Joel A. G. van Roon

Synergistic activity of interleukin-4 and interleukin-10 in suppression of inflammation and joint destruction in rheumatoid arthritis

Rheumatoid arthritis (RA) is a disease dominated by joint inflammation, accompanied by several peripheral inflammatory manifestations (1). Although the etiology of RA is still not fully understood, the pathogenesis is known to involve chronic synovitis leading to destruction of joint tissues (in particular, cartilage and bone) and consequently, serious impairment of joint function (2). Patients also exhibit features of systemic inflammation (such as marked acute-phase responses), and the disease is associated with autoimmune responses, the latter being most clearly displayed in the production of autoantibodies against the IgG Fc regions (rheumatoid factor) (3). The important role of T helper cells, macrophages, dendritic cells (DC), and B cells in local tissue destruction in RA has been described extensively (4–7) (summarized in Figure 1). Macrophages and DC in the RA joint contribute strongly to inflammation by the production of proinflammatory mediators, uptake of (auto-)antigen, and presentation of peptides of processed antigen to T helper cells by class II major histocompatibility complex (MHC) molecules (HLA– DR1 and HLA–DR4, which are linked to RA) together with costimulatory molecules. In addition to the cell–cell contact of T helper cells with macrophages and DC, there are a number of factors that cause costimulation of T helper cells (e.g., interleukin-7 [IL-7], IL-12, IL-15, and IL-18) in the joints of RA patients (8–11). A predominance of Th1 cell activity (defined by interferon-g [IFNg] production) and low Th2 cell activity (defined by IL-4 production) have been demonstrated in RA joints (12–14). This Th1/Th2 imbalance has been shown to strongly enhance activation of macrophages, DC, and B cells by cell–cell contact and secretion of cytokines (15–17). B cells are stimulated to differentiate and produce antigen-specific immunoglobulins, in particular, IgG (3,5). IgG interacts with antigen to form immune complexes, and its Fc constant region binds to Fcg receptors (FcgR), causing activation of macrophages and DC by receptor crosslinkage (18). Apart from activation, this leads to increased and very efficient uptake of antigen, presentation of arthritogenic epitopes, and an increase or persistence of activation of inflammatory cells, and consequently, maintenance or stimulation of the inflammatory cascade. In addition, several other cell types, such as synovial fibroblasts and neutrophils, have been shown to increase joint inflammation and joint destruction (19,20). As a consequence of the above inflammatory response, different cell types in the synovial tissue (ST), articular cartilage, and bone are transformed and destroyed by several mediators, such as cytokines (IL-1b, tumor necrosis factor a [TNFa], IL-15, IL-17), metalloproteinases (matrix metalloproteinase 1 [MMP-1] and MMP-3), and oxygen radicals (10,21–25). This ultimately results in serious impairment of joint function. Several antiinflammatory mechanisms in response to the proinflammatory activity are activated in the RA joint in an attempt to control the dysregulated (auto)immune reactivity. These include the production of cytokines with antiinflammatory properties, such as IL-10, IL-13, and transforming growth factor b, present Supported by the Nationaal Reumafonds (the Dutch League against Rheumatism). Joel A. G. van Roon, PhD, Floris P. J. G. Lafeber, PhD, J. W. J. Bijlsma, PhD, MD: University Medical Center Utrecht, Utrecht, The Netherlands. Address correspondence and reprint requests to Joel A. G. van Roon, PhD, Department of Rheumatology and Clinical Immunology (F01.127), University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. Submitted for publication May 11, 2000; accepted in revised form August 26, 2000.

Relationship between the type I interferon signature and the response to rituximab in rheumatoid arthritis patients

