Role Of CD100/Plexin B2 Interaction In The Pathogenesis Of Psoriasis

Psoriasis is a common clinical disease. It is a chronic inflammatory skin disease characterized by proliferation and abnormal differentiation of epidermal keratinocyte, excessive dermal papillary vascular dilatation and shallow infiltration ofinflammatory cell. The typical manifestationis clear boundary of erythematous scaly plaques. Psoriasis is extremely easy to relapse and difficult to treat which serious impair the quality of patients’ life. The exact pathogenesis of psoriasis has not been studied clearly, so now there is no ideal treatment. Because of this, the research on the pathogenesis of psoriasis is always a hot spot. The previews researches showed that, the interaction between KC and T cell is the key point of the onset of psoriasis. The interaction forms a malignant cycle, which makes the psoriasis hard to heal. So, it is important to further study the interaction between KC and T cell to demonstrate the pathogenesis as well as to invest new effective treatment to psoriasis.Recently, scientists found out that the γδ T cell from mice combined with Plexin-B2 on the KC surface through its CD100, which induce theγδ T cell to change tis conformation and to migrate. It showed that CD100-Plexin B2 is the key point to mediate the interaction between the γδ T cell and KC. CD100 also called Semaphorin 4D, is an important molecule that participate in immune modulation. It is highly expressed on T cell surface, modulate T cell and B cell activation, exist as soluble form(s CD100) in plasma at a low level. High affinity receptor of CD100 is Plexin-B1 and Plexin-B2, which expressed in many epithelial and endothelial cell as well as nerve and immune cells, they participate in proliferation and migration of a variety of tissues and cells.In our previous works, we analyzed the expression of s CD100 in patients with psoriasis, found out that the s CD100 serum level in psoriasis patients was significantly higher than that of normal control. The expression of Plexin-B2 found in KC of psoriatic lesions is relatively high, whereas the expression is pretty low in eczema tissue and normal skin. This result suggestthat CD100-Plexin-B2 might be involved in the pathogenesis of psoriasis, and may mediate the interaction of KC and γδT cell, but the exact mechanism is not clear.We hypothesize that, the interaction between CD100 and Plexin-B2 is involved in the pathogenesis of psoriasis: on the one hand, s CD100 in psoriasis patient combinewith Plexin-B2 in the lesions of KC surface, regulate proliferation, migration and other biological activity of KC; on the other hand, through the KC membrane surface Plexin-B2 molecule, KC interact with epidermal γδ T cell, regulate its activation and migration in the epidermis.1. Further clarify the expression of CD100 and Plexin B2 in the tissue of patients with psoriasis, and confirm the function of KC towards CD100.2. Useing IMQ-induced psoriasis like animal model to illuminate the function of CD100 and Plexin B2 in the mice model of psoriasis like disease.3. To clarify molecular machanisms of the interaction of CD100 and Plexin B2, which based on cell culture in vitro. Methods:1. Evaluated the expression of CD100 and Plexin B2 in skin tissues and peripheral blood with immunohistochemistry, western-blot, ELISA and Real-time PCR in Psoriasis patients.2. Evaluated the effect of CD100 on KC cells, including cell growth, proliferation and apoptosis, by stimulating Hacat and primary KC cells with CD100. Stimulated KC cells and Hacat cells with CD100 for 24 h. Evaluated capability of cell migration and invasion by Wound healing and Transwell test.3. Construct a IMQ-induced mice psoriasis like dermatitis model, test the expression of CD100 and Plexin-B2 on mice ear. Analysis the differences of the mice model after using Si RNA to block Plexin-B2, from different aspect like the whole condition, HE staining, and infiltration of lymphocytes. Further more, work on the type of infiltrated cells and the condition of secreted cytokins after blocking the expression of Plexin-B2 on mice ear skin, and find the mechanism of Plexin-B2 working in psoriasis.4. Ues Si RNA to block the expression of Plexin-B2 during cell culture in vitro, observe the effect on the growth, the proliferation, the apoptosis of KCs and Ha Cat cells with decreased Plexin-B2, study on the changes of proliferation of KCs and Ha Cat cells toward the stimulation from CD100, and test the expression of related cytokins5. Analysis the down stream pathway for CD100-Plexin-B2 by cell cell culture in vitro. Results:1. The expression level of s CD100 significantly increased in peripheral blood of Psoriasis patients. Compare to healthy population, CD100 and plexin B2 obviously increased in skin lesion of Psoriasis patients.2. s CD100 could promote the proliferation, migration, and invasion of Ha Cat cells and KCs, inhibited the apoptosis of Ha Cat cells and KCs. Blocking Plexin-B2 could inhibited proliferation of KCs which were induced by CD100. These results indicate that CD100 promote the proliferation and invasion of KCs, according to the interaction of Plexin-B2.3. Successfully built the IMQ-induced mice psoriasis like dermatitis model, the skin of the mice ear shows a clearly thickening as well as swelling and scales after using IMQ for 7 days, and also, the expression of Plexin-B2 was highly increased. The thickening, the swelling, the scales were significantly relieved after blocking the expression of Plexin-B2, and the infiltration of T cells, DCs, and macrophages were obviously decreased, mean while, the secretion of inflammation-related cytokines and chemokines like IL-17, IL-22, IL-36,CXCL1,CCL20 was decreased. All these results show that Plexin-B2 is very important in IMQ-induced psoriasis mice model.4. Blocking Plexin-B2 on Ha Cat, could significantly inhibited proliferation, migration, and invasion of Ha Cat, and promote the apoptosis. Blocking Plexin-B2 could inhibited psoriasis-related cytokines induced production of chemokines by KCs. This indicated that the function of Plexin-B2 in psoriasis mainly depends on it’s effect on related cytokines and chemokines.5. Blocking Plexin B2 could inhibited activation of Akt and Erk pathway on Hacat cells. Which indicate that Plexin B2 might play a role in this process by activating the downstream Akt and Erk signaling pathway. CD100 could stimulate Ha Cat cells by activating downstream signaling pathway of Akt and Erk. Conclusion:We found that CD100 and it’s ligand, Plexin-B2, were abnormal expressed in psoriasis. The interaction of CD100-Plexin-B2 could promote migration and proliferation of KCs. Plexin-B2 participate in the onset of mice psoriasis-like dermatitis model according to inhibitation of infiltrated lymphocytes and effection on secretion of related cytokines and chemokines. The downstream pathway of CD100-Plexin-B2 include Akt and Erk signaling pathway. Our research is the first to line out that the interaction of CD100-Plexin-B2 play an important role in psoriasis, and indicate it’s potential mechanism in psoriasis, which support a new ideal for therapy of psoriasis.