Ischemic Lobes Research Articles

Topological approach of liver segmentation based on 3D visualization technology in surgical planning for split liver transplantation.

Split liver transplantation (SLT) is a complex procedure. The left-lateral and right tri-segment splits are the most common surgical approaches and are based on the Couinaud liver segmentation theory. Notably, the liver surface following right tri-segment splits may exhibit different degrees of ischemic changes related to the destruction of the local portal vein blood flow topology. There is currently no consensus on preoperative evaluation and predictive strategy for hepatic segmental necrosis after SLT. To investigate the application of the topological approach in liver segmentation based on 3D visualization technology in the surgical planning of SLT. Clinical data of 10 recipients and 5 donors who underwent SLT at Shenzhen Third People's Hospital from January 2020 to January 2021 were retrospectively analyzed. Before surgery, all the donors were subjected to 3D modeling and evaluation. Based on the 3D-reconstructed models, the liver splitting procedure was simulated using the liver segmentation system described by Couinaud and a blood flow topology liver segmentation (BFTLS) method. In addition, the volume of the liver was also quantified. Statistical indexes mainly included the hepatic vasculature and expected volume of split grafts evaluated by 3D models, the actual liver volume, and the ischemia state of the hepatic segments during the actual surgery. Among the 5 cases of split liver surgery, the liver was split into a left-lateral segment and right tri-segment in 4 cases, while 1 case was split using the left and right half liver splitting. All operations were successfully implemented according to the preoperative plan. According to Couinaud liver segmentation system and BFTLS methods, the volume of the left lateral segment was 359.00 ± 101.57 mL and 367.75 ± 99.73 mL, respectively, while that measured during the actual surgery was 397.50 ± 37.97 mL. The volume of segment IV (the portion of ischemic liver lobes) allocated to the right tri-segment was 136.31 ± 86.10 mL, as determined using the topological approach to liver segmentation. However, during the actual surgical intervention, ischemia of the right tri-segment section was observed in 4 cases, including 1 case of necrosis and bile leakage, with an ischemic liver volume of 238.7 mL. 3D visualization technology can guide the preoperative planning of SLT and improve accuracy during the intervention. The simulated operation based on 3D visualization of blood flow topology may be useful to predict the degree of ischemia in the liver segment and provide a reference for determining whether the ischemic liver tissue should be removed during the surgery.

Melatonin attenuates hepatic ischemia-reperfusion injury in rats by inhibiting NF-κB signaling pathway

BackgroundThe sterile inflammatory response is one of the key mechanisms leading to hepatic ischemia-reperfusion injury. Melatonin has been shown to prevent organ injuries, but its roles in the inflammatory response after hepatic ischemia-reperfusion injury have not been fully explored, especially in late ischemia-reperfusion injury. The present study aimed to investigate the roles and possible mechanisms of melatonin in the inflammatory response after hepatic ischemia-reperfusion injury. MethodsSixty Sprague-Dawley rats were randomly divided into a sham group, ischemia-reperfusion injury group (I/R group), and melatonin-treated group (M + I/R group). The rats in the I/R group were subjected to 70% hepatic ischemia for 45 min, followed by 5 or 24 h of reperfusion. The rats in the M + I/R group were injected with melatonin (10 mg/kg, intravenous injection) 15 min prior to ischemia and immediately before reperfusion. Serum and samples of ischemic liver lobes were harvested for future analysis, and the 7-day survival rate was assessed after hepatic ischemia-reperfusion surgery. ResultsIn comparison with the I/R group, the M + I/R group showed markedly decreased expression levels of inflammatory cytokines (IL-6 and TNF-α) and numbers of apoptotic hepatocytes (P < 0.05). Immunoblotting showed that the expression levels of IL-6, p-NF-κBp65/t-NF-κBp65 and p-IκB-α/t-IκB-α in the M + I/R group were significantly lower than those in the I/R group, and immunofluorescence staining showed that the expression level of p-NF-κBp65 in the M + I/R group was lower than that in the I/R group (P < 0.05). The 7-day survival rates were 20% in the I/R group and 50% in the M + I/R group (P < 0.05). ConclusionsMelatonin downregulated the activity of the NF-κB signaling pathway in the early and late stages of hepatic ischemia-reperfusion injury, alleviated the inflammatory response, protected the liver from ischemia-reperfusion injury, and increased the survival rate.

Angiographic study of the transdural collaterals at the anterior cranial fossa in patients with Moyamoya disease.

