The immune response: targets for the treatment of severe sepsis

Promoting effect of Tmsb4x on the differentiation of peripheral blood mononuclear cells to dendritic cells during septicemia

BACKGROUND

Thymosin beta 4 × (Tmsb4x) has been highlighted as an important regulator in immune and inflammation responses. Promoted differentiation of mononuclear cells into dendritic cells (DCs) exert a beneficial effect on septicemia. Herein, we investigated the effects of Tmsb4x on the mononuclear cells to affect immune responses during septicemia.

METHODS

Initially, we isolated peripheral blood samples from healthy individuals and patients with septicemia for extraction of mononuclear cells, followed by Tmsb4x expression quantification. A cell model was constructed with mononuclear cells through lipopolysaccharide stimulation. The viability and apoptosis were evaluated in response to Tmsb4x silencing or re-expression. Additionally, the proportion of DCs was assessed by determining levels of inflammatory factors as well as by flow cytometric analysis. A mouse septicemia model was developed for in vivo validation.

RESULTS

Cell and animal models demonstrated decreased Tmsb4x expression in the setting of septicemia, which led to increased inflammatory response and reduced proportion of DCs, along with inhibited mononuclear cell viability and promoted apoptosis. However, restoration of Tmsb4x facilitated the differentiation of mononuclear cells into DCs.

CONCLUSION

To conclude, upregulated Tmsb4x promoted the generation of DCs from mononuclear cells, which contributed to deep understanding of underpinning mechanisms in the development of septicemia.

Gene Expression Profiles in Children With Suspected Sepsis

STUDY OBJECTIVE

Sepsis recognition is a clinical challenge in children. We aim to determine whether peripheral blood gene expression profiles are associated with pathogen type and sepsis severity in children with suspected sepsis.

METHODS

This was a prospective pilot observational study in a tertiary pediatric emergency department with a convenience sample of children enrolled. Participants were older than 56 days and younger than 18 years, had suspected sepsis, and had not received broad-spectrum antibiotics in the previous 4 hours. Primary outcome was source pathogen, defined as confirmed bacterial source from sterile body fluid or confirmed viral source. Secondary outcome was sepsis severity, defined as maximum therapy required for shock reversal in the first 3 hospital days. We drew peripheral blood for ribonucleic acid isolation at the sepsis protocol activation, obtained gene expression measures with the GeneChip Human Gene 2.0 ST Array, and conducted differential expression analysis.

RESULTS

We collected ribonucleic acid samples from a convenience sample of 122 children with suspected sepsis and 12 healthy controls. We compared the 66 children (54%) with confirmed bacterial or viral infection and found 558 differentially expressed genes, many related to interferon signaling or viral immunity. We did not find statistically significant gene expression differences in patients according to sepsis severity.

CONCLUSION

The study demonstrates feasibility of evaluating gene expression profiling data in children evaluated for sepsis in the pediatric emergency department setting. Our results suggest that gene expression profiling may facilitate identification of source pathogen in children with suspected sepsis, which could ultimately lead to improved tailoring of sepsis treatment and antimicrobial stewardship.

Brain Death-Induced Inflammatory Activity is Similar to Sepsis-Induced Cytokine Release

Brain death (BD) is associated with a systemic inflammation leading to worse graft outcomes. This study aimed to compare plasma cytokine values between brain-dead and critically ill patients, including septic and non-septic controls, and evaluate cytokine release kinetics in BD. Sixteen brain-dead and 32 control patients (16 with and 16 without sepsis) were included. Plasma cytokines were measured by magnetic bead assay after the first clinical exam consistent with BD and every 6 hours thereafter, and at the time of study entry in the control group. The values for IL-8 and IFN-γ were higher in brain-dead and septic patients than in non-septic patients [IL-8: 80.3 (18.7–169.6) vs. 68.2 (22.4–359.4) vs. 16.4 (9.2–42.7) pg/mL; P = 0.006; IFN-γ: 2.8 (1.6-6.1) vs. 3.4 (1.2–9.0) vs. 0.5 (0.5–1.8) pg/mL; P = 0.012]. TNF showed a clear tendency to increase in brain-dead patients [2.7 (1.0–4.8) vs. 1.0 (1.0–5.6) vs. 1.0 (1.0–1.0) pg/mL; P = 0.051], and IL-6 values were higher in brain-dead patients than in non-septic controls [174.5 (104.9–692.5) vs. 13.2 (7.3–38.6) pg/mL; P = 0.002]. These differences remained even after excluding brain-dead patients who also had sepsis (n = 3). IL-1β and IL-10 values increased from baseline to time point 2 (∼6 hours later) [IL-1β: 5.39 (1.93–16.89) vs. 7.11 (1.93–29.13) pg/mL; P = 0.012; IL-10: 8.78 (3.62–16.49) vs. 15.73 (5.49–23.98) pg/mL; P = 0.009]. BD-induced and sepsis-induced plasma cytokine values were similarly high, and both were higher than the observed in non-septic critically ill patients.

