The immunology of sepsis

Transcriptomic analysis of key genes and signaling pathways in sepsis-associated intestinal mucosal barrier damage

OBJECTIVES

The aim is to analyze differentially expressed genes (DEGs) in mice with sepsis-related intestinal mucosal barrier damage and to explore the diagnostic and protective mechanisms of this condition at the transcriptome level.

METHODS

Small intestinal tissues from healthy male C57BL/6J mice subjected to Cecal ligation and puncture (CLP) and sham operation were collected. High-throughput sequencing was performed using the paired-end sequencing mode of the Illumina HiSeq platform. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted on the differentially expressed genes (DEGs). A protein-protein interaction (PPI) network was constructed using the STRING database, and hub genes were identified with Cytoscape. These hub genes were then validated using quantitative real-time polymerase chain reaction (RT-qPCR).

RESULTS

A total of 239 DEGs were identified, with 49 upregulated and 130 downregulated genes. KEGG enrichment analysis showed that these DEGs were primarily involved in cytokine-cytokine receptor interaction, Th1 and Th2 cell differentiation, viral protein interactions with cytokines and their receptors, and the IL-17 signaling pathway. The top 10 hub genes were selected using the cytoHubba plugin. Experimental validation confirmed that the expression levels of TBX21, CSF3, IL-6, CXCR3, and CXCL9 matched the sequencing results.

CONCLUSION

TBX21, CSF3, IL-6,CXCR3, and CXCL9 may be potential biological markers for the diagnosis and treatment the sepsis-associated intestinal mucosal barrier.

Hospital readmission after surviving sepsis: A systematic review of readmission reasons and meta-analysis of readmission rates

PURPOSE

To review the evidence regarding hospital readmission diagnoses and analyse related readmission rates following a sepsis admission.

METHODS

Five databases, grey literature, and selected article reference lists were searched in May and June 2024. Included studies investigated sepsis survivor readmissions and reported readmission diagnoses and rates. Meta-analyses of readmission rates were performed.

RESULTS

After screening, 51 studies were included, with most studies (46/51; 90.2 %) investigating adult survivors. Infection or sepsis were reported as the most common readmission reason in 18 of the 21 studies investigating three or more readmission diagnoses in adults. Meta-analyses showed that 4.7 % (95 % CI: 3.1 to 6.5 %, PI: 0.3-13.4 %, n = 11 studies) of adult survivors readmitted to hospital with another sepsis diagnosis at 30 days, 8.1 % (95 % CI: 4.5 to 12.7 %, PI: <0.1-29.0 %, n = 7) at 90 days, and 16.4 % (95 % CI: 11.3 to 22.2 %, PI: <0.1-96.3 %, n = 3) at one year. At 30 days 3.5 % (95 % CI: 2.2-5.0 %, PI: 0.3-10.0 %, n = 7) of adult survivors readmitted to hospital with a cardiovascular disease diagnosis.

CONCLUSIONS

Infection and sepsis are frequent readmission diagnoses for sepsis survivors, with one in 21 adult survivors readmitted for sepsis at 30-days. PROSPERO registration: CRD42023455851.

Immunomodulatory effects and multi-omics analysis of Codonopsis Pilosula Extract in septic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Codonopsis Pilosula (CP), as a well-known traditional Chinese medicine (TCM) with medicinal and edible herb, is one of the most representative tonic Chinese herbal medicine. It has been widely used for regulating immune function with hardly any adverse effects in clinical practice.

AIM OF THE STUDY

This study aimed to elucidate the immunomodulatory effect and to explore probable mechanism of Codonopsis Pilosula Extract (CPE) in septic rats.

MATERIALS AND METHODS

The model of septic rat was established by cecal ligation and perforation (CLP). The thymus index, spleen index and cerebral index were calculated. Histological changes were observed by Hematoxylin-eosin (HE). The positive expression of CD4+ T cells was determined in the thymus and spleen by immunohistochemical (IHC). The expression level of 24 h CD4 was corroborated by real-time quantitative polymerase chain reaction (RT-QPCR). Infectious factors, immune factors and inflammatory factors were determined by enzyme-linked immunosorbent assay (ELISA). Blood cells were detected by automatic biochemical analyzer. The metabolite changes and gene expression levels, the potential targets and pathways of CPE in regulating immune function of thymus were analyzed by integrative analysis of transcriptomic and metabolomic methods.

RESULTS

High dose of CPE increased the thymus index and spleen index of septic rats at different stages, and the brain index at different stages could be increased at medium dose and high dose. Medium and high doses of CPE reduced the pathological changes of thymus, spleen and brain tissue. CPE promoted the expression levels of CD4 in the thymus and spleen. CPE improved the levels of red blood cells (RBC), lymphocytes (LYM) and hemoglobin (HGB), and decreased the levels of neutrophils (NEUT), NLR (NEUT/LYM) and PLR (PLT/LYM). CPE dynamically regulated the levels of white blood cells (WBC) and PLT (platelet). CPE dynamically regulated the expression levels of infectious factors, immune factors, and inflammatory factors related to disease severity.

CONCLUSION

CPE has the ability to dynamically modulate the expression levels of infectious factors, immune factors, and inflammatory factors related to disease severity, and alleviate the damages of immune organs. The research has provided a global view of the integration of metabolomics and transcriptomics to elucidate the immunomodulatory effects and mechanisms of CPE. CPE could affect a series of biological processes in glycerophospholipid metabolism by interfering with the B cell receptor (BCR) signaling pathway in the thymus, to maintain immune homeostasis of septic rats on the whole, especially humoral immunity.

In vivo and in vitro study on the regulatory mechanism of XiaoChaiHu decoction on PANoptosis in sepsis-induced cardiomyopathy

ETHNOPHARMACOLOGICAL RELEVANCE

In accordance with the tenets of traditional Chinese medicine, sepsis is categorized into three distinct syndromes: heat syndrome, blood stasis syndrome, and deficiency syndrome. Xiaochaihu decoction (XCHD) has many functions, including the capacity to protect the liver, cholagogue, antipyretic, anti-inflammatory, and anti-pathogenic microorganisms. XCHD exerts the effect of clearing heat and reconciling Shaoyang. The XCHD contains many efficacious active ingredients, yet the mechanism of sepsis-induced cardiomyopathy (SIC) remains elusive.

AIM OF THE STUDY

To investigate the molecular mechanisms underlying the protective effects of XCHD against SIC using an integrated approach combining network pharmacology and molecular biology techniques.

MATERIALS AND METHODS

Network pharmacology methods identified the active ingredients, target proteins, and pathways affected by XCHD in the context of SIC. We conducted in vivo experiments using mice with lipopolysaccharide-induced SIC, evaluating cardiac function through echocardiography and histology. XCHD-containing serum was analyzed to determine its principal active components using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The effects of XCHD-containing serum on SIC were further tested in vitro in LPS-treated H9c2 cardiac cells. Protein expression levels were quantified via Western blotting and enzyme-linked immunosorbent assay (ELISA). Additionally, molecular docking was performed between the active components and ZBP1, a potential target protein. Overexpression of ZBP1 in H9c2 cells allowed for a deeper exploration of its role in modulating SIC-associated gene expression.

RESULTS

UPLC-MS/MS identified 31 shared XCHD and XCHD-containing serum components. These included organic acids, terpenoids, and flavonoids, which have been identified as the active components of XCHD. Our findings revealed that XCHD alleviated LPS-induced myocardial injury, improved cardiac function, and preserved cardiomyocyte morphology in mice. In vitro studies, we demonstrated that XCHD-containing serum significantly suppressed the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-α) in LPS-induced H9c2 cells. Mechanistic investigations showed that XCHD downregulated genes associated with PANoptosis, a novel cell death pathway, suggesting its protective role in sepsis-damaged hearts. Conversely, overexpression of ZBP1 abolished the protective effects of XCHD and amplified PANoptosis-related gene expression.

CONCLUSIONS

Our study provides the first evidence supporting the protective effects of XCHD against SIC, both in vitro and in vivo. The underlying mechanism involves the inhibition of ZBP1-initiated PANoptosis, offering new insights into treating SIC using XCHD.

Melatonin attenuates sepsis-induced muscle atrophy by regulating the PI3K/Akt signaling pathway

BACKGROUND

In intensive care units, sepsis-related muscle atrophy is a severe complication of numerous diseases, yet the underlying mechanism and potential therapeutic options remain elusive. Recent research has identified melatonin as a promising candidate for attenuating organ dysfunction triggered by sepsis.

METHODS

We used in vitro and in vivo models to simulate sepsis, C2C12 myotubes were treated with LPS, and the mice underwent cecal ligation and puncture (CLP) surgery. Following a pretreatment regimen involving melatonin and the AKT inhibitor MK-2206 2HCl, we analyzed changes in p-Akt and MuRF1 protein levels, fiber cross-sectional areas, and myotube diameters. The analyses included RNA sequencing, Western blotting, qRT-PCR, and immunofluorescence staining.

