TMEM173 Drives Lethal Coagulation in Sepsis

An explainable predictive machine learning model of gangrenous cholecystitis based on clinical data: a retrospective single center study

BACKGROUND

Gangrenous cholecystitis (GC) is a serious clinical condition associated with high morbidity and mortality rates. Machine learning (ML) has significant potential in addressing the diverse characteristics of real data. We aim to develop an explainable and cost-effective predictive model for GC utilizing ML and Shapley Additive explanation (SHAP) algorithm.

RESULTS

This study included a total of 1006 patients with 26 clinical features. Through 5-fold CV, the best performing integrated learning model, XGBoost, was identified. The model was interpreted using SHAP to derive the feature subsets WBC, NLR, D-dimer, Gallbladder width, Fibrinogen, Gallbladder wallness, Hypokalemia or hyponatremia, these subsets comprised the final diagnostic prediction model.

CONCLUSIONS

The study developed a explainable predictive tool for GC at an early stage. This could assist doctors to make quick surgical intervention decisions and perform surgery on patients with GC as soon as possible.

Megakaryocyte in sepsis: the trinity of coagulation, inflammation and immunity

BACKGROUND

Megakaryocytes are traditionally recognized as cells responsible for platelet production. However, beyond their role in thrombopoiesis, megakaryocytes also participate in inflammatory responses and regulate immune system functions. Sepsis, characterized by life-threatening organ dysfunction due to a dysregulated response to infection, prominently features coagulopathy, severe inflammation, and immune dysfunction as key pathophysiological aspects.

AIM OF REVIEW

Given the diverse functions of megakaryocytes, we explore their roles in coagulation in the context of sepsis, and also in inflammatory and immune regulation. We try to infer future research directions and potential strategies for sepsis prevention and treatment based on the properties of megakaryocytes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The purpose of this review is to both highlight and provide an update on the functions of megakaryocytes and pathophysiological changes in sepsis. Specific emphasis is given to the role of megakaryocytes in sepsis, which suggests value of future research and clinical application.

Immune aging and infectious diseases

ABSTRACT

The rise in global life expectancy has led to an increase in the older population, presenting significant challenges in managing infectious diseases. Aging affects the innate and adaptive immune systems, resulting in chronic low-grade inflammation (inflammaging) and immune function decline (immunosenescence). These changes would impair defense mechanisms, increase susceptibility to infections and reduce vaccine efficacy in older adults. Cellular senescence exacerbates these issues by releasing pro-inflammatory factors, further perpetuating chronic inflammation. Moreover, comorbidities, such as cardiovascular disease and diabetes, which are common in older adults, amplify immune dysfunction, while immunosuppressive medications further complicate responses to infections. This review explores the molecular and cellular mechanisms driving inflammaging and immunosenescence, focusing on genomic instability, telomere attrition, and mitochondrial dysfunction. Additionally, we discussed how aging-associated immune alterations influence responses to bacterial, viral, and parasitic infections and evaluated emerging antiaging strategies, aimed at mitigating these effects to improve health outcomes in the aging population.

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.

The dysfunction of complement and coagulation in diseases: the implications for the therapeutic interventions

The complement system, comprising over 30 proteins, is integral to the immune system, and the coagulation system is critical for vascular homeostasis. The activation of the complement and coagulation systems involves an organized proteolytic cascade, and the overactivation of these systems is a central pathogenic mechanism in several diseases. This review describes the role of complement and coagulation system activation in critical illness, particularly sepsis. The complexities of sepsis reveal significant knowledge gaps that can be compared to a profound abyss, highlighting the urgent need for further investigation and exploration. It is well recognized that the inflammatory network, coagulation, and complement systems are integral mechanisms through which multiple factors contribute to increased susceptibility to infection and may result in a disordered immune response during septic events in patients. Given the overlapping pathogenic mechanisms in sepsis, immunomodulatory therapies currently under development may be particularly beneficial for patients with sepsis who have concurrent infections. Herein, we present recent findings regarding the molecular relationships between the coagulation and complement pathways in the advancement of sepsis, and propose potential intervention targets related to the crosstalk between coagulation and complement, aiming to provide more valuable treatment of sepsis.

ER: a critical hub for STING signaling regulation

The Stimulator of Interferon Genes (STING) has a crucial role in mediating the immune response against cytosolic double-stranded DNA (dsDNA) and its activation is critically involved in various diseases. STING is synthesized, modified, and resides in the endoplasmic reticulum (ER), and its ER exit is intimately connected with its signaling. The ER, primarily known for its roles in protein folding, lipid synthesis, and calcium storage, has been identified as a pivotal platform for the regulation of a wide range of STING functions. In this review, we discuss the emerging factors that regulate STING in the ER and examine the interplay between STING signaling and ER pathways, highlighting the impacts of such regulations on immune responses and their potential implications in STING-related disorders.

Zixue Powder attenuates septic thrombosis via reducing neutrophil extracellular trap through blocking platelet STING activation

ETHNOPHARMACOLOGICAL RELEVANCE

Microthrombosis is commonly seen in sepsis and COVID-19. Zixue Powder (ZXP) is a traditional Chinese herbal formula with the potential to treat microvascular and infectious diseases. However, the role and mechanism of ZXP in sepsis-associated thrombosis remain unclear.

AIM OF THE STUDY

Investigating the therapeutic effectiveness and underlying mechanisms of ZXP in septic thrombosis.

MATERIALS AND METHODS

ZXP's compositions were examined with UPLC-QTOF-MS. The efficacy of ZXP on sepsis-induced thrombosis was assessed through various methods: liver tissue pathology was examined using hematoxylin-eosin staining, platelet count was determined by a blood cell analyzer, and an enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of serum tissue factor (TF), thromboxane B2 (TXB2), D-Dimer, and plasminogen activator inhibitor-1 (PAI-1). Neutrophil extracellular traps (NETs) were localized and expressed in liver tissues by immunofluorescence, and the number of NETs in peripheral blood was evaluated by ELISA, which measured the quantity of cf-DNA and MPO-DNA in serum. Platelet P-selectin expression and platelet-neutrophil aggregation were measured by flow cytometry, and plasma P-selectin expression was measured by ELISA. Furthermore, the mechanism of the stimulator of interferon genes (STING) signaling pathway in ZXP's anti-sepsis thrombosis effect was investigated using the STING agonist, Western blot experiments, and immunoprecipitation experiments.

RESULTS

UPLC-QTOF-MS identified 40 chemical compositions of ZXP. Administration of ZXP resulted in significant improvements in liver thrombosis, platelet counts, and levels of TXB2, TF, PAI-1, and D-Dimer in septic rats. Moreover, ZXP inhibited NETs formation in both liver tissue and peripheral blood. Additionally, ZXP decreased the levels of P-selectin in both platelets and plasma, as well as the formation of platelet-neutrophil aggregates, thereby suppressing P-selectin-mediated NETs release. Immunoprecipitation and immunofluorescence staining experiments revealed that ZXP attenuated P-selectin secretion by inhibiting STING-mediated assembly of platelet soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) complex, ultimately preventing inhibition of NETs formation.

CONCLUSION

Our study showed that ZXP effectively mitigates platelet granule secretion primarily through modulation of the STING pathway, consequently impeding NET-associated thrombosis in sepsis. These findings offer valuable insights for future research on the development and application of ZXP.

Non-coding RNAs as key regulators of Gasdermin-D mediated pyroptosis in cancer therapy

Pyroptosis is an inflammatory programed cell death process that plays a crucial role in cancer therapeutic, while Gasdermin-D is a critical effector protein for pyroptosis execution. This review discusses the intricate interactions between Gasdermin-D and some non-coding RNAs (lncRNA, miRNA, siRNA) and their potential application in the regulation of pyroptosis as an anticancer therapy. Correspondingly, these ncRNAs significantly implicate in Gasdermin-D expression and function regarding the pyroptosis pathway. Functioning as competing endogenous RNAs (ceRNAs), these ncRNAs might regulate Gasdermin-D at the molecular level, underlying fatal cell death caused by cancer and tumor propagation. Therefore, these interactions appeal to therapeutics, offering new avenues for cancer treatment. It address this research gap by discussing the possible roles of ncRNAs as mediators of gasdermin-D regulation. It suggest therapeutic strategies based on the current research findings to ensure the interchange between the ideal pyroptosis and cancer cell death.