Unlike its parietal, temporal, and occipital counterparts, the frontal lobe has a broad basal surface directly facing the anterior cranial fossa dura mater which could permit establishment of transdural collaterals (TDCs) with the frontal lobe. Studies on the TDCs from the anterior cranial fossa in moyamoya disease (MMD) are scarce and inadequately investigated. A retrospective study of 100 hemispheres in 50 patients who were diagnosed with MMD by catheter angiography between January 2015 and June 2019 was performed in our institution. TDCs through the anterior ethmoid artery (AEA) or posterior ethmoid artery (PEA) were divided into 3 types respectively based on their respective angioarchitecture. Furthermore, we also studied TDCs to the temporal, parietal, and occipital lobes and collaterals from the posterior circulation to the territory of the anterior cerebral artery. TDCs through the AEA and PEA were identified in 89 (89/100, 89%) and 73 (73/100, 73%) of the hemispheres. The vascularization state of the frontal lobe was good in 89 (89/100, 89%) hemispheres. Rete mirabile and TDCs through the PEA were statistically different among patients with different Suzuki stages. No statistical difference was noted in TDCs through the AEA, frontal TDCs from other sources, and the vascularization state of the frontal lobe with regard to different Suzuki stages. TDCs through the AEA and PEA at the anterior cranial fossa play a very important role in compensating the ischemic frontal lobe. The frontal lobe could be well compensated in most of the patients with TDCs at the anterior cranial fossa.

A Pig Model of Hemivascular Liver Occlusion for The Study of Ischemia-Reperfusion Injury: Use of an Infrared System for Detecting Ischemic Areas

<p class=MsoFooterCxSpFirst style=text-align:justify;tab-stops:.5in; mso-mirror-indents:yes> Abstract <span lang=EN-GB style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-GB>Aim: <span lang=EN-GB style=font-size:10.0pt;color:black; mso-themecolor:text1;mso-ansi-language:EN-GB>Different animals are used as experimental models for the hepatic Ischemia- Reperfusion (IR) injury investigations and for each one of these animal models, many different surgical approaches have been performed. The aim of our study was to establish a new surgical pig model in which a hemi-liver is used to study the pathophysiology of hepatic IR injury. Contro-lateral hemi-liver is used as an internal control in the same animal. <span style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-US>Methods: <span style=font-size:10.0pt;color:black;mso-themecolor: text1;mso-ansi-language:EN-US> Liver ischemia was performed in six pigs by clamping the hepatic artery and vein and the portal vein to isolate the left hepatic lobe. Four hours of warm ischemia were followed by 4-hourrs of reperfusion. Biochemical and hematological analyses were performed throughout the experiments. Needle biopsies were obtained prior to ischemia and then hourly during the reperfusion for evaluation of tissue damage. <span lang=EN-GB style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-GB>To assess local temperature gradients on the liver surface a focal plane array detector camera was used. <span lang=EN-GB style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-GB>Results: <span lang=EN-GB style=font-size:10.0pt;color:black; mso-themecolor:text1;mso-ansi-language:EN-GB>Four hours ischemia induced mild signs of hepatic damage on the left ischemic lobe while more dramatic changes were evidenced after 2-hours reperfusion. Absence of tissue damage was detected on the right lobe. The liver functional test reached their maximum value at 2-4 hours after reperfusion. <span lang=EN-GB style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-GB>Conclusion: <span lang=EN-GB style=font-size:10.0pt; color:black;mso-themecolor:text1;mso-ansi-language:EN-GB>Our model is easy to perform, feasible and reproducible. This surgical model minimizes biases dependent on the individual response of different animals under the same conditions. In this IR model the new technology of an infrared thermocamera was used to control temperature changes and provide clinically important real-time information during surgery. <p class=MsoFooterCxSpMiddle style=text-align:justify;tab-stops:.5in; mso-mirror-indents:yes> <span style=font-size:11.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-US>Abbreviations: <span style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-US> <span style=font-size:10.0pt;color:black;mso-themecolor: text1;mso-ansi-language:EN-US>IR: Ischemia/Reperfusion; IV: Intravenous; <span lang=EN-GB style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-GB>ALP: Alkaline Phosphatase; ALT: Serum Alanine Aminotrasferase; AST: Aspartate Aminotransferase; LDH: Lactate Dehydrogenase; <span style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-US>ROI: Region of Interest <p class=MsoFooterCxSpLast style=text-align:justify;tab-stops:.5in;mso-mirror-indents: yes> <span style=font-size:11.0pt; color:black;mso-themecolor:text1;mso-ansi-language:EN-US>Keywords: <span style=font-size:10.0pt;color:black; mso-themecolor:text1;mso-ansi-language:EN-US> <span style=font-size:10.0pt;color:black;mso-themecolor:text1;mso-ansi-language: EN-US;mso-bidi-font-weight:bold>Animal model; Infrared imaging; Liver ischemia reperfusion injury, Liver transplantation <span style=font-size:10.0pt;color:black;mso-themecolor:text1; mso-ansi-language:EN-US>

Investigation of the emotional network in depression after stroke: A study of multivariate Granger causality analysis of fMRI data

