Mechanical stimulation induces preprotachykinin gene expression in osteoarthritic chondrocytes which is correlated with modulation of the transcription factor neuron restrictive silence factor

Substance P and Alpha-Calcitonin Gene-Related Peptide Differentially Affect Human Osteoarthritic and Healthy Chondrocytes

Osteoarthritis (OA) is a degenerative joint disease that not only causes cartilage loss but also structural damage in all joint tissues. Joints are innervated by alpha-calcitonin gene-related peptide (αCGRP) and substance P (SP)-positive sensory nerve fibers. Alteration of sensory joint innervation could be partly responsible for degenerative changes in joints that contribute to the development of OA. Therefore, our aim was to analyze and compare the molecular effects of SP and αCGRP on the metabolism of articular chondrocytes from OA patients and non-OA cartilage donors. We treated the cells with SP or αCGRP and analysed the influence of these neuropeptides on chondrocyte metabolism and modulation of signaling pathways. In chondrocytes from healthy cartilage, SP had minimal effects compared with its effects on OA chondrocytes, where it induced inflammatory mediators, inhibited chondrogenic markers and promoted apoptosis and senescence. Treatment with αCGRP also increased apoptosis and senescence and reduced chondrogenic marker expression in OA chondrocytes, but stimulated an anabolic and protective response in healthy chondrocytes. The catabolic influence of SP and αCGRP might be due to activation of ERK signaling that could be counteracted by an increased cAMP response. We suggest that a switch between the G-subunits of the corresponding receptors after binding their ligands SP or αCGRP plays a central role in mediating the observed effects of sensory neuropeptides on chondrocytes.

Osteoarthritis: Novel Molecular Mechanisms Increase Our Understanding of the Disease Pathology

Although osteoarthritis (OA) is the most common musculoskeletal condition that causes significant health and social problems worldwide, its exact etiology is still unclear. With an aging and increasingly obese population, OA is becoming even more prevalent than in previous decades. Up to 35% of the world’s population over 60 years of age suffers from symptomatic (painful, disabling) OA. The disease poses a tremendous economic burden on the health-care system and society for diagnosis, treatment, sick leave, rehabilitation, and early retirement. Most patients also experience sleep disturbances, reduced capability for exercising, lifting, and walking and are less capable of working, and maintaining an independent lifestyle. For patients, the major problem is disability, resulting from joint tissue destruction and pain. So far, there is no therapy available that effectively arrests structural deterioration of cartilage and bone or is able to successfully reverse any of the existing structural defects. Here, we elucidate novel concepts and hypotheses regarding disease progression and pathology, which are relevant for understanding underlying the molecular mechanisms as a prerequisite for future therapeutic approaches. Emphasis is placed on topographical modeling of the disease, the role of proteases and cytokines in OA, and the impact of the peripheral nervous system and its neuropeptides.

Dopamine/Phosphorylcholine Copolymer as an Efficient Joint Lubricant and ROS Scavenger for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic joint disease and its progression and pathogenesis are highly associated with the significant increase of joint friction and overproduction of reactive oxygen species (ROS) in inflammation. Combination of ROS elimination and lubrication enhancement may provide a novel strategy for the treatment of OA. In the present study, a pure biomaterial and nondrug system P(DMA-co-MPC), synthesized via free radical copolymerization, was designed and developed for the first time using 2-methacryloxyethyl phosphorylcholine (MPC) as a bioinspired lubricant and N-(3,4-dihydroxyphenethyl)methacrylamide (DMA) as an ROS scavenger. Our results showed that the P(DMA-co-MPC) aggregates could efficiently eliminate the ROS radicals and provide good lubrication property by adjusting the molar ratio of DMA and MPC in the copolymer. It is attributed to the antioxidant function of the hydroquinone moiety in DMA and the hydration lubrication effect of the zwitterionic phosphocholine group in MPC. Furthermore, the in vitro experiments demonstrated that the P(DMA-co-MPC) showed good biocompatibility with MC3T3-E1 cells and intracellular anti-inflammatory property by inhibiting the production of ROS and regulating the expression levels of pro-inflammatory cytokines, pain-related gene, anabolic genes, and catabolic genes. In conclusion, the drug-free P(DMA-co-MPC) aggregates developed herein can achieve dual functions of lubrication enhancement and anti-inflammatory effect and thus they may be representative as promising candidates for the treatment of OA.

