Alleviating Effects of AS1892802, a Rho Kinase Inhibitor, on Osteoarthritic Disorders in Rodents

FGF18 encoding circular mRNA-LNP based on glycerolipid engineering of mesenchymal stem cells for efficient amelioration of osteoarthritis

Mesenchymal stem cells (MSCs) exhibit substantial potential for osteoarthritis (OA) therapy through cartilage regeneration, yet the realization of optimal therapeutic outcomes is hampered by their limited intrinsic reparative capacities. Herein, MSCs are engineered with circular mRNA (cmRNA) encoding fibroblast growth factor 18 (FGF18) encapsulated within lipid nanoparticles (LNP) derived from a glycerolipid to facilitate OA healing. A proprietary biodegradable and ionizable glycerolipid, TG6A, with branched tails and five ester bonds, forms LNP exhibiting above 9-fold and 41-fold higher EGFP protein expression in MSCs than commercial LNP from DLin-MC3-DMA and ALC-0315, respectively. The introduction of FGF18 not only augmented the proliferative capacity of MSCs but also upregulated the expression of chondrogenic genes and glycosaminoglycan (GAG) content. Additionally, FGF18 enhanced the production of proteoglycans and type II collagen in chondrocyte pellet cultures in a three-dimensional culture. In an OA rat model, transplantation with FGF18-engineered MSCs remarkably preserved cartilage integrity and facilitated functional repair of cartilage lesions, as evidenced by thicker cartilage layers, reduced histopathological scores, maintenance of zone structure, and incremental type II collagen and extracellular matrix (ECM) deposition. Taken together, our findings suggest that TG6A-based LNP loading with cmRNA for engineering MSCs present an innovative strategy to overcome the current limitations in OA treatment.

A novel anti-NGF PEGylated Fab' provides analgesia with lower risk of adverse effects

Nerve growth factor (NGF) has emerged as a key driver of pain perception in several chronic pain conditions, including osteoarthritis (OA), and plays an important role in the generation and survival of neurons. Although anti-NGF antibodies improve pain control and physical function in patients with clinical chronic pain conditions, anti-NGF IgGs are associated with safety concerns such as effects on fetal and postnatal development and the risk of rapidly progressive osteoarthritis. To overcome these drawbacks, we generated a novel anti-NGF PEGylated Fab' antibody. The anti-NGF PEGylated Fab' showed specific binding to and biological inhibitory activity against NGF, and analgesic effects in adjuvant-induced arthritis model mice in a similar manner to an anti-NGF IgG. In collagen-induced arthritis model mice, the anti-NGF PEGylated Fab' showed higher accumulation in inflamed foot pads than the anti-NGF IgG. In pregnant rats and non-human primates, the anti-NGF PEGylated Fab' was undetectable in fetuses, while the anti-NGF IgG was detected and caused abnormal postnatal development. The PEGylated Fab' and IgG also differed in their ability to form immune complexes in vitro. Additionally, while both PEGylated Fab' and IgG showed analgesic effects in sodium monoiodoacetate-induced arthritic model rats, their effects on edema were surprisingly quite different. While the anti-NGF IgG promoted edema over time, the anti-NGF PEGylated Fab' did not. The anti-NGF PEGylated Fab' (ASP6294) may thus be a potential therapeutic candidate with lower risk of adverse effects for various diseases in which NGF is involved such as OA and chronic back pain.

Electroacupuncture activated local sympathetic noradrenergic signaling to relieve synovitis and referred pain behaviors in knee osteoarthritis rats

Introduction

Recent research has focused on the local control of articular inflammation through neuronal stimulation to avoid the systemic side effects of conventional pharmacological therapies. Electroacupuncture (EA) has been proven to be useful for inflammation suppressing and pain reduction in knee osteoarthritis (KOA) patients, yet its mechanism remains unclear.

