Associations of T helper 1, 2, 17 and regulatory T lymphocytes with mortality in severe sepsis

Regulatory B cells attenuate sepsis-associated pancreatic injury by regulating T cell homeostasis

Sepsis is a common and life-threatening syndrome resulting from systemic and dysregulated immune response to severe infection, which contributes to morbidity and mortality in critically ill patients. This work aimed to evaluate the regulatory function of Breg cells in sepsis-associated pancreatic injury. We established mice model of sepsis-associated pancreatic injury by cecal ligation and puncture (CLP). Pancreatic injury was assessed by measuring the levels of amylase activity and histologic pancreatic injury scores. The proportions of Breg cells and T cell subsets were analyzed by flow cytometry, their secreted cytokines were detected by ELISA. The expressions of T-bet, RORγt and Foxp3 in spleen were determined by RT-PCR. The apoptosis of pancreatic cells was examined by LDH assay and Tunel, and the cell viability was detected by MTT assay. Compared to the sham group, a significantly lower percentage of Breg cells was observed in model mice. Anti-CD22 treatment exacerbated pancreatic injury, and significantly increased the percentages of Th1, Th17 cells along with the levels of IFN-γ, IL-17 in CLP-induced sepsis model, but did not affect the differentiation of Treg cells and expression of IL-10. Anti-CD22 administration promoted the expressions of T-bet and RORγt, but did not affect the Foxp3 expression. Adoptive transfer Breg cells remarkably alleviated pancreatic injury, and significantly decreased the percentages of Th1, Th17 cells along with the levels of IFN-γ, IL-17 and further promoted the percentage of Treg cells and expression of IL-10 in CLP-induced sepsis model. Moreover, adoptive transfer Breg cells inhibited the expressions of T-bet and RORγt, and promoted Foxp3 expression in model mice. Lipopolysaccharide (LPS) promoted the apoptosis in pancreatic acinar cells, which was inhibited after culturing with Breg cells in vitro. LPS remarkably upregulated the differentiation of Th1 and Th17 cells, and downregulated the differentiation of Treg cells, which could be significantly reversed by Breg cells in vitro. In conclusion, Breg cells may exhibit the protective effects by modulating T cell responses along with the cytokines in sepsis-associated pancreatic injury.

Plasma proteomics in pediatric patients with sepsis- hopes and challenges

One of the main causes of morbidity and death in pediatric patients is sepsis. Of the 48.9 million cases of sepsis reported globally, 41.5% involve children under the age of five, with 2.9 million deaths associated with the disease. Clinicians must identify and treat patients at risk of sepsis or septic shock before late-stage organ dysfunction occurs since diagnosing sepsis in young patients is more difficult than in adult patients. As of right now, omics technologies that possess adequate diagnostic sensitivity and specificity can assist in locating biomarkers that indicate how the disease will progress clinically and how the patient will react to treatment. By identifying patients who are at a higher risk of dying or experiencing persistent organ dysfunction, risk stratification based on biomarkers generated from proteomics can enhance prognosis. A potentially helpful method for determining the proteins that serve as biomarkers for sepsis and formulating theories on the pathophysiological mechanisms behind complex sepsis symptoms is plasma proteomics.

Identification of DNA damage repair-related genes in sepsis using bioinformatics and machine learning: An observational study

Sepsis is a life-threatening disease with a high mortality rate, for which the pathogenetic mechanism still unclear. DNA damage repair (DDR) is essential for maintaining genome integrity. This study aimed to explore the role of DDR-related genes in the development of sepsis and further investigated their molecular subtypes to enrich potential diagnostic biomarkers. Two Gene Expression Omnibus datasets (GSE65682 and GSE95233) were implemented to investigate the underlying role of DDR-related genes in sepsis. Three machine learning algorithms were utilized to identify the optimal feature genes. The diagnostic value of the selected genes was evaluated using the receiver operating characteristic curves. A nomogram was built to assess the diagnostic ability of the selected genes via "rms" package. Consensus clustering was subsequently performed to identify the molecular subtypes for sepsis. Furthermore, CIBERSORT was used to evaluate the immune cell infiltration of samples. Three different expressed DDR-related genes (GADD45A, HMGB2, and RPS27L) were identified as sepsis biomarkers. Receiver operating characteristic curves revealed that all 3 genes showed good diagnostic value. The nomogram including these 3 genes also exhibited good diagnostic efficiency. A notable difference in the immune microenvironment landscape was discovered between sepsis patients and healthy controls. Furthermore, all 3 genes were significantly associated with various immune cells. Our findings identify potential new diagnostic markers for sepsis that shed light on novel pathogenetic mechanism of sepsis and, therefore, may offer opportunities for potential intervention and treatment strategies.

Macrophage activation syndrome in Sepsis: from pathogenesis to clinical management

BACKGROUND

Sepsis represents a significant global health and hygiene challenge. Excessive activation of macrophages in sepsis can result in certain patients displaying characteristics akin to those observed in Macrophage Activation Syndrome (MAS). MAS represents a grave immune system disorder characterized by persistent and severe inflammation within the body. In the context of sepsis, MAS presents atypically, leading some researchers to refer to it as Macrophage Activation-Like Syndrome (MALS). However, there are currently no effective treatment measures for this situation. The purpose of this article is to explore potential treatment methods for sepsis-associated MALS.

OBJECTIVE

The objective of this review is to synthesize the specific pathophysiological mechanisms and treatment strategies of MAS to investigate potential therapeutic approaches for sepsis-associated MALS.

METHOD

We searched major databases (including PubMed, Web of Science, and Google Scholar etc.) for literature encompassing macrophage activation syndrome and sepsis up to Mar 2024 and combined with studies found in the reference lists of the included studies.

CONCLUSION

We have synthesized the underlying pathophysiological mechanism of MALS in sepsis, and then summarized the diagnostic criteria and the effects of various treatment modalities utilized in patients with MAS or MALS. In both scenarios, heterogeneous treatment responses resulting from identical treatment approaches were observed. The determination of whether the patient is genuinely experiencing MALS significantly impacts the ultimate outcomes of therapeutic efficacy. In order to tackle this concern, additional clinical trials and research endeavors are imperative.

Dipsacoside B ameliorates cognitive impairment in sepsis-associated encephalopathy by reducing Th17 cell infiltration and neuroinflammation

Sepsis-associated encephalopathy (SAE) is the main cause of cognitive impairment in patients with sepsis. The infiltration of inflammatory signals into the central nervous system (CNS) via the compromised blood-brain barrier (BBB) represents a crucial step in the pathological progression of SAE. In particular, T-helper 17 cell (Th17 cells) has been suggested to be highly correlated with the activation of central immune responses. Thus, preventing Th17 cell infiltration into the CNS may be a possible strategy to alleviate cognitive decline in SAE. Dipsacoside B (DB) is one of the primary active components in Chuan Xu Duan (Dipsacus asper Wall). We speculate that DB may be a potential candidate for the treatment of SAE-related cognitive deficits. In the present study, we demonstrated that DB could effectively alleviate cognitive impairment in SAE mice. DB significantly suppressed the central inflammatory response induced by repeated lipopolysaccharide (LPS) injection. The mechanism underlying its therapeutic effect should be attributed to the reduction of BBB impairment and pathogenic Th17 cell infiltration into the CNS by inhibition of vascular endothelial growth factor A (VEGFA)/ Vascular endothelial growth factor receptor 2(VEGFR2)/ Endothelial nitric oxide synthase (eNOS) signaling. Our findings suggest that DB is a potential candidate for the treatment of SAE-related cognitive dysfunction.

Exosome-Derived microRNA: Potential Target for Diagnosis and Treatment of Sepsis

Exosome-derived microRNAs (miRNAs) are emerging as pivotal players in the pathophysiology of sepsis, representing a new frontier in both the diagnosis and treatment of this complex condition. Sepsis, a severe systemic response to infection, involves intricate immune and nonimmune mechanisms, where exosome-mediated communication can significantly influence disease progression and outcomes. During the progress of sepsis, the miRNA profile of exosomes undergoes notable alterations, is reflecting, and may affect the progression of the disease. This review comprehensively explores the biology of exosome-derived miRNAs, which originate from both immune cells (such as macrophages and dendritic cells) and nonimmune cells (such as endothelial and epithelial cells) and play a dynamic role in modulating pathways that affect the course of sepsis, including those related to inflammation, immune response, cell survival, and apoptosis. Taking into account these dynamic changes, we further discuss the potential of exosome-derived miRNAs as biomarkers for the early detection and prognosis of sepsis and advantages over traditional biomarkers due to their stability and specificity. Furthermore, this review evaluates exosome-based therapeutic miRNA delivery systems in sepsis, which may pave the way for targeted modulation of the septic response and personalized treatment options.

