Radiographic progression according to the severity of fat metaplasia on baseline sacroiliac joint (SIJ) MRI.

<p>Spinal radiographic progression (scored according to the SASSS) was significantly greater in patients with severe fat metaplasia on baseline SIJ MRI after adjusting for baseline SASSS and TNF inhibitors treatment. P values were calculated using an analysis of covariance model, with the severity of fat metaplasia at baseline as a factor and the baseline SASSS and TNF inhibitors treatment as covariates. The bottom and top of the box were the first and third quartiles, and the band inside the box was the median. The ends of the whiskers represented 1.5 interquartiles.</p

Radiographic Structural Damage Is Worse in the Dominant than the Non-Dominant Hand in Individuals with Early Rheumatoid Arthritis

<div><p>Objective</p><p>The relationship between mechanical stress and radiographic progression in rheumatoid arthritis (RA) is unclear. The assumption is that mechanical stress is greater in the dominant hand. Therefore, the aim of the present study was to compare the presence and progression of erosions and joint space narrowing (JSN) in the dominant and non-dominant hand.</p><p>Methods</p><p>Data from 194 patients recently diagnosed with seropositive RA, and with hand radiographs taken at the time of diagnosis and at 2-year follow-up, were analyzed retrospectively. Radiographs were scored using the van der Heijde-modified Sharp Score (HSS) method. Each joint group within each hand was rated separately by two independent examiners in a double-blinded manner.</p><p>Results</p><p>One hundred and ninety-four patients were enrolled (80% female, 88% positive rheumatoid factor, 92% positive anti-citrullinated protein antibody, and 95.4% right-handed). The baseline, follow-up erosion and JSN HSS were significantly higher in the dominant hand than in the non-dominant hand. The annual rate of radiographic progression was also higher in the dominant hand. The erosive progression in the wrist joints varied significantly according to handedness, but the erosion in the proximal interphalangeal joints and metacarpophalangeal joints was similar in both hands. The radiographic progression was associated with the dominant hand, an abnormal baseline C-reactive protein level, and joint damage at baseline. There was no significant difference in bone mineral density between the right and left hands.</p><p>Conclusion</p><p>Radiological damage was worse and progressed faster in the dominant hand, suggesting that mechanical stress is associated with radiographic joint damage in early and active RA.</p></div

IL-1Ra expressed by MSCs decreased Th17 differentiation.

<p>(A) RT-PCR analysis of human IL-1Ra genes in MSCs, HEK293T and HeLa cells. (B) The densitometric quantification of the mRNA expression of human IL-1Ra. β-actin expression was used as control. (C) MSCs were stimulated with 50 nM PMA or 50 ng/ml IL-1β+TNF-α+IFN-γ for 48 h at 37°C. The expression of IL-1Ra was examined by IFA using a rabbit anti-human IL-1Ra antibody and an anti-rabbit Alexa Fluor594-conjugated secondary antibody. The human nuclei (hNuclei) were stained with DAPI. Original magnification: 100×, scale bar: 200 μm. (D-E) MSCs were co-cultured at 5×10⁴ cells per ml with 5×10⁵ cells CD4+ T cells. Human recombinant IL-1Ra (2, 5, and 10 ng/ml) or human IL-1 receptor type 1 (2, 5, and 10 ng/ml) was added to the wells under Th17-inducing conditions. After 3 days of co-culture, the differentiated Th17 cells were harvested and the proportion of Th17 cells was analyzed by flow cytometry as described above. IL-1Ra inhibited the differentiation of Th17 cells in a dose-dependent manner. Error bars represent the mean ± SEM. *, P<0.05. **, P<0.01.</p

The therapeutic effects of human bone marrow-derived mesenchymal stem cells (MSCs) in IL-1RaKO mice.

<p>IL-1RaKO mice were intraperitoneally injected with 5×10⁶ MSCs at 7 and 14 weeks of age. (A) Hind paw arthritis score. Arthritic paws were scored on a scale of 0–4. The arthritis score decreased in the IL-1RaKO mice that received MSCs. (B) Representative photographs of redness and swelling of the hind paws in IL-1RaKO with or without MSCs. (C) Histological analysis of the ankle joints stained with hematoxylin and eosin (H&E), safranin O (S), and toluidine blue (T) in wild-type (WT) BALB/c mice, IL-1RaKO mice, and IL-1RaKO mice injected with MSCs. H&E-stained sections were examined under 50× and 100× magnification. Safranin O and toluidine blue staining was analyzed at 200× magnification. Scale bar: 200 μm (50×), 100 μm (100×), and 50 μm (200×). (D) Synovial hyperplasia and cellular infiltrate were each scored on a scale of 0–3. Joint inflammation scores were calculated as the sum of these two scores. (E) Cartilage loss estimated in samples stained with safranin O and toluidine blue, and the extent of pannus formation, were each scored on a scale of 0–3. Joint destruction scores were calculated as the sum of these two scores. The mean scores were evaluated by three independent examiners. Results are the mean ± SEM. *, P<0.05; **, P<0.01; ***, P<0.001.</p

Expression of citrullinated peptides in the arthritic joints of mice with collagen-induced arthritis (CIA).

