Repeated adenoviral administration into the biliary tract can induce repeated expression of the original gene construct in rat livers without immunosuppressive strategies

BACKGROUND

Systemic adenoviral readministration appears to be limited by immunogenicity.

AIMS

We examined the feasibility of repeated adenovirus mediated gene transfer into the liver via the biliary tract.

METHODS

Recombinant adenoviruses carrying a reporter lacZ gene were infused retrogradely into the common bile duct of rats. Transduction efficiency of the lacZ gene was estimated histochemically and quantitatively.

RESULTS

Retrograde administration of recombinant adenoviruses into the common bile duct of rats resulted in efficient transgene expression in the liver, specifically in hepatocytes, but not in biliary epithelia. Transduction efficiency induced by intrabiliary adenoviral administration was not substantially different from that induced by intraportal adenoviral infusion. Transgene expression in the liver was however transient, and development of neutralising antibodies against adenovirus was observed in serum but not in bile. When adenoviruses were readministered into the common bile duct, successful re-expression of the transgene in the liver was achieved despite the existence of neutralising antibodies in serum. Interestingly, although proliferation of adenovirus specific T cells in response to adenoviral readministration was suppressed significantly by immunosuppressive FK506 treatment, levels of transgene expression in the liver achieved by intrabiliary adenoviral readministration were not significantly different between animals treated with and without FK506. Furthermore, third adenoviral administration into the common bile duct also induced successful transgene expression in the liver.

CONCLUSIONS

These results suggest that adenovirus mediated gene transfer into the liver may be repeatable without immunosuppressive strategies in clinical settings by means of endoscopic retrograde cholangiography.

Hypoglycaemia in patients with liver diseases administered levothyroxine

OBJECTIVE

Experience of a few hypoglycaemic patients with liver disease and receiving levothyroxine suggested to us that the prevalence of hypoglycaemia might be higher in such patients. The purpose of this study was to ascertain whether the prevalence of hypoglycaemia this was actually the case.

METHODS

This study was a retrospective, cross-sectional analysis of a medical computerized database and/or written reports from our university hospital. Patients with primary liver disease who were admitted to our hospital between April 1998 and August 2000 were divided into two groups; the first group received levothyroxine and the second group did not. The patients in the second group were selected from three different time periods within the period shown. The prevalence of hypoglycaemia (blood glucose level <70 mg/dL) was compared between the two groups.

RESULTS

The prevalence of hypoglycaemia was significantly higher in the group receiving levothyroxine compared with the group not receiving levothyroxine (four of eight patients (50.0%) vs. three of 59 (5.1%), P = 0.003, Fisher's exact test).

CONCLUSIONS

The results suggest that levothyroxine may be a risk factor for hypoglycaemia in patients with liver disease. While a larger study, perhaps with an alternative study design is needed to confirm this, and to investigate possible mechanisms of effect, it would be prudent to monitor the blood glucose level of such patients closely.

pp60c-src activation in lung adenocarcinoma

Nine src family members are known including c-Src, c-Yes, c-Lck, c-Fyn, c-Hck, c-Lyn, c-Blk, c-Fgr and c-Yrk. They encode proteins with molecular weights of 55-62 kilodaltons (kDa), which are either cytoplasmic or membrane-associated protein tyrosine kinases. A close correlation exists between an elevated pp60c-src tyrosine kinase activity and cell transformation. However, the level of activation of pp60c-src in non-small cell lung cancers (NSCLC) remains obscure. The aim of this study was to examine the level of activity of pp60c-src in NSCLC. pp60c-src expression and in vitro protein tyrosine kinase activity in lung cancer tissue samples were measured by western blotting and in vitro kinase assays and compared with those in the surrounding non-tumour lung tissue from the same patient. pp60c-src phosphorylation was assessed by two-dimensional tryptic phosphopeptide mapping. The kinase activity of pp60c-src was significantly activated in NSCLC, especially in adenocarcinomas. In addition, the pp60c-src kinase activity increased with the size of the adenocarcinoma. Two-dimensional tryptic phosphopeptide mapping showed dephosphorylation of pp60c-src at Tyr 530 in adenocarcinomas. The proto-oncogene product, pp60c-src, was activated in NSCLC, especially in adenocarcinomas, in part through the dephosphorylation of Tyr 530. Our results suggest that activation of pp60c-src might play an important role in the progression of lung adenocarcinomas.

