Biomedical subjects

K O Lindros

Publications and source records attributed to K O Lindros.

At least 19 recordsLinked to original sources

PubMed2006

Chronic effects of celecoxib, a cyclooxygenase-2 inhibitor, cause enhanced alcohol-induced liver steatosis in rats.

BACKGROUND: The pathogenetic role of prostaglandins in steatosis, the first stage of alcoholic liver injury, is not well understood, especially that involving the inflammatory reactions controlled by prostaglandins and pro-inflammatory cytokines in the liver. We, therefore, studied the chronic effects of the COX-2 inhibitor, celecoxib, given to ethanol-treated rats. METHODS: Rats were fed ethanol and a low dose of celecoxib (approximately 20 mg/kg daily) in a high-fat/low-carbohydrate liquid diet for six weeks. RESULTS: Ethanol treatment caused liver steatosis, moderate cellular infiltration and enhanced levels of plasma alanine transaminase (ALT) and tumour necrosis factor-alpha (TNF-alpha). Co-administration of celecoxib further increased the steatosis, relative liver weights and increased plasma ALT and TNF-alpha levels above those in ethanol-treated rats. Also, celecoxib counteracted the ethanol-induced increase in hepatic prostaglandin E(2) receptor EP4 mRNA expression. In contrast, celecoxib alone increased plasma ALT and TNF-alpha levels. CONCLUSIONS: These results suggest that prolonged low-dose celecoxib treatment with ethanol enhances alcohol-induced steatosis and liver inflammatory reactions above that from ethanol or celecoxib alone. It is suggested that reduction in PGE(2) by treatment with celecoxib removes the endogenous protective effect of this prostaglandin.

Alanine Transaminase↗

PubMed2004

Oral chronic ethanol administration to rodents by agar gel diet.

BACKGROUND: Chronic ethanol administration to rodents requires specially designed equipment and is labor intensive. Here we report a new procedure. METHOD: A commercial liquid diet preparation was made into a gel by addition of 0.5% agar. The gel, containing 5.3% ethanol, was offered in Falcon tubes equipped with a feeding opening. RESULTS: The gel consumption by C57/Bl mice resulted in high blood ethanol levels (average 43 mM). After 6 weeks, marked liver steatosis and significantly increased serum alanine aminotransferase levels had developed. CONCLUSIONS: Administration of ethanol in a nutritionally adequate gel provides a simple method for studies on chronic ethanol effects in rodents.

Agar↗

PubMed2003

Phagocytosis and LPS-stimulated production of cytokines and prostaglandin E2 is different in Kupffer cells isolated from the periportal or perivenous liver region.

BACKGROUND: Kupffer cells can release pro-inflammatory mediators and contribute to damage, which often appears in a zonated fashion. METHODS: To assess position-associated functional differences, functions of intact Kupffer cells isolated from either the periportal or perivenous acinar region of rat liver were compared. RESULTS: Kupffer cells from the periportal region phagocytosed 2-3 times more FITC-labelled zymosan particles than corresponding perivenous cells, as determined by confocal microscopy and fluorescence assay. Periportal cells also produced more TNF-alpha and IL-1beta, but less NO and PGE2, compared to perivenous cells and the stimulation by addition of lipopolysaccharides (LPS) was moderate. In contrast, after overnight culture LPS dramatically increased TNF-alpha release and significantly more so in perivenous Kupffer cells (26-fold) than in periportal cells (11-fold). CONCLUSION: Our study suggests that periportal Kupffer cells are responsible for a major part of phagocytosis by the liver. The stronger LPS response of recovered perivenous Kupffer cells suggests a dominant role of these cells in pro-inflammatory events that ultimately may contribute to development of damage in this region.

Animals↗

PubMed2003

Alcohol affects the skeletal muscle proteins, titin and nebulin in male and female rats.

