Porphyromonas gingivalis oral infection exacerbates the development and severity of collagen-induced arthritis

Introduction

Clinical studies suggest a direct influence of periodontal disease (PD) on serum inflammatory markers and disease assessment of patients with established rheumatoid arthritis (RA). However, the influence of PD on arthritis development remains unclear. This investigation was undertaken to determine the contribution of chronic PD to immune activation and development of joint inflammation using the collagen-induced arthritis (CIA) model.

Methods

DBA1/J mice orally infected with Porphyromonas gingivalis were administered with collagen II (CII) emulsified in complete Freund’s adjuvant (CFA) or incomplete Freund’s adjuvant (IFA) to induce arthritis. Arthritis development was assessed by visual scoring of paw swelling, caliper measurement of the paws, mRNA expression, paw micro-computed tomography (micro-CT) analysis, histology, and tartrate resistant acid phosphatase for osteoclast detection (TRAP)-positive immunohistochemistry. Serum and reactivated splenocytes were evaluated for cytokine expression.

Results

Mice induced for PD and/or arthritis developed periodontal disease, shown by decreased alveolar bone and alteration of mRNA expression in gingival tissues and submandibular lymph nodes compared to vehicle. P. gingivalis oral infection increased paw swelling and osteoclast numbers in mice immunized with CFA/CII. Arthritis incidence and severity were increased by P. gingivalis in mice that received IFA/CII immunizations. Increased synovitis, bone erosions, and osteoclast numbers in the paws were observed following IFA/CII immunizations in mice infected with P gingivalis. Furthermore, cytokine analysis showed a trend toward increased serum Th17/Th1 ratios when P. gingivalis infection was present in mice receiving either CFA/CII or IFA/CII immunizations. Significant cytokine increases induced by P. gingivalis oral infection were mostly associated to Th17-related cytokines of reactivated splenic cells, including IL-1β, IL-6, and IL-22 in the CFA/CII group and IL-1β, tumor necrosis factor-α, transforming growth factor-β, IL-6 and IL-23 in the IFA/CII group.

Conclusions

Chronic P. gingivalis oral infection prior to arthritis induction increases the immune system activation favoring Th17 cell responses, and ultimately accelerating arthritis development. These results suggest that chronic oral infection may influence RA development mainly through activation of Th17-related pathways.     

Effect of dexamethasone prodrug on inflamed temporomandibular joints in juvenile rats

IntroductionJuvenile idiopathic arthritis (JIA) often causes inflammation of the temporomandibular joint (TMJ) and has been treated with both systemic and intra-articular steroids, with concerns about effects on growing bones. In this study, we evaluated the impact of a macromolecular prodrug of dexamethasone (P-DEX) with inflammation-targeting potential applied systemically or directly to the TMJ.MethodsJoint inflammation was initiated by injecting two doses of complete Freund’s adjuvant (CFA) at 1-month intervals into the right TMJs of 24 growing Sprague–Dawley male rats (controls on left side). Four additional rats were not manipulated. With the second CFA injection, animals received (1) 5 mg of P-DEX intra-articularly (n = 9), (2) 15 mg of P-DEX into the tail vein (n = 7), or (3) nothing in addition to CFA (n = 8). The rats were killed 28 days later and measured by radiography for ramus height (condylar superior to gonion inferior [CsGoInf]), by micro-computed tomography for condylar width (CW) and bone volume/standardized condylar volume (BV/CV), and by histology for retrodiscal inflammatory cells. Inflammation targeting of systemic P-DEX was confirmed by IVIS infrared dye imaging. Inflammation and bone growth were compared between groups using analysis of variance and Pearson’s correlations.ResultsCFA caused a significant reduction in CsGoInf (p < 0.05), but neither route of P-DEX administration had an effect on CsGoInf or CW at CFA injection sites. BV/CV was significantly reduced in both inflamed and control condyles as a result of either steroid application (p < 0.05). The inflammatory infiltrate was overwhelmingly lymphocytic, comprising 16.4 ± 1.3 % of the field in CFA alone vs. <0.01 % lymphocytes in contralateral controls (p < 0.0001). Both P-DEX TMJ (10.1 ± 1.2 %) and systemic P-DEX (8.9 ± 1.7 %) reduced lymphocytes (p < 0.002). The total area of inflammatory infiltrate was significantly less in the systemic injection group than in the group that received CFA injections alone (2.6 ± 1.5 mm² vs. 8.0 ± 1.3 mm²; p = 0.009), but not in the group that received intra-articular P-DEX (8.8 ± 1.2 mm²).ConclusionsHigh-dose systemic administration of inflammation-targeting P-DEX is more effective than an intra-articular injection in reducing TMJ inflammation, but both routes may affect TMJ bone density.     

