Peripheral blood and synovial fluid monocyte activation in inflammatory arthritis. I. A cytofluorographic study of monocyte differentiation antigens and class II antigens and their regulation by gamma-interferon

Single cell analysis of spondyloarthritis regulatory T cells identifies distinct synovial gene expression patterns and clonal fates

Regulatory T cells (Tregs) play an important role in controlling inflammation and limiting autoimmunity, but their phenotypes at inflammatory sites in human disease are poorly understood. We here analyze the single-cell transcriptome of >16,000 Tregs obtained from peripheral blood and synovial fluid of two patients with HLA-B27+ ankylosing spondylitis and three patients with psoriatic arthritis, closely related forms of inflammatory spondyloarthritis. We identify multiple Treg clusters with distinct transcriptomic profiles, including, among others, a regulatory CD8+ subset expressing cytotoxic markers/genes, and a Th17-like RORC+ Treg subset characterized by IL-10 and LAG-3 expression. Synovial Tregs show upregulation of interferon signature and TNF receptor superfamily genes, and marked clonal expansion, consistent with tissue adaptation and antigen contact respectively. Individual synovial Treg clones map to different clusters indicating cell fate divergence. Finally, we demonstrate that LAG-3 directly inhibits IL-12/23 and TNF secretion by patient-derived monocytes, a mechanism with translational potential in SpA. Our detailed characterization of Tregs at an important inflammatory site illustrates the marked specialization of Treg subpopulations.

MicroRNA-155-at the Critical Interface of Innate and Adaptive Immunity in Arthritis

MicroRNAs (miRNAs) are small non-coding RNAs that fine-tune the cell response to a changing environment by modulating the cell transcriptome. miR-155 is a multifunctional miRNA enriched in cells of the immune system and is indispensable for the immune response. However, when deregulated, miR-155 contributes to the development of chronic inflammation, autoimmunity, cancer, and fibrosis. Herein, we review the evidence for the pathogenic role of miR-155 in driving aberrant activation of the immune system in rheumatoid arthritis, and its potential as a disease biomarker and therapeutic target.

MicroRNA-155 contributes to enhanced resistance to apoptosis in monocytes from patients with rheumatoid arthritis

Monocytes and macrophages are key mediators of inflammation in rheumatoid arthritis (RA). Their persistence at the inflammatory site is likely to contribute to immunopathology. We sought to characterise one mechanism by which persistence may be achieved: resistance to apoptosis and the role of mir-155 in this process. CD14+ monocytes from peripheral blood (PBM) and synovial fluid (SFM) of RA patients were found to be resistant to spontaneous apoptosis relative to PBM from healthy control (HC) individuals. RA SFM were also resistant to anti-Fas-mediated apoptosis and displayed a gene expression profile distinct from HC and RA PBM populations. Gene expression profiling analysis revealed that the differentially expressed genes in RA SFM vs. PBM were enriched for apoptosis-related genes and showed increased expression of the mir-155 precursor BIC. Following identification of potential mir-155 target transcripts by bioinformatic methods, we show increased levels of mature mir-155 expression in RA PBM and SFM vs. HC PBM and a corresponding decrease in SFM of two predicted mir-155-target mRNAs, apoptosis mediators CASP10 and APAF1. Using miR mimics, we demonstrate that mir-155 over-expression in healthy CD14+ cells conferred resistance to spontaneous apoptosis, but not Fas-induced death in these cells, and resulted in increased production of cytokines and chemokines. Collectively our data indicate that CD14+ cells from patients with RA show enhanced resistance to apoptosis, and suggest that an increase in mir-155 may partially contribute to this phenotype.

•

CD14+ cells from the inflamed RA joint are strongly resistant to death.

•

Microarrays show differences in apoptosis genes in CD14+ cells from the RA joint.

•

Mir-155 is increased and its targets decreased in RA joint CD14+ cells.

•

Overexpression of mir-155 increases apoptosis resistance of healthy CD14+ cells.

Anti-inflammatory effects of the extract of Gnaphalium affine D. Don in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Gnaphalium affine D. Don (GA) has been traditionally used as a medicinal herb in China for the treatment of many ailments including rheumatoid arthritis. However, the anti-arthritic mechanism of GA has still not been demonstrated. This study aims to reveal the anti-inflammatory activity and anti-arthritic mechanism of ethanol extract of G. affine D. Don.

MATERIALS AND METHODS

Anti-inflammatory potential of GA was analyzed in vivo in carrageenan induced mice paw edema (acute study). Also, in vivo study was applied in collagen-induced arthritis (CIA) rats. In vitro experiments for analyzing the anti-inflammatory potential of GA were performed on rat alveolar macrophages cell line (NR8383). Analysis of nitric oxide release in NR8383 cells was done by Griess reaction. RT-PCR and western blotting experiment was performed to analyze the expression of phosphorylated p65 and IκBα/β-actin in NF-κB pathway. The production of TNF-α, IL-1β, and COX-2 in NR8383 cells were measured by enzyme-linked immunosorbent assay. The chemical profile of GA was analyzed by HPLC-VWD.

RESULTS

GA significantly reduced the paw volume in carrageenan induced rat paw edema rat at different doses (300 and 600 mg/kg), compared with the standard indomethacin treatment. In CIA, GA can obviously ameliorate the inflammatory symptom, including cytokine, histological symptom and paw swelling. In the vitro study, GA was able to reduce the nitric oxide (NO) levels in NR8383 cells that had been stimulated with lipopolysaccharide (LPS). The level of TNF-α, IL-1β, and COX-2 was also decreased with GA treatment in NR8383 cells that had been stimulated with lipopolysaccharide (LPS). Interestingly, GA was found to decrease the level of phosphorylated p65 and IκBα in NR8383 cells. Fifteen compounds were identified by HPLC-VWD with the reference substances and verified by LC-MS.

