Susceptibility to primary sclerosing cholangitis is associated with polymorphisms of intercellular adhesion molecule-1

The Role of Genetic and Immune Factors for the Pathogenesis of Primary Sclerosing Cholangitis in Childhood

Primary sclerosing cholangitis (PSC) is a rare cholestatic liver disease characterized by chronic inflammation of the biliary tree resulting in liver fibrosis. PSC is more common in male less than 40 years of age. The diagnosis of PSC is based on clinical, laboratory, image, and histological findings. A biochemical profile of mild to severe chronic cholestasis can be observed. Endoscopic retrograde cholangiography is the golden standard method for diagnosis, but magnetic resonance cholangiography is currently also considered a first-line method of investigation. Differences in clinical and laboratory findings were observed in young patients, including higher incidence of overlap syndromes, mostly with autoimmune hepatitis, higher serum levels of aminotransferases and gamma-glutamyl transferase, and lower incidence of serious complications as cholangiocarcinoma. In spite of the detection of several HLA variants as associated factors in large multicenter cohorts of adult patients, the exact role and pathways of these susceptibility genes remain to be determined in pediatric population. In addition, the literature supports a role for an altered immune response to pathogens in the pathogenesis of PSC. This phenomenon contributes to abnormal immune system activation and perpetuation of the inflammatory process. In this article, we review the role of immune and genetic factors in the pathogenesis of PSC in pediatric patients.

Current Concepts in Primary Biliary Cirrhosis and Primary Sclerosing Cholangitis

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are chronic, cholestatic diseases of the liver with common clinical manifestations. Early diagnosis and treatment of PBC slows progression and decreases the need for transplant. However, one-third of patients will progress regardless of treatment. Bilirubin <1.0 and alkaline phosphatase <2.0 x the upper limit of normal at 1 year after treatment appear to predict 10-year survival. Ursodeoxycholic acid (UDCA) is the recommended treatment for PBC, and recent studies with obeticholic acid showed promising results for UDCA non-responders. Unlike PBC, no therapy has been shown to alter the natural history of PSC. The recommended initial diagnostic test for PSC is magnetic resonance cholangiopancreatography, typically showing bile duct wall thickening, focal bile duct dilatation, and saccular dilatation of the intra- and/or extrahepatic bile ducts. Immunoglobulin 4-associated cholangitis must be excluded when considering the diagnosis of PSC, to allow for proper treatment, and monitoring of disease progression. In addition to the lack of therapy, PSC is a pre-malignant condition and close surveillance is indicated.

Intercellular adhesion molecule-1 polymorphisms in patients with Behçet disease: a meta-analysis

OBJECTIVES

To examine the association between the Intercellular adhesion molecule-1 (ICAM1) Polymorphisms and Behçet's disease.

METHODS

MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials for original studies up to July 31, 2012 were searched for relevant studies. All pooled odds ratios (ORs) were derived from either fixed or random-effects model with its 95% confidence intervals (CI).

RESULTS

Five studies met the inclusion criteria. Overall, ICAM1 E469 (OR = 1.45, 95% CI = 1.06-1.97), genotype ICAM1 469 E/E (OR = 1.45, 95% CI = 1.09-1.94), ICAM1 241 G/R (OR = 3.65, 95% CI = 1.69-7.89), had significant associations with Behçet's disease. A significant association was found between the presence of skin lesions and genotype ICAM1 469 E/E (OR = 3.52, 95% CI = 1.62-7.66).

CONCLUSIONS

Behçet's disease was associated with the ICAM1 E469, genotype ICAM1 469 E/E, ICAM1 241 G/R polymorphisms in different ethnic groups. Among patients, genotype ICAM1 469 E/E had a significant association with skin lesion.

Primary sclerosing cholangitis: diagnosis, prognosis, and management

Primary sclerosing cholangitis (PSC) is a chronic immune-mediated disease of the liver of unclear etiology, characterized by chronic inflammation and fibrosis of bile ducts. It primarily affects middle-aged men and is associated with 4-fold increased mortality as compared with an age- and sex-matched population. Progressive biliary and hepatic damage results in portal hypertension and hepatic failure in a significant majority of patients over a 10- to 15-year period from the initial diagnosis. In addition, PSC confers a markedly increased risk of hepatobiliary cancer, including cholangiocarcinoma and gallbladder cancer, as compared with the general population, and cancer is the leading cause of mortality in patients with PSC. It is associated with inflammatory bowel disease in 70% of patients and increases the risk of colorectal cancer almost 10-fold. Despite significant research efforts in this field, the pathogenic mechanisms of PSC are still incompletely understood, although growing evidence supports the role of genetic and immunologic factors. There are no proven medical therapies that alter the natural course of the disease. Thus, liver transplantation is the only available treatment for patients with advanced PSC, with excellent outcomes in this population.

