Are cleaning activities a source of exposure to crystalline silica in women with rheumatoid arthritis? A case-control study.

INTRODUCTION: Inhalation of crystalline silica (silicon dioxide, SiO2) is associated with a wide range of acute and chronic diseases, including rheumatoid arthritis (RA). The objectives of this work were to identify the main sources of exposure to SiO2 in a series of patients with RA not selected on the basis of their professional activity, compared with a representative sample of the French general population, and to assess the association between silica exposure and disease features. METHODS: The Dust Exposure Life-Course Questionnaire (DELCQ) is a tool that enables retrospective quantification of both occupational and non-occupational lifetime exposure to SiO2. DELCQ-previously validated in a large representative sample of the French general population-was administered to 97 consecutive RA patients, and exposure scores were compared between cases and age, gender and smoking status-matched controls (1:4). The main sources of SiO2 exposure were identified in cases and controls, and source-specific exposure levels were compared. The association between DELCQ scores and disease variables in cases was tested via univariable and multivariable analyses. RESULTS: In women with RA, the main sources of SiO2 exposure were cleaning activities and dusty clothes laundry, with higher exposure levels from these sources versus the general population (p<0.005). Across the whole series of RA patients, high SiO2 exposure was independently associated with mediastinal lymphadenopathy (OR 6.3, 95% CI 1.4 to 27.7). CONCLUSION: Cleaning activities and dusty clothes laundry may be underestimated sources of SiO2 exposure in women with RA.

Crystalline silica exposure in patients with rheumatoid arthritis and systemic sclerosis: a nationwide cross-sectional survey.

OBJECTIVES: Develop and validate a thorough exposure questionnaire to comprehensively explore crystalline silica (SiO2) exposure in the general population (gender-specific, occupational and non-occupational) and in patients with autoimmune diseases (rheumatoid arthritis (RA), systemic sclerosis (SSc)). METHODS: Lifetime exposures to SiO2 in occupational and non-occupational settings were assessed using a thorough exposure questionnaire. The questionnaire was applied to a general population panel (n = 2911) sampled from the French rolling census, and to unselected patients with SSc (n = 100) and RA (n = 97). Global (GES), occupational (OES) and non-occupational (NOES) exposure scores were assessed in SSc and RA patients, and compared with up to four controls from the general population, matched by age group, sex and tobacco consumption. RESULTS: Patients had higher GES than their matched controls (SSc: P = 0.001; RA: P < 0.0001) due to higher OES (P < 0.0001 for SSc and RA). Men had higher GES than women (SSc: P < 0.0001; RA: P = 0.002) due to higher OES (P < 0.0001 for SSc and RA). The NOES did not differ between men and women. In SSc patients: Men had higher GES than controls (P < 0.0001). Men and women with SSc had higher OES than controls (P < 0.0001). In RA patients: GES and OES were higher in both men (P = 0.00521; P < 0.0001) and women (P < 0.0001; P < 0.0001) than in their respective controls. Women had higher NOES than controls (P = 0.045). CONCLUSION: The lifetime SiO2 exposure gap between RA and SSc patients and controls was substantially due to occupational exposure. In both diseases, men had higher exposure scores than women.

MUC5B promoter variant rs35705950 and rheumatoid arthritis associated interstitial lung disease survival and progression.

BACKGROUND: The major risk factor for idiopathic pulmonary fibrosis (IPF), MUC5B rs35705950, was found to be associated with rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Whilst the MUC5B rs35705950 T risk allele has been associated with better survival in IPF, its impact on RA-ILD prognosis remains to be determined. Our objective was to explore the influence of MUC5B rs35705950 on survival and progression in RA-ILD. METHODS: Through an international retrospective observational study, patients with RA-ILD were genotyped for the MUC5B rs35705950 variant and consecutive pulmonary function tests (PFTs) findings were collected. Longitudinal data up to a 10-year follow-up were considered and analyzed using mixed regression models. Proportional hazards and joint proportional hazards models were used to analyze the association of baseline and longitudinal variables with lung transplant-free survival. Significant progression of RA-ILD was defined as at least an absolute or relative 10% decline of forced vital capacity at 2 years from baseline. RESULTS: Out of 321 registered patients, 261 were included in the study: 139 women (53.3%), median age at RA-ILD diagnosis 65 years (interquartile range [IQR] 57 to 71), 151 ever smokers (59.2%). Median follow-up was 3.5 years (IQR 1.3 to 6.6). Mortality rate was 32% (95%CI 19 to 42) at 10 years. The MUC5B rs35705950 variant did not impact lung transplant-free survival (HR for the T risk allele carriers=1.26; 95%CI 0.61 to 2.62; P=0.53). Decline in pulmonary function at 2 years was not influenced by MUC5B rs35705950 (OR=0.95; 95%CI 0.44 to 2.05; P=0.89), irrespective of the HRCT pattern. CONCLUSION: In this study, the MUC5B rs35705950 promoter variant did not influence transplant- free survival or decline in pulmonary function in patients with RA-ILD.

