Is disk-related sciatica a TNFalpha-dependent inflammatory disease?
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Humans↗
Biomedical subjects
Cem Gabay
Publications and source records attributed to Cem Gabay.
Delayed resolution of acute inflammation during zymosan-induced arthritis in leptin-deficient mice.
The severity of antigen-induced arthritis (AIA) is decreased in leptin-deficient ob/ob mice. However, joint inflammation in AIA depends on the immune response, which is impaired in ob/ob mice. In the present study we investigated the effects of leptin deficiency on zymosan-induced arthritis (ZIA), which is independent of adaptive immunity. Arthritis was induced by injection of zymosan into the knee joint. Joint swelling was similar after 6 and 24 hours in ob/ob and control mice. However, it remained elevated in ob/ob animals on day 3 whereas values normalized in controls. Histology revealed similar articular lesions in all animals on day 3, but on days 14 and 21 arthritis tended to be more severe in ob/ob mice. The acute phase response, reflected by circulating levels of IL-6 and serum amyloid A, was also more pronounced in ob/ob mice, although corticosterone was significantly elevated in these animals. Similar results were obtained in leptin receptor-deficient db/db mice. Thus, in contrast to AIA, ZIA is not impaired in leptin-deficient animals. On the contrary, resolution of acute inflammation appears to be delayed in the absence of leptin or leptin signalling, suggesting that chronic leptin deficiency interferes with adequate control of the inflammatory response in ZIA.
Acute Disease↗
CD14 is an acute-phase protein.
The origin of soluble CD14 (sCD14) in the circulation is uncertain. To examine whether CD14 could be an acute-phase protein (APP), the levels of sCD14, IL-6, and C-reactive protein were determined by ELISA in serum and synovial fluid (SF) of patients with various arthropathies, and the regulation of CD14 synthesis was examined in liver cells. In patients with crystal-mediated or immunologically mediated arthritis (rheumatoid arthritis), serum levels of sCD14 were higher than or similar to those found in infection-mediated arthritis (reactive arthritis), precluding a relation with bacteria exposure. Levels of sCD14 were similar in SF and serum, and did not correlate with the number of SF leukocytes, excluding an important source from leukocyte membrane-bound CD14, by protease-mediated shedding. In contrast, serum levels of sCD14 in patients correlated with those of C-reactive protein, a classical APP, and IL-6, a cytokine known to regulate the synthesis of APP in the liver. Serum levels of sCD14 also correlated with disease activity in rheumatoid arthritis and reactive arthritis patients. IL-6 stimulated the production of CD14 by HepG2 hepatoma cells. By real-time PCR, the inducibility of CD14 by IL-6 was also observed at the mRNA level both in HepG2 cells and human primary hepatocytes. These in vitro results were confirmed by in vivo studies in IL-6(-/-) mice injected with turpentine, an experimental model of acute-phase response. Liver levels of CD14 mRNA increased in IL-6(+/+), but not in IL-6(-/-) mice. These results indicate that sCD14 can be considered as a type 2 APP.
Acute-Phase Proteins↗
Production of intracellular IL-1alpha, IL-1beta, and IL-1Ra isoforms by activated human dermal and synovial fibroblasts: phenotypic differences between human dermal and synovial fibroblasts.
We compared the production of IL-1alpha, IL-1beta, and of IL-1Ra isoforms by cultured human dermal (HDF) and synovial fibroblasts (HSF) in response to IL-1alpha, TNF-alpha, or direct T cell membrane contact. IL-1Ra was constitutively present in the cell lysates of cultured HDF and its synthesis increased in stimulated cells, whereas IL-1Ra was present in low amounts in the supernatants. Secreted IL-1Ra (sIL-1Ra) and intracellular IL-1Ra type 1 (icIL-1Ra1) mRNA levels followed the same pattern. In stimulated HDF, IL-1alpha and IL-1beta were increased intracellularly but remained undetectable in the supernatants. In HSF, IL-1Ra levels increased in both cell lysates and supernatants upon stimulation. IL-1beta was only present in HSF cell lysates after stimulation, whereas IL-1alpha was undetectable. Both sIL-1Ra and icIL-1Ra1 mRNAs were detected in stimulated HSF. icIL-1Ra1 was the predominant intracellular isoform in both cell types. In conclusion, stimulated HDF produce high amounts of intracellular IL-1Ra, IL-1alpha, and IL-1beta. In contrast, HSF synthesized both intracellular and secreted IL-1Ra, whereas IL-1beta was present only in cell lysates. The presence of high amounts of icIL-1Ra1 and intracellular IL-1alpha in HDF suggests that these cytokines may carry out important function inside cells.
