Is high titre ANA specific for connective tissue disease?

OBJECTIVE

A positive antinuclear antibody (ANA), while sensitive, is not specific for systemic lupus erythematosus or connective tissue diseases (CTD). The purpose of the present study was to review those sera with a high titre (> or = dilutions above screening) ANA and determine from a review of the charts if these higher titres offered a satisfactory specificity for CTD.

METHODS

All FANA testing in this region is carried out in one of two related laboratories. We reviewed the medical records of patients who had a positive ANA at a titre 4 dilutions above screening at this city-wide laboratory over a 6-month period to determine whether this titre ("high titre") may offer relative diagnostic certainty. Antibodies to extractable nuclear antigens (ENA) and native DNA were also obtained.

RESULTS

422 ANA results were positive at high titre. The medical record was available for review in 320 patients, of whom 238 (75%) were seen by a specialist physician, almost always including a rheumatologist. Our review determined that 35% had a diagnosis of connective tissue disease, 21% had a diagnosis of a possible/probable inflammatory disease, 16% had an alternative specific diagnosis provided, and in 29% no final disease specific diagnosis was recorded but CTD was not suggested to us or the specialist by the data available. One or more anti-ENA antibodies and/or anti-DNA were positive in 69 (22%) and 8% of the sera tested respectively.

CONCLUSION

While long term follow-up is still required, a significant proportion of patients with high titre ANA have no CTD at the time of testing. Setting a higher cutoff for reporting of ANA may not increase specificity sufficiently to make it a useful alternative or addition to reporting a positive or negative value at screening titre alone.

[Increased occurrence of autoimmune thyroiditis in patients with chronic rheumatoid arthritis]

The frequent occurrence of both rheumatoid arthritis and autoimmune thyroiditis was already investigated with in part many conflicting results. We investigated a number of 792 patients (383 of them suffering from rheumatoid arthritis and 409 with osteoarthritis). In all patients antithyroid peroxidase and antithyroglobulin antibodies were determined. Patients with rheumatoid arthritis showed a significantly higher occurrence of circulating thyroid antibodies than those with osteoarthritis (9.1% versus 3.7%, p = 0.0016). We conclude that there exists a cumulate coincidence of both diseases. Patients suffering from rheumatoid arthritis should undergo a thyroid examination especially for the presence of autoimmune thyroiditis.

There is no disease-specific role for streptococci-responsive synovial T lymphocytes in the pathogenesis of psoriatic arthritis

The initiation or exacerbation of psoriasis vulgaris is associated with infections by group A streptococci. T lymphocytes specific for streptococcal antigens or expressing a restricted, for streptococcal superantigens typical T cell receptor Vbeta chain repertoire have been described in psoriatic skin lesions. The aim of our study was, therefore, to clarify whether streptococci-reactive T lymphocytes played a role in the pathogenesis of psoriatic arthritis (PsA), and by which antigens they might be stimulated. Synovial membrane mononuclear cells from patients with PsA and other arthropathies, separated by collagenase digestion, were expanded in interleukin-2-supplemented medium and subsequently cloned in a representative cloning procedure. The T cell lines and about 30% of the T cell clones proliferated in response to preparations of group A streptococci but not to other bacteria as tested by [3H]thymidine incorporation assays. Interestingly, they did not proliferate in response to exotoxin-negative streptococci, but did so in response to the streptococcal pyrogenic exotoxins A and C, which are known to be superantigens. Accordingly, no HLA-DR restriction was seen for the proliferative response. The remaining 70% of the established T cell clones did not react to an antigen of group A streptococci. Our results show that in patients with PsA, osteoarthritis or rheumatoid arthritis a significant number of synovial T lymphocytes were responsive to streptococcal superantigens, but not to conventional streptococcal antigens. A disease-specific role of streptococci-reactive T lymphocytes in the pathogenesis of PsA is, therefore, unlikely.

