Possible Causes of Primary Sclerosing Cholangitis

+ web-based presentation

Kurdistan Board GEH/GIT Surgery weekly J Club:Supervised by:

Professor Dr.Mohamed AlshekhaniMBChB-CABM,FRCP,EBGH.

Introduction:• It is idiopathic, heterogeneous, cholestatic liver disease characterized

by persistent, progressive, biliary inflammation &fibrosis. • There is no effective medical therapy.• ESLD necessitating liver transplantation may ultimately develop.• The cause & pathogenesis are unclear, but genetic / environment

contribute to development, progression&outcomes.• It is strongly associated with IBD (70 -80% have both)&it is a risk

factor for colon, BD,GB cancers.• PSC is a poorly understood disease for which medical therapy is

lacking.

ERCPNormal bile ducts Scleros Cholangitis

Liver histology in PSC

• “Onion skin fibrosis” • Atrophy and eventual

bile duct loss. • Ludwig Stage 1 = portal

hepatitis with little or no periportal inflammation and fibrosis

• Ludwig Stage 4 = frank biliary cirrhosis

Causes of Secondary Sclerosing cholangitis

• Biliary Calculi• Biliary stricture• Biliary Atresia• Bile duct malformations• Biliary infections -Cytomegalovirus -Cryptosporidium -Ascariasis -Asc cholangitis

• Chemotherapy eg FUDR• Formalin treatment for Hydatid cysts

Etiopathogenesis of PSC?

?

Small Duct PSC• Three recent studies • Rarely progresses to

large duct PSC (< 25% over 10 yrs)

• No cases of cholangioca• Urso - no evidence of

benefit• Effect on UC/dysplasia

unknown• Abandon the

term“pericholangitis”

Normal Normal ERCPERCP

Abnormal Liver Abnormal Liver biopsybiopsy

PSC, and Inflammatory Bowel Disease

• PSC -uncommon ? -7-9/100,000 pop 1993 -21/100,00 pop 2006

PSC -70-80% have associated IBD in Northern Europe

PSC -occurs in 5-10% of Total UC

-underestimate?

PSC- 20-30% normal LFTs

ERCP

MRCP

Frequency of IBD in Pts with PSC different parts of the world

First author country No of pt

IBD[%]

UC[%]

Crohn’s[%]

Schrumpf Norway 77 96 75 14Broome Sweden 305 81 72Farrant UK 126 73 71Wiesner US 174 71Olikosany Italy 117 54 36 10Escorell Spain 43 46 44 2Kocher India 18 50Takikawa Japan 192 21 20 1

Cancer in PSC-conclusions

• Risk of hepatobiliary cancer is constant at 1.5% per year

• Overall prevalence of 30 %• Cancer is now commonest mode of death in PSC• Increased risk of colonic cancer • Pancreatic cancer may also be increased• ?shared colonic /hepatobiliary risk of malignancy• Mechanism is unknown cp chronic inflammation

PSC is premalignant PSC is premalignant conditioncondition

“PSC-IBD”

• Does the IBD associated with PSC differ from UC?

Clinical Features of UC assoc with PSC -“PSC-UC” –

Different clinical phenotype?• Male predominance [2:1] cp UC alone [1:1.1]• Total in distribution – but symptomatically

mild• Rectal sparing in 23% -cp 5% of UC alone• Backwash Ileitis in 64%-cp 18% of UC alone -backwash ileitis assoc with colon ca /dysplasia• Increased rate of pouchitis post colectomy

Clinical Features of UC assoc with PSC -“PSC-UC” –

Different clinical phenotype?• Male predominance [2:1] cp UC alone [1:1.1]• Total in distribution – but symptomatically mild• Rectal sparing in 23% -cp 5% of UC alone• Backwash Ileitis in 64%-cp 18% of UC alone -backwash ileitis assoc with colon ca /dysplasia

• Extra colonic manifestations are different -rheumatoid arthritis cp seroneg arthropathy, & rare skin or eye involvement in PSC/IBD• Increased rate of pouchitis post colectomy

PSC-IBD

• Genetic differences between PSC-IBD and pan ulcerative colitis– Lower carriage of B*44 and DRB1*0103

(associated with peripheral arthritis and severe disease)

– Lower carriage of TNF-1031C (associated with erythema nodosum)

PSC-IBD: Conclusions

• PSC-IBD is characterized by– Extensive disease– Mild symptoms– High colorectal carcinoma rate– Low incidence of IBD-associated EIMS– High incidence of rheumatoid arthritis

• Lower rates of extraintestinal manifestations in PSC-IBD are reflected in lower carriage rates of HLA alleles associated with these EIMs