RESULTS

Activation of the PI3K/Akt pathway in skeletal muscle occurred 24 h post-CLP surgery in mice. This was accompanied by upregulated MuRF1 expression and reduced muscle fiber cross-sectional area, which culminated in muscle atrophy. However, these detrimental effects were attenuated when the mice were pretreated with melatonin via intraperitoneal injection for seven consecutive days. Similarly, LPS treatment of C2C12 myotubes activated the PI3K/Akt pathway, elevated MuRF1 expression, and markedly reduced myotube diameter after 48 h, leading to muscle atrophy. Pretreatment of C2C12 myotubes with melatonin 24 h in advance mitigated these adverse effects. However, cotreatment of C2C12 myotubes with melatonin and MK-2206 2HCl attenuated the beneficial effects of melatonin.

CONCLUSION

Melatonin can attenuate sepsis-induced muscle atrophy by regulating the PI3K/Akt pathway.

Affinity-based 3D-printed microfluidic chip for clinical sepsis detection with CD69, CD64, and CD25

Sepsis is a life-threatening immune response to infection in the body, eventually resulting in fatal organ failure. Current methods utilize blood cultures and quick-Sequential-Organ-Failure-Assessment (qSOFA), but there is a need for more accurate and time-sensitive diagnostic methods to improve survival rates. We present a 3D-printed microfluidic chip that bioconjugates antibodies CD69, CD64, and CD25 to channel surfaces to capture sepsis cells in blood samples and validate it with clinical samples (n = 125 septic, n = 10 healthy). Other variables were taken such as healthy volunteer blood samples and patient demographics to validate and confirm our device's diagnostic ability. Statistical differences were found between healthy volunteer and sepsis patient antigen cell counts (CD69 p-value < 0.001, CD64 p-value < 0.004, CD25 p-value < 0.0009), and were confirmed using principal component analysis. Demographics such as length of stay, age, culture results, and need for surgery also factored into sepsis detection on a smaller scale than the antigen cell counts. The receiver operating characteristic (ROC) analysis showed an area under the curve (AUC) of 0.989, 0.988, and 0.992 for CD69, CD64, and CD25, respectively, and a combined biomarker panel of 0.997. Overall, the device performed within a shorter time frame of 4 h compared to standard blood culture tests and was validated for use in detecting sepsis in patients.

A novel classical machine learning framework for early sepsis prediction using electronic health record data from ICU patients

Sepsis, a life-threatening condition triggered by the body's response to infection, remains a significant global health challenge, annually affecting millions in the United States alone with substantial mortality and healthcare costs. Early prediction of sepsis is critical for timely intervention and improved patient outcomes. This study introduces an innovative predictive model leveraging machine learning techniques and a specific data-splitting approach on highly imbalanced electronic health records (EHRs). Using PhysioNet/CinC Challenge 2019 data from 40,336 patients, including vital signs, lab values, and demographics. Preliminary assessments using classical and stacked ML models with Synthetic Minority Oversampling Technique (SMOTE) augmentation were conducted, showing improved performance. It is found that stacking ML models enhances overall accuracy but faces limitations in precision, recall, and F1 score for positive class prediction. A novel data-splitting approach with 5-fold cross-validation and SMOTE and COPULA augmentation techniques demonstrated promise, with F1 scores ranging from 93 % to 94 % using the COPULA technique. COPULA excelled at predictions for different hours' onsets compared to the SMOTE technique. The proposed model outperformed existing studies, suggesting clinical viability for early sepsis prediction.

Cath-HG improves the survival rates and symptoms in LPS-induced septic mice due to its multifunctional properties

The clinical syndrome of sepsis arises from severe infection, triggering an abnormal immune response that can lead to multiple organ dysfunction and ultimately the death of the host. Current therapies for sepsis are often limited in efficacy and fail to target the complex interplay of infection, inflammation and coagulation, leading to high mortality rates, which underscores the urgent need for novel therapeutics to combat sepsis. We previously identified Cath-HG, a compound capable of alleviating platelet dysfunction by suppressing GPVI-mediated platelet activation, thereby improving the survival of septic mice subjected to cecal ligation and puncture. Here, we further explored the antimicrobial, anti-inflammatory, LPS-neutralizing and anticoagulant properties of Cath-HG, as well as its protective effects in LPS-induced septic mice. Our results demonstrated that Cath-HG can bind to LPS, aggregate bacteria, and disrupt bacterial cell membranes, subsequently resulting in microbial death. Unlike most other Cathelicidins, Cath-HG displayed anticoagulation properties by regulating the enzymes plasmin, thrombin, β-tryptase, chymase and tissue plasminogen activator. In septic mice, Cath-HG provided protection against sepsis induced by LPS injection and exhibited bactericidal killing, LPS neutralization and inhibition of coagulation and MAPK signal transduction. Furthermore, Cath-HG obviously reduced the expression of pro-inflammatory cytokines and improved the pathological manifestations of tissue injury across multiple organs. Thus, Cath-HG emerges as a promising drug candidate for protecting against sepsis.

The VDR/FFAR2 axis mitigates sepsis-induced lung injury by suppressing macrophage lipid peroxidation

Sepsis-induced lung injury is a common critical condition in clinical practice, characterized by the accumulation of peroxides and inflammatory damage caused by excessive macrophage activation. Currently, effective treatments for sepsis-induced lung injury are lacking. Short-chain fatty acid receptor FFAR2 serves as an anti-inflammatory biomarker, but its role and mechanism in sepsis-induced lung injury remain unclear. To elucidate the influence and mechanism of FFAR2 on macrophage lipid peroxidation levels in sepsis-induced lung injury, this study conducted bioinformatics analysis and cellular experiments using the THP-1 macrophage cell line. By dual luciferase reporter and chromatin immunoprecipitation-quantitative PCR assays, it is confirmed that the transcription factor VDR upregulates FFAR2 expression in macrophages by binding to the promoter region -1695 ∼ 1525, thereby increasing the expression of iron death negative regulatory molecules and lowering macrophage lipid peroxidation levels. Moreover, both in vitro using THP-1 cells and bone marrow-derived macrophages (BMDMs) and in vivo using an LPS-induced septic mice model experiments revealed that activating the VDR/FFAR2 axis could reduce inflammation-induced macrophage lipid peroxide accumulation and alleviate lung injury in septic mice. This finding highlights the potential of FFAR2 as an immunotherapeutic target for mitigating sepsis-related lung injury.

Tim-3 pathway dysregulation and targeting in sepsis-induced immunosuppression

Sepsis is a major medical problem which causes millions of deaths worldwide every year. The host immune response in sepsis is characterized by acute inflammation and a simultaneous state of immunosuppression. In the later stage of sepsis, immunosuppression is a crucial factor that increases the susceptibility of septic patients to secondary infection and mortality. It is characterized by T cell exhaustion, excessive production of anti-inflammatory cytokines, hyperproliferation of immune suppressor cells and aberrant expression of immune checkpoint molecules. T cell immunoglobulin and mucin domain 3 (Tim-3), an immune checkpoint molecule, is found on the surface of various cells, including macrophages, NK cells, NKT cells, and T cells. There are four different ligands for Tim-3, and accumulating evidence indicates that Tim-3 and its ligands play a crucial role in regulating immune cell dysfunction during sepsis. Anti-Tim-3 antibodies have been applied in the field of cancer immunotherapy and have achieved positive therapeutic effects in some clinical trials. However, the therapeutic efficacy of Tim-3 blockade is still controversial in animal models of sepsis. These challenges highlight the need for a deeper understanding of Tim-3 signaling in sepsis. This review examines the comprehensive effect of Tim-3 signaling in the development of sepsis-induced immunosuppression and the therapeutic efficacy of Tim-3 blockade.

Continuous Biosensing to Monitor Acute Systemic Inflammation, a Diagnostic Need for Therapeutic Guidance

Continuous monitoring of acute inflammation can become a very important next step for guiding therapeutic interventions in severely ill patients. This Perspective discusses the current medical need for patients with acute inflammatory diseases and the potential of continuous biosensing technologies. First, we discuss biomarkers that could help to monitor the state of a patient with acute systemic inflammation based on theoretical studies and empirical data. Then, based on the state of the art, we describe sensing strategies that could be applied for the continuous monitoring of acute inflammatory biomarkers, followed by challenges that must be overcome. Nanoswitch-based continuous biosensors enable suitable measurement frequencies but still lack sensitivity, while regeneration risks lower sensor reliability. Developments are still needed in bioreceptors and molecular architectures, regeneration techniques, combined with suitable sampling and sample pretreatment methods, for bringing continuous biosensing of inflammation closer to reality. Furthermore, collaborations between healthcare professionals and scientists, regulatory bodies, and biosensor engineers are needed for a successful translation of sensing technologies from the laboratory to clinical practice.

Anti-sepsis effects of Dahuang Mudan decoction and its disassembled prescriptions

ETHNOPHARMACOLOGICAL RELEVANCE

Dahuang Mudan decoction (DMD) is a traditional Chinese prescription from Zhang Zhongjing's Synopsis of the Golden Chamber. In clinical practice, it is often used in the treatment of infectious diseases.

