Th17 cells: critical mediators of host responses to burn injury and sepsis

CD40L-Activated DC Promotes Th17 Differentiation and Inhibits Th2 Differentiation in Sepsis-Induced Lung Injury via cGAS-STING Signaling

Immune hemostasis due to an infection plays a vital role in sepsis-induced multiple organ dysfunction. Dendritic cells (DC) and T helper (Th) cells are the key members of the immune system maintaining immune homeostasis. This study aimed to explore the effect and mechanism of CD40L on the activation of DC and activated DC-induced Th2/Th17 differentiation. A CD40L knockout and cecal ligation and puncture (CLP) mouse model was established via cecal ligation. HE staining was used to evaluate the pathological changes. The gene expressions were studied using quantitative real-time polymerase chain reaction (qRT-PCR), while a transwell system was used to perform the co-culture of DC and T-cells. Flow cytometry was performed to detect the subtype of T and DC cells. ELISA was used to assess the amount of inflammatory factors. CD40L was highly expressed in the plasma of CLP mice. Knock out of CD40L inhibited the activation of DC cell and Th17 differentiation while promoting the Th2 differentiation. The mechanistic investigations revealed that CD40L promoted the activation of cGAS-STING pathway. Rescue experiments indicated that CD40L mediated DC activation via cGAS-STING signaling. Moreover, co-culturing of CD and CD+4 T-cells demonstrated that silencing of CD40L in DC suppressed the DC activation and inhibited Th17 differentiation while promoting Th2 differentiation. These findings revealed a relationship between CD40L, DC activation, and Th2/Th17 differentiation balance in sepsis-induced acute lung injury for the first time. These findings are envisaged to provide novel molecular targets for sepsis-induced lung injury treatment.

Clinicopathological studies on ulcerative lymphangitis in cattle: Alterations in serum inflammatory cytokines, anti-microbial, organs functions, and oxidative stress-related biomarkers

Background

Affection with Corynebacterium pseudotuberculosis (C. pseudotuberculosis) and development of cellulitis and/or abscess formation with cutaneous lymphangitis in cattle is rare to some extent, so literature about the biochemical changes that would accompany this infection is rare.

Aim

In this context, the present study was designed to screen the effect of the infection with C. pseudotuberculosis cutaneous lymphangitis on the release of some immune molecules, organ functions, and redox state in Baladi cows.

Methods

Fourteen Baladi cows from a small dairy farm in El-Behira, Egypt, were selected to complete this study. After bacteriological culture confirmation, seven of them were found suffering from cutaneous lesions due to infection with C. pseudotuberculosis (Diseased group), while the others were healthy (Healthy group). Serum samples were obtained to evaluate the presumptive changes in some clinicopathological parameters.

Results

Serum analysis revealed a significant decrease in the levels of interferon-gamma and interleukin-17 as well as a significant decrement in the concentration of beta-defensin (β-defensin) and lipocalin-2. While serum level of interleukin-10 recorded a significant increase in these animals when compared to healthy control animals. Concurrently, the affected animals recorded a significant elevation in serum levels of hepato-cardiac enzymes, urea, and creatinine in addition to disturbance in the serum redox state.

Conclusion

In conclusion, infection with C. pseudotuberculosis cattle may disturb the defensive immune state, body organ function, and redox state of the animals.

Systemic immune response of burns from the acute to chronic phase

Immune responses that occur following burn injury comprise a series of reactions that are activated in response to damaged autologous tissues, followed by removal of damaged tissues and foreign pathogens such as invading bacteria, and tissue repair. These immune responses are considered to be programmed in living organisms. Developments of modern medicine have led to the saving of burned patients who could not be cured previously; however, the programmed response is no longer able to keep up, and various problems have arisen. This paper describes the mechanism of immune response specific to burn injury and the emerging concept of persistent inflammation, immunosuppression, and catabolism syndrome.

Maternal consumption of a high-fat diet modulates the inflammatory response in their offspring, mediated by the M1 muscarinic receptor

Introduction

High-fat diet (HFD) consumption is associated with various metabolic disorders and diseases. Both pre-pregnancy and maternal obesity can have long-term consequences on offspring health. Furthermore, consuming an HFD in adulthood significantly increases the risk of obesity and metabolic disorders. However, an intriguing phenomenon known as the obesity paradox suggests that obesity may confer a protective effect on mortality outcomes in sepsis. In sepsis, activation of the cholinergic anti-inflammatory pathway (CAP) can help mitigate systemic inflammation. We employed a metabolic programming model to explore the relationship between maternal HFD consumption and offspring response to sepsis.

Methods

We fed female mice either a standard diet (SC) or an HFD during the pre-pregnancy, pregnancy, and lactation periods. Subsequently, we evaluated 28-day-old male offspring.

Results

Notably, we discovered that offspring from HFD-fed dams (HFD-O) exhibited a higher survival rate compared with offspring from SC-fed dams (SC-O). Importantly, inhibition of the m1 muscarinic acetylcholine receptor (m1mAChR), involved in the CAP, in the hypothalamus abolished this protection. The expression of m1mAChR in the hypothalamus was higher in HFD-O at different ages, peaking on day 28. Treatment with an m1mAChR agonist could modulate the inflammatory response in peripheral tissues. Specifically, CAP activation was greater in the liver of HFD-O following agonist treatment. Interestingly, lipopolysaccharide (LPS) challenge failed to induce a more inflammatory state in HFD-O, in contrast to SC-O, and agonist treatment had no additional effect. Analysis of spleen immune cells revealed a distinct phenotype in HFD-O, characterized by elevated levels of CD4+ lymphocytes rather than CD8+ lymphocytes. Moreover, basal Il17 messenger RNA (mRNA) levels were lower while Il22 mRNA levels were higher in HFD-O, and we observed the same pattern after LPS challenge.

Discussion

Further examination of myeloid cells isolated from bone marrow and allowed to differentiate showed that HFD-O macrophages displayed an anti-inflammatory phenotype. Additionally, treatment with the m1mAChR agonist contributed to reducing inflammatory marker levels in both groups. In summary, our findings demonstrate that HFD-O are protected against LPS-induced sepsis, and this protection is mediated by the central m1mAChR. Moreover, the inflammatory response in the liver, spleen, and bone marrow-differentiated macrophages is diminished. However, more extensive analysis is necessary to elucidate the specific mechanisms by which m1mAChR modulates the immune response during sepsis.

Monocytes and T cells incorporated in full skin equivalents to study innate or adaptive immune reactions after burn injury

Introduction

Thermal injury often leads to prolonged and excessive inflammation, which hinders the recovery of patients. There is a notable absence of suitable animal-free models for investigating the inflammatory processes following burn injuries, thereby impeding the development of more effective therapies to improve burn wound healing in patients.

Methods

In this study, we established a human full skin equivalent (FSE) burn wound model and incorporated human peripheral blood-derived monocytes and T cells.

Results

Upon infiltration into the FSEs, the monocytes differentiated into macrophages within a span of 7 days. Burn-injured FSEs exhibited macrophages with increased expression of HLA-DR+ and elevated production of IL-8 (CXCL8), in comparison to uninjured FSEs. Among the T cells that actively migrated into the FSEs, the majority were CD4+ and CD25+. These T cells demonstrated augmented expression of markers associated with regulatory T cell, Th1, or Th17 activity, which coincided with significant heightened cytokine production, including IFN-γ, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IP-10 (CXCL10), and TGF-β1. Burn injury did not impact the studied effector T cell subsets or cytokine levels.

Discussion

Collectively, this study represents a significant advancement in the development of an immunocompetent human skin model, specifically tailored for investigating burn-induced innate or adaptive immune reactions at the site of burn injury.

The immunomodulation role of Th17 and Treg in renal transplantation

Kidney transplantation (KT) is an ultimate treatment of end-stage chronic kidney disease, which can meet a lot of complications induced by immune system. With under-controlled immunosuppression, the patient will obtain a good prognosis. Otherwise, allograft disfunction will cause severe organ failure and even immune collapse. Acute or chronic allograft dysfunction after KT is related to Th17, Treg, and Th17/Treg to a certain extent. Elevated Th17 levels may lead to acute rejection or chronic allograft dysfunction. Treg mainly plays a protective role on allografts by regulating immune response. The imbalance of the two may further aggravate the balance of immune response and damage the allograft. Controlling Th17 level, improving Treg function and level, and adjusting Th17/Treg ratio may have positive effects on longer allograft survival and better prognosis of receptors.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 exaggerates multiple organ injury, inflammation, and immune cell imbalance by activating the NF-κB pathway in sepsis

Objective

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) modulates the inflammatory immune response and organ dysfunction, which are closely implicated in sepsis pathogenesis and progression. This study aimed to explore the role of MALT1 in sepsis-induced organ injury, immune cell dysregulation, and inflammatory storms.