Blotting, Western↗
The active metabolite of leflunomide, A77 1726, increases the production of IL-1 receptor antagonist in human synovial fibroblasts and articular chondrocytes.
Leflunomide is an immunomodulatory agent used for the treatment of rheumatoid arthritis. In this study, we investigated the effect of A77 1726 - the active metabolite of leflunomide - on the production of IL-1 receptor antagonist (IL-1Ra) by human synovial fibroblasts and articular chondrocytes. Cells were incubated with A77 1726 alone or in combination with proinflammatory cytokines. IL-1Ra production was determined by ELISA. A77 1726 alone had no effect, but in the presence of IL-1beta or tumour necrosis factor-alpha it markedly enhanced the secretion of IL-1Ra in synovial fibroblasts and chondrocytes. The effect of A77 1726 was greatest at 100 micromol/l. In synovial fibroblasts and de-differentiated chondrocytes, A77 1726 also increased IL-1beta-induced IL-1Ra production in cell lysates. Freshly isolated chondrocytes contained no significant amounts of intracellular IL-1Ra. A77 1726 is a known inhibitor of pyrimidine synthesis and cyclo-oxygenase (COX)-2 activity. Addition of exogenous uridine did not significantly modify the effect of A77 1726 on IL-1Ra production, suggesting that it was not mediated by inhibition of pyrimidine synthesis. Indomethacin increased IL-1beta-induced IL-1Ra secretion in synovial fibroblasts and de-differentiated chondrocytes, suggesting that inhibition of COX-2 may indeed enhance IL-1beta-induced IL-1Ra production. However, the stimulatory effect of indomethacin was consistently less effective than that of A77 1726. A77 1726 increases IL-1Ra production by synovial fibroblasts and chondrocytes in the presence of proinflammatory cytokines, and thus it may possess chondroprotective effects. The effect of A77 1726 may be partially mediated by inhibition of COX-2, but other mechanisms likely concur to stimulate IL-1Ra production.
Adult↗
Assessment of the efficacy of different statins in murine collagen-induced arthritis.
OBJECTIVE: Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) are widely used lipid-lowering agents. In addition to their well-known effect on cholesterol levels, statins have been reported to display antiinflammatory activities both in vitro and in vivo. In this context, in vivo prophylactic and therapeutic effects of simvastatin were recently demonstrated in mouse collagen-induced arthritis, a well-described experimental model for human rheumatoid arthritis (RA). The aim of this study was to further investigate in vivo effects of 3 different statins, atorvastatin, rosuvastatin, and simvastatin, using the same experimental model. METHODS: Different doses and routes of administration were used for the various statins in an attempt to elicit antiarthritic activity in preventive and curative treatment protocols. RESULTS: Atorvastatin and rosuvastatin had no in vivo efficacy, as indicated by clinical, histologic (synovial hyperplasia, exudate, and cartilage damage), immunologic (anti-type II collagen IgG production), and biochemical (interleukin-6, serum amyloid A, and glucocorticoid production) parameters of inflammation and autoimmunity. The previously described beneficial effects of administration of intraperitoneal simvastatin were reproduced in our experiments, but could be accounted for by very severe side effects of the treatment, leading to increased glucocorticoid levels. CONCLUSION: This work shows that different statins have no effect in a murine model of arthritis, an unexpected observation given the previously described therapeutic effect of statins in immune-mediated inflammatory diseases. It is still unclear whether statins will have benefit in the treatment of RA.
Animals↗
Total hip prosthetic joint infection due to Veillonella species.
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Aged↗
Cytokines in the rheumatic diseases.
Extensive data has accumulated over the last 10 to 15 years to implicate various cytokines in pathways of pathophysiology in rheumatic diseases. Abnormalities in cytokine production are not the cause of these diseases, but reflect continual production by immune and inflammatory cells. Cytokines are heterogeneous and function in an overlapping and redundant network. An important principle to emerge is that the net biologic response in a diseased organ or tissue reflects a balance between the local levels of proinflammatory and anti-inflammatory cytokines and factors. Thus, a chronic disease may result from the excess production of proinflammatory cytokines or the inadequate production of anti-inflammatory cytokines. This article summarizes the role of cytokines in rheumatic diseases by focusing on each disease and the involved pathways of pathophysiology.
Animals↗
[Efficacy of tumor necrosis factor-alpha blockade for severe sciatica?].
