Interleukin-17 as a predictor of sepsis in polytrauma patients: a prospective cohort study

A bidirectional mendelian-randomization analyses of genetically predicted circulating levels of systemic inflammatory regulators with risk of sepsis

Whether there is a causal relationship between circulating levels of systemic inflammatory regulators and sepsis remains unclear. To determine whether genetically predicted circulating levels of cytokines are associated with risk of sepsis, a bidirectional two-sample Mendelian randomization (MR) analysis based on the a STROBE-compliant cross-sectional observational study was conducted utilizing gene-wide association study (GWAS) data. Selected with rigor, single-nucleotide polymorphisms served as instrumental variables for subsequent MR analysis. The preferred method for the MR analysis was the inverse-variance weighted approach. However, for comprehensive sensitivity analyses, 6 additional MR methods were employed. Cochrane's Q test was performed to examine heterogeneity. A leave-one-out method ensured the stability of MR results. Our findings suggest an inverse association between the levels of beta-nerve growth factor (BNGF) and the risk of sepsis development (OR = 0.769, 95% CI = 0.599-0.987, P = .039). In contrast, higher levels of TNF-related apoptosis-inducing ligand and vascular endothelial growth factor A (VEGF-A) are positively correlated with sepsis risk (OR = 1.094, 95% CI = 1.012-1.183, P = .025; OR = 1.182, 95% CI = 1.016-1.375, P = .031, respectively). Reverse MR Analysis indicated that sepsis risk is linked with lower circulating levels of adenosine deaminase and Interleukin-17A (β = -0.043, 95% CI = -0.085 to -0.002, P = .042; β = -0.061, 95% CI = -0.108 to -0.013, P = .012, respectively), and also with higher circulating levels of BNGF, delta/notchlike epidermal growth factor-related receptor, fibroblast growth factor 23, leukemia inhibitory factor, monocyte chemoattractant protein-1, and osteoprotegerin (β = 0.056, 95% CI = 0.015-0.096, P = .007; β = 0.137, 95% CI = 0.035-0.240, P = .009; β = 0.118, 95% CI = 0.020-0.216, P = .018; β = 0.136, 95% CI = 0.020-0.252, P = .022; β = 0.143, 95% CI = 0.043-0.242, P = .005; β = 0.116, 95% CI = 0.010-0.222, P = .031, respectively). Sum up, our study provides evidence supporting a bidirectional causal relationship between sepsis and genetically predicted circulating levels of systemic inflammatory regulators.

The Impact of Steatotic Liver Disease on Cytokine and Chemokine Kinetics During Sepsis

Metabolic dysfunction-associated steatotic liver disease (MASLD) has recently been linked with sepsis outcomes. However, the immune mechanisms by which MASLD aggravates sepsis severity are unknown. This prospective cohort study aimed to analyze serum cytokine and chemokine kinetics in patients with MASLD and community-acquired sepsis. Out of the 124 patients, 68 (55%) were diagnosed with MASLD. There were no differences in age, sex, comorbidities, baseline sepsis severity, or etiology between the groups. Serum concentrations of 27 cytokines and chemokines on admission and day 5 of hospitalization were analyzed using a multiplex bead-based assay. Patients with MASLD had significantly higher serum concentrations of IL17A, IL-23, IL-33, CXCL10 and TGF-β1. Different cytokine kinetics were observed; patients with MASLD had a decrease in IL-10, IL-23, CXCL10 and TGF-β1, and an increase in IL-33, CXCL5 and CXCL1 on day 5. In the non-MASLD group, there was a decrease in IFN-γ, IL-6, IL-23 and CCL20, and an increase in CCL11 and CXCL5. While TGF-β1 significantly increased in non-MASLD, in MASLD, it decreased on day 5. Kinetics of TGF- β1 and CCL11 were associated with mortality in patients with MASLD. In conclusion, MASLD is linked with distinct cytokine and chemokine profiles during sepsis.

TLR4/TNFR1 blockade suppresses STAT1/STAT3 expression and increases SOCS3 expression in modulation of LPS-induced macrophage responses

Due to the urgent need to create appropriate treatment techniques, which are currently unavailable, LPS-induced sepsis has become a serious concern on a global scale. The primary active component in the pathophysiology of inflammatory diseases such as sepsis is the Gram-negative bacterial lipopolysaccharide (LPS). LPS interacts with cell surface TLR4 in macrophages, causing the formation of reactive oxygen species (ROS), TNF-α, IL-1β and oxidative stress. It also significantly activates the MAPKs and NF-κB pathway. Excessive production of pro-inflammatory cytokines is one of the primary characteristic features in the onset and progression of inflammation. Cytokines mainly signal through the JAK/STAT pathway. We hypothesize that blocking of TLR4 along with TNFR1 might be beneficial in suppressing the effects of STAT1/STAT3 due to the stimulation of SOCS3 proteins. Prior to the LPS challenge, the macrophages were treated with antibodies against TLR4 and TNFR1 either individually or in combination. On analysis of the macrophage populations by flowcytometry, it was seen that receptor blockade facilitated the phenotypic shift of the M1 macrophages towards M2 resulting in lowered oxidative stress. Blocking of TLR4/TNFR1 upregulated the SOCS3 and mTOR expressions that enabled the transition of inflammatory M1 macrophages towards the anti-inflammatory M2 phenotype, which might be crucial in curbing the inflammatory responses. Also the reduction in the production of inflammatory cytokines such as IL-6, IL-1β due to the reduction in the activation of the STAT1 and STAT3 molecules was observed in our combination treatment group. All these results indicated that neutralization of both TLR4 and TNFR1 might provide new insights in establishing an alternative therapeutic strategy for LPS-sepsis.

