Interleukin 10 promoter region polymorphisms and susceptibility to advanced alcoholic liver disease

Mechanisms of alcohol-induced hepatic fibrosis: a summary of the Ron Thurman Symposium

This report is a summary of Ron Thurman Symposium on the Mechanisms of Alcohol-Induced Hepatic Fibrosis which was organized by The National Institutes of Health in Santa Barbara, California, June 25, 2005. The Symposium and this report highlight the unique aspects by which drinking alcoholic beverages may result in hepatic fibrosis. Acetaldehyde, the first metabolite of ethanol, can upregulate transcription of collagen I directly as well as indirectly by upregulating the synthesis of transforming growth factor-beta 1 (TGF-beta1). Reactive oxygen species (ROS) generated in hepatocytes by alcohol metabolism can activate collagen production in hepatic stellate cells (HSCs) in a paracrine manner. Alcohol-induced hepatocyte apoptotic bodies can be phagocytosed by HSCs and Kupffer cells and result in increased expression of TGF-beta1 and subsequent HSC activation. Kupffer cells may contribute to the activation of HSCs by releasing ROS and TGF- beta1. Innate immunity may suppress hepatic fibrosis by killing activated HSCs and blocking TGF-beta1 signaling. In patients infected with hepatitis C virus (HCV), alcohol may promote hepatic fibrosis by suppressing innate immunity. HCV core and non-structural proteins contribute to HCV-induced hepatic fibrosis. Alcohol and HCV together may promote hepatic fibrosis through increased oxidative stress and upregulation of fibrogenic cytokines. The inactive aldehyde dehydrogenase (ALDH2) and the super-active alcohol dehydrogenase (ADH2) alleles may promote hepatic fibrosis through increased accumulation of acetaldehyde in the liver. Hepatic fibrosis can be reversed by inducing selective apoptosis or necrosis of activated HSCs, or by reverse trans-differentiation of activated HSCs into the quiescent phenotype.

Interleukin-10 and chronic liver disease

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Numerous investigations suggest that IL-10 plays a major role in chronic liver diseases. IL-10 gene polymorphisms are possibly associated with liver disease susceptibility or severity. Recombinant human IL-10 has been produced and is currently tested in clinical trials. These trials may give new insights into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

The role of genetic polymorphisms in alcoholic liver disease

Chronic alcohol consumption is a major cause of liver cirrhosis which, however, develops in only a minority of heavy drinkers. Evidence from twin studies indicates that genetic factors account for at least 50% of individual susceptibility. The contribution of genetic factors to the development of diseases may be investigated either by means of animal experiments, through linkage studies in families of affected patients, or population based case-control studies. With regard to the latter, single nucleotide polymorphisms of genes involved in the degradation of alcohol, antioxidant defense, necroinflammation, and formation and degradation of extracellular matrix are attractive candidates for studying genotype-phenotype associations. However, many associations in early studies were found to be spurious and could not be confirmed in stringently designed investigations. Therefore, future genotype-phenotype studies in alcoholic liver disease should meet certain requirements in order to avoid pure chance observations due to a lack of power, false functional interpretation, and insufficient statistical evaluation.

HFE genotypes in decompensated alcoholic liver disease: phenotypic expression and comparison with heavy drinking and with normal controls

OBJECTIVES

Predisposition to alcoholic liver disease (ALD) may be partly genetic. Heterozygosity for the HFE mutations C282Y and/or H63D has been associated with more severe disease in several liver conditions. Studies in ALD have not used controls matched for alcohol consumption and results have been conflicting.

METHODS

HFE genotyping was performed in two Caucasian heavy-drinking cohorts (>60 units/wk (M) or 40 units/wk (F) for >5 yr): (a) 254 patients with decompensated ALD (Child's grade B or C), (b) 130 controls with similar alcohol consumption but without liver disease. Results in males were also compared with those from another study of healthy male blood donors.

RESULTS

(1) Genotype distributions for the C282Y and H63D mutations were similar in ALD patients, heavy-drinking controls, and healthy blood donors. (2) ALD patients with and without HFE mutations had similar disease severity, age at presentation, and alcohol consumption. (3) Increased serum ferritin and % transferrin saturation were seen in 63% and 29% of ALD patients, regardless of HFE genotype; the increased % transferrin saturation was due to reduced unsaturated iron binding capacity, rather than increased serum iron. (4) Stainable liver iron was present in 52% of patients; grade was greater in patients with two HFE mutations than in those with one or with none. (5) Only the two C282Y homozygote patients had substantial iron overload.

CONCLUSIONS

Although serum iron abnormalities are common, C282Y and H63D mutation frequencies were not increased in heavy drinkers with decompensated liver disease. HFE mutations, although modestly influencing liver iron, do not predispose to clinically significant ALD.

The -159C/T polymorphism in the promoter region of the CD14 gene is associated with advanced liver disease and higher serum levels of acute-phase proteins in heavy drinkers

BACKGROUND

Innate inflammatory responses to endotoxin (lipopolysaccharide) contribute to the development of alcoholic liver disease (ALD). A single-nucleotide polymorphism (-159C/T) in the promoter region of the gene coding for CD14 (a lipopolysaccharide receptor) could be associated with the development of ALD. We sought too investigate the relationship between the CD14/-159C/T polymorphism and advanced ALD and acute-phase protein levels in heavy drinkers.

METHODS

A total of 138 heavy drinkers consecutively admitted to an Internal Medicine department were genotyped for the CD14/-159C/T polymorphism. Serum samples were analyzed for lipopolysaccharide-binding protein (LBP), soluble CD14 (sCD14), C-reactive protein (CRP), and immunoglobulin (Ig) A, IgG, and IgM. Patients with ascites or liver encephalopathy (n = 35) were classified as having advanced ALD.

RESULTS

After adjusting for potential confounding variables, the CD14/-159TT genotype was positively associated with advanced ALD (odds ratio, 2.99; 95% confidence interval, 1.09-8.24, p = 0.03) and serum LBP (p = 0.01) and sCD14 (p = 0.04) levels. The CD14/-159C/T polymorphism was not associated with serum levels of CRP, IgA, IgG, or IgM.

CONCLUSIONS

Our results support the notion that CD14/-159TT homozygous heavy drinkers have higher levels of the LPS-binding acute-phase proteins (LBP and sCD14) than do carriers of the CD14/-159C allele. Also, the CD14/-159TT genotype may be a risk factor for advanced ALD.

Tumor necrosis factor alpha, CYP 17, urokinase, and interleukin 10 gene polymorphisms in postmenopausal women: correlation to bone mineral density and susceptibility to osteoporosis

OBJECTIVE

Osteoporosis is a common disorder with a strong genetic component. We investigated the correlations between bone mineral density (BMD) and four gene polymorphisms (-308G>A tumor necrosis factor alpha (TNF-alpha), -34T>C CYP 17, *141T>C urokinase, and -627C>A interleukin 10 (IL-10) promoter), and their relationship to osteoporosis in postmenopausal women.

STUDY DESIGN

These polymorphisms were determined using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis. BMD of the lumbar spine and proximal femur were measured using dual-energy X-ray absorptiometry.

RESULTS

The prevalence of each genotype was as follows: (1) 79.3% A/A, 16.6% A/G, and 4.1% G/G in -308G>A TNF-alpha; (2) 18.9% T/T, 52.1% T/C, and 29% C/C in -34T>C CYP 17; (3) 86.4% C/C and 13.6% C/T in *141T>C urokinase; (4) 46.2% A/A, 45% A/C, and 8.8% C/C in -627C>A IL-10 promoter. Subjects with genotype C/C in -627C>A IL-10 promoter had lower BMD values and a significantly greater risk for osteoporosis (OR 8.1, 95% CI 1.5-42.8) at the lumbar spine compared with subjects with genotype A/C in -627C>A IL-10 promoter, after adjustment for potential confounders.

CONCLUSION

The RsaI IL-10 promoter gene polymorphism is associated with reduced BMD and predisposes women to osteoporosis at the lumbar spine.