Defective CD4<Superscript>+</Superscript>CD25<Superscript>+</Superscript>regulatory T cell functioning in collagen-induced arthritis: an important factor in pathogenesis,counter-regulated by endogenous IFN-γ

Mice with a deficiency in IFN-γ or IFN-γ receptor (IFN-γR) are more susceptible to collagen-induced arthritis (CIA), an experimental autoimmune disease that relies on the use of complete Freund's adjuvant (CFA). Here we report that the heightened susceptibility of IFN-γR knock-out (KO) mice is associated with a functional impairment of CD4⁺CD25⁺ T_reg cells. Treatment of wild-type mice with depleting anti-CD25 antibody after CFA-assisted immunisation with collagen type II (CII) significantly accelerated the onset of arthritis and increased the severity of CIA. This is an indication of a role of T_reg cells in the effector phase of CIA. IFN-γR deficiency did not affect the number of CD4⁺CD25⁺ T cells in the central and peripheral lymphoid tissues. In addition, CD4⁺CD25⁺ T cells isolated from naive IFN-γR KO mice had a normal potential to suppress T cell proliferation in vitro. However, after immunisation with CII in CFA, the suppressive activity of CD4⁺CD25⁺ T cells became significantly more impaired in IFN-γR-deficient mice. Moreover, expression of the mRNA for Foxp3, a highly specific marker for T_reg cells, was lower. We further demonstrated that the effect of endogenous IFN-γ, which accounts for more suppressive activity in wild-type mice, concerns both T_reg cells and accessory cells. Our results demonstrate that the decrease in T_reg cell activity in CIA is counter-regulated by endogenous IFN-γ.     

Enforced Expression of Roquin Protein in T Cells Exacerbates the Incidence and Severity of Experimental Arthritis

To investigate the role of Roquin, a RING-type ubiquitin ligase family member, we used transgenic mice with enforced Roquin expression in T cells, with collagen-induced arthritis (CIA). Wild-type (WT) and Roquin transgenic (Tg) mice were immunized with bovine type II collagen (CII). Arthritis severity was evaluated by clinical score; histopathologic CIA severity; proinflammatory and anti-inflammatory cytokine levels; anti-CII antibody levels; and populations of Th1, Th2, germinal center B cells, and follicular helper T cells in CIA. T cell proliferation in vitro and cytokine levels were determined to assess the response to CII. Roquin Tg mice developed more severe CIA and joint destruction compared with WT mice. Production of TNF-α, IFN-γ, IL-6, and pathogenic anti-collagen CII-specific IgG and IgG2a antibodies was increased in Roquin Tg mice. In addition, in vitro T cell assays showed increased proliferation and proinflammatory cytokine production in response to CII as a result of enforced Roquin expression in T cells. Furthermore, the Th1/Th2 balance was altered by an increased Th1 and decreased Th2 population. These findings suggest that overexpression of Roquin exacerbates the development of CIA and that enforced expression of Roquin in T cells may promote autoimmune diseases such as CIA.     

