Detection of tumour necrosis factor alpha and interleukin-1 beta in the rheumatoid osteoarthritic cartilage-pannus junction by immunohistochemical methods

Roles of TRP and PIEZO receptors in autoimmune diseases

Autoimmune diseases are pathological autoimmune reactions in the body caused by various factors, which can lead to tissue damage and organ dysfunction. They can be divided into organ-specific and systemic autoimmune diseases. These diseases usually involve various body systems, including the blood, muscles, bones, joints and soft tissues. The transient receptor potential (TRP) and PIEZO receptors, which resulted in David Julius and Ardem Patapoutian winning the Nobel Prize in Physiology or Medicine in 2021, attracted people's attention. Most current studies on TRP and PIEZO receptors in autoimmune diseases have been carried out on animal model, only few clinical studies have been conducted. Therefore, this study aimed to review existing studies on TRP and PIEZO to understand the roles of these receptors in autoimmune diseases, which may help elucidate novel treatment strategies.

Polymer brush based fluorescent immunosensor for direct monitoring of interleukin-1β in rat blood

A sandwich immunosensor was successfully developed for monitoring of interleukin-1β (IL-1β) in rat whole blood. The substrate stainless steel (SS) was first coated with a polydopamine layer and subsequently grafted with poly(ethylene glycol) methacrylate brushes, onto which a sandwich immunosensor was modified for detection of IL-1β. The device has been successfully applied for monitoring of IL-1β with a limit of detection of 4.7 pg mL^-1, and a linear detection range of 12.5-200 pg mL^-1. Good specificity and selectivity for monitoring of IL-1β in rat macrophage secretion were achieved. Furthermore, this device was validated by detection of IL-1β in rat whole blood samples with greater concentrations observed in obese rats compared to control, and strong positive correlation between concentrations of IL-1β and blood glucose. These results suggest this device is feasible for direct detection of target analytes in biological samples.

Current status of temporomandibular joint disorders and the therapeutic system derived from a series of biomechanical, histological, and biochemical studies

This article was designed to report the current status of temporomandibular joint disorders (TMDs) and the therapeutic system on the basis of a series of clinical, biomechanical, histological and biochemical studies in our research groups. In particular, we have focused on the association of degenerative changes of articular cartilage in the mandibular condyle and the resultant progressive condylar resorption with mechanical stimuli acting on the condyle during the stomatognathic function. In a clinical aspect, the nature and prevalence of TMDs, association of malocclusion with TMDs, association of condylar position with TMDs, association of craniofacial morphology with TMDs, and influences of TMDs, TMJ-osteoarthritis (TMJ-OA) in particular, were examined. In a biomechanical aspect, the nature of stress distribution in the TMJ from maximum clenching was analyzed with finite element method. In addition, the pattern of stress distribution was examined in association with varying vertical discrepancies of the craniofacial skeleton and friction between the articular disk and condyle. The results demonstrated an induction of large compressive stresses in the anterior and lateral areas on the condyle by the maximum clenching and the subsequent prominent increases in the same areas of the mandibular condyle as the vertical skeletal discrepancy became more prominent. Increase of friction at the articular surface was also indicated as a cause of larger stresses and the relevant disk displacement, which further induced an increase in stresses in the tissues posterior to the disks, indicating an important role of TMJ disks as a stress absorber. In a histological or biological aspect, increase in TMJ loading simulated by vertical skeletal discrepancy, which has already been revealed by the preceding finite element analysis or represented by excessive mouth opening, produced a decrease in the thickness of cartilage layers, an increase in the numbers of chondroblasts and osteoclasts and the subsequent degenerative changes in the condylar cartilage associated with the expression of bone resorption-related factors. In a biochemical or molecular and cellular aspect, excessive mechanical stimuli, irrespective of compressive or tensile stress, induced HA fragmentation, expression of proinflammatory cytokines, an imbalance between matrix metalloproteinases and the tissue inhibitors, all of which are assumed to induce lower resistance to external stimuli and degenerative changes leading to bone and cartilage resorption. Excessive mechanical stimuli also reduced the synthesis of superficial zone protein in chondrocytes, which exerts an important role in the protection of cartilage and bone layers from the degenerative changes. It is also revealed that various cytoskeletal changes induced by mechanical stimuli are transmitted through a stretch-activated or Ca2+channel. Finally, on the basis of the results from a series of studies, it is demonstrated that optimal intra-articular environment can be achieved by splint therapy, if indicated, followed by occlusal reconstruction with orthodontic approach in patients with myalgia of the masticatory muscles, and TMJ internal derangement or anterior disk displacement with or without reduction. It is thus shown that orthodontic treatment is available for the treatment of TMDs and the long-term stability after treatment.

Treatment with TNF-α inhibitor infliximab might reduce hand osteoarthritis in patients with rheumatoid arthritis

OBJECTIVES

To investigate the association between systemic and local inflammation and incident and progressive radiographic secondary osteoarthritis (OA) in interphalangeal joints (IPJs) over 3 years in rheumatoid arthritis (RA) patients and the effect of tumor necrosis factor alpha (TNF-α) inhibitor infliximab on secondary OA in IPJs.

