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Objective Functional polymorphisms of interleukin 16 (IL16) have been reported to be closely related to the risk of osteoarthritis (OA). However, how IL16 affects OA remains unclear. In this study, the role of IL16 in OA and the possible mechanisms were examined. Methods We established a meniscal/ligament injury (MLI) post-traumatic OA model in Sprague Dawley rats and an IL1β-induced ADTC5 cells OA model. We detected the expression of IL16, novel-miR-81, MMP3, and MMP13 by quantitative real-time polymerase chain reaction. Western blot was performed to detect the expression of IL16, MMP3, and MMP13. The association between IL16 and novel-miR-81 was confirmed by luciferase reporter assay. Hematoxylin and eosin staining, Safranin O and Fast Green staining, and immunohistochemical staining were performed to clarify the effect of intra-articular injection of novel-miR-81 agomir in rats OA model. Results IL16 was upregulated in OA model. Knockdown of IL16 and overexpression of novel-miR-81 downregulated the expression of MMP3 and MMP13. Importantly, IL16 was a key target of novel-miR-81. Intra-articular injection of novel-miR-81 agomir could attenuate OA progression in rats OA model. Conclusion Novel-miR-81 targeted IL16 to relieve OA, suggesting that novel-miR-81and IL16 may be new therapeutic targets for OA.

Bone marrow mesenchymal stem cells (BMSCs) have the ability to differentiate into chondrocytes. In the differentiation of BMSCs into chondrocytes, micro-RNAs (miRNAs) play an important role. rno-miR-90 is a new miRNA discovered by our research team, and its role in chondrogenic differentiation of BMSCs is unknown. This study aimed to investigate whether rno-miR-90 could promote chondrogenic differentiation of BMSCs by regulating secreted protein acidic and rich in cysteine-related modular calcium binding 2 (Smoc2). First, BMSCs chondroblast differentiation was successfully induced in vitro by classical induction method of transforming growth factor (TGF)-β3. On this basis, we transfected rno-miR-90 mimic and inhibitor, and confirmed that rno-miR-90 mimic could promote the differentiation of BMSCs into chondrocytes by real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. In addition, we demonstrated that Smoc2 was a target gene of rno-miR-90 by dual-luciferase reporter assay, and confirmed that rno-miR-90 mimic could inhibit the expression of Smoc2 by RT-qPCR and western blotting. In order to further prove the targeting relationship between rno-miR-90 and Smoc2, we constructed three interfering fragments of Smoc2, and proved that silencing Smoc2 could promote the differentiation of BMSCs into chondrocytes at the transcriptional and protein levels. Finally, we constructed a carrier scaffold for ectopic chondrogenic differentiation in vivo, and confirmed that rno-miR-90 mimic and siSmoc2 could promote chondrogenic differentiation of BMSCs by Alcian blue staining and immunohistochemistry.