The tonsil is no stranger to everyone. It is an important lymphoid organ. Because of its lymphocytes and antibodies, it can deal with various pathogenic microorganisms, including bacteria, viruses and parasites. It plays an anti-bacterial and anti-virus defense function and is often called the first gate of the human immune system. Our scientists have found that the tonsil flora is similar to the intestinal flora, and its microecological imbalance can lead to local immune activation and induce systemic immune response. A few days ago, the research group of Professor Li Zhanguo from the Clinical Immunology Center of Peking University People's Hospital and the research group of Professor Wang Jun from the Institute of Microbiology of the Chinese Academy of Sciences published a paper online in the international top academic journal advanced science, proving the immune regulation function of tonsil flora. In the future, antibacterial peptides from tonsils may be used to treat rheumatoid arthritis. It is understood that the oropharynx is the only way to eat and breathe. Therefore, tonsils are rich in microorganisms, including not only beneficial bacteria but also pathogenic bacteria. When it is stimulated by climate, environment, diet and other external factors or its own immunity is weak, tonsil microecological disorders, that is, common bacterial and viral infections, will occur, which will trigger local immune activation and induce systemic immune response. For example, hemolytic streptococcus infection can lead to rheumatic fever and acute glomerulonephritis. It has been found that the symbiotic flora is closely related to the occurrence and development of autoimmune diseases. Among them, there have been many reports on the mechanism of intestinal flora in the pathogenesis of autoimmune diseases such as rheumatoid arthritis (RA), while tonsils, as an important lymphoid organ and microbial reservoir as the intestine, have limited research on their flora. It can be seen in clinic that inflammation of tonsils can lead to rheumatoid arthritis. The pathogenic T cells in the synovium of patients' joints may originate from tonsils, but the mechanism of tonsils participating in the pathogenesis of rheumatoid arthritis is still unclear. Therefore, Li Zhanguo's Research Group paid attention to the role and mechanism of tonsil flora in the pathogenesis of rheumatoid arthritis. This is the first study on tonsil flora of rheumatoid arthritis patients and normal people in the world. By extracting tonsillar flora from patients and normal people and using metagenomic sequencing, the authors found that tonsillar flora in RA patients was obviously abnormal; Through metagenomic data analysis, it can be concluded that when the number of beneficial bacteria in tonsils decreases, the antibacterial ability can be greatly reduced, and the surrounding inflammatory reaction can not be controlled, resulting in infection or immune reaction. Experts say that cytokines are a double-edged sword, that is, they can play an immune regulatory role and participate in the occurrence of many diseases. Therefore, identifying the mechanism by which cytokines regulate disease status will help to design new treatments. This study found the important role of tonsil flora in immune balance and the immune regulatory mechanism of Streptococcus salivarius antimicrobial peptide salivaricin in rheumatoid arthritis. That is, when the antibacterial peptide in tonsils is insufficient, it can cause immune reaction disorder. Therefore, as long as sufficient tonsil antimicrobial peptides are supplemented, immune reactions can be avoided or used for the treatment of autoimmune diseases, providing potential targets for the treatment of autoimmune diseases. (outlook new era)