[Expression of the melanoma 2-mediated pyroptosis pathway in peripheral blood mononuclear cells of patients with idiopathic inflammatory myopathies].

OBJECTIVE: To detect the expression levels of absence in melanoma 2 (AIM2), cysteine aspartate-specific protease-1 (caspase-1), and gasdermin D (GSDMD) in peripheral blood mononuclear cell (PBMC) of patients with idiopathic inflammatory myopathy (IIM) and to explore their role in the pathogenesis of IIM.

METHODS: A total of 30 IIM patients (IIM group) who visited the Department of Rheumatology and Immunology, General Hospital of Northern Theater Command from May 2020 to June 2022 were recruited. Concurrently, 30 healthy volunteers matched by gender and age were recruited from the hospital's Health Examination Center. Clinical information, biochemical and immunological mar-kers, and venous blood samples were collected from the study subjects. Serum double-stranded DNA (dsDNA) levels were detected by fluorescence quantitative method, and the mRNA expression levels of AIM2, caspase-1, GSDMD, interleukin 1β (IL-1β), and IL-18 in PBMC were detected by reverse transcription quantitative real-time PCR (RT-qPCR). The protein expression levels of AIM2, caspase-1, GSDMD, IL-1β, and IL-18 in PBMC were detected using the Western blot (WB) method, and the serum levels of IL-1β and IL-18 were detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS: The IIM group included 10 cases of dermatomyositis (DM), 5 cases of polymyositis (PM), 11 cases of overlap syndrome (OM), and 4 cases of immune-mediated necrotizing myopathy (IMNM). Compared with the healthy control group, the serum levels of dsDNA, IL-1β, and IL-18 were significantly increased in the IIM group and its subgroups (P < 0.05). Except for the fact that there was no statistically significant difference in AIM2 mRNA levels in PBMC of the IMNM subgroup compared to the healthy control group, the expression of AIM2, caspase-1, and GSDMD mRNA was significantly increased in the IIM group and other subgroups (P < 0.05); Except for the comparison of IL-1β mRNA levels in PBMC of the IMNM and OM subgroups with the healthy control group showing no statistical difference, the expression of IL-1β and IL-18 mRNA was significantly increased in the IIM group and other subgroups (P < 0.05); Comparisons between subgroups indicated that the expression of IL-1β mRNA in the DM subgroup was significantly higher than that in the OM and IMNM subgroups, and the expression of IL-18 mRNA in the PM subgroup was significantly higher than that in the DM and OM subgroups (P < 0.05). The expression levels of AIM2, caspase-1, GSDMD, IL-1β, and IL-18 proteins in PBMC of the IIM group and its subgroups were significantly higher than those in the healthy control group (P < 0.05); Comparisons among subgroups revealed that the expression of IL-18 protein in the OM subgroup was significantly higher than that in the PM subgroup (P < 0.05). In the IIM group, the mRNA of caspase-1, GSDMD, and IL-18 showed a positive correlation with AIM2 mRNA, and the protein expression of caspase-1, GSDMD, IL-1β, and IL-18 also showed a positive correlation with AIM2 protein expression.

CONCLUSION: The AIM2 inflammasome-mediated pyroptosis pathway may be involved in the pathogenesis of IIM, providing a theoretical basis for further research on the etiology of IIM and the development of new therapies.