Different effects of a CD14 gene polymorphism on disease outcome in patients with alcoholic liver disease and chronic hepatitis C infection

AIM: Clinical and experimental data suggest that gut-derived endotoxins are an important pathogenic factors for progression of chronic liver disease. Recently, a C-T (-159) polymorphism in the promoter region of the CD14 gene was detected and found to confer increased CD14 expression and to be associated with advanced alcoholic liver damage. Here, we investigated this polymorphism in patients with less advanced alcoholic liver disease (ALD) and chronic hepatitis C virus (HCV) infection.

METHODS: CD14 genotyping was performed by PCR-RFLP analysis in (a) 121 HCV patients, (b) 62 patients with alcohol-associated cirrhosis (Alc-Ci), (c) 118 individuals with heavy alcohol abuse without evidence of advanced liver damage (Alc-w/o Ci), and (d) 247 healthy controls. Furthermore, serum levels of soluble CD14 (sCD14) and transaminases were determined.

RESULTS: The TT genotype was significantly more frequent in Alc-Ci compared to Alc-w/o Ci or controls (40.3% vs 23.7% or 24.0%, respectively). In Alc-w/o Ci, serum levels of transaminases did not differ significantly between patients with different CD14 genotypes. In HCV patients, TT-homozygotes had significantly higher sCD14 levels and sCD14 serum levels were significantly higher in patients with advanced fibrosis or cirrhosis. However, no association was found between CD14 genotypes and histological staging or grading.

CONCLUSION: Considering serum transaminases as surrogate markers for alcoholic liver damage, the CD14 polymorphism seems to exhibit different effects during the course of ALD. Differences in genotype distribution between cirrhotic HCV patients and alcoholics and the known functional impact of this polymorphism on CD14 expression levels further indicate differences in the pathophysiological role of CD14 and CD14-mediated lipopolysaccharides signal transduction with regard to the stage as well as the type of the underlying liver disease.

Are genetic polymorphisms of tumour necrosis factor alpha, interleukin-10, CD14 endotoxin receptor or manganese superoxide dismutase associated with alcoholic liver disease?

BACKGROUND

Four polymorphisms have been described associated with either increased risk for alcoholic liver disease (ALD) or more serious histological lesions: tumour necrosis factor alpha (TNF-alpha) G(-238)A, interleukin-10 (IL-10) C(-627)A, promoter of CD14 endotoxin receptor gene C(-159)T and manganese superoxide dismutase (MnSOD) C(-1183)T/valine --> alanine.

METHODS

We sought confirmatory evidence, through individual and simultaneous analysis of the four aforementioned polymorphisms, in 176 heavy drinkers: ALD (n = 100) if histology-compatible or clinical evidence of hepatic decompensation; and no evidence of liver disease (NLD) (n = 76) if normal liver tests on two occasions or normal liver histology (steatosis alone).

RESULTS

Patients with ALD were older (53+/-10 vs. 48+/-10 years, P<0.05), with a similar sex distribution. TNF-alpha G(-238)A showed no difference in heterozygous GA-genotype prevalence (ALD, 9.0%/NLD, 7.9%). IL-10 C(-627)A showed no difference between groups, either homozygote AA (8.0% vs. 10.5%) or heterozygote CA (34.0% vs. 39.5%). CD14 promoter C(-159)T showed no difference between groups in T-allele frequency, either homozygote TT (27% vs. 21%) or heterozygote CT (49% vs. 50%). Alanine MnSOD allele carriers showed no difference between groups in either the heterozygote (55.0% vs. 49.3%) or homozygote (22% vs. 25%). No difference was observed in the probability of having simultaneously two, three or four of the implicated polymorphisms: respectively, 43%, 33% and 0% in ALD, and 43%, 24% and 5% in NLD (not significant).

CONCLUSIONS

No association was found between the previously implicated polymorphisms of TNF-alpha, IL-10, CD14 and MnSOD, either individually or simultaneously, and the presence of established ALD.

Liver cirrhosis induced by long-term administration of a daily low dose of amiodarone: A case report

The anti-arrhythmic agent amiodarone (AD) is associated with numerous adverse effects, but serious liver disease is rare. The improved safety of administration of daily low doses of AD has already been established and this regimen is used for long-term medication. Nevertheless, asymptomatic continuous liver injury by AD may increase the risk of step-wise progression of non-alcoholic fatty liver disease. We present an autopsy case of AD-induced liver cirrhosis in a patient who had been treated with a low dose of AD (200 mg/d) daily for 84 mo. The patient was a 85-year-old male with a history of ischemic heart disease. Seven years after initiation of treatment with AD, he was admitted with cardiac congestion. The total dose of AD was 528 g. Mild elevation of serum aminotransferase and hepatomegaly were present. Liver biopsy specimens revealed cirrhosis, and under electron microscopy numerous lysosomes with electron-dense, whorled, lamellar inclusions characteristic of a secondary phospholipidosis were observed. Initially, withdrawal of AD led to a slight improvement of serum aminotransferase levels, but unfortunately his general condition deteriorated and he died from complications of pneumonia and renal failure. Long-term administration of daily low doses of AD carries the risk of progression to irreversible liver injury. Therefore, periodic examination of liver function and/or liver biopsy is required for the management of patients receiving long-term treatment with AD.

Interleukin-10 haplotype associated with total serum IgE in atopic dermatitis patients

BACKGROUND

The genetic background of atopic dermatitis (AD) is not clearly understood. Interleukin (IL)-10 is a powerful Th-2 cell cytokine produced by lymphoid cells that exerts its function by inhibiting macrophage/monocyte and T-cell lymphocyte replication and secretion of inflammatory cytokines [IL-1, tumour necrosis factor-alpha (TNFA), IL-6, IL-8 and IL-12].

OBJECTIVE

In an effort to discover additional polymorphism(s) in genes whose variant(s) have been implicated in total immunoglobulin E (IgE) level in AD patients, we scrutinized the single nucleotide polymorphisms (SNPs) in the IL10 gene as a potent candidate for contributing to the level of IgE in serum.

METHODS

We recruited 334 AD patients and assayed their serum total IgE levels using the LIPA-200 system. Four SNPs in the IL10 gene were genotyped using the single-base extension (SBE) method. Logistic regression analyses were performed with single polymorphisms and haplotypes (ht) to determine their association with the level of serum total IgE.

RESULTS

Genetic association analysis of total serum IgE in AD patients revealed that one of the IL10 ht, IL10-ht2, was associated with decreased serum total IgE in gene dose-dependent manner (P = 0.02-0.001).

CONCLUSIONS

It was predicted that the inhibition of innate immunity by increased IL-10 production in IL10-ht2-bearing individuals might be associated with decreased total serum IgE levels among AD patients. The greater effects of IL10 ht on decreased total serum IgE levels suggest that the effect of IL-10 polymorphism might be the result of a combined genotype (ht) rather than single polymorphisms.

Association of interleukin 10 haplotype with low bone mineral density in Korean postmenopausal women

Osteoporosis is a disease characterized by exaggerated loss of bone mass, with as much as 50 to 85% of the variation in bone mineral density (BMD) commonly accepted as being genetically determined. Although intensive studies have attempted to elucidate the genetic effects of polymorphisms on BMD and/or osteoporosis in several genes, the genes involved are still largely unknown. The possible associations of genetic variants in five-candidate genes (IL10, CCR3, MCP1, MCP2 and GC) with spinal BMD were investigated in Korean postmenopausal women (n = 370). Fourteen SNPs in five candidate genes were genotyped, and the haplotypes of each gene constructed. The associations of adjusted spinal BMD by age, year since menopause (YSM) and body mass index (BMI), with genetic polymorphisms, were analyzed using multiple regression models. Genetic association analysis of Korean postmenopausal women revealed that IL10 -592A > C and/or IL10 ht2 were associated with decreased bone mass, whereas no significant associations were observed with all polymorphisms in other genes. The levels of spinal BMD in individuals bearing the IL10 -592CC genotype were lower (0.78 +/- 0.16) than those in others (0.85 +/- 0.17) (P = 0.02), and the BMD of IL10 ht2 bearing individuals were also lower (0.82 +/- 0.15) than those in others (0.85 +/- 0.17) (P = 0.04). Our results suggest that variants of IL10 might play a role in the decreased BMD, although additional study might need to be followed-up in a more powerful cohort.

