Effectiveness and safety of rituximab in severely relapsed antineutrophil cytoplasmic antibody-associated vasculitis: a retrospective analysis of a Japanese multicentre cohort from the J-CANVAS.

We aimed to clarify the long-term safety and efficacy of rituximab (RTX) as a remission induction therapy following severe relapse in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We retrospectively collected the data of patients with severely relapsed AAV from a Japanese multicentre cohort. The primary exposure was RTX use; the primary outcome was complete remission (CR) proportions at week 24. Baseline characteristics were compared between the RTX and non-RTX groups. We performed multivariate logistic regression analysis and one-to-one propensity score matching analysis as a sensitivity analysis. Totally, 100 patients were enrolled: 52 in the RTX group and 48 in the non-RTX group. Baseline characteristics were comparable between the two groups, except for age, AAV subtype and ANCA serotype. The median age was 71 vs. 75 years, and the PR3-ANCA positivity rate was 44.2% vs. 18.8% in the RTX and non-RTX groups, respectively. No significant difference was observed in CR proportions at week 24 between the two groups (79.2% vs. 68.1%, p = 0.321), with an adjusted odds ratio of 1.27 (95% confidence interval [CI] 0.47-3.51). At week 48, CR proportions were significantly higher in the RTX group (91.7% vs. 64.9%, p = 0.005), with an adjusted odds ratio of 2.95 (95% CI 0.97-9.91). Serious infection rates were lower in the RTX group than in the non-RTX group, with no statistically significant difference. RTX was not superior to conventional immunosuppressive therapies at week 24 but showed significantly favourable results at week 48 for severely relapsed AAV.

Effectiveness of intravenous methylprednisolone pulse in patients with severe microscopic polyangiitis and granulomatosis with polyangiitis.

OBJECTIVES: To evaluate the effectiveness and safety of two different intravenous methylprednisolone (IVMP) pulse doses in patients with severe microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). METHODS: We emulated a target trial using observational data from the nationwide registry in Japan. Patients with severe glomerulonephritis or diffuse alveolar haemorrhage were selected and pseudo-randomized into three groups using propensity score-based overlap weighting as follows: non-IVMP, IVMP 0.5 g/day and IVMP 1.0 g/day. The primary outcome was all-cause mortality, and the secondary outcomes were composite all-cause mortality and kidney failure, severe relapse and serious infection from 2 to 48 weeks after treatment initiation. To estimate the treatment effects, the Cox proportional hazard model and Fine-Gray subdistribution hazard model were used. RESULTS: In this emulated target trial, of 201 eligible patients (MPA, 175; GPA, 26), 6 (3%) died, 4 (2.0%) had kidney failure, 11 (5.5%) had severe relapse, and 40 (19.9%) had severe infections. Hazard ratios (HR) for IVMP 0.5 g/day and IVMP 1.0 g/day pulse groups compared with non-IVMP pulse were as follows: all-cause mortality 0.46 (95% CI: 0.07, 2.81) and 0.07 (95% CI: 0.01, 0.41), respectively; all-cause mortality/kidney failure 1.18 (95% CI: 0.26, 5.31) and 0.59 (95% CI: 0.08, 4.52), respectively; subdistribution HRs for severe relapse were 1.26 (95% CI: 0.12, 13.70) and 3.36 (95% CI: 0.49, 23.29), respectively; and for serious infection 1.88 (95% CI: 0.76, 4.65) and 0.94 (95% CI: 0.28, 3.13), respectively. CONCLUSION: IVMP 1.0 g/day pulse may improve 48-week mortality in patients with severe MPA/GPA.

Clinical Characteristics and Outcomes of Polyarteritis Nodosa: An International Study.