CIRP increases Foxp3+ regulatory T cells and inhibits development of Th17 cells by enhancing TLR4-IL-2 signaling in the late phase of sepsis

BACKGROUND

T helper (Th) cell imbalances have been associated with the pathophysiology of sepsis, including the Th1/Th2 and Th17/T regulatory cells (Treg) paradigms. Cold-inducible RNA-binding protein (CIRP), a novel damage-associated molecular pattern (DAMP) was reported that could induce T cell activation, and skew CD4+ T cells towards a Th1 profile. However, the effect and underlying mechanisms of CIRP on Th17/Treg differentiation in sepsis still remains unknown.

METHODS

A prospective exploratory study including patients with sepsis was conducted. Blood samples were collected from patients on days 0, 3 and 7 on admission. The serum CIRP and peripheral blood Treg/Th17 percentage was determined by ELISA and flow cytometry. CD4+ T cells from the spleen and lymph nodes of mice with experimental sepsis were collected after treatment with normal saline (NS), recombinant murine CIRP (rmCIRP) and C23 (an antagonist for CIRP-TLR4) at late stage of sepsis. RNA-seq was conducted to reveal the pivotal molecular mechanism of CIRP on Treg/Th17 differentiation. Naïve CD4+ T cell was isolated from the Tlr4 null and wildtype mice in the presence or absence rmCIRP and C23 to confirmed above findings.

RESULTS

A total of 19 patients with sepsis finally completed the study. Serum CIRP levels remained high in the majority of patients up to 1 week after admittance was closely associated with high Treg/Th17 ratio of peripheral blood and poor outcome. A univariate logistic analysis demonstrated that higher CIRP concentration at Day 7 is an independent risk factor for Treg/Th17 ratio increasing. CIRP promotes Treg development and suppresses Th17 differentiation was found both in vivo and in vitro. Pretreated with C23 not only alleviated the majority of negative effect of CIRP on Th17 differentiation, but also inhibited Treg differentiation, to some extent. Tlr4 deficiency could abolish almost all downstream effects of rmCIRP. Furthermore, IL-2 is proved a key downstream molecules of the effect CIRP, which also could amplify the activated CD4+ T lymphocytes.

CONCLUSIONS

Persistent high circulating CIRP level may lead to Treg/Th17 ratio elevated through TLR4 and subsequent active IL-2 signaling which contribute to immunosuppression during late phases of sepsis.

Purinergic P2X7 receptor expression increases in leukocytes from intra-abdominal septic patients

Inflammation is a tightly coordinated response of the host immune system to bacterial and viral infections, triggered by the production of inflammatory cytokines. Sepsis is defined as a systemic inflammatory response followed by immunosuppression of the host and organ dysfunction. This imbalance of the immune response increases the risk of mortality of patients with sepsis, making it a major problem for critical care units worldwide. The P2X7 receptor plays a crucial role in activating the immune system by inducing the activation of peripheral blood mononuclear cells. In this study, we analyzed a cohort of abdominal origin septic patients and found that the expression of the P2X7 receptor in the plasma membrane is elevated in the different subsets of lymphocytes. We observed a direct relationship between the percentage of P2X7-expressing lymphocytes and the early inflammatory response in sepsis. Additionally, in patients whose lymphocytes presented a higher percentage of P2X7 surface expression, the total lymphocytes populations proportionally decreased. Furthermore, we found a correlation between elevated soluble P2X7 receptors in plasma and inflammasome-dependent cytokine IL-18. In summary, our work demonstrates that P2X7 expression is highly induced in lymphocytes during sepsis, and this correlates with IL-18, along with other inflammatory mediators such as IL-6, IL-8, and procalcitonin.

Analysis of lactate metabolism-related genes and their association with immune infiltration in septic shock via bioinformatics method

Background: Lactate, as an essential clinical evaluation index of septic shock, is crucial in the incidence and progression of septic shock. This study aims to investigate the differential expression, regulatory relationship, clinical diagnostic efficacy, and immune infiltration of lactate metabolism-related genes (LMGs) in septic shock. Methods: Two sepsis shock datasets (GSE26440 and GSE131761) were screened from the GEO database, and the common differentially expressed genes (DEGs) of the two datasets were screened out. LMGs were selected from the GeneCards database, and lactate metabolism-related DEGs (LMDEGs) were determined by integrating DEGs and LMGs. Protein-protein interaction networks, mRNA-miRNA, mRNA-RBP, and mRNA-TF interaction networks were constructed using STRING, miRDB, ENCORI, and CHIPBase databases, respectively. Receiver operating characteristic (ROC) curves were constructed for each of the LMDEGs to evaluate the diagnostic efficacy of the expression changes in relation to septic shock. Finally, immune infiltration analysis was performed using ssGSEA and CIBERSORT. Results: This study identified 10 LMDEGs, including LDHB, STAT3, LDHA, GSR, FOXM1, PDP1, GCDH, GCKR, ABCC1, and CDKN3. Enrichment analysis revealed that DEGs were significantly enriched in pathways such as pyruvate metabolism, hypoxia pathway, and immune-inflammatory pathways. PPI networks based on LMDEGs, as well as 148 pairs of mRNA-miRNA interactions, 243 pairs of mRNA-RBP interactions, and 119 pairs of mRNA-TF interactions were established. ROC curves of eight LMDEGs (LDHA, GSR, STAT3, CDKN3, FOXM1, GCKR, PDP1, and LDHB) with consistent expression patterns in two datasets had an area under the curve (AUC) ranging from 0.662 to 0.889. The results of ssGSEA and CIBERSORT both showed significant differences in the infiltration of various immune cells, including CD8 T cells, T regulatory cells, and natural killer cells, and LMDEGs such as STAT3, LDHB, LDHA, PDP1, GSR, FOXM1, and CDKN3 were significantly associated with various immune cells. Conclusion: The LMDEGs are significantly associated with the immune-inflammatory response in septic shock and have a certain diagnostic accuracy for septic shock.

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.

Serial Increases in Human Leukocyte Antigen-DR Expression and Decreases in Interleukin-10 Expression in Alveolar Monocytes of Survivors of Pneumonia-Related Acute Respiratory Distress Syndrome

ARDS is a potentially lethal syndrome. HLA-DR expression in monocytes reflects their activation and antigen-presenting capacity. However, the correlation between clinical outcomes and HLA-DR expression in alveolar monocytes/macrophages in patients with pneumonia-related ARDS remains unclear. Thus, we determined the trends of HLA-DR and cytokine expressions in alveolar monocytes using repeated measurements to answer this question. Thirty-one pneumonia patients with respiratory failure and ARDS without coronavirus disease 2019 between November 2019 and November 2021 were enrolled in our intensive care unit and three without complete data were excluded. Interleukin (IL)-10, IL-12, and HLA-DR expression in bronchoalveolar lavage (BAL) monocytes were determined on days one and eight. Monocyte HLA-DR expression (mHLA-DR) and CD4 T lymphocytes percentages in BAL cells of survivors increased remarkably after seven days. Monocyte IL-10 expression and monocytes percentages in BAL cells of survivors decreased substantially after seven days. The mHLA-DR was negatively correlated with disease severity scores on day one and eight. In conclusion, serial increases in HLA-DR expression and decreases in IL-10 expression were observed in BAL monocytes of survivors of pneumonia-related ARDS. More studies are needed to confirm this point of view, and then development of a therapeutic agent restoring mHLA-DR and preventing IL-10 production can be considered.

Construction of an HLA Classifier for Early Diagnosis, Prognosis, and Recognition of Immunosuppression in Sepsis by Multiple Transcriptome Datasets

Background: Sepsis is a clinical syndrome, due to a dysregulated inflammatory response to infection. Accumulating evidence shows that human leukocyte antigen (HLA) genes play a key role in the immune responses to sepsis. Nevertheless, the effects of HLA genes in sepsis have still not been comprehensively understood.

Methods: A systematical search was performed in the Gene Expression Omnibus (GEO) and ArrayExpress databases from inception to 10 September 2021. Random forest (RF) and modified Lasso penalized regression were conducted to identify hub genes in multi-transcriptome data, thus we constructed a prediction model, namely the HLA classifier. ArrayExpress databases, as external validation, were utilized to evaluate its diagnostic, prognostic, and predictive performance. Immune cell infiltration score was calculated via CIBERSORTx tools and single-sample gene set enrichment analysis (ssGSEA). Gene set variation analysis (GSVA) and ssGSEA were conducted to determine the pathways that are significantly enriched in different subgroups. Next, we systematically correlated the HLA classifier with immunological characteristics from multiple perspectives, such as immune-related cell infiltration, pivotal molecular pathways, and cytokine expression. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to validate the expression level of HLA genes in clinical samples.