Cutting edge issues in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic inflammatory liver disease characterized by the destruction of medium- to large-sized bile ducts and intense concentric fibrosis. Complications from PSC include bacterial cholangitis, cirrhosis, and cholangiocarcinoma and a therapy that might alter the natural history of the disease remains lacking. Our understanding of the pathogenesis of PSC also remains rudimentary but the strong association between PSC and inflammatory bowel disease suggest causal links between the diseases. The male predominance in PSC, lack of a defined, pathogenic auto-antigen, and the potential role of the innate immune system suggest that PSC may be due to dysregulation of immunity rather than a classic autoimmune disease. However, PSC shares several genetic susceptibility loci with other autoimmune diseases including the human leukocyte antigen DRB01*03 haplotype. The precise immune response of PSC is largely unknown but likely involves activation of the innate immune system by bacterial components delivered to the liver via the portal vein. Induction of adhesion molecules and chemokines leads to the recruitment of intestinal lymphocytes. Bile duct injury results from the sustained inflammation and production of inflammatory cytokines. Biliary strictures may cause further damage as a result of bile stasis and recurrent secondary bacterial cholangitis. Progress in our basic understanding of PSC is desperately needed in order to rationally design new therapeutic approaches to this disease.

Intercellular adhesion molecule-1 E469K gene polymorphism and coronary artery disease in the Chinese population: a meta-analysis involving 3065 subjects

BACKGROUND

The intercellular adhesion molecule-1 (ICAM-1) E469K gene polymorphism has been implicated in increased coronary artery disease (CAD) susceptibility, but the individual study results are still controversial.

HYPOTHESIS

The ICAM-1 E469K gene polymorphism may be associated with CAD risk.

METHODS

The current meta-analysis involving 3065 subjects and 11 separate studies was conducted to explore the relationship between the ICAM-1 E469K gene polymorphism and CAD in the Chinese population. The pooled odds ratio (ORs) for the distribution of K allele frequency of ICAM-1 E469K gene and its corresponding 95% confidence interval (CI) was assessed by random effect model.

RESULTS

The distribution of the K allele frequency was 0.67 for the CAD group and 0.60 for the control group. The pooled OR for the distribution of the K allele frequency of the ICAM-1 E469K gene was 1.32 (95% CI, 1.02-1.72; P(heterogeneity) < 0.00001; inconsistency index I(2) = 81.8%). The association between the ICAM-1 E469K gene polymorphism and CAD in the Chinese population was significant (P = 0.04).

CONCLUSIONS

In the Chinese population, the distribution of the K allele frequency of the ICAM-1 E469K gene was indicated to be associated with CAD risk. The K allele of the ICAM-1 E469K gene might predispose to the CAD susceptibility.

Pathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) represents a chronic cholestatic liver disease with fibroobliterative sclerosis of intra- and/or extrahepatic bile ducts, eventually leading to biliary cirrhosis. The association with human leukocyte antigen (HLA) and non-HLA haplotypes and the presence of autoantibodies in sera of PSC patients support a crucial role for immune-mediated mechanisms in the initiation and progression of PSC. The strong clinical association between PSC and inflammatory bowel diseases led to intriguing pathogenetic concepts, in which the inflamed gut with translocation of bacterial products and homing of gut-primed memory T lymphocytes via aberrantly expressed adhesion molecules plays a fundamental role. Genetically or chemically modified bile composition was shown to induce sclerosing cholangitis and liver fibrosis in a number of animal models ("toxic bile concept"). The potential role of vascular injury with ischemia of bile duct epithelium cells in the development of sclerosing cholangitis is supported by animal models of endothelial cell injury showing close morphological similarities with human PSC.

[Primary sclerosing cholangitis: diagnosis, prognosis and treatment]