Interleukin 4, interleukin 6 and interleukin 10 polymorphisms in children with acute and chronic immune thrombocytopenic purpura

Immune thrombocytopenic purpura (ITP) is an immune-mediated disorder. We investigated the polymorphisms of interleukin (IL)-4 intron 3, IL-6 (-572 G/C), and IL-10 (-627 C/A) in 50 children with acute ITP, 30 children with chronic TIP, and 100 healthy individuals. There were significant differences in the RP1/RP2 genotype proportion (P = 0.04) and the RP2 allelic frequency (P = 0.03) of IL-4 intron 3 and the A/C genotype proportion (P = 0.01) of IL-10 (-627) between children with chronic ITP and controls. This finding suggests that the IL-4 intron 3 and IL-10 (-627) polymorphisms contribute to the susceptibility of developing childhood chronic ITP.

Lack of Association of Genetic Polymorphisms in the Interleukin-1 .BETA., Interleukin-1 Receptor Antagonist, Interleukin-4, and Interleukin-10 Genes With Risk of Rheumatic Heart Disease in Taiwan Chinese

Inflammation and genetics may play a role in the pathogenesis of rheumatic heart disease (RHD). The aim of this study was to test whether interleukin (IL)-1beta, IL-1 receptor antagonist (IL-1Ra), IL-4, or IL-10 gene polymorphisms could be used as markers of susceptibility to or severity of RHD among the Chinese population in Taiwan. A group of 115 patients with RHD diagnosed by echocardiography, and 163 age- and sex-matched normal control subjects were studied. IL-1beta promoter, IL-1beta exon 5, IL-1Ra, IL-4 promoter, IL-4 intron 3, and IL-10 gene polymorphisms were identified by polymerase chain reaction-based restriction analysis. There was no significant difference in the distribution of genotypes and allelic frequencies between RHD cases and controls for IL-1beta promoter, IL-1beta exon 5, IL-1Ra, IL-4 promoter, IL-4 intron 3, and IL-10 gene polymorphisms. Further categorization of the RHD patients into mitral valve disease and combined valve disease subgroups also revealed no statistical difference in these gene polymorphisms when compared with controls. These findings suggest that the IL-1beta, IL-1Ra, IL-4, or IL-10 gene polymorphisms are not suitable genetic markers for RHD in Taiwan Chinese.

Approach to the pathogenesis and treatment of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) represents an advanced stage of fatty liver disease developed in the absence of alcohol abuse. Its increasing prevalence in western countries, the diagnostic difficulties by noninvasive tests, and the possibility of progression to advanced fibrosis and even cirrhosis make NASH a challenge for hepatologists. NASH is frequently associated with type 2 diabetes and the metabolic syndrome, and several genetic and acquired factors are involved in its pathogenesis. Insulin resistance plays a central role in the development of a steatotic liver, which becomes vulnerable to additional injuries. Several cyclic mechanisms leading to self-enhancement of insulin resistance and hepatic accumulation of fat have been recently identified. Excess intracellular fatty acids, oxidant stress, tumor necrosis factor-alpha, and mitochondrial dysfunction are causes of hepatocellular injury, thereby leading to disease progression and to the establishment of NASH. Intestinal bacterial overgrowth also plays a role, by increasing production of endogenous ethanol and proinflammatory cytokines. Therapeutic strategies aimed at modulating insulin resistance, normalizing lipoprotein metabolism, and downregulating inflammatory mediators with probiotics have promising potential.

The potential role of genes in nonalcoholic fatty liver disease

Although most people with obesity and type 2 diabetes will have steatosis, only a minority will ever develop nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Family studies suggest that genetic factors are important in disease progression, although dissecting genetic factors playing a role in NASH and fibrosis from those influencing the development established risk factors is difficult. Several approaches can be used to look for genetic factors playing a role in nonalcoholic fatty liver disease (NAFLD). In the future, genome-wide single nucleotide polymorphism (SNP) scanning of cases and controls may become feasible. To date, however,studies have relied on candidate gene, case control, allele association methodology. Recent, and as yet preliminary, studies have reported associations between steatosis severity, NASH, and fibrosis with genes whose products are involved in lipid metabolism,oxidative stress, and endotoxin-cytokine interactions. If confirmed,these associations will enhance understanding of disease pathogenesis,and accordingly, the ability to design effective therapies.

Alcohol and cirrhosis: dose--response or threshold effect?

BACKGROUND/AIMS

General population studies have shown a strong association between alcohol intake and death from alcoholic cirrhosis, but whether this is a dose-response or a threshold effect remains unknown, and the relation among alcohol misusers has not been studied.

METHODS

A cohort of 6152 alcohol misusing men and women aged 15-83 were interviewed about drinking pattern and social issues and followed for 84,257 person-years. Outcome was alcoholic cirrhosis mortality. Data was analyzed by means of Cox-regression models.

RESULTS

In this large prospective cohort study of alcohol misusers there was a 27 fold increased mortality from alcoholic cirrhosis in men and a 35 fold increased mortality from alcoholic cirrhosis in women compared to the Danish population. Number of drinks per day was not significantly associated with death from alcoholic cirrhosis, since there was no additional risk of death from alcoholic cirrhosis when exceeding an average daily number of five drinks (>60 g/alcohol) in neither men nor women.

CONCLUSIONS

The results indicate that alcohol has a threshold effect rather than a dose-response effect on mortality from alcoholic cirrhosis in alcohol misusers.

No relationship of -627 interleukin-10 promoter polymorphism in Chinese patients with rheumatoid arthritis

The aim of this study was to examine whether -627 interleukin-10 (IL-10) promoter polymorphism is a marker of susceptibility to or severity of rheumatoid arthritis (RA) in Chinese patients in Taiwan. The study included 198 Chinese patients with RA. One hundred unrelated healthy individuals living in central Taiwan served as the control subjects. The relationship between IL-10 gene polymorphism and clinical manifestations of RA was evaluated. For the genotype, allelic frequency, and carriage rate of IL-10 polymorphism, there were no statistically significant differences found between patients and controls. Furthermore, we did not detect any association of IL-10 genotype with rheumatoid factor (RF), extra-articular involvement, or bone erosion in the RA patients. The lack of association of -627 IL-10 gene polymorphism with RA and the clinical findings in our study implies that the IL-10 gene polymorphism cannot serve as a candidate gene marker for screening RA patients.

Comprehensive Analysis of Genetic Polymorphisms in the Interleukin-10 Promoter: Implications for Immune Regulation in Specific Ethnic Populations

The association of interleukin-10 (IL-10) promoter single-nucleotide polymorphisms (SNPs) as risk factors for certain inflammatory diseases, viral infections, cancers, and transplant rejection have been the subject of recent studies. The SNPs -1082 G --> A, -819 C --> T, and -592 C --> A, which have been associated with differential IL-10 production, are strongly linked with ethnicity. In this study, we determined the ethnic distribution of IL-10 promoter SNPs and their haplotype rates among Hispanics, African Americans, and Caucasians from Texas and Ashkenazi Jews from New York. Significant differences in prevalence rates of IL-10 SNPs (and their haplotype distribution) were found. African Americans and Hispanics have a lower rate of putative high-producer SNPs and a higher rate of low IL-10 producers when compared to Caucasians or Ashkenazi Jews. No statistically significant differences in allelic frequencies and haplotype rates were observed between Caucasians and Ashkenazi Jews. This study provides critical new information on the ethnic distribution of IL-10 promoter SNPs in a regional U. S. population and is the first to analyze the rate of SNPs in an unstudied ethnic population, Ashkenazi Jews. Knowledge of IL-10 promoter polymorphisms may prove useful in prediction of immunization responses, disease severity, and in the intelligent design of customized immunotherapy.

