Gene Silencing of NALP3 Protects Against Liver Ischemia–Reperfusion Injury in Mice

Liver ischemia reperfusion injury: Mechanisms, cellular pathways, and therapeutic approaches

Liver ischemia-reperfusion injury (LIRI) is a critical challenge in liver transplantation, resection, and trauma surgeries, leading to significant hepatic damage due to oxidative stress, inflammation, and mitochondrial dysfunction. This review explores the cellular and molecular mechanisms underlying LIRI, focusing on ATP depletion, mitochondrial dysfunction, and the involvement of reactive oxygen species (ROS). Inflammatory pathways, including the activation of nuclear factor-kappa B (NF-κB) and the NLRP3 inflammasome, as well as pro-inflammatory cytokines such as TNF-α and IL-1β, play a crucial role in exacerbating tissue damage. Various types of cell death, including necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis and cuproptosis are also discussed. Therapeutic interventions targeting these mechanisms, such as antioxidants, anti-inflammatories, mitochondrial protectors, and signaling modulators, have shown promise in pre-clinical studies. However, translating these findings into clinical practice faces challenges due to the limitations of animal models and the complexity of human responses. Emerging therapies, such as RNA-based treatments, genetic editing, and stem cell therapies, offer potential breakthroughs in LIRI management. This review highlights the need for further research and the development of innovative therapeutic approaches to improve clinical outcomes.

BCL6 Alleviates Hepatic Ischemia/Reperfusion Injury Via Recruiting SIRT1 to Repress the NF-κB/NLRP3 Pathway

BACKGROUND

Hepatic ischemia/reperfusion (I/R) injury (HIRI) is an intrinsic phenomenon observed in the process of various liver surgeries. Unfortunately, there are currently few options available to prevent HIRI. Accordingly, we aim to explore the role and key downstream effects of B-cell lymphoma 6 (BCL6) in hepatic I/R (HIR).

METHODS

BCL6 expression levels were measured in I/R liver tissue and primary hepatocytes stimulated by hypoxia/reoxygenation (H/R). Moreover, we ascertained the BCL6 effect on HIR in vivo using liver-specific BCL6 knockout mice and adenovirus-BCL6-infected mice. RNA-sequencing, luciferase, chromatin immunoprecipitation, and interactome analysis were combined to identify the direct target and corresponding molecular events contributing to BCL6 function. DNA pull-down was applied to identify upstream of BCL6 in the H/R challenge.

RESULTS

HIR represses BCL6 expression in vivo and in vitro. Hepatic BCL6 overexpression attenuates inflammation and apoptosis after I/R injury, whereas BCL6 deficiency aggravates I/R-induced liver injury. RNA-sequencing showed that BCL6 modulated nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 inflammasome signaling in HIRI. Mechanistically, BCL6 deacetylated nuclear factor kappa-B p65 lysine 310 by recruiting sirtuin 1 (SIRT1), thereby inhibiting the nuclear factor kappa-B/nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 pathway. Moreover, overexpression of SIRT1 blocked the detrimental effects of BCL6 depletion. Moreover, EX 527, a SIRT1 inhibitor, vanished protection from BCL6 overexpression. Furthermore, transcription factor 7 was found to mediate the transcription regulation of BCL6 on H/R challenge.

CONCLUSIONS

Our results provide the first evidence supporting BCL6 as an important protective agent of HIR. This suggests a potential therapeutic approach for HIR.

Intracerebroventricular infusion of secretoneurin inhibits neuronal NLRP3-Apoptosis pathway and preserves learning and memory after cerebral ischemia

Transient global cerebral ischemia (GCI) results in delayed neuronal death, primarily apoptosis, in the hippocampal CA1 subregion, which leads to severe cognitive deficits. While therapeutic hypothermia is an approved treatment for patients following cardiac arrest, it is associated with various adverse effects. Secretoneurin (SN) is an evolutionarily conserved neuropeptide generated in the brain, adrenal medulla and other endocrine tissues. In this study, SN was infused into the rat brain by intracerebroventricular injection 1 day after GCI, and we demonstrated that SN could significantly preserve spatial learning and memory in the Barnes maze tasks examined on days 14-17 after GCI. To further investigate underlying pathways involved, we demonstrated that, on day 5 after GCI, SN could significantly inhibit GCI-induced expression levels of Apoptosis Inducing Factor (AIF) and cleaved-PARP1, as well as neuronal apoptosis and synaptic loss in the hippocampal CA1 region. Additionally, SN could attenuate GCI-induced activation of both caspase-1 and caspase-3, and the levels of pro-inflammatory cytokines IL-1β and IL-18 in the CA1 region. Mechanically, we observed that treatment with SN effectively inhibited NLRP3 protein elevation and the bindings of NLRP3-ASC and ASC-caspase-1 in hippocampal neurons after GCI. In summary, our data indicate that SN could effectively attenuate NLRP3 inflammasome formation, as well as the activation of caspase-1 and -3, the production of pro-inflammatory cytokines, and ultimately the neuronal apoptotic loss induced by GCI. Potential neuronal pyroptosis, or caspase-1-dependent cell death, could also be involved in ischemic neuronal death, which needs further investigation.

Programmed cell death, from liver Ischemia-Reperfusion injury perspective: An overview

Liver ischemia-reperfusion injury (LIRI) commonly occurs in liver resection, liver transplantation, shock, and other hemorrhagic conditions, resulting in profound local and systemic effects via associated inflammatory responses and hepatic cell death. Hepatocyte death is a significant component of LIRI and its mechanism was previously thought to be limited to apoptosis and necrosis. With the discovery of novel types of programmed cell death (PCD), necroptosis, ferroptosis, pyroptosis, autophagy, NETosis, and parthanatos have been shown to be involved in LIRI. Understanding the mechanisms underlying cell death following LIRI is indispensable to mitigating the widespread effects of LIRI. Here, we review the roles of different PCD and discuss potential therapy in LIRI.

Effect of an Airbag-selective Portal Vein Blood Arrester on the Liver after Hepatectomy: A New Technique for Selective Clamping of the Portal Vein

OBJECTIVE

A novel technique was explored using an airbag-selective portal vein blood arrester that circumvents the need for an intraoperative assessment of anatomical variations in patients with complex intrahepatic space-occupying lesions.

METHODS

Rabbits undergoing hepatectomy were randomly assigned to 4 groups: intermittent portal triad clamping (PTC), intermittent portal vein clamping (PVC), intermittent portal vein blocker with an airbag-selective portal vein blood arrester (APC), and without portal blood occlusion (control). Hepatic ischemia and reperfusion injury were assessed by measuring the 7-day survival rate, blood loss, liver function, hepatic pathology, hepatic inflammatory cytokine infiltration, hepatic malondialdehyde levels, and proliferating cell nuclear antigen levels.

RESULTS

Liver damage was substantially reduced in the APC and PVC groups. The APC animals exhibited transaminase levels similar to or less oxidative stress damage and inflammatory hepatocellular injury compared to those exhibited by the PVC animals. Bleeding was significantly higher in the control group than in the other groups. The APC group had less bleeding than the PVC group because of the avoidance of portal vein skeletonization during hepatectomy. Thus, more operative time was saved in the APC group than in the PVC group. Moreover, the total 7-day survival rate in the APC group was higher than that in the PTC group.

CONCLUSION

Airbag-selective portal vein blood arresters may help protect against hepatic ischemia and reperfusion injury in rabbits undergoing partial hepatectomy. This technique may also help prevent liver damage in patients requiring hepatectomy.

Arachidonic acid activates NLRP3 inflammasome in MDSCs via FATP2 to promote post-transplant tumour recurrence in steatotic liver grafts

Background & Aims

The steatotic grafts have been applied in liver transplantation frequently owing to the high incidence of non-alcoholic fatty liver disease. However, fatty livers are vulnerable to graft injury. Myeloid-derived suppressor cell (MDSC) recruitment during liver graft injury promotes tumour recurrence. Lipid metabolism exerts the immunological influence on MDSCs in tumour progression. Here, we aimed to explore the role and mechanism of inflammasome activation in MDSCs induced by lipid metabolism during fatty liver graft injury and the subsequent effects on tumour recurrence.

Methods

MDSC populations and nucleotide-binding oligomerisation domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome levels were investigated in a clinical cohort and a rat liver transplantation model. The mechanism of NLRP3 activation by specific fatty acids was explored in mouse hepatic ischaemia/reperfusion injury (IRI) with tumour recurrence model and in vitro studies.

Results

MDSC populations and NLRP3 levels were increased with higher tumour recurrent rate in patients using steatotic grafts. NLRP3 was upregulated in MDSCs with lipid accumulation post mouse fatty liver IRI. Mechanistically, arachidonic acid was discovered to activate NLRP3 inflammasome in MDSCs through fatty acid transport protein 2 (FATP2), which was identified by screening lipid uptake receptors. The mitochondrial dysfunction with enhanced reactive oxygen species bridged arachidonic acid uptake and NLRP3 activation in MDSCs, which subsequently stimulated CD4+ T cells producing more IL-17 in fatty liver IRI. Blockade of FATP2 inhibited NLRP3 activation in MDSCs, IL-17 production in CD4+ T cells, and the tumour recurrence post fatty liver IRI.

Conclusions

During fatty liver graft injury, arachidonic acid activated NLRP3 inflammasome in MDSCs through FATP2, which subsequently stimulated CD4+ T cells producing IL-17 to promote tumour recurrence post transplantation.

Impact and implications

The high incidence of non-alcoholic fatty liver disease resulted in the frequent application of steatotic donors in liver transplantation. Our data showed that the patients who underwent liver transplantation using fatty grafts experienced higher tumour recurrence. We found that arachidonic acid activated NLRP3 inflammasome in MDSCs through FATP2 during fatty liver graft injury, which led to more IL-17 secretion of CD4+ T cells and promoted tumour recurrence post transplantation. The inflammasome activation by aberrant fatty acid metabolism in MDSCs bridged the acute-phase fatty liver graft injury and liver tumour recurrence.