Peripheral blood CD4+CD25+CD127low regulatory T cells are significantly increased by tocilizumab treatment in patients with rheumatoid arthritis: increase in regulatory T cells correlates with clinical response

IntroductionTocilizumab (TCZ), an anti-interleukin-6 receptor antibody, is clinically effective against rheumatoid arthritis (RA), and several reports have indicated how TCZ influences a number of mechanisms underlying RA pathogenesis. However, it is still unclear whether TCZ affects inflammatory cells in peripheral blood and whether any such changes are associated with clinical response. We evaluated associations between proportions of subsets of peripheral immune cells and clinical response in patients with RA treated with TCZ.MethodsThirty-nine consecutive patients with RA who started to receive TCZ as their first biologic between March 2010 and April 2012 were enrolled. The proportions of several subsets of peripheral cells with their levels of expression of differentiation markers, activation markers and costimulatory molecules were measured sequentially from baseline to week 52 by flow cytometry analysis.ResultsClinical Disease Activity Index (CDAI) remission was achieved in 53.8% of patients at week 52 of TCZ therapy. The proportions of CD4⁺CD25⁺CD127^low regulatory T cells (T_reg) and HLA-DR⁺ activated T_reg cells significantly increased with TCZ therapy (P < 0.001 and P < 0.001, respectively), whereas proportions of CD3⁺CD4⁺CXCR3⁻CCR6⁺CD161⁺ T helper 17 cells did not change over the 52 weeks. The proportions of CD20⁺CD27⁺ memory B cells, HLA-DR⁺CD14⁺ and CD69⁺CD14⁺ activated monocytes, and CD16⁺CD14⁺ monocytes significantly decreased (P < 0.001, P < 0.001, P < 0.001 and P < 0.001, respectively). Among them, only the change in T_reg cells was inversely correlated with the change in CDAI score (ρ = −0.40, P = 0.011). The most dynamic increase in T_reg cells was observed in the CDAI remission group (P < 0.001).ConclusionThis study demonstrates that TCZ affected proportions of circulating immune cells in patients with RA. The proportion of T_reg cells among CD4⁺ cells correlated well with clinical response.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0526-4) contains supplementary material, which is available to authorized users.     

LFA-1基因敲出鼠胶原诱导风湿性关节炎发病率及程度的降低

淋巴细胞功能相关抗原（LFA-1）属于黏附分子家族,在细胞相互作用中发挥重要作用。通过观察LFA-1基因敲除小鼠的胶原诱导关节炎(CIA)发病率、放射线学及组织学变化,探讨LFA-1分子在CIA发病中的作用。实验采用100μg的二型胶原(CII)加弗氏完全佐剂充分混合,在LFA-1基因敲除小鼠及正常对照组小鼠尾根部皮内注射,21天后重复免疫一次,随后进行发病率、放射线学及组织学分析。研究结果显示,CII免疫后,正常对照组小鼠平均发病率为57%,临床可见明显的放射线及组织学的异常变化。而LFA-1基因敲除小鼠无发病,放射线及组织学检查亦无明显异常改变。上述结果提示LFA-1在胶原诱导的关节炎发病中起重要作用。     

Tolerance induction by a poorly arthritogenic collagen II can prevent collagen-induced arthritis

Collagen type II (CII)-induced arthritis (CIA) can be induced in 78% of B10.RIII mice (H2r) by intradermal (id) immunization with CII of bovine origin in complete Freund's adjuvant (CFA), whereas immunization with CII of chick origin induces arthritis in less than 5% of these mice. Nevertheless, tolerization of B10.RIII mice with intravenously injected chick CII renders the animals resistant to induction of CIA by immunization with bovine CII. Such tolerization can be achieved either by intravenous injection of 500 micrograms chick CII 1 week prior to immunization with bovine CII in CFA or by such an intravenous injection of chick CII 2 weeks after immunization with bovine CII in CFA. Postimmunization treatment results in a significant decrease in the concentration of antibody to bovine CII. Preimmunization administration of chick CII causes a marked decrease in the antibody reactive with chick CII without a significant effect on the anti-bovine CII antibody concentration. In DBA/1 mice, a strain in which both bovine CII and chick CII can induce a high incidence of the disease, intravenous injection of bovine CII can also prevent arthritis induced by chick CII, even when given 7 or 14 days after immunization. The fact that chick CII as tolerogen is quite effective in preventing arthritis in B10.RIII mice, while as immunogen it is very ineffective in inducing arthritis in this strain, may be interpreted as evidence for interaction between different epitopes on CII in the pathogenesis of CIA.     

