Immunogenetics in PSC

Novel Genetic Risk Variants and Clinical Predictors Associated With Primary Sclerosing Cholangitis in Patients With Ulcerative Colitis

INTRODUCTION

Patients with ulcerative colitis (UC) who are likely to have primary sclerosing cholangitis (PSC) should be identified because PSC can influence UC clinical behavior and outcomes.The aim of this study was to establish a model incorporating clinical and genetic risk predictors that identifies patients with UC at risk of developing PSC.

METHODS

We conducted a retrospective case-control study. Inflammatory bowel disease cohorts from multiple institutions were used as discovery and replicate datasets. Quality control criteria, including minor allele frequency, call rates, Hardy-Weinberg equilibrium, cryptic relatedness, and population stratification (through principal components), were used. Discriminative accuracy was evaluated with area under the receiver operating characteristic curve.

RESULTS

Fifty-seven of 581 patients (9.8%) with UC had PSC. Multivariate analysis showed that patients with UC-PSC had more extensive disease (odds ratio [OR], 5.42; P = 1.57E-04), younger diagnosis age (younger than 20 years; OR, 2.22; P = 0.02), and less smoking (OR, 0.42; P = 0.02) than those with UC. After linkage disequilibrium pruning and multivariate analyses, 3 SNPs (rs3131621 at 6p21.33; rs9275596 and rs11244 at 6p21.32) at the HLA region were found associated with a 2- to 3-fold increased risk of PSC. Our model demonstrated good discriminatory power (area under the receiver operating characteristic curve, 88%).

DISCUSSION

Three variants in HLA (6p21.3) region significantly distinguished patients with UC-PSC from patients with UC alone. Once further validated in an independent large cohort, our model could be used to identify patients with UC at risk of PSC, and it could also help guide disease management.

Antigen-Specific Immunotherapy for Treatment of Autoimmune Liver Diseases

The liver is a critical organ in controlling immune tolerance. In particular, it is now clear that targeting antigens for presentation by antigen presenting cells in the liver can induce immune tolerance to either autoantigens from the liver itself or tissues outside of the liver. Here we review immune mechanisms active within the liver that contribute both to the control of infectious diseases and tolerance to self-antigens. Despite its extraordinary capacity for tolerance induction, the liver remains a target organ for autoimmune diseases. In this review, we compare and contrast known autoimmune diseases of the liver. Currently patients tend to receive strong immunosuppressive treatments and, in many cases, these treatments are associated with deleterious side effects, including a significantly higher risk of infection and associated health complications. We propose that, in future, antigen-specific immunotherapies are adopted for treatment of liver autoimmune diseases in order to avoid such adverse effects. We describe various therapeutic approaches that either are in or close to the clinic, highlight their mechanism of action and assess their suitability for treatment of autoimmune liver diseases.

Isolated ileitis associated with primary sclerosing cholangitis in three patients with Crohn's disease

BACKGROUND

Primary sclerosing cholangitis (PSC) is associated with ulcerative colitis and extensive colonic involvement or ileocolitis in Crohn's disease (CD). To our knowledge, no specific report of isolated ileitis associated with PSC in CD patients has been published in CD patients.

AIM AND METHODS

We report three cases of patients with isolated Crohn's ileitis associated with PSC and in whom colonic inflammation was never documented.

RESULTS

Patients were followed up 10-23 years and each patient underwent 6-7 ileocolonoscopies: inflammation was located only in the terminal ileum, which was confirmed on surgical specimens in two patients. Small-duct PSC led to diagnosis of CD ileitis in one patient, while small and large-ducts PSC were evidenced after CD diagnosis in the other 2. PSC were regularly followed for 9-10 years.

CONCLUSIONS

Our three cases of PSC with isolated CD ileitis and long-term follow-up without any sign of colonic involvement argue against the concept that colonic mucosal inflammation is critical for the pathogenesis of PSC in inflammatory bowel disease.

Genetics in PSC: what do the "risk genes" teach us?