Ghrelin protects against ischemia/reperfusion-induced hepatic injury via inhibiting Caspase-11-mediated noncanonical pyroptosis

BACKGROUND

Ischemia/reperfusion (I/R) injury is a complication of liver transplantation. I/R-induced inflammatory cell death, namely, pyroptosis, that is triggered by overactive inflammasomes results in the production of proinflammatory cytokines. Hepatic I/R injury correlates with the activation of the Caspase-11-mediated pyroptosis pathway. We investigated whether ghrelin, which is a pleiotropic gut hormone, may have anti-hepatic I/R injury effects, but the mechanism by which Ghrelin ameliorates hepatic I/R -induced injury remains a mystery.

METHODS

Hepatic I/R injury was induced in a mouse model by clamping the left and right lobes of the liver for 90 min followed by reperfusion for 6 h, 12 h, or 24 h. As treatment, a saline with or without ghrelin was infused via the tail vain. Hepatocytes were isolated using a two-step collagenase liver perfusion method.

RESULTS

In our study, treatment with ghrelin protected against hepatic I/R injury as shown by decreased alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels (p < 0.001) and reduced the histological injury in liver tissues compared with untreated controls. The LDH level of primary hepatocytes was increased by hypoxia/reoxygenation (H/R), and it was then restored to normal levels by ghrelin-treatment (p < 0.05). Western blotting analysis showed that ghrelin significantly inhibited the expression of pyroptosis-related proteins, including Caspase-11, GSDMD-N, NLRP3 and HMGB1, both in vivo and in vitro (all p < 0.05) compared with the untreated controls. Immunofluorescence showed that the expression of Gasdamin D (GSDMD) in hepatocytes was increased after I/R or H/R, whereas GSDMD expression was reduced by ghrelin treatment (p < 0.05).

CONCLUSIONS

Our findings suggest that ghrelin ameliorated I/R-induced hepatic injury by inhibiting Caspase-11-mediated pyroptosis. Ghrelin may be a potential therapeutic option to prevent hepatic I/R injury after liver transplantation.

Protective role of thymoquinone in hyperlipidemia-induced liver injury in LDL-R-/-mice

BACKGROUND

Hyperlipidemia, a heterogeneous group of disorders characterized by elevated plasma lipids in the blood, causes severe health problems, leading to fatty liver disease and nonalcoholic fatty liver disease. Thymoquinone, the major active chemical component of Nigella sativa, reportedly exerts a vast array of biological effects. Various studies have reported that Thymoquinone protects against liver injury.

AIMS

The aim of this study was to investigate the possible protective effects of Thymoquinone against liver injury in hyperlipidemia-induced LDL-R-/- mice.

METHODS

Eight-week-old male LDL-R-/- mice were randomly divided into three groups: a control group fed a normal diet and two groups fed a high-cholesterol diet or high-cholesterol diet mixed with Thymoquinone. All groups were fed different diets for 8 weeks. Blood samples were obtained from the inferior vena cava and collected in serum tubes. The samples were then stored at - 80 °C until used. Longitudinal sections of liver tissues were fixed in 10% formalin and then embedded in paraffin for histological evaluation. The remainder of the liver tissues were snap-frozen in liquid nitrogen for reverse transcription-polymerase chain reaction or western blotting.

RESULTS

Our results demonstrated that Thymoquinone administration significantly reduced liver histological alterations by hyperlipidemia. Thymoquinone mitigated hyperlipidemia-induced liver injury as indicated by the suppression of metabolic characteristics, liver biochemical parameters, pyroptosis indicators, a macrophage marker, and the phosphatidylinositide 3-kinase signaling pathway.

CONCLUSIONS

Thymoquinone is a potential therapeutic agent for hyperlipidemia-induced liver injury.

Autophagy in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) is a major complication of liver resection or liver transplantation that can seriously affect patient's prognosis. There is currently no definitive and effective treatment strategy for HIRI. Autophagy is an intracellular self-digestion pathway initiated to remove damaged organelles and proteins, which maintains cell survival, differentiation, and homeostasis. Recent studies have shown that autophagy is involved in the regulation of HIRI. Numerous drugs and treatments can change the outcome of HIRI by controlling the pathways of autophagy. This review mainly discusses the occurrence and development of autophagy, the selection of experimental models for HIRI, and the specific regulatory pathways of autophagy in HIRI. Autophagy has considerable potential in the treatment of HIRI.

Hypoxia inducible factor 1α promotes interleukin-1 receptor antagonist expression during hepatic ischemia-reperfusion injury

BACKGROUND

Ischemia-reperfusion injury (IRI) is a major risk associated with liver surgery and transplantation, and its pathological mechanism is complex. Interleukin-1 receptor antagonist (IL-1ra) can protect the liver from IRI. However, the regulatory mechanism of IL-1ra expression is still unclear.

AIM

To identify the mechanism that could protect the liver in the early stage of IRI.

METHODS

To screen the key genes in hepatic IRI, we performed RNA sequencing and gene enrichment analysis on liver tissue from mice with hepatic IRI. Subsequently, we verified the expression and effect of IL-1ra in hepatic IRI. We also used promoter mutagenesis and chromatin immunoprecipitation assay to search for the transcriptional regulatory sites of hypoxia-inducible factor (HIF)-1α. Finally, to explore the protective mechanism of ischemic preconditioning (IP), we examined the expression of HIF-1α and IL-1ra after IP.

RESULTS

We identified IL-1ra as a key regulator in hepatic IRI. The expression of IL-1ra was significantly upregulated after hepatic IRI both in vivo and in vitro. Furthermore, we found that HIF-1α regulated Il-1ra transcription in response to hypoxia. Increased HIF-1α accumulation promoted IL-1ra expression, whereas inhibition of HIF-1α exhibited the opposite effect. We also confirmed a predominant role for hypoxia response element in the regulation of Il1ra transcription by HIF-1α activation. Of note, we demonstrated that IP protects against hepatic IRI by inducing IL-1ra expression, which is mediated through HIF-1α.

CONCLUSION

We demonstrated that ischemia or hypoxia leads to increased expression of IL-1ra through HIF-1α. Importantly, IP protects the liver from IRI via the HIF-1α–IL-1ra pathway.

Ameliorative Effect of D-Carvone against Hepatic Ischemia-Reperfusion-Induced Injury in Rats

BACKGROUND

D-carvone is a monoterpene that exists in the essential oils of several plant species. Hepatic ischemia-reperfusion (Hep I/R) takes place clinically during different scenarios of liver pathologies. The aim of the current investigation is to disclose the hepato-protective actions of carvone against Hep I/R-induced damage and to reveal the underlying mechanism.

MATERIAL AND METHODS

Rats were assigned into five groups: sham and carvone plus sham groups, in which rats were administered either saline or carvone orally for three weeks prior to the induction of Hep I/R. In the Hep I/R group, rats were administered saline orally prior to the Hep I/R induction operation. The carvone 25 plus Hep I/R and Carvone 50 plus Hep I/R groups were administered carvone (25 and 50 mg/kg, respectively) for three weeks, followed by the induction of Hep I/R.

RESULTS

Liver ischemic animals demonstrated impaired liver function, several histopathological variations, and reduced levels of antioxidant enzyme activities. Furthermore, the Hep I/R groups showed the elevated gene expression of high-mobility group box 1 (HMGB1), toll-like receptors 4 (TLR4), nuclear factor kappa B (NFκB), and LR family pyrin domain containing 3 (NLP3), with subsequent escalated adhesion molecule 1 (ICAM-1), neutrophil infiltration, and several inflammatory mediators, including interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α), as well as apoptotic markers. Pretreatment with D-carvone alleviated ischemia/reperfusion-induced impaired liver function, diminished the histopathological deviations, and augmented the antioxidant enzymes. In addition, D-carvone mitigated the gene expression of HMGB1, TLR4, NFκB, and NLP3, with a subsequent reduction in ICAM-1, neutrophils infiltration, inflammatory mediators, and apoptotic markers.

CONCLUSION

Rats pretreated with D-carvone exhibited hepato-protective actions against Hep I/R-induced damage via the downregulation of HMGB1, TLR4, NFκB, NLP3, associated inflammatory mediators, and apoptotic markers.

The Role of NLRP3 Inflammasome Activation Pathway of Hepatic Macrophages in Liver Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) is considered an inherent component involved in liver transplantation, which induce early organ dysfunction and failure. And the accumulating evidences indicate that the activation of host innate immune system, especially hepatic macrophages, play a pivotal role in the progression of LIRI. Inflammasomes is a kind of intracellular multimolecular complexes that actively participate in the innate immune responses and proinflammatory signaling pathways. Among them, NLRP3 inflammasome is the best characterized and correspond to regulate caspase-1 activation and the secretion of proinflammatory cytokines in response to various pathogen-derived as well as danger-associated signals. Additionally, NLRP3 is highly expressed in hepatic macrophages, and the assembly of NLRP3 inflammasome could lead to LIRI, which makes it a promising therapeutic target. However, detailed mechanisms about NLRP3 inflammasome involving in the hepatic macrophages-related LIRI is rarely summarized. Here, we review the potential role of the NLRP3 inflammasome pathway of hepatic macrophages in LIRI, with highlights on currently available therapeutic options.

