Cytokines in rheumatoid arthritis

Potential therapeutic targets of macrophages in inhibiting immune damage and fibrotic processes in musculoskeletal diseases

Macrophages are a heterogeneous cell type with high plasticity, exhibiting unique activation characteristics that modulate the progression and resolution of diseases, serving as a key mediator in maintaining tissue homeostasis. Macrophages display a variety of activation states in response to stimuli in the local environment, with their subpopulations and biological functions being dependent on the local microenvironment. Resident tissue macrophages exhibit distinct transcriptional profiles and functions, all of which are essential for maintaining internal homeostasis. Dysfunctional macrophage subpopulations, or an imbalance in the M1/M2 subpopulation ratio, contribute to the pathogenesis of diseases. In skeletal muscle disorders, immune and inflammatory damage, as well as fibrosis induced by macrophages, are prominent pathological features. Therefore, targeting macrophages is of great significance for maintaining tissue homeostasis and treating skeletal muscle disorders. In this review, we discuss the receptor-ligand interactions regulating macrophages and identify potential targets for inhibiting collateral damage and fibrosis in skeletal muscle disorders. Furthermore, we explore strategies for modulating macrophages to maintain tissue homeostasis.

How Rheumatoid Arthritis Can Result from Provocation of the Immune System by Microorganisms and Viruses

The pathogenesis of rheumatoid arthritis (RA), similar to development of a majority of inflammatory and autoimmune disorders, is largely due to an inappropriate or inadequate immune response to environmental challenges. Among these challenges, infectious agents are the undisputed leaders. Since the 1870s, an impressive list of microorganisms suspected of provoking RA has formed, and the list is still growing. Although a definite causative link between a specific infectious agent and the disease has not been established, several arguments support such a possibility. First, in the absence of a defined pathogen, the spectrum of triggering agents may include polymicrobial communities or the cumulative effect of several bacterial/viral factors. Second, the range of infectious episodes (i.e., clinical manifestations caused by pathogens) may vary in the process of RA development from preclinical to late-stage disease. Third, infectious agents might not trigger RA in all cases, but trigger it in a certain subset of the cases, or the disease onset may arise from an unfortunate combination of infections along with, for example, psychological stress and/or chronic joint tissue microtrauma. Fourth, genetic differences may have a role in the disease onset. In this review, two aspects of the problem of “microorganisms and RA” are debated. First, is there an acquired immune deficiency and, in turn, susceptibility to infections in RA patients due to the too frequent and too lengthy infections, which at last break the tolerance of self antigens? Or, second, is there a congenital deficiency in tolerance and inflammation control, which may occur even with ordinary infection frequency and duration?

Effects of low-dose-gamma rays on the immune system of different animal models of disease

We reviewed the beneficial or harmful effects of low-dose ionizing radiation on several diseases based on a search of the literature. The attenuation of autoimmune manifestations in animal disease models irradiated with low-dose γ-rays was previously reported by several research groups, whereas the exacerbation of allergic manifestations was described by others. Based on a detailed examination of the literature, we divided animal disease models into two groups: one group consisting of collagen-induced arthritis (CIA), experimental encephalomyelitis (EAE), and systemic lupus erythematosus, the pathologies of which were attenuated by low-dose irradiation, and another group consisting of atopic dermatitis, asthma, and Hashimoto's thyroiditis, the pathologies of which were exacerbated by low-dose irradiation. The same biological indicators, such as cytokine levels and T-cell subpopulations, were examined in these studies. Low-dose irradiation reduced inter-feron (IFN)-gamma (γ) and interleukin (IL)-6 levels and increased IL-5 levels and the percentage of CD4(+)CD25(+)Foxp3(+)Treg cells in almost all immunological disease cases examined. Variations in these biological indicators were attributed to the attenuation or exacerbation of the disease's manifestation. We concluded that autoimmune diseases caused by autoantibodies were attenuated by low-dose irradiation, whereas diseases caused by antibodies against external antigens, such as atopic dermatitis, were exacerbated.

Ameliorative effect of Drynaria quercifolia (L.) J. Sm., an ethnomedicinal plant, in arthritic animals

Drynaria quercifolia (L.) J. Sm., is an ethnomedicinal plant used widely in Tamil Nadu to treat arthritis. The present study was aimed to evaluate the traditional claim of D. quercifolia rhizome water extract in adjuvant induced arthritic animals. Anti-arthritic effect was studied by assessing the levels of lysosomal enzymes, protein bound carbohydrates, urinary degradative collagen and serum cytokines on control and adjuvant induced arthritis. The paw swelling and body weight were also analyzed. The levels of ROS and lysosomal enzymes in neutrophils of control and adjuvant induced animals were also estimated. D. quercifolia rhizome water extract at doses of 100 and 200mg/kg reduced the paw thickness and elevated the mean body weight of arthritic rats. The treatment with extract showed a significant reduction in the levels of plasma and liver lysosomal enzymes as well as protein bound carbohydrates and urinary degradative collagen levels. The treatment reduced the levels of ROS and lysosomal enzymes in neutrophils significantly. The significant reduction in the levels of serum pro-inflammatory cytokines (TNF-α and IL-1β) and the increment in the levels of anti-inflammatory cytokine (IL-10) were also observed by the treatment. The present study supports the traditional claim of using D. quercifolia to treat rheumatism.

Phospholipase A(2) Activity in Gingival Crevicular Fluid from Patients with Periodontal Disease: A possible Marker of Disease Activity

The activity of phospholipase A₂ in human gingival crevicular fluid (GCF) associated with periodontal disease was demonstrated. Based upon the presence or absence of bleeding on probing (BOP), which is a marker for the disease activity, there were higher levels of the enzyme activity in BOP positive, than in negative sites. When the BOP positive sites became negative after periodontal therapy, the enzyme activity decreased dramatically to almost undetectable levels. There were no significant differences between the activity before and after treatment when the BOP positive sites remained unchanged. These results suggest that the activity in GCF reflects periodontal disease conditions and that it can be used as a marker for disease activity.

Effects of Polycan, a β-glucan, on experimental periodontitis and alveolar bone loss in Sprague-Dawley rats

BACKGROUND AND OBJECTIVE

Polycan is a promising candidate for the treatment of periodontal disease. This study was undertaken to examine whether Polycan, a type of β-glucan, has a protective effect on ligature-induced experimental periodontitis and related alveolar bone loss in Sprague-Dawley rats.