Hepatic adducts, circulating antibodies, and cytokine polymorphisms in patients with diclofenac hepatotoxicity

Diclofenac is a nonsteroidal anti-inflammatory drug that causes rare but serious hepatotoxicity, the mechanism of which is unclear. The purpose of the present study was to explore the potential role played by the immune processes. Antibodies to diclofenac metabolite-modified liver protein adducts were detected in the sera of seven out of seven patients with diclofenac-induced hepatotoxicity, 12 of 20 subjects on diclofenac without hepatotoxicity, and none of four healthy controls. The antibodies recognized adducts expressed in livers from rats treated with multiple doses of diclofenac, but not in those given single doses. In addition, several potential diclofenac adducts were identified in the liver of a patient with diclofenac-induced hepatic failure, but not from a normal human donor liver, by immunoblotting with an adduct-selective rabbit antiserum. To determine whether or not polymorphisms in genes encoding cytokine-related proteins influence susceptibility to hepatotoxicity, genotyping for the polymorphisms -627 in the interleukin (IL)-10 gene, -590 in the IL-4 gene, and codon 551 in the IL-4 receptor (IL-4R) were performed on DNA from 24 patients on diclofenac with hepatotoxicity, 48 subjects on diclofenac without hepatotoxicity, and healthy controls. The frequencies of the variant alleles for IL-10 and IL-4 were higher in patients (OR [odds ratio]: 2.8 for IL-10; 2.6 for IL-4; 5.3 for IL-10 + IL-4) compared with healthy controls and subjects on diclofenac without hepatotoxicity (OR: 2.8 for IL-10; 1.2 for IL-4; 5.0 for IL-10 + IL-4). In conclusion, the observed polymorphisms, resulting in low IL-10 and high IL-4 gene transcription, could favor a T helper (Th)-2 mediated antibody response to neoantigenic stimulation associated with disease susceptibility.

Chronic hepatitis in dogs: a review of current understanding of the aetiology, progression, and treatment

Chronic hepatitis is common in dogs in primary and referral practice but the cause is usually unknown. This paper reviews the literature on potential causes of chronic hepatitis in dogs (infectious, autoimmune, metabolic, toxic, and breed-associated) together with the literature on the progression of the disease and on treatments. This is compared with the current understanding of aetiology, progression, and treatment of chronic hepatitis in man. Unfortunately, little is known about the aetiology and progression of the canine disease and very few therapies have been subjected to critical trials. It is difficult therefore to draw conclusions about causes and effective treatment in dogs. Even the histological description for canine chronic hepatitis has yet to be standardised. Much research remains to be done and this review suggests some potential areas for future investigation.

Single nucleotide polymorphisms in the interferon-gamma and interleukin-10 genes do not influence chronic hepatitis C severity or T-cell reactivity to hepatitis C virus

BACKGROUND

The mechanisms by which interferon-gamma (IFN-gamma) contributes to inter-individual heterogeneity in the severity of chronic hepatitis C (CH-C) are unknown. In 116 consecutive patients with CH-C, we tested the hypothesis that host genetic factors regulating IFN-gamma production and activity influence the severity of liver damage and hepatitis C virus (HCV)-specific T-cell reactivity.

METHODS

We determined the genotypes of functionally significant polymorphisms in the IFN-gamma gene and in the promoter of interleukin-10 (IL-10), a cytokine that counteracts IFN-gamma. We also measured concanavalin A (Con A)-stimulated IL-10 and IFN-gamma production, and the frequency of virus-specific T-cells, producing IFN-gamma or IL-10.

RESULTS

The grade of inflammation and the stage of fibrosis of CH-C showed no associations with either the IFN-gamma or IL-10 promoter polymorphisms or with Con A-stimulated IL-10 or IFN-gamma production. Similarly, there were no associations between HCV-specific T-cell frequencies and these host genetic factors. On multivariate analysis, the grade of inflammation and the duration of HCV infection accounted for only 37% of the variance in the stage of CH-C (P<0.0001). This percentage did not increase by including any genetic variables in the analyses.

CONCLUSION

Future studies investigating the entire cytokine gene sequences will provide better information regarding genetic variations responsible for inter-individual differences in the severity of CH-C.

Genetics of liver disease: immunogenetics and disease pathogenesis

Understanding the genetic basis of "complex disease" has been heralded as one of the major challenges of the post genome era. However what are "complex diseases" and how will understanding the genetics of such diseases advance medical science? There has been a great deal of "hype" about the potential of the human genome mapping project. The three major claims are that this information will: (a) be used in diagnosis; (b) provide useful prognostic indices for disease management (including the development of individualised treatment regimens, based on the findings of both immunogenetic and pharmacogenetic studies); and (c) provide insight into the pathogenesis of these diseases. Of these three objectives the last has the greatest potential and is the least exaggerated claim. In this review I shall highlight major associations, discuss some of the practical issues that arise, and outline how current knowledge of the immunogenetic basis of chronic liver disease is beginning to inform the debate about disease pathogenesis.

Oxidative stress as a trigger for cellular immune responses in patients with alcoholic liver disease

Serum antibodies reactive with neo-antigens generated during ethanol metabolism have been identified in patients with alcoholic liver disease (ALD), although their role in the pathogenesis of disease remains unclear. In this study, we characterized peripheral blood mononuclear cell (PBMC) T-cell and antibody responses to human serum albumin (HAS) adducted with acetaldehyde under reducing conditions (AcA-HSA) or with malondialdehyde (MDA-HSA) in patients with advanced ALD (AALD, n = 28), heavy drinkers with no liver disease (NALD, n = 14), and mild/moderate drinking controls (n = 22). Peak proliferative responses of PBMC were assessed in vitro by tritiated thymidine incorporation after the addition of optimized concentrations of antigen or OKT3. Antibody titers were determined by enzyme-linked immunosorbent assay (ELISA). MDA-HSA induced PBMC T-cell proliferation was significantly higher in ALD than in NALD or control patients. Moreover, 10 of 28 (36%) of ALD patients had significant T-cell proliferative responses to MDA-HSA compared to 0 of 14 (0%, P =.02) of the NALD group and 2 of 22 (9%, P <.05) of controls. No significant difference in PBMC T-cell response to Aca-HSA was seen between subject groups. Patients with positive cellular responses to MDA had higher serum anti-MDA antibody titers than those not exhibiting a positive cellular response (P <.005). In conclusion, the pattern of cellular and humoral responses to MDA adducts suggests that the development of these responses may be a susceptibility factor for the development of advanced alcoholic liver disease. The apparent importance of T-cell responses to MDA adducts suggests that oxidative stress may represent an important stimulus for the development of cellular immune responses associated with advanced ALD.

Chronic Ethanol Consumption Enhances Interleukin-1-Mediated Signal Transduction in Rat Liver and in Cultured Hepatocytes

BACKGROUND

Interleukin-1 (IL-1) is a central mediator of the inflammatory process. Increased serum levels of IL-1 have been reported in alcoholics with liver damage, but it remains unknown whether chronic ethanol intake, in the presence or absence of lipopolysaccharide (LPS), activates IL-1 release and signaling in the hepatocyte.

METHODS

IL-1beta and IL-10 release, expression of their receptors (IL-1RI and IL-10R), and the IL-1RI signal transduction response were evaluated in livers and cultured hepatocytes from ethanol-fed or pair-fed rats exposed in vivo or in vitro to LPS, ethanol, or both.

RESULTS

Chronic ethanol intake increased both the serum levels of IL-1beta and IL-10 and the expression of IL-1RI, but not of IL-10R, in the liver microsomal fraction. In vivo LPS administration potentiated the ethanol-induced release of plasma cytokines. It is interesting to note that ethanol, either given in a single dose or chronically fed, stimulated IL-1beta and IL-10 release from cultured hepatocytes. Stimulation of hepatocytes with IL-1beta caused a higher activation of IL-1-associated kinase, extracellular receptor-activated kinases 1 and 2, and nuclear factor-kappaB (NF-kappaB) in hepatocytes from alcohol-fed animals than from controls. Furthermore, in the absence of any stimulation, hepatocytes from alcohol-fed animals showed an activation of both kinases, as well as an increase in NF-kappaB binding. Our results suggest the participation of the extracellular signal-regulated kinase (ERK)1/2 pathway in ethanol-induced NF-kappaB activation, because treatment with PD-98059, an ERK1/2 inhibitor, partially suppressed IL-1beta-induced NF-kappaB expression.

