Hemophilia and nonprogressing human immunodeficiency virus type 1 infection

Seven of 112 hemophiliacs infected with human immunodeficiency virus type-1 (HIV-1) before 1986 through contaminated plasma products are currently healthy, with CD4 T-cell counts above 500 cells/microL, and have never received antiretroviral therapy (long-term nonprogressors [LTNPs]). Seven age and sex-matched hemophiliacs infected in the same period but who have progressive HIV disease (progressors) and one additional slow-progressing individual were also studied. One hundred-fold, 20-fold, and 10-fold lower levels of full-length HIV RNA in plasma, peripheral blood mononuclear cells (PBMCs), and proviral DNA in PBMCs, respectively, were found in LTNPs compared with progressors. Plasma and cell-associated HIV RNA and proviral DNA were lower in LTNPs who tested negative for viral isolation from PBMCs or who were positive only after removal of CD8+ cells. No substantial differences were observed in the in vitro production of chemokines including RANTES, MIP-1 alpha, MIP-1 beta, MCP-1, and interleukin-8 (IL-8) in supernatants of activated PBMCs or CD8-depleted PBMCs of LTNPs, even when HIV isolation was simultaneously accomplished exclusively after removal of CD8+ cells. Low levels of HIV load and replication in peripheral blood are the strongest correlates of nonprogression in this small number of infected hemophiliacs.

Oxidative damage and fibrogenesis

Various chronic disease processes are characterized by progressive accumulation of connective tissue under-going fibrotic degeneration. Evidence of oxidative reactions is often associated with fibrogenesis occurring in liver, lung, arteries, and nervous system. Moreover, an increasing bulk of experimental and clinical data supports a contributory role of oxidative stress in the pathogenesis of this kind of disease. Indeed, many etiological agents of fibrogenesis stimulate free radical reactions either directly or through inflammatory stimuli. Free radicals, as well as products of their reaction with biomolecules, appear to modulate the activity of the two cellular types mainly involved in the process, namely phagocytes and extracellular matrix-producing cells. Lipid peroxidation and certain lipid peroxidation products induce genetic overexpression of fibrogenic cytokines, the key molecules in the pathomechanisms of fibrosis, as well as increased transcription and synthesis of collagen. Both these events can be downregulated, at least in experimental models, by the use of antioxidants. The effect of oxidative stress on cytokine gene expression appears to be an important mechanism by which it promotes connective tissue deposition.

Nuclear factor kB is activated by arachidonic acid but not by eicosapentaenoic acid

The omega-6 arachidonic acid supplementation of the human promonocytic cell line U937 strongly stimulates the nuclear translocation of the transcription factor NF-kB. Inhibitors of arachidonate oxidative metabolism prevent NF-kB activation, indirectly indicating a role for prostaglandin and leukotriene metabolites in the genesis of this phenomenon. Of note, omega-3 eicosapentaenoic acid does not exert any effect on NF-kB DNA binding. In subsequent experiments, prostaglandin E2 consistently showed the ability to activate NF-kB in U937 promonocytic cells, as well as in J774 macrophages. NF-kB activation by arachidonate, together with the lack of effect by eicosapentaenoic acid, suggests a way to modulate the expression of certain genes by means of a suitable dietary n-6/n-3 fatty acid ratio.

Selective elevation of monocyte chemotactic protein-1 in the cerebrospinal fluid of AIDS patients with cytomegalovirus encephalitis

The CC chemokine monocyte chemotactic protein-1 (MCP-1) was markedly elevated in the cerebrospinal fluid (CSF) of human immunodeficiency virus (HIV)-infected patients with cytomegalovirus (CMV) encephalitis. The MCP-1 CSF levels in CMV encephalitis were markedly higher than those in the CSF of HIV-infected patients with or without unrelated neurologic diseases, including progressive multifocal leukoencephalopathy, cryptococcal meningitis, toxoplasmic encephalitis, and primary lymphoma. Interleukin-8, RANTES, macrophage inflammatory protein (MIP)-1 alpha, and MIP-1 beta were not substantially increased in the CSF of CMV encephalitis patients. High levels of MCP-1 may underlie monocyte recruitment and tissue damage in CMV encephalitis and may represent a rapid and useful tool in the diagnostic armamentarium for neurologic disorders associated with HIV infection.

