TRIM21 is one of the autoantigens that reacts with an anti-SS-A antibody (Ab) present in patients with systemic lupus erythematosus (SLE) and Sjögren's syndrome. TRIM21 is thought to play a role in B-cell proliferation and apoptosis, among other activities. Here we examined a pathological role of TRIM21 in SLE. Trim21-deficient MRL/lpr mice were generated by backcrossing Trim21-deficient C57BL/6 mice to MRL/lpr mice. The levels of serum anti-dsDNA Ab and urine protein at 28 weeks of age were significantly higher in Trim21-deficient MRL/lpr mice as compared to wild-type MRL/lpr mice (p = 0.029 and 0.003, respectively). Resting B cells from Trim21-deficient mice showed significantly higher abilities to differentiate into plasmablasts and to produce Ab as compared with control mice. Due to the reduction of TRIM21-mediated ubiquitylation, IRF5 protein expression was increased in Trim21-deficient MRL/lpr mice (p = 0.021), which correlated with increased plasmablast generation and immunoglobulin production. B cells from SLE patients with anti-TRIM21 Ab seropositivity also showed a significantly higher ability to differentiate into plasmablasts as compared with those without anti-TRIM21 Ab or healthy controls. These results suggest that TRIM21 dysfunction contributes to SLE pathogenesis by promoting B-cell differentiation, for which anti-TRIM21 Ab may be partly responsible.

Background TRIM21 is a member of the tripartite motif family proteins and is one of the autoantigens which react with anti-SS-A antibody (Ab) present in sera of patients with systemic lupus erythematosus (SLE) and Sjögren’s syndrome. Previous studies have shown that TRIM21 dysfunction promotes aberrant B-cell differentiation and Ab production in SLE, and anti-TRIM21 Ab may be related to the TRIM21 dysfunction in human SLE pathogenesis. Here, we examined the relationship between anti-TRIM21 Ab and clinical and immunological characteristics in SLE patients. Methods Twenty-seven patients with SLE (23 women and four men) before immunosuppressive therapies, who fulfilled the revised 1997 American College of Rheumatology criteria for SLE, and four healthy controls (3 women and one man) were enrolled in the study. SLE patients were divided into two groups according to the seropositivity for anti-TRIM21 Ab. Serum anti-TRIM21 Ab levels were measured using enzyme-linked immunosorbent assays. The serum levels of cytokines and immunoglobulins were measured by cytometer beads arrays. The expression levels of TRIM21 protein in peripheral mononuclear cells (PBMCs) from SLE patients were evaluated by Western blotting. Results Sixteen and 9 patients showed seronegativity and seropositivity for anti-TRIM21 Ab, respectively. There were no significant differences in the background parameters, including female ratio, age, disease duration, SLE activity, and laboratory data between the two groups. The serum levels of interferon (IFN)-β were significantly higher in patients with anti-TRIM21 Ab as compared with those without anti-TRIM21 Ab ( P = .043). The levels of IgG1 and IgA were significantly higher in SLE patients with anti-TRIM21 Ab as compared with those without anti-TRIM21 Ab ( P = .0022 and .032, respectively). The PBMCs of patients with anti-TRIM21 Ab showed a significantly lower expression of TRIM21 protein as compared with those of patients without anti-TRIM21 Ab ( P = .014). Conclusions Anti-TRIM21 Ab seropositivity was related to B-cell abnormalities and type I IFN overproduction in SLE patients. These findings suggest that anti-TRIM21 Ab may have an inhibitory effect on TRIM21 functions and be a novel biomarker for the level of dependence on type I IFN overproduction and B-cell abnormalities.

Aim:To determine characteristics of rheumatoid arthritis (RA) patients in Japan who received the same biological disease-modifying antirheumatic drugs (bDMARDs) for at least 6 months and to identify factors associated with successful down-titration of bDMARDs dependent on shared decision-making. Methods:We included consecutive RA patients who received the same bDMARD with low disease activity or remission for at least 6 months in our two university hospitals. Patients treated with the bDMARD standard dose were defined as SD, while those treated with bDMARD down-titration were defined as DT. We retrospectively reviewed clinical charts and compared data between the two groups.Results: Of 288 patients with RA, 204 (70.8%) and 84 (29.2%) continued standard dose treatment and underwent down-titration treatment, respectively. Sixty-six of 84 (78.6%) down-titration-treated patients continued to show low disease activity or remission, whereas 18 (21.4%) relapsed 18.9 ± 24.4 months after bDMARD down-titration was started. Univariate predictor analysis showed that the probable factors of down-titration were no history of bDMARD treatment (P = .001) and low initial Disease Activity Assessment of 28 joint score (P = .048). Other clinical characteristics had no significant relationship with successful down-titration.Conclusions: Thus, bDMARD-naïve patients and those with low initial disease activity are more likely to agree to attempt down-titration. However, the timing and method of down-titration should be made in shared decision-making between patients and rheumatologists. K E Y W O R D Santirheumatic agents, arthritis-rheumatoid, decision-making, guideline, therapeutics

Disseminated nontuberculous mycobacterial infection (DNTM) is typically observed in immunocompromised hosts. Recently, it has been reported that healthy individuals with serum neutralizing autoantibodies for interferon (IFN)-γ can also develop DNTM. We herein report a case of anti-IFN-γ antibody-seropositive DNTM caused by Mycobacterium kansasii with symptoms mimicking TAFRO or POEMS syndrome, including anasarca, organomegaly, skin pigmentation, polyneuropathy, osteosclerotic change, thrombocytopenia, serum M protein, high C-reactive protein level, and reticulin fibrosis. The combination of antimicrobial chemotherapy with glucocorticoid and intravenous immunoglobulin improved his symptoms. Glucocorticoids may be an effective method of suppressing the production of anti-IFN-γ antibodies in DNTM.

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Background/Purpose TRIM21 is one of the autoantigens which react with anti-SS-A antibody (Ab). Previous studies have shown that TRIM21 dysfunction promotes aberrant B-cell differentiation in systemic lupus erythematosus (SLE). Here we examined the relationship between anti-TRIM21 Ab and clinical and immunological characteristics in SLE patients. Methods Twenty-seven patients with SLE before immunosuppressive therapies and four healthy controls (HC) were enrolled in the study. Serum anti-TRIM21 Ab levels were measured using enzyme-linked immunosorbent assays. The serum levels of cytokines and immunoglobulins were measured using cytometer beads arrays. The protein expression levels of TRIM21 in peripheral blood mononuclear cells (PBMCs) were evaluated by western blotting. Results Nineteen and 8 patients showed seronegativity and seropositivity for anti-TRIM21 Ab, respectively. There were no significant differences in the background parameters, including SLE activity and laboratory data. The serum levels of interferon (IFN)-α2 were significantly higher in patients with anti-TRIM21 Ab as compared with those without anti-TRIM21 Ab (p = 0.03). The levels of IgG1, IgG2, and IgA were significantly higher in patients with anti-TRIM21 Ab as compared with those without anti-TRIM21 Ab (p = 0.005, 0.04 and 0.01, respectively). The PBMCs of patients with anti-TRIM21 Ab showed a significantly higher expression of TRIM21 protein as compared with those of patients without anti-TRIM21 Ab. Conclusion Anti-TRIM21 Ab seropositivity is related to B-cell abnormalities and type I IFN overproduction in SLE patients, which may be due to the inhibitory effect of anti-TRIM21 Ab on TRIM21 functions.