Expression of p33(ING1) in hepatocellular carcinoma: relationships to tumour differentiation and cyclin E kinase activity

BACKGROUND

Inhibitor of growth-1 (ING1) is a new candidate for the tumour suppressor gene that encodes a 33k Da protein (p33(ING1)). While reduction of p33(ING1) is an important event in some human cancers, the expression of p33(ING1) in human hepatocellular carcinoma (HCC) remains to be examined. We evaluated p33(ING1) expression in various liver diseases including HCC.

METHODS

Expression of p33(ING1) was evaluated immunohistochemically not only in the normal liver (n = 5), but also in specimens of chronic hepatitis (n = 39) and HCC (n = 86). We also analysed the relationship between p33(ING1) expression and cyclin E kinase activity detected by autoradiography in 29 HCCs.

RESULTS

Expression of p33(ING1) was reduced in HCC, especially in moderately and poorly differentiated HCCs, and those at advanced stages. Furthermore, expression of p33(ING1) correlated inversely with cyclin E kinase activity.

CONCLUSIONS

These data suggest that reduction of p33(ING1) may contribute to the process of malignant transformation, progression and dedifferentiation of HCC via an increase of cyclin E kinase activity.

Combined use of percutaneous ethanol injection and radiofrequency ablation for the effective treatment of hepatocelluar carcinoma

Radiofrequency ablation (RFA) and percutaneous ethanol injection (PEI) therapy are currently used for the treatment of hepatocellular carcinoma (HCC). The purpose of this study was to evaluate the usefulness of combination therapy of PEI and RFA (PEI-RFA). Seventy-three patients with biopsy-proven HCC and liver cirrhosis underwent RFA after a bolus injection of ethanol into HCC. The volume of coagulated necrosis in the liver caused by PEI-RFA was estimated and compared with that by RFA alone. Coagulated necrosis areas in the liver of patients treated with PEI-RFA were significantly larger than those of patients treated with RFA alone. In PEI-RFA group, the volume of coagulated necrosis was significantly correlated with the amounts of ethanol injected into HCC. No major complications were observed during and after the PEI-RFA treatment. These results indicate that PEI-RFA is more effective than RFA alone and can make dramatic improvement of therapeutic effects in RFA therapy for HCC with fewer sessions of treatments. Therefore, PEI-RFA is considered to be a practical and promising option and may open up new avenues for the treatment of HCC.

A novel cytotoxic T-cell epitope presented by HLA-A24 molecule in hepatitis C virus infection

BACKGROUND/AIMS

It has been suggested that cytotoxic T lymphocytes (CTL) have crucial roles for the hepatocellular damage in hepatitis C virus (HCV) infection. A series of CTL epitopes located in the HCV protein have been identified. However, no CTL epitopes restricted by HLA-A24, a common HLA allele in humans, has been identified.

METHODS

Peripheral blood and liver infiltrating mononuclear cells from the patients with hepatitis C virus infection and healthy controls were stimulated with a series of peptides containing HLA-A24 binding motifs located in HCV protein.

RESULTS

An immunodominant HLA-A24 restricted CTL epitope (A24-4; AYSQQTRGL, amino acids 1031-1039) presented by HLA-A24 molecule was identified using a series of synthetic peptides containing the HLA-A24 binding motifs. The CTL activity against this peptide was induced both in peripheral blood and liver infiltrating mononuclear cells from HLA-A24-positive chronic hepatitis C patients, not from HLA-A24-negative patients and HLA-A24-positive healthy controls. CTL activity was blocked by anti-HLA-A24 and anti-CD8 antibodies, not by anti-CD4 antibody. Furthermore, the A24-4-specific CTL recognized the HCV gene transfected target cells.

CONCLUSIONS

Because this peptide is presented by a common HLA class I molecule, it might be useful for protection against hepatocellular damage and vaccine development in large population of the HCV-infected patients.

