Intra-articular Injection of Chloramphenicol Reduces Articular Cartilage Degeneration in a Rabbit Model of Osteoarthritis

Review of Intra-Articular Use of Antibiotics and Antiseptic Irrigation and Their Systematic Association with Chondrolysis

Introduction

Intra-articular antibiotics have been proposed as a treatment for septic arthritis to allow for high local concentrations without subjecting a patient to the toxicity/side effects of systemic therapy. However, there is concern for chondrotoxicity with intra-articular use of these solutions in high concentrations. The purpose of this systematic review was to evaluate the intra-articular use of antibiotics and antiseptic solutions, and to determine their association with chondrolysis following in vitro or in vivo administration.

Methods

A systematic review was conducted following PRISMA guidelines through PubMed, Clinical Key, OVID, and Google Scholar. Studies in English were included if they evaluated for chondrotoxicity following antibiotic exposure.

Results

The initial search resulted in 228 studies, with 36 studies meeting criteria. These 36 studies included manuscripts that studied 24 different agents. Overall, 7 of the 24 (29%) agents were non-chondrotoxic: minocycline, tetracycline, chloramphenicol, teicoplanin, pefloxacin, linezolid, polymyxin-bacitracin. Eight (33%) agents had inconsistent results: doxycycline, ceftriaxone, gentamicin, vancomycin, ciprofloxacin, ofloxacin, chlorhexidine, and povidone iodine. Chondrotoxicity was evident with 9 (38%) agents, all of which were also dose-dependent chondrotoxic based on reported estimated half maximal inhibitory concentrations (est. IC50): amikacin (est. IC50 = 0.31-2.74 mg/mL), neomycin (0.82), cefazolin (1.67-3.95), ceftazidime (3.16-3.59), ampicillin-sulbactam (8.64 - >25), penicillin (11.61), amoxicillin (14.01), imipenem (>25), and tobramycin (>25). Additionally, chondroprotective effects of doxycycline and minocycline were reported.

Conclusions

This systematic review identified agents that may be used in the treatment of septic arthritis. Nine agents should be avoided due to their dose-dependent chondrotoxic effects. Further studies are needed to clarify the safety of these medications for human intra-articular use.

Intra-articular injection of clioquinol ameliorates osteoarthritis in a rabbit model

Osteoarthritis (OA) is characterized by the degeneration of articular cartilage. Decreased autophagy is tightly associated with chondrocyte death, which contributes to the progression of OA. Thus, pharmacological activation of autophagy may be a promising therapeutic approach for OA. Here, we discovered that clioquinol, an antibiotic, significantly induces autophagy in OA chondrocytes from human tissue and rabbit model. Meanwhile, clioquinol can also augment the expression of extracellular matrix (ECM) components and suppress inflammatory mediators to improve OA microenvironment. Intra-articular injection of clioquinol can greatly prevent or slow down the development of this disease in a trauma-induced rabbit model of osteoarthritis. Such protective effect induced by clioquinol was at least in part explained by decreasing chondrocyte apoptosis and increasing autophagy. This study reveals the therapeutic potential of clioquinol in OA treatment.

Exosomes Immunity Strategy: A Novel Approach for Ameliorating Intervertebral Disc Degeneration

Low back pain (LBP), which is one of the most severe medical and social problems globally, has affected nearly 80% of the population worldwide, and intervertebral disc degeneration (IDD) is a common musculoskeletal disorder that happens to be the primary trigger of LBP. The pathology of IDD is based on the impaired homeostasis of catabolism and anabolism in the extracellular matrix (ECM), uncontrolled activation of immunologic cascades, dysfunction, and loss of nucleus pulposus (NP) cells in addition to dynamic cellular and biochemical alterations in the microenvironment of intervertebral disc (IVD). Currently, the main therapeutic approach regarding IDD is surgical intervention, but it could not considerably cure IDD. Exosomes, extracellular vesicles with a diameter of 30–150 nm, are secreted by various kinds of cell types like stem cells, tumor cells, immune cells, and endothelial cells; the lipid bilayer of the exosomes protects them from ribonuclease degradation and helps improve their biological efficiency in recipient cells. Increasing lines of evidence have reported the promising applications of exosomes in immunological diseases, and regarded exosomes as a potential therapeutic source for IDD. This review focuses on clarifying novel therapies based on exosomes derived from different cell sources and the essential roles of exosomes in regulating IDD, especially the immunologic strategy.