Absence of endogeneous interleukin-10 enhances the evolution of murine type-II collagen-induced arthritis.

Interleukin-10 (IL-10) exerts a wide spectrum of regulatory activities in the immune and inflammatory response. The aim of this study was to investigate the role of endogenous IL-10 in the modulation of the inflammatory response in mice subjected to collagen-induced arthritis. Collagen-induced arthritis (CIA) was induced in mice lacking the gene for IL-10 (IL-10 "knock-out", IL-10KO) and in wild-type control (IL-10WT) mice by an intradermal injection of 100 mul of the emulsion (containing 100 mug of bovine type II collagen) (CII) and complete Freund's adjuvant (CFA) at the base of the tail. On day 21, a second injection of CII in CFA was administered. IL-10 wild type (WT) mice developed an erosive, hind paw arthritis when immunised with CII in CFA. Macroscopic clinical evidence of CIA first appeared as peri-articular erythema and oedema in the hind paws. The incidence of CIA was 100% by day 27 in the CII-challenged IL-10WT. The severity of CIA progressed over a 35-day period, with radiographic evaluation revealing focal resorption of bone. The histopathology of CIA included erosion of the cartilage at the joint margins. IL-10KO mice experienced higher rates of clinical signs and more severe knee and paw injury as compared to IL-10WT. The degree of oxidative and nitrosative damage was significantly higher in IL-10KO mice than in wild-type littermates, as indicated by elevated malondialdehyde levels and formation of nitrotyrosine and poly (ADP-ribose) synthetase (PARS). Plasma levels of the proinflammatory cytokines, tumour necrosis factor, interleukin-1beta and interleukin-6 were also greatly enhanced in comparison to wild-type mice. These data demonstrate that endogenous IL-10 exerts an anti-inflammatory role during chronic inflammation and tissue damage associated with collagen-induced arthritis, possibly by regulating neutrophil recruitment, and the subsequent cytokine and oxidant generation.     

Sarilumab plus methotrexate improves patient-reported outcomes in patients with active rheumatoid arthritis and inadequate responses to methotrexate: results of a phase III trial

BackgroundSarilumab is a human monoclonal antibody directed against the alpha subunit of the interleukin-6 receptor complex. In the MOBILITY phase III randomized controlled trial (RCT), sarilumab + methotrexate (MTX) treatment resulted in clinical improvements at 24 weeks that were maintained at 52 weeks in adults with rheumatoid arthritis (RA), who have inadequate response to MTX (MTX-IR). These analyses indicate the effects of sarilumab + MTX versus placebo on patient-reported outcomes (PROs) in this RCT.MethodsPatients (n = 1197) were randomized to receive placebo, sarilumab 150 or 200 mg subcutaneously + MTX every 2 weeks for 52 weeks; after 16 weeks, patients without ≥20 % improvement from baseline in swollen or tender joint counts on two consecutive assessments were offered open-label treatment. PROs included patient global assessment of disease activity (PtGA), pain, health assessment questionnaire disability index (HAQ-DI), Short Form-36 Health Survey (SF-36), and functional assessment of chronic illness therapy-fatigue (FACIT-F). Changes from baseline at weeks 24 and 52 were analyzed using a mixed model for repeated measures. Post hoc analyses included percentages of patients reporting improvements equal to or greater than minimal clinically important differences (MCID) and normative values in the FACIT-F and SF-36. Pearson correlation between observed PRO scores and clinical measures of disease activity was tested at week 24.ResultsBoth doses of sarilumab + MTX vs placebo + MTX resulted in improvement from baseline by week 24 in PtGA, pain, HAQ-DI, SF-36 and FACIT-F scores (p < 0.0001) that was clinically meaningful, and persisted until week 52. In post hoc analyses, the percentages of patients with improvement equal to or greater than the MCID across all PROs were greater with sarilumab than placebo (p < 0.05), with differences ranging from 11.6 to 26.2 %, as were those reporting equal to or greater than normative scores.ConclusionsIn this RCT in patients with MTX-IR RA, sarilumab + MTX resulted in sustained improvement in PROs that were clinically meaningful, greater than placebo + MTX, and complement the previously reported clinical efficacy and safety of sarilumab.

