Pretreatment with mechano growth factor E peptide attenuates osteoarthritis through improving cell proliferation and extracellular matrix synthesis in chondrocytes under severe hypoxia.

Osteoarthritis (OA) is characterized by pain and declining gait function associated with degeneration of cartilage. A severe hypoxic environment occurs due to tissue injury in the joint cavity and may aggravate the development of OA. In this study, the effects of severe hypoxia and treatment with mechano growth factor (MGF) E peptide on metabolism of the extracellular matrix (ECM) during the progression of OA were determined. The results showed that cell viability, cell proliferation, and type II collagen expression in chondrocytes were significantly inhibited by cobalt chloride (CoCl2)-simulated severe hypoxia, whereas cell apoptosis and expression levels of hypoxia inducible factor 1 alpha, type I collagen, and matrix metalloproteinases 1/13 were clearly induced. Pretreatment with MGF E peptide reduced the abovementioned adverse effects induced by CoCl2-simulated severe hypoxia in chondrocytes. Pretreatment also upregulated the proliferation of chondrocytes under severe hypoxia through the PI3K-Akt and MEK-ERK1/2 signaling pathways. In a rat model of monosodium iodoacetate (MIA)-induced OA. MIA treatment induced tissue necrosis and cartilage degeneration, and histological score was significantly decreased. The levels of type II collagen and aggrecan were reduced after MIA treatment for 4 or 6 weeks, and abnormal distribution of ECM occurred in the inner epicondyle after 6 weeks. MGF E peptide also reduced the progression of MIA-induced OA by retarding cartilage degeneration, upregulating type II collagen synthesis, and improving ECM distribution after 4 or 6 weeks. Our findings suggest that MGF attenuates the progression of OA, and thus may be applied for the treatment of OA in the clinic.

Inhibition effect of Caragana sinica root extracts on Osteoarthritis through MAPKs, NF-κB signaling pathway.

Osteoarthritis (OA) is a common joint disease characterized by degradation and inflammation of cartilage extracellular matrix. We aimed to evaluate the protective effect of Caragana sinica root (CSR) on interleukin (IL)-1ß-stimulated rat chondrocytes and a monosodium iodoacetate (MIA)-induced model of OA. In vitro, cell viability of CSR-treated chondrocytes was measured by MTT assay. The mRNA expression of Matrix metallopeptidases (MMPs), a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) and extracellular matrix (ECM) were analyzed by quantitative real-time PCR (qRT-PCR). Moreover, the protein expression of MAPK (phosphorylation of EKR, JNK, p38), inhibitory kappa B (IκBα) and nuclear factor-kappa B (NF-κB p65) was detected by western blot analysis. In vivo, the production of nitric oxide (NO) was detected by Griess reagent, while those of inflammatory mediators, MMPs and ECM were detected by ELISA. The degree of OA was evaluated by histopathological analyses, Osteoarthritis Research Society International (OARSI) score and micro-CT analysis. CSR significantly inhibited the expression of MMPs, ADAMTSs and the degradation of ECM in IL-1ß-stimulated chondrocytes. Furthermore, CSR significantly suppressed IL-1ß-stimulated of MAPKs, NF-κB signaling pathway. In vivo, CSR and Indomethacin inhibited the production of inflammatory mediators, MMPs and degradation of ECM in MIA-induced model of OA. In addition, CSR improved the severity of OA. Taken together, these results suggest CSR is a potential therapeutic active agent in the treatment of OA.

Laser irradiation activates spinal adenosine A1 receptor to alleviate osteoarthritis pain in monosodium iodoacetate injected rats.

The analgesic role of the adenosine A1 receptor is thought to involve the modulation of the spinal N-methyl D-aspartate receptor-mediated nociceptive pathway, which is suggested to be an underlying mechanism in chronic pain. Knee osteoarthritis is a degenerative condition accompanied by chronic pain. We have demonstrated that 10.6-µm laser irradiation has an antinociceptive effect in the monosodium iodoacetate -induced knee osteoarthritis in rats. However, its mechanism of action has yet to be explored. In the present work, we investigate the mechanism of 10.6-µm laser irradiation mediated antinociception in the monosodium iodoacetate -induced knee osteoarthritis. Results showed that the 10.6-µm laser significantly reversed the monosodium iodoacetate -induced nociceptive behaviors for up to 28 days. Moreover, the up-regulation of the A1 receptor and the down-regulated phosphorylation of the N-methyl D-aspartate receptor 1 subunit of the N-methyl D-aspartate receptor were observed in the spinal cord dorsal horn in the monosodium iodoacetate injected rats treated by laser irradiation. Intrathecal injection of 8-cyclopentyl-1,3-dipropylxanthine markedly reversed the effects of laser irradiation, as evidenced both by behavioral pain tests and by levels of spinal phosphorylation of N-methyl D-aspartate receptor 1. These results suggest that the spinal A1 receptor contributes to the antinociceptive effects of 10.6-µm laser, at least in part by inhibiting phosphorylation of N-methyl D-aspartate receptor 1 in the monosodium iodoacetate -induced knee osteoarthritis pain.

