Katsue Sunahori Watanabe

Transcription factor Ikaros Represses Protein Phosphatase 2A (PP2A) Expression through an Intronic Binding Site

Background: PP2A is a serine/threonine phosphatase playing a central role in the pathology of the autoimmune disease SLE. Results: Ikaros binds to an intronic site in PP2A and modulates its expression. Conclusion: Ikaros represses PP2A expression by recruiting histone deacetylase HDAC1. Significance: This study proposes a novel pathway for regulation of PP2A, a critical molecule in SLE pathogenesis. Protein phosphatase 2A (PP2A) is a highly conserved and ubiquitous serine/threonine phosphatase. We have shown previously that PP2A expression is increased in T cells of systemic lupus erythematosus patients and that this increased expression and activity of PP2A plays a central role in the molecular pathogenesis of systemic lupus erythematosus. Although the control of PP2A expression has been the focus of many studies, many aspects of its regulation still remain poorly understood. In this study, we describe a novel mechanism of PP2A regulation. We propose that the transcription factor Ikaros binds to a variant site in the first intron of PP2A and modulates its expression. Exogenous expression of Ikaros leads to reduced levels of PP2Ac message as well as protein. Conversely, siRNA-enabled silencing of Ikaros enhances the expression of PP2A, suggesting that Ikaros acts as a suppressor of PP2A expression. A ChIP analysis further proved that Ikaros is recruited to this site in T cells. We also attempted to delineate the mechanism of Ikaros-mediated PP2Ac gene suppression. We show that Ikaros-mediated suppression of PP2A expression is at least partially dependent on the recruitment of the histone deacetylase HDAC1 to this intronic site. We conclude that the transcription factor Ikaros can regulate the expression of PP2A by binding to a site in the first intron and modulating chromatin modifications at this site via recruitment of HDAC1.

Correction: Downregulation of miR-200a-3p, Targeting CtBP2 Complex, Is Involved in the Hypoproduction of IL-2 in Systemic Lupus Erythematosus–Derived T Cells

Systemic lupus erythematosus (SLE) damages multiple organs by producing various autoantibodies. In this study, we report that decreased microRNA (miR)-200a-3p causes IL-2 hypoproduction through zinc finger E-box binding homeobox (ZEB)1 and C-terminal binding protein 2 (CtBP2) in a lupus-prone mouse. First, we performed RNA sequencing to identify candidate microRNAs and mRNAs involved in the pathogenesis of SLE. We found that miR-200a-3p was significantly downregulated, whereas its putative targets, ZEB2 and CtBP2, were upregulated in CD4 + T cells from MRL/lpr- Tnfrsf6 lpr mice compared with C57BL/6J mice. ZEB1 and ZEB2 comprise the ZEB family and suppress various genes, including IL-2 by recruiting CtBP2. IL-2 plays a critical role in immune tolerance, and insufficient IL-2 production upon stimulation has been recognized in SLE pathogenesis. Therefore, we hypothesized that decreased miR-200a-3p causes IL-2 deficit through the ZEB1–CtBP2 and/or ZEB2–CtBP2 complex in SLE CD4 + T cells. Overexpression of miR-200a-3p induced IL-2 production by downregulating ZEB1, ZEB2, and CtBP2 in EL4 cell lines. We further revealed that miR-200a-3p promotes IL-2 expression by reducing the binding of suppressive ZEB1–CtBP2 and ZEB2–CtBP2 complexes on negative regulatory element A in the IL-2 promoter in EL4 cells. Interestingly, the ZEB1–CtBP2 complex on negative regulatory element A was significantly upregulated after PMA/ionomycin stimulation in lupus CD4 + T cells. Our studies have revealed a new epigenetic pathway in the control of IL-2 production in SLE whereby low levels of miR-200a-3p accumulate the binding of the ZEB1–CtBP2 complex to the IL-2 promoter and suppress IL-2 production.

The efficacy of add-on tacrolimus for minor flare in patients with systemic lupus erythematosus: a retrospective study

Objective We have assessed the effectiveness of tacrolimus for minor flares in systemic lupus erythematosus (SLE) patients. Methods The medical records of 313 patients were retrospectively reviewed over a period of seven years, from 2006 to 2013. We enrolled patients with minor flare treated with add-on tacrolimus, without glucocorticoid (GC) intensification (tacrolimus group). Minor flare was defined as a ≥1-point increase in a total score between 3 and 11 in the SLE Disease Activity Index (SLEDAI). We enrolled as controls patients who were administered increased doses of GC for minor flare (GC group). All patients were followed for one year. The primary outcome measure was the proportion of responders. Results There were 14 eligible patients in the tacrolimus group and 20 eligible patients in the GC group. The mean SLEDAI at flare tended to be higher in the tacrolimus group than in the GC group (7.5 vs. 6.2, p = 0.085). A mean dose of 1.6 mg tacrolimus/day was administered for flare, while the mean GC dose was 13.7 mg/day in the GC group. The proportion of responders was 86% (12/14) in the tacrolimus group and 75% (15/20) in the GC group (p = 0.67). The mean dose of GC at 12 months was higher in the GC group than in the tacrolimus group (9.7 mg/day vs. 7.1 mg/day, p < 0.05). Only one patient discontinued tacrolimus because of fatigue after three months. Conclusion Adding tacrolimus without increasing the GC dose may provide an effective treatment option for minor flares in patients with SLE.