OBJECTIVE To analyze the relationship between the type I interferon (IFN) signature and clinical response to rituximab in rheumatoid arthritis (RA) patients. METHODS Twenty RA patients were treated with rituximab (cohort 1). Clinical response was defined as a decrease in the Disease Activity Score evaluated in 28 joints (DAS28) and as a response according to the European League Against Rheumatism (EULAR) criteria at week 12 and week 24. The presence of an IFN signature was analyzed in peripheral blood mononuclear cells by measuring the expression levels of 3 IFN response genes by quantitative polymerase chain reaction analysis. After comparison with the findings in healthy controls, patients were classified as having an IFN high or an IFN low signature. The data were confirmed in a second independent cohort (n = 31). Serum IFNα bioactivity was analyzed using a reporter assay. RESULTS In cohort 1, there was a better clinical response to rituximab in the IFN low signature group. Consistent with these findings, patients with an IFN low signature had a significantly greater reduction in the DAS28 and more often achieved a EULAR response at weeks 12 and 24 as compared with the patients with an IFN high signature in cohort 2 versus cohort 1. The pooled data showed a significantly stronger decrease in the DAS28 in IFN low signature patients at weeks 12 and 24 as compared with the IFN high signature group and a more frequent EULAR response at week 12. Accordingly, serum IFNα bioactivity at baseline was inversely associated with the clinical response, although this result did not reach statistical significance. CONCLUSION The type I IFN signature negatively predicts the clinical response to rituximab treatment in patients with RA. This finding supports the notion that IFN signaling plays a role in the immunopathology of RA.

The Role of Ectopic Germinal Centers in the Immunopathology of Primary Sjögren's Syndrome: A Systematic Review

OBJECTIVES To determine whether the presence of germinal centers (GCs) in salivary glands of patients with primary Sjögrens syndrome (pSS) is related to the severity of disease course and distinct immunopathology features. METHODS A systematic search was performed in September 2011 for terms and synonyms of Sjögrens syndrome and germinal centers. A total of 80 articles were retrieved, of which 16 were included for (meta-) analysis. RESULTS GC morphology was present in a mean ± SD 25.1 ± 5.0% of pSS patients. Mean lymphocyte focus scores were 1.25 points higher in patients with GCs as compared to those without GCs. Saliva production was reduced in patients with GCs, although this did not reach statistical significance. Percentages of patients positive for rheumatoid factor, anti-Sjögrens syndrome A (SSA), and anti-Sjögrens syndrome B (SSB) antibodies were significantly higher in patients with GCs (mean increase, 15%, 18%, and 18%, respectively). Additionally, patients with GCs were characterized by enhanced levels of local and systemic proinflammatory mediators. Importantly, these patients have a higher risk of lymphoma development (14% versus 1%). CONCLUSIONS Patients with GCs are characterized by more severe disease, although the small number of studies and their design hamper generalizability of results. The precise mechanisms that contribute to the development and persistence of germinal centers in pSS are largely unknown. This and the strongly increased risk of lymphoma development warrant intensive studies for the role of germinal centers in the immunopathology of pSS.

Blockade of the interleukin-7 receptor inhibits collagen-induced arthritis and is associated with reduction of T cell activity and proinflammatory mediators.

OBJECTIVE To study the effects of interleukin-7 receptor α-chain (IL-7Rα) blockade on collagen-induced arthritis (CIA) and to investigate the effects on T cell numbers, T cell activity, and levels of proinflammatory mediators. METHODS We studied the effect of anti-IL-7Rα antibody treatment on inflammation and joint destruction in CIA in mice. Numbers of thymocytes, splenocytes, T cell subsets, B cells, macrophages, and dendritic cells were assessed. Cytokines indicative of Th1, Th2, and Th17 activity and several proinflammatory mediators were assessed by multianalyte profiling in paw lysates. In addition, T cell-associated cytokines were measured in supernatants of lymph node cell cultures. RESULTS Anti-IL-7Rα treatment significantly reduced clinical arthritis severity in association with reduced radiographic joint damage. Both thymic and splenic cellularity were reduced after treatment with anti-IL-7Rα. IL-7Rα blockade specifically reduced the total number of cells as well as numbers of naive, memory, CD4+, and CD8+ T cells from the spleen and significantly reduced T cell-associated cytokines (interferon-γ, IL-5, and IL-17). IL-7Rα blockade also decreased local levels of proinflammatory cytokines and factors associated with tissue destruction, including tumor necrosis factor α, IL-1β, IL-6, matrix metalloproteinase 9, and RANKL. IL-7Rα blockade did not significantly affect B cells, macrophages, and dendritic cells. B cell activity, indicated by serum anticollagen IgG antibodies, was not significantly altered. CONCLUSION Blockade of IL-7Rα potently inhibited joint inflammation and destruction in association with specific reductions of T cell numbers, T cell-associated cytokines, and numerous mediators that induce inflammation and tissue destruction. This study demonstrates an important role of IL-7R-driven immunity in experimental arthritis and indicates the therapeutic potential of IL-7Rα blockade in human arthritic conditions.

