mortality in neonatal sepsis

OBJECTIVE

Neonatal sepsis is a serious disease that needs timely and immediate medical attention. So far, there is no specific prognostic biomarkers or model for dependable predict outcomes in neonatal sepsis. The aim of this study was to establish a predictive model based on readily available laboratory data to assess 30-day mortality in neonatal sepsis.

METHODS

Neonates with sepsis were recruited between January 2019 and December 2022. The admission information was obtained from the medical record retrospectively. Univariate or multivariate analysis was utilized to identify independent risk factors. The receiver operating characteristic curve was drawn to check the performance of the predictive model.

RESULTS

A total of 195 patients were recruited. There was a big difference between the two groups in the levels of hemoglobin and prothrombin time. Multivariate analysis confirmed that hemoglobin>133 g/L (hazard ratio: 0.351, p=0.042) and prothrombin time >16.6 s (hazard ratio: 4.140, p=0.005) were independent risk markers of 30-day mortality. Based on these results, a predictive model with the highest area under the curve (0.756) was built.

CONCLUSION

We established a predictive model that can objectively and accurately predict individualized risk of 30-day mortality. The predictive model should help clinicians to improve individual treatment, make clinical decisions, and guide follow-up management strategies.

Mild Systemic Inflammation Increases Erythrocyte Fragility

There is growing evidence that inflammation impairs erythrocyte structure and function. We assessed the impact of mild systemic inflammation on erythrocyte fragility in three different settings. In order to investigate causation, erythrocyte osmotic fragility was measured in mice challenged with a live attenuated bacterial strain to induce low-grade systemic inflammation; a significant increase in erythrocyte osmotic fragility was observed. To gather evidence that systemic inflammation is associated with erythrocyte fragility in humans, two observational studies were conducted. First, using a retrospective study design, the relationship between reticulocyte-based surrogate markers of haemolysis and high-sensitivity C-reactive protein was investigated in 9292 healthy participants of the UK Biobank project. Secondly, we prospectively assessed the relationship between systemic inflammation (measured by the urinary neopterin/creatinine ratio) and erythrocyte osmotic fragility in a mixed population (n = 54) of healthy volunteers and individuals with long-term medical conditions. Both human studies were in keeping with a relationship between inflammation and erythrocyte fragility. Taken together, we conclude that mild systemic inflammation increases erythrocyte fragility and may contribute to haemolysis. Further research is needed to assess the molecular underpinnings of this pathway and the clinical implications in inflammatory conditions.

Analysis of non-physiological shear stress-induced red blood cell trauma across different clinical support conditions of the blood pump

Systematic research into device-induced red blood cell (RBC) damage beyond hemolysis, including correlations between hemolysis and RBC-derived extracellular vesicles, remains limited. This study investigated non-physiological shear stress-induced RBC damage and changes in related biochemical indicators under two blood pump clinical support conditions. Pressure heads of 100 and 350 mmHg, numerical simulation methods, and two in vitro loops were utilized to analyze the shear stress and changes in RBC morphology, hemolysis, biochemistry, metabolism, and oxidative stress. The blood pump created higher shear stress in the 350-mmHg condition than in the 100-mmHg condition. With prolonged blood pump operation, plasma-free hemoglobin and cholesterol increased, whereas plasma glucose and nitric oxide decreased in both loops. Notably, plasma iron and triglyceride concentrations increased only in the 350-mmHg condition. The RBC count and morphology, plasma lactic dehydrogenase, and oxidative stress across loops did not differ significantly. Plasma extracellular vesicles, including RBC-derived microparticles, increased significantly at 600 min in both loops. Hemolysis correlated with plasma triglyceride, cholesterol, glucose, and nitric oxide levels. Shear stress, but not oxidative stress, was the main cause of RBC damage. Hemolysis alone inadequately reflects overall blood pump-induced RBC damage, suggesting the need for additional biomarkers for comprehensive assessments.

Major endothelial damage markers identified from hemadsorption filters derived from treated patients with septic shock - endoplasmic reticulum stress and bikunin may play a role

Introduction

In septic patients the damage of the endothelial barrier is decisive leading to circulatory septic shock with disseminated vascular coagulation, edema and multiorgan failure. Hemadsorption therapy leads to rapid resolution of clinical symptoms. We propose that the isolation of proteins adsorbed to hemadsorption devices contributes to the identification of mediators responsible for endothelial barrier dysfunction.

Material and methods

Plasma materials enriched to hemadsorption filters (CytoSorb®) after therapy of patients in septic shock were fractionated and functionally characterized for their effect on cell integrity, viability, proliferation and ROS formation by human endothelial cells. Fractions were further studied for their contents of oxidized nucleic acids as well as peptides and proteins by mass spectrometry.

Results

Individual fractions exhibited a strong effect on endothelial cell viability, the endothelial layer morphology, and ROS formation. Fractions with high amounts of DNA and oxidized DNA correlated with ROS formation in the target endothelium. In addition, defined proteins such as defensins (HNP-1), SAA1, CXCL7, and the peptide bikunin were linked to the strongest additive effects in endothelial damage.

Conclusion

Our results indicate that hemadsorption is efficient to transiently remove strong endothelial damage mediators from the blood of patients with septic shock, which explains a rapid clinical improvement of inflammation and endothelial function. The current work indicates that a combination of stressors leads to the most detrimental effects. Oxidized ssDNA, likely derived from mitochondria, SAA1, the chemokine CXCL7 and the human neutrophil peptide alpha-defensin 1 (HNP-1) were unique for their significant negative effect on endothelial cell viability. However, the strongest damage effect occurred, when, bikunin - cleaved off from alpha-1-microglobulin was present in high relative amounts (>65%) of protein contents in the most active fraction. Thus, a relevant combination of stressors appears to be removed by hemadsorption therapy which results in fulminant and rapid, though only transient, clinical restitution.

Trauma diagnostic-related target proteins and their detection techniques

Trauma is a significant health issue that not only leads to immediate death in many cases but also causes severe complications, such as sepsis, thrombosis, haemorrhage, acute respiratory distress syndrome and traumatic brain injury, among trauma patients. Target protein identification technology is a vital technique in the field of biomedical research, enabling the study of biomolecular interactions, drug discovery and disease treatment. It plays a crucial role in identifying key protein targets associated with specific diseases or biological processes, facilitating further research, drug design and the development of treatment strategies. The application of target protein technology in biomarker detection enables the timely identification of newly emerging infections and complications in trauma patients, facilitating expeditious medical interventions and leading to reduced post-trauma mortality rates and improved patient prognoses. This review provides an overview of the current applications of target protein identification technology in trauma-related complications and provides a brief overview of the current target protein identification technology, with the aim of reducing post-trauma mortality, improving diagnostic efficiency and prognostic outcomes for patients.

Genome-based taxonomic identification and safety assessment of an Enterococcus strain isolated from a homemade dairy product

The aim of this study was to explore the taxonomic identification and evaluate the safety of a bacterium, Enterococcus lactis IDCC 2105, isolated from homemade cheese in Korea, using whole genome sequence (WGS) analysis. It sought to identify the species level of this Enterococcus spp., assess its antibiotic resistance, and evaluate its virulence potential. WGS analysis confirmed the bacterial strain IDCC 2105 as E. lactis and identified genes responsible for resistance to erythromycin and clindamycin, specifically msrC, and eatAv, which are chromosomally located, indicating a minimal risk for horizontal gene transfer. The absence of plasmids in E. lactis IDCC 2105 further diminishes the likelihood of resistance gene dissemination. Additionally, our investigation into seven virulence factors, including hemolysis, platelet aggregation, biofilm formation, hyaluronidase, gelatinase, ammonia production, and β-glucuronidase activity, revealed no detectable virulence traits. Although bioinformatic analysis suggested the presence of collagen adhesion genes acm and scm, these were not corroborated by phenotypic virulence assays. Based on these findings, E. lactis IDCC 2105 presents as a safe strain for potential applications, contributing valuable information on its taxonomy, antibiotic resistance profile, and lack of virulence factors, supporting its use in food products.

