The Study Of The Therapeutic Effects Of Cold Atmospheric Plasma On Imiquimod-induced Psoriasiform Dermatitis In Mice

Recently,research on medical applications of cold atmospheric plasma(CAP)especially in dermatology,has become a hotspot worldwide.Studies have demonstrated that CAP can be applied to skin sterilization,wound healing,tissue regeneration and treatment of various neoplastic and inflammatory skin diseases.Psoriasis is a common inflammatory hyperproliferative skin disease,whose pathogenesis has not been fully understood.Current existing treatments cannot completely cure it.Keratinocyte hyperproliferation induced epidermal thickening is one of the characteristic manifestations of psoriatic lesions.Studies have shown that CAP can inhibit cell proliferation and even induce cell apoptosis.In addition,it has been reported that reactive oxygen species(ROS)from CAP have immunomodulatory effects.Thus,it is speculated that CAP can be used to treat psoriasis.This study mainly focused on the effects of CAP on the proliferation of KC in vitro or in vivo.Atmospheric pressure plasma jet(APPJ),a kind of CAP generator,was applied to Ha Ca T keratinocytes(indirectly)and imiquimod(IMQ)-induced psoriasiform dermatitis in mice(directly),which was undertaken to evaluate its therapeutic effects on psoriasis.The main contents and results are summarized as follows:1.The discharge characteristics of the APPJ device were detected and described.Cell culture medium was exposed to the above APPJ for different times and the treated medium was designated as plasma activated medium(PAM).The PH and the contents of the main active species of PAM were detected.It showed that the contents of the active species increased persistently with increasing plasma treatment time and the p H only changed slightly.2.The effects of PAM treatment on the proliferation of Ha Ca T cells and its related mechanisms were studied.The results indicated that PAM treatment could cause cell morphological changes,inhibit cell proliferation and induce cell apoptosis via increasing intracellular ROS levels dose dependently.3.Two common cellular inflammation models were used to simulate the inflammatory microenvironment in psoriatic lesions,and then the effect of PAM on the proliferation of the cells in the inflammatory state or not was examined.The results showed that the Ha Ca T cells under inflammatory state were more susceptible to PAM,under the same PAM dose,than the Ha Ca T cells under non-inflammatory state.It was presumed that the ROS levels in Ha Ca T cells in inflammation caused by LPS or TNF-α stimulation were increased,which resulted in an oxidative stress state and a decrease in tolerance to PAM.In addition,the co-culture system of normal Ha Ca T cells and Ha Ca T cells after inflammatory induction further verified their different sensitivity to PAM.4.The therapeutic effect of APPJ on IMQ-induced psoriasiform dermatitis in mice was evaluated according to the Psoriasis Area and Severity Index(PASI)scores and lesional HE staining.The results showed that the mice of the IMQ-induced model group showed typically psoriasis-like lesions.After APPJ treatment,the overall symptoms of skin lesions were significantly relieved,exhibiting lower PASI scores and reduced epidermal thickening.Those results indicated that APPJ had therapeutic effects on IMQ-induced psoriasiform dermatitis.5.The effects of APPJ on proliferation and apoptosis of the keratinocytes in psoriatic lesions were evaluated by Ki67 and active caspase-3 staining.Results showed that the proportion of Ki67 positive cells in the epidermis of the mice from psoriasiform model group was significantly increased,compared to that of the mice form control group.The proportion of Ki67 positive cells was significantly decreased after APPJ treatment.But APPJ treatment had no significant effect on the apoptosis of epidermal cells,which indicated that APPJ exerted therapeutic effects mainly by inhibiting the abnormal proliferation of keratinocyte.6.The effects of APPJ treatment on lesional cytokine expression,inflammatory infiltration and pathological angiogenesis were evaluated by immunohistochemical staining.The results showed that topical APPJ treatment significantly reduced the infiltration of CD3 positive cells into the lesions,and the expression of CD31,TNF-α,IL-17 and IL-22,exhibiting antiproliferative,anti-inflammatory and antiangiogenic effects.