Simulated Microgravity can Promote the Apoptosis and Change Inflammatory State of Kupffer Cells

Objective In this study,we analyzed the transcriptome sequences of Kupffer cells exposed to simulated microgravity for 3 d and conducted biological experiments to determine how microgravity initiates apoptosis in Kupffer cells.Methods Rotary cell culture system was used to construct a simulated microgravity model.GO and KEGG analyses were conducted using the DAVID database.GSEA was performed using the R language.The STRING database was used to conduct PPI analysis.qPCR was used to measure the IL1B,TNFA,CASP3,CASP9,and BCL2L11 mRNA expressions.Western Blotting was performed to detect the level of proteins CASP3 and CASP 9.Flow cytometry was used to detect apoptosis and mitochondrial membrane cells.Transmission electron microscopy was used to detect changes in the ultrastructure of Kupffer cells.Results Transcriptome Sequencing indicated that simulated microgravity affected apoptosis and the inflammatory state of Kupffer cells.Simulated microgravity improved the CASP3,CASP9,and BCL2L11 expressions in Kupffer cells.Annexin-V/PI and JC-1 assays showed that simulated microgravity promoted apoptosis in Kupffer cells.Simulated microgravity causes M1 polarization in Kupffer cells.Conclusion Our study found that simulated microgravity facilitated the apoptosis of Kupffer cells through the mitochondrial pathway and activated Kupffer cells into M1 polarization,which can secrete TNFA to promote apoptosis.

抑制Kupffer Cell对大鼠肝脏切除微循环障碍的影响

目的探讨应用Kupffer cell封闭剂对肝脏微循环障碍的影响。方法切除大鼠左肝叶建立肝脏切除模型60只健康SPF雄性级大鼠随机分为4组:假手术组(A),缺血再灌注组(B),缺血再灌注+肝叶切除+生理盐水组(C)和缺血再灌注+肝叶切除+三氯化钆组(D)。术前1 d和2 d,向D组注射氯化钆(浓度为0.25%,10 ml/kg),C组注射同等浓度的生理盐水。各组分别于术后1天处死。检测血中丙胺酸氨基转移酶(ALT),天冬氨酸氨基转移酶(AST),内皮素-1(ET-1)及一氧化氮(NO)的水平;病理学检查各组术后肝组织的病理改变。提取肝组织中RNA,应用RT-PCR法检测ET-1,eNOs,iNOs及HO-1mRNA的表达。结果 A组肝细胞无明显异常,C组肝细胞炎症和坏死的程度明显高于B组和D组。B,C,D组大鼠血清中ALT,AST。ET-1的水平明显高于A组(P<0.05),NO的水平明显低于A组(P<0.05);肝组织中织ET-1、eNOS、iNOS及HO-1 mRNA表达水平较A组显著升高(P<0.05);C组大鼠血清中ALT,AST.ET-1的水平明显高于B组和D组(**P<0.05,Δ*P<0.05),NO的水平明显低于其他两组(**P<0.05,Δ*P<0.05)且肝组织中织ET-1、eNOS、iNOS及HO-1 mRNA表达水平较其B组显著升高(**P<0.05),其中iNOS及HO-1 mRNA表达水平较D组显著升高(Δ*P<0.05)。结论术前注射氯化钆能够显著改善肝叶切除术后微循环障碍,减轻肝脏损伤。

Heme oxygenase-1 protects donor livers from ischemia/reperfusion injury:The role of Kupffer cells

AIM:To examine whether heme oxygenase (HO)-1 overexpression would exert direct or indirect effects on Kupffer cells activation, which lead to aggravation of reperfusion injury.METHODS: Donors were pretreated with cobalt protoporphyrin (CoPP) or zinc protoporphyrin (ZnPP), HO-1 inducer and antagonist, respectively. Livers were stored at 4℃ for 24 h before transplantation. Kupffer cells were isolated and cultured for 6 h after liver reperfusion.RESULTS: Postoperatively, serum transaminases were significantly lower and associated with less liver injury when donors were pretreated with CoPP, as compared with the ZnPP group. Production of the cytokines tumor necrosis factor-α and interleukin-6 generated by Kupffer cells decreased in the CoPP group. The CD14 expression levels (RT-PCR/Western blots) of Kupffer cells from CoPP-pretreated liver grafts reduced.CONCLUSION: The study suggests that the potential utility of HO-1 overexpression in preventing ischemia/reperfusion injury results from inhibition of Kupffer cells activation.