Neuromodulation of bone: Role of different peptides and their interactions (Review)

Our understanding of the skeletal system has been expanded upon the recognition of several neural pathways that serve important roles in bone metabolism and skeletal homeostasis, as bone tissue is richly innervated. Considerable evidence provided by in vitro, animal and human studies have further elucidated the importance of a host of hormones and local factors, including neurotransmitters, in modulating bone metabolism and osteo-chondrogenic differentiation, both peripherally and centrally. Various cells of the musculoskeletal system not only express receptors for these neurotransmitters, but also influence their endogenous levels in the skeleton. As with a number of physiological systems in nature, a neuronal pathway regulating bone turnover will be neutralized by another pathway exerting an opposite effect. These neuropeptides are also critically involved in articular cartilage homeostasis and pathogenesis of degenerative joint disorders, such as osteoarthritis. In the present Review, data on the role of several neuronal populations in nerve-dependent skeletal metabolism is examined, and the molecular events involved are explored, which may reveal broader relationships between two apparently unrelated organs.

Sensory neuropeptides are required for bone and cartilage homeostasis in a murine destabilization-induced osteoarthritis model

Numerous studies identified a role for the sensory neuropeptides substance P (SP) and alpha calcitonin gene-related peptide (αCGRP) in osteoarthritis (OA) pain behavior. Surprisingly, little attention has been paid on how their trophic effects on cartilage and bone cells might affect structural changes of bone and cartilage in OA pathology. Here, we sought to elucidate sensory neuropeptides influence on structural alterations of bone and cartilage during murine OA pathophysiology. OA was induced by destabilization of the medial meniscus (DMM) in the right knee joint of 12 weeks old male C57Bl/6J wildtype (WT) mice and mice either deficient for SP (tachykinin 1 (Tac1)-/-) or αCGRP. By OARSI histopathological grading we observed significant cartilage matrix degradation after DMM surgery in αCGRP-deficient mice after 4 weeks whereas Tac1-/- scores were not different to sham mice before 12 weeks after surgery. Indentation-type atomic force microscopy (IT-AFM) identified a strong superficial zone (SZ) cartilage phenotype in Tac1-/- Sham mice. Opposed to WT and αCGRP-/- mice, SZ cartilage of Tac1-/- mice softened 2 weeks after OA induction. In Tac1-/- DMM mice, bone volume to total volume ratio (BV/TV) increased significantly compared to the Tac1-/- Sham group, 2 weeks after surgery. WT mice had reduced BV/TV compared to αCGRP-/- and Tac1-/- mice after 12 weeks. Increased calcified cartilage thickness and medial condyle diameter were detected in the medial tibia of all groups 8 weeks after OA induction by nanoCT analysis. Meniscal ossification occurred in all OA groups, but was significantly stronger in the absence of neuropeptides. Increased serum concentration of the respective non-deleted neuropeptide was observed in both neuropeptide-deficient mice strains. Both neuropeptides protect from age-related bone structural changes under physiological conditions and SP additionally demonstrates an anabolic effect on bone structure preservation in a pathophysiological situation. Both neuropeptide deficient mice display an intrinsic structural cartilage matrix phenotype that might alter progression of cartilage degeneration in OA.

The Role of Substance P in the Regulation of Bone and Cartilage Metabolic Activity

Substance P (SP) is a neuropeptide that is released from sensory nerve endings and is widely present in nerve fibers. It acts on bones and related tissues by binding to receptors, thereby regulating bone metabolism, cartilage metabolism, and fracture healing. SP has attracted widespread attention as a signaling substance that can be recognized by both the immune system and the nervous system. Previous studies have shown that bone and chondrocytes can synthesize and secrete sensory neuropeptides and express their receptors, and can promote proliferation, differentiation, apoptosis, matrix synthesis, and the degradation of target cells through autocrine/paracrine modes. In this paper, we review the research progress made in this field in recent years in order to provide a reference for further understanding the regulatory mechanism of bone and cartilage physiology and pathological metabolism.

