Zuoqing Zhou1,2, Su'an Tang3,4, Xiaoyu Nie1,5, Yiqun Zhang2, Delong Li1,5, Yang Zhao1,5, Yumei Cao1, Jianwen Yin2, Tianyu Chen1,6, Guangfeng Ruan1, Zhaohua Zhu1, Xiaochun Bai7, Weiyu Han1,5, Changhai Ding8,9,10. 1. Clinical Research Centre, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. 2. Department of Orthopedics, The First Affiliated Hospital, Shaoyang University, Shaoyang, Hunan, China. 3. Clinical Research Centre, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. tangsan@mail2.sysu.edu.cn. 4. Centre of Orthopedics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. tangsan@mail2.sysu.edu.cn. 5. Centre of Orthopedics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. 6. Department of Orthopedics, The Third Affiliated Hospital, Southern Medical University, Guangzhou, Guangdong, China. 7. Guangdong Provincial Key Laboratory of Bone and Joint Degenerative Diseases, Guangzhou, Guangdong, China. 8. Clinical Research Centre, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. changhai.ding@utas.edu.au. 9. Guangdong Provincial Key Laboratory of Bone and Joint Degenerative Diseases, Guangzhou, Guangdong, China. changhai.ding@utas.edu.au. 10. Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia. changhai.ding@utas.edu.au.
Abstract
OBJECTIVE: This study aimed to investigate the biochemical effects of osteoarthritic infrapatellar fat pad (IPFP) on cartilage and the underlying mechanisms. METHODS: Human IPFP and articular cartilage were collected from end-stage osteoarthritis (OA) patients during total knee arthroplasty. IPFP-derived fat-conditioned medium (FCM) was used to stimulate human primary chondrocytes and cartilage explants. Functional effect of osteoarthritic IPFP was explored in human primary chondrocytes and articular cartilage in vitro and ex vivo. Activation of relative pathways and its effects on chondrocytes were assessed through immunoblotting and inhibition experiments, respectively. Neutralization test was performed to identify the main factors and their associated pathways responsible for the effects of IPFP. RESULTS: Osteoarthritic IPFP-derived FCM significantly induced extracellular matrix (ECM) degradation in both human primary chondrocytes and cartilage explants. Several pathways, such as NF-κB, mTORC1, p38MAPK, JNK, and ERK1/2 signaling, were significantly activated in human chondrocytes with osteoarthritic IPFP-derived FCM stimulation. Interestingly, inhibition of p38MAPK and ERK1/2 signaling pathway could alleviate the detrimental effects of FCM on chondrocytes, while inhibition of other signaling pathways had no similar results. In addition, IL-1β and TNF-α instead of IL-6 in osteoarthritic IPFP-derived FCM played key roles in cartilage degradation via activating p38MAPK rather than ERK1/2 signaling pathway. CONCLUSION: Osteoarthritic IPFP induces the degradation and inflammation of cartilage via activation of p38MAPK and ERK1/2 pathways, in which IL-1β and TNF-α act as the key factors. Our study suggests that modulating the effects of IPFP on cartilage may be a promising strategy for knee OA intervention.
OBJECTIVE: This study aimed to investigate the biochemical effects of osteoarthritic infrapatellar fat pad (IPFP) on cartilage and the underlying mechanisms. METHODS: Human IPFP and articular cartilage were collected from end-stage osteoarthritis (OA) patients during total knee arthroplasty. IPFP-derived fat-conditioned medium (FCM) was used to stimulate human primary chondrocytes and cartilage explants. Functional effect of osteoarthritic IPFP was explored in human primary chondrocytes and articular cartilage in vitro and ex vivo. Activation of relative pathways and its effects on chondrocytes were assessed through immunoblotting and inhibition experiments, respectively. Neutralization test was performed to identify the main factors and their associated pathways responsible for the effects of IPFP. RESULTS: Osteoarthritic IPFP-derived FCM significantly induced extracellular matrix (ECM) degradation in both human primary chondrocytes and cartilage explants. Several pathways, such as NF-κB, mTORC1, p38MAPK, JNK, and ERK1/2 signaling, were significantly activated in human chondrocytes with osteoarthritic IPFP-derived FCM stimulation. Interestingly, inhibition of p38MAPK and ERK1/2 signaling pathway could alleviate the detrimental effects of FCM on chondrocytes, while inhibition of other signaling pathways had no similar results. In addition, IL-1β and TNF-α instead of IL-6 in osteoarthritic IPFP-derived FCM played key roles in cartilage degradation via activating p38MAPK rather than ERK1/2 signaling pathway. CONCLUSION: Osteoarthritic IPFP induces the degradation and inflammation of cartilage via activation of p38MAPK and ERK1/2 pathways, in which IL-1β and TNF-α act as the key factors. Our study suggests that modulating the effects of IPFP on cartilage may be a promising strategy for knee OA intervention.
Authors: Katrin Agnes Muenzebrock; Valerie Kersten; Jacqueline Alblas; Joao Pedro Garcia; Laura B Creemers Journal: Front Bioeng Biotechnol Date: 2022-03-03