Peptidyl arginine deiminase inhibition suppresses arthritis via decreased protein citrullination in joints and serum with the downregulation of interleukin-6.

Objective: To explore the relevance of citrullinated proteins and anti-citrullinated protein antibodies (ACPA) via protein arginine deiminase (PAD) inhibition in peptide glucose-6-phosphate isomerase-induced arthritis (pGIA).Methods: Cl-amidine, a PAD inhibitor, was injected into pGIA. Clinical scores and histopathological findings of ankle joints were assessed. Serum ACPA titers were analyzed using ELISA. Citrullinated protein expression in joints and sera were examined with immunohistochemistry and Western blot analysis, respectively. Serum levels of IL-6, TNFα, and IL-1ß were measured with cytometric bead array (CBA). Gene expression levels of IL-6 and TNFα in joints, lymph nodes, and spleens were analyzed with quantitative PCR. GPI-specific productions of IFNγ and IL-17 from T cells in lymph nodes were evaluated.Results: Cl-amidine treatment significantly reduced arthritis severity while ACPA titers tended to be lower, but not significantly different compared to the control. Citrullinated proteins in joints and sera from treated mice were clearly decreased. With Cl-amidine treatment, serum IL-6 levels were significantly decreased, and IL-6 and TNFα gene expression were significantly reduced in joints. IL-17 production from GPI-specific T cells tended to be lower in Cl-amidine-treated mice, but not significantly different.Conclusion: Our results suggested that PAD-mediated citrullinated protein was involved in the pathogenesis of arthritis via IL-6.

Evaluation of changes in magnetic resonance images following 24 and 52 weeks of treatment of rheumatoid arthritis with infliximab, tocilizumab, or abatacept.

OBJECTIVES: To compare MRI findings in rheumatoid arthritis (RA) patients treated with biologic disease-modifying anti-rheumatic drugs (DMARDs). METHODS: The study subjects were 43 RA patients treated with biologic DMARDs (13 with infliximab, 15 with tocilizumab, and 15 with abatacept). They were evaluated using Simplified Disease Activity Index (SDAI) and low-field extremity MRI at baseline, and at 24 weeks and 52 weeks of treatment. RESULTS: Synovitis scores were significantly lower by 24 weeks in all groups, compared with baseline (P < 0.05). Significant improvement in bone marrow edema (BME) scores were noted from baseline to 24 weeks in infliximab and abatacept groups (P < 0.05), but from 24 weeks to 52 weeks in tocilizumab group (P < 0.01). No significant change was found in erosion score. The synovitis score at baseline correlated significantly with SDAI at 24 weeks (P < 0.05), and the score at 24 weeks correlated significantly with SDAI at 52 weeks (P < 0.05). CONCLUSIONS: The results suggest that the inflammatory improvement by infliximab and abatacept may express earlier than those by tocilizumab, despite similar improvement in SDAI. MRI-detected synovitis could be a useful predictor of SDAI at 24 weeks of treatment. The MRI remains the best tool to detect and assess the effects of biologic DMARDs in RA.

Association of anti-Ro/SSA antibody with response to biologics in patients with rheumatoid arthritis.

OBJECTIVE: To compare the effectiveness of three different biologics in anti-Ro/SSA antibody-positive and antibody-negative patients with rheumatoid arthritis (RA). METHODS: The study subjects were 110 biologics naïve patients with RA who started treatment with biologics and examined for anti-Ro/SSA antibody between December 2003 and March 2014. For patients treated with intravenous infliximab (IFX), tocilizumab (TCZ), or abatacept (ABT), we compared the clinical characteristics and changes in composite disease activity index, such as DAS28, SDAI, and CDAI, for 12 months in anti-Ro/SSA antibody-positive and antibody-negative patients. RESULTS: We examined 59 patients (nine were positive and 50 were negative for anti-Ro/SSA antibody) treated with IFX, 27 patients (5 positive and 22 negative) treated with TCZ, and 24 patients (13 positive and 11 negative) treated with ABT. For patients treated with IFX, parameters of disease activity did not change significantly from baseline in anti-Ro/SSA antibody-positive patients, whereas they improved in antibody-negative patients. On the other hand, treatment with TCZ and ABT significantly decreased disease activity, relative to baseline, in both anti-Ro/SSA antibody-positive and antibody-negative patients. Anti-Ro/SSA antibody-positive patients treated with IFX showed higher frequency of HACA and seroconversion of ANA, and lower serum TGF-ß levels. CONCLUSIONS: Positivity to anti-Ro/SSA in RA seems to confer resistance to IFX via production of HACA and ANA, and low serum TGF-ß levels, but not to TCZ and ABT.