The Emperor Has No Clothes? Searching for Dysregulation in Sepsis

The core conception of sepsis—that it is a dysregulated state—is a powerful and durable idea that has inspired decades of research. But is it true that the body’s response to sepsis is dysregulated? To answer that question, this review surveyed the history of trials of experimental sepsis treatments targeting the host response. Sepsis survival is not improved by blocking one or many immune pathways. Similarly, sepsis is resistant to treatment by normalizing one or many physiologic parameters simultaneously. The vast majority of interventions are either ineffective or harmful. With this track record of failure, it is time to consider the alternative hypothesis—regulation instead of dysregulation—and the possibility that sepsis traits are often functional, and that some physiologic alterations in sepsis do more good than harm, while others are neutral. This review discusses the implications of this perspective for the future of sepsis research.

Septicemia is associated with increased risk for dementia: a population-based longitudinal study

Background

Systemic infection has been linked to cognitive impairment. We hypothesized that patients with septicemia are predisposed to increased risks for developing dementia in a long-term setting.

Methods

This observational, retrospective, longitudinal, nation-wide population-based study was conducted using the data deduced from Longitudinal Health Insurance Database (LHID) in Taiwan. All patients with septicemia hospitalized for the first time from 2001 to 2011 without prior dementia were included. The development of Alzheimer's disease (AD) or non-Alzheimer dementias (NAD) in relation to the development of septicemia for each patient was recorded. An age- and sex-matched cohort without septicemia and without prior dementia served as the control. Septicemia, dementia, and other confounding factors were defined according to International Classification of Diseases Clinical Modification Codes. Cox proportional-hazards regressions were utilized to analyze adjusted hazard ratios.

Results

Patients with septicemia had a higher risk for developing dementia based on hazard ratios (HRs) (p<0.001). Patients with septicemia in the younger age groups had a greater dementia risk (p<0.01). Septicemia was associated with subsequent NAD (p<0.001), whereas the increased risk of AD was statistically insignificant (p>0.05). Furthermore, higher severity of septicemia was associated with increased risk of developing dementia.

Conclusions

Our findings suggest that septicemia is associated with an increased risk in developing NAD but not AD. A likely causal role of septicemia in increasing the risk of NAD is suggested, according to the findings that patients with higher severity of septicemia carried greater risk of sustaining dementia.

Anti-Inflammatory Activity of the Essential Oil Citral in Experimental Infection with Staphylococcus aureus in a Model Air Pouch

This study proposes to implement an alternative and effective strategy for local treatment of disease provoked by S. aureus. For the analysis of possible anti-inflammatory activity of essential oil, after establishing an air pouch model, 48 male mice of Balb/c were treated, infected, and euthanized at 4 and 8 h. Thus, the total and differential white blood cells were counted in the animal's blood, and cytokines IL-1β, IL-6, and TNF-α were titrated using ELISA in the air pouch lavage. Moreover, TNF-α, IL-1β, and IL-6 gene expression was analyzed through an RT-qPCR array, and S. aureus was quantified using qPCR. Our results, p < 0.05, showed that EOC reduced the quantity of microorganisms. The group of mice treated with essential oil citral showed a significant decrease in TNF-α levels in tests demonstrating anti-inflammatory activity. There is no data about the mutual influence of the air pouch model, essential oil citral, and S. aureus. Thus, considering the interaction of these variables and the anti-inflammatory activity of the essential oil citral, we demonstrated, by alternative local treatment, a new antimicrobial agent that is not an antibiotic.

Role of cellular events in the pathophysiology of sepsis

INTRODUCTION

Sepsis is a dysregulated host immune response due to an uncontrolled infection. It is a leading cause of mortality in adult intensive care units globally. When the host immune response induced against a local infection fails to contain it locally, it progresses to sepsis, severe sepsis, septic shock and death.

