Pan-organ damage analysis in the R848-induced systemic lupus erythematosus mouse model.

Abstract

BACKGROUND: Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that often leads to organ dysfunction. Resiquimod (R848) can induce the establishment of SLE models in mice within a relatively short period. However, there are few comprehensive systematic research reports on the degree and differences of organ involvement in this model. Therefore, the aim of this study was to clarify the systemic involvement of the SLE model induced by R848. METHODS: C57BL/6 mice were treated with 2 μg/μL R848 for 4 weeks. After the last administration, H&E staining was used to examine pathological changes in multiple organs (bone, thymus, spleen, knee joints, kidney, etc.). Real-time quantitative PCR (RT-qPCR) and western blotting were used to detect the mRNA and protein levels of toll-like receptors (TLRs) and inflammatory factors. Flow cytometry analysis was performed to examine the changes in T- and B-cell subsets within the spleen. Immunofluorescence was used to analyse immune complex deposition in the kidneys. RESULTS: R848 successfully induced an SLE mouse model characterized by splenomegaly, elevated serum levels of anti-dsDNA antibodies, immune complex deposition in the kidneys, and imbalanced T-/B- cell populations, etc. Severe pathological changes were detected in specific organs, such as the bone, thymus, spleen, and knee joint, whereas no obvious lesions were observed in organs, such as the heart. Accordingly, the Tlr7/8/9 pathway and its downstream inflammatory factor targets (Tnf, Ifng, Il6, and Il10) presented organ-specific expression profiles at the transcriptional level and the western blotting confirmed that the protein levels of TLR7/8 and TNF-α increased particularly in the spleen, but not in the kidney or submandibular gland. CONCLUSION: R848-induced SLE mice exhibit systemic immune disorders, with differences in pan-organ damage, inflammatory cell infiltration, and TLR7/8-mediated inflammatory factor expression. This study provides a foundation for clarifying the multisystem mechanism of SLE.