MATERIAL AND METHODS

 Polycan was orally administered, daily, for 10 d, at 21.25, 42.5 or 85 mg/kg, beginning 1 d after ligation. Changes in body weight and alveolar bone loss were monitored, and the anti-inflammatory effects of Polycan were determined by measuring the levels of myeloperoxidase (MPO), interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in gingival tissue. We also evaluated inducible nitric oxide synthase (iNOS) activity and malondialdehyde (MDA) concentrations as a measure of the antioxidant effect.

RESULTS

Ligature placement led to a marked decrease in body weight, increased alveolar bone loss and increased concentrations of MPO, IL-1β, TNF-α and MDA, as well as increased iNOS activity and inflammatory cell infiltration and decreased collagen-fiber content. Histological examination revealed increases in the number and activity of osteoclast cells, decreases in alveolar bone volume and elevated percentages of osteclasts on the alveolar bone surface. Daily oral treatment with 42.5 or 85 mg/kg of Polycan for 10 d led to significant, dose-dependent inhibition of the effect of ligature placement.

CONCLUSION

Taken together, these results suggest that 10 d of oral treatment with Polycan effectively inhibits ligature placement-induced periodontitis and related alveolar bone loss via an antioxidant effect.

Small-molecule inhibitors of IL-2/IL-2R: lessons learned and applied

The IL-2:IL-2R protein-protein interaction is of central importance to both healthy and diseased immune responses, and is one of the earliest examples of successful small-molecule inhibitor discovery against this target class. Drug-like inhibitors of IL-2 have been identified through a combination of fragment discovery, structure-based design, and medicinal chemistry; this discovery approach illustrates the importance of using a diverse range of complementary screening methods and analytical tools to achieve a comprehensive understanding of molecular recognition. The IL-2 story also provides insight into the dynamic nature of protein-protein interaction surfaces, their potential druggability, and the physical and chemical properties of effective small-molecule ligands. These lessons, from IL-2 and similar discovery programs, underscore an increasing awareness of the principles governing the development of drugs for protein-protein interactions.

TNF-alpha-induced aquaporin 9 in synoviocytes from patients with OA and RA

OBJECTIVES

To determine whether aquaporins (AQPs) are expressed in the synovial tissues of patients with OA and RA, and to examine the patterns of expression in patients with and without hydrarthrosis.

METHODS

AQPs were detected in synovial tissue samples from patients with OA and RA using RT-PCR and immunohistochemistry. Fibroblast-like synoviocytes (FLSs) from patients with OA and RA were cultured and stimulated with TNF-alpha. The expression of AQPs in FLSs was examined using RT-PCR and western blot analyses and the function of aquaglyceroporins was examined by a glycerol uptake assay.

RESULTS

AQP1, -3 and -9 mRNAs were expressed in synovial tissues from patients with OA and RA. AQP1, -3 and -9 proteins were also detected by immunohistochemistry. AQP9 mRNA was expressed more strongly in the synovial tissues of OA patients with hydrarthrosis than those without. AQP9 mRNA and protein expression were strongly induced with TNF-alpha treatment in FLSs, whereas the expression of AQP1 and -3 mRNAs was not induced with TNF-alpha treatment. AQP9 as an aquaglyceroporin was induced by TNF-alpha.

CONCLUSIONS

AQP9 mRNA was detected in synovial tissues from OA and RA patients with hydrarthrosis. AQP9 expression was strongly induced in FLSs with TNF-alpha. Although the functions of AQP1, -3 and -9 in synovial tissues remain to be elucidated, it suggested that AQP9 might be related to the pathogenesis of hydrarthrosis and inflammatory synovitis.

AAV2/1-TNFR:Fc gene delivery prevents periodontal disease progression

Periodontal disease is a chronic inflammatory condition induced by tooth-associated microbial biofilms that induce a host immune response. Therapeutic control of progressive tissue destruction in high-risk patients is a significant challenge in therapy. Soluble protein delivery of antagonists to tumor necrosis factor alpha (TNF-α) inhibits alveolar bone resorption due to periodontitis. However, protein therapy raises several concerns, such as recurrence of disease activity after treatment cessation and repeated dosing regimens. In this study, we used pseudotyped adeno-associated virus vector based on serotype 1 (AAV2/1) to deliver the TNF receptor-immunoglobulin Fc (TNFR:Fc) fusion gene to rats subjected to experimental Porphyromonas gingivalis (Pg)-lipopolysaccharide (LPS)-mediated bone loss. Animals received Pg-LPS delivered to the gingivae thrice weekly for 8 weeks, vehicle alone, Pg-LPS and intramuscular delivery of pseudotyped AAV2/1-TNFR:Fc vector (1×10¹¹ DNase I-resistant particles) or AAV2/1-TNFR:Fc vector delivered to naïve animals. AAV2/1-TNFR:Fc therapy led to sustained therapeutic levels of serum TNFR protein and protected against Pg-LPS-mediated loss of bone volume and density. Furthermore, AAV2/1-TNFR:Fc administration reduced local levels of multiple pro-inflammatory cytokines and osteoclast-like cells at the periodontal lesions. These findings suggest that delivery of AAV2/1-TNFR:Fc may be a viable approach to modulate periodontal disease progression.

Strain differences regarding susceptibility to ursolic acid-induced interleukin-1beta release in murine macrophages

Interleukin (IL)-1beta is a proinflammatory cytokine responsible for the onset of a broad range of diseases, such as inflammatory bowel disease and rheumatoid arthritis. We have recently found that aggregated ursolic acid (UA), a triterpene carboxylic acid, is recognized by CD36 for generating reactive oxygen species (ROS) via NADPH oxidase (NOX) activation, thereby releasing IL-1beta protein from murine peritoneal macrophages (pMphi) in female ICR mice. In the present study, we investigated the ability of UA for inducing IL-1beta production in pMphi from 4 different strains of female mice (C57BL/6J, C3H/He, DDY, and ICR), as well as an established macrophage line (RAW264.7 cells). The levels of IL-1beta released from UA-treated pMphi of C57BL/6J and DDY mice were significantly lower than from those of ICR mice, whereas IL-1beta was not released from the pMphi of C3H/He mice or RAW264.7 cells. Of paramount importance, CD36 as well as the NOX components gp91phox and p47phox (C3H/He mice) and gp91phox (RAW264.7 cells) were scarcely detected. In addition, the different susceptibilities to UA-induced IL-1beta release were suggested to be correlated with the amount of superoxide anion (O2-) generated from the 5 different types of Mphi. Notably, intracellular, but not extracellular, O2- generation was indicated to play a major role in UA-induced IL-1beta release. Together, our results indicate that the UA-induced IL-1beta release was strain-dependent, and the expression status of CD36 and gp91phox is strongly associated with inducibility.