AIM OF THE STUDY

To assess the therapeutic effect of DMD and its disassembled prescriptions on septic mice, and explore its potential mechanism.

MATERIALS AND METHODS

Cecal ligation and puncture (CLP) sepsis and endotoxemia mice models were established. The effects of DMD, its disassembled prescriptions and active compounds were studied. Xuebijing injection (XBJ) was used as positive drug. Mice 7-day survival rates, blood biochemical markers, hematoxylin and eosin (HE) staining and immune cell infiltration were used to evaluate the overall protective effect of the drugs on mice. Inflammatory cytokines and coagulation activation indicators were detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

DMD, its Huoxue prescription, constituent drugs Mudanpi (MDP) and Taoren (TR) significantly protected mice with sepsis, improved the survival rate, reduced the degree of organ damage, and reduced the infiltration of immune cells in the lung tissues. The protective effect is comparable to that of XBJ. MDP and TR inhibited the levels of inflammatory factors and coagulation activation in septic mice. Paeonol and paeoniflorin in MDP showed significant protective effects on septic mice, and inhibited inflammatory cytokines level and coagulation activation.

CONCLUSION

These results confirm that DMD and its disassembled prescriptions have good therapeutic effect on septic mice, and the mechanism may be related to inhibition of the inflammatory response and coagulation activation.

Antibiotic resistant bacteria survive treatment by doubling while shrinking

Many antibiotics that are used in healthcare, farming, and aquaculture end up in environments with different spatial structures that might promote heterogeneity in the emergence of antibiotic resistance. However, the experimental evolution of microbes at sub-inhibitory concentrations of antibiotics has been mainly carried out at the population level which does not allow capturing single-cell responses to antibiotics. Here, we investigate and compare the emergence of resistance to ciprofloxacin in Escherichia coli in well-mixed and structured environments using experimental evolution, genomics, and microfluidics-based time-lapse microscopy. We discover that resistance to ciprofloxacin and cross-resistance to other antibiotics is stronger in the well-mixed environment due to the emergence of target mutations, whereas efflux regulator mutations emerge in the structured environment. The latter mutants also harbor sub-populations of persisters that survive high concentrations of ciprofloxacin that inhibit bacterial growth at the population level. In contrast, genetically resistant bacteria that display target mutations also survive high concentrations of ciprofloxacin that inhibit their growth via population-level antibiotic tolerance. These resistant and tolerant bacteria keep doubling while shrinking in size in the presence of ciprofloxacin and regain their original size after antibiotic removal, which constitutes a newly discovered phenotypic response. This new knowledge sheds light on the diversity of strategies employed by bacteria to survive antibiotics and poses a stepping stone for understanding the link between mutations at the population level and phenotypic single-cell responses.

IMPORTANCE

The evolution of antimicrobial resistance poses a pressing challenge to global health with an estimated 5 million deaths associated with antimicrobial resistance every year globally. Here, we investigate the diversity of strategies employed by bacteria to survive antibiotics. We discovered that bacteria evolve genetic resistance to antibiotics while simultaneously displaying tolerance to very high doses of antibiotics by doubling while shrinking in size.

IRGM Deficiency Exacerbates Sepsis-Induced Acute Lung Injury by Inhibiting Autophagy Through the AKT/mTOR Signaling Pathway

Background

Sepsis is a life-threatening condition characterized by organ dysfunction due to an impaired immune response to infection. The lungs are highly susceptible to infection, often resulting in acute lung injury (ALI). The immune-related GTPase M (IRGM) and its murine homolog Irgm1 mediate autophagy and are implicated in inflammatory diseases, yet their roles in sepsis-induced ALI remain unclear.

Methods

We used RNA sequencing and bioinformatics to explore IRGM regulation. Sepsis-induced ALI was modeled in mice using cecal ligation and puncture (CLP). An in vitro model was created by stimulating A549 cells with lipopolysaccharide (LPS).

Results

In A549 cells, LPS treatment induced upregulation of IRGM expression and enhanced autophagy levels. IRGM knockdown exacerbated LPS-induced ALI, characterized by suppressed autophagy and increased apoptosis, along with significantly elevated levels of p-AKT and p-mTOR. Further investigation revealed that treatment with the AKT inhibitor MK2206 effectively reversed the autophagy inhibition caused by IRGM knockdown and reduced apoptosis. These findings suggest that the AKT/mTOR signaling pathway plays a crucial role in IRGM-mediated protection against sepsis-related ALI.

Conclusion

This study identifies the protective role of IRGM in sepsis-induced ALI and reveals that IRGM mitigates ALI by promoting autophagy through inhibition of the AKT/mTOR pathway. These findings provide insights into the pathogenesis of sepsis-related ALI and highlight IRGM as a potential therapeutic target.

Investigating the efficacy of dapsone in treating sepsis induced by cecal ligation and puncture surgery in male mice

Sepsis is a life-threatening condition caused by the body's response to an infection. Dapsone is a sulfone with antibiotic properties, and experimental evidence suggests it has significant anti-inflammatory and anti-oxidative stress effects. The objective of this study was to investigate the efficacy of dapsone in mice after CLP (cecal ligation and puncture) surgery, which is a model for inducing sepsis. The study divided animals into five groups: CLP, sham, and three groups receiving different doses of dapsone (0.5, 1, 2 mg/kg). Sepsis was induced through CLP surgery, followed by dapsone administration. In each group, half of the mice were used to evaluate levels of various markers and pathological changes at 24 h post-CLP, while the other half was used to record the mortality rates within 96 h. The results showed that single-dose administration of dapsone at (0.5, 1, 2 mg/kg) after CLP surgery improved survival compared to the CLP group. Dapsone was also associated with a significant reduction in pro-inflammatory cytokines TNF-α, IL-1β, IL-6, NO, and MPO, as well as lactate and creatinine serum levels. However, dapsone did not have a significant effect on urea serum levels. In conclusion, the data suggest that dapsone treatment leads to increased survival in septic mice after CLP, and due to its ability to reduce TNF-α, IL-1β, IL-6, MPO, and lactate levels, it has anti-inflammatory effects in sepsis. The sepsis treatment with dapsone in mice protects against inflammation and oxidative stress.

Prediction of Prognosis in Patients with Sepsis Based on Platelet-Related Genes

The study aimed to develop a risk prognostic model using platelet-related genes (PRGs) to predict sepsis patient outcomes. Sepsis patient data from the Gene Expression Omnibus (GEO) database and PRGs from the Molecular Signatures Database (MSigDB) were analyzed. Differential analysis identified 1139 differentially expressed genes (DEGs) between sepsis and control groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed enrichment in functions related to immune cell regulation and pathways associated with immune response and infectious diseases. A risk prognostic model was established using LASSO and Cox regression analyses, incorporating 10 PRGs selected based on their association with sepsis prognosis. The model demonstrated good stratification and prognostic effects, confirmed by survival and receiver operating characteristic (ROC) curve analyses. It served as an independent prognostic factor in sepsis patients. Further analysis using the CIBERSORT algorithm showed higher infiltration of activated natural killer (NK) cells and lower infiltration of CD8 T cells and CD4 T cells naïve in the high-risk group compared to the low-risk group. Additionally, expression levels of human leukocyte antigen (HLA) genes were significantly lower in the high-risk group. In conclusion, the 10-gene risk model based on PRGs accurately predicted sepsis patient prognosis and immune infiltration levels. This study provides valuable insights into the role of platelets in sepsis prognosis and diagnosis, offering potential implications for personalized treatment strategies.

Molecular patterns of microbial and metabolic interactions in septic patients with persistent lymphopenia

BACKGROUND

Persistent lymphopenia can be regarded as an important index of acquired immune dysfunction in sepsis. Whether the specific immune factor changes in septic patients with lymphopenia and the correlation to gut microbiota and metabolites remain unclear.

METHODS

This single-center prospective observation conducted lymphocyte subgroup analysis of blood samples and 16S rRNA gene amplicons sequencing and untargeted metabolomics analysis of fecal samples from 36 subjects with the persistent (≥3d) (n = 21) and non-persistent lymphopenia (<3d) (n = 15).

RESULTS

The persistent lymphopenia showed higher the 28d mortality and 90d mortality, while significantly lower CD3+T/LY, CD3+T cells, CD3+CD4+T cells, CD3+CD8+T cells, Th1 cells, Th2 cells, CD45RA + Treg cells. The 16S rRNA results showed that Staphylococcus, Peptostreptococcus, Bulleidia, Leuconostoc were significant enriched in the persistent lymphopenia. The metabolomics analysis showed that α-Ketoisovaleric acid was increased and 7-DHCA, α-MCA, β-MCA, HCA, LCA-3S, CA, UCA and Citramalic acid were decreased in the persistent lymphopenia.

CONCLUSION

In the process of interaction between host receptors and gut microbiota in patients with persistent lymphopenia sepsis, with a significant reduction in gut microbiota diversity and bile acid metabolites. That can affect various inflammatory pathways of gut immune cells, causing immune dysfunction in the body, which may be one of the main causes of death.