CONCLUSIONS

The results of the experiment scientifically validated its traditional use in inflammatory conditions.

LILRA5 is expressed by synovial tissue macrophages in rheumatoid arthritis, selectively induces pro-inflammatory cytokines and IL-10 and is regulated by TNF-alpha, IL-10 and IFN-gamma

Leukocyte immunoglobulin-like receptor A5 (LILRA5) belongs to a family of receptors known to regulate leukocyte activation. There are two membrane-bound and two soluble forms of LILRA5. The transmembrane LILRA5 contain a short cytoplasmic domain and a charged arginine residue within the transmembrane region. Cross-linking of LILRA5 on monocytes induced production of pro-inflammatory cytokines, suggesting that LILRA5 plays a role in inflammation. However, expression of LILRA5 in diseases with extensive inflammatory component is unknown. Rheumatoid arthritis (RA) is a chronic inflammatory synovitis characterized by unregulated activation of leukocytes leading to joint destruction. Here we demonstrate extensive LILRA5 expression on synovial tissue macrophages and in synovial fluid of patients with active RA but not in patients with osteoarthritis. We also show that LILRA5 associated with the common gamma chain of the FcR and LILRA5 cross-linking induced phosphorylation of Src tyrosine kinases and Spleen tyrosine kinase (Syk). Furthermore, LILRA5 induced selective production of pro-inflammatory cytokines as well as IL-10. LILRA5 mRNA and protein expression was tightly regulated by TNF-alpha, IL-10 and IFN-gamma. Increased expression of LILRA5 in rheumatoid tissue, together with its ability to induce key cytokines involved in RA, suggests that this novel receptor may contribute to disease pathogenesis.

Diet and rheumatoid arthritis: a review of the literature

INTRODUCTION

Rheumatoid arthritis is a common inflammatory condition. A large number of patients seek alternative or complementary therapies of which diet is an important component. This article reviews the evidence for diet in rheumatoid arthritis along with the associated concept of oral tolerization.

METHODS

References were taken from Medline from 1966 to September 2004. The keywords, rheumatoid arthritis, diet, n-3 fatty acids, vitamins, and oral tolerization, were used.

RESULTS

Randomized controlled trials (RCTs) indicate that dietary supplementation with n-3 fatty acids provides modest symptomatic benefit in groups of patients with rheumatoid arthritis. Epidemiological studies and RCTs show cardiovascular benefits in the broader population and patients with ischemic heart disease. A number of mechanisms through which n-3 fats may reduce inflammation have been identified. In a small number of patients with rheumatoid arthritis, other dietary manipulation such as fasting, vegan, and elimination diets may have some benefit. However, many of these diets are impractical or difficult to sustain long term.

CONCLUSIONS

Dietary manipulation provides a means by which patients can a regain a sense of control over their disease. Dietary n-3 supplementation is practical and can be easily achieved with encapsulated or, less expensively, bottled fish oil.

The expression and significance of intracellular T helper cytokines in systemic lupus erythematosus

To analyze the Th1 and Th2 paradigm of peripheral T helper cells in patients with systemic lupus erythematosus (SLE). The intracellular Th1 and Th2 cytokines were analyzed in fresh blood T cells from 20 SLE patients who had not yet received any treatment. Th1 and Th2 cells were quantitated based on their intracellular cytokine content as assessed by flow cytometry. Cytokine expressions were correlated with clinical features, laboratory findings, and disease activities. There was no difference in the expression of intracellular IFN-y, or IL-4 between SLE patients and healthy controls. However, the IL-2 and IL-10 levels were significantly higher and lower respectively in the lupus patients than in the control group. In addition, patients with arthritis had higher IFN-gamma expression than patients without arthritis. Moreover, patients with serositis or CNS involvement had higher IL-4 expression than in patients without these manifestations. There was no correlation between the SLEDAI scores and the cytokine expression levels. However, patients with serum anti-ds DNA antibodies had higher IL-10 levels than in those without these antibodies. The present study demonstrates that a Th1 pattern of intracellular cytokines predominates in patients with SLE prior to treatment. The pattern of particular intracellular T cell cytokines may suggest specific clinical manifestations and disease progression of SLE.

n-3 polyunsaturated fatty acids inhibit the antigen-presenting function of human monocytes

Diets rich in n-3 polyunsaturated fatty acids (PUFAs) are associated with suppression of cell-mediated immune responses, but the mechanisms are unclear. We hypothesized that n-3 PUFAs can inhibit the function of human antigen-presenting cells. A prerequisite for this role of blood monocytes is the cell surface expression of major histocompatibility complex (MHC) class II molecules [human leukocyte antigen (HLA)-DR, -DP, and -DQ], aided by the presence of intercellular adhesion molecule-1 (ICAM-1) and leukocyte function associated antigens 1 and 3. We showed previously that the n-3 PUFA eicosapentaenoic acid (EPA) inhibits the expression of HLA-DR on unstimulated human monocytes in vitro, but that docosahexaenoic acid (DHA) enhances its expression. However, both n-3 PUFAs suppress the expression of HLA-DR, HLA-DP, and ICAM-1 on interferon-gamma-activated monocytes. We also established that dietary fish-oil supplementation can inhibit the expression of these surface molecules on circulating human monocytes. We subsequently showed that when EPA and DHA were combined in the same ratio as is commonly found in fish-oil-supplement capsules (3:2), there was no significant effect in vitro on the expression of HLA-DR on unstimulated monocytes, but the expression on activated monocytes remained significantly inhibited. In the same in vitro system, the ability of activated monocytes to present antigen to autologous lymphocytes was significantly reduced after culture with the combined n-3 PUFAs. These findings provide one potential mechanism for the beneficial effect of fish oil in the treatment of rheumatoid arthritis, a disorder associated with elevated expression of MHC class II and adhesion molecules on monocytes present within affected joints.

