Unraveling the immunological landscape in acute pancreatitis progression to sepsis: insights from a Mendelian randomization study on immune cell traits.

Background: Acute pancreatitis (AP) is a severe digestive system disorder with a significant risk of progressing to sepsis, a major cause of mortality. Unraveling the immunological pathways in AP is essential for developing effective treatments, particularly understanding the role of specific immune cell traits in this progression. Methods: Employing a bidirectional two-sample Mendelian Randomization (MR) approach, this study first examined the causal relationship between AP and 731 immune cell traits to identify those significantly associated with AP. Subsequently, we explored the causal associations between 731 immune cell traits and sepsis. The analysis utilized extensive genome-wide association studies (GWAS) summary datasets, with a focus on identifying common immune cell traits with statistically significant causal associations between AP and sepsis. Results: Our investigation identified 44 immune cell traits unidirectionally associated with AP and 36 traits unidirectionally associated with sepsis. Among these, CD127 on CD28+ CD45RA- CD8+ T cells emerged as a common mediator, accounting for 5.296% of the increased risk of sepsis in AP patients. This finding highlights the significant role of specific memory CD8+ T cells in the pathophysiology of AP and its progression to sepsis. Conclusion: This study elucidates the critical role of specific immune cell traits, particularly CD127hi memory CD8+ T cells, in the progression of AP to sepsis. Our findings provide a foundation for future research into targeted immune-modulatory therapies, potentially improving patient outcomes in AP-related sepsis and offering new insights into the complex immunological dynamics of this condition.

Development and external validation of a nomogram for the early prediction of acute kidney injury in septic patients: a multicenter retrospective clinical study.

Background and purpose: Acute kidney injury (AKI) is a common serious complication in sepsis patients with a high mortality rate. This study aimed to develop and validate a predictive model for sepsis associated acute kidney injury (SA-AKI). Methods: In our study, we retrospectively constructed a development cohort comprising 733 septic patients admitted to eight Grade-A tertiary hospitals in Shanghai from January 2021 to October 2022. Additionally, we established an external validation cohort consisting of 336 septic patients admitted to our hospital from January 2017 to December 2019. Risk predictors were selected by LASSO regression, and a corresponding nomogram was constructed. We evaluated the model's discrimination, precision and clinical benefit through receiver operating characteristic (ROC) curves, calibration plots, decision curve analysis (DCA) and clinical impact curves (CIC) in both internal and external validation. Results: AKI incidence was 53.2% in the development cohort and 48.2% in the external validation cohort. The model included five independent indicators: chronic kidney disease stages 1 to 3, blood urea nitrogen, procalcitonin, D-dimer and creatine kinase isoenzyme. The AUC of the model in the development and validation cohorts was 0.914 (95% CI, 0.894-0.934) and 0.923 (95% CI, 0.895-0.952), respectively. The calibration plot, DCA, and CIC demonstrated the model's favorable clinical applicability. Conclusion: We developed and validated a robust nomogram model, which might identify patients at risk of SA-AKI and promising for clinical applications.

MSCs-derived extracellular vesicles alleviate sepsis-associated liver dysfunction by inhibiting macrophage glycolysis-mediated inflammatory response.

Sepsis-associated liver dysfunction (SALD) aggravates the disease progression and prognosis of patients. Macrophages in the liver play a crucial role in the occurrence and development of SALD. Human umbilical cord mesenchymal stem cells (MSCs), by secreting extracellular vesicles (EVs), show beneficial effects in various inflammatory diseases. However, whether MSC-derived EVs (MSC-EVs) could ameliorate the inflammatory response in liver macrophages and the underlying mechanisms remain unclear. In this study, a mouse model of sepsis induced by lipopolysaccharide (LPS) challenge was used to investigate the immunomodulatory functions of MSC-EVs in SALD. LPS-stimulated primary Kupffer cells (KCs) and Raw264.7 were used to further explore the potential mechanisms of MSC-EVs in regulating the inflammatory response of macrophages. The results showed that MSC-EVs alleviated liver tissue injury and facilitated the polarization of M1 to M2 macrophages. Further in vitro studies confirmed that MSC-EVs treatment significantly downregulated the expression of several enzymes related to glycolysis and reduced the glycolytic flux by inhibiting hypoxia-inducible factor 1α (HIF-1α) expression, thus effectively inhibiting the inflammatory responses of macrophages. These findings reveal that the application of MSC-EVs might be a potential therapeutic strategy for treating SALD.

