Study on the mechanism of action of different synovial cell-derived inflammatory exosomes on chondrocytes after lipopolysaccharide intervention / 安徽医科大学学报

Objective To observe the effect of different synovial cell secretions on chondrocytes after LPS-induced inflammation,and to explore the mechanism of two synovial cell secretions causing cartilage damage in the progres-sion of KOA disease.Methods Two kinds of synovial cells were co-cultured at 1∶4 and LPS-induced inflamma-tion.The supernatant and exocrine were extracted,and then the normal and LPS-induced inflammation were extrac-ted.The human cartilage tissue obtained during the operation was isolated and cultured into chondrocytes,which were divided into five groups:the first group was added with FLS secretion,the second group was added with nor-mal FLS secretion,the third group was added with secretion after co-culture of two kinds of synovial cells,the fourth group was added with inflammatory MLS secretion,and the fifth group was added with inflammatory FLS se-cretion.CCK-8 was used to detect the viability of chondrocytes in each group.TNF-α,IL-1β,IL-6 level in the su-pernatant of chondrocytes in each group was detected by ELISA.The protein expression of TLR4,NF-κB,IkK,IκB,ADAMTS5 in chondrocytes of each group was detected by Western blot method.Results CCK-8 showed that the activity of chondrocytes in the three groups of inflammatory secretions decreased compared with the secretions from normal synovial cells(P＜0.05);ELISA showed TNF-α,IL-1 β,IL-6 level in the supernatant of group Ⅲ,Ⅳ and V was higher than that of group Ⅰ and Ⅱ(P＜0.05),TNF-α,IL-1 β,IL-6 level in group Ⅲ was higher than that in group Ⅳ but lower than that in group Ⅴ(P＜0.05).Western blot showed the protein expression of TLR4,NF-κB,IkK,IκB,ADAMTS5 in chondrocytes of group Ⅲ,Ⅳ and Ⅴ was higher than that in group Ⅰ and Ⅱ(P＜0.05),the protein expression of TLR4,NF-κB,IkK,IκB,ADAMTS5 in group Ⅲ was higher than that in group Ⅳbut lower than that in group Ⅴ(P＜0.05).Conclusion Two kinds of synovial cell-derived secretions after LPS-induced inflammation can regulate cartilage TLRs/NF-κB signal pathway,causing cartilage inflammation.The in-flammatory effect of MLS secretion is stronger than that of FLS secretion,but the inflammatory effect of MLS secre-tion under two co-cultures is weaker than that of MLS secretion alone.

Expression of cannabinoid (CB1 and CB2) and cannabinoid-related receptors (TRPV1, GPR55, and PPARα) in the synovial membrane of the horse metacarpophalangeal joint.

Background: The metacarpophalangeal joint undergoes enormous loading during locomotion and can therefore often become inflamed, potentially resulting in osteoarthritis (OA). There are studies indicating that the endocannabinoid system (ECS) modulates synovium homeostasis, and could be a promising target for OA therapy. Some cannabinoid receptors, which modulate proliferative and secretory responses in joint inflammation, have been functionally identified in human and animal synovial cells. Objective: To characterize the cellular distribution of the cannabinoid receptors 1 (CB1R) and 2 (CB2R), and the cannabinoid-related receptors transient receptor potential vanilloid type 1 (TRPV1), G protein-related receptor 55 (GPR55) and peroxisome proliferator-activated receptor alpha (PPARα) in the synovial membrane of the metacarpophalangeal joint of the horse. Animals: The dorsal synovial membranes of 14 equine metacarpophalangeal joints were collected post-mortem from an abattoir. Materials and methods: The dorsal synovial membranes of 14 equine metacarpophalangeal joints were collected post-mortem from an abattoir. The expression of the CB1R, CB2R, TRPV1, GPR55, and PPARα in synovial tissues was studied using qualitative and quantitative immunofluorescence, and quantitative real-time reverse transcriptase PCR (qRT-PCR). Macrophage-like (MLS) and fibroblast-like (FLS) synoviocytes were identified by means of antibodies directed against IBA1 and vimentin, respectively. Results: Both the mRNA and protein expression of the CB2R, TRPV1, GPR55, and PPARα were found in the synoviocytes and blood vessels of the metacarpophalangeal joints. The synoviocytes expressed the mRNA and protein of the CB1R in some of the horses investigated, but not in all. Conclusions and clinical importance: Given the expression of the CB1R, CB2R, TRPV1, GPR55, and PPARα in the synovial elements of the metacarpophalangeal joint, these findings encouraged the development of new studies supporting the use of molecules acting on these receptors to reduce the inflammation during joint inflammation in the horse.

Potential role of mitochondria in synoviocytes.

Synoviocytes are located in the synovium lining layer, which is composed of macrophage-like synoviocytes (MLS) and fibroblast-like synoviocytes (FLS) with different characteristics. Mitochondria, which exist in most cells, are two membrane-covered organelles. In addition to providing the necessary ATP for synoviocytes, mitochondria are involved in the regulation of redox homeostasis and the integration of synoviocytes death signals. In recent years, mitochondrial dysfunction has been found in rheumatoid arthritis (RA) and osteoarthritis (OA). Interestingly, recent studies have started uncovering that mitochondria that were previously reported to play a role in chondrocytes or immune cells, but not known to have pronounced roles in synoviocytes, can actually play crucial roles in the regulation of the pathological properties of the synoviocytes. The purpose of this review is to summarize our current understanding of the key role of mitochondria in synoviocytes, including mitochondrial dysfunction in synoviocytes can induce and aggravate inflammatory responses and changes in mitochondrial structure and function with the involvement of multiple cytokines, signal pathway, and hypoxic state of synovial tissue alter the response of synoviocytes to apoptotic stimulation. Also, mitochondrial abnormalities in synoviocytes promote the synoviocytes invasion and proliferation.

Ontology and Function of Fibroblast-Like and Macrophage-Like Synoviocytes: How Do They Talk to Each Other and Can They Be Targeted for Rheumatoid Arthritis Therapy?

Fibroblast-like synoviocytes (FLS) and macrophage-like synoviocytes (MLS) are the two main cellular components of the synovium. It has been widely reported that FLS and MLS play essential roles in the joint pathology of rheumatoid arthritis (RA). Although various studies have analyzed both human and animal tissues and have shown that both cell types are involved in different stages of RA, ontology, and specific functions of both cell populations and their interactions are not well understood. In this review, we will summarize recent research on FLS and MLS in RA and focus on the development and function of two predominant synovial cell types. In addition, we will discuss the communication between FLS or MLS and highlight potential treatments for RA that involve synoviocytes.