Results: A total of nine datasets comprising 1,251 patients were included. Based on RF and modified Lasso penalized regression in multi-transcriptome datasets, five HLA genes (B2M, HLA-DQA1, HLA-DPA1, TAP1, and TAP2) were identified as hub genes, which were used to construct an HLA classifier. In the discovery cohort, the HLA classifier exhibited superior diagnostic value (AUC = 0.997) and performed better in predicting mortality (AUC = 0.716) than clinical characteristics or endotypes. Encouragingly, similar results were observed in the ArrayExpress databases. In the E-MTAB-7581 dataset, the use of hydrocortisone in the HLA high-risk subgroup (OR: 2.84, 95% CI 1.07–7.57, p = 0.037) was associated with increased risk of mortality, but not in the HLA low-risk subgroup. Additionally, immune infiltration analysis by CIBERSORTx and ssGSEA revealed that B cells, activated dendritic cells, NK cells, T helper cells, and infiltrating lymphocytes (ILs) were significantly richer in HLA low-risk phenotypes, while Tregs and myeloid-derived suppressor cells (MDSCs) were more abundant in HLA high-risk phenotypes. The HLA classifier was significantly negatively correlated with B cells, activated dendritic cells, NK cells, T helper cells, and ILs, yet was significantly positively correlated with Tregs and MDSCs. Subsequently, molecular pathways analysis uncovered that cytokine-cytokine receptor (CCR) interaction, human leukocyte antigen (HLA), and antigen-presenting cell (APC) co-stimulation were significantly enriched in HLA low-risk endotypes, which was significantly negatively correlated with the HLA classifier in multi-transcriptome data. Finally, the expression levels of several cytokines (IL-10, IFNG, TNF) were significantly different between the HLA subgroups, and the ratio of IL-10/TNF was significantly positively correlated with HLA score in multi-transcriptome data. Results of qRT-PCR validated the higher expression level of B2M as well as lower expression level of HLA-DQA1, HLA-DPA1, TAP1, and TAP2 in sepsis samples compared to control sample.

Conclusion: Based on five HLA genes, a diagnostic and prognostic model, namely the HLA classifier, was established, which is closely correlated with responses to hydrocortisone and immunosuppression status and might facilitate personalized counseling for specific therapy.

Advances in Immune Monitoring Approaches for Sepsis-Induced Immunosuppression

Sepsis represents a life-threatening organ dysfunction due to an aberrant host response. Of note is that majority of patients have experienced a severe immune depression during and after sepsis, which is significantly correlated with the occurrence of nosocomial infection and higher risk of in-hospital death. Nevertheless, the clinical sign of sepsis-induced immune paralysis remains highly indetectable and ambiguous. Given that, specific yet robust biomarkers for monitoring the immune functional status of septic patients are of prominent significance in clinical practice. In turn, the stratification of a subgroup of septic patients with an immunosuppressive state will greatly contribute to the implementation of personalized adjuvant immunotherapy. In this review, we comprehensively summarize the mechanism of sepsis-associated immunosuppression at the cellular level and highlight the recent advances in immune monitoring approaches targeting the functional status of both innate and adaptive immune responses.

Characterization of immune-related genes andimmune infiltration features for early diagnosis, prognosis and recognition of immunosuppression in sepsis

Among the body systems, the immune system plays a fundamental role in the pathophysiology of sepsis. The effects of immunogenomic and immune cell infiltration in sepsis were still not been systematically understood. Based on modified Lasso penalized regression and RF, 8 DEIRGs (ADM, CX3CR1, DEFA4, HLA-DPA1, MAPK14, ORM1, RETN, and SLPI) were combined to construct an IRG classifier. In the discovery cohort, IRG classifier exhibited superior diagnostic efficacy and performed better in predicting mortality than clinical characteristics or MARS/SRS endotypes. Encouragingly, similar results were observed in the ArrayExpress databases. The use of hydrocortisone in IRG high-risk subgroup was associated with increased risk of mortality. In IRG low-risk phenotypes, NK cells, T helper cells, and infiltrating lymphocyte (IL) are significantly richer, while T cells regulatory (Tregs) and myeloid-derived suppressor cells (MDSC) are more abundant in IRG high-risk phenotypes. IRG score were significantly negatively correlated with Cytokine cytokine receptor interaction (CCR) and human leukocyte antigen (HLA). Between the IRG subgroups, the expression levels of several cytokines (IL-10, IFNG, TNF) were significantly different, and IRG score was significantly positively correlated with ratio of IL-10/TNF. Results of qRT-PCR validated that higher expression level of ADM, DEFA4, MAPK14, ORM1, RETN, and SLPI as well as lower expression level of CX3CR1 and HLA-DPA1 in sepsis samples compared to control sample. A diagnostic and prognostic model, namely IRG classifier, was established based on 8 IRGs that is closely correlated with responses to hydrocortisone and immunosuppression status and might facilitate personalized counseling for specific therapy.

Early High-dose Continuous Veno-venous Hemofiltration Alleviates the Alterations of CD4+ T Lymphocyte Subsets in Septic Patients Combined with Acute Kidney Injury

BACKGROUND

This study aims to determine whether early high-dose continuous venous-venous hemofiltration (CVVH) alleviates the alterations in CD4⁺ T lymphocyte subsets in septic patients combined with acute kidney injury.

METHODS

Enrolled septic patients combined with acute kidney injury were randomized into CVVH (n = 50) and conventional treatment (non-CVVH, n = 53) groups. Healthy volunteers (n = 21) were enrolled. CVVH was initiated within 12 h of intensive care unit (ICU) admission with the doses of 35 ~ 60 mL/kg/h and maintained for at least 72 h. Th1, Th2, Th17 and T_reg were measured by flow cytometry on days 1, 3 and 7 of ICU admission. Sequential organ failure assessment (SOFA) scores were calculated.

RESULTS

Th1 percentages and Th1/Th2 ratios were lower, and Th2, Th17 and T_reg percentages and Th17/T_reg ratios were higher in septic patients compared to healthy volunteers. CVVH significantly increased Th1 percentages and Th1/Th2 ratios, and significantly decreased Th2, Th17 and T_reg percentages and Th17/T_reg ratios compared to non-CVVH. Th1 percentages and Th1/Th2 ratios were negatively correlated with SOFA scores, while Th2, Th17 and T_reg percentages and Th17/T_reg ratios were positively correlated with SOFA scores. Patients with CVVH had significantly lower SOFA scores on day 7 of ICU admission and a shorter ICU stay compared to those with non-CVVH.

CONCLUSIONS

Septic patients combined with acute kidney injury exhibit different alterations of CD4⁺ T lymphocyte subsets. Early high-dose CVVH alleviates the alterations, which may be one of factors associated with improved sepsis severity.

Construction and validation of a robust prognostic model based on immune features in sepsis

Purpose

Sepsis, with life-threatening organ failure, is caused by the uncontrolled host response to infection. Immune response plays an important role in the pathophysiology of sepsis. Immune-related genes (IRGs) are promising novel biomarkers that have been used to construct the diagnostic and prognostic model. However, an IRG prognostic model used to predict the 28-day mortality in sepsis was still limited. Therefore, the study aimed to develop a prognostic model based on IRGs to identify patients with high risk and predict the 28-day mortality in sepsis. Then, we further explore the circulating immune cell and immunosuppression state in sepsis.

Materials and methods

The differentially expressed genes (DEGs), differentially expressed immune-related genes (DEIRGs), and differentially expressed transcription factors (DETFs) were obtained from the GEO, ImmPort, and Cistrome databases. Then, the TFs-DEIRGs regulatory network and prognostic prediction model were constructed by Cox regression analysis and Pearson correlation analysis. The external datasets also validated the reliability of the prognostic model. Based on the prognostic DEIRGs, we developed a nomogram and conducted an independent prognosis analysis to explore the relationship between DEIRGs in the prognostic model and clinical features in sepsis. Besides, we further evaluate the circulating immune cells state in sepsis.

Results

A total of seven datasets were included in our study. Among them, GSE65682 was identified as a discovery cohort. The results of GSEA showed that there is a significant correlation between sepsis and immune response. Then, based on a P value <0.01, 69 prognostic DEIRGs were obtained and the potential molecular mechanisms of DEIRGs were also clarified. According to multivariate Cox regression analysis, 22 DEIRGs were further identified to construct the prognostic model and identify patients with high risk. The Kaplan-Meier survival analysis showed that high-risk groups have higher 28-day mortality than low-risk groups (P=1.105e-13). The AUC value was 0.879 which symbolized that the prognostic model had a better accuracy to predict the 28-day mortality. The external datasets also prove that the prognostic model had an excellent prediction value. Furthermore, the results of correlation analysis showed that patients with Mars1 might have higher risk scores than Mars2-4 (P=0.002). According to the previous study, Mars1 endotype was characterized by immunoparalysis. Thus, the sepsis patients in high-risk groups might exist the immunosuppression. Between the high-risk and low-risk groups, circulating immune cells types were significantly different, and risk score was significantly negatively correlated with naive CD4+ T cells (P=0.019), activated NK cells (P=0.0045), monocytes (P=0.0134), and M1 macrophages (P=0.0002).