Kupffer cell and apoptosis in experimental HCC

INTRODUCTION Our previous study has proved that Kupffer cellsmay have an inhibitory effect on the process ofhepatocarcinogenesis,however,their inhibitorymechanism needs exploring deeply.We performed acomparative study on the expression of PCNA,Bax,P53 and apoptosis of liver cancer cells usingimmunohistochemical technology and terminaldeoxynucleotidyl transferase (TdT)-mediateddUTP-digoxigenin nick end labeling(TUNEL)

Effect of Kupffer cells on immune tolerance in liver transplantation

Objective:To observe the effect of Kupfler cells on immune tolerance in liver transplantation. Methods:The rats were randomly divided into A,B and C groups.A group was sham operation group.The donor rats of group B had intraperitoneal injection of 1 nmol Kuppffer cells every other day for three days before liver transplantation.Rats of group C were injected with equal saline.The rat liver transplantation models were established by modified Kamada’s two-cuff technique.The rats were sacrificed after 24 hours.The concentrations of ALT and AST in serum were measured with the biochemical analyzer.The level of IL-2 and TNF- a in serum were measured by ELISA method.The apoptotic indexes were detected by immunohistochemical assay. Results:The concentration of ALT,AST,IL-1 and TNF- a in A,B and C groups were increased successively.The levels of group C were significantly higher than that of group B and A(P【0.05), and the levels of group B were significantly higher than that of group A(P【0.05).The apoptotic indexes of three groups were 3.40±0.37,14.70±2.54 and 26.33±3.65,respectively,with significant difference among three groups(P【0.05).Conclusions:Pretreatment with Kupfler cells can reduce liver injury and raise liver transplantation immune tolerance.

Role of Kupffer cells in the pathogenesis of liver disease

Kupffer cells, the resident liver macrophages have long been considered as mostly scavenger cells responsible for removing particulate material from the portal circulation. However, evidence derived mostly from animal models, indicates that Kupffer cells may be implicated in the pathogenesis of various liver diseases including viral hepatitis, steatohepatitis, alcoholic liver disease, intrahepatic cholostasis, activation or rejection of the liver during liver transplantation and liver fibrosis. There is accumulating evidence, reviewed in this paper, suggesting that Kupffer cells may act both as effector cells in the destruction of hepatocytes by produdng harmful soluble mediators as well as antigen presenting cells during viral infections of the liver. Moreover they may represent a significant source of chemoattractant molecules for cytotoxic CD8 and regulatory T cells. Their role in fibrosis is well established as they are one of the main sources of TGFβ1 production, which leads to the transformation of stellate cells into myofibroblasts. Whether all these variable functions in the liver are mediated by different Kupffer cell subpopulations remains to be evaluated. In this review we propose a model that demonstrates the role of Kupffer cells in the pathogenesis of liver disease.

Influence of Kupffer cells and platelets on ischemia-reperfusion injury in mild steatotic liver

AIM: To investigate the effect of mild steatotic liver on ischemia-reperfusion injury by focusing on Kupffer cells (KCs) and platelets. METHODS: Wistar rats were divided into a normal liver group (N group) and a mild steatotic liver group (S group) induced by feeding a choline-deficient diet for 2 wk. Both groups were subjected to 20 min of warm ischemia followed by 120 min of reperfusion. The number of labeled KCs and platelets in sinusoids and the blood perfusion in sinusoids were observed by intravital microscopy (IVM), which was performed at 30, 60 and 120 min after reperfusion. To evaluate serum alanine aminotransferase as a marker of liver deterioration, blood samples were taken at the same time as IVM.RESULTS: In the S group, the number of platelets adhering to KCs decreased significantly compared with the N group (120 after reperfusion; 2.9±1.1 cells/acinus vs 4.8±1.2 cells/acinus, P<0.01). The number of KCs in sinusoids was significantly less in the S group than in the N group throughout the observation periods (before ischemia, 19.6±3.3 cells/acinus vs 28.2±4.1 cells/acinus, P<0.01 and 120 min after reperfusion, 29.0±4.3 cells/acinus vs 40.2±3.3 cells/acinus, P<0.01). The blood perfusion of sinusoids 120 min after reperfusion was maintained in the S group more than in the N group. Furthermore, elevation of serum alanine aminotransferase was lower in the S group than in the N group 120 min after reperfusion (99.7±19.8 IU/L vs 166.3±61.1 IU/L, P=0.041), and histological impairment of hepatocyte structure was prevented in the S group. CONCLUSION: Ischemia-reperfusion injury in mild steatotic liver was attenuated compared with normal liver due to the decreased number of KCs and the reduction of the KC-platelet interaction.