Methods

Septic mice were constructed by intraperitoneal injection of lipopolysaccharide, followed by overexpression or knockdown of MALT1 by tail vein injection of the corresponding lentivirus. Mouse naïve CD4⁺ T cells and bone marrow-derived macrophages were treated with MALT1 overexpression/knockdown lentivirus plus lipopolysaccharide.

Results

In the lungs, livers, and kidneys of septic mice, MALT1 overexpression exaggerated their injuries, as shown by hematoxylin and eosin staining (all p < 0.05), elevated cell apoptosis, as reflected by the TUNEL assay and cleaved caspase-3 expression (p < 0.05 in the lungs and kidneys), and promoted macrophage infiltration, as illustrated by CD68 immunofluorescence (p < 0.05 in the lungs and kidneys). Meanwhile, in the blood, MALT1 overexpression reduced T-helper (Th)1/Th2 cells, increased Th17/regulatory T-cell ratios (both p < 0.05), promoted systematic inflammation, as revealed by tumor necrosis factor-α, interleukin-6, interleukin-1β, and C-reactive protein (all p < 0.05), elevated oxidative stress, as shown by nitric oxide (p < 0.05), superoxide dismutase, and malondialdehyde (p < 0.05), and enhanced liver and kidney dysfunction, as revealed by an automatic animal biochemistry analyzer (all p < 0.05 except for aspartate aminotransferase). However, MALT1 knockdown exerted the opposite effect as MALT1 overexpression. Ex vivo experiments revealed that MALT1 overexpression promoted the polarization of M1 macrophages and naïve CD4⁺ T cells toward Th2 and Th17 cells (all p < 0.05), while MALT1 knockdown attenuated these effects (all p < 0.05). Mechanistically, MALT1 positively regulated the nuclear factor-κB (NF-κB) pathway both in vivo and ex vivo (p < 0.05).

Conclusion

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 amplifies multiple organ injury, inflammation, oxidative stress, and imbalance of macrophages and CD4⁺ T cells by activating the NF-κB pathway in sepsis.

IL2RB affects Th1/Th2 and Th17 responses of peripheral blood mononuclear cells from septic patients

BACKGROUND

Immune dysfunction is a common and serious complication of sepsis. This study finds key genes linked to immunity in sepsis.

METHODS

The "Limma package" was used to analyze GSE154918 datasets for differentially expressed genes. The differentially expressed genes were then enriched for Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and interleukin 2 receptor subunit Beta (IL2RB) protein coding gene was chosen for investigation. IL2RB expression in peripheral blood mononuclear cells (PBMC) was assessed by polymerase chain reaction. White blood cells of septic patients and healthy controls were collected from hospitals and linked with acute physiology and chronic health evaluation (APACHE) II, sequential organ failure assessment (SOFA), C-reactive protein (CRP), and procalcitonin (PCT) of septic patients using Pearson's correlation analysis. PBMC cells were transfected with IL2RB, and the effect of transfection was observed on cellular interferon gamma (IFN-γ), interleukin (IL)-12, IL-4, IL-10, and IL-17A.

RESULTS

A total of 686 differential genes, comprising 446 upregulated and 240 down regulated genes, were identified. The enrichment of KEGG pathway revealed that the majority of differential genes were enriched in the T helper (Th1)/Th2 cell and Th17 cell differentiation pathways. In patients with sepsis, correlation analysis revealed a negative correlation between IL2RB and APACHE II score, SOFA score, CRP, and PCT. IFN-γ and IL-12 levels were elevated in PBMC of septic patients after IL2RB transfection, but IL-4, IL-10, and IL-17A levels were lowered.

CONCLUSION

Sepsis-induced immunological dysfunction is improved by IL2RB, which also balances Th1/Th2 responses and prevents Th17 activation. © 2023 Codon Publications. Published by Codon Publications.

Modern aspects of burn injury immunopathogenesis and immuno-biochemical markers of wound healing (review of literature)

Burns are one of the most common traumatic injuries in the world, representing a global public health problem. Major burns (severe burn injury or burn disease) are one of the most life-threatening injuries. There is a great need to identify and monitor the development of complications (sepsis and septic shock, coagulopathy and DIC) in burned patients. The basis of the pathogenesis of burn injury, as well as any general pathological process, is an inflammatory reaction, ultimately aimed at restoring the structure and function of the damaged tissue. A feature of the inflammatory reaction in burn injury is the scale of alteration of the skin and mucous membranes. The review presents the main aspects of the burn injuries immunopathogenesis and the features of post-burn immune dysfunction, manifested by disorders in the innate and adaptive immunity systems. Attention is focused on the role in the immunopathogenesis of developing systemic and local disorders in burn injury. Also the role are discussed of a minor subpopulations of lymphocytes (Treg-, Th-17-, γδT-cells) in the immunopathogenesis and in the bacterial infection protection. The characteristics of the main immuno-biochemical markers of burn injury (cytokines and growth factors, nitric oxide, matrix metalloproteases, bacteria concentration levels) are present. The prognostic role of these biomarkers in assessing of the severity degree of patients with burn injury and wound healing processes is shown. The review has been compiled using references from major databases such as RSCI, Web of Science, PubMed, Scopus and Google Scholar (up to march 2022). After obtaining all reports from database, the papers were carefully analyzed in order to find data related to the topic of this review (60 references).

Identification of Important Modules and Biomarkers That Are Related to Immune Infiltration Cells in Severe Burns Based on Weighted Gene Co-Expression Network Analysis

Background: Immunosuppression is an important trigger for infection and a significant cause of death in patients with severe burns. Nevertheless, the prognostic value of immune-related genes remains unclear. This study aimed to identify the biomarkers related to immunosuppression in severe burns. Methods: The gene expression profile and clinical data of 185 burn and 75 healthy samples were obtained from the GEO database. Immune infiltration analysis and gene set variation analysis were utilized to identify the disorder of circulating immune cells. A weighted gene co-expression network analysis (WGCNA) was carried out to select immune-related gene modules. Enrichment analysis and protein-protein interaction (PPI) network were performed to select hub genes. Next, LASSO and logistic regression were utilized to construct the hazard regression model with a survival state. Finally, we investigated the correlation between high- and low-risk patients in total burn surface area (TBSA), age, and inhalation injury. Results: Gene set variation analysis (GSVA) and immune infiltration analysis showed that neutrophils increased and T cells decreased in severe burns. In WGCNA, four modular differently expressed in burns and controls were related to immune cells. Based on PPI and enrichment analysis, 210 immune-related genes were identified, mainly involved in T-cell inhibition and neutrophil activation. In LASSO and logistic regression, we screened out key genes, including LCK, SKAP1 and GZMB, and LY9. In the ROC analysis, the area under the curve (AUC) of key genes was 0.945, indicating that the key genes had excellent diagnostic value. Finally, we discovered that the key genes were related to T cells, and the regression model performed well when accompanied by TBSA and age. Conclusion: We identified LCK, SKAP1, GZMB, and LY9 as good prognostic biomarkers that may play a role in post-burn immunosuppression against T-cell dysfunction and as potential immunotherapeutic targets for transformed T-cell dysfunction.

Measures of Adaptive Immune Function Predict the Risk of Nosocomial Infection in Pediatric Burn Patients

Thermal injury results in changes in the inflammatory and innate immune response of pediatric patients. Plasma cytokines, cellular profiles, and reduction in innate immune function following burn injury has also been correlated to adverse outcomes (e.g., mortality and infectious complications). Changes in adaptive immune function following thermal injury are not as well characterized. Our goal was to better understand if adaptive immune dysfunction occurs early after pediatric thermal injury and is a risk factor for nosocomial infections (NI). A prospective, longitudinal immune function observational study was performed at a single ABA-verified pediatric burn center. Eighty burn patients were enrolled with 20 developing a NI, defined using CDC criteria. We collected whole blood samples from pediatric burn patients within the first 72 hours from injury and between days 4-7, where applicable to analyze adaptive immune function. We compared immune function between burn patients who went on to develop NI and those that did not. Within the first 72 hours of injury, burn patients who developed NI had significantly lower absolute CD4+ lymphocyte counts and whole blood ex vivo phytohemagglutinin (PHA)-induced IFNγ and IL-10 production capacity compared to those that did not develop infection. Further analysis using receiver operating characteristic curve revealed that PHA-induced IL-10 production capacity had the highest area under the curve. Our data demonstrates early adaptive immune suppression occurs following pediatric thermal injury and PHA-induced IL-10 production capacity appears to be a predictor for the development of NI.