Elevated expression of interleukin-7 receptor in inflamed joints mediates interleukin-7–induced immune activation in rheumatoid arthritis

OBJECTIVE To evaluate the expression and functional ability of the high-affinity interleukin-7 receptor (IL-7Ralpha) in patients with rheumatoid arthritis (RA). METHODS Expression of IL-7Ralpha and IL-7 was determined in synovial tissue from RA patients and was compared with that in synovial tissue from patients with undifferentiated arthritis (UA) and osteoarthritis (OA). IL-7Ralpha expression on CD4 T cells, CD19 B cells, and CD14 monocyte/macrophages from RA synovial tissue, synovial fluid, and peripheral blood was also assessed. The proliferative capacity of IL-7Ralpha(bright) and IL-7Ralpha(dim/-) T cells was measured. In addition, we examined IL-7R blockade with soluble human IL-7Ralpha (hIL-7Ralpha) in the prevention of immune activation of peripheral blood mononuclear cells. RESULTS We found significantly higher IL-7Ralpha expression in RA and UA synovial tissue than in OA synovial tissue, and the level of IL-7Ralpha expression correlated significantly with the levels of CD3 and IL-7 expression. CD4 T cells from RA synovial fluid and synovial tissue strongly expressed IL-7Ralpha. A substantial percentage of B cells and macrophages from RA synovial fluid and synovial tissue also expressed IL-7Ralpha, although less prominently than T cells. We found that peripheral blood IL-7Ralpha(bright) T cells that did not express FoxP3 were highly proliferative as compared with IL-7Ralpha(dim/-) T cells that did express high levels of FoxP3. Soluble hIL-7Ralpha inhibited IL-7-induced proliferation and interferon-gamma production by mononuclear cells from RA patients. CONCLUSION Our data suggest that enhanced expression of IL-7Ralpha and IL-7 in RA patients contributes significantly to the joint inflammation by activating T cells, B cells, and macrophages. The inhibition of IL-7R-mediated immune activation by soluble hIL-7Ralpha further indicates an important role of IL-7Ralpha in inflammatory responses in RA, suggesting IL-7Ralpha as a therapeutic target for immunotherapy in RA.

The Soluble Leukocyte-Associated Ig-Like Receptor (LAIR)-2 Antagonizes the Collagen/LAIR-1 Inhibitory Immune Interaction

Leukocyte-associated Ig-like receptor (LAIR)-1 is a collagen-receptor that inhibits immune cell function upon collagen binding. Next to LAIR-1, the human genome encodes LAIR-2, a putative soluble homolog. In this study we show, for the first time, that the LAIR-2 gene is broadly transcribed in human PBMC, mirroring the expression profile of LAIR-1. LAIR-2 protein is expressed as a soluble receptor exhibiting high affinity for various collagen molecules to which it binds in a hydroxyproline-dependent manner. In vitro stimulation of PBMC induces secretion of LAIR-2. We detect high amounts of LAIR-2 in urine of pregnant women, indicating that the soluble receptor is indeed produced in vivo and can be cleared from the body via urine. Furthermore, LAIR-2 levels are increased in synovial fluid of patients with rheumatoid arthritis as compared with osteoarthritis patients. We hypothesize that soluble LAIR-2 may function as a natural competitor for LAIR-1, thereby regulating its inhibitory potential. Indeed, LAIR-2 prevents binding of human LAIR-1 to collagens and LAIR-1 cross-linking in vitro, suggesting that the protein has an immunoregulatory function in vivo. Hence, we reveal a novel mechanism of immune regulation by a soluble LAIR receptor regulating the inhibitory potential of the membrane-bound LAIR-1 via competition for ligands.

Heat-shock protein T-cell epitopes trigger a spreading regulatory control in a diversified arthritogenic T-cell response

Summary: Adjuvant arthritis (AA) in Lewis rats is T‐cell mediated and seems to depend on T cells recognising the 180–188 epitope of mycobacterial heat‐shock protein (hsp) 60. Analysis of arthritogenic T‐cell clone A2b has revealed a mimicry of this particular epitope with an articular cartilage‐associated target T‐cell epitope. Nasal administration of synthetic peptides covering this 180–188 sequence led to epitope‐.specific tolerance and resistance to AA. Since this tolerisation protocol also inhibited avridine arthritis, one may conclude that this form of epitope‐specific tolerance had effectuated a spreading tolerisation at the level of target antigens that included a diverse set of possible arthritis ‐associated antigens.

