Repressor and activator protein accelerates hepatic ischemia reperfusion injury by promoting neutrophil inflammatory response

Terf2ip deficiency accelerates non-alcoholic steatohepatitis through regulating lipophagy and fatty acid oxidation via Sirt1/AMPK pathway

BACKGROUND & AIMS

Our previous study has demonstrated that Telomeric repeat-binding factor 2-interacting protein 1(Terf2ip), played an important role in hepatic ischemia reperfusion injury. This study is aimed to explore the function and mechanism of Terf2ip in non-alcoholic steatohepatitis (NASH).

METHODS

The expression of Terf2ip was detected in liver tissue samples obtained from patients diagnosed with NASH. Mice NASH models were constructed by fed with high-fat diet (HFD) or methionine/choline deficient diet (MCD) in Terf2ip knockout and wild type (WT) mice. To further investigate the role of Terf2ip in NASH, adeno-associated viruses (AAV)-Terf2ip was administrated to mice.

RESULTS

We observed a significant down-regulation of Terf2ip levels in the livers of NASH patients and mice NASH models. Terf2ip deficiency was associated with an exacerbation of hepatic steatosis in mice under HFD or MCD. Additionally, Terf2ip deficiency impaired lipophagy and fatty acid oxidation (FAO) in NASH models. Mechanically, we discovered that Terf2ip bound to the promoter region of Sirt1 to regulate Sirt1/AMPK pathway activation. As a result, Terf2ip deficiency was shown to inhibit lipophagy through the AMPK pathway, while the activation of Sirt1 alleviated steatohepatitis in the livers of mice. Finally, re-expression of Terf2ip in hepatocyes alleviated liver steatosis, inflammation, and restored lipophagy.

CONCLUSIONS

These results revealed that Terf2ip played a protective role in the progression of NASH through regulating lipophagy and FAO by binding to Sirt1 promoter. Our findings provided a potential therapeutic target for the treatment of NASH.

Application of a novel artificial perfusate based on oxygen-carrying nanoparticles in normothermic machine perfusion for porcine liver preservation after cardiac death

OBJECTIVE

To investigate the efficacy of a novel artificial perfusate based on oxygen-carrying perfluoronaphthalene-albumin nanoparticles in normothermic machine perfusion (NMP) for preservation of porcine liver donation after cardiac death.

METHODS

Artificial perfusate with perfluoronaphthalene-albumin nanoparticles was prepared at 5% albumin (w/v) and its oxygen carrying capacity was calculated. The livers of 16 Landrace pigs were isolated after 1 h of warm ischemia, and then they were divided into 4 groups and preserved continuously for 24 h with different preservation methods: cold preservation with UW solution (SCS group), NMP preservation by whole blood (blood NMP group), NMP preservation by artificial perfusate without nanoparticles (non-nanoparticles NMP group) and NMP preservation by artificial perfusate containing nanoparticles (nanoparticles NMP group). Hemodynamics, tissue metabolism, biochemical indices of perfusate and bile were monitored every 4 h after the beginning of NMP. Liver tissue samples were collected for histological examination (HE and TUNEL staining) before preservation, 12 h and 24 h after preservation.

RESULTS

The oxygen carrying capacity of nanoparticles in 100 mL artificial perfusate was 6.94 μL/mmHg (1 mmHg=0.133 kPa). The hepatic artery and portal vein resistance of nanoparticles NMP group and blood NMP group remained stable during perfusion, and the vascular resistance of nanoparticles NMP group was lower than that of blood NMP group. The concentration of lactic acid in the perfusate decreased to the normal range within 8 h in both nanoparticles NMP group and blood NMP group. There were no significant differences in accumulated bile production, alanine aminotransferase and aspartate aminotransferase in perfusate between nanoparticles NMP group and blood NMP group (all P>0.05). After 24 h perfusion, the histological Suzuki score in blood NMP group and nanoparticles NMP group was lower than that in SCS group and non-nanoparticles NMP group (all P<0.05), and the quantities of TUNEL staining positive cells in blood NMP group and non-nanoparticles NMP group was higher than those in nanoparticles NMP group and SCS group 12 h and 24 h after preservation (all P<0.05).

CONCLUSION

Artificial perfusate based on oxygen-carrying nanoparticles can meet the oxygen supply requirements of porcine livers donation after cardiac death during NMP preservation, and it may has superiorities in improving tissue microcirculation and alleviating ischemia-reperfusion injury.

