Hepatic expression of tumour necrosis factor-alpha in chronic hepatitis B virus infection

Hepatitis mouse models: from acute-to-chronic autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease associated with interface hepatitis, raised plasma liver enzymes, the presence of autoantibodies and regulatory T-cell (Tregs) dysfunction. The clinical course is heterogeneous, manifested by a fulminant or indolent course. Although genetic predisposition is well accepted, the combination with currently undefined environmental factors is crucial for the development of the disease. Progress in the development of reliable animal models provides added understanding of the pathophysiology of AIH, and these will be very useful in evaluating potential therapeutics. It appears that artificially breaking tolerance in the liver is easy. However, maintaining this state of tolerance breakdown, to get chronic hepatitis, is difficult because liver immune homeostasis is strongly regulated by several immune response inhibitory mechanisms. For example, Tregs are crucial regulators in acute and chronic hepatitis, and C57BL/6 mice are most prone to experimental AIH. Immunization of C57BL/6 mice with liver (AIH) autoantigens (CYP2D6/FTCD or IL-4R) and the disturbance of liver regulatory mechanism(s), leading to experimental AIH, are likely to be most representative of human AIH pathology.

Tumor necrosis factor-alpha induced by hepatitis B virus core mediating the immune response for hepatitis B viral clearance in mice model

Persistent hepatitis B viral (HBV) infection results in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). An efficient control of virus infections requires the coordinated actions of both innate and adaptive immune responses. In order to define the role of innate immunity effectors against HBV, viral clearance was studied in a panel of immunodeficient mouse strains by the hydrodynamic injection approach. Our results demonstrate that HBV viral clearance is not changed in IFN-α/β receptor (IFNAR), RIG-I, MDA5, MYD88, NLRP3, ASC, and IL-1R knock-out mice, indicating that these innate immunity effectors are not required for HBV clearance. In contrast, HBV persists in the absence of tumor necrosis factor-alpha (TNF-α) or in mice treated with the soluble TNF receptor blocker, Etanercept. In these mice, there was an increase in PD-1-expressing CD8⁺ T-cells and an increase of serum HBV DNA, HBV core, and surface antigen expression as well as viral replication within the liver. Furthermore, the induction of TNF-α in clearing HBV is dependent on the HBV core, and TNF blockage eliminated HBV core-induced viral clearance effects. Finally, the intra-hepatic leukocytes (IHLs), but not the hepatocytes, are the cell source responsible for TNF-α production induced by HBcAg. These results provide evidences for TNF-α mediated innate immune mechanisms in HBV clearance and explain the mechanism of HBV reactivation during therapy with TNF blockage agents.

Psoriasis, hepatitis B, and the tumor necrosis factor-alpha inhibitory agents: a review and recommendations for management

BACKGROUND

Tumor necrosis factor inhibitory agents are currently considered to be contraindicated in psoriatic patients with hepatitis B.

OBJECTIVE

We aim to provide guidance to dermatologists on the use of tumor necrosis factor inhibitor therapy in these patients.

METHODS

The current literature was reviewed regarding the use of tumor necrosis factor-alpha inhibitory agents (etanercept, adalimumab, and infliximab) in psoriatic patients with particular reference to hepatitis B infection.

RESULTS

Tumor necrosis factor-alpha inhibitor therapy may result in reactivated hepatitis B in hepatitis B surface antigen-positive patients with psoriasis. This also occurs, although less frequently in patients with an isolated positive hepatitis B core antibody. Thus, all psoriasis patients should be screened for hepatitis B surface antigen plus hepatitis B core antibody prior to the initiation of tumor necrosis factor-alpha inhibitor therapy. Infliximab has been associated with more reactivation cases than the other 2 agents and fatalities have been reported with this agent. Evidence is presented that the risk of reactivation can be greatly minimized or eliminated by early or pre-emptive antiviral therapy.

LIMITATIONS

The data is largely based on small case series that are retrospective in nature.

