Association of whole blood metals/metalloids with severity in sepsis patients: A prospective, single-center, pilot study

BACKGROUND

Trace metals/metalloids were important for the biological functions of both the eukaryotic host and the microorganism. Their concentrations and variations may associate with the critical illness in sepsis, which still needs to be investigated.

METHODS

We performed a prospective cohort study on the patients with sepsis admitted to Tongji hospital (Wuhan, China) from Jul 01 to Dec 31, 2021. Sepsis was diagnosed in accordance with the third international consensus definitions for sepsis and septic shock (Sepsis-3). The concentrations of metals/metalloids including magnesium (Mg), calcium (Ca), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg), thallium (Tl) and lead (Pb) in whole blood were analyzed by ICP-MS based methods.

RESULTS

Compared to the healthy controls, patients with sepsis showed higher levels of Ca, Cr and Cu, and lower levels of Mg, Mn, Fe, Zn, As, Hg and Pb. Further analysis between the critical illness and noncritical illness, revealed the Mn, Fe were significantly lower in the critically-ill sepsis. The longitudinal profile of the two metals show the differences appeared to exist almost throughout the clinical course. By performing the binary regression logistic analysis, we determined the Fe, Mn as independently risk factors for critical illness in sepsis, with effect sizes (β) of 17.14 (95%CI: 1.79-163.81) and 10.83 (1.96-59.83), respectively, which collectively discriminated 83.3% of all cases between critical-illness and non-critically illness.

CONCLUSIONS

The variations of whole blood metals/metalloids were associated with the critically-ill sepsis.

Effect of Sepsis on Iron Parameters in a Population with High Prevalence of Malnutrition and Iron Deficiency: A Cross-Sectional Case-Control Pilot Study

There is lack of data on iron metabolism in critically ill sepsis children from population with high prevalence of iron deficiency (ID). The study was designed to study impact of sepsis on iron parameters in children with ID. Sepsis patients (age 6-59 months) and their apparently healthy sibling/cousin as controls were enrolled in this case-control pilot study. Serum iron, TIBC, transferrin saturation, ferritin and sTfR were measured in the two groups. sTfR-Ferritin index was calculated. Patients (n = 134) were significantly underweight compared to controls (n = 54) (WAZ score < - 2; 58% vs. 28%; p < 0.001). Serum iron and sTfR (mg/L) were lower [71.5 (51.0, 115.0) vs. 87.0 (64.5, 130.5), p = 0.068; 3.1 (2.1, 4.5) vs. 3.5 (2.8, 4.8), p = 0.026 respectively] while serum ferritin was higher [229 (94, 484.5) vs. 22 (9.2, 51); p < 0.001] in patients compared to controls. sTfR-Ferritin index was lower in patients [1.3 (0.8, 2.3) vs. 2.5 (1.8, 4.5); p < 0.001]. ROC AUC (patients vs. controls) were 0.89 (95% CI 0.83-0.95) and 0.76 (95% CI 0.68-0.85) for ferritin and sTfR-ferritin index respectively. Survivors and non-survivors were similar in terms of iron parameters. Sepsis-induced alterations in iron parameters among ID children are complex. Qualitatively it is similar (with quantitative differences) to non-ID adult population. Lack of correlation of iron parameters with mortality may be due to ID-associated immune dysfunction.

Ultrastructural Changes of Blood Cells in Children with Generalized Purulent Peritonitis: A Cross-Sectional and Prospective Study

In conditions of abdominal sepsis with indications of first- or second-stage shock, blood cells undergo significant ultrastructural changes that cause impaired gas exchange, changes in reactivity, and decompensation of organs and systems functions. This paper presents a cross-sectional prospective study aimed at researching the ultrastructure of blood cells in children experiencing abdominal septic shock against the background of generalized purulent peritonitis of appendicular origin. This study was conducted with 15 children aged 6-12 who were undergoing treatment for generalized appendicular purulent peritonitis, with first- or second-stage abdominal septic shock, in emergency care. The changes in the ultrastructure of erythrocytes did not correspond to changes characteristic of eryptosis, which confirms their occurrence under the influence of such pathogenic factors as intoxication, metabolic, water-electrolyte balance, and acid-base disorders. Ultrastructural changes of granulocytes indicate their hyperactivation, which leads to the exhaustion of membrane synthetic resources, membrane destruction, ineffective expenditure of bactericidal factors on substrates that are not subject to destruction. In lymphocytes, disorganization of the nuclear membrane and intracellular membranes, uneven distribution of chromatin, the hypertrophied Golgi apparatus, and a large number of young mitochondria, lysosomes, ribosomes, vesicles manifesting the disruption of metabolism, stress and decompensation of energy supply and protein synthesis systems, have been demonstrated. In conditions of abdominal sepsis with indications of first- or second-stage shock, blood cells undergo substantial ultrastructural changes causing gas exchange disruption, changes in reactivity, as well as decompensation of organs and system functioning.

