Shimpei Kasagi

Proteasome assembly defect due to a proteasome subunit beta type 8 (PSMB8) mutation causes the autoinflammatory disorder, Nakajo-Nishimura syndrome

Nakajo-Nishimura syndrome (NNS) is a disorder that segregates in an autosomal recessive fashion. Symptoms include periodic fever, skin rash, partial lipomuscular atrophy, and joint contracture. Here, we report a mutation in the human proteasome subunit beta type 8 gene (PSMB8) that encodes the immunoproteasome subunit β5i in patients with NNS. This G201V mutation disrupts the β-sheet structure, protrudes from the loop that interfaces with the β4 subunit, and is in close proximity to the catalytic threonine residue. The β5i mutant is not efficiently incorporated during immunoproteasome biogenesis, resulting in reduced proteasome activity and accumulation of ubiquitinated and oxidized proteins within cells expressing immunoproteasomes. As a result, the level of interleukin (IL)-6 and IFN-γ inducible protein (IP)-10 in patient sera is markedly increased. Nuclear phosphorylated p38 and the secretion of IL-6 are increased in patient cells both in vitro and in vivo, which may account for the inflammatory response and periodic fever observed in these patients. These results show that a mutation within a proteasome subunit is the direct cause of a human disease and suggest that decreased proteasome activity can cause inflammation.

Anti-Programmed Cell Death 1 Antibody Reduces CD4+PD-1+ T Cells and Relieves the Lupus-Like Nephritis of NZB/W F1 Mice

Programmed cell death 1 (PD-1) is an immunosuppressive receptor that transduces an inhibitory signal into activated T cells. Although a single nucleotide polymorphism in the gene for PD-1 is associated with susceptibility to systemic lupus erythematosus, the role of PD-1 in systemic lupus erythematosus is still not well understood. In this study, we used NZB/W F1 mice, a model of lupus-like nephritis, to examine the function of PD-1 and its ligands. PD-1 was predominantly expressed on CD4+ T cells that infiltrated the kidney, and CD4+PD-1high T cells produced higher levels of IFN-γ than CD4+PD-1low or CD4+PD-1− T cells. Stimulation with PMA/ionomycin caused splenic CD4+PD-1+ T cells to secrete high levels of IFN-γ, IL-10, low levels of TNF-α, faint levels of IL-2, IL-21, and no IL-4, IL-17. In vivo anti–PD-1 mAb treatment reduced the number of CD4+PD-1+ T cells in the kidney of NZB/W F1 mice and significantly reduced their mortality rate (p = 0.03). Conversely, blocking PD-L1 using an anti–PD-L1 mAb increased the number of CD4+PD-1+ T cells in the kidney, enhanced serum IFN-γ, IL-10, and IgG2a ds-DNA–Ab levels, accelerated the nephritis, and increased the mortality rate. We conclude that CD4+PD-1high T cells are dysregulated IFN-γ–producing, proinflammatory cells in NZB/W F1 mice.

SS-A/Ro52 promotes apoptosis by regulating Bcl-2 production

SS-A/Ro52 (Ro52), an autoantigen in systemic autoimmune diseases such as systemic lupus erythematosus and Sjögrens syndrome, has E3 ligase activity to ubiquitinate proteins that protect against viral infection. To investigate Ro52s role during stress, we transiently knocked it down in HeLa cells by siRo52 transfection. We found that Ro52(low) HeLa cells were significantly more resistant to apoptosis than wild-type HeLa cells when stimulated by H(2)O(2)- or diamide-induced oxidative stress, IFN-α, IFN-γ and anti-Fas antibody, etoposide, or γ-irradiation. Furthermore, Ro52-mediated apoptosis was not influenced by p53 protein level in HeLa cells. Depleting Ro52 in HeLa cells caused Bcl-2, but not other Bcl-2 family molecules, to be upregulated. Taken together, our data showed that Ro52 is a universal proapoptotic molecule, and that its proapoptotic effect does not depend on p53, but is exerted through negative regulation of the anti-apoptotic protein Bcl-2. These findings shed light on a new physiological role for Ro52 that is important to intracellular immunity.

Histone deacetylase inhibition alters dendritic cells to assume a tolerogenic phenotype and ameliorates arthritis in SKG mice

IntroductionThe purpose of this study was to elucidate the effects of histone deacetylase inhibition on the phenotype and function of dendritic cells and on arthritis in SKG mice.MethodsArthritis was induced in SKG mice by zymosan A injection. Trichostatin A, a histone deacetylase inhibitor, was administered and its effects on arthritis were evaluated by joint swelling and histological evaluation. Interleukin-17 production in lymph node cells was determined by an enzyme-linked immunosorbent assay (ELISA). Foxp3 expression in lymph node cells and the phenotypes of splenic dendritic cells were examined by fluorescence-activated cell sorting (FACS). Bone marrow-derived dendritic cells (BM-DC) were generated with granulocyte macrophage colony-stimulating factor. The effects of trichostatin A on cell surface molecules, cytokine production, indoleamine 2,3-dioxygenase (IDO) expression and T cell stimulatory capacity were examined by FACS, ELISA, quantitative real-time polymerase chain reaction and Western blot, and the allo-mixed lymphocyte reaction, respectively.ResultsTrichostatin A, when administered before the onset of arthritis, prevented SKG mice from getting arthritis. Trichostatin A treatment also showed therapeutic effects on arthritis in SKG mice, when it was administered after the onset of arthritis. Trichostatin A treatment reduced Th17 cells and induced regulatory T cells in lymph node, and also decreased co-stimulatory molecule expression on splenic dendritic cells in vivo. In vitro, trichostatin A markedly suppressed zymosan A-induced interleukin-12 and interleukin-6 production by BM-DC and up-regulated IDO expression at mRNA and protein levels. Trichostatin A-treated BM-DC also showed less T cell stimulatory capacity.ConclusionsHistone deacetylase inhibition changes dendritic cells to a tolerogenic phenotype and ameliorates arthritis in SKG mice.