A role of genetics in primary sclerosing cholangitis (PSC) development is now firmly established. A total of 16 risk genes have been reported at highly robust ("genome-wide") significance levels, and ongoing efforts suggest that the list will ultimately be considerably longer. Importantly, this genetic risk pool so far accounts for less than 10 % of an estimated overall PSC susceptibility. The relative importance of genetic versus environmental factors (including gene-gene and gene-environment interactions) in remaining aspects of PSC pathogenesis is unknown, and other study designs than genome-wide association studies are needed to explore these aspects. For some of the loci, e.g. HLA and FUT2, distinct interacting environmental factors may exist, and working from the genetic associations may prove one valid path for determining the specific nature of environmental triggers. So far the biological implications for PSC risk genes are typically merely hypothesized based on previously published literature, and there is therefore a strong need for dedicated translational studies to determine their roles within the specific disease context of PSC. Apparently, most risk loci seem to involve in a subset of biological pathways for which genetic associations exist in a multitude of immune-mediated diseases, accounting for both inflammatory bowel disease as well as prototypical autoimmunity. In the present article, we will survey the current knowledge on PSC genetics with a particular emphasis on the pathophysiological insight potentially gained from genetic risk loci involving in this profound immunogenetic pleiotropy.

Hepatobiliary manifestations of inflammatory bowel disease

Patients with inflammatory bowel diseases (IBDs) may present with several hepatic abnormalities. Some of these liver diseases are benign and only require observation, whereas others may cause liver failure and require liver transplantation. The aim of this review was to present and summarize the latest evidence on the most common liver diseases seen in patients with IBD. These manifestations can be divided in to 3 groups: those that are seen in association with IBD, those that are due to metabolic and physiologic changes induced by the IBD and those that are secondary to the drugs used in the treatment of IBD. Primary sclerosing cholangitis is one of the most common hepatobiliary manifestations of IBD that is more prevalent in patients with ulcerative colitis. There is no approved medical treatment for primary sclerosing cholangitis and about 50% of patients will require liver transplantation within 10 to 15 years from the time of diagnosis. Among the drugs that are commonly used in the treatment of IBD, thiopurines and methotrexate impose the higher risk of hepatotoxicity. In most cases, dose adjustment and avoidance of hepatotoxins will normalize the liver tests and discontinuation of the drug is required in a minority of cases. Reactivation of hepatitis B virus during immunosuppressive therapy is a major concern and adequate screening and vaccination is warranted. The approach to a patient with IBD who presents with abnormal liver chemistries can be challenging not only because 2 or more conditions can co-exist but also because management must be individualized.

Autoimmune liver disorders and small-vessel vasculitis: four case reports and review of the literature

Autoimmune liver diseases (AILD) are a group of immunologically induced hepatic disorders that can lead to liver cirrhosis and end-stage liver disease. Extra-hepatic involvement and association with rheumatic diseases (such as Sjögren's syndrome, systemic sclerosis and rheumatoid arthritis) are well known, whereas the coexistence of AILD with small-vessel vasculitis in the same patients have been only occasionally reported. In the present paper we report four such cases and an extensive review of the literature. Clinical features of autoimmune-liver diseases associated with small-vessel vasculitis are discussed, as well as possible common pathogenic pathways including HLA genomics, costimulatory molecules and autoantibodies. In conclusion, knowledge about this association can help physicians in recognising and treating an aggressive disease which could otherwise result in severe and multiple organ damage, compromising the overall prognosis and the indication to liver transplantation.

Genetic susceptibility to autoimmune liver disease

Autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC) are considered as putative autoimmune diseases of the liver. Whereas strong evidence that bacterial infection may trigger PBC exists, the etiologies for PSC and AIH remain unknown. Although there have been significant discoveries of genetic polymorphisms that may underlie the susceptibility to these liver diseases, their associations with environmental triggers and the subsequent implications have been difficult to elucidate. While single nucleotide polymorphisms within the negative costimulatory molecule cytotoxic T lymphocyte antigen 4 (CTLA-4) have been suggested as genetic susceptibility factors for all three disorders, we discuss the implications of CTLA-4 susceptibility alleles mainly in the context of PBC, where Novosphingobium aromaticivorans, an ubiquitous alphaproteobacterium, has recently been specifically associated with the pathogenesis of this devastating liver disease. Ultimately, the discovery of infectious triggers of PBC may expand the concept of genetic susceptibility in immune-mediated liver diseases from the concept of aberrant immune responses against self-antigens to insufficient and/or inappropriate immunological defense mechanisms allowing microbes to cross natural barriers, establish infection and damage respective target organs.

HLA and autoimmune digestive disease: a clinically oriented review for gastroenterologists

OBJECTIVES

The human leukocyte antigen (HLA) system includes genes involved in graft-vs-host rejection and in immune response. The discovery that HLAs are associated with several diseases led to appealing developments both in basic biomedical research and in clinical medicine, and offered the opportunity to improve the understanding of pathogenesis and classification of diseases, as well as to provide diagnostic and prognostic indicators. The aim of this article is to review the association between HLA alleles and autoimmune digestive disease and its current relationship with modern HLA nomenclature and clinical practice.

