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

Mononuclear Phagocytes in Rheumatoid Arthritis Patients and their Relatives - Family Similarity

The aim of this work was to study the peripheral blood monocyte functions in patients with advanced RA and their predisposed to RA relatives in comparison with those in women, not hereditary tainted with autoimmune diseases (donors). In groups comprising 24 RA patients, 24 relatives, and 24 donors the following monocyte functions were assessed: engulfment and digestion (radioisotope method); release of lysosomal glucuronidase in response to opsonized zymosan (fluorescent method); reactive oxygen species (ROS) generation (chemiluminescence), and serum levels of proinflammatory cytokines (ELISA). The monocyte specific feature in patients and their relatives is chiefly extracellular digestion due to the delayed engulfment. The digestive activity, probably inhibited in relatives, is increased in advanced RA. ROS generation by the cells and serum levels of TNF-alpha and IL-1-beta are abundant both in the patients and their relatives. High levels of pro-inflammatory cytokines, presumably, of monocyte origin, and increased levels of stimulated ROS generation may be due to the priming and prolonged activation of monocytes in relatives.

CONCLUSION

We show for the first time that the functioning of circulating mononuclear phagocytes in the assumed to be healthy predisposed to RA individuals differs from that in the healthy people not hereditary tainted with autoimmune diseases and in general resembles the functioning of the cells in the patients with advanced RA.

A signature of aberrant immune responsiveness identifies myocardial dysfunction in rheumatoid arthritis

OBJECTIVE

Heart failure is an important cause of death in patients with rheumatoid arthritis (RA). Evidence suggests that immune mechanisms contribute to myocardial injury and fibrosis, leading to left ventricular diastolic dysfunction (LVDD). The purpose of this study was to identify a signature of LVDD in patients with RA by analyzing the responsiveness of the innate and adaptive immune systems to stimulation ex vivo.

METHODS

RA patients (n=212) enrolled prospectively in a population-based cohort underwent echocardiography, and LV function was classified as normal, mild LVDD, or moderate-to-severe LVDD. The release of 17 cytokines by blood mononuclear cells in response to stimulation with a panel of 7 stimuli or in media alone was analyzed using multiplex immunoassays. Logistic regression models were used to test for associations between a multicytokine immune response score and LVDD, after adjusting for clinical covariates.

RESULTS

An 11-cytokine profile effectively differentiated patients with moderate-to-severe LVDD from those with normal LV function. An immune response score (range 0-100) was strongly associated with moderate-to-severe LVDD (odds ratio per 10 units 1.5 [95% confidence interval 1.2-2.1]) after adjusting for serum interleukin-6 levels, brain natriuretic peptide values, and glucocorticoid use, as well as other RA characteristics and LVDD risk factors.

CONCLUSION

The major finding of this study was that aberrant systemic immune responsiveness is associated with advanced myocardial dysfunction in patients with RA. The unique information added by the immune response score concerning the likelihood of LVDD warrants future longitudinal studies of its value in predicting future deterioration in myocardial function.

Pharmacokinetic-pharmacodynamic modeling of apratastat: a population-based approach

Apratastat is an orally active, potent, and reversible dual inhibitor of tumor necrosis factor-α converting enzyme (TACE) and matrix metalloproteinases (MMPs). This study characterizes the pharmacodynamic (PD) effect of apratastat following oral administration on tumor necrosis factor-alpha (TNF-α) release. Data were obtained from 3 clinical studies carried out in healthy subjects. Apratastat was administered orally in these studies as single doses or multiple doses (twice daily). The inhibition of TNF-α release by apratastat was investigated in studies of in vitro, ex vivo, and in vivo. Inhibitory E(max) models were used to characterize the inhibition of TNF-α release in both in vitro and ex vivo studies. Apratastat inhibited TNF-α release with a population mean IC(50) of 144 ng/mL in vitro and of 81.7 ng/mL ex vivo, respectively. The relationship between TNF-α and apratastat plasma concentration in the endotoxin-challenged study in healthy subjects was well characterized by a mechanism-based PD population model with IC(50) of 126 ng/mL. Apratastat can potently inhibit the release of TNF-α in vitro, ex vivo, and in vivo. Even though the dosage provided adequate exposure to inhibit TNF-α release, apratastat was not efficacious in rheumatoid arthritis (RA). This inconsistency between TNF-α inhibition and the clinical response requires further investigation.