Alcoholic myopathy is characterized by decreased protein synthesis and contents resulting in atrophy of muscle fibers. We investigated the effect of alcohol on the cytoskeletal muscle proteins, nebulin and titin. Because women are more susceptible than men to the toxic effects of alcohol, male and female rats were included. Four groups were investigated: alcoholic males, pair-fed males, alcoholic females, pair-fed females. Alcohol consumption per unit body weight was 12.9 g/kg.d, with no difference between males and females. After 10 wk, male and female rats fed alcohol had lower gastrocnemius and plantaris protein and RNA contents (P < 0.001), with no effect on soleus, indicating myopathy of type II fibers. The gastrocnemius was fractionated to measure myofibrillary protein contents. Low percentage SDS-gel electrophoresis was performed to determine myosin heavy chain (MHC), nebulin and titin contents. Alcohol reduced gastrocnemius myofibrillary protein and MHC contents, and the plantaris RNA/protein ratio (P < 0.01). The titin/MHC and nebulin/MHC ratios were unaffected, suggesting a concomitant reduction in titin and nebulin. The decreases in titin and nebulin contents may affect muscle function. An interaction between gender and alcohol was noted for the plantaris RNA/protein ratio (P < 0.025), suggesting a reduced capacity for muscle protein synthesis in females.

Animals↗

PubMed2001

Triiodothyronine downregulates the periportal expression of alpha class glutathione S-transferase in rat liver.

Most drug-metabolizing phase I and phase II enzymes, including the glutathione S-transferases (GST), exhibit a zonated expression in the liver, with lower expression in the upstream, periportal region. To elucidate the involvement of pituitary-dependent hormones in this zonation, the effect of hypophysectomy and 3,3',5-triiodo-L-thyronine (T3) on the distribution of GST was studied in rats. Hypophysectomy increased total GST activity both in the periportal and perivenous liver region. Subsequent T3 treatment counteracted this effect in the perivenous zone. However, analysis for either mu class M1/M2-specific (1,2-dichloro-4-nitrobenzene) or alpha class A1/A2-specific (7-chloro-4-nitrobenzo-2-oxa-1,3-diazole) GST activity revealed that T3 treatment did not significantly affect the perivenous activity of these GST classes. In contrast, T3 was found to significantly counteract the increase of alpha class GST activity caused by hypophysectomy in the periportal zone. To establish whether this effect was T3-specific, hepatocytes were isolated from either the periportal and perivenous zone by digitonin/collagenase perfusion and cultured either as pyruvate-supplemented monolayer or as co-culture with rat liver epithelial cells. Only in the latter it was found that T3 suppressed the A1/A2-specific GST activity and alpha class proteins predominantly in periportal cells. The data demonstrate that T3 is an important factor responsible for the low expression of alpha GST in the periportal region. T3 may be involved in the periportal downregulation of other phase I and II enzymes as well.

Animals↗

PubMed2001

The antiestrogen toremifene protects against alcoholic liver injury in female rats.

BACKGROUND/AIMS: Females are generally considered to be more susceptible to alcohol-induced liver injury than males. To elucidate whether gonadal hormones are involved, female rats were chronically treated with ethanol and with an antiestrogen. METHODS: Ethanol was administered in a low-carbohydrate liquid diet. Estrogen action was blocked by daily intubation of toremifene, a non-hepatotoxic second generation estrogen receptor antagonist. RESULTS: The female rats consuming intoxicating amounts of ethanol diet for 6 weeks developed massive microvesicular/macrovesicular steatosis, frequent inflammatory foci and spotty necrosis. Serum alanine aminotransferase increased 7-fold. Toremifene treatment did not affect steatosis, but significantly reduced inflammation and necrosis. Ethanol increased the expression of CD14 and tumor necrosis factor- (TNF) alpha mRNA and also the production of TNF-alpha by isolated Kupffer cells, but toremifene had no significant counteracting effect. However, toremifene significantly alleviated both ethanol induction of the pro-oxidant enzyme CYP2E1 and ethanol reduction of the oxidant-protective enzyme Se-glutathione peroxidase. CONCLUSIONS: The partial protection by toremifene against ethanol-induced liver lesions suggests a pathogenic contribution of estrogens, possibly associated with an oxygen radical mediated mechanism.

Alcoholism↗

PubMed2001

Promoter polymorphism of the CD14 endotoxin receptor gene as a risk factor for alcoholic liver disease.