Neuropeptides: important regulators of joint homeostasis

PURPOSE

This review explores the mechanisms of joint pain with a special focus on the role of neuropeptides in pain transmission and their potential role in the progression of joint degeneration as seen in osteoarthritis.

METHODS

A literature search was performed on papers published between January 1990 and September 2017 using the Web of Science Core Collection, MEDLINE and Scopus databases.

RESULTS

What is seen in the subchondral bone and synovia is mirrored in the central nervous system (CNS). Substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y are the major peptides involved both in the generation of pain as well as reducing pain post-joint trauma. The interplay between them and other neuropeptides and cytokines influence how noxious stimuli are transduced, transmitted and modulated for a final pain perception as part of a complex cascade of events. There is a close interaction between the different components in the joint that together cross-talk to adapt to load and catabolic factors during injury and inflammation.

CONCLUSION

The articular joint should be seen as an organ where local joint pain development and maintenance is influenced by interplay between the local transmitters in the joints as well as their dependence on the CNS. A slow-release cocktail of mixed antibodies targeted against neuropeptides and receptor blockers/stimulators involved in the events of early joint pain or any inflammatory joint disease is a future treatment target.

LEVEL OF EVIDENCE

V.

Spinal neuropeptide modulation, functional assessment and cartilage lesions in a monosodium iodoacetate rat model of osteoarthritis

BACKGROUND AND AIMS

Characterising the temporal evolution of changes observed in pain functional assessment, spinal neuropeptides and cartilage lesions of the joint after chemical osteoarthritis (OA) induction in rats.

METHODS AND RESULTS

On day (D) 0, OA was induced by an IA injection of monosodium iodoacetate (MIA). Rats receiving 2mg MIA were temporally assessed at D3, D7, D14 and D21 for the total spinal cord concentration of substance P (SP), calcitonin gene related-peptide (CGRP), bradykinin (BK) and somatostatin (STT), and for severity of cartilage lesions. At D21, the same outcomes were compared with the IA 1mg MIA, IA 2mg MIA associated with punctual IA injection of lidocaine at D7, D14 and D21, sham (sterile saline) and naïve groups. Tactile allodynia was sequentially assessed using a von Frey anaesthesiometer. Non-parametric and mixed models were applied for statistical analysis. Tactile allodynia developed in the 2mg MIA group as soon as D3 and was maintained up to D21. Punctual IA treatment with lidocaine counteracted it at D7 and D14. Compared to naïve, [STT], [BK] and [CGRP] reached a maximum as early as D7, which plateaued up to D21. For [SP], the increase was delayed up to D14 and maintained at D21. No difference in levels of neuropeptides was observed between MIA doses, except for higher [STT] in the 2mg MIA group (P=0.029). Neuropeptides SP and BK were responsive to lidocaine treatment. The increase in severity of cartilage lesions was significant only in the 2mg MIA groups (P=0.01).

CONCLUSION

In the MIA OA pain model, neuropeptide modulation appears early, and confirms the central nervous system to be an attractive target for OA pain quantification. The relationship of neuropeptide release with severity of cartilage lesions and functional assessment are promising and need further validation.

Peripheral Nerve Fibers and Their Neurotransmitters in Osteoarthritis Pathology

The importance of the nociceptive nervous system for maintaining tissue homeostasis has been known for some time, and it has also been suggested that organogenesis and tissue repair are under neuronal control. Changes in peripheral joint innervation are supposed to be partly responsible for degenerative alterations in joint tissues which contribute to development of osteoarthritis. Various resident cell types of the musculoskeletal system express receptors for sensory and sympathetic neurotransmitters, allowing response to peripheral neuronal stimuli. Among them are mesenchymal stem cells, synovial fibroblasts, bone cells and chondrocytes of different origin, which express distinct subtypes of adrenoceptors (AR), receptors for vasoactive intestinal peptide (VIP), substance P (SP) and calcitonin gene-related peptide (CGRP). Some of these cell types synthesize and secrete neuropeptides such as SP, and they are positive for tyrosine-hydroxylase (TH), the rate limiting enzyme for biosynthesis of catecholamines. Sensory and sympathetic neurotransmitters are involved in the pathology of inflammatory diseases such as rheumatoid arthritis (RA) which manifests mainly in the joints. In addition, they seem to play a role in pathogenesis of priori degenerative joint disorders such as osteoarthritis (OA). Altogether it is evident that sensory and sympathetic neurotransmitters have crucial trophic effects which are critical for joint tissue and bone homeostasis. They modulate articular cartilage, subchondral bone and synovial tissue properties in physiological and pathophysiological conditions, in addition to their classical neurological features.

