Autoimmune hepatitis is an autoimmune disease with liver parenchymal damage as the main manifestation. It is prevalent in women and has a variety of clinical manifestations, including persistent elevation of liver enzymes, elevated globular eggs, and multiple autoantibodies. The pathological changes are chronic active hepatitis characterized by lymphocytic debris necrosis in the confluent area. The differential diagnosis often requires a combination of clinical symptoms, autoantibodies and hepatopathology. Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune cholangitis (AIC) are collectively referred to as autoimmune liver disease, and when autoimmune hepatitis and primary biliary cirrhosis or primary sclerosing cholangitis are combined, it is called the overlap syndrome. Autoimmune hepatitis is also often associated with other autoimmune diseases such as systemic lupus erythematosus, dry syndrome, ulcerative colitis, thyroiditis, and scleroderma. I Epidemiology AIH occurs worldwide, but is most common in Caucasian (Caucasian) populations, especially in British, Irish, and Nordic peoples and their immigrants to Northern Europe, with an annual incidence of 0.1 to 1.2/100,000 and a prevalence of 20/100,000. In Asia, the prevalence of AIH is low among the yellow population, with 0.015~0.08 per 100,000 per year reported in Japan and low in Thailand, and AIH is reported to be rare in mainland China, Taiwan, Hong Kong, and Macau. nishioka investigated the prevalence of AIH in 13 countries and regions, which is lower than that of PBC. there is no report on the prevalence of AIH in mainland China, which may The prevalence of AIH in mainland China has not been reported, probably due to the incomplete understanding and diagnosis of the disease. A review of the quantity and quality of AIH reports and descriptions in the domestic literature and textbooks shows that there is a significant gap compared with advanced western countries, which should attract the attention and concern of hepatologists, gastroenterologists, infectious agents, pediatricians and general internists. II. Clinical manifestations Autoimmune hepatitis is more than 70% female. It can be seen in all age groups, with a peak incidence of 14 to 60 years old, and mostly has a chronic and prolonged course. Long-term fatigue is the most common complaint of patients, and symptoms similar to viral hepatitis such as fatigue, low-grade fever, anorexia, and anorexia of grease are common, sometimes accompanied by vague pain in the right upper abdomen, not accompanied by itchy skin, and some cases are seen in orthopedics and dermatology in the early stage because of joint pain and skin rash only. Physical examination is generally fair. Jaundice is present in 80% of cases, and liver palms, spider nevus, and hepatosplenomegaly are more common. In later stages of cirrhosis, giant spleen, ascites and superficial varices of the abdominal wall appear. Laboratory examination 1. Liver enzyme examination Serum transaminase ALT and AST levels are significantly increased, while serum γ-glutamyl transpeptidase (γ-GT) and alkaline phosphatase (AKP) are normal or only mildly increased. 2.Immunological examination High γ monoglobulinemia is seen in almost every patient, with the most obvious elevation of lgG, positive serum non-specific auto-antibodies, anti-nuclear antibody (ANA), anti-smooth muscle antibody (SMA), anti-hepatic and renal microsomal antibody (LKM-1), anti-neutrophil cytoplasmic antibody (ANCA). Positive liver-specific autoantibodies, anti-soluble liver antigen antibodies (SLA), desialic acid glycoprotein receptor antibodies, etc. AIH is classified into three types according to the autoantibody positivity, of which the most common with positive anti-nuclear antibody (ANA) and/or anti-smooth muscle antibody (SMA) is type I. Those with positive anti-liver-kidney microsomal (LKM-l) antibody in the serum but negative for both ANA and SMA are type II, which is more common in children; those with soluble liver antigen antibody ( SLA) in the blood, but negative for ANA, SMA and anti-LKM-1 antibodies is type III. Patients with HLA-B8 and HLA-DR3 (+) are more likely to be in the younger age group, have a more severe inflammatory response, have poorer prednisone efficacy, and have a higher incidence of liver transplantation. HLA-DR4(+) is more likely to be seen in older female patients with other autoimmune diseases, and has a better response to prednisone treatment. The basic pathological changes of autoimmune hepatitis are lymphocytic debris necrosis with marked lymphocytic infiltration, hepatocyte ballooning and apoptosis in addition to inflammatory cell infiltration in the confluent area and paracellular septum, and a wreath-like arrangement of surviving hepatocytes, bile duct hyperplasia and connective** deposits. As the injury progresses, it progresses from around the confluent area to the septal compartment. Liver biopsy is mandatory for diagnosis, with inflammation of the confluent zone (debris necrosis or interface necrosis) implying a high 5-year survival rate and a 17% rate of cirrhosis, with bridging necrosis or multilobular necrosis marking a 5-year mortality rate of 45% and an 82% chance of cirrhosis within 5 years. Reversible conversion of debilitating necrosis to confluent hepatitis is often seen after hormonal and immunosuppressive therapy, but can also occur spontaneously. If the debris necrosis develops into bridging necrosis and forms a fibrous septum, the lesion is irreversible, and the debris necrosis can persist after cirrhosis has formed to form active cirrhosis. Diagnosis The diagnostic criteria established by the International AIH Group meeting in 1992, 1. Negative hepatitis virus infection index, no excessive alcohol consumption and history of liver damage drugs. 2, ANA, SMA positive or LKM-1 antibody titer 1:80 positive. 3, γ a globule egg, IgG elevated more than 1.5 times the normal value, IgG normal can make the diagnosis of AIH except. 4, ALT is elevated. 5.Pathology can be seen as debris necrosis or can be accompanied by lobular hepatitis. 6, no biliary lesions, granulomas, iron and copper deposits and other manifestations. In 1999, the International AIH Group further revised the diagnostic point system for AIH. 1. AIH can be identified as those with scores greater than 15 before treatment and greater than 17 after treatment. 