Thrombomodulin-mediated Inhibition of Neutrophil Extracellular Trap Formation Alleviates Hepatic Ischemia/Reperfusion Injury by Blocking TLR4 in Rats Subjected to Liver Transplantation

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.

HSP110 aggravates ischemia-reperfusion injury after liver transplantation by promoting NF-κB pathway

BACKGROUND

Ischemia-reperfusion injury (IRI) poses a significant challenge to liver transplantation (LT). The underlying mechanism primarily involves overactivation of the immune system. Heat shock protein 110 (HSP110) functions as a molecular chaperone that helps stabilize protein structures.

METHODS

An IRI model was established by performing LT on Sprague-Dawley rats, and HSP110 was silenced using siRNA. Hematoxylin-eosin staining, TUNEL, immunohistochemistry, ELISA and liver enzyme analysis were performed to assess IRI following LT. Western blotting and quantitative reverse transcription-polymerase chain reaction were conducted to investigate the pertinent molecular changes.

RESULTS

Our findings revealed a significant increase in the expression of HSP110 at both the mRNA and protein levels in the rat liver following LT (P < 0.05). However, when rats were injected with siRNA-HSP110, IRI subsequent to LT was notably reduced (P < 0.05). Additionally, the levels of liver enzymes and inflammatory chemokines in rat serum were significantly reduced (P < 0.05). Silencing HSP110 with siRNA resulted in a marked decrease in M1-type polarization of Kupffer cells in the liver and downregulated the NF-κB pathway in the liver (P < 0.05).

CONCLUSIONS

HSP110 in the liver promotes IRI after LT in rats by activating the NF-κB pathway and inducing M1-type polarization of Kupffer cells. Targeting HSP110 to prevent IRI after LT may represent a promising new approach for the treatment of LT-associated IRI.

Salidroside ameliorates acute liver transplantation rejection in rats by inhibiting neutrophil extracellular trap formation

Acute rejection is an important factor affecting the survival of recipients after liver transplantation. Salidroside has various properties, including anti-inflammatory, antioxidant, and hepatoprotective properties. This study aims to investigate whether salidroside can prevent acute rejection after liver transplantation and to examine the underlying mechanisms involved. An in vivo acute rejection model is established in rats that are pretreated with tacrolimus (1 mg/kg/d) or salidroside (10 or 20 mg/kg/d) for seven days after liver transplantation. In addition, an in vitro experiment is performed using neutrophils incubated with salidroside (1, 10, 50 or 100 μM). Hematoxylin-eosin staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, immunosorbent assays, immunofluorescence analysis, Evans blue staining, and western blot analysis are performed to examine the impact of salidroside on NET formation and acute rejection in vitro and in vivo. We find that Salidroside treatment reduces pathological liver damage, serum aminotransferase level, and serum levels of IL-1β, IL-6, and TNF-α in vivo. The expressions of proteins associated with the HMGB1/TLR-4/MAPK signaling pathway (HMGB1, TLR-4, p-ERK1/2, p-JNK, p-P38, cleaved caspase-3, cleaved caspase-9, Bcl-2, Bax, IL-1β, TNF-α, and IL-6) are also decreased after salidroside treatment. In vitro experiments show that the release of HMGB1/TLR-4/MAPK signaling pathway-associated proteins from neutrophils treated with lipopolysaccharide is decreased by salidroside. Moreover, salidroside inhibits NETosis and protects against acute rejection by regulating the HMGB1/TLR-4/MAPK signaling pathway. Furthermore, salidroside combined with tacrolimus has a better effect than either of the other treatments alone. In summary, salidroside can prevent acute liver rejection after liver transplantation by reducing neutrophil extracellular trap development through the HMGB1/TLR-4/MAPK signaling pathway.

Role of the immune system in liver transplantation and its implications for therapeutic interventions

Liver transplantation (LT) stands as the gold standard for treating end-stage liver disease and hepatocellular carcinoma, yet postoperative complications continue to impact survival rates. The liver's unique immune system, governed by a microenvironment of diverse immune cells, is disrupted during processes like ischemia-reperfusion injury posttransplantation, leading to immune imbalance, inflammation, and subsequent complications. In the posttransplantation period, immune cells within the liver collaboratively foster a tolerant environment, crucial for immune tolerance and liver regeneration. While clinical trials exploring cell therapy for LT complications exist, a comprehensive summary is lacking. This review provides an insight into the intricacies of the liver's immune microenvironment, with a specific focus on macrophages and T cells as primary immune players. Delving into the immunological dynamics at different stages of LT, we explore the disruptions after LT and subsequent immune responses. Focusing on immune cell targeting for treating liver transplant complications, we provide a comprehensive summary of ongoing clinical trials in this domain, especially cell therapies. Furthermore, we offer innovative treatment strategies that leverage the opportunities and prospects identified in the therapeutic landscape. This review seeks to advance our understanding of LT immunology and steer the development of precise therapies for postoperative complications.