Identifying changes in immune cells and constructing prognostic models using immune-related genes in post-burn immunosuppression

BACKGROUND

Burn patients are prone to infection as well as immunosuppression, which is a significant cause of death. Currently, there is a lack of prognostic biomarkers for immunosuppression in burn patients. This study was conducted to identify immune-related genes that are prognosis biomarkers in post-burn immunosuppression and potential targets for immunotherapy.

METHODS

We downloaded the gene expression profiles and clinical data of 213 burn patients and 79 healthy samples from the Gene Expression Omnibus (GEO) database. Immune infiltration analysis was used to identify the proportion of circulating immune cells. Functional enrichment analyses were carried out to identify immune-related genes that were used to build miRNA-mRNA networks to screen key genes. Next, we carried out correlation analysis between immune cells and key genes that were then used to construct logistic regression models in GSE77791 and were validated in GSE19743. Finally, we determined the expression of key genes in burn patients using quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

A total of 745 differently expressed genes were screened out: 299 were up-regulated and 446 were down-regulated. The number of Th-cells (CD4+) decreased while neutrophils increased in burn patients. The enrichment analysis showed that down-regulated genes were enriched in the T-cell activation pathway, while up-regulated genes were enriched in neutrophil activation response in burn patients. We screened out key genes (NFATC2, RORA, and CAMK4) that could be regulated by miRNA. The expression of key genes was related to the proportion of Th-cells (CD4+) and survival, and was an excellent predictor of prognosis in burns with an area under the curve (AUC) value of 0.945. Finally, we determined that NFATC2, RORA, and CAMK4 were down-regulated in burn patients.

CONCLUSION

We found that NFATC2, RORA, and CAMK4 were likely prognostic biomarkers in post-burn immunosuppression and potential immunotherapeutic targets to convert Th-cell dysfunction.

Innate Immune System Response to Burn Damage-Focus on Cytokine Alteration

In the literature, burns are understood as traumatic events accompanied by increased morbidity and mortality among affected patients. Their characteristic feature is the formation of swelling and redness at the site of the burn, which indicates the development of inflammation. This reaction is not only important in the healing process of wounds but is also responsible for stimulating the patient’s innate immune system. As a result of the loss of the protective ability of the epidermis, microbes which include bacteria, fungi, and viruses have easier access to the system, which can result in infections. However, the patient is still able to overcome the infections that occur through a cascade of cytokines and growth factors stimulated by inflammation. Long-term inflammation also has negative consequences for the body, which may result in multi-organ failure or lead to fibrosis and scarring of the skin. The innate immune response to burns is not only immediate, but also severe and prolonged, and some people with burn shock may also experience immunosuppression accompanied by an increased susceptibility to fatal infections. This immunosuppression includes apoptosis-induced lymphopenia, decreased interleukin 2 (IL-2) secretion, neutrophil storm, impaired phagocytosis, and decreased monocyte human leukocyte antigen-DR. This is why it is important to understand how the immune system works in people with burns and during infections of wounds by microorganisms. The aim of this study was to characterize the molecular pathways of cell signaling of the immune system of people affected by burns, taking into account the role of microbial infections.

Transcriptome Analysis of Jujube (Ziziphus jujuba Mill.) Response to Heat Stress

Heat stress (HS) is a common stress influencing the growth and reproduction of plant species. Jujube (Ziziphus jujuba Mill.) is an economically important tree with strong abiotic stress resistance, but the molecular mechanism of its response to HS remains elusive. In this study, we subjected seedlings of Z. jujuba cultivar “Hqing1-HR” to HS (45°C) for 0, 1, 3, 5, and 7 days, respectively, and collected the leaf samples (HR0, HR1, HR3, HR5, and HR7) accordingly. Fifteen cDNA libraries from leaves were constructed for transcriptomics assays. RNA sequencing and transcriptomics identified 1,642, 4,080, 5,160, and 2,119 differentially expressed genes (DEGs) in comparisons of HR1 vs. HR0, HR3 vs. HR0, HR5 vs. HR0, and HR7 vs. HR0, respectively. Gene ontology analyses of the DEGs from these comparisons revealed enrichment in a series of biological processes involved in stress responses, photosynthesis, and metabolism, suggesting that lowering or upregulating expression of these genes might play important roles in the response to HS. This study contributed to our understanding of the molecular mechanism of jujube response to HS and will be beneficial for developing jujube cultivars with improved heat resistance.

A Novel Single Cell RNA-seq Analysis of Non-Myeloid Circulating Cells in Late Sepsis

Background

With the successful implementation of the Surviving Sepsis Campaign guidelines, post-sepsis in-hospital mortality to sepsis continues to decrease. Those who acutely survive surgical sepsis will either rapidly recover or develop a chronic critical illness (CCI). CCI is associated with adverse long-term outcomes and 1-year mortality. Although the pathobiology of CCI remains undefined, emerging evidence suggests a post-sepsis state of pathologic myeloid activation, inducing suboptimal lymphopoiesis and erythropoiesis, as well as downstream leukocyte dysfunction. Our goal was to use single-cell RNA sequencing (scRNA-seq) to perform a detailed transcriptomic analysis of lymphoid-derived leukocytes to better understand the pathology of late sepsis.

Methods

A mixture of whole blood myeloid-enriched and Ficoll-enriched peripheral blood mononuclear cells from four late septic patients (post-sepsis day 14-21) and five healthy subjects underwent Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq).

Results

We identified unique transcriptomic patterns for multiple circulating immune cell subtypes, including B- and CD4⁺, CD8⁺, activated CD4⁺ and activated CD8⁺ T-lymphocytes, as well as natural killer (NK), NKT, and plasmacytoid dendritic cells in late sepsis patients. Analysis demonstrated that the circulating lymphoid cells maintained a transcriptome reflecting immunosuppression and low-grade inflammation. We also identified transcriptomic differences between patients with bacterial versus fungal sepsis, such as greater expression of cytotoxic genes among CD8⁺ T-lymphocytes in late bacterial sepsis.

Conclusion

Circulating non-myeloid cells display a unique transcriptomic pattern late after sepsis. Non-myeloid leukocytes in particular reveal a host endotype of inflammation, immunosuppression, and dysfunction, suggesting a role for precision medicine-guided immunomodulatory therapy.

Neuronal-Activated ILC2s Promote IL-17A Production in Lung γδ T Cells During Sepsis

Background

Studies have revealed important roles for IL-17A in the development of acute lung injury (ALI) following sepsis. However, the mechanism underlying the regulation of lung IL-17A remains to be fully addressed. Recent studies suggested the effect of neuromedin U (NMU) on immune cell activation and the role of group 2 innate lymphoid cells (ILC2s) in the modulation of IL-17A production. We aimed to gain in-depth insight into the mechanism underlying sepsis-induced lung IL-17A production, particularly, the role of NMU in mediating neuronal regulation of ILC2s and IL-17A-producing γδ T cells activation in sepsis.

Methods

Wild type mice were subjected to cecal ligation and puncture (CLP) to induce sepsis with or without intraperitoneal injection of NMU. The levels of ILC2s, γδ T cells, IL-17A, NMU and NMU receptor 1 (NMUR1) in the lung were then measured. In order to determine the role of NMU signaling in ILC2 activation and the role of ILC2-released IL-9 in ILC2-γδ T cell interaction, ILC2s were sorted, and the genes of nmur1 and il9 in the ILC2s were knocked down using CRISPR/Cas9. The genetically manipulated ILC2s were then co-cultured with lung γδ T cells, and the levels of IL-17A from co-culture systems were measured.

Results

In septic mice, the levels of NMU, IL-17A, ILC2s, and IL-17A-producing γδ T cells in the lung are significantly increased, and the expression of NMUR1 in ILC2s is increased as well. Exogenous NMU further augments these increases. The main source of IL-17A in response to CLP is γδ T cells, and lung nmur1 is specifically expressed in ILC2s. In vitro co-culture of ILC2s and γδ T cells leads to increased number of γδ T cells and higher production of IL-17A from γδ T cells, and these alterations are further augmented by septic treatment and exogenous NMU. Genetic knockdown of nmur1 or il9 in ILC2s attenuated the upregulation of γδ T cells and IL-17A production.

