疾病动物模型,类风湿性关节炎 z-bio 2021-11-06 545

　　So far, induced animal models are the most widely used in RA research. It can be made not only with rodents, but also rabbits, dogs and monkeys. There are many types of inducers, including AA model, CIA model and OIA model. However, these induced animal models still have a certain gap with human clinical manifestations in pathological changes and immune system regulation disorders. For example, there is no antinuclear antibody, and no subcutaneous nodules, serositis, and vasculitis of RA. RA Animal models are only under certain conditions. Established by focusing on one or several factors. Can not fully reflect all the characteristics of RA.

　　(1) Adjuvant arthritis model

　　【Modeling mechanism】Adjuvants can cause inflammation in local lymph nodes and help stimulate the proliferation of immune cells. Immunization of animals with complete Freund's adjuvant (CFA) can stimulate the proliferation of immune cells, increase the immune function of the animal's body abnormally, and produce an autoimmune response against the synovium of the joints. The immune complexes are deposited in the joint cavity. Produce changes similar to rheumatoid arthritis.

　　【Modeling method】Mix liquid paraffin and anhydrous lanolin in a ratio of 2:1 or 6:4, add 80℃ inactivated BCG vaccine (BEG) to prepare a BCG emulsion with a concentration of 10g/L, and mill it fully to form Water-in-oil emulsion. Fully emulsified and mixed CFA was injected subcutaneously into the plantar part of the hind limb of the rat, and 0.1ml was injected into one side at a time. After CFA injection, observe the rat's reaction, joint swelling, histopathological changes and the changes of lymphocyte subsets. This model is called AA (adjuvant arthritis) rat model.

　　Note: ①When preparing CFA, the various ingredients should be fully ground in a mortar, or two syringes connected with a three-way tube for repeated injections, and mixed thoroughly to form a water-in-oil emulsion to delay the absorption of the adjuvant. Stimulate the immune system. ②Young (<21 days="" or="" older="">9 months old) rats are not easy to induce adjuvant arthritis.

　　【Features of the model】The primary lesions of the AA model are mainly local inflammatory reactions. The secondary lesions usually appear about 10 to 20 days after inflammation, and reach a peak about 20 days. Inflammation is most important in the ankle joint, which can invade the pads and the whole foot. The pathological changes included inflammation of the subsynovial tissue, synovial hyperplasia, pannus formation, and cartilage destruction; 4 weeks later, joint redness and swelling decreased, osteopenia, new bone formation, joint space narrowing, and irreversible joint changes.

　　[Model Evaluation and Application] The AA model can be used to study the pathogenesis of rheumatoid arthritis, the study of autoimmune pathology and the pharmacodynamics of rheumatoid arthritis drugs.

　　After sensitization, the AA rat model developed significant swelling of the ankle joints of both hind limbs, the sensitized side ankle joint system had inflammatory swelling, and the sensitized side had secondary autoimmune swelling, suggesting that the AA rat model and RA patients There are similarities in joint swelling. However, the AA rat model showed obvious T cell dysfunction, while RA patients often showed abnormal humoral and cellular immune function. This is the difference between the immune dysfunction of the AA rat model and RA patients.

　　The method of this model is simple and easy to implement, and its pathological performance is similar to RA, but it lacks chronic pathological process, the lesion has a certain degree of self-limiting, and there are certain differences in pathophysiology and other aspects. There are certain limitations in using the AA rat model alone.

　　(2) Collagen-induced arthritis model

　　[Modeling mechanism] Collagen is an extracellular matrix component, divided into type I, type II and type III. Type Ⅰ and type Ⅲ collagen are found in the interstitium of skin and some organs, while type Ⅱ collagen is abundantly found in articular cartilage. Immunization of animals with heterologous type II collagen can induce an autoimmune response against type II collagen in articular cartilage and establish a collagen-induced arthritis model.

　　[Modeling method] Dissolve the heterologous type II collagen in 0.1 mol/L acetic acid to make a 2g/L solution, stir at 4℃ to fully dissolve it, put it in the refrigerator at 4℃ overnight; then put the type II into a 2g/L solution. Collagen and CFA are mixed and emulsified in equal volume to make CII emulsion (that is, 1mg CII and 1m9 BCG vaccine per milliliter).

　　1. Preparation of mouse collagen-induced arthritis (CIA) model. The emulsion was injected intracutaneously with 0.1 ml of the tail root of each mouse to cause inflammation, and 0.1 ml of the emulsion was injected intraperitoneally on the 20th day as a challenge injection.

　　2. Preparation of the rat CIA model The rat's back is shaved, and 1 ml of emulsion is injected into the back of the rat intracutaneously in 4 to 6 locations. One week later, the booster immunization is performed, and 0.5 ml is injected.

