Exosomes from dysfunctional chondrocytes affect osteoarthritis in Sprague-Dawley rats through FTO-dependent regulation of PIK3R5 mRNA stability. Issue 9 (7th September 2022)

• Record Type: Journal Article
• Authors: Lv, Guohua; Wang, Bing; Li, Lei; Li, Yunchao; Li, Xinyi; He, Haoyu; Kuang, Lei
• Is Part Of: Bone & joint research. Volume 11:Issue 9(2022)
• Page Start: 652
• Page End: 668
• Publication Date: 2022-09-07
• Subjects: Osteoarthritis -- Dysfunctional chondrocyte-derived exosomes -- Long non-coding RNA OANCT -- PIK3R5 -- FTO -- Osteoarthritis (OA) -- chondrocytes -- mRNAs -- Sprague-Dawley rats -- macrophages -- rat modelling -- cartilage tissues -- RNAs -- autophagy -- western blot; Musculoskeletal system -- Periodicals; 573.705
• DOI: 10.1302/2046-3758.119.BJR-2021-0443.R2
• Languages: English
• ISSNs: 2046-3758

Abstract

Abstract : Aims: Exosomes (exo) are involved in the progression of osteoarthritis (OA). This study aimed to investigate the function of dysfunctional chondrocyte-derived exo (DC-exo) on OA in rats and rat macrophages. Methods: Rat-derived chondrocytes were isolated, and DCs induced with interleukin (IL)-1β were used for exo isolation. Rats with OA (n = 36) or macrophages were treated with DC-exo or phosphate-buffered saline (PBS). Macrophage polarization and autophagy, and degradation and chondrocyte activity of cartilage tissues, were examined. RNA sequencing was used to detect genes differentially expressed in DC-exo, followed by RNA pull-down and ribonucleoprotein immunoprecipitation (RIP). Long non-coding RNA osteoarthritis non-coding transcript (OANCT) and phosphoinositide-3-kinase regulatory subunit 5 (PIK3R5) were depleted in DC-exo-treated macrophages and OA rats, in order to observe macrophage polarization and cartilage degradation. The PI3K/AKT/mammalian target of rapamycin (mTOR) pathway activity in cells and tissues was measured using western blot. Results: DC-exo inhibited macrophage autophagy (p = 0.002) and promoted M1 macrophage polarization (p = 0.002). DC-exo at 20 μg/ml induced collagen degradation (p < 0.001) and inflammatory cell infiltration (p = 0.023) in rats. OANCT was elevated in DC (p < 0.001) and in cartilage tissues of OA patients (p < 0.001), and positively correlated with patients' Kellgren-Lawrence grade (p < 0.001). PIK3R5 was increased in DC-exo-treated cartilage tissues (p < 0.001), and OANCT bound to fat mass and obesity-associated protein (FTO) (p < 0.001). FTO bound to PIK3R5 (p < 0.001) to inhibit the stability of PIK3R5 messenger RNA (mRNA) (p < 0.001) and disrupt the PI3K/AKT/mTOR pathway (p < 0.001). Conclusion: Exosomal OANCT from DC could bind to FTO protein, thereby maintaining the mRNA stability of PIK3R5, further activating the PI3K/AKT/mTOR pathway to exacerbate OA. Cite this article: Bone Joint Res 2022;11(9):652–668.