Extracellular NCOA4 is a mediator of septic death by activating the AGER-NFKB pathway

Sepsis, a life-threatening condition resulting from a dysregulated response to pathogen infection, poses a significant challenge in clinical management. Here, we report a novel role for the autophagy receptor NCOA4 in the pathogenesis of sepsis. Activated macrophages and monocytes secrete NCOA4, which acts as a mediator of septic death in mice. Mechanistically, lipopolysaccharide, a major component of the outer membrane of Gram-negative bacteria, induces NCOA4 secretion through autophagy-dependent lysosomal exocytosis mediated by ATG5 and MCOLN1. Moreover, bacterial infection with E. coli or S. enterica leads to passive release of NCOA4 during GSDMD-mediated pyroptosis. Upon release, extracellular NCOA4 triggers the activation of the proinflammatory transcription factor NFKB/NF-κB by promoting the degradation of NFKBIA/IκB molecules. This process is dependent on the pattern recognition receptor AGER, rather than TLR4. In vivo studies employing endotoxemia and polymicrobial sepsis mouse models reveal that a monoclonal neutralizing antibody targeting NCOA4 or AGER delays animal death, protects against organ damage, and attenuates systemic inflammation. Furthermore, elevated plasma NCOA4 levels in septic patients, particularly in non-survivors, correlate positively with the sequential organ failure assessment score and concentrations of lactate and proinflammatory mediators, such as TNF, IL1B, IL6, and HMGB1. These findings demonstrate a previously unrecognized role of extracellular NCOA4 in inflammation, suggesting it as a potential therapeutic target for severe infectious diseases. Abbreviation: BMDMs: bone marrow-derived macrophages; BUN: blood urea nitrogen; CLP: cecal ligation and puncture; ELISA: enzyme-linked immunosorbent assay; LPS: lipopolysaccharide; NO: nitric oxide; SOFA: sequential organ failure assessment.

Clostridium butyricum attenuates LPS-induced myocardial injury in septic mice by modulating CD4 + CD25 + FOXP3 + Treg

Sepsis-induced myocardial injury has become a major threat to patient health and safety. Intestinal microbiota imbalance plays a crucial role in sepsis regulation. Using 16srRNA technology, we explored how intestinal colonization of Clostridium butyricum over 28 days impacted mice with LPS-induced sepsis. Significant changes were noted in the gut microbiota of the mice, highlighting that C. butyricum can positively influence the immune state in septic myocardial injury models. The bacterium's ability to prevent intestinal mucosal damage and alleviate the immunosuppressive state during the later stages of sepsis by regulating CD4 + CD25 + FOXP3 + Treg cells is particularly noteworthy. This suggests a therapeutic role for C. butyricum in sepsis management by protecting against myocardial injury and improving immune regulation.

In response to bacteria, neutrophils release extracellular vesicles capable of initiating thrombin generation through DNA-dependent and independent pathways

Neutrophils release extracellular vesicles, and some subsets of neutrophil-derived extracellular vesicles are procoagulant. In response to Staphylococcus aureus, neutrophils produce extracellular vesicles that associate electrostatically with neutrophil extracellular traps. DNA in neutrophil extracellular traps is procoagulant, but whether neutrophil extracellular vesicles produced during bacterial challenge have similar activity is unknown. Given that extracellular vesicle activity is agonist and cell-type dependent and coagulation contributes to sepsis, we hypothesized that sepsis-causing bacteria increase production of neutrophil-derived extracellular vesicles, as well as extracellular vesicle-associated DNA, and intact extracellular vesicles and DNA cause coagulation. We recovered extracellular vesicles from neutrophils challenged with S. aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa and measured associated DNA and procoagulant activity. Extracellular vesicles from S. aureus-challenged neutrophils, which were previously characterized, displayed dose-dependent procoagulant activity as measured by thrombin generation in platelet-poor plasma. Extracellular vesicle lysis and DNase treatment reduced thrombin generation by 90% and 37%, respectively. S. epidermidis, E. coli, and P. aeruginosa also increased extracellular vesicle production and extracellular vesicle-associated extracellular DNA, and these extracellular vesicles were also procoagulant. Compared to spontaneously released extracellular vesicles, which demonstrated some ability to amplify factor XII-dependent coagulation in the presence of an activator, only extracellular vesicles produced in response to bacteria could initiate the pathway. S. aureus and S. epidermidis extracellular vesicles had more surface-associated DNA than E. coli and P. aeruginosa extracellular vesicles, and S. aureus and S. epidermidis extracellular vesicles contributed to initiation and amplification of thrombin generation in a DNA-dependent manner. However, DNA on E. coli or P. aeruginosa extracellular vesicles played no role, suggesting that neutrophils release procoagulant extracellular vesicles, which can activate the coagulation cascade through both DNA-dependent and independent mechanisms.

Screening of prognostic core genes based on cell-cell interaction in the peripheral blood of patients with sepsis

Peripheral blood samples from 15 septic patients admitted within 24 h and 8 healthy volunteers were used to conduct RNA-seq. Quantitative PCR of THP1 cells was performed to investigate the expression levels of the selected key genes. A total of 1,128 differential genes were identified, 721 of which were upregulated and 407 were downregulated. These genes are mainly involved in neutrophil activation, T cell regulation, immune effector process regulation, cytokine receptor activity, and cytokine binding. The six target genes were ELANE, IL1R2, RAB13, RNASE3, FCGR1A, and TLR5. In the sepsis group, FCGR1A and TLR5 were positively associated with survival compared to ELANE, IL1R2, RAB13, and RNASE3, which were adversely associated with survival. Furthermore, a meta-analysis based on public databases revealed an increased expression of these six target genes in the peripheral blood of patients with sepsis. In addition, we discovered that monocytes primarily express these genes. Using qPCR, we confirmed that these six important genes were highly expressed in lipopolysaccharide-treated THP1 cells. In summary, these findings suggest that ELANE, IL1R2, RAB13, RNASE3, FCGR1A, and TLR5 may influence the prognosis of patients with sepsis and provide novel insights and potential avenues for the treatment of sepsis.

Utilizing integrated bioinformatics and machine learning approaches to elucidate biomarkers linking sepsis to fatty acid metabolism-associated genes

Sepsis, characterized as a systemic inflammatory response triggered by the invasion of pathogens, represents a continuum that may escalate from mild systemic infection to severe sepsis, potentially resulting in septic shock and multiple organ dysfunction syndrome. Advancements in lipidomics and metabolomics have unveiled the complex role of fatty acid metabolism (FAM) in both healthy and pathological states. Leveraging bioinformatics, this investigation aimed to identify and substantiate potential FAM-related genes (FAMGs) implicated in sepsis. The approach encompassed a differential expression analysis across a pool of 36 candidate FAMGs. GSEA and GSVA were employed to assess the biological significance and pathways associated with these genes. Furthermore, Lasso regression and SVM-RFE methodologies were implemented to determine key hub genes and assess the diagnostic prowess of nine selected FAMGs in sepsis identification. The study also investigated the correlation between these hub FAMGs. Validation was conducted through expression-level analysis using the GSE13904 and GSE65682 datasets. The study identified 13 sepsis-associated FAMGs, including ABCD2, ACSL3, ACSM1, ACSS1, ACSS2, ACOX1, ALDH9A1, ACACA, ACACB, FASN, OLAH, PPT1, and ELOVL4. As demonstrated by functional enrichment analysis results, these genes played key roles in several critical biological pathways, such as the Peroxisome, PPAR signaling pathway, and Insulin signaling pathway, all of which are intricately linked to metabolic regulation and inflammatory responses. The diagnostic potential of these FAMGs was further highlighted. In short, the expression patterns of these FAMGs c effectively distinguished sepsis cases from non-septic controls, which suggested that they may be promising biomarkers for early sepsis detection. This discovery not only enhanced our understanding of the molecular mechanisms underpinning sepsis but also paved the way for developing novel diagnostic tools and therapeutic strategies targeting metabolic dysregulation in septic patients. This research sheds light on 13 FAMGs associated with sepsis, providing valuable insights into novel biomarkers for this condition and facilitating the monitoring of its progression. These findings underscore the significance of purine metabolism in sepsis pathogenesis and open avenues for further investigation into therapeutic targets.

Exploiting the Zebrafish Model for Sepsis Research: Insights into Pathophysiology and Therapeutic Potentials

Sepsis, a severe condition instigated by infections, continues to be a primary global cause of death, typified by systemic inflammation and advancing immune dysfunction. Comprehending the complex pathological processes that underlie sepsis is integral to the creation of efficacious treatments. Despite the inability of animal models to entirely reproduce the clinical intricacies related to sepsis, they are invaluable instruments for the exploration and development of therapeutic approaches. Within this context, the zebrafish model is particularly noteworthy due to its genetic tractability, transparency, and appropriateness for high-throughput screening of genetic mutants and therapeutic compounds. This scholarly review emphasizes the crucial role that the zebrafish disease model plays in enhancing our comprehension of sepsis, by exploring its applications in deciphering immune and inflammatory responses, evaluating the consequences of genetic alterations, and examining novel therapeutic agents. The Insights derived from zebrafish research not only augment our understanding of the underlying mechanisms of sepsis, but also possess considerable potential for the transference of these discoveries into clinical therapies, thus potentially transforming the approach to sepsis management. The objective of this scholarly article is to underscore the importance of zebrafish in the realm of biomedical research pertaining to sepsis, and to delineate forthcoming opportunities for utilizing this model in clinical applications.

