SCARF1 promotes M2 polarization of Kupffer cells via calcium-dependent PI3K-AKT-STAT3 signalling to improve liver transplantation.

OBJECTIVES: This study aimed to investigate the protective effect of SCARF1 on acute rejection (AR), phagocytic clearance of Kupffer cells (KCs), M2 polarization and the exact mechanism underlying these processes. METHODS: AAV was transfected into the portal vein of rats, and AR and immune tolerance (IT) models of liver transplantation were established. Liver tissue and blood samples were collected. The level of SCARF1 was detected via WB and immunohistochemical staining. Pathological changes in liver tissue were detected using HE staining. Apoptotic cells were detected using TUNEL staining. KC polarization was assessed via immunohistochemical staining. Primary KCs were isolated and co-cultured with apoptotic T lymphocytes. Phagocytosis of apoptotic cells and polarization of KCs were both detected using immunofluorescence. Calcium concentration was determined using immunofluorescence and a fluorescence microplate reader. The levels of PI3K, p-AKT and P-STAT3 were assessed via WB and immunofluorescence. RESULTS: Compared to the IT group, the level of SCARF1 was significantly decreased in the AR group. Overexpression of SCARF1 in KCs improved AR and liver function markers. Enhanced phagocytosis mediated by SCARF1 is beneficial for improving the apoptotic clearance of AR and promoting M2 polarization of KCs. SCARF1-mediated enhancement of phagocytosis promotes increased calcium concentration in KCs, thus further activating the PI3K-AKT-STAT3 signalling pathway. CONCLUSIONS: SCARF1 promotes the M2 polarization of KCs by promoting phagocytosis through the calcium-dependent PI3K-AKT-STAT3 signalling pathway.

[Particle Size Distribution of PM Emission from In-use Gasoline and Diesel Vehicles].

Particle size distribution and emission factors from 9 State 3-5 light-duty gasoline vehicles (LDGVs) and 15 State 3-5 heavy-duty diesel vehicles (HDDVs) were tested in this study using a constant volume sampling (CVS) system on a dynamometer. The influences of driving cycles and emission control level on the PM emission factors and particle size distribution were analyzed. The results show that the PM emission factors of the tested LDGVs and HDDVs were (4.1±4.0)×1014 and (5.7±4.3)×1015 kg-1, respectively; the HDDV PM emission factor was (14±7) times less than that of LDGVs. Regarding LDGVs, the PM emission factor under the extra high speed condition was much more than that of the other speed conditions at (5.1±5.0)×1013 km-1, 11.7, 14.1, and 7.3 times more than that under the low, medium, and high speed conditions, respectively. Regarding HDDVs, the emission factor under the high speed condition was 2.5 and 1.4 times that under the low and medium speed conditions, respectively, and was mostly of nuclei-mode particles. At the emission control level of State 3-5, the PM emission factors of LDGVs were (2.7±1.7)×1013, (2.6±1.3)×1013, and (1.6±1.2)×1013 km-1, respectively, and those of HDDVs were (2.2±1.2)×1015, 2.0×1015, and (7.1±2.1)×1014 km-1, respectively. With improvement in emission control level, the particle number emission control of LDGVs and HDDVs generally showed a good downward trend. However, the emission of PM above 110 nm from LDGVs did not improve with the emission control level. Although the quantity emission factor of HDDVs with particle size above 110 nm is relatively low, its harm to the environment cannot be ignored, which should justify necessary attention.

Blockade of the Notch1/Jagged1 pathway in Kupffer cells aggravates ischemia-reperfusion injury of orthotopic liver transplantation in mice.

Liver ischemia-reperfusion injury (IRI) represents a risk factor for early graft dysfunction and an obstacle to expanding donor pool in orthotopic liver transplantation (OLT). Kupffer cells (KCs) are the largest antigen-presenting cell (APC) group and the primary modulators of inflammation in liver tissues. The vital role of Notch1/Jagged1 pathway in mouse OLT model has been reported, however, its potential therapeutic mechanism is unknown. Here, we made use of short hairpin RNA-Jagged1 and AAV-Jagged1 to explore the effects of Notch1/Jagged1 pathway in OLT. In vitro, blockade of Notch1/Jagged1 pathway downregulated the expression of Hairy and enhancer of split-1 (Hes1) gene, which in turn increased the proinflammatory effects of KCs. Moreover, the anti-inflammatory effects of Notch1/Jagged1 pathway were induced by inhibiting Hes1/gene of phosphate and tension/protein kinase B/Toll-like receptor 4/nuclear factor kappa B (Hes1/PTEN/AKT/TLR4/NF-κB) axis in KCs. In vivo, we used a well-established mouse model of OLT to mimic clinical transplantation. Mice were stochastically divided into 6 groups: Sham group (n = 15); Normal saline (NS) group (n = 15); Adeno-associated virus-green fluorescent protein (AAV-GFP) group (n = 15); AAV-Jagged1 group (n = 15); Clodronate liposome (CL) group (n = 15); CL+AAV-Jagged1 group (n = 15) . After OLT the liver damage in AAV-Jagged1 group were significantly accentuated compared to the AAV-GFP group. While blockade of Jagged1 aftet clearence of KCs by CL would not lead to further liver injuries. Taken together, our study demonstrated that blockade of Notch1/Jagged1 pathway aggravates inflammation induced by lipopolysaccharide (LPS) via Hes1/PTEN/AKT/TLR4/NF-κB in KCs, and the blockade of Notch1/Jagged1 pathway in donor liver increased neutrophil/macrophage infiltration and hepatocellular apoptosis, which suggested the function of Notch1/Jagged1 pathway in mouse OLT and highlighted the protective function of Notch1/Jagged1 pathway in liver transplantation.