Septic macrophages induce T cells immunosuppression in a cell-cell contact manner with the involvement of CR3.

Background: In addition to excessive inflammation, immunosuppression has been recognized as a contributing factor to poor prognosis of sepsis. Although it has been reported that T cells can become functionally impaired during sepsis, the underlying mechanisms responsible for this phenomenon remain unclear. This study aims to elucidate the mechanisms by which macrophages induce immunosuppression in T cells. Methods: In an in vivo setting, C57BL-6J mice were subjected to cecal ligation and puncture (CLP) with or without depletion of macrophages, and the functions of T cells were assessed. In vitro experiments involved direct co-culture or separate culture of T cells and septic macrophages using a transwell system, followed by analysis of T cell immunity. Additionally, a siRNA targeting CD18 on macrophages was utilized to investigate the role of complement receptor 3 (CR3). Results: Both macrophages and T cells exhibited immunosuppression during sepsis. In the in vivo experiments, the absence of macrophages partially alleviated T cell immunosuppression, as evidenced by restored vitality, increased production of TNF-α and IFN-γ, elevated CD8+ T cell levels, and decreased CD25+ T cell levels. In the in vitro experiments, direct co-culture of T cells with septic macrophages resulted in diminished T cell immunity, which was improved when T cells and macrophages were separated by a chamber wall. The expression of CR3 (CD11b/CD18) was upregulated on septic macrophages, and silencing of CD18 led to decreased TNF-α production by T cells, reduced CD4+ T cell numbers, and increased CD25+ T cell numbers. Conclusion: In sepsis, macrophages induce immunosuppression in T cells through direct cell-cell contact, with the involvement of CR3.

Factors associated with prolonged viral shedding of SARS-CoV-2 Omicron variant infection in Shanghai: A multicenter, retrospective, observational study.

Shanghai has faced an unprecedented COVID-19 pandemic with the BA.2.2 strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron infection. Comprehensive insights into its epidemiology, clinical manifestations, and viral shedding dynamics are currently limited. This study encompasses 208373 COVID-19 patients that were infected with the Omicron BA.2.2 sub-lineage in Shanghai, China. Demographic information, clinical symptoms, vaccination status, isolation status, as well as viral shedding time (VST) were recorded. Among the COVID-19 patients included in this study, 187124 were asymptomatic and 21249 exhibited mild symptoms. The median VST was 8.3 days. The common clinical symptoms included fever, persistent cough, phlegm, sore throat, and gastrointestinal symptoms. Factors such as advanced age, presence of comorbidities, mild symptomatology, and delayed isolation correlated with extended VST. Conversely, female gender and administration of two or three vaccine doses correlated with a reduction in VST. This investigation offers an in-depth characterization and analytical perspective on Shanghai's recent COVID-19 surge. Prolonged viral shedding of SARS-CoV-2 was observed in elderly, male, symptomatic patients, and those with comorbidity. Female, individuals with two or three vaccine doses, as well as those isolated early, shows an effective reduced VST.

ATP-citrate lyase controls endothelial gluco-lipogenic metabolism and vascular inflammation in sepsis-associated organ injury.