Conclusions

Our study provides a robust prognostic model based on 22 DEIRGs which can predict 28-day mortality and immunosuppression status in sepsis. The higher risk score was positively associated with 28-day mortality and the development of immunosuppression. IRGs are a promising biomarker that might facilitate personalized treatments for sepsis.

Transcriptomic Profiles in Children With Septic Shock With or Without Immunoparalysis

Background

Severe innate immune suppression, termed immunoparalysis, is associated with increased risks of nosocomial infection and mortality in children with septic shock. Currently, immunoparalysis cannot be clinically diagnosed in children, and mechanisms remain unclear. Transcriptomic studies identify subsets of septic children with downregulation of genes within adaptive immune pathways, but assays of immune function have not been performed as part of these studies, and little is known about transcriptomic profiles of children with immunoparalysis.

Methods

We performed a nested case-control study to identify differences in RNA expression patterns between children with septic shock with immunoparalysis (defined as lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)α response < 200 pg/ml) vs those with normal LPS-induced TNFα response. Children were enrolled within 48 hours of the onset of septic shock and divided into two groups based on LPS-induced TNFα response. RNA was extracted from whole blood for RNAseq, differential expression analyses using DESeq2 software, and pathway analyses using Ingenuity Pathway Analysis.

Results

32 children were included in analyses. Comparing those with immunoparalysis (n =19) to those with normal TNFα response (n = 13), 2,303 transcripts were differentially expressed with absolute value fold change ≥ 1.5 and false discovery rate ≤ 0.05. The majority of downregulated pathways in children with immunoparalysis were pathways that involved interactions between innate and adaptive immune cells necessary for cell-mediated immunity, crosstalk between dendritic cells and natural killer cells, and natural killer cell signaling pathways. Upregulated pathways included those involved in humoral immunity (T helper cell type 2), corticotropin signaling, platelet activation (GP6 signaling), and leukocyte migration and extravasation.

Conclusions

Our study suggests that gene expression data might be useful to identify children with immunoparalysis and identifies several key differentially regulated pathways involved in both innate and adaptive immunity. Our ongoing work in this area aims to dissect interactions between innate and adaptive immunity in septic children and to more fully elucidate patient-specific immunologic pathophysiology to guide individualized immunotherapeutic targets.

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.

The Novel Role of MIF in the Secretion of IL-25, IL-31, and IL-33 from PBMC of Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune inflammatory joint disease with complex pathogenesis associated with cytokine dysregulation. Macrophage migration inhibitory factor (MIF) plays a role in systemic inflammation and joint destruction in RA and could be associated with the secretion of other immune-modulatory cytokines such as IL-25, IL-31, and IL-33. For the above, our main aim was to evaluate the IL-25, IL-31, and IL-33 secretion from recombinant human MIF (rhMIF)-stimulated peripheral blood mononuclear cells (PBMC) of RA patients. The rhMIF and lipopolysaccharide (LPS) plus rhMIF stimuli promote the secretion of IL-25, IL-31, and IL-33 (p < 0.05) from PBMC of RA patients. The study groups, the different stimuli, and the interaction between both showed a statistically significant effect on the secretion of IL-25 (p < 0.05) and IL-31 (p < 0.01). The study of the effect of the RA patient treatments and their interaction with the effect of stimuli did not show an interaction between them. In conclusion, our study generates new evidence for the role of MIF in the secretion of IL-25, IL-31, and IL-33 and its immunomodulatory effect on RA.

Circulating lymphocyte subsets as promising biomarkers to identify septic patients at higher risk of unfavorable outcome

BACKGROUND

Early recognition of patients hospitalized for sepsis at higher risk of poor clinical outcome is a mandatory task and many studies suggested that indicators of the immune status may be useful for this purpose. We performed a retrospective, monocentric cohort study to evaluate whether lymphocyte subsets may be useful in predicting in-hospital mortality of septic patients.

METHODS

Data of all consecutive patients with a diagnosis of sepsis at discharge and an available peripherical blood lymphocyte subset (CD4, CD8, CD16/CD56 and CD19) analysis at hospital entry were retrospectively collected between January 2015 and August 2018. Clinical characteristics of patients, past medical history and other laboratory parameters were also considered.

RESULTS

Two-hundred-seventy-eight septic patients, 171 (61.5%) males, mean age 63.2 ± 19.6 years, were enrolled. Total counts of lymphocytes, CD4 T cells, CD8 T cells and B cells were found significantly lower in deceased than in surviving patients. At univariate analyses, CD4 T cells/µL (OR 0.99 for each incremental unit, 95%CI 0.99-1.10, p < 0.0001), age (OR 1.06, 95%CI 1.04-1.09, p < 0.0001), procalcitonin (OR 1.01, 95%CI 1.01-1.02, p < 0.0001) and female gender (OR 2.81, 95%CI 1.49-5.28, p = 0.001) were associated with in-hospital mortality. When a dichotomic threshold of < 400/µL for CD4 T cells as a dependent variable was considered in multivariate models, age (OR 1.04; 95%CI 1.01-1.09, p = 0.018); female gender (OR 3.18; 95%CI 1.40-7.20, p = 0.006), qSOFA (OR 4.00, 95%CI 1.84-8.67, p < 0.001) and CD4 T cells < 400/µL (OR 5.3; 95%CI 1.65-17.00, p = 0.005) were the independent predictors.

CONCLUSIONS

In adjunct to biomarkers routinely determined for the prediction of prognosis in sepsis, CD4 T lymphocytes, measured at hospital entry, may be useful in identifying patients at higher risk of in-hospital death.

Plasma Transfusion Promoted Reprogramming CD4+ T Lymphocytes Immune Response in Severe Sepsis Mice Model Through Modulating the Exosome Protein Galectin 9

Sepsis is a life-threatening disease that results in excessive stimulation of the host's immune cells. In the animal study, the purpose was to investigate the roles of fresh frozen plasma (FFP) transfusion in shaping the CD4⁺ T lymphocytes immune response through modulating the secreted exosome protein Galectin-9 in mice with severe sepsis. By using Western blot analysis, we first identified that the protein Galectin-9 is highly accumulated in the blood plasma of severe sepsis mice, and with transmission electron microscopy (TEM) and protein analysis, we found that Galectin-9 is a secreted exosome protein. Thereafter, we treated the severe sepsis mice with the antibiotic Cefuroxime Axetil; one group of mice received FFP transfusion and the other group of mice received normal saline. Surprisingly, the FFP transfusion reduced the secretion of exosome protein Galectin-9 and there was crosstalking between the exosome protein Galectin-9 and CD4⁺ T lymphocytes in mice with severe sepsis. Results showed that the proliferation of T helper (Th) cells (Th1 and Th17) was promoted, and regulatory T (Treg) cells' maintenance was inhibited in the sepsis mice after receiving FFP transfusion. Correspondingly, this immune reprogrammed activity shaped the inflammatory cytokine secretion with an increase in the interleukin (IL)-1β, IL-6, and interferon-gamma levels, while it decreased IL-10 levels. Taken together, it was suggested that FFP transfusion promoted reprogramming of CD4⁺ T lymphocytes' immune response through inhibiting the secretion of exosome protein Galectin-9 in mice with severe sepsis to relieve immunosuppression.

Screening of Key Genes of Sepsis and Septic Shock Using Bioinformatics Analysis

Objective

Sepsis is a disease associated with high mortality. We performed bioinformatic analysis to identify key biomarkers associated with sepsis and septic shock.

Methods

The top 20% of genes showing the greatest variance between sepsis and controls in the GSE13904 dataset (children) were screened by co-expression network analysis. The differentially expressed genes (DEGs) were identified through analyzing differential gene expression between sepsis patients and control in the GSE13904 (children) and GSE154918 (adult) data sets. Intersection analysis of module genes and DEGs was performed to identify common DEGs for enrichment analysis, protein-protein interaction network (PPI network) analysis, and Short Time-series Expression Miner (STEM) analysis. The PPI network genes were ranked by degree of connectivity, and the top 100 sepsis-associated genes were identified based on the area under the receiver operating characteristic curve (AUC). In addition, we evaluated differences in immune cell infiltration between sepsis patients and controls in children (GSE13904, GSE25504) and adults (GSE9960, GSE154918). Finally, we analyzed differences in DNA methylation levels between sepsis patients and controls in GSE138074 (adults).