Transcriptional changes in orthotopic liver transplantation and ischemia/reperfusion injury

Background There are few effective targeting strategies to reduce liver ischemia-reperfusion injury (IRI), which is one of the reasons for the poor prognosis of liver transplant recipients. Methods A systematic approach combining gene expression with protein interaction (PPI) network was used to screen the characteristic genes and related biological functions of post-transplant. Differentially expressed genes (DEGs) between IRI+ and IRI- were identified. Logistic regression model and receiver operating characteristic (ROC) curve were used to identify potential target genes of IRI. The expression of key genes was verified by qRT-PCR and Western-blot experiments. Finally, the ssGSEA was used to identify the immune cell infiltration in patients with IRI. Results The 283 common DEGs in GSE87487 and GSE151648 were mainly related to apoptosis and IL-17 signaling pathway. Through PPI network and logistic regression analysis, we identified that IL6, CCL2 and CXCL8 may be involved in the ischemia/reperfusion (IR) process. In addition, 32 genes were showed associated with IRI through inflammatory and metabolic pathways. Among the key genes identified, the differential expression of AGBL4, CILP2 and IL4I1 was verified by molecular experiments. Th17 cells of differentially infiltrated immune cells were positively correlated with CILP2 and IL4I1. The difference of Th17 cells between IRI+ and IRI- was verified by flow cytometry. Conclusion The study showed that AGBL4, CILP2 and IL4I1 were associated with IRI. Th17 cells may be associated with the regulation of IRI by key genes. These genes and related pathways may be targets for improving IRI.

Delivering siRNA Compounds During HOPE to Modulate Organ Function: A Proof-of-Concept Study in a Rat Liver Transplant Model

BACKGROUND

Apoptosis contributes to the severity of ischemia-reperfusion injury (IRI), limiting the use of extended criteria donors in liver transplantation (LT). Machine perfusion has been proposed as a platform to administer specific therapies to improve graft function. Alternatively, the inhibition of genes associated with apoptosis during machine perfusion could alleviate IRI post-LT. The aim of the study was to investigate whether inhibition of an apoptosis-associated gene (FAS) using a small interfering RNA (siRNA) approach could alleviate IRI in a rat LT model.

METHODS

In 2 different experimental protocols, FASsiRNA (500 µg) was administered to rat donors 2 h before organ procurement, followed by 22 h of static cold storage, (SCS) or was added to the perfusate during 1 h of ex situ hypothermic oxygenated perfusion (HOPE) to livers previously preserved for 4 h in SCS.

RESULTS

Transaminase levels were significantly lower in the SCS-FASsiRNA group at 24 h post-LT. Proinflammatory cytokines (interleukin-2, C-X-C motif chemokine 10, tumor necrosis factor alpha, and interferon gamma) were significantly decreased in the SCS-FASsiRNA group, whereas the interleukin-10 anti-inflammatory cytokine was significantly increased in the HOPE-FASsiRNA group. Liver absorption of FASsiRNA after HOPE session was demonstrated by confocal microscopy; however, no statistically significant differences on the apoptotic index, necrosis levels, and FAS protein transcription between treated and untreated groups were observed.

CONCLUSIONS

FAS inhibition through siRNA therapy decreases the severity of IRI after LT in a SCS protocol; however the association of siRNA therapy with a HOPE perfusion model is very challenging. Future studies using better designed siRNA compounds and appropriate doses are required to prove the siRNA therapy effectiveness during liver HOPE liver perfusion.

The mechanism of HMGB1 secretion and release

High mobility group box 1 (HMGB1) is a nonhistone nuclear protein that has multiple functions according to its subcellular location. In the nucleus, HMGB1 is a DNA chaperone that maintains the structure and function of chromosomes. In the cytoplasm, HMGB1 can promote autophagy by binding to BECN1 protein. After its active secretion or passive release, extracellular HMGB1 usually acts as a damage-associated molecular pattern (DAMP) molecule, regulating inflammation and immune responses through different receptors or direct uptake. The secretion and release of HMGB1 is fine-tuned by a variety of factors, including its posttranslational modification (e.g., acetylation, ADP-ribosylation, phosphorylation, and methylation) and the molecular machinery of cell death (e.g., apoptosis, pyroptosis, necroptosis, alkaliptosis, and ferroptosis). In this minireview, we introduce the basic structure and function of HMGB1 and focus on the regulatory mechanism of HMGB1 secretion and release. Understanding these topics may help us develop new HMGB1-targeted drugs for various conditions, especially inflammatory diseases and tissue damage.

A nuclear protein that gets released after cell death or is actively secreted by immune cells offers a promising therapeutic target for treating diseases linked to excessive inflammation. Daolin Tang from the University of Texas Southwestern Medical Center in Dallas, USA, and colleagues review how cellular stresses can trigger the accumulation of HMGB1, a type of alarm signal protein that promotes the recruitment and activation of inflammation-promoting immune cells. The researchers discuss various mechanisms that drive both passive and active release of HMGB1 into the space around cells. These processes, which include enzymatic modifications of the HMGB1 protein, cell–cell interactions and molecular pathways of cell death, could be targeted by drugs to lessen tissue damage and inflammatory disease caused by HMGB1-induced immune responses

The ER stress sensor inositol-requiring enzyme 1α in Kupffer cells promotes hepatic ischemia-reperfusion injury

Hepatic ischemia/reperfusion (I/R) injury is an inflammation-mediated process arising from ischemia/reperfusion-elicited stress in multiple cell types, causing liver damage during surgical procedures and often resulting in liver failure. Endoplasmic reticulum (ER) stress triggers the activation of the unfolded protein response (UPR) and is implicated in tissue injuries, including hepatic I/R injury. However, the cellular mechanism that links the UPR signaling to local inflammatory responses during hepatic I/R injury remains largely obscure. Here, we report that IRE1α, a critical ER-resident transmembrane signal transducer of the UPR, plays an important role in promoting Kupffer-cell-mediated liver inflammation and hepatic I/R injury. Utilizing a mouse model in which IRE1α is specifically ablated in myeloid cells, we found that abrogation of IRE1α markedly attenuated necrosis and cell death in the liver, accompanied by reduced neutrophil infiltration and liver inflammation following hepatic I/R injury. Mechanistic investigations in mice as well as in primary Kupffer cells revealed that loss of IRE1α in Kupffer cells not only blunted the activation of the NLRP3 inflammasome and IL-1β production, but also suppressed the expression of the inducible nitric oxide synthase (iNos) and proinflammatory cytokines. Moreover, pharmacological inhibition of IRE1α′s RNase activity was able to attenuate inflammasome activation and iNos expression in Kupffer cells, leading to alleviation of hepatic I/R injury. Collectively, these results demonstrate that Kupffer cell IRE1α mediates local inflammatory damage during hepatic I/R injury. Our findings suggest that IRE1α RNase activity may serve as a promising target for therapeutic treatment of ischemia/reperfusion-associated liver inflammation and dysfunction.

Dexmedetomidine alleviates hepatic ischaemia-reperfusion injury via the PI3K/AKT/Nrf2-NLRP3 pathway

Hepatic ischaemia-reperfusion (I/R) injury constitutes a tough difficulty in liver surgery. Dexmedetomidine (Dex) plays a protective role in I/R injury. This study investigated protective mechanism of Dex in hepatic I/R injury. The human hepatocyte line L02 received hypoxia/reoxygenation (H/R) treatment to stimulate cell model of hepatic I/R. The levels of pyroptosis proteins and inflammatory factors were detected. Functional rescue experiments were performed to confirm the effects of miR-494 and JUND on hepatic I/R injury. The levels of JUND, PI3K/p-PI3K, AKT/p-AKT, Nrf2, and NLRP3 activation were detected. The rat model of hepatic I/R injury was established to confirm the effect of Dex in vivo. Dex reduced pyroptosis and inflammation in H/R cells. Dex increased miR-494 expression, and miR-494 targeted JUND. miR-494 inhibition or JUND upregulation reversed the protective effect of Dex. Dex repressed NLRP3 inflammasome by activating the PI3K/AKT/Nrf2 pathway. In vivo experiments confirmed the protective effect of Dex on hepatic I/R injury. Overall, Dex repressed NLRP3 inflammasome and alleviated hepatic I/R injury via the miR-494/JUND/PI3K/AKT/Nrf2 axis.

N-acetyl-L-tryptophan attenuates hepatic ischemia-reperfusion injury via regulating TLR4/NLRP3 signaling pathway in rats

The aim of this study was to investigate the changes of TLR4/NLRP3 signal during hepatic ischemia-reperfusion injury (HIRI) and to verify whether N-acetyl-L-tryptophan (L-NAT) protected hepatocytes by regulating the activation of TLR4/NLRP3 signal. We have established the rat HIRI model and H₂O₂-induced cell damage model to simulate ischemia-reperfusion injury and detect the corresponding indicators. Compared with the sham group, Suzuki score and the level of serum ALT increased after HIRI, accompanied by an increased expression of NLRP3, ASC, Caspase-1, IL-1β, TLR4, and NF-κB. While L-NAT pretreatment reversed the above-mentioned changes. Compared with the control group, cells in the H₂O₂ treated group became smaller in cell volume and round in shape with unclear boundaries. Similar to the phenotypes in vivo, H₂O₂ treatment also induced significant increase in expression of pyroptosis-related proteins (NLRP3, ASC, Caspase-1 and IL-1β) and inflammatory factors (TLR4 and NF-κB). While L-NAT pretreatment attenuated injuries caused by H₂O₂. In conclusion, the present findings demonstrate that L-NAT alleviates HIRI by regulating activation of NLRP3 inflammasome, which may be related to the TLR4/NF-κB signaling pathway.

Beneficial effects of natural compounds on experimental liver ischemia-reperfusion injury

Liver ischemia-reperfusion injury (IRI) is a phenomenon inherent to hepatic surgery that severely compromises the organ functionality, whose underlying mechanisms involve cellular and molecular interrelated processes leading to the development of an excessive inflammatory response. Liver resident cells and those recruited in response to injury generate pro-inflammatory signals such as reactive oxygen species, cytokines, chemokines, proteases and lipid mediators that contribute to hepatocellular necrosis and apoptosis. Besides, dying hepatocytes release damage-associated molecular patterns that actívate inflammasomes to further stimulate inflammatory responses leading to massive cell death. Since liver IRI is a complication of hepatic surgery in man, extensive preclinical studies have assessed potential protective strategies, including the supplementation with natural compounds, with the objective to downregulate nuclear factor-κB functioning, the main effector of inflammatory responses. This can be accomplished by either the activation of peroxisome proliferator-activated receptor-α, G protein-coupled receptor 120 or antioxidant signaling pathways, the synthesis of specific pro-resolving mediators, downregulation of Toll-like receptor 4 activity or additional contributory mechanisms that are beginning to be understood. The latter aspect is a crucial issue to be accomplished in preclinical studies, in order to establish adequate conditions for the supplementation with natural products before major liver surgeries in man involving warm IR, such as hepatic trauma or resection of large intrahepatic tumors.

