Whether through hypersensitivity reactions or immune stimulation, hepatitis viruses trigger several different autoimmune disorders including autoimmune hepatitis.
Autoimmune diseases are caused by a combination of genetic and environmental factors. That is, autoimmune diseases develop in people with certain immune system and organ specific genes when they’re exposed to certain environmental triggers. Infectious agents are one of the most suspect triggers, and specific viruses and bacteria are linked to a number of different autoimmune diseases. Viral hepatitis is a well known autoimmune disease trigger.
Hepatitis Viruses and Autoimmune Disease
There is a long association between hepatitis and autoimmune diseases. Hepatitis can be caused by many different viruses. And many autoimmune diseases are associated with hepatitis. The most common viral cause of hepatitis include the hepatitis viruses: hepatitis A, hepatitis B, hepatitis C, hepatitis D, and hepatitis E. Other causes of viral hepatitis include cytomegalovirus, rubella virus, Epstein-Barr virus (EBV), parvovirus 19, and adenovirus.
Hepatitis A
Hepatitis A is primarily spread through fecally contaminated food and water. Hepatitis A causes an acute infection that resolves within several months and causes lifelong immunity. However, hepatitis A is a known trigger for autoimmune hepatitis including all of the autoimmune hepatitis subtypes.
Hepatitis B
Hepatitis B or serum hepatitis is primarily caused by blood to blood contact including intravenous drug use, blood transfusions, contaminated medical equipment, and childbirth. Hepatitis B primarily causes an acute infection that resolves within several months. However, some people whose immune systems never fully fight the virus, especially children infected around the time of childbirth, become hepatitis B carriers. Although they may show no evidence of disease, they may have chronic infection. People with chronic hepatitis B infection are at high risk for the autoimmune disorder polyarteritis nodosa and at increased risk for cryoglobulinemia although this disorder is more likely to occur in hepatitis C infection. An autoimmune form of glomerulonephritis associated with immune complexes and hypersensitivity reactions may also occur in hepatitis B.
Polyarteritis nodosa (PAN)
Polyarteritis nodosa emedicine.com/NEURO/topic314.htm is a vascular disorder affecting small and medium-sized arteries and arterioles causing a variety of different symptoms. Symptoms in polyarteritis nodosa include abdominal pain, renal insufficiency, heart disease, hypertension, and arthritis. As many as 69 percent of patients with PAN show evidence of the hepatitis B surface antigen, the primary infectious agent in hepatitis B.
Hepatitis C
Before the mid-80’s most cases of hepatitis C were caused by blood transfusions and organ transplants. Today, the most common cause of hepatitis C is intravenous drug use. Hepatitis C causes a chronic or lifelong infection in most people who are infected. The hepatitis C virus is the major cause of the autoimmune disorder mixed cryoglobulinemia. Mixed cryoglobulinemia is an immune complex-mediated form of systemic vasculitis that primarily affects small blood vessels. Cryoglobulinemia causes a variety of symptoms including urticarial vasculitis characterized by itching and hives and kidney inflammation.
Patients with cyroglobulinemia represent a distinct population in that lymphoid cells are significantly enriched with hepatitis C virions as well as increased population of B lymphocyte cells The liver, which is the major target of the hepatitis C virus, accumulates inflammatory infiltrates that enhance the migration of white blood cells. These immune system cells continually produce cytokines that help the hepatitis C virus survive. The circulating immune complexes that flourish in this environment cluster within blood vessels inducing cryoglulinemia development.
This continual immune stimulation is also responsible for the higher prevalence of overt B-cell non-Hodgkin’s lymphoma in HCV infected patients. Other autoimmune conditions seen in hepatitis C include autoimmune vasculitis, porphyria cutanea tarda, Sjogren’s syndrome, sicca syndrome, and lichen planus.
Cryoglobulinemia
Cryoglobulins are immunoglobulin proteins (the source of antibodies) that precipitate at cold temperatures. People with elevated levels of cryoglobulins develop conditions of cryoglobulinemia (Type I, Type II or mixed) that cause vasculitis characterized by bruising, weakness, and arthralgia (joint pain).
Resources
Elaine Moore, Hepatitis, Causes, Treatment, and Resources, Jefferson, NC: McFarland and Company, 2006.
D Sansonno, A Carbone, V DeRe, and F Dammacco, Hepatitis C virus infection, cryoglobulinemia, and beyond. Rheumatology, Feb 22, 2007.