Beta interferon is produced by Chlamydia trachomatis-infected fibroblast-like synoviocytes and inhibits gamma interferon-induced HLA-DR expression

Infection of fibroblast-like synovial cells with Chlamydia trachomatis (serotype D strain IC Cal 8) in culture induced the secretion of beta interferon (IFN-beta). Chlamydial infection inhibited IFN-gamma-induced expression of HLA-DR antigen in the cells. Addition of IFN-beta antibody directly to infected cultures mitigated HLA-DR inhibition, suggesting involvement of produced IFN-beta.

Shift toward T lymphocytes with a T helper 1 cytokine-secretion profile in the joints of patients with rheumatoid arthritis

OBJECTIVE

To investigate whether T cells in the inflamed joints of patients with rheumatoid arthritis (RA) preferentially produce the T helper 1 (Th1) cytokines, interferon-gamma (IFN gamma) and interleukin-2 (IL-2), or the Th2 cytokine, IL-4, when compared with corresponding peripheral blood-derived T cells.

METHODS

Synovial fluid mononuclear cells (SFMC) and corresponding peripheral blood mononuclear cells (PBMC) from 10 patients with RA were analyzed, either directly or after in vitro stimulation, for the intracellular presence of Th1 and Th2 cytokines. The amount of secreted cytokine in the cell culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

IFN gamma-containing cells were detected in the unstimulated SFMC, but not in the PBMC, of 3 patients with RA. Cells positive for IL-2 or IL-4 were not detected in the unstimulated samples. Following stimulation, the mean percentage of cells containing Th1 cytokines was significantly increased in the SFMC compared with the PBMC; no differences were found in the mean percentage of IL-4-containing cells. A comparable shift toward Th1 cytokines was observed when the amount of secreted cytokine was determined by ELISA.

CONCLUSION

A shift toward T cells with a Th1 cytokine profile was observed in the joints of patients with RA. Since an imbalance between Th1 and Th2 cells is thought to be of pathogenic significance, this finding might have implications for the development of new therapies for RA.

Sensitivity of activated murine peritoneal macrophages to photodynamic killing with benzoporphyrin derivative

This study compared the ability of highly purified resting and activated DBA/2 mouse peritoneal macrophages to survive treatment with the photosensitizer benzoporphyrin derivative (BPD, verteporfin) and light. Culture of macrophages with recombinant murine interferon-gamma (rIFN-gamma, 100 U/mL) for 72 h imparted a phenotypic and functional activation by dramatically increasing cell surface expression of major histocompatibility complex Class II (Ia) molecules and the formation of nitric oxide. The rIFN-gamma-activated macrophages were significantly (P < 0.05) more sensitive (lethal dose to cause a 50% reduction in cell survival, LD50 = 14.4 +/- 1.1 ng/mL) to photodynamic killing with BPD and light (10 J/cm2) than cells (LD50 = 18.2 +/- 2.0 ng/mL) cultured in medium alone. In contrast, macrophages treated with different concentrations of bacterial lipopolysaccharide (LPS) were as resistant or more resistant to photodynamic killing than cells cultured in medium alone. No cytotoxic effect of BPD was detected in cultures containing the drug but protected from light. Comparable amounts of BPD were taken up in vitro by unactivated and rIFN-gamma-activated macrophages, as detected by flow cytometric analysis. However, cells cultured with LPS (10 micrograms/mL) took up more BPD than macrophages cultured in medium alone or with rIFN-gamma. The DBA/2 P815 mastocytoma cells took up greater amounts of the drug and were subsequently more vulnerable to treatment with BPD and light (LD50 = 6.9 ng/mL) than macrophages cultured under any condition. The explanation for the increased vulnerability of rIFN-gamma-activated macrophages and the greater resistance of LPS-activated macrophages, relative to medium-cultured macrophages, to photodynamic killing with BPD is uncertain.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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

Monocyte-endothelial adhesion in chronic rheumatoid arthritis. In situ detection of selectin and integrin-dependent interactions

Blood monocytes are the principal reservoir for tissue macrophages in rheumatoid synovitis. Receptor-mediated adhesive interactions between circulating cells and the synovial venules initiate recruitment. These interactions have been studied primarily in cultured endothelial cells. Thus the functional activities of specific adhesion receptors, such as the endothelial selectins and the leukocytic integrins, have not been evaluated directly in diseased tissues. We therefore examined monocyte-microvascular interactions in rheumatoid synovitis by modifying the Stamper-Woodruff frozen section binding assay initially developed to study lymphocyte homing. Specific binding of monocytes to venules lined by low or high endothelium occurred at concentrations as low as 5 x 10(5) cells/ml. mAbs specific for P-selectin (CD62, GMP-140/PADGEM) blocked adhesion by > 90% in all synovitis specimens examined. In contrast, P-selectin-mediated adhesion to the microvasculature was either lower or absent in frozen sections of normal foreskin and placenta. mAbs specific for E-selectin (ELAM-1) blocked 20-50% of monocyte attachment in several RA synovial specimens but had no effect in others. mAbs specific for LFA-1, Mo1/Mac 1, the integrin beta 2-chain, and L-selectin individually inhibited 30-40% of adhesion. An mAb specific for the integrin beta 1-chain inhibited the attachment of elutriated monocytes up to 20%. We conclude that P-selectin associated with the synovial microvasculature initiates shear-resistant adhesion of monocytes in the Stamper-Woodruff assay and stabilizes bonds formed by other selectins and the integrins. Thus the frozen section binding assay permits direct evaluation of leukocyte-microvascular adhesive interactions in inflamed tissues and suggests a prominent role for P-selectin in monocyte recruitment in vivo.

