Liver sinusoidal endothelial cell injury by neutrophils in rats with acute obstructive cholangitis

Neutrophil-Induced Liver Injury and Interactions Between Neutrophils and Liver Sinusoidal Endothelial Cells

Neutrophils are the most abundant type of leukocytes with diverse functions in immune defense including production of reactive oxygen species, bacteriocidal proteins, neutrophil extracellular traps, and pro-inflammatory mediators. However, aberrant accumulation of neutrophils in host tissues and excessive release of bacteriocidal compounds can lead to unexpected injury to host organs. Neutrophil-mediated liver injury has been reported in various types of liver diseases including liver ischemia/reperfusion injury, nonalcoholic fatty liver disease, endotoxin-induced liver injury, alcoholic liver disease, and drug-induced liver injury. Yet the mechanisms of neutrophil-induced hepatotoxicity in different liver diseases are complicated. Current knowledge of these mechanisms are summarized in this review. In addition, a substantial body of evidence has emerged showing that liver sinusoidal endothelial cells (LSECs) participate in several key steps of neutrophil-mediated liver injury including neutrophil recruitment, adhesion, transmigration, and activation. This review also highlights the current understanding of the interactions between LSECs and neutrophils in liver injury. The future challenge is to explore new targets for selectively interfering neutrophil-induced liver injury without impairing host defense function against microbial infection. Further understanding the role of LSECs in neutrophil-induced hepatotoxicity would aid in developing more selective therapeutic approaches for liver disease.

Neutrophil recruitment mediated by sphingosine 1-phosphate (S1P)/S1P receptors during chronic liver injury

Excessive neutrophils are recruited to damaged tissue and cause collateral injury under chronic inflammatory conditions. Sphingosine 1-phosphate (S1P) modulates kinds of physiological and pathological actions by inducing recruitment of various cell types through S1P receptors (S1PRs). This study aimed to detect the S1P/S1PRs-mediated effects on neutrophil recruitment during chronic liver inflammation. In present study, increased neutrophils originated from bone marrow (BM) were detected in liver tissue of BDL-treated mice. Hepatic sphingosine kinase 1 (SphK, S1P rate-limiting enzyme) or S1P levels positively correlated with neutrophil marker expression in liver of mice and patients. In vitro, expression of S1PR₁, S1PR₂ and S1PR₃ were detected in both mouse BM neutrophils and differentiated human neutrophil-like (dHL60) cells. S1P powerfully boosted the migration and cytoskeletal remodeling of BM neutrophils through S1PR₁ or S1PR₂. Different from BM neutrophils, the migration and cytoskeletal remodeling of dHL60 cells were mediated by S1PR₂ or S1PR₃. S1PR₂ blockade obviously attenuates neutrophil infiltration in bile duct ligation (BDL)-induced mouse liver injury. In conclusion, S1P/S1PRs system plays a pivotal role in neutrophil recruitment.

Neutrophils contribute to spontaneous resolution of liver inflammation and fibrosis via microRNA-223

Persistent, unresolved inflammation in the liver represents a key trigger for hepatic injury and fibrosis in various liver diseases and is controlled by classically activated pro-inflammatory macrophages, while restorative macrophages of the liver are capable of reversing inflammation once the injury trigger ceases. Here we have identified a novel role for neutrophils as key contributors to resolving the inflammatory response in the liver. Using two models of liver inflammatory resolution, we found that mice undergoing neutrophil depletion during the resolution phase exhibited unresolved hepatic inflammation, activation of the fibrogenic machinery and early fibrosis. These findings were associated with an impairment of the phenotypic switch of pro-inflammatory macrophages into a restorative stage after removal of the cause of injury and an increased NLRP3 / miR-223 ratio. Mice with a deletion of the granulocyte specific miR-223 gene showed a similarly impaired resolution profile that could be reversed by restoring miR-223 levels using a miR-223 3p mimic or infusing neutrophils from wildtype animals. Collectively, our findings reveal a novel role for neutrophils in the liver as resolving effector cells that induce pro-inflammatory macrophages into a restorative phenotype, potentially via miR-223.