Tryptophan catabolism in synovial fluid of various arthropathies and its relationship with inflammatory cytokines

Synovial fluids (SF) from patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), gout, and osteoarthritis (OA) were investigated for the levels of interleukin (IL)-1 beta, IL-6 and IL-8, tryptophan (Trp) and indoleamine 2,3-dioxygenase (IDO) activity. Significant differences exist in the levels of IL-1 beta between inflammatory arthritides RA, PsA and gout and non inflammatory arthritis, such as OA. The highest concentration of IL-1 beta was found in RA, that showed high levels also of IL-6 and IL-8. In the same disease we also found the highest IDO activity and the lowest Trp concentration. In addition, IDO activity seems to be related with the decrease in Trp, as demonstrated by the inverse correlation found between these two substances in the SF of all patients.

Synovial hyperplasia in HTLV-I associated arthropathy is induced by tumor necrosis factor-alpha produced by HTLV-I infected CD68+ cells

OBJECTIVE

To investigate the pathogenic role of macrophage lineage (CD68+) cells in synovial proliferation in patients with human T cell leukemia virus I (HTLV-I) associated arthropathy (HAAP).

METHODS

Synovial tissues obtained from 3 patients with HAAP and 3 patients with osteoarthritis (OA) were examined for the expression of tumor necrosis factor-alpha (TNF-alpha) mRNA, HTLV-I tax/rex mRNA, and number of CD68 by in situ reverse transcription assay and immunohistochemistry. Western blot and flow cytometric analyses were used to determine TNF-alpha production in HTLV-I infected synoviocytes. Changes in CD68+ cell population were examined by flow cytometric analysis. Proliferative effects of supernatants of HTLV-I infected synoviocytes on normal synoviocytes were also determined.

RESULTS

TNF-alpha and HTLV-I tax/rex mRNA were preferentially expressed in CD68+ cells in HAAP synovia. Infection of OA synoviocytes by HTLV-I resulted in preferential expression in CD68+ cells, and these cells produced TNF-alpha. Supernatants of HTLV-I infected synoviocytes significantly enhanced the proliferation of normal synoviocytes through a TNF-alpha dependent pathway.

CONCLUSION

Our results suggest HTLV-I viral tropism for CD68+ cells, and that HTLV-I infected synoviocytes were induced to produce TNF-alpha, which enhances synovial proliferation in HAAP.

Functional genomic analysis in arthritis-affected cartilage: yin-yang regulation of inflammatory mediators by alpha 5 beta 1 and alpha V beta 3 integrins

Osteoarthritis-affected cartilage exhibits enhanced expression of fibronectin (FN) and osteopontin (OPN) mRNA in differential display and bioinformatics screen. Functional genomic analysis shows that the engagement of the integrin receptors alpha 5 beta 1 and alpha v beta 3 of FN and OPN, respectively, have profound effects on chondrocyte functions. Ligation of alpha 5 beta 1 using activating mAb JBS5 (which acts as agonist similar to FN N-terminal fragment) up-regulates the inflammatory mediators such as NO and PGE2 as well as the cytokines, IL-6 and IL-8. Furthermore, up-regulation of these proinflammatory mediators by alpha 5 beta1 integrin ligation is mediated via induction and autocrine production of IL-1 beta, because type II soluble IL-1 decoy receptor inhibits their production. In contrast, alpha v beta 3 complex-specific function-blocking mAb (LM609), which acts as an agonist similar to OPN, attenuates the production of IL-1 beta, NO, and PGE2 (triggered by alpha 5 beta 1, IL-1 beta, IL-18, or IL-1 beta, TNF-alpha, plus LPS) in a dominant negative fashion by osteoarthritis-affected cartilage and activated bovine chondrocytes. These data demonstrate a cross-talk in signaling mechanisms among integrins and show that integrin-mediated "outside in" and "inside out" signaling very likely influences cartilage homeostasis, and its deregulation may play a role in the pathogenesis of osteoarthritis.

IgG antibodies to type II collagen reflect inflammatory activity in patients with rheumatoid arthritis

OBJECTIVE

To determine the clinical significance of IgG antibodies to type II collagen (CII) and to define any correlation of antibodies to CII with the inflammatory response in patients with rheumatoid arthritis (RA).

METHODS

IgG antibodies to native human type II collagen (IgG anti-CII) were measured in sera and synovial fluid (SF) from patients with RA, patients with osteoarthritis (OA), and healthy controls by an improved ELISA. Demographic, clinical, and laboratory data including tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) levels were also obtained at the time of sampling in patients with RA.

