Rat Model Of Monosodium Iodoacetate Research Articles

Evaluating the Anti-Osteoarthritis Potential of Standardized Boswellia serrata Gum Resin Extract in Alleviating Knee Joint Pathology and Inflammation in Osteoarthritis-Induced Models.

Osteoarthritis is a widespread chronic degenerative disease marked by the deterioration of articular cartilage, modifications in subchondral bone, and a spectrum of symptoms, including pain, stiffness, and disability. Ultimately, this condition impairs the patient's quality of life. This study aimed to evaluate the therapeutic efficacy of standardized Boswellia serrata gum resin extract (BSRE) in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis. A total of 60 rats were allocated into six groups: normal control group (NC), osteoarthritis control (injected with MIA, OC), O + B50 (injected with MIA and treated with 50 mg/kg body weight (BW) BSRE), O + B75 (injected with MIA and treated with 75 mg/kg BW BSRE), O + B100 (injected with MIA and treated with 100 mg/kg BW BSRE), and O + M (injected with MIA and treated with 150 mg/kg BW methyl sulfonyl methane). Several parameters, including knee joint swelling, histopathological changes, and the expression of collagen type II alpha 1 (COL2A1) and aggrecan, were comprehensively assessed. Concurrently, the serum levels and mRNA expression of inflammatory mediators, cytokines, and matrix metalloproteinases (MMPs) were analyzed in both the serum and knee joint synovium. The results demonstrated that BSRE significantly mitigated knee joint swelling, cartilage destruction, and tissue deformation. Notably, BSRE administration markedly upregulated the expression of COL2A1 and aggrecan while concurrently reducing levels of nitric oxide, prostaglandin E2, leukotriene B4, interleukin (IL)-6, and tumor necrosis factor (TNF)-α. Furthermore, a substantial decrease was observed in the mRNA expression of inducible nitric oxide synthase, cyclooxygenase-2, 5-lipoxygenase, IL-6, TNF-α and MMP-3 and -13, thereby indicating promising therapeutic implications for osteoarthritis. In conclusion, BSRE exhibited anti-inflammatory properties and inhibited cartilage matrix degradation in a rat model of MIA-induced osteoarthritis, with the O + B100 group showing significant reductions in swelling and notable improvements in joint cartilage damage. These findings illuminate the preventive and therapeutic potential of BSRE for osteoarthritis treatment, emphasizing the criticality of exhaustive evaluation of novel compounds.

Lipoxin A4 ameliorates knee osteoarthritis progression in rats by antagonizing ferroptosis through activation of the ESR2/LPAR3/Nrf2 axis in synovial fibroblast-like synoviocytes

BackgroundOur previous studies have shown that lipoxin A4 (LXA4) can serve as a potential biomarker for assessing the efficacy of exercise therapy in knee osteoarthritis (KOA), and fibroblast-like synoviocytes (FLSs) may play a crucial role in KOA pain as well as in the progression of the pathology. ObjectiveBy analyzing the GSE29746 dataset and collecting synovial samples from patients with different Kellgren–Lawrence (KL) grades for validation, we focused on exploring the potential effect of LXA4 on ferroptosis in FLSs through the ESR2/LPAR3/Nrf2 axis to alleviate pain and pathological advancement in KOA. MethodsThe association between FLSs ferroptosis and chondrocyte matrix degradation was explored by cell co-culture. We overexpressed and knocked down LPAR3 in vitro to explore its potential mechanism in FLSs. A rat model of monosodium iodoacetate (MIA)-induced KOA was constructed and intervened with moderate-intensity treadmill exercise and intraperitoneal injection of PHTPP to investigate the effects of the LXA4 intracellular receptor ESR2 on exercise therapy. ResultsESR2, LPAR3, and GPX4 levels in the synovium decreased with increasing KL grade. After LXA4 intervention in the co-culture system, GPX4, LPAR3, and ESR2 were upregulated in FLSs, collagen II was upregulated in chondrocytes, and MMP3 and ADAM9 were downregulated. LPAR3 overexpression upregulated the expression of GPX4, Nrf2, and SOD1 in FLSs, while downregulating the expression of MMP13 and MMP3; LPAR3 knockdown reversed these changes. Moderate-intensity platform training improved the behavioral manifestations of pain in KOA rats, whereas PHTPP treatment partially reversed the improvement in synovial and cartilage pathologies induced by platform training. ConclusionLXA4 inhibited FLSs ferroptosis by activating the ESR2/LPAR3/Nrf2 axis, thereby alleviating the pain and pathological progression of KOA. This study brings a new target for the treatment of KOA and also leads to a deeper understanding of the potential mechanisms of exercise therapy for KOA.