Establishment of a novel rat model of severe acute cholangitis

OBJECTIVES

This study aimed to establish a novel non-binding, reversible rat model of acute cholangitis of the severe type (ACST).

MATERIALS AND METHODS

Twenty-six rats were randomly divided into the sham-operated group (n=13) and the ACST group (n=13). All rats were intubated with a modified catheter through the external jugular vein. The ACST model was established by ligation of the distal bile duct, placing one end of a modified catheter in the common bile duct, and then injecting lipopolysaccharides from the other end of the catheter and sealing it. The common bile duct pressure was measured before and at 0, 24, 48, and 72 hr after the model was established; similarly, the levels of serum total bilirubin (TBIL), alanine aminotransferase (ALT), and tumor necrosis factor (TNF)-α were measured at 0, 12, 24, and 48 hr after the model was established.

RESULTS

Pathological examination of liver tissues was carried out at 24 and 72 hr. The common bile duct pressure increased gradually after the operation. Serum levels of TBIL, ALT, and TNF-α in the ACST group progressively increased and were significantly higher than those in the sham-operated group, at each time point (P<0.05).

CONCLUSION

Obvious pathological changes were observed in the liver tissue of rats in the ACST group. This model appears to reflect the early course of human ACST and thus, can be used in postoperative experimental studies of ACST.

Plausible role of naringenin against cerebrally implanted C6 glioma cells in rats

Gliomas encompass a significant percentage of intrinsic neoplasms of the central nervous system in both adults and children. The constitutive activation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B is the hallmark of glioma. The up-regulated protein kinase B could influence the expression of cyclooxygenase-2, an indicator of aggressive glioma. The present study was embarked to demonstrate the effect of naringenin (50 mg/kg bw for 30 days administrated orally) on PI3K, protein kinase B, and cyclooxygenase-2 in cerebrally implanted rat C6 glioma model. After the experimental period of 30 days, the animals were sacrificed and excised brain tissues were subjected to study the expressions of PI3K, protein kinase B, and cyclooxygenase-2 by reverse transcriptase polymerase chain reaction followed Western blot analysis. The activity of COX-2 (production of prostaglandin-E(2)) was also determined by high pressure liquid chromatography. The results showed that the naringenin could down-regulate the expressions of PI3K and protein kinase B along with activity and expression of cyclooxygenase-2 in C6 glioma cells implanted rat brain. In conclusion, it can be argued that the reduced expressions of phosphatidylinositol 3-kinase and protein kinase B in naringenin-treated glioma-induced rat brain might be involved in the down-regulation of cyclooxygenase-2 expression and activity. Thus, fine-tuned investigation of which will be helpful for targeted drug discovery against glioma.

Bile acids induce inflammatory genes in hepatocytes: a novel mechanism of inflammation during obstructive cholestasis

Inflammation contributes to liver injury during cholestasis. The mechanism by which cholestasis initiates an inflammatory response in the liver, however, is not known. Two hypotheses were investigated in the present studies. First, activation of Toll-like receptor 4 (TLR4), either by bacterial lipopolysaccharide or by damage-associated molecular pattern molecules released from dead hepatocytes, triggers an inflammatory response. Second, bile acids act as inflammagens, and directly activate signaling pathways in hepatocytes that stimulate production of proinflammatory mediators. Liver inflammation was not affected in lipopolysaccharide-resistant C3H/HeJ mice after bile duct ligation, indicating that Toll-like receptor 4 is not required for initiation of inflammation. Treatment of hepatocytes with bile acids did not directly cause cell toxicity but increased the expression of numerous proinflammatory mediators, including cytokines, chemokines, adhesion molecules, and other proteins that influence immune cell levels and function. Up-regulation of several of these genes in hepatocytes and in the liver after bile duct ligation required early growth response factor-1, but not farnesoid X receptor. In addition, early growth response factor-1 was up-regulated in the livers of patients with cholestasis and correlated with levels of inflammatory mediators. These data demonstrate that Toll-like receptor 4 is not required for the initiation of acute inflammation during cholestasis. In contrast, bile acids directly activate a signaling network in hepatocytes that promotes hepatic inflammation during cholestasis.

