Interaction of Neutrophils with Macrophages Promotes IL-1β Maturation and Contributes to Hepatic Ischemia–Reperfusion Injury

Inhibition of 7-dehydrocholesterol reductase prevents hepatic ferroptosis under an active state of sterol synthesis

Recent evidence indicates ferroptosis is implicated in the pathophysiology of various liver diseases; however, the organ-specific regulation mechanism is poorly understood. Here, we demonstrate 7-dehydrocholesterol reductase (DHCR7), the terminal enzyme of cholesterol biosynthesis, as a regulator of ferroptosis in hepatocytes. Genetic and pharmacological inhibition (with AY9944) of DHCR7 suppress ferroptosis in human hepatocellular carcinoma Huh-7 cells. DHCR7 inhibition increases its substrate, 7-dehydrocholesterol (7-DHC). Furthermore, exogenous 7-DHC supplementation using hydroxypropyl β-cyclodextrin suppresses ferroptosis. A 7-DHC-derived oxysterol metabolite, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), is increased by the ferroptosis-inducer RSL-3 in DHCR7-deficient cells, suggesting that the ferroptosis-suppressive effect of DHCR7 inhibition is associated with the oxidation of 7-DHC. Electron spin resonance analysis reveals that 7-DHC functions as a radical trapping agent, thus protecting cells from ferroptosis. We further show that AY9944 inhibits hepatic ischemia-reperfusion injury, and genetic ablation of Dhcr7 prevents acetaminophen-induced acute liver failure in mice. These findings provide new insights into the regulatory mechanism of liver ferroptosis and suggest a potential therapeutic option for ferroptosis-related liver diseases.

Impact of dual neutralization of TNF-α and IL-1β along with Gentamicin treatment on the functions of blood and splenic neutrophils and its role on improvement of S. aureus induced septic arthritis

Researches of recent past years have emphasized potential of antibiotics to improve septic arthritis but as multi-drug resistant strains like MRSA are emerging fast, new alternative therapeutic advances are high in demand. This study aims to figure out the role of neutrophils in regulating inflammatory responses of S. aureus induced septic arthritis while using TNF-α Ab or IL-1β Ab along with antibiotic gentamicin or both in combination. In this study, role of anti-oxidant enzymes were investigated and correlated with generated ROS level. While expression of TLR2, TNFR2, MMP2, RANKL, SAPK/JNK in the spleen were evaluated through western blot. Serum activity of IL-8, IL-10, IL-12, OPG, OPN, CRP was assessed using ELISA. Flow cytometry study evaluated inflamed neutrophil population. Results have shown TNF-α neutralization along with gentamicin was able to reduce arthritic swelling prominently. While combination therapy effectively reduced blood neutrophil ROS activity, arginase activity, MPO activity along with spleen bacterial burden. Serum OPG, CRP, IL-10 level got reduced while serum OPN, IL-8 and IL-12 level enhanced in treatment groups, showing mitigation of inflammatory damage. Overall, it is a novel work that observed how antibiotic and antibody therapy enhanced neutrophil function positively to combat sepsis. This study may not be fully applicable in clinical trials as it is performed with animal model. Clinical trials include crystalline and inflammatory arthritides, trauma, neoplasm. Interdisciplinary collaboration between radiology, orthopaedic surgery and knowledge of animal system responses may give better idea to find proper therapeutic approach in future research works.

Impact of age on liver damage, inflammation, and molecular signaling pathways in response to femoral fracture and hemorrhage

Background

Trauma causes disability and mortality globally, leading to fractures and hemorrhagic shock. This can trigger an irregular inflammatory response that damages remote organs, including liver. Aging increases the susceptibility to dysregulated immune responses following trauma, raising the risk of organ damage, infections, and higher morbidity and mortality in elderly patients. This study investigates how aging affects liver inflammation and damage post-trauma.

Methods

24 male C57BL/6J mice were randomly divided into four groups. Twelve young (17-26 weeks) and 12 aged (64-72 weeks) mice were included. Mice further underwent either hemorrhagic shock (trauma/hemorrhage, TH), and femoral fracture (osteotomy) with external fixation (Fx) (THFx, n=6) or sham procedures (n=6). After 24 hours, mice were sacrificed. Liver injury and apoptosis were evaluated using hematoxylin-eosin staining and activated caspase-3 immunostaining. CXCL1 and infiltrating polymorphonuclear leukocytes (PMNL) in the liver were assessed by immunostaining, and concentrations of CXCL1, TNF, IL-1β, and IL-10 in the liver tissue were determined by ELISA. Gene expression of Tnf, Cxcl1, Il-1β, and Cxcl2 in the liver tissue was determined by qRT-PCR. Finally, western blot was used to determine protein expression levels of IκBα, Akt, and their phosphorylated forms.

Results

THFx caused liver damage and increased presence of active caspase-3-positive cells compared to the corresponding sham group. THFx aged group had more severe liver injury than the young group. CXCL1 and PMNL levels were significantly higher in both aged groups, and THFx caused a greater increase in CXCL and PMNL levels in aged compared to the young group. Pro-inflammatory TNF and IL-1β levels were elevated in aged groups, further intensified by THFx. Anti-inflammatory IL-10 levels were lower in aged groups. Tnf and Cxcl1 gene expression was enhanced in the aged sham group. Phosphorylation ratio of IκBα was significantly increased in the aged sham group versus young sham group. THFx-induced IκBα phosphorylation in the young group was significantly reduced in the aged THFx group. Akt phosphorylation was significantly reduced in the THFx aged group compared to the THFx young group.

Conclusion

The findings indicate that aging may lead to increased vulnerability to liver injury and inflammation following trauma due to dysregulated immune responses.