Methods

In the present study, the KOA model was established using the intra-articular injection of sodium monoiodoacetate (MIA) (1 mg/50 μL) into the knee cavity. EA was delivered at the ipsilateral ST36-GB34 acupoints. Hind paw weight-bearing and withdrawl thresholds were measured. On day 9, the histology, dep enrichment proteins, cytokines contents, immune cell population of the synovial membrane of the affected limbs were measured using HE staining, Masson staining, DIA quantitative proteomic analysis, flow cytometry, immunofluorescence staining, ELISA, and Western Blot. The ultrastructure of the saphenous nerve of the affected limb was observed using transmission electron microscopy on the 14th day after modeling.

Results

The result demonstrated that EA intervention during the midterm phase of the articular inflammation alleviated inflammatory pain behaviors and cartilage damage, but not during the early phase. Mid-term EA suppressed the levels of proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the synovium on day 9 after MIA by elevating the level of sympathetic neurotransmitters Norepinephrine (NE) in the synovium but not systemic NE or systemic adrenaline. Selective blocking of the sympathetic function (6-OHDA) and β2-adrenergic receptor (ICI 118,551) prevented the anti-inflammatory effects of EA. EA-induced increment of the NE in the synovium inhibited the CXCL1-CXCR2 dependent overexpression of IL-6 in the synovial macrophages in a β2-adrenergic receptor (AR)-mediated manner.

Discussion

These results revealed that EA activated sympathetic noradrenergic signaling to control local inflammation in KOA rats and contributed to the development of novel therapeutic neurostimulation strategies for inflammatory diseases.

A Pilot Analysis of Genome-Wide DNA Methylation Patterns in Mouse Cartilage Reveals Overlapping Epigenetic Signatures of Aging and Osteoarthritis

OBJECTIVE

Cartilage epigenetic changes are strongly associated with human osteoarthritis (OA). However, the influence of individual environmental OA risk factors on these epigenetic patterns has not been determined; herein we characterize cartilage DNA methylation patterns associated with aging and OA in a mouse model.

METHODS

Murine knee cartilage DNA was extracted from healthy young (16-week, n = 6), old (82-week, n = 6), and young 4-week post-destabilization of the medial meniscus (DMM) OA (n = 6) C57BL6/J mice. Genome-wide DNA methylation patterns were determined via Illumina BeadChip. Gene set enrichment analysis was performed by Ingenuity Pathway Analysis. The top seven most differentially methylated positions (DMPs) were confirmed by pyrosequencing in an independent animal set. Results were compared to previously published human OA methylation data.

RESULTS

Aging was associated with 20,940 DMPs, whereas OA was associated with 761 DMPs. Merging these two conditions revealed 279 shared DMPs. All demonstrated similar directionality and magnitude of change (Δβ 1.0% ± 0.2%, mean methylation change ± SEM). Shared DMPs were enriched in OA-associated pathways, including RhoA signaling (P = 1.57 × 10^-4 ), protein kinase A signaling (P = 3.38 × 10^-4 ), and NFAT signaling (P = 6.14 × 10^-4 ). Upstream regulators, including TET3 (P = 6.15 × 10^-4 ), immunoglobulin (P = 6.14 × 10^-4 ), and TLR7 (P = 7.53 × 10^-4 ), were also enriched. Pyrosequencing confirmed six of the seven top DMPs in an independent cohort.

CONCLUSION

Aging and early OA following DMM surgery induce similar DNA methylation changes within a murine OA model, suggesting that aging may induce pro-OA epigenetic "poising" within articular cartilage. Future research should focus on confirming and expanding these findings to other environmental OA risk factors, including obesity, as well as determining late OA changes in mice.