New Insights in Mechanisms and Therapeutics for Short- and Long-Term Impacts of Hepatic Ischemia Reperfusion Injury Post Liver Transplantation

Liver transplantation has been identified as the most effective treatment for patients with end-stage liver diseases. However, hepatic ischemia reperfusion injury (IRI) is associated with poor graft function and poses a risk of adverse clinical outcomes post transplantation. Cell death, including apoptosis, necrosis, ferroptosis and pyroptosis, is induced during the acute phase of liver IRI. The release of danger-associated molecular patterns (DAPMs) and mitochondrial dysfunction resulting from the disturbance of metabolic homeostasis initiates graft inflammation. The inflammation in the short term exacerbates hepatic damage, leading to graft dysfunction and a higher incidence of acute rejection. The subsequent changes in the graft immune environment due to hepatic IRI may result in chronic rejection, cancer recurrence and fibrogenesis in the long term. In this review, we mainly focus on new mechanisms of inflammation initiated by immune activation related to metabolic alteration in the short term during liver IRI. The latest mechanisms of cancer recurrence and fibrogenesis due to the long-term impact of inflammation in hepatic IRI is also discussed. Furthermore, the development of therapeutic strategies, including ischemia preconditioning, pharmacological inhibitors and machine perfusion, for both attenuating acute inflammatory injury and preventing late-phase disease recurrence, will be summarized in the context of clinical, translational and basic research.

SLX4IP promotes RAP1 SUMOylation by PIAS1 to coordinate telomere maintenance through NF-κB and Notch signaling

The maintenance of telomere length supports repetitive cell division and therefore plays a central role in cancer development and progression. Telomeres are extended by either the enzyme telomerase or the alternative lengthening of telomeres (ALT) pathway. Here, we found that the telomere-associated protein SLX4IP dictates telomere proteome composition by recruiting and activating the E3 SUMO ligase PIAS1 to the SLX4 complex. PIAS1 SUMOylated the telomere-binding protein RAP1, which disrupted its interaction with the telomere-binding protein TRF2 and facilitated its nucleocytoplasmic shuttling. In the cytosol, RAP1 bound to IκB kinase (IKK), resulting in activation of the transcription factor NF-κB and its induction of Jagged-1 expression, which promoted Notch signaling and the institution of ALT. This axis could be targeted therapeutically in ALT-driven cancers and in tumor cells that develop resistance to antitelomerase therapies. Our results illuminate the mechanisms underlying SLX4IP-dependent telomere plasticity and demonstrate the role of telomere proteins in directly coordinating intracellular signaling and telomere maintenance dynamics.

The Study on the Mechanism of Hugan Tablets in Treating Drug-Induced Liver Injury Induced by Atorvastatin

Atorvastatin is a widely used lipid-lowering drug in the clinic. Research shows that taking long-term atorvastatin has the risk of drug-induced liver injury (DILI) in most patients. Hugan tablets, a commonly used drug for liver disease, can effectively lower transaminase and protect the liver. However, the underlying mechanism of Hugan tablets alleviating atorvastatin-induced DILI remains unclear. To address this problem, comprehensive chemical profiling and network pharmacology methods were used in the study. First, the strategy of “compound−single herb−TCM prescription” was applied to characterize the ingredients of Hugan tablets. Then, active ingredients and potential targets of Hugan tablets in DILI treatment were screened using network pharmacology, molecular docking, and literature research. In the end, the mechanism of Hugan tablets in treating atorvastatin-induced DILI was elucidated. The results showed that Hugan tablets can effectively alleviate DILI induced by atorvastatin in model rats, and 71 compounds were characterized from Hugan tablets. Based on these compounds, 271 potential targets for the treatment of DILI were predicted, and 10 key targets were chosen by characterizing protein–protein interactions. Then, 30 potential active ingredients were screened through the molecular docking with these 10 key targets, and their biological activity was explained based on literature research. Finally, the major 19 active ingredients of Hugan tablets were discovered. In addition, further enrichment analysis of 271 targets indicated that the PI3K-Akt, TNF, HIF-1, Rap1, and FoxO signaling pathways may be the primary pathways regulated by Hugan tablets in treating DILI. This study proved that Hugan tablets could alleviate atorvastatin-induced DILI through multiple components, targets, and pathways.

