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Mitochondrial function is impaired in osteoarthritis (OA) but its impact on cartilage catabolism is not fully understood. Here, we investigated the molecular mechanism of mitochondrial dysfunction-induced activation of catabolic response in chondrocytes. Using cartilage slices from normal and OA cartilage, we show that mitochondrial membrane potential was lower in OA cartilage which was associated with increased production of mitochondrial superoxide and catabolic genes (IL-6, COX-2, MMP-3,-9,-13 and ADAMTS5). Pharmacological induction of mitochondrial dysfunction in chondrocytes and cartilage explants using CCCP increased the mitochondrial superoxide production and the expression of IL-6, COX-2, MMP-3,-9-13 and ADAMTS5 and cartilage matrix degradation. Mitochondrial dysfunction induced expression of catabolic genes was dependent on JNK/AP1 pathway but not the NFκB pathway. Scavenging of mitochondrial superoxide with MitoTEMPO or pharmacological inhibition of JNK or cFos/cJun blocked the mitochondrial dysfunction-induced expression of the catabolic genes in chondrocytes. We demonstrate here that mitochondrial dysfunction contributes to OA pathogenesis via JNK/AP1 mediated expression of catabolic genes. Our data shows that AP1 could be used as a therapeutic target for OA management.

Objective. A retrospective cross-sectional analysis was conducted of the US Food and Drug Administration's MAUDE (Manufacturer and User Facility Device Experience) database, to evaluate the complication profile of cochlear implantation according to manufacturer. Methods. A review of the MAUDE database was conducted from 1 January 2010 to 31 December 2020. Complications, including infection, extrusion, facial nerve stimulation, meningitis and cerebrospinal fluid leak, were identified using key word searches. The categorised data were analysed using a chi-square test to determine a difference in global complication incidence between three major cochlear implant manufacturers: manufacturer A (Cochlear Limited), manufacturer B (Med-El) and manufacturer C (Advanced Bionics). Results. A total of 31 857 adverse events were analysed. Implants of manufacturer C were associated with a statistically higher rate of infection (0.97 per cent), cerebrospinal fluid leak (0.07 per cent), extrusion (0.44 per cent) and facial nerve stimulation (0.11 per cent). Implants of manufacturer B were associated with a statistically higher rate of meningitis (0.07 per cent). Conclusion. Consideration of patient risk factors along with cochlear implant manufacturers can heighten awareness of cochlear implant complications pre-operatively, intra-operatively and post-operatively.

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