NLRP3 inflammasome-driven IL-1β and IL-18 contribute to lipopolysaccharide-induced septic cardiomyopathy

Sepsis is a life-threatening syndrome, and its associated mortality is increased when cardiac dysfunction and damage (septic cardiomyopathy [SCM]) occur. Although inflammation is involved in the pathophysiology of SCM, the mechanism of how inflammation induces SCM in vivo has remained obscure. NLRP3 inflammasome is a critical component of the innate immune system that activates caspase-1 (Casp1) and causes the maturation of IL-1β and IL-18 as well as the processing of gasdermin D (GSDMD). Here, we investigated the role of the NLRP3 inflammasome in a murine model of lipopolysaccharide (LPS)-induced SCM. LPS injection induced cardiac dysfunction, damage, and lethality, which was significantly prevented in NLRP3-/- mice, compared to wild-type (WT) mice. LPS injection upregulated mRNA levels of inflammatory cytokines (Il6, Tnfa, and Ifng) in the heart, liver, and spleen of WT mice, and this upregulation was prevented in NLRP3-/- mice. LPS injection increased plasma levels of inflammatory cytokines (IL-1β, IL-18, and TNF-α) in WT mice, and this increase was markedly inhibited in NLRP3-/- mice. LPS-induced SCM was also prevented in Casp1/11-/- mice, but not in Casp11mt, IL-1β-/-, IL-1α-/-, or GSDMD-/- mice. Notably, LPS-induced SCM was apparently prevented in IL-1β-/- mice transduced with adeno-associated virus vector expressing IL-18 binding protein (IL-18BP). Furthermore, splenectomy, irradiation, or macrophage depletion alleviated LPS-induced SCM. Our findings demonstrate that the cross-regulation of NLRP3 inflammasome-driven IL-1β and IL-18 contributes to the pathophysiology of SCM and provide new insights into the mechanism underlying the pathogenesis of SCM.

Early Growth Response-1: Friend or Foe in the Heart?

Cardiovascular disease is a major cause of mortality and morbidity worldwide. Early growth response-1 (Egr-1) plays a critical regulatory role in a range of experimental models of cardiovascular diseases. Egr-1 is an immediate-early gene and is upregulated by various stimuli including shear stress, oxygen deprivation, oxidative stress and nutrient deprivation. However, recent research suggests a new, underexplored cardioprotective side of Egr-1. The main purpose of this review is to explore and summarise the dual nature of Egr-1 in cardiovascular pathobiology.

Local injection of bone-marrow derived mesenchymal stromal cells alters a molecular expression profile of a contact frostbite injury wound and improves healing in a rat model

INTRODUCTION

Frostbite is a traumatic injury of the tissues upon low temperature environment exposure, which is characterized by direct cell injury due to freezing-thawing followed by development of an acute inflammatory process. Severe frostbite can lead to necrosis of soft tissues and loss of a limb. Mesenchymal stromal cells (MSCs) have a unique ability to modulate pathogenic immune response by secretion of paracrine factors, which suppress inflammation and mediate more efficient tissue regeneration. It should be noted that potential of stem cell therapy for frostbite injury treatment has not been investigated so far. Here, we evaluated a healing capacity of bone-marrow derived MSCs for the treatment of contact frostbite injury wound in a rat model.

METHODS

Cold-contact injury in a Wistar rat model was induced by 1-minute tight application of the cooled probe (-196 ⁰C) to the skin surface of the left hip. Rat bone marrow MSCs were phenotypically characterized and used for local injections into non-damaged tissues surrounding the wound of animals from the experimental group. The second group of rats was treated in the same manner with 1 mL of isotonic sodium chloride solution. Analysis of cytokine and growth factor expression profile in сold-contact injury wounds was performed on days 5, 9, and 16 using immunoblotting and enzyme-linked immunosorbent assay. Animal recovery in MSC-treated and vehicle-treated groups was evaluated by several criteria including body weight recording, determination of eschar desquamation and re-epithelialization terms, assessment of wound closure kinetics, and histological scoring of the wounds on day 23.

RESULTS

It turned out that a single subcutaneous administration of MSCs around the wound site resulted in elevated expression of pro-survival and pro-angiogenic VEGF-A and PDGF and 3-5-fold decrease in pro-inflammatory IL-1β as compared with the frostbite wound treated with a vehicle. Moreover, treatment with MSCs caused accelerated wound re-epithelialization (p < 0.05) as well as a better histological score of the MSC-treated wounds.

CONCLUSIONS

Thus, our data suggested that the use of MSCs is a promising therapeutic strategy for the treatment of cold-induced injury wounds.

Innate Immune Cells during Machine Perfusion of Liver Grafts-The Janus Face of Hepatic Macrophages

Machine perfusion is an emerging technology in the field of liver transplantation. While machine perfusion has now been implemented in clinical routine throughout transplant centers around the world, a debate has arisen regarding its concurrent effect on the complex hepatic immune system during perfusion. Currently, our understanding of the perfusion-elicited processes involving innate immune cells remains incomplete. Hepatic macrophages (Kupffer cells) represent a special subset of hepatic immune cells with a dual pro-inflammatory, as well as a pro-resolving and anti-inflammatory, role in the sequence of ischemia-reperfusion injury. The purpose of this review is to provide an overview of the current data regarding the immunomodulatory role of machine perfusion and to emphasize the importance of macrophages for hepatic ischemia-reperfusion injury.

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.

Interleukin-35 ameliorates cardiovascular disease by suppressing inflammatory responses and regulating immune homeostasis

The immune response is of great significance in the initiation and progression of a diversity of cardiovascular diseases involving pro-and anti-inflammatory cytokines. Interleukin-35 (IL-35), a cytokine of the interleukin-12 family, is a novel anti-inflammation and immunosuppressive cytokine, maintaining inflammatory suppression and regulating immune homeostasis. The role of IL-35 in cardiovascular diseases (CVDs) has aroused enthusiastic attention, a diversity of experimental or clinical evidence has indicated that IL-35 potentially has a pivot role in protecting against cardiovascular diseases, especially atherosclerosis and myocarditis. In this review, we initiate an overview of the relationship between Interleukin-35 and cardiovascular diseases, including atherosclerosis, acute coronary syndrome, pulmonary hypertension, abdominal aortic aneurysm, heart failure, myocardial ischemia-reperfusion, aortic dissection and myocarditis. Although the specific molecular mechanisms entailing the protective effects of IL-35 remain an unsolved issue, targeted therapies with IL-35 might provide a promising and effective solution to prevent and cure cardiovascular diseases.