Isolation of Kupffer cells and their suppressive effects on T lymphocyte growth in rat orthotopic liver transplantation

AIM： To develop a practical method for isolation, purification and culture of hepatic Kupffer cells （KCs） and to observe their suppressive effects on the proliferation of alloreactive T cells.METHODS： Perfusion in situ in vivo combined with density gradient centdfugation was applied in isolation, purification and culture of hepatic KC. The suppression by KCs on the T cell proliferation in mixed lymphocyte reaction （MLR） was observed.RESULTS：（1.1± 0.2） ×10^7 KCs per liver, （93.5% ±1.8%） viable cells, over 90% purity and positive for FD-2. After the first 24 h in culture, a great number of KCs which exhibited typical characteristics were observed. Using 3H-TdR incorporation assay, non-irradiated KCs significantly suppressed allo-MLR. The KCs recovered from accepted liver allografts in groups D and F were more effective in suppressing allo-MLR.CONCLUSION： A standardized procedure for isolation of highly purified rat KCs is proposed and KCs have suppressive effects on the proliferation of alloreactive T cells, especially those derived from accepted liver allografts.

Ron receptor-dependent gene regulation of Kupffer cells during endotoxemia

BACKGROUND: Ron receptor tyrosine kinase signaling in macrophages, including Kupffer cells and alveolar macrophages,suppresses endotoxin-induced proinflammatory cytokine/chemokine production. Further, we have also identified genes from Ron replete and Ron deplete livers that were differentially expressed during the progression of liver inflammation associated with acute liver failure in mice by microarray analyses.While important genes and signaling pathways have been identified downstream of Ron signaling during progression of inflammation by this approach, the precise role that Ron receptor plays in regulating the transcriptional landscape in macrophages, and particular in isolated Kupffer cells, has still not been investigated.METHODS: Kupffer cells were isolated from wild-type(TK+/+)and Ron tyrosine kinase deficient(TK-/-) mice. Ex vivo, the cells were treated with lipopolysaccharide(LPS) in the presence or absence of the Ron ligand, hepatocyte growth factor-like protein(HGFL). Microarray and qRT-PCR analyses were utilized to identify alterations in gene expression between genotypes.RESULTS: Microarray analyses identified genes expressed differentially in TK+/+ and TK-/- Kupffer cells basally as well as after HGFL and LPS treatment. Interestingly, our studies identified Mefv, a gene that codes for the anti-inflammatory protein pyrin, as an HGFL-stimulated Ron-dependent gene.Moreover, lipocalin 2, a proinflammatory gene, which is induced by LPS, was significantly suppressed by HGFL treatment.Microarray results were validated by qRT-PCR studies on Kupffer cells treated with LPS and HGFL.CONCLUSION: The studies herein suggest a novel mechanism whereby HGFL-induced Ron receptor activation promotes the expression of anti-inflammatory genes while inhibiting genes involved in inflammation with a net effect of diminished inflammation in macrophages.

Neutrophil depletion-but not prevention of Kupffer cell activation-decreases the severity of cerulein-induced acute pancreatitis

AIM： To determine whether neutrophil depletion and Kupffer cell inhibition might combine their protective effects to decrease the severity of acute pancreatitis. METHODS： Nice had cerulein administration to induce acute pancreatitis and were pretreated with either anti-mouse neutrophil serum or gadolinium chloride （GdCh） to prevent Kupffer cell activation, or both treatments. Injury was assessed in pancreas and lungs. Myeloperoxidases （MPO） assessed neutrophil infiltration. Interleukin-6 （IL-6） and IL-10 were measured in serum, pancreas, lungs and liver. RESULTS： In mice with acute pancreatitis, neutrophil depletion reduced the severity of pancreatitis and pancreatitis-associated lung injury. Kupffer cell inactivation by GdCh had less protective effect, although IL-6 and IL-10 concentrations were significantly decreased. The protective treatment brought by neutrophil depletion was not enhanced by Kupffer cell inactivation and both treatments did not combine their protective effects. CONCLUSION： Our results confirm the role of activated neutrophils in aggravating organ injury in acute pancreatitis while the role of Kupffer cell activation is less obvious.