Rap1a Overlaps the AGE/RAGE Signaling Cascade to Alter Expression of α-SMA, p-NF-κB, and p-PKC-ζ in Cardiac Fibroblasts Isolated from Type 2 Diabetic Mice

Cardiovascular disease, specifically heart failure, is a common complication for individuals with type 2 diabetes mellitus. Heart failure can arise with stiffening of the left ventricle, which can be caused by “active” cardiac fibroblasts (i.e., myofibroblasts) remodeling the extracellular matrix (ECM). Differentiation of fibroblasts to myofibroblasts has been demonstrated to be an outcome of AGE/RAGE signaling. Hyperglycemia causes advanced glycated end products (AGEs) to accumulate within the body, and this process is greatly accelerated under chronic diabetic conditions. AGEs can bind and activate their receptor (RAGE) to trigger multiple downstream outcomes, such as altering ECM remodeling, inflammation, and oxidative stress. Previously, our lab has identified a small GTPase, Rap1a, that possibly overlaps the AGE/RAGE signaling cascade to affect the downstream outcomes. Rap1a acts as a molecular switch connecting extracellular signals to intracellular responses. Therefore, we hypothesized that Rap1a crosses the AGE/RAGE cascade to alter the expression of AGE/RAGE associated signaling proteins in cardiac fibroblasts in type 2 diabetic mice. To delineate this cascade, we used genetically different cardiac fibroblasts from non-diabetic, diabetic, non-diabetic RAGE knockout, diabetic RAGE knockout, and Rap1a knockout mice and treated them with pharmacological modifiers (exogenous AGEs, EPAC, Rap1a siRNA, and pseudosubstrate PKC-ζ). We examined changes in expression of proteins implicated as markers for myofibroblasts (α-SMA) and inflammation/oxidative stress (NF-κB and SOD-1). In addition, oxidative stress was also assessed by measuring hydrogen peroxide concentration. Our results indicated that Rap1a connects to the AGE/RAGE cascade to promote and maintain α-SMA expression in cardiac fibroblasts. Moreover, Rap1a, in conjunction with activation of the AGE/RAGE cascade, increased NF-κB expression as well as hydrogen peroxide concentration, indicating a possible oxidative stress response. Additionally, knocking down Rap1a expression resulted in an increase in SOD-1 expression suggesting that Rap1a can affect oxidative stress markers independently of the AGE/RAGE signaling cascade. These results demonstrated that Rap1a contributes to the myofibroblast population within the heart via AGE/RAGE signaling as well as promotes possible oxidative stress. This study offers a new potential therapeutic target that could possibly reduce the risk for developing diabetic cardiovascular complications attributed to AGE/RAGE signaling.

Characteristics of Changes in Inflammatory Cytokines as a Function of Hepatic Ischemia-Reperfusion Injury Stage in Mice

Liver ischemia-reperfusion injury (IRI) can severely compromise the prognosis of patients receiving liver surgery. While inflammation contributes to the damage resulting from IRI, only a limited number of inflammation biomarkers have been identified as being associated with the different stages of hepatic IRI. As an approach to identify some of these inflammatory cytokines and the molecular mechanisms involved within different stages of hepatic IRI, we used an advanced antibody array assay to detect multiple proteins. With this technology, we observed specific differences in the content of inflammatory cytokines between ischemic and sham controls, as well as a function of the different reperfusion stages in a hepatic IRI mouse model. For example, while liver tissue content of IL-12p40/p70 was significantly increased in the ischemic stage, it was significantly decreased in the reperfusion stage as compared with that of the sham group. For other inflammatory cytokines, no changes were obtained between the ischemic and reperfusion stages with levels of IL-17, Eotaxin-2, Eotaxin, and sTNF RII all being consistently increased, while those of TIMP-1, TIMP-2, BLC, and MCSF consistently decreased as compared with that of the sham group at all reperfusion stages examined. Results from protein function annotation Gene Ontology and the KEGG pathway revealed that inflammatory cytokines are enriched in a network associated with activation of inflammatory response signaling pathways such as TLR, TNF, and IL-17 when comparing responses of the IR versus sham groups. The identification of cytokines along with their roles at specific stages of IRI may reveal important new biological markers for the diagnosis and prognosis of hepatic IRI.