Interleukin-17 as predictor mortality of septic patients: a systematic review and meta-analysis

OBJECTIVE

Aim: This study aimed to prove the role of IL-17 on the clinical outcomes of septic patients.

PATIENTS AND METHODS

Materials and Methods: This study used a systematic review and meta-analysis design. Data were obtained by searching articles published between January 2001 and June 2022 in Pubmed, Science Direct, Scopus, and Medline databases to evaluate Interleukin-17 on clinical outcomes in septic patients. Only human studies were used in this study. Meta-analysis was undertaken using random effects models.

RESULTS

Results: Fourteen published studies were eligible, and four studies were included in the meta-analysis. Meta-analysis of the ratio of means (RoM) IL-17 concentration demonstrated a 5.96-fold higher level in non-survivor septic patients compared with survivors (four studies; n = 194 patients; RoM=5.96; 95% CI, 3.51-10.31; p < 0.00001; I2 = 92%).

CONCLUSION

Conclusions: IL-17 levels were significantly elevated in non-survivor and predicted mortality of septic patients.

Nanobody-functionalized conduit with built-in static mixer for specific elimination of cytokines in hemoperfusion

Removing excessively produced cytokines is of paramount significance in blood purification therapy for hypercytokinemia-associated diseases. In this study, we devised a conduit that is modified with nanobodies (Nb) and incorporates static mixers (Nb-SMC) to eliminate surplus cytokines from the bloodstream. The low-pressure-drop (LPD) static mixer, with each unit featuring two 90°-crossed blades, was strategically arranged in a tessellated pattern on the inner wall of the conduit to induce turbulent mixing effects during the flow of blood. This arrangement enhances mass transfer and molecular diffusion, thereby assisting in the identification and elimination of cytokines. By utilizing computational fluid dynamics (CFD) studies, the Nb-SMC was rationally designed and prepared, ensuring an optimal interval between two mixer units (H/G = 2.5). The resulting Nb-SMC exhibited a remarkable selective clearance of IL-17A, reaching up to 85 %. Additionally, the process of Nb immobilization could be adjusted to achieve the simultaneous removal of multiple cytokines from the bloodstream. Notably, our Nb-SMC displayed good blood compatibility without potential adverse effects on the composition of human blood. As the sole documented static mixer-integrated conduit capable of selectively eliminating cytokines at their physiological concentrations, it holds promise in the clinical potential for hypercytokinemia in high-risk patients. STATEMENT OF SIGNIFICANCE: High-efficient cytokines removal in critical care still remains a challenge. The conduit technique we proposed here is a brand-new strategy for cytokines removal in blood purification therapy. On the one hand, nanobody endows the conduit with specific recognition of cytokine, on the other hand, the build-in static mixer enhances the diffusion of antigenic cytokine to the ligand. The combination of these two has jointly achieved the efficient and specific removal of cytokine. This innovative material is the only reported artificial biomaterial capable of selectively eliminating multiple cytokines under conditions close to clinical practice. It has the potential to improve outcomes for patients with hypercytokinemia and reduce the risk of adverse events associated with current treatment modalities.

Single-cell transcriptional gene signature analysis identifies IL-17 signaling pathway as the key pathway in sepsis

Sepsis is a multiple dysregulated systemic inflammatory response with high mortality and leads to public concern. This study was designed to identify possible critical pathways associated with sepsis clinical severity and outcome, which offer potential biomarkers and therapeutic targets for sepsis diagnosis and treatment. Single-cell transcriptome profiles of human peripheral blood mononuclear (PBMC) in the healthy control population and sepsis patients were downloaded from the sepsis database GSE167363 and performed quality control before subsequent analysis. The bulk-RNA sequencing of blood samples in the sepsis-associated databases GSE100159 and GSE133822 was also used to confirm the association between critical pathways and sepsis pathology after processing raw data. We found there was a total of 18 distinct clusters in PBMC of sepsis, which was identified by the t-SNE and UMAP dimension reduction analysis. Meanwhile, the main cell types including B, NK, T, and monocyte cells were identified via the cell maker website and the "Single R" package cell-type annotation analysis. Subsequently, GO and KEGG enrichment analysis of differential expression genes in each cluster found that DEGs between healthy control and sepsis patients were significantly enriched in the IL-17 signaling pathway in monocyte, NK, and T cells. Finally, GSE100159 and GSE133822 confirmed IL-17 signaling pathway-associated genes including IL-17R, TRAF6, RELB, TRAF5, CEBPB, JUNB, CXCL1, CXCL3, CXCL8, CXCR1, and CXCR2 were significantly up-regulated in sepsis blood samples compared with the age-matched healthy control population. Taken together, we concluded that the IL-17 signaling pathway serves as a significant potential mechanism of sepsis and provides a promising therapeutic target for sepsis treatment. This research will further deepen our understanding of sepsis development.

The roles of interleukin-17A in risk stratification and prognosis of patients with sepsis-associated acute kidney injury

BACKGROUND

The aim of this study was to evaluate the roles of interleukin (IL)-17A in risk stratification and prognosis of patients with sepsis-associated acute kidney injury (SAKI).