Expression of large tenascin-C splice variants in synovial fluid of patients with rheumatoid arthritis

Tenascin-C (TN-C) is a hexameric glycoprotein component of extracellular matrix, and alternative RNA splicing creates two major TN-C size variants (the small and large variants). The large TN-C variants play key roles in many pathologic conditions in adults, including tumorigenesis, regeneration, and inflammation. This cross-sectional study compared levels of large TN-C variants in synovial fluid of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Synovial fluid samples were obtained from knees of 26 patients with advanced RA and 79 with advanced OA. Expression of TN-C splice variants was examined using Western blotting. The levels of large TN-C variants in synovial fluid were determined by an enzyme-linked immunosorbent assay. Synovium were analyzed for TN-C by immunohistochemistry. Immunoblotting showed the presence of large TN-C variants in synovial fluid from patients with RA and OA. However, levels of large TN-C variants were fourfold higher in RA samples compared with OA samples (p < 0.01). Synovial fluid levels of TN-C in RA did not correlate with C-reactive protein levels. Immunohistochemistry of the synovium showed stronger reactivity in RA samples than in OA samples. These results indicate that local synthesis of TN-C is increased during rheumatic disease.

Paraoxonase and arylesterase levels in rheumatoid arthritis

It was reported that lipid peroxidation (LPO) products increase in rheumatoid arthritis (RA) patients and increased LPO products reduce many antioxidants. Lipid hydroperoxides (LOOHs) are byproduct of LPO. Paraoxonase (PON), arylesterase (ARE), free sulfhydryl (SH) groups, and ceruloplasmin (CP) are enzymes or proteins with antioxidant characteristics. This study aims to determine the levels of LOOHs and SH, and the activities of PON1, ARE, and CP in RA patients. The study included 47 active RA cases and 23 healthy volunteers. The levels of LOOHs and SH, and the activities of PON1, ARE, and CP were determined using appropriate methods. Student's t test and Spearman's correlation analysis methods were employed in the statistical evaluation. The level of LOOHs was found to be higher (p<0.001), while the level of SH and the activities of PON1, ARE, and CP were found to be lower (p<0.001, <0.001, <0.01, and <0.01, respectively) in the RA patient group when compared with the control group. There was a negative correlation between the level of LOOHs and the activity of PON1 in the patient group (r= -0.420 and p<0.01). The results of our study indicate increased oxidant and decreased antioxidant presence in RA patients. PON1 and ARE are known to have antiatherosclerotic effects in addition to their antioxidant characteristics. As the decrease in these antioxidants, resulting from increased oxidative stress in RA patients, development of atherosclerosis besides tissue injury seems inevitable.

Actinobacillus actinomycetemcomitans Y4 capsular polysaccharide induces IL-1beta mRNA expression through the JNK pathway in differentiated THP-1 cells

Capsular polysaccharide from Actinobacillus actinomycetemcomitans Y4 (Y4 CP) induces bone resorption in a mouse organ culture system and osteoclast formation in mouse bone marrow cultures, as reported in previous studies. We also found that Y4 CP inhibits the release of interleukin (IL)-6 and IL-8 from human gingival fibroblast (HGF). Thus Y4 CP induces various responses in localized tissue and leads to the secretion of several cytokines. However, the effects of Y4 CP on human monocytes/macrophages are still unclear. In this study, THP-1 cells, which are a human monocytic cell line, were stimulated with Y4 CP, and we measured gene expression in inflammatory cytokine and signal transduction pathways. IL-1beta and tumour necrosis factor (TNF)-alpha mRNA were induced from Y4 CP-treated THP-1 cells. IL-1beta mRNA expression was increased according to the dose of Y4 CP, and in a time-dependent manner. IL-1beta mRNA expression induced by Y4 CP (100 microg/ml) was approximately 7- to 10-fold greater than that in the control by real-time PCR analysis. Furthermore, neither PD98059, a specific inhibitor of extracellular signal-regulated kinase nor SB203580, a specific inhibitor of p38 kinase prevented the IL-1beta expression induced by Y4 CP. However, JNK Inhibitor II, a specific inhibitor of c-Jun N-terminal kinase (JNK) prevented the IL-1beta mRNA expression induced by Y4 CP in a concentration-dependent manner. These results indicate that Y4 CP-mediated JNK pathways play an important role in the regulation of IL-1beta mRNA. Therefore, Y4 CP-transduced signals for IL-1beta induction in the antibacterial action of macrophages may provide a therapeutic strategy for periodontitis.

Platelet-derived growth factor-AA increases IL-1beta and IL-8 expression and activates NF-kappaB in rheumatoid fibroblast-like synoviocytes

The effect of platelet-derived growth factor (PDGF)-AA on the inflammation in rheumatoid arthritis (RA) and osteoarthritis (OA) was investigated using cultured fibroblast-like synoviocytes (FLS) obtained from RA and OA patients as well as control nonarthritic (NA) individuals. PDGF-AA increased the mRNA and protein expressions of proinflammatory cytokines, interleukin (IL)-1beta and IL-8 in RA FLS. Biological activity of IL-1 in the culture supernatant of RA FLS was also increased by PDGF-AA stimulation. Interestingly, PDGF-AA synergized with tumour necrosis factor (TNF)-alpha to upregulate the protein expressions of IL-1beta and IL-8. PDGF-induced enhancement of the IL-1beta and IL-8 mRNA expressions was also observed in OA FLS. However, the expression of these proinflammatory cytokines in NA FLS did not change by PDGF treatment, suggesting that the inflammatory condition might have modified the biological effects of PDGF. In accordance with the enhanced expression of inflammatory cytokines, the activity of nuclear factor kappaB was also induced in response to PDGF-AA in RA FLS. These results suggest that PDGF-AA plays an important role in the progression of RA inflammation, and inhibiting PDGF activity may be useful for the effective RA treatment.

Secretion of oncostatin M by neutrophils in rheumatoid arthritis

OBJECTIVE

Neutrophils are known to express and release a large number of proinflammatory cytokines when they are stimulated by inflammatory stimuli. The objective of this study was to determine whether neutrophils express oncostatin M (OSM), a member of the interleukin-6 family of cytokines that has been implicated in the pathogenesis of inflammatory joint disease.

METHODS

Neutrophils were isolated from the blood of healthy volunteer donors and from the blood and synovial fluid of patients with rheumatoid arthritis (RA). OSM levels were measured in cell extracts and in culture supernatants by Western blotting. Total RNA was isolated from control and granulocyte-macrophage colony-stimulating factor (GM-CSF)-treated neutrophils, and OSM messenger RNA levels were quantified by hybridization of a radiolabeled probe.

