NFκB inhibition decreases hepatocyte proliferation but does not alter apoptosis in obstructive jaundice

Simvastatin augments activation of liver regeneration through attenuating transforming growth factor-β1 induced-apoptosis in obstructive jaundice rats

Obstructive jaundice, owing to biliary obstruction, has been illustrated to trigger various biochemical, histological and immunological changes, leading to liver damage or even failure. The detailed molecular mechanism of simvastatin (Sim) involvement in liver regeneration during obstructive jaundice progression remains poorly elucidated. In the present study, an acute obstructive jaundice rat model was established by ligation and division of common bile duct, which was used to investigate the effects of Sim as a hepatoprotective treatment. Male Sprague-Dawley rats were randomly divided into four groups: Sham-operated, bile duct ligation (BDL) plus saline treatment [0.02 mg/kg/d, intraperitoneally (i.p.)], BDL plus low-dose Sim treatment (0.02 mg/kg, i.p.) and BDL plus high-dose Sim treatment (0.2 mg/kg, i.p.). During this experiment, the BDL+normal saline (NS) group demonstrated increased levels of transforming growth factor-β1 (TGF-β1) expression. Furthermore, Sim-treated animals demonstrated significantly downregulated TGF-β1 expression and improved liver function vs. the BDL+NS group, indicating a TGF-β1 antagonizing function. Additionally, Sim increased hepatocyte DNA synthesis in BDL rats compared to both the BDL+NS and Sham group. Apoptosis was increased in BDL+NS compared to the Sham group, and Sim markedly reduced hepatocyte apoptosis in the BDL group. Moreover, analysis of TGF-β1 signaling pathways demonstrated that there was an increased hepatic TGF-β1 and Smad3 expression in the BDL group, which was attenuated in the presence of Sim. In contrast to TGF-β1, Sim induced the activity of the Smad7 (an inhibitor of TGF-β1 signaling) mRNA and Smad7 protein expression. Sim displays hepatoprotective effects in liver cells via the upregulation of Smad7 expression and impaired TGF-β signaling. Furthermore, the observations of the present study may provide evidence on the mechanism behind Sim blunting TGF-β1 signaling, which is used to ameliorate the complication of liver damage and reduce the mortality rates associated with obstructive jaundice.

Molecular mechanisms of hepatic apoptosis regulated by nuclear factors

Apoptosis is a prominent characteristic in the pathogenesis of liver disease. The mechanism of hepatic apoptosis is not well understood. Hepatic apoptosis alters relative levels of nuclear factors such as Foxa2, NF-κB, C/EBPβ, and p53. Regulation of nuclear factors modulates the degree of hepatic apoptosis and the progression of liver disease. Nuclear factors have distinctive mechanisms to mediate hepatic apoptosis. The modification of nuclear factors is a novel therapeutic strategy for liver disease as demonstrated by pre-clinical models and clinical trials.

Hepatocyte nuclear factor-kappa beta (NF-kappaB) activation is protective but is decreased in the cholestatic liver with endotoxemia

BACKGROUND

Obstructive jaundice (OJ) is an important clinical consideration associated with a high risk of bacteremia. Hepatocyte nuclear factor-kappa B (NF-kappaB) activation confers an antiapoptotic function. Although the occurrence of hepatocyte apoptosis has been shown in OJ, the activation and role of NF-kappaB over the time course of OJ in conjunction with endotoxemia have not yet been well defined. We hypothesized that NF-kappaB activation may be decreased over the time course of OJ and endotoxemia, which leads to severe liver injury. The aim of the current study was to examine whether NF-kappaB activation can decrease hepatocyte apoptosis and liver injury over the time course of OJ in response to lipopolysaccharide (LPS) administration.

METHODS

Male C57BL/6 mice were subjected to bile duct ligation and were administered LPS intravenously at 3 days (OJ3) or 14 days (OJ14) after bile duct ligation. NF-kappaB activation; protein expressions of NF-kappaB p65, IkappaB-alpha, Ikappabeta-b, and Pin1; immunohistochemistry of poly adenosine diphosphate (ADP)-ribose polymerase p85 fragment (PARP); and serum alanine transaminase (ALT) levels were examined.