METHODS

In the present observational longitudinal study baseline and 3-year hand X-rays of 416 recent-onset RA patients were scored for osteophytes and erosions in IPJs, blinded for time, using Osteoarthritis Research Society International atlas and Sharp-van der Heijde score. The associations between inflammatory factors and incident and progressive secondary OA in distal IPJs (DIPJs) and proximal IPJs (PIPJs) and the effect of infliximab compared to disease-modifying anti-rheumatic drug treatment on secondary OA were analyzed by multivariable regression and generalised estimating equations analyses.

RESULTS

Sixty-seven percent of the patients were female with, at baseline, a mean age of 54 years and OA present in DIPJs and PIPJs in 37% and 13%. Three years later, new secondary OA in DIPJs and PIPJs was seen in 11% and 10%, and progressive secondary OA in 36% and 35%. High erythrocyte sedimentation rate over 3 years and progressive erosive damage were risk factors for incident secondary OA in DIPJs, but not in PIPJs. At joint level, progression of erosions was associated with both incident and progressive secondary OA, only in DIPJs. Infliximab treatment was associated with lower incident secondary OA in PIPJs [relative risk 0.5 (95% confidence interval 0.2, 1.0)], independent of decrease in inflammation.

CONCLUSION

Incident and progressive secondary OA in DIPJs over 3 years was associated with high inflammatory activity in RA. Infliximab treatment reduced incident secondary OA in PIPJs independent of decrease in inflammation, suggesting that anti-TNF-α therapy might be effective against secondary hand OA via other pathways than suppression of inflammation. Further studies in populations of primary hand OA are necessary to determine the role of anti-TNF-α in treatment of primary hand OA.

Tumour necrosis factor alpha mediates transient receptor potential vanilloid 1-dependent bilateral thermal hyperalgesia with distinct peripheral roles of interleukin-1beta, protein kinase C and cyclooxygenase-2 signalling

TNFalpha plays a pivotal role in rheumatoid arthritis (RA) but little is known of the mechanisms that link the inflammatory and nociceptive effects of TNFalpha. We have established a murine model of TNFalpha-induced TRPV1-dependent bilateral thermal hyperalgesia that then allowed us to identify distinct peripheral mechanisms involved in mediating TNFalpha-induced ipsilateral and contralateral hyperalgesia. Thermal hyperalgesia and inflammation were assessed in both hindpaws following unilateral intraplantar (i.pl.) TNFalpha. The hyperalgesic mechanisms were analysed through pharmacogenetic approaches involving TRPV1(-/-) mice and TRPV1 antagonists. To study the mediators downstream of TNFalpha, cyclooxygenase (COX) and PKC inhibitors were utilised and cytokine and prostaglandin levels assessed. The role of neutrophils was determined through use of the selectin inhibitor, fucoidan. We show that TNFalpha (10pmol) causes thermal hyperalgesia (1-4h) in the ipsilateral inflamed and contralateral uninjured hindpaws, which is TRPV1-dependent. GF109203X, a PKC inhibitor, suppressed the hyperalgesia indicating that PKC is involved in TRPV1 sensitisation. Ipsilateral COX-2-derived prostaglandins were also crucial to the development of the bilateral hyperalgesia. The prevention of neutrophil accumulation with fucoidan attenuated hyperalgesia at 4 but not at 1h, indicating a role in the maintenance but not in the induction of bilateral hyperalgesia. However, TNFalpha-induced IL-1beta generation in both paws and the presence of local IL-1beta in the contralateral paw were essential for the development of bilateral hyperalgesia. These results identify a series of peripheral events through which TNFalpha triggers and maintains bilateral inflammatory pain. This potentially allows a better understanding of mechanisms involved in TNFalpha-dependent pain pathways in symmetrical diseases such as arthritis.

The effect of a newly synthesized indazole compound, TAS-3-124, on experimental autoimmune disease

The effects of a newly synthesized compound, 6-acetoamido-1-acetyl-1-indazole (TAS-3-124), on autoimmune diseases were studied. We used animal models of collagen-induced arthritis (CIA) in mice and experimental autoimmune encephalomyelitis (EAE) in rats to evaluate the efficacy of TAS-3-124. TAS-3-124 at doses of 100 and 300 mg/kg p.o. inhibited the development of CIA, decreasing the swelling of fore- and hind-limbs and bone destruction in knee joints. This agent also suppressed the delayed type hypersensitivity reaction (DTH) against type II collagen. These effects were confirmed by histopathological examination and measurement of the expression of mRNA of proinflammatory cytokines in the knee joint. In addition, TAS-3-124 at a dose of 300 mg/kg inhibited the development of EAE and the DTH to myelin basic protein (MBP) in rats. Moreover, TAS-3-124 inhibited the production of proinflammatory cytokines including interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and IL-6 but not T cell derived cytokines in mice. These demonstrate the efficacy of TAS-3-124 against experimental autoimmune disease, probably due to the suppression of the production of proinflammatory cytokines in the pathological lesion.

Serum levels of type IIA procollagen amino terminal propeptide (PIIANP) are decreased in patients with knee osteoarthritis and rheumatoid arthritis

OBJECTIVE

The aim of this study was to develop a specific immunoassay for PIIANP and measure its serum concentration in healthy controls and in patients with osteoarthritis (OA) and rheumatoid arthritis (RA). In addition, we investigated circulating forms recognized by antiserum IIA in pools of serum from healthy adults, patients with OA and patients with RA.

