IL-18 Level Correlates with Development of Sepsis in Surgical Patients

Hyper-inflammatory profile and immunoparalysis in patients with severe Legionnaires' disease

Introduction

Severe Legionnaires' disease (LD) can lead to multi-organ failure or death in 10%-30% of patients. Although hyper-inflammation and immunoparalysis are well described in sepsis and are associated with high disease severity, little is known about the immune response in LD. This study aimed to evaluate the immune status of patients with LD and its association with disease severity.

Methods

A total of 92 hospitalized LD patients were included; 19 plasmatic cytokines and pulmonary Legionella DNA load were measured in 84 patients on the day of inclusion (day 0, D0). Immune functional assays (IFAs) were performed from whole blood samples collected at D2 and stimulated with concanavalin A [conA, n = 19 patients and n = 21 healthy volunteers (HV)] or lipopolysaccharide (LPS, n = 14 patients and n = 9 HV). A total of 19 cytokines (conA stimulation) and TNF-α (LPS stimulation) were quantified from the supernatants. The Sequential Organ Failure Assessment (SOFA) severity score was recorded at D0 and the mechanical ventilation (MV) status was recorded at D0 and D8.

Results

Among the 84 patients, a higher secretion of plasmatic MCP-1, MIP1-β, IL-6, IL-8, IFN-γ, TNF-α, and IL-17 was observed in the patients with D0 and D8 MV. Multiparametric analysis showed that these seven cytokines were positively associated with the SOFA score. Upon conA stimulation, LD patients had a lower secretion capacity for 16 of the 19 quantified cytokines and a higher release of IL-18 and MCP-1 compared to HV. IL-18 secretion was higher in D0 and D8 MV patients. TNF-α secretion, measured after ex vivo LPS stimulation, was significantly reduced in LD patients and was associated with D8 MV status.

Discussion

The present findings describe a hyper-inflammatory phase at the initial phase of Legionella pneumonia that is more pronounced in patients with severe LD. These patients also present an immunoparalysis for a large number of cytokines, except IL-18 whose secretion is increased. An assessment of the immune response may be relevant to identify patients eligible for future innovative host-directed therapies.

Clinical Value of Serum Interleukin-18 in Neonatal Sepsis Diagnosis and Mortality Prediction

Purpose

Previous studies have demonstrated that interleukin-18 (IL-18) levels were elevated in adult patients with sepsis. However, its role in neonatal sepsis remains unknown. The current research was conducted to assess the clinical value of serum IL-18 level as a candidate biomarker in neonatal sepsis diagnosis and prediction of mortality.

Patients and Methods

From July 2022 to September 2022, we prospectively enrolled 91 septic neonates and 31 non-sepsis neonates in the intensive care unit of neonates at Henan Children's Hospital in Zhengzhou, China. Neonatal peripheral blood serum was collected at admission and levels of serum IL-18 were assessed. Employing multivariate logistic regression analysis, the evaluation of the potential of IL-18 as an independent biomarker for sepsis was executed. Furthermore, employing the receiver operating characteristic (ROC) curve analysis, the diagnostic value of IL-18 in sepsis and the ability of IL-18 in predicting the mortality of neonatal sepsis was measured. The statistical package SPSS 24.0 was employed to conduct all statistical analyses.

Results

Serum IL-18 levels in neonates in the sepsis group were elevated compared to the control group, reaching the highest levels in the non-survival sepsis group (P < 0.001). Correlation analysis exhibited a positive relationship between IL-18 levels and age, body temperature, respiratory rate, and C-reactive protein levels. IL-18 was identified as an independent biomarker in identifying sepsis (OR = 4.747, 95% CI 1.493-15.092, P = 0.008) by multiple logistic regression. ROC curve analysis exhibited that IL-18 was good in identifying neonatal sepsis (area under curve (AUC) = 0.77, 95% CI = 0.68-0.85, P < 0.001) and predicting neonatal mortality (AUC = 0.80, 95% CI = 0.63-0.96, P = 0.003).

Conclusion

IL-18 was a potential biomarker for identifying neonatal sepsis and neonatal mortality prediction.