Crossing Age Boundaries: The Unifying Potential of Presepsin in Sepsis Diagnosis Across Diverse Age Groups

Sepsis is a pervasive condition that affects individuals of all ages, with significant social and economic consequences. The early diagnosis of sepsis is fundamental for establishing appropriate treatment and is based on warning scores and clinical characteristics, with positive microbiological cultures being the gold standard. Research has yet to identify a single biomarker to meet this diagnostic demand. Presepsin is a molecule that has the potential as a biomarker for diagnosing sepsis. In this paper, we present a narrative review of the diagnostic and prognostic performance of presepsin in different age groups. Given its particularities, it is identified that presepsin is a potential biomarker for sepsis at all stages of life.

The impact of ulinastatin on lymphocyte apoptosis and autophagy in sepsis patients

This study aimed to assess the influence of ulinastatin (UTI) on lymphocyte apoptosis and autophagy in sepsis patients, as well as its effect on inflammatory factors and vital organ function, with the goal of providing insights for improved clinical management of sepsis. A total of 40 sepsis patients were randomly assigned to the UTI group or the control group. The UTI group received standard treatment plus intravenous UTI, while the control group received standard treatment alone. Peripheral blood samples were collected at multiple time points for analysis of lymphocyte apoptosis, autophagy, inflammatory markers, and organ function. Various experimental techniques including Hoechst staining, transmission electron microscopy, and Western blot analysis were utilized to assess lymphocyte apoptosis, autophagy, and related protein expression levels. The study revealed that UTI treatment significantly inhibited lymphocyte apoptosis and promoted autophagy in sepsis patients. The levels of autophagy-related proteins LC3-II and Beclin-1 were substantially elevated, while the ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax was increased following UTI treatment. Furthermore, the levels of inflammatory markers IL-6, procalcitonin, and C-reactive protein were markedly reduced in the UTI group compared to the control group. Additionally, UTI treatment led to improved liver, kidney and cardiac function as evidenced by reduced levels of liver enzymes and creatinine, and cardiac enzymes. The findings of this study demonstrate that UTI exerts a protective effect on septic patients by inhibiting lymphocyte apoptosis, promoting autophagy, and attenuating systemic inflammation. Moreover, UTI treatment was associated with improved liver, kidney, and cardiac function in septic patients. These results contribute to a better understanding of the clinical management of sepsis and underscore the potential of UTI as a therapeutic intervention in septic patients.

Single-cell RNA sequencing and immune repertoire analysis revealed dynamic immune characteristics associated with peripheral blood during sepsis

Sepsis is a potentially fatal condition arising from an abnormal immune response to an infection, which can result in organ failure and even death. To explore the mechanism underlying the dysregulated immune response during sepsis and identify potential therapeutic targets, single-cell RNA sequencing (scRNA-seq) and immune repertoire analysis were conducted to depict the cellular landscape of peripheral blood cells in septic mice. We observed significant alterations in the number and proportion of peripheral blood cell populations driven by sepsis. By combining single-cell gene expression profiles and B cell receptor (BCR) repertoire analysis, we discerned that infection inflicted serious damage on the antigen presentation ability of B cells and the diversity of BCR in a short time. In addition, we found that the cecal ligation and puncture procedure in mice inhibited the communication signals of CD4+ and CD8+ T cells and decreased the interactions between B cells and other cells. Our study provides detailed insights into the dynamic changes in the biological characteristics of peripheral blood cells driven by sepsis and provides important advances in our understanding of immune disorders during sepsis.

Combining ulinastatin with TIENAM improves the outcome of sepsis induced by cecal ligation and puncture in mice by reducing inflammation and regulating immune responses

Despite the high mortality associated with sepsis, effective and targeted treatments remain scarce. The use of conventional antibiotics such as TIENAM (imipenem and cilastatin sodium for injection, TIE) is challenging because of the increasing bacterial resistance, which diminishes their efficacy and leads to adverse effects. Our previous studies demonstrated that ulinastatin (UTI) exerts a therapeutic impact on sepsis by reducing systemic inflammation and modulating immune responses. In this study, we examined the possibility of administering UTI and TIE after inducing sepsis in a mouse model using cecal ligation and puncture (CLP). We assessed the rates of survival, levels of inflammatory cytokines, the extent of tissue damage, populations of immune cells, microbiota in ascites, and important signaling pathways. The combination of UTI and TIE significantly improved survival rates and reduced inflammation and bacterial load in septic mice, indicating potent antimicrobial properties. Notably, the survival rates of UTI+TIE-treated mice increased from 10 % to 75 % within 168 h compared to those of mice that were subjected to CLP. The dual treatment successfully regulated the levels of inflammatory indicators (interleukin [IL]-6, IL-1β, and tumor necrosis factor [TNF]-α) and immune cell numbers by reducing B cells, natural killer cells, and TNFR2+ Treg cells and increasing CD8+ T cells. Additionally, the combination of UTI and TIE alleviated tissue damage, reduced bacterial load in the peritoneal cavity, and suppressed the NF-κB signaling pathway. Our findings indicate that UTI and TIE combination therapy can significantly enhance sepsis outcomes by reducing inflammation and boosting the immune system. The results offer a promising therapeutic approach for future sepsis treatment.

Huperzine a ameliorates sepsis-induced acute lung injury by suppressing inflammation and oxidative stress via α7 nicotinic acetylcholine receptor

Sepsis, characterized by high mortality rates, causes over 50 % of acute lung injury (ALI) cases, primarily due to the heightened susceptibility of the lungs during this condition. Suppression of the excessive inflammatory response is critical for improving the survival of patients with sepsis; nevertheless, no specific anti-sepsis drugs exist. Huperzine A (HupA) exhibits neuroprotective and anti-inflammatory properties; however, its underlying mechanisms and effects on sepsis-induced ALI have yet to be elucidated. In this study, we demonstrated the potential of HupA for treating sepsis and explored its mechanism of action. To investigate the in vivo impacts of HupA, a murine model of sepsis was induced through cecal ligation and puncture (CLP) in both wild-type (WT) and α7 nicotinic acetylcholine receptor (α7nAChR) knockout mice. Our results showed that HupA ameliorates sepsis-induced acute lung injury by activating the α7nAChR. We used the CLP sepsis model in wild-type and α7nAChR -/- mice and found that HupA significantly increased the survival rate through α7nAChR, reduced the pro-inflammatory cytokine levels and oxidative stress, ameliorated histopathological lung injury, altered the circulating immune cell composition, regulated gut microbiota, and promoted short-chain fatty acid production through α7nAChR in vivo. Additionally, HupA inhibited Toll-like receptor NF-κB signaling by upregulating the α7nAChR/protein kinase B/glycogen synthase kinase-3 pathways. Our data elucidate HupA's mechanism of action and support a "new use for an old drug" in treating sepsis. Our findings serve as a basis for further in vivo studies of this drug, followed by application to humans. Therefore, the findings have the potential to benefit patients with sepsis.

Sepsis-associated liver injury: Mechanisms and potential therapeutic targets

In this editorial, we examined a recent article in the World Journal of Gastroenterology that focused on sepsis-associated liver injury (SLI) and its treatment. SLI is a serious complication of sepsis, primarily caused by microcirculatory disturbances, the gut-liver axis, and inflammatory responses. Specific treatment recommendations for SLI are lacking. The gut-liver axis represents a potential therapeutic target, with metformin showing promise in modulating the gut microbiome and enhancing intestinal barrier function. Although immunomodulatory therapies are being explored, anti-tumor necrosis factor agents and interleukin-1 receptor antagonists have not demonstrated significant clinical benefits. Statins may reduce liver inflammation and prevent injury in sepsis, but their clinical application is limited. Reduced D-related human leucocyte antigen expression on monocytes and lymphocytes suggests immune suppression in patients, indicating that corticosteroids could reverse clinical deterioration in severe infections and address adrenal cortical insufficiency. Current large-scale studies on glucocorticoid therapy for sepsis have yielded mixed results, likely due to inadequate assessment of the immune status of the host. Future research should prioritize the development of personalized immunotherapy tailored to patients' immune profiles, focusing on identifying novel indicators of immune status and advancing immunomodulatory targets and therapeutics for septic patients.