ObjectiveDepression after stroke (DAS) is a serious complication of stroke that significantly restricts rehabilitation. Brain imaging technology is an important method for studying the emotional network of DAS. However, few studies have focused on dynamic interactions within the network. The aim of this study was to investigate the emotional network of frontal lobe DAS using the multivariate Granger causality analysis (GCA) method, a technique that can estimate the association among the brain areas to analyze functional magnetic resonance imaging (fMRI) data collected from DAS and no depression after stroke (NDAS). MethodThirty-six first-time ischemic right frontal lobe stroke patients underwent resting-state fMRI (rs-fMRI) scans. The clinical assessment scale used for screening subjects was as follows: the 24-item Hamilton Rating Scale for Depression (HAMD-24), the National Institutes of Health Stroke Scale (NIHSS), the Mini-Mental State Examination (MMSE), and the Barthel Index (BI). The multivariate GCA method was used to analyze fMRI data collected from DAS and NDAS. ResultsThe results showed positive regulations in the order from the ventromedial prefrontal cortex (VMPFC), the anterior cingulate cortex (ACC), and the amygdala (AMYG) to the thalamus, and when the interaction order is opposite, the moderating effect is negative. The thalamus could predict the negative activity of the insular (IC) via the ACC. The dorsolateral prefrontal cortex (DLPFC) could predict the activity of the ACC via the temporal pole (TP). ConclusionThis study found a VMPFC–ACC–AMYG–thalamus emotional circuit to explain the network between different brain regions associated with DAS. The DLPFC and TP play an important role in the emotional regulation of DAS, and the function of the IC is regulated negatively by the thalamus. These findings advance the neural theory of DAS, which is based on the functional relationship between different brain areas.

A Study of the Brain Abnormalities of Post-Stroke Depression in Frontal Lobe Lesion

Post stroke depression (PSD) is a serious complication of stroke. Brain imaging is an important method of studying the mechanism of PSD. However, few studies have focused on the single lesion location. The aim of this study was to investigate the brain mechanism of frontal lobe PSD using combined voxel-based morphometry (VBM) and functional magnetic resonance imaging (fMRI). In total, 30 first-time ischemic frontal lobe stroke patients underwent T1 weighted MRI and resting-state fMRI scans. Clinical assessments included the 24-item Hamilton Rating Scale for Depression, the National Institutes of Health Stroke Scale, and the Mini-Mental State Examination. In our result, decreased gray matter (GM) volume in patients was observed in the prefrontal cortex, limbic system and motor cortex. The anterior cingulate cortex, selected as a seed to perform connectivity analyses, showed a greatly decreased functional connectivity with the prefrontal cortex, cingulate cortex, and motor cortex, but had an increased functional connectivity with the hippocampus gyrus, parahippocampa gyrus, insular, and amygdala. Stroke lesion location reduces excitability of brain areas in the ipsilateral brain. PSD affects mood through the brain network of the prefrontal-limbic circuit. Some brain networks, including motor cortex and the default mode network, show other characteristics of PSD brain network.

Patient Outcomes and Cerebral Infarction after Ruptured Anterior Communicating Artery Aneurysm Treatment.

Anterior communicating artery aneurysm rupture and treatment is associated with high rates of dependency, which are more severe after clipping compared with coiling. To determine whether ischemic injury might account for these differences, we characterized cerebral infarction burden, infarction patterns, and patient outcomes after surgical or endovascular treatment of ruptured anterior communicating artery aneurysms. We performed a retrospective cohort study of consecutive patients with ruptured anterior communicating artery aneurysms. Patient data and neuroimaging studies were reviewed. A propensity score for outcome measures was calculated to account for the nonrandom assignment to treatment. Primary outcome was the frequency of frontal lobe and striatum ischemic injury. Secondary outcomes were patient mortality and clinical outcome at discharge and at 3 months. Coiled patients were older (median, 55 versus 50 years; P = .03), presented with a worse clinical status (60% with Hunt and Hess Score >2 versus 34% in clipped patients; P = .02), had a higher modified Fisher grade (P = .01), and were more likely to present with intraventricular hemorrhage (78% versus 56%; P = .03). Ischemic frontal lobe infarction (OR, 2.9; 95% CI, 1.1-8.4; P = .03) and recurrent artery of Heubner infarction (OR, 20.9; 95% CI, 3.5-403.7; P < .001) were more common in clipped patients. Clipped patients were more likely to be functionally dependent at discharge (OR, 3.2; P = .05) compared with coiled patients. Mortality and clinical outcome at 3 months were similar between coiled and clipped patients. Frontal lobe and recurrent artery of Heubner infarctions are more common after surgical clipping of ruptured anterior communicating artery aneurysms, and are associated with poorer clinical outcomes at discharge.