Autophagy-activated nucleus pulposus cells deliver exosomal miR-27a to prevent extracellular matrix degradation by targeting MMP-13

Although autophagy may be beneficial for maintaining the metabolic balance of the extracellular matrix (ECM) in the nucleus pulposus (NP) and its vitality under inflammation, the underlying mechanism still remains unclear. A previous study found that autophagy activation stimulated the release of exosomes in normal chondrocytes, which are located in a similar avascular environment and share many common features with those of nucleus pulposus cells (NPCs). This study explored the protective effect on matrix degradation in the NP by exosomes derived from autophagy-activated NPCs and exosomal microRNAs. NPCs-derived exosomes (NPCs-Exos) were isolated from culture medium of either normal NPCs or rapamycin-treated NPCs and quantified by nanoparticle tracking analysis. The effect of rapamycin-treated NPC-derived exosomes on NPCs were assessed by coculture with interleukin 1β (IL-1β)-stimulated NPCs. After examination of six major proteinases of the ECM, matrix metalloproteinase 13 (MMP-13) was chosen for further study. miR-27a, which targets MMP-13, was investigated through previous studies and bioinformatics tool. The levels of miR-27a were upregulated in both rapamycin-treated NPCs and their exosomes, compared to the control. When exosomal miR-27a was transferred into NPCs, it alleviated IL-1β-induced degradation of the NPC ECM by targeting MMP-13. Autophagy activation may promote the release of NPCs-derived exosomes and thereby prevent the NPC matrix from degradation. Autophagy activation also alleviates intervertebral disc degeneration (IDD), at least partly via exosomal miR-27a, which restrains MMP-13 expression under IL-1β stimulation. Our work elucidates a new mechanism for how autophagy may participate in preventing IDD, which may be a promising therapeutic strategy.

Rapamycin-Induced Autophagy Promotes the Chondrogenic Differentiation of Synovium-Derived Mesenchymal Stem Cells in the Temporomandibular Joint in Response to IL-1β

Cartilage defects in temporomandibular disorders (TMD) lead to chronic pain and seldom heal. Synovium-derived mesenchymal stem cells (SMSCs) exhibit superior chondrogenesis and have become promising seed cells for cartilage tissue engineering. However, local inflammatory conditions that affect the repair of articular cartilage by SMSCs present a challenge, and the specific mechanism through which the function remains unclear. Thus, it is important to explore the chondrogenesis of SMSCs under inflammatory conditions of TMD such that they can be used more effectively in clinical treatment. In this study, we obtained SMSCs from TMD patients with severe cartilage injuries. In response to stimulation with IL-1β, which is well known as one of the most prevalent cytokines in TMD, MMP13 expression increased, while that of SOX9, aggrecan, and collagen II decreased during chondrogenic differentiation. At the same time, IL-1β upregulated the expression of mTOR and decreased the ratio of LC3-II/LC3-I and the formation of autophagosomes. Further study revealed that rapamycin pretreatment promoted the migration of SMSCs and the expression of chondrogenesis-related markers in the presence of IL-1β by inducing autophagy. 3-Benzyl-5-((2-nitrophenoxy)methyl)-dihydrofuran-2(3H)-one (3BDO), a new activator of mTOR, inhibited autophagy and increased the expression of p-GSK3βser9 and β-catenin, simulating the effect of IL-1β stimulation. Furthermore, rapamycin reduced the expression of mTOR, whereas the promotion of LC3-II/LC3-I was blocked by the GSK3β inhibitor TWS119. Taken together, these results indicate that rapamycin enhances the chondrogenesis of SMSCs by inducing autophagy, and GSK3β may be an important regulator in the process of rapamycin-induced autophagy. Thus, inducing autophagy may be a useful approach in the chondrogenic differentiation of SMSCs in the inflammatory microenvironment and may represent a novel TMD treatment.