Brain imaging and machine learning reveal uncoupled functional network for contextual threat memory in long sepsis

Positron emission tomography (PET) utilizes radiotracers like [18F]fluorodeoxyglucose (FDG) to measure brain activity in health and disease. Performing behavioral tasks between the FDG injection and the PET scan allows the FDG signal to reflect task-related brain networks. Building on this principle, we introduce an approach called behavioral task-associated PET (beta-PET) consisting of two scans: the first after a mouse is familiarized with a conditioning chamber, and the second upon recall of contextual threat. Associative threat conditioning occurs between scans. Beta-PET focuses on brain regions encoding threat memory (e.g., amygdala, prefrontal cortex) and contextual aspects (e.g., hippocampus, subiculum, entorhinal cortex). Our results show that beta-PET identifies a biologically defined network encoding contextual threat memory and its uncoupling in a mouse model of long sepsis. Moreover, machine learning algorithms (linear logistic regression) and ordinal trends analysis demonstrate that beta-PET robustly predicts the behavioral defense response and its breakdown during long sepsis.

Oceanic Breakthroughs: Marine-Derived Innovations in Vaccination, Therapy, and Immune Health

The vast, untapped potential of the world's oceans is revealing groundbreaking advancements in human health and vaccination. Microalgae such as Nannochloropsis spp. and Dunaliella salina are emerging as resources for recombinant vaccine development with specific and heterologous genetic tools used to boost production of functional recombinant antigens in Dunaliella salina and Nannochloropsis spp. to induce immunoprotection. In humans, several antigens produced in microalgae have shown potential in combating diseases caused by the human papillomavirus, human immunodeficiency virus, hepatitis B virus, influenza virus, Zika virus, Zaire Ebola virus, Plasmodium falciparum, and Staphylococcus aureus. For animals, microalgae-derived vaccine prototypes have been developed to fight against the foot-and-mouth disease virus, classical swine fever virus, vibriosis, white spot syndrome virus, and Histophilus somni. Marine organisms offer unique advantages, including the ability to express complex antigens and sustainable production. Additionally, the oceans provide an array of bioactive compounds that serve as therapeutics, potent adjuvants, delivery systems, and immunomodulatory agents. These innovations from the sea not only enhance vaccine efficacy but also contribute to broader immunological and general health. This review explores the transformative role of marine-derived substances in modern medicine, emphasizing their importance in the ongoing battle against infectious diseases.

Single-cell RNA sequencing and transcriptomic analysis reveal key genes and regulatory mechanisms in sepsis

The pathogenesis of sepsis, with a high mortality rate and often poor prognosis, has not been fully elucidated. Therefore, an in-depth study on the pathogenesis of sepsis at the molecular level is essential to identify key sepsis-related genes. The aim of this study was to explore the key genes and potential molecular mechanisms of sepsis using a bioinformatics approach. In addition, key genes with miRNA network correlation analysis and immune infiltration correlation analysis were investigated. The scRNA dataset (GSE167363) and RNA-seq dataset (GSE65682, GSE134347) from GEO database were used for screening out differentially expressed genes using single-cell sequencing and transcriptome sequencing. The analysis of immune infiltration was evaluated by the CIBERSORT method. Key genes and possible mechanisms were identified by WGCNA analysis, GSVA analysis, GSEA enrichment analysis and regulatory network analysis, and miRNA networks associated with key genes were constructed. Nine key genes associated with the development of sepsis, namely IL7R, CD3D, IL32, GPR183, HLA-DPB1, CD81, PEBP1, NCL, and ETS1 were screened, and the specific signaling mechanisms associated with the key genes causing sepsis were predicted. Immune profiling showed immune heterogeneity between control and sepsis samples. A regulatory network of 82 miRNAs, 266 pairs of mRNA-miRNA relationship pairs was also constructed. These nine key genes have the potential to become biomarkers for the diagnosis of sepsis and provide new targets and research directions for the treatment of sepsis.

Exosomal Drug Delivery Systems: A Novel Therapy Targeting PD-1 in Septic-ALI

BACKGROUND

The cytokine storm triggered by sepsis can lead to the development of acute lung injury (ALI). Human umbilical cord Mesenchymal stem cells derived exosomes (HucMSCs-EXOs) have been demonstrated to possess immunosuppressive and anti-inflammatory properties. Programmed cell death receptor 1 (PD-1) plays a crucial role in maintaining the inflammatory immune homeostasis. The aim of this study is to investigate the synergistic therapeutic effect of EXOs loaded with anti-PD-1 peptide on septic-ALI.

METHODS

This study prepares a novel EXOs-based drug, named MEP, by engineering modification of HucMSCs-EXOs, which are non-immunogenic extracellular vesicles, loaded with anti-PD-1 peptide. The therapeutic effect and potential mechanism of MEP on septic-ALI are elucidated through in vivo and in vitro experiments, providing experimental evidence for the treatment of septic acute lung injury with MEP.

RESULTS

We found that, compared to individual components (anti-PD-1 peptide or EXOs), MEP treatment can more effectively improve the lung injury index of septic-ALI mice, significantly reduce the expression levels of inflammatory markers CRP and PCT, as well as pro-inflammatory cytokines TNF-α and IL-1β in serum, decrease lung cell apoptosis, and significantly increase the expression of anti-inflammatory cytokine IL-10 and CD68+ macrophages. In vitro, MEP co-culture promotes the proliferation of CD206+ macrophages, increases the M2/M1 macrophage ratio, and attenuates the inflammatory response. GEO data analysis and qRT-PCR validation show that MEP reduces the expression of inflammasome-related genes and M1 macrophage marker iNOS.

CONCLUSION

In both in vitro and in vivo settings, MEP demonstrates superior therapeutic efficacy compared to individual components in the context of septic-ALI.

Potential mechanism of CARD16 protein action and susceptibility to sepsis in the elderly infected population: Through transcriptome analysis of blood

As global aging accelerates, the super-elderly population is at higher risk of infectious diseases, especially sepsis, a condition that may be associated with declining immune system function and abnormal inflammatory responses. The aim of this study was to investigate the role of CARD16 protein in sepsis susceptibility in the elderly population and its potential mechanism, and to reveal the expression characteristics of CARD16-related genes through blood transcriptomic analysis. Transcriptome sequencing was conducted on peripheral blood samples obtained from patients suffering from senile sepsis, along with samples from a healthy elderly control group. To examine the differences in gene expression, bioinformatics techniques were employed to compare the expression levels of CARD16-related genes between the two groups. Additionally, a comprehensive analysis was performed on the downstream inflammatory pathways and cytokines that are regulated by CARD16.The findings from the transcriptome analysis indicated that the expression of CARD16 was markedly upregulated in the cohort of patients experiencing hypersenile sepsis. This upregulation was associated with an increase in a variety of pro-inflammatory factors. Further network analysis suggested that CARD16 may potentiate the inflammatory response by modulating the NF-κB signaling pathway, which could consequently heighten the patients' vulnerability to sepsis.In comparison to the healthy elderly control group, the levels of anti-inflammatory genes in the super-elderly cohort were found to be significantly diminished. This observation points to a notable imbalance in immune regulation, further emphasizing the altered immune response in individuals with senile sepsis.

MLKL-mediated endothelial necroptosis drives vascular damage and mortality in systemic inflammatory response syndrome

The hypersecretion of cytokines triggers life-threatening systemic inflammatory response syndrome (SIRS), leading to multiple organ dysfunction syndrome (MODS) and mortality. Although both coagulopathy and necroptosis have been identified as important factors in the pathogenesis of SIRS, the specific cell types that undergo necroptosis and the interrelationships between coagulopathy and necroptosis remain unclear. In this study, we utilized visualization analysis via intravital microscopy to demonstrate that both anticoagulant heparin and nonanticoagulant heparin (NAH) pretreatment protect mice against TNF-α-induced mortality in SIRS. Moreover, the deletion of Mlkl or Ripk3 resulted in decreased coagulation and reduced mortality in TNF-α-induced SIRS. These findings suggest that necroptosis plays a key role upstream of coagulation in SIRS-related mortality. Furthermore, using a genetic lineage tracing mouse model (Tie2-Cre;Rosa26-tdT), we tracked endothelial cells (ECs) and verified that EC necroptosis is responsible for the vascular damage observed in TNF-α-treated mice. Importantly, Mlkl deletion in vascular ECs in mice had a similar protective effect against lethal SIRS by blocking EC necroptosis to protect the integrity of the endothelium. Collectively, our findings demonstrated that RIPK3-MLKL-dependent necroptosis disrupted vascular integrity, resulting in coagulopathy and multiorgan failure, eventually leading to mortality in SIRS patients. These results highlight the importance of targeting vascular EC necroptosis for the development of effective treatments for SIRS patients.

The role of inflammatory response and metabolic reprogramming in sepsis-associated acute kidney injury: mechanistic insights and therapeutic potential

Sepsis represents a severe condition characterized by organ dysfunction resulting from a dysregulated host response to infection. Among the organs affected, the kidneys are particularly vulnerable, with significant functional impairment that markedly elevates mortality rates. Previous researches have highlighted that both inflammatory response dysregulation and metabolic reprogramming are crucial in the onset and progression of sepsis associated acute kidney injury (SA-AKI), making these processes potential targets for innovative therapies. This study aims to elucidate the pathophysiological mechanisms of renal injury in sepsis by perspective of inflammatory response dysregulation, with particular emphasis on pyroptosis, necroptosis, autophagy, and ferroptosis. Furthermore, it will incorporate insights into metabolic reprogramming to provide a detailed analysis of the mechanisms driving SA-AKI and explore potential targeted therapeutic strategies, providing solid theoretical framework for the development of targeted therapies for SA-AKI.