Sepsis involves endothelial cell (EC) dysfunction, which contributes to multiple organ failure. To improve therapeutic prospects, elucidating molecular mechanisms of vascular dysfunction is of the essence. ATP-citrate lyase (ACLY) directs glucose metabolic fluxes to de novo lipogenesis by generating acetyl-Co-enzyme A (acetyl-CoA), which facilitates transcriptional priming via protein acetylation. It is well illustrated that ACLY participates in promoting cancer metastasis and fatty liver diseases. Its biological functions in ECs during sepsis remain unclear. We found that plasma levels of ACLY were increased in septic patients and were positively correlated with interleukin (IL)-6, soluble E-selectin (sE-selectin), soluble vascular cell adhesion molecule 1 (sVCAM-1), and lactate levels. ACLY inhibition significantly ameliorated lipopolysaccharide challenge-induced EC proinflammatory response in vitro and organ injury in vivo. The metabolomic analysis revealed that ACLY blockade fostered ECs a quiescent status by reducing the levels of glycolytic and lipogenic metabolites. Mechanistically, ACLY promoted forkhead box O1 (FoxO1) and histone H3 acetylation, thereby increasing the transcription of c-Myc (MYC) to facilitate the expression of proinflammatory and gluco-lipogenic genes. Our findings revealed that ACLY promoted EC gluco-lipogenic metabolism and proinflammatory response through acetylation-mediated MYC transcription, suggesting ACLY as the potential therapeutic target for treating sepsis-associated EC dysfunction and organ injury.

Comorbidities prolonged viral shedding of patients infected with SARS-CoV-2 omicron variant in Shanghai: A multi-center, retrospective, observational study.

BACKGROUND: As the omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surges amid the coronavirus disease 2019 (COVID-19) pandemic, there is limited comorbidities data associated with viral shedding time (VST). We aimed to investigate the effect of comorbidities on VST in asymptomatic and mild patients with omicron. METHODS: A multi-center, retrospective, observational study was conducted from March 12, 2022 to May 24, 2022 in Shanghai. The analysis was adjusted for patients' baseline demographic, using log-rank test and logistic regression model. RESULTS: The study enrolled 198,262 subjects. The median duration of viral shedding time (VST) was 8.29 days. The number of cumulative viral shedding events was significantly lower in the chronic obstructive pulmonary disease (COPD), hyperlipidemia, diabetes, urinary system disease, and cardiocerebrovascular disease than in the no corresponding comorbidities group. Patients with comorbidities had a lower incidence of viral shedding, and the most significant independent risk factor is COPD (aOR 1.78, 95% CI: 1.53-2.08, p < 0.001). Across different age ranges, the comorbidities affecting viral shedding also differ, with the greatest risk factors for viral shedding being hyperlipidemia (aOR 2.23, 95% CI: 1.50-3.31, p < 0.001) and COPD (aOR 1.85, 95% CI: 1.50-2.28, p < 0.001) between ages of 18-39 and 40-64, and thyroid dysfunction (aOR 2.36, 95% CI: 1.60-3.47, p < 0.001) above age 64. CONCLUSIONS: Omicron-infected patients with comorbidities might prolong the VST. The independent risk factors also differ across age ranges, suggesting that providing targeted effective prevention and control guidance and allocating appropriate resources to different populations should be a crucial strategy.

Mucin 1 Inhibits Ferroptosis and Sensitizes Vitamin E to Alleviate Sepsis-Induced Acute Lung Injury through GSK3ß/Keap1-Nrf2-GPX4 Pathway.

Background: Ferroptosis is a nonapoptotic form of programmed cell death, which may be related to the occurrence and development of sepsis-induced acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). Mucin 1 (MUC1) is a kind of macromolecule transmembrane glycoprotein. Previous studies have shown that MUC1 could relieve ALI in sepsis and predict whether sepsis patients would develop into ARDS. However, the role of MUC1 in the ferroptosis of sepsis-induced ALI/ARDS remains unclear. Materials and Methods: Sera samples from 50 patients with sepsis/septic shock were used to detect iron metabolism-related markers. Western blot and qRT-PCR were conducted to detect the expression levels of ferroptosis-related genes. Enzyme-linked immunosorbent assay (ELISA) was performed to evaluate inflammatory factors. Transmission electron microscopy (TEM) was used to assess morphological changes of cells. Results: The results showed that the iron metabolism-related indicators in sepsis-induced ARDS patients changed significantly, suggesting the iron metabolism disorder. The expression levels of ferroptosis-related genes in lung tissues of sepsis had marked changes, and the lipid peroxidation levels increased, while Ferrostatin-1 (Fer-1) could reverse the above results, which confirmed the occurrence of ferroptosis. In terms of mechanism studies, inhibition of MUC1 dimerization could increase the expression level of Keap1, reduce the phosphorylation level of GSK3ß, inhibit the entry of Nrf2 into the nucleus, further inhibit the expression level of GPX4, enhance the lipid peroxidation level of lung tissues, trigger ferroptosis, and aggravate lung injury. Besides, inhibiting MUC1 reversed the alleviating effect of vitamin E on ALI caused by sepsis, increased the aggregation of inflammatory cells in lung tissues, and aggravated alveolar injury and edema. Conclusions: Our study was the first to explore the changes of iron metabolism indicators in ALI/ARDS of sepsis, clarify the important role of ferroptosis in ALI/ARDS induced by sepsis, and reveal the effects and specific mechanisms of MUC1 in regulating ferroptosis, as well as the sensitization on vitamin E.