Inhibitory effect of rifampicin on the depressive action of interleukin-1 on cytochrome P-450-linked monooxygenase system

It has been shown that interleukin 1 (IL-1) depresses cytochrome P-450-linked monooxygenases. In the present study, the effects of rifampicin on the depressive action of IL-1 on the activities and gene expression of xenobiotic metabolizing enzymes in liver microsomes were investigated in vivo using Wistar rats. Among the monooxygenases studied, we especially focused on the induction mechanism for CYP2D, known to be depressed by IL-1 and responsible for the oxidation of xenobiotics, debrisoquine, bufuralol, and sparteine. The CYP2D protein and its messenger RNA (mRNA) were quantitated by Western blot and slot blot hybridization analyses in the groups treated with and without rifampicin and IL-1. The results showed that the depressive action of IL-1 on CYP2D was offset by additional administration of rifampicin, and the P-450 (CYP2D-linked monooxygenase system is up-regulated at the mRNA level by rifampicin. These results show that rifampicin has a blocking effect on the depressive action of IL-1 on the CYP2D subfamily.

Assessment of the presence and severity of esophagogastric varices by splenic index in patients with liver cirrhosis

PURPOSE

To determine whether spleen size is related to the severity of esophageal varices or associated gastric varices and liver functions in patients with cirrhosis.

METHOD

The authors retrospectively studied spleen size on CT (splenic index [SI] = length x width x height of the spleen), liver functions, and the results of esophagogastric endoscopy in 110 patients with cirrhosis. They also analyzed SI in 112 controls.

RESULTS

In controls, body weight, height, and age affected the SI. The SI in patients with uncompensated cirrhosis was greater compared with the SI in those with well-compensated disease (p = 0.0363). The SI in patients with esophageal varices was greater than in patients without esophageal varices (p<0.0001), but patients with and without gastric varices had similar SI values. The SI in patients with the red color signs (red wale marking, cherry red spot, and hematocystic spot) on esophageal varices or with risky varices (enlarged tortuous varices with beady, nodular, or tumor shape associated with red color signs) was greater than in patients without these signs (p = 0.0029 and p = 0.0030, respectively).

CONCLUSION

The SI is a good indicator of the severity of esophageal varices and hepatic functional reserve in patients with cirrhosis.

Increased bcl-2 expression in lymphocytes and its association with hepatocellular damage in patients with autoimmune hepatitis

The proto-oncogene product bcl-2 is known to inhibit apoptotic cell death, and its dysregulation might play a critical role in the development of autoimmune disease. To elucidate the role of bcl-2 in autoimmune hepatitis (AIH), its expression in peripheral blood mononuclear cells (PBMC) and in liver-infiltrating lymphocytes (LIL) was investigated. Increased bcl-2 expression in PBMC was found in AIH patients compared with that in chronic hepatitis C (CHC) patients and in healthy controls. The level of bcl-2 expression significantly correlated with serum ALT level. Further analysis showed that CD4+ T cells are enriched in bcl-2-expressing PBMC. To characterize the Th1/Th2 profile of bcl-2-expressing CD4+ T cells, intracellular interferon-gamma (IFN-gamma) and IL-4 were analysed. The results revealed that most of the bcl-2-expressing cells were found to be IFN-gamma-secreting Th1 cells. In three patients for whom their clinical courses could be followed, bcl-2 expression was decreased after the initiation of immunosuppressive therapy with corticosteroids. However, the level of IFN-gamma + cells was not altered. Immunohistochemical analysis also showed that large amounts of bcl-2+ cells were observed in periportal area in the liver. In conclusion, bcl-2-expressing cells were shown to be increased in peripheral blood and liver in AIH and the bcl-2 product was expressed mainly in CD4+ Th1-type cells, suggesting that these cells might promote the cellular immune response and contribute to the development of hepatitis and hepatocellular damage in AIH.

