autoimmune hepatitis

Definition: Autoimmune hepatitis (AIH) is a rare disease, characterized by female predominance, hypergammaglobulinemia, autoantibodies, association with HLA DR3 and HLA DR4 and a good response to immunosuppression.

Autoimmune hepatitis (AIH) is usually a chronic portal-based hepatitis with prominent plasma cells. Although necroinflammatory activity throughout the lobule is described, centrilobular necrosis (CN) is only rarely the predominant pattern of injury.

Types

 autoimmune hepatitis type 1

• AIH type 1 is characterized by anti-nuclear (ANA) and/or anti-smooth muscular (SMA) autoantibodies.
•  
   autoimmune hepatitis type 2
• AIH type 2 is characterized by liver/kidney microsomal autoantibodies (LKM).
•  
   autoimmune hepatitis type 3
• AIH type 3 may be distinguished by autoantibodies to soluble liver proteins (SLA) or the liver pancreas antigen (LP).

The autoimmune hepatitis type 2 (AIH type 2) affects predominantly pediatric patients and is characterized by a more severe clinical course, a higher frequency of relapse under immunosuppressive treatment and a more frequent progression to cirrhosis.

The autoimmune hepatitis type 1 and autoimmune hepatitis type 3 show a higher age of onset and a better long-term response to immunosuppressive treatment.

Attempts have been made to divide AIH into subtypes, depending primarily on the pattern of autoantibodies. Although useful for research purposes, these distinctions are not ideal.

Some clinical differences are seen between the subtypes, particularly in response to treatment and outcome between type 1 and type 2 AIH, but it must be appreciated that these are not distinct disease entities.

Type 1 AIH is most common. It can present at any age, is characterized by ANA, SMA, and in some cases perinuclear antineutrophil cytoplasmic antibodies (pANCA); treatment failure is rare. ANA and SMA titers of more than 1:80 are generally accepted as positive, although positive autoantibodies of uncertain clinical significance are more frequently detected in the elderly.

Type 2, which occurs in a younger age group, is associated with positive anti-liver kidney microsomal antibodies and is a more aggressive disease. Treatment failure is more frequent and relapse after drug withdrawal is almost inevitable; most of these patients need lifelong immunosuppressive therapy.

The putative type 3 autoimmune hepatitis (AIH type 3) is characterized by autoantibodies against SLA/LP (with or without ANA or SMA) and has been associated with more frequent relapse.

Synopsis

 hypergammaglobulinemia
 multifocal hepatic necrosis with bridging in the acute stage
 aggressive hepatitis with mononuclear cell infiltration or macronodular cirrhosis in the late stages
 chronic portal-based hepatitis with prominent plasma cells
 lobular necroinflammatory activity
 centrilobular necrosis

Lesional patterns

 autoimmune active chronic hepatitis
 autoimmune panlobular hepatitis
 autoimmune bridging mecrosis
 autoimmune massive hepatic necrosis

Laboratory

 autoimmune hepatitis type 1 (lupoid hepatitis) (anti-smooth muscle antibody, antinuclear antibodies)
 autoimmune hepatitis type 2 (LKM1-associated autoimmune hepatitis or anti-LKM1 chronic active hepatitis)
 autoimmune hepatitis type 3 (soluble liver antigen, liver/pancreas antigen)

AIH is characterized by elevated serum transaminase levels reflecting hepatocyte damage with typically modest elevations in alkaline phosphatase levels.

Patients with acute presentation may have jaundice, but otherwise this is a manifestation of severe exacerbations or a feature of end-stage disease. Immunology testing reveals hypergammaglobulinemia and high-titre circulating autoantibodies indicating immune activation.

AIH has been subdivided into three main categories according to the autoantibodies detected:

 Type 1 AIH, characterized by the presence of anti-smooth muscle antibodies (SMA) and/or anti-nuclear antibodies (ANA). This is the most common form.
 Type 2 AIH, characterized by anti-liver kidney microsomal antibodies. This form is rare in adults.
 Type 3 AIH, characterized by antibodies to soluble liver or liver-pancreas antigens.

Antibodies against cyclic citrullinated peptides (anti-CCPs) have been validated as specific diagnostic and prognostic markers of rheumatoid arthritis. Anti-CCPs have been found in 9% of patients with AIH. These patients have been reported to have a higher frequency of histological cirrhosis at presentation and to be at greater risk of dying from liver failure.

Other autoantibodies that may be found include autoantibodies to asialoglycoprotein receptor and anti-neutrophil cytoplasmic antibodies (ANCA).

Approximately 20% of patients will not have any of these autoantibodies, and they often have high immunoglobulin (IgG) and sometimes develop autoantibodies at a later stage.

Associations

 autoimmune disease

• celiac disease
• primary sclerosing cholangitis
• inflammatory bowel diseases (IBDs) (9123955, 8447289)
• familial autoimmune enteropathy (7996356)
• cryoglobulinaemia
• primary biliary cirrhosis (16416210)
• autoimmune enteric leiomyositis (15948126)

 miscellaneous

• erythroblastopenia
• cancer (10755264)
• trisomy 21 (10777202)

Overlaps

 primary biliary cirrhosis (PBC)
 primary sclerosing cholangitis
 chronic hepatitis C-immune predominant
 chronic hepatitis C-immune predominant
 autoimmune cholangitis
 cryptogenic chronic hepatitis

Microscopy

Patients presenting with chronic AIH typically have a plasma cell-rich mononuclear infiltrate mainly involving portal and periportal regions.

Plasma cells are not invariably present and a paucity of plasma cells does not therefore exclude a diagnosis of AIH.

Interface hepatitis is also a key diagnostic feature of AIH and is typically associated with ballooning and rosetting of periportal hepatocytes.