RESULTS

The median level and positivity for circulating IgG anti-CII were higher in patients with RA (n = 297) than patients with OA (n = 34) and healthy controls (n = 50) (p < 0.001). The titers of IgG anti-CII in SF were also higher in RA (n = 45) than in OA (n = 16) (p < 0.001). In paired samples, the levels of IgG anti-CII were significantly higher in SF compared to the sera in patients with RA (n = 45) (p < 0.001), but levels were not different in patients with OA (n = 16). Circulating IgG anti-CII converted from positive to negative in 13 patients (10.7%) and from negative to positive in 18 patients (14.8%) among 122 patients with RA in whom IgG anti-CII were monitored sequentially at a mean interval of 12.2 months. IgG anti-CII positive patients (n = 98) had shorter disease duration (p = 0.04) and less frequent deformity (p = 0.013), and higher median erythrocyte sedimentation rate (ESR) (p = 0.001) and C-reactive protein (CRP) (p < 0.001) than IgG anti-CII negative patients (n = 120). The levels of IgG anti-CII correlated with CRP (r = 0.270) and ESR (r = 0.253). CRP decreased significantly in patients (n = 13) who converted from IgG anti-CII positive to negative (p = 0.013). IgG anti-CII positive patients (n = 40) had higher levels of TNF-alpha and IL-6 than negative patients (n = 40) (p < 0.001). Levels of IgG anti-CII correlated well with TNF-alpha (r = 0.617) and IL-6 (r = 0.347).

CONCLUSION

Increased IgG anti-CII in sera and SF in RA correlated directly with acute phase reactants and the proinflammatory cytokines TNF-alpha and IL-6. Our data suggest that IgG anti-CII could reflect inflammatory activity with a potential to destroy cartilage in the early stages of RA.

High levels of IL-17 in rheumatoid arthritis patients: IL-15 triggers in vitro IL-17 production via cyclosporin A-sensitive mechanism

Recent data suggest that IL-15 plays an important role in the pathogenesis of rheumatoid arthritis. In the present study, we hypothesized that elevated in the joints of rheumatoid arthritis, but not osteoarthritis, patients, IL-15 may exert its proinflammatory properties via the induction of IL-17, a cytokine known to stimulate synoviocytes to release several mediators of inflammation including IL-6, IL-8, GM-CSF and PGE2. To test this hypothesis, we first measured the levels of IL-17 and IL-15 using specific ELISA and found that synovial fluids of patients with rheumatoid arthritis, but not with osteoarthritis, contain high levels of these cytokines. A strong correlation between IL-15 and IL-17 levels in synovial fluids was observed. Among tested factors, LPS and TNF-alpha failed, IL-15 and IL-2 were equipotent, and PMA + ionomycin was far more efficient in the induction of IL-17 secretion by PBMCs isolated from healthy blood donors. Interestingly, synovial fluid cells, in contrast to PBMCs isolated from patients with rheumatoid arthritis, but not osteoarthritis, respond to PMA + ionomycin with much lower, comparable to IL-15-triggered IL-17 secretion. Moreover, PMA + ionomycin-triggered IL-17 secretion is completely or partially blocked in the presence of low doses of cyclosporin A or high doses of methylprednisolone, respectively. IL-15-triggered IL-17 secretion by PBMCs was completely inhibited by these drugs. Thus, our results suggest for the first time that IL-15 may represent a physiological trigger that via cyclosporin A and steroid sensitive pathways leads to the overproduction of IL-17 in the joints of rheumatoid arthritis patients.

The lupus erythematosus cell phenomenon: comparative analysis of antichromatin antibody specificity in lupus erythematosus cell-positive and -negative sera

OBJECTIVE

To compare and investigate antihistone and antichromatin antibody responses as well as clinical variables in patients with systemic lupus erythematosus (SLE) who were either positive (LEC+) or negative (LEC-) for the lupus erythematosus (LE) cell phenomenon.