Characterization of anti-histone antibodies in patients with type 1 autoimmune hepatitis

We have recently found that antibodies to total histones are common in a group of American patients with type 1 autoimmune hepatitis (AIH). In an attempt to determine the profile and clinical association of anti-histone antibody (AHA), 45 Japanese AIH patients were studied for serum isotypic reactivity with individual histones (H1, H2A, H2B, H3, H4) by enzyme-linked immunosorbent assay and western blotting. The results revealed that 40% of sera had reactivities with at least one of individual histones and that the antibodies were detected in all three classes of immunoglobulins (IgG, IgM, IgA). Immunoglobulin G type anti-H3 showed the dominant reactivity and it characterized 72% of sera with AHA. The titre of anti-H3 decreased significantly (P < 0.0075) after steroid therapy and the index of decrease for anti-H3 was correlated in individuals with that for serum aminotransferase. In general, patients with AHA showed higher serum level of alanine aminotransferase (P < 0.05), immunoglobulin G (P < 0.025), and higher frequency of A2-DR4 haplotype (53 vs 17%) than their seronegative counterparts. However, the titre of AHA was low in this disease condition and histone class-specific antibodies did not distinguish patients with distinctive clinical features, although patients with anti-H3 tended to be younger than those without AHA.

Endoscopic lithotomy of common bile duct stones with sublingual nitroglycerin and guidewire

OBJECTIVE

In 21 patients, our objective was the endoscopic removal of common bile duct stones by sphincter dilation with the application of sublingual nitroglycerin.

METHODS

Nitroglycerin 0.3-0.6 mg was needed for proper dilation of the orifice and for successful cannulation of the Dormia basket into the bile duct. Cannulation of the Dormia basket was simplified by placing the guidewire in the common bile duct beforehand. Because of possible stone impaction, a mechanical lithotriptor was applied smoothly in two patients.

RESULTS

Complete stone removal was successful in 18 of the 21 (86%) patients. One patient who developed a mild form of acute pancreatitis recovered in a few days by conservative management with drip infusion of protease inhibitor. Blood pressure dropped transiently in a patient receiving nitroglycerin, but the general condition of the patient was stable.

CONCLUSIONS

This procedure was found to be safe, easy, and effective in extracting common bile duct stones.

Plasmid DNA-based immunization for hepatitis C virus structural proteins: immune responses in mice

BACKGROUND & AIMS

Plasmid DNA-based immunization has been shown to be an effective means of vaccination in animal models. In this study, the immune responses to various hepatitis C virus structural protein antigens were evaluated using this technique.

METHODS

Six recombinant plasmids were constructed. These include, individually, the coding regions for the core protein (pC); E1 (pE1) and E2 (pE2); as well as core, E1, and E2 together (pCE1E2); E1 and E2 together (pE1E2); and finally an E2 construct from which the N-terminal hypervariable region had been deleted (pE2 deltaHVR). These plasmids were transfected into mammalian cells to test their protein expression and were injected into the quadriceps muscles of BALB/c mice to measure specific antibodies and cytotoxic T-lymphocyte responses.

RESULTS

All the recombinant plasmids were shown to express specific antigens transiently in cells and elicited specific antibody responses to core, E1, and E2 in mice. Specific cytotoxic T lymphocyte responses were detected only in mice injected with plasmid constructs encoding the core.

CONCLUSIONS

Genetic immunization can aid the development of hepatitis C virus vaccines by allowing for the rapid construction and evaluation of different expression plasmids as potential immunogens.

Reciprocal cytotoxic T lymphocyte cross-reactivity interactions between two major epitopes within HIV-1 gp160

We have observed and analyzed an unexpected cross-reactivity of CD8+ CTL between two nonhomologous peptides of the HIV-1 IIIB gp160 envelope protein, P18 (residues 315-329) and HP53 (834-848, also called TH4.1), in the context of four different class I MHC molecules, Dd, Dp, Dq (or Lq), and H-2u. In strains expressing Dd, the cross-reactivity between peptides was bidirectional, whereas in other strains (H-2u, H-2p, and H-2q), the cross-reactivity was unidirectional; that is, P18-specific CTLs showed no killing against targets pulsed with HP53, although HP53 stimulated CTL showed cross-reactive lysis against P18-pulsed target cells. Cross-reactivity was also shown in immunization in vivo and with target cells endogenously expressing viral protein in vitro using two different recombinant vaccinia viruses expressing only the N-terminal portion of gp160, containing P18 but not HP53. Peptide cross-contamination was excluded. Cold target inhibition and single cell cloning experiments indicated that the same CTL was responding to both peptides. Using substituted and truncated peptides, we explored amino acid residues critical for cross-reactive CTL recognition, identified fine specificity similarities among all cross-reactive CTL lines but not non-cross-reactive lines, and mapped cross-reactivity to a 10-residue core of P18 and to an eight-residue core of HP53. A comparison of these peptide sequences and recent data on residues of P18 interacting with H-2Dd provided us with clues to residues involved in the interaction of the CTL with the MHC-peptide complex.