The Relationship between Extracellular/intracellular microRNAs and TLRs May Be Used as a Diagnostic and Therapeutic Approach in Sepsis

One of the leading causes of death in the intensive care unit (ICU) is sepsis. Different studies have been performed on different markers to determine the cause of sepsis. microRNAs (miRNAs) are non-coding RNAs that can be released both inside and outside the cell and regulate the target gene expression by binding to the 3' untranslated region (3'UTR) of the target genes. TLRs play an important role in innate immunity that can be modulated by biological markers such as microRNAs. In this study, we summarized the recent progress on the role of extracellular and intracellular microRNAs in sepsis. It has also been focused on the association of TLRs with extracellular and intracellular micro RNAs in the regulation of sepsis. In conclusion, this study has provided new insight into the role of microRNAs as a regulator of the TLRs which may lead to the aberrant inflammatory response in sepsis. Therefore, it suggests that both intracellular and extracellular microRNAs may play a therapeutic role in the treatment of sepsis via regulating TLRs. However, yet sepsis and septic shock are medical emergencies and further studies are needed to specify the exact role of microRNAs and TLRs in sepsis.

Recent advances in the biology of IL-1 family cytokines and their potential roles in development of sepsis

The IL-1 family comprises two anti-inflammatory cytokines (IL-37, IL-38), two receptor antagonists (IL-1ra, IL-36ra), and seven ligand agonists (IL-1α, IL-1β, IL-33, IL-36α, IL-36β, IL-36γ). The members of this family exert pleiotropic effects on intercellular signaling, leading to pro- or anti-inflammatory responses. They initiate potent inflammatory and immune responses by binding to specific receptors in the IL-1 receptor family, and their activities are repressed by naturally occurring inhibitors. Various immune cells produce and are regulated by these crucial molecules, which appear to be involved in the pathogenesis of diverse diseases including cancer as well as inflammatory and autoimmune disorders. Recent decades have seen substantial progress in understanding how the IL-1 family contributes to the development of sepsis. In this review, we will briefly introduce the IL-1 family and discuss its critical role in inflammatory and immune responses. The potential significance of IL-1 members in sepsis will also be explored, together with the clinical implications for treating this dangerous condition.

Interleukin-18 Reduces Blood Glucose and Modulates Plasma Corticosterone in a Septic Mouse Model

BACKGROUND

Dysregulation of glucose metabolism, including hyperglycemia with insulin resistance, is commonly observed in critically ill patients. Interleukin-18 (IL-18) improves the insulin resistance associated with obesity, but the relationship between IL-18 and glucose metabolism in sepsis was unclear. The purpose of this study was to investigate the influence of IL-18 on hyperglycemia during sepsis.

METHODS

Sepsis was induced using cecal ligation and puncture (CLP) in wild-type (WT) mice, IL-18 knockout (KO) mice, and IL-18 KO mice pretreated with recombinant IL-18. Blood glucose and plasma insulin, glucagon, and corticosterone were measured. The mRNAs for gluconeogenic enzymes (g6pc, pck1) and activation of insulin signaling were also analyzed.

RESULTS

In both WT and IL-18 KO mice, CLP operation led to hyperglycemia that lasted longer (18 h) than after sham operation (6 h). Blood glucose levels in IL-18 KO mice were significantly higher than in WT mice, without alteration of insulin or glucagon levels. In IL-18 KO mice, insulin signaling in the liver and skeletal muscle was decreased during hyperglycemia as compared with WT mice without suppression of hepatic glucose production enzymes. Pretreatment with recombinant IL-18 reduced blood glucose levels after CLP. Additionally, corticosterone levels were higher after CLP in the presence of either endogenous or exogenous IL-18.

CONCLUSION

IL-18 may reduce blood glucose by modulating insulin signaling in the liver during sepsis-induced hyperglycemia. IL-18 is an important factor associated with alterations in blood glucose during sepsis.

Detection of Serum Interleukin-6/10/18 Levels in Sepsis and Its Clinical Significance

OBJECTIVE

To explore the clinical significance of serum levels of IL-6/10/18 in sepsis.

METHODS

Sixty-six patients with sepsis were selected to be the case group. Additionally, 42 healthy adults were selected to be the control group. ELISA was used to measure the serum levels of IL-6/10/18, and ROC was utilized to evaluate the diagnostic values of IL-6/10/18 in sepsis.