Optimized protocol for quantification of extracellular nicotinamide adenine dinucleotide: evaluating clinical parameters and pre-analytical factors for translational research

Nicotinamide adenine dinucleotide (NAD+), a coenzyme for more than 500 enzymes, plays a central role in energy production, metabolism, cellular signaling, and DNA repair. Until recently, NAD+ was primarily considered to be an intracellular molecule (iNAD+), however, its extracellular species (eNAD+) has recently been discovered and has since been associated with a multitude of pathological conditions. Therefore, accurate quantification of eNAD+ in bodily fluids such as plasma is paramount to answer important research questions. In order to create a clinically meaningful and reliable quantitation method, we analyzed the relationship of cell lysis, routine clinical laboratory parameters, blood collection techniques, and pre-analytical processing steps with measured plasma eNAD+ concentrations. Initially, NAD+ levels were assessed both intracellularly and extracellularly. Intriguingly, the concentration of eNAD+ in plasma was found to be approximately 500 times lower than iNAD+ in peripheral blood mononuclear cells (0.253 ± 0.02 μM vs. 131.8 ± 27.4 μM, p = 0.007, respectively). This stark contrast suggests that cellular damage or cell lysis could potentially affect the levels of eNAD+ in plasma. However, systemic lactate dehydrogenase in patient plasma, a marker of cell damage, did not significantly correlate with eNAD+ (n = 33; r = -0.397; p = 0.102). Furthermore, eNAD+ was negatively correlated with increasing c-reactive protein (CRP, n = 33; r = -0.451; p = 0.020), while eNAD+ was positively correlated with increasing hemoglobin (n = 33; r = 0.482; p = 0.005). Next, variations in blood drawing, sample handling and pre-analytical processes were examined. Sample storage durations at 4°C (0-120 min), temperature (0° to 25°C), cannula sizes for blood collection and tourniquet times (0 - 120 s) had no statistically significant effect on eNAD+ (p > 0.05). On the other hand, prolonged centrifugation (> 5 min) and a faster braking mode of the centrifuge rotor (< 4 min) resulted in a significant decrease in eNAD+ levels (p < 0.05). Taken together, CRP and hemoglobin appeared to be mildly correlated with eNAD+ levels whereas cell damage was not correlated significantly to eNAD+ levels. The blood drawing trial did not show any influence on eNAD+, in contrast, the preanalytical steps need to be standardized for accurate eNAD+ measurement. This work paves the way towards robust eNAD+ measurements, for use in future clinical and translational research, and provides an optimized hands-on protocol for reliable eNAD+ quantification in plasma.

Iron as an emerging therapeutic target in critically ill patients

The multiple roles of iron in the body have been known for decades, particularly its involvement in iron overload diseases such as hemochromatosis. More recently, compelling evidence has emerged regarding the critical role of non-transferrin bound iron (NTBI), also known as catalytic iron, in the care of critically ill patients in intensive care units (ICUs). These trace amounts of iron constitute a small percentage of the serum iron, yet they are heavily implicated in the exacerbation of diseases, primarily by catalyzing the formation of reactive oxygen species, which promote oxidative stress. Additionally, catalytic iron activates macrophages and facilitates the growth of pathogens. This review aims to shed light on this underappreciated phenomenon and explore the various common sources of NTBI in ICU patients, which lead to transient iron dysregulation during acute phases of disease. Iron serves as the linchpin of a vicious cycle in many ICU pathologies that are often multifactorial. The clinical evidence showing its detrimental impact on patient outcomes will be outlined in the major ICU pathologies. Finally, different therapeutic strategies will be reviewed, including the targeting of proteins involved in iron metabolism, conventional chelation therapy, and the combination of renal replacement therapy with chelation therapy.

Double-edged functions of hemopexin in hematological related diseases: from basic mechanisms to clinical application

It is now understood that hemolysis and the subsequent release of heme into circulation play a critical role in driving the progression of various diseases. Hemopexin (HPX), a heme-binding protein with the highest affinity for heme in plasma, serves as an effective antagonist against heme toxicity resulting from severe acute or chronic hemolysis. In the present study, changes in HPX concentration were characterized at different stages of hemolytic diseases, underscoring its potential as a biomarker for assessing disease progression and prognosis. In many heme overload-driven conditions, such as sickle cell disease, transfusion-induced hemolysis, and sepsis, endogenous HPX levels are often insufficient to provide protection. Consequently, there is growing interest in developing HPX therapeutics to mitigate toxic heme exposure. Strategies include HPX supplementation when endogenous levels are depleted and enhancing HPX's functionality through modifications, offering a potent defense against heme toxicity. It is worth noting that HPX may also exert deleterious effects under certain circumstances. This review aims to provide a comprehensive overview of HPX's roles in the progression and prognosis of hematological diseases. It highlights HPX-based clinical therapies for different hematological disorders, discusses advancements in HPX production and modification technologies, and offers a theoretical basis for the clinical application of HPX.

Bacteria and Bacterial Components as Natural Bio-Nanocarriers for Drug and Gene Delivery Systems in Cancer Therapy

Bacteria and bacterial components possess multifunctional properties, making them attractive natural bio-nanocarriers for cancer diagnosis and targeted treatment. The inherent tropic and motile nature of bacteria allows them to grow and colonize in hypoxic tumor microenvironments more readily than conventional therapeutic agents and other nanomedicines. However, concerns over biosafety, limited antitumor efficiency, and unclear tumor-targeting mechanisms have restricted the clinical translation and application of natural bio-nanocarriers based on bacteria and bacterial components. Fortunately, bacterial therapies combined with engineering strategies and nanotechnology may be able to reverse a number of challenges for bacterial/bacterial component-based cancer biotherapies. Meanwhile, the combined strategies tend to enhance the versatility of bionanoplasmic nanoplatforms to improve biosafety and inhibit tumorigenesis and metastasis. This review summarizes the advantages and challenges of bacteria and bacterial components in cancer therapy, outlines combinatorial strategies for nanocarriers and bacterial/bacterial components, and discusses their clinical applications.

The Cytotoxic Effect of Septic Plasma on Healthy RBCs: Is Eryptosis a New Mechanism for Sepsis?

Sepsis is a life-threatening multiple-organ dysfunction induced by infection and is one of the leading causes of mortality and critical illness worldwide. The pathogenesis of sepsis involves the alteration of several biochemical pathways such as immune response, coagulation, dysfunction of endothelium and tissue damage through cellular death and/or apoptosis. Recently, in vitro and in vivo studies reported changes in the morphology and in the shape of human red blood cells (RBCs) causing erythrocyte death (eryptosis) during sepsis. Characteristics of eryptosis include cell shrinkage, membrane blebbing, and surface exposure to phosphatidylserine (PS), which attract macrophages. The aim of this study was to evaluate the in vitro induction of eryptosis on healthy RBCs exposed to septic plasma at different time points. Furthermore, we preliminary investigated the in vivo levels of eryptosis in septic patients and its relationship with Endotoxin Activity Assay (EAA), mortality and other biological markers of inflammation and oxidative stress. We enrolled 16 septic patients and 16 healthy subjects (no systemic inflammation in the last 3 months) as a control group. At diagnosis, we measured Interleukin-6 (IL-6) and Myeloperoxidase (MPO). For in vitro study, healthy RBCs were exposed to the plasma of septic patients and CTR for 15 min, 1, 2, 4 and 24 h. Morphological markers of death and eryptosis were evaluated by flow cytometric analyses. The cytotoxic effect of septic plasma on RBCs was studied in vitro at 15 min, 1, 2, 4 and 24 h. Healthy RBCs incubated with plasma from septic patients went through significant morphological changes and eryptosis compared to those exposed to plasma from the control group at all time points (all, p < 0.001). IL-6 and MPO levels were significantly higher in septic patients than in controls (both, p < 0.001). The percentage of AnnexinV-binding RBCs was significantly higher in septic patients with EAA level ≥0.60 (positive EAA: 32.4%, IQR 27.6-36.2) compared to septic patients with EAA level <0.60 (negative EAA: 14.7%, IQR 5.7-30.7) (p = 0.04). Significant correlations were observed between eryptosis and EAA levels (Spearman rho2 = 0.50, p < 0.05), IL-6 (Spearman rho2 = 0.61, p < 0.05) and MPO (Spearman rho2 = 0.70, p < 0.05). In conclusion, we observed a quick and great cytotoxic effect of septic plasma on healthy RBCs and a strong correlation with other biomarkers of severity of sepsis. Based on these results, we confirmed the pathological role of eryptosis in sepsis and we hypothesized its use as a biomarker of sepsis, potentially helping physicians to face important treatment decisions.