Anti-Osteoarthritic Effects of a Mixture of Dried Pomegranate Concentrate Powder, Eucommiae Cortex, and Achyranthis Radix 5:4:1 (g/g) in a Surgically Induced Osteoarthritic Rabbit Model

In this study, we aimed to determine the synergistic effects of a formula consisting of dried pomegranate concentrate powder, Eucommiae Cortex, and Achyranthis Radix 5:4:1 (g/g) (PCP:EC:AR) in a surgically induced osteoarthritis (OA) rabbit model. PCP:EC:AR was orally administered once per day. Knee thickness, maximum extension of the knee joint, gross articular defect area, and the histopathological appearance of the cartilage were monitored, along with serum collagen type II C-telopeptide (CTX-II), cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP)-3, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and subchondral IL-1β and TNF-α levels. Roentgenographic images were also evaluated. PCP:EC:AR significantly inhibited the surgically induced increase in knee thickness, maximum extension of both knees, knee thickness after capsule exposure, gross femoral and tibial articular defect areas, loss of the knee joint area, serum and synovial COMP, CTX-II, and MMP expression, and synovial IL-1β, and TNF-α expression. In addition, surgically induced narrowing of the knee bones, loss of the joint area, cartilage damage, and osteophyte formation were reduced. PCP:EC:AR suppressed the surgically induced increases in the Mankin score, and subchondral IL-1β and TNF-α immunolabeled cell numbers. PCP:EC:AR exerted potent OA protective effects in a surgically induced OA rabbit model.

[RhoA/Rho-kinase contributes to chronic pain following thoracotomy by up-regulating glutaminase 1 expression in rat spinal dorsal cord]

OBJECTIVE

To investigate whether RhoA/Rho-kinase contributes to the occurrence of chronic post-thoracotomy pain (CPSP) by up regulation of glutaminase 1 (GLS1) expression in the spinal dorsal cord.

METHODS

Twenty five male Sprague Dawley (SD) rats were divided into control group (n=5) and model group (n=20). The rats in the model group were randomized into two sub groups (n=10) for observation on day 10 and day 21 after thoracotomy, and each group was further divided into CPSP and non CPSP groups according to the behavioral test results. All the rats were sacrificed after behavioral test for examination of GLS1 and RhoA expressions in the spinal cord using Western blotting and RT PCR. We also compared the effect of the Rho kinase inhibitor fasudil and saline, both injected intraperitoneally daily at 10 mg/kg for 7 consecutive days following thoracotomy, on CPSP and GLS1 expression in 30 male SD rats on day 21 after thoracotomy.

RESULTS

Compared with the control group, the rats with CPSP showed significantly increased expressions of GLS1 and RhoA mRNA in the spinal cord on both day 10 and day 21 following thoracotomy (P<0.01), but the rats without CPSP did not show obvious changes in GLS1 and RhoA expressions. In fasudil treated rats, the mechanical pain threshold was obviously increased and the expressions of GLS1 and RhoA were significantly reduced as compared with those in saline treated rats (P<0.01).

CONCLUSION

RhoA plays an important role in the occurence of CPSP by up-regulating the expression of GLS1 in the spinal dorsal cord of rats.

Functions of Rho family of small GTPases and Rho-associated coiled-coil kinases in bone cells during differentiation and mineralization

BACKGROUND

Members of Rho-associated coiled-coil kinases (ROCKs) are effectors of Rho family of small GTPases. ROCKs have multiple functions that include regulation of cellular contraction and polarity, adhesion, motility, proliferation, apoptosis, differentiation, maturation and remodeling of the extracellular matrix (ECM).

SCOPE OF THE REVIEW

Here, we focus on the action of RhoA and RhoA effectors, ROCK1 and ROCK2, in cells related to tissue mineralization: mesenchymal stem cells, chondrocytes, preosteoblasts, osteoblasts, osteocytes, lining cells and osteoclasts.

MAJOR CONCLUSIONS

The activation of the RhoA/ROCK pathway promotes stress fiber formation and reduces chondrocyte and osteogenic differentiations, in contrast to that in mesenchymal stem cells which stimulated the osteogenic and the chondrogenic differentiation. The effects of Rac1 and Cdc42 in promoting chondrocyte hypertrophy and of Rac1, Rac2 and Cdc42 in osteoclast are discussed. In addition, members of the Rho family of GTPases such Rac1, Rac2, Rac3 and Cdc42, acting upstream of ROCK and/or other protein effectors, may compensate the actions of RhoA, affecting directly or indirectly the actions of ROCKs as well as other protein effectors.