DESIGN

Using as immunogen and standard the recombinant human Glutathione S-Transferase (GST)-exon 2 fusion protein of type II collagen, we developed a competitive polyclonal antibody-based ELISA. We compare serum PIIANP levels in 43 patients with knee OA (23 women and 20 men; mean age: 62.6+/-9.6 yr), 63 women with RA (mean age: 54+/-16 yr) and 88 healthy controls (67 women, mean age: 53+/-13 yr and 21 men, mean age: 63+/-7 yr). We randomly selected serum in each group for analyze circulating forms.

RESULTS

The immunoassay we developed demonstrated adequate intra and inter-assay precision (CV<10%) and dilution recovery (mean: 96%), allowing accurate measurements of serum PIIANP from 1.13 to 40 ng/ml. No significant cross-reactivity of the ELISA was observed with purified intact human procollagen type I N-propeptide, circulating thrombospondin and von Willebrand factor, proteins which exhibit significant sequence homology with PIIANP. Western blot analysis showed that antiserum IIA recognized two circulating immunoreactive forms of approximately 80 and 100 KDa respectively in serum from healthy adults, patients with OA and RA but also in a pool of synovial fluids from patients with OA. Serum PIIANP levels were markedly decreased in patients with knee OA (12.0+/-3.2 vs 25.8+/-7.5 ng/ml for OA and controls respectively, P<0.0001) and RA (14.1+/-2.5 ng/ml vs 21.7+/-7.6 ng/ml for RA and controls respectively, P<0.0001). In patients with RA, serum PIIANP levels were higher in those taking low-dose prednisone compared to non-users (15.0+/-2.4 vs 13.5+/-2.4 ng/ml, P<0.05).

CONCLUSIONS

We have developed the first specific immunoassay for serum PIIANP which exhibits adequate technical performances. This assay detects specifically two immunoreactive forms both in healthy adults and patients with arthritis and does not cross react with other proteins with sequence homology with PIIANP. Levels of PIIANP were significantly decreased in patients with knee OA and RA suggesting that type IIA collagen synthesis may be altered in these arthritic diseases. The measurement of type IIA collagen synthesis with this new molecular marker may be useful for the clinical investigation of patients with joint diseases.

Endothelial cell phenotypes in the rheumatoid synovium: activated, angiogenic, apoptotic and leaky

Endothelial cells are active participants in chronic inflammatory diseases. These cells undergo phenotypic changes that can be characterised as activated, angiogenic, apoptotic and leaky. In the present review, these phenotypes are described in the context of human rheumatoid arthritis as the disease example. Endothelial cells become activated in rheumatoid arthritis pathophysiology, expressing adhesion molecules and presenting chemokines, leading to leukocyte migration from the blood into the tissue. Endothelial cell permeability increases, leading to oedema formation and swelling of the joints. These cells proliferate as part of the angiogenic response and there is also a net increase in the turnover of endothelial cells since the number of apoptotic endothelial cells increases. The endothelium expresses various cytokines, cytokine receptors and proteases that are involved in angiogenesis, proliferation and tissue degradation. Associated with these mechanisms is a change in the spectrum of genes expressed, some of which are relatively endothelial specific and others are widely expressed by other cells in the synovium. Better knowledge of molecular and functional changes occurring in endothelial cells during chronic inflammation may lead to the development of endothelium-targeted therapies for rheumatoid arthritis and other chronic inflammatory diseases.

The pathophysiological role of cytokines

Cytokines are important hormonal mediators, produced in tissues undergoing defence, growth and repair processes. Infection and inflammation in particular result in a cascade of cytokine induction that acts to maintain tissue homeostasis. Most cytokines act within the injured tissues, although some have an endocrine action, recruiting distant tissues in defence of the tissue producing the cytokine and many are important for regulating acquired immunity in secondary lymphoid tissues. Induction of interleukin-1 (IL-1), tumour necrosis factor (TNF) and IL-6 highlight the way in which local tissue cytokine responses are induced and act. Since most cytokines act locally, cytokine measurement presents several difficulties. Only where cytokines (such as IL-6) have a systemic action are plasma cytokine concentrations really meaningful. The presence of cytokine antagonists and soluble cytokine receptors, often released in concert with their respective cytokine agonists, presents additional complexity to interpretation. Measurement and manipulation of cytokines can contribute towards an understanding of their pathophysiological role in both experimental and clinical settings. This includes measurement of plasma IL-6, which has striking relationships to tissue inflammation. Its value is exemplified by some recent studies of stroke patients, where IL-6 reflects not only the initial response but also clinical outcome and survival.

Co-expression of interleukin-1beta and tumor necrosis factor alpha in synovial tissues and synovial fluids of temporomandibular joint with internal derangement: comparison with histological grading of synovial inflammation

BACKGROUND

It has been clarified that interleukin-1 (IL-1)beta and tumor necrosis factor (TNF)alpha play an important role in pathogenesis of various joint disease. The purpose of this study was to investigate the cellular source of IL-1beta and TNFalpha in temporomandibular joint (TMJ), and to analyze the relation between the expression of these cytokines and the intensity of TMJ synovial inflammation.