Inhibition of oxidative stress and NLRP3 inflammasome by Saikosaponin-d alleviates acute liver injury in carbon tetrachloride-induced hepatitis in mice

NLRP3 inflammasome activation results in severe liver inflammation and injury. Saikosaponin-d (SSd) possesses anti-inflammatory and hepatoprotective effects. This study aimed to determine the protective effects of SSd on carbon tetrachloride (CCl₄)-induced acute liver injury in mice, and whether oxidative stress and NLRP3 inflammasome activation participate in the process.

The CCl₄ mice model and controls were induced. The mice were treated with SSd at 1, 1.5, or 2.0 mg/kg in a total volume of 100 µl/25 g of body weight. Liver injury was assessed by histopathology. Oxidative stress was determined using mitochondrial superoxide production (MSP), malondialdehyde (MDA) content, and superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities. NLRP3, ASC, and Caspase 1 were determined by real-time PCR and western blot. IL-1β and IL-18 levels were determined by ELISA.

Significantly elevated oxidative stress was induced in the liver by CCl₄, as demonstrated by histopathology and increases of MDA and MSP levels and decreases of SOD, GPx, and CAT activities (all P < 0.01). SSd significantly decreased the MDA and MSP levels and increased the activities of SOD, GPx, and CAT (all P < 0.05). The mRNA expression of NLRP3, ASC, and Caspase 1, and the protein expression of Caspase 1-p10, NLRP3, ASC, IL-1β, and IL-18 were significantly increased after CCl₄ induction (all P < 0.01). These changes were reversed by SSd (all P < 0.05).

Suppression of the oxidative stress and NLRP3 inflammasome activation were involved in SSd-alleviated acute liver injury in CCl₄-induced hepatitis.

Ischemia reperfusion injury induces pyroptosis and mediates injury in steatotic liver thorough Caspase 1 activation

A steatotic liver is increasingly vulnerable to ischemia reperfusion injury (IRI), and the underlying mechanisms are incompletely defined. Caspases are endo-proteases, which provide critical regulatory connections between cell death and inflammation. Caspase 1 is driven by inflammasomes which are key signaling platforms, that detect sterile stressors (DAMPs), releasing the highly pro-inflammatory cytokine interleukin IL-8 and IL-1β. To delineate the involvement of Caspase 1 and 11 in hepatocellular injury in steatotic liver undergoing IRI. Male C57BL6/Wild Type and Caspase 1Null, Caspase 11-/- and Caspase 1-/-/11-/- mice were fed a high fat diet (HFD) for 12 weeks. These mice were subjected to 40 min of ischemia followed by 2-24 h of reperfusion. Hepatocellular injury was assessed by histopathologic injury scoring, serum ALT and propidium iodide (PI) uptake, mRNA levels of Caspase 1, IL-1β by RT PCR, Caspase 1 activity assay and Caspase 1. Specific Caspase 1, inhibitor experiments were carried out. All groups gained similar body weight after a 12-week HFD. Cleaved Caspase 1 protein levels, Caspase 1 mRNA levels were significantly higher in steatotic liver undergoing IRI. Executor of pyroptosis cleaved GSDMD levels were higher in HFD fed mouse compared to lean. In addition, genetic deletion of Caspase 1, Casp1Null mouse expressing Caspase-11 and Caspase 1/11 double knock out demonstrated significant reduction in serum ALT (p < 0.01), Injury Score, (p < 0.0002) but not in Caspase 11 alone. Caspase 1 is the driver of hepatocellular injury in a steatotic liver undergoing IRI, inhibition of which leads to hepatoprotection, thus providing a therapeutic target for clinical use.

SET8 mitigates hepatic ischemia/reperfusion injury in mice by suppressing MARK4/NLRP3 inflammasome pathway

AIMS

Hepatic ischemia/reperfusion (I/R) injury is a critical factor affecting the prognosis of liver surgery. The aim of this study is to explore the effects of SET8 on hepatic I/R injury and the putative mechanisms.

MAIN METHODS

The expression of SET8 and MARK4 in I/R group and sham group were detected both in vivo and in vitro. In addition, mouse and RAW 264.7 cells were transfected with MARK4 siRNA and SET8 siRNA knockdown of MARK4 and SET8, respectively. The expression of SET8, MARK4 and NLRP3-associated proteins were detected after different treatments. The pathology of liver and the serologic detection were detected after different treatments.

KEY FINDINGS

Our present study identified SET domain-containing protein 8 (SET8) as an efficient protein, which can negatively regulate hepatic I/R-mediated inflammatory response and ameliorate hepatic I/R injury by suppressing microtubule affinity-regulating kinase 4 (MARK4)/ NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway. The data showed that MARK4 deficiency inhibited hypoxia/reoxygenation (H/R)-induced NLRP3 inflammasome activation, while SET8 deficiency showed the opposite effect. We further demonstrated that SET8 restrained NLRP3 inflammasome activation by inhibiting MARK4. Moreover, we verified SET8 made protective effect on hepatic I/R injury.

SIGNIFICANCE

SET8 plays an essential role in hepatic ischemia/reperfusion injury in mice by suppressing MARK4/NLRP3 inflammasome pathway. Our results may offer a new strategy to mitigate hepatic I/R injury.

Nuclear Receptors in the Control of the NLRP3 Inflammasome Pathway

The innate immune system is the first line of defense specialized in the clearing of invaders whether foreign elements like microbes or self-elements that accumulate abnormally including cellular debris. Inflammasomes are master regulators of the innate immune system, especially in macrophages, and are key sensors involved in maintaining cellular health in response to cytolytic pathogens or stress signals. Inflammasomes are cytoplasmic complexes typically composed of a sensor molecule such as NOD-Like Receptors (NLRs), an adaptor protein including ASC and an effector protein such as caspase 1. Upon stimulation, inflammasome complex components associate to promote the cleavage of the pro-caspase 1 into active caspase-1 and the subsequent activation of pro-inflammatory cytokines including IL-18 and IL-1β. Deficiency or overactivation of such important sensors leads to critical diseases including Alzheimer diseases, chronic inflammatory diseases, cancers, acute liver diseases, and cardiometabolic diseases. Inflammasomes are tightly controlled by a two-step activation regulatory process consisting in a priming step, which activates the transcription of inflammasome components, and an activation step which leads to the inflammasome complex formation and the subsequent cleavage of pro-IL1 cytokines. Apart from the NF-κB pathway, nuclear receptors have recently been proposed as additional regulators of this pathway. This review will discuss the role of nuclear receptors in the control of the NLRP3 inflammasome and the putative beneficial effect of new modulators of inflammasomes in the treatment of inflammatory diseases including colitis, fulminant hepatitis, cardiac ischemia-reperfusion and brain diseases.

Protective Role of Coenzyme Q10 in Acute Sepsis-Induced Liver Injury in BALB/c Mice

Sepsis increases the risk of the liver injury development. According to the research works, coenzyme Q10 exhibits hepatoprotective properties in vivo as well as in vitro. Current work aimed at investigating the protective impacts of coenzyme Q10 against liver injury in septic BALB/c mice. The male BALB/c mice were randomly segregated into 4 groups: the control group, the coenzyme Q10 treatment group, the puncture and cecal ligation group, and the coenzyme Q10+cecal ligation and puncture group. Cecal ligation and puncture was conducted after gavagaging the mice with coenzyme Q10 during two weeks. Following 48 h postcecal ligation and puncture, we estimated hepatic biochemical parameters and histopathological changes in hepatic tissue. We evaluated the expression of factors associated with autophagy, pyroptosis, and inflammation. Findings indicated that coenzyme Q10 decreased the plasma levels in alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase in the cecal ligation and puncture group. Coenzyme Q10 significantly inhibited the elevation of sequestosome-1, interleukin-1β, oligomerization domain-like receptor 3 and nucleotide-binding, interleukin-6, and tumor necrosis factor-α expression levels; coenzyme Q10 also increased beclin 1 levels. Coenzyme Q10 might be a significant agent in the treatment of liver injury induced by sepsis.

PINK1-mediated mitophagy protects against hepatic ischemia/reperfusion injury by restraining NLRP3 inflammasome activation

Activation of nucleotide-binding domain leucine-rich repeat containing family pyrin domain containing 3 (NLRP3) inflammasome in Kupffer cells (KCs) contributes significantly to hepatic ischemia/reperfusion (I/R) injury, while the mechanism of how NLRP3 inflammasome is regulated remains less well defined. Recent evidence has showed that mitophagy acts as a central player for maintaining mitochondrial homeostatis through elimination of damaged mitochondria, leading to the prevention of hyperinflammation triggered by NLRP3 activation. In this study, we aimed at investigating the potential role of PTEN-induced kinase 1 (PINK1)-mediated mitophagy in hepatic I/R injury. C57BL/6 mice subjected to partial warm hepatic I/R or primary KCs exposed to anoxia/reoxygenation (A/R) was used as in vivo or in vitro model, respectively. Mitophagy was measured by protein levels of PINK1, Parkin, LC3B-II, TOMM20 and p62. NLRP3, caspase-1 and IL-1β at mRNA and/or protein levels were used as indicators of inflammasome activation. Our results demonstrated remarkable hepatic inflammation and NLRP3 inflammasome activation during hepatic I/R, along with increased PINK1-mediated mitophagy. Notably, overexpression of PINK1 in vivo attenuated hepatic I/R injury, ROS production, NLRP3 activation and hepatic inflammation. In parallel, A/R challenge in vitro also triggered NLRP3 activation in KCs accompanied by increase in mitophagy. Enhanced mitophagy mediated by PINK1 overexpression further inhibited NLRP3 activation and reversed the KC-mediated inflammatory injury to hepatocytes. Kinase-dead mutation of PINK1 completely abolished the above protective effects by PINK1. Blocking of mitophagy/autophagy by silencing of PINK1/Parkin, ATG5, NDP52 or OPTN showed the totally opposite effects, respectively. Treatment with different autophagic inhibitors also consistently reversed the PINK1-mediated effects, suggesting that an intact PINK1-mediated mitophagy signaling was crucial for ablation of NLRP3 signaling in the presence of A/R. Together, these results support a critical role of PINK1-mediated mitophagy in mitochondrial quality control for KC activation and function in hepatic I/R.