CONCLUSIONS

Hepatitis B screening is essential prior to the initiation of tumor necrosis factor-alpha inhibitor therapy. Psoriatic patients found to be hepatitis B surface antigen or hepatitis B core antibody-positive should be referred to an appropriate specialist for evaluation and therapy. This would allow for the safe use of tumor necrosis factor-alpha inhibitors in psoriatic patients despite recently published guidelines to the contrary.

Use of tumor necrosis factor alpha inhibitors in hepatitis B surface antigen-positive patients: a literature review and potential mechanisms of action

As a class, tumor necrosis factor (TNF)-alpha inhibitors have provided clinicians significant control over chronic inflammatory diseases. With their widespread use has come the emergence of new side effects such as the reactivation of latent infections. One such infection that may reactivate is the hepatitis B virus (HBV). It is currently unknown if HBV reactivation is a class effect or attributable to a particular TNF-alpha inhibitor. To answer this question, a comprehensive literature review to identify trends in related cases was performed. A systemic literature review was performed using the PubMed and Medline databases (1996 to January 2010) searching for the index term "Hepatitis B" combined with the terms "tumor necrosis factor," "TNF-alpha inhibitors," "etanercept," "adalimumab," "certolizumab," and "golimumab." All relevant articles in English were reviewed, and secondary references of interest were also retrieved. Thirty-five cases with hepatitis B surface antigen (HBsAg) positivity known prior to initiation of TNF-alpha inhibitors were identified. Infliximab was used in 17 cases, etanercept in 12 cases, and adalimumab in 6 cases. All six cases of clinically symptomatic hepatitis were associated with infliximab therapy. Infliximab was associated with the most cases of greater than 2-fold increase in alanine aminotransferase (six of nine cases) and greater than 1,000-fold increase in HBV DNA load (three of four). The two deaths reported occurred with infliximab therapy. Potential mechanisms of action for the reported observations include differences in molecular design, route of administration, and potency in clearing TNF-alpha. In patients with a positive HBsAg prior to starting a TNF-alpha inhibitor, infliximab has the most reported cases associated with HBV reactivation. While such reactivation may be due to a variety of reasons, clinicians prescribing TNF-alpha inhibitors to HBsAg-positive patients should consider prophylactic antiviral therapy and close monitoring for any clinical or serological evidence of hepatitis.

Reactivation of hepatitis B viral infection in inactive HBsAg carriers following anti-tumor necrosis factor-alpha therapy

OBJECTIVE

To investigate whether anti-tumor necrosis factor-alpha (TNF-alpha) therapy can influence the reactivation of hepatitis B virus (HBV) infection in inactive HBsAg carriers.

METHODS

The medical records of 103 patients [59 with ankylosing spondylitis (AS), 41 with rheumatoid arthritis (RA), 2 with juvenile RA, and 1 with psoriatic arthritis] who had been treated with anti-TNF-alpha therapy were reviewed retrospectively. Data on seropositivity of HBV, HBV load, and serum aminotransferases prior to and after initiation of anti-TNF-alpha therapy were obtained.

RESULTS

Eight patients were inactive HBsAg carriers, and all of them had normal liver function and undetectable HBV load prior to anti-TNF-alpha therapy. Reactivation of hepatitis B occurred in 1 patient during the course of anti-TNF-alpha therapy. After the third infusion of infliximab 5 mg/kg at Week 6, a blood test showed that the patient had normal liver function. When the patient returned for the fourth infusion of infliximab at Week 14, a blood test showed markedly elevated aspartate aminotransferase (AST)/alanine aminotransferase (ALT) levels (457 and 1054 IU/l, respectively) and increased viral DNA by HBV polymerase chain reaction (PCR). The fourth infliximab infusion was canceled, and entecavir 0.5 mg/day was prescribed. Then AST/ALT levels began to decrease and returned to normal range after 3 months. Followup HBV PCR showed negative results.

CONCLUSION

We found 1 HBV reactivation case among 8 inactive HBsAg carriers following anti-TNF-alpha therapy. This finding supports the prophylactic use of antiviral agents in HBV carriers, even if they have normal liver function or an undetectable viral load.