Conclusion

In sepsis, NMU acting through NMUR1 in lung ILC2s initiates the ILC2 activation, which, in turn, promote IL-17A-producing γδ T cell expansion and secretion of IL-17A. ILC2-derived IL-9 plays an important role in mediating γδ T cell expansion and IL-17A production. This study explores a new mechanism underlying neuronal regulation of innate immunity in sepsis.

Th17, rather than Th1 cell proportion, is closely correlated with elevated disease severity, higher inflammation level, and worse prognosis in sepsis patients

Objective

The current study aimed to investigate the prognostic value of T helper (Th) 1 and Th17 proportions in sepsis patients.

Methods

Th1 and Th17 cells in blood CD4⁺ T cells were detected by flow cytometry in 210 sepsis patients and 100 healthy controls (HCs). Besides, serum interferon‐γ (IFN‐γ), tumor necrosis factor‐α (TNF‐α), and interleukin‐17 (IL‐17) levels in the enrolled sepsis patients were determined with enzyme‐linked immunosorbent assay.

Results

Compared with HCs, Th1 and Th17 proportions were elevated in sepsis patients (both p < .001). Meanwhile, Th1 proportion was strongly correlated with IFN‐γ (p < .001, r = .484) but weakly correlated with TNF‐α (p = .024, r = .156) and IL‐17 (p = .002, r = .212), while Th17 proportion showed faint correlation with IFN‐γ (p = .015, r = .168), but strong correlations with TNF‐α (p < .001, r = .602) and IL‐17 (p < .001, r = .498) in sepsis patients. Besides, Th1 proportion was weakly associated with APACHE II score (p = .030, r = .150), but Th17 proportion was closely associated with APACHE II score (p < .001, r = .322) and SOFA score (p < .001, r = .337) in sepsis patients. Regarding their prognostic value, Th1 proportion (p = .042) was slightly, while Th17 proportion (p < .001) was dramatically, increased in septic deaths compared with survivors, and Th17 possessed good predictive value for 28‐day mortality risk (AUC: 0.748, 95% CI: 0.659–0.836).

Conclusion

Th1 and Th17 proportions are elevated in sepsis patients compared with HCs, and Th17 proportion is correlated with increased disease severity, higher inflammation level, and worse prognosis in sepsis patients.

The pathogenesis and diagnosis of sepsis post burn injury

Burn is an under-appreciated trauma that is associated with unacceptably high morbidity and mortality. Although the survival rate after devastating burn injuries has continued to increase in previous decades due to medical advances in burn wound care, nutritional and fluid resuscitation and improved infection control practices, there are still large numbers of patients at a high risk of death. One of the most common complications of burn is sepsis, which is defined as “severe organ dysfunction attributed to host's disordered response to infection” and is the primary cause of death in burn patients. Indeed, burn injuries are accompanied by a series of events that lead to sepsis and multiple organ dysfunction syndrome, such as a hypovolaemic state, immune and inflammatory responses and metabolic changes. Therefore, clear diagnostic criteria and predictive biomarkers are especially important in the prevention and treatment of sepsis and septic shock. In this review, we focus on the pathogenesis of burn wound infection and the post-burn events leading to sepsis. Moreover, the clinical and promising biomarkers of burn sepsis will also be summarized.

Persistent Systemic Inflammation in Patients With Severe Burn Injury Is Accompanied by Influx of Immature Neutrophils and Shifts in T Cell Subsets and Cytokine Profiles

Severe burn injury causes local and systemic immune responses that can persist up to months, and can lead to systemic inflammatory response syndrome, organ damage and long-term sequalae such as hypertrophic scarring. To prevent these pathological conditions, a better understanding of the underlying mechanisms is essential. In this longitudinal study, we analyzed the temporal peripheral blood immune profile of 20 burn wound patients admitted to the intensive care by flow cytometry and secretome profiling, and compared this to data from 20 healthy subjects. The patient cohort showed signs of systemic inflammation and persistently high levels of pro-inflammatory soluble mediators, such as IL-6, IL-8, MCP-1, MIP-1β, and MIP-3α, were measured. Using both unsupervised and supervised flow cytometry techniques, we observed a continuous release of neutrophils and monocytes into the blood for at least 39 days. Increased numbers of immature neutrophils were present in peripheral blood in the first three weeks after injury (0.1–2.8 × 10⁶/ml after burn vs. 5 × 10³/ml in healthy controls). Total lymphocyte numbers did not increase, but numbers of effector T cells as well as regulatory T cells were increased from the second week onward. Within the CD4⁺ T cell population, elevated numbers of CCR4⁺CCR6^- and CCR4⁺CCR6⁺ cells were found. Altogether, these data reveal that severe burn injury induced a persistent innate inflammatory response, including a release of immature neutrophils, and shifts in the T cell composition toward an overall more pro-inflammatory phenotype, thereby continuing systemic inflammation and increasing the risk of secondary complications.

Type 17 Immune Response Facilitates Progression of Inflammation and Correlates with Cognition in Stable Schizophrenia

Dysregulation of the type 17 immune pathway has already been considered in schizophrenia and we previously measured decreased sera values of interleukin (IL)-17 in early stages. We further explored the possible correlation of IL-17 systemic levels with proinflammatory cytokines and cognitive scores and additionally analyzed the percentage of IL-17 producing lymphocytes in peripheral blood of patients with stable schizophrenia. We included 27 patients diagnosed with schizophrenia (F20), after a three-month stable depot antipsychotic therapy (risperidone or paliperidone) and 18 healthy control subjects. Positive and Negative Syndrome Scale of Schizophrenia and the Montreal-Cognitive Assessment (MoCA) were conducted. Sera concentrations of IL-17, IL-6, tumor necrosis factor alpha (TNF-α) and soluble ST2 receptor (sST2) were measured. Flow cytometry and Natural Killer (NK) and T cell analyses were done in 10 patients and 10 healthy controls. Moderate positive correlation was established between IL-17 and TNF-α (r = 0.640; p = 0.001), IL-17 and IL-6 (r = 0.514; p = 0.006), IL-17 and sST2 (r = 0.394; p = 0.042). Furthermore, a positive correlation between the serum levels of IL-17 and MoCA scores was observed, especially with visuospatial and executive functioning, as well as language functioning and delayed recall (p < 0.05). Significantly higher percentage of IL-17 producing CD56⁺ NK cells was measured in peripheral blood of patients with schizophrenia in remission vs. healthy individuals (p = 0.001). The percentage of CD4⁺ T cells and CD4⁺ T cells that produce IL-17 was significantly increased in patients (p = 0.001). This study revealed the involvement of innate type 17 immune response in the progression of inflammation and this could be related to cognitive functioning in stable schizophrenia.

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.

Th17/Treg imbalance in patients with severe acute pancreatitis: Attenuated by high-volume hemofiltration treatment

BACKGROUND

To investigate the effect of high-volume hemofiltration (HVHF) on Th17/Treg imbalance in patients with severe acute pancreatitis (SAP).

METHODS

Forty-two patients with SAP were randomly received 24 hours of continuous HVHF (n = 21) or without HVHF (n = 21). At day 28, all 42 patients were divided into survival group (n = 32) and non-survival group (n = 10). Venous blood samples collected at 0, 6, 12, and 24 hours during HVHF treatment (or equivalent time in non-HVHF group) were assessed by flow cytometry to detect Th17 and Treg cells. Concentrations of IL-6, IL-17, IL-10, and TGF-β1 were detected by enzyme-linked immunosorbent assay.

RESULTS

Th17%, Treg%, Th17/Treg, and levels of related cytokines were significantly higher in SAP patients than healthy controls (P < .05), and these changes were more pronounced in SAP patients with multiple organ failure than those with single organ failure (P < .05). After HVHF treatment, Th17%, Treg%, Th17/Treg, IL-6, IL-17, and IL-10 significantly reduced (P < .05), while there were no significant changes in non-HVHF group (P > .05). In addition, acute physiology and chronic health evaluation II and sequential organ failure assessment scores decreased markedly after HVHF treatment. Baselines of Th17%, Treg%, Th17/Treg, and related cytokines were significantly higher in non-survival group than survival group. Both acute physiology and chronic health evaluation I score and IL-6 level were positively correlated with Th17% before and after HVHF treatment (P < .01).

CONCLUSIONS

Th17/Treg imbalance is present in SAP and may be correlated with its severity and prognosis. HVHF effectively attenuates the Th17/Treg imbalance in SAP patients. The beneficial effect of HVHF on Th17/Treg imbalance is possibly associated with removing excess inflammatory mediators.

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.