Group 2 innate lymphocytes protect the balance between autophagy and apoptosis in cardiomyocytes during sepsis-induced cardiac injury

Group 2 innate lymphocytes (ILC2) have an important role in orchestrating sepsis-induced immune response. However, the impact of LC2 on sepsis-induced cardiac injury is still not fully understood. This study investigated the mechanisms governing ILC2 activation within the cardiac tissue after sepsis. In vivo experiments using wild-type and IL-33 deficient mice indicated that the presence of interleukin (IL)-33, which participates in expanding and activating ILC2 cells, was correlated with higher ILC2 levels (246 ± 34 vs. 66 ± 18, p < 0.01), reduced cardiac dysfunction, and lower markers of cardiac injury. Conversely, IL-33 deficiency led to exacerbated cardiac damage. Additionally, heart ILC2 significantly increased the expression and secretion of IL-5 (2.18 ± 0.34 ng/ml vs. 1.18 ± 0.24 ng/ml, p < 0.05) and IL-13 (10.55 ± 1.13 ng/ml vs. 7.59 ± 1.13 ng/ml, p < 0.05) following sepsis, with this response being mediated by IL-33. Moreover, IL-5 deficient mice exhibited increased cardiac dysfunction and myocardial apoptosis post-sepsis (20.7 ± 4.28% vs. 29.61 ± 4.28%, p < 0.05). Furthermore, in vitro experiments involving co-cultures of ILC2 with mice cardiomyocytes after lipopolysaccharide (LPS) administration suggested that IL-5 derived from ILC2 protects cardiomyocytes from autophagy and apoptosis. These findings imply that IL-33, released in response to sepsis, induces ILC2 activation and IL-5 secretion, orchestrating the equilibrium between autophagy and apoptosis in cardiomyocytes and offering potential therapeutic avenues for mitigating sepsis-induced cardiac injury.

Immunological sub-phenotypes and response to convalescent plasma in COVID-19 induced ARDS: a secondary analysis of the CONFIDENT trial

BACKGROUND

Convalescent plasma (CP) reduced the mortality in COVID-19 induced ARDS (C-ARDS) patients treated in the CONFIDENT trial. As patients are immunologically heterogeneous, we hypothesized that clusters may differ in their treatment responses to CP.

METHODS

We measured 20 cytokines, chemokines and cell adhesion markers using a multiplex technique at the time of inclusion in the CONFIDENT trial in patients of centers having accepted to participate in this secondary study. We performed descriptive statistics, unsupervised hierarchical cluster analysis, and examined the association between the clusters and CP effect on day-28 mortality.

RESULTS

Of the 475 patients included in CONFIDENT, 391 (82%) were sampled, and 196/391 (50.1%) had been assigned to CP. We identified four sub-phenotypes representing 89 (22.8%), 178 (45.5%), 38 (9.7%), and 86 (22.0%) patients. The most contributing biomarkers in the principal component analysis were IL-1β, IL-12p70, IL-6, IFN-α, IL-17A, IFN-γ, IL-13, TFN-α, total IgG, and CXCL10. Sub-phenotype-1 displayed a lower immune response, sub-phenotype-2 a higher adaptive response, sub-phenotype-3 the highest innate antiviral, pro and anti-inflammatory response, and adhesion molecule activation, and sub-phenotype-4 a higher pro and anti-inflammatory response, migration protein and adhesion molecule activation. Sub-phenotype-2 and sub-phenotype-4 had higher severity at the time of inclusion. The effect of CP treatment on mortality appeared higher than standard care in each sub-phenotype, without heterogeneity between sub-phenotypes (p = 0.97).

CONCLUSION

In patients with C-ARDS, we identified 4 sub-phenotypes based on their immune response. These sub-phenotypes were associated with different clinical profiles. The response to CP was similar across the 4 sub-phenotypes.

TRIAL REGISTRATION

Ethics Committee of the University Hospital of Liège CE 2020/239.

CLINICALTRIALS

gov NCT04558476. Registered 2020-09-11, https://www.

CLINICALTRIALS

gov/study/NCT04558476 .

The roles of arginases and arginine in immunity

Arginase activity and arginine metabolism in immune cells have important consequences for health and disease. Their dysregulation is commonly observed in cancer, autoimmune disorders and infectious diseases. Following the initial description of a role for arginase in the dysfunction of T cells mounting an antitumour response, numerous studies have broadened our understanding of the regulation and expression of arginases and their integration with other metabolic pathways. Here, we highlight the differences in arginase compartmentalization and storage between humans and rodents that should be taken into consideration when assessing the effects of arginase activity. We detail the roles of arginases, arginine and its metabolites in immune cells and their effects in the context of cancer, autoimmunity and infectious disease. Finally, we explore potential therapeutic strategies targeting arginases and arginine.

Bronchoscopic Diagnosis of Severe Respiratory Infections

The diagnosis of severe respiratory infections in intensive care remains an area of uncertainty and involves a complex balancing of risks and benefits. Due to the frequent colonisation of the lower respiratory tract in mechanically ventilated patients, there is an ever-present possibility of microbiological samples being contaminated by bystander organisms. This, coupled with the frequency of alveolar infiltrates arising from sterile insults, risks over-treatment and antimicrobial-associated harm. The use of bronchoscopic sampling to obtain protected lower respiratory samples has long been advocated to overcome this problem. The use of bronchoscopy further enables accurate cytological assessment of the alveolar space and direct inspection of the proximal airways for signs of fungal infection or alternative pathologies. With a growing range of molecular techniques, including those based on nucleic acid amplification and even alveolar visualisation and direct bacterial detection, the potential for bronchoscopy is increasing concomitantly. Despite this, there remain concerns regarding the safety of the technique and its benefits versus less invasive sampling techniques. These discussions are reflected in the lack of consensus among international guidelines on the topic. This review will consider the benefits and challenges of diagnostic bronchoscopy in the context of severe respiratory infection.

Sex- and time-dependent role of insulin regulated aminopeptidase in lipopolysaccharide-induced inflammation

The enzyme, insulin regulated aminopeptidase (IRAP), is expressed in multiple immune cells such as macrophages, dendritic cells and T cells, where it plays a role in regulating the innate and adaptive immune response. There is a genetic association between IRAP and survival outcomes in patients with septic shock where a variant of its gene was found to be associated with increased 28-day mortality. This study investigated the role for IRAP in a lipopolysaccharide (LPS)-induced inflammatory response which is thought to model facets of the systemic inflammation observed in the early stages of human gram-negative sepsis. The frequencies and activation of splenic immune cell populations were investigated in the IRAP knockout (KO) mice compared to the wildtype controls over a period of 4-, 24-, or 48-hours following LPS stimulation. Dendritic cells isolated from the spleen of female IRAP KO mice, displayed significant increases in the activation markers CD40, CD86 and MHCII at 24 hours after LPS induction. A modest heightened pro-inflammatory response to LPS was observed with increased expression of activation marker CD40 in M1 macrophages from male IRAP knockout mice. Observations in vitro in bone marrow-derived macrophages (BMDM) revealed a heightened pro-inflammatory response to LPS with significant increases in the expression of CD40 in IRAP deficient cells compared with BMDM from WT mice. The heightened LPS-induced response was associated with increased pro-inflammatory cytokine secretion in these BMDM cells. A genotype difference was also detected in the BMDM from female mice displaying suppression of the LPS-induced increases in the activation markers CD40, CD86, CD80 and MHCII in IRAP deficient cells. Thus, this study suggests that IRAP plays specific time- and sex-dependent roles in the LPS-induced inflammatory response in dendritic cells and macrophages.

Identification of key biomarkers and therapeutic targets in sepsis through coagulation-related gene expression and immune pathway analysis

Sepsis, characterized by a widespread and dysregulated immune response to infection leading to organ dysfunction, presents significant challenges in diagnosis and treatment. In this study, we investigated 203 coagulation-related genes in sepsis patients to explore their roles in the disease. Through differential gene expression analysis, we identified 20 genes with altered expression patterns. Subsequent correlation analysis, visualized through circos plots and heatmaps, revealed significant relationships among these genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses indicated that these genes are involved in immune response activation, coagulation, and immune receptor activity. Disease Ontology (DO) enrichment analysis further linked these genes to autoimmune hemolytic anemia and tumor-related signaling pathways. Additionally, the CIBERSORT analysis highlighted differences in immune cell composition in sepsis patients, revealing an increase in neutrophils and monocytes and a decrease in inactive NK cells, CD8 T cells, and B cells. We employed machine learning techniques, including random forest and SVM, to construct a diagnostic model, identifying FCER1G and FYN as key biomarkers. These biomarkers were validated through their expression levels and ROC curve analysis in an independent validation cohort, demonstrating strong diagnostic potential. Single-cell analysis from the GSE167363 dataset further confirmed the distinct expression profiles of these genes across various cell types, with FCER1G predominantly expressed in monocytes, NK cells, and platelets, and FYN in CD4+ T cells and NK cells. Enrichment analysis via GSEA and ssGSEA revealed that these genes are involved in critical pathways, including intestinal immune networks, fatty acid synthesis, and antigen processing. In conclusion, our comprehensive analysis identifies FCER1G and FYN as promising biomarkers for sepsis, providing valuable insights into the molecular mechanisms of this complex condition. These findings offer new avenues for the development of targeted diagnostic and therapeutic strategies in sepsis management.