Role of PPARγ in the hematogenous spread of hepatocellular carcinoma after hepatic ischemia reperfusion in mice

Objective To investigate the role of peroxisome proliferator-activated receptor γ (PPARγ) in hematogenous spread of hepatocellular carcinoma after hepatic ischemia reperfusion in mice and its mechanism. Methods One hundred and sixty mice were randomly divided into 4 groups, sham, control, Rosiglitazone(R group) and Rosiglitazone + GW9662 (R+ GW). The mice models with hepatic ischemia reperfusion combined with portal vein metastasis of hepatocellular carcinoma were well established. Serum ALT level, expressions of MMP-9, NF-κB and PPARγ, hepatic replacement area (HRA) and survival of mice were compared. Results (1) The median survival in sham group was 16.3 d, R group 12.1 d, control group 9.6 d, R+ GW group 8.7 d. (2) Impact on portal venous metastasis: compared with left hepatic lobe (ischemic hepatic lobe) of control group, the HRA was significantly decreased in the left hepatic lobe of sham group (29.1% vs. 13.2%, P<0.05). Tumor load was higher in control group than R group (29.1% vs. 13.0%, P<0.05). (3) Serum ALT level: after 2 h, 8 h and 24 h hepatic ischemia reperfusion injury (HIRI), the ALT levels in control group [(1 134.2±320.5) U/L], R group [(1 017.3±365.9)U/L] and R+ GW group [(1 344.0±304.3) U/L] were all higher than sham group [(20.6±7.8)U/L], P<0.05. With 8 and 24 h HIRI, ALT levels were highest in R+ GW group [(4 101.7±462.2)U/L, (3 730.8±582.7)U/L], following by control group [(3 649.1±440.1) U/L, (2 226.7±442.7) U/L], and R group [(1 691.9±398.6)U/L, (1 109.2±237.4)U/L], P<0.05. (4) MMP-9 expression: after 8 h HIRI, MMP-9 expression level was predominantly elevated in control group than R group [(41.3±10.7) vs. (4.7±1.1), P<0.05]. Similarly, MMP-9 expression was higher in R+ GW group than both control and R groups [(166.9±7.9) vs. (41.3±10.7) and (4.7±1.1), P<0.05]. (5) Expressions of PPARγ and NF-κB: in the control group, PPARγ expression emerged after 2 h HIRI, and reached the peak with 8 h HIRI, decreased significantly with 24 h HIRI. NF-κB expression elevated with time, and at the peak with 24 h HIRRI. In R+ GW group, the PPARγ expression was similar to control group and high expression of NF-κB were detected at all three endpoints. In R group, marked expression of PPARγ was observed after 2 h HIRI, and reached to peak after 24 h HIRI. NF-κB showed weakly positive expression after 2 h HIRI. Conclusions Rosiglitazone could significantly reduce hematogenous spread of hepatocellular carcinoma after hepatic ischemia reperfusion in mice. This may be attributed to NF-κB expression inhibition by PPARγ up-regulation and decreased MMP-9 production after pretreatment with Rosiglitazone. Key words: Hepatocellular carcinoma; Ischemia/reperfusion; Peroxisome proliferator-activated receptor γ(PPARγ); Portal venous metastasis

Intracellular HMGB1 mediating neutrophil extracellular trap formation during liver sterile inflammation

Abstract Neutrophil extracellular traps (NETs) has been recently found exacerbate sterile inflammatory injury during liver ischemia/reperfusion (I/R). High mobility group box-1 (HMGB1) released from damaged cells, mediates liver damage and inflammatory responses after I/R. However, the intracellular role of HMGB1 in NET formation remains unknown. We sought to determine the role of intracellular HMGB1 in NET formation. Myloid cells HMGB1 knockout (LysM-HMGB1 KO) and HMGB1-flox mice were subjected to a non-lethal warm liver I/R. Less NETs was identified in ischemic liver lobes of LysM-HMGB1 KO mice compared with flox mice by confocal immunofluorescence (IF) imaging. This was associated with significantly less NET markers in LysM-HMGB1 KO mice, serum level of myeloperoxidase (MPO)-DNA complexes, and tissue level of citrullinated histone H3. Absence of HMGB1 in myloid cells protected the live from I/R injury indicated by significantly decreased serum transaminases (sALT), less necrosis and inflammatory cytokines production compared to flox mice. In vitro, no NET formation was observed in HMGB1 KO neutrophils under stimulation of PMA (positive control) or extracellular HMGB1 or histones confirmed by IF imaging. Chromatin in HMGB1 KO neutrophils failed to de-condensate in response to PMA which is the key step of NET formation. Additionally, gene deletion of HMGB1 in neutrophils completely blocked citrullination of histone H3 as a key step of NET formation, compared with control neutrophils in response to various stimulations. Our study demonstrates the dominant role of intracellular HMGB1 in NET formation. Lack of HMGB1 in neutrophils leads to diminished NET formation protect the liver from organ damage and cells death after liver I/R.