Integrated Analysis of DNA Methylation and Gene Expression Profiles in a Rat Model of Osteoarthritis.

Osteoarthritis (OA) is common and affected by several factors, such as age, weight, sex, and genetics. The pathogenesis of OA remains unclear. Therefore, using a rat model of monosodium iodoacetate (MIA)-induced OA, we examined genomic-wide DNA methylation using methyl-seq and characterized the transcriptome using RNA-seq in the articular cartilage tissue from a negative control (NC) and MIA-induced rats. We identified 170 genes (100 hypomethylated and upregulated genes and 70 hypermethylated and downregulated genes) regulated by DNA methylation in OA. DNA methylation-regulated genes were enriched in functions related to focal adhesion, extracellular matrix (ECM)-receptor interaction and the PI3K-Akt and Hippo signaling pathways. Functions related to extracellular matrix organization, extracellular matrix proteoglycans, and collagen formation were involved in OA. A molecular and protein-protein network was constructed using methylated expression-correlated genes. Erk1/2 was a downstream target of OA-induced changes in DNA methylation and RNA expression. We found that the integrin subunit alpha 2 (ITGA2) gene is important in focal adhesion, alpha6-beta4 integrin signaling, and the inflammatory response pathway in OA. Overall, gene expression changes because DNA methylation influences OA pathogenesis. ITGA2, whose gene expression changes are regulated by DNA methylation during OA onset, is a candidate gene. Our findings provide insights into the epigenetic targets of OA processes in rats.

Anti-arthritic effects of Schisandra chinensis extract in monosodium iodoacetate-induced osteoarthritis rats.

The present study aimed to investigate the therapeutic effects of Schisandra chinensis (SC) extract on clinical symptoms of osteoarthritis and the modulating effect on the mechanisms associated with the progression of osteoarthritis in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis. Osteoarthritis-induced rats were randomized into four groups: MIA injection control (MC), MIA injection with celecoxib (PC), MIA injection with SC extract 100mg/kg (SC100), and MIA injection with SC extract 200mg/kg (SC200). Another healthy group received a saline injection as a negative control (NC). During the treatment, weight-bearing measurements were performed once a week for 4 weeks. Histopathological and biochemical analyses of the joints, blood, and chondrocyte tissue were performed following the completion of treatment. Compared with MC rats, SC rats demonstrated significantly alleviated pain behavior, bone erosion, and cartilage degradation. SC reduced serum levels of matrix metalloproteinases and pro-inflammatory cytokines. SC treatment also reversed the levels of biomarkers such as Collagen II and ADAMTS4 in the cartilage tissue. Moreover, SC administration inhibited the phosphorylation levels of nuclear factor kappa B (NF-κB) and NF-κB Inhibitor alpha. This study demonstrates that SC ameliorated osteoarthritis at in vivo level. Our results suggest that SC might be a potential therapeutic agent for osteoarthritis.

Selective block of sensory neuronal T-type/Cav3.2 activity mitigates neuropathic pain behavior in a rat model of osteoarthritis pain