METHOD

Literature survey was performed on the roles of different innate and adaptive immune cells in the development and progression of sepsis. Additionally, the effects of septic changes on reprogramming of different immune cells were also summarized to prepare the manuscript.

FINDINGS

Scientific evidences to date suggest that the loss of balance between inflammatory and anti-inflammatory responses results in reprogramming of immune cell activities that lead to irreversible tissue damaging events and multi-organ failure during sepsis. Many surface receptors expressed on immune cells at various stages of sepsis have been suggested as biomarkers for sepsis diagnosis. Various immunomodulatory therapeutics, which could improve the functions of immune cells during sepsis, were shown to restore immunological homeostasis and improve survival in animal models of sepsis.

CONCLUSION

In-depth and comprehensive knowledge on the immune cell activities and their correlation with severity of sepsis will help clinicians and scientists to design effective immunomodulatory therapeutics for treating sepsis.

Targeting cytokines as a treatment for patients with sepsis: A lost cause or a strategy still worthy of pursuit?

Despite often knowing the aetiology of sepsis and its clinical course there has not been the anticipated advances in treatment strategies. Cytokines are influential mediators of immune/inflammatory reactions and in patients with sepsis high circulating levels are implicated in the onset and perpetuation of organ failure. Antagonising the activities of pro-inflammatory cytokines enhances survival in animal models of sepsis but, so far, such a therapeutic strategy has not improved patient outcome. This article addresses the questions of why encouraging laboratory findings have failed to be translated into successful treatments of critically ill patients and whether modifying cytokine activity still remains a promising avenue for therapeutic advance in severe sepsis. In pursuing this task we have selected reports that we believe provide an incisive, critical and balanced view of the topic.

Increased risk of stroke after septicaemia: a population-based longitudinal study in Taiwan

Inflammation and infection have been noted to increase stroke risk. However, the association between septicaemia and increased risk of stroke remains unclear. This population-based cohort study, using a National Health Insurance database, aimed to investigate whether patients with septicaemia are predisposed to increased stroke risk. The study included all patients hospitalised for septicaemia for the first time between 2000 and 2003 without prior stroke. Patients were followed until the end of 2010 to evaluate incidence of stroke. An age-, gender- and co-morbidities-matched cohort without prior stroke served as the control. Cox's proportional hazards regressions were used to assess differences in stroke risk between groups. Based on hazard ratios (HRs), patients with septicaemia had greater stroke risk, especially in the younger age groups (age <45: HR = 4.16, 95% CI: 2.39-7.24, p<0.001; age 45-64: HR = 1.76, 95% CI: 1.41-2.19, p<0.001; age ≥ 65: HR = 1.05, 95% CI: 0.91-1.22, p>0.05). Haemorrhagic stroke was the dominant type (ischaemic stroke: HR = 1.20, 95% CI: 1.06-1.37, p<0.01; haemorrhagic stroke: HR = 1.82, 95% CI: 1.35-2.46, p<0.001) and patients without co-morbidities were at slightly higher risk (without co-morbidities: HR = 1.49, 95% CI: 1.02-2.17, p<0.05; with co-morbidities: HR = 1.24, 95% CI: 1.10-1.41, p<0.001). The impact of septicaemia on stroke risk was highest within 6 months of the event and gradually declined over time. Our results suggest that septicaemia is associated with an increase in stroke risk, which is greatest in haemorrhagic stroke. Closer attention to patients with history of septicaemia may be warranted for stroke preventive measures, especially for younger patients without co-morbidities.

How to die chemically? Whole body apoptosis

What would you do if your body decided to die when you were not ready? It appears that some biological program can shut down all bodily functions, in much the same way as apoptosis does so at the cellular level. Pacific salmon and annual cicada die after reproduction. How do they die chemically? Their programmed death after reproduction should have chemical signals. Similarly, pro-inflammatory cytokines, particularly tumor necrosis factor-α and interleukin-1β, could induce death in mammals. Acute massive production of them in sepsis and chronic tiny production in aging could lead to death. Thus, the mechanism of the whole body suicide program could be determined and some people could be rescued from this type of death by elucidating the death program. I propose that the concept of whole body apoptosis, defined as programmed whole body death, be adopted by scientific community.