Trial registration

ClinicalTrials.gov. NCT01061736. February 2, 2010     

Dendritic Cell-Specific Deletion of β-Catenin Results in Fewer Regulatory T-Cells without Exacerbating Autoimmune Collagen-Induced Arthritis

Dendritic cells (DCs) are professional antigen presenting cells that have the dual ability to stimulate immunity and maintain tolerance. However, the signalling pathways mediating tolerogenic DC function in vivo remain largely unknown. The β-catenin pathway has been suggested to promote a regulatory DC phenotype. The aim of this study was to unravel the role of β-catenin signalling to control DC function in the autoimmune collagen-induced arthritis model (CIA). Deletion of β-catenin specifically in DCs was achieved by crossing conditional knockout mice with a CD11c-Cre transgenic mouse line. Bone marrow-derived DCs (BMDCs) were generated and used to study the maturation profile of these cells in response to a TLR2 or TLR4 ligand stimulation. CIA was induced by intra-dermal immunization with 100 μg chicken type II collagen in complete Freund’s adjuvant on days 0 and 21. CIA incidence and severity was monitored macroscopically and by histology. The T cell profile as well as their cytokine production were analysed by flow cytometry. Lack of β-catenin specifically in DCs did not affect the spontaneous, TLR2- or TLR4-induced maturation and activation of BMDCs or their cytokine production. Moreover, no effect on the incidence and severity of CIA was observed in mice lacking β-catenin in CD11c⁺ cells. A decreased frequency of splenic CD3⁺CD8⁺ T cells and of regulatory T cells (Tregs) (CD4⁺CD25^highFoxP3⁺), but no changes in the frequency of splenic Th17 (CCR6⁺CXCR3^-CCR4⁺), Th2 (CCR6^-CXCR3^-CCR4⁺) and Th1 (CCR6^-CXCR3⁺CCR4^-) cells were observed in these mice under CIA condition. Furthermore, the expression of IL-17A, IL-17F, IL-22, IL-4 or IFNγ was also not affected. Our data indicate that ablation of β-catenin expression in DCs did not alter the course and severity of CIA. We conclude that although deletion of β-catenin resulted in a lower frequency of Tregs, this decrease was not sufficient to aggravate the onset and severity of CIA.     

Comparative analysis of collagen type II-specific immune responses during development of collagen-induced arthritis in two B10 mouse strains

Introduction

Immune responses against collagen type II (CII) are crucial for the development of collagen-induced arthritis (CIA). The aim of the present study was to evaluate and compare the CII-directed T cell and antibody specificity at different time points in the course of CIA using two mouse strains on the B10 genetic background - B10.Q, expressing A^q MHC class II molecules, and B10.DR4.Ncf1^*/*, expressing human rheumatoid arthritis-associated MHC II DR4 molecules (DRA*0101/DRB*0401).

Methods

B10.Q and B10.DR4.Ncf1^*/* mice were immunized with CII emulsified in adjuvant and development of CIA was assessed. T cells from draining lymph nodes were restimulated in vitro with CII peptides and interferon-gamma (IFN-γ) levels in culture supernatants were evaluated by ELISA. CII-specific antibody levels in serum samples were measured by ELISA.