The correlation of hemoglobin and 28-day mortality in septic patients: secondary data mining using the MIMIC-IV database

BACKGROUND

Previous studies found minimal evidence and raised controversy about the link between hemoglobin and 28-day mortality in sepsis patients. As a result, the purpose of this study was to examine the association between hemoglobin and 28-day death in sepsis patients by analyzing the Medical Intensive Care IV (MIMIC-IV) database from 2008 to 2019 at an advanced medical center in Boston, Massachusetts.

METHODS

We extracted 34,916 sepsis patients from the MIMIC-IV retrospective cohort database, using hemoglobin as the exposure variable and 28-day death as the outcome variable, and after adjusting for confounders (demographic indicators, Charlson co-morbidity index, SOFA score, vital signs, medication use status (glucocorticoids, vasoactive drugs, antibiotics, and immunoglobulins, etc.)), we investigated the independent effects of hemoglobin and 28-day risk of death by binary logistic regression as well as two-piecewise linear model, respectively.

RESULTS

Hemoglobin levels and 28-day mortality were shown to be non-linearly related.The inflection points were 104 g/L and 128 g/L, respectively. When HGB levels were between 41 and 104 g/L, there was a 10% decrease in the risk of 28-day mortality (OR: 0.90; 95% CI: 0.87 to 0.94, p-value = 0.0001). However, in the range of 104-128 g/L, we did not observe a significant association between hemoglobin and 28-day mortality (OR: 1.17; 95% CI: 1.00 to 1.35, P value = 0.0586). When HGB was in the range of 128-207 g/L, there was a 7% increase in the risk of 28-day mortality for every 1 unit increase in HGB (OR: 1.07; 95% CI: 1.01 to 1.15, P value = 0.0424).

CONCLUSION

In patients with sepsis, baseline hemoglobin was related to a U-shaped risk of 28-day death. When HGB was in the range of 12.8-20.7 g/dL, there was a 7% increase in the risk of 28-day mortality for every 1 unit increase in HGB.

Engineering Therapeutics to Detoxify Hemoglobin, Heme, and Iron

Hemolysis (i.e., red blood cell lysis) can increase circulatory levels of cell-free hemoglobin (Hb) and its degradation by-products, namely heme (h) and iron (Fe). Under homeostasis, minor increases in these three hemolytic by-products (Hb/h/Fe) are rapidly scavenged and cleared by natural plasma proteins. Under certain pathophysiological conditions, scavenging systems become overwhelmed, leading to the accumulation of Hb/h/Fe in the circulation. Unfortunately, these species cause various side effects such as vasoconstriction, hypertension, and oxidative organ damage. Therefore, various therapeutics strategies are in development, ranging from supplementation with depleted plasma scavenger proteins to engineered biomimetic protein constructs capable of scavenging multiple hemolytic species. In this review, we briefly describe hemolysis and the characteristics of the major plasma-derived protein scavengers of Hb/h/Fe. Finally, we present novel engineering approaches designed to address the toxicity of these hemolytic by-products.

A retrospective analysis of the hemolysis occurrence during extracorporeal membrane oxygenation in a single center

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO)-associated hemolysis still represents a serious complication. The present study aimed to investigate those predictive factors, such as flow rates, the use of anticoagulants, and circuit connected dialysis, that might play a pivotal role in hemolysis in adult patients.

METHODS

This is a retrospective single-center case series of 35 consecutive adult patients undergoing veno-venous ECMO support at our center between April 2014 and February 2020. Daily plasma-free hemoglobin (pfHb) and haptoglobin (Hpt) levels were chosen as hemolysis markers and they were analyzed along with patients' characteristics, daily laboratory findings, and corresponding ECMO system variables, as well as continuous renal replacement therapy (CRRT) when administered, looking for factors influencing their trends over time.

RESULTS

Among the many settings related to the ECMO support, the presence of CRRT connected to the ECMO circuit has been found associated with both higher daily pfHb levels and lower Hpt levels. After correction for potential confounders, hemolysis was ascribable to circuit-related variables, in particular the membrane oxygenation dead space was associated with an Hpt reduction (B = -215.307, p = 0.004). Moreover, a reduction of ECMO blood flow by 1 L/min has been associated with a daily Hpt consumption of 93.371 mg/dL (p = 0.001).

CONCLUSIONS

Technical-induced hemolysis during ECMO should be monitored not only when suspected but also during quotidian management and check-ups. While considering the clinical complexity of patients on ECMO support, clinicians should not only be aware of and anticipate possible circuitry malfunctions or inadequate flow settings, but they should also take into account the effects of an ECMO circuit-connected CRRT, as an equally important key factor triggering hemolysis.

Heme Scavenging and Delivery: The Role of Human Serum Albumin

Heme is the reactive center of several metal-based proteins that are involved in multiple biological processes. However, free heme, defined as the labile heme pool, has toxic properties that are derived from its hydrophobic nature and the Fe-atom. Therefore, the heme concentration must be tightly controlled to maintain cellular homeostasis and to avoid pathological conditions. Therefore, different systems have been developed to scavenge either Hb (i.e., haptoglobin (Hp)) or the free heme (i.e., high-density lipoproteins (HDL), low-density lipoproteins (LDL), hemopexin (Hx), and human serum albumin (HSA)). In the first seconds after heme appearance in the plasma, more than 80% of the heme binds to HDL and LDL, and only the remaining 20% binds to Hx and HSA. Then, HSA slowly removes most of the heme from HDL and LDL, and finally, heme transits to Hx, which releases it into hepatic parenchymal cells. The Hx:heme or HSA:heme complexes are internalized via endocytosis mediated by the CD91 and CD71 receptors, respectively. As heme constitutes a major iron source for pathogens, bacteria have evolved hemophores that can extract and uptake heme from host proteins, including HSA:heme. Here, the molecular mechanisms underlying heme scavenging and delivery from HSA are reviewed. Moreover, the relevance of HSA in disease states associated with increased heme plasma concentrations are discussed.

Interpreting Iron Homeostasis in Congenital and Acquired Disorders

Mammalian cells require iron to satisfy their metabolic needs and to accomplish specialized functions, such as hematopoiesis, mitochondrial biogenesis, energy metabolism, or oxygen transport. Iron homeostasis is balanced by the interplay of proteins responsible for iron import, storage, and export. A misbalance of iron homeostasis may cause either iron deficiencies or iron overload diseases. The clinical work-up of iron dysregulation is highly important, as severe symptoms and pathologies may arise. Treating iron overload or iron deficiency is important to avoid cellular damage and severe symptoms and improve patient outcomes. The impressive progress made in the past years in understanding mechanisms that maintain iron homeostasis has already changed clinical practice for treating iron-related diseases and is expected to improve patient management even further in the future.

Identification of iron metabolism-related genes in the circulation and myocardium of patients with sepsis via applied bioinformatics analysis

Background

Early diagnosis of septic cardiomyopathy is essential to reduce the mortality rate of sepsis. Previous studies indicated that iron metabolism plays a vital role in sepsis-induced cardiomyopathy. Here, we aimed to identify shared iron metabolism-related genes (IMRGs) in the myocardium and blood monocytes of patients with sepsis and to determine their prognostic signature.

Methods

First, an applied bioinformatics-based analysis was conducted to identify shared IMRGs differentially expressed in the myocardium and peripheral blood monocytes of patients with sepsis. Second, Cytoscape was used to construct a protein-protein interaction network, and immune infiltration of the septic myocardium was assessed using single-sample gene set enrichment analysis. In addition, a prognostic prediction model for IMRGs was established by Cox regression analysis. Finally, the expression of key mRNAs in the myocardium of mice with sepsis was verified using quantitative polymerase chain reaction analysis.

Results

We screened common differentially expressed genes in septic myocardium and blood monocytes and identified 14 that were related to iron metabolism. We found that HBB, SLC25A37, SLC11A1, and HMOX1 strongly correlated with monocytes and neutrophils, whereas HMOX1 and SLC11A1 strongly correlated with macrophages. We then established a prognostic model (HIF1A and SLC25A37) using the common differentially expressed IMRGs. The prognostic model we established was expected to better aid in diagnosing septic cardiomyopathy. Moreover, we verified these genes using datasets and experiments and found a significant difference between the sepsis and control groups.