These changes lead to the development of periportal fibrosis, initially as delicate strands of immature collagen enveloping small clusters of entrapped hepatocytes.

Subsequently, there is formation of broader fibrous septa associated with bridging and nodule formation. Progression to cirrhosis occurs in 40–80% of cases.

Inflammatory activity often subsides when cirrhosis has developed, making it difficult to distinguish end-stage AIH from other causes of cirrhosis.

Varying degrees of lobular necroinflammatory activity are also commonly seen in AIH. These range from mild spotty inflammation with acidophil body formation to more severe lesions associated with confluent or bridging necrosis.

Giant cell transformation of hepatocytes is also quite common—this usually occurs to a minor degree, but in some cases is sufficiently extensive to warrant the term “giant cell hepatitis”.

Lobular necroinflammatory changes tend to be more prominent in patients with an acute presentation.

In patients presenting with fulminant hepatic failure, there are typically large areas of panacinar necrosis. Many patients with an apparently acute presentation of AIH have histological features of an underlying chronic hepatitis, including evidence of bridging fibrosis or cirrhosis.

Liver biopsy plays an important role in establishing a diagnosis of AIH. This is based both on the presence of typical features supporting a diagnosis of AIH and on the absence of atypical features (e.g., biliary abnormalities or steatosis) that might point to an alternative diagnosis.

Liver biopsy should be performed to confirm the diagnosis unless there is a good reason or contraindication.

Liver biopsy also provides valuable information about disease severity, which has implications for instigating and monitoring responses to immunosuppressive therapy. The pattern and severity of inflammatory activity at the time of presentation are predictive for subsequent progression to fibrosis and cirrhosis.

Interface hepatitis generally responds well to immunosuppression, whereas bridging necrosis more frequently progresses to fibrosis or cirrhosis.

The presence of cirrhosis at the time of presentation has also been associated with an adverse prognosis.

However, such patients frequently have ongoing inflammatory activity and still benefit from immunosuppression. Suppression of inflammatory activity is associated with reduction in fibrosis including some cases in which there appears to be reversal of an established diagnosis of cirrhosis.;

Conversely, worsening of inflammatory activity during corticosteroid therapy is associated with progression of fibrosis.

Natural history - prognosis

The seminal trials of immunosuppression in AIH were published more than 25 years ago. They revealed that untreated AIH has a poor prognosis with 5- and 10-year survival rates of 50 and 10%, respectively, whereas treatment with prednisolone is associated with excellent short- and long-term survival.

Up to 30% of adult patients have histological features of cirrhosis at diagnosis and progression of fibrosis can occur in patients with inflammatory activity despite steroid therapy.

The presence of cirrhosis at baseline significantly increases the risk of subsequent death or liver transplantation.

The risk of hepatocellular carcinoma (HCC) in autoimmune liver disease is associated with the development of cirrhosis and is no greater than in other non-viral causes of cirrhosis.

The 10-year overall survival of patients with AIH ranges between 80 and 93%.

The increasing diagnosis of AIH on routine blood testing, particularly in the elderly, has uncovered a group of patients with asymptomatic AIH who appear to have a very indolent course.

These patients are often elderly, and it is not clear what their long-term outcome is or whether they always require immunosuppressive therapy.

References

 Autoimmune hepatitis: new paradigms in the pathogenesis, diagnosis, and management. Oo YH, Hubscher SG, Adams DH. Hepatol Int. 2010 May 19;4(2):475-93. PMID: 20827405 [Free]

 Histology of autoimmune hepatitis and its variants. Guindi M. Clin Liver Dis. 2010 Nov;14(4):577-90. PMID: 21055683

 Krawitt EL. Autoimmune hepatitis. N Engl J Med. 2006 Jan 5;354(1):54-66. PMID: 16394302

 Brunt EM, Di Bisceglie AM. Histological changes after the use of mycophenolate mofetil in autoimmune hepatitis. Hum Pathol. 2004 Apr;35(4):509-12. PMID: 15116334

 Misdraji J, Thiim M, Graeme-Cook FM. Autoimmune hepatitis with centrilobular necrosis. Am J Surg Pathol. 2004 Apr;28(4):471-8. PMID: 15087666

 Obermayer-Straub P, Strassburg CP, Manns MP. Autoimmune hepatitis. J Hepatol. 2000;32(1 Suppl):181-97. PMID: 10728804

 Alvarez F, Berg PA, Bianchi FB, Bianchi L, Burroughs AK, Cancado EL, Chapman RW, Cooksley WG, Czaja AJ, Desmet VJ, Donaldson PT, Eddleston AL, Fainboim L, Heathcote J, Homberg JC, Hoofnagle JH, Kakumu S, Krawitt EL, Mackay IR, MacSween RN, Maddrey WC, Manns MP, McFarlane IG, Meyer zum Buschenfelde KH, Zeniya M, et al. International Autoimmune Hepatitis Group Report: review of criteria for diagnosis of autoimmune hepatitis. J Hepatol. 1999 Nov;31(5):929-38. PMID: 10580593

 Burgart LJ, Batts KP, Ludwig J, Nikias GA, Czaja AJ. Recent-onset autoimmune hepatitis. Biopsy findings and clinical correlations. Am J Surg Pathol. 1995 Jun;19(6):699-708. PMID: 7755156

 Homberg JC, Abuaf N, Bernard O, Islam S, Alvarez F, Khalil SH, Poupon R, Darnis F, Levy VG, Grippon P, et al. Chronic active hepatitis associated with antiliver/kidney microsome antibody type 1: a second type of "autoimmune" hepatitis. Hepatology. 1987 Nov-Dec;7(6):1333-9. PMID: 3679093