Susceptibility to PSC

• Male gender• Inflammatory bowel disease• Non cigarette smoking• Immunogenetics -MHC genes -Non-MHC immunoregulatory genes• Cystic fibrosis genes

Relationship between smoking habit & appendicectomy in 170 pts with PSC*

PSC UC Controls pvalue

smoking

never 66% 52% 39% <0.001ever 34% 48% 61% <0.001

former 27% 36% 36% <0.05

current 7% 25% 25% <0.001

appendicectomy

no 86% 88% 87%

yes 14% 12% 13%*Mitchell et al;GUT 2002*

Smoking habits in PSC with and without IBD*

PSC withIBD

PSC without IBD

Controls

never 65% 68% 37%

ever 35% 32% 63%

former 27% 27% 37%

current 8% 5% 26%

*Mitchell et al :Gut 2002

?PSC Appears protective!

Protective effect of smoking in PSC?

• Powerful effect• Mechanism in PSC (as for IBD) is unknown• Theories:- alteration in mucosal blood flow -effect on immune system - effect on mucus

Pathogenesis of PSCHypotheses/considerations

Strong association with IBD partic UC but the paradox:• PSC can occur many years before development

of UC• PSC can occur many years after colectomy• Clinical activities of colitis and PSC not related unlike other EIM’s ie Skin,eyes, seronegative arthropathies

Pathogenesis of PSC

What are the possible pathogenic mechanisms?

Non-Immune portal bacteremia portal endotoxemia absorbed colonic toxins toxic bile acids copper accumulation/toxicity viral infections ischaemic damage Immune Mediated

Key HLA Susceptibilty Haplotypes assoc with PSC*

Haplotype Significance in PSC

B8-TNF*2-DR3*0101-DRB1*0301-DQA1*0501-DQB1*0201 DR3

Strong association;“auto-immune haplotype”

DRB3*0101-DRB1*1301-DQA1*0103-DQB1*0603 DR6

Strong association

DRB5*0101-DRB1*1501-DQA1*0102-DQB1*0602 DR15

Weak association

DRB4*0103-DRB1*0401-DQA1*03-DQB1*0302 DR4

Strong association with disease protection

*Cullen S &Chapman R: Autoimmune Reviews 2003

MHC Susceptibility Genes in PSC*

Complex disease –not attributable to single gene locus

3 key haplotypes associated with PSC• Responsible for 90% of all PSC pts• ?common susceptibility allele for all 3• Candidate is MICA*008 (mapping on HLA

Class I /Class II boundary between B8 &TNFA) : occurs in 2 of key candidate haplotypes

• Could all be linkage disequilibrium

*Cullen S & Chapman R:Autoimmune Reviews 2003

Is PSC an Autoimmune disease?Evidence for immune dysfunction

• AutoimmunityHLA DR3 DQ2 haplotype

Autoimmune disease associations

2:1 male to female

Poor response to immunosuppression

Evidence for immune dysfunction

Antibody Prevalence

Atypical p-ANCA 33-87%Antinuclear antibody 7-77%

Anti smooth muscle antibody 13-20%

Anti-endothelial cell antibody 35%

Anti-cardiolipin antibody 4-66%

Thyroperoxidase 7-16%

Thyroglobulin 4%

Rheumatoid factor 15%

Autoantibodies found in PSC

Evidence for immune dysfunction

Autoantibodies• Indicate an altered state of immune

responsiveness.• Low prevalence and low titres• No help in determining prognosis• Functional significance?

ANCAcontrol ANCA positive

Alcohol fixed normal neutrophils

Diagnostic Role of ANCA in PSC*

Number of pts tested

% ANCA positive

Prim Scl Chol 80 78%Prim Bil Cirr 70 0EH bile duct obstruction

21 0

Hepatitis C 38 0Autoimmune Hep 56 42%Ulcerative colitis 96 34%Crohn’s disease 48 4%

*Bansi D & Chapman R Gut 1996

Evidence for immune dysfunction -Autoantibodies

• Atypical p-ANCA – most common autoantibody found in

PSC– Sensitive not specific:overlap with AIH– Antigen(s) not yet clear but may be

neutrophil nuclear protein*– Limited diagnostic role

*Terjung &Worman 2005

Evidence for immune dysfunction- cellular immune abnormalities

Infiltration of portal

tract with lymphocytes

(monoclonal antibodystain for CD3)

Features of PSC cp Classical Autoimmune disease

Characteristic Classical autoimmune disease

Primary Sclerosing Cholangitis

Age Children and adults Children and adults

Sex Female predominance Male Predominance

Assoc AI Disease Yes Yes

HLA Association(Class I & II )

Yes Yes

Response to Immunosuppression

Usually good Good in childrenPoor in most adults

Role of biliary epithelial cells in the immune process?