Transcriptional Response in a Rat Model of Liver Ischemia‐Reperfusion Injury

Ischemia‐reperfusion (I/R) is central to the pathophysiology of liver injury caused by acute hepatic traumas, including liver transplantation. Elevated levels of reactive oxygen species (ROS) govern the magnitude of liver injury and tissue damage. Therapies that reduce the ROS burden are under investigation to determine their ability to improve transplant outcomes including those associated with extended criteria donors. However, the pathways and upstream regulators that drive ROS‐mediated responses remain unknown. In this study, we have utilized a rodent model of 70% partial transient warm hepatic ischemia to characterize transcriptional changes in response to ischemic insult and during early reperfusion. Blood supply to the left and medial lobes was clamped for 30 minutes while the right lobes remain perfused. Animals were sacrificed at the end of ischemia (no reperfusion), and after thirty minutes or six hours of reperfusion. The ischemic lobes and the non‐ischemic lobes were each compared to tissue from animals that underwent sham surgery at each time. Total RNA was prepared for microarray and analyzed using Affymetrix Rat Transcriptome 1.0 arrays. Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA) of the 24,536 quantified genes revealed a great overlap in biological pathways and upstream regulators that changed in both the ischemic and non‐ischemic lobes when compared to shams. This implies a significant proportion of changes in the ischemic‐reperfused lobes were attributable to the effects of anesthesia and/or surgery. We found 1575 differentially expressed genes (FDR&lt;0.05) in the ischemic‐reperfused group at 30 minutes and 2672 genes at 6 hours. However, 1067 and 1646 of the altered genes at 30 minutes and 6 hours, respectively, also changed in the non‐ischemic lobes, suggesting systemic factors play in role in the response to I/R. Among those genes unique to the ischemic‐reperfused group at thirty minutes, the expression of several immediate early genes (Egr‐1, Fos‐b, Jun‐b) increased over five‐fold. This response could indicate that induction of AP‐1 (activator protein‐1) in response to hypoxia plays a role in promoting cell survival. Further investigation of AP‐1 activity may identify new pharmacological targets to decrease hepatic ischemia‐reperfusion injury. This immediate early gene response, which is characteristic of liver regeneration after partial hepatectomy, has not been previously identified in models of hepatic ischemia‐reperfusion.Support or Funding InformationThis work was supported by NIGMS grant 5T32GM077995 from the National Institutes of Health, a Pharmacia Predoctoral Fellowship, and the Graduate Research Fellowship Program of the National Science Foundation (NSF).Valerie Zabala is a Howard Hughes Medical Institute Gilliam Fellow.

The relationship between activation of Toll-like receptor 4 and partial hepatic ischemia/reperfusion injury in mice

Objective To investigate the relationship between the activation of Toll-like receptor 4 (TLR4) and hepatic ischemia reperfusion injury. Methods 24 mice were randomly divided into TLR defect group (C3H/Hej, Hej group), wild type group (/Heouj C3H, Heouj group) and sham operation group (Sham group), 8 mice in every group. BALB/c mice copied partial hepatic ischemia reperfusion injury model, using immune histochemistry method to observe the TLR4 in the distribution of liver and the expression while monitoring of plasma alanine amino transferase (ALT) and portal vein endotoxin in blood serum endotoxin (EN) and tumor necrosis factor-α (TNF-α) changes; then to TLR4 congenital defects in mice C3H/Hej and wild type mice C3H/Heouj model and observe changes of ALT and portal vein serum TNF-α. Results (1) BALB/c mouse the left middle lobe of liver ischemia after 1 h, reperfusion 1, 3 h, ischemic liver lobe TLR4 increased expression of and 1 h after reperfusion, the strongest, positive cells is mainly Kupffer cells and blood vessels in neutrophils. (2) There was no significant difference between the time points of portal vein serum EN (P>0.05). (3) At 3 h of repefusion, serum TNF-α was significantly higher than sham group [Hej: (152±43) pg/ml vs. (18±10) pg/ml, n=6, t=5.26, P<0.01; Heouj: (249±52) pg/ml vs. (25±13) pg/ml, n=6, t=7. 24, P<0.01]; (4) Hej mice liver function damage light in Heouj mice [reperfusion for 1 h: (662±106) vs. (1 216±174) pg/ml, n=6, t=4.21, P<0.01; reperfusion for 3 h: (1145±132) pg/ml vs. (2 958±187) pg/ml, n=6, t=13.72, P<0.01], and 3 h of reperfusion the level of serum TNF-α significantly lower than heouj mice [(152±43) pg/ml vs. (249±52) pg/ml, n=6, t=3.94, P<0.01]. Conclusion TLR4 receptor is activated during hepatic ischemia reperfusion injury, the process of hepatic ischemia reperfusion injury was mediated by TNF-α and other cytokines. Key words: Liver; Reperfusion, injury; Receptors; Endotoxin

The vitamin D analogue paricalcitol attenuates hepatic ischemia/reperfusion injury through down-regulation of Toll-like receptor 4 signaling in rats.