The emerging role of adaptor proteins in regulating innate immunity of sepsis

Sepsis is a life-threatening syndrome caused by a dysregulated immune response. A large number of adaptor proteins have been found to play a pivotal role in sepsis via protein-protein interactions, thus participating in inflammatory cascades, leading to the generation of numerous inflammatory cytokines, as well as oxidative stress and regulated cell death. Although available strategies for the diagnosis and management of sepsis have improved, effective and specific treatments are lacking. This review focuses on the emerging role of adaptor proteins in regulating the innate immunity of sepsis and evaluates the potential value of adaptor protein-associated therapeutic strategy for sepsis.

Glycosaminoglycans: Participants in Microvascular Coagulation of Sepsis

Sepsis represents a syndromic response to infection and frequently acts as a common pathway leading to fatality in the context of various infectious diseases globally. The pathology of severe sepsis is marked by an excess of inflammation and activated coagulation. A substantial contributor to mortality in sepsis patients is widespread microvascular thrombosis-induced organ dysfunction. Multiple lines of evidence support the notion that sepsis induces endothelial damage, leading to the release of glycosaminoglycans, potentially causing microvascular dysfunction. This review aims to initially elucidate the relationship among endothelial damage, excessive inflammation, and thrombosis in sepsis. Following this, we present a summary of the involvement of glycosaminoglycans in coagulation, elucidating interactions among glycosaminoglycans, platelets, and inflammatory cells. In this section, we also introduce a reasoned generalization of potential signal pathways wherein glycosaminoglycans play a role in clotting. Finally, we discuss current methods for detecting microvascular conditions in sepsis patients from the perspective of glycosaminoglycans. In conclusion, it is imperative to pay closer attention to the role of glycosaminoglycans in the mechanism of microvascular thrombosis in sepsis. Dynamically assessing glycosaminoglycan levels in patients may aid in predicting microvascular conditions, enabling the monitoring of disease progression, adjustment of clinical treatment schemes, and mitigation of both acute and long-term adverse outcomes associated with sepsis.

GSDMD in regulated cell death: A novel therapeutic target for sepsis

Sepsis is a life-threatening multi-organ dysfunction syndrome caused by an abnormal host response to infection. Regulated cell death is essential for maintaining tissue homeostasis and eliminating damaged, infected, or aging cells in multicellular organisms. Gasdermin D, as a member of the gasdermin family, plays a crucial role in the formation of cytoplasmic membrane pores. Research has found that GSDMD plays important roles in various forms of regulated cell death such as pyroptosis, NETosis, and necroptosis. Therefore, through mediating regulated cell death, GSDMD regulates different stages of disease pathophysiology. This article mainly summarizes the concept of GSDMD, its role in regulated cell death, its involvement in organ damage associated with sepsis-related injuries mediated by regulated cell death via GSDMD activation and introduces potential drugs targeting GSDMD that may provide more effective treatment options for sepsis patients through drug modification.

Focus on the cGAS-STING Signaling Pathway in Sepsis and Its Inflammatory Regulatory Effects

Sepsis is a severe systemic inflammatory response commonly occurring in infectious diseases, caused by infection with virulent pathogens. In the pathogenesis of sepsis, the cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase-stimulator of interferon genes (cGAS-STING) signaling pathway serves a crucial role as a fundamental immunoregulatory mechanism. This signaling pathway activates STING upon recognizing intracellular DNA damage and pathogen-derived DNA, subsequently inducing the production of numerous inflammatory mediators, including interferon and inflammatory cytokines, which in turn trigger an inflammatory response. The aim of this paper is to explore the activation mechanism of the cGAS-STING signaling pathway in sepsis and its impact on inflammatory regulation. By delving into the mechanism of action of the cGAS-STING signaling pathway in sepsis, we aim to identify new therapeutic strategies for the treatment and prevention of sepsis.

Newsights of endoplasmic reticulum in hypoxia

The endoplasmic reticulum (ER) is important to cells because of its essential functions, including synthesizing three major nutrients and ion transport. When cellular homeostasis is disrupted, ER quality control (ERQC) system is activated effectively to remove misfolded and unfolded proteins through ER-phagy, ER-related degradation (ERAD), and molecular chaperones. When unfolded protein response (UPR) and ER stress are activated, the cell may be suffering a huge blow, and the most probable consequence is apoptosis. The membrane contact points between the ER and sub-organelles contribute to communication between the organelles. The decrease in oxygen concentration affects the morphology and structure of the ER, thereby affecting its function and further disrupting the stable state of cells, leading to the occurrence of disease. In this study, we describe the functions of ER-, ERQC-, and ER-related membrane contact points and their changes under hypoxia, which will help us further understand ER and treat ER-related diseases.

Inflammasome-independent pyroptosis

Gasdermins are membrane pore-forming proteins that cause pyroptosis, an inflammatory cell death in which cells burst and release cytokines, chemokines, and other host alarm signals, such as ATP and HMGB1, which recruit and activate immune cells at sites of infection and danger. There are five gasdermins in humans - gasdermins A to E. Pyroptosis was first described in myeloid cells and mucosal epithelia, which express gasdermin D and activate it when cytosolic sensors of invasive infection or tissue damage assemble into large macromolecular structures, called inflammasomes. Inflammasomes recruit and activate inflammatory caspases (caspase 1, 4, 5, and 11), which cut gasdermin D to remove an inhibitory C-terminal domain, allowing the N-terminal domain to bind to membrane acidic lipids and oligomerize into pores. Recent studies have identified inflammasome-independent proteolytic pathways that activate gasdermin D and the other gasdermins. Here, we review inflammasome-independent pyroptosis pathways and what is known about their role in normal physiology and disease.

Polyunsaturated fatty acid-derived lipid mediator Resolvin D1 alleviates sepsis-induced disseminated intravascular coagulation via Caspase-1/Gasdermin D pyroptotic pathway

BACKGROUND & AIMS

Sepsis-induced disseminated intravascular coagulation (DIC) is characterised by abnormal blood clotting resulting from severe infection, contributing to organ dysfunction in sepsis. Resolvin D1 (RvD1) is an endogenous lipid mediator, synthesised from the omega-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) through enzymatic processes involving 15-LOX and 5-LOX. RvD1 is recognised for its protective properties against various inflammatory conditions. This study aims to investigate its potential to modulate coagulation dysfunction in sepsis and to evaluate coagulation disorders in septic patients.

METHODS

Sepsis models were established by intraperitoneal injection LPS (20 mg/kg) or cecal ligation and puncture (CLP) followed by injection of RvD1 (10 μg/kg) or saline. The impact of RvD1 on coagulation dysfunction was assessed by clotting time and coagulation indicators such as TAT, D-dimer, PAI-1, and fibrinogen. The activity of the coagulation system in vivo was observed by evaluating dynamic microcirculation, platelets and thrombin in mice using intravital microscopy. The effect of RvD1 on pyroptosis was investigated by measuring NOD-like receptor protein 3 (NLRP3), Caspase-1, Caspase-11, and Gasdermin D (GSDMD) levels via western blot. Caspase-1 knockout mice, GSDMD knockout mice and bone marrow-derived macrophages (BMDMs) were used to elucidate the underlying mechanisms. Lastly, the concentration of RvD1 in plasma from septic patients was quantified to explore its relationship with coagulation and pyroptosis.