Reciprocal cytotoxic T lymphocyte cross-reactivity interactions between two major epitopes within HIV-1 gp160

We have observed and analyzed an unexpected cross-reactivity of CD8+ CTL between two nonhomologous peptides of the HIV-1 IIIB gp160 envelope protein, P18 (residues 315-329) and HP53 (834-848, also called TH4.1), in the context of four different class I MHC molecules, Dd, Dp, Dq (or Lq), and H-2u. In strains expressing Dd, the cross-reactivity between peptides was bidirectional, whereas in other strains (H-2u, H-2p, and H-2q), the cross-reactivity was unidirectional; that is, P18-specific CTLs showed no killing against targets pulsed with HP53, although HP53 stimulated CTL showed cross-reactive lysis against P18-pulsed target cells. Cross-reactivity was also shown in immunization in vivo and with target cells endogenously expressing viral protein in vitro using two different recombinant vaccinia viruses expressing only the N-terminal portion of gp160, containing P18 but not HP53. Peptide cross-contamination was excluded. Cold target inhibition and single cell cloning experiments indicated that the same CTL was responding to both peptides. Using substituted and truncated peptides, we explored amino acid residues critical for cross-reactive CTL recognition, identified fine specificity similarities among all cross-reactive CTL lines but not non-cross-reactive lines, and mapped cross-reactivity to a 10-residue core of P18 and to an eight-residue core of HP53. A comparison of these peptide sequences and recent data on residues of P18 interacting with H-2Dd provided us with clues to residues involved in the interaction of the CTL with the MHC-peptide complex.

Expression of HLA class I molecules and the transporter associated with antigen processing in hepatocellular carcinoma

The expression of the HLA class I molecules on the cell surface was investigated in hepatocellular carcinoma (HCC) cell lines using complement-mediated cytotoxicity (CMC) and flow cytometric analysis. Although HLA-A antigens were detected by CMC in all cell lines tested, HLA-B and -C antigens were not detectable in six of seven HCC cell lines. These results were also confirmed by flow cytometric analysis focusing on HLA-Bw4 and Bw6 public antigens. Furthermore, complementary DNA (cDNA) from each cell line was tested for the expression of HLA-A, -B, -C and the transporter associated with antigen processing genes (TAP1 and TAP2). Two cell lines showed a reduced level of one or both of the TAP messenger RNAs (mRNAs), and one of these showed a reduction of HLA-B and -C gene expression as well, but the others had detectable mRNA levels. These results demonstrate that hepatocellular carcinoma cell lines tested in the current study lose or decrease the expression of HLA-B and -C alleles on the cell surface, even though mRNA encoding these alleles is present, suggesting that the loss of the HLA molecules might be caused by posttranscriptional events or failure to transport and load peptides necessary for HLA expression. The selective loss of HLA-B and -C, but not -A, molecules (which also excludes a beta 2-microglobulin defect) is intriguing, and may be attributable to the ability of some of the HLA-A molecules to load signal peptides not requiring TAP transport, or to natural selection of HLA-B or -C locus-specific immune surveillance.