Expression of monocyte chemotactic and activating factor in rheumatoid arthritis. Regulation of its production in synovial cells by interleukin-1 and tumor necrosis factor

OBJECTIVE

To investigate whether monocyte chemotactic and activating factor (MCAF) contributes to the accumulation of macrophages in the joints of patients with rheumatoid arthritis (RA).

METHODS

MCAF was measured by radioimmunoassay. MCAF gene expression was determined by Northern blotting and reverse-transcriptase polymerase chain reaction. Recombinant human MCAF was injected into rabbit joints to evaluate the effect of MCAF on infiltration of macrophages.

RESULTS

High levels of MCAF were detected in synovial fluid from patients with RA. Cells freshly isolated from synovial fluid expressed MCAF messenger RNA (mRNA). Fibroblast-like synoviocytes were found to express MCAF mRNA and to secrete MCAF in response to interleukin-1 (IL-1) and tumor necrosis factor in vitro. IL-1 also promoted MCAF gene expression in rabbit synovial tissue in vivo. MCAF caused marked infiltration of macrophages in rabbit synovial tissue.

CONCLUSION

Our findings suggest that MCAF may contribute to the accumulation of macrophages in inflamed rheumatoid joints.

Possible clearance of effete polymorphonuclear leucocytes from synovial fluid by cytophagocytic mononuclear cells: implications for pathogenesis and chronicity in inflammatory arthritis

A feature common to all forms of chronic inflammatory arthritis, irrespective of the possible underlying cause, is the persistent exudation of large numbers of polymorphonuclear leucocytes (PMNL) into synovial fluid. These cells possess potent degradative enzymes and proinflammatory mediators, and their removal is vital to normal inflammatory resolution. A major route of disposal of extravasated PMNL appears to be programmed cell death (apoptosis), followed by their rapid recognition, and intact phagocytosis, by mature tissue macrophages. Such macrophages, containing PMNL (cytophagocytic mononuclear cells (CPM)), long recognised in synovial fluid as Reiter cells, are commonly found in reactive arthritis, spondyloarthritis, and crystal arthritides, but only rarely in rheumatoid disease. In a retrospective analysis of 187 knee synovial fluid cytospins, the relation between the formation of CPM and the presence of apoptotic (pyknotic) PMNL was investigated. As long as the synovial fluid examined was fresh there was a high correlation between numbers of CPM (as a percentage of macrophages) and pyknotic numbers of PMNL in fluids containing CPM. This suggests that the formation of CPM occurs in vivo and is involved in the disposal of PMNL. Numbers of pyknotic PMNL increased rapidly in stored synovial fluid without a significant change in numbers of CPM, and were highest in synovial fluid which did not contain CPM. The presence or absence of CPM, or their disease associations, could not be explained simply by limiting numbers of macrophages, or apoptotic PMNL in synovial fluid. These findings are consistent with a regulatory role for CPM in synovial fluid, where they may be important in preventing autolysis of PMNL, and thus local tissue damage.

T cells are responsible for the enhanced synovial cellular immune response to triggering antigen in reactive arthritis

In reactive arthritis (ReA) there is specific proliferation of synovial fluid (SF) mononuclear cells (MNC) to the triggering bacterial antigen; comparatively little or no response is seen in peripheral blood (PB). To investigate the mechanism of this elevated local immune response, we examined patients with typical ReA who showed an enhanced antigen-specific synovial immune response in bulk culture. Using separated fractions of T cells and antigen-presenting cells (APC) from PB and SF we showed that the synovial T cells rather than SF APC are responsible for the specific proliferation. By limiting dilution analysis, the frequency of T cells responding to the specific antigen was found to be significantly increased compared with the frequency of irrelevant antigen-specific T cells. Furthermore, the frequency of T cells responding to the specific antigen was higher in SF (between 1/619 and 1/4846, mean 1/2389) than in PB (between 1/1286 and 1/16,279, mean 1/7350). We conclude that the specific synovial cellular immune response in ReA is mainly due to an expansion of antigen-specific T cells within the joint. However, the non-specific hyper-reactivity of SF T cells and differences between SF and PB APC may make a more minor contribution.

Alteration in T cell/macrophage ratio may reveal lymphocyte proliferation specific for the triggering antigen in reactive arthritis

It has previously been shown that synovial fluid (SF) mononuclear cells (MNC) from patients with reactive arthritis (ReA) and some patients with undifferentiated oligoarthritis (UOA) respond specifically to the triggering bacterium (specific responders). However, in some patients there is a response to two or more bacteria (non-specific responders) and in a third group no response is found (non-responders). We assessed whether the proportion of synovial MNC which were macrophage-monocyte (MaMo) differed among the specific responder, non-specific responder and non-responder groups. There was no difference between the specific (33 +/- 9) and the non-specific (32 +/- 26) groups; non-responders had a higher percentage of MaMo (61.3 +/- 31%) although the difference was not significant. We also investigated whether the specificity of the response to antigen in ReA or UOA SF was altered by changing the T-cell/MaMo ratio. In all five specific responders the immune response remained specific whatever the ratio tested. However, four of the five non-specific responders, but none of the non-responders, developed a specific response to one of the tested antigens by increasing the T cell/MaMo ratio. We conclude that in some patients with a non-specific response, alteration of the T cell/MaMo ratio uncovers a specific response which may identify the triggering antigen.