BackgroundPeripheral and central nociceptive sensitization is a critical pathogenetic component in osteoarthritis (OA) chronic pain. T-type calcium channel 3.2 (CaV3.2) regulates neuronal excitability and plays important roles in pain processing. We previously identified that enhanced T-type/CaV3.2 activity in the primary sensory neurons (PSNs) of dorsal root ganglia (DRG) is associated with neuropathic pain behavior in a rat model of monosodium iodoacetate (MIA)-induced knee OA. PSN-specific T-type/CaV3.2 may therefore represent an important mediator in OA painful neuropathy. Here, we test the hypothesis that the T-type/CaV3.2 channels in PSNs can be rationally targeted for pain relief in MIA-OA.MethodsMIA model of knee OA was induced in male and female rats by a single injection of 2 mg MIA into intra-knee articular cavity. Two weeks after induction of knee MIA-OA pain, recombinant adeno-associated viruses (AAV)-encoding potent CaV3.2 inhibitory peptide aptamer 2 (CaV3.2iPA2) that have been characterized in our previous study were delivered into the ipsilateral lumbar 4/5 DRG. Effectiveness of DRG-CaV3.2iPA2 treatment on evoked (mechanical and thermal) and spontaneous (conditioned place preference) pain behavior, as well as weight-bearing asymmetry measured by Incapacitance tester, in the arthritic limbs of MIA rats were evaluated. AAV-mediated transgene expression in DRG was determined by immunohistochemistry.ResultsAAV-mediated expression of CaV3.2iPA2 selective in the DRG-PSNs produced significant and comparable mitigations of evoked and spontaneous pain behavior, as well as normalization of weight-bearing asymmetry in both male and female MIA-OA rats. Analgesia of DRG-AAV-CaV3.2iPA1, another potent CaV3.2 inhibitory peptide, was also observed. Whole-cell current-clamp recordings showed that AAV-mediated CaV3.2iPA2 expression normalized hyperexcitability of the PSNs dissociated from the DRG of MIA animals, suggesting that CaV3.2iPA2 attenuated pain behavior by reversing MIA-induced neuronal hyperexcitability.ConclusionsTogether, our results add therapeutic support that T-type/CaV3.2 in primary sensory pathways contributes to MIA-OA pain pathogenesis and that CaV3.2iPAs are promising analgesic leads that, combined with AAV-targeted delivery in anatomically segmental sensory ganglia, have the potential for further development as a peripheral selective T-type/CaV3.2-targeting strategy in mitigating chronic MIA-OA pain behavior. Validation of the therapeutic potential of this strategy in other OA models may be valuable in future study.

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.

Effects of Dipsacus asperoides Extract on Monosodium Iodoacetate-Induced Osteoarthritis in Rats Based on Gene Expression Profiling.

The root of Dipsacus asperoides C. Y. Cheng et T. M. Ai is traditionally used as an analgesic and anti-inflammatory agent to treat pain, rheumatoid arthritis, and bone fractures. However, neither its effects on osteoarthritis (OA) nor its effects on the arthritic cartilage tissue transcriptome have not been fully investigated. In this study, we used a rat model of monosodium iodoacetate- (MIA-) induced OA to investigate the therapeutic effects of a Dipsacus asperoides ethanolic extract (DAE, 200 mg/kg for 21 days). The study first assessed joint diameter, micro-CT scans, and histopathological analysis and then conducted gene expression profiling using RNA sequencing in articular cartilage tissue. We found that DAE treatment ameliorates OA disease phenotypes; it reduced the knee joint diameter and prevented changes in the structural and histological features of the joint, thereby showing that DAE has a protective effect against OA. Based on the results of gene expression profiling and subsequent pathway analysis, we found that several canonical pathways were linked to DAE treatment, including WNT/β-catenin signaling. Taken together, the present results suggest molecular mechanism, involving gene expression changes, by which DAE has a protective effect in a rat model of MIA-induced OA.

Antarctic Krill Oil Ameliorates Monosodium Iodoacetate-Induced Irregularities in Articular Cartilage and Inflammatory Response in the Rat Models of Osteoarthritis.

The aim of this study was to examine the effects of Antarctic krill oil (FJH-KO) in a rat model of monosodium iodoacetate (MIA) induced osteoarthritis. The effect of FJH-KO on the development and severity of MIA-induced osteoarthritis was assessed using hematoxylin and eosin (H&E) staining and micro-CT. The expression of PGE2, pro-inflammatory cytokines (IL-1β, TNF-α), and arthritics related genes in osteoarthritic rats in response to FJH-KO supplementation was investigated using real time PCR. FJH-KO supplementation in the arthritic rat model reduced tissue damage, cartilage degeneration, and reduced the MIA-induced irregularities in articular cartilage surface. Serum PGE2, IL-1β, IL-6, and TNF-α levels were higher in MIA treated animals, but these levels decreased upon FJH-KO supplementation. When FJH-KO was provided at a dose of 150 mg/kg b.w to MIA-treated animals, it significantly increased the mRNA expression of anabolic factors. The mRNA expression of catabolic factors was significantly decreased MIA-treated animals that were provided FJH-KO at a dose of 100 and 150 mg/kg b.w. Moreover, the mRNA expression of inflammatory mediators was significantly decreased MIA-treated animals supplemented with FJH-KO. These results suggest supplementation with FJH-KO ameliorates the irregularities in articular cartilage surface and improves the inflammatory response in the osteoarthritis. Thus, FJH-KO could serve as a potential therapeutic agent for osteoarthritis treatment.