Use of recombinant protein to identify a motif-negative human cytotoxic T-cell epitope presented by HLA-A2 in the hepatitis C virus NS3 region

To define cytotoxic T-cell (CTL) epitopes, the common approach involving the use of a series of overlapping synthetic peptides covering the whole protein sequence is impractical for large proteins. Motifs identify only a fraction of epitopes. To identify human CTL epitopes in the NS3 region of hepatitis C virus (HCV), we modified an approach using recombinant protein and the ability of short peptides to bind to class I major histocompatibility complex (MHC) molecules. Peripheral blood mononuclear cells from an HCV-infected patient were stimulated with a proteolytic digest of the recombinant NS3 protein to expand CTL to any active peptides in the digest. The digest was fractionated by reverse-phase high-performance liquid chromatography, and fractions were assessed for the ability to sensitize targets for lysis by CTL. The most active fraction was sequenced, identifying a 15-residue peptide (NS3-1J; TITTGAPVTYSTYGK). This sequence was confirmed to be the source of the activity by synthesis of the corresponding peptide. CTL lines specific for NS3-1J were established from two HCV-infected patients (both HLA-A2 and -B7 positive) by stimulation with the synthetic peptide in vitro. The CTL were HLA-A2 restricted, and the minimal epitope was mapped to a decapeptide NS3-1J (10.4). As this minimal epitope lacks the common HLA-A2-binding motif, this technique is useful for mapping CTL epitopes independent of known motifs and without the requirement for enormous numbers of overlapping peptides. Because this peptide is presented by the most common HLA class I molecule, present in almost half the population, it might be a useful component of a vaccine against HCV.

Patients with chronic hepatitis C have circulating cytotoxic T cells which recognize hepatitis C virus-encoded peptides binding to HLA-A2.1 molecules

Antiviral cytotoxic T lymphocytes (CTL) may play a role in clearance of hepatitis C virus (HCV)-infected cells and thereby cause hepatocellular injury during acute and chronic HCV infection. The aim of this study was to identify HLA-A2.1-restricted HCV T-cell epitopes and to evaluate whether anti-HCV-specific CTL are present during chronic hepatitis C. Peripheral blood mononuclear cells from four HLA-A2-positive patients with chronic hepatitis C and from two individuals after recovery from HCV infection were tested against a panel of HCV-encoded peptides derived from different regions of the genome, including some peptides containing HLA-A2.1 binding motifs. HLA-A2-negative patients with chronic hepatitis C as well as healthy HLA-A2-positive (anti-HCV-negative) donors served as controls. Peripheral blood mononuclear cells stimulated repeatedly with several HCV-encoded peptides (three in core, one in NS4B, and one in NS5B) yielded cytolytic responses. All four HLA-A2-positive patients with active infection had CTL specific for at least one of the identified epitopes, whereas two patients who had recovered from HCV infection had almost no CTL responses. Monoclonal antibody blocking experiments performed for two epitopes demonstrated a class I- and HLA-A2-restricted CTL response. CTL epitopes could partially be predicted by HLA-A2 binding motifs and more reliably by quantitative HLA-A2.1 molecule binding assays. Most of the identified epitopes could also be produced via the endogenous pathway. Specific CTL against multiple, mostly highly conserved epitopes of HCV were detected during chronic HCV infection. This finding may be important for further investigations of the immunopathogenesis of HCV, the development of potential therapies against HCV on the basis of induction or enhancement of cellular immunity, and the design of vaccines.

Effects of ionic strength and pH on the dissociation constant between NADPH-adrenoferredoxin reductase and adrenoferredoxin

The dissociation constant between NADPH-adrenoferredoxin reductase and adrenoferredoxin was measured at various ionic strengths (0.05-0.25) and pHs (6.6-8.2) by means of a kinetic method involving pyridoxal 5'-phosphate. For each ionic strength, the maximum dissociation constant was obtained at pH 7.4. It ranged from 8.34 (ionic strength = 0.05) to 169 nM (ionic strength = 0.25) at pH = 7.4. At each pH, the dissociation constant increased along with the increase in ionic strength.

Interleukin 2 induction of cytochrome P450-linked monooxygenase systems of rat liver microsomes

The effects of interleukin 2 (IL-2), a pivotal cytokine for generating an effective immune response, on rat liver microsomal cytochrome P450-linked monooxygenase systems were investigated by measuring the contents of cytochromes b5 and P450, and the activities of various xenobiotic-metabolizing enzymes [debrisoquine and bufuralol monooxygenases (CYP2D), 7-ethoxycoumarin O-deethylase, benzphetamine N-demethylase, aniline hydroxylase and p-nitroanisole N-demethylase]. The enzymatic activities except for p-nitroanisole N-demethylase and aniline hydroxylase were increased approximately to 1.3-fold of those of untreated liver microsomes following intraperitoneal injection of IL-2 (15 U/rat). However, the amount of immunoreactive b5 protein, and the activities of aniline hydroxylase and p-nitroanisole N-demethylase were not changed by injection of IL-2. To elucidate further the mechanism of the induction of CYP2D by IL-2, quantitative analyses of immunoreactive CYP2D protein and its mRNA were conducted by western blot and slot blot hybridization analyses. The results indicated that IL-2 induced an increase in the amounts of immunoreactive CYP2D protein and its mRNA. These enzymatic activities were thus up-regulated at the mRNA level.