Analysis of complex biomarkers for human immune-mediated disorders based on cytokine responsiveness of peripheral blood cells

The advent of improved biomarkers promises to enhance the clinical care for patients with rheumatoid arthritis (RA) and other immune-mediated disorders. We have developed an innovative approach to broadly assess the cytokine responsiveness of human PBMCs using a multistimulant panel and multiplexed immunoassays. The objective of this study was to demonstrate this concept by determining whether cytokine profiles could discriminate RA patients according to disease stage (early versus late) or severity. A 10-cytokine profile, consisting of IL-12, CCL4, TNF-alpha, IL-4, and IL-10 release in response to stimulation with anti-CD3/anti-CD28, CXCL8 and IL-6 in response to CMV and EBV lysate, and IL-17A, GM-CSF, and CCL2 in response to human heat shock protein 60, easily discriminated the early RA group from controls. These data were used to create an immune response score, which performed well in distinguishing the early RA patients from controls and also correlated with several markers of disease severity among the patients with late RA. In contrast, the same 10-cytokine profile assessed in serum was far less effective in discriminating the groups. Thus, our approach lays the foundation for the development of immunologic "signatures" that could be useful in predicting disease course and monitoring the outcomes of therapy among patients with immune-mediated diseases.

The contact-mediated response of peripheral-blood monocytes to preactivated T cells is suppressed by serum factors in rheumatoid arthritis

Stimulation of monocytes/macrophages after cell contact with preactivated T cells has been suggested to contribute to the excessive TNF-α production in rheumatoid arthritis (RA). In this study, T cell-contact-dependent TNF-α production by peripheral-blood monocytes in vitro was investigated and found to be significantly lower in treated and untreated patients with RA than in healthy controls. This suppression was not due to a general deficiency of monocytes to respond, because responses to lipopolysaccharide were comparable in patients and controls. In agreement with the pivotal role of TNF-α in RA, T cell-dependent induction of TNF-α in synovial macrophages was fivefold to tenfold higher than in peripheral-blood monocytes from either patients or controls. The decreased response of peripheral-blood monocytes from patients with RA was found to be mediated by inhibitory serum factors, because the addition of patient sera to monocytes from healthy controls suppressed TNF-α response in the co-culture assay. Preincubation of monocytes from healthy controls with RA serum was sufficient to suppress the subsequent TNF-α response in T cell co-cultures, indicating that inhibitory factors do indeed bind to monocyte surfaces, which might represent a regulatory counter-action of the immune system to the long-standing and consuming autoimmune process in RA. There are some indications that apolipoprotein A-1 might be part of this regulatory system.

Active immunization against murine TNFalpha peptides in mice: generation of endogenous antibodies cross-reacting with the native cytokine and in vivo protection

New lines of treatment targeting cytokines have been successfully developed recently and are now widely used in therapy. They are based on passive administration of cytokine inhibitors either soluble receptors or mAbs and the major example is TNFalpha in rheumatoid arthritis (RA). Since a few years, our group has developed a novel alternative approach targeting cytokines by using active immunization against biologically inactive but immunogenic cytokine derivatives. In the present work, we present a new aspect of this research, based on immunization against specific cytokine peptides chosen by molecular modelling. We could elicit a significant humoral response against four TNFalpha peptides by active immunization, and show that the Abs generated cross-reacted with the native cytokine with good titers as determined by ELISA. Interestingly, during coimmunization experiments with couples of peptides, one showed a clear immunodominant effect over the other. Overall, we could not show the neutralization of TNFalpha biological activity in vitro by the immunized sera, but it seems that it is not a prerequisite to observe clinical efficacy. Indeed, using the LPS/galactosamine-induced shock, we could demonstrate that one of the four peptides tested conferred a clinical protection. These results validate the feasibility and efficacy of active immunization against cytokine peptides, and confirm that active immunization against cytokines could represent in the future an alternative to passive immunization in many diseases.

(E)-2(R)-[1(S)-(Hydroxycarbamoyl)-4-phenyl-3-butenyl]-2'-isobutyl-2'-(methanesulfonyl)-4-methylvalerohydrazide (Ro 32-7315), a selective and orally active inhibitor of tumor necrosis factor-alpha convertase

Tumor necrosis factor-alpha (TNF-alpha), a cytokine secreted by inflammatory cells, has been implicated in several inflammatory disease states. (E)-2(R)-[1(S)-(Hydroxycarbamoyl)-4-phenyl-3-butenyl]-2'-isobutyl-2'-(methanesulfonyl)-4-methylvalerohydrazide (Ro 32-7315), is a potent, orally active inhibitor of the TNF-alpha convertase (TACE), an enzyme responsible for proteolytic cleavage of the membrane bound precursor, pro-TNF-alpha. Ro 32-7315 inhibited a recombinant form of TACE (IC(50) = 5.2 nM) with selectivity over related matrix metalloproteinases. In a cellular assay system, THP-1 cell line, and in human and rat whole blood, Ro 32-7315 significantly reduced lipopolysaccharide (LPS)-induced TNF-alpha release with IC(50) values of 350 +/- 14 nM (n = 5), 2.4 +/- 0.5 microM (n = 5), and 110 +/- 18 nM (n = 5), respectively. Oral administration of Ro 32-7315 to Wistar rats caused a dose-dependent inhibition of LPS-induced release of systemic TNF-alpha with an ED(50) of 25 mg/kg. Treatment (days 0-14) of Allen and Hamburys hooded rats with Ro 32-7315 (2.5, 5, 10, and 20 mg/kg, i.p., twice daily) significantly reduced adjuvant-induced secondary paw swelling (42, 71, 83, and 93%, respectively) as compared with the vehicle group. In the Ro 32-7315-treated group, the reduced paw swelling was associated with improved lesion score and joint mobility. Furthermore, in a placebo-controlled, single-dose study, Ro 32-7315 given orally (450 mg) significantly suppressed ex vivo, LPS-induced TNF-alpha release in the whole-blood samples taken from healthy male and female volunteers (mean inhibition of 42% over a 4-h duration, n = 6). These data collectively support the potential use of such a compound for the oral treatment of inflammatory disorders.