Effectiveness of abatacept for patients with Sjögren's syndrome associated with rheumatoid arthritis. An open label, multicenter, one-year, prospective study: ROSE (Rheumatoid Arthritis with Orencia Trial toward Sjögren's syndrome Endocrinopathy) trial.

OBJECTIVE: To clarify the efficacy and safety of abatacept for secondary Sjögren's syndrome (SS) associated with rheumatoid arthritis (RA). METHODS: The primary endpoint of this open-labeled, prospective, observational multicenter study for secondary SS with RA was the remission rate of Simplified Disease Activity Index (SDAI) at 52 weeks after initiation of abatacept. The secondary endpoints included Saxon's test and Schirmer's test. Adverse events and adherence rate during the study period were also analyzed. RESULTS: Thirty-six patients (all females) were enrolled in this study. The mean SDAI decreased significantly from 20.6 ± 11.2 (±SD) at baseline to 10.0 ± 10.5 at 52 weeks (p < 0.05). Patients with SDAI remission increased from 0 (0 week) to 12 patients (33.3%) at 52 weeks. Saliva volume assessed by Saxon's test increased significantly from 2136 ± 1809 (0 week) to 2397 ± 1878 (24 weeks) mg/2 min (n = 34, p < 0.05). Saliva volume increased significantly from 2945 ± 2090 (0 week) to 3419 ± 2121 (24 weeks) mg/2 min in 11 patients with Greenspan grade 1 or 2 of labial salivary gland biopsy (p < 0.05), but no change was noted in 18 patients with Greenspan grade 3 or 4. Tear volume by Schirmer's test increased significantly from 4.2 ± 4.8 (0 week) to 6.4 ± 7.8 (24 weeks) mm/5 min (n = 30, p < 0.05). The adherence rate to abatacept was 80.6% (29/36) over the 52-week period. Twelve adverse events occurred in 10 of the 36 patients, and 7 of these events were infections. CONCLUSION: Abatacept seems to be effective for both RA and SS related manifestations.

Clinical features of patients with IgG4-related disease complicated with perivascular lesions.

OBJECTIVE: To define the clinical features of IgG4-related disease (IgG4-RD) complicated with perivascular lesions. METHODS: The clinical features of seven patients with IgG4-RD and perivascular lesions diagnosed at the University of Tsukuba Hospital between October 2008 and October 2013, were analyzed, including clinical background, results of imaging studies, satisfaction of the 2011 comprehensive diagnostic criteria (CDC) for IgG4-RD, laboratory data, distribution of perivascular lesions, involvement of other organs, and response to steroid therapy. RESULTS: We studied six men and one woman with a mean age of 66.9 ± 6.7 years (± SD). Six of seven patients were diagnosed as definite IgG4-RD, while the seventh was considered possible IgG4-RD, based on the CDC for IgG4-RD. Serum IgG4 levels at diagnosis were higher than 135 mg/dl in all seven patients (mean, 933 ± 527). Serum C-reactive protein (CRP) levels were elevated in two only (mean, 1.42 ± 3.56 mg/dl). The perivascular lesions were located in the pulmonary artery (n = 1), thoracic aorta (n = 2), abdominal aorta (n = 6), coronary (n = 1), celiac (n = 1), superior mesenteric (n = 1), renal (n = 2), inferior mesenteric (n = 5), and iliac (n = 3) arteries. In addition to perivascular lesions, six patients showed involvement of other organs. All seven patients were treated with prednisolone (0.6 mg/kg/day), which rapidly improved the perivascular and other organ lesions in six patients (the other one patient have not yet been evaluated due to the short follow-up). CONCLUSION: Perivascular lesions show wide distribution in patients with IgG4-RD. Serum CRP levels are not necessarily elevated in these patients. Steroid therapy is effective in IgG4-RD and results in resolution of lesions.