The domain of sciatica is at the edge of a mini revolution. For ten years evidence have been accumulating in favour of a local inflammation rather than a pathology resulling only from a nerve compression. This hypothesis has first been strengthened by the discovery of inflammatory mediators in human herniated discs and then by animal models. These models have demonstrated the impossibility for nerve root compression to produce sciatica in the absence of inflammation and the importance of proinflammatory cytokines in this pathology. TNF-alpha have been proved to be the most important inflammatory cytokine and TNF-alpha modulators has been most effective in the treatment of these models. Two pilot studies realized on humans seem to confirm these experimental data. A multicenter randomised, double-blind, placebo controlled study is being planed in Switzerland.
Antibodies, Monoclonal↗
[Review of the protective effects of tumor necrosis factor inhibitors in rheumatoid arthritis].
Rheumatoid arthritis (RA) is a chronic in-flammatory disease with progressive joint damage, generally considered irreversible. A more aggressive therapeutic approach is promoted. Progression of joint damage, gradual functional disability and rate of mortality are lowered by disease modifying antirheumatic drugs (DMARD). Among these, we discuss the relative role of TNF inhibitors and their efficacy on preventing radiographic progression of joint damage. We also touch on the notion of a therapeutic window of opportunity early in the course of RA, as early initiation of aggressive treatment seems to provide a sustained benefit on radiographic progression.
Adalimumab↗
Leptin activates the promoter of the interleukin-1 receptor antagonist through p42/44 mitogen-activated protein kinase and a composite nuclear factor kappa B/PU.1 binding site.
We have recently shown that leptin strongly induces the expression and secretion of the interleukin-1 receptor antagonist (IL-1Ra) [Gabay, Dreyer, Pellegrinelli, Chicheportiche and Meier (2001) J. Clin. Endocrinol. Metab. 86, 783-791] in monocytes. However, the intracellular signalling mechanisms involved remained unknown. We now demonstrate that the activation of the IL-1Ra promoter by leptin is strictly dependent on the presence of the long form of the leptin receptor (OB-Rb), and that it also requires the activation of the p42/44 mitogen-activated protein kinases (MAPKs) as well as the presence of a nuclear factor kappaB (NF-kappa B)/PU.1 composite site at position -80 of the IL-1Ra promoter. Although leptin is capable of activating a NF-kappa B reporter element in transient transfection experiments, the protein complex binding to the NF-kappa B/PU.1 site of the IL-1Ra promoter is not composed of the p65/p50 subunits of NF-kappa B, as is evident in electrophoretic gel mobility-shift experiments. In contrast, a protein complex which does not contain PU.1 binds to this composite element in a leptin-dependent manner. In summary, we characterize the signalling pathway for leptin and OB-Rb involved in the induction of IL-1Ra, involving p42/44 MAPK, and a yet uncharacterized complex of transcription factor(s) binding to a NF-kappa B/PU.1 composite element of the IL-1Ra promoter.
Binding Sites↗
Mice transgenic for intracellular interleukin-1 receptor antagonist type 1 are protected from collagen-induced arthritis.
Interleukin-1 receptor antagonist (IL-1Ra) is a natural IL-1 inhibitor, which competitively inhibits binding of IL-1 to its receptors. IL-1Ra is produced as four different isoforms, one secreted (sIL-1Ra) and three intracellular (icIL-1Ra1, 2, 3), derived from the same gene. We previously observed increased production of icIL-1Ra1 in the joints of mice with collagen-induced arthritis (CIA). However, due to its intracellular localization, the biological role of icIL-1Ra1 remains unknown. The aim of the present study was to examine the effect of the icIL-1Ra1 isoform, as compared to that of sIL-1Ra, in the CIA model by comparing transgenic (tg) mice overexpressing icIL-1Ra1 or sIL-1Ra to their wild-type littermates. Serum levels of tg human IL-1Ra were elevated in sIL-1Ra and, to a lesser extent, also in icIL-1Ra1 mice. Clinical scoring indicated that none of the icIL-1Ra1 or siL-1Ra tg mice developed CIA, whereas arthritis was present in, respectively, 60% and 100% of their wild-type littermates. Histological and radiological analyses confirmed the absence of arthritis in icIL-1Ra1 and sIL-1Ra tg mice. Accordingly, circulating levels of the acute-phase protein serum amyloid A tended to be lower in icIL-1Ra1 tg mice than in their wild-type littermates and were significantly lower in sIL-1Ra tg mice than in controls. In contrast, no difference was observed between the groups regarding serum levels of anti-type II collagen antibodies and ex vivo spleen cell proliferative response to collagen. In conclusion, icIL-1Ra1, which is released into the extracellular space when produced in high amounts, has a similar anti-arthritic effect as sIL-1Ra.