Results

The common genes were associated mainly with up-regulated inflammatory and metabolic responses, as well as down-regulated immune responses. Sepsis patients showed lower infiltration by most types of immune cells. Genes in the PPI network with AUC values greater than 0.9 in both GSE13904 (children) and GSE154918 (adults) were screened as key genes for diagnosis. These key genes (MAPK14, FGR, RHOG, LAT, PRKACB, UBE2Q2, ITK, IL2RB, and CD247) were also identified in STEM analysis to be progressively dysregulated across controls, sepsis patients and patients with septic shock. In addition, the expression of MAPK14, FGR, and CD247 was modified by methylation.

Conclusion

This study identified several potential diagnostic genes and inflammatory and metabolic responses mechanisms associated with the development of sepsis.

Role of the adaptive immune response in sepsis

Sepsis is a syndrome of shock and dysfunction of multiple vital organs that is caused by an uncontrolled immune response to infection and has a high mortality rate. There are no therapies for sepsis, and it has become a global cause for concern. Advances in patient care and management now mean that most patients survive the initial hyper-inflammatory phase of sepsis but progress to a later immunosuppressed phase, where 30% of patients die due to secondary infection. Deficits in the adaptive immune response may play a major role in sepsis patient mortality. The adaptive immune response involves a number of cell types including T cells, B cells and dendritic cells, all with immunoregulatory roles aimed at limiting damage and returning immune homeostasis after infection or insult. However, in sepsis, adaptive immune cells experience cell death or exhaustion, meaning that they have defective effector and memory responses ultimately resulting in an ineffective or suppressed immune defence. CD4+ T cells seem to be the most susceptible to cell death during sepsis and have ensuing defective secretory profiles and functions. Regulatory T cells seem to evade apoptosis and contribute to the immune suppression observed with sepsis. Preclinical studies have identified a number of new targets for therapy in sepsis including anti-apoptotic agents and monoclonal antibodies aimed at reducing cell death, exhaustion and maintaining/restoring adaptive immune cell functions. While early phase clinical trials have demonstrated safety and encouraging signals for biologic effect, larger scale clinical trial testing is required to determine whether these strategies will prove effective in improving outcomes from sepsis.

Classification of Patients With Sepsis According to Immune Cell Characteristics: A Bioinformatic Analysis of Two Cohort Studies

Background: Sepsis is well-known to alter innate and adaptive immune responses for sustained periods after initiation by an invading pathogen. Identification of immune cell characteristics may shed light on the immune signature of patients with sepsis and further indicate the appropriate immune-modulatory therapy for distinct populations. Therefore, we aimed to establish an immune model to classify sepsis into different immune endotypes via transcriptomics data analysis of previously published cohort studies.

Methods: Datasets from two observational cohort studies that included 585 consecutive sepsis patients admitted to two intensive care units were downloaded as a training cohort and an external validation cohort. We analyzed genome-wide gene expression profiles in blood from these patients by using machine learning and bioinformatics.

Results: The training cohort and the validation cohort had 479 and 106 patients, respectively. Principal component analysis indicated that two immune subphenotypes associated with sepsis, designated the immunoparalysis endotype, and immunocompetent endotype, could be distinguished clearly. In the training cohort, a higher cumulative 28-day mortality was found in patients classified as having the immunoparalysis endotype, and the hazard ratio was 2.32 (95% CI: 1.53–3.46 vs. the immunocompetent endotype). External validation further demonstrated that the present model could categorize sepsis into the immunoparalysis and immunocompetent type precisely and efficiently. The percentages of 4 types of immune cells (M0 macrophages, M2 macrophages, naïve B cells, and naïve CD4 T cells) were significantly associated with 28-day cumulative mortality (P < 0.05).

Conclusion: The present study developed a comprehensive tool to identify the immunoparalysis endotype and immunocompetent status in hospitalized patients with sepsis and provides novel clues for further targeting of therapeutic approaches.

Sex differences of inflammatory and immune response in pups of Wistar rats with SIRS

It is a common fact, that the content of sex hormones in humans and animals varies in different age periods. The functional state of the immune system also changes with age. However, sex differences studies of inflammatory and immune responses during puberty prevail in literature. Investigation of immune responses to LPS peculiarities in prepubertal females and males may contribute to the development of more effective immunotherapy and minimize side effects of children vaccination. Therefore, the aim of this work was to investigate the LPS-induced SIRS sex differences in prepubertal Wistar rats. Despite the absence of sex differences in estradiol and testosterone levels, LPS-induced inflammatory changes in liver and lungs are more pronounced among males. Males demonstrate the increasing neopterin, corticosterone levels and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Not less important is that in females, demonstrating less morphological changes in liver and lungs, endotoxin level is tenfold higher, and corticosterone level decreases. Thus, endotoxin cannot be used as a marker of the severity of multiple organ failure in prepubertal period. The LPS-induced immune reactions in females and males are similar and are characterized by immunosuppression. Both females and males have decreased production of cytokines (IL-2, IL-4, TNF-α, TGF-β) and the absolute number of CD3 + and CD3 + CD8 + lymphocytes in blood. The acute atrophy of thymus and apoptosis of thymic cells are revealed in animals of both sexes. However, the number of CD3 + CD4 + T-helpers and CD4 + CD25 + Foxp3 + T-cells decreases only in females with SIRS, and in males there was a decrease of CD45R + B-cells. The least expressed sex differences in immune responses in the prepubertal period can be determined by the low levels of sex steroids and the absence of their immunomodulatory effect. Further studies require the identification of mechanisms, determining the sex differences in the inflammatory and immune responses in prepubertal animals.

The Critical Roles and Mechanisms of Immune Cell Death in Sepsis

Sepsis was first described by the ancient Greek physicians over 2000 years ago. The pathophysiology of the disease, however, is still not fully understood and hence the mortality rate is still unacceptably high due to lack of specific therapies. In the last decade, great progress has been made by shifting the focus of research from systemic inflammatory response syndrome (SIRS) to multiple organ dysfunction syndrome (MODS). Sepsis has been re-defined as infection-induced MODS in 2016. How infection leads to MODS is not clear, but what mediates MODS becomes the major topic in understanding the molecular mechanisms and developing specific therapies. Recently, the mechanism of infection-induced extensive immune cell death which releases a large quantity of damage-associated molecular patterns (DAMPs) and their roles in the development of MODS as well as immunosuppression during sepsis have attracted much attention. Growing evidence supports the hypothesis that DAMPs, including high-mobility group box 1 protein (HMGB1), cell-free DNA (cfDNA) and histones as well as neutrophil extracellular traps (NETs), may directly or indirectly contribute significantly to the development of MODS. Here, we provide an overview of the mechanisms and consequences of infection-induced extensive immune cell death during the development of sepsis. We also propose a pivotal pathway from a local infection to eventual sepsis and a potential combined therapeutic strategy for targeting sepsis.

T-Bet Expression Mediated by the mTOR Pathway Influences CD4+ T Cell Count in Mice With Lethal Candida Sepsis

The sustained high morbidity and mortality of Candida sepsis are mainly caused by compromise of host immunity. Clinically, it is often manifested as a significant decrease in CD4+ T cell count, although the mechanism is unclear. We established a lethal mice Candida sepsis model and used Murine Sepsis Score to group mice with different disease severity to establish the influence of T-bet expression on CD4+ T cell count in Candida sepsis. We found that CD4+ T cell count decreased in Candida-infected compared to uninfected mice, and the degree of decrease increased with aggravation of sepsis. Expression of T-bet similarly decreased with worsening of sepsis, but it was significantly enhanced in candidiasis in comparison of naïve state. To clarify its possible mechanism, we measured the activity of mammalian target of rapamycin (mTOR), which is a key regulator of T-bet expression. The mTOR pathway was activated after infection and its activity increased with progression of sepsis. We used mice with T-cell-specific knockout of mTOR or tuberous sclerosis complex (TSC)1 to further inhibit or strengthen the mTOR signaling pathway. We found that mTOR deletion mice had a higher CD4+ T cell count by regulating T-bet expression, and the result in TSC1 deletion mice was reversed. These results demonstrate that T-bet expression mediated by the mTOR pathway influences the CD4+ T cell count in mice with Candida sepsis.