OLFM4 Regulates Lung Epithelial Cell Function in Sepsis-Associated ARDS/ALI via LDHA-Mediated NF-κB Signaling.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is one of the leading causes of death in patients with sepsis. As such, early and accurate identification of sepsis-related ARDS is critical. METHODS: Bioinformatic analysis was used to explore the GEO datasets. ELISA method was used to detect the plasma or cellular supernatant of relevant proteins. Quantitative real-time PCR was used for mRNA measurements and Western blot was applied for protein measurements. Immunohistochemistry staining and Immunofluorescence staining were used to identify the localization of OLFM4. Cecal ligation and puncture (CLP) model was used to establish sepsis model. RESULTS: The bioinformatic analysis results identified ten genes (CAMP, LTF, RETN, LCN2, ELANE, PGLYRP1, BPI, DEFA4, MPO, and OLFM4) as critical in sepsis and sepsis-related ARDS. OLFM4, LCN2, and BPI were further demonstrated to have diagnostic values in sepsis-related ARDS. Plasma expression of OLFM4 and LCN2 was also upregulated in sepsis-related ARDS patients compared to septic patients alone. OLFM4 expression was significantly increased in the lung tissues of septic mice and was co-localized with Ly6G+ neutrophils, F4/80+ macrophages and pro-surfactant C+ lung epithelial cells. In vitro data showed that OLFM4 expression in lung epithelial cells was downregulated upon LPS stimulation, whereas neutrophil media induced OLFM4 expression in lung epithelial cells. Overexpression of OLFM4 and treatment with recombinant OLFM4 effectively suppressed LPS-induced pro-inflammatory responses in lung epithelial cells. Furthermore, the increased levels of LDHA phosphorylation and the downstream NF-κB activation induced by LPS in epithelial cells were effectively diminished by OLFM4 overexpression and recombinant OLFM4 treatment via a reduction in ROS production and HIF1α expression. CONCLUSION: OLFM4 may regulate the pro-inflammatory response of lung epithelial cells in sepsis-related ARDS by modulating metabolic disorders; this result could provide new insights into the treatment of sepsis-induced ARDS.

The Role and Mechanism of Pyroptosis and Potential Therapeutic Targets in Sepsis: A Review.

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Recently was been found that pyroptosis is a unique form of proinflammatory programmed death, that is different from apoptosis. A growing number of studies have investigated pyroptosis and its relationship with sepsis, including the mechanisms, role, and relevant targets of pyroptosis in sepsis. While moderate pyroptosis in sepsis can control pathogen infection, excessive pyroptosis can lead to a dysregulated host immune response and even organ dysfunction. This review provides an overview of the mechanisms and potential therapeutic targets underlying pyroptosis in sepsis identified in recent decades, looking forward to the future direction of treatment for sepsis.

Identification of Significant Genes and Pathways in Acute Pancreatitis via Bioinformatical Analysis.