ALGX‐XC20, a Novel Transient Receptor Potential Ankyrin 1 (TRPA1) Antagonist Attenuates Joint Pain and Articular Cartilage Damage in an Osteoarthritis Rat Model

Currently, there are no approved disease‐modifying drugs for osteoarthritis (OA). OA patients depend upon analgesic drugs such as nonsteroidal anti‐inflammatory drugs (NSAIDs) and opioid analgesics for pain management. Despite existing therapies, pain relief in OA remains largely inadequate. Recently, the functional role for TRPA1 receptor‐channels which are expressed on nociceptor sensory nerves and other non‐neuronal cells within the joint has been identified, although studies of the role of TRPA1 in the pathogenesis of OA pain are limited. TRPA1 represents a promising target for the development of novel therapeutic agent for managing OA pain. This study investigated the effects of ALGX‐XC20, a highly selective and potent TRPA1 antagonist with a long in‐vivo half‐life on pain behaviors and cartilage damage in a rat model of monosodium iodoacetate (MIA)‐induced OA. The analgesic effect of a single dose (30 mg/kg; oral) of ALGX‐XC20 was evaluated for a period of 14 days post‐OA induction and compared to celecoxib (30 mg/kg; oral), a selective cyclooxygenase‐2 (COX‐2) inhibitor by using pain‐related behavior assessments, including hindlimb weight distribution and von Frey tests. The histological scoring of cartilage damage was also determined according to the Mankin grading system. The MIA‐induced OA rat group displayed a large reduction in the weight bearing distribution on the ipsilateral hindlimb (p<0.01–0.05) and hind paw mechanical withdrawal thresholds compared to saline control group, which was maintained for 14 days. The MIA‐evoked reduction in weight bearing distribution was significantly reversed (~50%) in the MIA‐induced group treated with ALGX‐XC20 compared to the MIA‐treated group for the 2‐week duration, while the antiallodynic effect of ALGX‐XC20 was less pronounced. In addition, histopathology studies showed that ALGX‐XC20 was also effective in reducing the severe cartilage damage in the MIA‐injected knee joint as shown by a significant improvement in the Mankin score in the ALGX‐XC20 treated group at 14 days (p<0.05). The magnitude of the effect on spontaneous weight bearing behavior due to ALGX‐XC20 treatment is closely comparable to the effects observed for the MIA‐celecoxib group and reported for TRPA1‐KO animals. The positive analgesic effects in this OA model due to pharmacological inhibition of TRPA1 by ALGX‐XC20 occur without any adverse behavioral effects. These in vivo data suggest that ALGX‐XC20 may be used as a novel therapeutic analgesic/anti‐inflammatory drug for the treatment of chronic arthritis, such as OA pain. This TRPA1 antagonist drug may also represent a new class of disease‐modifying drug by providing a chondroprotective effect on articular cartilage.

Alterations of autophagy in knee cartilage by treatment with treadmill exercise in a rat osteoarthritis model.

The aim of the present study was to investigate potential alterations in the articular cartilage in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis (OA) with or without treatment with moderate treadmill exercise. A total of 30 male Sprague-Dawley rats were randomly divided into three groups (n=10), including the control, OA and OA with treadmill exercise (OAE) groups. Rats were evaluated upon completing the treadmill exercise program (speed, 18 m/min; 30 min/day; 5 days/week for 4 weeks). Interleukin (IL)-1β and IL-4 levels in the serum and intra-articular lavage fluid (IALF) were measured by ELISA. Alterations in articular cartilage and synovium were also evaluated by histology, immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction. The results revealed that IL-1β in the serum and IALF decreased in the OAE group, whereas IL-4 increased, and histological evaluation indicated that the OAE group had a clear treatment response. However, the expression of type II collagen in the articular cartilage increased in the OAE group as compared with the OA group, whereas ADAMTS5 expression decreased. In contrast to light chain 3B (LC3B), the protein expression levels of BECLIN1 and sequestosome 1 (SQSTM1) were increased in the OA group. In addition, a significant increase was observed between OA and OAE groups in LC3B and SQSTM1 protein levels, whereas no change was observed in BECLIN1 levels between the OA and OAE groups in the superficial and deep zones. The results of western blotting demonstrated that LC3II was notably decreased in the OA group and partially increased in the OAE group. The mRNA expression levels of LC3B and SQSTM1 increased in the OA and OAE groups, with a significant difference observed between the two groups, while a concomitant decrease was detected in BECLIN1 levels. In conclusion, 30 min of treadmill exercise had an evident protective effect in the articular cartilage of rats with MIA-induced OA and may promote autophagy in the articular cartilage.