The Therapeutic Treatment with the GAG-Binding Chemokine Fragment CXCL9(74-103) Attenuates Neutrophilic Inflammation and Lung Dysfunction during Klebsiella pneumoniae Infection in Mice

Klebsiella pneumoniae is an important pathogen associated with hospital-acquired pneumonia (HAP). Bacterial pneumonia is characterized by a harmful inflammatory response with a massive influx of neutrophils, production of cytokines and chemokines, and consequent tissue damage and dysfunction. Targeted therapies to block neutrophil migration to avoid tissue damage while keeping the antimicrobial properties of tissue remains a challenge in the field. Here we tested the effect of the anti-inflammatory properties of the chemokine fragment CXCL9(74–103) in pneumonia induced by Klebsiella pneumoniae in mice. Mice were infected by intratracheal injection of Klebsiella pneumoniae and 6 h after infection were treated systemically with CXCL9(74–103). The recruitment of leukocytes, levels of cytokines and chemokines, colony-forming units (CFU), and lung function were evaluated. The treatment with CXCL9(74–103) decreased neutrophil migration to the airways and the production of the cytokine interleukin-1β (IL-1β) without affecting bacterial control. In addition, the therapeutic treatment improved lung function in infected mice. Our results indicated that the treatment with CXCL9(74–103) reduced inflammation and improved lung function in Klebsiella pneumoniae-induced pneumonia.

Renin-angiotensin system inhibitors combined with cisplatin exacerbate cisplatin-induced nephrotoxicity in mice

INTRODUCTION

We previously reported that the concomitant use of enalapril and telmisartan exacerbates the risk of cisplatin (CDDP)-induced acute renal dysfunction compared to other antihypertensive drugs in mice. Thus, in the current study, we investigated the risk of developing chronic kidney disease following repeated concomitant use of CDDP and antihypertensive drugs.

MATERIALS AND METHODS

Male BALB/c mice were divided into 12 groups: (1) Control group (untreated), (2) CDDP group (7 mg/kg, CDDP), (3) AML group (5 mg/kg, amlodipine), (4) ENA group (2.5 mg/kg, enalapril), (5) TEL group (10 mg/kg, telmisartan), (6) LOS group (10 mg/kg, losartan), (7) CDDP+AML group (5 mg/mL, AML), (8) CDDP+ENA group (2.5 mg/kg, ENA), (9) CDDP+LowENA group (1.25 mg/kg, ENA), (10) CDDP+TEL group (10 mg/kg, TEL), (11) CDDP+LowTEL group (5 mg/kg, TEL), and (12) CDDP+LOS group (10 mg/kg, LOS). CDDP was administered intraperitoneally four times every 7 days, and each antihypertensive drug was administered orally from day 3 before CDDP administration until day 24 (six times a week). The degree of renal damage was assessed. The nephrotoxicity of each individual was evaluated by measuring serum creatinine and blood urea nitrogen levels. The degrees of renal fibrosis and epithelial-mesenchymal transition were also examined in kidney tissue sections.

RESULTS AND DISCUSSION

The results suggest that combinatorial treatment of CDDP and renin-angiotensin system inhibitors, particularly ENA and TEL, may exacerbate CDDP-induced nephrotoxicity. This study clearly demonstrates the need for large-scale clinical studies to construct treatment regimens that do not interfere with the therapeutic intensity of CDDP.

Polymorphonuclear Neutrophils in Rheumatoid Arthritis and Systemic Lupus Erythematosus: More Complicated Than Anticipated

Polymorphonuclear neutrophils (PMN) are the most abundant leucocytes in the circulation in humans. They represent a heterogeneous population exerting diverse functions through several activities. Usually described as typical pro-inflammatory cells, immunomodulatory properties of PMNs have been reported. Among others, once activated and depending on the stimulus, PMNs expel neutrophil extracellular traps (NET) in the extracellular space. NETs are complexes made of DNA and granule proteins representing an innate immune mechanism fighting infections. Nevertheless, an excess of NET formation might be involved in the development of inflammatory or autoimmune responses. Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are two chronic, inflammatory, autoimmune diseases of unknown etiology and affecting mostly women. Several abnormal or non-classical functions of PMNs or PMN sub-populations have been described in SLE and RA. Particularly, NETs have been suggested to trigger pro-inflammatory responses by exposing pro-inflammatory mediators. Likewise, NETs may be the targets of autoantibodies or even might trigger the development of autoantibodies by exposing autoantigens. In the present review, we will summarize heterogeneous properties of human PMNs and we will discuss recent evidence linking PMNs and NETs to the pathogenesis of both SLE and RA.

Inhibition of NETosis for treatment purposes: friend or foe?

Active neutrophils participate in innate and adaptive immune responses through various mechanisms, one of the most important of which is the formation and release of neutrophil extracellular traps (NETs). The NETs are composed of network-like structures made of histone proteins, DNA and other released antibacterial proteins by activated neutrophils, and evidence suggests that in addition to the innate defense against infections, NETosis plays an important role in the pathogenesis of several other non-infectious pathological states, such as autoimmune diseases and even cancer. Therefore, targeting NET has become one of the important therapeutic approaches and has been considered by researchers. NET inhibitors or other molecules involved in the NET formation, such as the protein arginine deiminase 4 (PAD4) enzyme, an arginine-to-citrulline converter, participate in chromatin condensation and NET formation, is the basis of this therapeutic approach. The important point is whether complete inhibition of NETosis can be helpful because by inhibiting this mechanism, the activity of neutrophils is suppressed. In this review, the biology of NETosis and its role in the pathogenesis of some important diseases have been summarized, and the consequences of treatment based on inhibition of NET formation have been discussed.

Immunomonitoring of Monocyte and Neutrophil Function in Critically Ill Patients: From Sepsis and/or Trauma to COVID-19

Immune cells and mediators play a crucial role in the critical care setting but are understudied. This review explores the concept of sepsis and/or injury-induced immunosuppression and immuno-inflammatory response in COVID-19 and reiterates the need for more accurate functional immunomonitoring of monocyte and neutrophil function in these critically ill patients. in addition, the feasibility of circulating and cell-surface immune biomarkers as predictors of infection and/or outcome in critically ill patients is explored. It is clear that, for critically ill, one size does not fit all and that immune phenotyping of critically ill patients may allow the development of a more personalized approach with tailored immunotherapy for the specific patient. In addition, at this point in time, caution is advised regarding the quality of evidence of some COVID-19 studies in the literature.

Neutrophil Extracellular Traps Augmented Alveolar Macrophage Pyroptosis via AIM2 Inflammasome Activation in LPS-Induced ALI/ARDS

Background

Uncontrollable inflammation is a critical feature of gram-negative bacterial pneumonia-induced acute respiratory distress syndrome (ARDS). Both neutrophils and alveolar macrophages participate in inflammation, but how their interaction augments inflammation and triggers ARDS is unclear. The authors hypothesize that neutrophil extracellular traps (NETs), which are formed during neutrophil NETosis, partly cause alveolar macrophage pyroptosis and worsen the severity of ARDS.