Mitral valve granulomatosis: A paradoxical reaction complicating etanercept treatment in rheumatoid arthritis. A case report.

BACKGROUND: "Sarcoidosis-like" paradoxical reactions to Antitumor necrosis factor α (anti-TNFα) treatment have been reported. The clinical presentations are varied, most of the time, with a relatively typical picture of mediastinopulmonary involvement. More rarely, isolated granulomatous locations from various organs are described, leading to difficulties in diagnosis. CASE PRESENTATION: We report a granulomatous cardiac valve location complicating etanercept treatment in a 26-years-old caucasian male with rheumatoid arthritis. The patient received leflunomide and low-dose corticosteroids, then etanercept was introduced because of persistent disease activity. He had no history of tuberculosis infection or contact, chest CT-scan was normal. At 3 months, he showed complete remission. After 6 months of etanercept treatment, the patient suddenly complained of headache with scotomas of the right visual field and vertigo, without fever. Cerebral MRI revealed 3 recent infarcts. Cardiac ultrasonography revealed a mobile mass on the posterior mitral leaflet. C-reactive protein level was 8mg/L, and all analyses were negative for an infectious agent. Leflunomide and etanercept were discontinued, and antibiotic therapy was started. Mitral valve resection and plasty were performed 2 days later. Histology of the valve revealed large non-caseating epithelioid granulomas with a suppurative-like necrotic center. After ruling out infectious endocarditis, sarcoidosis, rheumatoid valvulitis or lupus-like reaction induced by anti-TNF therapy, the diagnosis of a paradoxical reaction to etanercept was finally retained. Tocilizumab monotherapy was introduced to treat RA flare, no antibiotic preventive treatment was added. After 2 years, the patient was in remission. CONCLUSION: This case raises for the first time the possibility of a paradoxical adverse event with an isolated granulomatous reaction on the heart valve occurring with anti-TNF treatment, namely etanercept.

Involvement of Tumor Necrosis Factor Receptor Type II in FoxP3 Stability and as a Marker of Treg Cells Specifically Expanded by Anti-Tumor Necrosis Factor Treatments in Rheumatoid Arthritis.

OBJECTIVE: To study the involvement of Treg cells expressing tumor necrosis factor receptor type II (TNFRII) in exerting control of inflammation in experimental models and in the response to anti-TNF treatments in patients with rheumatoid arthritis (RA) or spondyloarthritis (SpA). METHODS: The role of TNFRII in Treg cells was explored using a multilevel translational approach. Treg cell stability was evaluated by analyzing the methylation status of the Foxp3 locus using bisulfite sequencing. Two models of inflammation (imiquimod-induced skin inflammation and delayed-type hypersensitivity arthritis [DTHA]) were induced in TNFRII-/- mice, with or without transfer of purified CD4+CD25+ cells from wild-type (WT) mice. In patients with RA and those with SpA, the evolution of the TNFRII+ Treg cell population before and after targeted treatment was monitored. RESULTS: Foxp3 gene methylation in Treg cells was greater in TNFRII-/- mice than in WT mice (50% versus 36.7%). In cultured Treg cells, TNF enhanced the expression, maintenance, and proliferation of Foxp3 through TNFRII signaling. Imiquimod-induced skin inflammation and DTHA were aggravated in TNFRII-/- mice (P < 0.05 for mice with skin inflammation and P < 0.0001 for mice with ankle swelling during DTHA compared to WT mice). Adoptive transfer of WT mouse Treg cells into TNFRII-/- mice prevented aggravation of arthritis. In patients with RA receiving anti-TNF treatments, but not those receiving tocilizumab, the frequency of TNFRII+ Treg cells was increased at 3 months of treatment compared to baseline (mean ± SEM 65.2 ± 3.1% versus 49.1 ± 5.5%; P < 0.01). In contrast, in anti-TNF-treated patients with SpA, the frequency of TNFRII+ Treg cells was not modified. CONCLUSION: TNFRII expression identifies a subset of Treg cells that are characterized by stable expression of Foxp3 via gene hypomethylation, and adoptive transfer of TNFRII-expressing Treg cells ameliorates inflammation in experimental models. Expansion and activation of TNFRII+ Treg cells may be one of the mechanisms by which anti-TNF agents control inflammation in RA, but not in SpA.