RESULTS

The heart rate, respiratory rate, WBC count and APACHE II score in the sepsis group were significantly higher than those in the control group, and these indexes were increased in turn in the mild sepsis group, severe sepsis group, and septic shock group (all P < 0.05 after correction). The serum IL-6/18 levels in sepsis patients were significantly higher than those in the control group, and both of the levels were increased in turn in the mild sepsis group, severe sepsis group, and septic shock group (both P < 0.05). However, no significant difference was found in serum IL-10 level between groups (P > 0.05). The cut-off points of IL-6 and IL-18 were 109.19 pg/ml (sensitivity: 94.4%; specificity: 83.3%) and 116.01 pg/ml (sensitivity: 77.8%; specificity: 83.3%), respectively. Serum IL-6 levels were positively correlated with the APACHE II score and heart rate (both P < 0.001).

CONCLUSION

Serum levels of IL-6/8 are up-regulated in sepsis patients. Additionally, IL-6 has a greater sensitivity than IL-18. Serum IL-6 levels were positively correlated with the APACHE II score and heart rate, indicating that IL-6 could be used as a potential biomarker for sepsis.

Host response biomarkers in the diagnosis of sepsis: a general overview

Critically ill patients who display a systemic inflammatory response syndrome (SIRS) are prone to develop nosocomial infections. The challenge remains to distinguish as early as possible among SIRS patients those who are developing sepsis. Following a sterile insult, damage-associated molecular patterns (DAMPs) released by damaged tissues and necrotic cells initiate an inflammatory response close to that observed during sepsis. During sepsis, pathogen-associated molecular patterns (PAMPs) trigger the release of host mediators involved in innate immunity and inflammation through identical receptors as DAMPs. In both clinical settings, a compensatory anti-inflammatory response syndrome (CARS) is concomitantly initiated. The exacerbated production of pro- or anti-inflammatory mediators allows their detection in biological fluids and particularly within the bloodstream. Some of these mediators can be used as biomarkers to decipher among the patients those who developed sepsis, and eventually they can be used as prognosis markers. In addition to plasma biomarkers, the analysis of some surface markers on circulating leukocytes or the study of mRNA and miRNA can be helpful. While there is no magic marker, a combination of few biomarkers might offer a high accuracy for diagnosis.

Endogenous interleukin 18 suppresses hyperglycemia and hyperinsulinemia during the acute phase of endotoxemia in mice

BACKGROUND

Hyperglycemia associated with insulin resistance is common among critically ill patients. Interleukin (IL)-18 has been linked with hyperglycemia and insulin resistance in chronic disease, but the relation between IL-18 and insulin resistance during critical illness was unexplored. This study investigated whether IL-18 modulates hyperglycemia and insulin resistance during acute inflammation.

METHODS

We injected lipopolysaccharide (LPS) 40 mg/kg into wild-type (WT) and IL-18 knockout (KO) mice to induce endotoxemia and examined insulin resistance and insulin-dependent signaling pathways during the acute phase.

RESULTS

During the first hour after LPS treatment, IL-18 KO mice showed higher blood glucose and insulin and less insulin receptor substrate-1 and less phosphorylated Akt in the liver compared with WT mice. Interleukin-18 KO mice exhibited better survival after LPS treatment.

CONCLUSIONS

The findings suggest that endogenous IL-18 may attenuate hyperglycemia and modulate insulin signaling in liver. Accordingly, IL-18 may modulate glucose tolerance during acute inflammation.

Interleukin 18: a biomarker for differential diagnosis between adult-onset Still's disease and sepsis

OBJECTIVE

The differential diagnosis between rheumatic diseases and infectious conditions is a great challenge in clinical practice. Adult-onset Still's disease (AOSD) is a rare systemic inflammatory syndrome that shares several clinical and laboratory variables with sepsis. Interleukin (IL)-18 is overexpressed in AOSD, suggesting a possible role as a disease biomarker. The aim of our study was to detect IL-18 serum levels in a cohort of patients with AOSD and sepsis and to address its possible role as a biomarker for differential diagnosis.