GENERAL SIGNIFICANCE

ROCK activity can trigger cartilage degradation and affect bone formation, therefore these kinases may represent a possible therapeutic target to treat osteoarthritis and osseous diseases. Inhibition of Rho/ROCK activity in chondrocytes prevents cartilage degradation, stimulate mineralization of osteoblasts and facilitate bone formation around implanted metals. Treatment with osteoprotegerin results in a significant decrease in the expression of Rho GTPases, ROCK1 and ROCK2, reducing bone resorption. Inhibition of ROCK signaling increases osteoblast differentiation in a topography-dependent manner.

Lidocaine induces ROCK-dependent membrane blebbing and subsequent cell death in rabbit articular chondrocytes

Local anesthetics are administered intraarticularly for pain control in orthopedic clinics and surgeries. Although previous studies have shown that local anesthetics can be toxic to chondrocytes, the underlying cellular mechanisms remain unclear. The present study investigates acute cellular responses associated with lidocaine-induced toxicity to articular chondrocytes. Rabbit articular chondrocytes were exposed to lidocaine and their morphological changes were monitored with live cell microscopy. The viability of chondrocytes was evaluated using a fluorescence based LIVE/DEAD assay. Acute treatment of chondrocytes with lidocaine (3-30 mM) induced spherical protrusions on the cell surface (so called "membrane blebbing") in a time- and concentration-dependent manner. The concentration-response relationship for the lidocaine effect was shifted leftward by elevating extracellular pH, as expected for the non-ionized lidocaine being involved in the bleb formation. ROCK (Rho-kinase) inhibitors Y-27632 and fasudil completely prevented the lidocaine-induced membrane blebbing, suggesting that ROCK activation is required for bleb formation. Caspase-3 levels were unchanged by 10 mM lidocaine (p = 0.325) and a caspase inhibitor z-VAD-fmk did not affect the lidocaine-induced blebbing (p = 0.964). GTP-RhoA levels were significantly increased (p < 0.001), but Rho inhibitor-1 failed to suppress the membrane blebbing (p = 0.875). Lidocaine (30 mM) reduced the cell viability of isolated chondrocytes (p < 0.001) and in situ chondrocytes (p < 0.001). The chondrotoxicity was attenuated by pretreatment of cells with ROCK inhibitors or a myosin-II inhibitor blebbistatin (p < 0.001). These findings suggest that lidocaine induces ROCK-dependent membrane blebbing and thereby produces a cytotoxic effect on chondrocytes. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:754-762, 2016.

Investigating the effects of the Rho-kinase enzyme inhibitors AS1892802 and fasudil hydrochloride on the contractions of isolated pregnant rat myometrium

OBJECTIVES

Rho-kinases (ROCKs), are one of the dynamic structures of the actin cytoskeleton and they mediate different biological processes, including regulation of calcium sensitivity of smooth muscle contraction. The activation of Rho A/ROCK system is thought to be effective on the termination time of the pregnancy process. The aim of this study, was to investigate in vitro effects of the ROCK enzyme inhibitors, clinically available fasudil hydrochloride, and a new promising inhibitor AS1892802, on the contractions of isolated pregnant rat myometrium.

STUDY DESIGN

Term pregnant Wistar albino rats (n=12), weighing 200-220g, were used in this study. Myometrial tissues obtained from rats were dissected into four full-thickness longitudinal muscle strips and then myometrial tension was recorded isometrically. The inhibitory effects of cumulative concentrations of AS1892802 and of fasudil hydrochloride in the presence and absence of ODQ (guanylate cyclase inhibitor), l-NAME (nitric oxide synthase inhibitor) and l-NNA (endothelial nitric oxide synthase inhibitor) on oxytocin-induced myometrial contractions were measured, and values for -log10EC50 (pD2) and mean maximal inhibition (Emax) were compared.