G protein-coupled receptor 30 activation protects hepatic ischemia-reperfusion injury of liver tissue through inhibiting NLRP3 in the rat model

One of the most prominent characteristics of hepatic ischemia-reperfusion injury (HI/R) is an intense inflammatory reaction, which plays a key role in inflammatory injury induced by ischemia-reperfusion. Nucleotide-binding oligomerization domain-containing protein (NOD-), leucine-rich repeat (LRR), and pyrin domains-containing protein 3 (NLRP3) are involved in the inflammatory injury of ischemia-reperfusion as an important pattern recognition receptor for innate immunity. G protein-coupled receptor 30 (GPR30) is a newly identified as 7-transmembrane G protein-coupled receptor and can be activated by many stimulations including estrogen. The current study aims to explore whether GPR30 agonist (G1) can alleviate hepatic ischemia-reperfusion injury HI/R by inhibiting NLRP3. An induced HI/R rat model was generated, blood and liver samples were gathered and subjected to histological examination, biochemical assays, Western blot assays, and qRT-PCR. Our results indicated GPR30 agonist (G1) pretreatment or NLRP3 silencing significantly decreased the serum levels of Interleukin 1β (IL-1β), alanine aminotransferase (ALT) and aspartate aminotransferase, improved histological alterations and hepatocyte apoptosis. Moreover, G1 pretreatment or NLRP3 silencing downregulated the protein level of Caspase-1 and pro-Interleukin 1β (pro-IL-1β) while G1 pretreatment upregulated the expression of GPR30 (p < 0.05). In conclusion, the salutary effects of GPR30 agonists on HI/R are mediated at least in part through downregulating NLRP3 expression. GPR30 may be used as a therapy target of HI/R.

ASC, IL-18 and Galectin-3 as Biomarkers of Non-Alcoholic Steatohepatitis: A Proof of Concept Study

Non-alcoholic steatohepatitis (NASH) is a severe form of non-alcoholic fatty liver disease that is growing in prevalence. Symptoms of NASH become apparent when the disease has progressed significantly. Thus, there is a need to identify biomarkers of NASH in order to detect the disease earlier and to monitor disease severity. The inflammasome has been shown to play a role in liver diseases. Here, we performed a proof of concept study of biomarker analyses (cut-off points, positive and negative predictive values, receiver operating characteristic (ROC) curves, and likelihood ratios) on the serum of patients with NASH and healthy controls on apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), interleukin (IL)-18, Galectin-3 (Gal-3), and C-reactive protein (CRP). ASC, IL-18, and Gal-3 were elevated in the serum of NASH patients when compared to controls. The area under the curve (AUC) for ASC was the highest (0.7317) with an accuracy of 68%, followed by IL-18 (0.7036) with an accuracy of 66% and Gal-3 (0.6891) with an accuracy of 61%. Moreover, we then fit a stepwise multivariate logistic regression model using ASC, IL-18, and Gal-3 to determine the probability of patients having a NASH diagnosis, which resulted in an AUC of 0.71 and an accuracy of 79%, indicating that combining these biomarkers increases their diagnostic potential for NASH. These results indicate that ASC, IL-18, and Gal-3 are reliable biomarkers of NASH and that combining these analytes increases the biomarker potential of these proteins.

The interrupted cross-talk of inflammatory and oxidative stress trajectories signifies the effect of artesunate against hepatic ischemia/reperfusion-induced inflammasomopathy

The antimalarial drug artesunate (Art) has proven its beneficial effects against ischemia/reperfusion (I/R) injury in diverse organs, but its potential role against hepatic I/R is still obscure. This study, hence, examined whether treatment with Art alone or in combination with rapamycin (Rapa), an mTOR inhibitor, can ameliorate hepatic I/R injury via targeting the NLRP3 inflammasome signaling pathway. Rats were divided into hepatic sham- and I/R-operated rats. The latter were either left untreated (I/R group) or treated with Art, Rapa, or their combination. On the molecular level, all treatment regimens succeeded to hinder inflammasome assembly and activation, assessed as NLRP3, ASC, cleaved caspase-1, caspase-11, N-terminal cleaved gasdermin-D (GSDMD-N), IL-1β, and IL-18. This effect was associated by the inhibition in the harmful signaling pathways HMGB1/RAGE and TLR4/MyD88/TRAF6 to inactivate the transcription factor NF-κB and the production of its pro-inflammatory cytokines IL-1β, IL-18, IL-6, and TNF-α. Additionally, this effect entailed the inhibition of ICAM-1/MPO/ROS cascade, which in turn hampered cell demise induced by apoptosis, manifested as correction of the imbalanced Bcl2/Bax, as well as pyroptosis (LDH, cleaved caspase-1, caspase-11, GSDMD-N, IL-1β, and IL-18), and necrosis. The corrected pathways were reflected on the improved liver function (serum ALT, AST, and LDH) and microscopical hepatic architecture. Noteworthy, the effect of Art on all parameters exceeded significantly that of Rapa and even improved the effect of the latter in the combination group. In conclusion, our results suggest novel roles for Art in abating functional and structural I/R-induced hepatic abnormalities via several traversing cross-talking pathways that succeeded to abate NLRP3 inflammasome and cell death.

Liver Ischemia Reperfusion Injury, Enhanced by Trained Immunity, Is Attenuated in Caspase 1/Caspase 11 Double Gene Knockout Mice

Ischemia reperfusion injury (IRI) during liver transplantation increases morbidity and contributes to allograft dysfunction. There are no therapeutic strategies to mitigate IRI. We examined a novel hypothesis: caspase 1 and caspase 11 serve as danger-associated molecular pattern (DAMPs) sensors in IRI. By performing microarray analysis and using caspase 1/caspase 11 double-knockout (Casp DKO) mice, we show that the canonical and non-canonical inflammasome regulators are upregulated in mouse liver IRI. Ischemic pre (IPC)- and post-conditioning (IPO) induce upregulation of the canonical and non-canonical inflammasome regulators. Trained immunity (TI) regulators are upregulated in IPC and IPO. Furthermore, caspase 1 is activated during liver IRI, and Casp DKO attenuates liver IRI. Casp DKO maintained normal liver histology via decreased DNA damage. Finally, the decreased TUNEL assay-detected DNA damage is the underlying histopathological and molecular mechanisms of attenuated liver pyroptosis and IRI. In summary, liver IRI induces the upregulation of canonical and non-canonical inflammasomes and TI enzyme pathways. Casp DKO attenuate liver IRI. Development of novel therapeutics targeting caspase 1/caspase 11 and TI may help mitigate injury secondary to IRI. Our findings have provided novel insights on the roles of caspase 1, caspase 11, and inflammasome in sensing IRI derived DAMPs and TI-promoted IRI-induced liver injury.

MicroRNA-124 regulates cell pyroptosis during cerebral ischemia-reperfusion injury by regulating STAT3

Cerebral ischemia-reperfusion injury (CIRI) is the observed continuation and deterioration of ischemic injury, and currently, there are no effective treatment strategies for the condition. It has been reported that microRNAs (miRNAs) serve an important role in CIRI by regulating pyroptosis. The present study demonstrated that miRNA-124 regulated CIRI by regulating STAT3. To explore the relationship between miRNA-124/STAT3 and pyroptosis in CIRI, CIRI was simulated using a middle cerebral artery occlusion model. Subsequently, miRNA-124 expression levels were altered via the intracerebroventricular injection of miRNA-124 agonist or antagonist. The degree of brain tissue injury was assessed by conducting TTC staining and neurological function scoring. Relative miRNA-124 expression levels were determined via reverse transcription-quantitative PCR. A luciferase reporter gene system verified the targeted binding of miRNA-124 to STAT3. The expression levels of key proteins and proinflammatory cytokines associated with pyroptosis [caspase-1, gasdermin D, interleukin (IL)-18 and IL-1β] were detected via western blotting and immunohistochemistry. The increased expression levels of pyroptosis-associated proteins and proinflammatory cytokines in the I/R groups compared with the control group, indicated that pyroptosis intensified over time during CIRI, and miRNA-124 agonist significantly abrogated pyroptosis and improved neurological function compared with the control group. Furthermore, miRNA-124 inhibited STAT3 activation in a targeted manner, which also decreased the extent of pyroptosis. However, miRNA-124 antagonist reversed miR-124 agonist-mediated effects. Therefore, the present study indicated that miRNA-124 may provide neuroprotection against pyroptosis during CIRI, potentially via inhibition of the STAT3 signaling pathway.

