Abstract: 【Abstract】 Objective To explore the relationship between serum thymic stromal lymphopoietin （TSLP） levels and the occurrence of pruritus as well as interstitial lung diseases （ILD） in patients with dermatomyositis （DM） or clinically amyopathic dermatomyositis （CADM）. Methods A retrospective analysis was conducted on the clinical data from 61 diagnosed DM/CADM patients at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine between February 2019 and March 2022. Thirty-five age- and sex-matched healthy individuals were included as controls. Serum TSLP and anti-melanoma differentiation-associated gene 5 （MDA5） antibody levels were measured using enzyme-linked immunosorbent assay （ELISA）. A multiplexed flow cytometry assay was performed to detect the serum levels of 12 cytokines, including interferon （IFN）-α2, IFN-γ, interleukin （IL）-4, IL-5, etc. Pruritus severity in DM/CADM patients was assessed using the visual analog scale （VAS）. Relationships of serum TSLP levels with skin lesions, inflammatory markers, and the severity of ILD were analyzed using GraphPad Prism 8.0.1 and R （version 4.3.2） software. Results Among the 61 patients with DM/CADM, 18 were males （13 with DM and 5 with CADM） and 43 were females （30 with DM and 13 with CADM）, with ages of 53.08 ± 14.97 years and disease duration of 6.27 ± 4.27 months. No significant differences were observed in sex or age between the DM/CADM group and the healthy control group （both P > 0.05）. Of the 61 patients, 15 （24.59%） were positive for anti-MDA5 antibodies, and 31 （51.67%） had ILD, including 11 with acute/subacute interstitial pneumonia （A/SIP）. The pruritus VAS score （M ［Q1, Q3］） among the 61 patients was 3 （0, 6） points; 20 patients （32.79%） reported no pruritus, while 11 （18.32%）, 17 （27.87%）, and 13 （21.31%） experienced mild, moderate, and severe pruritus, respectively. Serum TSLP levels were significantly higher in the DM/CADM patients than in the healthy controls （91.0 ［34.6, 273.0］ vs. 25.0 ［0.0, 83.5］ pg/ml, Z = 1 502.50, P < 0.001］. The TSLP levels were significantly positively correlated with serum levels of alanine aminotransferase （ALT）, lactate dehydrogenase, C-reactive protein, erythrocyte sedimentation rate and ferritin, and significantly negatively correlated with pruritus VAS scores, eosinophil percentages, and eosinophil counts （all P < 0.05）. Serum TSLP levels were significantly higher in the anti-MDA5 antibody-positive patients than in the anti-MDA5 antibody-negative patients （273.0 ［103.8, 2 576.0］ pg/ml vs. 67.4 ［16.9, 218.7］ pg/ml, P = 0.002）, as well as in the patients with A/SIP than in those without A/SIP （390.0 ［168.2, 2 869.6］ vs. 67.5 ［21.8, 235.9］ pg/ml, P < 0.001）. ROC analysis showed that the combined detection of serum TSLP levels and anti-MDA5 antibodies had a higher predictive value for A/SIP in DM/CADM patients （AUC = 0.922） than either the detection of anti-MDA5 antibodies （AUC = 0.831） or TSLP （AUC = 0.824） alone did. Conclusions Serum TSLP levels were significantly higher in patients with DM/CADM than in healthy controls, with particularly higher levels observed in anti-MDA5 antibody-positive patients and patients with coexisting A/SIP, and were correlated with several indicators of disease activity. The combination of serum TSLP levels and anti-MDA5 antibodies provided greater predictive value for A/SIP than either of them alone did.

Key words: Dermatomyositis, Pruritus, Thymic stromal lymphopoietin, Lung diseases, interstitial, Clinically amyopathic dermatomyositis