Endocrine manifestations of hepatitis C virus infection

Chronic infection with hepatitis C virus (HCV) can result in both hepatic and extrahepatic disease and endocrine dysfunction represents an important class of HCV-related extrahepatic disease. The most frequently occurring--and clinically important--of these endocrine disorders are thyroid disease and type 2 diabetes mellitus. In this Review, we evaluate the evidence in support of a link between HCV infection and endocrine-system dysfunction, and discuss potential pathophysiological mechanisms. A meta-analysis of the literature has revealed significant associations between chronic HCV infection, thyroid autoimmunity and hypothyroidism. Furthermore, a high prevalence of thyroid cancer has been reported in HCV-positive patients. Several clinicoepidemiological studies have demonstrated that chronic HCV infection could lead to the development of type 2 diabetes mellitus, possibly as a result of HCV-induced metabolic disturbances. Some researchers have postulated that a type 1 T-helper -cell mediated immune response underpins the association of chronic HCV infection with endocrine disease. Indeed, the available data suggest that a common immunological, type 1 T-helper cell pattern of cytokine expression and activation (via interferon-gamma) could provide the pathophysiological basis for this association. Nonetheless, additional studies will be necessary to elucidate fully all the mechanisms involved in HCV-related endocrine dysfunction.

The hepatitis B x antigen effector, URG7, blocks tumour necrosis factor α-mediated apoptosis by activation of phosphoinositol 3-kinase and β-catenin

Hepatitis B x antigen (HBxAg) contributes significantly to the pathogenesis of chronic infection and development of hepatocellular carcinoma. To discern some of its operative pathways, HepG2 cells were stably transduced with HBx or the bacterial chloramphenicol acetyltransferase (CAT) gene. Differential gene expression has previously revealed an upregulated gene, clone 7 (URG7), that conferred resistance to anti-Fas killing on HepG2X cells. Given that tumour necrosis factor alpha (TNFα) is also an important mediator of chronic hepatitis, and partially shares signalling with Fas, experiments were designed to test whether URG7 blocks TNFα killing of HepG2X cells. HepG2X cells expressing URG7 and HepG2 cells overexpressing URG7 in the absence of HBxAg were resistant to TNFα killing compared with HepG2CAT cells. URG7 small interfering RNA restored the sensitivity of HepG2X cells to TNFα killing. Killing was associated with the activation of caspases 3 and 8, suggesting that URG7 blocked these caspases. This resistance was also associated with activation of phosphoinositol 3-kinase/Akt. Given that Akt and HBxAg also activate β-catenin, experiments were designed to determine whether URG7 blocked apoptosis via activation of β-catenin. Both HBxAg and URG7 activated fragments of the β-catenin promoter, and also promoted expression of β-catenin target genes. Hence, URG7 inhibits TNFα-mediated killing by blocking one or more caspases in the apoptotic pathway and by activating phosphoinositol 3-kinase and β-catenin, thereby overriding the apoptotic signalling of TNFα. This suggests that URG7 helps to protect virus-infected hepatocytes during chronic hepatitis B virus infection.

Hepatitis C infection and diabetes

Since the discovery of the hepatitis C virus (HCV) in 1989, attention has been paid to the association of chronic HCV infection and the development of diabetes. The risk factors for diabetes include older age, HCV genotype 3, severe liver fibrosis, family history of diabetes, and liver/kidney transplantation. Emerging evidence in animals and humans has shown that HCV infection induces hepatic steatosis and increases tumor necrosis factor-alpha level, both resulting in the development of insulin resistance and subsequent type 2 diabetes. It is suggested that the presence of diabetes and hepatic steatosis may enhance fibrosis progression, hepatocellular carcinoma, and atherosclerosis. Interferon is reportedly associated with improved glucose tolerance. However, interferon might enhance underlying autoimmunity against beta cells, leading to overt type 1 diabetes that is genetically predisposed or give rise to hyperglycemia, resulting in the development of type 2 diabetes. In light of the national epidemic of type 2 diabetes, the link between HCV and diabetes would be a major public health problem. Further clinical researches are awaited in order to effectively detect, prevent, and treat HCV-associated type 2 diabetes, which would also slow the progression of hepatitis C itself.

