Conclusion
miR-155 knockdown inhibited the NLRP3/Caspase-1 pathway by targeting SMAD2, thus inhibiting mouse KOA chondrocyte pyroptosis.
Methods
Mouse KOA chondrocyte model was established by lipopolysaccharide (LPS) induction and identified through Collagen II immunofluorescence staining and toluidine blue staining. LPS-induced KOA chondrocytes were transfected with miR-155 inhibitor or/and si-SMAD2, followed by the evaluation of miR-155 expression, pyroptosis, the SMAD2/NLRP3/Caspase-1 axis-related protein levels, IL-1β and 1L-18 levels, and cell viability by RT-qPCR, FAM-FLICA Caspase-1 Detection Kit, Western blot, ELISA, and MTT assays, respectively. The binding sites between miR-155 and SMAD2 were predicted online and the binding relationship was verified by dual-luciferase assay.
Objective
Knee osteoarthritis (KOA) is based on degenerative pathological changes. miR-155 is involved in regulating KOA. This study estimated the mechanism of miR-155 in mouse KOA chondrocytes.
Results
miR-155 was highly-expressed in LPS-induced KOA chondrocytes. miR-155 knockdown increased cell viability and decreased pyroptotic chondrocytes, and Caspase-1, 1L-1β and 1L-18 levels. miR-155 targeted SMAD2. SMAD2 knockdown partially annulled the effects of miR-155 silencing on inhibiting KOA chondrocyte pyroptosis. NLRP3 pathway was activated in LPS-induced KOA chondrocytes, inhibited after miR-155 knockdown, and activated again after further SMAD2 knockdown. NLRP3 inhibition suppressed Caspase-1, IL-1β, and IL-18 levels and chondrocyte pyroptosis and increased cell viability.