Efficacy and safety of abatacept for patients with Sjögren's syndrome associated with rheumatoid arthritis: rheumatoid arthritis with orencia trial toward Sjögren's syndrome Endocrinopathy (ROSE) trial-an open-label, one-year, prospective study-Interim analysis of 32 patients for 24 weeks.

Abstract Objective. To assess the efficacy and safety of abatacept for secondary Sjögren's syndrome (SS) associated with rheumatoid arthritis (RA). Methods. The primary endpoint of this 1-year, open-labeled, prospective, observational multicenter study of RA-associated secondary SS was the rate of SDAI remission at 52 weeks after initiation of abatacept therapy. The secondary endpoints included that of Saxson's test and Schirmer's test. Adverse events during the study period were also analyzed. Results. Thirty-two patients (all females) were enrolled in this study. Interim analysis at 24 weeks included assessment of efficacy (n = 31) and safety (n = 32). The mean SDAI decreased from 19.8 ± 11.0 (± SD) at baseline to 9.9 ± 9.9 at 24 weeks (P < 0.05). Patients with clinical remission, as assessed by SDAI, increased from 0 patient (0 week) to 8 patients (25.8%) at 24 weeks. Saliva volume (assessed by Saxson's test) increased slightly from 2232 ± 1908 (0 week) to 2424 ± 2004 (24 weeks) mg/2 min (n = 29). In 11 patients with Greenspan grading 1/2 of labial salivary glands biopsy, saliva volume increased from 2945 ± 2090 (0 week) to 3419 ± 2121 (24 weeks) mg/2 min (P < 0.05). Schirmer's test for tear volume showed increase from 3.6 ± 4.6 (0 week) to 5.5 ± 7.1 (24 weeks) mm/5 min (n = 25; P < 0.05). Five adverse events occurred in five of 32 patients (15.6%), and three of these events were infections. Conclusion. Abatacept seems to be effective for both RA and RA-related secondary SS.

Regulatory roles of tumor necrosis factor alpha-induced proteins (TNFAIPs) 3 and 9 in arthritis.

Tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6) have proved to be important in rheumatoid arthritis (RA) because the outcome of RA has greatly improved with the recent availability of biologics targeting them. It is well accepted that these cytokines are involved in the activation of the nuclear factor-κB (NF-κB) signaling pathway, but our understanding of the dependency of these pro-inflammatory cytokines and the link between them in RA is currently limited. Recently, we and others proved the importance of TNFα-induced protein (TNFAIP), due to the spontaneous development of arthritis in deficient animals that are dependent on IL-6. To date, nine TNFAIPs have been identified, and TNFAIP3 and TNFAIP9 were found to be clearly associated with mouse and human arthritis. In this review, we compare and discuss recent TNFAIP topics, especially focusing on TNFAIP3 and TNFAIP9 in autoimmune arthritis in mice and humans.

Involvement of CD161+ Vδ1+ γδ T cells in systemic sclerosis: association with interstitial pneumonia.