OBJECTIVE: We describe the demographics, clinical features, disease course, and survival of polyarteritis nodosa (PAN) through an international collaboration (GLOBAL-PAN). METHODS: Patients with PAN were recruited between 1990 and 2020 from observational cohorts of nine countries across Europe, Japan, and North America. Eligibility was retrospectively defined using the European Medicines Agency classification algorithm. Patients with PAN related to hepatitis B virus (n = 12) and two monogenic diseases mimicking PAN, deficiency of adenosine deaminase 2 enzyme (n = 16) or familial Mediterranean fever (n = 11), were excluded. Data regarding organ involvement, relapse, disease-related damage, and survival were analyzed. RESULTS: Three hundred fifty-eight patients (female:male ratio 174:184), including those with systemic PAN (sPAN, n = 282) and cutaneous PAN (n = 76), were included. Twenty-five were pediatric onset. Mean ± SD age at diagnosis was 44.3 ± 18.1 years. Constitutional symptoms (71.5%), cutaneous involvement (70.5%), musculoskeletal findings (69.1%), and neurologic features (48.0%) were common manifestations. Among patients with sPAN, gastrointestinal involvement and proteinuria over 400 mg/day were reported in 52.2% and 11.2%, respectively. During a median (interquartile range) 59.6 (99.5) months of follow-up, relapse occurred in 48.5% of patients. One, 5- and 10-year survival rates for sPAN were 97.1%, 94.0%, and 89.0%, respectively. Predictors of death for sPAN included age ≥65 years at diagnosis, serum creatinine at diagnosis >140 µmol/L, gastrointestinal manifestations, and central nervous system (CNS) involvement. CONCLUSION: The spectrum of PAN remains a complex, multifaceted disease. Relapse is common. Age ≥65 years and serum creatinine >140 µmol/L at diagnosis, as well as gastrointestinal and CNS involvement, are independent predictors of death in sPAN.

Critical role of lectin pathway mediated by MBL-associated serine proteases in complement activation for the pathogenesis in systemic lupus erythematosus.

In complement activation system, although the classical pathway has shown to play a critical role for the pathogenesis of SLE, the role of lectin pathway has remained unknown in the pathogenesis of SLE. As Mannose-binding lectin-associated serine proteases (MASPs) are associated with activation of the lectin pathway, we conducted this study to clarify MASPs associations in the pathogenesis of SLE. We evaluated the serum level of MASPs (MASP-1 and MASP-2) in total 68 SLE patients consisting of 15 patients with biopsy-confirmed membranous lupus nephritis (M-LN), 35 patients with biopsy-confirmed proliferative lupus nephritis (P-LN), and 18 SLE patients without LN (non-LN). Our data showed that the serum levels of MASPs were reduced in both P-LN and non-LN although those of M-LN were not reduced. Our data show that the lectin pathway mediated by MASPs plays a critical role for the pathogenesis of SLE except for M-LN.

Polyarteritis nodosa diagnosed in a young male after COVID-19 vaccine: A case report.

In response to the coronavirus disease 2019 pandemic, the coronavirus disease 2019 vaccine was rapidly developed and the effectiveness of the vaccine has been established. However, various adverse effects have been reported, including the development of autoimmune diseases. We report a case of new-onset polyarteritis nodosa in a 32-year-old male following the coronavirus disease 2019 vaccination. The patient developed limb pain, fever, pulmonary embolism, multiple subcutaneous nodules, and haematomas. Skin biopsy revealed necrotising inflammation accompanied by fibrinoid necrosis and high inflammatory cell infiltration in the walls of medium to small arteries. The symptoms resolved following corticosteroid treatment. Although it is difficult to prove a relationship between the vaccine and polyarteritis nodosa, similar cases have been reported and further reports and analyses are therefore necessary.

Seasonal Influence on Development of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A Retrospective Cohort Study Conducted at Multiple Institutions in Japan (J-CANVAS).

OBJECTIVE: To clarify seasonal and other environmental effects on the onset of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS: We enrolled patients with new-onset eosinophilic granulomatosis with polyangiitis (EGPA), microscopic polyangiitis (MPA), and granulomatosis with polyangiitis (GPA) registered in the database of a Japanese multicenter cohort study. We investigated the relationship between environmental factors and clinical characteristics. Seasons were divided into 4 (spring, summer, autumn, and winter), and the seasonal differences in AAV onset were analyzed using Pearson chi-square test, with an expected probability of 25% for each season. RESULTS: A total of 454 patients were enrolled, with a mean age of 70.9 years and a female proportion of 55.5%. Overall, 74, 291, and 89 patients were classified as having EGPA, MPA, and GPA, respectively. Positivity for myeloperoxidase (MPO)-ANCA and proteinase 3 (PR3)-ANCA was observed in 355 and 46 patients, respectively. Overall, the seasonality of AAV onset significantly deviated from the expected 25% for each season (P = 0.001), and its onset was less frequently observed in autumn. In ANCA serotypes, seasonality was significant in patients with MPO-ANCA (P < 0.001), but not in those with PR3-ANCA (P = 0.97). Additionally, rural residency of patients with AAV was associated with PR3-ANCA positivity and biopsy-proven pulmonary vasculitis. CONCLUSION: The onset of AAV was influenced by seasonal variations and was less frequently observed in autumn. In contrast, the occurrence of PR3-ANCA was triggered, not by season, but by rural residency.