Phenotypic analysis of functionally associated molecules on peripheral blood and synovial fluid monocytes from arthritis patients

Surface expression of 16 different membrane molecules was analyzed in peripheral blood and synovial fluid monocytes from patients with rheumatoid arthritis and reactive arthritis compared to controls. The most significant findings were modulated expression of function-associated FcRI, CR1, CR3, MHC class II and activation-associated CD31, M5, and M6 molecules in arthritis patients compared to controls. Of these molecules, only upregulated expression of MHC class II has previously been reported in synovial fluid monocytes of patients with rheumatoid arthritis.

Decreased monocyte-mediated angiogenesis in scleroderma

Scleroderma is a disease characterized by proliferative vascular lesions in which monocytes/macrophages may play a key role. Monocytes were isolated from 14 scleroderma patients and 11 normal controls and cultured with or without lipopolysaccharide (LPS) (5 micrograms/ml). Monocyte-conditioned medium was assayed in the rat corneal bioassay for angiogenesis. Conditioned medium from normal monocytes was nonangiogenic, as was conditioned medium from scleroderma monocytes. While conditioned medium from LPS-activated normal monocytes was potently angiogenic in 11/13 corneas, conditioned medium from LPS-activated scleroderma monocytes was angiogenic in only 3/14 corneas. Levels of the angiogenic cytokine tumor necrosis factor-alpha (TNF-alpha) were measured in conditioned medium from scleroderma and normal monocytes. TNF-alpha levels were not significantly different in patient and control groups and thus do not account for the decreased angiogenic activity exhibited by scleroderma monocytes. As monocytes require activation to produce angiogenic activity, we determined the cell surface binding of monoclonal antibodies to activation-related (HLA-DR, 3D8, and 8D7) and other (Leu-M5) markers on monocytes by radioimmunoassay. Monocytes were cultured alone, with LPS (5 micrograms/ml), or with interferon-gamma (IFN) (200 units/ml). The usual increase in binding of anti-HLA-DR on stimulation of scleroderma monocytes with IFN was slightly less than that of controls. IFN-stimulated monocytes bound less anti-8D7 than controls. Anti-3D8 and anti-Leu-M5 binding was comparable in both groups. These results suggest that scleroderma monocytes do not produce normal levels of angiogenic activity with LPS stimulation, have some altered markers of activation on their cell surfaces, and may thus contribute to the aberrant vascular proliferation found in this disease.

Constitutive production of angiotensin converting enzyme from rheumatoid nodule cells under serum free conditions

Angiotensin converting enzyme was assayed in serum free culture supernatants from unstimulated rheumatoid nodule cells. Angiotensin converting enzyme was released spontaneously and the angiotensin converting enzyme derived from rheumatoid nodule cells was suppressed in a dose and time dependent manner by the protein synthesis inhibitor cycloheximide. These data suggest the constitutive de novo synthesis of angiotensin converting enzyme by rheumatoid nodule cells.

Biopsychosocial parameters of disease activity in rheumatoid arthritis

The purpose of this study was to examine the applicability of a biopsychosocial model for estimating disease activity in rheumatoid arthritis (RA). Sixty-three patients with RA were evaluated at baseline, 3 months, and 6 months. Joint counts were collected as the measure of disease activity. Peripheral blood immunophenotypic subsets, demographic characteristics, and psychological measures were obtained and entered into hierarchical regression analyses, with the joint count as the dependent variable. Immunophenotypic subsets (that is, CD57+/CD16-, HLA-DR+) were predictive of disease activity at all three time intervals. At baseline and 3 months, psychological variables (that is, helplessness and depression) were significantly related to joint counts, and the full model was highly significant. The conclusion was that the biopsychosocial perspective is useful for estimating RA disease activity.

Enhanced production of neutrophil-activating peptide-1/interleukin-8 in rheumatoid arthritis

Production of the neutrophil-activating peptide (NAP)-1/IL-8 by mononuclear phagocytes from patients with RA and from control subjects was studied under various conditions. Mononuclear cells from bone marrow (BMMC), PBMC, and synovial fluid (SFMC) were cultured for up to 48 h in the absence or presence of Escherichia coli LPS, different interleukins, interferon-gamma, zymosan, or immune complexes, and the neutrophil-stimulating activity released into the culture medium was determined. As shown by neutralization with an antiserum raised against human recombinant NAP-1/IL-8, over 90% of this activity could be attributed to NAP-1/IL-8. In unstimulated mononuclear cells from control individuals and BMMC from RA patients, the production of NAP-1/IL-8 was very low and was enhanced moderately by stimulation with LPS. By contrast, the spontaneous production of NAP-1/IL-8 was 3- to 10-fold higher in PBMC and even much higher in SFMC from RA patients. In all instances, the yield of NAP-1/IL-8 could be enhanced by stimulation in culture. In addition to LPS, rheumatoid factor-containing immune complexes, zymosan, and IL-1 were highly effective in inducing NAP-1/IL-8 production, while IL-3, GM-CSF, tumor necrosis factor (TNF), and IL-2 were somewhat less potent. An inhibitory effect was obtained with IFN-gamma, which significantly decreased the spontaneous NAP-1/IL-8 release from SFMC and the IL-1- and LPS-induced NAP-1/IL-8 from RA and control PBMC. Inhibition was also observed with glucocorticoids. The production of NAP-1/IL-8 was markedly reduced by dexamethasone in phagocytosis-stimulated PBMC, and almost totally inhibited in SFMC obtained from joints after intraarticular administration of betamethasone. By contrast, the cyclooxygenase inhibitor, indomethacin, tended to increase the NAP-1/IL-8 yield from PBMC in culture.