METHODS

The binding properties of LEC+ and LEC- SLE sera to chromatin-associated nuclear antigens (histones H1, H2A, H2B, H3, H4; complexes of H2A-H2B, [H2A-H2B]-DNA, H1-DNA; total and H1-stripped chromatin; native and denatured DNA) were investigated. In addition, sera from patients with drug-induced lupus (by procainamide, hydralazine, or quinidine), as well as from patients with rheumatoid arthritis and osteoarthritis, were assessed. Enzyme-linked immunosorbent assay was used to detect specific antibody binding.

RESULTS

Mirroring the important role of histone H1 in the formation of LE cells, anti-histone H1 reactivity was 8-fold higher in LEC+ sera than in LEC- sera. In addition, reactivities to most of the other antigens tested, i.e., other histones and histone-DNA complexes as well as chromatin and DNA, were significantly higher in LEC+ sera than in LEC- sera. All but 1 serum sample from the patients with drug-induced lupus were negative for LE cell formation as well as for anti-histone H1 reactivity, but displayed high antibody reactivities to histone-DNA complexes, including chromatin. Sera from patients with rheumatoid arthritis and osteoarthritis did not show significant binding to these antigens. When comparing the clinical features of LEC+ and LEC- SLE patients, severe organ involvement, including nephritis and central nervous system involvement, was common in the LEC+ group, but rare in the LEC- group.

CONCLUSION

A positive LE cell phenomenon not only correlated with the presence of high anti-histone H1 antibody levels in SLE, but also indicated serologically and clinically active disease with major organ involvement.

Association between IgM response to IgG damaged by glyoxidation and disease activity in rheumatoid arthritis

OBJECTIVE

To determine the association of serum IgG advanced glycation endproducts (AGE) and IgM anti-IgG-AGE antibodies with clinical measurements of rheumatoid arthritis (RA) disease activity.

METHODS

The study group consisted of 62 patients with RA and 16 control patients with osteoarthritis. Patient derived variables included perceived disease activity (10 cm visual analog scale, VAS) and Health Assessment Questionnaire (HAQ) results. Clinical measures of RA activity consisted of tender and swollen joint counts and a physician evaluation of disease activity (by VAS) as well as history of nodules, bone erosions, Sjogren's syndrome, and vasculitis documented by chart review. Patient sera were evaluated for glucose, glycosylated hemoglobin, and presence of RF, IgG-AGE and IgM anti-IgG-AGE. The nitroblue tetrazolium colorimetric and aminophenyl boronic acid methods were used for measurement of IgG-AGE, along with an ELISA for measurement of IgM anti-IgG-AGE.

RESULTS

Significant correlations were found between the presence of IgM anti-IgG-AGE and clinical measurements of swollen joint count and physician VAS.

CONCLUSION

IgM anti-IgG-AGE appears to be associated with clinical measurements of RA activity and represents a new marker of more active disease in RA.

Immunomodulatory properties of rumalon, a glycosaminoglycan peptide complex, in patients with osteoarthritis: activation of T helper cell type 2 cytokines and antigen-specific IgG4 antigen-specific igG4 antibodies

OBJECTIVE

To assess the immunogenic properties of the glycosaminoglycan peptide complex Rumalon, an aqueous extract of bovine cartilage and bone marrow frequently used in patients with osteoarthritis (OA).

METHODS

Sera from 31 patients with OA who had received several series of Rumalon injections (Group 1, n = 17: before therapy and after one injection series; Group 2, n = 6: after 2-3 injection series; Group 3, n = 4: after 4-8 injection series; Group 4, n = 4: after 9-18 injection series) were tested by ELISA for antibodies against Rumalon and its components as well as by a double sandwich ELISA for type 1 [interferon-gamma, interleukin 2 (IL-2)] and type 2 cytokines (IL-4, IL-5, IL-10, IL-13).

RESULTS

After the first injection series antibodies to Rumalon were induced in 7 of the 17 patients that were all negative before therapy. The antibodies were preferentially of the IgG4 type. IgG4 levels were increased during therapy (ELISA optical density x 1000 in Group 1: 73.9 +/- 209.5; Group 4: 1354.5 +/- 307.6), and in Group 4 all patients had developed these antibodies. Upon analysis of cytokine levels, there was a significant increase in IL-5 (Group 1 before therapy 407.4 +/- 257.1 pg/ml, Groups 3 and 4: 1409.4 +/- 963.1 pg/ml; p < 0.001) and to a lesser extent of IL-10 during therapy (Group 1 before therapy 950.2 +/- 867.8 pg/ml, Groups 3 and 4: 2817.8 +/- 3127.3 pg/ml; p < 0.05), while type 1 cytokines were not affected.