METHODS

We enrolled 146 sepsis patients (84 non-SAKI and 62 SAKI patients) admitted to the emergency department from November 2020 to November 2021. Patients with SAKI were differentiated based on the severity of acute kidney injury. All clinical parameters were evaluated upon admission before administering antibiotic treatment. Inflammatory cytokines were assessed using flow cytometry and the Pylon 3D automated immunoassay system (ET Healthcare). In addition, a receiver operating characteristic (ROC) curve was utilized to determine the prognostic values of IL-17A in SAKI.

RESULTS

The levels of creatinine, IL-2, IL-4, IL-6, IL-17A, tumor necrosis factor alpha, C-reactive protein, and procalcitonin (PCT) were significantly higher in the SAKI group than in the non-SAKI group (p < 0.05). The level of IL-17A revealed significant differences among stages 1, 2, and 3 in SAKI patients (p < 0.05). The mean levels of PCT, IL-4, and IL-17A were significantly higher in the non-survival group than in the survival group in SAKI patients (p < 0.05). In addition, the area under the ROC curve of IL-17A was 0.811. Moreover, the IL-17A cutoff for differentiating survivors from non-survivors was 4.7 pg/mL, of which the sensitivity and specificity were 77.4% and 71.0%, respectively.

CONCLUSION

Elevated levels of IL-17A could predict that SAKI patients are significantly prone to worsening kidney injury with higher mortality. The usefulness of IL-17A in treating SAKI requires further research.

The association of IL-17A rs2275913 single nucleotide polymorphism with anti-tuberculous drug resistance in patients with pulmonary tuberculosis

BACKGROUND

Drug-resistant  Tuberculosis (DR-TB) is a global health burden with high morbidity and mortality in developing countries including Egypt. The susceptibility to infection with DR-TB strains may be genetically determined. Several interleukin gene polymorphisms were investigated as risk factors for tuberculosis infection but focusing on their association with DR-TB was limited. Therefore, the objective of this study is to assess the association of IL 17 - 197 G > A (rs2275913) single nucleotide polymorphism (SNP) with susceptibility to DR-TB strains in comparison to drug-sensitive tuberculosis (DS-TB) strains in Egyptian patients with pulmonary TB. This cross-sectional study was conducted on 80 patients with DR-TB strains and 80 with DS-TB strains as a control group. Both age and sex were comparable among the study's groups. IL-17 - 197 G > A (rs2275913) SNP was genotyped by real-time PCR, and IL-17 serum concentration was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The GA and AA genotype frequencies of IL 17 - 197 G > A (rs2275913) SNP were significantly higher in patients with DR-TB strains than those with DS-TB strains (p < 0.001). The frequency of the A allele was significantly (p < 0.001) higher in patients with DR-TB group (32.5%) compared to the control group (13.8%). Substantial higher serum levels of IL-17 were detected in the DR-TB group with significant association with AA and AG genotypes.

CONCLUSION

Polymorphism in IL-17 -197 G > A (rs2275913) resulted in higher serum levels of IL-17 and Egyptian patients with such polymorphism are three times at risk of infection with DR-TB strains than patients with wild type.

Network pharmacology-based approach to explore the underlying mechanism of sinomenine on sepsis-induced myocardial injury in rats

Background: Sepsis, a systemic disease, usually induces myocardial injury (MI), and sepsis-induced MI has become a significant contributor to sepsis-related deaths in the intensive care unit. The objective of this study is to investigate the role of sinomenine (SIN) on sepsis-induced MI and clarify the underlying mechanism based on the techniques of network pharmacology. Methods: Cecum ligation and puncture (CLP) was adopted to induce sepsis in male Sprague-Dawley (SD) rats. Serum indicators, echocardiographic cardiac parameters, and hematoxylin and eosin (H&E) staining were conducted to gauge the severity of cardiac damage. The candidate targets and potential mechanism of SIN against sepsis-induced MI were analyzed via network pharmacology. Enzyme-linked immunosorbent assay was performed for detecting the serum concentration of inflammatory cytokines. Western blot was applied for evaluating the levels of protein expression. Terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling assay was applied to assess cardiomyocyte apoptosis. Results: SIN significantly improved the cardiac functions, and attenuated myocardial structural damage of rats as compared with the CLP group. In total, 178 targets of SIN and 945 sepsis-related genes were identified, and 33 overlapped targets were considered as candidate targets of SIN against sepsis. Enrichment analysis results demonstrated that these putative targets were significantly associated with the Interleukin 17 (IL-17) signal pathway, inflammatory response, cytokines-mediated signal pathway, and Janus Kinase-Signal Transducers and Activators of Transcription (JAK-STAT) pathway. Molecular docking suggested that SIN had favorable binding affinities with Mitogen-Activated Protein Kinase 8 (MAPK8), Janus Kinase 1 (JAK1), Janus Kinase 2 (JAK2), Signal Transducer and Activator of Transcription 3 (STAT3), and nuclear factor kappa-B (NF-κB). SIN significantly reduced the serum concentration of Tumor Necrosis Factor-α (TNF-α), Interleukin 1 Beta (IL-1β), Interleukin 6 (IL-6), Interferon gamma (IFN-γ), and C-X-C Motif Chemokine Ligand 8 (CXCL8), lowered the protein expression of phosphorylated c-Jun N-terminal kinase 1 (JNK1), JAK1, JAK2, STAT3, NF-κB, and decreased the proportion of cleaved-caspase3/caspase3. In addition, SIN also significantly inhibited the apoptosis of cardiomyocytes as compared with the CLP group. Conclusion: Based on network pharmacology analysis and corresponding experiments, it was concluded that SIN could mediate related targets and pathways to protect against sepsis-induced MI.

