Infection with the hepatitis C virus (HCV) can trigger autoimmune hepatitis (AIH) in a minority of patients. This means that the liver cells are damaged not only by the virus but also by the body's own immune system.
AIH triggers the body to attack its liver cells as if the liver cells were harmful foreign substances. Patients with a combination of HCV and autoimmune hepatitis may suffer from more debilitating symptoms than patients with HCV alone. Autoimmune hepatitis is associated with other autoimmune illnesses, including thyroiditis (inflammation of the thyroid), diabetes, rheumatoid arthritis (inflammation of the joints), and ulcerative colitis (inflammation of the large intestine).
Below are some frequently asked questions about the complex relationship between HCV and autoimmune hepatitis.
Q. What are the Symptoms of Autoimmune Hepatitis?
A. In its most clandestine form, AIH may be detected during the evaluation of HCV in a person who is asymptomatic (without symptoms). An asymptomatic presentation occurs approximately 15% to 20% of the time. People whose condition is asymptomatic often have a milder course of disease. At the opposite extreme, AIH may be discovered during an attack of the disease, usually characterized by grossly elevated liver-related blood tests, jaundice, severe itching, right upper quadrant pain, and fatigue. This occurs in up to 25% of the cases. Other people fall somewhere in between, having vague symptoms such as a general sense of lethargy, muscle and joint aches, or mild abdominal discomfort.
Fatigue is the most common and often the sole symptom, occurring in approximately 85% of symptomatic people. The severity of fatigue does not always correlate with the degree of liver inflammation and damage.
Extrahepatic (involving organ and tissue other than the liver) features result from the immune system harming other organs of the body. These symptoms can include absence of a menstrual period, bloody diarrhea (due to ulcerative colitis), abdominal pain, arthritis, rashes, anemia, kidney disease, dry eyes, and dry mouth.
People with AIH typically have a chronic fluctuating course. AIH is characterized by exacerbations (worsening) and remissions of disease, which occur at varying intervals.
Q. What Causes These Symptoms?
A. When the immune system becomes activated, as in the case of an autoimmune disease, there is increased production of inflammatory cells (T-cells), antibodies, and other inflammatory chemicals. The overactivated immune system can lead to systemic symptoms of fatigue and low-grade fever. Some other symptoms, such as glomerulonephritis and arthritis, are due to deposits of antibodies that accumulate in the kidney or joints, leading to damage in those tissues.
Q. What Is the Process by Which HCV Triggers Autoimmune Conditions?
A. Although the mechanism is still poorly understood, it is theorized that proteins appear on the surface of infected liver cells. This leads to an autoimmune response, in which cells of the immune system (including T and B cells) recognize these new proteins as foreign bodies. These cells then attack the liver, causing inflammation of the liver cells and eventual destruction of liver tissue.
Q. How Is Autoimmune Hepatitis Diagnosed?
A. Autoimmune hepatitis requires laboratory tests to distinguish it from uncomplicated hepatitis C infections. When AIH is triggered, the immune system produces protective antibodies that actually attack the enemy organ. These antibodies are known as autoantibodies. Hypergammaglobulinemia, an excess of antibodies in the blood, is a common finding in autoimmune hepatitis. Blood tests for certain autoantibodies may also provide diagnostic clues. The diagnosis may, however, require a liver biopsy.
Q. How Is Treatment for Patients With Autoimmunity Determined?
A. Interferon is the only approved treatment for HCV, but its use in people with autoimmune hepatitis has been shown to exacerbate the disease. In general, steroids are used for people with autoimmune hepatitis due to non-viral causes. But in patients with hepatitis C, steroids can increase viral replication.
A liver biopsy is usually recommended to determine which disease process is causing the greatest damage to the liver: the HCV infection or the autoimmune hepatitis. In general, if the HCV infection were predominant and the autoimmune hepatitis mild, treatment of HCV with a regimen containing interferon would be considered. However, if the autoimmune hepatitis were severe, leading to such complications as kidney damage, rashes, or rapid liver failure, steroids or other immunosuppressant drugs would more likely be recommended.
The choice between these treatment options boils down to the immune system. Alfa interferon, which activates the immune system to reduce viral replication, could be problematic for those whose immune system was already over-activated due to severe autoimmune hepatitis. Steroids, which suppress the immune system, could be problematic for those with severe HCV-infection, leading to a compromise of the body's ability to fight the infection.