Safety of antitumour necrosis factor (anti-TNF) therapy in patients with chronic viral infections: hepatitis C, hepatitis B, and HIV infection

Tumour necrosis factor alpha (TNFalpha) is a pivotal cytokine in host defences with broad ranging effects on the innate and adaptive immune systems. Clinically, TNFalpha inhibitors have demonstrated remarkable efficacy in a wide range of autoimmune and inflammatory disorders but clearly at the cost of heightened susceptibility to a variety of infections in those treated with these agents. Most reports to date have described increased susceptibility to intracellular pathogens in patients with underlying chronic viral infections, but little in the way of adverse event reporting in these patients has occurred. While the reported experience to date is rather limited, TNFalpha inhibitors have displayed a reasonable safety profile in the setting of some chronic viral infections and in certain circumstances have demonstrated adjunctive activity in the treatment of these infections. Given the high prevalence of chronic viral infections in patients who are candidates for anti-TNF therapy and the potential for these agents in the treatment of chronic viral illness, additional studies are urgently needed to assess the risks and benefits of such therapy in these populations.

Involvement of the p38 mitogen-activated protein kinase cascade in hepatocellular carcinoma

BACKGROUND

The mitogen-activated protein kinase (MAPK) cascade is activated in response to various extracellular stimuli. The authors investigated the involvement of the p38 MAPK, a member of the MAPK superfamily, cascade in hepatoma cell lines and in human hepatocellular carcinoma (HCC) tissue specimens.

METHODS

Constitutively active mutant of MAPK kinase 6 (MKK6), which is upstream of p38 MAPK, was transfected into the HepG2 and HuH7 human hepatoma cell lines. The constitutive active mutant was constructed by replacing Ser-189 and Thr-193 with Glu. The growth and death of mutant MKK6-transfected hepatoma cells were analyzed by the WST-1 and sub-G1 assays. The surgically resected livers of 20 HCC patients were divided histologically into tumorous (T) and nontumorous (NT) lesions. p38 MAPK activity was analyzed using in vitro kinase assay and MKK6 activity was measured using Western blot analysis.

RESULTS

Mutant MKK6 transfection increased p38 MAPK activity, cytochrome c release from the mitochondria to the cytosol, and caspase-3 activity, accompanied by apoptosis. In contrast, SB203580, a p38 MAPK-specific inhibitor, prevented MKK6-induced apoptosis in hepatoma cell lines. In the T lesions of 20 HCC parients, p38 MAPK and MKK6 activities were significantly lower compared with NT lesions (P < 0.05). There was a significant positive correlation between p38 MAPK and MKK6 activity (r = 0.507, P < 0.05). Larger tumors (> 20 mm) exhibited lower levels of p38 MAPK and MKK6 activity than did smaller tumors (P < 0.05).

CONCLUSIONS

These findings suggested that reduction of the p38 MAPK cascade may account, in part, for the resistance to apoptosis, leading to the unrestricted cell growth of human HCC.

Phyllanthus amarus has anti-inflammatory potential by inhibition of iNOS, COX-2, and cytokines via the NF-kappaB pathway

BACKGROUND/AIMS

Phyllanthus amarus is a herbal medicine traditionally applied in the treatment of viral hepatitis. Aim of this study was to investigate potential anti-inflammatory properties of standardized P. amarus extracts concerning a potential influence of P. amarus on endotoxin-induced nitric oxide synthase (iNOS), cyclooxygenase (COX-2), and cytokine production in vivo and in vitro.

METHODS

Investigations were performed in rat Kupffer cells (KC), in RAW264.7 macrophages, in human whole blood, and in mice. Cells were stimulated with lipopolysaccharides (LPS) in the presence or absence of P. amarus extracts (hexane, EtOH/H(2)O), mice were treated with galactosamine/LPS as a model for acute toxic hepatitis. Nitrite was measured by Griess assay, prostaglandin E(2) (PGE(2)) by radioimmunoassay, and cytokines by enzyme-linked immunosorbent assay. iNOS and COX-2 were determined by Western blot, activation of NF-kappaB and AP-1 by EMSA.