RESULTS

Both ROCK inhibitors, AS1892802 and fasudil hydrochloride starting from the concentrations of 10(-6)M reached statistical significance on contraction amplitude and frequency of myometrial strips (p<0.05). The inhibition of the amplitude and frequency of myometrial contractions was antagonized with ODQ (10(-5)M; only amplitude), l-NAME (3×10(-5)M) and l-NNA (10(-5)M) (p<0.05).

CONCLUSION

These results suggest that fasudil hydrochloride and AS1892802 may contribute to the development of new tocolytic drugs. We conclude that AS1892802 and fasudil hydrochloride perform this inhibitory effect partially through ROCK inhibition and the NO/cGMP pathway.

Rho Kinase (ROCK) Inhibitors and Their Therapeutic Potential

Rho kinases (ROCKs) belong to the serine-threonine family, the inhibition of which affects the function of many downstream substrates. As such, ROCK inhibitors have potential therapeutic applicability in a wide variety of pathological conditions including asthma, cancer, erectile dysfunction, glaucoma, insulin resistance, kidney failure, neuronal degeneration, and osteoporosis. To date, two ROCK inhibitors have been approved for clinical use in Japan (fasudil and ripasudil) and one in China (fasudil). In 1995 fasudil was approved for the treatment of cerebral vasospasm, and more recently, ripasudil was approved for the treatment of glaucoma in 2014. In this Perspective, we present a comprehensive review of the physiological and biological functions for ROCK, the properties and development of over 170 ROCK inhibitors as well as their therapeutic potential, the current status, and future considerations.

Long-term analgesic effect of a single dose of anti-NGF antibody on pain during motion without notable suppression of joint edema and lesion in a rat model of osteoarthritis

OBJECTIVE

Osteoarthritis (OA) patients experience exaggerated pain during movements such as walking. Anti-nerve growth factor (NGF) antibodies have recently shown analgesic effects in OA patients. We examined the effect of a single dose of anti-NGF antibody on pain during motion, joint edema and lesion in a rat model of OA to determine whether the analgesic effect demonstrated in clinical studies can be translated to a preclinical model.

METHODS

Sodium monoiodoacetate (MIA)-induced arthritic rats that develop a right-left gait imbalance when walking as an index of pain during motion. This imbalance was assessed using a gait analysis system called "CatWalk". Edema size and lesion score in the relevant knee joint were also measured. The effect of a single intravenous injection of an anti-NGF monoclonal antibody AS2886401-00 on these parameters was assessed.

RESULTS

AS2886401-00 administered at 0.3 or 1 mg/kg on Day 3 post-MIA injection resulted in a statistically significant improvement in gait imbalance even on Day 35. When gait measurement was set on Week 3 post-MIA administration, administration of the antibody at a timing close to the gait measurement, i.e., 1 or 24 h prior to the measurement, was less effective. AS2886401-00 did not suppress either edema or lesion.

CONCLUSIONS

A single dose of anti-NGF antibody exerts a long-lasting analgesic effect on pain during motion in a rat model of OA. This finding could be associated with the analgesic efficacies that anti-NGF antibodies have exhibited in clinical studies. It appears unlikely that analgesia is secondary to inhibition of joint edema and lesion.

Dual effects of Rho-kinase inhibitors on a rat model of inflammatory pain

BACKGROUND

Rho-kinases (ROCKs), a family of small GTP-dependent enzymes, are involved in a range of pain models, and their inhibition typically leads to antinociceptive effects.

OBJECTIVES

To study the effects of inhibiting ROCKs using two known inhibitors, Y27632 and HA1077 (fasudil), administered locally, on nociception and paw edema in rats.

METHODS

A range of doses of Y27632 or HA1077 (2.5 μg to 1000 μg) were injected locally into rat paws alone or in combination with carrageenan, a known proinflammatory stimulus. Nociceptive responses to mechanical stimuli and increased paw volume, reflecting edema formation, were measured at 2 h and 3 h, using a Randall-Selitto apparatus and a hydroplethysmometer, respectively.