The therapeutic effects of lipoxin A4 during treadmill exercise on monosodium iodoacetate-induced osteoarthritis in rats

Lipoxin A4 (LXA4), a kind of adipokines, is a potent stop signal of inflammation. Our preliminary study found that LXA4 of serum and intra-articular lavage fluid (IALF) was rapidly elevated in 2 h and rapidly reduced to normal level at 4 h after moderate-intensity treadmill exercise. The aim was to confirm the therapeutic effects of LXA4 during treadmill exercise on rat model of monosodium iodoacetate (MIA)-induced OA and the detailed mechanism of LXA4 on OA. One hundred and twenty-four male Sprague-Dawley rats were submitted to two different protocols. A single session of treadmill exercise: sixty-four rats were randomly divided into treadmill exercise of different intensities for 60 min only once (n = 4). Formal treadmill exercise: sixty rats were randomly divided into six groups (n = 10): control group (CG), knee OA group (OAG), OA with treadmill exercise of different intensities (OAL, OAM and OAH), and OAM + BOC-2 (an antagonist of LXA4 receptor). The rats were evaluated by ELISA, histology, immunohistochemistry and western blotting. Fibroblast-like synoviocytes (FLSs) were obtained from knee joint of rats. The effects of LXA4 on interleukin (IL)-1β induced FLSs were evaluated by western blotting and immunofluorescence. The results of ELISA, histological evaluation, western blotting and immunohistochemistry indicated that OAM had a better treatment which could be suppressed by BOC-2. Moreover, LXA4 could attenuate the expression of matrix metalloproteinase (MMP)-3 and MMP-13 and suppress the expression of nuclear factor-kappa B (NF-κB) p65 induced by IL-1β in FLSs. The therapeutic effects of LXA4 during treadmill exercise on MIA-induced OA via inhibiting NF-κB signaling pathway.

Attenuation of inflammation and cartilage degradation by sulfasalazine-containing hyaluronic acid on osteoarthritis rat model

The aim of this study was to investigate the effects of a sulfasalazine-containing hyaluronic acid (SASP/HA) systems on in vitro anti-inflammation and the alleviation of cartilage degradation in both lipopolysaccharide (LPS)-stimulated synoviocytes and a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis (OA). The SASP/HA resulted in long-term release of SASP from the SASP/HA for up to 60 days in a sustained manner. In vitro studies performed using real-time polymerase chain reaction (PCR) assay revealed that the SASP/HA was able to effectively and dose-dependently inhibit the mRNA expression levels of pro-inflammatory cytokines such as matrix metalloproteinases-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in LPS-stimulated synoviocytes. In vivo studies showed that intra articular injection of SASP/HA greatly reduced the MIA-stimulated mRNA expression of MMP-3, COX-2, IL-6, and TNF-α in blood. Furthermore, these significant anti-inflammatory effects of SASP/HA contributed markedly to the alleviation of progression of MIA-induced OA and cartilage degradation, as demonstrated by X-ray, micro-computed tomography (micro-CT), gross findings, and histological evaluations. Therefore, our findings indicated that the long-term and sustained delivery of SASP using HA can play a therapeutic role in alleviating inflammation as well as protecting against cartilage damage in OA.

Prevention of articular cartilage degeneration in a rat model of monosodium iodoacetate induced osteoarthritis by oral treatment with Withaferin A

Withaferin A (WFA), a highly oxygenated withanolide is used for anti-osteoporotic, fracture healing, obesity control as medicine and dietary supplement in Ayurveda and Unani medicine but its potential remains to be investigate for the osteoarthritis studies. In the present study, chondro-protective effects of WFA, under in vitro and in vivo conditions were evaluated. In-vitro pharmacological activity of WFA was tested on rat articular chondrocytes through MTT, DPPH, different staining, FACS and translation studies. In-vivo studies of WFA were evaluated through monosodium iodoacetate (MIA) induced osteoarthritis studies. DPPH assay, alcian blue and toluidine blue staining indicated the chondrogenic potential of WFA. Similarly, WFA enhance chondrogenesis through up-regulation of SOX9 protein. In addition, WFA reduced the ROS generation, mitochondrial depolarization and apoptosis induced by inflammatory cytokines IL-1β and TNF-α. Furthermore, WFA treatment in MIA treated rats alleviated cartilage erosion and improvement in sub-chondral bone micro-architecture by decrease in Tissue volume (∼32%), and trabecular bone pattern factor (∼28%). Taken together, our study provides convincing evidence for the candidature of WFA (10 mg kg−1 day−1) as a potential agent for the treatment of cartilage degenerative diseases like osteoarthritis.