RESULTS

RvD1 significantly attenuated coagulation dysfunction in septic mice induced by LPS and CLP, and inhibited Caspase-1/GSDMD-dependent pyroptosis in septic mice and bone marrow-derived macrophages. In septic patients, the plasma concentrations of RvD1 was negatively correlated with both coagulation-related indicators and markers of GSDMD activation.

CONCLUSION

The results suggest that RvD1 can improve coagulation dysfunction in sepsis by regulating the Caspase-1/GSDMD pyroptotic pathway. Additionally, the concentration of RvD1 in septic patient plasma is related to prognosis and DIC development. RvD1 could be a potential biomarker and a promising therapeutic alternative in sepsis-induced DIC.

Targeting STING elicits GSDMD-dependent pyroptosis and boosts anti-tumor immunity in renal cell carcinoma

While Stimulator-of-interferon genes (STING) is an innate immune adapter cruicial for sensing cytosolic DNA and modulating immune microenvironment, its tumor-promoting role in tumor survival and immune evasion remains largely unknown. Here we reported that renal cancer cells are exceptionally dependent on STING for survival and evading immunosurveillance via suppressing ER stress-mediated pyroptosis. We found that STING is significantly amplified and upregulated in clear cell renal cell carcinoma (ccRCC), and its elevated expression is associated with worse clinical outcomes. Mechanically, STING depletion in RCC cells specifically triggers activation of the PERK/eIF2α/ATF4/CHOP pathway and activates cleavage of Caspase-8, thereby inducing GSDMD-mediated pyroptosis, which is independent of the innate immune pathway of STING. Moreover, animal study revealed that STING depletion promoted infiltration of CD4+ and CD8+ T cells, consequently boosting robust antitumor immunity via pyroptosis-induced inflammation. From the perspective of targeted therapy, we found that Compound SP23, a PROTAC STING degrader, demonstrated comparable efficacy to STING depletion both in vitro and in vivo for treatment of ccRCC. These findings collectively unveiled an unforeseen function of STING in regulating GSDMD-dependent pyroptosis, thus regulating immune response in RCC. Consequently, pharmacological degradation of STING by SP23 may become an attractive strategy for treatment of advanced RCC.

STING mediates microglial pyroptosis via interaction with NLRP3 in cerebral ischaemic stroke

BACKGROUND

Ischaemia-evoked neuroinflammation is a critical pathogenic event following ischaemic stroke. Gasdermin D (GSDMD)-associated pyroptosis represents a type of inflammation-associated programmed cell death, which can exacerbate neuroinflammatory responses and brain damage. Stimulator of interferon genes (STING) was recently described as a vital innate immune adaptor protein associated with neuroinflammation. Nevertheless, the regulatory effects of STING on microglial pyroptosis post-stroke have not been well elaborated.

METHODS

STING-knockout and wild-type (WT) mice were subjected to middle cerebral artery occlusion (MCAO). STING small interfering RNA (siRNA) was transfected into BV2 cells before oxygen-glucose deprivation/reoxygenation (OGD/R). STING-overexpressing adeno-associated virus (AAV) and NOD-like receptor family pyrin domain containing 3 (NLRP3) siRNA were administered by stereotaxic injection. 2,3,5-Triphenyl tetrazolium chloride (TTC) staining, TdT-mediated dUTP nick end labeling (TUNEL) staining, Fluoro-Jade C (FJC) staining, neurobehavioural tests, immunohistochemistry, cytokine antibody array assay, transmission electron microscopy, immunoblot, Enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR) were carried out. Co-immunoprecipitation assays were used to investigate the interplay between STING and NLRP3.

RESULTS

STING expression was increased after MCAO and mainly detected on microglia. STING deletion alleviated brain infarction, neuronal damage and neurobehavioural impairment in mice subjected to MCAO. STING knockout suppressed microglial activation and the secretion of inflammatory chemokines, accompanied by mitigation of microglial pyroptosis. Specific upregulation of microglial STING by AAV-F4/80-STING aggravated brain injury and microglial pyroptosis. Mechanistically, co-immunoprecipitation showed that STING bound to NLRP3 in microglia. Supplementation of NLRP3 siRNA reversed AAV-F4/80-STING-induced deterioration of microglial pyroptosis.

CONCLUSIONS

The current findings indicate that STING modulates NLRP3-mediated microglial pyroptosis following MCAO. STING may serve as a therapeutic target in neuroinflammation induced by cerebral ischaemic/reperfusion (I/R) injury.

The gasdermin family: emerging therapeutic targets in diseases

The gasdermin (GSDM) family has garnered significant attention for its pivotal role in immunity and disease as a key player in pyroptosis. This recently characterized class of pore-forming effector proteins is pivotal in orchestrating processes such as membrane permeabilization, pyroptosis, and the follow-up inflammatory response, which are crucial self-defense mechanisms against irritants and infections. GSDMs have been implicated in a range of diseases including, but not limited to, sepsis, viral infections, and cancer, either through involvement in pyroptosis or independently of this process. The regulation of GSDM-mediated pyroptosis is gaining recognition as a promising therapeutic strategy for the treatment of various diseases. Current strategies for inhibiting GSDMD primarily involve binding to GSDMD, blocking GSDMD cleavage or inhibiting GSDMD-N-terminal (NT) oligomerization, albeit with some off-target effects. In this review, we delve into the cutting-edge understanding of the interplay between GSDMs and pyroptosis, elucidate the activation mechanisms of GSDMs, explore their associations with a range of diseases, and discuss recent advancements and potential strategies for developing GSDMD inhibitors.

Lipopolysaccharide delivery systems in innate immunity

Lipopolysaccharide (LPS), a key component of the outer membrane in Gram-negative bacteria (GNB), is widely recognized for its crucial role in mammalian innate immunity and its link to mortality in intensive care units. While its recognition via the Toll-like receptor (TLR)-4 receptor on cell membranes is well established, the activation of the cytosolic receptor caspase-11 by LPS is now known to lead to inflammasome activation and subsequent induction of pyroptosis. Nevertheless, a fundamental question persists regarding the mechanism by which LPS enters host cells. Recent investigations have identified at least four primary pathways that can facilitate this process: bacterial outer membrane vesicles (OMVs); the spike (S) protein of SARS-CoV-2; host-secreted proteins; and host extracellular vesicles (EVs). These delivery systems provide new avenues for therapeutic interventions against sepsis and infectious diseases.

STING contributes to lipopolysaccharide-induced tubular cell inflammation and pyroptosis by activating endoplasmic reticulum stress in acute kidney injury

Recently, innate immunity and inflammation were recognized as the key factors for acute kidney injury (AKI) caused by sepsis, which is closely related to high mortality. Stimulator of interferon genes (STING) has emerged as a critical component of innate immune and inflammatory responses. However, the role of STING in the pathogenesis of septic AKI remains unclear. This study demonstrated that the STING was significantly activated in tubular cells induced by lipopolysaccharide (LPS) in vivo and in vitro. Tubule-specific STING knockout attenuated LPS-induced renal dysfunction and pathological changes. Mechanistically, the STING pathway promotes NOD-like receptor protein 3 (NLRP3) activation. STING triggers endoplasmic reticulum (ER) stress to induce mitochondrial reactive oxygen species (mtROS) overproduction, enhancing thioredoxin-interacting protein activation and association with NLRP3. Eventually, the NLRP3 inflammasome leads to tubular cell inflammation and pyroptosis. This study revealed the STING-regulated network and further identified the STING/ER stress/mtROS/NLRP3 inflammasome axis as an emerging pathway contributing to tubular damage in LPS-induced AKI. Hence, targeting STING may be a promising therapeutic strategy for preventing septic AKI.