Nociceptive Sensitizers Are Regulated in Damaged Joint Tissues, Including Articular Cartilage, When Osteoarthritic Mice Display Pain Behavior

Objective

Pain is the most common symptom of osteoarthritis (OA), yet where it originates in the joint and how it is driven are unknown. The aim of this study was to identify pain‐sensitizing molecules that are regulated in the joint when mice subjected to surgical joint destabilization develop OA‐related pain behavior, the tissues in which these molecules are being regulated, and the factors that control their regulation.

Methods

Ten‐week‐old mice underwent sham surgery, partial meniscectomy, or surgical destabilization of the medial meniscus (DMM). Pain‐related behavior as determined by a variety of methods (testing of responses to von Frey filaments, cold plate testing for cold sensitivity, analgesiometry, incapacitance testing, and forced flexion testing) was assessed weekly. Once pain‐related behavior was established, RNA was extracted from either whole joints or microdissected tissue samples (articular cartilage, meniscus, and bone). Reverse transcription–polymerase chain reaction analysis was performed to analyze the expression of 54 genes known to regulate pain sensitization. Cartilage injury assays were performed using avulsed immature hips from wild‐type or genetically modified mice or by explanting articular cartilage from porcine joints preinjected with pharmacologic inhibitors. Levels of nerve growth factor (NGF) protein were measured by enzyme‐linked immunosorbent assay.

Results

Mice developed pain‐related behavior 8 weeks after undergoing partial meniscectomy or 12 weeks after undergoing DMM. NGF, bradykinin receptors B1 and B2, tachykinin, and tachykinin receptor 1 were significantly regulated in the joints of mice displaying pain‐related behavior. Little regulation of inflammatory cytokines, leukocyte activation markers, or chemokines was observed. When tissue samples from articular cartilage, meniscus, and bone were analyzed separately, NGF was consistently regulated in the articular cartilage. The other pain sensitizers were also largely regulated in the articular cartilage, although there were some differences between the 2 models. NGF and tachykinin were strongly regulated by simple mechanical injury of cartilage in vitro in a transforming growth factor β–activated kinase 1–, fibroblast growth factor 2–, and Src kinase–dependent manner.

Conclusion

Damaged joint tissues produce proalgesic molecules, including NGF, in murine OA.

Role of capsaicin-sensitive nerves and tachykinins in mast cell tryptase-induced inflammation of murine knees

OBJECTIVE, DESIGN

Mast cell tryptase (MCT) is elevated in arthritic joints, but its direct effects are not known. Here, we investigated MCT-evoked acute inflammatory and nociceptive mechanisms with behavioural, in vivo imaging and immunological techniques.

MATERIAL AND SUBJECTS

Neurogenic inflammation involving capsaicin-sensitive afferents, transient receptor potential vanilloid 1 receptor (TRPV1), substance P (SP), neurokinin A (NKA) and their NK1 tachykinin receptor were studied using gene-deleted mice compared to C57Bl/6 wildtypes (n = 5-8/group).

TREATMENT

MCT was administered intraarticularly or topically (20 μl, 12 μg/ml). Capsaicin-sensitive afferents were defunctionalized with the TRPV1 agonist resiniferatoxin (RTX; 30-70-100 μg/kg s.c. pretreatment).

METHODS

Knee diameter was measured with a caliper, synovial perfusion with laser Doppler imaging, mechanonociception with aesthesiometry and weight distribution with incapacitance tester over 6 h. Cytokines and neuropeptides were determined with immunoassays.