Aging aggravated liver ischemia and reperfusion injury by promoting STING-mediated NLRP3 activation in macrophages

Although aggravated liver injury has been reported in aged livers post‐ischemia and reperfusion (IR), the underlying mechanism of innate immune activation of aged macrophages is not well understood. Here, we investigated whether and how Stimulator of interferon genes (STING) signaling regulated macrophage proinflammatory activation and liver IR injury. Mice were subjected to hepatic IR in vivo. Macrophages isolated from IR‐stressed livers and bone marrow‐derived macrophages (BMDMs) from young and aged mice were used for in vitro studies. Enhanced nucleotide‐binding domain and leucine‐rich repeat containing protein 3 (NLRP3) activation was found in both livers and macrophages of aged mice post‐IR. NLRP3 knockdown in macrophages inhibited intrahepatic inflammation and liver injury in both young and aged mice. Interestingly, enhanced activation of the STING/ TANK‐binding kinase 1 (TBK1) signaling pathway was observed in aged macrophages post‐IR and mitochondria DNA (mtDNA) stimulation. STING suppression blocked over‐activation of NLRP3 signaling and excessive secretion of proinflammatory cytokines/chemokines in the mtDNA‐stimulated BMDMs from aged mice. More importantly, STING knockdown in macrophages abrogated the detrimental role of aging in aggravating liver IR injury and intrahepatic inflammation. Finally, peripheral blood from the recipients undergoing liver transplantation was collected and analyzed. The results showed that the elderly recipients had much higher levels of TNF‐α, IL‐6, IL‐1β, and IL‐18 post‐transplantation, indicating increased NLRP3 activation in lR‐stressed livers of elderly recipients. In summary, our study demonstrated that the STING‐NLRP3 axis was critical for the proinflammatory response of aged macrophages and would be a novel therapeutic target to reduce IR injury in elderly patients.

Rev-erbα regulates hepatic ischemia-reperfusion injury in mice

Hepatic ischemia-reperfusion (I/R) injury is a complex pathophysiological process that often times occurs in liver transplantation, hepatectomy, and ischemic shock. Aberrant activation of inflammatory responses has been implicated in hepatic I/R injury. In this study, we aimed to investigate the role of circadian clock gene Rev-erbα (a well-known regulator of inflammation) in hepatic I/R injury. We first showed that Rev-erbα ablation sensitized mice to hepatic I/R injury as evidenced by higher levels of plasma alanine aminotransferase and aspartate aminotransferase, an increased histological score, as well as enhanced hepatic myeloperoxidase activity in Rev-erbα^-/- mice. More severe hepatic I/R injury in Rev-erbα^-/- mice was accompanied by higher expression of pro-inflammatory cytokines, exacerbated activation of Nlrp3 inflammasome, and more extensive infiltration of inflammatory cells. Moreover, pharmacological activation of Rev-erbα by SR9009 significantly alleviated the hepatic damage and inflammatory responses. In addition, I/R operation started at ZT18 (corresponding to low Rev-erbα expression) caused more severe liver damage and inflammatory responses in wild-type mice as compared to operation started at ZT6 (corresponding to high Rev-erbα expression), supporting a protective effect of Rev-erbα on hepatic I/R injury. Collectively, Rev-erbα protects hepatic I/R injury probably via repression of inflammatory responses, and targeting Rev-erbα may be a promising approach for management of hepatic I/R injury.

Focus on the Role of NLRP3 Inflammasome in Diseases

Inflammation is a protective reaction activated in response to detrimental stimuli, such as dead cells, irritants or pathogens, by the evolutionarily conserved immune system and is regulated by the host. The inflammasomes are recognized as innate immune system sensors and receptors that manage the activation of caspase-1 and stimulate inflammation response. They have been associated with several inflammatory disorders. The NLRP3 inflammasome is the most well characterized. It is so called because NLRP3 belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs). Recent evidence has greatly improved our understanding of the mechanisms by which the NLRP3 inflammasome is activated. Additionally, increasing data in animal models, supported by human studies, strongly implicate the involvement of the inflammasome in the initiation or progression of disorders with a high impact on public health, such as metabolic pathologies (obesity, type 2 diabetes, atherosclerosis), cardiovascular diseases (ischemic and non-ischemic heart disease), inflammatory issues (liver diseases, inflammatory bowel diseases, gut microbiome, rheumatoid arthritis) and neurologic disorders (Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, amyotrophic lateral sclerosis and other neurological disorders), compared to other molecular platforms. This review will provide a focus on the available knowledge about the NLRP3 inflammasome role in these pathologies and describe the balance between the activation of the harmful and beneficial inflammasome so that new therapies can be created for patients with these diseases.

NLRP6 Plays an Important Role in Early Hepatic Immunopathology Caused by Schistosoma mansoni Infection

Schistosomiasis is a debilitating parasitic disease that affects more than 200 million people worldwide and causes approximately 280,000 deaths per year. Inside the definitive host, eggs released by Schistosoma mansoni lodge in the intestine and especially in the liver where they induce a granulomatous inflammatory process, which can lead to fibrosis. The molecular mechanisms initiating or promoting hepatic granuloma formation remain poorly understood. Inflammasome activation has been described as an important pathway to induce pathology mediated by NLRP3 receptor. Recently, other components of the inflammasome pathway, such as NLRP6, have been related to liver diseases and fibrotic processes. Nevertheless, the contribution of these components in schistosomiasis-associated pathology is still unknown. In the present study, using dendritic cells, we demonstrated that NLRP6 sensor is important for IL-1β production and caspase-1 activation in response to soluble egg antigens (SEA). Furthermore, the lack of NLRP6 has been shown to significantly reduce periovular inflammation, collagen deposition in hepatic granulomas and mRNA levels of α-SMA and IL-13. Livers of Nlrp6^–/– mice showed reduced levels of CXCL1/KC, CCL2, CCL3, IL-5, and IL-10 as well as Myeloperoxidase (MPO) and Eosinophilic Peroxidase (EPO) enzymatic activity. Consistently, the frequency of macrophage and neutrophil populations were lower in the liver of NLRP6 knockout mice, after 6 weeks of infection. Finally, it was further demonstrated that the onset of hepatic granuloma and collagen deposition were also compromised in Caspase-1^–/–, IL-1R^–/– and Gsdmd^–/– mice. Our findings suggest that the NLRP6 inflammasome is an important component for schistosomiasis-associated pathology.

RNA interference therapeutics in organ transplantation: The dawn of a new era

RNA interference (RNAi) is a natural process through which double-stranded RNA molecules can silence the gene carrying the same code as the particular RNA of interest. In 2006, the discovery of RNAi was awarded the Nobel Prize in Medicine and its success has accumulated since. Gene silencing through RNAi has been used successfully in a broad range of diseases, and, more recently, this technique has gained interest in the field of organ transplantation. Here, genes related to ischemia-reperfusion injury (IRI) or graft rejection may be silenced to improve organ quality after transplantation. Several strategies have been used to deliver siRNA, and pretransplant machine perfusion presents a unique opportunity to deliver siRNA to the target organ during ex situ preservation. In this review, the potential of RNAi in the field of organ transplantation will be discussed. A brief overview on the discovery of RNAi, its mechanism, and limitations are included. In addition, studies using RNAi to target genes related to IRI in liver, kidney, lung, and heart transplantation are discussed.

Inflammasome-Mediated Inflammation in Liver Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is an important cause of liver damage occurring during surgical procedures including hepatic resection and liver transplantation, and represents the main underlying cause of graft dysfunction and liver failure post-transplantation. To date, ischemia-reperfusion injury is an unsolved problem in clinical practice. In this context, inflammasome activation, recently described during ischemia-reperfusion injury, might be a potential therapeutic target to mitigate the clinical problems associated with liver transplantation and hepatic resections. The present review aims to summarize the current knowledge in inflammasome-mediated inflammation, describing the experimental models used to understand the molecular mechanisms of inflammasome in liver ischemia-reperfusion injury. In addition, a clear distinction between steatotic and non-steatotic livers and between warm and cold ischemia-reperfusion injury will be discussed. Finally, the most updated therapeutic strategies, as well as some of the scientific controversies in the field will be described. Such information may be useful to guide the design of better experimental models, as well as the effective therapeutic strategies in liver surgery and transplantation that can succeed in achieving its clinical application.

NLRP6 deficiency aggravates liver injury after allogeneic hematopoietic stem cell transplantation

This study aims to observe the expression and role of NLRP6 in liver injury after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). Allo-HSCT model was established through infusion of 5 × 10⁶ bone marrow mononuclear cells into whole body irradiated mice. On days 7, 14, 21 and 28 after transplantation, the peripheral blood was collected to detect liver function. The liver of the mice was obtained to assess the pathological changes of liver tissues after allo-HSCT by H&E staining and Mason staining. Meanwhile, expression of NLRP6, phosphorylated p38-MAPK and IκBα, caspase-1 and NLRP3 in liver were detected by Western blot. ELISA was used for detection of the level of interleukin (IL)-1β, IL-18, tumor necrosis factor (TNF)-α, IL-6, myeloperoxidase (MPO) and tumor growth factor (TGF)-β1. Increased expression of NLRP6, phosphorylated Iκbα, phosphorylated p38-MAPK, pro-caspase-1, and p20, in liver tissue with injury and fibrosis in mice after allo-HSCT were observed. Meanwhile, the level of IL-1β, IL-18, IL-6 and TNF-α was also increased. However, NLRP6^-/- mice showed more severe liver damage and liver fibrosis after transplantation together with higher level of phosphorylated Iκbα, phosphorylated p38-MAPK, Pro-caspase-1, p20 expression as well as IL-1β, IL-18, IL-6, and TNF-α secretion compared with wide-type. Interestingly, the expression of NLRP3 in the liver of NLRP6^-/- mice was significantly higher than that of wild-type. In conclusion, the expression of NLRP6 in host's liver is associated with liver injury after allo-HSCT. NLRP6 deficiency in host's liver leads to more severe liver damage, indicating a protective role of NLRP6 in host's liver to liver damage after allo-HSCT.