Rapid, High-Throughput Single-Cell Multiplex In Situ Tagging (MIST) Analysis of Immunological Disease with Machine Learning

The cascade of immune responses involves activation of diverse immune cells and release of a large amount of cytokines, which leads to either normal, balanced inflammation or hyperinflammatory responses and even organ damage by sepsis. Conventional diagnosis of immunological disorders based on multiple cytokines in the blood serum has varied accuracy, and it is difficult to distinguish normal inflammation from sepsis. Herein, we present an approach to detect immunological disorders through rapid, ultrahigh-multiplex analysis of T cells using single-cell multiplex in situ tagging (scMIST) technology. scMIST permits simultaneous detection of 46 markers and cytokines from single cells without the assistance of special instruments. A cecal ligation and puncture sepsis model was built to supply T cells from two groups of mice that survived the surgery or died after 1 day. The scMIST assays have captured the T cell features and the dynamics over the course of recovery. Compared with cytokines in the peripheral blood, T cell markers show different dynamics and cytokine levels. We have applied a random forest machine learning model to single T cells from two groups of mice. Through training, the model has been able to predict the group of mice through T cell classification and majority rule with 94% accuracy. Our approach pioneers the direction of single-cell omics and could be widely applicable to human diseases.

Monitoring of the Forgotten Immune System during Critical Illness-A Narrative Review

Immune organ failure is frequent in critical illness independent of its cause and has been acknowledged for a long time. Most patients admitted to the ICU, whether featuring infection, trauma, or other tissue injury, have high levels of alarmins expression in tissues or systemically which then activate innate and adaptive responses. Although necessary, this response is frequently maladaptive and leads to organ dysfunction. In addition, the counter-response aiming to restore homeostasis and repair injury can also be detrimental and contribute to persistent chronic illness. Despite intensive research on this topic in the last 40 years, the immune system is not routinely monitored in critical care units. In this narrative review we will first discuss the inflammatory response after acute illness and the players of maladaptive response, focusing on neutrophils, monocytes, and T cells. We will then go through commonly used biomarkers, like C-reactive protein, procalcitonin and pancreatic stone protein (PSP) and what they monitor. Next, we will discuss the strengths and limitations of flow cytometry and related techniques as an essential tool for more in-depth immune monitoring and end with a presentation of the most promising cell associated markers, namely HLA-DR expression on monocytes, neutrophil expression of CD64 and PD-1 expression on T cells. In sum, immune monitoring critically ill patients is a forgotten and missing piece in the monitoring capacity of intensive care units. New technology, including bed-side equipment and in deep cell phenotyping using emerging multiplexing techniques will likely allow the definition of endotypes and a more personalized care in the future.

Potential Immune Indicators for Predicting the Prognosis of COVID-19 and Trauma: Similarities and Disparities

Although cellular and molecular mediators of the immune system have the potential to be prognostic indicators of disease outcomes, temporal interference between diseases might affect the immune mediators, and make them difficult to predict disease complications. Today one of the most important challenges is predicting the prognosis of COVID-19 in the context of other inflammatory diseases such as traumatic injuries. Many diseases with inflammatory properties are usually polyphasic and the kinetics of inflammatory mediators in various inflammatory diseases might be different. To find the most appropriate evaluation time of immune mediators to accurately predict COVID-19 prognosis in the trauma environment, researchers must investigate and compare cellular and molecular alterations based on their kinetics after the start of COVID-19 symptoms and traumatic injuries. The current review aimed to investigate the similarities and differences of common inflammatory mediators (C-reactive protein, procalcitonin, ferritin, and serum amyloid A), cytokine/chemokine levels (IFNs, IL-1, IL-6, TNF-α, IL-10, and IL-4), and immune cell subtypes (neutrophil, monocyte, Th1, Th2, Th17, Treg and CTL) based on the kinetics between patients with COVID-19 and trauma. The mediators may help us to accurately predict the severity of COVID-19 complications and follow up subsequent clinical interventions. These findings could potentially help in a better understanding of COVID-19 and trauma pathogenesis.

Interleukin 35 contributes to immunosuppression by regulating inflammatory cytokines and T cell populations in the acute phase of sepsis

Cytokines interact closely with each other and play a crucial role in the progression of sepsis. We focused on the associations of a cytokine network with IL-35 in sepsis. First, the retrospective study included 42 patients with sepsis and 23 healthy controls. Blood samples were collected from patients on days 1, 2, 4. Levels of IL-35, IL-1β, IL-4, IL-6, IL-10, IL-17A, TNF-α and IFN-γ were measured. They all increased to various extend on days 1, 2, 4, and strongly associated with markers of disease severity. Network analysis revealed a network formed by IL-35, with IL-6, IL-10, IL-17A, TNF-α and IFN-γ throughout the acute phase of sepsis(days 1, 2 and4). Then, the CLP-induced septic rats were used. The recombinant human IL-35(rIL-35) upregulated the levels of IL-10, but downregulated IL-4, IL-6, IL-17A, TNF-α and IFN-γ, while it had no significant effect on IL-1β, and upregulated the percentages of CD4⁺CD25⁺Tregs, and iTR35, but downregulated Teff cells in the peripheral blood. The rIL-35 reduced inflammation damage and improved prognosis of the septic rats. IL-35 forms a network with other cytokines and plays a major role in the immunopathogenesis of sepsis.