METHODS

A group of unselected patients with AOSD diagnosed according to the Yamaguchi criteria and consecutive patients with sepsis diagnosed according to the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference criteria were enrolled. The clinical and laboratory data were collected. In the AOSD group, disease activity was assessed by Pouchot's and Rau's criteria. IL-18 serum levels were detected by ELISA.

RESULTS

Thirty-nine patients with AOSD and 18 patients with sepsis were enrolled. Two out of 18 patients with sepsis (11.1%) also fulfilled the Yamaguchi criteria. A significant difference was found in IL-18 serum levels between patients with active and inactive disease (p < 0.001), and it positively correlated with disease activity (p = 0.0003), ferritin serum level (p = 0.016), and erythrocyte sedimentation rate (p = 0.041). IL-18 was significantly increased in patients with AOSD when compared with sepsis (p = 0.014). For a cutoff of 148.9 pg/ml, this test had a specificity of 78.3% and a sensitivity of 88.6%.

CONCLUSION

We have demonstrated that IL-18 can be a biomarker for differential diagnosis between AOSD and sepsis.

MicroRNA fingerprints identify miR-150 as a plasma prognostic marker in patients with sepsis

BACKGROUND

The physiopathology of sepsis continues to be poorly understood, and despite recent advances in its management, sepsis is still a life-threatening condition with a poor outcome. If new diagnostic markers related to sepsis pathogenesis will be identified, new specific therapies might be developed and mortality reduced. Small regulatory non-coding RNAs, microRNAs (miRNAs), were recently linked to various diseases; the aim of our prospective study was to identify miRNAs that can differentiate patients with early-stage sepsis from healthy controls and to determine if miRNA levels correlate with the severity assessed by the Sequential Organ Failure Assessment (SOFA) score.

METHODOLOGY/PRINCIPAL FINDINGS

By using genome-wide miRNA profiling by microarray in peripheral blood leukocytes, we found that miR-150, miR-182, miR-342-5p, and miR-486 expression profiles differentiated sepsis patients from healthy controls. We also proved by quantitative reverse transcription-polymerase chain reaction that miR-150 levels were significantly reduced in plasma samples of sepsis patients and correlated with the level of disease severity measured by the SOFA score, but were independent of the white blood counts (WBC). We found that plasma levels of tumor necrosis factor alpha, interleukin-10, and interleukin-18, all genes with sequence complementarity to miR-150, were negatively correlated with the plasma levels of this miRNA. Furthermore, we identified that the plasma levels ratio for miR-150/interleukin-18 can be used for assessing the severity of the sepsis.

CONCLUSIONS/SIGNIFICANCE

We propose that miR-150 levels in both leukocytes and plasma correlate with the aggressiveness of sepsis and can be used as a marker of early sepsis. Furthermore, we envision miR-150 restoration as a future therapeutic option in sepsis patients.

Interleukin 8 is a surrogate marker for rapid diagnosis of bacteriuria

Urinary tract infection (UTI) is one of the most common sources of infection in children under 5. Rapid diagnosis is a need to avoid complications of UTI. The goal of the present study was to evaluate the use of urinary interleukin 8 (IL8) as a rapid laboratory method for diagnosis of UTI. A total of 116 children were included in the study. They were complaining of different diseases with pyuria. In addition twenty healthy children were included as control subjects. Urine samples were subjected to full chemical, cytological and bacteriological examinations. In addition, urinary IL8 was measured. Patients showed significantly elevated urine IL-8 levels (80-820 pg/ml) compared to control subjects (6-10 pg/ml) (p < 0.0001). There was significant correlation between interleukin 8 level and white blood cells counts in urine (p = 0.039). The mean +/- SD of urinary IL-8 was significantly increased 165.8 +/- 115.1 in urine with bacterial growth (Staphylococcus species and Escherichia coli) p < 0.001 than in urine without growth. Urine with Escherichia coli (E. coli) growth had significantly higher IL 8 level than growth with other types of organisms. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value had higher level for IL8 compared to other parameters in urine examination i.e., nitrite, WBCs and RBCs (85.7%, 60%, 64%, 87%, 64% respectively). This study highlights that bacteriuria is associated with higher level of urinary interleukin 8 than pyuria without bacteriuria. Thus from this study we can conclude that IL8 can be used as rapid surrogate marker for rapid laboratory diagnosis of urosepsis.