METHODS

We examined 33 synovial biopsy specimens from patients with internal derangement of the TMJ by an immunohistochemical technique using specific antibodies to IL-1beta and TNFalpha. We also studied 20 synovial fluids from the patients by enzyme-linked immunosorbent assay method. These data are compared with histological grading of synovial inflammation by Gynther's system.

RESULTS

Both IL-1beta and TNFalpha were predominantly localized in the synovial lining cell layer and the blood vessels of synovial biopsy specimens obtained from patients with TMJ internal derangement. A statistically significant correlation was found between the intensity of IL-1beta expression and that of TNFalpha. Additionally, the intensity of TNFalpha expression was statistically correlated with histological grading by Gynther's system.

CONCLUSION

These results supported that IL-1beta and TNFalpha may be involved in the occurrence of TMJ internal derangement and that they coordinately play an role in pathogenesis of TMJ internal derangement.

Immunohistochemical study of interleukin-1beta and interleukin-1 receptor antagonist in an antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUND

In temporomandibular joint (TMJ) arthritis, there is limited knowledge of the relationship between interleukin-1beta (IL-1beta) and interleukin-1 receptor antagonist (IL-1ra), as well as the source of these cytokines. We investigated the development of an antigen-induced arthritis in the rabbit TMJ immunohistochemically.

METHODS

Unilateral TMJ arthritis was induced in 32 adult New Zealand White rabbits. From 6 h to 12 weeks after induction of arthritis, topology of IL-1beta and IL-1ra were observed.

RESULT

The acute stage of induced arthritis lasted for one week after induction, thereafter it became chronic. In the early phase of the acute stage, infiltrating inflammatory cells, as well as synovial cells, produced IL-1beta and IL-1ra. In the late phase of the acute stage, the main source of these cytokines was subsynovial fibroblasts. In this phase of arthritis, IL-1beta and IL-1ra did not appear to be produced by synovial cells. From the early to intermediate phase of the chronic stage, proliferating synovial cells produced IL-1beta and IL-1ra. In this phase of the arthritis, these cytokines were also observed in a cluster formation in chondrocytes.

CONCLUSION

This arthritis model shows a staging of the joint inflammation process with time. IL-1beta and IL-1ra are produced by a certain kind of cells depending on the stage of inflammation.

How circulating cytokines trigger the neural circuits that control the hypothalamic-pituitary-adrenal axis

It is now no secret that the brain plays a crucial role in organizing, adapting and restraining the systemic inflammatory response via a complex cascade of mechanisms involving proteins of the innate immune system, molecules of the proinflammatory signal transduction pathways, prostaglandins (PGs) and specific populations of neurons. These neuronal circuits, in particular those controlling autonomic functions, are all together involved in engaging the physiological responses that may help eliminating the foreign material and adjust the inflammatory events to prevent detrimental consequences. For instance, elevation in plasma glucocorticoid levels is one of the most powerful endogenous and well-controlled feedback on the pro-inflammatory signal transduction machinery taking place across the organisms. The main Center that controls this neuroendocrine system is the paraventricular nucleus of the hypothalamus (PVN) that receives neuronal projections from numerous hypothalamic and extra-hypothalamic nuclei and areas. There is now compelling evidence that molecules produced by cells of the blood-brain barrier (BBB) may bind to their cognate receptors expressed at the surface of neurons that are responsible to trigger the hypothalamic-pituitary adrenal (HPA) axis. This review presents the new molecular insights regarding the pro-inflammatory signal transduction pathways that occur in these cells and how they are related to the neuroendocrine circuits mediating the increase in plasma glucocorticoid levels during systemic and localized immunogenic insults.

A synthetic triterpenoid selectively inhibits the induction of matrix metalloproteinases 1 and 13 by inflammatory cytokines

OBJECTIVE

To address the effects of a novel synthetic triterpenoid, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), on the induction of matrix metalloproteinases 1 and 13 (MMP-1, MMP-13) by inflammatory cytokines.

METHODS

Human chondrosarcoma cells stimulated with inflammatory cytokines (interleukin-1beta [IL-1beta], tumor necrosis factor alpha) were used to study the effects of CDDO on the induction of MMPs and the invasion of cells through a collagen matrix.

RESULTS

CDDO selectively reduced the induction of MMP-1 and MMP-13 at the levels of messenger RNA and protein. Treatment with CDDO prior to cytokine stimulation enhanced this inhibition, and we demonstrated that CDDO functions at the level of transcription. Additionally, CDDO reduced IL-1beta-mediated invasion of cells through a collagen matrix.

CONCLUSION

This study demonstrates that CDDO is a novel inhibitor of MMP-1 and MMP-13 gene expression mediated by inflammatory cytokines. Thus, CDDO may have therapeutic potential for the inhibition of joint degradation in osteoarthritis.