Twin concordance studies indicate that genetic factors influence the individual susceptibility for alcoholic liver disease (ALD). Both clinical and experimental data suggest that Kupffer cell activation by gut-derived endotoxins and other bacterial products is an important pathogenic factor. Activated Kupffer cells release proinflammatory cytokines, a process that is regulated by the CD14 endotoxin receptor (CD14). Recently, a C-->T (-159) polymorphism in the promoter region of the CD14 gene was detected and found to confer increased CD14 expression. In the present study, the association of CD14 promoter polymorphism with different forms of ALD was examined in 3 separate autopsy series. Among 442 men with valid alcohol-consumption data, 381 men had been moderate or heavy alcohol consumers. The allele frequency of the CD14 promoter genotype, determined by a modified cycle minisequencing technique, was 0.34 (CC), 0.51 (CT), and 0.16 (TT). The T allele was found to be associated with advanced ALD, i.e., with alcoholic hepatitis (odds ratio [OR]: 2.48; P = .018), and especially with cirrhosis (OR: 3.45; P = .004), but not with fatty liver, periportal fibrosis, or bridging fibrosis. The overall age-adjusted risk for cirrhosis was 3.08 (P = .01) for the carriers of the CT genotype, and 4.17 (P = .005) for the homozygous TT genotype. These results suggest that in the relatively isolated Finnish population, the T allele confers increased risk of alcoholic liver damage. In particular, TT homozygotes are at a high risk to develop cirrhosis.

Adult↗

PubMed2001

Sex difference in alcohol-related organ injury.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Nobuhiro Sato and Kai O. Lindros. The presentations were (1) Sex differences in ethanol pharmacokinetics, by E. Baraona; (2) Estrogen regulates the sensitivity to endotoxin in hepatic Kupffer cells, by K. Ikejima; (3) Sex difference in alcohol-related organ injury, by E. Mezey; (4) Aggravated ethanol-induced liver injury in female rats: Protection by the antiestrogen toremifene, by Harri A. Järveläinen; and (5) Alcohol metabolism in Asian subjects: Sex differences and flushing response, by V. A. Ramchandani.

Alcohol Dehydrogenase↗

PubMed2001

Models of alcoholic liver disease in rodents: a critical evaluation.

This article represents the proceedings of a workshop at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were J. Christian Bode and Hiroshi Fukui. The presentations were (1) Essentials and the course of the pathological spectrum of alcoholic liver disease in humans, by P. de la M. Hall; (2) Lieber-DeCarli liquid diet for alcohol-induced liver injury in rats, by C. S. Lieber and L. M. DeCarli; (3) Tsukamoto-French model of alcoholic liver injury, by S. W. French; (4) Animal models to study endotoxin-ethanol interactions, by K. O. Lindros and H. Järveläinen; and (5) Jejunoileal bypass operation in rats-A model for alcohol-induced liver injury? by Christiane Bode, Alexandr Parlesak, and J. Christian Bode.

Animals↗

PubMed2000

Effect of ethanol on the expression of hepatic glutathione S-transferase: an in vivo/in vitro study.

Ethanol, a human toxicant and a solvent in pharmacological research, is known to interfere with biotransformation of xenobiotics. We compared the in vivo and in vitro long-term effects of ethanol exposure on the expression of glutathione S-transferases (GST, EC 2. 5.1.18) in rat liver. Long-term in vivo ethanol treatment to achieve blood ethanol levels ranging between 10-50 mM was by liquid diet feeding. For in vitro experiments, rat hepatocytes co-cultured with rat liver epithelial cells were exposed to 17 and 68 mM ethanol for up to 10 days. Two weeks of liquid diet ethanol treatment increased total GST activity. Both Mu and Alpha classes and in particular the A1 and A2 subunits and the amount of their corresponding mRNAs were increased. Total GST activity was also increased in co-cultures after exposure to 68 mM ethanol for 10 days. However, the Mu class subunits M1 and M2 and the corresponding mRNAs were increased, rather than the Alpha class subunits. Thus, long-term exposure to ethanol induces hepatic GST both in vivo and in vitro, but different isoenzymes are affected. Consequently, extrapolation of in vitro data on GST expression and regulation to the in vivo situation must be judicious. During xenobiotic metabolism in cell culture, a shift in relative expression and induction of different GST forms may occur, resulting in either an under- or overestimation of effects.