Inhibition of allogeneic T-cell response by Kupffer cells expressing indoleamine 2,3-dioxygenase

AIM:To explore the possibility and mechanism of inhibiting allogeneic T-cell responses by Kupffer cells (KC)pretreated with interferon-γ(IFN-γ)in vitro. METHODS:The expressions of indoleamine 2,3-dioxygenase(IDO)mRNA and FasL mRNA in KC pretreated with IFN-γwere studied with real-time polymerase chain reaction(PCR).The catabolism of tryptophan by IDO from KC was analyzed by high performance liquid chromatography.Allogeneic T-cell response was used to confirm the inhibition of KC in vitro.The proliferation of lymphocytes was detected using[ 3 H]thymidine incorporation.Cell cycle and lymphocyte apoptosis were evaluated by flow cytometric assay. RESULTS:Real-time PCR revealed IDO mRNA and FasL mRNA expressions in KC pretreated with IFN-γ,and IDO catabolic effect was confirmed by a decrease in tryptophan and increase in kynurenine concentration. KC expressing IDO and FasL in BABL/c mice acquired the ability to suppress the proliferation of T-cells from C57BL/6,which could be blocked by addition of 1-methyl-tryptophan and anti-FasL antibody.KC expressing IDO could induce allogeneic T-cell apoptosisCONCLUSION:In addition to Fas/FasL pathway,IDO may be another mechanism for KC to induce immune tolerance.

Donor denervation and elimination of Kupffer cells affect expression of P-selectin and ICAM-1 in liver graft

BACKGROUND: The non-function and dysfunction of primary liver graft likely involves dependence on Kupffer cells and hepatic innervation. The present experiment was designed to study the expression of P-selectin and intercellular adhesion molecule-1 (ICAM-1) mRNA in liver graft and to elucidate the role of Kupffer cells and the sympathetic nerve of the liver in down-regulating this expression. METHODS: Donor rats were given hexamethonium, a sympathetic ganglionic blocking agent, and/or gadolinium chloride, an inhibitor of Kupffer cells. Then the changes of graft P-selectin and ICAM-1 mRNA expression were measured after liver transplantation. RESULTS: The expressions of P-selectin and ICAM-1 mRNA were increased after liver transplantation, and down-regulated by liver denervation and elimination of Kupffer cells. CONCLUSIONS: Live donor denervation and elimination of Kupffer cells down-regulated the expressions of P-selectin and ICAM-1 mRNA in grafts. This may decrease graft ischemia/reperfusion injury.

Role of Kupffer cells in acute hemorrhagic necrotizing pancreatitis-associated lung injury of rats

AIM： To investigate the role of Kupffer cells （KCs） in acute hemorrhagic necrotizing pancreatitis-associated lung injury （AHNP-U）. METHODS： Forty-two rats were allocated to four groups [sham operation, AHNP model, gadolinium chloride （GdCl3） pretreatment, GdCl3 control]. In GdCl3 pretreatment group, GdCl3 was administered by caudal vein injection 24 h before the AHNP model induction. Blood from the iliac artery, alveolar macrophages and tissues from the pancreas and lung, were collected in six animals per group 3 and 6 h after acute pancreatitis induction. TNF-α, IL-1 of Lserum, myeloperoxidase （MPO） of lung tissue, NF-κB activation of alveolar macrophages were detected. Serum AST and ALT in sham operation group and GdCl3 control group were tested. In addition, histopathological changes of the pancreas and lung were observed under light microscope. RESULTS： MPO of lung tissue and TNF-α, IL-1 levels of serum were all reduced significantly in GdCl3 pretreatment group compared to those in AHNP group （P〈0.01）. NF-KB activation of alveolar macrophages was also attenuated significantly in GdCl3 pretreatment group compared to that in AHNP group （P〈0.01）. The pathological injury of the lung was ameliorated obviously in GdCl3 pretreatment group compared to that in AHNP group. Nevertheless, the serum amylase level did not reduce and injury of the pancreas was not prevented in GdCl3 pretreatment group. CONCLUSION： Pulmonary injury induced by AHNP is mediated by KC activation and AHNP-LI can be significantly ameliorated by pretreatment with GdCh and KCs play a vital role in AHNP-LI.