IntroductionRecent studies have revealed that vitamin D and its synthetic analogues have a protective effect on experimental ischemia/reperfusion (I/R) models in several organs, but little is known about its effect on the liver. The aim of this study was to evaluate the beneficial effects of vitamin D in a model of liver I/R in rats, focusing on Toll-like receptor (TLR) 4 signaling, which has been shown to be involved in I/R injury.Material and methodsTwenty-four male Wistar rats were randomized into four groups: Saline + Sham, Saline + I/R, Paricalcitol + Sham, and Paricalcitol + I/R. A synthetic vitamin D2 analogue, paricalcitol, was intraperitoneally injected 24 h prior to surgery. The animals were subjected to 60 min of partial warm ischemia (70%), followed by reperfusion for 6 h on the same day. The ischemic lobe of the liver and blood were collected for molecular biochemical analyses.ResultsLiver damage following I/R was diminished by pretreatment with paricalcitol. Pretreatment with paricalcitol decreased the levels of pro-inflammatory mediators, such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and macrophage migration inhibitory factor (MIF), in both plasma and liver tissue. In addition, pretreatment with paricalcitol markedly down-regulated the expression of TLR4, HMGB1, TNF-α and NF-κB.ConclusionsThe vitamin D analogue paricalcitol attenuates hepatic I/R injury through down-regulation of the TLR4 signaling pathway and might be considered to be a potential nutritional therapeutic agent against I/R injury in the liver.

Endoplasmic reticulum stress of Kupffer cells involved in the conversion of natural regulatory T cells to Th17 cells in liver ischemia-reperfusion injury.

Our previous studies have shown that regulatory T cells (Tregs) are reduced and Th17 cells are elevated in liver insults. Recent studies have indicated the critical role of endoplasmic reticulum (ER) stress of Kupffer cells (KCs) in evoking liver inflammation following reperfusion. The objective of this study was to investigate the role of ER stress of KCs in the conversion of Tregs to Th17 cells and the effect on liver ischemia-reperfusion injury. The partial warm liver ischemia-reperfusion injury mouse model was adopted. ER stress of KCs and the frequency of Tregs and Th17 cells following reperfusion were analyzed. Apart from depletion and adoptive transfer of KCs, KCs were isolated from ischemic lobes and co-cultured with Tregs to study the effect of KCs on Tregs and Th17 cells. It was found that KCs induced ER stress, decreased natural Tregs (nTregs), and increased Th17 cells after reperfusion. Depletion of KCs modulated the reduction of nTregs and elevation of Th17 cells. Co-culture with stressed KCs led to the reduction in nTregs and elevation of Th17 cells. This effect was suppressed by anti-interleukin-6. Adoptive transfer of these stressed KCs resulted in the reduction in nTregs and elevation of Th17 cells and caused liver injury. Endoplasmic reticulum stress of KCs contributed to the conversion of nTregs to Th17 cells due to interleukin-6, resulting in the worsening of liver insult.

New NIR spectroscopy based method to determine ischemia in vivo in liver – a first study on rats

Abstract In this study we analysed ischemic rat liver lobes with Near Infrared Spectroscopy (NIRS) to evaluate the potential of NIRS as predictor of ischemic reperfusion injury (IRI). We were able to predict duration of ischemia using visible and near infrared light.

A Novel Mouse Model of Liver Ischemic/Reperfusion Injury and its Differences to the Existing Model

ABSTRACTBackground: Ischemia of the cephalad lobes (70% of liver mass) is a frequently employed mouse hepatic ischemia/reperfusion (I/R) model that does not involve outflow occlusion. This model produces results with relatively large variances. Materials and Methods: A novel model of ischemia of the left lateral lobe (35% of liver mass) that involves temporarily occluding the blood supply to the cephalad lobes to expel blood followed by occlusion of both the inflow and outflow of the left lateral lobe, was developed. Mice in the 35% (novel) and 70% (existing) model groups were subjected to I/R injury, and biochemical and histological analyses of blood and liver samples were performed. Tissue oxygen partial pressure (tPO2) measurements in the ischemic lobes were also performed to determine whether the hepatic tissue was in a stable hypoxic state. Statistical analyses of the biochemical results, histological scores, and tPO2 levels were performed from which coefficients of variation (CV) were calculated. Results: The CVs of the aminotransferase activities, histological scores, and tPO2 levels were much lower in the 35% group than those in the 70% group. The tPO2 measurements demonstrated that inflow occlusion in the 70% model did not result in a stable hypoxic state, even after the portal triads were ligated and severed, indicating that there was blood reflux from the vena cava, which would be responsible for the variations in results with the 70% I/R model. Conclusions: The new 35% I/R model leads to reproducible results because both inflow and outflow of the ischemic lobe are occluded.