Results

At four different CIA time points we analyzed T cell specificity to the immunodominant CII epitope 259-273 (CII259-273) and several posttranslationally modified forms of CII259-273 as well as antibody responses to three B cell immunodominant epitopes on CII (C1, U1, J1). Our data show that CII-specific T and B cell responses increase dramatically after disease onset in both strains and are sustained during the disease course. Concerning anti-CII antibody fine specificity, during all investigated stages of CIA the B10.Q mice responded predominantly to the C1 epitope, whereas the B10.DR4.Ncf1^*/* mice also recognized the U1 epitope. In the established disease phase, T cell reactivity toward the galactosylated CII259-273 peptide was similar between the DR4- and the A^q-expressing strains whereas the response to the non-modified CII peptide was dramatically enhanced in the DR4 mice compared with the B10.Q. In addition, we show that the difference in the transgenic DR4-restricted T cell specificity to CII259-273 is not dependent on the degree of glycosylation of the collagen used for immunization.

Conclusions

The present study provides important evaluation of CII-specific immune responses at different phases during CIA development as well as a comparative analysis between two CIA mouse models. We indicate significant differences in CII T cell and antibody specificities between the two strains and highlight a need for improved humanized B10.DR4 mouse model for rheumatoid arthritis.     

Peripheral blood derived mononuclear cells enhance osteoarthritic human chondrocyte migration

IntroductionA major problem in cartilage repair is the lack of chondrogenic cells migrating from healthy tissue into defects. Cartilage is essentially avascular and therefore its healing is not considered to involve mononuclear cells. Peripheral blood derived mononuclear cells (PBMC) offer a readily available autologous cell source for clinical use and therefore this study was designed to evaluate the effects of PBMCs on chondrocytes and cartilage.MethodsHuman primary chondrocytes and cartilage tissue explants were taken from patients undergoing total knee replacement (n = 17). Peripheral blood samples were obtained from healthy volunteers (n = 12) and mononuclear cells were isolated by density-gradient centrifugation. Cell migration and chemokinetic potential were measured using a scratch assay, xCELLigence and CyQuant assay. PCR array and quantitative PCR was used to evaluate mRNA expression of 87 cell motility and/or chondrogenic genes.ResultsThe chondrocyte migration rate was 2.6 times higher at 3 hour time point (p < 0.0001) and total number of migrating chondrocytes was 9.7 times higher (p < 0.0001) after three day indirect PBMC stimulus and 8.2 times higher (p < 0.0001) after three day direct co-culture with PBMCs. A cartilage explant model confirmed that PBMCs also exert a chemokinetic role on ex vivo tissue. PBMC stimulation was found to significantly upregulate the mRNA levels of 2 chondrogenic genes; collagen type II (COL2A1 600–fold, p < 0.0001) and SRY box 9 (SOX9 30–fold, p < 0.0001) and the mRNA levels of 7 genes central in cell motility and migration were differentially regulated by 24h PBMC stimulation.ConclusionThe results support the concept that PBMC treatment enhances chondrocyte migration without suppressing the chondrogenic phenotype possibly via mechanistic pathways involving MMP9 and IGF1. In the future, peripheral blood mononuclear cells could be used as an autologous point-ofcare treatment to attract native chondrocytes from the diseased tissue to aid in cartilage repair.     

Genetic inhibition of RIPK3 ameliorates functional outcome in controlled cortical impact independent of necroptosis

Traumatic brain injury (TBI) is a leading cause of death and disability with no specific effective therapy, in part because disease driving mechanisms remain to be elucidated. Receptor interacting protein kinases (RIPKs) are serine/threonine kinases that assemble multi-molecular complexes that induce apoptosis, necroptosis, inflammasome and nuclear factor kappa B activation. Prior studies using pharmacological inhibitors implicated necroptosis in the pathogenesis of TBI and stroke, but these studies cannot be used to conclusively demonstrate a role for necroptosis because of the possibility of off target effects. Using a model of cerebral contusion and RIPK3 and mixed lineage kinase like knockout (MLKL^−/−) mice, we found evidence for activation of RIPK3 and MLKL and assembly of a RIPK1-RIPK3-MLKL necrosome complex in pericontusional brain tissue. Phosphorylated forms of RIPK3 and MLKL were detected in endothelium, CD11b + immune cells, and neurons, and RIPK3 was upregulated and activated in three-dimensional human endothelial cell cultures subjected to CCI. RIPK3^−/− and MLKL^−/− mice had reduced blood-brain barrier damage at 24 h (p < 0.05), but no differences in neuronal death (6 h, p = ns in CA1, CA3 and DG), brain edema (24 h, p = ns), or lesion size (4 weeks, p = ns) after CCI. RIPK3^−/−, but not MLKL^−/− mice, were protected against postinjury motor and cognitive deficits at 1–4 weeks (RIPK3^−/− vs WT: p < 0.05 for group in wire grip, Morris water maze hidden platform trials, p < 0.05 for novel object recognition test, p < 0.01 for rotarod test). RIPK3^−/− mice had reduced infiltrating leukocytes (p < 0.05 vs WT in CD11b + cells, microglia and macrophages), HMGB1 release and interleukin-1 beta activation at 24–48 h (p < 0.01) after CCI. Our data indicate that RIPK3 contributes to functional outcome after cerebral contusion by mechanisms involving inflammation but independent of necroptosis.Subject terms: Molecular neuroscience, Brain injuries     

