Rie Suematsu

Interferon regulatory factor 5 is critical for the development of lupus in MRL/lpr mice

OBJECTIVE Interferon regulatory factor 5 (IRF-5) is a transcription factor that mediates intracellular signals activated by engagement of Toll-like receptors (TLRs). IRF5 polymorphisms are associated with an increased or decreased risk of systemic lupus erythematosus (SLE) in various human populations, but the precise role of IRF5 in SLE development is not fully understood. This study was undertaken to examine the role of IRF5 in the development of murine lupus. METHODS We crossed gene-targeted IRF5-deficient (IRF5(-/-) ) mice with MRL/MpJ-lpr/lpr (MRL/lpr) mice and examined the progeny for survival, glomerulonephritis, autoantibody levels, immune system cell populations, and dendritic cell function. RESULTS IRF5(-/-) MRL/lpr mice survived longer than control IRF5(+/+) MRL/lpr mice and displayed only very mild glomerulonephritis. Autoantibodies to SLE-related nuclear antigens were lower in IRF5(-/-) MRL/lpr mouse serum, and numbers of activated CD4+ T cells were reduced in the spleen. Splenic DCs from IRF5(-/-) MRL/lpr mice produced lower levels of inflammatory cytokines when treated in vitro with TLR-7 or TLR-9 ligands or immune complexes. Interferon-α production in response to CpG was also decreased. CONCLUSION Our results show that IRF5 is a crucial driver of lupus development in mice, and indicate that IRF5 may be an attractive new target for therapeutic intervention to control disease in SLE patients.

Therapeutic response of patients with adult Still’s disease to biologic agents: multicenter results in Japan

ObjectiveThe efficacy of biologics in treating adult Still’s disease (ASD) is suggested, but the information is still lacking and the validation is insufficient. To determine the efficacy of several biologic agents in refractory ASD in Japan, a multicenter survey was performed.MethodClinical data on 16 ASD patients who had been treated with at least 1 of the biological agents (total 24 occasions) were collected retrospectively.ResultsInfliximab was used in 9 cases, etanercept in 4, and tocilizumab in 11. Half of the patients that had been treated initially with infliximab or etanercept were changed to another biologics. Tocilizumab was effective in cases switched from another 2 drugs. Tocilizumab showed efficacy in treating both systemic and arthritic symptoms and showed apparent steroid-sparing effect and the highest continuation rate.ConclusionTocilizumab may be a promising biologic agent in refractory ASD.

Toll-like receptor homolog RP105 modulates the antigen-presenting cell function and regulates the development of collagen-induced arthritis.

IntroductionRP105 is a Toll-like receptor homolog expressed on B cells, dendritic cells (DCs), and macrophages. We investigated the role of RP105 in the development of collagen-induced arthritis (CIA).MethodsCIA was induced in RP105-deficient DBA/1 mice and the incidence and arthritis index were analyzed. The cytokine production by spleen cells was determined. The functions of the DCs and regulatory T cells (Tregs) from RP105-deficient or control mice were determined by adding these cells to the lymph node cell culture. Arthritis was also induced by incomplete Freunds adjuvant (IFA) plus collagen or by injecting anti-collagen antibody and lipopolysaccharide.ResultsRP105-deficient mice showed accelerated onset of arthritis and increased severity. Interferon-gamma (IFN-γ) and tumor necrosis factor-alpha production by spleen cells from RP105-deficient mice was increased in comparison with that from wild-type mice. The DCs from RP105-deficient mice induced more IFN-γ production, whereas Tregs from those mice showed less inhibitory effect against IFN-γ production. RP105-deficient mice also showed more severe arthritis induced by collagen with IFA.ConclusionsThese results indicate that RP105 regulates the antigen-presenting cell function and Treg development, which induced the attenuation of the cell-mediated immune responses and, as a result, suppressed the development of CIA.

Autoantibody-producing RP105− B cells, from patients with systemic lupus erythematosus, showed more preferential expression of BCMA compared with BAFF-R than normal subjects

OBJECTIVE B cells lacking RP105 produce autoantibodies in patients with SLE. Expression of B-cell activating factor (BAFF) binding receptors (BBRs) and survival of RP105(-) B cells from SLE patients were examined. METHODS Detection of difference of gene expression between RP105(-) and RP105(+) B cells was done by DNA microarrays. Surface expression was confirmed by flow cytometry. The contribution of BAFF, a proliferation-inducing ligand (APRIL) and monomers/trimers of sCD40L to survival of RP105(-) and RP105(+) B cells was examined. RESULTS Gene expression of B-cell maturation antigen (BCMA) was different among BBRs in RP105(-) and RP105(+) B cells in SLE. Preferential expression of BCMA on RP105(-) B cells was confirmed compared with RP105(+) B cells by flow cytometry, although BAFF receptor (BAFF-R) expression on RP105(-) B cells was significantly lower. Additionally, relative ratios of BCMA/BAFF-R expression on RP105(-) B cells were increased significantly in SLE patients compared with normal subjects. Stimulation by sCD40L decreased the number of surviving RP105(-) and RP105(+) B cells in vitro. RP105(+) B cells were not rescued from sCD40L-induced cell death by BAFF and/or APRIL. In contrast, either BAFF or APRIL maintained the survival of RP105(-) B cells due to avoidance of cell death. Activated RP105(-) B cells reduced BAFF-R and increased BCMA levels. CONCLUSIONS RP105(-) B cells from SLE patients showed more preferential expression of BCMA compared with BAFF-R than normal subjects, and were possibly regulated by BAFF/APRIL. Our results provide a new insight of BCMA and their ligands in B cells from SLE patients.