Antigen-presenting cells containing bacterial peptidoglycan in synovial tissues of rheumatoid arthritis patients coexpress costimulatory molecules and cytokines

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by intimal lining hyperplasia and massive infiltration of the synovial sublining by antigen-presenting cells (APCs), lymphocytes, and plasma cells. Peptidoglycan (PG), a major cell wall component of gram-positive bacteria, which is abundantly expressed in all mucosa, is believed to be involved in the pathogenesis of RA because of its ability to induce the production of proinflammatory cytokines as well as to induce arthritis in rodents. While PG has been detected in APCs in RA joints, little is known about the role of these cells in RA. In this study, the presence and immune competence of PG-containing cells in synovial tissues from 14 RA and 14 osteoarthritis (OA) patients were analyzed in situ.

METHODS

Using immunohistochemistry, we examined the coexpression of phenotypic markers, costimulatory molecules, and cytokines by PG-containing cells.

RESULTS

PG was present in higher numbers in RA than in OA synovial tissues, although the difference was not significant. PG-containing cells were mainly macrophages, but some mature dendritic cells also contained PG. A high percentage of PG-containing cells in both RA and OA synovial tissues coexpressed HLA-DR. CD40, CD80, and CD86 expression by PG-containing cells was higher in RA than in OA tissues. Furthermore, PG-containing cells coexpressed cytokines, which modulate inflammatory reactions, in particular, tumor necrosis factor alpha and interleukins 6 and 10.

CONCLUSION

The results suggest that PG-containing cells may contribute to inflammation within the microenvironment of the joint in RA patients.

The effects of high magnitude cyclic tensile load on cartilage matrix metabolism in cultured chondrocytes

Excessive mechanical load is thought to be responsible for the onset of osteoarthrosis (OA), but the mechanisms of cartilage destruction caused by mechanical loads remain unknown. In this study we applied a high magnitude cyclic tensile load to cultured chondrocytes using a Flexercell strain unit, which produces a change in cell morphology from a polygonal to spindle-like shape, and examined the protein level of cartilage matrixes and the gene expression of matrix metalloproteinases (MMPs), tissue inhibitors of matrix metalloproteinases (TIMPs) and proinflammatory cytokines such as IL-1beta and TNF-alpha. Toluidine blue staining, type II collagen immunostaining, and an assay of the incorporation of [35S]sulfate into proteoglycans revealed a decrease in the level of cartilage-specific matrixes in chondrocyte cultures subjected to high magnitude cyclic tensile load. PCR-Southern blot analysis showed that the high magnitude cyclic tensile load increased the mRNA level of MMP-1, MMP-3, MMP-9, IL-1beta, TNF-alpha and TIMP-1 in the cultured chondrocytes, while the mRNA level of MMP-2 and TIMP-2 was unchanged. Moreover, the induction of MMP-1, MMP-3 and MMP-9 mRNA expression was observed in the presence of cycloheximide, an inhibitor of protein synthesis. These findings suggest that excessive mechanical load directly changes the metabolism of cartilage by reducing the matrix components and causing a quantitative imbalance between MMPs and TIMPs.

Effects of interleukin-1beta and tumor necrosis factor-alpha on expression of matrix-related genes by cultured equine articular chondrocytes

OBJECTIVE

To determine the effects of interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) on expression and regulation of several matrix-related genes by equine articular chondrocytes.

SAMPLE POPULATION

Articular cartilage harvested from grossly normal joints of 8 foals, 6 yearling horses, and 8 adult horses.

PROCEDURE

Chondrocytes maintained in suspension cultures were treated with various doses of human recombinant IL-1beta or TNF-alpha. Northern blots of total RNA from untreated and treated chondrocytes were probed with equine complementary DNA (cDNA) probes for cartilage matrix-related genes. Incorporation of 35S-sulfate, fluorography of 14C-proline labeled medium, zymography, and western blotting were used to confirm effects on protein synthesis.

RESULTS

IL-1beta and TNF-alpha increased steady-state amounts of mRNA of matrix metalloproteinases 1, 3, and 13 by up to 100-fold. Amount of mRNA of tissue inhibitor of metalloproteinase-1 also increased but to a lesser extent (1.5- to 2-fold). Amounts of mRNA of type-II collagen and link protein were consistently decreased in a dose-dependent manner. Amount of aggrecan mRNA was decreased slightly; amounts of biglycan and decorin mRNA were minimally affected.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment of cultured equine chondrocytes with IL-1beta or TNF-alpha resulted in marked alterations in expression of various matrix and matrix-related genes consistent with the implicated involvement of these genes in arthritis. Expression of matrix metalloproteinases was increased far more than expression of their putative endogenous inhibitor. Results support the suggestion that IL-1beta and TNF-alpha play a role in the degradation of articular cartilage in arthritis.

Anabolic and destructive mediators in osteoarthritis

Osteoarthritis is a joint disease that is characterized by focal degradation of articular cartilage. In addition to the degeneration of articular cartilage, attempts at repair are found in the affected tissue. Cartilage cells (chondrocytes) play a key role, not only in the destructive process, but also in the repair response. It has become apparent that anabolic and catabolic mediators, released from chondrocytes themselves or from other joint cells, drive both destructive and repair activities in the osteoarthritic joint.