Microenvironment tailors nTreg structure and function.

Natural regulatory T cells (nTregs) ensure the control of self-tolerance and are currently used in clinical trials to alleviate autoimmune diseases and graft-versus-host disease after hematopoietic stem cell transfer. Based on CD39/CD26 markers, blood nTreg analysis revealed the presence of five different cell subsets, each representing a distinct stage of maturation. Ex vivo added microenvironmental factors, including IL-2, TGFß, and PGE2, direct the conversion from naive precursor to immature memory and finally from immature to mature memory cells, the latest being a no-return stage. Phenotypic and genetic characteristics of the subsets illustrate the structural parental maturation between subsets, which further correlates with the expression of regulatory factors. Regarding nTreg functional plasticity, both maturation stage and microenvironmental cytokines condition nTreg activities, which include blockade of autoreactive immune cells by cell-cell contact, Th17 and IL-10 Tr1-like activities, or activation of TCR-stimulating dendritic cell tolerization. Importantly, blood nTreg CD39/CD26 profile remained constant over a 2-y period in healthy persons but varied from person to person. Preliminary data on patients with autoimmune diseases or acute myelogenous leukemia illustrate the potential use of the nTreg CD39/CD26 profile as a blood biomarker to monitor chronic inflammatory diseases. Finally, we confirmed that naive conventional CD4 T cells, TCR-stimulated under a tolerogenic conditioned medium, could be ex vivo reprogrammed to FOXP3 lineage Tregs, and further found that these cells were exclusively committed to suppressive function under all microenvironmental contexts.

MUC5B Promoter Variant and Rheumatoid Arthritis with Interstitial Lung Disease.

BACKGROUND: Given the phenotypic similarities between rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) (hereafter, RA-ILD) and idiopathic pulmonary fibrosis, we hypothesized that the strongest risk factor for the development of idiopathic pulmonary fibrosis, the gain-of-function MUC5B promoter variant rs35705950, would also contribute to the risk of ILD among patients with RA. METHODS: Using a discovery population and multiple validation populations, we tested the association of the MUC5B promoter variant rs35705950 in 620 patients with RA-ILD, 614 patients with RA without ILD, and 5448 unaffected controls. RESULTS: Analysis of the discovery population revealed an association of the minor allele of the MUC5B promoter variant with RA-ILD when patients with RA-ILD were compared with unaffected controls (adjusted odds ratio, 3.8; 95% confidence interval [CI], 2.8 to 5.2; P=9.7×10-17). The MUC5B promoter variant was also significantly overrepresented among patients with RA-ILD, as compared with unaffected controls, in an analysis of the multiethnic case series (adjusted odds ratio, 5.5; 95% CI, 4.2 to 7.3; P=4.7×10-35) and in a combined analysis of the discovery population and the multiethnic case series (adjusted odds ratio, 4.7; 95% CI, 3.9 to 5.8; P=1.3×10-49). In addition, the MUC5B promoter variant was associated with an increased risk of ILD among patients with RA (adjusted odds ratio in combined analysis, 3.1; 95% CI, 1.8 to 5.4; P=7.4×10-5), particularly among those with evidence of usual interstitial pneumonia on high-resolution computed tomography (adjusted odds ratio in combined analysis, 6.1; 95% CI, 2.9 to 13.1; P=2.5×10-6). However, no significant association with the MUC5B promoter variant was observed for the diagnosis of RA alone. CONCLUSIONS: We found that the MUC5B promoter variant was associated with RA-ILD and more specifically associated with evidence of usual interstitial pneumonia on imaging. (Funded by Société Française de Rhumatologie and others.).