Association between hypogammaglobulinaemia and severe infections during induction therapy in ANCA-associated vasculitis: from J-CANVAS study.

OBJECTIVES: To investigate the association between decreased serum IgG levels caused by remission-induction immunosuppressive therapy of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and the development of severe infections. METHODS: We conducted a retrospective cohort study of patients with new-onset or severe relapsing AAV enrolled in the J-CANVAS registry, which was established at 24 referral sites in Japan. The minimum serum IgG levels up to 24 weeks and the incidence of severe infection up to 48 weeks after treatment initiation were evaluated. After multiple imputations for all explanatory variables, we performed the multivariate analysis using a Fine-Gray model to assess the association between low IgG (the minimum IgG levels <500 mg/dl) and severe infections. In addition, the association was expressed as a restricted cubic spline (RCS) and analysed by treatment subgroups. RESULTS: Of 657 included patients (microscopic polyangiitis, 392; granulomatosis with polyangiitis, 139; eosinophilic granulomatosis with polyangiitis, 126), 111 (16.9%) developed severe infections. The minimum serum IgG levels were measured in 510 patients, of whom 77 (15.1%) had low IgG. After multiple imputations, the confounder-adjusted hazard ratio of low IgG for the incidence of severe infections was 1.75 (95% confidence interval: 1.03-3.00). The RCS revealed a U-shaped association between serum IgG levels and the incidence of severe infection with serum IgG 946 mg/dl as the lowest point. Subgroup analysis showed no obvious heterogeneity between treatment regimens. CONCLUSION: Regardless of treatment regimens, low IgG after remission-induction treatment was associated with the development of severe infections up to 48 weeks after treatment initiation.

In lupus cystitis, is the urinary tract dilated or obstructed?

OBJECTIVES: Lupus cystitis is a rare but serious complication of systemic lupus erythematosus (SLE) that can cause permanent bladder dysfunction, leading to irreversible deterioration of kidney function. We report two cases of SLE with lupus cystitis who showed different images from the same cause of disease. METHODS: Patient 1, a 67-year-old woman diagnosed with SLE presented with persistent dysuria for 3 weeks with sudden headache and vomiting. She was hospitalized because of acute kidney injury; the serum creatinine level was 10.68 mg/dL. Computed tomography (CT) showed significant bilateral ureteral stenosis and bilateral hydronephrosis. Patient 2, a 45-year-old woman diagnosed with SLE presented with dysuria requiring self-catheterization. CT showed significant bilateral ureteral dilatation and bilateral hydronephrosis. RESULTS: In patient 1, the right kidney was afunctional. Left nephrostomy was performed on Day 2. Her serum creatinine returned to the normal range. In patient 2, After admission, she changed to an indwelling bladder catheter. Her serum creatinine level improved from 2.04 to 1.31 mg/dL. CONCLUSION: In patients with lupus cystitis, the urinary tract is commonly dilated, but stenosis has been seen in rare case. Physicians should be careful in diagnosing it.

Changes in anti-MDA5 antibody titres and serum cytokine levels before and after diagnosis of anti-MDA5 antibody-positive dermatomyositis.

OBJECTIVES: Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive DM is characterized by rapidly progressive interstitial lung disease and has a poor prognosis. We aimed to investigate whether anti-MDA5 antibody titres and cytokine levels predict clinical course, and evaluate changes in both parameters before and after diagnosis. METHODS: This was a retrospective, single-centre study in 38 patients with anti-MDA5 antibody-positive DM. We compared clinical characteristics and laboratory data at diagnosis between patients in the treatment response (n = 23) and non-response (n = 15) groups, and between those in the relapse (n = 5) and non-relapse (n = 24) groups. We also measured serum anti-MDA5 antibody titres and cytokine levels before and after diagnosis. RESULTS: The non-response group was older, had a higher ground-glass opacity score, lower PaO2/FiO2, higher CRP level, and higher anti-MDA5 antibody titre than the response group. No cytokines significantly differed between groups at diagnosis. The relapse group had a significantly higher anti-MDA5 antibody titre than the non-relapse group. In the survivor group, the anti-MDA5 antibody titre and levels of IFN-α, IFN-γ, monocyte chemotactic protein-1 (MCP-1), IL-6, IL-33, CRP, and ferritin were significantly lower 6 months post-treatment than at diagnosis. Macrophage-associated cytokines such as IL-6, IL-8, IL-18 and MCP-1 increased after anti-MDA5 antibody positivity in three patients who were anti-MDA5 antibody-positive before diagnosis. CONCLUSION: The anti-MDA5 antibody titre at diagnosis may predict the clinical course. Levels of macrophage-associated cytokines significantly declined at 6 months post-treatment, and they may have increased after anti-MDA5 antibody titre positivity.