How the blood talks to the brain parenchyma and the paraventricular nucleus of the hypothalamus during systemic inflammatory and infectious stimuli

There are exciting new developments regarding the molecular mechanisms involved in the influence of circulating proinflammatory molecules within cells of the blood-brain barrier (BBB) during systemic immune challenges. These molecules, when present in the circulation, have the ability to trigger a series of events in cascade, leading to either the mitogen-activated protein (MAP) kinases/nuclear factor kappa B (NF-kappaB) or the janus kinase (JAK)/signal transducer and activator of transcription (STAT) transduction pathways in vascular-associated cells of the central nervous system (CNS). The brain blood vessels exhibit both constitutive and induced expression of receptors for different proinflammatory ligands that have the ability to stimulate these signaling molecules. Depending on the challenges and the cytokines involved, the transduction signal(s) solicited in cells of the BBB may orient the neuronal activity in a very specific manner in activating the transcription and production of soluble factors, such as prostaglandins (PGs). It is interesting to note that cytokines as well as systemic localized inflammation stimulate the cells of the BBB in a nonselective manner (i.e., within both large blood vessels and small capillaries across the brain). This nonselectivity raises several questions with regard to the localized neuronal activation induced by different experimental models of inflammation and cytokines. It is possible that the selectivity of the neuronal response is a consequence of the fine interaction between nonparenchymal synthesis of soluble mediators and expression of specific receptors for these ligands within parenchymal elements of different brain nuclei. This review will present the recent developments on this concept and the mechanisms that take place in cells of the BBB, which lead to the neuronal circuits involved in restoring the body's homeostasis during systemic immunogenic challenges. The induction of fever, the hypothalamic-pituitary adrenal (HPA) axis, and other autonomic functions are among the physiological outcomes necessary for the protection of the mammalian organism in the presence of foreign material.

Specific expression of interleukin-1 beta in temporomandibular joints with internal derangement: correlation with clinical findings

OBJECTIVE

Interleukin-1 beta appears to play an important role in the pathophysiology of joint diseases. The aim of this study was to analyze the expression of interleukin-1 beta in temporomandibular joint internal derangement.

STUDY DESIGN

Using an immunohistochemical technique with specific antibodies, we examined 20 human temporomandibular joint samples from patients with internal derangement of the temporomandibular joint: 5 extirpated disks and 15 biopsy specimens from the synovitic area of the temporomandibular joint upper compartment. We also examined 2 control specimens. The evaluation of interleukin-1 beta expression compared with clinical findings.

RESULTS

Interleukin-1 beta was predominantly localized in the synovial lining cells and endothelial cells of blood vessels. Statistically significant correlation was found between interleukin-1 beta expression and some clinical findings.

CONCLUSIONS

The results suggest that interleukin-1 beta may be involved in the pathogenesis of temporomandibular joint internal derangement and that the intensity of interleukin-1 beta expression may correlate with clinical findings, especially pain.

Advances in the microscopy of osteoarthritis

This review describes recent contributions made by microscopy to the understanding of osteoarthritis, a clinical syndrome the pathological features of which are well defined by classical white light microscopy. The fluorescence and reflected light, conventional and scanning optical microscopy of excised osteoarthritic tissue preparations, from human and animal sources, has enabled the identification of cell proteins such as S100, of matrix components such as the proteoglycans and collagens, and of adhesion molecules including fibronectin, the integrins and tenascin. Comparable microscopic studies have been made of cell and tissue culture preparations of osteoarthritic cartilage and synovium. Scanning optical microscopy also allows the rapid measurement, in hydrated osteoarthritic tissues, of cell density, cell size, surface roughness and other parameters. The importance of water in sustaining the physical attributes of cartilage is accepted and new forms of electron microscopy can play important parts in the study of unfixed osteoarthritic cartilage. These methods include the low temperature scanning electron microscopy and electron probe x-ray microanalysis of hydrated bulk material and the high resolution transmission electron microscopy of low temperature replicas of cartilage surfaces. Understanding of osteoarthritis has been facilitated by these advances and will continue to be enhanced as new techniques of microscopy evolve.

Prevalence, morphology, and topography of blood vessels in herniated disc tissue. A comparative immunocytochemical study

STUDY DESIGN

Ninety disc herniations removed during surgery were studied by immunocytochemistry, using two different endothelial cell markers, to study the prevalence, morphology, and topography of blood vessels in disc herniations.

OBJECTIVES

To increase the specific localization of even very small blood vessels present in disc herniations by using specific antibodies to endothelial cells; to study blood vessels comparatively with two different endothelial cell antibodies, comparing their prevalence; and to study blood vessel morphology and topographic relationships of blood vessels to other tissue elements, particularly disc cells.

SUMMARY OF BACKGROUND DATA

In many previous macroscopic studies and in studies using conventional histologic methodology, blood vessels have been observed in degenerated and injured intervertebral discs. In a smaller patient sample, the authors previously observed blood vessels in approximately 80% of disc herniations by immunocytochemistry, the blood vessels co-localizing with macrophage cells. Many of these blood vessels are the product of very active neovascularization after disc tissue injury. The presence of such blood vessels has not, however, been studied in greater detail or in larger patient samples. Immunocytochemistry offers superior visualization and more specific localization and was thus used in the present study.