RESULTS

GM-CSF stimulated a rapid and transient expression and release of OSM from blood neutrophils, which was more rapid than the expression and release from blood monocytes. A 28-kd protein was identified in cell extracts, but an additional 25-kd isoform was detected in culture supernatants. Synovial fluid neutrophils could not be stimulated to express OSM, but this cytokine was detected in cell-free supernatants at various levels.

CONCLUSION

Blood neutrophils can be stimulated to express and rapidly release large quantities of OSM. We propose that this important cytokine is released from neutrophils as they infiltrate rheumatoid joints and, thus, contribute to the complex cytokine network that characterizes RA.

Th1 Cytokines Regulate Adenosine Receptors and Their Downstream Signaling Elements in Human Microvascular Endothelial Cells

We and others have shown that adenosine, acting at its receptors, is a potent modulator of inflammation and angiogenesis. To better understand the regulation of adenosine receptors during these processes we studied the effects of IL-1, TNF-alpha, and IFN-gamma on expression and function of adenosine receptors and select members of their coupling G proteins in human dermal microvascular endothelial cells (HMVEC). HMVEC expressed message and protein for A(2A) and A(2B), but not A(1) or A(3) receptors. IL-1 and TNF-alpha treatment increased message and protein expression of A(2A) and A(2B) receptor. IFN-gamma treatment also increased the expression of A(2B) receptors, but decreased expression of A(2A) receptors. Resting HMVEC and IFN-gamma-treated cells showed minimal cAMP response to the selective A(2A) receptor agonist 2-[2-(4-chlorophenyl)ethoxy]adenosine (MRE0094). In contrast, MRE0094 stimulated a dose-dependent increase in cAMP levels in TNF-alpha-treated cells that was almost completely blocked by the A(2A) receptor antagonist ZM-241385 (4-[2-[7-amino-2-(2-furyl)[1,2,4]triazolo-[2,3-a][1,3,5]triazin-5-ylamino]ethyl]phenol). The nonselective adenosine receptor agonist 5'-(N-ethylcarboxamido)adenosine increased cAMP levels in both TNF-alpha- and IFN-gamma-treated cells, but not control cells, and its effect was only partially reversed by ZM-241385 in TNF-alpha-treated cells and not affected in IFN-gamma-treated cells. HMVEC expressed a higher level of G protein beta1 isoform than beta4 isoform. Although none of the cytokines tested affected G(beta1) expression, both IL-1 and TNF-alpha significantly up-regulated G(beta4) expression. These findings indicate that inflammatory cytokines modulate adenosine receptor expression and function on HMVECs and suggest that the interaction between proinflammatory cytokines and adenosine receptors may affect therapeutic responses to anti-inflammatory drugs that act via adenosine-dependent mechanisms.

Cortisol responses to mild psychological stress are inversely associated with proinflammatory cytokines

Glucocorticoids can down-regulate immune activity, but acute stress has been reported to increase both cortisol and levels of plasma cytokines. We investigated individual differences in cortisol responses and their associations with proinflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1ra), cardiovascular activity, and mental health. Saliva samples and blood were taken from 199 healthy middle-aged participants of the Whitehall II cohort at baseline, immediately after stress and 45 min later. We defined the 40% of participants with the highest cortisol response to stress as the cortisol responder group and 40% with the lowest response as the cortisol non-responder group. Plasma IL-6 was higher and the IL-1ra response to stress was greater in the cortisol non-responder group. The cortisol non-responders showed lower heart rate variability than the cortisol responders. The cortisol responder group experienced more subjective stress during the tasks and reported more impaired mental health than the non-responders. We conclude that individual variations in neuroendocrine stress responsivity may have an impact on proinflammatory cytokines, and that both high and low cortisol stress responsiveness has potentially adverse effects.

IL1-beta and TNF-alpha induce changes in the nuclear polyphosphoinositide signalling system in osteoblasts similar to that occurring in patients with rheumatoid arthritis: an immunochemical and immunocytochemical study

Osteoarthritis (OA) and rheumatoid arthritis (RA) are common joint diseases that can lead to destruction of cartilage and structural changes in the subchondral bone. In this study we show by western blot and quantitative immunocytochemistry that nuclear phospholipase C beta(1) (PLC beta(1)) and phosphatidylinositol 4,5-bisphosphate (PIP(2)), two key elements of the polyphosphoinositide signal transduction system that regulate different cellular processes, increase in primary osteoblast cultures of RA patients when compared with post-traumatic after fall (PT) patients, whilst those of OA are not significantly affected. Moreover, we demonstrate that these alterations could be induced in PT osteoblasts by proinflammatory cytokines IL-1 beta and TNF-alpha. This suggests that proinflammatory cytokines, highly produced by RA infiltrating mononuclear cells, can modulate the nuclear polyphosphoinositide signalling pathway of the osteoblasts involved in bone remodelling.

Augmented binding and activation of latent transforming growth factor-beta by a tryptic fragment of latency associated peptide

Transforming growth factor-beta (TGF-beta) is secreted in a latent form; thus, activation is critical for the control of TGF-beta action. Latent TGF-beta exists in a complex in which mature TGF-beta is noncovalently linked to latency associated peptide (LAP) and latent TGF-beta binding protein (LTBP) complex. We have shown that latent TGF-beta is efficiently activated in heterotypic cultures of endothelial cells (ECs) and smooth muscle cells (SMCs). Under those conditions, LAP plays an important role in targeting latent TGF-beta to the surface of SMCs, and plasmin and calpain target it to the surface of ECs for activation. Here, we demonstrate in a homotypic culture system that fragments of LAP increase the binding of latent TGF-beta to ECs, resulting in its activation by cell-associated proteolysis. LAP fragments appear to bind to the cell surface and augment the binding of latent TGF-beta, independent of transglutaminase. These results suggest a unique mechanism for the activation of latent TGF-beta by proteolytic fragments of LAP. The mechanism may arise from degradation by elevated levels of proteases under certain conditions.

The calcium-binding protein S100A12 induces neutrophil adhesion, migration, and release from bone marrow in mouse at concentrations similar to those found in human inflammatory arthritis

We investigated the proinflammatory activities of S100A12 in the context of synovial inflammation. S100A12 levels were increased in the synovial fluids and plasma of patients with gout, rheumatoid arthritis, psoriatic arthritis, and undetectable in osteoarthritis, a noninflammatory disorder. S100A12 proved to induce neutrophil adhesion to fibrinogen via Mac-1 at concentrations similar to those found in the synovial fluids. Similar concentrations induced the recruitment of large numbers of neutrophils and monocytes in the murine air pouch model. To characterize the effect of increased S100A12 plasma levels, mice were injected intravenously with S100A12. This led to the mobilization of neutrophils from the bone marrow to the peripheral blood. These results suggest that S100A12 stimulates the accumulation of neutrophil by inducing their release from the bone marrow, as well as by activating their adhesion and migration toward inflammatory sites.