Role of Lgals9 Deficiency in Attenuating Nephritis and Arthritis in BALB/c Mice in a Pristane-Induced Lupus Model

In systemic lupus erythematosus (SLE), an autoimmune disease associated with multiple organ involvement, the development of lupus nephritis determines prognosis, and arthritis impairs quality of life. Galectin 9 (Gal‐9, Lgals9) is a β‐galactoside–binding lectin that has been used for clinical application in autoimmune diseases, since recombinant Gal‐9, as a ligand for T cell immunoglobulin and mucin domain–containing protein 3 (TIM‐3), induces apoptosis of activated CD4+TIM‐3+ Th1 cells. This study was undertaken to investigate whether deficiency of Lgals9 has beneficial or deleterious effects on lupus in a murine model.

Bilateral Abducens Nerve Palsy due to Idiopathic Intracranial Hypertension as an Initial Manifestation of Systemic Lupus Erythematosus

Idiopathic intracranial hypertension (IIH) is a syndrome of increased intracranial pressure and presents as an intractable headache, vomiting, and ophthalmologic manifestations. We herein report the case of a young girl who presented with bilateral abducens nerve palsy due to IIH as the onset of systemic lupus erythematosus (SLE). The patient was successfully treated with corticosteroid therapy. Our case lacked the typical symptoms of IIH, such as headache or nausea; therefore, it is necessary to carefully determine the cause of bilateral abducens nerve palsies. The development of IIH in SLE patients is a rare occurrence, but this manifestation should not be overlooked.

Anti-SS-A/Ro antibody positivity as a risk factor for relapse in patients with polymyositis/dermatomyositis

Abstract Objective: The objective of this study is to elucidate predictors of relapse in patients with polymyositis and dermatomyositis (PM/DM). Methods: Fifty PM/DM patients who achieved disease stabilization at Okayama University Hospital in 2004–2014 were enrolled retrospectively. Candidate predictors such as demographic factors, clinical symptoms, laboratory data, and treatment status were compared. Results: The mean age of enrolled patients was 58 years; 34 were female. The patient groupings were as follows: 21 with PM, 27 with DM, and two with clinically amyopathic DM. During a mean observation period of 685 d, 5 patients (10%) died and 20 (40%) relapsed. The relapsed patients displayed baseline muscle weakness less frequently (85% versus 100%, p = .03) and anti-SS-A/Ro antibody more frequently (65% versus 27%, p = .007). Anti-SS-A/Ro-positive patients exhibited a higher relapse rate than anti-SS-A/Ro-negative patients (log-rank test, p = .03). Anti-SS-A/Ro-positive patients also exhibited higher anti-Jo-1 antibody positivity and lower levels of serum complement. After adjusting anti-Jo-1 antibody positivity, age, sex, CK <500 IU/L, and lung involvement, anti-SS-A/Ro positivity was still an independent risk factor for higher relapse-rate (odds ratio, 5.5; 95% confidence interval, 1.4–25.1). Conclusions: Anti-SS-A/Ro antibody positivity may be a useful biomarker for prediction of relapse.

Anti-high Mobility Group Box 1 Antibody Ameliorates Albuminuria in MRL/lpr Lupus-Prone Mice

We evaluated the efficacy of a neutralizing anti-high mobility group box 1 (HMGB1) monoclonal antibody in MRL/lpr lupus-prone mice. The anti-HMGB1 monoclonal antibody (5 mg/kg weight) or class-matched control immunoglobulin G2a (IgG2a) was administered intravenously twice a week for 4–15 weeks. Urine albumin was monitored, and histological evaluation of the kidneys was conducted at 16 weeks. Lymphadenopathies were evaluated by 1-(2′-deoxy-2′-[18F]fluoro-β-D-arabinofuranosyl)cytosine ([18F]FAC) positron emission tomography/computed tomography (PET/CT) at 12 weeks. Following 4-week treatment, [18F]FAC-PET/CT showed similar accumulation in cervical and axillary lymph nodes at 12 weeks of age. However, anti-HMGB1 monoclonal antibody sufficiently inhibited the increase in albuminuria compared to an isotype control following 15-week treatment. Complement deposition was also improved; however, there were no significant differences in IgG deposition and renal pathological scores between the two groups. Anti-double-stranded DNA (dsDNA) antibody titers and cytokine and chemokine levels were also unaltered. Although there were no significant differences in glomerular macrophage infiltration, neutrophil infiltration was significantly decreased by the anti-HMGB1 monoclonal antibody. Antagonizing HMGB1 treatment suppressed HMGB1 translocation from nuclei in the kidney and suppressed neutrophil extracellular traps. The anti-HMGB1 monoclonal antibody demonstrated therapeutic potential against albuminuria in lupus nephritis by inhibiting neutrophil recruitment and neutrophil extracellular traps.

Central diabetes insipidus in refractory antineutrophil cytoplasmic antibody-associated vasculitis

We herein describe two cases of refractory antineutrophil cytoplasmic antibody-associated vasculitis (AAV) complicated with diabetes insipidus (DI) possibly related to hypertrophic pachymeningitis (HP). One patient had microscopic polyangiitis and HP, which were refractory to cyclophosphamide, azathioprine, rituximab, mycophenolate mofetil (MMF), and mizoribine. Remission was finally achieved with the use of etanercept, but DI occurred 5 years later. The other patient had granulomatosis with polyangiitis, which that was refractory to cyclophosphamide, methotrexate, MMF, and rituximab. DI subsequently developed, but was successfully treated with etanercept. Dura mater hypertrophy was macroscopically observed in the latter case.