Antiosteoarthritic Effects of ChondroT in a Rat Model of Monosodium Iodoacetate-Induced Osteoarthritis.

Ganghwaljetongyeum is a traditional Korean herbal medicine used to treat joint pain, limited motion, fever, and swelling; it also inhibits inflammatory processes associated with arthritis. ChondroT, a water extract of Ganghwaljetongyeum, is a new complex herbal medicine. This study investigated the effects of ChondroT using a rat model of monosodium iodoacetate- (MIA-) induced osteoarthritis. Thirty-six rats were randomly divided into three ChondroT groups and a normal, control, and positive control group. Changes in paw edema volume, histopathology, and plantar withdrawal response were analyzed. Further, inflammatory cytokines, arachidonic acids, liver and kidney function, and hematological features were measured. ChondroT significantly decreased paw edema by the 5th day and notably improved articular cartilage damage; it also significantly improved the plantar withdrawal response in terms of both reaction time and force intensity. Moreover, treatment with ChondroT significantly decreased the serum levels of tumor necrosis factor alpha, interleukin-1β, interleukin-6, and prostaglandin E2 and significantly increased serum aspartate aminotransferase and alanine aminotransferase levels. This study demonstrates that ChondroT has anti-inflammatory and analgesic effects in a MIA-induced osteoarthritis rat model. These results support the clinical relevance of ChondroT for future use in patients with osteoarthritis. However, further studies are required to elucidate the corresponding mechanisms.

Suppressive Effect of the n-Hexane Extract of Litsea japonica Fruit Flesh on Monosodium-Iodoacetate-Induced Osteoarthritis in Rats.

We examined the antiosteoarthritic effect of the n-hexane extract of Litsea japonica fruit flesh (LJF-HE) in a rat model of monosodium-iodoacetate- (MIA-) induced osteoarthritis. LJF-HE significantly reduced the difference in weight-bearing capabilities of the hind paws between healthy and MIA-treated rats. Histological examination of the knee joints indicated that LJF-HE suppressed cartilage and bone destruction. Additionally, there were decreases in the expression of matrix metalloproteinase-2 and metalloproteinase-9 and cyclooxygenase-2 in the joints. The serum levels of deoxypyridinoline (DPD) and osteocalcin, which are markers of bone metabolism, also decreased. Furthermore, LJF-HE significantly suppressed infiltration of inflammatory cells into the synovium and inhibited the expression of proinflammatory cytokines such as tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1, and IL-6 in the joints and serum. The serum levels of leukotriene B4 and lipoxygenase were also significantly lowered by LJF-HE. Finally, LJF-HE inhibited the production of nitric oxide, prostaglandin E2, IL-6, and TNF-α in lipopolysaccharide-activated macrophages, which might be associated with inhibited phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase. Our data suggest that LJF-HE has an anti-inflammatory effect and may have potential as an antiosteoarthritic agent.

Adelmidrol, in combination with hyaluronic acid, displays increased anti-inflammatory and analgesic effects against monosodium iodoacetate-induced osteoarthritis in rats.