Reduction of osteoarthritis severity in the temporomandibular joint of rabbits treated with chondroitin sulfate and glucosamine.

Osteoarthritis is a degenerative disease that causes substantial changes in joint tissues, such as cartilage degeneration and subchondral bone sclerosis. Chondroitin sulfate and glucosamine are commonly used products for the symptomatic treatment of osteoarthritis. The aim of the present study was to investigate the effects of these products when used as structure-modifying drugs on the progression of osteoarthritis in the rabbit temporomandibular joint. Thirty-six New Zealand rabbits were divided into 3 groups (n = 12/group): control (no disease); osteoarthritis (disease induction); and treatment (disease induction and administration of chondroitin sulfate and glucosamine). Osteoarthritis was induced by intra-articular injection of monosodium iodoacetate. Animals were killed at 30 and 90 days after initiation of therapy. The treatment was effective in reducing disease severity, with late effects and changes in the concentration of glycosaminoglycans in the articular disc. The results indicate that chondroitin sulfate and glucosamine may have a structure-modifying effect on the tissues of rabbit temporomandibular joints altered by osteoarthritis.

Protectin DX attenuates IL-1ß-induced inflammation via the AMPK/NF-κB pathway in chondrocytes and ameliorates osteoarthritis progression in a rat model.

Protectin DX (PDX) has been reported to have extensive anti-inflammatory effects. However, it is unknown whether PDX acts as an anti-inflammatory agent in the context of osteoarthritis (OA). This study aimed to evaluate the anti-inflammatory activity of PDX in vitro and in vivo in a model of OA. Primary rat chondrocytes were preincubated with PDX 1 h prior to IL-1ß treatment for 24 h. We found that PDX was nontoxic, and pretreatment with PDX increased cell viability in IL-1ß-induced chondrocytes. Preincubation with PDX also efficiently inhibited the degradation of type II collagen dose-dependently. Additionally, the expression of MMP-3, MMP-13, ADAMTS4, iNOS, COX-2, NO, and PGE2 decreased after IL-1ß stimulation when cells were preincubated with PDX. Moreover, PDX inhibited the increase in phosphorylated NF-κB p65 and IκBα upon IL-1ß stimulation, and the negative effects of IL-1ß on chondrocytes were partially blocked by treatment with pyrrolidine dithiocarbamate (PDTC), a selective NF-κB inhibitor. In addition, we found that PDX increased AMPK phosphorylation in IL-1ß-mediated chondrocytes. The phosphorylation of AMPK could be inhibited by compound C, a classic AMPK inhibitor. Compound C also remarkably reversed the decrease in p65 phosphorylation and MMP-13 expression caused by PDX. Furthermore, nuclear translocation of NF-κB was visible by immunofluorescence after PDX-induced AMPK activation. Additionally, we verified that PDX ameliorated cartilage degradation in monosodium iodoacetate (MIA)-induced OA rats through histological evaluation and ELISA of TNF-α in the serum and intra-articular lavage fluid. In conclusion, we have shown that PDX suppresses inflammation in chondrocytes in vitro and in vivo, likely through the AMPK/NF-κB signaling pathway. Our results suggest that PDX could be a useful novel therapeutic agent for OA treatment.

A rat model of knee osteoarthritis suitable for electroacupuncture study.