Sepsis-associated encephalopathy: a vicious cycle of immunosuppression

Sepsis-associated encephalopathy (SAE) is commonly complicated by septic conditions, and is responsible for increased mortality and poor outcomes in septic patients. Uncontrolled neuroinflammation and ischemic injury are major contributors to brain dysfunction, which arises from intractable immune malfunction and the collapse of neuroendocrine immune networks, such as the cholinergic anti-inflammatory pathway, hypothalamic-pituitary-adrenal axis, and sympathetic nervous system. Dysfunction in these neuromodulatory mechanisms compromised by SAE jeopardizes systemic immune responses, including those of neutrophils, macrophages/monocytes, dendritic cells, and T lymphocytes, which ultimately results in a vicious cycle between brain injury and a progressively aberrant immune response. Deep insight into the crosstalk between SAE and peripheral immunity is of great importance in extending the knowledge of the pathogenesis and development of sepsis-induced immunosuppression, as well as in exploring its effective remedies.

Dynamic changes in human HLA-DRA gene expression and Th cell subsets in sepsis: Indications of immunosuppression and associated outcomes

BACKGROUND

Sepsis is a life-threatening disease that is an immune disorder response that causes multiple organ dysfunction. In this study, we investigated the dynamic changes in mRNA expression of HLA-DRA gene and the specific transcription factor of helper T cell subsets to explore long-term immunophenotyping and its relationship with prognosis.

METHODS

Seventy-eight sepsis patients and twelve healthy controls were recruited in this study. Blood samples were collected at eight-time points during their septic course and were assayed for the gene expression of HLA-DRA and T helper cell subset-specific transcription factors (T-bet: Th1, GATA3: Th2, Foxp3: Treg, RORC: Th17).

RESULTS

The levels of HLA-DRA in survivors gradually increased but were maintained at lower levels in non-survivors. The specific transcription factor of Th1 and Th2 cells, T-bet and GATA-3 were significantly lower in sepsis patients than in normal controls, and the non-survivors showed significantly lower levels than the survivors (P < .05). RORC and FOXP3, the specific transcription factor of Treg and Th17 were significantly higher in survivors than in non-survivors and normal controls (P < .05). T-bet and GATA-3 had a linear correlation with HLA-DRA expression (P < .01).

CONCLUSIONS

The dynamic changes in HLA-DRA expression in peripheral blood could accurately reflect the immune status of sepsis patients, and the reduction in HLA-DRA may be an important reason for abnormal T cell differentiation. The sustained low levels of the Th cell subsets (Th1 and Th2) suggest the suppression of adaptive immunity, and this persistent immunosuppression may be the leading cause of death in septic patients.

Effects of early enteral nutrition on Th17/Treg cells and IL-23/IL-17 in septic patients

BACKGROUND

The imbalance of Th17/Treg cells and the IL-23/IL-17 axis have been confirmed to be associated with sepsis and various inflammatory diseases. Early enteral nutrition (EEN) can modulate the inflammatory response, improve immune dysfunction, and prevent enterogenic infection in critically ill patients; however, the precise mechanisms remain unclear. Considering the important roles of Th17 and Treg lymphocytes in the development of inflammatory and infectious diseases, we hypothesized that EEN could improve the immune dysfunction in sepsis by maintaining a balanced Th17/Treg cell ratio and by regulating the IL-23/IL-17 axis.

AIM

To investigate the effects of EEN on the Th17/Treg cell ratios and the IL-23/IL-17 axis in septic patients.

METHODS

In this prospective clinical trial, patients were randomly divided into an EEN or delayed enteral nutrition (DEN) group. Enteral feeding was started within 48 h in the EEN group, whereas enteral feeding was started on the 4th day in the DEN group. The Th17 and Treg cell percentages and the interleukin levels were tested on days 1, 3, and 7 after admission. The clinical severity and outcome variables were also recorded.

RESULTS

Fifty-three patients were enrolled in this trial from October 2017 to June 2018. The Th17 cell percentages, Th17/Treg cell ratios, IL-17, IL-23, and IL-6 levels of the EEN group were lower than those of the DEN group on the 7th day after admission (P < 0.05). The duration of mechanical ventilation and of the intensive care unit stay of the EEN group were shorter than those of the DEN group (P < 0.05). However, no difference in the 28-d mortality was found between the two groups (P = 0.728).

CONCLUSION

EEN could regulate the imbalance of Th17/Treg cell ratios and suppress the IL-23/IL-17 axis during sepsis. Moreover, EEN could reduce the clinical severity of sepsis but did not reduce the 28-d mortality of septic patients.

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.

Endotoxin tolerance modulates TREG and TH17 lymphocytes protecting septic mice

Background: Tolerance induces a regulated immune response to infection. We hypothesized that tolerance induction modulated profile of T regulatory cell (Treg) and T lymphocyte 17 (Th17) cells and is related cytokine released in septic animals. Methods: Male black C57/6 mice received subcutaneous (s.c.) injections of lipopolysaccharide (LPS) (1 mg/kg) for 5 days, on day 8^th was made cecal ligation and puncture (CLP). Blood and spleen tissue were collected for cell analysis and cytokines measurements. Results: Cytokines (interleukin 2 (IL-2), interleukin (IL-6), transforming growth factor β (TGF-β) and interferon γ (INF-γ)) related to Treg and Th17 stimulation were elevated in the spleen of tolerant animals compared to sham. Treg and Th17 lymphocytes showed an increased amount in blood (Treg: 920 ± 84 cells vs. 1946 ± 65 cells, sham vs. tolerant; Th17:38321± 1954 cells vs. 43526 ± 7623 cells, sham vs. tolerant) and spleen (Treg: 5947 ± 273 cells vs. 16521 ± 486 cells, sham vs. tolerant; Th17: 26543 ± 2944 cells vs. 64567 ± 5523 cells, sham vs. tolerant). Treg (135±23 cells) and Th17 (1590 ± 256 cells) cells were reduced in blood of septic animals compared to sham, while CLP tolerant animals presented an increasing number of these cells. Lymphocyte Th17IL6+ were elevated in tolerant and CLP tolerant animals in the blood compared to sham. Conclusion: LPS tolerance was associated with increasing population of Treg and Th17. LPS tolerance reduces the hyper inflammatory response with immunoregulation exerted by Treg and Th17 cells protecting from septic damage.

Prognostic Relevance of Altered Lymphocyte Subpopulations in Critical Illness and Sepsis

Lymphopenia and functional defects in lymphocytes may impact the prognosis in patients with critical illness or sepsis. Therefore, we prospectively analyzed peripheral blood leukocytes from 63 healthy volunteers, 50 non-critically ill standard care (SC) patients with infections, and 105 intensive care unit (ICU) patients (52 with sepsis, 53 without sepsis) using flow cytometry. Compared to healthy volunteers, SC and ICU patients showed significant leukocytosis, especially in sepsis, while lymphocyte numbers were significantly decreased. All major lymphocyte populations (B, T, and natural killer (NK) cells) decreased in ICU patients. However, we observed a relative reduction of T cells, alongside decreased CD8+ T cells, in critically ill patients, independent of sepsis. High absolute T cell counts (>0.36/nL) at ICU admission were associated with a significantly reduced mortality, independent of patient’s age. Moreover, patients that survived ICU treatment showed dynamic changes within 48 h towards restoration of lymphopenia and T cell depletion, while non-surviving patients failed to restore lymphocyte counts. In conclusion, the flow-cytometric analysis of peripheral blood revealed striking changes in circulating lymphocyte subsets in critically ill patients, independent of sepsis. Lymphopenia and T cell depletion at ICU admission were associated with increased mortality, supporting their relevance as predictive biomarkers and potential therapeutic targets in intensive care medicine.

Early and dynamic alterations of Th2/Th1 in previously immunocompetent patients with community-acquired severe sepsis: a prospective observational study

BACKGROUND

T helper (Th) cells regulate sepsis processes, including primary pathogen clear and secondary pathogen defence. The objectives of this study were to determine the early and dynamic alterations of Th1 and Th2 populations to community-acquired severe sepsis upon onset among previously immunocompetent patients and whether it was related to clinical outcomes.

METHODS

This prospective observational cohort study was conducted at a general intensive care unit (ICU) of a tertiary teaching hospital in China. Immunocompetent patients with community-acquired severe sepsis within 24 h upon onset were included as septic group. Healthy volunteers and critically ill patients without severe sepsis were recruited as controls. Whole blood was collected on D0, 3rd day (D3) and 7th day (D7) for septic group and once upon enrollment for controls. Th1 and Th2 populations were measured by flow cytometry and assessed for associations with 28-day mortality using cox proportional hazard models. Associations of dynamic alterations of Th cell subpopulations with clinical outcomes were investigated.

RESULTS

This study demonstrated that community-acquired severe sepsis patients (n = 71) had increased Th2/Th1 and Th2 populations, compared to healthy controls (n = 7) and critically ill patients without severe sepsis (n = 7) at admission. Among the septic cohort, values of Th2/Th1 were significantly higher in non-survivors than survivors on D0 (p = 0.04), D3 (p < 0.001) and D7 (p < 0.001). Patients with persistently increasing Th2/Th1 demonstrated the highest mortality (47.1%) and incidence of ICU-acquired infections (64.7%).