Tumor Necrosis Factor-Alpha Targeting Can Protect against Arthritis with Low Sensitization to Infection.

Tumor necrosis factor-alpha (TNF-α) blockade is an effective treatment for rheumatoid arthritis (RA) and other inflammatory diseases, but in patients, it is associated with reduced resistance to the infectious agents Mycobacterium tuberculosis and Listeria monocytogenes, among others. Our goal was to model infection and arthritis in mice and to compare etanercept, a currently used anti-TNF-α inhibitor, to an anti-TNF-α vaccine. We developed a murine surrogate of the TNF-α kinoid and produced an anti-murine TNF-α vaccine (TNFKi) composed of keyhole limpet hemocyanin conjugated to TNF-α, which resulted in anti-TNF-α antibody production in mice. We also used etanercept (a soluble receptor of TNF commonly used to treat RA) as a control of TNF neutralization. In a mouse model of collagen-induced arthritis, TNFKi protected against inflammation similar to etanercept. In a mouse model of acute L. monocytogenes infection, all TNFKi-treated mice showed cleared bacterial infection and survived, whereas etanercept-treated mice showed large liver granulomas and quickly died. Moreover, TNFKi mice infected with the virulent H37Rv M. tuberculosis showed resistance to infection, in contrast with etanercept-treated mice or controls. Depending on the TNF-α blockade strategy, treating arthritis with a TNF-α inhibitor could result in a different profile of infection suceptibility. Our TNFKi vaccine allowed for a better remaining host defense than did etanercept.

Time trends in the incidence, prevalence, and severity of rheumatoid arthritis: A systematic literature review.

INTRODUCTION: Rheumatoid arthritis (RA) generates a heavy socioeconomic burden. The ability to predict the frequency and severity of socioeconomic effects due to RA is crucial to the development of public health policies. OBJECTIVE: To conduct a systematic literature review of data on the prevalence, incidence, and severity of RA. METHODS: Medline, EMBASE, the Cochrane Library, and online American College of Rheumatology communications were searched for articles on the prevalence and incidence of RA, as well as on selected severity and activity criteria. Relevant articles were then selected by two investigators. RESULTS: Frequency data are conflicting. No proof exists from cohort studies that the incidence of RA has changed over time. Overall, the prevalence of RA is stable or on the rise. Studies consistently demonstrated a decrease in severity over time, with lower activity, fewer extraarticular manifestations, a diminished need for surgery to treat joint destruction, and less severe radiological changes. The excess mortality, in contrast, despite a trend toward a decrease over time, remains significant. CONCLUSION: The activity and deleterious effects of RA have diminished over time, in conjunction with recent therapeutic advances (new drugs and improved patient selection). However, there seems to be no decrease in the frequency of RA, which continues to induce significant excess mortality.

In Vivo Expansion of Activated Foxp3+ Regulatory T Cells and Establishment of a Type 2 Immune Response upon IL-33 Treatment Protect against Experimental Arthritis.

IL-33 is strongly involved in several inflammatory and autoimmune disorders with both pro- and anti-inflammatory properties. However, its contribution to chronic autoimmune inflammation, such as rheumatoid arthritis, is ill defined and probably requires tight regulation. In this study, we aimed at deciphering the complex role of IL-33 in a model of rheumatoid arthritis, namely, collagen-induced arthritis (CIA). We report that repeated injections of IL-33 during induction (early) and during development (late) of CIA strongly suppressed clinical and histological signs of arthritis. In contrast, a late IL-33 injection had no effect. The cellular mechanism involved in protection was related to an enhanced type 2 immune response, including the expansion of eosinophils, Th2 cells, and type 2 innate lymphoid cells, associated with an increase in type 2 cytokine levels in the serum of IL-33-treated mice. Moreover, our work strongly highlights the interplay between IL-33 and regulatory T cells (Tregs), demonstrated by the dramatic in vivo increase in Treg frequencies after IL-33 treatment of CIA. More importantly, Tregs from IL-33-treated mice displayed enhanced capacities to suppress IFN-γ production by effector T cells, suggesting that IL-33 not only favors Treg proliferation but also enhances their immunosuppressive properties. In concordance with these observations, we found that IL-33 induced the emergence of a CD39(high) Treg population in a ST2L-dependent manner. Our findings reveal a powerful anti-inflammatory mechanism by which IL-33 administration inhibits arthritis development.