Investigating hub genes in the relationship between septic cardiomyopathy and cuproptosis and potential Chinese herbal drug candidates with bioinformatic tools

BACKGROUND

The aim of this study was using bioinformatic tools to identify hub genes in the relationship between septic cardiomyopathy (SCM) and cuproptosis and predict potential Chinese herbal drug candidates.

METHODS

SCM datasets were downloaded from the gene expression omnibus. Cuproptosis related genes were collected from a research published on Science in March, 2022. The expression profiles of genes related to cuproptosis in SCM were extracted. Differentially expressed genes (DEGs) were analyzed using R package limma. A single-sample gene set enrichment analysis was conducted to measure the correlation between DEGs and immune cell infiltration. Hub genes were screened out by random forest model. Finally, HERB database and COREMINE database were used to predict Chinese herbal drugs for hub genes and carry out molecular docking.

RESULTS

A total of 9 DEGs were identified. Cuproptosis differential genes PDHB, DLAT, DLD, FDX1, GCSH, LIAS were significantly correlated with one or more cells and their functions in immune infiltration. The random forest model screened pyruvate dehydrogenase E1 beta subunit (PDHB) as the hub gene. PDHB was negatively correlated with Plasmacytoid dendritic cell infiltration. Pyruvic acid, rhodioloside and adenosine were predicted with PDHB as the target, and all three components are able to bind to PDHB.

CONCLUSIONS

Cuproptosis related gene PDHB is associated with the occurrence and immune infiltration of septic cardiomyopathy. Rhodioloside and other Chinese herbal drugs may play a role in the treatment of SCM by regulating the expression of PDHB.

FGF1 attenuates sepsis-induced coagulation dysfunction and hepatic injury via IL6/STAT3 pathway inhibition

BACKGROUND & AIMS

Sepsis, a globally prevalent and highly lethal condition, remains a critical medical challenge. This investigation aims to assess the relevance of FGF1 as a potential therapeutic target for sepsis.

METHODS

Sepsis was induced in C57BL/6 mice through LPS administration to establish an in vivo animal model. Various in vitro assays were conducted using human umbilical vein endothelial cells to elucidate the role of FGF1 in the disruption of the coagulation system and liver injury associated with sepsis, as well as to explore its underlying molecular mechanisms.

RESULTS

In in vivo experiments, FGF1 ameliorated coagulation system disruption in septic mice by reducing the levels of pro-inflammatory and coagulation-related factors in the bloodstream. FGF1 also enhanced liver function in septic mice, mitigating liver inflammation and cell apoptosis, fostering liver vascular regeneration, increasing liver blood perfusion, and improving mouse survival. In vitro experiments demonstrated that FGF1 could inhibit LPS-induced inflammatory responses and apoptosis in endothelial cells, fortify endothelial cell barrier function, decrease endothelial cell permeability, promote endothelial cell proliferation, and restore endothelial cell tube-forming ability. Both in vivo and in vitro experiments substantiated that FGF1 improved sepsis by inhibiting the IL-6/STAT3 signaling pathway.

CONCLUSION

In summary, our study indicates that FGF1 mitigates excessive inflammatory responses in sepsis by suppressing the IL-6/STAT3 signaling pathway, thereby improving systemic blood circulation and ameliorating liver damage in septic organisms. Consequently, this research identifies FGF1 as a potential clinical target for the treatment of human sepsis.

Factors affecting neutrophil functions during sepsis: human microbiome and epigenetics

Sepsis is a severe disease that occurs when the body's immune system reacts excessively to infection. The body's response, which includes an intense antibacterial reaction, can damage its tissues and organs. Neutrophils are the major components of white blood cells in circulation, play a vital role in innate immunity while fighting against infections, and are considered a feature determining sepsis classification. There is a plethora of basic research detailing neutrophil functioning, among which, the study of neutrophil extracellular traps is providing novel insights into mechanisms and treatments of sepsis. This review explores their functions, dysfunctions, and influences in the context of sepsis. The interplay between neutrophils and the human microbiome and the impact of DNA methylation on neutrophil function in sepsis are crucial areas of study. The interaction between neutrophils and the human microbiome is complex, particularly in the context of sepsis, where dysbiosis may occur. We highlight the importance of deciphering neutrophils' functional alterations and their epigenetic features in sepsis because it is critical for defining sepsis endotypes and opening up the possibility for novel diagnostic methods and therapy. Specifically, epigenetic signatures are pivotal since they will provide a novel implication for a sepsis diagnostic method when used in combination with the cell-free DNA. Research is exploring how specific patterns of DNA methylation in neutrophils, detectable in cell-free DNA, could serve as biomarkers for the early detection of sepsis.

Nanotechnology-Mediated Immunomodulation Strategy for Inflammation Resolution

Inflammation serves as a common characteristic across a wide range of diseases and plays a vital role in maintaining homeostasis. Inflammation can lead to tissue damage and the onset of inflammatory diseases. Although significant progress is made in anti-inflammation in recent years, the current clinical approaches mainly rely on the systemic administration of corticosteroids and antibiotics, which only provide short-term relief. Recently, immunomodulatory approaches have emerged as promising strategies for facilitating the resolution of inflammation. Especially, the advanced nanosystems with unique biocompatibility and multifunctionality have provided an ideal platform for immunomodulation. In this review, the pathophysiology of inflammation and current therapeutic strategies are summarized. It is mainly focused on the nanomedicines that modulate the inflammatory signaling pathways, inflammatory cells, oxidative stress, and inflammation targeting. Finally, the challenges and opportunities of nanomaterials in addressing inflammation are also discussed. The nanotechnology-mediated immunomodulation will open a new treatment strategy for inflammation therapy.

Temperature trajectories and mortality in hypothermic sepsis patients

OBJECTIVES

Hypothermia is associated with poor outcomes in sepsis patients, and hypothermic sepsis patients exhibit temperature alterations during initial treatment. The objective of this study was to classify hypothermic sepsis patients based on body temperature trajectories and investigate the associations of these patients with 28-day mortality.

METHODS

This was a retrospective analysis of prospectively collected data from adult sepsis or septic shock patients who visited three emergency departments between August 2014 and December 2019. Hypothermic sepsis was defined as an initial body temperature <36 °C. delta temperature was calculated by subtracting the 0 h body temperature from the 6 h body temperature. We divided the patients into three groups according to delta temperature: Group A (delta temperature ≤ 0), Group B (0 < delta temperature ≤ 1) and Group C (delta temperature > 1). The primary outcome was 28-day mortality, and a multivariable Cox proportional hazards regression model was generated.

RESULTS

Among 7344 patients with sepsis or septic shock, 325 hypothermic patients were included in the analysis, and the overall mortality rate was 36%. While initial body temperature was not different between survivors and nonsurvivors, survivors exhibited a higher body temperature at 6 h. The 28-day mortality rates for Groups A, B and C were 53.1%, 36.0%, and 30.0%, respectively, and Group A had significantly higher mortality than Group C did (p < 0.05). Group C demonstrated a 44.2% decrease in 28-day mortality compared to Group A (adjusted hazard ratio of 0.558; 95% confidence interval of 0.330-0.941).

CONCLUSIONS

In hypothermic sepsis patients, an increase of 1 °C or more in body temperature after the initial 6 h is associated with a reduced risk of 28-day mortality.

A New Strategy for Targeting UCP2 to Modulate Glycolytic Reprogramming as a Treatment for Sepsis A New Strategy for Targeting UCP2

Sepsis is a severe and life-threatening disease caused by infection, characterized by a dysregulated immune response. Unfortunately, effective treatment strategies for sepsis are still lacking. The intricate interplay between metabolism and the immune system limits the treatment options for sepsis. During sepsis, there is a profound shift in cellular energy metabolism, which triggers a metabolic reprogramming of immune cells. This metabolic alteration impairs immune responses, giving rise to excessive inflammation and immune suppression. Recent research has demonstrated that UCP2 not only serves as a critical target in sepsis but also functions as a key metabolic switch involved in immune cell-mediated inflammatory responses. However, the regulatory mechanisms underlying this modulation are complex. This article focuses on UCP2 as a target and discusses metabolic reprogramming during sepsis and the complex regulatory mechanisms between different stages of inflammation. Our research indicates that overexpression of UCP2 reduces the Warburg effect, restores mitochondrial function, and improves the prognosis of sepsis. This discovery aims to provide a promising approach to address the significant challenges associated with metabolic dysfunction and immune paralysis.