RESULTS

Hepatocyte NF-kappaB activation was observed during OJ. After LPS administration, the hepatic NF-kappaB activation defined by electrophoretic mobility shift assay was decreased in the OJ14 group compared with the OJ3 group, which is consistent with a decrease in NF-kappaB p65 protein expression. Changes in phosphorylated Ikappa-B-beta but not phosphorylated IkappaB-alpha mirrored these results. Significant hepatocyte apoptosis defined by PARP immunohistochemistry was observed in the LPS-treated OJ14 relative to the LPS-treated OJ3. Hepatic expressions of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in the LPS OJ14 mice were upregulated relative to those in the LPS OJ3. Serum ALT levels increased significantly in the LPS OJ14 relative to other mice. The survival rate was significantly less in the LPS OJ14 relative to other mice.

CONCLUSION

After prolonged OJ, exposure to endotoxemia was associated with a decrease in hepatocyte NF-kappaB activation and an increase in hepatocyte apoptosis and secondary necrosis, thus resulting in liver dysfunction.

Protective effect and mechanisms of radix astragali injection on the intestinal mucosa of rats with obstructive jaundice

Objective. To research the protective effects and mechanisms of Radix Astragali injection on the intestinal mucosa of rats with obstructive jaundice (OJ). Methods. The rats were randomly divided into sham-operated, model control and Radix Astragali treated group. We observed the pathological changes of intestinal mucosa, expression levels of Bax and NF-κB proteins, and apoptosis indexes in intestinal mucosa as well as serum NO, MDA and SOD contents, respectively, on 7d, 14d, 21d and 28d after operation. Results. The pathological severity score (on 7d and 14d), apoptotic indexes (on 14d) of the intestinal mucosa and serum MDA content (on 14d) of treated group were significantly lower than those in the model control group (P < .05). The serum SOD contents (on all time points) of treated group were significantly higher than those in the model control group (P < .05). The sham-operated group (on 21d) of the product of staining intensity and positive rate of Bax protein was significantly lower than model control group (P < .05). Conclusion. Radix Astragali injection could protect the intestinal mucosa of OJ rats by increasing the content of SOD, reducing the content of MDA, inhibiting the apoptosis and relieving the pathological changes of intestinal mucosa.

Effect of the combination of fibrin glue and growth hormone on intestinal anastomoses in a pig model of traumatic shock associated with peritonitis

BACKGROUND

Intra-abdominal sepsis and hemorrhagic shock have been found to impair the healing of intestinal anastomoses. The present study examined whether fibrin glue (FG) and recombinant human growth hormone (GH) can improve intestinal primary anastomotic healing in a pig model of traumatic shock associated with peritonitis. Further, the study was designed to investigate the probable mechanism of these agents.

METHODS

Female anesthetized pigs were divided into five groups. Group sham (n = 7), pigs without traumatic shock had small bowel resection anastomoses; group control (n = 14), pigs had bowel resection anastomoses 24 h after abdominal gunshot plus exsanguination/resuscitation; group FG (n = 14); group GH (n = 14); group FG/GH (n = 14), pigs received FG, recombinant GH, or both, respectively. Recombinant GH was given daily for 7 days. Blood samples were collected daily for measurement of interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha levels. Investigations also included adhesion formation, anastomotic bursting pressure, tensile strength, hydroxyproline (HP) content, myeloperoxidase (MPO), tumor necrosis factor (NF)-kappaB activity, and histology analysis 10 days later. A second experiment (n = 20 subjects assigned to each of the five groups) was designed to study survival during the first 20 postoperative days.

RESULTS

Traumatic shock associated with peritonitis led to significant decreases in intestinal anastomotic bursting pressures, tensile strengths, and tissue hydroxyproline content, along with severe adhesion formation, increases in MPO activity and NF-kappaB activity, and plasma levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Both FG and recombinant GH treatment led to early significant increases in plasma levels of TNF-alpha and IL-6. At the same time, FG alone, unlike recombinant GH alone, led to significant increases in anastomotic bursting pressures, tensile strength, and tissue HP content, along with decreases in anastomotic MPO and NF-kappaB activity and later plasma levels of TNF-a and IL-6. The FG group also developed more marked neoangiogenesis and collagen deposition on histology analysis. However, FG and recombinant GH synergistically effected improved anastomotic healing, abolishing the infaust effects promoted by recombinant GH. Adhesion formation after intestinal anastomosis could not be lowered by FG alone or by the combination of FG and recombinant GH. Both FG alone and FG/GH, in contrast to GH alone and control treatment, significantly prolonged the survival time of experimental animals.

