## 2 Experiment Setup and Methods
### IMQ-Induced Psoriatic-Like Mouse Model  
The BALB/c mice used in the experiment were bought from HFK Bioscience (Beijing Co., Ltd., Beijing, China). These mice were bred in the animal facility under specific pathogen-free conditions for 10 days before the experiment. These mice were also weight and age matched. Animal experiments were performed in the USUHS laboratory animal facility. The protocol used in this study was approved by the USUHS Institutional Animal Care and Use Committee [20]. The dorsal hair of mice (8-10 weeks of age) was removed across a surface area of \(\sim\)4-5 cm\({}^{2}\)[1]. Next, 5% uniquimod (IMQ) cream (Mingxin Lidi Laboratory, Shanghai, China) was applied daily (at 07:00 AM) at a topical dose of 62.5 mg for 7 days to establish an IMQ-induced psoriasis mouse model [20]. The BALB/c mice were randomly divided into the following groups: control group; IMQ-treated group (topical dose with 62.5 mg of 5% IMQ cream alone, at 07:00 every day); LTP-treated group (LTP treatments for 10 min/day, at 13:00 every day); TWHF group (1 mg/cm\({}^{2}\)/day, at 19:00 every day); LTP + TWHF group (LTP treatments for 10 min followed by TWHF treatment, at 13:00 every day). Each group had five mice, and seven consecutive days of administration or plasma treatment was necessary for all mice. All mice were euthanized 24 h after the last treatment via cervical dislocation and the dorsal skins were collected. Another group of mice was used to study the penetration effect of LTP on mouse skin. A depilatory paste removed the mice's hairs, and the mice were killed via cervical dislocation after 24 h. A pair of small scissors was used to cut out the dorsal skin. Then, the isolated skin's subcutaneous tissue was scraped off cleanly with a surgical knife and washed with phosphate buffer saline (PBS) [1]. The isolated skin was covered with bibulous paper to remove the excess water and then immediately treated with the LTP jet array. Because the stratum corneum (SC) is an important skin barrier, the treatment position on the isolated skin was fixed without any movement for 5-10 min to study the effect of the plasma on the structural integrity of the SC. Measurement of Skin Inflammation Severity, Immunohistochemistry and Cytokine Detection via Quantitative Real-Time PCR  
The Psoriasis Area and Severity Index (PASI) includes measurements of skin thickness, erythema, and scale. The same measurements were carried out in our previous study [20]. All mice were evaluated as IMQ was administrated for seven consecutive days. The mouse skin's thickness was measured using a micrometer and averaged five times. In order to measure the epidermal thickness and cellular accumulation, surgical specimens of dorsal skin tissues were paraffin-embedded for H&E staining [20]. Paraffin-embedded tissues sections (4 mm) were stained with hematoxylin (Beyotime, Haimen, China) for 40 s and with eosin (Beyotime, China) for 30 s [20]. An OLYMPUS light microscope was used to measure the tissue sections. Photoshop in three separated fields of view was used to measure the mouse epidermis's thickness. Skin tissues were fixed with 4% paraformaldehydedehyde for 2 days and embedded with paraffin. Afterward, samples were cut into 4 mm thick slides. For immunohistochemistry, sections were sequentially incubated with the primary antibody anti-CD3 (1:100, Abcam) and the secondary antibody HRP anti-rabbit IgG (Maxim), and then the color was developed with diaminobenzidine. Image J software was used to measure the region where CD3+ cells accumulated for quantitative analyses, and accumulation was expressed as the percentage of positive cells. Twenty-four hours after the last treatment, the mice were euthanized via cervical dislocation, and the spleens, as well as the axillary and inguinal lymph nodes, were separated and placed in pre-cooled PBS. We removed the attached connective tissue of the spleens, and the axillary and inguinal lymph nodes, then put a 0.1 cm\({}^{3}\) tissue into 1 mL of saline.