RESULTS

MCT induced synovial vasodilatation, oedema, impaired weight distribution and mechanical hyperalgesia, but cytokine or neuropeptide levels were not altered at the 6-h timepoint. Hyperaemia was reduced in RTX-treated and TRPV1-deleted animals, and oedema was absent in NK1-deficient mice. Hyperalgesia was decreased in SP/NKA- and NK1-deficient mice, weight bearing impairment in RTX-pretreated, TRPV1- and NK1-deficient animals.

CONCLUSIONS

MCT evokes synovial hyperaemia, oedema, hyperalgesia and spontaneous pain. Capsaicin-sensitive afferents and TRPV1 receptors are essential for vasodilatation, while tachykinins mediate oedema and pain.

The role of peripheral nerve fibers and their neurotransmitters in cartilage and bone physiology and pathophysiology

The peripheral nervous system is critically involved in bone metabolism, osteogenesis, and bone remodeling. Nerve fibers of sympathetic and sensory origin innervate synovial tissue and subchondral bone of diathrodial joints. They modulate vascularization and matrix differentiation during endochondral ossification in embryonic limb development, indicating a distinct role in skeletal growth and limb regeneration processes. In pathophysiological situations, the innervation pattern of sympathetic and sensory nerve fibers is altered in adult joint tissues and bone. Various resident cell types of the musculoskeletal system express receptors for sensory and sympathetic neurotransmitters. Osteoblasts, osteoclasts, mesenchymal stem cells, synovial fibroblasts, and different types of chondrocytes produce distinct subtypes of adrenoceptors, receptors for vasointestinal peptide, for substance P and calcitonin gene-related peptide. Many of these cells even synthesize neuropeptides such as substance P and calcitonin gene-related peptide and are positive for tyrosine-hydroxylase, the rate-limiting enzyme for biosynthesis of catecholamines. Sensory and sympathetic neurotransmitters modulate osteo-chondrogenic differentiation of mesenchymal progenitor cells during endochondral ossification in limb development. In adults, sensory and sympathetic neurotransmitters are critical for bone regeneration after fracture and are involved in the pathology of inflammatory diseases as rheumatoid arthritis which manifests mainly in joints. Possibly, they might also play a role in pathogenesis of degenerative joint disorders, such as osteoarthritis. All together, accumulating data imply that sensory and sympathetic neurotransmitters have crucial trophic effects which are critical for proper limb formation during embryonic skeletal growth. In adults, they modulate bone regeneration, bone remodeling, and articular cartilage homeostasis in addition to their classic neurological actions.

Characterization of a REST-Regulated Internal Promoter in the Schizophrenia Genome-Wide Associated Gene MIR137

MIR137 has been identified as a candidate gene for schizophrenia from genome-wide association studies via association with an intronic single nucleotide polymorphism (SNP), rs1625579. The location of the SNP suggests one mechanism in which transcriptional or posttranscriptional regulation of miR-137 expression could underlie schizophrenia. We identified and validated a novel promoter of the MIR137 gene adjacent to miR-137 itself which can direct the expression of distinct mRNA isoforms encoding miR-137. Analysis of both endogenous gene expression and reporter gene assays determined that this internal promoter is regulated by repressor element-1 silencing transcription factor (REST), which has previously been associated with pathways linked to schizophrenia. Distinct isoforms of REST mediate differential expression at this locus, suggesting the relative levels of these isoforms are important for miR-137 expression profiles. The internal promoter contains a variable number tandem repeat (VNTR) domain adjacent to the pre-miR-137 sequence. The reporter gene activity directed by this promoter was modified by the genotype of the VNTR. Differential expression was also observed in response to cocaine, which is known to regulate the REST pathway in SH-SY5Y cells. Our data support the hypothesis that a "gene × environment" interaction could modify the level of miR-137 expression via this internal promoter and that the genotype of the VNTR could modulate transcriptional responses. We demonstrate that this promoter region is not in disequilibrium with rs1625579 and therefore would supply a distinct pathway to potentially alter miR-137 levels in response to environmental cues.