Acupuncture is widely used for knee osteoarthritis (KOA) treatment in clinical practice. In the present study, we aimed to set a standard KOA animal model for electroacupuncture (EA) study and provide an acupuncture recipe for further KOA studies. Rats intra-articularly administered monosodium iodoacetate (MIA, 0.3, 1 or 3 mg respectively, n=12 each) were evaluated for pain-like behavior: paw withdrawal mechanical threshold, weight bearing deficit, and joint pathological changes (OARSI score) until 28 days after injury. Then by using the suitable dose (1 mg MIA), therapeutic effects of EA treatment (bilateral ST36 and ST35 acupoints, 2/10 Hz, 30 min/d, 6d/w, 2w) were evaluated in 3 groups (n=16 each): Early-on EA, Mid-term EA and Delayed EA, in which EA was started on day 1, day 7 or day 14 after MIA injection. Both 1 mg and 3 mg MIA induced significant joint damage and persistent pain behavior. But animals accepted 3 mg MIA rapidly developed cartilage and bone damage within 14 days. Early-on EA treatment provided significant pain relief and joint structure preservation in KOA rats. Mid-term EA treatment only reduced pain, while delayed EA treatment resulted in no effects in both aspects. 1 mg of MIA produces steady pain behavior and progressive joint damage, which was suitable for EA treatment evaluation. Early-on EA treatment provided both joint protection and pain reduction, while Mid-term EA could only be used for studying EA-induced analgesia in KOA.

Role of TrkA signalling and mast cells in the initiation of osteoarthritis pain in the monoiodoacetate model.

OBJECTIVE: Aiming to delineate novel neuro-immune mechanisms for NGF/TrkA signalling in osteoarthritis (OA) pain, we evaluated inflammatory changes in the knee joints following injection of monoiodoacetate (MIA) in mice carrying a TrkA receptor mutation (P782S; TrkA KI mice). METHOD: In behavioural studies we monitored mechanical hypersensitivity following intra-articular MIA and oral prostaglandin D2 (PGD2) synthase inhibitor treatments. In immunohistochemical studies we quantified joint mast cell numbers, calcitonin gene-related peptide expression in synovia and dorsal root ganglia, spinal cord neuron activation and microgliosis. We quantified joint leukocyte infiltration by flow cytometry analysis, and PGD2 generation and cyclooxygenase-2 (COX-2) expression in mast cell lines by ELISA and Western blot. RESULTS: In TrkA KI mice we observed rapid development of mechanical hypersensitivity and amplification of dorsal horn neurons and microglia activation 7 days after MIA. In TrkA KI knee joints we detected significant leukocyte infiltration and mast cells located in the vicinity of synovial nociceptive fibres. We demonstrated that mast cells exposure to NGF results in up-regulation of COX-2 and increase of PGD2 production. Finally, we observed that a PGD2 synthase inhibitor prevented MIA-mechanical hypersensitivity in TrkA KI, at doses which were ineffective in wild type (WT) mice. CONCLUSION: Using the TrkA KI mouse model, we delineated a novel neuro-immune pathway and suggest that NGF-induced production of PGD2 in joint mast cells is critical for referred mechanical hypersensitivity in OA, probably through the activation of PGD2 receptor 1 in nociceptors: TrkA blockade in mast cells constitutes a potential target for OA pain.

Pulsed electromagnetic field at different stages of knee osteoarthritis in rats induced by low-dose monosodium iodoacetate: Effect on subchondral trabecular bone microarchitecture and cartilage degradation.

The aim of the study was to investigate the efficacy of pre-emptive, early, and delayed pulsed electromagnetic field (PEMF) treatment on cartilage and subchondral trabecular bone in knee osteoarthritis (OA) rats induced by low-dose monosodium iodoacetate (MIA). Seventy-five 12-week-old male Sprague-Dawley rats were assigned to five groups: OA (n = 30), pre-emptive PEMF (n = 10), early PEMF (n = 10), delayed PEMF (n = 10), and control (n = 15). Osteoarthritis was induced by injecting 0.2 mg MIA in rat's right knee joint. Control rats received a single sterile saline injection in the right knee. Male rats received pre-emptive (n = 10, day 0-end of week 4), early (n = 10, end of week 4-end of week 8), or delayed (n = 10, end of week 8-end of week 12) PEMF treatment (75 Hz, 1.6 mT). After 4, 8, and 12 weeks, rats were sacrificed at each time point and right knees were harvested. After sacrifice, micro-computed tomography, histology, and biomarker analyses were performed. We found pre-emptive PEMF treatment preserved subchondral trabecular bone microarchitecture and prevented subchondral bone loss in MIA-induced OA rat model. Early and delayed PEMF treatment maintained subchondral trabeculae. PEMF treatment increased bone and cartilage formation, and decreased bone and cartilage resorption. Pre-emptive and early PEMF treatment had moderate effects on cartilage degradation. Time point of treatment initiation is crucial for treating OA. PEMF might become a potential biophysical treatment modality for osteoarthritis. Bioelectromagnetics. 38:227-238, 2017. © 2016 Wiley Periodicals, Inc.