Damage-associated molecular pattern-activated neutrophil extracellular trap exacerbates sterile inflammatory liver injury.

Innate immunity plays a crucial role in the response to sterile inflammation such as liver ischemia/reperfusion (I/R) injury. The initiation of liver I/R injury results in the release of damage-associated molecular patterns, which trigger an innate immune and inflammatory cascade through pattern recognition receptors. Neutrophils are recruited to the liver after I/R and contribute to organ damage and innate immune and inflammatory responses. Formation of neutrophil extracellular traps (NETs) has been recently found in response to various stimuli. However, the role of NETs during liver I/R injury remains unknown. We show that NETs form in the sinusoids of ischemic liver lobes in vivo. This was associated with increased NET markers, serum level of myeloperoxidase-DNA complexes, and tissue level of citrullinated-histone H3 compared to control mice. Treatment with peptidyl-arginine-deiminase 4 inhibitor or DNase I significantly protected hepatocytes and reduced inflammation after liver I/R as evidenced by inhibition of NET formation, indicating the pathophysiological role of NETs in liver I/R injury. In vitro, NETs increase hepatocyte death and induce Kupffer cells to release proinflammatory cytokines. Damage-associated molecular patterns, such as High Mobility Group Box 1 and histones, released by injured hepatocytes stimulate NET formation through Toll-like receptor (TLR4)- and TLR9-MyD88 signaling pathways. After neutrophil depletion in mice, the adoptive transfer of TLR4 knockout or TLR9 knockout neutrophils confers significant protection from liver I/R injury with a significant decrease in NET formation. In addition, we found inhibition of NET formation by the peptidyl-arginine-deiminase 4 inhibitor and that DNase I reduces High Mobility Group Box 1 and histone-mediated liver I/R injury. Damage-associated molecular patterns released during liver I/R promote NET formation through the TLR signaling pathway. Development of NETs subsequently exacerbates organ damage and initiates inflammatory responses during liver I/R.

Neutrophil extracellular traps activated by damage associated molecular patterns exacerbates sterile inflammatory liver injury (INM1P.427)

Abstract The initiation of liver ischemia/reperfusion (I/R) injury results in the release of damage associated molecular patterns (DAMPs) such as HMGB1 and histones, which trigger innate immune and inflammatory cascade via Toll-like receptor 4 (TLR4) or TLR9. Infiltrated neutrophils contribute to the organ damage, innate immune and inflammatory responses after liver I/R. Formation of neutrophil extracellular trap (NET) has been recently found in response to various stimuli. However, the role of NETs during liver I/R remains unknown. We show that NETs form in the sinusoids of ischemic liver lobes in vivo, associated with increased serum level of myeloperoxidase (MPO)-DNA complexes and tissue level of citrullinated-histone H3 (NET markers) compared to control mice. Treatment with peptidyl-arginine-deiminase (PAD) 4 inhibitor or DNase I conferred significant protection after liver I/R evidenced by inhibition of NET formation, indicating the pathophysiological role of NETs in liver I/R injury. DAMPs, such as HMGB1 and histones stimulate NET formation through TLR4 and TLR9-MyD88 signaling pathways. After neutrophil depletion in mice, the adoptive transfer of TLR4 knockout (KO) or TLR9 KO neutrophils confers significant protection from liver I/R injury with significant decrease in NET formation. Conclusion: DAMPs released during liver I/R promotes NET formation through TLRs signaling pathway. NETs subsequently exacerbates organ damage and initiates inflammatory responses during liver I/R.

CXC chemokines function as a rheostat for hepatocyte proliferation and liver regeneration.

BackgroundOur previous in vitro studies have demonstrated dose-dependent effects of CXCR2 ligands on hepatocyte cell death and proliferation. In the current study, we sought to determine if CXCR2 ligand concentration is responsible for the divergent effects of these mediators on liver regeneration after ischemia/reperfusion injury and partial hepatectomy.MethodsMurine models of partial ischemia/reperfusion injury and hepatectomy were used to study the effect of CXCR2 ligands on liver regeneration.ResultsWe found that hepatic expression of the CXCR2 ligands, macrophage inflammatory protein-2 (MIP-2) and keratinocyte-derived chemokine (KC), was significantly increased after both I/R injury and partial hepatectomy. However, expression of these ligands after I/R injury was 30-100-fold greater than after hepatectomy. Interestingly, the same pattern of expression was found in ischemic versus non-ischemic liver lobes following I/R injury with expression significantly greater in the ischemic liver lobes. In both systems, lower ligand expression was associated with increased hepatocyte proliferation and liver regeneration in a CXCR2-dependent fashion. To confirm that these effects were related to ligand concentration, we administered exogenous MIP-2 and KC to mice undergoing partial hepatectomy. Mice received a “high” dose that replicated serum levels found after I/R injury and a “low” dose that was similar to that found after hepatectomy. Mice receiving the “high” dose had reduced levels of hepatocyte proliferation and regeneration whereas the “low” dose promoted hepatocyte proliferation and regeneration.ConclusionsTogether, these data demonstrate that concentrations of CXC chemokines regulate the hepatic proliferative response and subsequent liver regeneration.