OBJECTIVE: Interstitial pneumonia (IP) is a chronic progressive interstitial lung disease associated with high mortality and poor prognosis. However, the pathogenesis of IP remains to be elucidated. The aim of this study was to clarify the role of CD161(+) Vδ1(+) γδ T cells in SSc patients with IP. METHODS: The proportion of CD161(+) Vδ1(+) γδ T cells in peripheral blood mononuclear cells (PBMCs) and serum sialylated carbohydrate antigen (KL-6) levels were determined. GeneChip analysis was performed with CD161(-) and CD161(+) Vδ1(+) γδ T cells. Cytokine and chemokine expression from CD161(+) Vδ1(+) γδ T cells was measured and used to evaluate the effect of culture supernatant on fibroblast proliferation. RESULTS: The proportion of CD161(+) Vδ1(+) γδ T cells was significantly higher in SSc than healthy controls (HCs) and correlated negatively with serum KL-6 levels in IP-positive SSc patients. The gene and mRNA expression level of chemokine ligand 3 (CCL3) was markedly higher in CD161(+) Vδ1(+) γδ T cells than in CD161(-) Vδ1(+) γδ T cells. CD161(+) Vδ1(+) γδ T cells in IP-positive SSc patients showed higher production of CCL3 and lower production of IFN-γ than in HCs. Culture supernatant derived from IP-negative and IP-positive SSc patients promoted fibroblast proliferation, whereas that from HCs did not. CONCLUSION: The small proportion and the altered cell functions of CD161(+) Vδ1(+) γδ T cells among PBMCs in SSc patients play a role in the pathogenesis of IP. These findings suggest that CD161(+) Vδ1(+) γδ T cells may play a regulatory role in the pathogenesis of IP in SSc patients via IFN-γ production.

Analysis of subclinical synovitis detected by ultrasonography and low-field magnetic resonance imaging in patients with rheumatoid arthritis.

OBJECTIVE: To assess the utilities of ultrasonography (US) and low-field magnetic resonance imaging (compacTscan, cMRI) in the diagnosis of subclinical synovitis of hand joints of patients with rheumatoid arthritis (RA). METHODS: A total of 1,540 joints of 77 RA patients were examined clinically, using US, using cMRI, and the baseline X-ray examination was performed. Clinical synovitis was defined as joint tenderness or swelling. Subclinical synovitis was diagnosed by US and by cMRI. The incidence of bone erosion and joint space narrowing was assessed by X-ray examination performed at approximately 40 weeks of follow-up. RESULTS: Of the hand joints examined, 294 (19.1 %) were diagnosed with clinical synovitis, and 218 joints (14.1 %) were diagnosed with subclinical synovitis. The remaining 1,028 joints (66.8 %) were synovitis-free on clinical examination and imaging. For the diagnosis of subclinical synovitis, cMRI (11.4 %) was significantly more sensitive than power Doppler signals detected by US (US-PD; 6.8 %) (P < 0.01), and the combination of US-PD and cMRI was more useful (14.1 %) than US-PD or cMRI alone (P < 0.05). Follow-up X-ray examination of 600 joints showed a significantly higher incidence of bone erosion in joints with subclinical synovitis than in synovitis-free joints (P < 0.05). CONCLUSION: US-PD and cMRI are useful for detecting subclinical synovitis in patients with RA. Subclinical synovitis of the small joints of the hand can progress to bone destruction.

Clinicopathological features of IgG4-related disease complicated with orbital involvement.

OBJECTIVE: IgG4-related disease (IgG4-RD) is characterized by IgG4-positive plasmacytic infiltration and fibrosis in various organs. Orbital involvement in IgG4-RD includes lacrimal glands, extra-ocular muscles, trigeminal nerve and other parts of the orbit. Immunohistochemical staining is used to diagnose IgG4-RD in patients with orbital inflammation. The purpose of this retrospective study was to clarify the clinicopathological features of IgG4-RD complicated with orbital involvement. METHODS: We examined the clinical features, pathological findings and response to treatment in nine patients with IgG4-RD who underwent orbital tissue biopsy between April 2010 and August 2012 at the University of Tsukuba Hospital. RESULTS: Among the nine patients, eight had dacryoadenitis, one had infraorbital nerve swelling, and another one had IgG4-related orbital inflammation. Involvement of other organs was identified in all patients, including involvement of the salivary glands, lymph nodes, lung, kidney and para-aorta. In all patients, biopsy samples from orbital tissues showed lymphoplasmacytic infiltration and fibrosis, and IgG4-positive/IgG-positive plasmacyte ratio of > 40%. All patients were treated with prednisolone (0.6 mg/kg/day) and responded well in early phase, although relapse was noted in two patients following tapering of prednisolone, evident by swelling of lacrimal glands. CONCLUSION: Patients with IgG4-RD complicated with orbital involvement often present with involvement of other organs. The histopathological findings of orbital tissue match the characteristic features of IgG4-RD. Corticosteroid is effective for orbital and systemic involvement in IgG4-RD.