Conclusion

Common differential expression of IMRGs was identified in blood monocytes and myocardium between sepsis and control groups, among which HIF1A and SLC25A37 might predict prognosis in septic cardiomyopathy. The study may help us deeply understand the molecular mechanisms of iron metabolism and aid in the diagnosis and treatment of septic cardiomyopathy.

Hemoglobin Casts in Kidney Biopsies: Etiological Spectrum

Intravascular hemolysis, which is the destruction of red blood cells in circulation, can cause acute kidney injury as the hemoglobin released by the lysed cells is toxic to the tubular epithelial cells. We performed a retrospective analysis of 56 cases of hemoglobin cast nephropathy reported at our institution to analyze the etiological spectrum causing this rare disease. The mean patient age was 41.7 (range: 2-72 years), and the male-to-female ratio was 1.8:1. All patients presented with acute kidney injury. The etiologies include rifampicin-induced, snake bite, autoimmune hemolytic anemia, falciparum malarial infection, leptospiral infection, autoimmune hemolytic anemia, sepsis, non-steroidal anti-inflammatory drugs, ingestion of termite oil, heavy metal poisoning, wasp sting, and valvular heart disease with severe mitral regurgitation. We demonstrate a wide spectrum of conditions associated with hemoglobin casts in the kidney biopsy. Hemoglobin immunostain is required to establish the diagnosis.

Personalized diagnostic approach and indirect quantification of extravasation in human anaphylaxis

BACKGROUND

Anaphylaxis is the most acute and life-threatening manifestation of allergic disorders. Currently, there is a need to improve its medical management and increase the understanding of its molecular mechanisms. This study aimed to quantify the extravasation underlying human anaphylactic reactions and propose new theragnostic approaches.

METHODS

Molecular determinations were performed in paired serum samples obtained during the acute phase and at baseline from patients presenting with hypersensitivity reactions. These were classified according to their severity as Grades 1, 2 and 3, the two latter being considered anaphylaxis. Tryptase levels were measured by ImmunoCAP, and serum protein concentration was quantified by Bradford assay. Human serum albumin (HSA) and haemoglobin beta subunit (HBB) levels were determined by Western blot and polyacrylamide gel electrophoresis, respectively.

RESULTS

A total of 150 patients were included in the study. Of them, 112 had experienced anaphylaxis (83 and 29 with Grade 2 and 3 reactions, respectively). Tryptase diagnostic efficiency substantially improved when considering patients' baseline values (33%-54%) instead of the acute value threshold (21%). Serum protein concentration and HSA significantly decreased in anaphylaxis (p < .0001). HSA levels dropped with the severity of the reaction (6% and 15% for Grade 2 and 3 reactions, respectively). Furthermore, HBB levels increased during the acute phase of all hypersensitivity reactions (p < .0001).

CONCLUSIONS

For the first time, the extravasation underlying human anaphylaxis has been evaluated based on the severity of the reaction using HSA and protein concentration measurements. Additionally, our findings propose new diagnostic and potential therapeutic approaches for this pathological event.

Coagulation and hemolysis complications in neonatal ECLS: Role of devices

Neonatal extracorporeal life support (ECLS) has enjoyed a long history of successful patient support for both cardiac and respiratory failure. The small size of this patient population has provided many technical challenges from cannulation to pumps and oxygenators. This is further complicated by the relatively meager commercial options for equipment owing to the relatively low utilization of neonatal ECLS compared to adults, which has exploded following the H1N1 epidemic and the availability of the polymethylpentene oxygenator. This paper focuses on the impact of equipment choices on thrombosis and hemolysis in neonatal ECLS and the underlying mechanisms behind them. Based upon the available evidence, it is clear neonatal ECLS requires careful attention to the selection and operation of all parts of the ECLS system. Practitioners should also be aware of the factors that increase blood cell fragility, which can impact decisions around equipment and subsequent operation.

Heme oxygenase-1 as a predictor of sepsis-induced acute kidney injury: a cross-sectional study

BACKGROUND

Sepsis patients suffer from severe inflammation and poor prognosis. Oxidative stress and local inflammation that results from sepsis can trigger organ injury, including acute kidney injury (AKI). Previous studies have shown that heme oxygenase-1 (HO-1) is overexpressed in proximal tubular cells under oxidative stress and has significant cytoprotective and anti-inflammatory effects. Heme-induced inflammation in sepsis is antagonized by increased tissue expression of heme oxygenase-1 (HO-1), which impacts on AKI development. The investigators observed intrarenal HO-1 expression and corresponding potential increases in plasma and urinary HO-1 protein concentrations in four different AKI models. Since serum levels of HO-1 reflect HO-1 expression, we aimed to investigate whether serum HO-1 could predict the development of AKI in sepsis patient.

METHODS

A total of 83 sepsis patients were enrolled in this study including septic patients with AKI and sepsis patients without AKI. According to the definition of septic shock and the global kidney diagnostic criteria described in the Kidney Disease: Improving Global Outcomes (KDIGO), patients were allocated to the sepsis and septic shock groups with and without AKI, respectively. The serum levels of HO-1 were measured by enzyme-linked immunosorbent assays (ELISA). Statistical analyses were performed using SPSS software.

RESULTS

There were statistically significant differences between septic patients with AKI and sepsis patients without AKI in terms of Sequential Organ Failure Assessment (SOFA) score, hospitalization time, and laboratory indicators including serum HO-1, creatine kinase MB (CK-MB), troponin I (TnI), urea, myoglobin (MYO), serum creatinine (Scr), procalcitonin, and activated partial thromboplastin time. Serum levels of alkaline phosphatase (ALP), urea, MYO, Scr, procalcitonin, activated partial thromboplastin time, and prothrombin time exhibited significant differences among the four groups. The concentration of serum HO-1 was higher in sepsis-induced AKI compared with sepsis patients without AKI. Serum HO-1 levels were increased in patients with sepsis shock-induced AKI. The area under the receiver operating characteristic (ROC) curve for serum HO-1 combined with Scr was 0.885 [95% confidence interval (CI): 0.761-1.000].

CONCLUSIONS

Serum HO-1 is positively correlated with sepsis-induced AKI. These findings suggest that measurement of serum HO-1 may play a diagnostic and prediction role in sepsis-induced AKI.

High-Level Expression of Cell-Surface Signaling System Hxu Enhances Pseudomonas aeruginosa Bloodstream Infection

Bloodstream infections (BSIs) caused by Pseudomonas aeruginosa are associated with a high mortality rate in the clinic. However, the fitness mechanisms responsible for the evolution of virulence factors that facilitate the dissemination of P. aeruginosa to the bloodstream are poorly understood. In this study, a transcriptomic analysis of the BSI-associated P. aeruginosa clinical isolates showed a high-level expression of cell-surface signaling (CSS) system Hxu. Whole-genome sequencing and comparative genomics of these isolates showed that a mutation in rnfE gene was responsible for the elevated expression of the Hxu-CSS pathway. Most importantly, deletion of the hxuIRA gene cluster in a laboratory strain PAO1 reduced its BSI capability while overexpression of the HxuIRA pathway promoted BSI in a murine sepsis model. We further demonstrated that multiple components in the blood plasma, including heme, hemoglobin, the heme-scavenging proteins haptoglobin, and hemopexin, as well as the iron-delivery protein transferrin, could activate the Hxu system. Together, these studies suggested that the Hxu-CSS system was an important signal transduction pathway contributing to the adaptive pathogenesis of P. aeruginosa in BSI.