RESULTS

Animals treated with either ROCK inhibitor showed biphasic nociceptive effects, with lower doses being associated with pronociceptive, and higher doses with antinociceptive responses. In contrast, a monophasic dose-dependent increase in edema was observed in the same animals. Local injection of 8-bromo-cyclic (c)GMP, an activator of the nitric oxide⁄cGMP⁄protein kinase G pathway, also produced biphasic effects on nociceptive responses in rat paws; however, low doses were antinociceptive and high doses were pronociceptive. Local administration of cytochalasin B, an inhibitor of actin polymerization and a downstream mediator of ROCK activity, reversed the antinociceptive effect of Y27632.

CONCLUSIONS

The results of the present study suggest that ROCKs participate in the local mechanisms associated with nociception⁄antinociception and inflammation, with a possible involvement of the nitric oxide⁄cGMP⁄protein kinase G pathway. Also, drug effects following local administration may differ markedly from the effects following systemic administration. Finally, separate treatment of pain and edema may be needed to maximize clinical benefit in inflammatory pain.

Efficacy of drugs with different mechanisms of action in relieving spontaneous pain at rest and during movement in a rat model of osteoarthritis

Patients with osteoarthritis (OA) suffer from joint pain aggravated by movement, which affect their quality of life. In the present study, a weight bearing paradigm for pain at rest and a gait paradigm for pain during movement were tested in rats with unilateral knee arthritis induced by an intra-articular injection of sodium monoiodoacetate (MIA). At week 3 after MIA (1mg/knee) injection, animals developed pain-associated, right-left imbalances of weight distribution (weight bearing) or foot print parameters (gait). Diclofenac, at doses up to 30 mg/kg orally (p.o.), did not have a significant effect on either paradigm. Morphine rectified the weight bearing and gait imbalances at 1 and 3mg/kg subcutaneously, respectively. The weak opioid and serotonin/norepinephrine reuptake inhibitor (SNRI) tramadol also significantly corrected the indices at 10mg/kg (weight bearing) and 100mg/kg p.o. (gait). The SNRI duloxetine at 30 mg/kg p.o. corrected the weight bearing imbalance but not gait imbalance. We assessed the effect of different drugs on pain-induced disturbances in weight distribution and gait in MIA-induced arthritic rats. Analgesic drugs, each with different mechanisms of action, were less effective in rectifying the imbalance in gait than that in weight distribution. The assessment of the effect of analgesics on not only rest pain but pain during movement is valuable for the comprehensive examination of their therapeutic efficacies in OA.

ROCK inhibition enhances aggrecan deposition and suppresses matrix metalloproteinase-3 production in human articular chondrocytes

Homeostasis of articular cartilage is maintained by a balance between catabolism and anabolism. Matrix metalloproteinase-3 (MMP-3) catabolism of cartilaginous extracellular matrix (ECM), including aggrecan (AGN), is an important factor in osteoarthritis progression. We previously reported that inhibition of Rho-associated coiled-coil forming kinase (ROCK), an effector of Rho family GTPases, activates the chondrogenic transcription factor SRY-type high-mobility-group box (SOX) 9 and prevents dedifferentiation of monolayer-cultured chondrocytes. We hypothesized that ROCK inhibition prevents chondrocyte dedifferentiation by altering the transcriptional balance between MMP-3 and AGN. Normal human articular chondrocytes were cultured in the presence or absence of ROCK inhibitor (ROCKi, Y-27632). Expression of MMP-3 and AGN during monolayer cultivation was assessed by quantitative real-time PCR and western blot analysis. Chondrogenic redifferentiation potential of ROCKi-treated chondrocytes was evaluated by immunohistological analysis of pellet cultures. ROCKi treatment suppressed MMP-3 expression in monolayer- and pellet-cultured chondrocytes but increased AGN expression. Chromatin immunoprecipitation revealed that the association between transcription factors E26 transformation specific (ETS)-1 and SOX9 and their target genes MMP-3 and AGN, respectively, was affected by ROCKi treatment. ROCKi decreased the association between ETS-1 and its binding sites on the MMP-3 promoter, whereas ROCKi promoted the interaction between SOX9 and the AGN promoter. Our results suggest that ROCK inhibition may have an important role in modulating the balance between degradation and synthesis of cartilaginous ECM, a finding that may facilitate development of techniques to prepare differentiated chondrocytes for cartilage regeneration therapy.