Primary sclerosing cholangitis is a chronic cholestatic disease characterized by inflammation with fibrosis and obliteration of the intra- and extrahepatic bile ducts. This disease is usually associated with ulcerative colitis. The process of chronic cholestasis eventually leads to biliary cirrhosis. The prevalence of primary sclerosing cholangitis is low in southern Europe but is especially high in Scandinavian countries. The etiopathogenesis is unknown but immune disorders, potential toxic agents or intestinal infections, ischemic injury to the bile ducts, and possibly alterations in hepatobiliary transporters are known to play a role. The disease manifests at the age of approximately 40 years, mainly in men with clinical and laboratory features of cholestasis but may also be asymptomatic. There are specific forms in which the small intrahepatic bile ducts are involved, mainly affecting children, as well as overlap syndromes with autoimmune hepatitis. A form characterized by an increase in IgG4 has been described, which is usually associated with autoimmune pancreatitis. The key diagnostic procedure is endoscopic retrograde cholangiography, although magnetic resonance cholangiography is the first diagnostic procedure that should be used since it is equally informative and non-invasive. Liver biopsy is not essential for diagnosis. Primary sclerosing cholangitis is a progressive disease with a probability of transplant-free survival of 18 years in asymptomatic forms and of 8.5 years in symptomatic forms. Cholangiocarcinoma can result from the disease and confers a poor prognosis. There is no specific treatment although ursodeoxycholic acid improves the biochemical alterations of cholestasis. Liver transplantation is the last therapeutic resort with good results in terms of survival although the disease can recur in the transplanted liver.

Primary sclerosing cholangitis: overview and update

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disorder that most commonly affects middle-aged men. PSC is strongly associated with IBD, and in this setting the risk of colorectal cancer is markedly increased. Cholangiocarcinoma, and its devastating consequences, is another well-recognized complication of PSC. This condition tends to progress to end-stage liver disease, and patients with PSC have reduced survival rates compared with the general population. Despite significant research efforts in this field, the pathogenetic mechanisms of PSC are still incompletely understood, although growing evidence supports the role of genetic and immunologic factors. Effective medical therapy is lacking; liver transplantation is the only curative treatment modality, with excellent outcomes in this patient population.

The immunobiology of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease histologically characterized by the presence of intrahepatic and/or extrahepatic biliary duct concentric, obliterative fibrosis, eventually leading to cirrhosis. Approximately 75% of patients with PSC have inflammatory bowel disease. The male predominance of PSC, the lack of a defined, pathogenic autoantigen, and the potential role of the innate immune system suggest that it may be due to dysregulation of immunity rather than a classic autoimmune disease. However, PSC is associated with several classic autoimmune diseases, and the strongest genetic link to PSC identified to date is with the human leukocyte antigen DRB01*03 haplotype. The precise immunopathogenesis of PSC is largely unknown but likely involves activation of the innate immune system by bacterial components delivered to the liver via the portal vein. Induction of adhesion molecules and chemokines leads to the recruitment of intestinal lymphocytes. Bile duct injury results from the sustained inflammation and production of inflammatory cytokines. Biliary strictures may cause further damage as a result of bile stasis and recurrent secondary bacterial cholangitis. Currently, there is no effective therapy for PSC and developing a rational therapeutic strategy demands a better understanding of the disease.

ICAM-1 (Lys469Glu) and PECAM-1 (Leu125Val) polymorphisms in diffuse astrocytomas

Cell adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) play an important role in glioma invasion and angiogenesis. The aim of this study was to investigate whether specific genetic polymorphisms of ICAM-1 and PECAM-1 could be associated with glioma development and progression. Single-nucleotide polymorphism in codon 469 of ICAM-1 and codon 125 of PECAM-1 were examined in 158 patients with astrocytomas and 162 controls using polymerase chain reaction and restriction enzyme analysis. The distribution of PECAM-1 polymorphic genotypes in astrocytomas did not show any significant difference. However, a specific ICAM-1 genotype (G/G, corresponding to Lys469Glu) exhibited higher frequency in grade II astrocytomas compared to controls, grade III, and grade IV astrocytomas; suggesting that this polymorphism could be involved in the development of grade II astrocytomas.

Intercellular adhesion molecule-1 K469E polymorphism in Korean patients with spontaneous preterm delivery

OBJECTIVES

To investigate the association between intercellular adhesion molecule-1 (ICAM-1) gene K469E polymorphism and spontaneous preterm delivery in a Korean population.

METHODS

Genomic DNA was extracted from whole blood from 55 women experiencing preterm labor and 153 multiparous women (control group) with a history of at least 2 term deliveries. DNA samples were analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The spontaneous preterm delivery (SPD) group carried the 469E allele significantly more frequently than those in the control group (odds ratio [OR], 1.62; 95% CI, 1.04-2.53). The EE genotype was significantly associated with increased risk of SPD (OR, 2.84; 95% CI, 1.17-6.89; P = 0.02). Allelic frequencies in women with abnormal C-reactive protein levels (K = 0.48; E = 0.52) were significantly different from frequencies in the controls (K = 0.68; E = 0.32) (P = 0.006).

CONCLUSIONS

ICAM-1 gene K469E polymorphism may be a candidate region and useful predictor of susceptibility to SPD in the Korean population.