METHODS

Thin frozen sections from 90 disc herniations were immunostained in parallel with von Willebrand factor and Ulex europaeus antibodies, both of which localize endothelial cells specifically. Indirect immunocytochemistry by avidin-biotin-peroxidase complex or alkaline phosphatase-antialkaline phosphatase were used for immunolocalization. Blood vessels were classified as being: +, abundant: (+), very few; or +, totally absent.

RESULTS

The prevalence of blood vessels in disc herniations was found in 82 of 90 (91%) disc herniations with von Willebrand factor antibody and in 75 of 90 (83%) disc herniations with Ulex europaeus antibody. In 59 disc herniations (66%), blood vessels were observed with both antibodies in parallel, whereas they were observed with neither antibody in only six of 90 disc herniations. Furthermore, the ratio of abundant to very few blood vessels was 73:9 with von Willebrand factor antibody and 63:12 with Ulex europaeus antibody, further supporting the abundance of blood vessels in disc herniations. Blood vessels were most prevalent in sequestrated discs, but they were also observed in six of eight protrusions. Dense blood vessel networks were observed to penetrate the disc tissue, and blood vessels were also present in areas of inflammatory cell infiltration. Topographically, blood vessels were, on several occasions and with both antibodies, seen to pass close by or to surround disc cells.

CONCLUSIONS

By immunocytochemistry with endothelial cell markers, blood vessels can be observed to be numerous, and their prevalence in herniated discs is very high, presumably as a result of a very intense neovascularization process after the disc injury. A close apposition to disc cells may suggest attempts to increase the nutrition of these cells and will influence the metabolism of the cells.

Immunocytochemical localization of immunoglobulins in disc herniations

STUDY DESIGN

Disc herniation and control discs were studied for the presence of immunoglobulins immunocytochemically.

OBJECTIVES

To study a possible presence of immunoglobulin complexes in herniated disc tissue and to locate them at the tissue level by immunocytochemistry; to compare immunohistologic findings with those obtained in control disc tissue; and to compare the prevalences of immunoglobulin M and immunoglobulin G.

SUMMARY OF BACKGROUND DATA

In herniated disc tissue, high activity of inflammatory phospholipase A2 was previously demonstrated, and inflammatory cells were noted immunohistochemically. Immunoglobulins G and M were observed biochemically but have not been located at the tissue level.

METHODS

Fifty-two disc herniations and three macroscopically normal fresh cadaver discs were managed by an identical immunocytochemical protocol, using monoclonal antihuman antibodies to immunoglobulins M and G.

RESULTS

In 29 of 52 disc herniations (56%), immunoglobulin M deposits were observed, and in 18 of 52 disc herniations (35%) immunoglobulin G could be demonstrated. Almost all the disc herniations where immunoglobulin G was present also contained immunoglobulin M deposits (except for two). In the control discs studied, neither immunoglobulin could be observed immunohistochemically. The immunoglobulin deposits were noted in areas where blood vessels were also present. Morphologically, immunoglobulin immunoreactivity resembling immune complexes was observed.

CONCLUSIONS

The results lend support to previous suggestions of inflammation and immune reaction in disc herniations, including previous biochemical studies suggesting immunoglobulin deposition. The exact role of the demonstrated immunoglobulins in disc tissue pathophysiology will have to be clarified further.

Dose-range and dose-frequency study of recombinant human interleukin-1 receptor antagonist in patients with rheumatoid arthritis. The IL-1Ra Arthritis Study Group

OBJECTIVE

To preliminarily evaluate the safety and efficacy of different dose levels and dosing frequencies of recombinant human interleukin-1 receptor antagonist (rHuIL-1Ra) in the treatment of patients with rheumatoid arthritis (RA).

METHODS

One hundred seventy-five patients with active RA were enrolled in a randomized, double-blind trial of rHuIL-1Ra administered by subcutaneous injection. There were 9 treatment groups in the trial. During the initial 3-week treatment phase, patients were treated with 20, 70, or 200 mg rHuIL-1Ra, administered either once, 3 times, or 7 times per week, followed by a 4-week maintenance phase, during which all patients received the treatment-phase dose once per week. To maintain the blindness of the study, patients received daily injections of either rHulL-1Ra or placebo on the days rHuIL-1Ra was not administered.

RESULTS

Recombinant HuIL-1Ra was well tolerated. The most frequent adverse event was injection-site reactions, which were reported in 62% of patients and caused 8 patients (5%) to withdraw prematurely from the study. Five patients (3%) developed serious adverse reactions unrelated to dose or dosing frequency. Due to the lack of a placebo arm and to the multiple small treatment groups, a definitive statement regarding efficacy could not be made. However, by the end of the 3-week treatment phase, daily dosing appeared more effective than weekly dosing when assessed by the number of swollen joints, the investigator and patient assessments of disease activity, pain score, and C-reactive protein levels.

CONCLUSION

These preliminary data suggest that rHuIL-1Ra may be safely administered by subcutaneous injection to RA patients. The frequency of dosing appears to be important in determining clinical response, with daily administration providing the most benefit. A placebo-controlled trial is in progress to further assess the clinical usefulness and to better define appropriate doses of rHuIL-1Ra in patients with RA.

