TY - JOUR AB - Fibrotic changes in the infrapatellar fat pad (IFP) are involved in the pathogenesis of knee osteoarthritis (KOA). HIF‑1α is a transcription factor that is activated during hypoxia and is suggested to play a role in fibrosis in various organs. However, its participation in the fibrotic changes in IFP remains unclear. Therefore, we investigated the role of HIF‑1α in IFP fibrosis using a carrageenan‑induced KOA rat model and evaluated the potential of low‑intensity pulsed ultrasound (LIPUS) as a novel treatment for KOA. A rat model was prepared by intra‑articular injection of 0.5% carrageenan (50 µl) using 8‑week‑old male Wistar rats. Fibrosis of the IFP was evaluated histologically by hematoxylin and eosin and Sirius Red staining at 1 and 2 weeks after intra‑articular injection. The mRNA expression levels of HIF‑1α and fibrosis‑related molecules, CTGF and VEGF, were analyzed using reverse transcription‑quantitative PCR, and the DNA binding activity of HIF‑1α was assessed using a binding assay. In addition, the effect of irradiation with LIPUS on the fibrosis of IFP was verified. Histological studies demonstrated a significant increase in the fibrosis of IFP 1 and 2 weeks after intra‑articular injection of carrageenan, accompanied by overexpression of CTGF and VEGF, which was followed by upregulation of transcriptional activation of HIF‑1α. Moreover, intervention with LIPUS for 2 weeks after injection of carrageenan attenuated fibrosis of IFP, accompanied by a significant reduction in the transcriptional activation of HIF‑1α and decreased the gene expression levels of HIF‑1α, CTGF, and VEGF. The present study demonstrated that activation of HIF‑1α promoted fibrosis of IFP in carrageenan‑induced arthritis in rats and that intervention with LIPUS decreased the activity of HIF‑1α and inhibited fibrosis. These results suggest that LIPUS may serve as a novel approach for the treatment of KOA, through its modulation of HIF‑1α. AD - Graduate School of Health Sciences, Morinomiya University of Medical Sciences, Suminoe‑ku, Osaka 559‑8611, Japan AU - Kitagawa,Takashi AU - Kawahata,Hirohisa AU - Aoki,Motokuni AU - Kudo,Shintarou DA - 2022/10/01 DO - 10.3892/br.2022.1562 IS - 4 JO - Biomed Rep KW - infrapatellar fat pad knee osteoarthritis fibrosis HIF‑1α low‑intensity pulsed ultrasound PY - 2022 SN - 2049-9434 2049-9442 SP - 79 ST - Inhibitory effect of low‑intensity pulsed ultrasound on the fibrosis of the infrapatellar fat pad through the regulation of HIF‑1α in a carrageenan‑induced knee osteoarthritis rat model T2 - Biomedical Reports TI - Inhibitory effect of low‑intensity pulsed ultrasound on the fibrosis of the infrapatellar fat pad through the regulation of HIF‑1α in a carrageenan‑induced knee osteoarthritis rat model UR - https://doi.org/10.3892/br.2022.1562 VL - 17 ER -