Murine tumor necrosis factor α-induced adipose-related protein (tumor necrosis factor α-induced protein 9) deficiency leads to arthritis via interleukin-6 overproduction with enhanced NF-κB, STAT-3 signaling, and dysregulated apoptosis of macrophages.

OBJECTIVE: To elucidate the role of tumor necrosis factor α-induced adipose-related protein (TIARP; or tumor necrosis factor α-induced protein 9 [TNFAIP-9]) in the development and pathogenesis of arthritis. METHODS: We generated TIARP-deficient (TIARP(-/-) ) mice and investigated several organs in aged mice. Peritoneal macrophages were collected and cultured with lipopolysaccharide (LPS) and TNFα, and then the production of cytokines and subsequent NF-κB signal transduction were analyzed. We also examined the susceptibility of young TIARP(-/-) mice to collagen-induced arthritis (CIA). Draining lymph nodes and splenocytes were isolated and cultured, and serum levels of anti-type II collagen (anti-CII) antibodies, interleukin-6 (IL-6), and TNFα on day 60 were measured. We further investigated the effects of anti-IL-6 receptor monoclonal antibody (mAb) on the development of arthritis in TIARP(-/-) mice. IL-6/STAT-3 signaling was also analyzed using TIARP(-/-) macrophages. RESULTS: TIARP(-/-) mice developed spontaneous enthesitis and synovitis, had high serum levels of IL-6, had increased CD11b+ cell counts in the spleen, and showed enhanced LPS- and TNFα-induced IL-6 expression in macrophages. Sustained degradation of IκBα with dysregulated apoptosis was also noted in TIARP(-/-) macrophages. CIA was clearly exacerbated in TIARP(-/-) mice, accompanied by marked neutrophil and macrophage infiltration in joints. The levels of anti-CII antibodies in serum were unchanged, whereas autoreactive Th1 cell and Th17 cell responses were higher in TIARP(-/-) mice. Treatment with anti-IL-6 receptor mAb prevented the development of CIA in TIARP(-/-) mice, and TIARP(-/-) macrophages showed increased IL-6-induced STAT-3 phosphorylation. CONCLUSION: These findings suggest that TIARP acts as a negative regulator of arthritis by suppressing IL-6 production, its signaling and TNFα-induced NF-κB signaling, resulting in enhanced apoptosis in macrophages.

Therapeutic efficacy of tocilizumab in patients with rheumatoid arthritis refractory to anti-tumor-necrosis-factor inhibitors: 1 year follow-up with low-field extremity MRI.

OBJECTIVE: Tocilizumab (TCZ) is effective in patients with rheumatoid arthritis (RA) who are refractory to anti-tumor-necrosis-factor (anti-TNF) biologics. The Rheumatoid Arthritis Society Disease Activity Score in 28 Joints (DAS28) is used to evaluate the response to TCZ. However, DAS28 is inappropriate marker because TCZ normalizes C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in the early stage of treatment. The aim of our study was to test the usefulness of magnetic resonance imaging (MRI)-based markers of response to TCZ treatment. METHODS: Nine patients with RA who were refractory to anti-TNF inhibitors (six to infliximab, one to etanercept, one to adalimumab, and one to both) were assessed. MRI images of both hands were obtained by low-field extremity MRI at baseline, 20, and 44 weeks of treatment, in addition to assessment with DAS28-ESR. The effect of TCZ on RA was examined by compact MRI score (cMRIS). RESULTS: All patients showed good or moderate response to TCZ treatment, as evaluated by significant reduction in DAS28-ESR at both 20 and 44 weeks (p < 0.001, each, relative to baseline). In contrast, MRI-based indexes (e.g., cMRIS, synovitis, edema, erosion scores) improved significantly at 44 weeks but not at 20 weeks. CONCLUSION: Differences in response to TCZ therapy were determined based on the method of evaluation, suggesting that MRI-based markers are potentially useful for evaluating RA response to TCZ therapy.