Deletion of Rap1 protects against myocardial ischemia/reperfusion injury through suppressing cell apoptosis via activation of STAT3 signaling

Ischemic heart disease is a leading cause of morbidity and mortality. Repressor activator protein 1 (Rap1), an established telomere-associated protein, is a novel modulator of hypoxia-induced apoptosis. This study aimed to explore the potential direct role of Rap1 in myocardial ischemia/reperfusion injury (I/RI) and to determine the underlying molecular mechanism. In a mouse model of myocardial I/RI (30-min of left descending coronary artery ligation followed by 2-h reperfusion), Rap1 deficiency significantly reduced myocardial infarct size (IS) and improved cardiac systolic/diastolic function. This was associated with a reduction in apoptosis in the post-ischemic myocardium. In H9C2 and primary cardiomyocytes, Rap1 knockdown or knockout significantly suppressed hypoxia/reoxygenation (H/R)-induced cell injury and apoptosis through increasing the phosphorylation/activation of STAT3 at site Ser⁷²⁷ and translocation of STAT3 to the nucleus. We surmise this since Stattic (selective STAT3 inhibitor) pretreatment canceled the abovementioned protective effect. Furthermore, co-immunoprecipitation assay revealed a direct interaction between Rap1 and STAT3, but not JAK2, suggesting that the association of Rap1 with STAT3 may contribute to the reduced activity of STAT3 (Ser⁷²⁷ ) upon H/R stimulation. In conclusion, Rap1 deficiency protects the heart from ischemic damage through STAT3-dependent reduction of cardiomyocyte apoptosis, which may yield viable target for pharmacological intervention in ischemic heart disease.

Capsaicin inhibits the migration and invasion via the AMPK/NF-κB signaling pathway in esophagus sequamous cell carcinoma by decreasing matrix metalloproteinase-9 expression

Antitumor activity of Capsaicin has been studied in various tumor types, but its potency in esophageal squamous cell carcinoma (ESCC) remains to be elucidated. Here, we explored the molecular mechanism of the capsaicin-induced antitumor effects on ESCC Eca109 cells. Eca109 cells were treated with capsaicin in vitro, the migration and invasion capacities were significantly decreased by scratch assay and transwell invasion assay. Meanwhile, matrix metalloproteinase (MMP)-9 (MMP-9) expression levels were also obviously down-regulated by Western blot. However, phosphorylated AMPK levels were significantly up-regulated, and this effect was eliminated by the AMPK inhibitor Compound C treatment. In addition, capsaicin can enhance sirtuin1 (SIRT1) expression, which could activate nuclear factor-κB (NF-κB) through deacetylation, and activate AMPK inducing the phosphorylation of IκBα and nuclear localization of NF-κB p65. Overall, these results revealed that Capsaicin can inhibit the migration and invasion of ESCC cells via the AMPK/NF-κB signaling pathway.

Anti-aging effects exerted by Tetramethylpyrazine enhances self-renewal and neuronal differentiation of rat bMSCs by suppressing NF-kB signaling

In order to improve the therapeutic effects of mesenchymal stem cell (MSC)-based therapies for a number of intractable neurological disorders, a more favorable strategy to regulate the outcome of bone marrow MSCs (bMSCs) was examined in the present study. In view of the wide range of neurotrophic and neuroprotective effects, Tetramethylpyrazine (TMP), a biologically active alkaloid isolated from the herbal medicine Ligusticum wallichii, was used. It was revealed that treatment with 30–50 mg/l TMP for 4 days significantly increased cell viability, alleviated senescence by suppressing NF-κB signaling, and promoted bMSC proliferation by regulating the cell cycle. In addition, 40–50 mg/l TMP treatment may facilitate the neuronal differentiation of bMSCs, verified in the present study by presentation of neuronal morphology and expression of neuronal markers: microtubule-associated protein 2 (MAP-2) and neuron-specific enolase (NSE). The quantitative real-time polymerase chain reaction (qRT-PCR) revealed that TMP treatment may promote the expression of neurogenin 1 (Ngn1), neuronal differentiation 1 (NeuroD) and mammalian achaete–scute homolog 1 (Mash1). In conclusion, 4 days of 40–50 mg/l TMP treatment may significantly delay bMSC senescence by suppressing NF-κB signaling, and enhancing the self-renewal ability of bMSCs, and their potential for neuronal differentiation.

MicroRNA profiling of mouse liver in response to DENV-1 infection by deep sequencing

BACKGROUND

Dengue caused by dengue virus (DENV) serotypes -1 to -4 is the most important mosquito-borne viral disease in the tropical and sub-tropical countries worldwide. Yet many of the pathophysiological mechanisms of host responses during DENV infection remain largely unknown and incompletely understood.