The contribution of interleukin-1 and tumor necrosis factor to periodontal tissue destruction

Interleukin (IL)-1 and tumor necrosis factor (TNF) represent proinflammatory cytokines that stimulate a number of events which occur during periodontal disease. These include the induction of adhesion molecules and other mediators that facilitate and amplify the inflammatory response, the stimulation of matrix metalloproteinase, and bone resorption. The activity of these cytokines coincides with the critical events that occur during periodontal disease, namely, loss of attachment and bone resorption. The use of antagonists to IL-1 and TNF in experimental periodontitis have demonstrated a cause-and-effect relationship between the activity of these cytokines and the spread of an inflammatory front to deeper areas in the connective tissue, loss of connective tissue attachment, osteoclast formation, and loss of alveolar bone. In addition, the loss of fibroblasts that occurs during infection with periodontal pathogens is, in part, mediated by TNF. Thus, much of the damage that occurs during periodontal tissue destruction can be attributed to IL-1 and TNF activity. This destruction may very well represent an overreaction of the host response to periodontal pathogens caused by excessive production of IL-1 and TNF.

Role of macrophages in experimental group B streptococcal arthritis

Septic arthritis is a clinical manifestation of group B Streptococcus (GBS) infection in both neonates and adults. Because macrophages are known to participate in tissue injury, the role of this cell population in GBS-induced arthritis was investigated. Mice were rendered monocytopenic by administration of etoposide, a drug that selectively depletes the monocyte/macrophage population and then injected with GBS (1 x 10(7) colony-forming units per mouse). Appearance of arthritis, mortality, GBS growth in the organs, and local and systemic cytokine production were examined. Etoposide-treated mice had a significantly less severe arthritis than control animals. Histopathological analysis of the joints confirmed clinical observations. Decreased joint levels of the proinflammatory cytokines interleukin 1 (IL-1) beta and IL-6 accompanied the less severe development of arthritis in monocytopenic mice. In contrast, mortality was increased in the etoposide-treated mice compared with controls. Monocytopenic mice exhibited elevated bacterial load in the blood and kidneys at all time points examined. These results indicate that lack of macrophages leads to less severe joint lesions, but also results in impaired clearance of bacteria, and consequent enhancement of mortality rates.

The beneficial effect of interleukin-12 on arthritis induced by group B streptococci is mediated by interferon-gamma and interleukin-10 production

OBJECTIVE

To assess the effect of interleukin-12 (IL-12) administration on the evolution of systemic infection and septic arthritis induced by group B streptococci (GBS) in mice.

METHODS

CD1 mice were inoculated intravenously with arthritogenic strain 1/82 of type IV GBS. Exogenous murine IL-12 was administered intraperitoneally 18 hours or 5 days after infection with 1 x 10(7) GBS, at doses ranging from 0.5 to 2.5 microg per mouse. Mice were monitored daily for survival and for signs of arthritis. In a subsequent set of experiments, mice were killed at selected times for examination of bacterial clearance, histopathologic changes in the joints, and cytokine production.

RESULTS

IL-12 administration before the onset of clinical signs had a beneficial effect on GBS-induced arthritis and was clearly dose-dependent. The 2.5-microg dose per mouse totally prevented death from GBS-induced arthritis. The decrease in pathology was associated with a reduction of the bacterial burden and a change in the cytokine profile. In particular, systemic and joint levels of interferon-gamma (IFN gamma) and IL-10 significantly increased in mice treated with IL-12, whereas a decrease in IL-6 and IL-1 beta production was observed. The beneficial effects of IL-12, in terms of the incidence and severity of articular lesions, were reversed by coadministration of anti-IFN gamma or anti-IL-10-neutralizing antibodies.

CONCLUSION

The findings of this study demonstrate that IL-12 is important in controlling the cytokine production that leads to the evolution of GBS-induced experimental arthritis. The amelioration of articular lesions is mostly attributable to IL-12-induced IFN gamma, but with a relevant participation of IL-12-induced IL-10.

VLA-4-dependent and -independent pathways in cell contact-induced proinflammatory cytokine production by synovial nurse-like cells from rheumatoid arthritis patients

Nurse-like stromal cell lines from the synovial tissue of patients with rheumatoid arthritis (RA-SNC) produce, on coculture with lymphocytes, large amounts of proinflammatory cytokines. In the present paper, we analyze the molecular events necessary for the induction of cytokine release from RA-SNC cells, and particularly the roles played by cell adhesion and the transmigration (also known as pseudoemperipolesis) of lymphocytes. For this purpose, the effects of various mAbs on the binding and transmigration of a human B-cell line, MC/car, were examined using a cloned RA-SNC line, RA-SNC77. To analyze the role of lymphocyte binding and transmigration on upregulated cytokine production by the RA-SNC77 cells, we used C3 exoenzyme-treated MC/car cells, which could bind to RA-SNC77 cells but could not transmigrate. Treatment with anti-CD29 or anti-CD49d mAb significantly reduced binding and transmigration of the MC/car cells. In contrast, the neutralizing anti-CD106/vascular cell adhesion molecule 1 mAb did not show any inhibitory effect. Likewise, none of the neutralizing mAbs against CD11a, CD18, CD44, CD49e, or CD54 showed significant effects. Binding of C3-treated or untreated MC/car cells to RA-SNC77 cells induced comparable levels of IL-6 and IL-8 production. In addition, the enhanced cytokine production by RA-SNC77 cells required direct lymphocyte contact via a very late antigen-4 (VLA-4)-independent adhesion pathway. These results indicate that, although both the VLA-4-dependent/vascular cell adhesion molecule 1-independent and the VLA4-independent adhesion pathways are involved in MC/car binding and subsequent transmigration, only the VLA4-independent adhesion pathway is necessary and sufficient for the enhanced proinflammatory cytokine production by RA-SNC77 cells. The transmigration process, which is dependent on Rho-GTPase, is not a prerequisite for this phenomenon.

Vascular endothelial growth factor expression by activated synovial leukocytes in rheumatoid arthritis: critical involvement of the interaction with synovial fibroblasts

OBJECTIVE

To examine the expression and regulation of the angiogenic factor, vascular endothelial growth factor (VEGF), by fibroblast-like synoviocytes (FLS), monocytes, and polymorphonuclear neutrophils (PMNs) isolated from the synovial fluid (SF) of rheumatoid arthritis (RA) patients.