Effects of Kupffer cell inactivation on graft survival and liver regeneration after partial liver transplantation in rats

BACKGROUND： Gadolinium chloride（Gd Cl3） selectively inactivates Kupffer cells and protects against ischemia/reperfusion and endotoxin injury. However, the effect of Kupffer cell inactivation on liver regeneration after partial liver transplantation（PLTx） is not clear. This study was to investigate the role of Gd Cl3 pretreatment in graft function after PLTx, and to explore the potential mechanism involved in this process.METHODS： PLTx（30% partial liver transplantation） was performed using Kamada’s cuff technique, without hepatic artery reconstruction. Rats were randomly divided into the control low-dose（5 mg/kg） and high-dose（10 mg/kg） Gd Cl3 groups. Liver injury was determined by the plasma levels of alanine aminotransferase and aspartate aminotransferase, liver regeneration by PCNA staining and Brd U uptake, apoptosis by TUNEL assay. IL-6 and p-STAT3 levels were measured by ELISA and Western blotting.RESULTS： Gd Cl3 depleted Kupffer cells and decreased animal survival rates, but did not significantly affect alanine aminotransferase and aspartate aminotransferase（P〉0.05）. Gd Cl3 pretreatment induced apoptosis and inhibited IL-6 overexpression and STAT3 phosphorylation after PLTx in graft tissues.CONCLUSION： Kupffer cells may contribute to the liver regeneration after PLTx through inhibition of apoptosis and activation of the IL-6/p-STAT3 signal pathway.

Protection against hepatic ischemia/reperfusion injury via downregulation of toll-like receptor 2 expression by inhibition of Kupffer cell function

AIM： To elucidate the mechanism of liver protection by inhibition of Kupffer cells （KCs） function.METHODS： All the animals were randomly divided into three groups. Blockade group （gadolinium chloride solution （GdCl3） injection plus ischemia/reperfusion （I/R） injury）：GdCl3 solution was injected once every 24 h for 2 d via the tail vein before I/R injury. Non-blockade group （saline solution injection plus I/R injury）： saline instead of GdCl3 as a control was injected as in the blockade group. Sham group： saline was injected without I/R injury. Liver samples were collected 4 h after blood inflow restoration. The blockade of the function of KCs was verified by immunostaining with an anti-CD68 mAb. Toll-like receptor2 （TLR2） was immunostained with a goat antimouse polydonal anti-TLR2 antibody. Membrane proteins were extracted from the liver samples and TLR2 protein was analyzed by Western blot. Portal vein serum and plasma were taken respectively at the same time point for further detection of the levels of tumor necrosis factor-α （TNF-α） and alanine aminotransferase （ALT）, an indicator of liver function.I/R injury via downregulation of theexpression of TLR2.RESULTS： Compared to non-blockade group, CD^68＋ cells significantly reduced in blockade group （OPTDI, optical density integral）： 32.97±10.55 vs 185.65±21.88, P〈0.01） and the liver function impairment was relieved partially （level of ALT： 435.89±178.37 U/L vs 890.21±272.91 U/L,P〈0.01）. The expression of TLR2 protein in blockade group significantly decreased compared to that in non- group（method of immunohistochemistry, OPDTI： 75.74±17.44 vs 170.58±25.14, P〈0.01; method of Western blot, A value： 125.89±15.49 vs 433.91±35.53, P〈0.02）. The latter correlated with the variation of CD68 staining （r = 0.745,P〈0.05）. Also the level of portal vein TNF-α decreased in blockade group compared to that in non-blockade group （84.45±14.73 ng/L vs 112.32±17.56 ng/L, P〈0.05）, butwas still higher than that in sham group （84.45±14.73 ng/L vs 6.07±5.33 ng/L, P〈0.01）.CONCLUSION： Inhibition of the function of KCs may protect liver against I/R injury via downregulation of the expression of TLR2.