Methods

The authors first analysed whether NETs and caspase-1 are involved in clinical cases of ARDS. Then, the authors employed a lipopolysaccharide (LPS)-induced ARDS model to investigate whether targeting NETs or alveolar macrophages is protective. The AIM2 sensor can bind to DNA to promote AIM2 inflammasome activation, so the authors studied whether degradation of NET DNA or silencing of the AIM2 gene could protect alveolar macrophages from pyroptosis in vitro.

Results

Analysis of aspirate supernatants from ARDS patients showed that NET and caspase-1 levels were correlated with the severity of ARDS and that the levels of NETs and caspase-1 were higher in nonsurvivors than in survivors. In vivo, the NET level and proportion of pyroptotic alveolar macrophages in bronchoalveolar lavage fluid (BALF) were obviously higher in LPS-challenged mice than in control mice 24 h after injury. Administration of DNase I (a NET DNA-degrading agent) and BB-Cl-amidine (a NET formation inhibitor) alleviated alveolar macrophage pyroptosis, and Ac-YVAD-cmk (a pyroptosis inhibitor) attenuated NET levels in BALF and neutrophil infiltration in alveoli. All treatments markedly attenuated the severity of ARDS. Notably, LPS causes NETs to induce alveolar macrophage pyroptosis, and degradation of NET DNA or silencing of the AIM2 gene protected against alveolar macrophage pyroptosis.

Conclusion

These findings shed light on the proinflammatory role of NETs in mediating the neutrophil-alveolar macrophage interaction, which influences the progression of ARDS.

Monoacylglycerol Acyltransferase 1 Knockdown Exacerbates Hepatic Ischemia/Reperfusion Injury in Mice With Hepatic Steatosis

Nonalcoholic fatty liver disease (NAFLD) is becoming the most common indication for liver transplantation. The growing prevalence of NAFLD not only increases the demand for liver transplantation, but it also limits the supply of available organs because steatosis predisposes grafts to ischemia/reperfusion injury (IRI) and many steatotic grafts are discarded. We have shown that monoacylglycerol acyltransferase (MGAT) 1, an enzyme that converts monoacylglycerol to diacylglycerol, is highly induced in animal models and patients with NAFLD and is an important mediator in NAFLD-related insulin resistance. Herein, we sought to determine whether Mogat1 (the gene encoding MGAT1) knockdown in mice with hepatic steatosis would reduce liver injury and improve liver regeneration following experimental IRI. Antisense oligonucleotides (ASO) were used to knockdown the expression of Mogat1 in a mouse model of NAFLD. Mice then underwent surgery to induce IRI. We found that Mogat1 knockdown reduced hepatic triacylglycerol accumulation, but it unexpectedly exacerbated liver injury and mortality following experimental ischemia/reperfusion surgery in mice on a high-fat diet. The increased liver injury was associated with robust effects on the hepatic transcriptome following IRI including enhanced expression of proinflammatory cytokines and chemokines and suppression of enzymes involved in intermediary metabolism. These transcriptional changes were accompanied by increased signs of oxidative stress and an impaired regenerative response. We have shown that Mogat1 knockdown in a mouse model of NAFLD exacerbates IRI and inflammation and prolongs injury resolution, suggesting that Mogat1 may be necessary for liver regeneration following IRI and that targeting this metabolic enzyme will not be an effective treatment to reduce steatosis-associated graft dysfunction or failure.

Inhibition of BRD4 Reduces Neutrophil Activation and Adhesion to the Vascular Endothelium Following Ischemia Reperfusion Injury

Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil infiltration that exacerbates the initial ischemic insult. The molecular pathways involved are poorly characterized and there is currently no treatment. We performed an in silico analysis demonstrating changes in NFκB-mediated gene expression in early renal IRI. We then evaluated NFκB-blockade with a BRD4 inhibitor on neutrophil adhesion to endothelial cells in vitro, and tested BRD4 inhibition in an in vivo IRI model. BRD4 inhibition attenuated neutrophil adhesion to activated endothelial cells. In vivo, IRI led to increased expression of cytokines and adhesion molecules at 6 h post-IRI with sustained up-regulated expression to 48 h post-IRI. These effects were attenuated, in part, with BRD4 inhibition. Absolute neutrophil counts increased significantly in the bone marrow, blood, and kidney 24 h post-IRI. Activated neutrophils increased in the blood and kidney at 6 h post-IRI and remained elevated in the kidney until 48 h post-IRI. BRD4 inhibition reduced both total and activated neutrophil counts in the kidney. IRI-induced tubular injury correlated with neutrophil accumulation and was reduced by BRD4 inhibition. In summary, BRD4 inhibition has important systemic and renal effects on neutrophils, and these effects are associated with reduced renal injury.

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.

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.

NLRP3 Inflammasome Activation in Lung Vascular Endothelial Cells Contributes to Intestinal Ischemia/Reperfusion-Induced Acute Lung Injury

Intestinal ischemia/reperfusion (I/R) injury is a life-threatening complication that leads to inflammation and remote organ damage. The NLRP3 inflammasome regulates the caspase-1-dependent release of IL-1β, an early mediator of inflammation after I/R injury. In this study, we investigated the role of the NLRP3 inflammasome in mice with intestinal I/R injury. Deficiency of NLRP3, ASC, caspase-1/11, or IL-1β prolonged survival after intestinal I/R injury, but neither NLRP3 nor caspase-1/11 deficiency affected intestinal inflammation. Intestinal I/R injury caused acute lung injury (ALI) characterized by inflammation, reactive oxygen species generation, and vascular permeability, which was markedly improved by NLRP3 deficiency. Bone marrow chimeric experiments showed that NLRP3 in non-bone marrow-derived cells was the main contributor to development of intestinal I/R-induced ALI. The NLRP3 inflammasome in lung vascular endothelial cells is thought to be important to lung vascular permeability. Using mass spectrometry, we identified intestinal I/R-derived lipid mediators that enhanced NLRP3 inflammasome activation in lung vascular endothelial cells. Finally, we confirmed that serum levels of these lipid mediators were elevated in patients with intestinal ischemia. To our knowledge, these findings provide new insights into the mechanism underlying intestinal I/R-induced ALI and suggest that endothelial NLRP3 inflammasome-driven IL-1β is a novel potential target for treating and preventing this disorder.