Proliferative response of synovial fluid and peripheral blood mononuclear cells to arthritogenic and non-arthritogenic microbial antigens and to the 65-kDa mycobacterial heat-shock protein

Cellular immune responses to microbial antigens have been implicated in the pathogenesis of some forms of arthritis including reactive arthritis, Reiter's syndrome, ankylosing spondylitis and rheumatoid arthritis. We investigated the proliferative T cell responses of paired peripheral blood (PB) and synovial fluid (SF) mononuclear cells (MC) to so-called arthritogenic bacteria (Yersinia enterocolitica and Salmonella typhimurium), to control antigens, such as Candida albicans, mumps virus and purified protein derivative, to the recombinant mycobacterial 65-kDa heat-shock protein (hsp 65) and the mitogen phytohemagglutinin (PHA) in 16 patients with different inflammatory rheumatic diseases. The [3H]thymidine uptake of unstimulated cells (medium control) as well as the proliferative response to the different antigens tested was markedly increased in SFMC irrespective of the underlying rheumatic disease. In contrast, mitogenic stimulation was decreased in SFMC. The proliferative response to the hsp 65 correlated significantly with the responses to Yersinia, Salmonella and Candida. These results may reflect an enhanced function of SF antigen-presenting cells, different functional properties and subset distributions of PB and SF T cells with a preferential accumulation of helper-inducer/memory T cells or a maintenance of an ongoing immune response by T cells cross-recognizing self epitopes such as epitopes located on the hsp 65. Thus, care should be taken in the interpretation of SF T cell responses to microbial antigens as diagnostic tools in arthritis.

Autoantibody production by severe combined immunodeficient mice reconstituted with synovial cells from rheumatoid arthritis patients

In an attempt to characterize the heterogeneity of the human autoantibody response, mice with severe combined immunodeficiency were reconstituted with synovial or blood lymphocytes from patients with rheumatoid arthritis (RA). Mononuclear cells extracted from synovial fluid or tissue (SMC) were a greatly enriched source of IgM rheumatoid factor (RF)-producing cells compared to the peripheral blood mononuclear cells (PBMC) of rheumatoid arthritis patients or normal donors. Six to nine weeks after reconstitution of mice with synovial mononuclear cells, 0%-39.3% (mean = 11.4%) of total IgM consisted of IgM RF compared to 0%-0.15% (mean = 0.02%) in mice given RA PBMC and 0%-1.2% (mean = 0.34%) in mice given normal PBMC. Detectable levels of IgM RF were maintained in some mice for as long as 20 weeks after transfer. Mice reconstituted with synovial membrane or synovial fluid lymphocytes produced a heterogeneous mixture of immunoglobulins. These included other autoantibodies, such as anti-nuclear and anti-cytoplasmic antibodies, and antibodies to exogenous antigens such as the Epstein-Barr virus nuclear antigen-1 (EBNA-1). This heterogeneity is further illustrated by the demonstration that the sera from mice given synovial cells also contained IgG antibodies possessing all three major VH families (VH1, VH3 and VH4) and the four major V kappa families (V kappa 1 to V kappa 4). Autoantibody production gradually decreased with time even under circumstances where total immunoglobulin levels increased, and elevated production could not be induced by antigenic stimulation. These findings describe a new model for the analysis of human autoantibody production.

Monocyte activation in early onset rheumatoid arthritis

Monocytes from peripheral blood and synovial fluid of patients with definite and classic rheumatoid arthritis spontaneously produced significantly greater amounts of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and interleukin-1 beta (IL-1 beta) than samples of peripheral blood from normal controls. Peripheral blood monocytes from patients with rheumatoid arthritis produced significantly greater amounts of PGE2 than control samples when stimulated with lipopolysaccharide. There were no significant differences in the spontaneous release of superoxide or N-acetyl-beta-D-glucosaminidase by peripheral blood monocytes between patients and healthy controls. Both stimulated and unstimulated peripheral blood monocytes from patients with definite or classic rheumatoid arthritis produced significantly greater amounts of PGE2 than samples from normal controls. This was true, regardless of the stage of disease and the presence or absence of roentgenological joint abnormalities. Amounts of N-acetyl-beta-D-glucosaminidase released by peripheral blood monocytes from patients correlated positively with the erythrocyte sedimentation rate (ESR) and negatively with duration of disease. Amounts of IL-1 beta and N-acetyl-beta-D-glucosaminidase released from the peripheral blood monocytes of patients who had had their disease for less than one year were significantly higher than those of normal controls. There were no significant correlations between the types of treatment and the amounts of PGE2, LTB4, IL-1 beta or N-acetyl-beta-D-glucosaminidase released by peripheral blood monocytes in patients with rheumatoid arthritis. The findings suggest that monocytes are activated in patients with rheumatoid arthritis both at the onset of disease and during its chronic phase, and that they produce large amounts of mediators which may have a role in the induction and extension of the inflammatory process which leads to tissue damage.