Decreased phagocytic activity of Kupffer cells in a rat nonalcoholic steatohepatitis model

AIM: To investigate Kupffer cell dynamics and phagocytic activity,using a rat nonalcoholic steatohepatitis (NASH) model. METHODS: Male F344 rats were fed either a control diet or a choline-deficient L-amino acid-defined (CDAA) diet,followed by contrast enhanced ultrasonography (CEUS) using Levovist. The uptake of latex beads by the Kupffer cells was determined by fluorescent microscopy. The status of the Kupffer cells was compared between the two groups,using the immunohistochemical staining technique. RESULTS: After 4 or more wk of the CDAA diet,CEUS examination revealed a decrease in the signal intensity,20 min after intravenous Levovist. Fluorescent microscopic examination showed that the uptake of latex beads by the Kupffer cells was reduced at week 1 and 2 in the study group,compared with the controls,with no further reduction after 3 wk. Immunohistochemical staining revealed no significant difference in the Kupffer cell counts between the control group and the CDAA group. CONCLUSION: CEUS examination using Levovist demonstrated reduced contrast effect and phagocytic activity in the liver parenchymal phase,although the Kupffer cell numbers were unchanged,indicating reduced phagocytic function of the Kupffer cells in the rat NASH model. We believe that CEUS examination using Levovist is a useful screening modality,which can detect NASH in fatty liver patients.

Augmenter of liver regeneration promotes hepatocyte proliferation induced by Kupffer cells

AIM： To observe the effects of augmenter of liver regeneration （ALR） on Kupffer cells and to determine whether ALR promotes hepatocyte proliferation induced by Kupffer cells. METHODS： Kupffer cells and hepatocytes were cultured in vitro and various concentrations of recombinant rat ALR （rrALR） were added. ^3H-thymidine, BrdU and ^3H-leucine incorporation was determined in cultured Kupffer cells and hepatocytes, in hepatocytes conditioned by Kupffer cells, and in associated medium, rrALR was labeled by iodination and used to determine its binding activity by Scatchard analysis in Kupffer cells and primarily cultured rat hepatocytes. RESULTS： rrALR stimulated DNA replication in Kupffer cells and protein synthesis both in cells and in medium in a non-concentration-dependent manner. The effect was significant at the concentration of 1μg/L ALR. However, rrALR had no effect on primarily cultured hepatocytes, when hepatocytes were cultured with the Kupffer cell medium conditioned by ALR, DNA replication and protein synthesis in hepatocytes increased significantly at the concentration of 1μg/L ALR. When the ALR concentration was increased, its effect on hepatocyte proliferation decreased to the basal level. Scatchard analysis indicated the presence of a single class of high affinity receptors with a dissociation constant （Kd） of 0.883 nmol/L and a maximum binding capacity （Bmax） of 126.1 pmol/g protein in the rat Kupffer cells. CONCLUSION： ALR can promote hepatocyte proliferation induced by Kupffer cells, which is associated with the concentration of ALR, suggesting that Kupffer cells play a dual role in liver regeneration.

Effects of glycine on phagocytosis and secretion by Kupffer cells in vitro

AIM:To investigate the effects and mechanisms of action of glycine on phagocytosis and tumor necrosis factor(TNF)-α secretion by Kupffer cells in vitro. METHODS:Kupffer cells were isolated from normal rats by collagenase digestion and Percoll density gradient differential centrifugation.After culture for 24 h,Kupffer cells were incubated in fresh Dulbecco's Modification of Eagle's Medium containing glycine (G1:1 mmol/L,G2:10 mmol/L,G3:100 mmol/L and G4:300 mmol/L)for 3 h,then used to measure phagocytosis by a bead test,TNF-α secretion after lipopolysaccharide stimulation by radioactive immunoassay,and microfilament and microtubule expression by staining with phalloidin-fluorescein isothiocyanate (FITC)or a monoclonal anti-α tubulin-FITC antibody, respectively,and evaluated under a ultraviolet fluorescence microscope. RESULTS:Glycine decreased the phagocytosis of Kupffer cells at both 30 min and 60 min(P<0.01,P< 0.05).The numbers of beads phagocytosed by Kupffer cells in 30 min were 16.9±4.0(control),9.6±4.1(G1), 12.1±5.7(G2),8.1±3.2(G3)and 7.5±2.0(G4),and were 22.5±7.9(control),20.1±5.8(G1),19.3±4.8 (G2),13.5±4.7(G3)and 9.2±3.1(G4)after 60 min. TNF-α secretion by Kupffer cells in G1(0.19±0.03),G2 (0.16±0.04),G3(0.14±0.03)and G4(0.13±0.05) was significantly less than that in controls(0.26±0.03, P<0.01),and the decrease in secretion was dose-dependent(P<0.05).Microfilaments of Kupffer cells in G2, G3 and G4 groups were arranged in a disorderly manner. The fluorescence densities of microtubules in G1(53.4± 10.5),G2(54.1±14.6),G3(64.9±12.1)and G4(52.1 ±14.2)were all lower than those in the controls(102.2 ±23.7,P<0.01),but the decrease in microtubule fluorescence density was not dose-dependant. CONCLUSION:Glycine can decrease the phagocytosis and secretion by Kupffer cells in vitro,which may be related to the changes in the expression of microfilaments and microtubules induced by Kupffer cells.