Iron overload as a risk factor for hepatic ischemia-reperfusion injury in liver transplantation: Potential role of ferroptosis

Hepatic ischemia-reperfusion (I/R) injury is a major problem in liver transplantation (LT). Although hepatocyte cell death is the initial event in hepatic I/R injury, the underlying mechanism remains unclear. In the present study, we retrospectively analyzed the clinical data of 202 pediatric living donor LT and found that a high serum ferritin level, a marker of iron overload, of the donor is an independent risk factor for liver damage after LT. Since ferroptosis has been recently discovered as an iron-dependent cell death that is triggered by a loss of cellular redox homeostasis, we investigated the role of ferroptosis in a murine model of hepatic I/R injury, and found that liver damage, lipid peroxidation, and upregulation of the ferroptosis marker Ptgs2 were induced by I/R, and all of these manifestations were markedly prevented by the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) or α-tocopherol. Fer-1 also inhibited hepatic I/R-induced inflammatory responses. Furthermore, hepatic I/R injury was attenuated by iron chelation by deferoxamine and exacerbated by iron overload with a high iron diet. These findings demonstrate that iron overload is a novel risk factor for hepatic I/R injury in LT, and ferroptosis contributes to the pathogenesis of hepatic I/R injury.

GSDME-Dependent Incomplete Pyroptosis Permits Selective IL-1α Release under Caspase-1 Inhibition

Pyroptosis is a form of regulated cell death that is characterized by gasdermin processing and increased membrane permeability. Caspase-1 and caspase-11 have been considered to be essential for gasdermin D processing associated with inflammasome activation. In the present study, we found that NLRP3 inflammasome activation induces delayed necrotic cell death via ASC in caspase-1/11-deficient macrophages. Furthermore, ASC-mediated caspase-8 activation and subsequent gasdermin E processing are necessary for caspase-1-independent necrotic cell death. We define this necrotic cell death as incomplete pyroptosis because IL-1β release, a key feature of pyroptosis, is absent, whereas IL-1α release is induced. Notably, unprocessed pro-IL-1β forms a molecular complex to be retained inside pyroptotic cells. Moreover, incomplete pyroptosis accompanied by IL-1α release is observed under the pharmacological inhibition of caspase-1 with VX765. These findings suggest that caspase-1 inhibition during NLRP3 inflammasome activation modulates forms of cell death and permits the release of IL-1α from dying cells.

•

NLRP3 inflammasome induces necrotic cell death in the absence of caspase-1/11

•

ASC initiates GSDME-dependent pyroptosis via caspase-8

•

IL-1α, but not IL-1β, is released during Casp1/11-independent pyroptosis

•

Pharmacological inhibition of caspase-1 permits IL-1α release during pyroptosis

Glucose regulates hypoxia-induced NLRP3 inflammasome activation in macrophages

Although the intimate linkage between hypoxia and inflammation is well known, the mechanism underlying this linkage has not been fully understood. Nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is an intracellular multiprotein complex that regulates interleukin-1β (IL-1β) secretion and pyroptosis, and is implicated in the pathogenesis of sterile inflammatory diseases. Here, we investigated the regulatory mechanism of NLRP3 inflammasome activation in response to hypoxia in macrophages. Severe hypoxia (0.1% O₂ ) induced the processing of pro-IL-1β, pro-caspase-1, and gasdermin D, as well as the release of IL-1β and lactate dehydrogenase in lipopolysaccharide (LPS)-primed murine macrophages, indicating that hypoxia induces NLRP3 inflammasome-driven inflammation and pyroptosis. NLRP3 deficiency and a specific caspase-1 blockade inhibited hypoxia-induced IL-1β release. Hypoxia-induced IL-1β release and cell death were augmented under glucose deprivation, and an addition of glucose in the media negatively regulated hypoxia-induced IL-1β release. Under hypoxia and glucose deprivation, hypoxia-induced glycolysis was not driven and subsequently, the intracellular adenosine triphosphates (ATPs) were depleted. Atomic absorption spectrometry analysis showed a reduction of intracellular K⁺ concentrations, indicating the K⁺ efflux occurring under hypoxia and glucose deprivation. Furthermore, hypoxia and glucose deprivation-induced IL-1β release was significantly prevented by inhibition of K⁺ efflux and K_ATP channel blockers. In vivo experiments further revealed that IL-1β production was increased in LPS-primed mice exposed to hypoxia (9.5% O₂ ), which was prevented by a deficiency of NLRP3, an apoptosis-associated speck-like protein containing a caspase recruitment domain, and caspase-1. Our results demonstrate that NLRP3 inflammasome can sense intracellular energy crisis as a danger signal induced by hypoxia and glucose deprivation, and provide new insights into the mechanism underlying hypoxia-induced inflammation.

Ferroptosis driven by radical oxidation of n-6 polyunsaturated fatty acids mediates acetaminophen-induced acute liver failure

Acetaminophen (APAP) overdose is a common cause of drug-induced acute liver failure. Although hepatocyte cell death is considered to be the critical event in APAP-induced hepatotoxicity, the underlying mechanism remains unclear. Ferroptosis is a newly discovered type of cell death that is caused by a loss of cellular redox homeostasis. As glutathione (GSH) depletion triggers APAP-induced hepatotoxicity, we investigated the role of ferroptosis in a murine model of APAP-induced acute liver failure. APAP-induced hepatotoxicity (evaluated in terms of ALT, AST, and the histopathological score), lipid peroxidation (4-HNE and MDA), and upregulation of the ferroptosis maker PTGS2 mRNA were markedly prevented by the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1). Fer-1 treatment also completely prevented mortality induced by high-dose APAP. Similarly, APAP-induced hepatotoxicity and lipid peroxidation were prevented by the iron chelator deferoxamine. Using mass spectrometry, we found that lipid peroxides derived from n-6 fatty acids, mainly arachidonic acid, were elevated by APAP, and that auto-oxidation is the predominant mechanism of APAP-derived lipid oxidation. APAP-induced hepatotoxicity was also prevented by genetic inhibition of acyl-CoA synthetase long-chain family member 4 or α-tocopherol supplementation. We found that ferroptosis is responsible for APAP-induced hepatocyte cell death. Our findings provide new insights into the mechanism of APAP-induced hepatotoxicity and suggest that ferroptosis is a potential therapeutic target for APAP-induced acute liver failure.