Primary sclerosing cholangitis--what is the difference between east and west?

Primary sclerosing cholangitis (PSC) is a chronic, progressive, cholestatic liver disease characterized by inflammation and fibrotic obliteration of the hepatic biliary tree. It is commonly associated with inflammatory bowel disease (IBD). A number of complications can occur which require special consideration, the most important of which is the development of cholangiocellular carcinoma (CCC). Unfortunately, no medical therapy is currently available for the underlying liver disease. Liver transplantation is an effective, life-extending option for patients with advanced PSC. Geographical variations between East and West include a second peak for age with a lower association with IBD in a Japanese population and female predominance in a lone study from Turkey. The clinical and biochemical Mayo criteria may not be universally applicable, as different patients show variations regarding the initial presentation and natural course of the disease. Directing research towards explaining these geographical differences and understanding the pathogenesis of PSC is required in order to develop better therapies for this devastating disease.

Primary sclerosing cholangitis - What is the difference between east and west?

Primary sclerosing cholangitis (PSC) is a chronic, progressive, cholestatic liver disease characterized by inflammation and fibrotic obliteration of the hepatic biliary tree. It is commonly associated with inflammatory bowel disease (IBD). A number of complications can occur which require special consideration, the most important of which is the development of cholangiocellular carcinoma (CCC). Unfortunately, no medical therapy is currently available for the underlying liver disease. Liver transplantation is an effective, life-extending option for patients with advanced PSC. Geographical variations between East and West include a second peak for age with a lower association with IBD in a Japanese population and female predominance in a lone study from Turkey. The clinical and biochemical Mayo criteria may not be universally applicable, as different patients show variations regarding the initial presentation and natural course of the disease. Directing research towards explaining these geographical differences and understanding the pathogenesis of PSC is required in order to develop better therapies for this devastating disease.

Polymorphisms of the ICAM-1 gene are associated with biliary atresia

Inflammation is an important feature of biliary atresia, and recent studies suggest that its occurs in a genetically susceptible host. The intercellular adhesion molecule-1 (ICAM-1) is of paramount importance for the initiation and propagation of various inflammatory conditions.

AIM

To determine whether the Glu241Arg polymorphism in the ICAM-1 gene, which impairs inflammatory responses, is associated with biliary atresia.

METHODS

Between February 2002 and November 2004, 19 patients (mean age 1 +/- 0.4 years) diagnosed as biliary atresia were included in the study. Thirty-eight children with chronic liver disease and a group of unrelated healthy controls (n = 123) included in this study. After informed consent, blood was collected and genomic DNA was obtained. Genotyping was performed by amplification-refractory mutation system polymerase chain reaction (ARMSPCR). Associations were assessed by using Fischer's exact test.

RESULTS

ICAM G242R A allele frequency was significantly higher in the BA group than in both the CLD and healthy control groups (OR = 4.4, 95 CI% 1.3-15.1, P = 0.03 and OR = 4.8 CI% 1.5-15.6, P = 0.01, respectively). Univariate analysis showed that polymorphism of ICAM G241R polymorphism was significantly related to biliary atresia. There was not significant correlation between PELD score and ICAM-1 genotypes both in BA and CLD groups.

CONCLUSION

These findings provide evidence for the possible role of ICAM-1 241R polymorphism in BA pathogenesis.

The challenges in primary sclerosing cholangitis--aetiopathogenesis, autoimmunity, management and malignancy

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease, characterized by progressive inflammation and fibrosis of the bile ducts, resulting in biliary cirrhosis and is associated with a high risk of cholangiocarcinoma. The majority of patients are young, male and have coexisting inflammatory bowel disease. PSC is found with a prevalence of 10/100,000 in Northern European populations. The pathophysiology of PSC is a complex multistep process including immunological mechanisms, immunogenetic susceptibility and disorders of the biliary epithelia. The diagnosis is primarily based on endoscopic cholangiography although magnetic resonance imaging is increasingly used; biochemistry and immunoserology as well as histology play only a minor role. Due to the high risk of developing cholangiocarcinoma and also other tumours of the GI tract, surveillance strategies are essential, however they have yet to be established and evaluated. Biochemical parameters, clinical risk factors, endoscopic procedures and imaging techniques contribute to the early identification of patients at risk. Since medical therapy of PSC with ursodeoxycholic acid does not improve survival, to date, liver transplantation is the only option with a cure potential; if transplantation is accurately timed, transplanted PSC patients have an excellent rate of survival. However if cholangiocarcinoma is detected, a curative treatment is not possible in the majority of cases. The present review critically summarizes the current knowledge on the aetiopathogenesis of PSC and gives an overview of the diagnostic approaches, surveillance strategies and therapeutic options. Primary sclerosing cholangitis is a disease of unknown aetiology and without any further curative treatment options apart from liver transplantation. Therefore it may be regarded as the greatest challenge in hepatology today.

Etiopathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown etiology but lymphocytic portal tract infiltration is suggestive of an immune-mediated basis for this disease. Associations with inflammatory bowel disease (IBD) especially ulcerative colitis (UC), and with particular autoimmune diseases, as well as the genetic associations further suggest PSC may be an immune-mediated disease. The immunogenetics of PSC have been the subject of active research and several HLA and non-HLA associated genes have been implicated in the development of the disease. Lymphocytes derived from the inflamed gut may enter the liver via the enterohepatic circulation to cause hepatic disease. PSC may be triggered in genetically susceptible individuals by infections or toxins entering the portal circulation through a permeable colon and hence evoking an abnormal immune response.

Sclerosing cholangitis epidemiology and etiology

Sclerosing cholangitis represents a spectrum of chronic biliary diseases that either has an unknown etiology (i.e., primary) or is caused by identifiable insults to the biliary tree (i.e., secondary). To date, the epidemiology of primary sclerosing cholangitis has been appraised; however, its etiology continues to be unclear. In contrast, the etiology of secondary sclerosing cholangitis is always known, but the epidemiology of this clinical entity is difficult to study.

Susceptibility to active decompensated cirrhosis is associated with polymorphisms of intercellular adhesion molecule-1 (ICAM-1) in chronic HBV carriers

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the pathogenesis of viral hepatitis B. Several inflammatory diseases are associated with distinct polymorphisms of the ICAM-1 gene. The aims of this study were to analyse the association of ICAM-1 polymorphisms G241R and K469E with susceptibility to active decompensated cirrhosis in chronic hepatitis B virus (HBV) carriers. The polymorphisms at codons G241R and K469E of ICAM-1 were analysed by sequence-specific primer polymerase chain reaction (PCR-SSP) in 572 unrelated chronic HBV carriers and 157 unrelated healthy HBV non-infected blood donors. There were significantly increased frequencies of R at codon 241 and E at codon 469 in patients with active decompensated cirrhosis (38.3% and 58.3%), compared with patients with chronic hepatitis B (CHB; 21.9% and 46.5%) and chronic asymptomatic HBV carriers (AsC; 12.6% and 40.3%). The frequencies of R241-E469 haplotype and genotypes carrying at least one R241-E469 haplotype were significantly higher in patients with active decompensated cirrhosis than those in patients with CHB (38.3% and 63.3%vs 21.9% and 36.7%), and significantly higher in patients with CHB than those in AsC (21.9% and 36.7%vs 12.6% and 23.3%). The ICAM-1 polymorphisms at codons G241R and E469K were associated with the disease susceptibility, and susceptibility to active decompensated cirrhosis is significantly increased in chronic HBV carriers carrying at least one R241-E469 haplotype.

Genetic epidemiology of primary sclerosing cholangitis

The aetiology of primary sclerosing cholangitis (PSC) is not known. A more than 80-fold increased risk of PSC among first-degree relatives emphasizes the importance of genetic factors. Genetic associations within the human leukocyte antigen (HLA) complex on chromosome 6p21 were detected in PSC 25 years ago. Subsequent studies have substantiated beyond doubt that one or more genetic variants located within this genetic region are important. The true identities of these variants, however, remain to be identified. Several candidate genes at other chromosomal loci have also been investigated. However, according to strict criteria for what may be denominated a susceptibility gene in complex diseases, no such gene exists for PSC today. This review summarises present knowledge on the genetic susceptibility to PSC, as well as genetic associations with disease progression and clinical subsets of particular interest (inflammatory bowel disease and cholangiocarcinoma).

Intercellular adhesion molecule 1 (ICAM1) Lys56Met and Gly241Arg gene variants, plasma-soluble ICAM1 concentrations, and risk of incident cardiovascular events in 23,014 initially healthy white women

BACKGROUND AND PURPOSE

The objective of this study was to examine the association of 2 nonsynonymous intercellular adhesion molecule 1 (ICAM1) gene variants (Lys56Met and Gly241Arg) with baseline plasma soluble ICAM1 concentrations and with risk of total and selected cardiovascular disease (CVD) events in a prospective cohort of 23 014 apparently healthy white American women followed for 10 years. ICAM1 variations have been associated with plasma soluble ICAM1 concentrations and inflammatory conditions, including atherosclerosis. However, to date, no large prospective, genetic-epidemiological data set is available that would allow evaluation of the degree of association of these gene variants with risk of CVD.