Sepsis in Trauma: A Deadly Complication

Sepsis is a major cause of death following a traumatic injury. As a life-threatening medical emergency, it is defined as the body's extreme response to an infection. Without timely treatment, sepsis can rapidly lead to tissue damage, and organ failure The capacity to limit tissue damage through metabolic adaptation and repair processes is associated with an excessive immune response of the host. It is important to make an early prediction of sepsis, based on the quick Sepsis associated Organ Failure Assessment Score (qSOFA), so an accurate treatment can be initiated reducing the morbidity and mortality at the emergency and UCI services. Many factors increase the rate of complications and the development of sepsis in a trauma patient, representing a challenge to orthopedic surgeons. Several early biomarkers that help to identify and predict the inflammatory and immune responses of the host going through polytrauma and sepsis have been studied; procalcitonin (PCT), C-reactive protein (CRP), glycosylated hemoglobin (HbA1c), the Neutrophil/lymphocyte ratio (NLR), Interleukin-17 (IL-17), Caspase-1, Vanin-1, High-density lipoproteins (HDL), and the Thrombin-activable fibrinolysis inhibitor (TAFI). Once sepsis is diagnosed, treatment must be immediately initiated with an appropriate empiric antimicrobial, an all-purpose supporting treatment, and metabolic control, followed by the specific antibiotic therapy based on blood culture. Since the participation of sepsis in polytrauma has been recognized as a key event in the outcome of patients at the ICU, the ability of the specialist to early recognize a septic process has become a key feature to reduce mortality and improve clinical prognosis.

Nanobody-loaded immunosorbent for highly-specific removal of interleukin-17A from blood

Elimination of overproduced cytokines from blood can relieve immune system disorders caused by hypercytokinemia. Due to the central roles of interleukin-17A (IL-17A) plays in regulating the immunity and inflammatory responses in humans, here, a novel immunosorbent containing anti-IL-17A nanobodies (Nbs) was constructed for IL-17A removal from blood. The theoretical maximum adsorption capacity estimated from the Langmuir isotherm is up to 11.55 mg/g gel, which is almost consistent with the saturated adsorption capacity determined in dynamic adsorption. The in vitro plasma perfusion test demonstrated a remarkable adsorptive performance of the Nb-coupled sorbent since more than 75% IL-17A could be eliminated under the plasma/sorbent ratio of 1000:1. These results indicated the Nb-loaded immunosorbent can provide a simple and economic platform technology for immunoaffinity depletion of single or even multiple cytokines from plasma.

T cell cytokines in the diagnostic of early-onset sepsis

BACKGROUND

Early-onset sepsis (EOS) remains a substantial cause of morbidity and mortality among neonates. Yet, currently available biological parameters have not proven to be accurate enough to predict EOS reliably. This study aimed to determine serum concentrations of 13 cytokines in umbilical cord blood and evaluate their diagnostic value for EOS.

METHODS

A prospective single-center study that included analysis of umbilical cord blood of term and preterm neonates who were born from March 2017 to November 2017. Using ELISA analysis, 13 cytokines were simultaneously quantified and correlated with the development of EOS.

RESULTS

Four hundred and seventy-four neonates were included, of which seven met the criteria for culture-positive EOS. Interleukin (IL)-6 (p < 0.001), IL-9 (p = 0.003), and IL-21 (p < 0.001) were significantly increased in neonates with EOS compared to controls. Sensitivity and specificity for IL-6, IL-9, and IL-21 at the defined cut-off points were 85.7 and 77.3%, 71.4 and 62.5%, and 71.4 and 52.0%, respectively.

CONCLUSIONS

In neonates with EOS, IL-9 and IL-21 are significantly elevated and may be employed in the diagnostic of EOS. However, diagnostic accuracy remains lower than with IL-6. Values of 13 T cell cytokines may be used as reference values for future studies in neonates.

IMPACT

Interleukin-9 (IL-9) and interleukin-21 (IL-21) are significantly elevated in neonates with early-onset sepsis. IL-9 and IL-21 have been shown to play a specific role in neonatal sepsis. Neonatal reference values were generated for several cytokines. IL-9 and IL-21 might be attractive biomarkers for neonatal sepsis in future. This study is likely to promote further research in this area. Values of several T cell cytokines may be used as reference values for future studies in neonates.

The Role of DAMPS in Burns and Hemorrhagic Shock Immune Response: Pathophysiology and Clinical Issues. Review

Severe or major burns induce a pathophysiological, immune, and inflammatory response that can persist for a long time and affect morbidity and mortality. Severe burns are followed by a "hypermetabolic response", an inflammatory process that can be extensive and become uncontrolled, leading to a generalized catabolic state and delayed healing. Catabolism causes the upregulation of inflammatory cells and innate immune markers in various organs, which may lead to multiorgan failure and death. Burns activate immune cells and cytokine production regulated by damage-associated molecular patterns (DAMPs). Trauma has similar injury-related immune responses, whereby DAMPs are massively released in musculoskeletal injuries and elicit widespread systemic inflammation. Hemorrhagic shock is the main cause of death in trauma. It is hypovolemic, and the consequence of volume loss and the speed of blood loss manifest immediately after injury. In burns, the shock becomes evident within the first 24 h and is hypovolemic-distributive due to the severely compromised regulation of tissue perfusion and oxygen delivery caused by capillary leakage, whereby fluids shift from the intravascular to the interstitial space. In this review, we compare the pathophysiological responses to burns and trauma including their associated clinical patterns.