Serp-2, a virus-derived apoptosis and inflammasome inhibitor, attenuates liver ischemia-reperfusion injury in mice

BACKGROUND

Ischemia-reperfusion injury (IRI) is an antigen-independent, innate immune response to arterial occlusion and ischemia with subsequent paradoxical exacerbation after reperfusion. IRI remains a critical problem after vessel occlusion and infarction or during harvest and surgery in transplants. After transplant, liver IRI (LIRI) contributes to increased acute and chronic rejection and graft loss. Tissue loss during LIRI has been attributed to local macrophage activation and invasion with excessive inflammation together with hepatocyte apoptosis and necrosis. Inflammatory and apoptotic signaling are key targets for reducing post-ischemic liver injury.Myxomavirus is a rabbit-specific leporipoxvirus that encodes a suite of immune suppressing proteins, often with extensive function in other mammalian species. Serp-2 is a cross-class serine protease inhibitor (serpin) which inhibits the inflammasome effector protease caspase-1 as well as the apoptotic proteases granzyme B and caspases 8 and 10. In prior work, Serp-2 reduced inflammatory cell invasion after angioplasty injury and after aortic transplantation in rodents. In this report, we explore the potential for therapeutic treatment with Serp-2 in a mouse model of LIRI.

METHODS

Wildtype (C57BL/6 J) mice were subjected to warm, partial (70%) hepatic ischemia for 90 min followed by treatment with saline or Serp-2 or M-T7, 100 ng/g/day given by intraperitoneal injection on alternate days for 5 days. M-T7 is a Myxomavirus-derived inhibitor of chemokine-GAG interactions and was used in this study for comparative analysis of an unrelated viral protein with an alternative immunomodulating mechanism of action. Survival, serum ALT levels and histopathology were assessed 24 h and 10 days post-LIRI.

RESULTS

Serp-2 treatment significantly improved survival to 85.7% percent versus saline-treated wildtype mice (p = 0.0135), while M-T7 treatment did not significantly improve survival (p = 0.2584). Liver viability was preserved by Serp-2 treatment with a significant reduction in serum ALT levels (p = 0.0343) and infarct scar thickness (p = 0.0016), but with no significant improvement with M-T7 treatment. Suzuki scoring by pathologists blinded with respect to treatment group indicated that Serp-2 significantly reduced hepatocyte necrosis (p = 0.0057) and improved overall pathology score (p = 0.0046) compared to saline. Immunohistochemistry revealed that Serp-2 treatment reduced macrophage infiltration into the infarcted liver tissue (p = 0.0197).

CONCLUSIONS

Treatment with Serp-2, a virus-derived inflammasome and apoptotic pathway inhibitor, improves survival after liver ischemia-reperfusion injury in mouse models. Treatment with a cross-class immune modulator provides a promising new approach designed to reduce ischemia-reperfusion injury, improving survival and reducing chronic transplant damage.

Mitochondrial DNA in liver inflammation and oxidative stress

The function of liver is highly dependent on mitochondria producing ATP for biosynthetic and detoxifying properties. Accumulating evidence indicates that most hepatic disorders are characterized by profound mitochondrial dysfunction. Mitochondrial dysfunction not only exhibits mitochondrial DNA (mtDNA) damage and depletion, but also releases mtDNA. mtDNA is a closed circular molecule encoding 13 of the polypeptides of the oxidative phosphorylation system. Extensive mtDNA lesions could exacerbate mitochondrial oxidative stress and subsequently cause damage to hepatocytes. When mtDNA leaves the confines of mitochondria to the cytosolic and extracellular environment, it can act as damage-associated molecular patterns (DAMPs) to trigger the inflammatory response through the Toll-like receptor 9, inflammasomes, and stimulator of interferon genes (STING) pathways and further exacerbate hepatocellular damage and even remote organs injury. In addition, mtDNA also plays a vital role in hepatitis B virus (HBV)-related liver injury and hepatocellular carcinoma (HCC). In this review, we describe mtDNA alterations during liver injury, focusing on the mechanisms of mtDNA-mediated liver inflammation and oxidative stress injury.

Glycyrrhizin attenuates hepatic ischemia-reperfusion injury by suppressing HMGB1-dependent GSDMD-mediated kupffer cells pyroptosis

Gasdermin D (GSDMD), a genetic substrate for inflammatory caspases, plays a central role in pyroptosis of macrophages and release of interleukin‑1β (IL-1β), but was mainly referred to microbial infection. High mobility group box-1 (HMGB1), served as an alarm molecule during various pathological process, has been widely recognized to be involved in liver ischemia-reperfusion (I/R). Glycyrrhizin, a natural anti-inflammatory and antiviral triterpene in clinical use, was recently referred to have ability to prevent I/R induced liver injury by inhibiting HMGB1 expression and activity. However, the mechanisms responsible for damage amelioration subsequently to HMGB1 inhibition during liver I/R remain enigmatic. This study was designed to explore the functional role and molecular mechanism of glycyrrhizin in the regulation of I/R induced liver injury. We found that liver I/R promotes GSDMD-mediated pyroptotic cell death of Kupffer cells, which was inhibited by glycyrrhizin. Interestingly, endogenous HMGB1, not exogenous one, was involved in hypoxia-reoxygenation (H/R) induced pyroptosis. Moreover, GSDMD knockdown protects kupffer cells against H/R induced pyroptosis in vitro. Here, we report, for the first time, that glycyrrhizin attenuated tissue damage and kupffer cells pyroptosis during liver ischemia-reperfusion injury (LIRI) and identify a previously unrecognized HMGB1- dependent GSDMD- mediated signaling pathway in the mechanism of kupffer cells pyroptosis induced by H/R. Our findings provide the first demonstration of GSDMD-determined pyroptotic cell death responsible for I/R induced release of IL-1β and this would provide a mandate to better understand the unconventional mechanisms of cytokine release in the sterile innate immune system.

Gene Silencing With siRNA (RNA Interference): A New Therapeutic Option During Ex Vivo Machine Liver Perfusion Preservation

RNA interference (RNAi) is a natural process of posttranscriptional gene regulation that has raised a lot of attention culminating with the Nobel Prize in Medicine in 2006. RNAi-based therapeutics have been tested in experimental transplantation to reduce ischemia/reperfusion injury (IRI) with success. Modulation of genes of the innate immune system, as well as apoptotic genes, and those involved in the nuclear factor kappa B pathways can reduce liver injury in rodent liver pedicle clamping and transplantation models of IRI. However, in vivo use of RNAi faces limitations regarding the method of administration, uptake, selectivity, and stability. Machine perfusion preservation, a more recent alternative approach for liver preservation showing superior results to static cold preservation, could be used as a platform for gene interference therapeutics. Our group was the first to demonstrate uptake of small interfering RNA (siRNA) during liver machine preservation under both normothermic and hypothermic perfusion. Administering siRNA in the perfusion solution during ex vivo machine preservation has several advantages, including more efficient delivery, lower doses and cost-saving, and none/fewer side effects to other organs. Recently, the first RNAi drug was approved by the US Food and Drug Administration for clinical use, opening a new avenue for new drugs with different clinical applications. RNAi has the potential to have transformational therapeutic applications in several areas of medicine including transplantation. We believe that machine preservation offers great potential to be the ideal delivery method of siRNA to the liver graft, and future studies should be initiated to improve the clinical applicability of RNAi in solid organ transplantation.

The role of inflammasome complex in ischemia-reperfusion injury

Ischemia-reperfusion injury refers to a temporary interruption of blood flow in a tissue. Restoration of blood flow initiates the inflammation in tissue causing ischemic damage through the activation of a multiprotein complex termed inflammasome. The complex contains a receptor, mainly a member of nucleotide oligomerization domain-like receptors, that receives danger signals. The receptor is oligomerized as a response to danger signals and then the apoptosis-associated speck-like protein containing a caspase recruitment domain and procaspase protein are added to the oligomerized receptors to form the inflammasome complex. In the next step, the isolated procaspase is converted into an active caspase molecule that initiates the inflammation through the release of interleukin-1β and interleukin-18. The inflammasome has an important role in the pathogenesis of ischemia-reperfusion injury in different tissues. Here, we summarized the role of inflammasome in the pathogenesis of ischemia-reperfusion of brain, liver, kidney, and heart. Moreover, we highlighted the expression of inflammasome components, the mechanisms involved in activation of the complex, and its inhibition as an optimistic therapeutic technique in ischemia-reperfusion injuries.

NLRP3 Inflammasome and IL-33: Novel Players in Sterile Liver Inflammation

In sterile liver inflammation, danger signals are released in response to tissue injury to alert the immune system; e.g., by activation of the NLRP3 inflammasome. Recently, IL-33 has been identified as a novel type of danger signal or “alarmin”, which is released from damaged and necrotic cells. IL-33 is a pleiotropic cytokine that targets a broad range of immune cells and exhibits pro- and anti-inflammatory properties dependent on the disease. This review summarizes the immunomodulatory roles of the NLRP3 inflammasome and IL-33 in sterile liver inflammation and highlights potential therapeutic strategies targeting these pathways in liver disease.

Inflammasomes in Tissue Damages and Immune Disorders After Trauma

Trauma remains a leading cause of death worldwide. Hemorrhagic shock and direct injury to vital organs are responsible for early mortality whereas most delayed deaths are secondary to complex pathophysiological processes. These processes result from imbalanced systemic reactions to the multiple aggressions associated with trauma. Trauma results in the uncontrolled local and systemic release of endogenous mediators acting as danger signals [damage-associated molecular patterns (DAMPs)]. Their recognition by the innate immune system triggers a pro-inflammatory immune response paradoxically associated with concomitant immunosuppression. These responses, ranging in intensity from inappropriate to overwhelming, promote the propagation of injuries to remote organs, leading to multiple organ failure and death. Some of the numerous DAMPs released after trauma trigger the assembly of intracellular multiprotein complexes named inflammasomes. Once activated by a ligand, inflammasomes lead to the activation of a caspase. Activated caspases allow the release of mature forms of interleukin-1β and interleukin-18 and trigger a specific pro-inflammatory cell death termed pyroptosis. Accumulating data suggest that inflammasomes, mainly NLRP3, NLRP1, and AIM2, are involved in the generation of tissue damage and immune dysfunction after trauma. Following trauma-induced DAMP(s) recognition, inflammasomes participate in multiple ways in the development of exaggerated systemic and organ-specific inflammatory response, contributing to organ damage. Inflammasomes are involved in the innate responses to traumatic brain injury and contribute to the development of acute respiratory distress syndrome. Inflammasomes may also play a role in post-trauma immunosuppression mediated by dysregulated monocyte functions. Characterizing the involvement of inflammasomes in the pathogenesis of post-trauma syndrome is a key issue as they may be potential therapeutic targets. This review summarizes the current knowledge on the roles of inflammasomes in trauma.