Heme oxygenase-1 protects rat liver against warm ischemia/reperfusion injury via TLR2/TLR4-triggered signaling pathways.

To investigate the efficacy and molecular mechanisms of induced heme oxygenase (HO)-1 in protecting liver from warm ischemia/reperfusion (I/R) injury. Partial warm ischemia was produced in the left and middle hepatic lobes of SD rats for 75 min, followed by 6 h of reperfusion. Rats were treated with saline, cobalt protoporphyrin (CoPP) or zinc protoporphyrin (ZnPP) at 24 h prior to the ischemia insult. Blood and samples of ischemic lobes subjected to ischemia were collected at 6 h after reperfusion. Serum transaminases level, plasma lactate dehydrogenase and myeloperoxidase activity in liver were measured. Liver histological injury and inflammatory cell infiltration were evaluated by tissue section and liver immunohistochemical analysis. We used quantitative reverse transcription polymerase chain reaction to analyze liver expression of inflammatory cytokines and chemokines. The cell lysates were subjected to immunoprecipitation with anti-Toll-IL-1R-containing adaptor inducing interferon-β (TRIF) and anti-myeloid differentiation factor 88 (MyD88), and then the immunoprecipitates were analyzed by SDS-PAGE and immunoblotted with the indicated antibodies. HO-1 protected livers from I/R injury, as evidenced by diminished liver enzymes and well-preserved tissue architecture. In comparison with ZnPP livers 6 h after surgery, CoPP treatment livers showed a significant increase inflammatory cell infiltration of lymphocytes, plasma cells, neutrophils and macrophages. The Toll-like receptor (TLR)-4 and TANK binding kinase 1 protein levels of rats treated with CoPP significantly reduced in TRIF-immunoprecipitated complex, as compared with ZnPP treatment. In addition, pretreatment with CoPP reduced the expression levels of TLR2, TLR4, IL-1R-associated kinase (IRAK)-1 and tumor necrosis factor receptor-associated factor 6 in MyD88-immunoprecipitated complex. The inflammatory cytokines and chemokines mRNA expression rapidly decreased in CoPP-pretreated liver, compared with the ZnPP-treated group. However, the expression of negative regulators Toll-interacting protein, suppressor of cytokine signaling-1, IRAK-M and Src homology 2 domain-containing inositol-5-phosphatase-1 in CoPP treatment rats were markedly up-regulated as compared with ZnPP-treated rats. HO-1 protects liver against I/R injury by inhibiting TLR2/TLR4-triggered MyD88- and TRIF-dependent signaling pathways and increasing expression of negative regulators of TLR signaling in rats.

Hepatic ischemia/reperfusion promote hematogenic metastasis of hepatocellular carcinoma in mice through induction of MMP-9 expression

Objective To investigate the effect of ischemia/reperfusion(I/R) on tumor metastasis in a experimental mouse model of hematogenous metastasis after I/R; we also quantitated expression of matrix metalloproteinases-9 (MMP-9) during I/R.Methods An experimental mouse model of metastasis after partial hepatic I/R was designed to determine the effects of I/R on tumor metastasis to liver.Tumor loads were valued 7 days after operation.In addition,tissue analysis for alanine transaminase,aspartate transaminase (AST) and matrix metalloproteinases and 8 h reperfusion were performed.Results After 2 h hepatic reperfusion,ALT and AST in I 45 min group were higher than the sham group and I 30 min group (P ＜0.05).ALT and AST in the sham group were both a little higher than the normal.ALT and AST in the I 45 min group and I 30 min group at 8 h were both higher than those at 2 h reperfusion(P ＜0.05).The tumor load (valued by Hepatic replacement area) and the expression of MMP-9 in ischemic lobe in I 45 min group were greater than that after 30 min group and sham group.(P =0.013,P =0.007).There was no statistical difference on tumor load between the right lobe of sham operated mice and the right lobe (non-ischemic lobe) of mice subjected to I/R(P =0.089).Mouse survival were compared among the groups.Mice in Sham group lived longer than I 30 min group (P =0.041).And there were no statistical significance between I 45 min group and I 30 min group (P =0.055).MMP-9 expression in I 45 min group was higher than I 30 min group(P ＜ 0.001).Conclusion Hepatic I/R promotes liver hematogenic metastasis of hepatocellular carcinoma in mice through induction of MMP-9 expression. Key words: Hepatocellular carcinoma ; Ischemia/reperfusion; Matrix metalloproteinase-9 ; Portal vein metastasis