Updates on the Immune Cell Basis of Hepatic Ischemia-Reperfusion Injury

Liver ischemia-reperfusion injury (IRI) is the main cause of organ dysfunction and failure after liver surgeries including organ transplantation. The mechanism of liver IRI is complex and numerous signals are involved but cellular metabolic disturbances, oxidative stress, and inflammation are considered the major contributors to liver IRI. In addition, the activation of inflammatory signals exacerbates liver IRI by recruiting macrophages, dendritic cells, and neutrophils, and activating NK cells, NKT cells, and cytotoxic T cells. Technological advances enable us to understand the role of specific immune cells during liver IRI. Accordingly, therapeutic strategies to prevent or treat liver IRI have been proposed but no definitive and effective therapies exist yet. This review summarizes the current update on the immune cell functions and discusses therapeutic potentials in liver IRI. A better understanding of this complex and highly dynamic process may allow for the development of innovative therapeutic approaches and optimize patient outcomes.

New therapeutic concepts against ischemia-reperfusion injury in organ transplantation

INTRODUCTION

Ischemia-reperfusion injury (IRI) involves a positive amplification feedback loop that stimulates innate immune-driven tissue damage associated with organ procurement from deceased donors and during transplantation surgery. As our appreciation of its basic immune mechanisms has improved in recent years, translating putative biomarkers into therapeutic interventions in clinical transplantation remains challenging.

AREAS COVERED

This review presents advances in translational/clinical studies targeting immune responses to reactive oxygen species in IRI-stressed solid organ transplants, especially livers. Here we focus on novel concepts to rejuvenate suboptimal donor organs and improve transplant function using pharmacologic and machine perfusion (MP) strategies. Cellular damage induced by cold ischemia/warm reperfusion and the latest mechanistic insights into the microenvironment's role that leads to reperfusion-induced sterile inflammation is critically discussed.

EXPERT OPINION

Efforts to improve clinical outcomes and increase the donor organ pool will depend on improving donor management and our better appreciation of the complex mechanisms encompassing organ IRI that govern the innate-adaptive immune interface triggered in the peritransplant period and subsequent allo-Ag challenge. Computational techniques and deep machine learning incorporating the vast cellular and molecular mechanisms will predict which peri-transplant signals and immune interactions are essential for improving access to the long-term function of life-saving transplants.

The Novel MyD88 Inhibitor TJ-M2010-5 Protects Against Hepatic Ischemia-reperfusion Injury by Suppressing Pyroptosis in Mice

BACKGROUND

. With the development of medical technology and increased surgical experience, the number of patients receiving liver transplants has increased. However, restoration of liver function in patients is limited by the occurrence of hepatic ischemia-reperfusion injury (IRI). Previous studies have reported that the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling pathway and pyroptosis play critical roles in the development of hepatic IRI.

METHODS

. A mouse model of segmental (70%) warm hepatic IRI was established using BALB/c mice in vivo. The mechanism underlying inflammation in mouse models of hepatic IRI was explored in vitro using lipopolysaccharide- and ATP-treated bone marrow-derived macrophages. This in vitro inflammation model was used to simulate inflammation and pyroptosis in hepatic IRI.

RESULTS

. We found that a MyD88 inhibitor conferred protection against partial warm hepatic IRI in mouse models by downregulating the TLR4/MyD88 signaling pathway. Moreover, TJ-M2010-5 (a novel MyD88 inhibitor, hereafter named TJ-5) reduced hepatic macrophage depletion and pyroptosis induction by hepatic IRI. TJ-5 treatment inhibited pyroptosis in bone marrow-derived macrophages by reducing the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells, decreasing the release of high-mobility group box-1, and promoting endocytosis of lipopolysaccharide-high-mobility group box-1 complexes.

CONCLUSIONS

. Inhibition of MyD88 may protect the liver from partial warm hepatic IRI by reducing pyroptosis in hepatic innate immune cells. These results reveal the mechanism underlying the development of inflammation in partially warm hepatic IRI and the induction of cell pyroptosis.

Emerging Role of Neutrophil Extracellular Traps in Gastrointestinal Tumors: A Narrative Review

Neutrophil extracellular traps (NETs) are extracellular fibrous networks consisting of depolymerized chromatin DNA skeletons with a variety of antimicrobial proteins. They are secreted by activated neutrophils and play key roles in host defense and immune responses. Gastrointestinal (GI) malignancies are globally known for their high mortality and morbidity. Increasing research suggests that NETs contribute to the progression and metastasis of digestive tract tumors, among them gastric, colon, liver, and pancreatic cancers. This article explores the formation of NETs and reviews the role that NETs play in the gastrointestinal oncologic microenvironment, tumor proliferation and metastasis, tumor-related thrombosis, and surgical stress. At the same time, we analyze the qualitative and quantitative detection methods of NETs in recent years and found that NETs are specific markers of coronavirus disease 2019 (COVID-19). Then, we explore the possibility of NET inhibitors for the treatment of digestive tract tumor diseases to provide a new, efficient, and safe solution for the future therapy of gastrointestinal tumors.