CONCLUSIONS

Th2/Th1 was markedly up-regulated with Th2 dominance upon community-acquired severe sepsis onset among previously immunocompetent patients and its persistently dynamic increase was associated with ICU-acquired infections and 28-day death. Trial registration Institutional Ethics Committee of Zhongda Hospital, 2014ZDSYLL086, registered in June 2014-prospectively registered; ClinicalTrials.gov, NCT02883218, registered on 25 Aug 2016-retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT02883218?cond=NCT02883218&rank=1.

Tanshinone IIA attenuates sepsis-induced immunosuppression and improves survival rate in a mice peritonitis model

BACKGROUND

The importance of sepsis-induced immunosuppression and its contribution to mortality has recently emerged. In this study we examined the effects of Tanshinone II-A (TSN), a widely used traditional Chinese medicine, on immunosuppression in experimental peritonitis induced septic mice.

MATERIALS AND METHODS

Sepsis was achieved by means of cecal ligation and puncture (CLP). TSN at different doses (5, 15 and 45 mg/kg, i.p.) were used at different time-points (0, 3, 6 and 12 h) after CLP to evaluate its effect on the survival of septic mice. In parallel experiments, mice given TSN at optimal dose and time-point were euthanized to collect peritoneal macrophages, blood and tissue samples at 24 h after the CLP.

RESULTS

TSN improved the survival of septic mice in a dose- and time-dependent manner. TSN reduced CLP-induced serum biochemical parameters and protected organs from histopathological injuries. CLP-induced apoptosis and decreased percentages of splenic CD4⁺ and CD8⁺ T cells were reversed in TSN-treated mice. Moreover, CLP-induced formation of regulatory T cells (Treg) in the spleen was abolished in TSN-treated mice. CLP greatly decreased the levels of interferon-γ and interleukin (IL)-2 in the spleen, while the levels of IL-4 and IL-10 increased after CLP. TSN completely reversed these alterations and elicited a more-balanced Th1/Th2 response. Moreover, TSN promoted macrophage phagocytotic activity and improved bacterial clearance of septic mice. Lastly, TSN abolished CLP-triggered increase in serum HMBG1 level. And HMGB1 neutralization could increase the percentages of splenic CD3+CD4+/CD3+CD8+ lymphocytes and decreased the Treg population.

CONCLUSIONS

Overall, our data suggest that TSN exerts immune modulatory effect and might be a useful strategy to ameliorate immunosuppression in polymicrobial sepsis.

Sepsis and Nosocomial Infection: Patient Characteristics, Mechanisms, and Modulation

Sepsis is a leading cause of death worldwide. After initial trials modulating the hyperinflammatory phase of sepsis failed, generations of researchers have focused on evaluating hypo-inflammatory immune phenotypes. The main goal has been to develop prognostic biomarkers and therapies to reduce organ dysfunction, nosocomial infection, and death. The depressed host defense in sepsis has been characterized by broad cellular reprogramming including lymphocyte exhaustion, apoptosis, and depressed cytokine responses. Despite major advances in this field, our understanding of the dynamics of the septic host response and the balance of inflammatory and anti-inflammatory cellular programs remains limited. This review aims to summarize the epidemiology of nosocomial infections and characteristic immune responses associated with sepsis, as well as immunostimulatory therapies currently under clinical investigation.

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.

Persistent accumulation of circulating monocytic myeloid-derived suppressor cells contributes to post-infectious immunosuppression in renal transplant recipients with bacterial infection: A pilot study

INTRODUCTION

Post-infectious immunosuppression is disadvantageous to patients' long-term outcomes, especially in transplant recipients receiving large doses of immunosuppressants. A growing body of evidence indicates the immunoregulatory ability of myeloid-derived suppressor cells (MDSCs). We herein investigate the characteristics of monocytic-MDSCs (M-MDSCs) in a cohort of renal transplant recipients with/without infection to clarify the potential involvement in post-infectious immunosuppression.

METHODS

The study prospectively included 28 adult recipients who underwent allogeneic ABO-compatible renal transplant. Blood samples were drawn at day 0, 7, 14, 28, 60 and 90 postoperation. The incidence of infection and treatment strategies were recorded. The frequency and absolute number of peripheral blood M-MDSCs as well as other immune cells were determined by flow cytometry. Immnosuppressive functions of M-MDSCs were analyzed by inhibition of T cells proliferation. mRNA levels of immunosuppressive molecules in sorted M-MDSCs were also examined.

RESULTS

7 recipients were diagnosed with bacterial (n = 5) or viral (n = 2) infection and 3/5 of bacterial-infected recipients suffered from secondary infection during further follow-up. In the non-infected group, M-MDSCs numbers increased transiently during the early postoperative period, however, bacterial but not viral infection led to significant and persistent accumulation of M-MDSCs that remained at high levels after anti-infective treatments. M-MDSCs from infected recipients demonstrated potent ability to suppress T cells proliferation in vitro and negatively correlated with lymphocytes in vivo, yet not in the non-infected group. Inducible nitric oxide synthase (iNOS) mRNA levels were higher in sorted M-MDSCs when compared with monocytes, and suppressive activity was reversed by addition of a NOS inhibitor.

CONCLUSIONS

Circulating M-MDSCs underwent significant and persistent increases after bacterial infection in renal transplant recipients, contributing to post-infectious immunodeficiency. Therefore, special attention should be given to M-MDSCs during the monitoring of immune status and infection management.

Diabetes and Sepsis: Risk, Recurrence, and Ruination

Sepsis develops when an infection surpasses local tissue containment. A series of dysregulated physiological responses are generated, leading to organ dysfunction and a 10% mortality risk. When patients with sepsis demonstrate elevated serum lactates and require vasopressor therapy to maintain adequate blood pressure in the absence of hypovolemia, they are in septic shock with an in-hospital mortality rate >40%. With improvements in intensive care treatment strategies, overall sepsis mortality has diminished to ~20% at 30 days; however, mortality continues to steadily climb after recovery from the acute event. Traditionally, it was thought that the complex interplay between inflammatory and anti-inflammatory responses led to sepsis-induced organ dysfunction and mortality. However, a closer examination of those who die long after sepsis subsides reveals that many initial survivors succumb to recurrent, nosocomial, and secondary infections. The comorbidly challenged, physiologically frail diabetic individuals suffer the highest infection rates. Recent reports suggest that even after clinical "recovery" from sepsis, persistent alterations in innate and adaptive immune responses exists resulting in chronic inflammation, immune suppression, and bacterial persistence. As sepsis-associated immune defects are associated with increased mortality long-term, a potential exists for immune modulatory therapy to improve patient outcomes. We propose that diabetes causes a functional immune deficiency that directly reduces immune cell function. As a result, patients display diminished bactericidal clearance, increased infectious complications, and protracted sepsis mortality. Considering the substantial expansion of the elderly and obese population, global adoption of a Western diet and lifestyle, and multidrug resistant bacterial emergence and persistence, diabetic mortality from sepsis is predicted to rise dramatically over the next two decades. A better understanding of the underlying diabetic-induced immune cell defects that persist following sepsis are crucial to identify potential therapeutic targets to bolster innate and adaptive immune function, prevent infectious complications, and provide more durable diabetic survival.

The immune system's role in sepsis progression, resolution, and long-term outcome

Sepsis occurs when an infection exceeds local tissue containment and induces a series of dysregulated physiologic responses that result in organ dysfunction. A subset of patients with sepsis progress to septic shock, defined by profound circulatory, cellular, and metabolic abnormalities, and associated with a greater mortality. Historically, sepsis-induced organ dysfunction and lethality were attributed to the complex interplay between the initial inflammatory and later anti-inflammatory responses. With advances in intensive care medicine and goal-directed interventions, early 30-day sepsis mortality has diminished, only to steadily escalate long after "recovery" from acute events. As so many sepsis survivors succumb later to persistent, recurrent, nosocomial, and secondary infections, many investigators have turned their attention to the long-term sepsis-induced alterations in cellular immune function. Sepsis clearly alters the innate and adaptive immune responses for sustained periods of time after clinical recovery, with immune suppression, chronic inflammation, and persistence of bacterial representing such alterations. Understanding that sepsis-associated immune cell defects correlate with long-term mortality, more investigations have centered on the potential for immune modulatory therapy to improve long-term patient outcomes. These efforts are focused on more clearly defining and effectively reversing the persistent immune cell dysfunction associated with long-term sepsis mortality.

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.

