Juanbi Qianggu Formula inhibits fibroblast-like synovicytes activation via repressing LncRNA ITSN1-2 to promote RIP2 K48 ubiquitination.

Background: Long non-coding RNA ITSN1-2(lncRNA ITSN1-2) promotes fibroblast-like synovicytes (FLS) proliferation and suppress apoptosis through activation of the NOD2/RIP2 signaling pathway, thereby exacerbating synovitis in Rheumatoid arthritis (RA) pathology. Juanbi Qianggu Formula (JBQG), a clinically efficacious traditional Chinese medicine, has shown significant efficiency in inhibiting FLS activation in RA and alleviating disease progression in RA patients. However, the molecular mechanism underlying JBQG's anti-arthritic effects remains incompletely understood, particularly regarding its potential to modulate lncRNA ITSN1-2-mediated NOD2/RIP2 signaling in FLS activation. This study aims to investigate the functional interplay between JBQG and the lncRNA ITSN1-2/NOD2/RIP2 axis in regulating FLS behavior during RA development.

Methods: Synovial tissues were collected from 24 rheumatoid arthritis (RA) patients and 20 osteoarthritis (OA) patients to observe the lncRNA ITSN1-2/NOD2/RIP2 signal in RA synovial tissue and its correlation with RA inflammation and bone destruction. Blood-absorbed components of JBQG were analyzed through mass spectrometry, while network pharmacology and in vitro experiments were conducted to investigate JBQG's regulatory effects on NOD2/RIP2 signaling. Mechanistic studies focused on lncRNA-ITSN1-2/miR-2683-3p/PELI3/RIP2 interactions, employing dual-luciferase assays, FISH staining, and Co-IP/Western blot. To evaluate therapeutic efficacy, a collagen-induced arthritis (CIA) rat model with lncRNA ITSN1-2 overexpression was established. JBQG's effects were assessed through histopathological examination and serum inflammation factors analysis following 23 g/kg/day treatment for 4 weeks.

Results: LncRNA ITSN1-2/NOD2/RIP2 signaling was significantly activated in RA synovial tissues, showing profound correlation with RA disease inflammation and progression. JBQG treatment reduced cytoplasmic lncRNA ITSN1-2 levels in FLS, thereby inhibiting NOD2/RIP2 pathway activation and FLS functions in migration and invasion. Mechanistically, lncRNA ITSN1-2 exerted competitive endogenous RNA (ceRNA) activity by sequestering miR-2683-3p, which upregulated PELI3 expression. This induction promoted RIP2 K48 ubiquitination, destabilizing RIP2 protein integrity and inhibiting downstream NF-κB signaling. Consequently, FLS migratory and invasive capacities were significantly diminished, underscoring JBQG's dual regulatory impact on lncRNA-miRNA cross-talk and inflammatory cytokine cascades.

Conclusion: This study demonstrates that JBQG exerts potent anti-arthritic effects in RA therapy through dual regulatory mechanisms targeting the lncRNA ITSN1-2/miR-2683-3p/PELI3/RIP2 axis.