METHODS

Monocytes or PMNs obtained from RA SF were cocultured with unstimulated, semiconfluent RA FLS. Culture supernatants were assayed for the proliferation and in vitro tube formation of endothelial cells, and for the production of VEGF, by enzyme-linked immunosorbent assay. The expression of VEGF messenger RNA and protein was also determined by reverse transcription-polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

We found that the interaction of inflammatory, activated leukocytes with FLS resulted in synergistic increases in VEGF expression and secretion, which contributed to the proliferation of endothelial cells and to in vitro endothelial tube formation. The induction of VEGF was mediated via specific adhesion molecules, as indicated by the finding that anti-integrin antibodies significantly inhibited VEGF. Furthermore, the levels of VEGF secretion correlated with the expression of cell surface integrin (CD11b and CD18) on both monocytes and PMNs in the SF.

CONCLUSION

VEGF expression within inflamed joints thus appears to be regulated not only by inflammatory cytokines, but also by the physical interaction of activated leukocytes and FLS. Once expressed, VEGF likely plays a crucial role in the neovascularization of the pannus and the progressive joint destruction associated with the synovial inflammation of RA.

Inflammatory cytokines regulate function and expression of adenosine A(2A) receptors in human monocytic THP-1 cells

Adenosine, acting at its receptors, particularly A(2A) receptors, is a potent endogenous anti-inflammatory agent that modulates the functions and differentiation of inflammatory and immune cells. Because the inflammatory milieu abounds in proinflammatory cytokines, we investigated the effects of Th1-inflammatory cytokines on function and expression of adenosine A(2A) receptors in the human monocytic cell line THP-1. We found that, consistent with previous reports, adenosine and 2-[p-(2-carnonylethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenosine (CGS-21680), a selective A(2A) receptor agonist, suppress IL-12 production but increase IL-10 production in LPS-activated THP-1 cells. These effects were blocked by the A(2A) receptor antagonist 4-(2-[7-amino-2-(2-furyl)[1,2,4-triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM-241385). More importantly, the suppressive effect of adenosine and CGS-21680 on IL-12 production was significantly enhanced in cells pretreated with either IL-1 (10 U/ml) or TNF-alpha (100 U/ml) but markedly attenuated in cells pretreated with IFN-gamma (100 U/ml). Similarly, IL-1 and TNF-alpha treatment potentiated the stimulatory effect of adenosine and CGS-21680 on IL-10 production, whereas IFN-gamma treatment almost completely abolished this effect. CGS-21680 stimulated an increase in intracellular cAMP in a time- and dose-dependent manner in IL-1- and TNF-alpha-treated cells but not in control or IFN-gamma-treated cells. Both IL-1 and TNF-alpha increased A(2A) receptor mRNA and protein. In parallel with its effect on A(2A) receptor function, IFN-gamma down-regulated A(2A) receptor message and protein. Because adenosine mediates many of the antiinflammatory effects of drugs such as methotrexate, these observations suggest that local changes in the cytokine milieu may influence the therapeutic response to those drugs by altering the expression and function of adenosine receptors on inflammatory cells.

Soluble antagonists to interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibits loss of tissue attachment in experimental periodontitis

BACKGROUND, AIMS

Periodontal disease is a significant cause of tooth loss among adults and is characterized by the alteration and permanent destruction of the deeper periodontal tissues. Although the presence of pathologic microbes is required to trigger this process, the amplification and progression of the diseased state is believed to rely heavily on the production of host mediators in response to bacteria or their metabolic products. The inflammatory response is effective in preventing large-scale colonization of the gingival tissues by bacteria that lie in close proximity to the tooth surface or within the gingival sulcus. It has been postulated that the host-response in some individuals may lead to an over-reaction to invading oral pathogens resulting in the destruction of periodontal tissues.

METHODS

Several host-derived mediators are believed to contribute to this response. Two agents considered to be essential in periodontal destruction are interleukin-1 (IL-1) and tumor necrosis factor (TNF). We investigated the role of IL-1 and TNF in the loss of connective tissue attachment in a Macaca fascicularis primate model of experimental periodontitis. Silk ligatures impregnated with the periodontal pathogen, Porphyromonas gingivalis were wrapped around the posterior teeth and the activity of IL-1 and TNF were inhibited by soluble receptors to these proinflammatory cytokines via local injection into interdental papillae.

RESULTS

Histomorphometric analysis indicates that IL-1 and TNF antagonists significantly reduced the loss of connective tissue attachment by approximately 51% and the loss of alveolar bone height by almost 91%, both of which were statistically significant.

CONCLUSION

This investigation demonstrates that the loss of connective tissue attachment and progression of periodontal disease can be retarded by antagonists to specific host mediators such as IL-1 and TNF and may provide a potential treatment modality to combat the disease process.

Interleukin-6 changes deformability of neutrophils and induces their sequestration in the lung

Interleukin-6 (IL-6) is an important mediator of both the hepatic and the bone marrow components of the acute-phase response. Previous studies from our laboratory have shown that cells released into the circulation from the marrow preferentially sequester in the lung. The present study was designed to examine the mechanism of this sequestration using a single dose of recombinant human IL-6 to stimulate the marrow in rabbits. Marrow release was monitored by labeling polymorphonuclear leukocyte (PMN) precursors in the marrow with the thymidine analogue, 5'-bromo-2-deoxyuridine (BrdU), 24 h before IL-6 treatment. This treatment caused a neutrophilia that was associated with the increase of circulating BrdU- labeled PMN (PMN(BrdU)) and morphometric studies confirmed that PMN(BrdU) released from the marrow preferentially sequestered in the lung microvessels compared to unlabeled PMN. IL-6 treatment increases PMN F-actin content (p < 0.05) that was not due to cell activation by IL-6. In vitro studies show that IL-6 treatment decreased the deformability of circulating PMN (p < 0.05). These studies confirm that IL-6 treatment causes an accelerated release of PMN from the bone marrow and shows that these newly released PMN have high levels of F-actin, are less deformable, and preferentially sequester in lung microvessels.

Influence of interferon-gamma administration on the severity of experimental group B streptococcal arthritis

OBJECTIVE

To assess the effect of interferon-gamma (IFNgamma) administration on the evolution of systemic infection and septic arthritis induced by group B streptococci (GBS) in mice.