CONCLUSIONS

We found that FG, but not recombinant GH, could lower the risk of anastomotic leakage, improve intestinal anastomotic healing, and prolong survival in a pig model of traumatic shock associated with peritonitis. Both FG and recombinant GH synergistically effected improved intestinal anastomotic healing. It was suggested that GH could be used locally to promote intestinal anastomotic healing in intra-abdominal peritonitis.

Gene therapy targeting nuclear factor-kappaB: towards clinical application in inflammatory diseases and cancer

Nuclear factor (NF)-κB is regarded as one of the most important transcription factors and plays an essential role in the transcriptional activation of pro-inflammatory cytokines, cell proliferation and survival. NF-κB can be activated via two distinct NF-κB signal transduction pathways, the so-called canonical and non-canonical pathways, and has been demonstrated to play a key role in a wide range of inflammatory diseases and various types of cancer. Much effort has been put in strategies to inhibit NF-κB activation, for example by the development of pharmacological compounds that selectively inhibit NF-κB activity and therefore would be beneficial for immunotherapy of transplantation, autoimmune and allergic diseases, as well as an adjuvant approach in patients treated with chemotherapy for cancer. Gene therapy targeting NF-κB is a promising new strategy with the potential of long-term effects and has been explored in a wide variety of diseases, ranging from cancer to transplantation medicine and autoimmune diseases. In this review we discuss recent progress made in the development of NF-κB targeted gene therapy and the evolution towards clinical application.

Effects of Salvia miltiorrhizae on ICAM-1, TLR4, NF-kappaB and Bax proteins expression in multiple organs of rats with severe acute pancreatitis or obstructive jaundice

To observe the protective effects of Salvia miltiorrhizae injection on multiple organs of rats with SAP or OJ. Two hundred eighty-eight rats were used for SAP-associated experiments and OJ-associated experiments. The rats were randomly divided into sham-operated, model control and treated group. According to the different time points after operation, the SAP rats in each group were subdivided into 3, 6 and 12 h groups while the OJ rats were divided into 7, 14, 21 and 28 days groups. The mortality rates, pathological changes and ICAM-1 (only in lung), TLR4 (only in liver), Bax and NF-kappaB proteins expression in multiple organs (liver, kidney, lung, intestinal mucosa, spleen, thymus and lymph nodes) were observed, respectively. The mortality rates of treated groups decreased in both SAP and OJ experiments. Compared to model control group, the pathological changes can be seen in treated groups including; (1) the pathological changes of multiple organs in SAP and OJ experiments were improved, the pathological severity scores of kidney (at 6 h), intestinal mucosa (at 12 h), spleen (at 6 and 12 h), thymus (at 3 and 6 h) and lymph nodes (at 3 and 6 h) in SAP experiment and of liver (on 21 and 28 days), lung (21 days), intestinal mucosa (on 21 and 28 days) and spleen (on 21 and 28 days) in OJ experiment significantly declined (P < 0.05 or P < 0.01); (2) the positive rate of Bax protein in pancreas (at 3 h) and liver (on 6 and 12 h) in SAP experiment and in liver (on 28 days), kidney (on 21 days), and thymus (on 28 days) in OJ experiment were significantly lower (P < 0.05 or P < 0.01); (3) the positive rate of NF-kappaB in liver (at 12 h) and kidney (at 6 h) in SAP experiment and in liver (on 21 days), kidney (on 28 days), intestinal mucosa (on 28 days) and thymus (on 14 days) in OJ experiment significantly decreased (P < 0.05). (4) the positive rate of ICAM-1 in lungs (at 12 h) in SAP experiment was significantly less (P < 0.05). Salvia miltiorrhizae injection can protect multiple organs of SAP or OJ rats and inhibit the expression of ICAM-1, TLR4, NF-kappaB and regulate Bax proteins. Salvia miltiorrhizae may relieve the inflammation response and enhance the immunity function of SAP and OJ rats.