Novel aspects of sepsis pathophysiology: NETs, plasma glycoproteins, endotheliopathy and COVID-19

In 2016, sepsis was newly defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis remains one of the crucial medical problems to be solved worldwide. Although the world health organization has made sepsis a global health priority, there remain no specific and effective therapy for sepsis so far. Indeed, over the previous decades almost all attempts to develop novel drugs have failed. This may be partly ascribable to the multifactorial complexity of the septic cascade and the resultant difficulties of identifying drug targets. In addition, there might still be missing links among dysregulated host responses in vital organs. In this review article, recent advances in understanding of the complex pathophysiology of sepsis are summarized, with a focus on neutrophil extracellular traps (NETs), the significant role of NETs in thrombosis/embolism, and the functional roles of plasma proteins, histidine-rich glycoprotein (HRG) and inter-alpha-inhibitor proteins (IAIPs). The specific plasma proteins that are markedly decreased in the acute phase of sepsis may play important roles in the regulation of blood cells, vascular endothelial cells and coagulation. The accumulating evidence may provide us with insights into a novel aspect of the pathophysiology of sepsis and septic ARDS, including that in COVID-19.

Probiotic potential of Tetragenococcus halophilus EFEL7002 isolated from Korean soy Meju

BACKGROUND

Probiotic starters can improve the flavor profile, texture, and health-promoting properties of fermented foods. Tetragenococcus halophilus is a halophilic lactic acid bacterium that is a candidate starter for high-salt fermented foods. However, the species is known to produce biogenic amines, which are associated with neurotoxicity. Here, we report a probiotic starter strain of T. halophilus, EFEL7002, that is suitable for use in high-salt fermentation.

RESULTS

EFEL7002 was isolated from Korean meju (fermented soybean) and identified as T. halophilus, with 99.85% similarity. The strain is safe for use in food as it is a non-hemolytic and non-biogenic amine producer. EFEL7002 is tolerant to gastrointestinal conditions and can adhere to Caco-2 cells. This strain showed antioxidant, anti-inflammatory, and protective effects against the human gut epithelial barrier. EFEL7002 grew well in media containing 0-18% NaCl showing maximum cell densities in 6% or 12% NaCl.

CONCLUSIONS

T. halophilus EFEL7002 can be used as a health-promoting probiotic starter culture for various salty fermented foods.

Hematological Abnormalities in Culture Positive Neonatal Sepsis

Background

In neonatal sepsis, anemia, leukocytosis, thrombocytopenia, and a shortened coagulation time are the most common hematologic abnormalities. However, there is inadequate information regarding the hematological abnormalities in neonatal sepsis. Thus, we aimed to determine the magnitude of hematological abnormalities in neonatal sepsis.

Methods

This is a cross-sectional study that included 143 neonates with culture proven sepsis aged 1–28 days from September 2020 to November 2021 at the University of Gondar Specialized Referral Hospital. The sociodemographic data was collected using a pre-tested structured questionnaire, and the clinical and laboratory data was collected using a data collection sheet. A total of 2 mL of venous blood was taken using a vacutainer collection device for the complete blood count (CBC) and blood culture analysis. A univariate and multivariate logistic regression model was used to investigate factors associated with hematological abnormalities in neonatal sepsis. Statistical significance was declared when a p-value was less than 0.05.

Results

The prevalence of anemia, thrombocytopenia, and leucopenia in neonatal sepsis was 49% (95% CI: 40.89–57.06), 44.7% (95% CI: 36.8–52.9), and 26.6% (95% CI: 22.01–29.40), respectively. On the other hand, leukocytosis and thrombocytosis were found in 7.7% (95% CI: 4.35–13.25) and 11.9% (95% CI: 7.56–18.21), respectively. Being female (AOR: 3.3; 95% CI: 1.20–3.82) and being aged less than 7 days (AOR: 2.44; 95% CI: 1.6–6.9) were found to be significant predictors of anemia.

Conclusion

The magnitude of anemia, leucopenia, and thrombocytopenia is high in neonatal sepsis. Furthermore, being female and being younger than 7 days were risk factors for anemia. Thus, the diagnosis and treatment of anemia, leucopenia, and thrombocytopenia prevents further complications in neonatal sepsis.

Injectable Self-Healing First-Aid Tissue Adhesives with Outstanding Hemostatic and Antibacterial Performances for Trauma Emergency Care

Soft-tissue trauma emergency caused by natural disasters and traffic accidents is highly prevalent, which can result in massive bleeding, pathogen infection, and even death. Although numerous tissue adhesives can bind to tissue surfaces and cover wounds, most of them still have several deficiencies, including long gelation time, poor adhesive strength, and anti-infection, making them inappropriate for use as first-aid bandages. Herein, injectable and self-healing four-arm-PEG-CHO/polyethyleneimine (PEI) tissue adhesives as liquid first-aid supplies are developed via the dynamic Schiff base reaction for trauma emergency. It is found that the prepared hydrogel adhesives exhibit short and controlled gelation time (9∼88 s), strong adhesive strength, and excellent antibacterial ability. Their hemostatic and antimicrobial performances can be tailored by the mass ratio of four-arm-PEG-CHO/PEI. Moreover, in vitro biological assays display that the developed tissue adhesives possess satisfactory cyto/hemocompatibility. Importantly, in vivo the designed adhesives show fast hemostatic capacity and excellent anti-infection as compared to commercial Prontosan gel. Thus, this work indicates that the four-arm-PEG-CHO/PEI first-aid tissue adhesives display great potential for wound emergency management.

[A new approach to combat the sepsis including COVID-19 by accelerating detoxification of hemolysis-related DAMPs]

Sepsis is one of the leading cause of death worldwide. Recently, several studies suggested that free-hemoglobin and heme derived from hemolysis are important factors which may be associated with severity of septic patients including COVID-19. In other words, hemolysis-derived products enhance the inflammatory responses as damage-associated molecular patterns (DAMPs) in both intravascular and extravascular space. In addition, hemoglobin has vasoconstrictive activity by depleting nitric oxide, whereas heme or Fe²⁺ produce reactive oxygen species (ROS) through Fenton reaction leading to tissue injury. At present, we have no therapeutic options against sepsis-related hemolysis in clinical settings, however, there might be two therapeutic strategies in this regard. One is supplemental therapy of depleted scavenging proteins such as haptoglobin and hemopexin, the other is activation of the internal scavenging system including macrophage-CD163 pathway. These novel targets against sepsis are also critical for the next pandemic. In this review, we summarize the current issues regarding sepsis-related hemolysis including COVID-19, as well as for future perspectives.

Erythrocyte degradation, metabolism, secretion, and communication with immune cells in the blood during sepsis: A review

Sepsis is a health issue that affects millions of people worldwide. It was assumed that erythrocytes were affected by sepsis. However, in recent years, a number of studies have shown that erythrocytes affect sepsis as well. When a pathogen invades the human body, it infects the blood and organs, causing infection and sepsis-related symptoms. Pathogens change the internal environment, increasing the levels of reactive oxygen species, influencing erythrocyte morphology, and causing erythrocyte death, i.e., eryptosis. Characteristics of eryptosis include cell shrinkage, membrane blebbing, and surface exposure of phosphatidylserine (PS). Eryptotic erythrocytes increase immune cell proliferation, and through PS, attract macrophages that remove the infected erythrocytes. Erythrocyte-degraded hemoglobin derivatives and heme deteriorate infection; however, they could also be metabolized to a series of derivatives. The result that erythrocytes play an anti-infection role during sepsis provides new perspectives for treatment. This review focuses on erythrocytes during pathogenic infection and sepsis.

Adropin decreases endothelial monolayer permeability after cell-free hemoglobin exposure and reduces MCP-1-induced macrophage transmigration

BACKGROUND

Cell-free heme-containing proteins mediate endothelial injury in a variety of disease states including subarachnoid hemorrhage and sepsis by increasing endothelial permeability. Inflammatory cells are also attracted to sites of vascular injury by monocyte chemotactic protein 1 (MCP-1) and other chemokines. We have identified a novel peptide hormone, adropin, that protects against hemoglobin-induced endothelial permeability and MCP-1-induced macrophage migration.

METHODS

Human microvascular endothelial cells were exposed to cell-free hemoglobin (CFH) with and without adropin treatment before measuring monolayer permeability using a FITC-dextran tracer assay. mRNA and culture media were collected for molecular studies. We also assessed the effect of adropin on macrophage movement across the endothelial monolayer using an MCP-1-induced migration assay.

RESULTS

CFH exposure decreases adropin expression and increases paracellular permeability of human endothelial cells. Treating cells with synthetic adropin protects against the increased permeability observed during the natural injury progression. Cell viability was similar in all groups and Hmox1 expression was not affected by adropin treatment. MCP-1 potently induced macrophage migration across the endothelial monolayer and adropin treatment effectively reduced this phenomenon.