Celecoxib: considerations regarding its potential disease-modifying properties in osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease characterized by progressive loss of articular cartilage, subchondral bone sclerosis, osteophyte formation, and synovial inflammation, causing substantial physical disability, impaired quality of life, and significant health care utilization. Traditionally, non-steroidal anti-inflammatory drugs (NSAIDs), including selective cyclooxygenase (COX)-2 inhibitors, have been used to treat pain and inflammation in OA. Besides its anti-inflammatory properties, evidence is accumulating that celecoxib, one of the selective COX-2 inhibitors, has additional disease-modifying effects. Celecoxib was shown to affect all structures involved in OA pathogenesis: cartilage, bone, and synovium. As well as COX-2 inhibition, evidence indicates that celecoxib also modulates COX-2-independent signal transduction pathways. These findings raise the question of whether celecoxib, and potentially other coxibs, is more than just an anti-inflammatory and analgesic drug. Can celecoxib be considered a disease-modifying osteoarthritic drug? In this review, these direct effects of celecoxib on cartilage, bone, and synoviocytes in OA treatment are discussed.

Persistence of interleukin 7 activity and levels on tumour necrosis factor alpha blockade in patients with rheumatoid arthritis

Objectives: To identify the mechanism of interleukin (IL)7-stimulated tumour necrosis factor α (TNFα) production and to determine the relationship between intra-articular IL7 and TNFα expression levels in patients with rheumatoid arthritis (RA). In addition, the effect of TNFα blockade on IL7 activity and on IL7 levels was studied. Methods: The effect of IL7 on isolated CD4 T cells and CD14 monocytes/macrophages was studied. IL7 and TNFα levels were measured in the synovial fluid of patients with RA. In RA synovial tissue, IL7 and TNFα expression was assessed in addition to IL1β, numbers of inflammatory cells and adhesion molecule expression. The extent to which TNFα blockade could prevent IL7-induced lymphocyte responses was studied in vitro. In addition, regulation of serum IL7 levels on anti-TNFα therapy (adalimumab) was studied. Results: IL7 induced cell contact-dependent TNFα production by cocultures of T cells and monocytes, but not by T cells and monocytes cultured separately. IL7 and TNFα levels in RA synovial fluid and synovial tissue significantly correlated. IL7-stimulated lymphocyte responses were not inhibited by TNFα blockade. Circulating IL7 levels were significantly reduced in patients who successfully responded to anti-TNFα treatment. However, IL7 levels persisted in non-responders. Conclusion: The present data suggest that IL7 is an important inducer of T cell-dependent TNFα production in RA joints. This may contribute to the correlation of intra-articular IL7 and TNFα in these joints. Furthermore, the persistence of IL7-induced inflammatory activity on TNFα blockade in vitro and persistence of IL7 levels and disease activity in anti-TNFα non-responders suggest that IL7 might additionally promote TNFα-independent inflammation.

The prognostic value of routinely performed minor salivary gland assessments in primary Sjögren's syndrome

Objectives To investigate the prognostic value of the lymphocytic focus score (LFS) and the percentages of IgA+, IgM+ and IgG+ plasma cells for disease severity of primary Sjögren syndrome (pSS). Methods Medical charts of 174 pSS patients were retrospectively analysed, comparing histology results (LFS and percentages of IgA+, IgM+ and IgG+ plasma cells) with disease outcomes as non-Hodgkin lymphoma (NHL) and clinical scores including cumulative EULAR (European League against Rheumatism) Sjögren syndrome disease activity index (ESSDAI) and the total number of extraglandular manifestations. Results The mean LFS was significantly higher in patients developing NHL (3.0±0.894 vs 2.25±1.086; p=0.021). The threshold of ≥3 foci has a positive predictive value of 16% for lymphoma, and a negative predictive value of 98%. Only LFS ≥3 contributed significantly and independently to NHL development in a standard multiple regression model. Ig class distribution of plasma cells did not help to identify patients developing lymphoma. Patients with LFS ≥3, ≤40% IgA+ or ≥25% IgM+ plasma cells in salivary gland biopsy specimens had significantly enhanced systemic disease. Conclusions Routine histopathological minor salivary gland assessment has important prognostic value. The LFS might help to identify patients with an increased risk for lymphoma.