CONCLUSION

Rumalon appears to have immunomodulatory properties and preferentially stimulates IgG4 antibodies via the activation of type 2 cytokines in vivo. Whether these phenomena can be correlated with the postulated therapeutic effect of Rumalon in patients with OA remains to be seen, but pain relief via release of endorphins by Th2 cells could be one explanation.

The migratory and phagocytic activity of polymorphonuclear leukocytes in rheumatoid arthritis and osteoarthritis patients

Polymorphonuclear neutrophils (PMN) play a central role in the elimination of most extracellular pathogenic microorganisms and any impairment of their functions therefore predisposes to defect immune defence. We investigated the migratory and phagocytic functions of the PMNs isolated from peripheral blood and synovial fluid of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). The results suggest that in RA the number and the migratory but not phagocytic capacity of synovial fluid (SF) neutrophils were enhanced, while in OA they were significantly decreased in synovial fluid cells comparatively with peripheral blood (PB). The migratory function of both PB and SF cells from RA patients was increased comparatively with that of the cells from OA patients. We found the different abnormal functions in synovial fluid neutrophils from RA and OA patients. These results may help to elucidate the underlying mechanism which leads to severe joint destruction and different susceptibility to infectious diseases in patients with rheumatic disorders.

Autocrine regulation of collagenase 3 (matrix metalloproteinase 13) during osteoarthritis

OBJECTIVE

To correlate the increased collagenase production previously seen in chondrocytes isolated from osteoarthritic (OA) lesions and the expression of cytokines and cytokine receptors.

METHODS

Chondrocytes were isolated from OA cartilage and characterized for synthesis of collagenases, cytokines, and cytokine receptors by Northern and Western blot analyses, RNA protection assay, and flow cytometry.

RESULTS

Chondrocytes located in cartilage proximal to the macroscopic OA lesions bound more tumor necrosis factor alpha (TNFalpha) and interleukin-1beta (IL-1beta) compared with chondrocytes isolated from morphologically normal cartilage from the same joint. In response to TNFalpha stimulation, messenger RNA (mRNA) levels for the IL-1 receptor I (IL-1RI), IL-1RII, TNF receptor II (TNFR II), and IL-6 receptor as well as the level of proinflammatory cytokines, such as IL-1alpha, IL-1beta, lymphotoxin beta, TNFalpha, and IL-6, also increased. In contrast, treatment with transforming growth factor beta1 (TGFbeta1) resulted in down-regulation of matrix metalloproteinase 1 (MMP-1) and MMP-13 concomitant with a reduction in the levels of mRNA for IL-1RI, IL-1RII, TNFRI, and TNFRII and proinflammatory cytokine levels. In contrast, the levels of mRNA for TGFbeta receptor I, TGFbeta1, and TGFbeta3 were up-regulated.

CONCLUSION

These data show that TGFbeta1 has antagonistic effects upon OA chondrocytes, in contrast to the effects seen with TNFalpha. The cyclical course of OA, where a period of active disease is followed by a period of remission, can be explained by a sequential pattern of cytokine stimulation followed by a feedback inhibition of autocrine cytokine production and cytokine receptor expression, thus affecting collagenase synthesis.

The role of IL-12 in inflammatory activity of patients with rheumatoid arthritis (RA)