METHODS

Using a mouse model, the miRNA expressions in liver during DENV-1 infection was investigated using high throughput miRNA sequencing. The differential expressions of miRNAs were then validated by qPCR, followed by target genes prediction. The identified miRNA targets were subjected to gene ontology (GO) annotation and pathway enrichment analysis to elucidate the potential biological pathways and molecular mechanisms associated with DENV-1 infection.

RESULTS

A total of 224 and 372 miRNAs out of 433 known mouse miRNAs were detected in the livers of DENV-1-infected and uninfected mice, respectively; of these, 207 miRNAs were present in both libraries. The miR-148a-3p and miR-122-5p were the two most abundant miRNAs in both groups. Thirty-one miRNAs were found to have at least 2-fold change in upregulation or downregulation, in which seven miRNAs were upregulated and 24 miRNAs were downregulated in the DENV-1-infected mouse livers. The miR-1a-3p was found to be the most downregulated miRNA in the DENV-1-infected mouse livers, with a significant fold change of 0.10. To validate the miRNA sequencing result, the expression pattern of 12 miRNAs, which were highly differentially expressed or most abundant, were assessed by qPCR and nine of them correlated positively with the one observed in deep sequencing. In silico functional analysis revealed that the adaptive immune responses involving TGF-beta, MAPK, PI3K-Akt, Rap1, Wnt and Ras signalling pathways were modulated collectively by 23 highly differentially expressed miRNAs during DENV-1 infection.

CONCLUSION

This study provides the first insight into the global miRNA expressions of mouse livers in response to DENV-1 infection in vivo and the possible roles of miRNAs in modulating the adaptive immune responses during DENV-1 infection.

Transcriptome Analysis of Acute Phase Liver Graft Injury in Liver Transplantation

BACKGROUND

Liver transplantation remains the treatment of choice for a selected group of hepatocellular carcinoma (HCC) patients. However, the long-term benefit is greatly hampered by post-transplant HCC recurrence. Our previous studies have identified liver graft injury as an acute phase event leading to post-transplant tumor recurrence.

METHODS

To re-examine this acute phase event at the molecular level and in an unbiased way, RNA sequencing (RNA-Seq) was performed on liver graft biopsies obtained from the transplant recipients two hours after portal vein reperfusion with an aim to capture frequently altered pathways that account for post-transplant tumor recurrence. Liver grafts from recurrent recipients (n = 6) were sequenced and compared with those from recipients without recurrence (n = 5).

RESULTS

RNA expression profiles comparison pointed to several frequently altered pathways, among which pathways related to cell adhesion molecules were the most involved. Subsequent validation using quantitative polymerase chain reaction confirmed the differential involvement of two cell adhesion molecules HFE (hemochromatosis) and CD274 and their related molecules in the acute phase event.

CONCLUSION

This whole transcriptome strategy unravels the molecular landscape of liver graft gene expression alterations, which can identify key pathways and genes that are involved in acute phase liver graft injury that may lead to post-transplant tumor recurrence.

Glutathione Peroxidase 3 Delivered by hiPSC-MSCs Ameliorated Hepatic IR Injury via Inhibition of Hepatic Senescence

Background and Aims: Down-regulation of GPx3 accelerated hepatic senescence, which further caused overwhelming inflammation and severe liver graft injury. MSCs derived from human induced pluripotent stem cells (hiPSC-MSCs) have been developed as more efficient delivery vehicle with the property of injury tropism. Here, we aimed to explore the suppressive role of GPx3 in hepatic IR injury using novel delivery system of hiPSC-MSCs.

Methods: The mice IR injury model with partial hepatectomy was established. The engineered hiPSC-MSCs delivering GPx3 was constructed. All the mice were segregated into three groups. hiPSC-MSC-GPx3, hiPSC-MSC-pCDH (vector control) or PBS were injected via portal vein after reperfusion. Liver injury was evaluated by histological and serological test. Hepatic apoptosis was detected by Tunel staining and remnant liver regeneration was assessed by Ki67 staining. The role of hepatic senescence in liver graft injury was evaluated in rat orthotopic liver transplantation model. The suppressive effect of GPx3 on hepatic senescence was examined in mice IR injury model and confirmed in vitro. Hepatic senescence was detected by SA-β-Gal and P^16/ink4a staining.