RESULTS

P. amarus EtOH/H(2)O and hexane extracts showed an inhibition of LPS-induced production of NO and PGE(2) in KC and in RAW264.7. The extracts also attenuated the LPS-induced secretion of tumor necrosis factor (TNF-alpha) in RAW264.7 as well as in human whole blood. Both extracts reduced expression of iNOS and COX-2 and inhibited activation of NF-kappaB, but not of AP-1. P. amarus inhibited induction of interleukin (IL)-1beta, IL-10, and interferon-gamma in human whole blood and reduced TNF-alpha production in vivo.

CONCLUSIONS

This work shows that standardized extracts of P. amarus inhibit the induction of iNOS, COX-2, and TNF-alpha. Therefore, we report for the first time an anti-inflammatory potential of this traditionally employed herbal medicine both in vitro and in vivo.

Inhibition of LPS-induced nitric oxide and TNF-alpha production by alpha-lipoic acid in rat Kupffer cells and in RAW 264.7 murine macrophages

The activation of Kupffer cells represents a central mechanism of inflammatory liver injury involving the production of two important inflammatory mediators, nitric oxide and TNF-alpha. The aim of this study was to investigate the effect of the hepatoprotective compound alpha-lipoic acid (thioctic acid) on the production of nitric oxide and TNF-alpha in isolated rat Kupffer cells and RAW 264.7 macrophages. Isolated rat Kupffer cells or RAW 264.7 were either untreated, treated with alpha-lipoic acid (500 micro g/mL), or activated with 1 micro g/mL of lipopolysaccharide in the presence or absence of alpha-lipoic acid (0.2-500 micro g/mL). After 20 h the accumulation of nitrite was measured by the Griess assay. Tumour necrosis factor-alpha secretion was quantified after 4 h by L929 bioassay. Cell viability was determined by mitochondrial reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test, nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) DNA binding activity by gelshift assays. Treatment of Kupffer cells and RAW 264.7 with alpha-lipoic acid alone had no effect on basal nitric oxide production. However, alpha-lipoic acid significantly inhibited lipopolysaccharide-induced nitrite accumulation. alpha-Lipoic acid did not alter basal TNF-alpha secretion in Kupffer cells, whereas it significantly inhibited lipopolysaccharide-induced TNF-alpha production. alpha-Lipoic acid attenuated the activation of nuclear factor-kappaB and AP-1, two transcription factors pivotal in induction of inducible nitric oxide synthase and TNF-alpha. alpha-Lipoic acid significantly inhibits lipopolysaccharide-induced macrophage production of nitric oxide and TNF-alpha via an attenuated activation of NF-kappaB and activator protein-1. The reduced production of nitric oxide and TNF-alpha in Kupffer cells may be involved in the hepatoprotective action conveyed by alpha-lipoic acid.

Role of NF-kappaB and myc proteins in apoptosis induced by hepatitis B virus HBx protein

Chronic infection with hepatitis B virus (HBV) promotes a high level of liver disease and cancer in humans. The HBV HBx gene encodes a small regulatory protein that is essential for viral replication and is suspected to play a role in viral pathogenesis. HBx stimulates cytoplasmic signal transduction pathways, moderately stimulates a number of transcription factors, including several nuclear factors, and in certain settings sensitizes cells to apoptosis by proapoptotic stimuli, including tumor necrosis factor alpha (TNF-alpha) and etopocide. Paradoxically, HBx activates members of the NF-kappaB transcription factor family, some of which are antiapoptotic in function. HBx induces expression of Myc protein family members in certain settings, and Myc can sensitize cells to killing by TNF-alpha. We therefore examined the roles of NF-kappaB, c-Myc, and TNF-alpha in apoptotic killing of cells by HBx. RelA/NF-kappaB is shown to be induced by HBx and to suppress HBx-mediated apoptosis. HBx also induces c-Rel/NF-kappaB, which can promote apoptotic cell death in some contexts or block it in others. Induction of c-Rel by HBx was found to inhibit its ability to directly mediate apoptotic killing of cells. Thus, HBx induction of NF-kappaB family members masks its ability to directly mediate apoptosis, whereas ablation of NF-kappaB reveals it. Investigation of the role of Myc protein demonstrates that overexpression of Myc is essential for acute sensitization of cells to killing by HBx plus TNF-alpha. This study therefore defines a specific set of parameters which must be met for HBx to possibly contribute to HBV pathogenesis.