METHODS

Articles dealing with the association between HLAs and autoimmune digestive disease (including celiac disease, inflammatory bowel disease, autoimmune hepatitis, sclerosing cholangitis and primary biliary cirrhosis) were searched for using Pubmed and SCOPUS databases from earliest records to January 2008.

RESULTS

The review has provided two sections. In the first, we explain the basic principles of HLA structure, function, and nomenclature, as an introduction to the second section, which describes current associations between HLA alleles and digestive diseases. The clinical implications of each HLA association are critically discussed. Actually, a clinical role for HLA typing is suggested for only a few conditions, e.g., celiac disease.

CONCLUSIONS

The knowledge of current HLA nomenclature and of its association with some digestive diseases such as celiac disease can be useful in clinical practice for diagnostic and prognostic purposes. This can avoid improper HLA typing as well as stressing the need for further studies on other possible clinical applications.

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.

HLA DRB1*13 as a risk factor for type 1 autoimmune hepatitis in North American patients

Our goal was to determine if HLA DRB1*13 is associated with autoimmune hepatitis in North American patients. Two hundred and ten adults with definite type 1 autoimmune hepatitis were typed by DNA-based techniques, and the frequency of HLA DRB1*13 in patients without DRB1*03 and DRB1*04 was compared to that in 396 patients with eight other chronic liver diseases and 102 normal individuals. HLA DRB1*13 occurred more commonly in the autoimmune patients who lacked DRB1*03 and DRB1*04 than normal subjects who were similarly restricted (56% vs. 27%, P = 0.007). The frequency of HLA DRB1*13 was higher in autoimmune patients without DRB1*03 and DRB1*04 than in patients with other chronic liver diseases who were similarly restricted (59% vs. 32%, P = 0.01). Only patients with primary sclerosing cholangitis had a comparable occurrence of HLA DRB1*13. In conclusion, HLA DRB1*13 may be a genetic risk factor for some white North American patients with type 1 autoimmune hepatitis.

Cholangiocarcinoma in primary sclerosing cholangitis is associated with NKG2D polymorphisms

Primary sclerosing cholangitis (PSC) is often complicated by the development of cholangiocarcinoma (CCA). Genetic variation of natural killer cell receptor G2D (NKG2D) has been associated with cancer susceptibility. An important ligand for NKG2D, major histocompatibility complex class I chain-related molecule A (MICA), serves as a marker of cellular stress. The 5.1 allele of the gene encoding MICA has been associated with PSC. In this study, we aimed to investigate the influence of genetic variations in the NKG2D-MICA receptor-ligand pair on the risk of CCA in patients with PSC. Seven single nucleotide polymorphisms (SNPs) covering the NKG2D gene were genotyped in 365 Scandinavian PSC patients and 368 healthy controls with TaqMan technology. Genotype data on the MICA 5.1 variant were available from previous studies. Forty-nine of the PSC patients (13.6%) had developed CCA at the time of study. Two of the NKG2D SNPs were associated with an increased risk of CCA: rs11053781 [odds ratio (OR) = 2.08, 95% confidence interval (CI) = 1.31-3.29, corrected P (P(c)) = 0.011] and rs2617167 (OR = 2.32, 95% CI = 1.47-3.66, P(c) = 0.0020). Carriership of the MICA 5.1 allele was associated with resistance against CCA (OR = 0.43, 95% CI = 0.20-0.95, not corrected P = 0.032).

CONCLUSION

Our results show that genetic variants of the NKG2D receptor are associated with development of CCA in PSC patients. This suggests that interaction between NKG2D and MICA is involved in protection against CCA in PSC. Patients who are homozygous for the nonrisk alleles are unlikely to develop CCA; this finding could be helpful in identifying PSC patients with a low CCA risk.

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).

Primary sclerosing cholangitis is associated with extended HLA-DR3 and HLA-DR6 haplotypes

