Psoriasis (psoriasis, Ps), commonly known as lepra alphos, is a common, chronic, non-infectious, painful, disfiguring and mutilating immunoinflammatory disease. At present, there are at least 100 million psoriasis patients worldwide. China has about 6.5 million psoriasis patients, wherein about 20% are moderately to  severely ill. There is currently no cure available. The incidence of psoriasis is high, and 10-30% of patients have psoriatic arthritis. This disease is also associated with type 2 diabetes, non-alcoholic fatty liver disease, cardiovascular disease and metabolic syndrome, etc. 

In addition, dilemmas such as social prejudices, treatment costs, time costs, and disfigurement, disability, loss of the ability to work in patients of psoriasis are also prone to anxiety and depression. In October 2018, the International Research Center for Medical Management of Peking University released the Research Report on the Disease Burden and Quality of Life of Psoriasis Patients in China in Beijing. As reported, over the past year, 89% patients said they have mental stress; 78% patients suffered discrimination. 34% patients had suicidal thoughts due to psoriasis, and 5% had committed suicide last year. 

Atopic dermatitis (AD) is a chronic, recurrent and inflammatory dermatosis. Patients often have severe itchiness, which seriously affects the quality of life. AD is one of the most common skin diseases, affecting up to 20% children and 1-3% adults. More than half of the patients who went to the hospital were moderately and severely ill. The main symptoms of these patients were extensive rash and unbearable severe itching. Patients have low quality life. They frequently suffer from mental illnesses such as sleeping disorder, anxiety and depression, seriously affecting their learning, work and social activities. For patients with moderate to severe AD, existing medical treatments are very limited, safe, effective and durable systemic treatment methods are urgently needed for clinical test. 

Systemic lupus erythematosus (SLE) is a chronic multi-organ autoimmune disease that can cause extensive tissue and organ damage. It is characterized by periodic onset and remission, accompanied by a variety of symptoms, including extreme fatigue, unexplained fever, joint pain/swelling, and butterfly rash. The prevalence of SLE ranges from 20/100000 to 150/100000. 

Currently, the treatment of SLE is mainly based on immunosuppressive agents. Although these drugs can improve the symptoms and prognosis of SLE, they also have some issues such as lack of selectivity and more side effects. In recent years, with the rapid development of immunology and the deepening of the research on the pathogenesis of SLE, as a new drug for SLE, biological agents have gradually come into the scene.