CONCLUSIONS

Chronic ethanol intake potentiates the action of the proinflammatory cytokine IL-1beta, enhancing the release and signaling response of IL-1beta in the hepatocyte, which in conjunction with other cytokines or LPS may exacerbate the inflammatory damage associated with alcoholic liver disease.

Cytokine gene polymorphisms and the susceptibility to liver cirrhosis in patients with chronic hepatitis C

BACKGROUND

The speed of fibrosis progression varies considerably between patients with chronic hepatitis C. This study analyzed whether cytokine gene polymorphisms are associated with a progressive course of the disease.

METHODS

Leukocyte DNA from 101 patients with chronic hepatitis C, 52 patients with hepatitis C virus (HCV)-induced cirrhosis and 200 Caucasian blood donors was prepared. Using PCR, RFLP and PAGE, gene polymorphism analysis of the interleukin (IL)1alpha( - 889), IL1beta( - 511 and +3954), IL1 receptor agonist (RA)(intron2 VNTR), IL4(intron3 VNTR) and TNFalpha( - 308) loci was performed.

RESULTS

Of the polymorphisms analyzed, IL1beta( - 511) and IL1RA(intron2 VNTR) were unevenly distributed between the study groups. The IL1 (- 511)*A2A2 genotype occurred significantly more often in chronic hepatitis C and HCV-induced liver cirrhosis than in the controls (P < 0.01, P < 0.05, respectively). Patients with HCV-induced cirrhosis displayed a significantly higher frequency of the IL1RA(intron2 VNTR)*A2 polymorphism than patients with chronic hepatitis C and controls (P < 0.05).

CONCLUSIONS

Although the IL1beta( - 511)*A2A2 genotype may increase the susceptibility to acquire chronic hepatitis C and IL1RA(intron2 VNTR)*A2 polymorphism is associated with disease progression to cirrhosis, our results indicate that the analyzed cytokine gene polymorphisms have an overall low impact on the natural course of chronic hepatitis C infection.

Investigation of alcohol metabolizing enzyme genes in Chinese alcoholics with avascular necrosis of hip joint, pancreatitis and cirrhosis of the liver

AIMS AND METHODS

Alcoholism may cause a range of diseases including avascular necrosis of the hip joint (AVN), cirrhosis of the liver, pancreatitis and oesophageal carcinoma. Chinese alcoholic patients diagnosed with AVN have a higher incidence of cirrhosis than of acute pancreatitis or oesophageal cancer. Thus, the aim of this study was to investigate genetic differences in polymorphisms of the alcohol-metabolizing enzymes ADH2, ADH3, ALDH2 and P4502E1 for subgroups of Chinese alcoholic patients, defined by diagnoses of AVN (n = 51), acute pancreatitis (n = 92) and liver cirrhosis (n = 159), and for 280 non-alcoholic patients.

RESULTS

Analysis revealed that ADH2*1 allele frequency was significantly lower for the alcoholic AVN than for the cirrhosis subgroup. However, no significant difference was found between the alcoholic AVN and pancreatitis subgroups. Furthermore, ALDH2*2 prevalence was not found to differ significantly between the alcoholic subgroups. When compared with our previously published data for alcoholic patients with oesophageal carcinoma, ADH2*1 carriage was significantly less frequent for the alcoholic AVN patients in the current study. Further, ALDH2*2 carriage was significantly less frequent for the alcoholic AVN subgroup than for the oesophageal carcinoma patients.

CONCLUSIONS

The allele frequencies for ADH2*1 and ALDH2*2 are different when comparing subpopulations of alcoholics defined by presence of specific alcohol-induced diseases, suggesting that genetic variation in alcohol-metabolizing enzyme genes accounts for, at least in part, the specific types of organ damage observed. We also found the combination of AVN and cirrhosis to be more prevalent than that of AVN and acute pancreatitis. In contrast, the ADH2 and ALDH2 allele frequencies for the AVN subgroup were more similar to those of the acute-pancreatitis than to the cirrhosis subgroup. These data indicate the possibility that other genetic variations may also influence the type of organ-specific complications in Chinese alcoholics.

Interleukin-10 gene -627 allele variants, not interleukin-I beta gene and receptor antagonist gene polymorphisms, are associated with atopic bronchial asthma

Asthma is an airway hyperresponsive disease characterized by the expression of multiple inflammatory genes, including cytokines. Interleukin-I and interleukin-10 (IL-1 and IL-10) are cytokines that might play a role in the process of inflammation and are therefore considered to be involved in the pathogenesis of bronchial asthma. The aim of this study was to test whether the polymorphisms of the promoter region and exon 5 of the IL-1 gene, intron 2 of the IL-1Ra gene, and -627 nucleotide (C/A) of the IL-10 gene could be genetic markers for the susceptibility of bronchial asthma. A normal control group made up of 47 healthy volunteers and 117 patients with bronchial asthma were examined in this study. We analyzed the variable number of tandem repeats at intron 2 of the IL-1Ra gene for the polymorphisms by polymerase chain reaction (PCR). PCR-based restriction analysis of the IL-1 gene polymorphisms of the promoter region and exon 5 was carried out by the endonucleases Ava I and Taq I, respectively. The IL-10 gene -627 C/A polymorphisms were investigated by PCR-based restriction analysis. The distribution of CC homozygotes in the IL-10 gene was significantly lower in asthma patients than in controls (P=0.013, OR=3.599, 95% CI=1.240 approximately 10.441). The polymorphisms studied in the IL-1 genes did not reveal any significant association with bronchial asthma when compared with the control group (promoter region by chi-square test, P=0.627; exon 5 region by Fisher's exact test, P=0.403). Only two alleles of the IL-1Ra gene corresponding to one and two copies of an 86-base pair sequence repeat were identified by PCR in the control group. There were three alleles found in the asthmatic patient group. The results revealed no significant differences between normal individuals and asthma patients (P=0.454, Fisher's exact test). The IL-10 gene -627 "A" allele is an associated risk factor of developing atopic asthma.

Advances in alcoholic liver disease

Alcoholic liver disease (ALD) remains a major cause of morbidity and mortality worldwide. For example, the Veterans Administration Cooperative Studies reported that patients with cirrhosis and superimposed alcoholic hepatitis had a 4-year mortality of >60%. Interactions between acetaldehyde, reactive oxygen and nitrogen species, inflammatory mediators and genetic factors appear to play prominent roles in the development of ALD. The cornerstone of therapy for ALD is lifestyle modification, including drinking and smoking cessation and losing weight, if appropriate. Nutrition intervention has been shown to play a positive role on both an inpatient and outpatient basis. Corticosteroids are effective in selected patients with alcoholic hepatitis and pentoxifylline appears to be a promising anti-inflammatory therapy. Some complementary and alternative medicine agents, such as milk thistle and S-adenosylmethionine, may be effective in alcoholic cirrhosis. Treatment of the complications of ALD can improve quality of life and, in some cases, decrease short-term mortality.

S-adenosylmethionine (AdoMet) modulates endotoxin stimulated interleukin-10 production in monocytes

IL-10 is produced by a large variety of cells including monocytes, macrophages, B and T lymphocytes, as well as natural killer cells and is an important suppressor for both immunoproliferative and inflammatory responses. IL-10 exerts antifibrotic effects in the liver, and decreased monocyte synthesis of IL-10 is well documented in alcoholic cirrhosis. Intracellular deficiency of S-adenosylmethionine (AdoMet) is a hallmark of toxin-induced liver injury. Although the administration of exogenous AdoMet attenuates this injury, the mechanisms of its actions are not fully established. This study was performed to investigate the effect of exogenous AdoMet on IL-10 production in LPS-stimulated RAW 264.7 cells, a murine macrophage cell line. Our results demonstrated that exogenous AdoMet administration enhanced both protein production and gene expression of IL-10 in RAW 264.7 cells. Ethionine, an inhibitor for methionine adenosyltransferases, inhibited LPS-stimulated IL-10 both at the protein and mRNA levels. Exogenous AdoMet increased the intracellular cAMP concentration as early as 3 h and continued for 24 h after AdoMet treatment; however, the inhibitors for both adenylyl cyclase and PKA did not significantly affect IL-10 production. On the basis of these results, we conclude that AdoMet administration may exert its anti-inflammatory and hepatoprotective effects, at least in part, by enhancing LPS-stimulated IL-10 production.