Primary sclerosing cholangitis (PSC) is associated with the human leukocyte antigen (HLA)-DRB1*0301-DQA1*0501-DQB1*0201 (DR3) and HLA-DRB1*1301-DQA1*0103-DQB1*0603 (DR6) haplotypes. Recently, the extended HLA class I region has been found to harbour genes that modulate or confer susceptibility independently of the HLA class II genes in several immune-mediated diseases. The aim of the present study was to evaluate the influence of genes in the extended HLA class I region on susceptibility to PSC. Seven microsatellite markers (MIB, D6S265, D6S2222, D6S464, D6S2223, D6S2225 and D6S2239) were analysed together with HLA class II alleles in 219 Norwegian patients with PSC and 282 random controls. To control for associations because of linkage disequilibrium (LD), 142 HLA-DR3 homozygous and 187 DR6-positive controls were included. The unstratified analysis showed significant associations with the alleles MIB*349 [odds ratio (OR) = 3.0, corrected P value (P(c)) = 3 x 10(-12)], D6S265*122 (OR = 1.7, P(c)= 0.004), D6S464*209 (OR = 1.8, P(c)= 0.03) and D6S2225*147 (OR = 2.7, P(c)= 4 x 10(-6)), which were mainly secondary to the DR3 association. When stratifying for DR6, an association with the D6S265*122 allele was still observed (OR = 3.7, P(c)= 0.0004). In the presence of the D6S265*122 allele, the risk to develop PSC conferred by DR6 was increased four times compared with the risk conferred by DR6 alone. In addition, a novel negative association of PSC with DR11 was observed (OR = 0.21, P(c)= 2 x 10(-4)). In conclusion, our study shows that a gene in LD with D6S265 contributes to susceptibility to develop PSC in individuals carrying DR6. Moreover, we found that the PSC-associated DR3 haplotype extends more telomeric than that previously reported. We also report a possible protective effect of DR11 on development of PSC.

Particular genetic variants of ligands for natural killer cell receptors may contribute to the HLA associated risk of primary sclerosing cholangitis

BACKGROUND/AIMS

Combinations of killer immunoglobulin-like receptors (KIRs) and HLA class I ligands that reduce natural killer (NK) cell inhibition have been shown to increase risk for autoimmune diseases. We aimed to clarify to what extent such combinations influence susceptibility to primary sclerosing cholangitis (PSC).

METHODS

Three hundred and sixty-five Scandinavian PSC patients and 368 healthy controls were genotyped for the presence or absence of genes encoding all KIRs using a PCR-SSP approach. KIR binding site variation of HLA-A, -B and -C was also determined.

RESULTS

The KIR gene frequencies were similar among patients and controls. However, the frequency of HLA-Bw4 and -C2, which are ligands for the inhibitory KIRs 3DL1 and 2DL1, respectively, was significantly reduced in PSC patients as compared with controls (38.2% vs. 54.7%, P(corrected)[P(c)]=0.0006 and 42.7% vs. 56.9%, P(c)=0.009, respectively). Two HLA risk haplotypes in PSC (carrying DRB1*0301 or DRB1*1501, respectively) were devoid of both of these alleles, and carried the 5.1 variant of the major histocompatibility complex class I chain-related A (MICA) gene previously reported to influence PSC susceptibility.

CONCLUSIONS

Particular variants of ligands for NK cell receptors encoded at three neighbouring genes in the HLA complex may contribute to PSC associations observed in this genetic region.

Different HLA class II associations in ulcerative colitis patients with and without primary sclerosing cholangitis

Approximately 80% of patients with primary sclerosing cholangitis (PSC) of Northern European origin have inflammatory bowel disease (IBD), the majority ulcerative colitis (UC). An inherent problem in interpreting positive findings in genetic association studies of PSC is thus to distinguish between factors associated with hepatobiliary versus intestinal pathology. We aimed to clarify to what extent human leukocyte antigen (HLA) class II associations in UC patients with and without PSC differ. High-resolution DRB1 and DQB1 typing was performed in 365 Scandinavian PSC patients, an independent cohort of 330 Norwegian UC patients and 368 healthy controls. HLA associations found in PSC were mostly distinct from those seen in UC, and no significant differences were noted between PSC patients with concurrent UC and PSC patients without IBD. This suggests different HLA associated genetic susceptibility to PSC and UC, and supports notions that UC in PSC may represent a distinct UC phenotype.

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.

Genetic polymorphisms associated with inflammatory bowel disease do not confer risk for primary sclerosing cholangitis

OBJECTIVES

Approximately 80% of patients with primary sclerosing cholangitis (PSC) of Northern European origin have concurrent inflammatory bowel disease (IBD). The majority have ulcerative colitis, but there is also an association with Crohn's colitis. The pathogenetic link between PSC and IBD is unknown. We aimed to assess whether genetic risk factors in PSC can be identified on the basis of known IBD susceptibility genes and the shared PSC-IBD phenotype.

METHODS

IBD-associated polymorphisms in the CARD15, TLR-4, CARD4, SLC22A4, SLC22A5, DLG5, and MDR1 genes were genotyped in a large cohort of 365 Scandinavian PSC patients and 368 healthy controls using TaqMan technology.