Role of neutrophil extracellular traps in inflammatory evolution in severe acute pancreatitis

ABSTRACT

Severe acute pancreatitis (SAP) is a life-threatening acute abdominal disease with two peaks of death: the first in the early stage, characterized by systemic inflammatory response-associated organ failure; and the second in the late stage, characterized by infectious complications. Neutrophils are the main immune cells participating in the whole process of SAP. In addition to the traditional recognition of neutrophils as the origination of chemokine and cytokine cascades or phagocytosis and degranulation of pathogens, neutrophil extracellular traps (NETs) also play an important roles in inflammatory reactions. We reviewed the role of NETs in the occurrence and development of SAP and its fatal complications, including multiple organs injury, infected pancreatic necrosis, and thrombosis. This review provides novel insights into the involvement of NETs throughout the entire process of SAP, showing that targeting NETs might be a promising strategy in SAP treatment. However, precision therapeutic options targeting NETs in different situations require further investigation.

Updated Views on Neutrophil Responses in Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is an inevitable event during organ transplantation and represents a primary risk factor for the development of early graft dysfunction in lung, heart, liver, and kidney transplant recipients. Recent studies have implicated recipient neutrophils as key mediators of this process and also have found that early innate immune responses after transplantation can ultimately augment adaptive alloimmunity and affect late graft outcomes. Here, we discuss signaling pathways involved in neutrophil recruitment and activation after ischemia-mediated graft injury in solid organ transplantation with an emphasis on lung allografts, which have been the focus of recent studies. These findings suggest novel therapeutic interventions that target ischemia-reperfusion injury-mediated graft dysfunction in transplant recipients.

Neutrophil extracellular traps and complications of liver transplantation

Many end-stage liver disease etiologies are attributed to robust inflammatory cell recruitment. Neutrophils play an important role in inflammatory infiltration and neutrophil phagocytosis, oxidative burst, and degranulation. It has also been suggested that neutrophils may release neutrophil extracellular traps (NETs) to kill pathogens. It has been proven that neutrophil infiltration within the liver contributes to an inflammatory microenvironment and immune cell activation. Growing evidence implies that NETs are involved in the progression of numerous complications of liver transplantation, including ischemia-reperfusion injury, acute rejection, thrombosis, and hepatocellular carcinoma recurrence. NETs are discussed in this comprehensive review, focusing on their effects on liver transplantation complications. Furthermore, we discuss NETs as potential targets for liver transplantation therapy.

The role of extracellular traps in ischemia reperfusion injury

In response to strong signals, several types of immune cells release extracellular traps (ETs), which are web-like structures consisting of DNA decorated with various protein substances. This process is most commonly observed in neutrophils. Over the past two decades, ET formation has been recognized as a unique mechanism of host defense and pathogen destruction. However, the role of ETs in sterile inflammation has only been studied extensively in recent years. Ischemia reperfusion injury (IRI) is a type of sterile inflammatory injury. Several studies have reported that ETs have an important role in IRI in various organs. In this review, we describe the release of ETs by various types of immune cells and focus on the mechanism underlying the formation of neutrophil ETs (NETs). In addition, we summarize the role of ETs in IRI in different organs and their effects on tumors. Finally, we discuss the value of ETs as a potential therapeutic target for organ IRI and present possible challenges in conducting studies on IRI-related ETs as well as future research directions and prospects.

The Role of Neutrophils as a Driver in Hepatic Ischemia-Reperfusion Injury and Cancer Growth

The innate immune system plays an essential role in the response to sterile inflammation and its association with liver ischemia and reperfusion injury (IRI). Liver IRI often manifests during times of surgical stress such as cancer surgery or liver transplantation. Following the initiation of liver IRI, stressed hepatocytes release damage-associated molecular patterns (DAMPs) which promote the infiltration of innate immune cells which then initiate an inflammatory cascade and cytokine storm. Upon reperfusion, neutrophils are among the first cells that infiltrate the liver. Within the liver, neutrophils play an important role in fueling tissue damage and tumor progression by promoting the metastatic cascade through the formation of Neutrophil Extracellular Traps (NETs). NETs are composed of web-like DNA structures containing proteins that are released in response to inflammatory stimuli in the environment. Additionally, NETs can aid in mediating liver IRI, promoting tumor progression, and most recently, in mediating early graft rejection in liver transplantation. In this review we aim to summarize the current knowledge of innate immune cells, with a focus on neutrophils, and their role in mediating IRI in mouse and human diseases, including cancer and transplantation. Moreover, we will investigate the interaction of Neutrophils with varying subtypes of other cells. Furthermore, we will discuss the role and different treatment modalities in targeting Neutrophils and NETs to prevent IRI.