Anemia measurements to distinguish between viral and bacterial infections in the emergency department

The clinical diagnosis of acute infections in the emergency department is a challenging task due to the similarity in symptom presentation between virally and bacterially infected individuals, while the use of routine laboratory tests for pathogen identification is often time-consuming and may contain contaminants. We investigated the ability of various anemia-related parameters, including hemoglobin, red cell distribution width (RDW), and iron, to differentiate between viral and bacterial infection in a retrospective study of 3883 patients admitted to the emergency department with a confirmed viral (n = 1238) or bacterial (n = 2645) infection based on either laboratory tests or microbiological cultures. The ratio between hemoglobin to RDW was found to be significant in distinguishing between virally and bacterially infected patients and outperformed other anemia measurements. Moreover, the predictive value of the ratio was high even in patients presenting with low C-reactive protein values (< 21 mg/L). We followed the dynamics of hemoglobin, RDW, and the ratio between them up to 72 h post emergency department admission, and observed a consistent discrepancy between virally and bacterially infected patients over time. Additional analysis demonstrated higher levels of ferritin and lower levels of iron in bacterially infected compared with virally infected patients. The anemia measurements were associated with length of hospital stay, where all higher levels, except for RDW, corresponded to a shorter hospitalization period. We highlighted the importance of various anemia measurements as an additional host-biomarker to discern virally from bacterially infected patients.

The Effect of Sepsis on the Erythrocyte

Sepsis induces a wide range of effects on the red blood cell (RBC). Some of the effects including altered metabolism and decreased 2,3-bisphosphoglycerate are preventable with appropriate treatment, whereas others, including decreased erythrocyte deformability and redistribution of membrane phospholipids, appear to be permanent, and factors in RBC clearance. Here, we review the effects of sepsis on the erythrocyte, including changes in RBC volume, metabolism and hemoglobin's affinity for oxygen, morphology, RBC deformability (an early indicator of sepsis), antioxidant status, intracellular Ca²⁺ homeostasis, membrane proteins, membrane phospholipid redistribution, clearance and RBC O₂-dependent adenosine triphosphate efflux (an RBC hypoxia signaling mechanism involved in microvascular autoregulation). We also consider the causes of these effects by host mediated oxidant stress and bacterial virulence factors. Additionally, we consider the altered erythrocyte microenvironment due to sepsis induced microvascular dysregulation and speculate on the possible effects of RBC autoxidation. In future, a better understanding of the mechanisms involved in sepsis induced erythrocyte pathophysiology and clearance may guide improved sepsis treatments. Evidence that small molecule antioxidants protect the erythrocyte from loss of deformability, and more importantly improve septic patient outcome suggest further research in this area is warranted. While not generally considered a critical factor in sepsis, erythrocytes (and especially a smaller subpopulation) appear to be highly susceptible to sepsis induced injury, provide an early warning signal of sepsis and are a factor in the microvascular dysfunction that has been associated with organ dysfunction.

Sepsis and septic shock: Pathogenesis and treatment perspectives

The majority of bacteremias do not develop to sepsis: bacteria are cleared from the bloodstream. Oxygen released from erythrocytes and humoral immunity kill bacteria in the bloodstream. Sepsis develops if bacteria are resistant to oxidation and proliferate in erythrocytes. Bacteria provoke oxygen release from erythrocytes to arterial blood. Abundant release of oxygen to the plasma triggers a cascade of events that cause: 1. oxygen delivery failure to cells; 2. oxidation of plasma components that impairs humoral regulation and inactivates immune complexes; 3. disseminated intravascular coagulation and multiple organs' failure. Bacterial reservoir inside erythrocytes provides the long-term survival of bacteria and is the cause of ineffectiveness of antibiotics and host immune reactions. Treatment perspectives that include different aspects of sepsis development are discussed.

Progression from severe sepsis in pregnancy to death: a UK population-based case-control analysis

Objective

To identify factors associated with progression from pregnancy‐associated severe sepsis to death in the UK.

Design

A population‐based case‐control analysis using data from the UK Obstetric Surveillance System (UKOSS) and the UK Confidential Enquiry into Maternal Death (CEMD).

Setting

All pregnancy care and death settings in UK hospitals.