Genetic polymorphisms and the progression of liver fibrosis: a critical appraisal

Liver fibrosis is a highly dynamic process in which multiple genes interact with environmental factors. Recent human epidemiologic studies have identified possible polymorphisms in a number of candidate genes that influence the progression of liver fibrosis. These genetic factors could explain the broad spectrum of responses to the same etiologic agent found in patients with chronic liver diseases. Polymorphisms in genes encoding immunoregulatory proteins, proinflammatory cytokines, and fibrogenic factors may influence disease progression in patients with alcohol-induced liver disease, primary biliary cirrhosis, or chronic hepatitis C. However, some of the studies have yielded contradictory results. For example, conflicting results have been obtained in studies assessing the role of mutations in the hemochromatosis gene on fibrosis progression in patients with chronic hepatitis C. Large-scale, well-designed studies are required to clarify the actual role of this factor and other genetic variants in liver fibrosis.

What is toxicology and how does toxicity occur?

Toxicology has matured since it was defined as the 'science of poisons'. Modern toxicology is no longer anthropocentric but takes on different views at various biological systems, including ecosystems. Each will interact specifically when exposed to defined chemical agents, including drugs. Adverse effects during drug therapy or after (accidental) poisoning are the result of some negative interactions between the agent and the exposed biological system. Toxicity is no longer a specific property of drugs and chemicals but an operative term to describe the adverse outcome of a specific drugs-host interaction. Newer developments in toxicology have focused on the host. Toxicogenetics continues to provide answers to variations of host response to xenobiotics, including drugs. Clinically relevant genetic polymorphisms and gene defects have been detected, and their number is rapidly growing. The key to understanding is in the host proteins that interact with the drug and mediate the cellular response. Hence, the proteom, i.e. the complete set of proteins of a cell, an individual or a species, determines how an exposed biological system may interact with the manifold of different xenobiotics. Structure-activity studies try to find out useful predictive parameters for risk and toxicity assessment.

Genetic and epigenetic factors in autoimmune reactions toward cytochrome P4502E1 in alcoholic liver disease

Autoimmune reactions are often associated with alcoholic liver disease; however, the mechanisms responsible are largely unknown. This study investigates the potential role of the immune response against hydroxyethyl free radical (HER)-derived antigens and of polymorphisms in immunoregulatory genes in the development of anti-cytochrome P4502E1 (CYP2E1) autoantibodies in alcohol abusers. Immunoglobulin G (IgG) recognizing human CYP2E1 and HER-derived epitopes were measured by microplate immunosorbent assay in the sera of 90 patients with alcoholic fibrosis/cirrhosis (ALD), 37 heavy drinkers without liver disease or steatosis only (HD), and 59 healthy subjects. Single nucleotide polymorphisms in the interleukin 10 (IL-10) promoter and in exon 1 of the cytotoxic T-lymphocyte antigen-4 (CTLA-4) gene were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis. The titers and frequency of anti-CYP2E1 autoantibodies were significantly higher in ALD than in HD subjects or controls. ALD patients with anti-HER IgG had higher titers and a 4-fold increased risk (OR: 4.4 [1.8-10.9]) of developing anti-CYP2E1 autoantibodies than subjects without anti-HER antibodies. The mutant CTLA-4 G allele, but not the IL-10 polymorphism, was associated with an enhanced risk of developing anti-CYP2E1 IgG (OR: 3.8 [1.4-10.3]). CTLA-4 polymorphism did not influence antibody formation toward HER-antigens. ALD patients with concomitant anti-HER IgG and the CTLA-4 G allele had a 22-fold higher (OR: 22.9 [4.2-125.6]) risk of developing anti-CYP2E1 autoreactivity than subjects negative for these factors. In conclusion, antigenic stimulation by HER-modified CYP2E1 combined with an impaired control of T-cell proliferation by CTLA-4 mutation promotes the development of anti-CYP2E1 autoantibodies that might contribute to alcohol-induced liver injury.

Genome-wide analysis of hepatic fibrosis in inbred mice identifies the susceptibility locus Hfib1 on chromosome 15

BACKGROUND & AIMS

Host genetic factors are likely to contribute to the variable course of hepatic fibrosis in response to chronic liver injury. Similarly, the fibrotic response differs among inbred mouse strains after challenge with CCl(4). Our aim was to identify unknown susceptibility loci for hepatic fibrosis in a cross between fibrosis-susceptible and -resistant inbred mice.

METHODS

Seven inbred mouse strains were treated with CCl(4), and hepatic fibrosis was phenotypically characterized by histology, hepatic hydroxyproline levels, and serum surrogate markers. F(1) hybrids of susceptible BALB/cJ and resistant A/J inbred strains were intercrossed to obtain 358 F(2) progeny. Quantitative trait loci (QTL) that determine hepatic fibrosis were identified by genome-wide interval mapping and haplotype analysis.

RESULTS

In this model, marked strain differences in fibrosis susceptibility exist, with BALB/c inbred mice being most susceptible. The hydroxyproline levels of F(1) mice resemble the resistant parental strains, indicating that fibrosis susceptibility is a recessive trait. QTL analysis identifies a susceptibility locus on chromosome 15 that significantly affects the stage of fibrosis and hydroxyproline levels. According to standard nomenclature, this locus is called Hfib1 (hepatic fibrogenic gene 1). Hfib1 is defined by genetic markers D15Mit26 and D15Mit122. A suggestive QTL on chromosome 2 colocalizes with the complement factor 5 gene, known to be mutated in the resistant strain A.

CONCLUSIONS

The set of inbred strains provides a framework for systematic analysis of fibrogenic genes. QTL mapping is useful to identify genetic susceptibility loci for hepatic fibrosis that might harbor new molecular targets for antifibrotic drug design.

Mechanistic perspectives on sulfonamide-induced cutaneous drug reactions

PURPOSE OF REVIEW

Idiosyncratic drug reactions continue to limit the therapeutic utility of sulfonamide drugs because of their associated morbidity and mortality. Cutaneous reactions are the predominant reasons for withdrawal of such drugs from use in patients. As a consequence of the recognized metabolic and immunologic capability of the skin, an understanding of the pathogenic role of this tissue in the development of sulfonamide-induced cutaneous drug reactions may provide insight into the mechanisms and risk factors for these and other adverse drug events.

RECENT FINDINGS

In the present review we discuss currently available mechanistic information, including issues related to drug bioactivation and adduct formation, immunoresponsiveness, and immune dysregulation, for the development of sulfonamide-induced (delayed-type) cutaneous drug reactions. The potential application of findings from several related areas of research are also discussed within the context of the pathogenesis of these cutaneous reactions.

SUMMARY

Despite progress, numerous unresolved issues support the testing of novel hypotheses, the search for additional risk factors, and the need for a global approach, including links between laboratory and clinical paradigms. These issues must be addressed if we are to gain an understanding of the mechanistic bases for these cutaneous drug reactions.

Single-nucleotide polymorphisms in the interleukin-10 gene: differences in frequencies, linkage disequilibrium patterns, and haplotypes in three United States ethnic groups

Interleukin-10 (IL-10) is a cytokine that seems to function as a downregulator of the innate (nonadaptive) immune system. Approximately three-quarters of interindividual variability in human IL-10 levels has been attributed to genetic variation, and there is evidence suggesting a potential role for IL-10 in a range of human diseases. To provide a basis for haplotype analysis and future disease association studies, we characterized genetic variation in IL10 by sequencing all exons, and 2.5 kb of the 5'- and the 3'-flanking region in a panel of DNA samples from 24 African Americans, 23 European Americans, and 24 Hispanic Americans. The region sequenced was found to contain 28 single-nucleotide polymorphisms (SNPs), 16 with frequency >2% and 14 with frequency >5%. All SNPs with frequency >5% were present in subjects from all three populations. No SNP caused amino acid changes. Differences in pairwise linkage-disequilibrium (LD) patterns and in SNP and haplotype frequency distributions among the three populations may be of potential importance for disease association studies.