Deep immune profiling of whole blood to identify early immune signatures that correlate to patient outcome after major trauma

BACKGROUND

Major injury results in an early cascade of immunologic responses that increase susceptibility to infection and multiorgan dysfunction. Detailed immune profiling by mass cytometry has the potential to identify immune signatures that correspond to patient outcomes. Our objective was to determine the prognostic value of immune signatures early after major trauma injury.

METHODS

Trauma patients (n = 17) were prospectively enrolled between September 2018 and December 2019. Serial whole blood samples were obtained from trauma patients (mean Injury Severity Score, 26.2; standard error of the mean, 3.7) at Days 1 and 3 after injury, and from age- and sex-matched uninjured controls using a standardized protocol for fixation, storage, and labeling. Computational analyses including K-nearest neighbor automated clustering of immune cells and Spearman's correlation analysis were used to identify correlations between cell populations, clinical measures, and patient outcomes.

RESULTS

Analysis revealed nine immune cell clusters that correlated with one or more clinical outcomes. On Days 1 and 3 postinjury, the abundance of immature neutrophil and classical monocytes exhibited a strong positive correlation with increased intensive care unit and hospital length of stay. Conversely, the abundance of CD4 T-cell subsets, namely Th17 cells, is associated with improved patient outcomes including decreased ventilator days (r = -0.76), hospital-acquired pneumonia (r = -0.69), and acute kidney injury (r = -0.73).

CONCLUSION

Here, we provide a comprehensive multitime point immunophenotyping analysis of whole blood from patients soon after traumatic injury to determine immune correlates of adverse outcomes. Our findings indicate that alterations in myeloid-origin cell types may contribute to immune dysfunction after injury. Conversely, the presence of effector T cell populations corresponds with decreased hospital length of stay and organ dysfunction. Overall, these data identify novel immune signatures following traumatic injury that support the view that monitoring of immune (sub)-populations may provide clinical decision-making support for at-risk patients early in their hospital course.

LEVEL OF EVIDENCE

Prognostic/Epidemiologic, Level IV.

γδ T/Interleukin-17A Contributes to the Effect of Maresin Conjugates in Tissue Regeneration 1 on Lipopolysaccharide-Induced Cardiac Injury

The mechanisms underlying sepsis-induced cardiomyopathy (SIC) remain poorly understood, and there are no specific therapeutics for SIC. We investigated the effects of maresin conjugates in tissue regeneration 1 (MCTR1) on SIC and explored its potential mechanisms. The experiments were conducted using an endotoxemia model induced by lipopolysaccharide (LPS). Mice were given MCTR1 intravenously 6 h after LPS stimulation. Echocardiography was performed to assess cardiac function 12 h after LPS administration. Treatment with MCTR1 significantly enhanced cardiac function and reduced LPS-induced increase of mRNA expression levels of inflammation cytokines. Transcriptomic analysis indicated that MCTR1 inhibited neutrophil chemotaxis via the IL-17 signaling pathway. We confirmed that MCTR1 reduced the expressions of neutrophil chemoattractants and neutrophil infiltration in the LPS-stimulated hearts. MCTR1 also resulted in a considerable reduction in IL-17A production mainly derived from γδ T cells. Moreover, our results provided the first evidence that neutralizing IL-17A or depletion of γδ T cells markedly decreased neutrophil recruitment and enhanced cardiac function in LPS-induced cardiac injury. These results suggest that MCTR1 alleviates neutrophil infiltration thereby improves cardiac function in LPS-induced cardiac injury via the IL-17 signaling pathway. Thus, MCTR1 represented a novel therapeutic strategy for patients with SIC.

IL-17 is a potential biomarker for predicting the severity and outcomes of pulmonary contusion in trauma patients

Pulmonary contusion (PC) is very common in blunt chest trauma, and always results in negative pulmonary outcomes, such as pneumonia, acute respiratory distress syndrome (ARDS), respiratory failure or even death. However, there are no effective biomarkers which can be used to predict the outcomes in these patients. The present study aimed to determine the value of interleukin (IL)-17 and IL-22 in predicting the severity and outcomes of PC in trauma patients. All trauma patients admitted to The First Affiliated Hospital of Guangxi Medical University between January 2015 and December 2017, were studied. Patients aged >14 years old with a diagnosis of PC upon their admission to the emergency department were included. Patients with PC were enrolled as the PC group, patients without PC were enrolled as the non-PC group, and healthy individuals were selected as the control group. Clinical information, including sociodemographic parameters, clinical data, biological findings and therapeutic interventions were recorded for all patients who were enrolled. Blood samples were collected and stored according to the established protocols. PC volume was measured by computed tomography and plasma cytokine levels were assayed by ELISA. A total of 151 patients with PC (PC group) and 159 patients without PC (non-PC group) were included in the present study. In addition, 50 healthy individuals were used as the control group. The primary cause of PC was motor vehicle crashes. PC patients had more rib fractures, but similar injury severity scores compared with other patients. More patients received Pleurocan drainage treatment and had pneumonia complications in the PC group compared with the other two groups. PC patients had a high incidence of ARDS and admission to the intensive care unit (ICU). PC patients also experienced longer periods on mechanical ventilation and had longer stays in the ICU and hospital. PC volume was effective in predicting the outcomes of PC patients. IL-22 levels were similar in the PC group and non-PC group. However, IL-17 could be used as a biomarker to predict the severity of PC, and was strongly associated with PC volume. IL-17 was significantly associated with pro-inflammatory complications in PC patients and could be used as a biomarker for predicting in-patient outcomes of patients with PC. In conclusion, IL-17 is a potential biomarker for predicting the severity and outcomes of PC in trauma patients.