The lipid basis of cell death and autophagy

ABBREVIATIONS

ACSL: acyl-CoA synthetase long chain family; DISC: death-inducing signaling complex; DAMPs: danger/damage-associated molecular patterns; Dtgn: dispersed trans-Golgi network; FAR1: fatty acyl-CoA reductase 1; GPX4: glutathione peroxidase 4; LPCAT3: lysophosphatidylcholine acyltransferase 3; LPS: lipopolysaccharide; MUFAs: monounsaturated fatty acids; MOMP: mitochondrial outer membrane permeabilization; MLKL, mixed lineage kinase domain like pseudokinase; oxPAPC: oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine; OxPCs: oxidized phosphatidylcholines; PUFAs: polyunsaturated fatty acids; POR: cytochrome p450 oxidoreductase; PUFAs: polyunsaturated fatty acids; RCD: regulated cell death; RIPK1: receptor interacting serine/threonine kinase 1; SPHK1: sphingosine kinase 1; SOAT1: sterol O-acyltransferase 1; SCP2: sterol carrier protein 2; SFAs: saturated fatty acids; SLC47A1: solute carrier family 47 member 1; SCD: stearoyl-CoA desaturase; VLCFA: very long chain fatty acids.

Rab26 alleviates sepsis-induced immunosuppression as a master regulator of macrophage ferroptosis and polarization shift

Macrophage dysfunction is a significant contributor to more than 70 % of sepsis-related deaths, specifically secondary bacterial infections, during the immunosuppression stage of sepsis. Nevertheless, the role of Rab26 in this context remains unclear. In this study, we observed a substantial decrease in Rab26 expression in macrophages during the immunosuppressive phase of sepsis, which was also found to be suppressed by high extracellular levels of HMGB1. During the progression of sepsis, Rab26 deficiency promotes a polarization shift from the M1 to the M2-like phenotype in macrophages, rendering them susceptible to ferroptosis. Subsequent experimentation has revealed that Rab26 deficiency facilitates the degradation of GPX4, thereby aggravating macrophage ferroptosis through the upregulation of levels of lipid ROS, MDA, and ferrous iron induced by RSL3, a ferroptosis inducer. Additionally, Rab26-deficient mice in the immunosuppressed phase of sepsis exhibit heightened susceptibility to secondary infections, leading to exacerbated lung tissue damage and increased mortality rate. Overall, these findings indicate that Rab26 plays a crucial role in sepsis-induced macrophage immunosuppression by regulating macrophage ferroptosis and polarization. Hence, it represents a potential novel target for sepsis therapy.

Megakaryocytes possess a STING pathway that is transferred to platelets to potentiate activation

Platelets display unexpected roles in immune and coagulation responses. Emerging evidence suggests that STING is implicated in hypercoagulation. STING is an adaptor protein downstream of the DNA sensor cyclic GMP-AMP synthase (cGAS) that is activated by cytosolic microbial and self-DNA during infections, and in the context of loss of cellular integrity, to instigate the production of type-I IFN and pro-inflammatory cytokines. To date, whether the cGAS-STING pathway is present in platelets and contributes to platelet functions is not defined. Using a combination of pharmacological and genetic approaches, we demonstrate here that megakaryocytes and platelets possess a functional cGAS-STING pathway. Our results suggest that in megakaryocytes, STING stimulation activates a type-I IFN response, and during thrombopoiesis, cGAS and STING are transferred to proplatelets. Finally, we show that both murine and human platelets contain cGAS and STING proteins, and the cGAS-STING pathway contributes to potentiation of platelet activation and aggregation. Taken together, these observations establish for the first time a novel role of the cGAS-STING DNA sensing axis in the megakaryocyte and platelet lineage.

The critical roles of STING in mitochondrial homeostasis

The stimulator of interferon genes (STING) is a crucial signaling hub in the immune system's antiviral and antimicrobial defense by detecting exogenous and endogenous DNA. The multifaceted functions of STING have been uncovered gradually during past decades, including homeostasis maintenance and overfull immunity or inflammation induction. However, the subcellular regulation of STING and mitochondria is poorly understood. The main functions of STING are outlined in this review. Moreover, we discuss how mitochondria and STING interact through multiple mechanisms, including the release of mitochondrial DNA (mtDNA), modulation of mitochondria-associated membrane (MAM) and mitochondrial dynamics, alterations in mitochondrial metabolism, regulation of reactive oxygen species (ROS) production, and mitochondria-related cell death. Finally, we discuss how STING is crucial to disease development, providing a novel perspective on its role in cellular physiology and pathology.

Trauma-induced innate immune activation and disseminated intravascular coagulation

Dysregulated innate immunity participates in the pathomechanisms of disseminated intravascular coagulation (DIC) in trauma-induced coagulopathy. Accidental and regulated cell deaths and neutrophil extracellular traps release damage-associated molecular patterns (DAMPs), such as histones, nuclear and mitochondrial DNA, and high-mobility group box 1, into circulation immediately after trauma. DAMP-induced inflammation activation releases tissue factor-bearing procoagulant extracellular vesicles through gasdermin D-mediated pore formation and plasma membrane rupture by regulated cell death. DAMPs also evoke systemic inflammation, platelet, coagulation activation, and impaired fibrinolysis associated with endothelial injury, leading to the dysfunction of anticoagulation systems, which are the main pathophysiological mechanisms of DIC. All these processes induce systemic thrombin generation in vivo, not restricted to the injury sites immediately after trauma. Thrombin generation at the site of injury stops bleeding and maintains homeostasis. However, DIC associated with endothelial injury generates massive thrombin, enhancing protease-activated, receptor-mediated bidirectional interplays between inflammation and coagulation, aggravating the diverse actions of thrombin and disturbing homeostasis. Insufficiently regulated thrombin causes disseminated microvascular thrombosis, resulting in tissue hypoxia due to reduced oxygen delivery, and mitochondrial dysfunction due to DAMPs causes tissue dysoxia. In addition, DAMP-induced calcium influx and overload, as well as neutrophil activation, play a role in endothelial cell injury. Tissue hypoxia and cytotoxicity result in multiple organ dysfunction in DIC after trauma. Controls against dysregulated innate immunity evoking systemic inflammation, thrombin generation, and cytotoxicity are key issues in improving the prognosis of DIC in trauma-induced coagulopathy.

Control of Cell Death in Health and Disease

Apoptosis, necroptosis, and pyroptosis are genetically programmed cell death mechanisms that eliminate obsolete, damaged, infected, and self-reactive cells. Apoptosis fragments cells in a manner that limits immune cell activation, whereas the lytic death programs of necroptosis and pyroptosis release proinflammatory intracellular contents. Apoptosis fine-tunes tissue architecture during mammalian development, promotes tissue homeostasis, and is crucial for averting cancer and autoimmunity. All three cell death mechanisms are deployed to thwart the spread of pathogens. Disabling regulators of cell death signaling in mice has revealed how excessive cell death can fuel acute or chronic inflammation. Here we review strategies for modulating cell death in the context of disease. For example, BCL-2 inhibitor venetoclax, an inducer of apoptosis, is approved for the treatment of certain hematologic malignancies. By contrast, inhibition of RIPK1, NLRP3, GSDMD, or NINJ1 to limit proinflammatory cell death and/or the release of large proinflammatory molecules from dying cells may benefit patients with inflammatory diseases.

Cell death

Cell death supports morphogenesis during development and homeostasis after birth by removing damaged or obsolete cells. It also curtails the spread of pathogens by eliminating infected cells. Cell death can be induced by the genetically programmed suicide mechanisms of apoptosis, necroptosis, and pyroptosis, or it can be a consequence of dysregulated metabolism, as in ferroptosis. Here, we review the signaling mechanisms underlying each cell-death pathway, discuss how impaired or excessive activation of the distinct cell-death processes can promote disease, and highlight existing and potential therapies for redressing imbalances in cell death in cancer and other diseases.