HLA and cytokine gene polymorphisms in biliary atresia

BACKGROUND/AIMS

Extrahepatic biliary atresia remains one of the major hepatic causes of death in early childhood. Though a number of hypotheses have been developed to account for this disease, its aetiopathogenesis is poorly understood. One possibility is that this is an immune mediated disease which occurs following either toxic or infectious insult in a genetically susceptible host. Earlier studies suggested weak HLA associations but these remain unconfirmed. More recently studies of viral and autoimmune liver disease have begun to investigate non-MHC immunoregulatory gene polymorphisms.

METHODS

In the present study we used molecular genotyping to investigate selected HLA A, B, DRB1, DQA1, DQB1 and DPB1 alleles as well as polymorphisms in the interleukin-1 gene family, interleukin-10 promoter sequence and tumour necrosis factor alpha promoter genes in 101 children referred for surgical assessment with extra hepatic biliary atresia. Genotyping data were compared with those of 134 racially and geographically matched healthy adult health care workers.

RESULTS AND CONCLUSIONS

Overall there were no statistically significant differences in the distribution of any of the genes tested comparing patients and controls. These data suggest that biliary atresia is not an HLA-associated disease and that polymorphisms in both the interleukin-1 and interleukin-10 genes are not risk factors for this disease.

Single nucleotide polymorphisms and microsatellite alleles of tumor necrosis factor alpha and interleukin-10 genes and the risk of advanced chronic alcoholic liver disease

BACKGROUND

Only a minority of ethanol abusers develop advanced chronic alcoholic liver disease (CALD). In CALD there is a imbalance between TNF alpha and IL-10, which may be modulated by several polymorphisms at both genetic loci. Our aim has been to elucidate the possible relation between these polymorphisms and the risk of CALD.

PATIENTS AND METHODS

147 patients with advanced CALD and 355 healthy controls (all white Spaniards) were included. TNF alpha biallelic single nucleotide polymorphisms (SNP) at positions -238, -308, and -376 and IL-10 biallelic SNP at positions -597, - 824, and - 1087 were investigated by polymerase chain reaction (PCR) amplification and dot blot hybridization. Moreover, polymorphic microsatellites TNFa, TNFb, IL-10.R and IL-10.G were investigated in a multiplex PCR and alleles were estimated in an automatic sequencer.

RESULTS

No differences were found in the distribution of any of the studied polymorphisms, except by an excess of the haplotype formed by the allele 11 of the microsatellite IL-10.G and the GCC arrangement of the SNPs at the promoter of IL-10 gene in patients (15.7 vs. 8.24%, odds ratio: 2.08, 95% C.I. = 1.31-3.31).

CONCLUSIONS

The studied polymorphisms at TNF alpha and IL-10 genetic loci are not clearly related to the risk of CALD. The excess of G11-GCC haplotype found in CALD patients needs independent confirmation.

Lymphocyte-mediated liver injury in alcohol-related hepatitis

The pathogenesis of alcohol-related liver disease (ALD) remains inadequately explained. Increasing alcohol intake is associated with an increased risk of ALD, but many heavy drinkers develop no liver damage. An explanation for ALD susceptibility requires theories that extend beyond a biochemical understanding of alcohol metabolism. Several hepatic cell populations are involved in the pathogenesis of liver injury. The liver-associated lymphocyte (LAL) response to alcohol intake plus immune stimulation may determine susceptibility to liver damage. We have isolated rat LALs and demonstrated the following: (1) Liver-associated lymphocytes differ from the peripheral blood lymphocyte pool; the CD8:CD4 ratio is higher in the LAL population than in peripheral blood. (2) Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 production by these cells is suppressed by regular alcohol intake. (3) Tumor necrosis factor-alpha and interleukin-6 production by LALs is increased after parenteral administration of concanavalin A (Con A) and by Con A in in vitro LAL cultures obtained from healthy (control) and ethanol-consuming rats. (4) In vivo stimuli that lead to increased cytokine production by LALs lead, within 12-24 h, to increased hepatocyte necrosis [elevated alanine aminotransferase (ALT) levels] and apoptosis. (5) Liver-associated lymphocytes isolated from ethanol-consuming rats, transferred to non-ethanol-consuming rats, confer on the latter animals an ethanol-consuming response to Con A. (6) Cytokine release by LALs is quantitatively as significant as that from Kupffer cells after exposure to lipopolysaccharide. (7) In co-culture studies inhibition of TNF-alpha activity reduces hepatocyte apoptosis induced in the presence of activated LALs. (8) Finally, nuclear factor-kappa B inhibition decreases production of nitric oxide and TNF-alpha, with an associated reduction in hepatocyte apoptosis. In summary, our study findings support the suggestion that a role for LALs exists in the pathogenesis of alcohol and Con A-mediated liver disease.

Iron regulation of hepatic macrophage TNFalpha expression

Sustained TNFalpha induction is central to the pathogenesis of chronic liver disease including alcoholic liver disease (ALD). However, molecular understanding of this abnormality at the cellular level remains elusive. Redox regulation of NF-kappaB is critical in the transcriptional control of TNFalpha expression. Evidence supports that increased iron storage in hepatic macrophages (HM) is causally associated with accentuated and sustained NF-kappaB activation in these cells in ALD. Treatment of cultured HM with a lipophilic iron chelator (deferiprone) abrogates LPS-induced NF-kappaB activation. HM from an animal model of ALD have increased nonheme iron content accompanied by increased generation of EPR-detected radicals, NF-kappaB activation, and TNFalpha induction, all of which are normalized by ex vivo treatment of the cells with deferiprone. A moderate increase in the nonheme iron content in HM by erythrophagocytosis, promotes subsequent LPS-stimulated NF-kappaB activation in a hemeoxygenase-dependent manner. Recent evidence also suggests a role of intracellular low molecular weight iron in the early signal transduction for LPS-mediated NF-kappaB activation.

Protection against acetaminophen-induced liver injury and lethality by interleukin 10: role of inducible nitric oxide synthase

Mechanistic study of idiosyncratic drug-induced hepatitis (DIH) continues to be a challenging problem because of the lack of animal models. The inability to produce this type of hepatotoxicity in animals, and its relative rarity in humans, may be linked to the production of anti-inflammatory factors that prevent drug-protein adducts from causing liver injury by immune and nonimmune mechanisms. We tested this hypothesis by using a model of acetaminophen (APAP)-induced liver injury in mice. After APAP treatment, a significant increase was observed in serum levels of interleukin (IL)-4, IL-10, and IL-13, cytokines that regulate inflammatory mediator production and cell-mediated autoimmunity. When IL-10 knockout (KO) mice were treated with APAP, most of these mice died within 24 to 48 hours from liver injury. This increased susceptibility to APAP-induced liver injury appeared to correlate with an elevated expression of liver proinflammatory cytokines, tumor necrosis factor (TNF)-alpha, and IL-1, as well as inducible nitric oxide synthase (iNOS). In this regard, mice lacking both IL-10 and iNOS genes were protected from APAP-induced liver injury and lethality when compared with IL-10 KO mice. All strains, including wild-type animals, generated similar amounts of liver APAP-protein adducts, indicating that the increased susceptibility of IL-10 KO mice to APAP hepatotoxicity was not caused by an enhanced formation of APAP-protein adducts. In conclusion, these findings suggest that an important feature of the normal response to drug-induced liver injury may be the increased expression of anti-inflammatory factors such as IL-10. Certain polymorphisms of these factors may have a role in determining the susceptibility of individuals to idiosyncratic DIH.

Association of polymorphisms of the transforming growth factor-beta1 gene with the rate of progression of HCV-induced liver fibrosis

BACKGROUND

The objective of the present study was to elucidate possible relationships between four polymorphisms of the TGF-beta1 gene (-800G>A; -509C>T; Leu10Pro; Arg25Pro) and stage, histological activity grade and progression rate of liver fibrosis, classified according to the METAVIR-score.