RESULTS

No significant association between any of the investigated genetic IBD risk variants and overall susceptibility to PSC was observed. Apart from a tendency toward an increased carrier frequency of the mutant CARD15 alleles in PSC patients with concurrent Crohn's disease as compared with healthy controls (15.6%vs 9.0%, P = 0.22), no association with any of the polymorphisms investigated was evident even when considering only PSC patients with concurrent IBD.

CONCLUSION

It seems unlikely that IBD-associated polymorphisms in the CARD15, TLR-4, CARD4, SLC22A4, SLC22A5, DLG5, and MDR1 genes confer susceptibility to PSC. The current knowledge of genetic risk factors in IBD may not contribute to our understanding of molecular mechanisms involved in the pathogenesis of PSC or the IBD phenotype in PSC.

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.

Polymorphisms in the steroid and xenobiotic receptor gene influence survival in primary sclerosing cholangitis

BACKGROUND & AIMS

The steroid and xenobiotic receptor (SXR) is a ligand-dependent transcription factor that mediates protection against bile acid-induced liver injury in cholestatic animal models. Ursodeoxycholic acid and rifampicin are known ligands. We investigated whether functional polymorphisms of the SXR gene influence disease susceptibility or disease progression in patients with primary sclerosing cholangitis (PSC).

METHODS

Polymorphisms at 8 loci across the SXR gene were genotyped in 327 Scandinavian PSC patients and 275 healthy controls. Kaplan-Meier survival analyses and Cox regressions were performed to estimate effects from genotypes on patient survival, defined as time from diagnostic cholangiography to death or liver transplantation.

RESULTS

Susceptibility to PSC was not associated with any of the SXR polymorphisms studied. Median survival was significantly reduced in patients homozygous for the minor allele as compared with patients carrying at least 1 major allele of the neighboring polymorphisms rs6785049 (10.8 vs 14.0 years, respectively, P = .01), rs1054190 (3.6 vs 13.6 years, respectively, P = .004), and rs3814058 (3.5 vs 13.3 years, respectively, P = .01). The increased risk of death or liver transplantation was confirmed in univariate Cox regressions (relative risk [RR](rs6785049) = 1.7, 95% CI: 1.1-2.6; RR(rs1054190) = 3.1, 95% CI: 1.4-7.1; and RR(rs3814058) = 2.2, 95% CI: 1.2-4.2 for the 3 polymorphisms, respectively). In multiple Cox regressions including age at PSC onset, rs1054190 remained an independent risk factor.

CONCLUSIONS

Functional SXR gene variants appear to modify disease course in PSC. Further investigations of polymorphisms in the SXR gene may provide insight into the prognostic importance of SXR-regulated pathways in this disease, perhaps even in a therapeutic perspective.

The 32-base pair deletion of the chemokine receptor 5 gene (CCR5-Delta32) is not associated with primary sclerosing cholangitis in 363 Scandinavian patients

CCR5 is a chemokine receptor expressed on T-cells and macrophages. A 32-base pair deletion in the chemokine receptor 5 gene (CCR5-Delta32) leads to a non-functional receptor. Conflicting evidence exists whether this deletion is associated with primary sclerosing cholangitis (PSC). We genotyped the CCR5-Delta32 variant in 363 PSC patients and 366 controls. No significant increase in the Delta32 allele frequency was detected in the PSC patients compared to controls (12.7% vs 10.7% OR = 1.22, 95% CI [0.88, 1.68], P = 0.23). Survival analysis did not reveal any significant effects from CCR5-Delta32 genotypes on disease progression. Thus, in this study (power > 90%, given OR = 2, alpha = 0.05), we were unable to replicate previous findings and our results do not support an involvement of CCR5-Delta32 in either PSC susceptibility or progression.

No major effect of the CD28/CTLA4/ICOS gene region on susceptibility to primary sclerosing cholangitis

OBJECTIVE

Primary sclerosing cholangitis (PSC) is currently thought to be an immune-mediated disease, where both host genes and environmental factors interact. Some of the immunoregulatory genes responsible for individual susceptibility to PSC have been identified. The co-stimulatory receptor gene cluster on chromosome 2q33 encodes both the positive T-cell regulators CD28 and ICOS, and the negative regulator CTLA4. The CTLA4 gene has been implicated in several immune-mediated diseases, but it is not known whether PSC is associated with any of these genes.

MATERIAL AND METHODS

Polymerase chain reaction (PCR)-based genotyping was performed on 144 PSC patients and 285 controls. Two single nucleotide polymorphisms (SNPs) in the CTLA4 gene were investigated as well as six microsatellites covering approximately 262 kb of the flanking regions, including the ICOS and CD28 genes.