Hypertrophic pachymeningitis in ANCA-associated vasculitis: a cross-sectional and multi-institutional study in Japan (J-CANVAS).

BACKGROUND: This study investigated the characteristics of hypertrophic pachymeningitis (HP) in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), using information from a multicenter study in Japan. METHODS: We analyzed the clinical information of 663 Asian patients with AAV (total AAV), including 558 patients with newly diagnosed AAV and 105 with relapsed AAV. Clinical findings were compared between patients with and without HP. To elucidate the relevant manifestations for HP development, multivariable logistic regression analyses were additionally performed. RESULTS: Of the patients with AAV (mean age, 70.2 ± 13.5 years), HP was noted in 30 (4.52%), including 20 (3.58%) with newly diagnosed AAV and 10 (9.52%) with relapsed AAV. Granulomatosis with polyangiitis (GPA) was classified in 50% of patients with HP. A higher prevalence of GPA was significantly observed in patients with HP than in those without HP in total AAV and newly diagnosed AAV (p < 0.001). In newly diagnosed AAV, serum proteinase 3 (PR3)-ANCA positivity was significantly higher in patients with HP than in those without HP (p = 0.030). Patients with HP significantly had ear, nose, and throat (ENT) (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.03-2.14, p = 0.033) and mucous membrane/eye manifestations (OR 5.99, 95% CI 2.59-13.86, p < 0.0001) in total AAV. Moreover, they significantly had conductive hearing loss (OR 11.6, 95% CI 4.51-29.57, p < 0.0001) and sudden visual loss (OR 20.9, 95% CI 5.24-85.03, p < 0.0001). CONCLUSION: GPA was predominantly observed in patients with HP. Furthermore, in newly diagnosed AAV, patients with HP showed significantly higher PR3-ANCA positivity than those without HP. The ear and eye manifestations may be implicated in HP development.

Clinical characteristics and social productivity levels of patients with malignant rheumatoid arthritis based on a nationwide clinical database in Japan: annual survey from 2003 to 2013.

OBJECTIVES: Malignant rheumatoid arthritis (MRA) is defined as rheumatoid arthritis (RA) with systemic vasculitis or other severe extra-articular manifestations. Japan has a nationwide database for MRA. We analyzed the characteristics of Japanese patients with MRA based on data from the Ministry of Health, Labour and Welfare (MHLW). METHODS: We were permitted to use data on 43,108 patients who were registered in the MHLW database from 2003 to 2013. RESULTS: Median age was 65 (interquartile range, 57-72) years. Patients consisted of 71% females. Proportions of patients who had or had experienced interstitial pneumonia and pleuritis were increased, episcleritis was stable, and other MRA manifestations were decreased over time. The number of positive symptoms per patient also decreased over time. The median dose of glucocorticoid, percentage of patients undergoing surgery, and use of non-steroidal anti-inflammatory drugs and apheresis decreased year by year. Steinbrocker stage and class improved over time. Median C-reactive protein levels and erythrocyte sedimentation rate also decreased. Regarding social productivity levels of patients with MRA, the proportion of patients who were working or working from home increased and the proportion of patients recuperating or hospitalized decreased. CONCLUSION: In patients with MRA, disease activity decreased and social productivity improved from 2003 to 2013.

Successful treatment of anti-MDA5 antibody-positive refractory interstitial lung disease with plasma exchange therapy.