CONCLUSIONS

Endothelial injury is a hallmark of many disease states. Our results suggest that adropin treatment could be a valuable strategy in preventing heme-mediated endothelial injury and macrophage infiltration. Further investigation of adropin therapy in animal models and human tissue specimens is needed.

Heme stimulates platelet mitochondrial oxidant production to induce targeted granule secretion

Hemolysis, a pathological component of many diseases, is associated with thrombosis and vascular dysfunction. Hemolytic products, including cell-free hemoglobin and free heme directly activate platelets. However, the effect of hemolysis on platelet degranulation, a central process in not only thrombosis, but also inflammatory and mitogenic signaling, remains less clear. Our group showed that hemoglobin-induced platelet activation involved the production of mitochondrial reactive oxygen species (mtROS). However, the molecular mechanism by which extracellular hemolysis induces platelet mtROS production, and whether these mtROS regulate platelet degranulation remains unknown. Here, we demonstrate using isolated human platelets that cell free heme is a more potent agonist for platelet activation than hemoglobin, and stimulates the release of a specific set of molecules, including the glycoprotein thrombospondin-1 (TSP-1), from the α-granule of platelets. We uncover the mechanism of heme-mediated platelet mtROS production which is dependent on the activation of platelet toll-like receptor 4 (TLR4) signaling and leads to the downstream phosphorylation and inhibition of complex-V by the serine kinase Akt. Notably, inhibition of platelet TLR4 or Akt, or scavenging of mtROS prevents heme-induced granule release in vitro. Further, heme-dependent granule release is significantly attenuated in vivo in mice lacking TLR4 or those treated with the mtROS scavenger MitoTEMPO. These data elucidate a novel mechanism of TLR4-mediated mitochondrial regulation, establish the mechanistic link between hemolysis and platelet degranulation, and begin to define the heme and mtROS-dependent platelet secretome. These data have implications for hemolysis-induced thrombo-inflammatory signaling and for the consideration of platelet mitochondria as a therapeutic target in hemolytic disorders.

The Value of a Complete Blood Count (CBC) for Sepsis Diagnosis and Prognosis

Sepsis represents an important global health burden due to its high mortality and morbidity. The rapid detection of sepsis is crucial in order to prevent adverse outcomes and reduce mortality. However, the diagnosis of sepsis is still challenging and many efforts have been made to identify reliable biomarkers. Unfortunately, many investigated biomarkers have several limitations that do not support their introduction in clinical practice, such as moderate diagnostic and prognostic accuracy, long turn-around time, and high-costs. Complete blood count represents instead a precious test that provides a wealth of information on individual health status. It can guide clinicians to early-identify patients at high risk of developing sepsis and to predict adverse outcomes. It has several advantages, being cheap, easy-to-perform, and available in all wards, from the emergency department to the intensive care unit. Noteworthy, it represents a first-level test and an alteration of its parameters must always be considered within the clinical context, and the eventual suspect of sepsis must be confirmed by more specific investigations. In this review, we describe the usefulness of basic and new complete blood count parameters as diagnostic and prognostic biomarkers of sepsis.

Complement C5 inhibition protects against hemolytic anemia and acute kidney injury in anthrax peptidoglycan-induced sepsis in baboons

Late-stage anthrax infections are characterized by dysregulated immune responses and hematogenous spread of Bacillus anthracis, leading to extreme bacteremia, sepsis, multiple organ failure, and, ultimately, death. Despite the bacterium being nonhemolytic, some fulminant anthrax patients develop a secondary atypical hemolytic uremic syndrome (aHUS) through unknown mechanisms. We recapitulated the pathology in baboons challenged with cell wall peptidoglycan (PGN), a polymeric, pathogen-associated molecular pattern responsible for the hemostatic dysregulation in anthrax sepsis. Similar to aHUS anthrax patients, PGN induces an initial hematocrit elevation followed by progressive hemolytic anemia and associated renal failure. Etiologically, PGN induces erythrolysis through direct excessive activation of all three complement pathways. Blunting terminal complement activation with a C5 neutralizing peptide prevented the progressive deposition of membrane attack complexes on red blood cells (RBC) and subsequent intravascular hemolysis, heme cytotoxicity, and acute kidney injury. Importantly, C5 neutralization did not prevent immune recognition of PGN and shifted the systemic inflammatory responses, consistent with improved survival in sepsis. Whereas PGN-induced hemostatic dysregulation was unchanged, C5 inhibition augmented fibrinolysis and improved the thromboischemic resolution. Overall, our study identifies PGN-driven complement activation as the pathologic mechanism underlying hemolytic anemia in anthrax and likely other gram-positive infections in which PGN is abundantly represented. Neutralization of terminal complement reactions reduces the hemolytic uremic pathology induced by PGN and could alleviate heme cytotoxicity and its associated kidney failure in gram-positive infections.

Complement-mediated autoimmune haemolytic anaemia as an initial presentation of Legionnaires' disease

A 42-year-old diabetic man presented to the hospital with severe sepsis and multiorgan dysfunction. A probable respiratory source of sepsis was suspected because of suggestive clinical and radiological findings. He was critically ill and was therefore admitted to intensive care for further management including ventilatory support and renal replacement therapy. He was also found to have marked anaemia requiring multiple blood transfusions with clinical and laboratory evidence pointing towards severe haemolysis. Further workup for the aetiology of pneumonia established a diagnosis of Legionella by confirmatory tests namely legionella antigen in the urine and exponentially rising serum antibody titres. The cause for the severe haemolysis was found to be complement-mediated autoimmune haemolysis as determined by direct antiglobulin test positive for complement components C3 and negative for IgG. Such clinically significant autoimmune haemolysis as a presenting feature, rather than a late complication, has never before been reported in the literature.

Selenocompounds and Sepsis: Redox Bypass Hypothesis for Early Diagnosis and Treatment: Part A-Early Acute Phase of Sepsis: An Extraordinary Redox Situation (Leukocyte/Endothelium Interaction Leading to Endothelial Damage)

Significance: Sepsis is a health disaster. In sepsis, an initial, beneficial local immune response against infection evolves rapidly into a generalized, dysregulated response or a state of chaos, leading to multiple organ failure. Use of life-sustaining supportive therapies creates an unnatural condition, enabling the complex cascades of the sepsis response to develop in patients who would otherwise die. Multiple attempts to control sepsis at an early stage have been unsuccessful. Recent Advances: Major events in early sepsis include activation and binding of leukocytes and endothelial cells in the microcirculation, damage of the endothelial surface layer (ESL), and a decrease in the plasma concentration of the antioxidant enzyme, selenoprotein-P. These events induce an increase in intracellular redox potential and lymphocyte apoptosis, whereas apoptosis is delayed in monocytes and neutrophils. They also induce endothelial mitochondrial and cell damage. Critical Issues: Neutrophil production increases dramatically, and aggressive immature forms are released. Leukocyte cross talk with other leukocytes and with damaged endothelial cells amplifies the inflammatory response. The release of large quantities of reactive oxygen, halogen, and nitrogen species as a result of the leukocyte respiratory burst, endothelial mitochondrial damage, and ischemia/reperfusion processes, along with the marked decrease in selenoprotein-P concentrations, leads to peroxynitrite damage of the ESL, reducing flow and damaging the endothelial barrier. Future Directions: Endothelial barrier damage by activated leukocytes is a time-sensitive event in sepsis, occurring within hours and representing the first step toward organ failure and death. Reducing or stopping this event is necessary before irreversible damage occurs.