Molecular signatures of mood stabilisers highlight the role of the transcription factor REST/NRSF

BACKGROUND

The purpose of this study was to address the affects of mood modifying drugs on the transcriptome, in a tissue culture model, using qPCR arrays as a cost effective approach to identifying regulatory networks and pathways that might coordinate the cell response to a specific drug.

METHODS

We addressed the gene expression profile of 90 plus genes associated with human mood disorders using the StellARray™ qPCR gene expression system in the human derived SH-SY5Y neuroblastoma cell line.

RESULTS

Global Pattern Recognition (GPR) analysis identified a total of 9 genes (DRD3(⁎), FOS(†), JUN(⁎), GAD1(⁎†), NRG1(⁎), PAFAH1B3(⁎), PER3(⁎), RELN(⁎) and RGS4(⁎)) to be significantly regulated in response to cellular challenge with the mood stabilisers sodium valproate ((⁎)) and lithium ((†)). Modulation of FOS and JUN highlights the importance of the activator protein 1 (AP-1) transcription factor pathway in the cell response. Enrichment analysis of transcriptional networks relating to this gene set also identified the transcription factor neuron restrictive silencing factor (NRSF) and the oestrogen receptor as an important regulatory mechanism.

LIMITATIONS

Cell line models offer a window of what might happen in vivo but have the benefit of being human derived and homogenous with regard to cell type.

CONCLUSIONS

This data highlights transcription factor pathways, acting synergistically or separately, in the modulation of specific neuronal gene networks in response to mood stabilising drugs. This model can be utilised in the comparison of the action of multiple drug regimes or for initial screening purposes to inform optimal drug design.

Polymorphic variation as a driver of differential neuropeptide gene expression

The regulation of neuropeptide gene expression and their receptors in a tissue specific and stimulus inducible manner will determine in part behaviour and physiology. This can be a dynamic process resulting from short term changes in response to the environment or long term modulation imposed by epigenetically determined mechanisms established during life experiences. The latter underpins what is termed 'nature and nurture, or 'gene×environment interactions'. Dynamic gene expression of neuropeptides or their receptors is a key component of signalling in the CNS and their inappropriate regulation is therefore a predicted target underpinning psychiatric disorders and neuropathological processes. Finding the regulatory domains within our genome which have the potential to direct gene expression is a difficult challenge as 98% of our genome is non-coding and, with the exception of proximal promoter regions, such elements can be quite distant from the gene that they regulate. This review will deal with how we can find such domains by addressing both the most conserved non-exonic regions in the genome using comparative genomics and the most recent or constantly evolving DNA such as repetitive DNA or retrotransposons. We shall also explore how polymorphic changes in such domains can be associated with CNS disorders by altering the appropriate gene expression patterns which maintain normal physiology.

A CRPS-IgG-transfer-trauma model reproducing inflammatory and positive sensory signs associated with complex regional pain syndrome

The aetiology of complex regional pain syndrome (CRPS), a highly painful, usually post-traumatic condition affecting the limbs, is unknown, but recent results have suggested an autoimmune contribution. To confirm a role for pathogenic autoantibodies, we established a passive-transfer trauma model. Prior to undergoing incision of hind limb plantar skin and muscle, mice were injected either with serum IgG obtained from chronic CRPS patients or matched healthy volunteers, or with saline. Unilateral hind limb plantar skin and muscle incision was performed to induce typical, mild tissue injury. Mechanical hyperalgesia, paw swelling, heat and cold sensitivity, weight-bearing ability, locomotor activity, motor coordination, paw temperature, and body weight were investigated for 8days. After sacrifice, proinflammatory sensory neuropeptides and cytokines were measured in paw tissues. CRPS patient IgG treatment significantly increased hind limb mechanical hyperalgesia and oedema in the incised paw compared with IgG from healthy subjects or saline. Plantar incision induced a remarkable elevation of substance P immunoreactivity on day 8, which was significantly increased by CRPS-IgG. In this IgG-transfer-trauma model for CRPS, serum IgG from chronic CRPS patients induced clinical and laboratory features resembling the human disease. These results support the hypothesis that autoantibodies may contribute to the pathophysiology of CRPS, and that autoantibody-removing therapies may be effective treatments for long-standing CRPS.