METHODS

CD1 mice were inoculated intravenously with arthritogenic strain 1/82 of type IV GBS. Exogenous murine IFNgamma or anti-IFNgamma monoclonal antibodies were administered intravenously either 2 hours (-2 hours) before or 18 hours after infection with 1 x 10(7) GBS. Mice were monitored daily for survival and for signs of arthritis. In a subsequent set of experiments, mice were killed at selected times for examination of bacterial clearance, joint histopathology, and cytokine production.

RESULTS

Mortality in mice treated with IFNgamma at -2 hours was 100%, compared with 20% in those treated at 18 hours and with 40% in controls. As indicated by the arthritis score, mice treated with IFNgamma at -2 hours developed early and more severe arthritis, whereas those treated at 18 hours had milder arthritis compared with infected controls. Less severe joint pathology in the mice treated with IFNgamma at 18 hours correlated with low levels of interleukin-6 (IL-6) and IL-1beta and a low bacterial load in the joints, whereas rapid onset and worsening of articular lesions in those treated at -2 hours corresponded to early and sustained levels of IL-6.

CONCLUSION

The findings of this study demonstrate that the effects mediated by IFNgamma on GBS-induced arthritis may be detrimental or beneficial, depending on the time of administration of IFNgamma in relation to infection with the antigen.

Interleukin-6 induces demargination of intravascular neutrophils and shortens their transit in marrow

Recombinant human interleukin-6 (IL-6) causes both a thrombocytosis and leukocytosis. The thrombocytosis is caused by an accelerating thrombocytopoiesis, but the mechanism of the leukocytosis is unknown. This study was designed to determine the relative contributions of marrow stimulation and intravascular demargination to the IL-6 induced neutrophilia. IL-6 (2 microgram/kg), administered intravenously to rabbits, caused a biphasic neutrophilia with an initial peak at 3 h and a second peak at 9 h. Using the thymidine analog 5'-bromo-2'-deoxyuridine (BrdU) to label dividing polymorphonuclear leukocytes (PMNs) in the bone marrow, we showed that IL-6 treatment mobilizes PMNs from the marginated pool into the circulating pool at 2-6 h with a decrease in L-selectin expression on PMNs and also accelerates the release of PMNs from the postmitotic pool in the bone marrow at 12-24 h. We have concluded that IL-6 causes a biphasic neutrophilia wherein the first peak results from the mobilization of PMNs into the circulating pool from the marginated pool and the second peak results from an accelerated bone marrow release of PMNs.

Human Rheumatoid Factor Production Is Dependent on CD40 Signaling and Autoantigen

High-affinity pathologic rheumatoid factor (RF) B cells occur in autoimmune diseases such as rheumatoid arthritis, but are deleted in healthy individuals. The reasons for the survival and differentiation of these autoreactive B cells in rheumatoid arthritis are not known. Previous studies in mice transgenic for a human IgM RF have shown that peripheral encounter with soluble human IgG leads to deletion of high-affinity RF B cells; however, deletion can be prevented when concomitant T cell help is provided. This study aimed to further discern the minimal factors necessary not only for the in vivo survival of RF B cells, but also for their differentiation into Ab-secreting cells. The combination of MHC class II-reactive T cells and Ag induced the production of RF in human IgM RF transgenic mice, while either stimulus alone was ineffective. Neutralizing Abs against CD40 ligand (CD40L), but not against IL-4 or IL-15, abrogated IgM-RF production. Moreover, blockade of CD40L-CD40 allowed IgG to delete the RF precursor cells. Most importantly, activating Abs to CD40 could substitute entirely for T cell help in promoting the survival of RF precursors and in stimulating RF synthesis in T cell deficient animals. The data indicate that CD40 signaling alone can prevent deletion of RF B cells by Ag and in the presence of IgG is sufficient to trigger RF synthesis. The results suggest that selective induction of apoptosis in high-affinity RF B cells may be achieved by blockade of CD40L-CD40 interaction.

Long-term follow-up of cytokines and soluble cytokine receptors in peripheral blood of patients with juvenile rheumatoid arthritis

Plasma levels of interleukin-1beta (IL-1beta), IL-2, soluble IL-2 receptor (sIL-2R), IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), and the p60 soluble TNF receptor (sTNFR) were repeatedly determined by enzyme-linked immunosorbent assays (ELISA) in 35 patients with different subtypes of juvenile rheumatoid arthritis (JRA) during an observation period of up to 36 months. The data were related to conventional inflammatory parameters and disease activity. Patients with systemic disease showed the most pronounced elevations of plasma cytokines, followed by polyarticular and pauciarticular JRA. Soluble receptors sIL-2R and sTNFR were consistently elevated in patients of all JRA subtypes and indicated disease activity even in patients with normal C-reactive protein (CRP). In contrast, the determination of IL-1beta, IL-2, IL-8, and TNF-alpha revealed strikingly different individual profiles in patients of the same clinical subtype of JRA and irrespective of disease activity. It is concluded that the determination of sIL-2R and sTNFR may be relevant for monitoring JRA, as they indicate disease activity also in cases with unaltered conventional inflammatory parameters. The different individual cytokine profiles of patients within identical subtypes of disease suggest JRA to be even more heterogeneous than hitherto assumed. The data should be considered in attempts to develop anticytokine strategies in the therapy of JRA.

Role of tumor necrosis factor alpha, interleukin-1beta, and interleukin-6 in a mouse model of group B streptococcal arthritis

Intravenous inoculation of CD1 mice with 10(7) CFU of type IV group B Streptococcus (GBS IV) results in a high incidence of diffuse septic arthritis. In this study the roles of tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 in articular pathology were evaluated. Cytokine levels were quantified in the serum and joints by enzyme-linked immunosorbent assay in mice injected with GBS IV and tested or not tested with pentoxifylline (PTF), a methylxanthine that affects cytokine production. PTF was administered intraperitoneally at a dose of 1 mg/mouse (50 mg/kg of body weight) 1 h after GBS infection and then at 24-h intervals for 4 days. High levels of IL-1beta and IL-6, but not TNF-alpha, were detected in the joints of mice injected with GBS IV from 5 to 15 days after infection, when articular lesions were most frequent and severe. IL-1beta and IL-6 concentrations in the joints significantly (P < 0.001) exceeded those detected in the serum, confirming a strong local production. PTF treatment resulted in a strong reduction of cytokine production and in a marked decrease in both the incidence and severity of arthritis. Inoculation of exogenous murine recombinant IL-1beta or IL-6 in mice treated with GBS IV plus PTF resulted in an incidence and severity of articular lesions similar to those obtained with inoculation of GBS IV alone. No significant effect was obtained with TNF-alpha administration. These data show a strong involvement of IL-1beta and IL-6, but not TNF-alpha, in the pathogenesis of GBS arthritis.