Segmental cholangitis impairs hepatic regeneration capacity after partial hepatectomy in rats

BACKGROUND

Patients with hilar cholangiocarcinoma or hepatolithiasis often develop segmental cholangitis (SC), but it is unclear whether hepatectomy for patients with SC can be performed safely.

METHODS

Rats were subjected to segmental bile duct ligation (SBDL) with LPS (SC group) or a saline (Sham group) infusion into the bile duct of the ligated lobes. The rats were sacrificed at 3, 24 and 48 h after the SBDL. For another experiment, the rats were subjected to partial hepatectomy (PHx) for the ligated lobes. Hepatic regeneration rates and the expression of regeneration-associated genes were evaluated.

RESULTS

In the SC group, severe parenchymal damage was observed in the acute phase (3 h). Altered gene expression in the liver in response to biliary infection occurred not only in the infected lobes but also in the non-infected lobes. In the rats of the SC group, both the hepatic regeneration rate and serum HGF levels were significantly lower than in the Sham group.

CONCLUSION

These results clearly demonstrate that SC impairs the regeneration capacity of the contralateral remnant liver. Therefore, hepatectomy should be avoided for patients with SC even if it occurs in the part of the liver to be resected.

15-deoxy-delta 12,14-prostaglandin J2 prevents inflammatory response and endothelial cell damage in rats with acute obstructive cholangitis

Acute obstructive cholangitis is a common disease with a high mortality rate. Ligands for peroxisome proliferator-activated receptor-gamma (PPARgamma), such as 15-deoxy-Delta(12,14)-prostaglandin J(2) (15D-PGJ(2)), have been proposed as a new class of anti-inflammatory compounds. This study investigated the effect of 15D-PGJ(2) treatment on lipopolysaccharide (LPS)-induced acute obstructive cholangitis. The rats were randomly assigned to five groups: sham operation (Sham; simple laparotomy), sham operation with intraperitoneal saline infusion (Sham+Saline), sham operation with intraperitoneal LPS infusion (Sham+LPS), bile duct ligation (BDL) with saline infusion into the bile duct (BDL+Saline), and BDL with LPS infusion into the bile duct (BDL+LPS). Biochemical assays of blood samples, histology of the liver, portal venous pressure, hyaluronic acid clearance, and expression of inflammation-associated genes in the liver were evaluated. Furthermore, the Sham+LPS and the BDL+LPS group were divided into two groups (with and without 15D-PGJ(2) treatment), and their survival rates were compared. Biochemical assays of blood samples, portal venous pressure, hyaluronic acid clearance, and expression of inflammation-associated genes in the liver were all significantly higher in the BDL+LPS group compared with those in the BDL+Saline group, indicating the presence of increased liver damage in the first group. However, preoperative administration of 15D-PGJ(2) significantly improved these outcomes. Furthermore, the survival rate after establishment of cholangitis was significantly improved by the administration of 15D-PGJ(2) in the BDL+LPS group. These results clearly demonstrate that 15D-PGJ(2) inhibits the inflammatory response and endothelial cell damage seen in acute obstructive cholangitis and could contribute to improve the outcome of this pathology.

Protection of Veratrum nigrum L. var. ussuriense Nakai alkaloids against ischemia-reperfusion injury of the rat liver

AIM: To investigate the protective effects and possible mechanisms of Veratrum nigrum L.var. ussuriense Nakai alkaloids (VnA) on hepatic ischemia/reperfusion (I/R) injury in rats.