The aim of this study was to investigate the role of IL-12 in patients with RA. IL-12 (p70) and its associated cytokines were measured in sera and synovial fluid (SF) using an enzyme-linked immunosorbent method. Seven American College of Rheumatology (ACR) core set measures as well as IL-12 levels were sequentially monitored at the commencement and 4 months after treatment with a low-dose steroid and disease-modifying anti-rheumatic drugs (DMARDs). In sera, 64 (42.2%) of 152 RA patients had detectable concentrations of IL-12 (p70), whereas one (1.4%) of 69 osteoarthritis (OA) patients and five (10%) of 50 healthy controls had detectable IL-12 (P < 0.001). The median level of circulating IL-12 was also higher in RA patients (P < 0.001). In SF, the number of patients with detectable IL-12 and the median IL-12 levels were significantly higher in RA patients (n = 53) than in OA patients (n = 22). In paired samples (n = 53) of sera and SF from RA patients, IL-12 levels were higher in the SF than in sera (P < 0.001). Patients with detectable IL-12 (n = 51) in sera had higher tender joint scores (P = 0.003), swollen joint scores (P < 0.001) and C-reactive protein (CRP; P = 0.036), than those without (n = 55). Four months after treatment with DMARDs, the improved group showed a larger IL-12 decrease than the non-improved group (P = 0.017). The levels of IL-12 correlated positively with those of IL-2, interferon-gamma, IL-6, and tumour necrosis factor-alpha, but were correlated inversely with those of IL-10. Our results demonstrate that IL-12 levels reflect RA disease activity and that IL-12 is involved in the production of proinflammatory cytokines. An IL-12 blockade could be useful for the treatment of RA.

Intracytoplasmic Th1 and Th2 cytokines in rheumatoid arthritis blood and synovial tissue

In rheumatoid arthritis (RA), T cells have been proposed either as a main actor or as an epiphenomenon in such a primarily synoviocyte-driven disease. A major issue remains the remarkable paradox between the T cell infiltrate and the relative failure to detect definite markers of their activity. To determine the Th1/Th2 cytokine profile in RA synovium, we used a single cell flow cytometric assay for interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-4 and IL-10 in paired peripheral blood (PB) and synovial tissue (ST) lymphocytes from RA and osteoarthritis (OA) patients and PB lymphocytes from healthy controls. Cytokines were undetectable in unstimulated PB and ST lymphocytes. More stimulated PB and ST CD4(+)lymphocytes produced IFN-gamma than IL-4, for all individuals tested. RA PB CD4(+)lymphocytes showed the same Th1 cytokine pattern as normal controls. No increase of such a Th1 profile was observed for ST lymphocytes. A specific recruitment of T CD4(+)lymphocytes in the rheumatoid inflamed synovium could not be concluded on the basis of these results.

A proinflammatory role for IL-18 in rheumatoid arthritis

IL-18 is a novel cytokine with pleiotropic activities critical to the development of T-helper 1 (Th1) responses. We detected IL-18 mRNA and protein within rheumatoid arthritis (RA) synovial tissues in significantly higher levels than in osteoarthritis controls. Similarly, IL-18 receptor expression was detected on synovial lymphocytes and macrophages. Together with IL-12 or IL-15, IL-18 induced significant IFN-gamma production by synovial tissues in vitro. IL-18 independently promoted GM-CSF and nitric oxide production, and it induced significant TNF-alpha synthesis by CD14(+) macrophages in synovial cultures; the latter effect was potentiated by IL-12 or IL-15. TNF-alpha and IFN-gamma synthesis was suppressed by IL-10 and TGF-beta. IL-18 production in primary synovial cultures and purified synovial fibroblasts was, in turn, upregulated by TNF-alpha and IL-1beta, suggesting that monokine expression can feed back to promote Th1 cell development in synovial membrane. Finally, IL-18 administration to collagen/incomplete Freund's adjuvant-immunized DBA/1 mice facilitated the development of an erosive, inflammatory arthritis, suggesting that IL-18 can be proinflammatory in vivo. Together, these data indicate that synergistic combinations of IL-18, IL-12, and IL-15 may be of importance in sustaining both Th1 responses and monokine production in RA.

Molecular IgV(H) analysis demonstrates highly somatic mutated B cells in synovialitis of osteoarthritis: a degenerative disease is associated with a specific, not locally generated immune response