Phenotyping of P105-Negative B Cell Subsets in Patients with Systemic Lupus Erythematosus

This study aimed to investigate phenotype of RP105(−) B cell subsets in patients with systemic lupus erythematosus (SLE). Flow cytometry was used for phenotyping RP105-negaive B cell subsets. Based on CD19, RP105, and CD138 expression, RP105(−) B cells consist of at least 5 subsets of late B cells, including CD19(+)RP105(int), CD19(+) RP105(−), CD19(low) RP105(−) CD138(−), CD19(low) RP105(−)CD138(int), and CD19(low) RP105(−) CD138(++) B cells. Especially, CD19(+)RP105(int) and CD19(low) RP105(−)CD138(int) B cells are significantly larger than other RP105(−) B cell subsets in SLE. By comparison of RP105(−) B cell subsets between patients with SLE and normal subjects, these subsets were detectable even in normal subjects, but the percentages of RP105(−) B cell subsets were significantly larger in SLE. The phenotypic analysis of RP105(−) B cell subsets suggests dysregulation of later B cell subsets in SLE and may provide new insights into understanding regulation of B cells in human SLE.

Subsets of RP105-negative plasmablasts in IgG4-related disease

We read with interest the paper by Wallace ZS, plasmablasts as a biomarker for IgG4-related disease (IgG4-RD), independent of serum IgG4 concentrations.1 Evidently, the study showed that patients with active, untreated IgG4-RD have elevations in their circulating plasmablast counts. We strongly approve their results and propose new insights into plasmablast subsets in …

Functional disturbance of the stress-adaptation system in patients with scleroderma

There have been several reports indicating the association between recent stress experiences and the onset or the exacerbation of rheumatic diseases, although few such reports exist in patients with scleroderma (SSc). The present study was performed to elucidate whether there were any functional disturbances in the neuro-endocrine-immune system as a homeostatic system upon stress in SSc patients. Various serum levels of stress-related hormones and cytokines were examined before and after a mental calculation stress test, and a basal questionnaire study of sense of coherence (SOC, which is related to the ability to cope with stress), recent stress experiences, and quality of life (QOL) was performed in 17 SSc patients and in 38 healthy volunteers. Physical QOL state was impaired in patients, but there were no differences in recent stress experiences and SOC scores between patients and controls. Basal serum cortisol levels were similar in patients and controls, but increased levels of proinflammatory cytokine and noradrenalin were seen in SSc patients. Characteristically, contrary to the control group, whose cortisol levels increased significantly following the mental calculation stress test, no significant increase was observed in the patients when post-test cortisol levels were compared to pre-test levels, suggesting a defect in the normal cortisol response upon stress in SSc patients. The present results suggest that there may be impaired function of the neuro-endocrine-immune system upon stress in SSc patients.

Nocardiosis in Adult-Onset Still’s Disease and Vasculitis Syndrome

Four cases of nocardiosis in patients with adult-onset Still disease and vasculitis syndrome are presented. Three patients developed lung abscesses and 1 case developed a brain abscess. All were treated with high-dose corticosteroids, and 3 were given cyclosporine when they developed nocardiosis. All patients were successfully treated with antibiotics; cyclosporine was discontinued in 2 cases. These cases indicate that systemic nocardiosis can develop in patients with various rheumatologic diseases who are treated with corticosteroid and immunosuppressive drugs such as cyclosporine.

Persistent expression of CXCR5 on plasmablasts in IgG4-related disease

We read with interest the papers by Fox and Fox,1 and Wallace et al 2 on IgG4 levels and plasmablasts as a marker for IgG4-related disease (IgG4-RD). We strongly approve their results and have reported plasmablasts lacking RP105 (CD180) in IgG4-RD in your journal.3 Recently, we have found an important and additional result about plasmablasts in IgG4-RD. RP105-negative B cells are assigned as five subsets of activated late B cells (subset 1), early or pre-plasmablasts (subset 2), plasmablasts (subset 3), early plasma cells (subset 4) and plasma cells (subset 5).4 However, precise phenotype of RP105-negative B cells in IgG4-RD was hitherto unknown.5 To clarify the phenotype of RP105-negative B cells, multicolour analysis (more than 200 antigens …

Are the 2016 EULAR/ACR/PRINTO classification criteria for macrophage activation syndrome applicable to patients with adult-onset Still’s disease?

The objectives of this study are to determine whether the 2016 European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organization classification criteria for macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (SJIA) can be used to identify MAS in patients with adult-onset Still’s disease (AOSD). Using laboratory data from 76 AOSD patients with and without MAS, we analyzed the ability of the collective and individual constitutive elements of the 2016 MAS in SJIA criteria and additional laboratory measures to discriminate between AOSD patients with (n = 16) and without (n = 60) MAS. Cutoff values to determine the sensitivity, specificity, and predictive values were calculated from receiver operating characteristic curves, and modified classification criteria for MAS in AOSD were evaluated. The 2016 MAS in SJIA classification criteria had an overall sensitivity of 100%, specificity of 70.0%, positive predictive value of 47.1%, and negative predictive value of 100% to discriminate between AOSD patients with and without MAS based on laboratory data. Among the individual criteria, the sensitivity of triglycerides (46.7%) and the specificity of ferritin (15.0%) for MAS in AOSD were particularly low. The sensitivity and specificity for classifying MAS in AOSD patients were increased to 100 and 93%, respectively, by excluding triglycerides and changing the cutoff values for other criteria in the 2016 MAS in SJIA classification. The 2016 classification criteria for MAS in SJIA had higher sensitivity but lower specificity to identify MAS in AOSD patients compared with SJIA patients.