Inhibition of MiR-122 Decreases Cerebral Ischemia-reperfusion Injury by Upregulating DJ-1-Phosphatase and Tensin Homologue Deleted on Chromosome 10 (PTEN)/Phosphonosinol-3 Kinase (PI3K)/AKT

BACKGROUND Ischemia-reperfusion injury is caused by a blood reperfusion injury in ischemic brain tissue, and usually occurs in the treatment stage of ischemic disease, which can aggravate brain tissue injury. MiR-122 is closely related to ischemia-reperfusion injury in the myocardium, kidney, and liver; however, the role in cerebral ischemia-reperfusion injury has not been established. MATERIAL AND METHODS In this study, cerebral ischemia-reperfusion injury was established in a rat model, and the control group was a sham-operated group. After ischemia-reperfusion injury for 6, 12, and 24 hours, brain tissue specimens were collected and the expression of miR-122 and DJ-1 were determined using quantitative real-time polymerase chain reaction. Flow cytometry was used to determine the reactive oxygen species (ROS) content. The modified Neurological Severity Score (mNSS) scale was used to evaluate the sensory and motor function defects of the rats. The malondialdehyde (MDA), superoxide dismutase (SOD), and enzyme activity were determined. The rats in the cerebral ischemia-reperfusion injury model were divided into 2 groups (antagomir-NC group and antagomir miR-122 group). Brain neuron RN-c cells were divided into the following 4 groups: antagomir-NC, antagomir miR-122, pIRES2-blank, and pIRES2-DJ-1. Seventy-two hours after transfection, ischemia-reperfusion treatment was carried out and conventional cultured RN-c cells were used as the control group. Flow cytometry was used to detect apoptosis and western blot was used to detect the expression of DJ-1, PTEN, AKT, and p-AKT. RESULTS The expression of miR-122 increased significantly in the process of ischemia-reperfusion damage after cerebral infarction, while the expression of DJ-1 decreased significantly. Downregulation of miR-122 significantly increased the expression of DJ-1, enhanced the activity of the PTEN/PI3K/AKT pathway, reduced cell apoptosis, and alleviated cerebral ischemia-reperfusion injury. CONCLUSIONS Inhibition of miR-122 can decrease cerebral ischemia-reperfusion injury by upregulating DJ-1-PTEN/PI3K/AKT pathway.

Taurine Alleviates Schistosoma-Induced Liver Injury by Inhibiting the TXNIP/NLRP3 Inflammasome Signal Pathway and Pyroptosis

Schistosomiasis is a parasitic helminth disease that can cause severe inflammatory pathology, leading to organ damage, in humans. During a schistosomal infection, the eggs are trapped in the host liver, and products derived from eggs induce a polarized Th2 cell response, resulting in granuloma formation and eventually fibrosis. Previous studies indicated that the nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is involved in schistosomiasis-associated liver fibrosis and that taurine could ameliorate hepatic granulomas and fibrosis caused by Schistosoma japonicum infection. Nevertheless, the precise role and molecular mechanism of the NLRP3 inflammasome and the protective effects of taurine in S. japonicum infection have not been extensively studied. In this study, we investigated the role of the NLRP3 inflammasome and the hepatoprotective mechanism of taurine in schistosoma-induced liver injury in mice. NLRP3 deficiency ameliorated S. japonicum-infection-induced hepatosplenomegaly, liver dysfunction, and hepatic granulomas and fibrosis; it also reduced NLRP3-dependent liver pyroptosis. Furthermore, taurine suppressed hepatic thioredoxin-interacting protein (TXNIP)/NLRP3 inflammasome activation in mice with S. japonicum infections, thereby inhibiting the activation of downstream inflammatory mediators such as interleukin-1β and subsequent pyroptosis. Our results suggest that the TXNIP/NLRP3 inflammasome pathway and mediating pyroptosis are involved in S. japonicum-induced liver injury and may be a potential therapeutic target for schistosomiasis treatment. In addition, taurine may be useful to alleviate or to prevent the occurrence of schistosomiasis-associated liver fibrosis.

Effect of Beta-Blockade on the Expression of Regulatory MicroRNA after Severe Trauma and Chronic Stress

BACKGROUND

Beta-blockade administration after lung contusion, hemorrhagic shock, and chronic stress has been shown to improve bone marrow function, decrease hypercatecholaminemia, and reduce inflammation. MicroRNAs (miR) are critical biologic regulators that can downregulate gene expression by causing messenger RNA degradation or inhibition of translation. This study sought to expand our understanding of the molecular mechanisms underlying the reduced inflammatory response after the administration of beta-blockade (BB) in our rodent trauma model.

STUDY DESIGN

Male Sprague-Dawley rats aged 8 to 9 weeks were randomized to lung contusion, hemorrhagic shock with daily restraint stress (LCHS/CS) or LCHS/CS plus propranolol (LCHS/CS+BB). Restraint stress occurred 2 hours daily after LCHS. Propranolol (10 mg/kg) was given daily until day 7. Total RNA and miR were isolated from bone marrow and genome-wide miR expression patterns were assayed. Bone marrow cytokine expression was determined with quantitative polymerase chain reaction.

RESULTS

LCHS/CS led to significantly increased bone marrow expression of interleukin (IL) 1β, tumor necrosis factor-α, IL-6, nitric oxide, and plasma C-reactive protein. There were marked differences in expression of 45 miRs in the LCHS/CS+BB group compared with the LCHS/CS group when using a p value <0.001. Rno-miR-27a and miR-25 were upregulated 7- to 8-fold in the rodents who underwent LCHS/CS+BB compared with LCHS/CS alone, and this correlated with reduced bone marrow expression of IL-1β, tumor necrosis factor-α, IL-6, nitric oxide, and reduced plasma C-reactive protein in the LCHS/CS+BB group.

CONCLUSIONS

The genomic and miR expression patterns in bone marrow after LCHS/CS differed significantly compared with rodents that received propranolol after LCHS/CS. The use of BB after severe trauma can help mitigate persistent inflammation by upregulating Rno-miR-27a and miR-25 and reducing inflammatory cytokines in those who remain critically ill.

Role of TLR5 in inflammation and tissue damage after intestinal ischemia-reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury is a life-threatening complication that leads to inflammation and remote organ damage. However, the underlying mechanism is not yet fully understood. Toll-like receptor 5 (TLR5) is highly expressed in mucosa and recognizes flagellin, the main component of the bacterial flagella. Here, we investigated the role of TLR5 in inflammation and tissue damage after intestinal I/R injury using TLR5-deficient mice.