2. Those with scores of 10-15 before treatment and 12-17 after treatment may be AIH. V. Differential diagnosis AIH should be distinguished from other causes of chronic It should be distinguished from other causes of chronic liver disease such as hepatitis B, C virus and cytomegalovirus as well as drug-related hepatitis. It should be noted that cases with viral hepatitis indicators do not exclude AIH, because viral hepatitis may be the cause of AIH. Many systemic autoimmune diseases such as SLE, primary SS, scleroderma, etc. can cause liver damage, and liver lesions can be the first manifestation, and liver damage can sometimes be quite severe, and ANA and SMA can also be positive. For example, autoimmune hepatitis was once called “lupus-like hepatitis” and was thought to be a variant of SLE. However, SLE is often multisystemic, involving the skin, kidneys, nervous system, etc., and liver damage often parallels other systemic damage and is related to disease activity, whereas AIH is mainly characterized by parenchymal liver damage, with relatively mild extrahepatic damage. Indeed, autoimmune liver disease is often combined with other autoimmune diseases, such as AIH and SLE, SS, UC, thyroiditis, etc. However, with the continuous development of immunology, **cytology, and biochemistry, studies have shown that cellular immunity is the main immune mechanism in the pathogenesis of AIH, with T-lymphocyte infiltration and debris-like necrosis in the liver as the main pathological features, which is different from SLE with active B-lymphocytes In particular, the isolation of liver-specific autoantigens such as the antigenic determinant cluster of the desialic acid glycoprotein receptor (ASGP-R) has been decisive in identifying markers of AIH-specific immunology. There is growing evidence that autoimmune liver disease is a separate group of autoimmune diseases. In cases where both diagnostic criteria for SLE and clinicopathological manifestations of AIH are met, the two diseases should be considered to coexist. In addition, the clinical manifestations of PBC, AIC and PSC are also similar to those of AIH, so they need to be differentiated in the diagnosis. Hormones and immunosuppressants Hormones and immunosuppressants are the first choice for the treatment of AIH. Although there is still controversy on whether immunosuppressants should be applied at the same time, there is a convergence of views on the choice of immunosuppressants based on hormone therapy. is a new immunosuppressant extracted from soil fungi with similar effects to cyclophilin A. It is still in the research stage. Corticosteroids are significantly better than immunosuppressants in inducing rapid remission of the disease, but azathioprine is significantly better than corticosteroids in stabilizing remission, and the three-phase treatment regimen is shown below. 1. Induction of remission: 1 mg/kg prednisone until response, decreasing by 10 mg/w, 5 mg/w up to 15 mg/d. When transaminases reach within 2 times normal values, add azathioprine 1-1.5 mg/kg if the diagnosis is clear, but not if the diagnosis is not clear. Maintenance therapy: Prednisone 5-10mg/d plus azathioprine 50-100mg/d. After one year, if the inflammatory response is mild or normal, reduce the dose of prednisone to 2.5mg/d. If the inflammatory response is mild or normal, reduce the dose to 2.5mg/d. After 3 months, repeat the liver biopsy and resume the original dose if the inflammatory response exists or worsens. Long-term treatment: Maintenance therapy with doses for at least 3 years, relapse is an indication for long-term treatment. More than 50% of relapses occur after discontinuation of therapy, especially within 1 year of discontinuation. Regardless of the method of treatment for AIH, early diagnosis and early treatment are essential to improve the remission rate. Effective treatment with improvement in self-reported symptoms precedes improvement in laboratory parameters and finally **ological improvement. **ological changes lag behind clinical and laboratory changes by 3-6 months, so treatment must be extended for another 3-6 months. Liver biopsy prior to withdrawal is necessary to establish the diagnosis of remission. **Improvement of the science is the key to avoid progression to cirrhosis. 2. Oral tolerance therapy Inducing the body to lose its reactivity to autoantigens through oral administration of antigens is a novel approach to the treatment of autoimmune diseases. Because the efficacy of oral tolerance depends on the portal-liver circulation and the uptake of antigens by immune cells in the liver, AIH is an ideal disease for implementing this method of treatment. Further development of this therapy is currently pending the identification of autoantigens and the establishment of animal models. 3. Usflu 10-20mg/kg/day 4. Liver transplantation Early liver transplantation is advisable in cases with poor drug efficacy and those that have progressed to cirrhosis, especially in decompensated patients for whom prednisone therapy has failed is the only treatment, although there are still cases of relapse after liver transplantation, but it is not rare, suggesting the presence and ability of the recipient to be expressed by the donor liver, or the presence of specific antigens activated memory T cells. The specific immune mechanisms need to be further investigated. VII. Prognosis The activity of the disease is one of the decisive factors in the prognosis. The prognosis is poor when the serum AST is >5-10 times normal, γ-globulin is >2 times normal and continues to rise, when the disease is of acute course, and when it rapidly progresses to cirrhosis. The pathological stage is another marker that determines the severity and prognosis of the disease. The presence of cirrhotic changes such as bridging necrosis, formation of fibrous septa, or even regenerative nodules in liver histology suggests a poor prognosis. Overlap syndrome Among autoimmune liver diseases. Cases that meet the diagnostic criteria of autoimmune hepatitis and have clinicopathological manifestations of PBC or PSC are called overlap syndrome, accounting for about 13% of autoimmune liver diseases.