Animals↗

PubMed2000

Growth hormone-regulated periportal expression of CYP2C7 in rat liver.

Most drug- and steroid-metabolizing cytochrome P450 (CYP) enzymes are expressed in the mammalian liver in a characteristic zonated pattern, with high expression in the downstream perivenous (centrilobular) region. Here, we report that CYP2C7, a member of the rat CYP2 family, is expressed preferentially in the opposite, periportal region. CYP2C7 mRNA, as detected by reverse transcription-polymerase chain reaction, was detected almost exclusively in cell lysates obtained from the periportal region, indicating a very steep acinar gradient. The amount of immunoreactive CYP2C7 protein in periportal cell lysates was also higher than in samples from the perivenous region. This gradient was reversed by hypophysectomy, which markedly and selectively reduced the periportal CYP2C7 protein content. Subsequent growth hormone infusion by osmotic minipumps restored the zonation by selectively increasing the amount of periportal CYP2C7 protein. Although hypophysectomy suppressed CYP2C7 mRNA and growth hormone counteracted it, regulation at this level did not appear to occur in a zone-specific fashion. This indicates that growth hormone-mediated zonal regulation of CYP2C7 protein has additional translational or posttranslational components. Ethanol treatment, which has been shown to affect growth hormone levels, significantly induced CYP2C7 mRNA, but not zone specifically. Our results demonstrate that growth hormone up-regulates the CYP2C7 gene by enhancing the expression of the protein specifically in the periportal liver region. Growth hormone may up-regulate other periportally expressed liver genes in a similar fashion.

Animals↗

PubMed2000

Kupffer cell inactivation alleviates ethanol-induced steatosis and CYP2E1 induction but not inflammatory responses in rat liver.

BACKGROUND/AIMS: Gadolinium chloride inactivates Kupffer cells and alleviates alcohol-induced liver lesions. We investigated the mechanism of gadolinium chloride protection after oral ethanol feeding. METHODS: Rats were maintained ethanol-intoxicated for 6 weeks by feeding ethanol in a low-carbohydrate/high-fat liquid diet. Macrophages were inactivated by intravenous administrations of gadolinium chloride. At termination, liver samples and cell lysates obtained from the periportal and perivenous region were analyzed for histopathology, mRNA expression of endotoxin-associated parameters and cytokines and for enzymes involved in oxidative stress. RESULTS: Ethanol treatment alone caused marked microvesicular/macrovacuolar steatosis and focal inflammation. Gadolinium significantly alleviated pathology, by reducing steatosis but not inflammation. Gadolinium treatment eliminated ED2 immunopositive Kupffer cells, which were larger and more frequent periportally. Ethanol significantly increased the mRNA expression of the endotoxin (LPS) receptor CD14 and the LPS binding protein LBP, but not that of the pro-inflammatory cytokines TNF-alpha and IL-1beta. The mRNA of CD14 was found to be expressed preferentially in the perivenous region, but gadolinium treatment had no significant effect on the expression or the distribution. However, gadolinium significantly moderated the ethanol induction of CYP2E1 and this effect correlated to the degree of steatosis. Ethanol increased glutathione transferase and reduced glutathione peroxidase activity, but these changes persisted after gadolinium treatment. CONCLUSIONS: Our results suggest that gadolinium chloride reduces symptoms of ALD mainly by counteracting steatosis, and that CD14-positive Kupffer cell populations are not involved in gadolinium protection. The strong correlation between pathology and CYP2E1 induction might suggest a steatopathogenic role for this enzyme.

Acute-Phase Proteins↗

PubMed2000

Effect of long-term ethanol exposure on the acinar distribution of hepatic glutathione S-transferase.

