Research Of Kun Ming (KM) Mutant Mice Chronic Inflammatory Skin Disease Model

Background KM spontaneous mutant mice were found in the breeding ground of our research institute. The first mutant mouse has abnormal phenotype that the hair of the whole body is sparse, the epidermis is thicken and the skin ruga. Now they are raised in the SPF level animal room. During the breeding, we found that the mutant phenotype of the KM mutant mice can inherit steadily. The mutant phenotype of the mutant mice is almost the same as the wild-type at the age of newborn, and they are distinguished when their hair begins growing at1week old around. The hair of KM mutant mice is sparse and we can see the pink skin till weaning. When they grown-up, their skin show distinctly loose and wrinkle and the surface present arefaction, in addition, some mutant mice drop scurf and some show skin ulcer, which are similar to the symptom of human chronic inflammatory skin disease. Therefore, we inbreed the KM mutant mice and hope to discover the mutant rule of inheritance and the orientation of the mutant gene. We make the preliminary research of the biological characteristics of KM mutant mice and detect the differences between the KM mutant mice and wild-type in the biological characteristics; According to the phenotype of mutant mice, We observe the changes of the pathological mechanism of skin, and the immune cells and molecules, and the changes of number of lymphocyte of immunity organ including spleen and lymph node which will be hopeful to help us understand the systemic phenotype characteristics and genetic law of mutant mice, and lay the foundation for the subsequent gene location and mechanism research, and further develop the new animal models of disease.Methods We inbred the mice strain and observed their rule of inheritance with the methods of sib-cross, top-cross and so on. We made the electronic pickup to observe the phenotype dynamically of the mutant and the wild-type mice. We detected the weight, organ coefficient, metabolic rate, temperature, blood routine and biochemical tests with the mice of different months and sexes. We used the conventional HE histologic, immunohistochemistry and special staining to detect the amount of skin inflammatory cells and cytokines, and detected the expression of adipokines leptin in adipose tissue of KM mutant mice and KM wild-type mice of3month and6month years old. We further detected the apoptosis and proliferation of skin tissue, spleen and lymph gland of the KM mutant mice and KM wild-type mice of different age group, and detected the account of T, B lymphocyte in spleen and lymph gland.Results KM mutant mice were bred to the tenth generation and showed inherit steadily. Through the observation of the mutant phenotype penetrance, we inferred that the genetic law was autosomal recessive mutation conctrolled by a single gene and had no gender differences, which was almost coincidence with the Mendel gene separation rule. The mutant phenotype of the KM mutant mice showed hair hypotrichosis, scurf, rhicnosis and so on. They grew slowly and their weight was obviously less than the same age of the KM wildtype mice. Other internal organs of weight coefficient were almost higher than KM wildtype mice of the same age old except the thymus and abdominal fat. They behaved hyperpyrexia and drank large amount of water. Blood routine results were that count of white blood cell, lymphocyte percentage were higher than the same age of wild-type mice, and the granulocyte percentage decline with the age increases, the monocyte percentage had the increasing trend. The level of blood sugar, cholestenone, triglyceride and high density lipoprotein descend, the level of low density lipoprotein elevate. Skin organization pathology manifest epidermis cells necrosis, and the epithelium hyperkeratosis or parakeratosis, stratum granulosum incrassation, basal cell layer edema, dermis shallow hemangiectasis, connective tissue inflammatory cell infiltration and so on. T cells, macrophage, mast cell et. al and inflammatory factor IL-6, IL-22、TNF-α、IFN-γ et. al infiltration increased in the skin tissue. Leptin expression increased in adipose tissue.The apoptotic cells of epidermal organization showed weakly increases, their hair-follicle and sebum gland cell increment reduced. The perish of spleen and the lymph node cell increased weakly relatively and the3month,6month old mutant mice proliferation cell increase, but9month old mutant mice proliferation cell reduced. T, B lymphocyte in spleen and lymph node increased, but the number of B cell reduced in9month old mutant mice.Conclusions The mutant phenotype of KM spontaneous mutant mice mainly show spontaneous chronic inflammatory disease in their skin tissue and systemic inflammation alters, and can inherit steadily, which have the same pathology and cellular elements changes as the human chronic inflammatory skin disease. KM mutant mice have the hope of becoming the new animal model of chronic inflammatory skin disease if we further research and locate the mutant gene.