METHODS

ICAM1 genotypes and baseline plasma soluble ICAM1 concentrations were determined. The primary outcome measure was a composite CVD end point (incident ischemic stroke, myocardial infarction, or death due to ischemic CVD); other measures were incident ischemic stroke, myocardial infarction, and coronary revascularization. During follow-up, 751 total incident CVD events, 187 incident myocardial infarction cases, 203 incident ischemic stroke cases, and 433 coronary revascularization events occurred.

RESULTS

All observed genotype frequencies were in Hardy-Weinberg equilibrium across the whole sample population. We found baseline plasma soluble ICAM1 concentrations to be significantly reduced among carriers of Met56 allele (P<0.0001) and Arg241 allele (P<0.0001) as compared with the respective noncarriers of these variants. However, the polymorphisms tested and the respective haplotypes were neither associated with overall risk nor with risk with risk for selected CVD events regardless of whether analyses were adjusted for traditional CVD risk factors/confounders (all P values >0.10).

CONCLUSIONS

In this large prospective study, we found an association of the nonsynonymous gene variants tested with reduced baseline plasma soluble ICAM1 concentrations. However, no evidence was found for an association of the gene variants tested with the overall or selected CVD end points examined, suggesting that these variants may not add useful aids to current risk predictors for early assessment of cardiovascular events.

Rapid detection of intercellular adhesion molecule 1 (G241R and K469E) polymorphisms by a novel PCR-SSP assay

Intercellular adhesion molecule 1 (ICAM-1) is a cell surface glycoprotein member of the immunoglobulin superfamily and is actively involved in immune and inflammatory responses. We introduce a novel polymerase chain reaction-sequence-specific primers (PCR-SSP) method for rapid and simultaneous genotyping of ICAM-1 G241R and K469E polymorphisms. In a total of 184 DNA samples that have been previously analyzed for these polymorphisms using polymerase chain reaction-restriction fragment length polymorphism technique, re-genotyping of all samples with this new assay showed accurate and reproducible results. As PCR-SSP-based genotyping protocols are more convenient and cost-effective to do, it could therefore offer a valuable tool for assessment of ICAM-1 polymorphisms to which more confirmatory studies are needed.

Sclerosing cholangitis

PURPOSE OF REVIEW

Primary sclerosing cholangitis is a chronic cholestatic liver disease characterized by strictures of the biliary tree complicated by cirrhosis and cholangiocarcinoma. It is immune mediated, although the precise aetiology remains unknown.

RECENT FINDINGS

Research into etiopathogenesis and epidemiology, diagnosis of cholangiocarcinoma, associations with inflammatory bowel disease and autoimmune pancreatitis, and medical therapy are discussed.

SUMMARY

Multiple gene polymorphisms associated with primary sclerosing cholangitis have been investigated. Common inflammatory bowel disease-associated polymorphisms do not confer any susceptibility to primary sclerosing cholangitis; the role of intercellular adhesion molecule-1 gene polymorphisms and CCR5 mutations remain unclear. Elevated IgG4 has been demonstrated in a subgroup of primary sclerosing cholangitis patients, which may indicate an overlap with autoimmune pancreatitis and possible responsiveness to steroids. Biliary brush cytology may assist in diagnosis of cholangiocarcinoma, although further clinical indicators are required. Animal studies suggest the superiority of 24-norursodeoxycholic acid over ursodeoxycholic acid in reducing histological disease progress; translational studies in humans are now required.

Genetic background of the multifactorial liver and bile duct diseases

The majority of liver diseases, are complex. They are the results of interactions between several genes and environmental factors. Familial aggregation and higher concordance rate of monozygotic twins compared to those of dizygotic twins provide evidence for the importance of genetic factors in the pathogenesis. There are only limited data in connection with the genetic background of multifactorial liver diseases. In the future, the genetic background may permit prevention, early, accurate diagnosis, prediction of disease course, complications, prognosis, as well as treatment response.

Genomics and complex liver disease: Challenges and opportunities

The concept of genetic susceptibility in the contribution to human disease is not new. What is new is the emerging ability of the field of genomics to detect, assess, and interpret genetic variation in the study of susceptibility to development of disease. Deciphering the human genome sequence and the publication of the human haplotype map are key elements of this effort. However, we are only beginning to understand the contribution of genetic predisposition to complex liver disease through its interaction with environmental risk factors. In the coming decade, we anticipate the development of human studies to better dissect the genotype/phenotype relationship of complex liver diseases. This endeavor will require large, well-phenotyped patient populations of each disease of interest and proper study designs aimed at answering important questions of hepatic disease prognosis, pathogenesis, and treatment. Teamwork between patients, physicians, and genomics scientists can ensure that this opportunity leads to important biological discoveries and improved treatment of complex disease.