Mononuclear cells enhance prostaglandin E2 production of polymorphonuclear leukocytes via tumor necrosis factor alpha

To clarify the interactions between mononuclear cells and polymorphonuclear leukocytes, and to identify the cytokine(s) that mediate the interaction, the effects of a culture supernatant of LPS-stimulated mononuclear cells on production of arachidonic acid metabolites of polymorphonuclear cells were studied. The culture supernatant of LPS-stimulated mononuclear cells increased production of prostaglandin E2 of polymorphonuclear cells. TNF alpha, but not IL-1, IL-2, IL-6, or IFN gamma, enhanced the prostaglandin E2 production when added in vitro. Additionally, an anti-rTNF alpha monoclonal antibody inhibited the stimulating activity of the culture supernatants. TNF alpha, produced by mononuclear cells, appears to play an important role in the development of inflammation, such as rheumatoid arthritis, by enhancing the arachidonic acid metabolism of the polymorphonuclear cells.

Synovial fluid antigen-presenting cells unmask peripheral blood T cell responses to bacterial antigens in inflammatory arthritis

We and others have previously shown that synovial fluid (SF) mononuclear cells (MC) from patients with both reactive arthritis and other inflammatory arthritides proliferate in vitro in response to bacteria clinically associated with the triggering of reactive arthritis. In all cases, such SFMC responses are greater than the corresponding peripheral blood (PB) MC responses, often markedly so, and the mechanism for this is unclear. We have investigated this phenomenon by comparing the relative abilities of irradiated non-T cells derived from PB and SF to support autologous T cell responses to ReA-associated bacteria. Seven patients whose SFMC had been shown previously to respond to bacteria were studied. We demonstrate antigen-specific responses of PB T cells to bacteria in the presence of SF non-T cells which are in marked contrast to the minimal responses of either unfractionated PBMC or PB T cells reconstituted with PB non-T cells. We also show that PB, but not SF T cells respond strongly to autologous SF non-T cells in the absence of antigen or mitogen. These findings demonstrate that SF antigen-presenting cells (APC) are potent activators of PB T cells. We conclude that the contrasting responses of SFMC and PBMC to bacterial antigens may be accounted for at least in part by an enhanced ability of SF APC to support T cell proliferative responses.

The prevalence and distribution of macrophages bearing Fc gamma R I, Fc gamma R II, and Fc gamma R III in synovium

Fc-receptors for IgG (Fc gamma R) are important triggers of effector function in macrophages. We have investigated the distribution of cells bearing Fc gamma R I, Fc gamma R II, and Fc gamma R III in 14 synovia and 3 nodules from rheumatoid arthritis (RA) patients, using monoclonal antibodies on serial cryostat sections. 8 osteoarthritis (OA), 2 ankylosing spondylitis (AS) patients and one sarcoid patient were also studied. Significant numbers of macrophages bearing Fc gamma R were present in inflamed synovial tissue with no significant difference in relative frequency between RA and OA. There was no correlation with the degree of lymphocytic infiltration. Distinctive staining patterns for the three Fc-receptors suggest differential regulation of these molecules on macrophages in synovium.

Cytokines in chronic inflammatory arthritis. III. Rheumatoid arthritis monocytes are not unusually sensitive to gamma-interferon, but have defective gamma-interferon-mediated HLA-DQ and HLA-DR induction

Macrophages present in the synovium and synovial fluid of patients with rheumatoid arthritis (RA) express large amounts of HLA-DR molecules on their surface, despite low levels of gamma-interferon (gamma-IFN) in the joint. To determine whether this apparent paradox is the result of increased sensitivity to gamma-IFN in RA, we compared concentrations of gamma-IFN that induced HLA-DR and DQ on peripheral blood monocytes of RA patients and normal donors, using fluorescence-activated cell sorter analysis. Among normal donors, highly variable sensitivity to gamma-IFN was observed. Higher amounts of gamma-IFN were required to induce class II major histocompatibility complex molecules on RA monocytes versus normal monocytes. The maximum amount of HLA-DR that could be induced on RA and normal monocytes was similar; however, peak levels of HLA-DQ were significantly less in RA. Monocytes from patients with other forms of chronic inflammatory arthritis had intermediate HLA-DQ expression after gamma-IFN treatment. These data suggest that an increased sensitivity to gamma-IFN in RA does not account for the high level of HLA-DR expression in the joint. Also, a defect in HLA-DQ and HLA-DR induction by gamma-IFN was observed.

Cytokines in chronic inflammatory arthritis. IV. Granulocyte/macrophage colony-stimulating factor-mediated induction of class II MHC antigen on human monocytes: a possible role in rheumatoid arthritis

Granulocyte/macrophage CSF (GM-CSF) has recently been identified in rheumatoid arthritis (RA) synovial effusions. To study a potential role for GM-CSF and other cytokines on the induction of HLA-DR expression on monocytes and synovial macrophages, we analyzed the relative ability of recombinant human cytokines to induce the surface expression of class II MHC antigens on normal peripheral blood monocytes by FACS analysis. GM-CSF (800 U/ml) (mean fluorescence channel 2.54 +/- 0.33 times the control, p less than 0.001) and IFN-gamma (100 U/ml) (5.14 +/- 0.60, p less than 0.001) were the most potent inducers of HLA-DR. TNF-alpha and IL-4 also increased HLA-DR expression, although to a lesser degree [1.31 +/- 0.06 (p less than 0.02) and 1.20 +/- 0.03 (p less than 0.01), respectively]. IL-1 (40 U/ml), IL-2 (10 ng/ml), IL-3 (50 U/ml), IL-6 (100 U/ml), and CSF-1 (1,000 U/ml) did not affect surface HLA-DR density. GM-CSF also increased HLA-DR mRNA expression and surface HLA-DQ expression, but decreased CD14 (a monocyte/macrophage antigen) expression. The effect of GM-CSF on HLA-DR was not mediated by the generation of IFN-gamma in vitro because it was not blocked by anti-IFN-gamma mAb. GM-CSF was additive with IL-4 and low amounts (less than 3 U/ml) of IFN-gamma and synergistic with TNF-alpha. Because we have recently reported that supernatants of cultured RA synovial cells produce a non-IFN-gamma factor that induces HLA-DR on monocytes, we then attempted to neutralize this factor with specific anti-GM-CSF mAb. Four separate synovial tissue supernatants were studied, and the antibody neutralized the HLA-DR-inducing factor in each (p less than 0.01).