In osteoarthritis (OA), the synovial tissue exhibits a nonfollicular inflammatory infiltration with a characteristic arrangement of lymphocytes and plasma cells. These arrangements are either small perivascular aggregates with plasma cells surrounding the lymphocytes or small groups of plasma cells, located in the vicinity of small blood vessels. These patterns suggest that B lymphocytes directly differentiate into plasma cells. To understand the B-cell response in OA, we analyzed the V(H) genes from B cells of synovial tissue of nine OA patients (average age, 71.5+/-10.5 years; six female and three male). V(H) gene repertoires were determined from RNA prepared from tissue cryosections and from DNA of single isolated B lymphocytes and plasma cells. The inflammatory infiltrate was analyzed immunohistochemically by detecting CD20, Ki-M4 (follicular dendritic cells), CD4, IgG, IgM, IgA, Ki-67, and by simultaneous demonstration of the plasma-cell-specific antigen CD138 (syndecan-1) and factor VIII. The molecular data demonstrate B cells with a high number of somatic mutations (average, 16.5 to 19.8), and high ratios of replacement to silent mutations in the small lymphocytic/plasmacellular aggregates of OA. In the tissue cryosections, the values of the sigmaR/sigmaS at the complementarity determining regions were 5.3 and 2.0 in the framework regions. For both the isolated B lymphocytes and plasma cells, the value of this ratio in the complementarity determining regions was 3.5. In the framework regions, the values of this ratio were 2.0 for the isolated B cells and 1.8 for the plasma cells. B lymphocytes and plasma cells exhibited a distribution not described thus far. Two patterns of B-cell distribution could be observed: (a) Centrally located CD20+ B and CD4+ and CD8+ T lymphocytes were surrounded directly by IgG (predominantly) or IgA and IgM plasma cells. No proliferating Ki-67-positive cells and no follicular dendritic cells (germinal centers) could be detected in the aggregates; (b) Plasma cells (predominantly IgG) were located directly near endothelial cells of small blood vessels. The finding of highly mutated V(H) genes in B lymphocytes and the characteristic arrangement of B lymphocytes and plasma cells suggests that B cells, which participate in OA synovialitis, have undergone germinal center reaction at different sites. This may explain the low inflammatory infiltration without germinal centers in OA, which is a feature of this primarily degenerative joint disease.

Cytokines and their role in the pathophysiology of osteoarthritis

The specific causative agent of the pathological process of osteoarthritis (OA) has not yet been identified, however, episodic inflammation at the clinical stage is now a well documented phenomenon and believed to be involved in the disease progression. Interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) are the predominant proinflammatory cytokines synthesized during the OA process. Other cytokines having proinflammatory properties or catabolic factors could also contribute to this pathological condition, and those having antiinflammatory properties may be able to counteract the negative effects of the former on the disease process. In this chapter, we will review cytokine interactions and their modulatory effects on joint articular tissue metabolism, including their stimulatory and/or inhibitory actions, and their potential relevance to OA. We will also briefly survey the major biological factors, in relation to cytokines, that look promising for future therapeutic approaches.

Fundamental pathways in osteoarthritis: an overview

Osteoarthritis (OA) is a significant world-wide health problem owing to the progressive and debilitating nature of the condition which results in high morbidity and a marked decrease in the quality of life. Significant advances in the medical and surgical management of OA have resulted from an understanding of the fundamental pathways governing the health and disease of synovial joint tissues. Continuing investigations into the nature of synovial joint pathophysiology at both the molecular and biochemical level should pave the way for the development of novel therapeutic strategies, including gene therapy and tissue engineering, in the treatment of the OA patient.

Metabolic disturbances and synovial joint responses in osteoarthritis

Previously held views that the pathogenesis of idiopathic osteoarthritis (OA) originated in the synovial joint and was not influenced by systemic metabolic disturbances in the patient is inconsistent with recent data demonstrate skewing of the growth hormone/insulin-like growth factor-1 axis in the symptomatic OA patient. In light of this novel information, the role of growth hormone and insulin-like growth factor-1 in the pathogenesis and progression of OA requires further definition. In male patients with OA, the red blood cell sequesters more growth hormone than an aged-matched control group. Thus, this growth hormone "depot" may provide a mechanism for removal of "toxic" levels of growth hormone from the circulation. Storage of "excess" growth hormone in red cells may reduce the inflammatory or otherwise undesirable "toxic" actions of GH. In some patients, serum growth hormones levels may exceed three-times the average value considered normal. These "episodic" variations in growth hormone levels may play a significant role in the elevated levels of serum growth hormone seen in the OA patient. The connection between elevated growth hormone and decreased insulin-like growth factor-1 levels and the defined cartilage anabolic and catabolic pathways defined in in vitro assays of articular cartilage derived from the OA patients remain to be more precisely defined. However, the dampened insulin-like growth factor-1 response in OA coupled with elevated cartilage extracellular matrix degradation (mediated by metalloproteinases) and depressed compensatory biosynthesis (induced and perpetuated by the presence of cytokines such as interleukin-1 and tumor necrosis factor-alpha) may, in fact, act synergistically to suppress normal cartilage repair mechanisms thus resulting in progressive destructive lesions of the cartilage and bone.