METHODS: Forty male Wistar rats were randomly divided into four experimental groups (n = 10 in each): (A) Control group (the sham operation group); (B) I/R group (pretreated with normal saline); (C) Small-dose (10 μg/kg) VnA pretreatment group; (D) Large-dose (20 μg/kg) VnA pretreatment group. Hepatic ischemia/reperfusion (Hepatic I/R) was induced by occlusion of the portal vein and the hepatic artery for 90 min, followed by reperfusion for 240 min. The pretreatment groups were administered with VnA intraperitoneally, 30 min before surgery, while the control group and I/R group were given equal volumes of normal saline. Superoxide dismutase (SOD) activity, myeloperoxidase (MPO) activity and nitric oxide (NO) content in the liver tissue at the end of reperfusion were determined and liver function was measured. The expression of intercellular adhesion molecule-1 (ICAM-1) and E-selectin (ES) were detected by immunohistochemical examinations and Western blot analyses.

RESULTS: The results showed that hepatic I/R elicited a significant increase in the plasma levels of alanine aminotransferase (ALT: 74.53 ± 2.58 IU/L vs 1512.54 ± 200.76 IU/L, P < 0.01) and lactic dehydrogenase (LDH: 473.48 ± 52.17 IU/L vs 5821.53 ± 163.69 IU/L, P < 0.01), as well as the levels of MPO (1.97 ± 0.11 U/g vs 2.57 ± 0.13 U/g, P < 0.01) and NO (69.37 ± 1.52 μmol/g protein vs 78.39 ± 2.28 μmol/g protein, P < 0.01) in the liver tissue, all of which were reduced by pretreatment with VnA, respectively (ALT: 1512.54 ± 200.76 IU/L vs 977.93 ± 89.62 IU/L, 909.81 ± 132.76 IU/L, P < 0.01, P < 0.01; LDH: 5821.53 ± 163.69 IU/L vs 3015.44 ± 253.01 IU/L, 2448.75 ± 169.4 IU/L, P < 0.01, P < 0.01; MPO: 2.57 ± 0.13 U/g vs 2.13 ± 0.13 U/g, 2.07 ± 0.05 U/g, P < 0.01, P < 0.01; NO: 78.39 ± 2.28 μmol/g protein vs 71.11 ± 1.73 μmol/g protein, 68.58 ± 1.95 μmol/g protein, P < 0.05, P < 0.01). The activity of SOD (361.75 ± 16.22 U/mg protein vs 263.19 ± 12.10 U/mg protein, P < 0.01) in the liver tissue was decreased after I/R, which was enhanced by VnA pretreatment (263.19 ± 12.10 U/mg protein vs 299.40 ± 10.80 U/mg protein, 302.09 ± 14.80 U/mg protein, P < 0.05, P < 0.05). Simultaneously, the histological evidence of liver hemorrhage, polymorphonuclear neutrophil infiltration and the overexpression of ICAM-1 and E-selectin in the liver tissue were observed, all of which were attenuated in the VnA pretreated groups.

CONCLUSION: The results demonstrate that VnA pretreatment exerts significant protection against hepatic I/R injury in rats. The protective effects are possibly associated with enhancement of antioxidant capacity, reduction of inflammatory responses and suppressed expression of ICAM-1 and E-selectin.

Hepatocellular apoptosis after hepatectomy in obstructive jaundice in rats

AIM: To investigate the hepatocellular apoptosis after hepatectomy in obstructive jaundice and biliary decompression rats.

METHODS: After bile duct ligation for 7 days, rats were randomly divided into OB group in which the rats underwent 70% hepatectomy, OB-CD group in which the rats underwent hepatectomy accompanied by choledochoduodenostomy, CD-Hx group in which the rats underwent choledochoduodenostomy and then received 70% hepatectomy on the fifth day after biliary decompression. The control group (Hx group) only underwent hepatectomy.

