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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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.

Expression of macrophage inflammatory protein-1αin Kupffer cells following liver ischemia or reperfusion injury in rats

AIM： To explore the expression of macrophage inflammatory protein-1α （MIP-1α） in Kupffer cells （KCs） following liver ischemia/reperfusion injury IRI in rats. METHODS： Forty male SD rats were divided randomly into five groups. A model of partial warm ischemia/ reperfusion injury in the rat liver was established. KCs were isolated and incubated one hour, six hours, 12 h, and 24 h after the reperfusion. Tumor necrosis factor alpha （TNF-α） and interleukin-lbeta （IL-1β） in the supernatants were measured by ELISA. MIP-1α in KCs was detected by immunocytochemical and RT-PCR. RESULTS： No or few MIP-1α protein and mRNA were expressed in the KCs of the control group. Its expression in the IRI group had a significant increase after the reperfusion （P 〈 0.05）, which was contrary to the control group. CONCLUSION： The active behavior of the MIP-1α gene in KCs following liver ischemia/reperfusion injury is assumed to be one of the major causes for the hepatic ischemia/reperfusion injury.

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.

Prokineticin 2/Bv8 is expressed in Kupffer cells in liver and is down regulated in human hepatocellular carcinoma

AIM： TO study the implication of prokineticin 1 （PKI/EGVEGF） and prokineticin 2 （PK2/13v8） in hepatocellular carcinoma angiogenesis.METHODS： The gene induction of PK1/EG-VEGF and PK2/Bv8 was investigated in 10 normal, 28 fibrotic and 28 tumoral livers by using real time PCR. Their expression was compared to the expression of VEGF （an angiogenesis marker）, vWF （an endothelial cell marker） and to CD68 （a monocyte/macrophage marker）. Furthermore, the rnRNA levels of PK1/EG-VEGF, PK2/Bv8, prokineticin receptor 1 and 2 were evaluated by real time PCR in isolated liver cell populations. Finally, PK2/Bv8 protein was detected in normal liver paraffin sections and in isolated liver cells by immunohistochernistry and immunocytochemistry.RESULTS： PK2/Bv8 mRNA but not PK1/EG-VEGF was expressed in all types of normal liver samples examined. In the context of liver tumor development, we reported that PK2/13v8 correlates only with CD68 and showed a significant decrease in expression as the pathology evolves towards cancer. Whereas, VEGF and vWF mRNA were significantly upregulated in both fibrosis and HCC,as expected. In addition, out of all isolated liver cells examined, only Kupffer cells （liver resident macrophages） express significant levels of PK2/Bv8 and its receptors, prokineticin receptor 1 and 2.CONCLUSION： In normal liver PK2/Bv8 and its receptors were specifically expressed by Kupffer cells. PK2/Bv8 expression decreased as the liver evolves towards cancer and did not correlate with HCC angiogenesis.

Effect of aging on cytoskeleton system of Kupffer cell and its phagocytic capacity

IM To investigate the agerelated alterations of cytoskeleton system in liver Kupffer cell and their relation to the changed phagocytic function.METHODS The phagocytic function of Kupffer cells from rats of various ages (6mo, 12mo, 18mo and 24mo) were quantitatively evaluated by phagocytosis of polystyrene beads. The actin distribution and measurement of Kupffer cell were determined by a phalloidinTRITC method; and the myosin and vimentin distribution and measurement with indirect immunochemical staining.RESULTS Aging resulted in significant alterations of actin, myosin and vimentin distributions and reductions in Kupffer cell; the 3 cytoskeleton components of 24moold Kupffer cell were significantly decreased to 680%, 849% and 755%, respectively of these of 6moold Kupffer cell(P<001,001 and 001). And these decreases had significant positive relations with the damaged phagocytosis of the aged Kupffer cell. γ values were 096(P<005), 099(P<001) and 095 (P<005) respectively.CONCLUSION The cytoskeleton system of the aged Kupffer cell presents an evident state of senescence, which may be an important mechanism of decreased phagocytosis of the aged Kupffer cell..

M2-like Kupffer cells in fibrotic liver may protect against acute insult

AIM To investigate the mechanism of hepatoprotection conferred by liver fibrosis through evaluating the activation phenotype of kupffer cells.METHODS Control and fibrotic mice were challenged with a lethal dose of D-Gal N/lipopolysaccharide(LPS),and hepatic damage was assessed by histology,serum alanine transferase(ALT)levels,and hepatic expression of HMGB1,a potent pro-inflammatory mediator.The localization of F4/80(a surrogate marker of KCs),HMGB1,and type I collagen(Col-1)was determined by immunofluorescence staining.The phenotype of KCs was characterized by real-time PCR.KCs isolated from control or fibrotic mice were challenged with LPS or HMGB1 peptide,and HMGB1 translocation was analyzed.RESULTS Liver fibrosis protected mice against D-Gal N/LPS challenge,as shown by improved hepatic histology and reduced elevation of ALT compared with the normal mice treated in the same way.This hepatoprotection was also accompanied by inhibition of HMGB1 expression in the liver.Co-localization of F4/80,HMGB1,and Col-1 was found in fibrotic livers,indicating the close relationship between KCs,HMGB1 and liver fibrosis.KCs isolated from fibrotic mice predominantly exhibited an M2-like phenotype.In vitro experiments showed that HMGB1 was localized in the nucleus of the majority of M2-like KCs and that the translocation of HMGB1 was inhibited following stimulation with LPS or HMGB1 peptide,while both LPS and HMGB1 peptide elicited translocation of intranuclear HMGB1 in KCs isolated from the control mice.CONCLUSION M2-like Kupffer cells in fibrotic liver may exert a protective effect against acute insult by inhibiting the translocation of HMGB1.

Kupffer cells contribute to concanavalin A-induced hepatic injury through a Th1 but not Th17 type response-dependent pathway in mice

BACKGROUND:Increasing evidence suggests that a close interaction of Kupffer cells with T cells plays a central role in concanavalin A-induced hepatic injury in mice,but the underlying mechanisms remain obscure.The present study aimed to determine the relative roles of Th1 and Th17 type responses in concanavalin A-induced hepatic injury in mice, and to investigate whether or not Kupffer cells contribute to hepatic injury via a Th1 or Th17 type response-dependent pathway. METHODS:Immune-mediated hepatic injury was induced in C57BL/6 mice by intravenous injection of concanavalin A. Kupffer cells were inactivated by pretreatment with gadolinium chloride 24 hours before the concanavalin A injection.The interferon-gamma(IFN-γ)and interleukin-17(IL-17)pathways were blocked by specific neutralizing antibodies.Hepatic injury was assessed using serum transferase activity and pathological analysis.Expression of inflammatory cytokines within the liver was detected by real-time polymerase chain reaction and immunohistochemistry. RESULTS:Neutralization of IFN-γsignificantly attenuated concanavalin A-induced hepatic injury.However,neutralization of IL-17 failed to suppress the injury.Inactivation of Kupffer cells by gadolinium chloride pretreatment protected against concanavalin A-induced injury and significantly reduced hepatic cytokine levels including TNF-α,IL-6 and IFN-γbut not IL-17.CONCLUSION:Our findings suggest that Kupffer cells contribute to concanavalin A-induced hepatic injury via a Th1 type response-dependent pathway and production of inflammatory cytokines including TNF-α,IL-6 and IFN-γ.