Canine rheumatoid arthritis and inflammatory cytokines

Bioassays were developed to detect canine pro-inflammatory cytokines. These enabled characterisation of these cytokines and their isoforms and provided means for their assay in the joints of dogs with different naturally occurring arthropathies. Canine IL-1 was detected by its induction of proliferation of D10(N4)M cell line, whilst IL-6 had a proliferative effect on B9 cell line. TNFalpha had a cytotoxic effect on WEHI 164 (13) cells. Partial purification of the cytokines was achieved by FPLC ion-exchange chromatography and two isoforms of IL-1 were shown, possibly corresponding to IL-1alpha and IL-1beta. TNFalpha only appeared as one isoform whereas IL-6 showed at least five isoforms, possibly corresponding to the other molecules in the IL-6 family, such as IL-11 and oncostatin M. Analysis of synovial fluids from dogs with osteoarthritis (OA) and rheumatoid arthritis (RA) showed that IL-1 and TNFalpha bioactivity was not readily detectable at increased levels in diseased joints but that IL-6 was significantly increased in both diseases. It is now important to determine the role of IL-6 in OA and RA in the dog, particularly in the induction of proteolytic enzymes which lead to cartilage loss.

Interleukin-8, interleukin-10, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression levels are higher in synovial tissue from patients with rheumatoid arthritis than in osteoarthritis

The aim of this work was to determine differences in pro- and anti-inflammatory cytokine and adhesion molecule expression in synovial tissue from patients with rheumatoid arthritis (RA) or osteoarthritis (OA). Synovial tissue samples were obtained from patients with RA and OA, and from healthy individuals. The expression of mRNA of interleukin (IL)-1beta, IL-4, IL-6, IL-8, IL-10, IL-13, tumour necrosis factor-alpha (TNF-alpha) and transforming growth-factor-beta1 (TGF-beta1) was evaluated by the polymerase chain reaction (PCR). In addition, IL-8 and IL-10 transcripts were measured by quantitative PCR. The expression of IL-8 and IL-10 proteins was determined by immunoperoxidase staining. To evaluate the inflammatory stage of synovial tissue, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) protein expression was also determined. RA patients were found to display higher levels of adhesion molecules than patients with OA. PCR analysis showed a similar profile of cytokine transcripts between the OA and RA groups. Gene expression of IL-4 and IL-13 in synovium was undetectable. In contrast, IL-1beta, IL-6, IL-8, IL-10, TNF-alpha and TGF-beta1 transcripts were expressed by both groups. Increased levels of IL-8 and IL-10 transcripts and their proteins were observed in synovium from RA patients when compared to patients with OA and healthy controls. Thus, our data show that IL-8, IL-10, ICAM-1 and VCAM-1 expression levels are higher in synovial tissue from patients with RA than in similar tissue from patients with OA.

Flow cytometric analysis of intracellular chemokines in chondrocytes in vivo: constitutive expression and enhancement in osteoarthritis and rheumatoid arthritis

Chemokines play a key role in modulating leukocyte functions at sites of inflammation. To assess chondrocyte contribution to the chemotactic environment of inflamed joints the intracellular content of CC and CXC chemokines was investigated. IL-8, GROalpha, MCP-1, RANTES, MIP-1alpha and MIP-1beta expression was evaluated by flow cytometric analysis and RT-PCR in chondrocytes isolated from cartilage specimens obtained from patients with osteoarthritis and rheumatoid arthritis and multiorgan donors as normal controls. All the chemokines except RANTES were found in normal chondrocytes, with different degrees of staining intensity. In osteoarthritis and rheumatoid arthritis patients, an enhancement of IL-8, GROalpha, MIP-1alpha and MIP-1beta was observed.