Target of immune attack

AND

Participant in immune response

HLA expression on bile duct epithelium

Biliary epithelial cells

Aberrant expression of HLA Class II antigens

Allows binding of autoantigens or exogenous antigens

Present peptides to Class II restricted T-lymphocytes

Immune response

Bacteria,Infective Agents and PSC

• Do bacteria / other infective agents gain access to portal circulation via inflamed and leaky bowel wall?

Bacteria/Infective agents – evidence

• Portal bacteraemia– Found in 25% of colectomy patients in 1960’s

– Confounded by introduction of bacteria during ERCP

– Animal studies eg bacterial peptides in rectum of rats /rabbits with colitis appear in bile and initiate a small duct cholangitis

Bacteria - evidence

• Portal bacteraemia

– Presence of intact colon in male patients at time of liver transplant for PSC may be a risk factor for recurrence of PSC in the allograft.

(Vera et al,Lancet 2003)

Unifying hypothesis for pathogenesis of PSC 1

(JM Vierling)

Immunogenetically susceptible host

Bacterial antigens

Kupfer cell activation

Cytokine and chemokine secretion

Neutrophils, monocytes,lymphocytes and fibroblasts

Concentric fibrosis around bile ducts

Ischaemia and atrophy of BEC

Cholestasis,fibrosis and biliary cirrhosis

Summary of pathogenesis of PSC

• Good evidence of immune dysregulation

• Circumstantial evidence of bacterial involvement

• No evidence for viruses/protozoaans

• Memory T lymphocytes might also be the link between the gut and the liver

Conclusion• No convincing evidence of

any single factor in triggering or maintaining the pathogenetic process in PSC

• Unlikely that “the Holy Grail” will

ever be found

Small Duct PSC• Three recent studies • Rarely progresses to

large duct PSC (< 25% over 10 yrs)

• No cases of cholangioca• Urso - no evidence of

benefit• Effect on UC/dysplasia

unknown• Abandon the

term“pericholangitis”

Normal Normal ERCPERCP

Abnormal Liver Abnormal Liver biopsybiopsy

PSC phenotype“Small duct” PSC

Retroviruses in PSCResults/Conclusion*

• HIV-1 p24 gag seropositivity in 35% PBC and in 39% PSC /biliary atresia

• HIAP (human intra cisternal A-type particle) prev found in Sjogren’s salivary glands 75%PBC 39% PSC

• Conclusion: HIV-1 & HIAP Ab reactivity ? autoimmune response to viral protein ? immune response to uncharacterised viral

proteins crossreacting with HIV-1 And HIAP

*Mason et al Lancet 1998

“Small duct” PSC

• Not necessarily associated with IBD• Better long term prognosis• Just an early stage of large duct

disease?– Same age of onset– Similar follow - up period– Only 20% progress to large duct disease

Management:drugs• No effective treatment but we control the

complications.• UDCA decreases liver enzymes, but not survival & high dose

increased the risk of death, liver transplantation, minimal listing criteria for liver transplantation, cirrhosis, esophageal or gastric varices, & cholangiocarcinoma.

• May be given at a dose of 13 -15 mg/ kilogram) for 6 months & If no decrease in alkaline phosphatase suggest discontinuation.

Management: survielance• Even if patients with IBD have undergone liver transplantation, they

should undergo annual colonoscopy with surveillance biopsies, given the increased risk of CRC.

• Patients who do not have evidence of IBD should undergo colonoscopy every 5 years, given their risk of colonic lesions.

• An annual GB U/S for assessment of polyps or other mass lesions is also recommended & any masses of any size should undergo cholecystectomy.

• 65% 5-year recurrence-free survival rate among selected patients with PSC & perihilar cholangiocarcinoma who have undergone liver transplantation after neoadjuvant chemotherapy/radiation.

Management:transplantation• 40% will ultimately require liver transplantation, 6% of all liver

transplantations.• 1-year survival 85% & 5-year survival 72%.• 25% recurs after transplantation diagnosed by cholangiographic

evidence in the absence of chronic liver rejection or vascular offenses (such as ischemia).

• Colectomy before liver transplantation in IBD may decrease the frequency of recurrence after transplantation.

Management: new drugs trials• Obeticholic acid is a semisynthetic analogue of chenodeoxycholic acid ,

a potent ligand for the farsenoid X receptor that has an antifibrotic effect.

• 24-nor -ursodeoxycholic acid, a synthetic bile acid that produce a bile acid–dependent bicarbonate-rich choleresis, may have beneficial effects.

• Apical sodium-dependent bile acid transporter inhibitor.• Vancomycin alter the gut microbiota & reduce innate immune

responses.• Intestinal microbiome may be involved, a pilot study of fecal

microbiota transplantation is underway.