METHODS

Three study groups, i.e. 48 patients with hepatic fibrosis (26 with known duration of hepatitis C virus infection), 47 patients with non-fibrotic diseases and 50 healthy blood donors, were analyzed for TGF-beta1 polymorphisms using ARMS-PCR and sequence analysis. The concentrations of total TGF-beta1 in plasma and of hyaluronan, P-III-NP and activities of transminases in serum were measured.

RESULTS

The presence of proline at codons 10 and/or 25 was associated with a faster progression of fibrosis than other polymorphisms. Patients with the genotype (25)ArgPro developed fibrosis significantly faster (0.23 units/year) than those having (25)ArgArg (0.08 units/year). Similarly, the fibrosis progression rate of patients with genotypes (10)LeuPro and (10)ProPro was almost three times as fast as of those having genotype (10)LeuLeu. Stage and histological activity grade of fibrosis in (25)ArgPro in comparison to (25)ArgArg were higher. Also (10)LeuPro showed a higher average stage of fibrosis than (10)LeuLeu. The TGF-beta1 plasma concentrations of patients with hepatic fibrosis were not significantly different between carriers of (25)ArgArg and (25)ArgPro genotypes. The frequency of the genotype (25)ArgPro in liver fibrotic patients was about three times that of the control group whereas the frequency distribution of the genotype (25)ArgArg tended to lower frequency in the fibrosis group. TGF-beta1-promoter polymorphisms did not show any correlation with stage, grade or progression of liver fibrosis.

CONCLUSION

Our results indicate that the heterozygous ArgPro of codon 25 predicts significantly faster fibrotic progression of chronic hepatitis C than the homozygous (25)ArgArg genotype. The homozygous LeuLeu genotype of codon 10 showed a slow progression of fibrosis.

Genetic contribution of the interleukin-10 promoter polymorphism in endometriosis susceptibility

PROBLEM

Interleukin-10 (IL-10) is an important immunomodulatory cytokine. The aim of this study was to investigate whether polymorphisms of the IL-10 gene promoter polymorphisms may be responsible in part for genetic susceptibility to endometriosis.

METHODS OF STUDY

Polymorphisms at position -1082 and -592 in the IL-10 promoter region were determined in 196 patients with endometriosis and 160 fertile healthy women by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP).

RESULTS

There were no statistically significant differences in the genotype and allele frequencies of IL-10 promoter polymorphism between the endometriosis and control groups. However, when subgrouped according to clinical features, the frequencies of the -592*CC genotype and -592*C allele were significantly increased in patients with autoantibodies to carbonic anhydrase II (anti-CA II ab) compared with controls.

CONCLUSION

IL-10 promoter polymorphisms were associated with the production of anti-CA II ab in patients with endometriosis, suggesting a role in the genetic susceptibility for endometriosis.

Candidate gene case-control association studies: advantages and potential pitfalls

There is increasing information on the importance of genetic polymorphisms in human genes. Polymorphisms occur on average once every 500-1000 base pairs in the human genome and are useful in the identification of genes involved in human disease. Some genetic polymorphisms have functionally significant effects on the gene product and are the most useful type of polymorphism in disease association studies while others are simply useful markers. There are two main approaches using polymorphisms in the identification of genes involved in polygenic diseases. The first involves examining inheritance patterns for genetic polymorphisms in family studies and the second case-control studies which compare genotype frequencies for candidate disease genes in unrelated individuals with the disease and healthy controls. Use of family studies is generally the preferred approach but this is only feasible if the genetic component of the disease is relatively strong, DNA samples are available from other family members and the disease is relatively easy to diagnose and is not stigmatized. Population case-control studies are useful both as an alternative and an adjunct to family studies. When performing case-control studies factors such as study design, methods for recruitment of cases and controls, functional significance of polymorphisms chosen for study and statistical analysis of data require close attention to ensure that only genuine associations are detected. To illustrate some potential problems in the design and interpretation of association studies, some specific examples of association studies on drug response and on disease susceptibility involving receptor genes, cytochrome P450 and other xenobiotic metabolizing enzyme genes and immune system genes including TNF-alpha, IL-10 and the IL-4 receptor are discussed.

Alcoholic liver disease: new insights into mechanisms and preventative strategies

Alcoholic liver disease has a known aetiology but a complex pathogenesis. It is an extremely common disease with a high mortality, but the reason why only a relatively small proportion of heavy drinkers progress to advanced disease remains elusive. Accumulating evidence points towards an elaborate interplay between metabolism, inflammation and immunity in the development of steatosis, hepatitis and fibrosis. These complex pathways leading to liver injury offer many potential susceptibility loci, as well as sites for potential therapeutic intervention.

Association of the tumour necrosis factor alpha -308 but not the interleukin 10 -627 promoter polymorphism with genetic susceptibility to primary sclerosing cholangitis

BACKGROUND AND AIMS

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown aetiology. Abnormalities in immune regulation and genetic associations suggest that PSC is an immune mediated disease. Several polymorphisms within the tumour necrosis factor alpha (TNF-alpha) and interleukin 10 (IL-10) promoter genes have been described which influence expression of these cytokines. This study examines the possible association between polymorphisms at the -308 and -627 positions in the TNF-alpha and IL-10 promoter genes, respectively, and susceptibility to PSC.

METHODS

TNF-alpha -308 genotypes were studied by polymerase chain reaction (PCR) in 160 PSC patients from Norway and the UK compared with 145 ethnically matched controls. IL-10 -627 genotypes were studied by PCR in 90 PSC patients compared with 84 ethnically matched controls.

RESULTS

A total of 16% of Norwegian PSC patients and 12% of British PSC patients were homozygous for the TNF2 allele compared with 3% and 6% of respective controls. The TNF2 allele was present in 60% of PSC patients versus 30% of controls (OR(combined data)=3.2 (95% confidence intervals (CI) 1.8--4.5); p(corr)=10(-5)). The association between the TNF2 allele and susceptibility to PSC was independent of the presence of concurrent inflammatory bowel disease (IBD) in the PSC patients; 61% of PSC patients without IBD had TNF2 compared with 30% of controls (OR(combined data)=3.2 (95% CI 1.2--9.0); p(corr)=0.006 ). There was no difference in the -627 IL-10 polymorphism distributions between patients and controls in either population. The increase in TNF2 allele in PSC patients only occurs in the presence of DRB1*0301 (DR3) and B8. In the combined population data, DRB1*0301 showed a stronger association with susceptibility to PSC than both the TNF2 and B8 alleles (OR(combined data)=3.8, p(corr)=10(-6) v OR(combined data)=3.2, p(corr)=10(-5) v OR(combined data )=3.41, p(corr)=10(-4), respectively).

CONCLUSIONS

This study identified a significant association between possession of the TNF2 allele, a G-->A substitution at position -308 in the TNF-alpha promoter, and susceptibility to PSC. This association was secondary to the association of PSC with the A1-B8-DRB1*0301-DQA1*0501-DQB1*0201 haplotype. No association was found between the IL-10 -627 promoter polymorphism and PSC.

Current concepts in the pathogenesis of alcoholic liver injury

Alcoholic liver disease (ALD) develops as a consequence of priming and sensitizing mechanisms rendered by cross-interactions of primary mechanistic factors and secondary risk factors. This concept, albeit not novel, is becoming widely accepted by the field, and more research is directed toward identifying and characterizing the interfaces of the cross-interactions to help understand individual predisposition to the disease. Another pivotal development is the beginning of cell type-specific research to elucidate specific contributions not only of hepatocytes, but also of hepatic macrophages, liver-associated lymphocytes, sinusoidal endothelial cells, and hepatic stellate cells to sensitizing and priming mechanisms. In particular, the critical role of hepatic macrophages has been highlighted and the priming mechanisms concerning this paracrine effect have been proposed. Glutathione depletion in hepatocyte mitochondria is considered the most important sensitizing mechanism. One of the contributing factors is decreased methionine metabolism. Remaining key questions include how altered methionine metabolism contribute to the pathogenesis of ALD; how cross-talk among nonparenchymal liver cells or between nonparenchymal cells and hepatocytes leads to ALD; how dysfunctional mitochondria determine the type of cell death in ALD; and what secondary factors are critical for the development of advanced ALD such as alcoholic hepatitis and cirrhosis.