Concanavalin A hepatotoxicity in mice: tumor necrosis factor-mediated organ failure independent of caspase-3-like protease activation

Several models of tumor necrosis factor (TNF)/TNF-receptor 1 (TNF-R1)-dependent liver injury in mice were investigated with respect to caspase-3-like protease activation representing a pivotal mechanism of apoptotic cell death. Injection of TNF or T-cell-activating agents (i.e., agonistic anti-CD3 antibody or staphylococcal enterotoxin B [SEB]) into galactosamine (GalN)-sensitized mice caused TNF/TNF-R1-dependent liver injury. Intravenous concanavalin A (Con A) alone induced TNF-mediated hepatotoxicity dependent on both TNF-R1 and TNF-R2. Hepatic caspase-3-like proteases were activated in GalN/TNF, GalN/anti-CD3, or GalN/SEB-treated mice, but not in Con A-treated mice. Consistently, the broad-spectrum caspase inhibitor, benzoyloxycarbonyl-val-ala-asp-fluoromethylketone (zVADfmk), prevented TNF-mediated hepatotoxicity in all GalN-dependent models, but failed to protect against Con A. Under transcriptional arrest, however, Con A induced TNF-R1-dependent, but not TNF-R2-dependent, activation of caspase-3-like proteases, and zVADfmk prevented animals from Con A-mediated liver injury under this condition. Histological analysis revealed distinct differences between Con A- and GalN/Con A-induced liver injury regarding apoptotic morphology of hepatocytes. We conclude that impaired transcription induces a switch of Con A hepatotoxicity toward a caspase-3-like protease-dependent pathway. The observation that the functional state of the transcriptional machinery decides whether TNF-driven hepatocyte apoptosis involves activation of caspase-3-like proteases or alternative signaling pathways in vivo might be of relevance for the immunopathology of the liver.

Histopathology and pathobiology of hepatotropic virus-induced liver injury

The present report concerns current knowledge regarding immunopathogenesis that can be applied in the interpretation of histopathological changes in acute and chronic viral hepatitis. The histopathological features of viral hepatitis have not been changed and light microscopic examination remains essential for making a diagnosis and classification of chronic hepatitis and for the provision of objective parameters on grading and staging. However, new understanding and knowledge of viral pathogenesis, host immune responses, the biological behaviour of the causative viral agents and, in particular, viral interference in multiple hepatotropic viral infections must be taken into consideration in the interpretation of histopathological and immunopathological findings of liver tissues. This report also presents some histopathological analyses on multiple hepatotropic viral infections. It can be concluded that the diagnostic histological criteria for acute hepatitis remain applicable in such settings. However, the cause of acute flare up in chronic hepatitis could not be determined without clinical, virological and serological information. Routine histopathology cannot distinguish a new infection from an acute exacerbation due to a high level of viral replication or mutant virus. A repertoire of immunocytochemical stainings for viral antigens is helpful, but caution must be exercised in suggesting a specific viral aetiology due to the fact that suppression of pre-existing viral antigens can be pronounced when the new or concurrent infection is hepatitis C virus related.

