Immunohistochemical analysis of pyroptosis‐related protein expression in IgG4‐related sialadenitis

NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3)-induced pyroptosis is involved in the development of a variety of autoimmune diseases, but its role in IgG4-related sialadenitis (IgG4-RS) is unclear.Salivary gland tissues from 19 patients with IgG4-RS were designated the experimental group, and peritumoral tissues from 20 patients with benign salivary gland tumours were designated the control group. The cell morphology and fibrosis in the IgG4-RS samples were observed by haematoxylin-eosin (H&E) and Masson trichrome (MT) staining. Immunohistochemical (IHC) staining was used to determine pyroptosis-related proteins (NLRP3, ASC (apoptosis-associated speck-like protein containing a CARD), Caspase-1, GSDMD (gasdermin family members, including digestive dermatin D), interleukin 1β (IL-1β), and interleukin 18 (IL-18)) expression levels.Increased lymphoid follicle proliferation, germinal centre plasma cell infiltration, and irregular fibrosis were observed in the experimental group compared with the control group. The NLRP3, ASC, Caspase-1, GSDMD, IL-1β, and IL-18 levels were significantly higher in the experimental group than in the control group (p < 0.0001).This study suggested that pyroptosis-related proteins might be involved in IgG4-RS pathogenesis. However, the specific cellular pathway involved and whether multiple cell death pathways contribute to the occurrence of IgG4-RS still need to be further studied.