OBJECTIVES: We examined the effectiveness of plasma exchange (PE) therapy to reduce the mortality of rapidly progressive interstitial lung disease (RP-ILD) in patients positive for anti-melanoma differentiation-associated gene 5 (MDA5) antibodies. METHODS: Among 142 patients newly diagnosed with PM/DM or clinically amyopathic DM from 2008 to 2019 at our hospital, 10 were diagnosed with refractory RP-ILD and were positive for anti-MDA5 antibodies. PE was used as an adjunct to standard therapy and consisted of fresh frozen plasma as replacement solution. The primary outcome was non-disease-specific mortality. RESULTS: Anti-MDA5 antibodies were detected in 28 patients, of whom 21 were diagnosed with RP-ILD and 10 were refractory to intensive immunosuppressive therapy. Six patients received PE (PE group) and four did not (non-PE group). The 1-year survival rate of the PE group was higher than that of the non-PE group (100% and 25%, respectively, P = 0.033). Regarding adverse events associated with PE, two patients had anaphylactic shock, one had high fever due to fresh frozen plasma allergy and one had a catheter infection. All adverse events resolved with appropriate treatment. CONCLUSION: We evaluated the association between 1-year survival rate and PE for refractory RP-ILD in patients positive for anti-MDA5 antibodies. Intensive immunosuppressive therapy improved the survival rate in RP-ILD patients with anti-MDA5 antibodies, but 20-30% of cases were still fatal. PE could be administered to patients with active infectious disease who were immunocompromised by intensive immunosuppressive therapy. PE may be considered in refractory RP-ILD patients positive for anti-MDA5 antibodies.

Elevated cerebrospinal fluid levels of total protein in patients with secondary central nervous system vasculitis and giant cell arteritis.

Objectives: Secondary central nervous system vasculitis (SCNSV) is an extremely rare, refractory, and fatal disease in patients with giant cell arteritis (GCA). We compared the characteristics of GCA patients with and without SCNSV.Methods: This retrospective, single-center, observational cohort study included 35 patients with GCA admitted to Juntendo University Hospital from April 2009 to March 2019. The primary outcome was all-cause mortality.Results: We diagnosed four patients with GCA and SCNSV (SCNSV group) and 31 patients with GCA but no SCNSV (non-SCNSV group). The mortality rate of the SCNSV and non-SCNSV groups was 100% and 10%, respectively (p = .001). The SCNSV group had lower serum levels of C-reactive protein at the time of GCA diagnosis and higher cerebrospinal fluid (CSF) levels of total protein (102 mg/dL vs. 38 mg/dL, p = .008) and albumin (66 mg/dL vs. 21 mg/dL, p = .008) at the time of SCNSV diagnosis.Conclusion: At the time of SCNSV diagnosis, GCA patients had elevated CSF total protein and albumin levels. CSF examination in GCA patients suspected of having SCNSV may be useful for early diagnosis of SCNSV.

The Association between Absence of Abdominal Pain and Mortality in Lower Intestinal Perforation in Patients with Autoimmune Rheumatic Diseases.

OBJECTIVE: To determine mortality and predictive factors for lower intestinal perforation (LIP) among patients with autoimmune rheumatic diseases. METHODS: This retrospective, single-center, observational study analyzed mortality rates in 31 autoimmune rheumatic disease patients with LIP who were admitted to our hospital from January 2002 to June 2017. The primary outcome was the mortality rate during hospitalization. RESULTS: The median age at the time of LIP was 61 years, and the survival rate at discharge was 64.5%. Eleven patients died of sepsis during hospitalization. Cox univariable analysis for mortality during hospitalization showed that absence of abdominal pain (hazard ratio (HR) 5.61, 95% confidence interval (CI) 1.38-22.9), higher age (HR 1.06, 95% CI 1.01-1.11), chronic kidney disease (HR 6.89, 95% CI 1.85-25.7), systemic vasculitis (HR 3.95, 95% CI 1.14-13.6), higher blood urea nitrogen (HR 1.02, 95% CI 1.01-1.04), higher serum creatinine (HR 1.41, 95% CI 1.06-1.87), and LIP due to malignancy (HR 14.3, 95% CI 1.95-105.1) significantly increased mortality. CONCLUSION: Abdominal pain was absent in 16% of LIP patients with autoimmune rheumatic diseases, and this absence was a poor prognostic factor in this cohort. Moreover, higher age, chronic kidney disease, systemic vasculitis, and LIP due to malignancy were associated with significantly increased mortality. Physicians should be aware of LIP in autoimmune disease patients with higher age, chronic kidney diseases, or systemic vasculitis even if patients reveal mild abdominal symptoms.

Clinical characteristics and change in the antibody titres of patients with anti-MDA5 antibody-positive inflammatory myositis.