Ethyl pyruvate prevents intestinal inflammatory response and oxidative stress in a rat model of extrahepatic cholestasis

BACKGROUND

Ringer's ethyl pyruvate solution (REPS) has been shown to ameliorate liver injury in a murine model of extrahepatic cholestasis. The goal of the present investigation was to gain additional information about whether infusing REPS instead of Ringer's lactate solution (RLS) after inducing obstructive jaundice would be beneficial to intestinal barrier function, inflammatory response, and oxidative stress.

METHODS

Male Sprague Dawley rats were divided into three groups: Group Sham (n=6), sham-treated controls; Group RLS (n=9), common bile duct ligation (CBDL) plus RLS; and Group REPS (n=9), CBDL plus REPS. On 14 d after BDL, the rats were sacrificed and intestinal permeability was analyzed. Ileal IL-6 and TNF-alpha levels, malondialdehyde (MDA), glutathione (GSH), myeloperoxidase (MPO), and NF-kappaB activity were determined. Histologic examination and apoptosis of ileum were also examined.

RESULTS

Relative to sham-treated controls, CBDL in RLS-treated rats were associated with increased intestinal permeability to FITC-labeled dextran (4.51+/-0.85 versus 0.44+/-0.18, P<0.01), histopathologic damage and apoptosis (68.4+/-13.4 versus 6.7+/-1.9 pre-1000 villi cells, P<0.01). IL-6 and TNF-alpha level, MDA, MPO, and NF-kappaB activity in ileal tissues were also promoted, along with decreased GSH levels. Treatment with REPS significantly decreased intestinal permeability (3.37+/-0.71, P<0.01) and apoptosis (42.8+/-14.3 pre-1000 villi cells, P<0.01). Other changes were also significantly attenuated by treatment with REPS after CBDL.

CONCLUSIONS

The present study demonstrates that administration of REPS, but not RLS, maintains intestinal barrier function and reduces intestinal oxidative damage, inflammatory response, and apoptosis in cholestatic rats. This effect of ethyl pyruvate may be useful for preventing intestinal injury in patients with biliary obstruction.

Endogenous opioids modulate hepatocyte apoptosis in a rat model of chronic cholestasis: the role of oxidative stress

AIMS/BACKGROUND

There are increasing number of evidences indicating the contribution of endogenous opioids in the pathophysiology of cholestatic liver disease. The aim of the present study was to determine the role of the endogenous-opioid system in the modulation of hepatocytes apoptosis and liver oxidant/anti-oxidant balance during chronic cholestasis in rats.

METHODS

We induced cholestasis in rats by bile duct ligation (BDL). Naltrexone, an opioid antagonist, was administered at different doses (2.5, 5, 10, 20 and 40 mg/kg/day) to cholestatic animals for 5 weeks.

RESULTS

Naltrexone prevented the cholestasis-induced decrease of hepatic glutathione levels at higher doses (20 and 40 mg/kg/day). In the next phase of the study, we evaluated the effects of 20 mg/kg/day naltrexone treatment on hepatic damage indices and liver oxidant/anti-oxidant balance in 5-week BDL rats. There was a marked increase in the number of apoptotic hepatocytes as well as serum liver enzymes and hepatic lipid peroxidation levels in cholestatic rats compared with sham-operated animals 5 weeks after the operation. Liver anti-oxidant enzyme activities were significantly reduced in cholestatic rats compared with controls. Chronic treatment with naltrexone significantly improved all the aforementioned indices in comparison with saline-treated cholestatic rats.

CONCLUSION

Our findings demonstrate that the administration of opioid antagonist is protective against hepatic damage in a rat model of chronic cholestasis. We suggest that increased levels of endogenous opioids contribute to hepatocytes apoptosis in cholestasis, possibly through downregulation of liver anti-oxidant defense.