Synthesis of platelet-activating factor and its receptor expression in Kupffer cells in rat carbon tetrachloride-induced cirrhosis

AIM:To determine the platelet-activating factor (PAF) synthesis and its receptor expression in Kupffer cells in rat carbon tetrachloride-induced cirrhosis. METHODS:Kupffer cells, isolated from the livers of control and CCl4-induced cirrhotic rats, were placed in serum-free medium overnight. PAF saturation binding, ET-1 saturation and competition binding were assayed. ET-1 induced PAF synthesis, mRNA expression of PAF, preproendothelin-1, endothelin A (ETA) and endothelin B (ETB) receptors were also determined. RESULTS:A two-fold increase of PAF synthesis (1.42 ± 0.14 vs 0.66 ± 0.04 pg/μg DNA) and a 1.48-fold increase of membrane-bound PAF (1.02 ± 0.06 vs 0.69 ± 0.07 pg/μg DNA) were observed in activated Kupffer cells of cirrhotic rats. The application of ET-1 to Kupffer cells induced PAF synthesis in a concentration-dependent manner in both cirrhotic and normal rats via ETB receptor, but PAF synthesis in the activated Kupffer cells was more effective than that in the normal Kupffer cells. In activated Kupffer cells, PAF receptor expression and PAF binding capacity were markedly enhanced. Activated Kupffer cells raised the [125I]-ET-1 binding capacity, but changed neither the affinity of the receptors, nor the expression of ETA receptor. CONCLUSION:Kupffer cells in the course of CCl4-induced cirrhosis are the main source of increased PAF. ET-1 is involved endogenously in stimulating the PAF synthesis in activated Kupffer cells via ETB receptor by paracrine. ETA receptor did not appear in activated Kupffer cells, which may exacerbate the hepatic and extrahepatic complications of cirrhosis.

Effects of Ca^(2+) channel blockers on store-operated Ca^(2+) channel currents of Kupffer cells after hepatic ischemia/reperfusion injury in rats

AIM： To study the effects of hepatic ischemia/ reperfusion （I/R） injury on store-operated calcium channel （SOC） currents （Isoc） in freshly isolated rat Kupffer cells, and the effects of Ca^2＋ channel blockers, 2-aminoethoxydiphenyl borate （2-APB）, SK＆F96365, econazole and miconazole, on Isoc in isolated rat Kupffer cells after hepatic I/R injury.METHODS： The model of rat hepatic I/R injury was established. Whole-cell patch-clamp techniques were performed to investigate the effects of 2-APB, SK＆F96365, econazole and miconazole on Isoc in isolated rat Kupffer cells after hepatic I/R injury.RESULTS： I/R injury significantly increased Isoc from -80.4±25.2pA to -159.5±34.5pA （^bp 〈 0.01, n = 30）. 2-APB （20, 40, 60, 80, 100 pmol/L）, SK＆F96365 （5, 10, 20, 40, 50 pmol/L）, econazole （0.1, 0.3, 1, 3, 10 μmol/L） and miconazole （0.1, 0.3, 1, 3, 10 μmol/L） inhibited Isoc in a concentration-dependent manner with IC50 of 37.41 μmol/L （n = 8）, 5.89 μmol/L （n = 11）, 0.21 μmol/L （n = 13）, and 0.28 μmol/L （n = 10）. The peak value of Isoc in the I-V relationship was decreased by the blockers in different concentrations, but the reverse potential of Isoc was not transformed. CONCLUSION： SOC is the main channel for the influx of Ca^2＋ during hepatic I/R injuries. Calcium channel blockers, 2-APB, SK＆F96365, econazole and miconazole,have obviously protective effects on I/R injury, probably by inhibiting Isoc in Kupffer cells and preventing the activation of Kupffer cells.