Reperfusion damage to the bile canaliculi in transplanted human liver

In 19 patients who have undergone orthotopic liver transplantation (OLT), the trend and degree of cholestasis was statistically monitored in terms of plasma levels of L-gamma-glutamyl transferase (GGT) and total bilirubin. In addition, the ultrastructure of the bile canaliculus was examined during the entire OLT procedure, i.e., during explantation, cold ischemia, and after 60 to 90 minutes of organ reperfusion. Cholestasis was evident from the second day after surgery, with a peak after approximately 10 to 16 days. Defined, small changes in the functional state of actin filaments were noted in the bile canalicular area after prolonged ischemia. But the morphological status of the bile canaliculi changed dramatically after reperfusion. In fact, the mean area and perimeter of the canaliculi had increased significantly, and there was a marked loss in the number of bile microvilli per unit of canalicular area. The bile canaliculus appears to be one of the liver structures most susceptible to ischemia-reperfusion damage. A series of biochemical changes occurring during ischemia and after reoxygenation of the transplanted liver, especially, would provide a reason for the observed early morphological damage of the bile canaliculus, which, in turn, would explain the cholestasis of these patients in the first posttransplantation period.

Association of BoLA class II haplotypes with subclinical progression of bovine leukaemia virus infection in Holstein-Friesian cattle

The influence of bovine lymphocyte antigen (BoLA) complex polymorphism on subclinical progression of bovine leukaemia virus (BLV) infection was investigated in 41 Holstein-Friesian cows from two herds in Italy. All cows were seropositive for BLV and 22 had persistent lymphocytosis (PL). BoLA-A specificities were defined by serology, and class II haplotypes were defined based on restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR)-RFLP analysis of DQ and DR genes. Chi-square analysis revealed a significant and absolute association of haplotype DQA*3A-DQB*3A-DRB2*2A-DRB3.2*11 with resistance to PL (P chi 2 = 0.028, relative risk (RR) = 0.061). Consistent with this observation, multiple regression analysis revealed that animals carrying this haplotype had lower lymphocyte counts (P = 0.0057). By contrast, haplotype DQA*12-DQB*12-DRB2*3A-DRB3.2*8 was associated with susceptibility to PL (P chi 2 = 0.043, RR = 9.625) and increased lymphocyte counts (P = 0.0537). These results confirm the association of haplotype DQA*3A-DQB*3A-DRB2*2A-DRB3.2*11 with resistance to PL, and substantiate earlier findings of haplotype DQA*12-DQB*12-DRB2*3A-DRB3.2*8 as a risk factor for subclinical progression to PL in BLV-infected Holstein-Friesian cattle.

Structure-activity relationships study of two series of leukotriene B4 antagonists: novel indolyl and naphthyl compounds substituted with a 2-[methyl(2-phenethyl)amino]-2-oxoethyl side chain

N-Methyl-N-phenethylphenylacetamide has been reported to be a key binding domain to LTB4 receptors. Here we describe the synthesis and structure-activity relationship (SAR) studies of two new series of LTB4 receptor antagonists in which the phenyl ring of this receptor binding domain is replaced with indole and naphthalene, respectively. Results of these studies indicate that, in addition to the 2-[methyl(2-phenethyl)amino]-2-oxoethyl moiety, the presence of an acid group and a lipophilic side chain, as well as the spatial relationship of these three functions, is crucial for high binding affinity with LTB4 receptors. Our SAR studies also reveal that an arenecarboxylic acid, or an enoic acid in which the carboxyl group is conjugated with the central ring, is the preferred polar group. The lipophilic side chain of the naphthyl series was found to tolerate minor variations, ranging from a phenylmethoxy group to phenyl and alkyloxy groups. The most active compounds are 2-ethyl-3-[1-[2-[methyl(2-phenethyl) amino]-2-oxoethyl]-5-(phenylmethoxy)indol-3-yl]propenoic+ ++ acid (4g) of the indolyl series and 4-[2-[methyl(2-phenethyl)amino]-2-oxoethyl]-8-(phenylmethoxy )-2-naphthalenecarboxylic acid (2a) or the naphthyl series, with IC50 of 8 and 4.7 nM respectively, in the receptor binding assay using intact human neutrophils.