Tumor necrosis factor-alpha (TNF-alpha) in canine osteoarthritis: Immunolocalization of TNF-alpha, stromelysin and TNF receptors in canine osteoarthritic cartilage

The presence and distribution of tumor necrosis factor-alpha (TNF-alpha), TNF receptors and stromelysin [matrix metalloproteinase 3 (MMP-3)] in articular cartilage were evaluated in an iatrogenically induced model of osteoarthritis (OA). Eleven adult male dogs were assigned randomly to a control group (N = 4) or an OA group (N = 7). Osteoarthritis was created by surgical transection of the cranial cruciate ligament of one stifle joint. Both femoral condyles were sampled 3 months post-surgery at necropsy and immunohistochemically analyzed for the presence of the aforementioned cytokines and receptors. Chondrocytes stained for TNF-alpha and TNF receptors in control articular cartilage, spanning an area encompassing most of the middle and deep zones. Positive matrical and chondrocytic staining for TNF-alpha, TNF receptors, and stromelysin was present in OA articular cartilage. Staining varied in intensity and distribution and was dependent of the severity of the lesion. Smooth muscle cells of arteries and arterioles (periarticular synovial membrane) were stained for only one (p55) of two TNF receptors; this staining was confined to control tissues. Results indicate that the differential expression of TNF-alpha and its receptors may be important in the normal maintenance of articular cartilage. The increased presence of TNF-alpha and its receptors in articular cartilage with mild osteoarthritic changes suggests a role in the development of early OA. Regulating TNF-alpha may be an important component in the treatment of OA.

Cytokines in osteoarthritis: mediators or markers of joint destruction?

OBJECTIVE

The integrity of articular cartilage is maintained by the balance between cytokine-driven anabolic and catabolic processes. Unregulated or excess influences of these molecules are thought to play a part in the pathophysiology of many joint diseases. However, the role of cytokines in osteoarthritis (OA) is not well established. Our aims are twofold: firstly to consider the evidence for the contribution of cytokines to the pathophysiology of OA and secondly to evaluate their potential as markers of disease activity in OA.

METHODS

Cytokine homeostasis, the role of catabolic and anabolic cytokines in maintaining cartilage integrity, and the contribution of such cytokines to destructive processes in OA were examined. Consideration was given to the interrelationship between cartilage, bone, and synovium in OA; metabolites produced by such structures were compared with cytokines as indicators of disease activity.

RESULTS

The evidence reviewed suggests that interleukin-1 (IL-1) and the less potent tumor necrosis factor alpha (TNF alpha) are mediators of joint damage in OA. The cytokines interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) were implicted in both destructive and protective mechanisms, suggesting a dual role. Metabolites of the different components of the joint provided a better measure of disease activity than cytokines.

CONCLUSIONS

Experimental evidence is emerging that catabolic cytokines are mediators of joint damage in OA, although their usefulness as markers of disease activity is limited because of the need to monitor a wide range of ligands and their inhibitors simultaneously. In contrast, metabolites released from cells within bone, synovium, and cartilage related to disease activity and provided prognostic information.

Association between degree of bone-erosion and synovial fluid-levels of tumor necrosis factor alpha in the knee-joints of patients with rheumatoid arthritis

OBJECTIVE

To determine whether concentrations of cytokines and matrix-degrading enzymes in synovial fluid of patients with rheumatoid arthritis or osteoarthritis are associated with the degree of bone-destruction in the same joint.

METHODS

Determination of Interleukin-1 alpha, IL-1 beta, IL-1-receptor-antagonist, IL-6, IL-8, tumor necrosis factor alpha (by ELISA), collagenase-activity and caseinase-activity (by substrate-assays) in the SF (knee) of patients with RA (n42) or OA (n35). The degree of bone-destruction was assessed radiographically.

RESULTS

SF cytokine- and enzyme-levels were higher in patients with RA than in those with OA. In the RA group, SF-levels of TNF alpha were positively correlated with the degree of bone destruction of the respective joint. No correlation was found between radiographically assessed joint changes and SF-concentrations of other cytokines, enzyme activities, serum CRP, or duration of disease. In the OA-group, none of the examined parameters was associated with the degree of joint destruction.

CONCLUSIONS

Our data may support the assumption of TNF alpha playing an important role in joint destruction in RA. Possible alternative conclusions are discussed.

Production of TNF by monocytes of patients with early rheumatoid arthritis is increased

We studied the production of tumour necrosis factor alpha (TNF) by monocytes of patients with early rheumatoid arthritis (RA) before starting disease modifying anti-rheumatic drug treatment and a median 6 months (range 5-11 months) later, and correlated the pre-treatment results with 3-year prognosis. Monocytes of patients (n = 14) and controls (n = 14), isolated by the density gradient centrifugations, were cultured for 24 h with Escherichia coli lipopolysaccharide (LPS) 0-10 micrograms/ml. Before treatment, levels of TNF were higher in LPS-stimulated RA monocyte cultures than in the control cultures; differences were statistically significant in LPS 10 and 0.01 micrograms/ml. At 6 months, respective differences were not significant. Levels of TNF before treatment did not correlate to clinical or laboratory parameters of inflammation, or development of erosions. The results indicate that monocytes of patients with early RA are primed, and that the state of priming decreases during treatment.