Targeting VEGF-A with a vaccine decreases inflammation and joint destruction in experimental arthritis.

OBJECTIVES: Inflammation and angiogenesis are two tightly linked processes in arthritis, and therapeutic targeting of pro-angiogenic factors may contribute to control joint inflammation and synovitis progression. In this work, we explored whether vaccination against vascular endothelial growth factor (VEGF) ameliorates collagen-induced arthritis (CIA). METHODS: Anti-VEGF vaccines were heterocomplexes consisting of the entire VEGF cytokine (or a VEGF-derived peptide) linked to the carrier protein keyhole limpet hemocyanin (KLH). Two kinds of vaccines were separately tested in two independent experiments of CIA. In the first, we tested a kinoid of the murine cytokine VEGF (VEGF-K), obtained by conjugating VEGF-A to KLH. For the second, we selected two VEGF-A-derived peptide sequences to produce heterocomplexes (Vpep1-K and Vpep2-K). DBA/1 mice were immunized with either VEGF-K, Vpep1-K, or Vpep2-K, before CIA induction. Clinical and histological scores of arthritis, anti-VEGF, anti-Vpep Ab titers, and anti-VEGF Abs neutralizing capacity were determined. RESULTS: Both VEGF-K and Vpep1-K significantly ameliorated clinical arthritis scores and reduced synovial inflammation and joint destruction at histology. VEGF-K significantly reduced synovial vascularization. None of the vaccines reduced anti-collagen Ab response in mice. Both VEGF-K and Vpep1-K induced persistently high titers of anti-VEGF Abs capable of inhibiting VEGF-A bioactivity. CONCLUSION: Vaccination against the pro-angiogenic factor VEGF-A leads to the production of anti-VEGF polyclonal Abs and has a significant anti-inflammatory effect in CIA. Restraining Ab response to a single peptide sequence (Vpep1) with a peptide vaccine effectively protects immunized mice from joint inflammation and destruction.

Cachexia and adiposity in rheumatoid arthritis. Relevance for disease management and clinical outcomes.

Altered body composition is a frequent finding in rheumatoid arthritis and is associated with the two major outcomes of the disease: disability and cardiovascular mortality. It is estimated that up to two thirds of patients may be affected by loss of lean mass, the so-called rheumatoid cachexia. Hence, body weight being equal, the relative amount of lean mass is lower and that of body fat is higher in rheumatoid arthritis patients vs. healthy controls. Both disease-related factors and other factors, like drug treatments, physical activity and nutrition contribute to modify body composition in rheumatoid arthritis. The effect of pharmacological treatments, and notably of anti-TNF drugs, on body composition is controversial. Conversely, training programs to stimulate muscle growth can restore lean mass and reduce adiposity. There is good evidence that amelioration of body composition ameliorates function and reduces disability. Currently, there is no evidence that interventions that modify body composition can reduce cardiovascular morbidity and mortality in rheumatoid arthritis.

Therapeutic vaccination with TNF-Kinoid in TNF antagonist-resistant rheumatoid arthritis: a phase II randomized, controlled clinical trial.