A novel series of [2-[methyl(2-phenethyl)amino]-2-oxoethyl] benzene-containing leukotriene B4 antagonists: initial structure-activity relationships

This report describes the synthesis of a new class of LTB4 receptor antagonists containing [2-[methyl(2-phenethyl)amino]-2-oxoethyl]benzene as a key binding domain for interaction with high-affinity LTB4 receptors. In addition to this binding domain, two other structural features, an acid function and a lipophilic group, are also required by these compounds for high binding affinity. Our studies indicate that maximal binding affinity in this series is controlled by the spatial relationship of these groups relative to one another. The structure-activity relationships are discussed. The most potent compound in this chemical series, (E)-5-[2-[methyl(2-phenethyl)-amino]-2-oxoethyl]-2-(benzyloxy)cinn amic acid (32), has an IC50 of 2 nM in a guinea pig spleen cell membrane assay. In the whole-cell human neutrophils binding assay, (Z)-5-[2-[methyl-(2-phenethyl)amino]-2-oxoethyl]-2-(benzyloxy)cinn amic acid (30) was the most potent compound with an IC50 of 50 nM.

Reactivity of monoclonal antibodies of the B cell panel on PBM from BLV-infected and lymphocytotic cows

The monoclonal antibodies included in the B cell panel of the Third Workshop on Ruminant Leukocyte Antigens were tested by flow cytometry for their reactivity with peripheral blood mononuclear cells (PBM) from normal, BLV (bovine leukemia virus)-infected but non-lymphocytotic and lymphocytotic cows. Three MoAbs probably detected pan-B cell antigens. They detected an increase in the B/T cell ratio in peripheral blood from lymphocytotic cattle. However, no changes were observed in the surface phenotypes of B cells from infected animals with MoAbs of the workshop panel.

Simple and rapid procedure for the purification of lipoprotein(a)

Lipoprotein(a) [Lp(a)] is a low-density lipoprotein-like particle displaying strong athero-thrombotic properties. Highly purified Lp(a) is increasingly requested for standardization of Lp(a) measurements and for biological studies. Several procedures have been described for Lp(a) separation and purification but none of them appear completely suitable. We present here a procedure for Lp(a) purification based on sequential elutions after lysine-Sepharose affinity chromatography. We were able to identify four distinct subspecies of Lp(a) showing different affinity to epsilon-amino groups of lysine-Sepharose, simply by modifying molarity and pH of the eluents; the fraction obtained in highly purified state represented the major form and could be eluted with 0.5 M sodium phosphate buffer (pH 4.4). Advantages of this procedure are represented by simplicity, rapidity and final yield.

Interleukin-10-induced HIV-1 expression is mediated by induction of both membrane-bound tumour necrosis factor (TNF)-alpha and TNF receptor type 1 in a promonocytic cell line

OBJECTIVE

To investigate whether the upregulatory effect of interleukin (IL)-10 on HIV expression in a model of latent HIV infection is mediated by induction of endogenous tumour necrosis factor (TNF)-alpha and TNF receptors (TNFR).

DESIGN

The latently HIV-infected promonocytic cell line U1 was examined, because in this in vitro model IL-10 has been shown to synergize with multiple cytokines, including TNF-alpha, in enhancing HIV production.