METHODS AND RESULTS

Intestinal levels of TLR5 mRNA and flagellin protein were elevated in wild-type mice subjected to intestinal I/R. Although TLR5 deficiency had no effect on intestinal flagellin levels, it significantly attenuated intestinal injury and inflammatory responses after intestinal I/R. TLR5 deficiency also markedly improved survival in mice after intestinal I/R injury. In wild-type mice, intestinal I/R injury induced remote organ damage, particularly in the lung, which was attenuated by TLR5 deficiency. Furthermore, TLR5 deficiency prevented lung inflammatory responses and vascular permeability after intestinal I/R injury.

CONCLUSION

These findings demonstrate a novel role of TLR5 and provide new insights into the mechanism underlying inflammation and tissue damage after intestinal I/R injury.

Interleukin-1 Family Cytokines: Keystones in Liver Inflammatory Diseases

The pyrogenic property being the first activity described, members of the interleukin-1 superfamily (IL-1α, IL-1β, IL-18, and the newest members: IL-33, IL-36, IL-37, and IL-38) are now known to be involved in several inflammatory diseases such as obesity, atherosclerosis, cancer, viral and parasite infections, and auto-inflammatory syndromes as well as liver diseases. Inflammation processes are keystones of chronic liver diseases, of which the etiology may be viral or toxic, as in alcoholic or non-alcoholic liver diseases. Inflammation is also at stake in acute liver failure involving massive necrosis, and in ischemia-reperfusion injury in the setting of liver transplantation. The role of the IL-1 superfamily of cytokines and receptors in liver diseases can be either protective or pro-inflammatory, depending on timing and the environment. Our review provides an overview of current understanding of the IL-1 family members in liver inflammation, highlighting recent key investigations, and therapeutic perspectives. We have tried to apply the concept of trained immunity to liver diseases, based on the role of the members of the IL-1 superfamily, first of all IL-1β but also IL-18 and IL-33, in modulating innate lymphoid immunity carried by natural killer cells, innate lymphoid cells or innate T-αβ lymphocytes.

Pro-inflammatory role of NLRP3 inflammasome in experimental sterile corneal inflammation

We evaluated the role of NLR family pyrin domain containing 3 (NLRP3) inflammasome in sterile corneal inflammation caused by lipopolysaccharide (LPS) or alkali burns in C57BL6 mice or NLRP3 KO (Nlrp3^−/−) mice. Various molecules related to the NLRP3 inflammasome were upregulated in C57BL6 mice after both alkali burn injury and LPS treatment. After alkali burn injury, the corneal opacity grade was significantly reduced in Nlrp3^−/− mice compared with C57BL6 mice. In Nlrp3^−/− mice, Gr-1 immunoreactivity and MMP-9 mRNA expression in the corneal stroma were significantly reduced by both LPS treatment and alkali burn injury. Quantitative PCR and immunohistochemistry revealed that IL-1β and MMP-9 expression in the corneal stroma were down-regulated in Nlrp3^−/− mice with both alkali burn injury and LPS treatment. These findings suggest that the NLRP3 inflammasome has a pro-inflammatory effect in the cornea by recruiting neutrophils to sites of inflammation.

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.

Clinical relevance of lung-restricted antibodies in lung transplantation

Lung transplant is a definitive treatment for several end-stage lung diseases. However, the high incidence of allograft rejection limits the overall survival following lung transplantation. Traditionally, alloimmunity directed against human leukocyte antigens (HLA) has been implicated in transplant rejection. Recently, the clinical impact of non-HLA lung-restricted antibodies (LRA) has been recognized and extensive research has demonstrated that they may play a dominant role in the development of lung allograft rejection. The immunogenic lung-restricted antigens that have been identified include amongst others, collagen type I, collagen type V, and k-alpha 1 tubulin. Pre-existing antibodies against these lung-restricted antigens are prevalent in patients undergoing lung transplantation and have emerged as one of the predominant risk factors for primary graft dysfunction which limits short-term survival following lung transplantation. Additionally, LRA have been shown to predispose to chronic lung allograft rejection, the predominant cause of poor long-term survival. This review will discuss ongoing research into the mechanisms of development of LRA as well as the pathogenesis of associated lung allograft injury.

Evaluation of prognostic values of inflammation-based makers in patients with HBV-related acute-on-chronic liver failure

Systemic inflammatory responses are associated with the development and progression of liver failure. Neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), prognostic nutritional index (PNI), red cell distribution width (RDW), RDW-to platelet ratio (RPR), mean platelet volume (MPV), and MPV-to platelet ratio (MPR) are markers of systemic inflammation. This study aimed to evaluate the prognostic values of these inflammatory markers in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF).203 HBV-ACLF patients, 79 cirrhosis patients (LC), 63 chronic hepatitis B (CHB), and 81 healthy subjects (HS) participated in this cohort study. Complete blood counts and biochemical examinations were obtained after overnight fasting. Multivariate analyses of 90-day outcome predictors were analyzed by Cox regression models. Survival probability curves were calculated by the Kaplan-Meier method.The levels of NLR, MLR, RDW, MPV, RPR, and MPR were significantly higher and PNI was lower in patients with liver failure at presentation compared to those in LC, CHB, and HS (P <.001). In acute-on-chronic liver failure (ACLF) patients, NLR and MLR were higher in nonsurvivors than in survivors (P <.001), while other inflammatory markers showed no difference. ROC curve analyses showed that NLR combined with MLR had the highest AUC for identified poor outcome, followed by NLR, chronic liver failure-sequential organ failure assessment (CLIF-SOFA), MLR, model for end-stage liver disease (MELD), Child-Turcotte-Pugh (CTP) and TBIL. Multivariate analyses showed that TBIL, NLR, CTP, MELD, and CLIF-SOFA were independent predictors for 90-day mortality.Combination of NLR and MLR are more accurate prognostic markers for predicting poor outcome than either marker alone in ACLF patients. And this combination is superior to the CLIF-SOFA, MELD, CTP score, and TBIL in terms of prognostic ability.

Sevoflurane relieves hepatic ischemia-reperfusion injury by inhibiting the expression of Grp78

Purpose: This article aimed to study the role of sevoflurane pre-conditioning in hepatic ischemia–reperfusion and its potential mechanism.

