Autoimmune hepatitis (AIH) occurs when the immune system wrongly identifyies the liver as something ‘foreign’ (like a bacterium or a virus) and attacks it.
In AIH the immune system attacks the liver cells, known as hepatocytes, causing inflammation and damage. Initially the damage is mild but without a treatment in the long term it can progressively develop to different grades of scarring (fibrosis) up to the irreversible stage of cirrhosis.
The reason why someone develops AIH is unclear. We know it is due to an impaired control of the immune system. The current thought is that an individual needs to have a genetic predisposition which is then triggered by an infection or something environmental, such as a drug or a toxin, even long before the disease appears. Quite often other members of the patient’s family suffer from autoimmune conditions. At present it is not possible to predict who is going to develop AIH.
Many people have no symptoms at all when they present with the condition and are only diagnosed after a routine blood test shows abnormal liver function (raised serum level transaminases and immunoglobulins). Symptoms can develop over weeks or months and are non-specific (tiredness, general fatigue, anorexia, weight loss and joint and muscle pains). On rare occasions AIH develops quickly and symptoms and signs appear rapidly.
The presence of certain autoantibodies help establish the diagnosis of AIH – antinuclear antibodies (ANAs), smooth-muscle antibodies (SMAs), liver-kidney microsomal type 1 (LKM-1), or anti-liver cytosol 1 (anti-LC1) antibodies – and a liver biopsy is required to confirm the diagnosis. Rarely patients with AIH develop features of primary sclerosing cholangitis (PSC) or primary biliary cirrhosis (PBC) and they are commonly classified as having an “overlap syndrome”.
The aim of treatment is to reduce the inflammation in the liver using medication to reduce the activity of the immune system (immunosuppression) and so stop the damage worsening. Initial treatment is likely to be a steroid medication often started at a high dose and then reduced to a low dose with the addition of a second immunosuppressant (eg azathioprine). Alternative drugs are available should these not be tolerated or prove ineffective. In approximately 15% of patients treatment is ineffective at controlling the condition and the disease progresses, which may result in the need for liver transplantation. Outcomes for liver transplant for AIH are excellent although the condition recurs after transplant in 10-20% of people.