The NF-kappaB inhibitors attenuate hepatic injury in bile duct ligated rats

Cholestasis-induced liver injury during bile duct obstruction causes an inflammatory response and this inflammatory process may be an important source of tissue injury. We hypothesized that NF-kappaB inhibition would decrease liver injury in a rat model of extrahepatic biliary obstruction. A total of 40 female rats of Sprague-Dawley strain were allocated to four groups. First group was sham operated control. The second group underwent common bile duct ligation (BDL) and was monitored for 10 days. Third group of rats underwent BDL and received pyrrolidine dithiocarbomate (PDTC) at a dose of 100 mg/kg/day intraperitoneally. Fourth group underwent BDL and received sulfasalazine at a dose of 100 mg/kg b.w. Both inhibitors were administered once a day throughout last 7 days of the experimental period. Rats were terminated 10 days after sham operation or BDL. Aspartate aminotransferase, alanine aminotransferase, gamma-glutamil transpeptidase, and tumor necrosis factor-alpha levels were elevated in the BDL group as compared to the control group, while this increase was significantly decreased by treatment with PDTC and sulfasalazine (P < 0.05). Hepatic GSH, SOD and catalase levels were significantly depressed by BDL, but were elevated back to control levels in NF-kappaB inhibitor-treated BDL groups. Increases in tissue free radical and MDA levels and MPO activity due to BDL were reduced back to control levels by NF-kappaB inhibitor treatment (P < 0.05). Similarly histological damage in the BDL rats was reduced by treatments. These results indicate that inhibitors of NF-kappaB activity such as PDTB and sulfasalazine exert a therapeutic effect on cholestatic liver injury in rats with BDL through anti-inflammatory and antioxidant actions.

Chronic morphine treatment induces oxidant and apoptotic damage in the mice liver

Recently many researchers have proposed a protective role for morphine against tumor growth and metastasis, especially through induction of apoptosis in tumoral cells. These findings may lead to underestimation of cytotoxic effects of opioid drugs which are usually expected only at high doses. The present study was conducted to clarify whether repeated morphine administration, which is commonly used for relief from chronic pain, would interfere with liver antioxidant defence and hepatocytes vitality. Morphine was injected repeatedly at doses that have been reported to relieve cancer pain and reduce tumor spread in mice (5 and 10 mg/kg/day for nine consecutive days). The changes in hepatic glutathione concentration, its synthesis pathway and enzymatic antioxidant defense revealed the pro-oxidant effects of chronic morphine treatment on the liver. None of these changes were observed in those mice that were co-treated with naltrexone (opioid antagonist) and same doses of morphine. However induction of liver conjugating enzymes following morphine treatment was not receptor mediated. Moreover, chronic morphine treatment induced hepatocytes apoptosis. Interestingly, the apoptotic changes were antagonized by co-administration of either naltrexone or thiol antioxidant. In conclusion, although hepatotoxic effects of morphine at high doses have been reported previously, our findings propose that repeated morphine administration even at lower doses would induce oxidative stress in the liver, which may contribute to induction of apoptosis in hepatocytes. Since many of the observed adverse effects were mediated by opioid receptors, our results suggest that other opioid analgesics should also be used more cautiously.

Constitutive activation of NF-kappaB in human hepatocellular carcinoma: evidence of a cytoprotective role

Activation of nuclear factor-kappaB (NF-kappaB) can promote or inhibit apoptosis. Oxidative stress is an important mechanism by which certain anticancer drugs kill cancer cells, and is also one of the mechanisms that activate NF-kappaB. We therefore examined hepatic expression of the NF-kappaB monomer p65 in human hepatocellular carcinoma (HCC) tissue samples from eight patients and compared it with their respective samples of surrounding liver tissues. We also studied the effect of NF-kappaB inhibition in human HCC cells exposed to oxidative stress, by infecting HuH7 cells with a recombinant adenovirus carrying mutant IkappaBalpha (mIkappaBalpha). Cultured HuH7 cells were infected with mIkappaBalpha or beta-galactosidase (beta-Gal) for 24 hr followed by treatment with increasing concentrations of H2O2. Cytotoxicity, NF-kappaB translocation, NF-kappaB DNA binding, cell proliferation, and apoptosis were determined. The monomer p65 was overexpressed in six of eight human HCC tissues. In HuH7 cells, introduction of mIkappaBalpha potently inhibited the translocation, activation, and DNA binding of NF- kappaB. In control (beta-Gal-infected) HuH7 cells, exposure to H2O2 produced a dose-dependent increase in apoptosis, regardless of NF-kappaB status. mIkappaBalpha-mediated inhibition of NF-kappaB activation sensitized HuH7 cells to H2O2-induced inhibition of cell growth, and further promoted cell death. Addition of H2O2 (200-500 microM) to control or mIkappaBalpha-infected HuH7 cells enhanced caspase-3 activity and cleavage. Adenovirus-mediated transfer of mIkappaBalpha potently inhibits NF-kappaB activity in HuH7 cells, and this enhances oxidative stress-induced cell killing.