Plasma Platelet-derived Microparticles in Patients with Connective Tissue Diseases

Objective. To clarify the role of platelet-derived microparticles (PDMP), which are small vesicles with thrombotic and immunological properties, in systemic lupus erythematosus (SLE), systemic sclerosis (SSc), dermatomyositis/polymyositis (PM/DM), and mixed connective tissue disease (MCTD). Methods. Plasma levels of PDMP were measured by ELISA, and compared among patients with one of the 4 diseases. Association of PDMP levels with clinical characteristics and medication of the patients was also examined. Results. PDMP levels were higher in patients with MCTD and SSc than in controls. Multiple linear regression analysis revealed that patients with Raynaud’s phenomenon (RP) showed higher PDMP levels than those without. PDMP levels in individual patients did not fluctuate significantly over several months. Conclusion. PDMP level is associated with MCTD, SSc, and RP, and could be a novel marker for RP.

Role of imaging studies in the diagnosis and evaluation of giant cell arteritis in Japanese: report of eight cases

The objective of this study is to clarify the characteristics and imaging results of Japanese patients with giant cell arteritis (GCA). Eight patients with biopsy-proven GCA were enrolled. Their clinical data and imaging results were retrospectively examined from their medical records. All the patients met the criteria for the classification of GCA by the American College of Rheumatology. Although the clinical manifestations are similar to those previously reported, none of the eight patients presented ocular symptoms, and half of them presented jaw claudication. Ultrasonography (US) of temporal artery showed the halo sign in all the patients. Fluorodeoxyglucose positron emission tomography (FDG-PET) was performed in four patients and indicated the presence of aortitis of the patients. US is a quick and noninvasive test to detect inflammation of temporal artery, and FDG-PET is very helpful for early diagnosis of aortitis in GCA. Awareness of the disease and appropriate imaging tests will result in diagnosis of GCA.

Epidural spinal tumor and periaortitis as rare complications of Wegener’s granulomatosis

This case report describes findings in a 61-year-old woman who manifested scleritis, small pulmonary nodules, otitis media, periaortitis, and progressive epidural spinal tumor, associated with elevated serum myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) levels. She was clinically diagnosed with Wegener’s granulomatosis, although vasculitis was not diagnosed due to the lack of typical histological findings. We discuss the differential diagnosis in this patient, and the association of MPO-ANCA with periaortitis or epidural spinal tumor.

The HPB-AML-I cell line possesses the properties of mesenchymal stem cells.

BackgroundIn spite of its establishment from the peripheral blood of a case with acute myeloid leukemia (AML)-M1, HPB-AML-I shows plastic adherence with spindle-like morphology. In addition, lipid droplets can be induced in HPB-AML-I cells by methylisobutylxanthine, hydrocortisone, and indomethacin. These findings suggest that HPB-AML-I is similar to mesenchymal stem cells (MSCs) or mesenchymal stromal cells rather than to hematopoietic cells.MethodsTo examine this possibility, we characterized HPB-AML-I by performing cytochemical, cytogenetic, and phenotypic analyses, induction of differentiation toward mesenchymal lineage cells, and mixed lymphocyte culture analysis.ResultsHPB-AML-I proved to be negative for myeloperoxidase, while surface antigen analysis disclosed that it was positive for MSC-related antigens, such as CD29, CD44, CD55, CD59, and CD73, but not for CD14, CD19, CD34, CD45, CD90, CD105, CD117, and HLA-DR. Karyotypic analysis showed the presence of complicated abnormalities, but no reciprocal translocations typically detected in AML cases. Following the induction of differentiation toward adipocytes, chondrocytes, and osteocytes, HPB-AML-I cells showed, in conjunction with extracellular matrix formation, lipid accumulation, proteoglycan synthesis, and alkaline phosphatase expression. Mixed lymphocyte culture demonstrated that CD3+ T-cell proliferation was suppressed in the presence of HPB-AML-I cells.ConclusionsWe conclude that HPB-AML-I cells appear to be unique neoplastic cells, which may be derived from MSCs, but are not hematopoietic progenitor cells.

Claviform aspergillus‐related vegetation in the left ventricle of a patient with systemic lupus erythematosus

A 38‐year‐old woman was diagnosed with systemic lupus erythematosus and received immunosuppressive therapy. After 6 months of treatment, workup for low‐grade fever yielded elevated enzyme‐linked immunosorbent assay titers for Aspergillus antigen in serum and ascites, leading to the diagnosis of disseminated aspergillosis. Transthoracic echocardiography revealed a claviform vegetation attached to the left ventricular anterior septum. Two days after the start of antifungal Amphotericin‐B therapy, the patient suffered from several neurologic disorders. A second transthoracic echocardiography revealed that the vegetation decreased in size. Two weeks later, the vegetation increased again. Combination therapy of Amphotericin‐B and Voriconazole was initiated, and the vegetation eventually disappeared completely.