OBJECTIVES: Active immunization, or vaccination, with tumor necrosis factor (TNF)-Kinoid (TNF-K) is a novel approach to induce polyclonal anti-TNF antibodies in immune-mediated inflammatory diseases. This study was performed to transfer the proof of concept obtained in mice model of rheumatoid arthritis (RA) into human. We designed a pilot study to demonstrate the feasibility of therapeutic vaccination in RA. METHODS: This was a phase IIa, placebo-controlled, multicenter study in adults with RA who previously experienced secondary failure of TNF antagonists. Patients were immunized intramuscularly with 2 or 3 doses of placebo (n = 10) or 90 (n = 6), 180 (n = 12), or 360 µg TNF-K (n = 12). The primary objective was to identify the best dose and schedule based on anti-TNF antibody titers. Clinical symptoms and safety were assessed during 12 months and solicited reactions for 7 days after each injection. RESULTS: The highest anti-TNF antibody response was detected in patients immunized with 360 µg TNF-K and with 3 injections, although this difference was not significant with all other groups. Similar proportions of patients receiving TNF-K and placebo reported adverse events up to month 12. Serious adverse events were reported by 4 patients treated with TNF-K (13.3%) and 3 treated with placebo (30.0%), all unrelated to treatment. At month 12, DAS28-CRP, tender and swollen joint counts, and HAQ scores decreased significantly more in patients who exhibited anti-TNF antibody response than in patients who did not. CONCLUSIONS: TNF-K therapeutic vaccination induced dose- and schedule-dependent anti-TNF antibodies in RA patients and was well tolerated. Patients who developed anti-TNF antibodies showed a trend toward clinical improvement. Although the most aggressive dose and schedule, i.e. 360 mg dose administered 3 times, did show a strong trend of higher antibody response, further studies are warranted to examine even higher and more frequent doses in order to establish the best conditions for clinical improvement. TRIAL REGISTRATION: ClinicalTrials.gov NCT01040715.

Targeting IL-6 for the treatment of rheumatoid arthritis: Phase II investigational drugs.

INTRODUCTION: IL-6 is a key cytokine in the pathogenesis of rheumatoid arthritis (RA). The clinical efficacy of tocilizumab (TCZ), a humanized anti-IL6-receptor mAb, confirmed the value of IL-6 blockade in this disease. A number of new anti-IL-6 biologics are currently in Phase I - III of clinical development for RA. AREAS COVERED: This article reviews the available results from Phase II trials of investigational anti-IL-6 agents in RA. The authors discuss the potential relevance of alternative IL-6-blocking agents, with regard to their specific molecular targets in IL-6 signaling pathways and to the main open questions in the clinical research agenda for anti-IL-6 biologics. EXPERT OPINION: The results of Phase II trials of new anti-IL-6 biologics show promising results in terms of efficacy. The most frequently reported adverse events were not unexpected based on previous experience with TCZ. Further evidence is needed to appraise whether the difference in molecular structure or in the specific target of new anti-IL-6 biologics might result in added therapeutic value over TCZ. New data from Phase III trials that provides a head-to-head comparison against TCZ and anti-TNF agents with or without methotrexate background treatment are expected in the future.

TLR9 independent interferon α production by neutrophils on NETosis in response to circulating chromatin, a key lupus autoantigen.

OBJECTIVES: Interferon (IFN) α is a key immunoregulatory cytokine secreted by activated plasmacytoid dendritic cells (PDC) that constitute less than 1% of leucocytes. IFNα plays an important role in the pathogenesis of systemic lupus erythematosus (SLE). Nevertheless, the natural IFNα inducers in SLE as well as the different IFNα secreting cell types are only partially characterised. METHODS: Chromatin was purified from calf thymus. Human peripheral blood mononuclear cells (PBMC), neutrophils and mouse bone marrow neutrophils were purified and cultured with different stimuli. IFNα production was estimated by flow cytometry, ELISA and a bioassay, and gene expression by quantitative real time PCR. Neutrophil activation and NETosis were analysed by flow cytometry, ELISA and confocal microscopy. RESULTS: Neutrophils produced a bioactive IFNα on stimulation with purified chromatin. IFNα secretion was observed with steady state neutrophils purified from 56 independent healthy individuals and autoimmune patients in response to free chromatin and not chromatin containing immune complexes. Chromatin induced IFNα secretion occurred independently of Toll-like receptor 9 (TLR9). Neutrophil priming by granulocyte-colony stimulating factor, granulocyte macrophage-colony stimulating factor or IFNα was not necessary but PBMC sustained IFNα secretion by neutrophils. PDC were 27 times more efficient than neutrophils but blood neutrophils were 100 times more frequent than PDC. Finally, neutrophil activation by chromatin was associated with NETosis and DNA sensor upregulation. CONCLUSIONS: Neutrophils have the capability of producing IFNα on selective triggering, and we identified a natural lupus stimulus involved, unveiling a new mechanism involved in SLE. Neutrophils represent another important source of IFNα and important targets for future therapies aimed at influencing IFNα levels.