RESULTS: The level of total serum bilirubin and serum enzymes was significantly lower in CD-Hx group than in OB-CD and OB groups on day 1, 3 and 5 after hepatectomy. The apoptotic index was significantly lower in CD-Hx group than in OB-CD and OB groups on day 3 and 5. The oligonucleosomal DNA fragments and Caspase-3 activity were also lower in CD-Hx group than in OB-CD and OB groups 3 days after hepatectomy, without differences between CD-Hx and Hx groups.

CONCLUSION: Hepatocellular apoptosis plays vital roles in jaundice rats, and biliary decompression is more effective in treatment of patients with severe jaundice before operation.

Synthesis of endotoxin receptor CD14 protein in Kupffer cells and its role in alcohol-induced liver disease

AIM

To observe the synthesis of endotoxin receptor CD14 protein and its mRNA expression in Kupffer cells (KCs), and evaluate the role of CD14 in the pathogenesis of liver injury in rats with alcohol-induced liver disease (ALD).

METHODS

Twenty-eight Wistar rats were divided into two groups: ethanol-fed group and control group. Ethanol-fed group was fed ethanol (dose of 5g-12 g/kg/d) and control group received dextrose instead of ethanol. Two groups were sacrificed at 4 wk and 8 wk, respectively. KCs were isolated and the synthesis of CD14 protein and its mRNA expression in KCs were determined by flow cytometric analysis (FCM) or the reverse transcription polymerase chain reaction (RT-PCR) analysis. The levels of plasma endotoxin and alanine transaminase (ALT) were measured by Limulus Amebocyte Lysate assay and standard enzymatic procedures respectively, and the levels of plasma tumor necosis factor (TNF)-alpha and interleukin (IL)-6 were both determined by ELISA. The liver pathology change was observed under light and electric microscopy.

RESULTS

In ethanol-fed group, the percentages of FITC-CD14 positive cells were 76.23 % and 89.42 % at 4 wk and 8 wk, respectively. Compared with control group (4.45 % and 5.38 %), the difference was significant (P<0.05). The expressions of CD14 mRNA were 7.56+/-1.02 and 8.74+/-1.37 at 4 wk and 8 wk, respectively, which were significantly higher compared with the control group (1.77+/-0.21 and 1.98+/-0.23) (P<0.05). Plasma endotoxin levels at 4 wk and 8 wk increased significantly in ethanol-fed group (129+/-21 ng/L and 187+/-35 ng/L) than those in control rats (48+/-9 ng/L and 53+/-11 ng/L)(P<0.05). Mean values of plasma ALT levels increased dramatically in ethanol-fed rats (112+/-15 IU/L and 147+/-22 IU/L) than those in the control animals (31+/-12 IU/L and 33+/-9 IU/L) (P<0.05). In ethanol-fed rats, the levels of TNF-alpha were 326+/-42 ng/L and 402+/-51 ng/L at 4 wk and 8 wk, respectively which were significantly higher than those in control group (86+/-12 ng/L and 97+/-13 ng/L) (P<0.05). The levels of IL-6 were 387+/-46 ng/L and 413+/-51 ng/L, which were also higher than control group (78+/-11 ng/Land 73+/-10 ng/L) (P<0.05). In liver section from ethanol-fed rats, there were marked pathological changes including steatosis, cell infiltration and necrosis. No marked pathological changes were seen in control group.

CONCLUSION

Ethanol administration led to a significant synthesis of endotoxin receptor CD14 protein and its gene expression in KCs, which maybe result in the pathological changes of liver tissue and hepatic functional damages.

Role of NF-kB in multiple organ dysfunction during acute obstructive cholangitis

AIM

To elucidate the role of NF-kB activation in the development of multiple organ dysfunction (MOD) during acute obstructive cholangitis (AOC) in rats.