RESULTS

Overall, there were no statistically significant differences between PSC patients and controls in genotype and allele frequencies for the CTLA4 +49AG and CT60 SNPs or for the CD28-A, CD28-B, SARA43, SARA1, SARA31, and SARA47 microsatellite markers. Nor were any associations with clinical subgroups observed.

CONCLUSIONS

There are no major effects of the CD28/CTLA4/ICOS gene region on susceptibility to PSC, but minor contributions (OR <1.8) cannot be excluded.

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.

The association of HLA-DR13 with lower graft survival rates in hepatitis B and primary sclerosing cholangitis Caucasian patients receiving a liver transplant

We investigated an association of human leukocyte antigen (HLA)-DR13 to graft survival in liver transplantation among Caucasian recipients. 28,708 deceased liver transplants performed between January 1990 and December 2002 in the United States as reported to the United Network for Organ Sharing registry were utilized to compare survival rates. We utilized Caucasian adult patients (>20 years) by Kaplan-Meier curves, log-rank tests, and Cox proportional hazard analyses. HLA-DR13-negative hepatitis B virus (HBV) and primary sclerosing cholangitis (PSC) recipients yielded significantly lower graft survival rates than those of DR13-negative patients (P = 0.002, P = 0.015, respectively). This negative association was still significant after adjusting potential confounding factors. The Cox test demonstrated that HLA-DR13-positive groups have a significantly higher hazard ratio in PSC (1.40; P = 0.029; 95% confidence interval, 1.04-1.90) and HBV patients (1.78; P = 0.032; 95% confidence interval, 1.05-3.02). In conclusion, our data suggest that HLA-DR13 is a strong, positive predictor of increased risk for graft loss in HBV and PSC liver transplant recipients. Further study is needed to test the hypothesis that DR13-related immune responses may play a role in mediating graft loss in HBV and PSC liver transplantations.

Primary sclerosing cholangitis in two brothers: report of a family with special emphasis on molecular HLA and MICA genotyping

Immune mechanisms play a role in the pathogenesis of primary sclerosing cholangitis (PSC), as suggested by its association with certain HLA haplotypes. Genetic predisposition is supported by its occurrence in families, but data are scarce. Our aim is to report on two brothers with PSC, and to investigate HLA and MICA alleles in this family. The clinical, biochemical, radiological, and pathological findings in two brothers with PSC as well as in their sister and parents were reviewed. Molecular genotyping of HLA class II and MICA alleles was performed in all five family members. In two brothers, p-ANCA positive PSC was found. The youngest also had ulcerative colitis, and had evolved into cirrhosis at the age of 17 years. Their mother had positive p-ANCA and mild cholestatic changes. Their father and sister were unaffected. Both brothers were homozygous for the MICA*00801 allele, and were positive for the susceptibility HLA haplotypes DR3-DQ2 and DR6-DQ6. Their unaffected father and sister both carried the protective DR4 allele. The presence of PSC in two brothers, and the distribution of HLA haplotypes and MICA alleles, adds supportive evidence for an immunogenetic origin of PSC.

Association of matrix metalloproteinase-1 and -3 promoter polymorphisms with clinical subsets of Norwegian primary sclerosing cholangitis patients

BACKGROUND/AIMS

Primary sclerosing cholangitis (PSC) is considered an immune mediated liver disease of multifactorial and multigenetic aetiology. Concomitant ulcerative colitis (UC) is seen in many PSC patients, but the pathogenetic link between these disorders is unknown. Due to association with inflammation, fibrosis, and cancer development, the matrix metalloproteinases MMP-1 and MMP-3 are candidate genes for predisposition to both PSC, UC and cholangiocarcinoma.

METHODS

We investigated the association of MMP-1 and MMP-3 promoter polymorphisms in 165 Norwegian PSC patients compared to 118 UC patients and 346 healthy controls.

RESULTS

There were no differences in MMP-1 and MMP-3 frequencies between PSC patients and UC patients or healthy controls. PSC patients with UC showed an increased frequency of the MMP-3 allele 5A compared to PSC patients without UC (60% vs. 45%; P(c)=0.01). All patients (100%) with cholangiocarcinoma carried MMP-1 allele 1G, compared to only 72% of PSC patients without cholangiocarcinoma.

CONCLUSIONS

We found no general associations of the MMP-1 and MMP-3 genes to PSC or UC among Norwegian patients, but specific alleles were associated to subsets of PSC patients with UC and cholangiocarcinoma. The results support the theory of genetic heterogeneity among PSC patients.