Sustained phosphorylation of Bid is a marker for resistance to Fas-induced apoptosis during chronic liver diseases

BACKGROUND & AIMS

Increased rates of apoptosis have been reported to play a role in the pathophysiology of many disorders, including liver diseases. Conversely, genetic mutations that result in impairment of programmed cell death have been associated with cancer development. However, apoptosis resistance can also be the result of nongenetic stress adaptation, as seen in the cancer-prone metabolic liver disease hereditary tyrosinemia. To clarify whether stress-induced apoptosis resistance is a general feature of chronic liver diseases, an animal model of chronic cholestasis was examined.

METHODS

Studies were performed with mice before and 2 weeks following bile duct ligation and with Fah-/- and Fah/p21-/- mice before and after NTBC withdrawal.

RESULTS

Here we show that bile duct ligation induced profound resistance against Fas monoclonal antibody-mediated hepatocyte death. The apoptosis signaling pathway was blocked downstream of caspase-8 activation and proximal to mitochondrial cytochrome c release. In controls, activation of the Fas receptor resulted in rapid dephosphorylation of Bid and its subsequent cleavage, whereas Bid remained phosphorylated and uncleaved in chronic cholestasis and other models of hepatic apoptosis resistance.

CONCLUSIONS

We propose a model in which the phosphorylation status of Bid determines the apoptotic threshold of hepatocytes in vivo. Furthermore, resistance to apoptosis in chronic cholestasis may contribute to the long-term risk of cancer in this setting.

ETHYL PYRUVATE REDUCES LIVER INJURY IN A MURINE MODEL OF EXTRAHEPATIC CHOLESTASIS

Ethyl pyruvate has been shown to ameliorate liver injury and decrease expression of several proinflammatory cytokines when used to treat mice with hemorrhagic shock or alcoholic hepatitis. Herein we sought to determine whether delayed treatment with ethyl pyruvate dissolved in a Ringer's-type balanced salt solution--Ringer's ethyl pyruvate solution (REPS)--would be beneficial in a murine model of common bile duct ligation (CBDL)-induced liver injury. Male C57BL/6 mice were subjected to a sham (n = 6) procedure or CBDL (n = 27). Twenty-four hours after operation, mice subjected to CBDL were randomized to receive treatment with either REPS (40 mg/kg of ethyl pyruvate per dose) or Ringer's lactate solution (RLS) every 8 h over a 72 h period. Compared with sham-treated controls, CBDL in RLS-treated mice was associated with histological evidence of hepatocellular necrosis as well as significant increases in the plasma concentrations of alanine aminotransferase and total bilirubin. Relative to sham-treated controls, CBDL in RLS-treated mice also was associated with increased hepatic lipid peroxidation and increased hepatic expression of transcripts for TNF, IL-6, and iNOS. All of these changes were significantly attenuated by delayed treatment with REPS after CBDL. In the RLS-treated group, CBDL was associated with increased NF-kappaB DNA binding in nuclear extracts prepared from liver tissue. Treatment with REPS increased NF-kappaB DNA binding still further. CBDL was associated with increased hepatocellular apoptosis in both the RLS- and REPS-treated groups. These data support the view that ethyl pyruvate ameliorates hepatic inflammation, lipid peroxidation, and necrosis in mice subjected to CBDL. Ethyl pyruvate warrants further evaluation as an adjunctive treatment to ameliorate liver injury from extrahepatic biliary obstruction.