Circulation Of Rheumatoid Arthritis Patients Research Articles

A Neutrophil Activation Biomarker Panel in Prognosis and Monitoring of Patients With Rheumatoid Arthritis.

Exaggerated neutrophil activation and formation of neutrophil extracellular traps (NETs) are linked to inflammation and autoimmunity, including rheumatoid arthritis (RA). However, whether NETs are present in the circulation of RA patients and contribute to inflammation and disease progression has not been carefully addressed. We undertook this study to assess markers of neutrophil activation and NET formation in plasma samples, investigating whether they add clinical value in improving the determination of prognosis and monitoring in RA patients. Markers of neutrophil activation (calprotectin) and cell death (NETs) were analyzed, using enzyme-linked immunosorbent assay, in serum and plasma obtained from patients in 3 cross-sectional RA cohorts and sex-matched healthy controls. A longitudinal inception cohort (n = 247), seen for a median follow-up of 8 years, was used for predictive analyses. Markers of neutrophil activation and cell death were increased in RA patients compared to healthy individuals (P < 0.0001). Calprotectin levels correlated with the Clinical Disease Activity Index (r = 0.53, P < 0.0001) and could be used to distinguish between patients with disease in remission and those with active disease, an observation not seen when examining C-reactive protein levels. A biomarker panel consisting of anti-citrullinated protein antibody and calprotectin could predict erosive disease (odds ratio [OR] 7.5, P < 0.0001) and joint space narrowing (OR 4.9, P = 0.001). NET levels were associated with markers of inflammation (P = 0.0002). Furthermore, NETs and a "neutrophil activation signature" biomarker panel had good predictive value in identifying patients who were developing extraarticular nodules (OR 5.6, P = 0.006). Neutrophils undergo marked activation and cell death in RA. Neutrophil biomarkers can provide added clinical value in the monitoring and prognosis of RA patients and may allow for early preventive treatment intervention.

Interleukin-34 Promotes Fibrocyte Proliferation.

Rheumatoid arthritis (RA) is a systemic autoimmune disease affecting multiple joints. It remains unclear which factors in the circulation are associated with the systemic spread of the disease. Fibrocytes are pluripotent mesenchymal stem cells present in the circulation of RA patients. Our earlier findings implicated activated fibrocytes in the etiology of onset and pathogenesis of RA. Elevated levels of interleukin-34 (IL-34) in the serum and synovial fluid of RA patients are associated with rheumatoid factor and anticyclic citrullinated peptide antibodies, indicators of RA. Moreover, IL-34 levels are independent predictors of radiographic progression in RA patients. We provide evidence of simultaneous elevated levels of IL-34 and increased numbers of activated fibrocytes in the circulation of mice induced to develop arthritis. In vitro, IL-34 treatment induced the proliferation of fibrocytes, mediated by activation of cognate CSF-R1s on fibrocytes. Taken together, we infer that IL-34 has a role in stimulating fibrocyte proliferation and activation during arthritis, thereby contributing to both onset of RA and systemic spread of disease.

CD4+CD28null T cells in RA show distinctive proinflammatory features and IFN-γ promoter demethylation

Background and objectivesApproximately one third of rheumatoid arthritis (RA) patients display an expanded T cell subset that lacks the co-stimulatory molecule CD28, often referred to as CD4+CD28null T cells. Despite...

The proinflammatory activity of recombinant serum amyloid A is not shared by the endogenous protein in the circulation

Elevated serum levels of the acute-phase protein serum amyloid A (SAA) are a marker for active rheumatoid arthritis (RA), and SAA can also be found in the tissues of patients with active RA. Based on a number of studies with recombinant SAA (rSAA), the protein has been suggested to be a potent proinflammatory mediator that activates human neutrophils, but whether endogenous SAA shares these proinflammatory activities has not been directly addressed. The present study was undertaken to investigate whether SAA in the plasma of patients with RA possesses proinflammatory properties and activates neutrophils in a manner similar to that of the recombinant protein. Neutrophil activation was monitored by flow cytometry, based on L-selectin shedding from cell surfaces. Whole blood samples from healthy subjects and from RA patients with highly elevated SAA levels were studied before and after stimulation with rSAA as well as purified endogenous SAA. Recombinant SAA potently induced cleavage of L-selectin from neutrophils and in whole blood samples. Despite highly elevated SAA levels, L-selectin was not down-regulated on RA patient neutrophils as compared with neutrophils from healthy controls. Spiking SAA-rich whole blood samples from RA patients with rSAA, however, resulted in L-selectin shedding. In addition, SAA purified from human plasma was completely devoid of neutrophil- or macrophage-activating capacity. The present findings show that rSAA is proinflammatory but that this activity is not shared by endogenous SAA, either when present in the circulation of RA patients or when purified from plasma during an acute-phase response.