Nuclear localization of STING1 competes with canonical signaling to activate AHR for commensal and intestinal homeostasis

Extensive studies demonstrate the importance of the STING1 (also known as STING) protein as a signaling hub that coordinates immune and autophagic responses to ectopic DNA in the cytoplasm. Here, we report a nuclear function of STING1 in driving the activation of the transcription factor aryl hydrocarbon receptor (AHR) to control gut microbiota composition and homeostasis. This function was independent of DNA sensing and autophagy and showed competitive inhibition with cytoplasmic cyclic guanosine monophosphate (GMP)-AMP synthase (CGAS)-STING1 signaling. Structurally, the cyclic dinucleotide binding domain of STING1 interacted with the AHR N-terminal domain. Proteomic analyses revealed that STING1-mediated transcriptional activation of AHR required additional nuclear partners, including positive and negative regulatory proteins. Although AHR ligands could rescue colitis pathology and dysbiosis in wild-type mice, this protection was abrogated by mutational inactivation of STING1. These findings establish a key framework for understanding the nuclear molecular crosstalk between the microbiota and the immune system.

ITPR1-associated spinocerebellar ataxia with craniofacial features-additional evidence for germline mosaicism

Inositol 1,4,5-triphosphate receptor type 1 (ITPR1) is an endoplasmic reticulum-bound intracellular inositol triphosphate receptor involved in the regulation of intracellular calcium. Pathogenic variants in ITPR1 are associated with spinocerebellar ataxia (SCA) types 15/16 and 29 and have recently been implicated in a facial microsomia syndrome. In this report, we present a family with three affected individuals found to have a heterozygous missense c.800C > T (predicted p.Thr267Met) who present clinically with a SCA29-like syndrome. All three individuals presented with varying degrees of ataxia, developmental delay, and apparent intellectual disability, as well as craniofacial involvement-an uncommon finding in patients with SCA29. The variant was identified using clinical exome sequencing and validated with Sanger sequencing. It is presumed to be inherited via parental germline mosaicism. We present our findings to provide additional evidence for germline mosaic inheritance of SCA29, as well as to expand the clinical phenotype of the syndrome.

The multifunctional protein HMGB1: 50 years of discovery

Fifty years since the initial discovery of HMGB1 in 1973 as a structural protein of chromatin, HMGB1 is now known to regulate diverse biological processes depending on its subcellular or extracellular localization. These functions include promoting DNA damage repair in the nucleus, sensing nucleic acids and inducing innate immune responses and autophagy in the cytosol and binding protein partners in the extracellular environment and stimulating immunoreceptors. In addition, HMGB1 is a broad sensor of cellular stress that balances cell death and survival responses essential for cellular homeostasis and tissue maintenance. HMGB1 is also an important mediator secreted by immune cells that is involved in a range of pathological conditions, including infectious diseases, ischaemia-reperfusion injury, autoimmunity, cardiovascular and neurodegenerative diseases, metabolic disorders and cancer. In this Review, we discuss the signalling mechanisms, cellular functions and clinical relevance of HMGB1 and describe strategies to modify its release and biological activities in the setting of various diseases.

Targeting the cGAS-STING pathway as an inflammatory crossroad in coronavirus disease 2019 (COVID-19)

CONTEXT AND OBJECTIVE

The emerging pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has imposed significant mortality and morbidity on the world. An appropriate immune response is necessary to inhibit SARS-CoV-2 spread throughout the body.

RESULTS

During the early stages of infection, the pathway of stimulators of interferon genes (STING), known as the cGAS-STING pathway, has a significant role in the induction of the antiviral immune response by regulating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Interferon regulatory factor 3 (IRF3), two key pathways responsible for proinflammatory cytokines and type I IFN secretion, respectively.

DISCUSSION

During the late stages of COVID-19, the uncontrolled inflammatory responses, also known as cytokine storm, lead to the progression of the disease and poor prognosis. Hyperactivity of STING, leading to elevated titers of proinflammatory cytokines, including Interleukin-I (IL-1), IL-4, IL-6, IL-18, and tissue necrosis factor-α (TNF-α), is considered one of the primary mechanisms contributing to the cytokine storm in COVID-19.

CONCLUSION

Exploring the underlying molecular processes involved in dysregulated inflammation can bring up novel anti-COVID-19 therapeutic options. In this article, we aim to discuss the role and current studies targeting the cGAS/STING signaling pathway in both early and late stages of COVID-19 and COVID-19-related complications and the therapeutic potential of STING agonists/antagonists. Furthermore, STING agonists have been discussed as a vaccine adjuvant to induce a potent and persistent immune response.

The pathogenesis and potential therapeutic targets in sepsis

Sepsis is defined as "a life-threatening organ dysfunction caused by dysregulated host systemic inflammatory and immune response to infection." At present, sepsis continues to pose a grave healthcare concern worldwide. Despite the use of supportive measures in treating traditional sepsis, such as intravenous fluids, vasoactive substances, and oxygen plus antibiotics to eradicate harmful pathogens, there is an ongoing increase in both the morbidity and mortality associated with sepsis during clinical interventions. Therefore, it is urgent to design specific pharmacologic agents for the treatment of sepsis and convert them into a novel targeted treatment strategy. Herein, we provide an overview of the molecular mechanisms that may be involved in sepsis, such as the inflammatory response, immune dysfunction, complement deactivation, mitochondrial damage, and endoplasmic reticulum stress. Additionally, we highlight important targets involved in sepsis-related regulatory mechanisms, including GSDMD, HMGB1, STING, and SQSTM1, among others. We summarize the latest advancements in potential therapeutic drugs that specifically target these signaling pathways and paramount targets, covering both preclinical studies and clinical trials. In addition, this review provides a detailed description of the crosstalk and function between signaling pathways and vital targets, which provides more opportunities for the clinical development of new treatments for sepsis.

Gasdermins in sepsis

Sepsis is a hyper-heterogeneous syndrome in which the systemic inflammatory response persists throughout the course of the disease and the inflammatory and immune responses are dynamically altered at different pathogenic stages. Gasdermins (GSDMs) proteins are pore-forming executors in the membrane, subsequently mediating the release of pro-inflammatory mediators and inflammatory cell death. With the increasing research on GSDMs proteins and sepsis, it is believed that GSDMs protein are one of the most promising therapeutic targets in sepsis in the future. A more comprehensive and in-depth understanding of the functions of GSDMs proteins in sepsis is important to alleviate the multi-organ dysfunction and reduce sepsis-induced mortality. In this review, we focus on the function of GSDMs proteins, the molecular mechanism of GSDMs involved in sepsis, and the regulatory mechanism of GSDMs-mediated signaling pathways, aiming to provide novel ideas and therapeutic strategies for the diagnosis and treatment of sepsis.

The noncanonical inflammasome-induced pyroptosis and septic shock

Sepsis remains one of the most common and lethal conditions globally. Currently, no proposed target specific to sepsis improves survival in clinical trials. Thus, an in-depth understanding of the pathogenesis of sepsis is needed to propel the discovery of effective treatment. Recently attention to sepsis has intensified because of a growing recognition of a non-canonical inflammasome-triggered lytic mode of cell death termed pyroptosis upon sensing cytosolic lipopolysaccharide (LPS). Although the consequences of activation of the canonical and non-canonical inflammasome are similar, the non-canonical inflammasome formation requires caspase-4/5/11, which enzymatically cleave the pore-forming protein gasdermin D (GSDMD) and thereby cause pyroptosis. The non-canonical inflammasome assembly triggers such inflammatory cell death by itself; or leverages a secondary activation of the canonical NLRP3 inflammasome pathway. Excessive cell death induced by oligomerization of GSDMD and NINJ1 leads to cytokine release and massive tissue damage, facilitating devastating consequences and death. This review summarized the updated mechanisms that initiate and regulate non-canonical inflammasome activation and pyroptosis and highlighted various endogenous or synthetic molecules as potential therapeutic targets for treating sepsis.