Effect of hepatitis B virus on tumour necrosis factor (TNF alpha) gene expression in human THP-1 monocytic and Namalwa B-cell lines

In response to viruses, monocytes and B cells produce TNF alpha. Therefore, we investigated TNF alpha gene expression and protein secretion in a human monocytic cell line, THP-1, and a Burkitt's lymphoma B-cell line, Namalwa, in response to hepatitis B virus (HBV). Stimulation by phorbol myristate acetate (PMA) (100 ng/ml for 48 h) induced TNF alpha secretion in THP-1 and Namalwa cells (100 to 300 pg/ml). In THP cells, the optimum response (> 2000 pg/ml) was obtained in the presence of a second mitogenic signal such as lipopolysaccharide (LPS) (10 microg/ml for 24 h). In our activation conditions, Northern blot analysis revealed a marked accumulation of TNF alpha mRNA species at 1.7 kb in both cell lines. When PMA- or PMA+LPS-stimulated THP-1 cells were exposed to HBV, TNF alpha protein and mRNA significantly decreased (> 50%). In contrast, HBV exposure of PMA-activated Namalwa cells resulted in strongly increased TNF alpha protein secretion (1 ng/ml). In this case, HBV induced TNF alpha mRNA accumulation that consisted of two types: a regular 1.7 kb and two novel high molecular weight (HMW) species at 3.7 and 4.3 kb. Exposure of stimulated THP-1 and Namalwa cells to HBV resulted in HBs and pre-S1 antigen production in the supernatants. In addition, HMW HBV DNA forms were detected in both cell lines, but with distinct HindIII restriction patterns. These findings indicate that TNF alpha gene expression may be differently regulated by HBV in activated human macrophages and B cells, and thus TNF alpha may be involved in the pathogenesis of HBV.

Acute-phase gene expression correlates with intrahepatic tumor necrosis factor-alpha abundance but not with plasma tumor necrosis factor concentrations during sepsis/systemic inflammatory response syndrome in the rat

OBJECTIVES

To test the hypothesis that after cecal ligation and puncture in the rat, there is increased expression of the tumor necrosis factor (TNF)/interleukin-1-dependent, acute-phase reactant alpha 1-acid glycoprotein in the liver, and that this change correlates temporally with increased abundance of TNF-alpha in the hepatic parenchyma but not with circulating concentrations of TNF-alpha.

DESIGN

Prospective, randomized, controlled study.

SETTING

Research laboratory at the University of Pennsylvania School of Medicine.

SUBJECTS

Male, adolescent Sprague-Dawley rats, weighing 200 to 300 g.

INTERVENTIONS

The procedure of cecal ligation and single puncture with an 18-gauge needle was performed in one group of animals. Control animals underwent sham operation. At 0, 3, 6, 16, 24, 48, and 72 hrs after either procedure, blood was collected and the liver was isolated and perfusion-fixed with 2% paraformaldehyde. In a second group of animals, liver tissue was harvested for isolation of total hepatic RNA.

MEASUREMENTS AND MAIN RESULTS

Northern blot hybridization analysis demonstrated an increase in steady-state concentrations of alpha 1-acid glycoprotein messenger RNA that peaked at 16 hrs after cecal ligation and puncture. The alpha 1-acid glycoprotein messenger RNA was not detected in control animals. TNF-alpha concentrations in the plasma, as determined by enzyme-linked immunosorbent assay, were detected 3 and 6 hrs after cecal ligation and puncture. However, TNF-alpha concentrations were undetectable in the plasma at other time points after cecal ligation and puncture and at all time points in the sham-operated animals. Immunohistochemical staining of 7-micron hepatic sections demonstrated a progressive increase in TNF-alpha abundance, with a peak at 16 hrs. Alterations in alpha 1-acid glycoprotein gene expression correlated in time with intrahepatic TNF-alpha abundance, but not with plasma TNF-alpha concentrations.

CONCLUSIONS

The changes in TNF-alpha-dependent hepatic gene expression that accompany an animal model of the systemic inflammatory response syndrome correlate with intrahepatic, and not circulating, TNF-alpha concentrations and reflect paracrine, and not endocrine, activity. Therefore, plasma concentrations of TNF-alpha do not appropriately reflect hepatocellular responses during the systemic inflammatory response syndrome.