METHODS

Forty-two Wistar rats were divided into three groups: the AOC group, the group of bile duct ligation (BDL group), and the sham operation group (SO group). All the animals in the three groups were killed in the 6th and 48th hour after operation. Morphological changes of vital organs were observed under light and electron microscopy. NF-kB activation was determined with Electrophoretic Mobility Shift Assay (EMSA). Arterial blood gas analyses and the serum levels of lactate dehydrogenase (LDH), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine were performed. The concentrations of TNF-alpha and IL-6 in plasma were also measured.

RESULTS

The significant changes of histology and ultrastructure of vital organs were observed in AOC group. By contrast, in BDL group, all the features of organs damage were greatly reduced. Expression of NF-kB activation in various tissues increased in AOC group when compared to other two groups. At 6 h, the arterial pH in three groups was 7.52+/-0.01, 7.46+/-0.02, and 7.45+/-0.02, and the blood pCO(2) was 33.9+/-0.95 mmHg, 38.1+/-0.89 mmHg, 38.9+/-0.94 mmHg, there was difference in three groups (P<0.05). At 48 h, the blood pH values in three groups was 7.33+/-0.07, 7.67+/-0.04, and 7.46+/-0.03, and blood HCO(3)(-) was 20.1+/-1.29 mmol x L(-1), 26.7+/-1.45 mmol x L(-1) and 27.4+/-0.35 mmol x L(-1), there was also difference in three groups (P<0.05). In AOC group, Levels of LDH, ALT, BUN and creatinine were 1,6359.9+/-2,278.8 nkat x L(-1), 5,796.2+/-941.9 nkat.L(-1), 55.7+/-15.3 mg/dl, and 0.72+/-0.06 mg/dl, which were higher than in SO group (3,739.1+/- 570.1 nkat x L(-1), 288.4+/-71.7 nkat x L(-1), 12.5+/-2.14 mg/dl, and 0.47+/-0.03 mg/dl) (P<0.05). Levels of plasma TNF-alpha and IL-6 in AOC at 48 h were 429+/-56.62 ng x L(-1) and 562+/-57 ng x L(-1), which increased greatly when compared to BDL group (139+/-16 ng x L(-1), 227+/-43 ng x L(-1)) and SO group (74+/-10 ng x L(-1), 113+/-19 ng x L(-1)) (P<0.05).

CONCLUSION

The pathological damages and the NF-kB activation of many vital organs excised during AOC. These findings have an important implication for the role of NF-kB activation in MOD during AOC.

Effect of N-desulfated heparin on hepatic/renal ischemia reperfusion injury in rats

AIM: To investigate the effect of N-desulfated heparin on hepatic/renal ischemia and reperfusion injury in rats.

METHODS: Using rat models of 60 min hepatic or renal ischemia followed by 1 h, 3 h, 6 h and 24 h reperfusion, animals were randomly divided into following groups, the sham operated controls, ischemic group receiving only normal saline, and treated group receiving N-desulfated heparin at a dose of 12 mg/kg at 5 min before reperfusion. P-selectin expression was detected in hepatic/renal tissues with immunohistochemistry method.

RESULTS: P-selectin expression, serum ALT, AST, BUN and Cr levels were significantly increased during 60 minute ischemia and 1 h, 3 h, 6 h and 24 h reperfusion, while the increment was significantly inhibited, and hepatic/renal pathology observed by light microscopy was remarkably improved by treatment with the N-desulfated heparin. Furthermore, the heparin was found no effects on PT and KPTT.

CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion. The N-desulfated heparin might prevent hepatic/renal damage induced by ischemia and reperfusion injury without significant anticoagulant activity.

Intestinal damage mediated by Kupffer cells in rats with endotoxemia

AIM

To determine the in vivo effects of phagocytic blockade of Kupffer cell (KC) on the release of proinflammatory cytokines in small intestinal lesion and on the integrity of intestinal tract by using gadolinium chloride (GdCl(3)) during early endotoxemia.