Monocyte Tissue Factor Expression: Lipopolysaccharide Induction and Roles in Pathological Activation of Coagulation

The coagulation system is a part of the mammalian host defense system. Pathogens and pathogen components, such as bacterial lipopolysaccharide (LPS), induce tissue factor (TF) expression in circulating monocytes that then activates the coagulation protease cascade. Formation of a clot limits dissemination of pathogens, enhances the recruitment of immune cells, and facilitates killing of pathogens. However, excessive activation of coagulation can lead to thrombosis. Here, we review studies on the mechanism of LPS induction of TF expression in monocytes and its contribution to thrombosis and disseminated intravascular coagulation. Binding of LPS to Toll-like receptor 4 on monocytes induces a transient expression of TF that involves activation of intracellular signaling pathways and binding of various transcription factors, such as c-rel/p65 and c-Fos/c-Jun, to the TF promoter. Inhibition of TF in endotoxemia and sepsis models reduces activation of coagulation and improves survival. Studies with endotoxemic mice showed that hematopoietic cells and myeloid cells play major roles in the activation of coagulation. Monocyte TF expression is also increased after surgery. Activated monocytes release TF-positive extracellular vesicles (EVs) and levels of circulating TF-positive EVs are increased in endotoxemic mice and in patients with sepsis. More recently, it was shown that inflammasomes contribute to the induction of TF expression and activation of coagulation in endotoxemic mice. Taken together, these studies indicate that monocyte TF plays a major role in activation of coagulation. Selective inhibition of monocyte TF expression may reduce pathologic activation of coagulation in sepsis and other diseases without affecting hemostasis.

Novel Substituted Azoloazines with Anticoagulant Activity

Hypercytokinemia, or cytokine storm, often complicates the treatment of viral and bacterial infections, including COVID-19, leading to the risk of thrombosis. However, the use of currently available direct anticoagulants for the treatment of COVID-19 patients is limited due to safety reasons. Therefore, the development of new anticoagulants remains an urgent task for organic and medicinal chemistry. At the same time, new drugs that combine anticoagulant properties with antiviral or antidiabetic activity could be helpfull in the treatment of COVID-19 patients, especially those suffering from such concomitant diseases as arterial hypertension or diabetes. We have synthesized a number of novel substituted azoloazines, some of which have previously been identified as compounds with pronounced antiviral, antibacterial, antidiabetic, antiaggregant, and anticoagulant activity. Two compounds from the family of 1,2,4-triazolo[1,5-a]pyrimidines have demonstrated anticoagulant activity at a level exceeding or at least comparable with that of dabigatran etexilate as the reference compound. 7,5-Di(2-thienyl)-4,5-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine has shown the highest ability to prolong the thrombin time, surpassing this reference drug by 2.2 times. This compound has also exhibited anticoagulant activity associated with the inhibition of thrombin (factor IIa). Moreover, the anticoagulant effect of this substance becomes enhanced under the conditions of a systemic inflammatory reaction.

A nomogram to predict 28-day mortality in neonates with sepsis: a retrospective study based on the MIMIC-III database

Background

Sepsis is the second-leading cause of death in neonates. We established a predictive nomogram to identify critically ill neonates early and reduce the time to treatment.

Methods

It is a retrospective case-control study based on the MIMIC-III database. The study population comprised 924 neonates diagnosed with sepsis.

Results

Neonates with sepsis included in the MIMIC-III database were enrolled, including 880 surviving neonates and 44 neonates who died. In the derivation dataset, stepwise regression and the Lasso algorithm were employed to select predictive variables, and the neonatal sequential organ failure assessment score (nSOFA) was calculated simultaneously. Bootstrap resampling was utilized to perform internal validation. The results indicated that the Lasso algorithm displayed superior discrimination, sensitivity, and specificity relative to stepwise regression and nSOFA scores. After 500 bootstrap resampling tests, the area under the receiver operating characteristic curve (AUC) of the Lasso algorithm was 0.912 (95% CI: 0.870-0.977). The nomogram based on the Lasso algorithm outperformed stepwise regression and nSOFA scores in terms of calibration and the clinical net benefit. This nomogram can assist in prognosticating neonatal severe sepsis and aid in guiding clinical practice while concurrently improving patient outcomes.

Conclusions

The established nomogram revealed that jaundice, corticosteroid use, weight, serum calcium, inotropes and base excess are all important predictors of 28-day mortality in neonates with sepsis. This nomogram can facilitate the early identification of neonates with severe sepsis. However, it still requires further modification and external validation to make it widely available.

Pyroptosis-induced inflammation and tissue damage

Pyroptosis is a programmed necrotic cell death executed by gasdermins, a family of pore-forming proteins. The cleavage of gasdermins by specific proteases enables their pore-forming activity. The activation of the prototype member of the gasdermin family, gasdermin D (GSDMD), is linked to innate immune monitoring by inflammasomes. Additional gasdermins such as GSDMA, GSDMB, GSDMC, and GSDME are activated by inflammasome-independent mechanisms. Pyroptosis is emerging as a key host defense strategy against pathogens. However, excessive pyroptosis causes cytokine storm and detrimental inflammation leading to tissue damage and organ dysfunction. Consequently, dysregulated pyroptotic responses contribute to the pathogenesis of various diseases, including sepsis, atherosclerosis, acute respiratory distress syndrome, and neurodegenerative disorders. This review will discuss the inflammatory consequences of pyroptosis and the mechanisms of pyroptosis-induced tissue damage and disease pathogenesis.

The Redox Protein High-Mobility Group Box 1 in Cell Death and Cancer

Significance: As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer. Recent Advances: HMGB1 is a nonhistone nuclear protein that acts as a deoxyribonucleic acid chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depend on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on the tumor types and stages. Critical Issues: A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions. Future Directions: Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease. Antioxid. Redox Signal. 39, 569-590.

Neutrophil extracellular traps contribute to immunothrombosis formation via the STING pathway in sepsis-associated lung injury

Neutrophil extracellular traps (NETs) are involved in the activation and dysfunction of multiple overlapping and interacting pathways, including the immune response to injury, inflammation, and coagulation, which contribute to the pathogenesis of sepsis-induced acute lung injury (SI-ALI). However, how NETs mediate the relationship between inflammation and coagulation has not been fully clarified. Here, we found that NETs, through stimulator of interferon genes (STING) activation, induced endothelial cell damage with abundant production of tissue factor (TF), which magnified the dysregulation between inflammatory and coagulant responses and resulted in poor prognosis of SI-ALI model mice. Disruption of NETs and inhibition of STING improved the outcomes of septic mice and reduced the inflammatory response and coagulation. Furthermore, Toll-like receptor 2 (TLR2) on the surface of endothelial cells was involved in the interaction between NETs and the STING pathway. Collectively, these findings demonstrate that NETs activate the coagulant cascade in endothelial cells in a STING-dependent manner in the development of SI-ALI.

Sepsis-Induced Acute Lung Injury Is Alleviated by Small Molecules from Dietary Plants via Pyroptosis Modulation

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality, and it has three major pathogeneses, namely alveolar-capillary barrier destruction, elevated gut permeability, and reduced neutrophil extracellular traps (NETS), all of which are pyroptosis-involved. Due to limitations of current agents like adverse reaction superposition, inevitable drug resistance, and relatively heavier financial burden, naturally extracted small-molecule compounds have a broad market even though chemically modified drugs have straightforward efficacy. Despite increased understanding of the molecular biology and mechanism underlying sepsis-induced ARDS, there are no specific reviews concerning how small molecules from dietary plants alleviate sepsis-induced acute lung injury (ALI) via regulating pyroptotic cell death. Herein, we traced and reviewed the molecular underpinnings of sepsis-induced ALI with a focus on small-molecule compounds from dietary plants, the top three categories of which are respectively flavonoids and flavone, terpenoids, and polyphenol and phenolic acids, and how they rescued septic ALI by restraining pyroptosis.