Factors associated with disease activity of pouchitis after surgery for ulcerative colitis

BACKGROUND

Pouchitis occurs in 20% to 59% of patients operated on for ulcerative colitis. Several risk factors have been identified for the development of pouchitis. This study was undertaken to assess the incidence of pouchitis at least 5 years after ileal pouch-anal anastomosis for ulcerative colitis, and to evaluate possible predictive factors for inflammation activity.

METHODS

A total of 107 subjects were enrolled (54 M, 53 F, mean age 45 years, range 23-69) with a J-pouch created between 1985 and 1994. Preoperative medical history was determined, an endoscopy performed, and biopsies taken from the pouch and neoterminal ileum above the pouch. Sera from all patients were tested for perinuclear antineutrophil cytoplasmic antibodies (pANCAs).

RESULTS

After a mean 7.5-years' follow-up time, the cumulative incidence of pouchitis was 58%. Risk for development of active inflammation (PDAI > or = 7) was significantly higher in patients with preoperative extraintestinal manifestations (OR 2.7, 95% CI 1.1-6.4, P=0.03). Patients who had had ankylosing spondylitis (AS) (OR 11.7, P=0.006) or iritis (OR 9.8, P=0.013) were especially at risk. Positive titres of pANCAs were associated with inflammation in the neoterminal ileum; 80% of patients with high pANCA levels (>100) had pouchitis. Current smokers tended to have a more benign disease course.

CONCLUSIONS

A correlation existed between the prevalence and titre of pANCAs and extent and disease activity of pouchitis. Chronic pouchitis may continuously stimulate the immunological process, keeping pANCAs at detectable levels. A strong correlation between AS, iritis and pouchitis suggests a common link in their pathogenesis.

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

BACKGROUND/AIMS

Intercellular adhesion molecule-1 (ICAM-1, CD54) gene polymorphisms have been implicated in the susceptibility to a range of inflammatory diseases, including inflammatory bowel disease (IBD). Primary sclerosing cholangitis (PSC) is an immune-mediated chronic cholestatic liver disease associated with IBD. ICAM-1 is expressed on proliferating bile ducts and interlobular bile ducts in late stage PSC and serum levels of soluble intercellular adhesion molecules are increased in PSC. The aim of this study was to analyse ICAM-1 gene polymorphisms in PSC patients.

METHODS

In this study, 104 patients with PSC and 213 healthy controls were recruited from Oxfordshire Caucasians. PCR with sequence-specific primers (PCR-SSP) was used to detect both ICAM-1 biallelic polymorphisms G241R and K469E. The results were controlled for the HLA haplotypes associated with PSC.

RESULTS

The E/E frequency of K469E in PSC was 12% (12/104), significantly lower than that in controls (24%, 51/213;P = 0.009; Pc = 0.02; OR, 0.41). The occurrence of the haplotype G241-E469/G241-E469 in PSC was 4% (4/104), significantly lower than the control group (13%, 28/213; P = 0.01; Pc = 0.04; OR, 0.26). There was no difference between PSC and control groups in the frequencies of the genotype R241G or in allele frequencies of K469E.

CONCLUSIONS

The E469E homozygote status for ICAM-1 is associated with protection against PSC.

Aberrant local renin-angiotensin II responses in the pathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is an idiopathic inflammatory disorder of the biliary tract characterized by diffuse biliary tract stricture formation, progressive chronic cholestasis and the development of secondary biliary cirrhosis. Biliary tract ischemia can produce morphological changes identical to PSC. We propose the existence of a localized renin-angiotensin system within the liver and extend the hypothesis that aberrant production of angiotensin II within the portal tract is the critical event contributing to the pathogenesis of PSC. A chronic reparative and proliferative state caused by chronic ischemia may promote carcinogenesis. Proof of this hypothesis will have implications for future therapeutic approaches given that current treatments for PSC aimed at reducing inflammation or the effects of cholestasis have proven ineffective.

Sclerosing pancreatitis presenting as a periampullary tumour

BACKGROUND

Sclerosing lesions of the pancreatic duct are rare and may be secondary to primary sclerosing cholangitis (PSC) or the result of a primary sclerosing process (the recently described lymphoplasmacystic sclerosing pancreatitis, LSP). Occasionally this process may present as a mass lesion.

CASE OUTLINE

A 21 -year-old man presented with abdominal pain and jaundice, giving a high index of suspicion for a periampullary malignancy. There were minimal symptoms suggestive of PSC. The resected head of the pancreas demonstrated changes of chronic pancreatitis with a fibro-inflammatory process of the pancreatic duct suggesting an underlying ductal sclerosing process.