METHODS

Membrane-bound TNF-alpha, TNFR-1 and TNFR-2 surface expression were determined by flow cytometry. TNF-alpha mRNA was estimated by competitive polymerase chain reaction (PCR), and TNF-alpha, soluble TNFR-1 and soluble TNFR-2 supernatant content by enzyme-linked immunosorbent assay. HIV-1 expression was quantitated by reverse transcriptase assay and p24 antigen release.

RESULTS

We demonstrated that IL-10 induces a time and cell-concentration dependent upregulation of HIV expression in U1 cells. This effect is mediated through the endogenous production of TNF-alpha as demonstrated by blocking experiments with anti-TNF-alpha antibodies and by detection of IL-10-induced increase of TNF-alpha mRNA by competitive PCR. More importantly, IL-10 is able to upregulate membrane-bound TNF-alpha and TNFR-1, along with a consistent increase in the shedding of soluble TNFR-1 without inducing detectable TNF-alpha secretion.

CONCLUSIONS

IL-10 activates HIV expression through the membrane-bound TNF-alpha/TNFR-1 pathway, suggesting an amplification mechanism of HIV expression that might occur during cell-to-cell interaction. This positive regulatory effect of IL-10 in an in vitro model of chronic HIV infection is consistent with the inexorable progression of disease seen in advanced patients when both IL-10 and TNF-alpha are elevated.

Molecular characterization of a variant of proviral bovine leukaemia virus (BLV)

Southern-blot hybridization and partial sequencing of the pol and env genes were used to characterize BLV-integrated provirus of seropositive cattle from two dairy herds in northern Italy. Comparison of the data obtained with those of previously characterized BLV strains from other geographic areas (Australia, Belgium, Japan and USA) revealed the presence of a viral variant (BLV-12), which showed both conserved and unique features. Regarding the gp51 envelope glycoprotein, the BLV-12 variant showed: 1. A high extent of conservation, which included potential glycosylation sites and cysteine residues; 2. Three unique amino acid residues not present in any of the other BLV strains analysed; and 3. Some variability at the level of one (G) of the three (F, G and H) conformational epitopes, which is probably important in the process of infection. These results agree with the suggestion that the sequence variability of the gp51 glycoprotein preferentially involves structures whose change is thought to underlie the phenomenon of escape from immune surveillance.

Induction of procollagen type I gene expression and synthesis in human hepatic stellate cells by 4-hydroxy-2,3-nonenal and other 4-hydroxy-2,3-alkenals is related to their molecular structure

4-Hydroxy-2,3-nonenal (HNE) has been shown to induce procollagen type I gene expression and synthesis in hepatic stellate cells (HSC), i.e. the cells responsible for deposition of collagen and other extracellular matrix proteins in fibrotic liver. Here we report that the stimulatory effect of HNE mostly depends on the contemporary presence of the hydroxyl group in position C4 and of the double bond between position C2 and C3 since equimolar concentrations of 2,3-nonenal as well as of nonenal did not procollagen type I synthesis either at mRNA or at protein levels. Accordingly to this concept, all the other 4-hydroxy-2,3-alkenals of different chain length tested on cultured human HSC (4-hydroxy-2,3-hexenal, 4-hydroxy-2,3-octenal and 4-hydroxy-2,3-undecenal) strongly induced procollagen type I gene expression and synthesis. The stimulatory effect of 4-hydroxy-2,3-alkenals may depend on the well known ability of these aldehydes to react with either SH-groups or NH2-groups of functional proteins.