Population

All non‐influenza sepsis‐related maternal deaths (January 2009 to December 2012) were included as cases (n = 43), and all women who survived severe non‐influenza sepsis in pregnancy (June 2011 to May 2012) were included as controls (n = 358).

Methods

Cases and controls were identified using the CEMD and UKOSS. Multivariable logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals.

Main outcome measures

Odds ratios for socio‐demographic, medical, obstetric and management factors in women who died from sepsis, compared with those who survived.

Results

Four factors were included in the final regression model. Women who died were more likely to have never received antibiotics [aOR = 22.7, 95% confidence interval (CI) 3.64–141.6], to have medical comorbidities (aOR = 2.53, 95%CI 1.23–5.23) and to be multiparous (aOR = 3.57, 95%CI 1.62–7.89). Anaemia (aOR = 13.5, 95%CI 3.17–57.6) and immunosuppression (aOR = 15.0, 95%CI 1.93–116.9) were the two most important factors driving the association between medical comorbidities and progression to death.

Conclusions

There must be continued vigilance for the risks of infection in pregnant women with medical comorbidities. Improved adherence to national guidelines, alongside prompt recognition and treatment with antibiotics, may reduce the burden from sepsis‐related maternal deaths.

Tweetable abstract

Medical comorbidities, multiparity and antibiotic delays increase the risk of death from maternal sepsis.

Which carries the biggest risk: Anaemia or blood transfusion?

It is well recognized that anaemia, a frequent complication of critical illness, is associated with poor outcomes, perhaps particularly in patients with ischaemic heart disease. But studies have also reported increased morbidity and mortality in patients who receive blood transfusions. So which carries the biggest risk, when should we transfuse and when should we hold off? Should we have fixed transfusion triggers and if so in all patients, or different triggers for different groups of patients? Indeed, these are more complex decisions than initially apparent. ICU patients are very heterogeneous and will react differently to the same intervention. As such, decisions to transfuse or not must be individualized, taking into account specific patient factors, such as age and comorbidities, physiologic variables, as well as the haemoglobin value. This approach will ensure that anaemia is treated when necessary while avoiding unnecessary exposure to red blood cells.

Mechanisms of cytolysin-induced cell damage -- a role for auto- and paracrine signalling

Cytolysins inflict cell damage by forming pores in the plasma membrane. The Na(+) conductivity of these pores results in an ion influx that exceeds the capacity of the Na(+) /K(+) -pump to extrude Na(+) . This net load of intracellular osmolytes results in swelling and eventual lysis of the attacked cell. Many nucleated cells have the capacity to reduce the potential damage of pore-forming proteins, whereas erythrocytes have been regarded as essentially defenceless against cytolysin-induced cell damage. This review addresses how autocrine/paracrine signalling and the cells intrinsic volume regulation markedly influence the fate of the cell after membrane insertion of cytolysins. Moreover, it regards the various steps that may explain the relative large degree of diversity between cell types and species as well as highlights some of the current gaps in the mechanistic understanding of cytolysin-induced cell injury.

Escherichia coli alpha-hemolysin triggers shrinkage of erythrocytes via K(Ca)3.1 and TMEM16A channels with subsequent phosphatidylserine exposure

alpha-Hemolysin from Escherichia coli (HlyA) readily lyse erythrocytes from various species. We have recently demonstrated that this pore-forming toxin provokes distinct shrinkage and crenation before it finally leads to swelling and lysis of erythrocytes. The present study documents the underlying mechanism for this severe volume reduction. We show that HlyA-induced shrinkage and crenation of human erythrocytes occur subsequent to a significant rise in [Ca(2+)](i). The Ca(2+)-activated K(+) channel K(Ca)3.1 (or Gardos channel) is essential for the initial shrinkage, because both clotrimazole and TRAM-34 prevent the shrinkage and potentiate hemolysis produced by HlyA. Notably, the recently described Ca(2+)-activated Cl(-) channel TMEM16A contributes substantially to HlyA-induced cell volume reduction. Erythrocytes isolated from TMEM16A(-/-) mice showed significantly attenuated crenation and increased lysis compared with controls. Additionally, we found that HlyA leads to acute exposure of phosphatidylserine in the outer leaflet of the plasma membrane. This exposure was considerably reduced by K(Ca)3.1 antagonists. In conclusion, this study shows that HlyA triggers acute erythrocyte shrinkage, which depends on Ca(2+)-activated efflux of K(+) via K(Ca)3.1 and Cl(-) via TMEM16A, with subsequent phosphatidylserine exposure. This mechanism might potentially allow HlyA-damaged erythrocytes to be removed from the bloodstream by macrophages and thereby reduce the risk of intravascular hemolysis.