Objective: The aim of this study was to evaluate the clinical characteristics of patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive inflammatory myositis, and the change in anti-MDA5 antibody titres before and after onset. Method: For 105 PM/DM patients, newly diagnosed in our hospital within the period 2008-2016, serum anti-MDA5 antibody levels were measured at diagnosis and after treatment by ELISA using the MESACUP anti-MDA5 test. The relationships between anti-MDA5 antibody levels and clinical manifestations, laboratory data, and mortality were examined. Result: Compared with patients who were anti-MDA5 antibody negative, those who were antibody positive demonstrated more frequent dermatitis, clinically amyopathic DM, interstitial lung disease and rapid-progressive interstitial lung disease, as well as significantly higher serum ferritin, significantly lower creatine kinase and aldolase, and significantly less frequent ANA (⩾1:160) and anti-cytoplasmic pattern of ANA staining positivity. Anti-MDA5 antibody titres were examined before disease onset in two patients; one showed antibody positivity with low titres 2 years earlier, while both exhibited increased titres at onset. Anti-MDA5 antibody titres declined significantly less in survivors than in non-survivors after treatment; however, there was no significant difference between the two groups when the rate was compared at 2 months after treatment. Conclusion: An initial decrease in anti-MDA5 antibody titre after commencement of treatment was observed in most of the patients, including in fatal cases, suggesting that this may not necessarily be a useful marker for treatment of patients with DM.

Prevalence of hepatitis B virus infection in patients with rheumatic diseases in Tohoku area: a retrospective multicenter survey.

Hepatitis B virus (HBV) reactivation has been increasingly recognized in patients receiving chemotherapy and immunosuppressive therapy; however, the prevalence of HBV infection and rate of HBV screening in patients with rheumatic diseases remains unclear. In this study, we aimed to assess the prevalence of HBV infection and fulminant HBV hepatitis in patients with rheumatic diseases. We also investigated the rate of HBV screening before immunosuppressive therapy in patients with rheumatic diseases. A retrospective questionnaire survey was conducted in the North-east area (Tohoku) of Japan. Questionnaires, comprising 6 questions, were sent to 318 rheumatologists in May 2010, and responses were gathered until June 2011. In total, 71 rheumatologists (22.3%) responded to the survey. We enrolled 7,650 patients with rheumatoid arthritis (RA) and 1,031 patients with systemic lupus erythematosus (SLE). When limited to institutes at which almost all (≥ 90%) patients were tested for HBV serology, 1.1% (40/3,580) patients with RA and 0.3% (3/1,128) patients with SLE were positive for hepatitis B surface antigen (HBsAg), and 25.2% (177/703) patients with RA and 13.7% (34/248) patients with SLE were positive for hepatitis B core antibody (HBcAb). About one-third of rheumatologists did not check HBsAg and more than half did not check hepatitis B surface antibody (HBsAb) or HBcAb at all before therapy. Fulminant HBV hepatitis was observed in 1 RA patient who was current HBV carrier. In conclusion, the prevalence of HBV infection is high in patients with RA and SLE. HBV screening before immunosuppressive therapy should be strictly performed.

TIM-4 has dual function in the induction and effector phases of murine arthritis.

T cell Ig and mucin domain (TIM)-4 is involved in immune regulation. However, the pathological function of TIM-4 has not been understood and remains to be clarified in various disease models. In this study, DBA/1 mice were treated with anti-TIM-4 mAb during the induction or effector phase of collagen-induced arthritis (CIA). Anti-TIM-4 treatment in the induction phase exacerbated the development of CIA. In vitro experiments suggest that CD4 T cells bind to TIM-4 on APCs, which induces inhibitory effect to CD4 T cells. In contrast, therapeutic treatment with anti-TIM-4 mAb just before or after the onset or even at later stage of CIA significantly suppressed the development and progression by reducing proinflammatory cytokines in the ankle joints without affecting T or B cell responses. Consistently, clinical arthritis scores of collagen Ab-induced arthritis, which is not mediated by T or B cells, were significantly reduced in anti-TIM-4-treated mice with a concomitant decrease of proinflammatory cytokines in the joints. In vitro, macrophages secreted proinflammatory cytokines in response to TIM-4-Ig protein and LPS, which were reduced by the anti-TIM-4 mAb. The anti-TIM-4 mAb also inhibited the differentiation and bone-resorbing activity of osteoclasts. These results indicate that TIM-4 has two distinct functions depending on the stage of arthritis. The therapeutic effect of anti-TIM-4 mAb on arthritis is mediated by the inhibition of proinflammatory cytokine production by inflammatory cells, osteoclast differentiation, and bone resorption, suggesting that TIM-4 might be an appropriate target for the therapeutic treatment of arthritis.