Adhesins, Bacterial↗
IL-1 trap. Regeneron/Novartis.
Regeneron and Novartis are co-developing the interleukin (IL)-1 antagonist IL-1 trap for the potential treatment of rheumatoid arthritis. In July 2002, a phase II trial was initiated and results are expected mid-2003.
Animals↗
Production of interleukin-1 receptor antagonist by human articular chondrocytes.
Interleukin-1 receptor antagonist (IL-1Ra) is a natural IL-1 inhibitor possessing anti-inflammatory properties. IL-1Ra is produced as different isoforms, one secreted (sIL-1Ra) and three intracellular (icIL-1Ra1, icIL-1Ra2 and icIL-1Ra3), derived from the same gene. We examined the production of IL-1Ra species by cultured human articular chondrocytes in response to various cytokines. The levels of IL-1Ra were undetectable in culture supernatants of untreated cells, but were significantly increased by IL-1beta. Cell lysates contained very low levels of IL-1Ra, even in response to IL-1beta, suggesting that chondrocytes produce predominantly sIL-1Ra. IL-6, which had no effect on its own, enhanced the effect of IL-1beta, while dexamethasone prevented the response. We observed by RT-PCR that IL-1beta and IL-6 induced primarily the production of sIL-1Ra mRNA. Furthermore, IL-1beta alone or combined with IL-6 increased the levels of nascent unspliced sIL-1Ra mRNA, suggesting that sIL-1Ra expression is regulated at the transcriptional level. Reporter gene assays in immortalized chondrocytes, C-20/A4, consistently showed increased sIL-1Ra promoter activity in response to IL-1beta and IL-6. In conclusion, human articular chondrocytes produce sIL-1Ra in response to IL-1beta and IL-6. The production of sIL-1Ra by chondrocytes may have a protective effect against articular inflammatory and catabolic responses.
Arthritis, Rheumatoid↗
Leptin signaling deficiency impairs humoral and cellular immune responses and attenuates experimental arthritis.
Leptin is produced almost exclusively by adipocytes and regulates body weight at the hypothalamic level. In addition, recent studies showed that leptin plays an important role in T lymphocyte responses. To examine the role of leptin in Ag-induced arthritis, the development of joint inflammation was assessed in immunized leptin-deficient mice (ob/ob), +/?, and wild-type mice (+/+) following the administration of methylated BSA into the knees. The results showed that ob/ob mice developed less severe arthritis compared with control mice. The levels of IL-1beta and TNF-alpha mRNA in the synovium of arthritic knees were lower in ob/ob than in +/? mice. In vitro Ag-specific T cell proliferative responses were significantly decreased in ob/ob mice with lower IFN-gamma and higher IL-10 production, suggesting a shift toward a Th2-type response in ob/ob mice. The serum levels of anti-methylated BSA Abs of any isotype were significantly decreased in arthritic ob/ob mice compared with controls. Essentially identical results were obtained in db/db mice, which lack the expression of the long isoform of leptin receptor. By RT-PCR, we observed that B lymphocytes express leptin receptor mRNA, indicating that in addition to its effect on the cellular response, leptin may exert a direct effect on B cell function. In conclusion, leptin contributes to the mechanisms of joint inflammation in Ag-induced arthritis by regulating both humoral and cell-mediated immune responses.
Animals↗
Primary human articular chondrocytes, dedifferentiated chondrocytes, and synoviocytes exhibit differential responsiveness to interleukin-4: correlation with the expression pattern of the common receptor gamma chain.
Interleukin (IL)-4, which exhibits potent anti-inflammatory activities, is of potential therapeutic value in destructive arthropathies. To further define the response of human joint cells to IL-4, we analyzed the ability of this cytokine to modulate the effects of IL-1beta and growth factors. Freshly isolated chondrocytes, dedifferentiated chondrocytes, and synoviocytes were treated with IL-4 before determination of nitric oxide (NO) and collagenase production in response to IL-1beta, or before proliferation assays in presence of IL-1beta, platelet-derived growth factor (PDGF), or transforming growth factor (TGF)-beta. IL-4 downregulated IL-1beta induced NO production in dedifferentiated chondrocytes and inhibited IL-1beta induced collagenase release, as well as IL-1beta and growth factor induced proliferation in dedifferentiated chondrocytes and synoviocytes. In contrast, IL-4 had no effect in freshly isolated primary chondrocytes and in cartilage explants. The lack of response to IL-4 in primary chondrocytes was associated with impaired signal transduction, as indicated by markedly decreased IL-4 dependent tyrosine phosphorylation of signal transducer and activator of transcription (STAT)-6. It also correlated with differences in the expression pattern of IL-4 receptor (IL-4R) subunits during chondrocyte dedifferentiation. Indeed, whereas the IL-4Ralpha and IL-13Ralpha' subunits were expressed in all cell types, expression of the common receptor gamma chain was restricted to freshly isolated chondrocytes. In conclusion, IL-4 downregulated IL-1beta-induced catabolic events and cell proliferation in dedifferentiated chondrocytes and synoviocytes, but had no effects in freshly isolated chondrocytes. The difference in IL-4 responsiveness between primary and dedifferentiated chondrocytes correlated with changes in proximal signaling events and in the expression pattern of IL-4R subunits during cell dedifferentiation.