The ability of ethanol to affect the regional distribution of individual glutathione S-transferase (GST) isoenzymes in rat liver was investigated by analyzing the expression levels in cell lysates obtained from the periportal or perivenous liver region after in situ digitonin perfusion. In control rats, a significant perivenous dominance of GST proteins and activities measured by the substrates 1-chloro-2,4-dinitrobenzene (broad spectrum), 1, 2-dichloro-4-nitrobenzene (M1/M2-specific), and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (A1/A2-specific) was found. In pair-fed rats exposed to ethanol (36% of total calories) for 2 weeks, all GST activities measured were significantly increased in both acinar zones. However, the relative increase was greater in the perivenous region. The induction of the A1/A2-specific activity was the most pronounced. HPLC analysis revealed for both regions that this increase was largely confined to the A2 subunit, with only minor effects observed on the A1 subunit. At the mRNA level, the constitutive perivenous dominance of both GST A1 and GST A2 expression became more pronounced after ethanol administration. The results demonstrate that long-term ethanol exposure induces individual GST isoenzymes differently and might have a profound effect on xenobiotic-induced regional liver damage.

Animals↗

PubMed1999

Effect of chronic coadministration of endotoxin and ethanol on rat liver pathology and proinflammatory and anti-inflammatory cytokines.

To better understand how gut-derived endotoxins influence alcohol-induced liver injury and the expression of inflammatory cytokines a new animal model was developed. After 2 weeks on a modified ethanol-containing liquid diet, some rats also were infused with endotoxin via osmotic minipumps for 4 additional weeks. Ethanol diet alone increased plasma endotoxin threefold to 9.3 pg/mL. Endotoxin infusion increased the levels to 388 and 513 pg/mL in controls and ethanol-fed animals, respectively. Panlobular macrovesicular and microvesicular steatosis and inflammatory foci were observed in livers from both ethanol- and ethanol-endotoxin-treated animals, but there was no significant potentiation by endotoxin. Only minor changes, mainly polymorphonuclear infiltration, were seen in animals treated with endotoxin alone although the messenger RNA (mRNA) expression of both proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta) and anti-inflammatory cytokines IL-4 and IL-10 were markedly increased, as shown by competitive polymerase chain reaction (PCR) analysis using cyclophilin as standard. The effect of endotoxin infusion on cytokine mRNA expression in ethanol-fed animals was not significantly different. Expression of transforming growth factor beta1 (TGF-beta1) mRNA was increased twofold by ethanol, eightfold by endotoxin, but only threefold by ethanol-endotoxin treatment. The mRNA expression of lipopolysaccharide binding protein (LBP) and CD14 endotoxin receptor was not significantly increased by chronic endotoxin treatment, contrasting with the marked elevation observed after acute endotoxin challenge. These results suggest that the tolerance observed despite sustained hepatic expression of proinflammatory cytokines is counteracted by the anti-inflammatory cytokines and by down-regulation of CD14 and LBP. Furthermore, a similar adaptation may occur in alcoholics with continuous endotoxemia.

Acute-Phase Proteins↗

PubMed1999

Dose-dependent localization of TCDD in isolated centrilobular and periportal hepatocytes.

Dose-response relationships for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suggest a differential sensitivity of liver cell types to the induction of cytochrome P450 gene expression, and that the induction of hepatic protein CYP1A2 causes sequestration of TCDD. In addition, immunolocalization of hepatic CYP1A1/1B1/1A2 proteins is not uniform after exposure to TCDD. The mechanism for the regio-specific induction of hepatic P450s by TCDD is unknown, but may involve the differential distribution of participants in the AhR-mediated pathway and/or regional P450 isozymes, as well as, non-uniform distribution/sequestration of TCDD. Therefore, this study examined the effects of TCDD in unfractionated, centrilobular and periportal hepatocytes isolated from female Sprague-Dawley rats acutely exposed (3 days) to a single oral dose of 0.01-10.0 microg [3H]TCDD/kg. A dose-dependent increase in concentration of TCDD was accompanied by a dose-dependent increase in CYP1A1, CYP1A2, and CYP1B1 mRNA expression and associated enzymes in all liver-cell populations. Centrilobular hepatocytes showed a 2.7- to 4.5-fold higher concentration of TCDD as compared to the periportal hepatocytes at doses up to 0.3 microg TCDD/kg. Centrilobular hepatocytes also exhibited an elevated MROD activity as compared to the periportal hepatocytes at doses up to 0.3 microg TCDD/kg. Furthermore, centrilobular hepatocytes showed an elevated concentration of induced CYP1A2 and CYP1B1 mRNA as compared to periportal hepatocytes within the 0.01- and 0.3-microg TCDD/kg-treatment groups. This is the first study to demonstrate that a dose-dependent difference in distribution of TCDD exists between centrilobular and periportal cells that might be related to regional differences in P450 induction.