Interleukin-1 and tumor necrosis factor antagonists inhibit the progression of inflammatory cell infiltration toward alveolar bone in experimental periodontitis

Periodontal disease is a significant cause of tooth loss in humans and is one of the most prevalent diseases associated with bone loss. Following bacterial colonization, the gingiva becomes inflamed and, in some cases, progresses to destruction of alveolar bone. To investigate the temporal movement of inflammatory cells toward alveolar bone and the role of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in this process, studies were carried out in a Macaca fascicularis primate model of experimental periodontitis. IL-1 and TNF activity was inhibited by local application of soluble receptors to IL-1 and TNF by injection into interdental papillae. The results indicate that following induction of experimental periodontitis, the front of inflammatory cells progresses toward alveolar bone and is associated with osteoclast formation. These processes are inhibited by blockers to IL-1 and TNF. These studies suggest that the conversion from gingivitis to periodontitis is directly associated with the movement of an inflammatory infiltrate toward alveolar bone, and that this activity is at least partially dependent upon IL-1 and/ or TNF.

Dietary fish oil alters specific and inflammatory immune responses in chicks

Two experiments were designed to determine the effects of dietary (n-3) fatty acids and grain source on the growth-suppressive effects of the inflammatory response and indices of specific immunity. In Experiment 1, chicks were fed diets containing 0.5, 1, or 2 g/100 g of either corn oil or fish oil. In Experiment 2, chicks were fed diets containing up to 2 g/100 g of either fish oil, linseed oil or corn oil as the source of dietary fat, in either cereal grain- or corn-based diets. In each experiment, subsets of chicks within each dietary treatment were either vaccinated with infectious bronchitis virus (IBV) vaccine, injected with Salmonella typhimurium lipopolysaccharide (LPS), heat-killed Staphylococcus aureus, or remained noninjected. Increasing dietary fish oil, but not corn oil increased body weight and lessened the growth-suppressing effect of heat-killed S. aureus or S. typhimurium LPS. Increasing the concentration of dietary fish oil decreased febrile response, circulating hemopexin and metallothionein concentrations. Dietary fish oil resulted in decreased release relative to dietary corn oil of interleukin-1 by peritoneal macrophages. Although IBV titers were not significantly affected by dietary oil treatment, phytohemagglutination-induced wattle swelling was greater among chicks fed fish oil. In Experiment 2, the modulating effects of fish oil on the immune system were dependent on the type of grain used in the diet, with fish oil/cereal diets resulting in greater cell-mediated immunity and lower indices of inflammation than fish oil/corn diets. Inclusion of increasing amounts of fish oil in the diet improved performance, decreased indices of the inflammatory response and either improved or did not change indices of the specific immune response of growing chicks.

Anti-inflammatory actions of the neuroimmunomodulator alpha-MSH

alpha-melanocyte-stimulating hormone (alpha-MSH) is an endogenous neuroimmunomodulatory peptide that inhibits fever and all major forms of experimental inflammation. In humans, concentrations of alpha-MSH are increased at sites of inflammation, and in plasma in inflammatory disorders and after infection of endotoxin. The effects of this 'anti-cytokine' peptide are mediated through alpha-MSH receptors and regulatory circuits in macrophages and neutrophils, and through descending neural anti-inflammatory pathways that originate from alpha-MSH receptors on neurons within the brain.

Regulation of lysyl oxidase and cyclooxygenase expression in human lung fibroblasts: interactions among TGF-beta, IL-1 beta, and prostaglandin E

Prostaglandin E2, transforming growth factor-beta, and interleukin-1 beta variably regulate the expression of cyclooxygenase 1, cyclooxygenase 2, and lysyl oxidase in IMR90, human embryo lung fibroblasts. Prostaglandin E2 at 100 nM upregulates cyclooxygenase 1 mRNA by approximately three-fold while it downregulates lysyl oxidase mRNA levels. Notably, prostaglandin E2 suppresses the enhancing effect of TGF-beta on basal levels of lysyl oxidase mRNA. These changes in steady state mRNA levels reflect transcriptional level control, at least in part. Corresponding changes are seen in the protein levels of lysyl oxidase, cyclooxygenase 1 and cyclooxygenase 2 and catalytic activities of these enzymes, including net prostaglandin E2 synthesis. Cyclooxygenase 2 mRNA(t1/2, 30 min) is considerably less stable than that of cyclooxygenase 1 (t1/2, 4 h) while lysyl oxidase mRNA is unusually stable (t1/2 > 14 h). Taken together with the differing kinetics with which these genes respond to perturbation by these cytokines, the present results suggest a coordinated, autocrine-like mechanism of regulation of cyclooxygenase 1 and cyclooxygenase 2 and further point to the potential of their metabolic product, prostaglandin E2, to suppress the expression of lysyl oxidase in the inflammatory response to injury.

Evaluation of interleukin-6 in rheumatoid arthritis as an activity criterion

This study evaluated interleukin-6 levels as an activity criterion in rheumatoid arthritis (RA) and compared if with other activity criteria. We evaluated 35 patients with active RA, 31 with inactive RA, and 25 patients with osteoarthritis, in addition to 28 healthy individuals. Serum interleukin-6 levels were higher in active RA patients than in those with inactive RA, or osteoarthritis and healthy individuals (P < 0.001). Serum interleukin-6 levels of patients with active RA were positively correlated with the erythrocyte sedimentation rate, C-reactive protein, and alpha 2-globulin levels (P < 0.001), but there was a negative correlation with serum albumin levels (P < 0.05). We conclude that interleukin-6 can be responsible for both the most systemic manifestations of RA and for its local manifestations.

Alterations in neurokinin 1 receptor gene expression in models of pain and inflammation

Substance P and the related tachykinin peptides are involved in inflammatory processes and in the transmission of sensory nociceptive information. In this article we review the evidence implicating substance P and the neurokinin 1 (NK1) receptor in arthritic disease. We also provide preliminary evidence demonstrating that cultured synoviocytes from a patient with rheumatoid arthritis express NK1 receptor mRNA that can be downregulated by tumor necrosis factor alpha, whereas synoviocytes from a normal patient do not express detectable NK1 receptor mRNA or protein. Data are also presented summarizing recent studies on nociception-induced increases in sensory ganglia of levels of mRNA encoding substance P and increases in dorsal horn NK1 receptor mRNA levels. Morphine pretreatment blocked the increases in dorsal horn NK1 receptor mRNA levels but did not block the nociception-induced substance P encoding mRNA levels in sensory ganglia. These results are discussed with reference to mechanisms that may regulate P turnover and NK1 receptor sensitivity in models of pain and inflammation.