METHODS

Wistar rats were divided into three groups: Group A, rats were injected with endotoxin (E. coli O111:B(4), a dose of 12 mg x kg(-1)) only; Group B, rats were pretreated intravenously with 25 mg of GdCl(3) per kg 24 h are given endotoxin; and Group C, sham operation only. All animals were sacrificed 4 h after endotoxin injection. In portion of the rats of three groups, bile duct was cannulated, which the bile was collected externally. Morphological changes of ileum were observed under light microscopy and electronic microscopy. The KC were isolated from rats by collagenase perfusion and in KC, expression of TNF-alpha and IL-6 mRNA were determined by RT-PCR analysis. Plasma and bile TNF-alpha and IL-6 Levels were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In group A, there were neutrophil infiltration and superficial epithelial necrosis of the ileal villi, sloughing of mucosal epithelium, and disappearance of some villi. In group B, the ileal mucosal damage was much reduced. which in group C, no significant morphological changes were seen. GdCl(3) pretreatment decreased significantly the expression of TNF-alpha and IL-6 mRNA in group B (4.32+/-0.47 and 4.05+/-0.43) when compared to group A (9.46+/-1.21 and 9.04+/-1.09) (P<0.05). There was no significant expression of TNF-alpha and IL-6 mRNA in group C (1.03+/-0.14 and 10.4+/-0.13). In rats of group A, the levels of TNF-alpha and IL-6 in bile and plasma were 207+/-29 ng x L(-1), 1032+/-107 ng x L(-1), 213+/-33 ng x L(-1), and 1185+/-127 ng x L(-1), respectively. In group B, they were 113+/-18 ng x L(-1), 521+/-76 ng x L(-1), 147+/-22 ng x L(-1), and 572+/-54 ng x L(-1), respectively. In group C, they were 67+/-10 ng x L(-1), 72+/-13 ng x L(-1), 109+/-18 ng x L(-1), and 118+/-22 ng x L(-1) respectively. There were significant difference between the three group (P<0.05).

CONCLUSION

KC release cytokines TNF-alpha and IL-6 causing damage to the integrity of intestinal epithelium and play a crucial role in the initiation and progression of intestinal mucosal damage during early endotoxemia.

Subcellular daunorubicin distribution and its relation to multidrug resistance phenotype in drug-resistant cell line SMMC-7721/R

AIM: To investigate the correlation between subcellular daunorubicin distribution and the multidrug resistance phenotype in drug-resistant cell line SMMC-7721/R.

METHODS: The multidrug resistant cell line SMMC-7721/R, a human hepatocellular carcinoma cell line, was established. Antisense oligonucleotides (AS-ODN) were used to obtain different multidrug resistance phenotypes by inhibiting the expression of mdr1 gene and/or multidrug resistance-related protein gene (mrp) using Lipofectamine as delivery agent. Expression of mdr1 and mrp genes was evaluated by RT-PCR and Western blotting. Intracellular daunorubicin (DNR) concentration was measured by flow cytometry. Subcellular DNR distribution was analyzed by confocal laser scanning microscopy. Adriamycin (ADM) and DNR sensitivity was examined by MTT method.

RESULTS: Low level expression of mdr1 and mrp mRNAs and no expression of P-Glycoprotein (P-gp) and multidrug resistance-related protein (P₁₉₀) were detected in parental sensitive cells SMMC-7721/S, but over-expression of these two genes was observed in drug-resistant cell SMMC-7721/R. The expression of mdr1 and mrp genes in SMMC-7721/R cells was down-regulated to the level in the SMMC-7721/S cells by AS-ODN. Intracellular DNR concentration in SMMC-7721/S cells was 10 times higher than that in SMMC-7721/R cells. In SMMC7721/S cells intracellular DNR distributed evenly in the nucleus and cytoplasm, while in SMMC-7721/R cells DNR distributed in a punctate pattern in the cytoplasm and was reduced in the nucleus. DNR concentration in SMMC-7721/R cells co-transfected with AS-ODNs targeting to mdr1 and mrp mRNAs recovered to 25 percent of that in SMMC7721/S cells. Intracellular DNR distribution pattern in drug-resistant cells treated by AS-ODN was similar to drug-sensitive cell, and the cells resistance index (RI) to DNR and ADM decreased at most from 88.0 and 116.0 to 4.0 and 2.3, respectively. Co-Transfection of two AS-ODNs showed a stronger synergistic effect than separate transfection.