Six-transmembrane epithelial antigen of prostate4 (STEAP4) is a tumor necrosis factor alpha-induced protein that regulates IL-6, IL-8, and cell proliferation in synovium from patients with rheumatoid arthritis.

Human six-transmembrane epithelial antigen of prostate4 (STEAP4), an ortholog of mouse tumor necrosis factor-α-induced adipose-related protein (TIARP), plays a role in tumor necrosis factor (TNF)-dependent arthritis models. However, its role in rheumatoid arthritis (RA) is still obscure. This study explored such a role for STEAP4. The expressions of STEAP4, TNFα, and IL-6 were compared in synovia of RA and osteoarthritis patients. STEAP4 induction was examined in TNFα-stimulated fibroblast-like synoviocytes (FLS) in vitro. FLS (with/without TNFα stimulation) were also analyzed for IL-6 expression after STEAP4 knockdown, using siRNA or transfection with STEAP4-plasmid DNA. IL-8, cell proliferation, and apoptosis were also evaluated in STEAP4-overexpressing FLS. The expression of STEAP4 in joints correlated with TNFα expression, specifically in RA synovium. In the cultured FLS, STEAP4 protein expression was augmented by TNFα activation, and localized in endosomal/lysosomal compartments. STEAP4 downregulation by siRNA enhanced the expression of IL-6 mRNA, while STEAP4 overexpression suppressed IL-6 and IL-8 expression, inhibited cell proliferation, and induced apoptosis via caspase-3. The results indicated that human STEAP4 is regulated by TNFα in synovium, where it controls IL-6 secretion and proliferation of FLS, suggesting that STEAP4 might potentially suppress the pathogenesis of TNFα-induced arthritis such as RA.

Comparative suppressive effects of tyrosine kinase inhibitors imatinib and nilotinib in models of autoimmune arthritis.

Imatinib and nilotinib are inhibitors that selectively target a set of protein tyrosine kinases, including abelson kinase (Abl), together with the chimeric oncoprotein, breakpoint cluster region-abelson kinase (Bcr-Abl), as well as stem cell factor receptor (KIT), platelet-derived growth factor receptor (PDGFR), discoidin domain receptor (DDR), and colony stimulating factor-1 receptor (CSF-1R). The aim of the present study was to investigate whether imatinib or nilotinib was effective against arthritis in the glucose-6-phosphate isomerase (GPI)-induced arthritis mouse model. Imatinib or nilotinib was administered orally to the arthritic mice at different time points. Efficacy was evaluated by visual scoring and by determining the production of anti-GPI antibody. Splenocytes from the arthritic mice were cultured with GPI in the presence of imatinib or nilotinib in vitro, and cytokine levels in the culture supernatants were analyzed. To investigate the effects of imatinib and nilotinib on T-cell proliferation, lymph node cells from the arthritic mice were cultured with GPI in the presence of imatinib or nilotinib in vitro. Interleukin (IL)-17 mRNA expression in the arthritic ankle joints from the onset of arthritis was analyzed by real-time polymerase chain reaction (PCR). The administration of imatinib from day 0 showed suppression of arthritis (P < 0.05), the administration of nilotinib from day 0 resulted in pronounced suppression of arthritis (P < 0.01), and that from day 7 showed significant inhibition of the progression of arthritis (P < 0.05). A reduction in anti-GPI antibodies was correlated with the therapeutic efficacy of imatinib, but not with that of nilotinib. Imatinib dose-dependently inhibited tumor necrosis factor (TNF)-α, IL-6, interferon (IFN)-γ, and IL-17 production by splenocytes in vitro, while nilotinib inhibited only IL-17 and IFN-γ production in a dose-dependent fashion. Imatinib at 3 µM exerted a mild antiproliferative effect on CD4+ T cells (P < 0.05), whereas imatinib at 10 µM and nilotinib at 3 and 10 µM demonstrated a marked antiproliferative effect (P < 0.01). The IL17 gene expression level on day 7 tended to be higher than that on day 14. These findings suggest that imatinib and nilotinib could prevent autoimmune arthritis, essentially via distinct mechanisms, in that imatinib inhibits both inflammatory and T-cell-derived cytokine production, whereas nilotinib suppresses T-cell-derived cytokine production. Imatinib and nilotinib could have therapeutic potential for rheumatoid arthritis (RA) and other inflammatory diseases.