BackgroundOsteoarthritis (OA) is a degenerative joint disease produced by a cascade of events that can ultimately lead to joint damage. The aim of this study was to evaluate the effect of adelmidrol, a synthetic palmitoylethanolamide analogue, combined with hyaluronic acid on pain severity and modulation of the inflammatory response in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis.MethodsOA was induced by intra-articular injection of MIA in the knee joint. On day 21 post-MIA administration, the knee joint was analyzed. Rats subjected to OA were treated by intra-articular injection of adelmidrol in combination with sodium hyaluronate at different doses and time points after MIA induction. Limb nociception was assessed by the paw withdrawal latency and threshold measurement. Samples were examined macroscopically, histologically, and by immunohistochemistry.ResultsAt day 21 post-MIA injection, the MIA + solvent and MIA + 1.0% sodium hyaluronate groups showed irregularities and fibrillation in the surface layer, a decrease in blood cells and multilayering in transition and radial zones, no pannus formation, and modified Mankin scores significantly higher than sham knees. The combination of hyaluronic acid and adelmidrol dose-dependently (adelmidrol 0.6% + 1.0% sodium hyaluronate and adelmidrol 2% + 1.0% sodium hyaluronate) reduced the histological alterations induced by MIA. Moreover, degeneration of articular cartilage, mast cell infiltration, and pro-inflammatory cytokine and chemokine plasma levels were significantly downregulated by treatment with a combination of hyaluronic acid and adelmidrol at the above doses.ConclusionsOur results clearly demonstrate that the combination of hyaluronic acid and adelmidrol improves the signs of OA induced by MIA.

Abstract 465: Lipid-lowering Agent Gemcabene Down-regulates Acute Phase C-reactiveProtein via /EBP-δ-mediated Transcriptional Mechanism and Attenuates Inflammation and Osteoarthritis in Animal Models

Background: Inflammation plays a key role in setting the stage as well as causing the progression of atherosclerosis. High sensitivity c-reactive protein (hsCRP), an acute phase reactant released during inflammatory processes, has been recognized as a predictor of cardiovascular risk. Experiments & Results: Since gemcabene reduced hsCRP in humans, we investigated the mechanism of hsCRP reduction and efficacy of anti-inflammatory activity in animal models of arthritis and pain. In human hepatoma cell line, PLC/PRF/5, gemcabene showed dose-dependent inhibition of IL-6+ IL-1β-induced CRP production by -70% inhibition at 2 mM. In TNF-α-stimulated primary human coronary artery endothelial cells, both CRP and IL-6 productions were inhibited by gemcabene in a dose-dependent manner (-70% at 2mM). Transfection studies with human CRP regulatory sequences in luciferase/ β-gal system showed a 25-fold increase in IL-6- as well as IL-6+ IL-1β -stimulated CRP transcription, which was reduced by gemcabene (-50% at 2 mM), suggesting transcriptional down-regulation of CRP. Site-directed mutation of C/EBP, NF-κB, and STAT sites of the human CRP promoter suggested that the overlapping downstream C/EBP and NF-κB binding sites are important for gemcabene-mediated down-regulation of CRP promoter. STAT3 response element, while needed for IL-6-induced expression of CRP, is not required for gemcabene-mediated inhibition. Identification of the protein, in a gel-shift assay, that interacts with C/EBP binding sites revealed it to be C/EBPδ. Anti-inflammatory efficacy of gemcabene was evaluated in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis (OA) and carrageenan-induced thermal hyperalgesia (CITH). Gemcabene improved joint comfort (-50% at 30 mg/kg/d for 2 wk) in MIA and attenuated paw withdrawal latency (60% at 30 mg/kg/d and 97% at 100 mg/kg/d, compared to untreated control) in the CITH model. These findings were further confirmed by an IL-6/IL-6sR knee injection model showing 63 and 71% reduction in hind paw weight distribution at 10 and 30 mg/kg/d doses, respectively. Conclusions: Gemcabene decreases CRP by C/EBPδ and NF-κB mediated transcriptional mechanism, and attenuates inflammation-induced OA and hyperalgesia.

Electrophysiological evidence for voltage-gated calcium channel 2 (Cav2) modulation of mechano- and thermosensitive spinal neuronal responses in a rat model of osteoarthritis