　　"After the immune induction, observe the animal's response, joint swelling, histopathological changes and changes in lymphocyte subsets.

　　【Features of the model】The mice developed joint swelling on the 24th day after the mice were sensitized. The redness and swelling of the two hind feet first appeared, and then spread to the forefoot and the tail and became more serious, reaching the highest peak at 36 days. In addition, during the onset of the disease, the animal's coat loses its luster, slightly sheds hair, loses weight, and is accompanied by inflammatory lesions in the ears and tail.

　　Seven days after the rats were sensitized, the skin of some rats’ ankle joints became red, mildly swollen, and pathological sections showed mild inflammation; 14 days later, most of the rats’ ankle joints developed swelling, the skin of the feet and ankles was shiny, congested, and the joints moved. Restricted, pathological sections showed hyperplasia and hypertrophy of synovial tissue, with more inflammatory cell infiltration; 21 days later, joint swelling continued to increase, some rats developed skin ulcers, pathological sections showed abundant pannus formation and articular cartilage erosion; 5～ The pathological changes worsened after 6 weeks, and the articular cartilage and subchondral bone were both eroded and destroyed by pannus.

　　The immunological feature of CIA is that CD4+ T cells play a major role in regulating factors, and humoral immune factors such as anti-collagen type II autoantibodies and inflammatory cytokines also play an important role in its pathological process.

　　【Model Evaluation and Application】The CIA model can be used for the study of the pathogenesis of rheumatoid arthritis, autoimmune pathology, cytokine effects, and the pharmacodynamics of rheumatoid arthritis drugs. The induction of CIA is related to animal strains. Xenotype II collagen has a high induction rate in DA, BB, DR and LEW rats, while BM or F344 rats are less sensitive.

　　The clinical manifestation of the CIA model is multiple peripheral arthritis. The pathological changes are mainly proliferative synovitis, followed by articular cartilage destruction, and bone destruction. Monocytes infiltrate and persist in the synovium, and there are high-titer IgC and antibodies against their own type II collagen in animals, suggesting that the immune process is the main cause of the disease.

　　(3) Egg protein-induced arthritis model

　　【Modeling mechanism】Albumen is a heterogeneous protein. The animal is immunized with egg protein to make the animal body produce an immune response against egg protein. Finally, ovalbumin is injected into the joint cavity, so that the antibody against ovalbumin binds to the ovalbumin, and activates complement, resulting in the deposition of immune complexes in the joint cavity, causing the persistence of synovitis, synovial hyperplasia, pannus formation, and establishment Ovalbumin-induced arthritis model.

　　[Method of Modeling] Rats are mostly used for modeling. Dissolve egg protein in normal saline, make a solution of 20g/L, mix it with the same amount of CFA, and inject 1ml subcutaneously into the back of the rat for sensitization, 1 ml each time, once a week, sensitization for 3 consecutive weeks. One week after the last injection, 5 mg of solubilized egg protein was injected into the joint cavity.

　　"After the immune induction, observe the rat's reaction, joint swelling, histopathological changes and the changes of lymphocyte subsets.

　　【Features of the model】Within 24 hours after the last injection, joint swelling and thickening occurred, and the surface temperature increased significantly. The pathological manifestation was acute synovitis and a large amount of exudate. Subsequently, the swelling of the joints was reduced, reaching a plateau in 14 to 21 days, and the incidence rate reached 100%. The synovium of the joint is obviously proliferated and pannus is formed. The synovial cells increase from 1 to 3 layers to 5 to 10 layers, mainly monocytes and macrophages, followed by lymphocytes, and CD4+ T lymphocytes are more common. Early cartilage destruction may occur in some animals at this stage. Irreversible articular cartilage and bone destruction occurred after 4 weeks, necrosis of chondrocytes, cartilage fibrosis, and new subchondral bone formation. Finally, bone deformation may occur, and chronic inflammation may still exist by 6 months.

　　【Model evaluation and application】The ovalbumin-induced arthritis model can be used for research on the pathogenesis of rheumatoid arthritis, autoimmune pathology, cytokine effects, and pharmacodynamics of rheumatoid arthritis drugs.

　　The pathogenesis of the OIA model is mainly due to the persistence of antigens in the joints, which stimulate synovial cells to secrete antibodies and form antigen-antibody-C3 complexes, which make synovitis persist, synovial hyperplasia, and pannus formation. Immunoglobulin and C3 complexes are also found on the articular cartilage of RA patients, which proves that the ovalbumin-induced arthritis model has some similarities in the pathogenesis of RA.