Cell-free hemoglobin is a marker of systemic inflammation in mouse models of sepsis: a Raman spectroscopic study

Sepsis is a life-threatening condition caused by heightened host immune responses post infection. Despite intensive research, most of the existing diagnostic methods remain non-specific, labour-intensive, time-consuming or are not sensitive enough for rapid and timely diagnosis of the onset and progression of sepsis. The present work was undertaken to explore the potential of Raman spectroscopy to identify the biomarkers of sepsis in a label-free and minimally invasive manner using different mouse models of inflammation. The sera of BALB/c mice infected with Salmonella Typhimurium reveal extensive hemolysis, as indicated by the Raman bands that are characteristic of the porphyrin ring of hemoglobin (668, 743, 1050, 1253 and 1397 cm-1) which increase in a kinetic manner. These markers are also observed in a lipopolysaccharide-induced endotoxic shock model, but not in a thioglycollate-induced sterile peritonitis model. These data demonstrate that hemolysis is a signature of systemic, but not localised, inflammation. To further validate our observations, sepsis was induced in the nitric oxide synthase 2 (Nos2-/-) deficient strain which is more sensitive to infection. Interestingly, Nos2-/- mice exhibit a higher degree of hemolysis than C57BL/6 mice. Sepsis-induced hemolysis was also confirmed using resonance Raman spectroscopy with 442 nm excitation which demonstrated a pronounced increase in the resonant Raman bands at 670 and 1350 cm-1 in sera of the infected mice. This is the first study to identify inflammation-induced hemolysis in mouse models of sepsis using Raman spectral signatures for hemoglobin. The possible implications of this method in detecting hemolysis in different inflammatory pathologies, such as the ongoing COVID-19 pandemic, are discussed.

Association of fluid balance with mortality in sepsis is modified by admission hemoglobin levels: A large database study

Purpose

Sepsis involves a dysregulated inflammatory response to infection that leads to organ dysfunction. Early fluid resuscitation has been advocated by the Surviving Sepsis Campaign guidelines. However, recent studies have shown that a positive fluid balance is associated with increased mortality in septic patients. We investigated if haemoglobin levels on admission to the intensive care unit (ICU) could modify the association of fluid balance with mortality in patients with sepsis. We hypothesized that with increasing fluid balance, patients with moderate anemia (hemoglobin 7-10g/dL) would have poorer outcomes compared to those without moderate anemia (hemoglobin >10g/dL).

Materials and methods

This retrospective study utilized the Medical Information Mart for Intensive Care-III (MIMIC-III) database. Patients with sepsis, as identified by the International Classification of Diseases, 9th, Clinical Modification codes, were studied. Patients were stratified into those with and without moderate anemia at ICU admission. We investigated the influence of fluid balance measured within 24 hours of ICU admission on 28-day mortality for both patient groups using multivariable logistic regression models. Subgroup and sensitivity analyses were conducted.

Results

8,132 patients (median age 68.6 years, interquartile range 55.1–79.8 years; 52.8% female) were included. Increasing fluid balance (in L) was associated with a significantly decreased risk of 28-day mortality in patients without moderate anemia (OR 0.91, 95%CI 0.84–0.97, p = 0.005, at 6-hour). Conversely, increasing fluid balance was associated with a significantly increased risk of 28-day mortality in patients with moderate anemia (OR 1.05, 95% CI 1.01–1.1, p = 0.022, at 24-hour). Interaction analyses showed that mortality was highest when haemoglobin decreased in patients with moderate anemia who had the most positive fluid balance. Multiple subgroups and sensitivity analyses yielded consistent results.

Conclusions

In septic patients admitted to ICU, admission hemoglobin levels modified the association between fluid balance and mortality and are an important consideration for future fluid therapy trials.

Heme oxygenase-1: Equally important in allogeneic hematopoietic stem cell transplantation and organ transplantation?

The intracellular enzyme heme oxygenase-1 (HO-1) is responsible for the degradation of cell-free (cf) heme. Cfheme, released upon cell damage and cell death from hemoglobin, mitochondria and myoglobin, functions as a powerful damage-associated molecular pattern (DAMP). Indeed, cfheme plays a role in a myriad of diseases characterized by (systemic) inflammation, and its rapid degradation by HO-1 is pivotal to maintain homeostasis. In the past decade, HO-1 has been extensively studied for its potential protective role in different transplantation settings, including allogeneic hematopoietic stem cell transplantation (HSCT), solid organ transplantation and pancreatic islet transplantation. These studies have shown that HO-1 can be induced by a wide range of molecules, and that induction of HO-1 has the potential to significantly reduce the incidence and severity of transplantation-related complications such as graft-versus-host disease (GvHD) and ischemia/reperfusion injury (IRI). As such, further investigation into the use of HO-1-inducing agents in human transplantation settings to facilitate the potential use of these agents in the clinic is warranted. In this review, we summarize the literature of the past 10 years on the role of HO-1 in allogeneic HSCT, solid organ transplantation (focusing on kidney and liver) and pancreatic islet transplantation. Furthermore, we provide a hypothesis about the way that HO-1 is able to provide protection against acute GvHD after allogeneic HSCT. A total of 48 research articles and 17 review articles were included in this review.

Effect of Reactive Oxygen Species on the Endoplasmic Reticulum and Mitochondria during Intracellular Pathogen Infection of Mammalian Cells

Oxidative stress, particularly reactive oxygen species (ROS), are important for innate immunity against pathogens. ROS directly attack pathogens, regulate and amplify immune signals, induce autophagy and activate inflammation. In addition, production of ROS by pathogens affects the endoplasmic reticulum (ER) and mitochondria, leading to cell death. However, it is unclear how ROS regulate host defense mechanisms. This review outlines the role of ROS during intracellular pathogen infection, mechanisms of ROS production and regulation of host defense mechanisms by ROS. Finally, the interaction between microbial pathogen-induced ROS and the ER and mitochondria is described.

Enhanced Eradication of Bacterial/Fungi Biofilms by Glucose Oxidase-Modified Magnetic Nanoparticles as a Potential Treatment for Persistent Endodontic Infections

Bacterial/fungal biofilm-mediated persistent endodontic infections (PEIs) are one of the most frequent clinical lesions in the oral cavity, resulting in apical periodontitis and tooth damage caused by loss of minerals. The conventional root canal disinfectants are poorly bio-safe and harmful to teeth and tissues, making them ineffective in treating PEIs. The development of nanomaterials is emerging as a promising strategy to eradicate disease-related bacteria/fungi. Herein, glucose oxidase (GOx)-modified magnetic nanoparticles (MNPs) were synthesized via a facile and versatile route for investigating their effects on removing PEI-related bacterial/fungal biofilms. It is found that GOx was successfully immobilized on the MNPs by detecting the changes in the diameter, chemical functional group, charge, and magnetic response. Further, we demonstrate that GOx-modified MNPs (GMNPs) exhibit highly effective antibacterial activity against Enterococcus faecalis and Candida albicans. Moreover, the antibacterial/fungal activity of GMNPs is greatly dependent on their concentrations. Importantly, when placed in contact with bacterial/fungal biofilms, the dense biofilm matrix is destructed due to the movement of GMNPs induced by the magnetic field, the formation of reactive oxygen species, and nutrient starvation induced by GOx. Also, the in vitro experiment shows that the as-prepared GMNPs have excellent cytocompatibility and blood compatibility. Thus, GMNPs offer a novel strategy to treat bacteria/fungi-associated PEIs for potential clinical applications.

Cell-free hemoglobin-mediated human lung microvascular endothelial barrier dysfunction is not mediated by cell death

Circulating cell-free hemoglobin (CFH) contributes to endothelial injury in several inflammatory and hemolytic conditions. We and others have shown that CFH causes increased endothelial permeability, but the precise mechanisms of CFH-mediated endothelial barrier dysfunction are not fully understood. Based on our previous study in a mouse model of sepsis demonstrating that CFH increased apoptosis in the lung, we hypothesized that CFH causes endothelial barrier dysfunction through this cell death mechanism. We first confirmed that CFH causes human lung microvascular barrier dysfunction in vitro that can be prevented by the hemoglobin scavenger, haptoglobin. While CFH caused a small but significant decrease in cell viability measured by the membrane impermeable DNA dye Draq7 in human lung microvascular endothelial cells, CFH did not increase apoptosis as measured by TUNEL staining or Western blot for cleaved caspase-3. Moreover, inhibitors of apoptosis (Z-VAD-FMK), necrosis (IM-54), necroptosis (necrostatin-1), ferroptosis (ferrostatin-1), or autophagy (3-methyladenine) did not prevent CFH-mediated endothelial barrier dysfunction. We conclude that although CFH may cause a modest decrease in cell viability over time, cell death does not contribute to CFH-mediated lung microvascular endothelial barrier dysfunction.