BACKGROUND AND AIMS: Acute pancreatitis (AP) is one of the common acute abdominal diseases with complicated pathogenesis. The purpose of this study is to identify the differentially expressed genes (DEGs) in the pancreas and underlying mechanisms. METHODS: Gene expression profiles of GSE109227 and GSE65146 were available from GEO database. Then, an integrated analysis of these genes was performed, including gene ontology (GO) and KEGG pathway enrichment analysis, protein-protein interaction (PPI) network construction, core gene correlation analysis, transcription factors (TFs) prediction, and expression level evaluation in human organs. RESULTS: A total number of 92 differential expressed genes were screened from the datasets, including 81 up-regulated genes and 11 down-regulated genes. The up-regulated genes were mainly enriched in the biological process, such as sarcomere organization, actin cytoskeleton organization, tumor necrosis factor biosynthetic process, response to cytokine, cell-cell adhesion, and the cell migration, and also involved in some signaling pathways, including leukocyte transendothelial migration, proteoglycans in cancer, thyroid cancer, cell adhesion, tight junction, bladder cancer, amoebiasis, glycerolipid metabolism, and VEGF signaling pathway, while down-regulated genes were significantly enriched in the endoplasmic reticulum unfolded protein response, the oxidation-reduction, and no significant signaling pathways. CDH1 and CLDN4 were identified as core genes by PPI network analysis with MCODE plug-in, as well as GO and KEGG re-enrichment. For validation in Gene Expression Profiling Interactive Analysis (GEPIA), CDH1 and CLDN4 were interacting with each other and regulated by the predictive common TFs FOXP3 or USF2. The two core genes and USF2 were expressed in varied human organs including the pancreas, while FOXP3 was not detected in the normal human pancreatic tissues. CONCLUSIONS: This study implied that core gene CDH1 and CLDN4, which might be regulated by FOXP3 or USF2, played a significant role in acute pancreatitis. They could be potential diagnostic and therapeutic targets for AP patients.

The Warburg Effect Promotes Mitochondrial Injury Regulated by Uncoupling Protein-2 in Septic Acute Kidney Injury.

BACKGROUND: Evidence implying that metabolism reprogramming plays an important role in the regulation of sepsis is increasing; however, whether it has a similar role in septic organ dysfunction remains unclear. Here, we provide evidence to support a new role of uncoupling protein-2 (UCP2)-regulated Warburg effect, i.e., aerobic glycolysis, in promoting mitochondrial injury in the kidney. METHODS: To imitate sepsis condition, male C57BL/6 mice were operated by the cecal ligation puncture in vivo, whereas a normal human kidney cell line (HK-2) was treated with lipopolysaccharide in vitro. UCP2 small interfering RNA pretreatment was performed to knock down UCP2 expression in vitro. The glycolysis metabolite was detected by liquid chromatography/tandem mass spectrometry in vivo and detected by commercial kits in vitro. Oxidative phosphorylation level and glycolysis level were monitored by measuring the oxygen consumption rate (indicative of respiration) and extracellular acidification rate (indicative of glycolysis) in vitro. Exogenous lactate was supplied to stimulate HK-2 cells and indicators of mitochondrial dysfunction were also assessed. RESULTS: Aerobic glycolysis is enhanced in septic tubular epithelial cells, and the glycolysis inhibitor 2-deoxyglucose can partially restore mitochondrial membrane potential and decrease the reactive oxygen species production. With the knockdown of UCP2, the aerobic glycolysis level upregulates, and mitochondrial injury increases. CONCLUSIONS: These results provide insights on a new mechanism of metabolic regulation of mitochondrial injury and the importance of targeting aerobic glycolysis for the treatment of septic acute kidney injury.

Identification of Potential Biomarkers and Immune Features of Sepsis Using Bioinformatics Analysis.

Sepsis remains a major global concern and is associated with high mortality and morbidity despite improvements in its management. Markers currently in use have shortcomings such as a lack of specificity and failures in the early detection of sepsis. In this study, we aimed to identify key genes involved in the molecular mechanisms of sepsis and search for potential new biomarkers and treatment targets for sepsis using bioinformatics analyses. Three datasets (GSE95233, GSE57065, and GSE28750) associated with sepsis were downloaded from the public functional genomics data repository Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified using R packages (Affy and limma). Functional enrichment of the DEGs was analyzed with the DAVID database. Protein-protein interaction networks were derived using the STRING database and visualized using Cytoscape software. Potential biomarker genes were analyzed using receiver operating characteristic (ROC) curves in the R package (pROC). The three datasets included 156 whole blood RNA samples from 89 sepsis patients and 67 healthy controls. Between the two groups, 568 DEGs were identified, among which 315 were upregulated and 253 were downregulated in the septic group. These genes were enriched for pathways mainly involved in the innate immune response, T-cell biology, antigen presentation, and natural killer cell function. ROC analyses identified nine genes-LRG1, ELANE, TP53, LCK, TBX21, ZAP70, CD247, ITK, and FYN-as potential new biomarkers for sepsis. Real-time PCR confirmed that the expression of seven of these genes was in accordance with the microarray results. This study revealed imbalanced immune responses at the transcriptomic level during early sepsis and identified nine genes as potential biomarkers for sepsis.