DISCUSSION

Clinical presentation and imaging characteristics of PSC involving the pancreas are often misleading and may suggest a neoplasm as the underlying disorder. Conclusive diagnosis is usually not determined until after surgical intervention. Although racial differences in pancreatic duct involvement have been suggested, the underlying histopathology is the same as in PSC involving the biliary ducts.

Hepatic manifestations of gastrointestinal diseases. Inflammatory bowel disease, celiac disease, and Whipple's disease

The gastrointestinal tract and the liver are closely related anatomically, physiologically, and pathologically. Some disease associations are well documented, such as PSC in association with IBD, whereas others are less well defined. A heightened clinical suspicion is required in these patients who do not present with the classical disease associations. The underlying causes of their diseases are the subject of much debate and research, and their diagnosis and management remain challenging.

Genetic effects on susceptibility, clinical expression, and treatment outcome of type 1 autoimmune hepatitis

Currently, three genetic factors have been short-listed as possible modulators of susceptibility and severity in type 1 AIH. They are female sex, HLA DRB alleles encoding lysine at position DR beta 71, and the CTLA4*G allele. The fourth association (i.e., TNFRSF6) remains to be confirmed. There are many other candidates to investigate. Current hypotheses suggest that the autoimmune genotype will include multiple (some linked, others discrete) loci which make a permissive background. Not all "at risk" individuals will develop clinical disease, and selection will depend on the interaction of this "permissive gene pool" (i.e., the host) with the environment. The resulting autoimmune phenotype will depend on gene dose and gene interaction. The human genome project has presented medical science with the challenge to identify the genes that determine common human diseases, including autoimmunity [1]. Although type 1 AIH is considerably less common than diabetes or RA, it may serve as a useful model for other autoimmune diseases. Diagnosis depends on histologic findings, and liver biopsy examinations are part of the usual assessment strategy in type 1 AIH. The availability of these tissue specimens provides a clear basis for monitoring disease progression and may permit investigators to study the impact of genetic polymorphism on disease activity. The emergence of high throughput technologies will significantly enhance our ability to study the interactions between constellations of polymorphic genes and both disease expression and behavior. An abundance of polymorphism is found in the genome. In many diseases, functional studies and genome scanning have helped revise and reduce the list of candidates. Affected families are rare in type 1 AIH, and patients are at risk if corticosteroid treatment is withheld. Under these circumstances, genetic studies may be the most practical, low risk means to investigate the pathogenesis of type 1 AIH and many other autoimmune diseases.

Recurrence of primary sclerosing cholangitis after liver transplantation

Orthotopic liver transplantation (OLT) has become the only effective therapeutic option for patients with end-stage liver disease caused by primary sclerosing cholangitis (PSC). Excellent long-term outcome has been reported, with 5-year patient survival rates of approximately 80%. In the last few years, increasing evidence has emerged that PSC recurs after OLT. The diagnosis of PSC is based on well-defined cholangiographic features combined with biochemical and histological findings. However, none of these features is specific for PSC, particularly after OLT, because biliary strictures in the liver allograft can occur from a variety of causes other than recurrence. Therefore, PSC recurrence remains a controversial issue, especially because of a lack of a gold standard for diagnosis and well-established diagnostic criteria. Some reports provided cholangiographic evidence that post-OLT biliary strictures occurred more frequently in patients with PSC than in those who underwent OLT for other liver diseases (including patients with a Roux-en-Y biliary reconstruction). Because no other possible cause of biliary strictures could be invoked to explain the greater prevalence of these strictures, recurrent disease has been implicated. There also is histological evidence suggesting that PSC recurs after OLT. Histological findings suggestive of PSC were found more often in PSC allografts compared with a control group. Furthermore, histological features typical for PSC (fibro-obliterative lesions) were seen exclusively in liver biopsy specimens from patients with PSC. Recurrence of PSC was defined in a recent study from the Mayo Clinic by means of strict cholangiographic and histological criteria in a large cohort of patients with PSC in whom other causes of biliary strictures were excluded. PSC recurrence was found in 20% of patients. No risk factor for PSC recurrence could be found, and recurrent disease did not influence patient or graft survival after a mean follow-up of 4.5 years. In conclusion, several studies provided convincing evidence that PSC recurs after OLT, with an incidence of 5% to 20% and an interval to diagnosis of at least 1 year after OLT. To date, patient and graft survival do not appear to be negatively affected by disease recurrence in the intermediate term of follow-up.