Results: GPx3 can be successfully delivered by hiPSC-MSCs into liver tissues. Histological examination showed that hiPSC-MSC-GPx3 treatment significantly ameliorated hepatic IR injury post-operation. Significantly lower LDH (891.43±98.45 mU/mL, P<0.05) and AST (305.77±36.22 IU/L, P<0.01) were observed in hiPSC-MSC-GPx3 group compared with control groups. Less apoptotic hepatocytes were observed and the remnant liver regeneration was more active in hiPSC-MSC-GPx3 group. In rat orthotopic liver transplantation model, more senescent hepatocytes were observed in small-for-size liver graft, in which GPx3 expression was significantly compromised. In mice IR injury model, hiPSC-MSC-GPx3 significantly suppressed hepatic senescence. In addition, rGPx3 inhibited cellular senescence of liver cells in a dose dependent manner. Four candidate genes (CD44, Nox4, IFNG, SERPERINB2) were identified to be responsible for suppressive effect of GPx3 on hepatic senescence.

Conclusion: Engineered hiPSC-MSCs delivering GPx3 ameliorated hepatic IR injury via inhibition of hepatic senescence.

Screening circular RNA expression patterns following focal cerebral ischemia in mice

Circular RNAs (circRNAs) have been demonstrated to act as microRNA (miRNA) sponges and they play important roles in regulating gene expression through a circRNA-miRNA-gene pathway. The specific roles of circRNAs in the pathogenesis of cerebral ischemia, however, are still unclear. Thus, the aim of this study is to determine circRNA expression profiles in the ischemic brain after stroke, which was induced by 45 min of transient middle cerebral artery occlusion (MCAO). The results from the circRNA microarrays revealed that 1027 circRNAs were significantly altered 48 hours after reperfusion in the ischemic brain compared with the sham group. Among them, 914 circRNAs were significantly upregulated, and the remaining 113 were significantly downregulated. In addition, the expressions of the three selected circRNAs, mmu_circRNA_40001, mmu_circRNA_013120, and mmu_circRNA_40806, were verified using quantitative real-time polymerase chain reaction (qRT-PCR). After predicting their target genes, the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses were further used to predict the associated significant cell signaling pathways and functions. The results show that the most enriched pathways are associated with the Rap1 signaling pathway and the Hippo signaling pathway, which regulate cell survival and death. Finally, we constructed an interaction network of circRNA-miRNA-target genes, including 13 miRNAs and their corresponding genes, indicating that changes in circRNA are associated with genes related with brain injury and recovery. In conclusion, circRNAs are complicated in the pathological development of brain injury after stroke, suggesting novel diagnostic and therapeutic targets for stroke therapy.

Decoding telomere protein Rap1: Its telomeric and nontelomeric functions and potential implications in diabetic cardiomyopathy

Mammalian Rap1, the most conserved telomere-interacting protein, beyond its role within nucleus for the maintenance of telomeric functions, is also well known for its pleiotropic functions in various physiological and pathological conditions associated with metabolism, inflammation and oxidative stress. For all these, nowadays Rap1 is the subject of critical investigations aimed to unveil its molecular signaling pathways and to scrutinize the applicability of its modulation as a promising therapeutic strategy with clinical relevance. However, the underlying intimate mechanisms of Rap1 are not extensively studied, but any modulation of this protein level has been associated with pathologies like inflammation, oxidative stress and deregulated metabolism. This is considerably important in light of the recent discovery of Rap1 modulation in diseases like cancer and cardiac metabolic disorders. In this review, we focus on both the telomeric and nontelomeric functions of Rap1 and its modulation in various health risks, especially on the heart.

CCR2 dependent neutrophil activation and mobilization rely on TLR4-p38 axis during liver ischemia-reperfusion injury

Liver ischemia-reperfusion injury (IRI) is a common clinical problem in which neutrophil recruitment is an essential event. Our previous study revealed the important role of C-C motif chemokine receptor 2 (CCR2) in neutrophils during liver IRI. The aim of the present study was to further investigate the underlying mechanisms mediating the changes in CCR2 expression in neutrophils during this pathophysiological process. Herein, we found that TLR4 ablation reduced neutrophil mobilization from the bone marrow and the subsequent infiltration into the liver during liver IRI; neutrophil-derived CCR2 expression was also repressed. In addition, neutrophil mobilization was dependent on CCR2 expression in neutrophils, which in turn relied on activation of the TLR4-p38 axis during liver IRI. In conclusion, neutrophil-derived CCR2 expression regulates neutrophil mobilization from the bone marrow and infiltration into the liver, which requires activation of the TLR4-p38 axis during liver IRI.