Analysis of MAdCAM-1 and ICAM-1 polymorphisms in 365 Scandinavian patients with primary sclerosing cholangitis

BACKGROUND/AIMS

Mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) has been implicated in the aberrant homing of intestinal lymphocytes to the liver in primary sclerosing cholangitis (PSC). Intercellular adhesion molecule-1 (ICAM-1) has also been implicated in the pathogenesis of PSC and the E/E genotype of the K469E polymorphism has been reported to be associated with PSC susceptibility. The aims of this study were to determine if MAdCAM-1 polymorphisms or the K469E polymorphism of ICAM-1 are associated with PSC in Scandinavia.

METHODS

Seven single nucleotide polymorphisms (SNPs) in MAdCAM-1 and the G421R and K469E ICAM-1 SNPs were genotyped in 365 PSC patients from Norway and Sweden. 327 Norwegian ulcerative colitis (UC) patients and 368 Norwegian bone marrow donors served as controls.

RESULTS

No significant association with PSC was found for any of the MAdCAM-1 or ICAM-1 SNPs. Allele frequencies for these polymorphisms were not significantly different between PSC patients with UC, UC patients and healthy controls.

CONCLUSIONS

Polymorphisms in MAdCAM-1 are not likely to significantly affect PSC susceptibility. In addition, the E/E genotype of the K469E in ICAM-1 does not influence PSC susceptibility in Scandinavia.

Adulthood-Onset Celiac Disease Is Associated with Intercellular Adhesion Molecule-1 (ICAM-1) Gene Polymorphism

Celiac disease (CD) is a multifactorial T-cell-mediated autoimmune disease characterized by gluten-triggered villous atrophy and malabsorption. Although human leukocyte antigen (HLA) class II genes are strong susceptibility factors, non-HLA genes likely contribute to most of CD predisposition. The intercellular adhesion molecule-1 (ICAM-1) gene is a good candidate for CD predisposition because its encoded protein acts as an adhesion and costimulatory receptor. Two single-base polymorphisms (G/A in exon 4 encoding G241R, and A/G in exon 6 encoding K469E) were analyzed in 180 French Caucasian CD case patients (110 patients diagnosed before the age of 15 and 70 patients after the age of 18), and 212 French Caucasian healthy controls. The R241 allele frequency was increased in CD case patients compared with controls (14.2% vs. 5.4% respectively, p = 0.000015, odds ratio [OR] for the R241 allele = 2.9, 95% confidence intervals [CI] = 1.7-4.8). After stratifying for age of disease onset, the R241 variant mainly conferred predisposition to CD occurring during adulthood (OR = 4.2, 95% CI = 2.3-7.5, Pc = 0.000004 for adulthood-onset CD vs. R = 2.1, 95%, CI = 1.2-3.9, Pc = 0.0047 for childhood-onset CD). Position 241 of ICAM-1 maps to the binding site for the integrin Mac-1 and might modify the strength of interaction between endothelium and immune cells. If confirmed in independent datasets, these results may be of importance in at-risk individuals to distinguish rapid from delayed progression to clinical CD.

Genetics of hepatobiliary diseases

With the recent publication of the first human map of genetic variation (ie, Human Haplotype Map), genomic-based discoveries will likely affect not only the research bench but also the bedside. These advances will improve the understanding of the genetics of hepatobiliary diseases, resulting in better prevention measures and diagnosis as well as more effective therapies. Currently, alcoholic liver disease, nonalcoholic fatty liver disease, and symptomatic gallbladder stones affect a sizable portion of the population. On the other hand, chronic cholestatic liver diseases, hepatocellular carcinoma, and polycystic liver disease, although rare, shorten life expectancy and diminish the quality of life of patients. In the genomic era, we have the opportunity to start dissecting the susceptibility genetic variants of liver diseases. We are now in a position to begin elucidating the complex genotype/phenotype relationships of liver diseases with the anticipation to understand disease pathogenesis better. These efforts will require the application of genomic-based approaches in large well-organized translational studies in the diseases of interest.

Immunopathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown etiology;however, lymphocytic portal tract infiltration is suggestive of an immune-mediated basis for PSC. Associations with inflammatory bowel disease--especially ulcerative colitis--and with other auto-immune diseases, together with genetic associations, further suggest that PSC may be an immune-mediated disease. The immunogenetics of PSC have been the subject of active research, and several human leukocyte antigen (HLA)- and non-HLA-associated genes have been implicated in the development of the disease. Lymphocytes derived from the inflamed gut may enter the liver via the enterohepatic circulation to cause hepatic disease.PSC may be triggered in genetically susceptible individuals by infections or toxins entering the portal circulation through a permeable colon and, therefore, evoking an abnormal immune response.

Autoimmune hepatitis and primary sclerosing cholangitis

Autoimmune liver disease in children presents predominantly as autoimmune hepatitis (AIH) and primary sclerosing cholangitis (PSC). These diagnoses must be considered in patients who have acute and chronic hepatitis, particularly when an extrahepatic autoimmune disorder is present. In AIH, the timely and sustained control of liver inflammation is critical to improve the short- and long-term outcomes. No effective treatment for PSC has been identified to date, but supportive care, careful attention to complications and associated nonhepatic diseases, and liver transplantation significantly improve the long-term outcome.

ICAM-1 polymorphisms and development of cutaneous malignant melanoma

Tumour growth in cutaneous malignant melanoma (CMM) is mediated by cell adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1). ICAM-1 expression is associated with increasing Breslow thickness of vertical growth-phase tumours and, in patients with stage 1 disease, may be associated with disease free and patient survival. In this study we have investigated whether two single nucleotide polymorphisms (SNPs) in the ICAM-1 gene encoding amino acid substitutions in codons 241 and 469 of the expressed ICAM-1 molecule are associated with susceptibility to and markers of prognosis (including tumour Breslow thickness) in CMM. A total of 164 CMM patients and 264 cancer-free controls were genotyped for these SNPs by the 5' nuclease assay for allelic discrimination (TaqMan). No genotypes showed any significant associations with CMM susceptibility, although there was a non-significant increase in frequency of the ICAM-1 469 AA genotype among CMM patients vs. controls (38.4% vs. 29.9%; P = 0.11). However, the ICAM-1 241 GG genotype was significantly decreased in frequency among patients with primary invasive tumours of greater Breslow thickness (72.5% vs. 91.2%; P = 0.013; OR = 0.25 (0.072-0.85)). These results provide no evidence for a role for the ICAM-1 codon 241 and 469 SNPs in determining susceptibility to CMM, but provide preliminary evidence that the role of ICAM-1 polymorphism in modulating tumour growth in CMM requires further investigation in a larger study group.

Sclerosing cholangitis

PURPOSE OF REVIEW

Primary sclerosing cholangitis is a chronic cholestatic liver disease characterized by strictures of the biliary tree. It is immune mediated, although the precise cause remains unknown. Recent reports have shown a higher prevalence and burden of disease than was previously suspected.

RECENT FINDINGS

The research into the etiopathogenesis, epidemiology, diagnosis of cholangiocarcinoma, medical and surgical therapy, and timing and outcome of liver transplantation is discussed.

SUMMARY

Genetic heterogeneity among patients with primary sclerosing cholangitis is supported, and further gene polymorphisms associated with protection against primary sclerosing cholangitis have been elucidated. Bile duct injury seems to be a multistep process. Magnetic resonance cholangiopancreatography is a cost-effective and accurate way of diagnosing primary sclerosing cholangitis in comparison with endoscopic retrograde cholangiopancreatography. Ursodeoxycholic acid may have a role as a colorectal and hepatobiliary cancer chemopreventive agent. Liver transplantation remains the only treatment in end-stage disease. The 5-year and 10-year patient and graft survival rates are comparable with those in patients without primary sclerosing cholangitis, but there is a higher rate of retransplantation for primary sclerosing cholangitis in most centers. Hepatobiliary malignancy is found in a minority of patients at transplantation, although 5-year survival rates for these patients are still promising.

Cholestasis and cholestatic syndromes

PURPOSE OF REVIEW

This review highlights recent advances in understanding the regulation of bile acid transport in cholestasis and the pathogenesis and treatment of a variety of cholestatic conditions.

RECENT FINDINGS

Highlights include new understanding of the role of Mrp4 in bile acid homeostasis in cholestasis, new insights into the pathogenesis of specific cholestatic syndromes including primary biliary cirrhosis, primary sclerosing cholangitis, biliary atresia, and progressive familial intrahepatic cholestasis, and clinical trials of therapies for primary biliary cirrhosis, primary sclerosing cholangitis and intrahepatic cholestasis.

SUMMARY

Our understanding of the molecular mechanisms of cholestasis is advancing. These advances will hopefully lead to more effective therapies for specific cholestatic conditions.