Role of tachykinin 1 and 4 gene-derived neuropeptides and the neurokinin 1 receptor in adjuvant-induced chronic arthritis of the mouse

Objective

Substance P, encoded by the Tac1 gene, is involved in neurogenic inflammation and hyperalgesia via neurokinin 1 (NK1) receptor activation. Its non-neuronal counterpart, hemokinin-1, which is derived from the Tac4 gene, is also a potent NK1 agonist. Although hemokinin-1 has been described as a tachykinin of distinct origin and function compared to SP, its role in inflammatory and pain processes has not yet been elucidated in such detail. In this study, we analysed the involvement of tachykinins derived from the Tac1 and Tac4 genes, as well as the NK1 receptor in chronic arthritis of the mouse.

Methods

Complete Freund’s Adjuvant was injected intraplantarly and into the tail of Tac1^−/−, Tac4^−/−, Tacr1^−/− (NK1 receptor deficient) and Tac1^−/−/Tac4^−/− mice. Paw volume was measured by plethysmometry and mechanosensitivity using dynamic plantar aesthesiometry over a time period of 21 days. Semiquantitative histopathological scoring and ELISA measurement of IL-1β concentrations of the tibiotarsal joints were performed.

Results

Mechanical hyperalgesia was significantly reduced from day 11 in Tac4^−/− and Tacr1^−/− animals, while paw swelling was not altered in any strain. Inflammatory histopathological alterations (synovial swelling, leukocyte infiltration, cartilage destruction, bone damage) and IL-1β concentration in the joint homogenates were significantly smaller in Tac4^−/− and Tac1^−/−/Tac4^−/− mice.

Conclusions

Hemokinin-1, but not substance P increases inflammation and hyperalgesia in the late phase of adjuvant-induced arthritis. While NK1 receptors mediate its antihyperalgesic actions, the involvement of another receptor in histopathological changes and IL-1β production is suggested.

Lateral patellar facetectomy had improved clinical results in patients with patellar-retaining total knee arthroplasty

To evaluate the functional outcome of a partial lateral facetectomy in patellar-retaining total knee arthroplasty (TKA), we retrospectively analyzed 63 knees of 59 patients who underwent TKA for primary knee osteoarthritis with (32 knees of 30 patients, group 1) or without (31 knees of 29 patients, group 2) patellar facetectomy from September 2005 to July 2007. All cases were followed up for a minimum of 36 months. Although there was no significant differences between the 2 groups in preoperative patellar score, Western Ontario and McMaster Universities score, knee and function scores, postoperatively, group 1 showed more significant improvements in the scores and fewer lateral patellar osteophytes in radiographs than group 2. A partial lateral facetectomy is an effective way to improve the function of patellar-retaining TKA in patients with primary osteoarthritis.

The human neurokinin B gene, TAC3, and its promoter are regulated by Neuron Restrictive Silencing Factor (NRSF) transcription factor family

We have previously shown that one of the major determinants directing the expression of the preprotachykinin-A (TAC1) gene, which encodes the neuropeptide substance P, is the transcription factor Neuronal Restrictive Silencer Factor (NSRF), which is also termed Repressor Element-1 Silencing Factor (REST). In rodent models of epilepsy, NRSF and its truncated isoform short NRSF (sNRSF), also termed REST4, are increased as an immediate response to seizure. In similar models the neurokinin B (NKB) gene (TAC3) is also induced and NKB has also been shown to be proconvulsant. In this communication we have demonstrated that both the TAC3 endogenous gene and its promoter are regulated, directly or indirectly, by the NRSF transcription factors resulting in both the increased expression of the endogenous gene and increased reporter gene activity. We demonstrate by chromatin immunoprecipitation analysis that NRSF and sNRSF will bind to the NKB promoter in vivo. Consistent with a model in which NRSF modulation of TAC3 gene expression is a mechanism that operates during epilepsy, the observed increases in both the level of the endogenous gene and the activity of the NKB promoter by these NRSF variants, were diminished by the action of the anticonvulsant drug, carbamazepine.