Natural killer T cells promote collagen-induced arthritis in DBA/1 mice

The role of NKT cells in the pathogenesis of collagen-induced arthritis (CIA) remains unclear since most studies have used C57BL/6 (B6) mice, which are less susceptible to CIA than mice with a DBA/1 background. To clarify the immunological functions of NKT cells in CIA, it is necessary to analyze in detail the effects of NKT cell deficiency on CIA development in DBA/1 mice. The incidence and severity of CIA were significantly exacerbated in DBA/1CD1d^+/− mice as compared to DBA/1CD1d^−/− mice. In DBA/1CD1d^+/− mice, antigen-specific responses of B and T cells against CII were remarkably increased and inflammatory cytokine levels were also increased in vivo and in vitro. The number of IL-17-producing NKT cells significantly increased in DBA/1CD1d^+/− mice as the disease progressed. Our results clearly show that NKT cells are involved not only in accelerating the severity and incidence of CIA but also in perpetuating the disease progression.     

A Mouse Model of Adoptive Immunotherapeutic Targeting of Autoimmune Arthritis Using Allo-Tolerogenic Dendritic Cells

Objective

Tolerogenic dendritic cells (tDCs) are immunosuppressive cells with potent tolerogenic ability and are promising immunotherapeutic tools for treating rheumatoid arthritis (RA). However, it is currently unknown whether allogeneic tDCs (allo-tDCs) induce tolerance in RA, and whether the numbers of adoptively transferred allo-tDCs, or the requirement for pulsing with relevant auto-antigens are important.

Methods

tDCs were derived from bone marrow precursors of C57BL/B6 mice, which were induced in vitro by GM-CSF, IL-10 and TGF-β1. Collagen-induced arthritis (CIA) was modeled in D1 mice by immunization with type II collagen (CII) to test the therapeutic ability of allo-tDCs against CIA. Clinical and histopathologic scores, arthritic incidence, cytokine and anti-CII antibody secretion, and CD4⁺Th subsets were analyzed.

Results

tDCs were characterized in vitro by a stable immature phonotype and a potent immunosuppressive ability. Following adoptive transfer of low doses (5×10⁵) of CII-loaded allo-tDCs, a remarkable anti-arthritic activity, improved clinical scores and histological end-points were found. Serological levels of inflammatory cytokines and anti-CII antibodies were also significantly lower in CIA mice treated with CII-pulsed allo-tDCs as compared with allo-tDCs. Moreover, treatment with allo-tDCs altered the proportion of Treg/Th17 cells.

Conclusion

These findings suggested that allo-tDCs, especially following antigen loading, reduced the severity of CIA in a dose-dependent manner. The dampening of CIA was associated with modulated cytokine secretion, Treg/Th17 polarization and inhibition of anti-CII secretion. This study highlights the potential therapeutic utility of allo-tDCs in autoimmune arthritis and should facilitate the future design of allo-tDC immunotherapeutic strategies against RA.     

