What are the Causes of Autoimmune Hepatitis?
Autoimmune Hepatitis is defined as a necroinflammatory disease of the liver, usually chronic and progressive, of not well known cause. This disease is characterized by the presence of immunological alterations, among which are hypergammaglobulinemia, the presence of autoantibodies and, generally, a good response to immunosuppressive treatment. The clinical presentation is very variable, in the form of acute disease, fulminant or, on the contrary, asymptomatic or not very active.
What are the Causes of Autoimmune Hepatitis?
Currently the etiology of the disease is unknown; it is suspected that in genetically predisposed individuals, some environmental agent activates the immune system against liver antigens, causing chronic progressive inflammation. No clear evidence has been found on which or what are the possible triggers of the immune response against own liver antigens.
These are the most implicated agents: viruses such as those of hepatitis A, B or C, Herpes Simplex Virus type I or measles virus, and different drugs or environmental toxins, which can trigger liver toxicity by immunological mechanisms.
An important data for the diagnosis of the disease is the presence of autoantibodies, although its pathogenic implication is not clear.
Autoimmune hepatitis has been classified into two subtypes taking into account these autoantibodies:
-Type 1 is associated with the presence of antinuclear antibodies (ANA), anti-smooth muscle antibodies (ASMA) or Antibodies against soluble liver antigen/liver-pancreas (SLA/LP).
-Type 2 is associated with antibodies against hepatorenal microsomes type 1 (LKM-1) or against hepatic cytosolic protein (LC1).
For the diagnosis, biochemical and immunological criteria should be taken into account. In addition, a liver biopsy for histological evaluation is considered very convenient and often required. Likewise, the response to immunosuppressive treatment represents an important diagnostic criterion.
The symptoms are non-specific in Autoimmune Hepatitis, so the onset can be insidious, with asthenia (general weakness), jaundice (yellowish coloration of the skin and mucous) and arthralgias (pain located in the joints), but it is very frequent for the patient to be asymptomatic (absence of symptoms) and the diagnostic suspicion is based on the casual detection of alterations in biochemical parameters. However, presentation is also frequent in the form of acute hepatitis, occasionally severe or fulminating.
It predominates in the female sex and in most cases occurs between 50 and 70 years of age. Its association with other autoimmune diseases is frequent, in the patient or in his first degree relatives.
They are also non-specific. Transaminase (liver enzymes) values can range from normal values to concentrations greater than 50 times the upper limit of normal, with variable bilirubin and little or no elevation of alkaline phosphatase. Another feature is the increase in gamma globulin and IgG.
Treatment with corticosteroids induces clinical and histological remission in 80% of patients in the first 3 years of treatment and reduces or prevents liver fibrosis in 79% of cases.
The decision to treat patients with Autoinmmune Hepatitis is complicated due to the variety of clinical presentations of the disease, the lack of knowledge of the natural history of moderate asymptomatic disease, the recommendations about the treatment objectives, the existence of cases of patients with intolerance or refractoriness to conventional treatment and the variety of immunosuppressive treatments alternative to conventional treatment. Therefore, treatment decisions can be guided but there are no established treatment guidelines since each treatment strategy must be individualized depending on the condition of each patient.
Failure in treatment is defined as clinical, analytical and histological worsening despite treatment. The treatment consists of administering Prednisone in monotherapy at a dose of 60 mg/d or at a dose of 30 mg/d in combination with Azathioprine at a dose of 150 mg/d for 4-6 weeks and subsequently reducing the dose progressively each month of clinical-analytical improvement up to a maintenance dose.
The cause of autoimmune hepatitis is not known, however, there is a certain genetic predisposition to develop this disease. Sometimes it is possible to identify a trigger factor of infectious type that initiates the hepatic inflammatory process; it occurs by hepatitis A virus. Certain medications such as nitrofurantoin and minocycline can trigger an autoimmune hepatitis.
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