Cartilage, Articular↗
Specific role of interleukin-1 in hepatic neutrophil recruitment after ischemia/reperfusion.
Hepatic ischemia/reperfusion injury is caused primarily by the products of neutrophils recruited into the liver after reperfusion. The mediators responsible for the development of this inflammatory response are thought to be tumor necrosis factor-alpha and interleukin (IL)-1. Although there is abundant evidence to support a role for tumor necrosis factor-alpha, much less is known about the function of IL-1 in this injury. In the present studies, we investigated whether IL-1 was a critical mediator for the induction of liver inflammation after ischemia/reperfusion. Wild-type and IL-1 receptor I-knockout (IL-1RI(-/-)) mice were exposed to 90 minutes of partial hepatic ischemia and up to 24 hours of reperfusion. In wild-type mice, IL-1beta expression was maximal after ischemia and 8 hours of reperfusion. At the same time, both wild-type and IL-1RI(-/-) mice had severe liver injury as assessed by serum alanine aminotransferase levels and hepatic histopathology. However, IL-1RI(-/-) mice had significantly less neutrophil accumulation in liver tissues as measured by liver myeloperoxidase content and histology. The reduction in hepatic neutrophil recruitment in IL-1RI(-/-) mice was associated with decreased activation of the transcription factor, nuclear factor-kappaB, and reduced expression of the CXC chemokine, macrophage inflammatory protein-2. These data suggest that IL-1 functions to augment neutrophil accumulation, but does not play an essential role in this response.
Animals↗
IL-1 receptor antagonist serum levels are increased in human obesity: a possible link to the resistance to leptin?
We have recently shown that human monocytic cells express functional leptin receptors and that leptin is capable of inducing the expression and secretion of the IL-1 receptor antagonist (IL-1Ra). Although IL-1Ra has anti-inflammatory and possibly anti-atherogenic properties, it has also been shown to antagonize the action of leptin at the hypothalamic level in rodents, thereby inducing leptin resistance. We have therefore examined whether IL-1Ra levels are increased in human hyperleptinemic conditions, such as obesity. To this end, we measured serum IL-1Ra levels in 20 morbidly obese nondiabetic subjects [body mass index (BMI), 45 +/- 6 kg/m(2); serum leptin, 52 +/- 20 ng/ml] as well as in 10 age- and sex-matched lean controls (BMI, 22 +/- 2 kg/m(2); serum leptin, 7 +/- 4 ng/ml). Serum IL-1Ra concentrations proved to be elevated 6.5-fold in the obese subjects, and they were positively correlated in a linear manner with the leptin levels (r(2) = 0.34; P = 0.01), although lean body mass (LBM) and the insulin resistance index were even better predictors of IL-1Ra levels (r(2) = 0.45 and 0.58, respectively; P < 0.01). Six months after 15 of the 20 obese subjects had undergone bypass surgery for their morbid obesity, their mean BMI and leptin levels decreased to 33 +/- 7 kg/m(2) and 18 plus minus 12 ng/ml, respectively. This change in leptin concentrations was associated with a significant reduction in IL-1Ra levels (P < 0.02). However, there was a better correlation between the decrease in IL-1Ra level and the change in LBM than with the reduction in leptin levels, indicating that leptin is not the sole determinant of circulating IL-1Ra in obesity. In summary, we demonstrate that IL-1Ra levels are highly elevated in human obesity and that its concentrations decrease after weight loss from bypass surgery. However, LBM and insulin resistance are better predictors of serum IL-1Ra concentrations than are leptin levels, suggesting that additional metabolic factors control the secretion of this cytokine antagonist. Although the immunological consequences of this alteration remain unknown, it is tempting to speculate that the obesity-related increase in IL-1Ra might contribute to the central resistance to leptin in obese patients, similar to the inhibition of the hypothalamic signaling of leptin by IL-1Ra in rodents.
Adult↗