Interference with KCTD9 inhibits NK cell activation and ameliorates fulminant liver failure in mice

Background

Potassium channel tetramerisation domain containing 9 (KCTD9), a member of KCTD family with a DNA-like pentapeptide repeat domain, was found to be increased particularly in NK cells of patients with HBV-induced acute-on-chronic liver failure (HBV-ACLF) and experimental viral fulminant hepatitis. Knockdown of KCTD9 in immortalized NK cells inhibits cytokines production and cytotoxicity. As NK cell activation was shown to exacerbate liver damage in viral fulminant hepatitis, we propose that target inhibition of KCTD9 may prohibit NK cells activity and thus ameliorate liver damage in viral fulminant hepatitis.

Result

Hydrodynamic delivery of plasmid expressing short-hairpin RNA against KCTD9 resulted in impaired NK cells function as demonstrated by reduced cytokine production and cytotoxicity, and ameliorated liver injury as manifested by improved liver histology and survival rate. In contrast, delivery of plasmid expressing KCTD9 led to deteriorated disease progression.

Conclusion

Interference with KCTD9 expression exert beneficial effect in viral fulminant hepatitis therapy. Such effect may be mediated by impairment of NK cell activation.

Electronic supplementary material

The online version of this article (10.1186/s12865-018-0256-x) contains supplementary material, which is available to authorized users.

Saikosaponin‑d alleviates carbon‑tetrachloride induced acute hepatocellular injury by inhibiting oxidative stress and NLRP3 inflammasome activation in the HL‑7702 cell line

Saikosaponin‑d (SSd) the primary active component of triterpene saponin derived from Bupleurum falcatum L., possesses anti‑inflammatory and antioxidant properties. The present study aimed to examine the potential therapeutic effects of SSd on carbon tetrachloride (CCl4)‑induced acute hepatocellular injury in the HL‑7702 cell line and its underlying mechanisms. HL‑7702 cells were treated with SSd at different doses (0.5, 1 or 2 µmol/l). Cell viability was determined using an MTT assay. Injury was assessed by the levels of serum alanine aminotransferase (ALT) and aspartate transaminase (AST). Oxidative stress was assessed using malondialdehyde (MDA) content and total‑superoxide dismutase (T‑SOD) activity. The expression of nucleotide‑binding domain, leucine‑rich‑containing family, pyrin domain‑containing‑3 (NLRP3), apoptosis‑associated speck‑like protein (ASC), caspase‑1 and high mobility group protein B1 (HMGB1) was assessed by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis. Interleukin (IL)‑1β and IL‑18 were determined by RT‑qPCR and ELISA. SSd attenuated the inhibition of cell viability and the high AST and ALT levels induced by CCl4 in HL‑7702 cells. Oxidative stress was induced in HL‑7702 cells by CCl4, as demonstrated by the increase of MDA and the decrease of T‑SOD activity. These changes were reversed by SSd. SSd significantly downregulated the mRNA and protein expression of NLRP3, ASC, caspase‑1, IL‑1β, IL‑18 and HMGB1 induced by CCl4. In conclusion SSd alleviated CCl4‑induced acute hepatocellular injury, possibly by inhibiting oxidative stress and NLRP3 inflammasome activation in the HL‑7702 cell line.

Effects of resveratrol on activation of NLRP3 inflammasome in HSC-T6 cells

AIM

To investigate the effect of resveratrol (Res) on the activation of nod-like receptor protein 3 (NLRP3) inflammasome in hepatic stellate cell (HSC)-T6 cells and to explore the anti-fibrotic mechanism of Res.

METHODS

Rat hepatic stellate cell (HSC) line HSC-T6 was used. HSC-T6 cells were seeded into cell culture plates with high glucose DMEM medium containing 10% fetal bovine serum for 24 h. Then, the cells were incubated with Res (4, 8, and 16 μmol/L) or acetylcysteine (NAC; 5 mmol/L) for 24 h. Oxidative stress (OS) was induced by exposure to hydrogen peroxide (H₂O₂; 0.2 mmol/L) for 4 h. MTT method was used to observe the effect of Res on HSC-T6 cell proliferation. ELISA was used to detect the contents of type I collagen (COL-I), transforming growth factor β1 (TGF-β1), interleukin (IL)-1β, IL-18, malondialdehyde (MDA), and superoxide dismutase (SOD) in cell culture supernatant. Reactive oxygen species (ROS) production was measured with a fluorescence microplate reader following staining with DCFH-DA probe. Western blot analysis was used to detect the expression of alpha-smooth muscle actin (α-SMA), NLRP3, apoptosis-associated speck-like protein (ASC), and cysteinyl aspartate specific proteinase 1 (caspase 1) in HSC-T6 cells.

RESULTS

Compared with control cells, Res at concentrations from 4 μmol/L to 64 μmol/L significantly suppressed the proliferation of HSC-T6 cells. Compared with control cells, OS induction significantly increased the proliferation of HSC-T6 cells, the contents of COL-1, TGF-β1, MDA, IL-1β, and IL-18 in cell culture supernatant, intracellular ROS production, and the protein expression of α-SMA, NLRP3, ASC, and caspase 1-p10 (P < 0.01), but decreased the content of SOD in cell culture supernatant (P < 0.01). Compared with the OS group, treatment with low-, medium-, or high-dose Res or positive control NAC significantly decreased the proliferation of HSC-T6 cells, the contents of COL-1, TGF-β1, MDA, IL-1β, and IL-18 in cell culture supernatant, intracellcular ROS production, and the protein expression of α-SMA, NLRP3, ASC, and caspase 1-p10 (P < 0.01), but increased the content of SOD in cell culture supernatant (P < 0.01).

CONCLUSION

Res could suppress the proliferation and activation of HSC-T6 cells via down-regulation of ROS-NLRP3 inflammasome signaling.

Cardioprotective effect of rosuvastatin against isoproterenol-induced myocardial infarction injury in rats

Rosuvastatin, a member of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, exerts various pharmacological activities. This study evaluated the cardioprotective effect of rosuvastatin on isoproterenol-induced myocardial infarction injury in rats. A rat model of myocardial infarction injury was induced by isoproterenol (ISO) for 2 consecutive days, rosuvastatin was administered for 8 weeks. The levels of myocardial infarct size, aspartate transaminase (AST), alanine transaminase (ALT), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH) activities, as well as malondialdehyde (MDA) levels, superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) activities and reduced glutathione (GSH) concentrations were determined. Hematoxylin and eosin staining was used to observe cardiac histological changes. Interleukin-1β (IL-1β) and IL-18 levels in heart tissues were detected with ELISA kits. The mRNA and protein levels of NOD-like receptor superfamily, pyrin domain containing 3 (NLRP3) inflammasome were measured by qRT-PCR and western blot analysis, respectively. Our results showed that treatment with rosuvastatin reduced myocardial infract area, ameliorated histopathological alterations in myocardium, and decreased activities of myocardial injury marker enzymes in ISO-induced rats. In addition, rosuvastatin remarkably restored ISO-induced elevation of lipid peroxidation and decrease of antioxidants, significantly reduced myocardial pro-inflammatory cytokines concentrations in this animal model. Furthermore, rosuvastatin significantly inhibited the activation of NLRP3 inflammasome in this animal model. This study demonstrates that rosuvastatin significantly alleviates ISO-induced myocardial infarction injury. The mechanism is associated with attenuation of oxidative stress and inflammation, via the inhibition of NLRP3 inflammasome.

Activation of NLRP3 inflammasomes in mouse hepatic stellate cells during Schistosoma J. infection

The major pathological changes during Schistosoma J. infection are characterized by granulomatous inflammation in the liver, a cellular immune response to schistosomal egg antigens. The molecular mechanisms initiating or promoting this schistosomal granulomatous inflammation remain poorly understood. In the present study, we first demonstrated that in mice infected with Schistosoma J. for 6 weeks exhibited increased levels of IL-1β in liver, a major product of NLRP3 inflammasomes and collagen deposition around the eosinophilic granuloma with Schistosoma J. eggs, which was substantially attenuated by caspase-1 inhibitor, YVAD. This activation of the NLRP3 inflammasome occurred in hepatic stellate cells (HSCs), as shown by a marked increase in co-localization of IL-1β with HSCs marker, desmin. Using isolated, cultured mouse HSCs, we further explored the mechanisms by which soluble egg antigen (SEA) from Schistosoma J. activates NLRP3 inflammasomes. SEA induced the formation and activation of NLRP3 inflammasomes, which was associated with both redox regulation and lysosomal dysfunction, but not with potassium channel activation. These results suggest that NLRP3 inflammasome activation in HSCs may serve as an early mechanism to turn on the inflammatory response and thereby instigate liver fibrosis during Schistosoma J. infection.

Traumatic Injury

Traumatic injury as one of the world's most relevant but neglected health concerns results in modulated inflammasome activity, which is closely linked to the development of post-injury complications. Cytokine-producing capacity of cells is important for the appropriate immune response to trauma and requires not only synthesis and transcription of inflammasome components but also their activation. Unfortunately, the precise role of inflammasome in trauma is still largely unknown. However, in the following chapter, we provide an overview on the best described inflammasomes in the various settings of trauma, introducing the recent findings on the up-to-date best described NLRP inflammasomes and underlying cytokines in the inflammatory response to trauma.