The activation of IL-17 signaling pathway promotes pyroptosis in pneumonia-induced sepsis

Background

Pyroptosis is closely relevant to sepsis. However, the molecular mechanisms of pyroptosis in pneumonia-induced sepsis are still not fully understood. Thus, this study aimed to find the specific molecular pathways associated with pyroptosis and explore their relationship in pneumonia-induced sepsis.

Methods

First, significant signaling pathways related to pneumonia-induced sepsis were screened by bioinformatics analysis based on GSE48080. The peripheral blood samples from patients with pneumonia-induced sepsis and healthy subjects were collected. Pneumonia-induced sepsis rat models were also established. Then, inflammatory response, pyroptosis, and regulatory T cells (Tregs)/T-helper 17 (Th17), Th1/Th2, and M1/M2 cell ratios in pneumonia-induced sepsis were evaluated.

Results

IL-17 signaling pathway was significantly related to pneumonia-induced sepsis by bioinformatics analysis. Compared with healthy groups, the higher of Th17/Treg, Th1/Th2 and M1/M2 cell radios in the patients and sepsis rat model indicated that pneumonia-induced sepsis caused a severe inflammatory response. This result was confirmed by higher levels of pro-inflammatory factors (IL-6, TNF-α, IL-1β, and IL-18) and an inflammation indicator (LDH), as well as pyroptosis occurrence in sepsis. Additionally, the up-regulation of key molecules (HMGB1, RAGE, IL-17A, TRAF6 and NK-κB) in the IL-17 signaling pathway suggested the IL-17 pathway was activated. Moreover, the release of IL-1β and IL-18 and the levels of the molecules (NLRP3, NLRC4, Cleaved caspase-1, and Cleaved GSDMD) associated with caspase-1-dependent pyroptosis were up-regulated in pneumonia-induced sepsis.

Conclusions

As NK-κB activation can promote the development of caspase-1-dependent pyroptosis, these findings suggested that the activation of the IL-17 signaling pathway could promote pyroptosis in pneumonia-induced sepsis.

Exploring the complex role of chemokines and chemoattractants in vivo on leukocyte dynamics

Chemotaxis is fundamental for leukocyte migration in immunity and inflammation and contributes to the pathogenesis of many human diseases. Although chemokines and various other chemoattractants were initially appreciated as important mediators of acute inflammation, in the past years they have emerged as critical mediators of cell migration during immune surveillance, organ development, and cancer progression. Such advances in our knowledge in chemokine biology have paved the way for the development of specific pharmacological targets with great therapeutic potential. Chemoattractants may belong to different classes, including a complex chemokine system of approximately 50 endogenous molecules that bind to G protein-coupled receptors, which are expressed by a wide variety of cell types. Also, an unknown number of other chemoattractants may be generated by pathogens and damaged/dead cells. Therefore, blocking chemotaxis without causing side effects is an extremely challenging task. In this review, we focus on recent advances in understanding how the chemokine system orchestrates immune cell migration and positioning at the whole organ level in homeostasis, inflammation, and infection.

Increased oxidative phosphorylation in lymphocytes does not atone for decreased cell numbers after burn injury

The acute systemic inflammatory response syndrome (SIRS) and multiorgan dysfunction (MOD) that occur in large burn injuries may be attributed, in part, to immunosuppressive responses such as decreased lymphocytes. However, the mitochondrial bioenergetics of lymphocytes after severe burn injury are poorly understood. The purpose of this study was to examine mitochondrial function of lymphocytes following severe burns in a swine model. Anesthetized Yorkshire swine (n = 17) sustained 40% total body surface area full-thickness contact burns. Blood was collected at pre-injury (Baseline; BL) and at 24 and 48 h after injury for complete blood cell analysis, flow cytometry, cytokine analysis, and ficoll separation of intact lymphocytes for high-resolution mitochondrial respirometry analysis. While neutrophil numbers increased, a concomitant decrease was found in lymphocytes (P < 0.001) after burn injury, which was not specific to CD4⁺ or CD8⁺ lymphocytes. No changes in immune cell population were observed from 24 h to 48 h post-injury. IL 12-23 decreased while a transient increase in IL 4 was found from BL to 24h (P < 0.05). CRP progressively increased from BL to 24h (P < 0.05) and 48h (P < 0.001) post-injury. Routine and maximal mitochondrial respiration progressively increased from BL to 24h (P < 0.05) and 48 h post-injury (P < 0.001). No changes were found in leak respiration or residual oxygen consumption. When considering the reduction in lymphocyte number, the total peripheral lymphocyte bioenergetics per volume of blood significantly decreased from BL to 24h and 48h (P < 0.05). For the first time, we were able to measure mitochondrial activity in intact lymphocyte mitochondria through high-resolution respirometry in a severely burned swine model. Our data showed that the non-specific reduction in peripheral T cells after injury was larger than the increased mitochondrial activity in those cells, which may be a compensatory mechanism for the total reduction in lymphocytes. Additional studies in the metabolic activation of T cell subpopulations may provide diagnostic or therapeutic targets after severe burn injury.

Mechanism of pulmonary immunosuppression: extrapulmonary burn injury suppresses bacterial endotoxin-induced pulmonary neutrophil recruitment and neutrophil extracellular trap (NET) formation

Pulmonary immunosuppression often occurs after burn injury (BI). However, the reasons for BI-induced pulmonary immunosuppression are not clearly understood. Neutrophil recruitment and neutrophil extracellular trap (NET) formation (NETosis) are important components of a robust pulmonary immune response, and we hypothesized that pulmonary inflammation and NETosis are defective after BI. To test this hypothesis, we established a mouse model with intranasal LPS instillation in the presence or absence of BI (15% of body surface burn) and determined the degree of immune cell infiltration, NETosis, and the cytokine levels in the airways and blood on d 2. Presence of LPS recruited monocytes and large numbers of neutrophils to the airways and induced NETosis (citrullinated histone H3, DNA, myeloperoxidase). By contrast, BI significantly reduced LPS-mediated leukocyte recruitment and NETosis. This BI-induced immunosuppression is attributable to the reduction of chemokine (C-C motif) ligand (CCL) 2 (monocyte chemoattractant protein 1) and CCL3 (macrophage inflammatory protein 1α). BI also suppressed LPS-induced increase in IL-17A, IL-17C, and IL-17E/IL-25 levels in the airways. Therefore, BI-mediated reduction in leukocyte recruitment and NETosis in the lungs are attributable to these cytokines. Regulating the levels of some of these key cytokines represents a potential therapeutic option for mitigating BI-mediated pulmonary immunosuppression.-Sakuma, M., Khan, M. A. S., Yasuhara, S., Martyn, J. A., Palaniyar, N. Mechanism of pulmonary immunosuppression: extrapulmonary burn injury suppresses bacterial endotoxin-induced pulmonary neutrophil recruitment and neutrophil extracellular trap (NET) formation.

A conceptual time window-based model for the early stratification of trauma patients

Progress in the testing of therapies targeting the immune response following trauma, a leading cause of morbidity and mortality worldwide, has been slow. We propose that the design of interventional trials in trauma would benefit from a scheme or platform that could support the identification and implementation of prognostic strategies for patient stratification. Here, we propose a stratification scheme based on defined time periods or windows following the traumatic event. This 'time-window' model allows for the incorporation of prognostic variables ranging from circulating biomarkers and clinical data to patient-specific information such as gene variants to predict adverse short- or long-term outcomes. A number of circulating biomarkers, including cell injury markers and damage-associated molecular patterns (DAMPs), and inflammatory mediators have been shown to correlate with adverse outcomes after trauma. Likewise, several single nucleotide polymorphisms (SNPs) associate with complications or death in trauma patients. This review summarizes the status of our understanding of the prognostic value of these classes of variables in predicting outcomes in trauma patients. Strategies for the incorporation of these prognostic variables into schemes designed to stratify trauma patients, such as our time-window model, are also discussed.

A multiplex analysis of sepsis mediators during human septic shock: a preliminary study on myocardial depression and organ failures

BACKGROUND

The mechanisms of organ failure during sepsis are not fully understood. The hypothesis of circulating factors has been suggested to explain septic myocardial dysfunction. We explored the biological coherence of a large panel of sepsis mediators and their clinical relevance in septic myocardial dysfunction and organ failures during human septic shock.

METHODS

Plasma concentrations of 24 mediators were assessed on the first day of septic shock using a multi-analyte cytokine kit. Septic myocardial dysfunction and organ failures were assessed using left ventricle ejection fraction (LVEF) and the Sequential Organ Failure Assessment score, respectively.