Protective and predictive role of Mucin1 in sepsis-induced ALI/ARDS.

OBJECTIVE: We aimed to investigate whether inhibition of MUC1 would aggravate sepsis-induced ALI, and explore the predictive value of plasma MUC1 for sepsis patients with or without ARDS. MATERIALS AND METHODS: MUC1 siRNA pre-treatment was used to knockdown MUC1 expression in vitro. GO203 was used to inhibit the homodimerization of MUC1-C in vivo. Expression levels of MUC1, TLR 4 and HIF-1α were detected by Western blot. In addition, plasma MUC1 levels of enrolled patients were detected by ELISA on the day of admission and on the 3rd day. ROC curve was used to determine the predictive value of MUC1 in sepsis patients with ARDS. RESULTS: Our results showed that inhibition of MUC1 could aggravate sepsis-induced acute lung injury and increase the expression of inflammatory cytokines in sera and BALF of sepsis mice. At the same time, we confirmed that inhibition of MUC1 could significantly decrease HIF-1α expression and thereby activate the expression level of TLR4. HIF-1α was a negative regulator of TLR-4. In addition, plasma MUC1 levels of sepsis patients with ARDS were significantly higher than those without ARDS and healthy adults. ROC curve showed that predictive value of plasma MUC1 on sepsis with ARDS on the 3rd day of enrollment was higher than the day of enrollment. CONCLUSION: MUC1 could inhibit the expression of TLR-4 by stabilizing HIF-1α, thereby alleviate sepsis-induced lung injury and protect organ function. At the same time, elevated MUC1 levels in plasma had a good predictive valud on whether patients with sepsis would develop ARDS.

Interleukin-22 Might Act as a Double-Edged Sword in Type 2 Diabetes and Coronary Artery Disease.

Type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD) are both characterized by chronic low-grade inflammation. The role of Th17 and its related cytokines in T2DM and CAD is unclear. Here we investigated the serum levels of five Th17-related cytokines (IL-17, IL-22, MIP-3α, IL-9, and IL-27) in T2DM, CAD, and T2DM-CAD comorbidity patients. IL-22 was found to be elevated in all three conditions. Elevated serum IL-22 was independently associated with the incidence of T2DM and CAD. Conversely, IL-22 was found to protect endothelial cells from glucose- and lysophosphatidylcholine- (LPC-) induced injury, and IL-22R1 expression on endothelial cells was increased upon treatment with high glucose and LPC. Blocking of IL-22R1 with IL-22R1 antibody diminished the protective role of IL-22. Our results suggest that IL-22 functions as a double-edged sword in T2DM and CAD and that IL-22 may be used in the treatment of chronic inflammatory diseases such as T2DM and CAD.

The paradoxical role of IL-17 in atherosclerosis.

Atherosclerosis is a chronic inflammatory disease mediated by innate and adaptive immune responses. In recent years, CD4(+) T cells (Th1, Th2, Treg, and Th17) have been increasingly studied for their role in atherosclerosis pathophysiology, atheroma stability, plaque rupture, and life-threatening acute coronary syndrome. IL-17, a marker cytokine of Th17 cells, has been reported to be involved in the pathogenesis of rheumatoid arthritis, inflammatory bowel disease, and asthma. However, its role in atherosclerosis has been poorly characterized. This article provides a comprehensive overview of the role of IL-17 in the development of atherosclerosis and human coronary artery diseases.