Modulation of endogenous IL-1 beta and IL-1 receptor antagonist results in opposing effects on HIV expression in chronically infected monocytic cells

A proportion of HIV-infected individuals experience episodes of localized or systemic bacterial infections caused by Gram-negative bacteria. Many of the clinical side effects of these infections are associated with the production of proinflammatory cytokines, which are induced primarily by LPS, a constituent of the bacterial cell wall of Gram-negative bacteria. The present study examines the mechanisms involved in LPS-mediated induction of HIV expression in U1 cells, a promonocytic cell line chronically infected with HIV. Stimulation of U1 cells by LPS alone induced minimal levels of HIV expression, which was significantly enhanced by granulocyte-macrophage colony-stimulating factor (GM-CSF). Costimulation of U1 cells with LPS plus GM-CSF resulted in the accumulation of steady-state levels of HIV RNA; however, only a weak induction of HIV long terminal repeat-driven transcription, which was not associated with the activation of the cellular transcription factor nuclear factor-kappa B, was noted. Costimulation of cells with LPS plus GM-CSF induced the production of proinflammatory cytokines, IL-8, IL-1 beta and IL-6, but not TNF-alpha. IL-1 receptor antagonist (ra) inhibited LPS enhancement of HIV expression in GM-CSF-stimulated cells, suggesting that endogenous IL-1 was involved in LPS-mediated viral production. In this regard, anti-inflammatory cytokines inhibited LPS plus GM-CSF-stimulated HIV expression, and this effect closely correlated with inhibition of IL-1 beta release and, in particular, with up-regulation of endogenous IL-1ra production. Thus, the balance between an endogenously produced viral inducer (IL-1 beta ) and an inhibitor (IL-1ra) may represent an important pathway leading to modulation of HIV expression from monocytic cells.

Modulation of endogenous IL-1 beta and IL-1 receptor antagonist results in opposing effects on HIV expression in chronically infected monocytic cells

A proportion of HIV-infected individuals experience episodes of localized or systemic bacterial infections caused by Gram-negative bacteria. Many of the clinical side effects of these infections are associated with the production of proinflammatory cytokines, which are induced primarily by LPS, a constituent of the bacterial cell wall of Gram-negative bacteria. The present study examines the mechanisms involved in LPS-mediated induction of HIV expression in U1 cells, a promonocytic cell line chronically infected with HIV. Stimulation of U1 cells by LPS alone induced minimal levels of HIV expression, which was significantly enhanced by granulocyte-macrophage colony-stimulating factor (GM-CSF). Costimulation of U1 cells with LPS plus GM-CSF resulted in the accumulation of steady-state levels of HIV RNA; however, only a weak induction of HIV long terminal repeat-driven transcription, which was not associated with the activation of the cellular transcription factor nuclear factor-kappa B, was noted. Costimulation of cells with LPS plus GM-CSF induced the production of proinflammatory cytokines, IL-8, IL-1 beta and IL-6, but not TNF-alpha. IL-1 receptor antagonist (ra) inhibited LPS enhancement of HIV expression in GM-CSF-stimulated cells, suggesting that endogenous IL-1 was involved in LPS-mediated viral production. In this regard, anti-inflammatory cytokines inhibited LPS plus GM-CSF-stimulated HIV expression, and this effect closely correlated with inhibition of IL-1 beta release and, in particular, with up-regulation of endogenous IL-1ra production. Thus, the balance between an endogenously produced viral inducer (IL-1 beta ) and an inhibitor (IL-1ra) may represent an important pathway leading to modulation of HIV expression from monocytic cells.

Giant cell reparative granuloma: presentation of one case and review of the literature

The authors describe a case of giant cell reparative granuloma (GCRG) of the distal phalanx of the thumb. After differential diagnosis involving other lytic lesions of the phalanges was made, surgical treatment was planned. The authors emphasize the importance of suitable treatment of GCRG in order to avoid the danger of recurrence and the risk of loss of the phalanx.

Effects of ethanol metabolism on PKC activity in isolated rat hepatocytes

Isolated rat hepatocytes were exposed to increasing concentrations of ethanol. During exposure of cells to ethanol a moderate but significant modification in the level of hepatic PKC c-isoforms has been observed. The ethanol-induced effect on liver protein kinase C was reversed by 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, indicating that the conversion of ethanol to acetaldehyde may be involved in the enzyme inactivation. The involvement of the alcohol metabolite in PKC modifications was confirmed by the exposure of hepatocytes or partially purified liver enzyme to acetaldehyde concentrations of pathological interest.