RESULTS

Seventy-four patients with septic shock (and without immunosuppression or chronic heart failure) were prospectively included. Twenty-four patients (32%) had septic myocardial dysfunction (as defined by LVEF < 45%) and 30 (41%) died in ICU. Hierarchical clustering identified three main clusters of sepsis mediators, which were clinically meaningful. One cluster involved inflammatory cytokines of innate immunity, most of which were associated with septic myocardial dysfunction, organ failures and death; inflammatory cytokines associated with septic myocardial dysfunction had an additive effect. Another cluster involving adaptive immunity and repair (with IL-17/IFN pathway and VEGF) correlated tightly with a surrogate of early sepsis resolution (lactate clearance) and ICU survival.

CONCLUSIONS

In this preliminary study, we identified a cluster of cytokines involved in innate inflammatory response associated with septic myocardial dysfunction and organ failures, whereas the IL-17/IFN pathway was associated with a faster sepsis resolution and a better survival.

Mode of Action of Aspirin in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic and debilitating autoimmune disorder of the central nervous system in which the autoimmune T cells destroy myelin, thus causing lesion, damage, and neuronal dysfunction. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS that is particularly useful for testing new therapeutic approaches against MS. Aspirin (acetyl salicylic acid) is one of the oldest and widely used medicines in the world, and recently it has been shown that low-dose aspirin is capable of suppressing the disease process of EAE in mice. One of the root causes of this autoimmune disease process is the decrease and/or suppression of Foxp3-expressing anti-autoimmune regulatory T cells (Tregs) and associated increase in autoimmune T-helper 1 (Th1) and Th17 cells. Aspirin upregulates Tregs and decreases Th1 and Th17 responses. Accordingly, the suppression of Tregs abrogates the protective effect of aspirin on EAE, indicating that aspirin protects EAE via Tregs. While there are several mechanisms for the maintenance of Tregs under immune insults, aspirin increases the level of interleukin-11 (IL-11), an immunomodulatory cytokine, and IL-11 alone is sufficient to protect Tregs. Being a multifunctional molecule, aspirin stimulates the activation of cAMP-response element-binding (CREB) to promote the recruitment of CREB to the IL-11 gene promoter and stimulate the transcription of IL-11 in splenocytes. Therefore, it appears that low-dose aspirin protects EAE via CREB-mediated stimulation of IL-11-Treg pathway and that aspirin may have therapeutic importance in MS.

IL-22/IL-22R1 axis is involved in myocardial injury of a mouse cecal ligation and puncture model

Myocardial depression is a hallmark of severe sepsis, which may result from a complex interplay among several factors. However, the mechanisms are still unclear yet. In this study, we aimed to explore if IL-22/IL-22R1 axis plays a role in the myocardial injury during sepsis. A cecal ligation and puncture (CLP) mouse model was established to explore the histopathological changes and to analyze the role of IL-22/IL-22R1 axis in myocardial injury during the process of sepsis. Histopathologically, myocardial injury was apparently observed with the progress of sepsis but it was improved at 72 h after surgery. On the contrary, the heart tissue in the sham group revealed injury at a limited degree at the first 8 h after surgery and then restored to normal. Results from immunohistochemical study and real-time qPCR showed that IL-22, IL-22R1 and IL-22BP had different changing trends in the progress of sepsis at both protein and mRNA levels. The expression of IL-22R1 and IL-22BP was markedly induced after CLP modeling (P < 0.01), while that of IL-22 was sharply reduced in both groups (P < 0.01). The differences in the expression of IL-22, IL-22R1 and IL-22BP between the sham and CLP groups were significant only at 72 h after surgery (P < 0.05) but not at the other time points (P > 0.05). In conclusion, IL-22/IL-22R1 axis is involved and may have a potential immunoprotective role in the cardiac tissue repair, but the immunoprotection on the cardiac tissue of CLP mice was remarkably damaged in the progress of sepsis and even in the recovery phase.

Advances in addressing full-thickness skin defects: a review of dermal and epidermal substitutes

full-thickness skin defects remain a reconstructive challenge. Novel regenerative modalities can aid in addressing these defects. A literature review of currently available dermal and epidermal regenerates was performed. The mechanism and application for each skin substitute was analyzed to provide a guide for these modalities. Available epidermal substitutes include autografts and allografts and may be cultured or noncultured. Dermal regenerate templates exist in biologic and synthetic varieties that differ in the source animal and processing. Epidermal and dermal skin substitutes are promising adjunctive tools for addressing certain soft tissue defects and have improved outcomes in reconstructive procedures. The following article provides a comprehensive review of the biologic materials available and the types of complex wounds amenable to their use.

Complement After Trauma: Suturing Innate and Adaptive Immunity

The overpowering effect of trauma on the immune system is undisputed. Severe trauma is characterized by systemic cytokine generation, activation and dysregulation of systemic inflammatory response complementopathy and coagulopathy, has been immensely instrumental in understanding the underlying mechanisms of the innate immune system during systemic inflammation. The compartmentalized functions of the innate and adaptive immune systems are being gradually recognized as an overlapping, interactive and dynamic system of responsive elements. Nonetheless the current knowledge of the complement cascade and its interaction with adaptive immune response mediators and cells, including T- and B-cells, is limited. In this review, we discuss what is known about the bridging effects of the complement system on the adaptive immune system and which unexplored areas could be crucial in understanding how the complement and adaptive immune systems interact following trauma.

Early Changes in Circulatory T Helper Type 1, 2, and 17 Cells of Patients with Out-of-Hospital Cardiac Arrest after Successful Cardiopulmonary Resuscitation

Background

Immune disorder is an important feature of patients with out-of-hospital cardiac arrest (OHCA) after the return of spontaneous circulation (ROSC). We investigated the expression of circulatory T helper type (Th) 1, Th2, and Th17 cells to explore the early immune alteration in OHCA patients after ROSC.

Methods

During July-September 2016 and March-September 2017, 65 consecutive OHCA patients with ROSC >12 h and 30 healthy individuals were enrolled in this study. Clinical and 28-day survival data were collected. Peripheral blood samples were analyzed to evaluate the expression of Th1/Th2/Th17 cells by flow cytometry from OHCA patients after ROSC on days 1 and 3 and from healthy individuals.

Results

Compared with healthy individuals, T lymphocyte counts and Th1 cell counts decreased on days 1 and 3 after ROSC (1464 [1198, 2152] vs. 779 [481, 1140] vs. 581 [324, 1118]/μl, χ² = 30.342, P < 0.001; 154 [90, 246] vs. 39 [19, 78] vs. 24 [12, 53]/μl, χ² = 42.880, P < 0.001), and Th2 and Th17 cell counts decreased on day 3 (17.0 [10.8, 24.0] vs. 9.0 [3.0, 15.5]/μl, Z = -3.228, P = 0.001; 4.7 [2.7, 9.1] vs. 2.7 [1.0, 6.5]/μl, Z = -2.294, P = 0.022). No change in CD4+/CD3+ lymphocyte ratio was seen on day 1 or day 3 (57.9 [49.4, 63.0] vs. 55.4 [46.5, 66.5] vs. 55.4 [50.2, 67.0]%, χ² = 0.171, P = 0.918). Th1/CD4+ lymphocyte ratio decreased on days 1 and 3 (19.0 [14.0, 24.9] vs. 9.3 [4.6, 13.9] vs. 9.5 [4.9, 13.6]%, χ² = 25.754, P < 0.001), and Th2/CD4+ lymphocyte ratio increased on day 1 and decreased on day 3 (1.9 [1.2, 2.5] vs. 2.5 [1.6, 4.0] vs. 1.9 [1.6, 3.8]%, χ² = 6.913, P = 0.032). Th1/Th2 cell ratio also decreased on both days (9.4 [7.3, 13.5] vs. 3.1 [1.9, 5.6] vs. 4.2 [2.8, 5.9], χ² = 44.262, P < 0.001). Despite an upward trend in the median of Th17/CD4+ lymphocyte ratio in OHCA patients, there was no significant difference compared with healthy individuals (0.9 [0.4, 1.2] vs. 0.7 [0.4, 1.2] vs. 0.6 [0.3, 1.0]%, χ² = 2.620, P = 0.270). The dynamic expression of Th1/Th2/Th17 cells on days 1 and 3 were simultaneously analyzed in 28/53 OHCA patients who survived >3 days; patients were divided into survivors (n = 10) and nonsurvivors (n = 18) based on 28-day survival. No significant differences in Th1/Th2/Th17 cell counts, ratios in CD4+ lymphocytes, and Th1/Th2 cell ratio were seen between survivors and nonsurvivors on both days (all P > 0.05). There was no difference over time in both survivors and nonsurvivors (all P > 0.05).

