Objective: Iron overload is common in elderly people which is associated with an increased prevalence of osteoarthritis (OA), but the exact role of iron in the development of OA has not been established. The aim of the present study is to elucidate the connection between iron overload and OA using an iron overloaded mice model, as well as to explore the role of iron homeostasis, iron transporters dependent iron influx in OA pathogenesis.Methods: The iron overloaded mice model was established and OA was surgically induced. OA progression was assessed at 8 weeks after surgery. Next, primary chondrocytes were treated with pro-inflammatory cytokines and iron regulators mediated iron homeostasis were evaluated. Involvement of iron transporters was analyzed using chondrocytes mimicking an osteoarthritis-related phenotype in vitro.Results: Iron overloaded mice exhibited greater cartilage destruction and elevated ADAMTS5 as well as MMP13 expression along with increased iron accumulation and dysregulated iron regulators. Pro-inflammatory cytokines could disturb cellular iron homeostasis via upregulating iron import proteins, TFR1 and DMT1, downregulating iron efflux protein FPN, thus result in cellular iron overload. Among iron transporters, DMT1 was found to play pivotal roles in iron overload induced OA progress. Inhibition of DMT1 suppressed IL-1β induced inflammatory response and ECM degradation via blockade of MAPK and PI3K/AKT/NF-κB pathways.Conclusions: Our results suggest that iron takes parts in the development of OA and cutting iron influx via inhibiting DMT1 activity could be an attractive new target for OA treatment.
Iron overload is common in elderly people which is implicated in the disease progression of osteoarthritis (OA), however, how iron homeostasis is regulated during the onset and progression of OA and how it contributes to the pathological transition of articular chondrocytes remain unknown. In the present study, we developed an in vitro approach to investigate the roles of iron homeostasis and iron overload mediated oxidative stress in chondrocytes under an inflammatory environment. We found that pro‐inflammatory cytokines could disrupt chondrocytes iron homeostasis via upregulating iron influx transporter TfR1 and downregulating iron efflux transporter FPN, thus leading to chondrocytes iron overload. Iron overload would promote the expression of chondrocytes catabolic markers, MMP3 and MMP13 expression. In addition, we found that oxidative stress and mitochondrial dysfunction played important roles in iron overload‐induced cartilage degeneration, reducing iron concentration using iron chelator or antioxidant drugs could inhibit iron overload‐induced OA‐related catabolic markers and mitochondrial dysfunction. Our results suggest that pro‐inflammatory cytokines could disrupt chondrocytes iron homeostasis and promote iron influx, iron overload‐induced oxidative stress and mitochondrial dysfunction play important roles in iron overload‐induced cartilage degeneration.
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