Subjective and objective levels of physical activity and their association with cardiorespiratory fitness in rheumatoid arthritis patients

IntroductionThe aims of the present study were: (a) to examine the agreement between subjective (assessed via the International Physical Activity Questionnaire; IPAQ) and objective (accelerometry; GT3X) physical activity (PA) levels in patients with rheumatoid arthritis (RA), and (b) to evaluate the associations of RA patients’ subjective and objective PA to their scores on the maximal oxygen uptake test (VO2max).MethodsThe participants wore the GT3X for seven days before completing the IPAQ and VO2max test. The Bland-Altman plot was used to illustrate the agreement between the objective and subjective PA data, and the Wilcoxon test was employed to examine the differences. The association between the PA measurement and VO2max test was examined via the correlations and the magnitude was presented by the Steiger’s Z value.ResultsSixty-eight RA patients (age = 55 ± 13 years, body mass index: 27.8 ± 5.4 kg/m2, median of disease duration = 5 (2–8) yrs) were recruited. Smaller differences between the subjective and objective measures were found when PA was assessed at the moderate level. Wilcoxon tests revealed that patients reported less time spent engaged in sedentary behaviours (Z = −6.80, P < 0.01) and light PA (Z = −6.89, P < 0.01) and more moderate PA (Z = −6.26, P < 0.01) than was objectively indicated. Significant positive correlations were revealed between VO2max with all PA levels derived from accelerometry (light PA rho = .35, P < .01; moderate PA rho = .34, P = .01; moderate and vigorous PA, (MVPA) rho = .33, P = .01), and a negative association to sedentary time (ST) emerged (rho = −.27, P = .04). IPAQ-reported moderate PA and MVPA positively correlated with maxV02 (rho = .25, P = .01, rho = .27, P = .01, respectively). Differences between the magnitude of correlations between the IPAQ-VO2 max and GT3X-VO2 max were only significant for ST (Z = 3.43, P < .01).ConclusionsVia responses to the IPAQ, RA patients reported that they were less sedentary and engaged in more higher intensity PA than what was objectively assessed. Accelerometry data correlated with VO2max at all PA levels. Only subjective moderate and MPVA correlated with VO2max. Findings suggest that self-reported PA and ST should be interpreted with caution in people with RA and complemented with accelerometry when possible.

Trial registration

Trial registration: ClinicalTrials.gov ISRCTN04121489. Registered 5 September 2012.     

Type II collagen antibody response is enriched in the synovial fluid of rheumatoid joints and directed to the same major epitopes as in collagen induced arthritis in primates and mice

Introduction

Antibodies towards type II collagen (CII) are detected in patients with rheumatoid arthritis (RA) and in non-human primates and rodents with collagen induced arthritis (CIA). We have previously shown that antibodies specific for several CII-epitopes are pathogenic using monoclonal antibodies from arthritic mice, although the role of different anti-CII epitopes has not been investigated in detail in other species. We therefore performed an inter-species comparative study of the autoantibody response to CII in patients with RA versus monkeys and mice with CIA.

Methods

Analysis of the full epitope repertoire along the disease course of CIA was performed using a library of CII triple-helical peptides. The antibody responses to the major CII epitopes were analyzed in sera and synovial fluid from RA patients, and in sera from rhesus monkeys (Macaca mulatta), common marmosets (Callithrix jacchus) and mice.

Results

Many CII epitopes including the major C1, U1, and J1 were associated with established CIA and arginine residues played an important role in the anti-CII antibody interactions. The major epitopes were also recognized in RA patients, both in sera and even more pronounced in synovial fluid: 77% of the patients had antibodies to the U1 epitope. The anti-CII immune response was not restricted to the anti-citrulline protein antibodies (ACPA) positive RA group.

Conclusion

CII conformational dependent antibody responses are common in RA and are likely to originate from rheumatoid joints but did not show a correlation with ACPA response. Importantly, the fine specificity of the anti-CII response is similar with CIA in monkeys and rodents where the recognized epitopes are conserved and have a major pathogenic role. Thus, anti-CII antibodies may both contribute to, as well as be the consequence of, local joint inflammation.