Impact of Circuit Size on Coagulation and Hemolysis Complications in Pediatric Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) circuit volume, patient size, and blood flow may influence coagulation and hemolysis complications. We performed a single-center retrospective analysis of ECMO patients over a 6.5 year period. In 299 ECMO runs, 13% required coagulation-associated circuit changes. Respiratory ECMO was associated with coagulation-associated circuit changes [odds ratio (O/R) 2.8, p < 0.05] and developed severe (plasma-free hemoglobin [pfHb] > 100 mg/dl) hemolysis (O/R 2.3, p < 0.05). Severe hemolysis and component changes were associated with hospital mortality (O/R 2.3 and 2.5, respectively, p < 0.05). The activated partial thromboplastin time (aPTT) to residence time (RT) ratio (aPTT/RT) was used as a surrogate for coagulation risk. We found that aPTT/RT > 2.5 more than doubled time to circuit change (3-8 days, p < 0.05), but aPTT/RT > 3 increased bleeding risks and hospital mortality (O/R 1.8; p < 0.1). Hemolysis was associated with patient weight and circuit to patient volume ratio (CPVR) (p < 0.05), but not pump type. Hemolysis slightly increased with transfusion (p = 0.08), and transfusion requirements increased for CPVR >50% (p < 0.1).Our data suggest that pediatric respiratory ECMO patients are more likely to develop coagulation and hemolysis complications, which are associated with increased mortality. This may result from higher inflammatory processes, which affect coagulation and red cell fragility. Minimizing circuit volume, inflammation, and red cell stress may help to reduce these two complications and their associated mortality.

Risk Factors for Hemolysis During Extracorporeal Life Support for Congenital Diaphragmatic Hernia

BACKGROUND

Neonates receiving extracorporeal life support (ECLS) for congenital diaphragmatic hernia (CDH) require prolonged support compared with neonates with other forms of respiratory failure. Hemolysis is a complication that can be seen during ECLS and can lead to renal failure and potentially to worse outcomes. The purpose of this study was to identify risk factors for the development of hemolysis in CDH patients treated with ECLS.

METHODS

The Extracorporeal Life Support Organization database was used to identify infants with CDH (2000-2015). The primary outcome was hemolysis (plasma-free hemoglobin >50 mg/dL). Potentially associated variables were identified in the data set. Descriptive statistics and a series of nested multivariable logistic regression models were used to identify associations between hemolysis and demographic, pre-ECLS, and on-ECLS factors.

RESULTS

There were 4576 infants with a mortality of 52.5%. The overall mean rate of hemolysis was 10.5% during the study period. In earlier years (2000-2005), the hemolysis rates were 6.3% and 52.7% for roller versus centrifugal pumps, whereas in later years (2010-2015), they were 2.9% and 26.5%, respectively. The fully adjusted model demonstrated that the use of centrifugal pumps was a strong predictor of hemolysis (odds ratio: 6.67, 95% confidence interval: 5.14-8.67). In addition, other risk factors for hemolysis included low 5-min Apgar score, on-ECLS complications (renal, metabolic, and cardiovascular), and duration of ECLS.

CONCLUSIONS

In our cohort of CDH patients receiving ECLS over 15 y, the use of centrifugal pumps increased over time, along with the rate of hemolysis. Patient- and treatment-level risk factors were identified contributing to the development of hemolysis.

Serum levels of neurofilament light chain, neuron-specific enolase and S100 calcium-binding protein B during acute bacterial meningitis: a prospective cohort study

PURPOSE

Acute bacterial meningitis (ABM) is a severe disease with an overall poor outcome. Neurofilament (NFL) has shown to be a promising biomarker of neuroaxonal injury in various neurological disorders but has not been investigated in ABM. The aims of this study were (i) to obtain a temporal profile of NFL, neuron-specific enolase (NSE) and S100B in serum during ABM, and (ii) to evaluate their use as biomarkers of severity (Glasgow coma score) and prognosis (Glasgow Outcome Score, GOS and death) in severe ABM.

METHODS

Fifteen adults with severe community-acquired ABM who were admitted to the intensive care unit (ICU) and fulfilled the inclusion criteria were included. Lumbar puncture and blood tests were performed on admission, and blood tests were performed three times daily during the ICU stay. GOS was obtained day 30.

RESULTS

Serum NFL was significantly elevated in ABM patients compared to healthy controls, both at admission and throughout the observation period (p < .01). NFL increased significantly from day 1 up to day 3-6 (p < .0001), peaking day 6. NSE increased significantly from admission up to day 3 (p < .01). At day 5-6, the serum values were not significantly different from values at admission. The highest median serum value of S100B was observed at admission (0.10 µg/L, IQR 0.06-0.14), significantly decreasing day 4-6 (p < .05). None of the investigated biomarkers revealed significant correlation with severity and prognosis.

CONCLUSION

This study represents a first clinical observation of the temporal profile of NFL in serum, in severe ABM. No correlation with severity or prognosis.

Molecular Insights and Functional Consequences of the Interaction of Heme with Activated Protein C

Aims: In hemolysis, which is accompanied by increased levels of labile redox-active heme and is often associated with hemostatic abnormalities, a decreased activity of activated protein C (APC) is routinely detected. APC is a versatile enzyme that exerts its anticoagulant function through inactivation of clotting factors Va and VIIIa. APC has not been demonstrated to be affected by heme as described for other clotting factors and, thus, is a subject of investigation. Results: We report the interaction of heme with APC and its impact on the protein function by employing spectroscopic and physiologically relevant methods. Binding of heme to APC results in inhibition of its amidolytic and anticoagulant activity, increase of the peroxidase-like activity of heme, and protection of human umbilical vein endothelial cells from heme-induced hyperpermeability. To define the sites that are responsible for heme binding, we mapped the surface of APC for potential heme-binding motifs. T²⁸⁵GWGYHSSR²⁹³ and W³⁸⁷IHGHIRDK³⁹⁵, both located on the basic exosite, turned out as potential heme-binding sites. Molecular docking employing a homology model of full-length APC indicated Tyr²⁸⁹ and His³⁹¹ as the Fe(III)-coordinating amino acids. Innovation: The results strongly suggest that hemolysis-derived heme may directly influence the protein C pathway through binding to APC, conceivably explaining the decreased activity of APC under hemolytic conditions. Further, these results extend our understanding of heme as a multifaceted effector molecule within coagulation and may allow for an improved understanding of disease development in hemostasis under hemolytic conditions. Conclusion: Our study identifies APC as a heme-binding protein and provides insights into the functional consequences.

Metabolic and Hematological Responses to Endotoxin-Induced Inflammation in Chicks Experiencing Embryonic 2,3,7,8-Tetrachlorodibenzodioxin Exposure

Dioxin exposure during bird embryonic development disrupts immunity as well as mechanisms involved in energy metabolism, potentially affecting negatively acute-phase responses to pathogens. Thus, we hypothesized that embryonic exposure to 2,3,7,8-tetrachlorodibenzodioxin (TCDD) changes the metabolism and blood physiology of domestic chicks, affecting their physiological competence for responding to immune challenges. To test this hypothesis, we injected doses of 0, 1.5, and 3 ng TCDD/egg (based on survival experiments) on embryonic day 4 and then measured O₂ consumption and CO₂ production for metabolic rate, ventilation, and body temperature (T_B ) in 5-d-old chicks. Then, chicks were injected with lipopolysaccharide (LPS, endotoxin) or saline prior to repeating the physiological measurements. A second chick group exposed to identical TCDD and LPS treatments had blood partial pressure of oxygen, partial pressure of carbon dioxide, pH, bicarbonate concentration, lactate concentration, osmolality, hemoglobin concentration, red blood cell concentration, and hematocrit, as well as T_B , analyzed at 1 and 5 h after LPS injection. Metabolism in chicks embryonically exposed to 1.5 and 3 ng TCDD/egg was up to 37% higher, whereas body mass of chicks exposed to 3 ng TCDD/egg was approximately 6% lower. Chicks embryonically exposed to 3 ng TCDD/egg challenged with LPS showed a relative persistent hypometabolism accompanied by elimination of the normal hematological and osmotic responses to LPS. We conclude that embryonic exposure to TCDD affects posthatching metabolism as well as impairs metabolic, hematological, and osmotic responses to LPS. Environ Toxicol Chem 2020;39:2208-2220. © 2020 SETAC.