Osteoarthritis (OA) remains one of the greatest healthcare burdens in western society, with chronic debilitating pain-dominating clinical presentation yet therapeutic strategies are inadequate in many patients. Development of better analgesics is contingent on improved understanding of the molecular mechanisms mediating OA pain. Voltage-gated calcium channels 2.2 (Cav2.2) play a critical role in spinal nociceptive transmission, therefore blocking Cav2.2 activity represents an attractive opportunity for OA pain treatment, but the only available licensed Cav2.2 antagonist ziconitide (PrilatTM) is of limited use. TROX-1 is an orally available, use dependent and state-selective Cav2 antagonist, exerting its analgesic effect primarily via Cav2.2 blockade, with an improved therapeutic window compared with ziconitide. Using a rat model of monosodium iodoacetate (MIA), 2mg, induced OA we used in vivo electrophysiology to assess the effects of spinal or systemic administration of TROX-1 on the evoked activity of wide dynamic range spinal dorsal horn neurons in response to electrical, natural mechanical (dynamic brush and von Frey 2, 8, 26 and 6g) and thermal (40, 45 and 45°C) stimuli applied to the peripheral receptive field.MIA injection into the knee joint resulted in mechanical hypersensitivity of the ipsilateral hind paw and weight-bearing asymmetry. Spinal administration of TROX-1 (0.1 and 1μg/50μl) produced a significant dose-related inhibition of dynamic brush, mechanical (von Frey filament (vF) 8, 26 and 60g) and noxious thermal-(45 and 48°C) evoked neuronal responses in MIA rats only. Systemic administration of TROX-1 produced a significant inhibition of the mechanical-(vF 8, 26 and 60g) evoked neuronal responses in MIA rats. TROX-1 did not produce any significant effect on any neuronal measure in Sham controls. Our in vivo electrophysiological results demonstrate a pathological state-dependent effect of TROX-1, which suggests an increased functional role of Cav2, likely Cav2.2, channels in mediating OA pain.

Osteoarthritis-dependent changes in antinociceptive action of Nav1.7 and Nav1.8 sodium channel blockers: An in vivo electrophysiological study in the rat

Voltage-gated sodium channel blockers are not traditionally recommended for osteoarthritis (OA) pain therapy, but given the large peripheral drive that follows OA development there is a rationale for their use. Using a rat model of monosodium iodoacetate (MIA)-induced OA we used in vivo electrophysiology to assess the effects of the Nav1.7- and Nav1.8-selective antagonists, ProTxII and A-803467 respectively, on the evoked activity of spinal dorsal horn neurons in response to electrical, mechanical and thermal stimuli applied to the peripheral receptive field. These studies allow examination of the roles of these channels in suprathreshold stimuli, not amenable to behavioral threshold measures. Spinal administration of ProTxII significantly reduced neuronal responses evoked by mechanical punctate (von Frey (vF) 8–60g) and noxious thermal (45 and 48°C) stimuli in MIA rats only. A-803467 significantly inhibited neuronal responses evoked by vF 8–60g and 48°C heat after spinal administration; significantly inhibited responses evoked by brush, vFs 26–60g and 40–48°C stimuli after systemic administration; significantly inhibited the electrically evoked Aδ-, C-fiber, post-discharge, Input and wind-up responses and the brush, vFs 8–60g and 45–48°C evoked neuronal responses after intra plantar injection in the MIA group. In comparison A-803467 effects in the sham group were minimal and included a reduction of the neuronal response evoked by vF 60g and 45°C heat stimulation after spinal administration, no effect after systemic administration and an inhibition of the evoked response to 45°C heat after intra plantar injection only. The observed selective inhibitory effect of ProTxII and A-803467 for the MIA-treated group suggests an increased role of Nav1.7 and 1.8 within nociceptive pathways in the arthritic condition, located at peripheral and central sites. These findings demonstrate the importance of, and add to, the mechanistic understanding of these channels in osteoarthritic pain.

Epidemiologic and etiologic approach of osteoarthritis

The aim of this study was to investigate the effects of a sulfasalazine-containing hyaluronic acid (SASP/HA) systems on in vitro anti-inflammation and the alleviation of cartilage degradation in both lipopolysaccharide (LPS)-stimulated synoviocytes and a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis (OA). The SASP/HA resulted in long-term release of SASP from the SASP/HA for up to 60 days in a sustained manner. In vitro studies performed using real-time polymerase chain reaction (PCR) assay revealed that the SASP/HA was able to effectively and dose-dependently inhibit the mRNA expression levels of pro-inflammatory cytokines such as matrix metalloproteinases-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in LPS-stimulated synoviocytes. In vivo studies showed that intra articular injection of SASP/HA greatly reduced the MIA-stimulated mRNA expression of MMP-3, COX-2, IL-6, and TNF-α in blood. Furthermore, these significant anti-inflammatory effects of SASP/HA contributed markedly to the alleviation of progression of MIA-induced OA and cartilage degradation, as demonstrated by X-ray, micro-computed tomography (micro-CT), gross findings, and histological evaluations. Therefore, our findings indicated that the long-term and sustained delivery of SASP using HA can play a therapeutic role in alleviating inflammation as well as protecting against cartilage damage in OA.