High Interleukin-10 Expression in Type 2 T Helper Cells in Septic Patients

Interleukin (IL)-10 response is associated with mortality in patients with sepsis. IL-10 is primarily produced by monocytes and type 2 T helper (Th2) cells. The aim of this study was to investigate differences in IL-10 production between monocytes and Th2 cells in patients with sepsis. Forty patients with sepsis and 35 healthy controls were enrolled. Cytokine expressions in peripheral blood mononuclear cells (PBMCs) were measured by flow cytometry. The IL-10 expression in the Th2 cells of the septic patients was higher than in the healthy controls, but the expression of IL-10 in the monocytes of the septic patients was lower than in the healthy controls. After regression analysis, IL-10 expression in Th2 cells was positively associated with sepsis, but IL-10 expression in monocytes was not associated with sepsis or shock. In conclusion, the production of IL-10 in Th2 cells was higher in the patients with sepsis.

Alterations of T helper lymphocyte subpopulations in sepsis, severe sepsis, and septic shock: a prospective observational study

Circulating lymphocyte number was significantly decreased in patients with sepsis. However, it remains unknown which severity phase (sepsis, severe sepsis, and septic shock) does it develop and what happen on each subpopulation. Eight patients with differing severities of sepsis (31 sepses, 33 severe sepses, and 16 septic shocks) were enrolled. Quantitative real-time polymerase chain reaction (RT-PCR) of Th1, Th2, and Th17; regulatory T (Treg) cell-specific transcription factor T-bet; GATA-3; RORgammat (RORγt); forkhead box P3 (FOXP3); and IL-17 mRNA were performed, and the enzyme-linked immunosorbent assay (ELISA) was used to detect serum interferon (IFN)-γ, IL-4, and IL-10. In this study, the Th1, Th2, Treg transcription factors, and related cytokines IFN-γ, IL-4, and IL-10 levels of sepsis and severe sepsis patients in peripheral blood were significantly higher than those of the normal controls. Except for IL-17, the T-bet, GATA-3, and IFN-γ levels of septic shock patients were lower than those of sepsis patients. We also observed that the proportions of Th17/Treg in the sepsis and septic shock groups were inversed. From the above, the inflammatory response especially the adaptive immune response is still activated in sepsis and severe sepsis, but significant immunosuppression was developed in septic shock. In addition, the proportion of Th17/Treg inversed may be associated with the illness aggravation of patients with sepsis.

Liver Cirrhosis and Diabetes Mellitus Are Risk Factors for Staphylococcus aureus Infection in Patients with Healthcare-Associated or Hospital-Acquired Pneumonia

Background. The risk factors for Staphylococcus aureus (S. aureus) pneumonia are not fully identified. The aim of this work was to find out the clinical characteristics associated with S. aureus infection in patients with healthcare-associated pneumonia (HCAP) and hospital-acquired pneumonia (HAP), which may be applicable for more appropriate selection of empiric antibiotic therapy. Methods. From July 2007 to June 2010, patients who were admitted to the intensive care unit with severe HCAP/HAP and severe sepsis were enrolled in this study. Lower respiratory tract sample was semiquantitatively cultured. Initial broad-spectrum antibiotics were chosen by Taiwan or American guidelines for pneumonia management. Standard bundle therapies were provided to all patients according to the guidelines of the Surviving Sepsis Campaign. Results. The most frequently isolated pathogens were Pseudomonas aeruginosa, S. aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. Patients with positive isolation of S. aureus in culture had significantly higher history of liver cirrhosis and diabetes mellitus, with odds ratios of 3.098 and 1.899, respectively. The S. aureus pneumonia was not correlated with history of chronic obstructive pulmonary disease, hypertension, and hemodialysis. Conclusion. Liver cirrhosis and diabetes mellitus may be risk factors for S. aureus infection in patients with severe HCAP or HAP.

Catecholamines for inflammatory shock: a Jekyll-and-Hyde conundrum

Catecholamines are endogenous neurosignalling mediators and hormones. They are integral in maintaining homeostasis by promptly responding to any stressor. Their synthetic equivalents are the current mainstay of treatment in shock states to counteract myocardial depression and/or vasoplegia. These phenomena are related in large part to decreased adrenoreceptor sensitivity and altered adrenergic signalling, with resultant vascular and cardiomyocyte hyporeactivity. Catecholamines are predominantly used in supraphysiological doses to overcome these pathological consequences. However, these adrenergic agents cause direct organ damage and have multiple 'off-target' biological effects on immune, metabolic and coagulation pathways, most of which are not monitored or recognised at the bedside. Such detrimental consequences may contribute negatively to patient outcomes. This review explores the schizophrenic 'Jekyll-and-Hyde' characteristics of catecholamines in critical illness, as they are both necessary for survival yet detrimental in excess. This article covers catecholamine physiology, the pleiotropic effects of catecholamines on various body systems and pathways, and potential alternatives for haemodynamic support and adrenergic modulation in the critically ill.

Sepsis-induced immune dysfunction: can immune therapies reduce mortality?

Sepsis is a systemic inflammatory response induced by an infection, leading to organ dysfunction and mortality. Historically, sepsis-induced organ dysfunction and lethality were attributed to the interplay between inflammatory and antiinflammatory responses. With advances in intensive care management and goal-directed interventions, early sepsis mortality has diminished, only to surge later after "recovery" from acute events, prompting a search for sepsis-induced alterations in immune function. Sepsis is well known to alter innate and adaptive immune responses for sustained periods after clinical "recovery," with immunosuppression being a prominent example of such alterations. Recent studies have centered on immune-modulatory therapy. These efforts are focused on defining and reversing the persistent immune cell dysfunction that is associated with mortality long after the acute events of sepsis have resolved.

HS-23, a Lonicera japonica extract, reverses sepsis-induced immunosuppression by inhibiting lymphocyte apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Lonicera japonica Thunberg, a widely used traditional Chinese medicine, possesses antibacterial, antiviral, and antiendotoxin activities. This study investigated the molecular mechanisms of HS-23, the ethanol extract of the dried flower buds of L. japonica, on sepsis-induced immunosuppression.

MATERIALS AND METHODS

Male ICR mice were intravenously administered HS-23 (10, 20, and 40mg/kg) immediately (0h) and 22h after cecal ligation and puncture (CLP). The spleen was isolated for biochemical assays 24h after CLP.

RESULTS

HS-23 improved sepsis-induced mortality. CLP induced a marked decrease in the number of splenocytes, B cells, and natural killer cells, which was attenuated by HS-23. HS-23 also attenuated CLP-induced apoptosis in CD4(+) and CD8(+) T cells and inhibited both the intrinsic and extrinsic apoptotic pathway in the spleen. HS-23 attenuated the CLP-induced decrease in interleukin (IL)-17 production. CLP significantly decreased splenic production of tumor necrosis factor-α and IL-2, and these effects were attenuated by HS-23.

CONCLUSION

Our findings suggest that HS-23 reverses immunosuppression during the late phase of sepsis by inhibiting lymphocyte apoptosis and enhancing Th1 cytokine production. HS-23 warrants further evaluation as a potential therapeutic agent for the treatment of sepsis.

Calcium-sensing receptor in the T lymphocyte enhanced the apoptosis and cytokine secretion in sepsis

Calcium-sensing receptor (CaSR) is a member of the G protein-coupled receptor superfamily that existed in lymphocytes and promoted cytokine secretion. Lymphocytes are also involved in sepsis. However, the role of CaSR in lymphocytes in sepsis is unclear. In this study, we want to examine whether the CaSR in lymphocytes in sepsis is involved in the cytokine secretions and apoptosis and make clear the relationship between NF-κB and MAPK signal transduction pathways. We investigated the issues mentioned earlier using Western blotting, ELISA, and Flow Cytometry. The sepsis was remodeled by cecal ligation and puncture (CLP). We found that CaSR protein expression increased in the peripheral blood T lymphocytes in CLP rats. The calcimimetic R568 (NPS R568) promoted, whereas the calcilytic NPS 2143 attenuated, signaling pathways proteins P65 (subunit of NF-κB), ERK1/2, and JNK (one subgroup of MAPKs) phosphorylation. However, P-P38 and P-JAKs exhibit no significant changes. Furthermore, the production TNF-α and IL-4 was greater in CLP rats than in normal rats, and NPS R568 promoted secretion of these cytokines. Simultaneously, the apoptotic ratio of T cells in CLP increased, and NPS R 568 exacerbated the apoptosis degree. However, these effects could also be inhibited by U0126 or SP600125 (MAPKs pathway inhibitor) or Bay-11-7082 or (NF-κB pathway inhibitor). From these results, we can conclude that, in the sepsis, CaSR activation promoted T-cell apoptosis and the secretion of pro-inflammatory cytokine TNF-α and anti-inflammatory cytokines IL-4 probably through NF-κB and partial MAPK signal transduction pathways.