Methods: Rat liver ischemia–reperfusion model was constructed. Serum TNF-α, IL-1β, IL-10, and IL-6 concentrations were detected by ELISA. Malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO) in liver homogenate were determined. Hematoxylin–Eosin (HE) staining, Tunel, and immunohistochemistry were performed. Ischemia–reperfusion hepatocyte model was established. Cells transfection was conducted. Apoptosis was observed by flow cytometry. Quantitative real-time PCR (qRT-PCR) and Western blotting analysis were used.

Results: Compared with I/R group, liver damage degree, liver cell apoptosis, and glucose regulatory protein 78 (Grp78) expression was obviously reduced in rats of SEV group. TNF-α, IL-1β, and IL-6 concentrations were also significantly increased (P<0.01). MDA and NO concentrations were dramatically lower (P<0.01) and SOD concentration was significantly higher (P<0.01). Apoptosis rate, Grp78, PERK, eIF2α, and p-c-JNK/JNK expression was also significantly decreased (P<0.01). Sevoflurane significantly reduced apoptosis and expression of PERK, eIF2α, p-c-JNK/JNK by inhibiting the expression of Grp78 (P<0.01).

Conclusion: Sevoflurane relieves hepatic ischemia–reperfusion injury by inhibiting the expression of Grp78.

IL-1β activation in response to Staphylococcus aureus lung infection requires inflammasome-dependent and independent mechanisms

Maintaining balanced levels of IL-1β is extremely important to avoid host tissue damage during infection. Our goal was to understand the mechanisms behind the reduced pathology and decreased bacterial burdens in Ifnlr1^-/- mice during lung infection with Staphylococcus aureus. Intranasal infection of Ifnlr1^-/- mice with S. aureus led to significantly improved bacterial clearance, survival and decrease of proinflammatory cytokines in the airway including IL-1β. Ifnlr1^-/- mice treated with recombinant IL-1β displayed increased bacterial burdens in the airway and lung. IL-1β levels in neutrophils from Ifnlr1^-/- infected mice lungs were decreased when compared to neutrophils from WT mice. Mice lacking NLRP3 and caspase-1 had reduced IL-1β levels 4 h after infection, due to reductions or absence of active caspase-1 respectively, but levels at 24 h were comparable to WT infected mice. Ifnlr1^-/- infected mice had decreases in both active caspase-1 and neutrophil elastase indicating an important role for the neutrophil serine protease in IL-1β processing. By inhibiting neutrophil elastase, we were able to decrease IL-1β levels by 39% in Nlrp3^-/- infected mice when compared to WT mice. These results highlight the crucial role of both proteases in IL-1β processing, via inflammasome-dependent and -independent mechanisms.

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.

IL-35 is a Protective Immunomodulator in Brain Ischemic Injury in Mice

IL-35 has been identified as a novel anti-inflammatory cytokine that belongs to the IL-12 cytokine family and has been verified to play a protective role in autoimmune diseases. In this study, we investigated the protective effects of IL-35 on cerebral ischemia/reperfusion (I/R) injury in a middle cerebral artery occlusion mouse model. We determined that the expression of IL-35 was initially decreased and subsequently increased in I/R injury. Moreover, IL-35 (i.c.v.) pre- and posttreatment significantly reduced the infarct volume and improved neurological deficits after 45 min of ischemia and 24 h of reperfusion. Importantly, IL-35 treatment improved neurological function recovery, particularly in balance ability, at 14 days after treatment. Finally, our results showed that IL-35 treatment reduced the expression of IL-6 and IL-1β, which are confirmed proinflammatory cytokines, thus indicating that these cytokines have both been linked to the anti-inflammatory mechanisms of IL-35. Therefore, IL-35 may be a key immune mediator in brain ischemic injury and appears to have promising potential for clinical trials.

Circular RNAs are differentially expressed in liver ischemia/reperfusion injury model

Liver ischemia/reperfusion (I/R) injury has high mortality due to the intense inflammatory process occurs in the liver. However, the pathological mechanism underlying I/R injury is still not clear. Recent works showed that circular RNAs play critical roles in many human diseases. In this study, the occurrence of liver I/R injury was validated by an analysis of the blood samples and hematoxylin-eosin (HE) staining of liver tissues. Total RNA was purified and followed by RNA-seq in the purpose of screening the circRNAs in significant differentially expression, which were validated by quantitative PCR. GO and KEGG analysis were performed to determine the function of these differentially expressed circular RNAs. The circular structure of the circRNA was validated with gel electrophoresis and RNase R treatment. We found that some circular RNAs were differentially expressed in Liver I/R mouse models through bioinformatics analysis. These circular RNAs play roles in biological process, cellular component, and molecular function through GO analysis. Meanwhile, Hippo signaling pathway was found to be correlated with circular RNAs function in I/R models by KEGG analysis. To further validate bioinformatics data, two up-regulated and three down-regulated circular RNAs were confirmed in I/R models. The circularity of these differentially expressed circular RNAs was validated through gel electrophoresis and RNase R treatment. In summary, this work provides new insights into the mechanism underlying pathogenesis of liver I/R injury, providing new and potentially efficient targets against I/R injury.

Dunye Guanxinning Improves Acute Myocardial Ischemia-Reperfusion Injury by Inhibiting Neutrophil Infiltration and Caspase-1 Activity

Acute myocardial infarction is the most serious manifestation of cardiovascular disease, and it is a life-threatening condition. Dunye Guanxinning (DG) is a protective traditional Chinese patent herbal medicine with high clinical efficacy and suitable for the treatment of myocardial infarction. However, the mechanism through which it is beneficial is unclear. In this study, we hypothesized that DG improves acute myocardial ischemia-reperfusion injury by inhibiting neutrophil infiltration and caspase-1 activity. We found that DG administration decreased infarct size and cardiomyocyte apoptosis and improved left ventricular ejection fraction, fractional shortening, end-systolic volume index, end-systolic diameter, and carotid arterial blood flow output in rats. DG administration also improved hemorheological parameters, myocardial damage biomarkers, and oxidative stress indexes. The findings showed that DG administration inhibited neutrophil infiltration and reduced the serum interleukin-1 beta (IL-1β) level and myocardial IL-1β maturation. Moreover, DG administration inhibited caspase-1 activity and activated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in rat hearts. These results suggested that DG administration inhibits inflammasome activity and IL-1β release through the AMPK pathway. Our findings support the clinical efficacy of DG and partially reveal its mechanism, which is beneficial for understanding the therapeutic effects of this protective traditional Chinese patent drug.