Cytokines and soluble receptor changes in the transition from primary to early chronic HIV type 1 infection

We studied determinants of chronic inflammation and/or immune activation in plasma from patients in the transition from primary to early chronic HIV-1 infection. The following parameters were estimated in seven patients over time: plasma concentrations of soluble CD8 (sCD8), tumor necrosis factor alpha (TNF-alpha), soluble TNF receptor type II (sTNFRII), interleukin 6 (IL-6), soluble IL-6 receptor (sIL6R), IL-10, transforming growth factor beta1 (TGF-beta1), along with CD4- and CD8-positive T cell counts, p24 antigenemia, and clinical evaluation. Results showed that concentrations of sCD8, TNF-alpha, and sTNFRII, and peripheral CD8-positive lymphocyte counts, were significantly increased in patients, compared to HIV-negative controls, and showed a trend toward normal values over time. Levels of IL6, sIL6R, IL-10, and TGF-beta1 did not differ from those of controls and did not change over time. Heterogeneity was observed among the patients in terms of CD4-positive T cell depletion, levels of sCD8, concentrations of TNF-alpha/sTNFRII, and clinical outcome. These data indicate that in the transition phase from primary acute to chronic and asymptomatic infection the host immune activation in response to the virus is highly heterogeneous and that the sustained rise in TNF-alpha and its receptor may represent an important therapeutic target in early disease. The persistence of a state of chronic inflammation and/or immune activation could influence the progression of disease independently from CD4-positive T cell counts.

In vivo potentiation of 1,2-dibromoethane hepatotoxicity by ethanol through inactivation of glutathione-s-transferase

In the rat, a single ethanol (EtOH) pretreatment (2.5 g/kg b.w., per os) was able to strongly enhance the cytotoxicity of 1,2-dibromoethane (DBE)(87 mg/kg b.w., per os). The principal metabolic routes of DBE involve both oxidative and conjugative transformations. Microsomal cytochrome P450 content and dimethyl nitrosamine demethylase activity were not changed, while a significant loss of cytosolic total GSH-transferase was observed in rats killed 6 h after EtOH pretreatment. Pretreatment with methylpyrazole, an inhibitor of alcohol-dehydrogenase prevented the effects provoked by ethanol. The major EtOH metabolite, acetaldehyde. seemed thus to play a fundamental role in the mechanism responsible for the potentiation of DBE toxicity mediated by EtOH. To further support this hypothesis, disulfiram (75 mg/kg b.w.), an inhibitor of aldehyde dehydrogenase, was given i.p. to rats. When DBE was administered to disulfiram- and EtOH-pretreated rats, a marked increase of liver cytolysis was shown and cytosolic GSH-transferase activity was further inhibited if compared to that induced by EtOH treatment alone. The results are consistent with the hypothesis that EtOH given to rats increases DBE liver toxicity because its major metabolite, acetaldehyde, reduces the DBE conjugates to GSH transferase, with consequent shift of DBE metabolism to the oxidative route and accumulation of reactive oxidative intermediates no longer effectively conjugated with GSH.

On the role of lipid peroxidation in the pathogenesis of liver damage induced by long-standing cholestasis