New therapeutic approaches to the management of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common disease that affects up to 1% of the population, and causes significant morbidity and early mortality. The aetiology of RA is unknown; however, in the last 10 to 15 years significant advances in molecular technology have provided a greater understanding of the pathogenesis of the disease. This has led to the development of new approaches to the treatment of RA. The disease modifying antirheumatic oral agent leflunomide inhibits the proliferation of activated T cells that are important in the inflammation and degradation of synovial tissues. The 2 biological agents approved for the treatment of RA, infliximab and etanercept, are inhibitors of the pro-inflammatory cytokine, tumour necrosis factor-alpha (TNFalpha). Infliximab is a chimeric human/mouse monoclonal antibody which is administered by intravenous infusion and binds with high affinity to TNFalpha, thereby neutralising its effects. Etanercept is a recombinant, soluble TNF receptor molecule which is administered subcutaneously and binds to TNFalpha in the serum rendering it biologically inactive. The protein A immunoadsorption column is a medical device that in conjunction with plasmapheresis can be used in patients with refractory RA. These agents have provided new and effective therapies for the treatment of patients with RA.

Tachykinin activation of human monocytes from patients with rheumatoid arthritis: in vitro and ex-vivo effects of cyclosporin A

Three types of tachykinin receptors, namely NK1, NK2 and NK3, are known to preferentially interact with substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), respectively. We previously demonstrated that NK1 and NK2 receptors are present on human monocytes, SP and NKA inducing superoxide anion production and tumor necrosis factor-alpha (TNF-alpha) mRNA expression. NK2 receptor stimulation also triggered an enhanced respiratory burst in monocytes isolated from rheumatoid arthritis (RA) patients. This study was aimed to evaluate the in vitro and ex-vivo effects of cyclosporin A (CsA) on tachykinins-evoked TNF-alpha release from monocytes of healthy donors and RA patients. CsA (100 ng/ml) potently inhibited phorbol ester- and tachykinin-evoked TNF-alpha secretion. In RA patients treated with CsA (Sandimmun Neoral 2.5 mg/kg/day, a significant time-dependent reduction in TNF-alpha secretion from monocytes was measured. This may contribute to the CsA therapeutic activity in RA.

Proliferation of a subpopulation of human peripheral blood monocytes in the presence of colony stimulating factors may contribute to the inflammatory process in diseases such as rheumatoid arthritis

Apart from acting on hemopoietic progenitor cells, colony stimulating factors (CSFs) have been shown to be involved in the activation, survival, proliferation and differentiation of more mature cells of the monocyte/macrophage lineage. There is evidence that a proportion of human peripheral blood monocytes can proliferate in response to CSF-1, (also known as M-CSF) and granulocyte-macrophage-CSF (GM-CSF). CSFs have been shown to be at elevated levels in the synovial fluid of RA patients and thus local proliferation of monocyte/macrophage within an inflamed lesion may contribute to the local tissue hyperplasia evident in inflammatory conditions. Flow cytometric analysis of surface antigen expression and cytokine production in response to lipopolysaccharide stimulation has been used to characterise the proliferating subpopulation of monocytes. Further characterization and subsequent isolation of this subpopulation of monocytes may provide new and important information necessary in understanding inflammatory diseases such as rheumatoid arthritis, where local proliferation at the site of inflammation may be a key factor contributing to the chronicity of the disease.

Prostaglandin E1 suppresses tumor necrosis factor-alpha and interleukin-10 production by lipopolysaccharides-stimulated mononuclear cells

Prostaglandin E1 has been clinically used in a variety of vascular occlusive diseases. We investigated the in vitro effect of prostaglandin E1 on the synthesis of tumor necrosis factor-alpha, interleukin-1, interleukin-6, interleukin-10 and transforming growth factor beta by human peripheral blood mononuclear cells stimulated with lipopolysaccharides. Prostaglandin E1 significantly suppressed both the mRNA expression and the production of tumor necrosis factor-alpha and interleukin-10 by lipopolysaccharides-stimulated peripheral blood mononuclear cells in a dose-dependent manner (1 x 10(-6)-1 x 10(-8) M). Since tumor necrosis factor-alpha is a potent proinflammatory cytokine involved in certain inflammatory diseases, our findings suggest the possibility to expand the clinical application of prostaglandin E1.