Rho kinase inhibitors: a patent review (2012 - 2013)

INTRODUCTION

The Rho kinase/ROCK is critical in vital signal transduction pathways central to many essential cellular activities. Since ROCK possess multiple substrates, modulation of ROCK activity is useful for treatment of many diseases.

AREAS COVERED

Significant progress has been made in the development of ROCK inhibitors over the past two years (Jan 2012 to Aug 2013). Patent search in this review was based on FPO IP Research and Communities and Espacenet Patent Search. In this review, patent applications will be classified into four groups for discussions. The grouping is mainly based on structures or scaffolds (groups 1 and 2) and biological functions of ROCK inhibitors (groups 3 and 4). These four groups are i) ROCK inhibitors based on classical structural elements for ROCK inhibition; ii) ROCK inhibitors based on new scaffolds; iii) bis-functional ROCK inhibitors; and iv) novel applications of ROCK inhibitors.

EXPERT OPINION

Although currently only one ROCK inhibitor (fasudil) is used as a drug, more drugs based on ROCK inhibition are expected to be advanced into market in the near future. Several directions should be considered for future development of ROCK inhibitors, such as soft ROCK inhibitors, bis-functional ROCK inhibitors, ROCK2 isoform-selective inhibitors, and ROCK inhibitors as antiproliferation agents.

Osteoarthritis pain mechanisms: basic studies in animal models

OBJECTIVE

Osteoarthritis (OA) is a complex and painful disease of the whole joint. At present there are no satisfying agents for treating OA. To promote OA research and improved treatment, this review summarizes current preclinical evidence on the development of OA.

METHODS

Preclinical OA research was searched and key findings are summarized and commented.

RESULTS

Mechanisms of OA-associated pain have been studied in rodent knee OA models produced by intra-knee injection of the chondrocyte glycolytic inhibitor mono-iodoacetate (MIA), surgery, or spontaneous development in some species. These models are clinically relevant in terms of histological damage and functional changes, and are used to study mechanisms underlying mechanical, thermal, ambulatory, body weight supporting-evoked, and ongoing OA pain. Recent peripheral, spinal, and supraspinal biochemical and electrophysiological studies in these models suggest that peripheral pro-inflammatory mediators and neuropeptides sensitize knee nociceptors. Spinal cytokines and neuropeptides promote OA pain, and peripheral and spinal cannabinoids inhibit OA pain respectively through cannabinoid-1 (CB1) and CB1/CB2 receptors. TRPV1 and metalloproteinases contribute and supraspinal descending facilitation of 5-hydroxytryptamine (5-HT)/5-HT 3 receptors may also contribute to OA pain. Conditioned place preference tests demonstrate that OA pain induces aversive behaviors, suggesting the involvement of brain. During OA, brain functional connectivity is enhanced, but at present it is unclear how this change is related to OA pain.

CONCLUSION

Animal studies demonstrate that peripheral and central sensitization contributes to OA pain, involving inflammatory cytokines, neuropeptides, and a variety of chemical mediators. Interestingly, brainstem descending facilitation of 5-HT/5-HT3 receptors plays a role OA pain.

Wnt and Rho GTPase signaling in osteoarthritis development and intervention: implications for diagnosis and therapy

Wnt and Rho GTPase signaling play critical roles in governing numerous aspects of cell physiology, and have been shown to be involved in endochondral ossification and osteoarthritis (OA) development. In this review, current studies of canonical Wnt signaling in OA development, together with the differential roles of Rho GTPases in chondrocyte maturation and OA pathology are critically summarized. Based on the current scientific literature together with our preliminary results, the strategy of targeting Wnt and Rho GTPase for OA prognosis and therapy is suggested, which is instructive for clinical treatment of the disease.