Intractable Hemophagocytic Syndrome Associated with Systemic Lupus Erythematosus Resistant to Corticosteroids and Intravenous Cyclophosphamide That Was Successfully Treated with Cyclosporine A.

Hemophagocytic syndrome (HPS) associated with systemic lupus erythematosus (SLE), dubbed acute lupus hemophagocytic syndrome (ALHS), is an intractable complication of SLE. A 24-year-old man who had been diagnosed with SLE three months previously, presented with fever, rash, hallucination, and pancytopenia accompanied with hyperferritinemia and bone marrow hemophagocytosis. He was diagnosed with ALHS and neuropsychiatric (NP)-SLE. Although 4 courses of methylprednisolone pulse therapy and 1 course of intravenous cyclophosphamide (IVCY) improved his NP-SLE, his ALHS did not respond. However, the addition of cyclosporine A (CsA) led to a rapid remission from ALHS. This suggests the usefulness of CsA in the treatment of intractable, corticosteroid- and IVCY-resistant ALHS.

Identification of novel biomarker as citrullinated inter-alpha-trypsin inhibitor heavy chain 4, specifically increased in sera with experimental and rheumatoid arthritis.

BACKGROUND: Anticitrullinated protein antibodies (ACPA) and citrullinated proteins play key roles in the pathogenesis of rheumatoid arthritis (RA). Many candidate citrullinated antigens have been identified in joints, but citrullinated proteins in sera are mostly uncertain in patients with RA. We explored the expression of citrullinated proteins in joints and sera of experimental arthritis, and we further investigated their specific expression correlated with the disease activity in patients with RA. METHODS: Citrullinated protein expression in tissues was examined by IHC in peptide glucose-6-phosphate isomerase-induced arthritis (pGIA). Serum citrullinated proteins from pGIA were examined by Western blotting, and the sequence was identified by MS. With the same methods, serum citrullinated proteins were analyzed in patients with RA, primary Sjögren's syndrome, systemic lupus erythematosus, and osteoarthritis as well as in healthy subjects, by Western blotting and MS. In patients with RA, the relationship between the expression of the identified protein (inter-alpha-trypsin inhibitor heavy chain 4 [ITIH4]) and clinical features was evaluated, and the levels of citrullinated ITIH4 were compared before and after biological treatment. The antibody response against citrullinated ITIH4 peptide was measured by enzyme-linked immunosorbent assay. RESULTS: Citrullinated proteins were detected specifically in arthritic joints and sera from pGIA relative to controls. In sera, a common band of citrullinated protein at 120 kDa was revealed, and it fluctuated in parallel with arthritis score of pGIA by Western blotting. Interestingly, in 82% of RA patient sera, similar bands of citrullinated protein were specifically detected. These proteins were identified as citrullinated ITIH4, and especially the R438 site was commonly citrullinated between mice and humans. Citrullinated ITIH4 levels were associated with clinical parameters such as C-reactive protein (CRP), rheumatoid factor, and Disease Activity Score in 28 joints as measured by CRP in patients with RA. Its levels were decreased in correlation with the reduction of disease activity score after effective treatment in patients with RA. Moreover, antibody response to citrullinated epitope in ITIH4 was specifically observed in patients with RA. CONCLUSIONS: Our results suggest that serum citrullinated ITIH4 was specifically increased in patients with RA and could be a novel biomarker for assessing disease activity in patients with RA.