CONCLUSIONS: P-gp and P₁₉₀ are two members mediating MDR in cell line SMMC7721/R. Intracellular drug concentration increase and subcellular distribution change are two important factors in multidrug resistance (MDR) formation. The second factor, drugs transport by P-gp and P₁₉₀ from cell nucleus to organell in cytoplasm, may play a more important role.

Expression of CD14 protein and its gene in liver sinusoidal endothelial cells during endotoxemia

AIM

To observe expression of CD14 protein and CD14 gene in rat liver sinusoidal endothelial cells (LSECs) during endotoxemia, and the role of CD14 protein in the activation of lipopolysaccharide (LPS)-induced LSECs.

METHODS

Wistar rat endotoxemia model was established first by injection of a dose of LPS (5mg/kg, Escherichia coli O111:B4 ) via the tail vein, then sacrificed after 0 h,3h,6h, 12h, and 24h, respectively. LSECs were isolated from normal and LPS-injected rats by an in situ collagenase perfusion technique. The isolated LSECs were incubated with rabbit anti-rat CD14 polyclonal antibody, then stained with goat anti rabbit IgG conjugated fluorescein isothiocyanate(FITC) and flow cytometric analysis (FCM) was performed. The percentage and mean fluorescence intensity (MFI) of CD14-positive cells were taken as the indexes. LSECs were collected to measure the expression of CD14 mRNA by in situ hybridization analysis. The isolated LSECs from normal rats were incubated firstly with anti-CD14 antibody, then stimulated with different concentrations of LPS, and the supernatants of these cells were then collected for measuring the levels of tumor necrosis factor (TNF)-a and Interleukin (IL)-6 with ELISA.

RESULTS

In rats with endotoxemia, LSECs displayed a strong MFI distinct from that of control rats. CD14 positive cells in rats with endotoxemia were 54.32%, 65.83%, 85.64%, and 45.65% at 3h, 6h, 12h, and 24h respectively, there was significant difference when compared to normal group of animals (4.45%)(P<0.01). The expression of CD14 mRNA in isolated LSECs was stronger than that in control rats. In LPS group, the levels of TNF-alpha and IL-6 were 54+/-6 ng.L(-1), 85+/-9 ng.L(-1), 206+/-22 ng.L(-1), 350+/-41 ng.L(-1), 366+/-42 ng.L(-1) and 103+/-11 ng.L(-1), 187+/-20 ng.L(-1), 244+/-26 ng.L(-1), 290+/-31 ng.L(-1), and 299+/-34 ng.L(-1), respectively at different concentration points. In anti-CD14 group, the levels of TNF-alpha and IL-6 were 56+/-5 ng.L(-1), 67+/-8 ng.L(-1), 85+/-10 ng.L(-1), 113+/-12 ng.L(-1), 199+/-22 ng.L(-1) and 104+/-12 ng.L(-1), 125+/-12 ng.L(-1), 165+/-19 ng.L(-1), 185+/-21 ng.L(-1), and 222+/-23 ng.L(-1), respectively at different concentration points. There was significant difference between the two groups (P<0.01).

CONCLUSION

LSECs can synthesize CD14 protein and express CD14 gene during endotoxemia. CD14 protein plays an important role in the activation of LPS-induced LSECs. This finding has important implications for the understanding of the mechanisms by which LPS may injure liver sinusoidal endothelial cells during sepsis.