Previous studies have suggested a possible involvement of free radical reactions in the pathogenesis of cholestatic liver injury as well as in the modulation of hepatic fibrogenesis. In this study we investigated whether lipid peroxidation is involved in the development of chronic liver damage induced by long-standing cholestasis. For this purpose we have used the rat model of bile duct ligation (BDL), which leads to liver fibrosis and cirrhosis. Using this model we observed that the development of chronic liver damage was associated with the onset of lipid peroxidation, as pointed out by detection of carbonyl compounds, 4-hydroxynonenal (HNE) and malondialdehyde (MDA), in BDL livers and of fluorescent adducts between MDA and serum proteins. Lipid peroxidation was a relatively late event (starting after 1-2 weeks of BDL) and was unrelated to the early development of liver necrosis and cholestasis (already evident after 72 h after BDL). A positive significant linear correlation between the kinetic of infiltration of neutrophils and of a monocyte/macrophage population in BDL livers and MDA and HNE generation in the same organs is presented, indicating a close link between lipid peroxidation and the activation of inflammatory cells. We also observed that a positive linear correlation exists between collagen deposition in these livers and hepatic production of MDA and HNE. This event, which is accompanied by an increase in the number of fat storing cells (FSC, the cells that produce collagen in fibrotic liver), suggests that lipid peroxidation in this model may contribute to stimulate collagen synthesis by proliferating FSC.

Acetaldehyde involvement in ethanol-induced potentiation of rat hepatocyte damage due to the carcinogen 1,2-dibromoethane

Previous experiments with hepatocytes isolated from ethanol-treated rats showed that alcohol potentiates the toxic action of 1,2-dibromoethane (DBE) by inhibiting its metabolism via glutathione-S-transferase. The aim of this study was to investigate whether acetaldehyde, the main product of ethanol metabolism, may be responsible for such inactivation. By pretreatment with 4-methylpyrazole, an inhibitor of acetaldehyde formation, the ethanol inactivation of glutathione transferase was actually prevented. As a consequence of this protective action, 4-methylpyrazole also prevented the high basal lipid peroxidation and the potentiated DBE toxicity observed in hepatocytes from ethanol-dosed animals. Finally, the inactivation of glutathione-S-transferase by concentrations of acetaldehyde likely to occur in the ethanol-intoxicated animal was confirmed in an in vitro model by direct aldehyde addition to hepatocyte suspensions.

Scavenging effect of silipide, a new silybin-phospholipid complex, on ethanol-derived free radicals

Ethanol metabolism by cytochrome P4502E1 (CYP2E1) produces free radical intermediates, identified as hydroxyethyl radicals. We have observed that in vitro addition or in vivo pretreatment of rats with Silipide, a new 1:1 complex of silybin with phosphatidyl-choline, is able to decrease the spin trapping of hydroxyethyl radicals in microsomes from chronic alcohol-fed rats. This effect is not due to an interference with the metabolism of ethanol by CYP2E1, but is rather related to the capacity of the silybin molecule to scavenge hydroxyethyl radicals. However, such an effect is lost when pure silybin in amounts comparable to those present in Silipide is administered instead, due to the low bioavailability of uncomplexed flavonoid. Further experiments in vivo have shown that Silipide administration also decreases hydroxyethyl radical signals detectable in the bile of rats acutely treated with ethanol. The ability of Silipide to scavenge ethanol-derived radicals along with its antioxidant activity suggests that this drug might be potentially useful in counteracting free radical-mediated injuries involved in the development of liver damage caused by alcohol abuse.

Hepatocellular metabolism of 4-hydroxy-2,3-nonenal is impaired in conditions of chronic cholestasis

4-Hydroxy-2,3-nonenal is a major aldehydic end-product of lipid peroxidation known to exert several biological and cytotoxic effects and to be produced during conditions of chronic cholestasis. Here we report that viable hepatocytes isolated from cholestatic livers of bile duct-ligated rats (BDL hepatocytes) show a significantly lower rate of HNE metabolism than control cells. This feature is likely to be the consequence of a significant inhibition in the activity of HNE-metabolizing cytosolic glutathione-S-transferase and alcohol dehydrogenase in BDL hepatocytes. Particulate NADP-dependent aldehyde dehydrogenase was also inhibited. No significant change was found for aldehyde reductase activity. A decreased hepatocellular metabolism of HNE can expose liver parenchymal and non-parenchymal cells to cytotoxic as well as pro-inflammatory and pro-fibrogenic effects of HNE, contributing to the development of chronic cholestatic liver damage.