TGF-β uncouples glycolysis and inflammation in macrophages and controls survival during sepsis

Changes in metabolism of macrophages are required to sustain macrophage activation in response to different stimuli. We showed that the cytokine TGF-β (transforming growth factor-β) regulates glycolysis in macrophages independently of inflammatory cytokine production and affects survival in mouse models of sepsis. During macrophage activation, TGF-β increased the expression and activity of the glycolytic enzyme PFKL (phosphofructokinase-1 liver type) and promoted glycolysis but suppressed the production of proinflammatory cytokines. The increase in glycolysis was mediated by an mTOR-c-MYC-dependent pathway, whereas the inhibition of cytokine production was due to activation of the transcriptional coactivator SMAD3 and suppression of the activity of the proinflammatory transcription factors AP-1, NF-κB, and STAT1. In mice with LPS-induced endotoxemia and experimentally induced sepsis, the TGF-β-induced enhancement in macrophage glycolysis led to decreased survival, which was associated with increased blood coagulation. Analysis of septic patient cohorts revealed that the expression of PFKL, TGFBRI (which encodes a TGF-β receptor), and F13A1 (which encodes a coagulation factor) in myeloid cells positively correlated with COVID-19 disease. Thus, these results suggest that TGF-β is a critical regulator of macrophage metabolism and could be a therapeutic target in patients with sepsis.

Copper metabolism in cell death and autophagy

Copper is an essential trace element in biological systems, maintaining the activity of enzymes and the function of transcription factors. However, at high concentrations, copper ions show increased toxicity by inducing regulated cell death, such as apoptosis, paraptosis, pyroptosis, ferroptosis, and cuproptosis. Furthermore, copper ions can trigger macroautophagy/autophagy, a lysosome-dependent degradation pathway that plays a dual role in regulating the survival or death fate of cells under various stress conditions. Pathologically, impaired copper metabolism due to environmental or genetic causes is implicated in a variety of human diseases, such as rare Wilson disease and common cancers. Therapeutically, copper-based compounds are potential chemotherapeutic agents that can be used alone or in combination with other drugs or approaches to treat cancer. Here, we review the progress made in understanding copper metabolic processes and their impact on the regulation of cell death and autophagy. This knowledge may help in the design of future clinical tools to improve cancer diagnosis and treatment.Abbreviations: ACSL4, acyl-CoA synthetase long chain family member 4; AIFM1/AIF, apoptosis inducing factor mitochondria associated 1; AIFM2, apoptosis inducing factor mitochondria associated 2; ALDH, aldehyde dehydrogenase; ALOX, arachidonate lipoxygenase; AMPK, AMP-activated protein kinase; APAF1, apoptotic peptidase activating factor 1; ATF4, activating transcription factor 4; ATG, autophagy related; ATG13, autophagy related 13; ATG5, autophagy related 5; ATOX1, antioxidant 1 copper chaperone; ATP, adenosine triphosphate; ATP7A, ATPase copper transporting alpha; ATP7B, ATPase copper transporting beta; BAK1, BCL2 antagonist/killer 1; BAX, BCL2 associated X apoptosis regulator; BBC3/PUMA, BCL2 binding component 3; BCS, bathocuproinedisulfonic acid; BECN1, beclin 1; BID, BH3 interacting domain death agonist; BRCA1, BRCA1 DNA repair associated; BSO, buthionine sulphoximine; CASP1, caspase 1; CASP3, caspase 3; CASP4/CASP11, caspase 4; CASP5, caspase 5; CASP8, caspase 8; CASP9, caspase 9; CCS, copper chaperone for superoxide dismutase; CD274/PD-L1, CD274 molecule; CDH2, cadherin 2; CDKN1A/p21, cyclin dependent kinase inhibitor 1A; CDKN1B/p27, cyclin-dependent kinase inhibitor 1B; COMMD10, COMM domain containing 10; CoQ10, coenzyme Q 10; CoQ10H2, reduced coenzyme Q 10; COX11, cytochrome c oxidase copper chaperone COX11; COX17, cytochrome c oxidase copper chaperone COX17; CP, ceruloplasmin; CYCS, cytochrome c, somatic; DBH, dopamine beta-hydroxylase; DDIT3/CHOP, DNA damage inducible transcript 3; DLAT, dihydrolipoamide S-acetyltransferase; DTC, diethyldithiocarbamate; EIF2A, eukaryotic translation initiation factor 2A; EIF2AK3/PERK, eukaryotic translation initiation factor 2 alpha kinase 3; ER, endoplasmic reticulum; ESCRT-III, endosomal sorting complex required for transport-III; ETC, electron transport chain; FABP3, fatty acid binding protein 3; FABP7, fatty acid binding protein 7; FADD, Fas associated via death domain; FAS, Fas cell surface death receptor; FASL, Fas ligand; FDX1, ferredoxin 1; GNAQ/11, G protein subunit alpha q/11; GPX4, glutathione peroxidase 4; GSDMD, gasdermin D; GSH, glutathione; HDAC, histone deacetylase; HIF1, hypoxia inducible factor 1; HIF1A, hypoxia inducible factor 1 subunit alpha; HMGB1, high mobility group box 1; IL1B, interleukin 1 beta; IL17, interleukin 17; KRAS, KRAS proto-oncogene, GTPase; LOX, lysyl oxidase; LPCAT3, lysophosphatidylcholine acyltransferase 3; MAP1LC3, microtubule associated protein 1 light chain 3; MAP2K1, mitogen-activated protein kinase kinase 1; MAP2K2, mitogen-activated protein kinase kinase 2; MAPK, mitogen-activated protein kinases; MAPK14/p38, mitogen-activated protein kinase 14; MEMO1, mediator of cell motility 1; MT-CO1/COX1, mitochondrially encoded cytochrome c oxidase I; MT-CO2/COX2, mitochondrially encoded cytochrome c oxidase II; MTOR, mechanistic target of rapamycin kinase; MTs, metallothioneins; NAC, N-acetylcysteine; NFKB/NF-Κb, nuclear factor kappa B; NLRP3, NLR family pyrin domain containing 3; NPLOC4/NPL4, NPL4 homolog ubiquitin recognition factor; PDE3B, phosphodiesterase 3B; PDK1, phosphoinositide dependent protein kinase 1; PHD, prolyl-4-hydroxylase domain; PIK3C3/VPS34, phosphatidylinositol 3-kinase catalytic subunit type 3; PMAIP1/NOXA, phorbol-12-myristate-13-acetate-induced protein 1; POR, cytochrome P450 oxidoreductase; PUFA-PL, PUFA of phospholipids; PUFAs, polyunsaturated fatty acids; ROS, reactive oxygen species; SCO1, synthesis of cytochrome C oxidase 1; SCO2, synthesis of cytochrome C oxidase 2; SLC7A11, solute carrier family 7 member 11; SLC11A2/DMT1, solute carrier family 11 member 2; SLC31A1/CTR1, solute carrier family 31 member 1; SLC47A1, solute carrier family 47 member 1; SOD1, superoxide dismutase; SP1, Sp1 transcription factor; SQSTM1/p62, sequestosome 1; STEAP4, STEAP4 metalloreductase; TAX1BP1, Tax1 binding protein 1; TEPA, tetraethylenepentamine; TFEB, transcription factor EB; TM, tetrathiomolybdate; TP53/p53, tumor protein p53; TXNRD1, thioredoxin reductase 1; UCHL5, ubiquitin C-terminal hydrolase L5; ULK1, Unc-51 like autophagy activating kinase 1; ULK1, unc-51 like autophagy activating kinase 1; ULK2, unc-51 like autophagy activating kinase 2; USP14, ubiquitin specific peptidase 14; VEGF, vascular endothelial gro wth factor; XIAP, X-linked inhibitor of apoptosis.

Gelsevirine is a novel STING-specific inhibitor and mitigates STING-related inflammation in sepsis

Background

Stimulation of IFN genes (STING) is central to the production of interferon and proinflammatory cytokines in response to microbial DNA or self-DNA in the cytosol. The detrimental role of the activation of STING during sepsis has been well documented.