Early use of high-dose vitamin C is beneficial in treatment of sepsis

PURPOSE

Vitamin C has shown benefits in patients with sepsis in addition to standard therapy recently. However, further evidence is required to verify the efficacy of vitamin C in clinical practice. This study aimed to investigate the effect of adjunctive intravenous high-dose vitamin C treatment on hospital mortality in patients with sepsis.

METHODS

One hundred seventeen patients with sepsis in our department from June 2017 to May 2019 were randomly divided into two groups: the control group (56 cases) and the vitamin C group (61 cases). The control group was treated by the routine and basic therapy with intravenous drip of 5% dextrose and placebo (100 ml/time, 2 times/day), while the vitamin C group was administered intravenously by 3.0 g vitamin C dissolved into 5% dextrose (100 ml/time, 2 times/day) based on the control group. The mortality and efficacy were statistically analyzed and compared between the two groups.

RESULTS

The 28-day mortality differed significantly between the control group and the vitamin C group (42.97% vs. 27.93%) (p < 0.05). The changes in the sepsis-related organ failure assessment (ΔSOFA) scores at 72 h after ICU admission (4.2 vs. 2.1), the application time of vasoactive drugs (25.6 vs. 43.8), and the procalcitonin clearance (79.6% vs. 61.3%) differed significantly between groups (p < 0.05).

CONCLUSION

The early treatment of sepsis with intravenous high-dose vitamin C in combination with standard therapy showed a beneficial effect on sepsis, in terms of the reduced 28-day mortality, the decreased SOFA score, and the increased clearance rate of procalcitonin.

Damage-associated molecular patterns in trauma

In 1994, the "danger model" argued that adaptive immune responses are driven rather by molecules released upon tissue damage than by the recognition of "strange" molecules. Thus, an alternative to the "self versus non-self recognition model" has been provided. The model, which suggests that the immune system discriminates dangerous from safe molecules, has established the basis for the future designation of damage-associated molecular patterns (DAMPs), a term that was coined by Walter G. Land, Seong, and Matzinger. The pathological importance of DAMPs is barely somewhere else evident as in the posttraumatic or post-surgical inflammation and regeneration. Since DAMPs have been identified to trigger specific immune responses and inflammation, which is not necessarily detrimental but also regenerative, it still remains difficult to describe their "friend or foe" role in the posttraumatic immunogenicity and healing process. DAMPs can be used as biomarkers to indicate and/or to monitor a disease or injury severity, but they also may serve as clinically applicable parameters for optimized indication of the timing for, i.e., secondary surgeries. While experimental studies allow the detection of these biomarkers on different levels including cellular, tissue, and circulatory milieu, this is not always easily transferable to the human situation. Thus, in this review, we focus on the recent literature dealing with the pathophysiological importance of DAMPs after traumatic injury. Since dysregulated inflammation in traumatized patients always implies disturbed resolution of inflammation, so-called model of suppressing/inhibiting inducible DAMPs (SAMPs) will be very briefly introduced. Thus, an update on this topic in the field of trauma will be provided.

Biology of Interleukin-17 and Its Pathophysiological Significance in Sepsis

The interleukin (IL)-17 family includes six structure-related cytokines (A-F). To date, majority of studies have focused on IL-17A. IL-17A plays a pivotal role in various infectious diseases, inflammatory and autoimmune disorders, and cancer. Several recent studies have indicated that IL-17A is a biomarker as well as a therapeutic target in sepsis. In the current review, we summarize the biological functions of IL-17, including IL-17-mediated responses and signal transduction pathways, with particular emphasis on clinical relevance to sepsis.

IL-17A activated by Toll-like receptor 9 contributes to the development of septic acute kidney injury

Toll-like receptor 9 (TLR9), which is activated by endogenously released mtDNA during sepsis, contributes to the development of polymicrobial septic acute kidney injury (AKI). However, downstream factors of TLR9 to AKI remain unknown. We hypothesized that IL-17A activated by TLR9 may play a critical role in septic AKI development. To determine the effects of TLR9 on IL-17A production in septic AKI, we used a cecal ligation and puncture (CLP) model in Tlr9 knockout (Tlr9KO) mice and wild-type (WT) littermates. We also investigated the pathway from TLR9 activation in dendritic cells (DCs) to IL-17A production by γδT cells in vitro. To elucidate the effects of IL-17A on septic AKI, Il-17a knockout (Il-17aKO) mice and WT littermates were subjected to CLP. We further investigated the relationship between the TLR9-IL-17A axis and septic AKI by intravenously administering recombinant IL-17A or vehicle into Tlr9KO mice and assessing kidney function. IL-17A levels in both plasma and the peritoneal cavity and mRNA levels of IL-23 in the spleen were significantly higher in WT mice after CLP than in Tlr9KO mice. Bone marrow-derived DCs activated by TLR9 induced IL-23 and consequently promoted IL-17A production in γδT cells in vitro. Knockout of Il-17a improved survival, functional and morphological aspects of AKI, and splenic apoptosis after CLP. Exogenous IL-17A administration aggravated CLP-induced AKI attenuated by knockout of Tlr9. TLR9 in DCs mediated IL-17A production in γδT cells during sepsis and contributed to the development of septic AKI.

