Mechanism Of Narrowband Ultraviolet-B Irradiation In The Treatment Of Psoriasis

Background:Psoriasis is a chronic immunoinflammatory skin disease characterized by excessive proliferation and abnormal differentiation of epidermal keratinocytes,infiltration of lymphocytes（mostly T cells）,dermal vascular changes such as angiogenesis,dilation,tortuosity,high endothelial small vessel formation,The most common clinical manifestation is psoriasis vulgaris.Psoriasis has a wide range of etiologies and a complex pathogenesis.Immune pathways play an important role in the pathogenesis of psoriasis.The pathogenesis of psoriasis is closely related to chronic inflammation mediated by abnormal activation of T cells.Psoriasis is caused by the complex interaction of the immune system,psoriasis-related susceptible sites,autoantigens,and a variety of environmental factors.In the past 20 years,studies have clearly shown that psoriasis is a true T cell-mediated disease,driven mainly by pathogenic T cells,immune system disorders and T cell activation has been fully proved in the development of psoriasis plays a vital role.In the clinical treatment of psoriasis,narrow-band ultraviolet（NB-UVB）is widely used as a treatment.NB-UVB phototherapy is an important treatment in dermatology.The most common dermatological indications for NB-UVB include psoriasis,atopic dermatitis,and vitiligo,and it has been found to be an effective and well tolerated treatment option in a variety of dermatological conditions,but the mechanism of NB-UVB treatment for skin disorders has not been fully elucidated.Objective:The purpose of this study is to clarify these mechanisms,evaluate the role of vascular endothelial growth factor（VEGF）and RasGRP1 in the treatment of psoriasis with NB-UVB irradiation,and explore the mechanism of RasGRP1 in the pathogenesis of psoriasis to provide new functional targets for the diagnosis and treatment of psoriasis.Methods:（1）The psoriatic mice were treated with NB-UVB irradiation,The skin tissues of NB-UVB treated mice were sequenced by gene transcriptome.（2）We made functional prediction of Rasgrp1 gene,carried out functional research related to the pathogenesis of psoriasis,and analyzed the relationship between Rasgrp1 gene expression and psoriasis.（3）We used RNA sequencing immunohistochemistry and other techniques to analyze the changes of expression pattern（expression area and cell positioning）of Rasgrp1 gene in psoriasis mice and clinical psoriasis patients.（4）To explore the role of Rasgrp1 and its upstream gene VEGF in the pathogenesis of psoriasis.We irradiated mice,Ha Ca T and Jur Kat cell lines with NB-UVB respectively.The clinical samples were used as models to explore the function and regulatory mechanism of VEGF-RasGRP1 in the treatment of psoriasis.Results:（1）Compared with the control group,the gene transcription level of Rasgrp1is up-regulated in the skin tissues of psoriasis patients and IMQ-induced psoriasis mice.The protein expression of RasGRP1 is significantly increased in the skin of imiquimod-induced psoriasis mice.The immunofluorescence detection of psoriatic lesions shows that RasGRP1 is mainly expressed in T cells.（2）By RNA-Seq sequencing,we found that NB-UVB irradiation inhibited the RAS pathway of mice,and VEGF-RasGRP1 was significantly inhibited.Through related experiments,we have found that NB-UVB significantly reduces skin inflammation in psoriasis mice and reduces the secretion of IL-17A by T cells.（3）NB-UVB can significantly inhibit the expression of VEGF gene and protein in the skin tissue of psoriasis mice.In order to confirm the main cell population that secretes VEGF,single cell sequencing showed that VEGF is mainly secreted by epidermal keratinocytes.By separating the skin epidermis and dermal tissue,it was found that NB-UVB can significantly inhibit VEGF in the epidermis,while VEGF in the dermal tissue is not affected by NB-UVB.After exploring the appropriate dose and time of NB-UVB radiation,we administered an appropriate amount of NB-UVB radiation to Ha Ca T cells.The results showed that at the irradiation dose of400m J/cm2 and the irradiation time of 8h,NB-UVB could significantly inhibit VEGF expression in Ha Ca T cells.（4）The subcutaneous injection of VEGF165 into IMQ-induced mice can aggravate the psoriasis phenotype of mice,activating the expression of RAS pathway and aggravate the skin inflammation of psoriasis mice.The small molecule inhibitor SU5205 is used as the inhibitor of VEGFR2 to effectively reduce the skin inflammation of psoriasis mice and inhibit the expression of RasGRP1 in the skin tissue of psoriasis mice,thereby reducing the production of IL-17A+αβT andγδT cells;It proved that VEGF-VEGFR2 pathway was involved in the regulation of skin inflammation in psoriasis mice.（5）Rasgrp1 gene knockout can effectively reduce the IMQ-induced psoriasis-like phenotype and inflammation in mice,and reduce the proportion of IL-17A+αβT and IL-17A+γδT cells in the skin tissue of psoriasis mice.The expression of AKT-NF-κB pathway in the skin of Rasgrp1^-/-psoriasis mice was detected,and the results showed that the knock-out of Rasgrp1 could inhibit the production of IL-17A by T cells by affecting AKT-NF-κB pathway.（6）Stimulating Jur Kat cells with VEGF,and transfecting RASGRP1 overexpression lentivirus and knockdown lentivirus into the Jur Kat cells at the same time,and finding that VEGF can significantly activate the secretion of RASGRP1 and downstream inflammatory factors in the Jur Kat cells,and the overexpression and knockdown of RASGRP1 in the Jur Kat cells can affect the secretion of downstream inflammatory factors;（7）The mice were subcutaneously injected with the adeno-associated virus of RasGRP1 to construct an overexpression model of RasGRP1.The mice overexpressed RasGRP1 were induced by imiquimod to produce psoriatic inflammation.Compared with the mice in the control group,the overexpression of RasGRP1 significantly aggravated the skin inflammation in psoriatic mice,and activated the AKT-NF-κB pathway,which increased the secretion of IL-17A by T cells.Conclusion:The expression of RasGRP1 in activated T cells of the psoriatic mouse and human skin was significantly increased.NB-UVB radiation inhibits the production of inflammatory factors through the VEGF-RasGRP1-AKT-NF-κB pathway and reduces the levels of psoriasis-related inflammatory factors such as skin IL-1βand IL-17,thereby reducing psoriatic skin inflammation.The knock-out of Rasgrp1 can significantly reduce skin inflammation in psoriasis mice and provide a potential target for the treatment of psoriasis.