Cells of the monocyte-macrophage series in peripheral blood and synovial fluid in inflammatory arthritis. A preliminary study of cellular phenotype

The phenotype of peripheral blood and synovial fluid cells of the monocyte-macrophage series was studied by FACS to extend previous immunohistological observations made in synovial membranes. The results of this preliminary study suggest that changes can be found in peripheral blood monocytes which might influence diapedesis and interaction with immune complexes. The phenotype of synovial fluid macrophages does not provide evidence of advanced maturation and is most consistent with rapid recruitment of the cells into the joint. Synovial fluid macrophages showed increased expression of the leukocyte integrin p150.95 which functions as an adhesion molecule and complement receptor. This is consistent with our previous observation of upregulation of this molecule on Mph in inflamed synovial membranes. This preliminary study has indicated areas for more detailed analysis with the aim of defining sequential changes in macrophage expression of functional surface molecules in inflammatory arthritis.

Cytokines in chronic inflammatory arthritis. I. Failure to detect T cell lymphokines (interleukin 2 and interleukin 3) and presence of macrophage colony-stimulating factor (CSF-1) and a novel mast cell growth factor in rheumatoid synovitis

Because previous studies showed low levels of IFN-gamma in rheumatoid arthritis (RA) synovial fluid (SF) and synovial tissue (ST) explant supernatants, we assayed RA SF and ST for IL-2 and IL-3-like activity. Using an IL-2 dependent murine CTLL line, 6 of 14 RA SF caused increased thymidine uptake (greater than three times control). The activity was distinct from IL-2 because it was not blocked by antibody to IL-2-R. In addition, IL-2 was not detected (less than 50 pg/ml) in 16 joint samples using an ELISA. Multi-colony-stimulating factor (CSF) activity was measured using two assays that can detect murine IL-3 (mast cell proliferation, and bone marrow CSF). In the mast cell assay, [3H]TdR uptake was 493 +/- 67 cpm for medium, 2,910 +/- 329 cpm in the presence of RA SF (p less than 0.001), 1,246 +/- 156 cpm in the presence of SF from patients with seronegative spondyloarthropathies (p less than 0.001), and 736 +/- 100 cpm in the presence of osteoarthritis SF (p greater than 0.1). In the CSF assay, four of five RA SF and five of five RA ST induced colony formation from bone marrow nonadherent cells. Macrophage colonies were most common, although mixed colonies and granulocytes were occasionally observed. The multi-CSF activity in RA is not due to IL-3 since human rIL-3 was not active in either murine assay, and IL-3 mRNA was not detected in RA synovium. Sephadex column chromatography of RA SF revealed that the mast cell growth factor (approximately 6 x 10(3) mol wt) and the CSF (approximately 40 and 100 x 10(3) mol wt) are distinct. The colony-stimulating aspect of the "IL-3-like" activity in RA SF is likely due to CSF-1 because it is the appropriate mol wt and because the activity was neutralized by specific anti-CSF-1 antibody. Finally, an RIA detected 1.6-25 ng/ml of CSF-1 in RA SF and ST and CSF-1 mRNA was detected in four of five RA synovial tissue samples tested.

Peripheral blood and synovial fluid monocyte activation in inflammatory arthritis. II. Low levels of synovial fluid and synovial tissue interferon suggest that gamma-interferon is not the primary macrophage activating factor

Because synovial fluid monocytes (SFM) in patients with inflammatory arthritis bear an activated phenotype (i.e., high expression of HLA-DR and low expression of the monocyte differentiation antigen Mo2), we assessed the role of gamma-interferon (gamma-IFN) in the activation of these cells. Sensitive and specific radioimmunoassays detected only 0.40 +/- 0.20 units/ml of gamma-IFN in the SF of patients with rheumatoid arthritis (RA) and 0.61 +/- 0.67 units/ml of gamma-IFN in the SF of patients with other forms of chronic inflammatory arthritis. There was no detectable alpha-IFN in any SF studied by radioimmunoassay. Bioassays failed to detect nonimmunoreactive IFN. Synovial tissue (ST) explants produced very little gamma-IFN (0.14 +/- 0.091 units/ml), and production was not increased by the presence of indomethacin in the cultures or by removal of adherent cells. However, gamma-IFN was produced if ST was cultivated in the presence of phytohemagglutinin. In SF and ST supernatants, gamma-IFN-mediated induction of HLA-DR on monocytes was inhibited, even though the amount of immunoreactive IFN was not affected. Prostaglandin E2 was shown to be one possible inhibitor. We demonstrated that a factor that induces HLA-DR on some individuals' peripheral blood monocytes, and cannot be neutralized by monoclonal anti-gamma-IFN antibody, is present in SF and ST supernatants. These data suggest that activation of SFM may occur by mechanisms other than gamma-IFN.