Trauma Induces Interleukin-17A Expression on Th17 Cells and CD4+ Regulatory T Cells as Well as Platelet Dysfunction

Background: The organism's immune response to trauma is distinctively controlled, its dysregulation leading to severe post-traumatic complications. Platelets, CD4+ regulatory T cells (CD4+ Tregs) and T helper 17 (Th17) cells have been identified to participate in the post-traumatic immune response. Unfortunately, little is known about their exact role and potential interdependency in humans. Aims of this clinical trial were to phenotype the human immune response following injury and to identify risk factors rendering the host more susceptible to trauma induced injury.

Methods: This non-interventional prospective clinical trial enrolled patients following multiple trauma, follow up was conducted for 10 days. Peripheral blood CD4+ Tregs and Th17 cells were analyzed using flow cytometry to determine Interleukin 17A (IL-17A) expression. Hemostasis and platelet function were assessed with rotational thromboelastometry (ROTEM^®). Subgroup analysis was conducted for the factors gender, age, and trauma severity.

Results and Conclusion: This is the first clinical trial to phenotype the immune response following trauma, focusing on platelets, and the adaptive immune response. We discovered a novel increased IL-17A expression on Th17 cells and on CD4+ Tregs following trauma and describe the kinetics of the immune response. The IL-17A response on CD4+ Tregs challenges the ascribed role of CD4+ Tregs to be solely counter inflammatory in this setting. Furthermore, despite a rising number of platelets, ROTEM analysis shows post-traumatic platelet dysfunction. Subgroup analysis revealed gender, age, and trauma severity as influencing factors for several of the analyzed parameters.

IL-17, IL-27, and IL-33: A Novel Axis Linked to Immunological Dysfunction During Sepsis

Sepsis is a major cause of morbidity and mortality worldwide despite numerous attempts to identify effective therapeutics. While some sepsis deaths are attributable to tissue damage caused by inflammation, most mortality is the result of prolonged immunosuppression. Ex vivo, immunosuppression during sepsis is evidenced by a sharp decrease in the production of pro-inflammatory cytokines by T cells and other leukocytes and increased lymphocyte apoptosis. This allows suppressive cytokines to exert a greater inhibitory effect on lymphocytes upon antigen exposure. While some pre-clinical and clinical trials have demonstrated utility in targeting cytokines that promote lymphocyte survival, this has not led to the approval of any therapies for clinical use. As cytokines with a more global impact on the immune system are also altered by sepsis, they represent novel and potentially valuable therapeutic targets. Recent evidence links interleukin (IL)-17, IL-27, and IL-33 to alterations in the immune response during sepsis using patient serum and murine models of peritonitis and pneumonia. Elevated levels of IL-17 and IL-27 are found in the serum of pediatric and adult septic patients early after sepsis onset and have been proposed as diagnostic biomarkers. In contrast, IL-33 levels increase in patient serum during the immunosuppressive stage of sepsis and remain high for more than 5 months after recovery. All three cytokines contribute to immunological dysfunction during sepsis by disrupting the balance between type 1, 2, and 17 immune responses. This review will describe how IL-17, IL-27, and IL-33 exert these effects during sepsis and their potential as therapeutic targets.

A nationwide fluidics biobank of polytraumatized patients: implemented by the Network "Trauma Research" (NTF) as an expansion to the TraumaRegister DGU® of the German Trauma Society (DGU)

To decrypt the complexity of the posttraumatic immune responses and to potentially identify novel research pathways for exploration, large-scale multi-center projects including not only in vivo and in vitro modeling, but also temporal sample and material collection along with clinical data capture from multiply injured patients is of utmost importance. To meet this gap, a nationwide biobank for fluidic samples from polytraumatized patients was initiated in 2013 by the task force Network “Trauma Research” (Netzwerk Traumaforschung, NTF) of the German Trauma Society (Deutsche Gesellschaft für Unfallchirurgie e.V., DGU). The NTF-Biobank completes the clinical NTF-Biobank Database and complements the TR-DGU with temporal biological samples from multiply injured patients. The concept behind the idea of the NTF-Biobank was to create a robust interface for meaningful innovative basic, translational and clinical research. For the first time, an integrated platform to prospectively evaluate and monitor candidate biomarkers and/or potential therapeutic targets in biological specimens of quality-controlled and documented patients is introduced, allowing reduction in variability of measurements with high impact due to its large sample size. Thus, the project was introduced to systemically evaluate and monitor multiply injured patients for their (patho-)physiological sequalae together with their clinical treatment strategies applied for overall outcome improval.

Danger signals in trauma

This review summarizes a short list of currently discussed trauma-induced danger-associated molecular patterns (DAMP). Due to the bivalent character and often pleiotropic effects of a DAMP, it is difficult to describe its "friend or foe" role in post-traumatic inflammation and regeneration, both systemically as well locally in tissues. DAMP can be used as biomarkers to indicate or monitor disease or injury severity, but also may serve as clinically applicable parameters for better indication and timing of surgery. Due to the inflammatory processes at the local tissue level or the systemic level, the precise role of DAMP is not always clear to define. While in vitro and experimental studies allow for the detection of these biomarkers at the different levels of an organism-cellular, tissue, circulation-this is not always easily transferable to the human setting. Increased knowledge exploring the dual role of DAMP after trauma, and concentrating on their nuclear functions, transcriptional targets, release mechanisms, cellular sources, multiple functions, their interactions and potential therapeutic targeting is warranted.