Conclusion

Downregulated T lymphocyte counts, including Th1/Th2/Th17 subsets and Th1/Th2 cell ratio imbalance, occur in the early period after ROSC, that may be involved in immune dysfunction in OHCA patients.

T cells and their immunometabolism: A novel way to understanding sepsis immunopathogenesis and future therapeutics

Sepsis has always been considered as a big challenge for pharmaceutical companies in terms of discovering and designing new therapeutics. The pathogenesis of sepsis involves aberrant activation of innate immune cells (i.e. macrophages, neutrophils etc.) at early stages. However, a stage of immunosuppression is also observed during sepsis even in the patients who have recovered from it. This stage of immunosuppression is observed due to the loss of conventional (i.e. CD4⁺, CD8⁺) T cells, Th17 cells and an upregulation of regulatory T cells (Tregs). This process also impacts metabolic processes controlling immune cell metabolism called immunometabolism. The present review is focused on the T cell-mediated immune response, their immunometabolism and targeting T cell immunometabolism during sepsis as future therapeutic approach. The first part of the manuscripts describes an impact of sepsis on conventional T cells, Th17 cells and Tregs along with their impact on sepsis. The subsequent section further describes the immunometabolism of these cells (CD4⁺, CD8⁺, Th17, and Tregs) under normal conditions and during sepsis-induced immunosuppression. The article ends with the therapeutic targeting of T cell immunometabolism (both conventional T cells and Tregs) during sepsis as a future immunomodulatory approach for its management.

Application of Monte Carlo cross-validation to identify pathway cross-talk in neonatal sepsis

To explore genetic pathway cross-talk in neonates with sepsis, an integrated approach was used in this paper. To explore the potential relationships between differently expressed genes between normal uninfected neonates and neonates with sepsis and pathways, genetic profiling and biologic signaling pathway were first integrated. For different pathways, the score was obtained based upon the genetic expression by quantitatively analyzing the pathway cross-talk. The paired pathways with high cross-talk were identified by random forest classification. The purpose of the work was to find the best pairs of pathways able to discriminate sepsis samples versus normal samples. The results found 10 pairs of pathways, which were probably able to discriminate neonates with sepsis versus normal uninfected neonates. Among them, the best two paired pathways were identified according to analysis of extensive literature. Impact statement To find the best pairs of pathways able to discriminate sepsis samples versus normal samples, an RF classifier, the DS obtained by DEGs of paired pathways significantly associated, and Monte Carlo cross-validation were applied in this paper. Ten pairs of pathways were probably able to discriminate neonates with sepsis versus normal uninfected neonates. Among them, the best two paired pathways ((7) IL-6 Signaling and Phospholipase C Signaling (PLC); (8) Glucocorticoid Receptor (GR) Signaling and Dendritic Cell Maturation) were identified according to analysis of extensive literature.

Defects in innate and adaptive immunity in patients with sepsis and health care associated infection

Recent advances in sepsis therapy exclusively involve improvements in supportive care, while sepsis mortality rates remain disturbingly high at 30%. These persistently high sepsis mortality rates arise from the absence of sepsis specific therapies. However with improvements in supportive care, patients with septic shock commonly partially recover from the infection that precipitated their initial illness, yet they frequently succumb to subsequent health care associated infections. Remarkably today the pathophysiology of sepsis in humans, a common disease in western society, remains largely a conundrum. Conventionally sepsis was regarded as primarily a disorder of inflammation. More recently the importance of immune compromise in the pathophysiology of sepsis and health care associated infection has now become more widely accepted. Accordingly a review of the human evidence for this novel sepsis paradigm is timely. Septic patients appear to exhibit a complex and long-lasting immune deficiency state, involving lymphocytes of both the innate and adaptive immune responses that have been linked with mortality and the occurrence of health care associated infection. Such is the pervasive nature of immune compromise in sepsis that ultimately immune modulation will play a crucial role in sepsis therapies of the future.

Phenotyping the Immune Response to Trauma: A Multiparametric Systems Immunology Approach

OBJECTIVE

Trauma induces a complex immune response that requires a systems biology research approach. Here, we used a novel technology, mass cytometry by time-of-flight, to comprehensively characterize the multicellular response to trauma.

DESIGN

Peripheral blood mononuclear cells samples were stained with a 38-marker immunophenotyping cytometry by time-of-flight panel. Separately, matched peripheral blood mononuclear cells were stimulated in vitro with heat-killed Streptococcus pneumoniae or CD3/CD28 antibodies and stained with a 38-marker cytokine panel. Monocytes were studied for phagocytosis and oxidative burst.

SETTING

Single-institution level 1 trauma center.

PATIENTS OR SUBJECTS

Trauma patients with injury severity scores greater than 20 (n = 10) at days 1, 3, and 5 after injury, and age- and gender-matched controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Trauma-induced expansion of Th17-type CD4 T cells was seen with increased expression of interleukin-17 and interleukin-22 by day 5 after injury. Natural killer cells showed reduced T-bet expression at day 1 with an associated decrease in tumor necrosis factor-β, interferon-γ, and monocyte chemoattractant protein-1. Monocytes showed robust expansion following trauma but displayed decreased stimulated proinflammatory cytokine production and significantly reduced human leukocyte antigen - antigen D related expression. Further analysis of trauma-induced monocytes indicated that phagocytosis was no different from controls. However, monocyte oxidative burst after stimulation increased significantly after injury.

CONCLUSIONS

Using cytometry by time-of-flight, we were able to identify several major time-dependent phenotypic changes in blood immune cell subsets that occur following trauma, including induction of Th17-type CD4 T cells, reduced T-bet expression by natural killer cells, and expansion of blood monocytes with less proinflammatory cytokine response to bacterial stimulation and less human leukocyte antigen - antigen D related. We hypothesized that monocyte function might be suppressed after injury. However, monocyte phagocytosis was normal and oxidative burst was augmented, suggesting that their innate antimicrobial functions were preserved. Future studies will better characterize the cell subsets identified as being significantly altered by trauma using cytometry by time-of-flight, RNAseq technology, and functional studies.

Effects of early enteral nutrition on T helper lymphocytes of surgical septic patients: A retrospective observational study

The aim of this study was to investigate the effects of early enteral nutrition (EEN) on T helper lymphocytes and the subpopulations ratios of surgical septic patients.We performed a retrospective study including 107 eligible patients from February 2014 to December 2015. Patients were divided into EEN, delayed enteral nutrition (DEN), or total parenteral nutrition (TPN) group according to the duration before enteral feeding. Th1, Th2, Th17, and Treg lymphocyte percentages were collected on days 3, 7, and 14 after admission. The disease severity and clinical outcome variables were also recorded.The Th1, Th17 percentages, and Th1/Th2, Th17/Treg ratios of EEN group were significantly lower than those of DEN or TPN group on the 14th day after admission (P < .05). Compared with TPN, DEN might have a tendency to decrease the Th1 and Th17 percentages. EEN could improve the disease severity and clinical outcomes of septic patients, however, no difference on 28-day mortality was found between EEN and DEN group.EEN could improve the dysregulation of Th1/Th2 and Th17/Treg ratios during early stage of sepsis. Compared with DEN, EEN could improve the disease severity and clinical outcomes, but not decrease the 28-day mortality of surgical septic patients.

Cytokine Kinetics in Febrile Neutropenic Children: Insights on the Usefulness as Sepsis Biomarkers, Influence of Filgrastim, and Behavior of the IL-23/IL-17 Pathway

Background

The study aimed to describe the kinetics of various cytokines from day 1 to day 14 of the onset of fever in neutropenic children and to evaluate their performances as discriminators of sepsis in the first 24 hours of fever, the possible influence of filgrastim, and the functioning of the IL-23/IL-17 axis.

Methods

IL-1β, TNF-α, IL-10, IL-12/23p40, IL-21, IL-6, IL-8, IL-17, G-CSF, and GM-CSF were measured in plasma on days 1, 2, 3, 5, and 14 from the onset of fever in 35 patients.

Results

Thirteen patients (37.1%) developed sepsis. In mixed models, IL-6, IL-8, IL-10, and G-CSF showed higher estimated means in septic patients (P < 0.005), and IL-12/23p40 and IL-17 in nonseptic patients (P < 0.05). On day 1, IL-6, IL-8, and IL-10 appeared upregulated in patients who received filgrastim. Only IL-6, IL-8, IL-10, and procalcitonin were useful as discriminators of sepsis. Associating the markers with each other or to a risk assessment model improved performance.