<p>An anti-citrullinated peptide antibody was produced by a hybridoma cell line derived by fusing myeloma cells with B cells from mice immunized with cyclic citrullinated peptide. (A) Immunohistochemical staining to confirm the presence of citrullinated peptides in the joints of normal control (NC) mice, non-infected CIA mice, and Post-infected CIA mice (n = 5 per group). The bottom row shows magnifications of the boxed areas. Scale bars: 200 μm. (B) Citrullinated regions were examined by quantitative image analysis. The fold increase in the size of the citrullinated area was then calculated relative to the same area in NC mice. Data represent the mean of three independent experiments (± standard error of the mean). *** P <0.001.</p

Annual changes in the van der Heijde modified Sharp score between the dominant and non-dominant hand.

<p>JSN, joint space narrowing; MCPs, metacarpal joints; PIPs, proximal interphalangeal joints; SE, Standard error</p><p>Annual changes in the van der Heijde modified Sharp score between the dominant and non-dominant hand.</p

Citrullinated vimentin and fibronectin in synovial tissues of mice with collagen-induced arthritis (CIA) post-infected with <i>P</i>.<i>gingivalis</i>.

<p>(A) Immunohistochemical staining for vimentin, enolase, and fibronectin which are known to be prone to citrullination in the arthritic joints of CIA mice Post-infected with <i>P</i>.<i>gingivalis</i> (n = 3). The number of (B) vimentin-, (C) fibronectin-, and (D) enolase- positive cells was counted. The co-localization of citrulline with (E) vimentin and (F) fibronectin was confirmed. Data represent the mean ± SEM of three independent counts. ***p<0.001.</p

Arthritic role of <i>Porphyromonas gingivalis</i> in collagen-induced arthritis mice

<div><p>Epidemiological studies show an association between rheumatoid arthritis (RA) and periodontal disease. <i>Porphyromonas gingivalis</i> (<i>P</i>.<i>gingivalis</i>) is a well-known pathogen in periodontitis. This study investigated the pathogenic effects of <i>P</i>.<i>gingivalis</i> on autoimmune arthritis <i>in vivo</i>. Collagen-induced arthritis (CIA) mice were intraperitoneally injected with W83 and 2561 strains of <i>P</i>.<i>gingivalis</i>. Infection with <i>P</i>.<i>gingivalis</i> exacerbated arthritis score in CIA mice. Synovial inflammation and bone destruction in CIA mice infected with <i>P</i>.<i>gingivalis</i> were more severe than in uninfected CIA mice. Both W83 and 2561 strains were more pro-arthritic after arthritis symptom was fully activated. Interestingly, only W83 strain was arthritogenic before autoimmune reaction initiated. Citrullination was detected in synovial tissue of CIA mice and CIA mice inoculated with <i>P</i>.<i>gingivalis</i>, but not in normal control mice. The citrullinated area was greater in <i>P</i>.<i>gingivalis</i>-infected CIA mice than in non-infected CIA mice. This study showed that <i>P</i>.<i>gingivalis</i> exacerbated disease in a mouse model of autoimmune arthritis and increased the expression of citrullinated antigens in the synovium. The arthritogenic effects of <i>P</i>.<i>gingivalis</i> were at least in part, dependent upon the bacterial strain with or without fimbriae expression, route and time of infection. <i>P</i>.<i>gingivalis</i>-mediated citrullination may explain the possible link between periodontal disease and RA.</p></div

Histological analysis and osteoclastogenesis of arthritic joints from CIA mice infected with <i>P</i>.<i>gingivalis</i>.

<p>(A) Histological analysis of joints in the hind paws of animals from each group. Tissue sections were stained with hematoxylin and eosin, safranin O, and toluidine blue. Scale bars: 200 μm. (B) Inflammation scores and (C) joint destruction scores were calculated. Histological scores were evaluated by three independent observers in a blinded manner and expressed as the mean ± SEM (*p<0.05, **p<0.01, and ***p<0.001). (D) Osteoclastogenesis in synovial tissues was determined by staining with tartrate-resistant acid phosphatase (TRAP). Scale bar: 200 μm. (E) Area occupied by TRAP-positive osteoclasts. (F) TRAP-positive osteoclasts with multinucleated cells were counted using an automated system for quantitative image analysis. Data represent the mean of three independent counts (± SEM). *P < 0.05.</p

MSCs decrease the splenic Th17/Treg ratio and mRNA levels of pro-inflammatory cytokines in the ankle joint.

<p>(A, B) CD4, CD25, FoxP3, and RORγt expression in the spleen were determined by flow cytometry. The frequency of Th17 cells was reported as the percentage of CD4+ RORγt+ cells out of the total CD4+ T cell population. The frequency of Treg was reported as the percentage of CD4+CD25+FoxP3+ cells out of the total CD4+ T cell population. (C) Total RNA was isolated from the joints, and the expression of human, mouse IL-1Ra and pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α, and IL-17 was investigated. (D-I) The densitometric quantification of the mRNA expression in joints. β-actin expression was used as the endogenous control. Data represent the mean ± SEM. *, P<0.05; **, P<0.01; ***, P<0.001.</p