Effects of interleukin 1 alpha on the activities and gene expressions of the cytochrome P450IID subfamily

The mechanism by which recombinant human interleukin 1 alpha (rhIL-1 alpha) inhibits the activities of drug-metabolizing enzymes of rat liver microsomes, especially debrisoquine monooxygenase and bufuralol monooxygenase (both cytochrome P450IID supported reactions), as well as other enzymes, was investigated by injecting IL-1 alpha into rats. rhIL-1 alpha suppressed the activities of various P450-linked monooxygenase systems such as aminopyrine N-demethylase, benzphetamine N-demethylase, and 7-ethoxycoumarin O-deethylase. It also suppressed the activities of debrisoquine monooxygenase and bufuralol monooxygenase. On the other hand, IL-1 alpha had little effect on the activity of p-nitroanisole N-demethylase. The suppression of debrisoquine monooxygenase and bufuralol monooxygenase activities was caused by a decrease in the amounts of immunoreactive P450IID protein and its mRNA. The reduction rates in the level of immunoreactive P450IID protein and its mRNA were comparable. These results suggest that at the mRNA level, the enzymatic activities of debrisoquine monooxygenase and bufuralol monooxygenase are down-regulated by IL-1 alpha.

Inhibition mechanism of reconstituted cytochrome P-450scc-linked monooxygenase system by antimycotic reagents and other inhibitors

The effects of various antimycotic reagents and some other reagents on a cytochrome P-450-linked monooxygenase system were investigated with respect to the activities of NADPH-ferricyanide reductase. NADPH-cytochrome c reductase of NADPH-adreno-ferredoxin reductase from NADPH to cytochrome c via adreno-ferredoxin, NADPH-cytochrome P-450-phenylisocyanide complex reductase, and the cholesterol side chain cleavage of the cytochrome P-450scc-linked monooxygenase system. No reagents inhibited the NADPH-ferricyanide reductase activity. Only cloconazole inhibited about 50% of NADPH-cytochrome c reductase activity. Cloconazole, econazole, clotrimazole, etomidate and ketoconazole inhibited both NADPH-cytochrome P-450-phenylisocyanide complex reductase and the side chain cleavage activity of cholesterol of the cytochrome P-450scc-linked monooxygenase system. Cloconazole, econazole, etomidate and ketoconazole behaved like non-competitive inhibitors for NADPH-cytochrome P-450-phenylisocyanide reductase activities and their Ki values were 10(-4)-10(-6) M. Cloconazole was a non-competitive inhibitor of NADPH-cytochrome c reductase and its Ki value was 8.3 x 10(-4) M. Cloconazole, clotrimazole, econazole, etomidate, ketoconazole and mitotane completely inhibited the side chain cleavage activity of cholesterol.

Adrenoferredoxin-binding peptide of NADPH-adrenoferredoxin reductase

The amino-acid sequence at the adrenoferredoxin-binding site of NADPH-adrenoferredoxin reductase ferredoxin:NADP+ oxidoreductase, EC 1.18.1.2) from bovine adrenocortical mitochondria was investigated chemically. NADPH-adrenoferredoxin reductase has an essential lysine residue at the adrenoferredoxin-binding site. A polypeptide at the adrenoferredoxin-binding site was isolated by high-pressure liquid chromatography from NADPH-adrenoferredoxin reductase modified with pyridoxal 5'-phosphate and cleaved with cyanogen bromide. The amino-acid sequence of the adrenoferredoxin-binding peptide was identified. The peptide accounted for 95% of the sugar content of the NADPH-adrenoferredoxin reductase.