Conclusions

Cytokines kinetics showed proinflammatory and anti-inflammatory responses similar to what is described in nonneutropenic patients. IL-8, IL-6, IL-10, and procalcitonin are useful as early biomarkers of sepsis. Filgrastim upregulates expression of these markers, and we observed deficiency in the IL-23-IL-17 axis accompanying sepsis.

Neutrophil migration in infection and wound repair: going forward in reverse

Neutrophil migration and its role during inflammation has been the focus of increased interest in the past decade. Advances in live imaging and the use of new model systems have helped to uncover the behaviour of neutrophils in injured and infected tissues. Although neutrophils were considered to be short-lived effector cells that undergo apoptosis in damaged tissues, recent evidence suggests that neutrophil behaviour is more complex and, in some settings, neutrophils might leave sites of tissue injury and migrate back into the vasculature. The role of reverse migration and its contribution to resolution of inflammation remains unclear. In this Review, we discuss the different cues within tissues that mediate neutrophil forward and reverse migration in response to injury or infection and the implications of these mechanisms to human disease.

The Role of Th-17 Cells and γδ T-Cells in Modulating the Systemic Inflammatory Response to Severe Burn Injury

Burns are a global public health problem, accounting for an estimated 265,000 deaths annually. Inflammation is essential in supplying the growth factors, cytokines and chemokines needed to recruit T-cells and myeloid cells to the site of a burn injury for wound healing. However, major burns generate a marked pathophysiological inflammatory response through a widespread release of abundant pro-inflammatory mediators that predispose patients to a systemic inflammatory response syndrome, sepsis and multi-organ failure. Recently, there has been promising investigation into the role of γδ T-cells and Th-17 cells in the regulation and propagation of this inflammatory response. This study reviews the current literature on the post-burn immune response.

Reconstitution of Peripheral T Cells by Tissue-Derived CCR4+ Central Memory Cells Following HIV-1 Antiretroviral Therapy

Background:

Highly active antiretroviral therapy induces clinical benefits to HIV-1 infected individuals, which can be striking in those with progressive disease. Improved survival and decreased incidence of opportunistic infections go hand in hand with a suppression of the plasma viral load, an increase in peripheral CD4⁺ T-cell counts, as well as a reduction in the activation status of both CD4⁺ and CD8⁺ T cells.

Methods:

We investigated T-cell dynamics during ART by polychromatic flow cytometry in total as well as in HIV-1-specific CD4⁺ and CD8⁺ T cells in patients with advanced disease. We also measured gene expression by single cell transcriptomics to assess functional state.

Results:

The cytokine pattern of HIV-specific CD8⁺ T cells was not altered after ART, though their magnitude decreased significantly as the plasma viral load was suppressed to undetectable levels. Importantly, while CD4⁺ T cell numbers increased substantially during the first year, the population did not normalize: the increases were largely due to expansion of mucosal-derived CCR4⁺ CD4⁺ T_CM; transcriptomic analysis revealed that these are not classical Th₂-type cells.

Conclusion:

The apparent long-term normalization of CD4⁺ T-cell numbers following ART does not comprise a normal balance of functionally distinct cells, but results in a dramatic Th₂ shift of the reconstituting immune system.

Protective effect of pilin protein with alum+naloxone adjuvant against acute pulmonary Pseudomonas aeruginosa infection

Pseudomonas aeruginosa is an important opportunistic human pathogen that causes a wide variety of severe nosocomial infections. Type IV pili of P. aeruginosa are made up of polymerized pilin that aids in bacterial adhesion, biofilm formation and twitching motility. The aim of this study was to evaluate the efficacy of alum and naloxone (alum+NLX) as an adjuvant for P. aeruginosa recombinant PilA (r-PilA) as a vaccine candidate in the improvement of humoral and cellular immunity. Primary immunization with r-PilA in combination with alum+NLX followed by two booster shots was sufficient to generate robust cellular and humoral responses, which were Th1 and Th2 type responses consisting of IgG1 and IgG2a subtypes. Analysis of the cytokine response among immunized mice showed an increased production of IL-4, INF-γ and IL-17 by splenocytes upon stimulation by r-PilA. These sera were also able to reduce bacterial load in the lung tissue of challenged mice. The reduction of systemic bacterial spread resulted in increased survival rates in challenged immunized mice. In conclusion, immunization with r-PilA combined with alum+NLX evokes cellular and humoral immune responses, which play an important role in providing protection against acute P. aeruginosa lung infection among immunized mice.

Flagellin and pilin immunization against multi-drug resistant Pseudomonas aeruginosa protects mice in the burn wound sepsis model

Pseudomonas aeruginosa is a formidable pathogen and a major threat to burn patients. Antimicrobial therapy is often unsuccessful because P. aeruginosa can develop multi-drug resistance; thus, immunotherapy and vaccine can be a rational alternative. Flagella and type IV pili have been identified as important virulence factors in the colonization and pathogenesis of P. aeruginosa in burn wound infections. Immunogenicity and efficacy of mixed recombinant full-length type b flagellin (r-b-flagellin) and recombinant PilA (r-PilA) as candidate vaccines were assessed by measuring humoral and cellular responses, using an experimental burned mouse model. Primary immunization with "r-b-flagellin+r-PilA" followed by two booster shots was sufficient to generate a robust humoral response, which was predominantly a Th2 response consisting mainly of subtype IgG1 and low levels of IgG2a. Analysis of the cytokine response among immunized mice showed an increased production of IL-4, INF-γ and IL-17 by splenocytes upon stimulation by "r-b-flagellin+r-PilA". Opsonophagocytosis assays confirmed the enhanced killing of bacteria by anti "r-b-flagellin+r-PilA" immune sera. These antibodies were also able to reduce bacterial load in the site of original infection into the liver and spleen of challenged mice. The reduction of systemic bacterial spread resulted in an increased survival rate of challenged immunized mice. In conclusion, immunization with "r-b-flagellin+r-PilA" proteins provides a better protective response against P. aeruginosa infection in the burn mouse model.

Immunogenicity of Pseudomonas aeruginosa recombinant b-type fagellin as a vaccine candidate: Protective efficacy in a murine burn wound sepsis model

Pseudomonas aeruginosa (PA) is a formidable opportunistic pathogen among patients with burn wound infections. Antimicrobial therapy is often unsuccessful because PA can develop multi-drug resistance; thus, immunotherapy can be a rational alternative. The goal of this study was to evaluate the immunogenicity recombinant type b flagellin (r-b-flagellin) as a potential vaccine against P. aeruginosa in a mouse model for burn wound sepsis. Primary immunization with r-b-flagellin (10μg) followed by two booster shots was sufficient to generate a robust humoral response, which was predominantly a T helper 2 (Th2) type response consisting mainly of subtype IgG1 and low levels of IgG2a. Analysis of the Th1-Th2 response among immunized mice showed an increased production of IL-4, INF-γ and IL-17 by splenocytes upon stimulation by r-b-flagellin. Opsono-phagocytosis assays confirmed the enhanced killing of bacteria by anti r-b-flagellin immune sera. These antibodies were also able to inhibit motility of P. aeruginosa and afforded protection to immunized mice by reducing bacterial load in the site of original infection into the liver of challenged mice. The reduction of systemic bacterial spread resulted in an increase in the survival rate of challenged immunized mice. In conclusion, immunization of mice with r-b-flagellin protein increased the level of humoral and cellular immune response and led to an efficacious protection against P. aeruginosa infection in the burn mouse model.

Intestine immune homeostasis after alcohol and burn injury

Traumatic injury remains one of the most prevalent reasons for patients to be hospitalized. Burn injury accounts for 40,000 hospitalizations in the United States annually, resulting in a large burden on both the health and economic system and costing millions of dollars every year. The complications associated with postburn care can quickly cause life-threatening conditions including sepsis and multiple organ dysfunction and failure. In addition, alcohol intoxication at the time of burn injury has been shown to exacerbate these problems. One of the biggest reasons for the onset of these complications is the global suppression of the host immune system and increased susceptibility to infection. It has been hypothesized that infections after burn and other traumatic injury may stem from pathogenic bacteria from within the host's gastrointestinal tract. The intestine is the major reservoir of bacteria within the host, and many studies have demonstrated perturbations of the intestinal barrier after burn injury. This article reviews the findings of these studies as they pertain to changes in the intestinal immune system after alcohol and burn injury.