Investigation of the expressions of MMPs and TIMPs between isogeneic and allogeneic rat aortic transplantation.

The present study investigated the effects of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in transplantation-associated arteriosclerosis by observing their expression in transplanted aortas in rats. Allogenic and isogenic abdominal aortic transplantations were performed and grafts were removed from the recipients at the designated time points (day 7, 14, 28 and 56 post transplantation). Hematoxylin and eosin staining, immunohistochemistry, immunofluorescence and western blot analysis were used to evaluate the grafts. Significant proliferation of the intima was observed in the allogenic transplantation groups (P<0.05). The expressions of MMPs and TIMPs in the allografts were significantly increased compared with the isografts, and the suppression of MMP2 in allografts reduced injury after transplantation. The present study concluded that the imbalance of MMPs and TIMPs led to the disturbance of synthesis and the degradation of the extracellular matrix and it may represent a key cause of chronic rejection.

Interaction Behaviors of Fibrinopeptide-A and Graphene with Different Functional Groups: A Molecular Dynamics Simulation Approach.

Graphene as a 2-dimentional material has been widely used in the field of biomedical applications. In this study, molecular dynamics simulations are carried out on the fibrinopeptide-A and graphene surfaces with N and O modifications. A new set of parameters for the CHARMM force field are developed to describe the behaviors of the surfaces. Our results indicate that the existence of most oxygen and nitrogen groups may enhance the interaction between the surfaces and the peptide, whereas the substitutional nitrogen on the graphene surface does not make a big difference. The improvement of interaction is not only because of the functional group on the surface, but also the defective morphology. The defective morphology also clears away the surface water layer. Our results suggest that the interactions between graphene biomolecules can be affected by functionalizing the surface with different types of functional groups, which is in accordance with the theory of material design.

Cannulation Selection of Portal Venous and Splenic Venous Catheterization in Venovenous Bypass of Swine Orthotopic Liver Transplantation.

BACKGROUND The aim of this study was to compare the hemodynamic changes in 2 different cannulations in portal system (portal venous catheterization and splenic venous catheterization) during venovenous bypass (VVB) of swine orthotopic liver transplantation (OLT) MATERIAL AND METHODS Thirty pairs (a total of 60) of healthy Duroc pigs were selected for OLT. According to the difference of cannulation in portal venous system during VVB, these pigs were divided into 2 groups: the PVC group (pigs with portal venous catheterization, n=15) and the SVC group (pigs with splenic venous catheterization, n=15). Intraoperative hemodynamic parameters were monitored continuously. RESULTS Two recipients in the PVC group died: 1 died of unsmooth bypass during the operation and 1 died of disseminated intravascular coagulation (DIC). There was only 1 death in the SVC group, due to hemorrhagic shock. The duration of anhepatic phase (AP) in the SVC group was significantly shorter than in the PVC group (P<0.05). Moreover, hemodynamic parameters in phase III (5 min after start of portal vein suturing) and phase IV (5 min after graft reperfusion) were remarkably different between the SVC group and the PVC group (P<0.05). CONCLUSIONS Our results show that VVB via splenic venous catheterization in swine OLT: 1) shortens the AP time; 2) keeps the hemodynamics stable; and 3) reduces the occurrence of postoperative complications. Thus, SVC appears to be superior to PVC.

Computer simulation of biomolecule-biomaterial interactions at surfaces and interfaces.

Biomaterial surfaces and interfaces are intrinsically complicated systems because they involve biomolecules, implanted biomaterials, and complex biological environments. It is difficult to understand the interaction mechanism between biomaterials and biomolecules through conventional experimental methods. Computer simulation is an effective way to study the interaction mechanism at the atomic and molecular levels. In this review, we summarized the recent studies on the interaction behaviors of biomolecules with three types of the most widely used biomaterials: hydroxyapatite (HA), titanium oxide (TiO2), and graphene(G)/graphene oxide(GO). The effects of crystal forms, crystallographic planes, surface defects, doping atoms, and water environments on biomolecules adsorption are discussed in detail. This review provides valuable theoretical guidance for biomaterial designing and surface modification.