Targeting Complement in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by polyarticular synovitis leading to cartilage, tendon and bone destruction, and pain and dysfunction of the joints. It is considered to be an immune-mediated inflammatory disorder, in which the complement system also plays a fundamental role. In the circulation of RA patients, increased levels of complement activation products have been found, often correlating with disease activity. In synovial fluid of the patients, decreased levels of native complement components and increased levels of activation products have been detected. Furthermore, in synovial tissue and cartilage, deposition of activated complement components has been demonstrated. As activators of the complement system in RA, immune complexes, C-reactive protein, and certain immunoglobulin G glycoforms have been identified. A role for complement activation in the pathogenesis of this disease is supported by studies showing an association between complement activation and inflammatory responses in the diseased joints or in individual cell types found in RA joints, and by extensive studies on animal models of the disease, utilizing for example animals deficient for certain complement components. Finally, several agents are under development to therapeutically influence the complement system, and some have already been tested in clinical trials of RA.

Synovial Fluid from Rheumatoid Arthritis Patients Contains Sufficient Levels of IL-1β and IL-6 to Promote Production of Serum Amyloid A By HEP3B Cells

The presence of positive acute phase proteins within the circulation of rheumatoid arthritis patients suggests that elevated cytokine production associated with this chronic inflammatory disorder initiates the hepatic acute phase response. Cytokines produced at inflammatory lesions are believed to travel via the circulation to the liver where they induce acute phase protein production by hepatocytes. To test whether serum from rheumatoid arthritis patients contained sufficient levels of cytokines to promote an acute phase response in vitro, a bioassay was developed that employed the human hepatoma cell line Hep3B. These cells produced the acute phase protein serum amyloid A (SAA) in response to a combination of recombinant IL-1 beta and IL-6 or to monocyte conditioned medium. Serum (or plasma) from normal individuals or from rheumatoid arthritis patients did not induce SAA production by Hep3B cells. Moreover, these serum samples did not prevent SAA production induced by monocyte conditioned medium, indicating that they did not contain inhibitors of cytokine activity. Despite the inactivity of serum samples, synovial fluid samples obtained from rheumatoid arthritis patients were active in the hepatocyte bioassay and promoted SAA synthesis. One synovial fluid sample was analysed in detail to identify cytokines responsible for the SAA-inducing activity. Neutralizing antisera against IL-6 and IL-1 beta blocked this activity by > 90% whereas anti-IL1 alpha and anti-TNF-alpha sera were without effect. Absolute cytokine levels within the synovial fluid sample were determined by ELISA; IL-6, IL-beta and TNF-alpha, but not IL-1 alpha, were confirmed to be present. Moreover, the synovial fluid sample contained a large amount of the IL-1 receptor antagonist. These data indicate, therefore, that synovial fluid recovered from an inflamed joint contains all the necessary cytokines in balance with inhibitors to promote SAA production by Hep3B cells. The steady state levels of these factors within the plasma compartment, however, were insufficient to induce the acute phase response by cultured Hep3B cells, suggesting that this system does not mimic the relationship between the circulation and the liver that likely exists in rheumatoid arthritis patients.

Treatment of Rheumatoid Arthritis with a Chimeric CD4 Monoclonal Antibody (cM‐T412): Immunopharmacological Aspects and Mechanisms of Action

To investigate the mechanisms of action underlying the therapeutic effect of CD4 monoclonal antibody therapy in rheumatoid arthritis (RA), clinical responses were compared with several laboratory parameters. Twenty-nine RA patients received either 10 mg, 50 mg or 100 mg of cM-T412, a chimeric CD4 MoAb, for 7 days. The CD4 binding sites on circulating lymphocytes were saturated directly with cM-T412 and serum levels of unbound cM-T412 accumulated towards day 7 of treatment only in the patients treated with 50 and 100 mg. The treatment induced an instant and prolonged depression of the number of circulating CD4+ cells, similar for all dosages. Clinical improvement was observed predominantly in the patients treated with 50 or 100 mg cM-T412 daily and did not correlate with changes in counts of circulating leucocyte subsets nor with changes in serum cytokine levels. An antiglobulin response against cM-T412 developed in a majority of the patients. Side effects on the first day of treatment were correlated with an increase of serum IL-6 levels. This study indicates that a favourable clinical effect of cM-T412 administration was associated with the presence of unbound cM-T412 in the circulation of RA patients. Therefore penetration of unbound cM-T412 into the site of inflammation might determine the therapeutic effect in RA.