Methods

Here, we found that gelsevirine (GS) potently inhibit interferon and inflammatory cytokine induction in macrophages exposed to STING agonists (2'3'-cGAMP, IFN stimulatory DNA (ISD), and poly(dA:dT)). I n silico docking analysis and surface plasmon resonance binding study showed that GS bonds with high affinity to the cyclic dinucleotide (CDN)-binding pocket of STING. Biotin pull-down assay also confirmed that GS competitively bonded to STING protein. Furthermore, GS inhibited 2'3'-cGAMP-induced STING dimerization and subsequent activation. In addition, GS induced K48-linked STING ubiquitination and degradation, which was likely through upregulating and recruiting TRIM21. In mice exposed to cecal ligation and puncture (CLP)-induced sepsis, post-operative administration of GS significantly extended the survival period and mitigated acute organ damage.

Results

Overall, GS inhibited STING signaling by competitively binding to the CDN-binding pocket to lock STING in an inactive open conformation, while also promoting K48-linked STING ubiquitination and degradation.

Conclusions

Our findings identify a novel STING-specific inhibitor that could be applied in the treatment of sepsis.

Cytosolic LPS-induced caspase-11 oligomerization and activation is regulated by extended synaptotagmin 1

Caspase-11 (Casp-11) is known to induce pyroptosis and defends against cytosol-invading bacterial pathogens, but its regulation remains poorly defined. Here, we identified extended synaptotagmin 1 (E-Syt1), an endoplasmic reticulum protein, as a key regulator of Casp-11 oligomerization and activation. Macrophages lacking E-Syt1 exhibited reduced production of interleukin-1β (IL-1β) and impaired pyroptosis upon cytosolic lipopolysaccharide (LPS) delivery and cytosol-invasive bacterial infection. Moreover, cleavage of Casp-11 and its downstream substrate gasdermin D were significantly diminished in ESyt1-/- macrophages. Upon LPS stimulation, E-Syt1 underwent oligomerization and bound to the p30 domain of Casp-11 via its synaptotagmin-like mitochondrial lipid-binding protein (SMP) domain. E-Syt1 oligomerization and its interaction with Casp-11 facilitated Casp-11 oligomerization and activation. Notably, ESyt1-/- mice were susceptible to infection by cytosol-invading bacteria Burkholderia thailandensis while being resistant to LPS-induced endotoxemia. These findings collectively suggest that E-Syt1 may serve as a platform for Casp-11 oligomerization and activation upon cytosolic LPS sensing.

Regulation of cGAS and STING signaling during inflammation and infection

Stimulator of interferon genes (STING) is a sensor of cyclic dinucleotides including cyclic GMP-AMP, which is produced by cyclic GMP-AMP synthase (cGAS) in response to cytosolic DNA. The cGAS-STING signaling pathway regulates both innate and adaptive immune responses, as well as fundamental cellular functions such as autophagy, senescence, and apoptosis. Mutations leading to constitutive activation of STING cause devastating human diseases. Thus, the cGAS-STING pathway is of great interest because of its role in diverse cellular processes and because of the potential therapeutic implications of targeting cGAS and STING. Here, we review molecular and cellular mechanisms of STING signaling, and we propose a framework for understanding the immunological and other cellular functions of STING in the context of disease.

Extracellular SQSTM1 exacerbates acute pancreatitis by activating autophagy-dependent ferroptosis

ABBREVIATIONS

5-HETE, 5-hydroxyeicosatetraenoic acid; ACSL4, acyl-CoA synthetase long chain family member 4; AP, acute pancreatitis; ATG, autophagy related; AGER, advanced glycosylation end-product specific receptor; DAMPs, danger/damage-associated molecular patterns; FTH1, ferritin heavy chain 1; GPX4, glutathione peroxidase 4; IL, interleukin; INSR, insulin receptor; MAP1LC3B, microtubule associated protein 1 light chain 3 beta; MDA, malondialdehyde; MPO, myeloperoxidase; PRRs, pattern recognition receptors; PUFA, polyunsaturated fatty acid; RNAi, RNA interference; SQSTM1, sequestosome 1; TNF, tumor necrosis factor; TLR, toll like receptor.

Inflammasome genes polymorphisms are associated with progression to mechanical ventilation and death in a cohort of hospitalized COVID-19 patients in a reference hospital in Rio de Janeiro, Brazil

COVID-19 has a broad spectrum of clinical manifestations. We assessed the impact of single nucleotide polymorphisms (SNPs) of inflammasome genesas risk factors for progression toCOVID-19 critical outcomes, such as mechanical ventilation support (MVS) or death.The study included 451 hospitalized individuals followed up at the INI/FIOCRUZ, Rio de Janeiro, Brazil, from 06/2020 to 03/2021. SNPs genotyping was determined by Real-Time PCR. We analyzed risk factors for progression to MVS (n = 174[38.6 %]) or death (n = 175[38.8 %])as a result of COVID-19 by Cox proportional hazardmodels.Slower progression toMVSwas associated with allele G (aHR = 0.66;P = 0.005) or the genotype G/G (aHR = 0.391;P = 0.006) in the NLRP3 rs10754558 or the allele G (aHR = 0.309;P = 0.004) in the IL1βrs1143634, while C allele in the NLRP3 rs4612666 (aHR = 2.342;P = 0.006) or in the rs10754558 (aHR = 2.957;P = 0.005) were associated with faster progression to death. Slower progression to death was associated to allele G (aHR = 0.563;P = 0.006) or the genotype A/G (aHR = 0.537;P = 0.005) in the CARD8 rs6509365; the genotype A/C in the IFI16 rs1101996 (aHR = 0.569;P = 0.011); the genotype T/T (aHR = 0.394;P = 0.004) or allele T (aHR = 0.68;P = 0.006) in the NLRP3 rs4612666, and the genotype G/G (aHR = 0.326;P = 0.005) or allele G (aHR = 0,68;P = 0.014) in the NLRP3 rs10754558. Our results suggest that inflammasome genetic variations might influence the critical clinical course of COVID-19.

Gasdermins assemble; recent developments in bacteriology and pharmacology

The discovery of gasdermin D (GSDMD) as the terminal executioner of pyroptosis provided a large piece of the cell death puzzle, whilst simultaneously and firmly putting the gasdermin family into the limelight. In its purest form, GSDMD provides a connection between the innate alarm systems to an explosive, inflammatory form of cell death to jolt the local environment into immunological action. However, the gasdermin field has moved rapidly and significantly since the original seminal work and novel functions and mechanisms have been recently uncovered, particularly in response to infection. Gasdermins regulate and are regulated by mechanisms such as autophagy, metabolism and NETosis in fighting pathogen and protecting host. Importantly, activators and interactors of the other gasdermins, not just GSDMD, have been recently elucidated and have opened new avenues for gasdermin-based discovery. Key to this is the development of potent and specific tool molecules, so far a challenge for the field. Here we will cover some of these recently discovered areas in relation to bacterial infection before providing an overview of the pharmacological landscape and the challenges associated with targeting gasdermins.

STING activation in platelets aggravates septic thrombosis by enhancing platelet activation and granule secretion

Sepsis is a dysregulated inflammatory consequence of systemic infection. As a result, excessive platelet activation leads to thrombosis and coagulopathy, but we currently lack sufficient understanding of these processes. Here, using the cecal ligation and puncture (CLP) model of sepsis, we observed septic thrombosis and neutrophil extracellular trap formation (NETosis) within the mouse vasculature by intravital microscopy. STING activation in platelets was a critical driver of sepsis-induced pathology. Platelet-specific STING deficiency suppressed platelet activation and granule secretion, which alleviated sepsis-induced intravascular thrombosis and NETosis in mice. Mechanistically, sepsis-derived cGAMP promoted the binding of STING to STXBP2, the assembly of SNARE complex, granule secretion, and subsequent septic thrombosis, which probably depended on the palmitoylation of STING. We generated a peptide, C-ST5, to block STING binding to STXBP2. Septic mice treated with C-ST5 showed reduced thrombosis. Overall, platelet activation via STING reveals a potential strategy for limiting life-threatening sepsis-mediated coagulopathy.