The mouse dendritic cell marker CD11c is down-regulated upon cell activation through Toll-like receptor triggering.

Dendritic cells (DC) play a key role in regulating immune responses and are the best professional antigen-presenting cells. Two major DC populations are defined in part according to cell surface CD11c expression levels. Unexpectedly, we observed that mouse DC strongly down-regulate the typical DC marker CD11c upon activation. To better characterize DC responses, we have analyzed CD11c expression on mouse and human myeloid DC after Toll-like receptor (TLR) triggering. Here we show that mouse bone marrow-derived DC (BMDC) as well as spleen DC down-regulate cell surface CD11c upon activation by TLR3/4/9 agonists. In all cases, full DC activation was reached, as determined by cytokine secretion, cell stimulation in mixed leukocyte reactions (MLR), and CD40/CD86/major histocompatibility complex (MHC) up-regulation. Interestingly, membrane CD11c down-regulation correlated with increased cytoplasmic pools of CD11c. In contrast to the up-regulation of CD40 and MHC class II molecules, lipopolysaccharide (LPS)-induced CD11c down-regulation was MyD88-dependent. Polyinosinic-polycytidylic acid (poly I:C), which does not signal through MyD88, also induced cell surface CD11c down-regulation. Notably, CD11c down-regulation was not observed upon activation of human DC, either through TLR-dependent or -independent cell activation. Thus, activated mouse DC may be transiently CD11c-negative in vivo, hampering the identification of those cells. On the other hand, cell surface CD11c down-regulation may serve as a new activation marker for mouse DC.

Rheumatoid arthritis: from autoimmunity to synovitis and joint destruction.

Rheumatoid arthritis is an autoimmune disease characterized by the production of two known antibodies - rheumatoid factor and anti-citrullinated peptide antibody (ACPA) - against common autoantigens that are widely expressed within and outside the joints. The interactions between genes and environment are crucial in all stages of the disease, involving namely genes from major histocompatibility complex locus, and antigens such as tobacco or microbes (e.g. Porphyromonas gingivalis). T and B cells are activated as soon as the earliest phases of the disease, rheumatoid arthritis appearing as a Th1 and Th17 disease. Inflammatory cytokines have a considerable importance in the hierarchy of the processes involved in RA. The joint destruction seen in RA is caused not only by cytokine imbalances, but also by specific effects of the Wnt system and osteoprotegerin on osteoclasts and by matrix production dysregulation responsible for cartilage damage. Both innate and adaptative immunity demonstrated their respective cornerstone position in rheumatoid arthritis, since targeted treatments has been efficiently developed against TNF-α, IL-6 receptor, IL-1ß, CD20 B cells and T-cell/Dendritic cell interactions.

Modulation of anti-tumor necrosis factor alpha (TNF-α) antibody secretion in mice immunized with TNF-α kinoid.

Tumor necrosis factor alpha (TNF-α) blockade is an effective treatment for patients with TNF-α-dependent chronic inflammatory diseases, such as rheumatoid arthritis, Crohn's disease, and psoriasis. TNF-α kinoid, a heterocomplex of human TNF-α and keyhole limpet hemocyanin (KLH) (TNF-K), is an active immunotherapy targeting TNF-α. Since the TNF-K approach is an active immunization, and patients receiving this therapy also receive immunosuppressant treatment, we evaluated the effect of some immunosuppressive drugs on the generation of anti-TNF-α antibodies produced during TNF-K treatment. BALB/c mice were injected intramuscularly with TNF-K in ISA 51 adjuvant. Mice were also injected intraperitoneally with one of the following: phosphate-buffered saline, cyclophosphamide, methylprednisolone, or methotrexate. Anti-TNF-α and anti-KLH antibody levels were assessed by enzyme-linked immunosorbent assay and the anti-TNF-α neutralizing capacity of sera by L929 bioassay. Our results showed that current treatments used in rheumatoid arthritis, such as methylprednisolone and methotrexate, do not significantly alter anti-TNF-α antibody production after TNF-K immunization. In contrast, the administration of cyclophosphamide (200 mg/kg) after immunization significantly reduced anti-TNF-α antibody titers and their neutralizing capacity.