Administration, Oral↗

PubMed1999

Acetaldehyde prevents nuclear factor-kappa B activation and hepatic inflammation in ethanol-fed rats.

Acetaldehyde has been proposed as one of the mediators of liver injury in alcoholic liver disease. We investigated whether increased acetaldehyde levels affected the development of alcoholic liver injury. Male Wistar rats were fed a liquid diet containing fish oil and ethanol by intragastric infusion. Sustained elevations of acetaldehyde were achieved by daily treatment with two inhibitors of aldehyde dehydrogenase (ALDH): disulfiram and benzcoprine. Pathologic changes, plasma and liver acetaldehyde, nuclear factor-kappa B (NF-kappaB) and I kappa B alpha (I kappaB alpha) protein, tumor necrosis factor-alpha (TNF-alpha) and cyclooxygenase 2 (COX-2) mRNA were evaluated. Treatment with the ALDH inhibitors led to increased acetaldehyde in liver and plasma but prevented necrosis and inflammation. Steatosis was not affected. Both inhibitors decreased activation of NF-kappaB and down-regulated TNF-alpha and COX-2 expression. Decreased activation of NF-kappaB was accompanied by I kappaB alpha preservation. Acetaldehyde probably inhibits NF-kappaB activation through I kappaB alpha preservation. Down-regulation of TNF-alpha and COX-2 occur secondary to inhibition of NF-kappaB and account for the absence of necrosis and inflammation in the ALDH inhibitor-treated groups.

Acetaldehyde↗

PubMed1998

No significant expression of CYP2E1 in rat liver stellate cells.

The putative role of the ethanol-inducible cytochrome P450(CYP)2E1 in stimulating collagen synthesis by rat liver stellate cells was studied. Analysis of carefully isolated stellate cells revealed that their content of immunoreactive CYP2E1 protein and of CYP2E1 mRNA, as determined by reverse transcription, polymerase chain reaction (RT-PCR), was very low, i.e. only 0-4% of that in hepatocytes. We conclude that it is improbable that such low expression of CYP2E1 in stellate cells would have functional importance.

Animals↗

PubMed1998

Induction of UDP-glycosyltransferase family 1 genes in rat liver: different patterns of mRNA expression with two inducers, 3-methylcholanthrene and beta-naphthoflavone.

Uridine diphosphate (UDP)-glucuronosyltransferases (UGTs), presently called UDP-glycosyltransferases, catalyse the detoxification of many toxic and carcinogenic compounds. Glucuronidation is also a major metabolic pathway for numerous drugs. The UGT1A6 gene (formerly known as UGT1*06 and UGT1A1) has been suggested to belong to the aryl hydrocarbon (Ah) gene battery, which consists of several genes encoding for drug-metabolising enzymes regulated by dioxin and other ligands of the Ah receptor. In this study, we analysed the localisation of UGT1A6 expression in rat liver by in situ hybridisation to mRNA. Two different RNA probes were used, one which was specific to UGT1A6 and the other against the C terminal sequence shared by all UGT1 genes. In this study, no UGT1A6 mRNA was detected in the control animals. However, other gene(s) of the UGT1 family were expressed in the perivenous region surrounding the central veins as detected by hybridisation with the probe against the common region of the UGT1 genes. Treatment with the lower dose (5 mg/kg) of 3-methylcholanthrene (3MC) induced expression of UGT1A6 perivenously. Treatment with the higher dose (25 mg/kg) of 3-Methylcholanthrene resulted in a more panacinar expression pattern. In contrast to the perivenous induction observed with 3-methylcholanthrene, treatment with 15 mg/kg of beta-naphthoflavone (BNF) resulted in strong induction in the periportal region. The results reveal an inducer-specific pattern of UGT1A6 expression similar to that demonstrated earlier for other Ah battery genes, namely CYP1A1, CYP1A2, GSTYalpha and ALDH3. The finding further supports the notion that common factors regulate the regional hepatic expression of Ah battery genes.

Animals↗