Epstein-barr virus infections induce aberrant osteoclastogenesis in immune system-humanized NOD/Shi-scid/IL-2RγCnull mice.

Epstein-Barr virus (EBV) and other viral infections are possible triggers of autoimmune diseases, such as rheumatoid arthritis (RA). To analyze the causative relationship between EBV infections and RA development, we performed experiment on humanized NOD/Shi-scid/IL-2RγCnull (hu-NOG) mice reconstituted human immune system components and infected with EBV. In EBV-infected hu-NOG mice, breakdown of knee joint bones was found to be accompanied by the accumulation of receptor activator of nuclear factor-κB (NF-κB) (RANK) ligand (RANKL), a key factor in osteoclastogenesis, human CD19 and EBV-encoded small RNA (EBER)-bearing cells. Accumulation of these cells expanded in the bone marrow adjacent to the bone breakage, showing a histological feature like to that in bone marrow edema. On the other hand, human RANK/human matrix metalloprotease-9 (MMP-9) positive, osteoclast-like cells were found at broken bone portion of EBV-infected mouse knee joint. In addition, human macrophage-colony stimulating factor (M-CSF), an essential factor in development of osteoclasts, evidently expressed in spleen and bone marrow of EBV-infected humanized mice. Furthermore, RANKL and M-CSF were identified at certain period of EBV-transformed B lymphoblastoid cells (BLBCs) derived from umbilical cord blood lymphocytes. Co-culturing bone marrow cells of hu-NOG mice with EBV-transformed BLBCs resulted in the induction of a multinucleated cell population positive for tartrate-resistant acid phosphatase and human MMP-9 which indicating human osteoclast-like cells. These findings suggest that EBV-infected BLBCs induce human aberrant osteoclastogenesis, which cause erosive arthritis in the joints.

Risk factors associated with relapse after methotrexate dose reduction in patients with rheumatoid arthritis receiving golimumab and methotrexate combination therapy.

AIM: To identify risk factors for relapse after methotrexate (MTX) dose reduction in rheumatoid arthritis (RA) patients receiving golimumab (GLM)/MTX combination therapy. METHOD: Data on RA patients ≥20 years old receiving GLM (50 mg) + MTX for ≥6 months were retrospectively collected. MTX dose reduction was defined as a reduction of ≥12 mg from the total dose within 12 weeks of the maximum dose (≥1 mg/wk average). Relapse was defined as Disease Activity Score in 28 joints using C-reactive protein level (DAS28-CRP) score ≥3.2 or sustained (≥ twice) increase of ≥0.6 from baseline. RESULTS: A total of 304 eligible patients were included. Among the MTX-reduction group (n = 125), 16.8% of patients relapsed. Age, duration from diagnosis to the initiation of GLM, baseline MTX dose, and DAS28-CRP were comparable between relapse and no-relapse groups. The adjusted odds ratio (aOR) of relapse after MTX reduction was 4.37 (95% CI 1.16-16.38, P = 0.03) for prior use of non-steroidal anti-inflammatory drugs (NSAIDs), and the aORs for cardiovascular disease (CVD), gastrointestinal disease and liver disease were 2.36, 2.28, and 3.03, respectively. Compared to the non-reduction group, the MTX-reduction group had a higher proportion of patients with CVD (17.6% vs 7.3%, P = 0.02) and a lower proportion of prior use of biologic disease-modifying antirheumatic drugs (11.2% vs. 24.0%, P = 0.0076). CONCLUSION: Attention should be given to RA patients with history of CVD, gastrointestinal disease, liver disease, or prior NSAIDs-use when considering MTX dose reduction to ensure benefits outweigh the risks of relapse.

Are Viral Infections Key Inducers of Autoimmune Diseases? Focus on Epstein-Barr Virus.

It is generally accepted that certain viral infections can trigger the development of autoimmune diseases. However, the exact mechanisms by which these viruses induce autoimmunity are still not understood. In this review, we first describe hypothetical mechanisms by which viruses induce some representative autoimmune diseases. Then, we focus on Epstein-Barr virus (EBV) and discuss its role in the pathogenesis of rheumatoid arthritis (RA). The discussion is mainly based on our own previous findings that (A) EBV DNA and its products EBV-encoded small RNA (EBER) and latent membrane protein 1 (LMP1) are present in the synovial lesions of RA, (B) mRNA expression of the signaling lymphocytic activation molecule-associated protein (SAP)/SH2D1A gene that plays a critical role in cellular immune responses to EBV is reduced in the peripheral T cells of patients with RA, and (C) EBV infection of mice reconstituted with human immune system components (humanized mice) induced erosive arthritis that is pathologically similar to RA. Additionally, environmental factors may contribute to EBV reactivation as follows: Porphyromonas gingivalis peptidylarginine deiminase (PAD), an enzyme required for citrullination, engenders antigens leading to the production of citrullinated peptides both in the gingiva and synovium. Anti-citrullinated peptides autoantibody is an important marker for diagnosis and disease activity of RA. These findings, as well as various results obtained by other researchers, strongly suggest that EBV is directly involved in the pathogenesis of RA, a typical autoimmune disease.

Successful treatment for eosinophilic granulomatosis with polyangiitis causing severe myocarditis followed by cardiac magnetic resonance.

A 38-year-old woman had a history of asthma for 20 years. Bullous lesions had appeared on her left side of the back. Two months before admission, the biopsy revealed eosinophilic cellulitis. One month later, she experienced numbness in both legs. She was admitted to our hospital for emergency treatment due to chest pain and loss of consciousness. Emergency coronary angiography revealed triple-vessel vasospasm. She had cardiac arrest for 4 min during the examination. We suspected eosinophilic granulomatosis with polyangiitis due to pulmonary infiltrate, eosinophilia, and a history of illness. We, therefore, started methylprednisolone pulse therapy. Although her condition and laboratory findings improved, cardiac magnetic resonance (CMR) imaging performed on day 16 showed myocardial oedema and myocardial fibrosis on late gadolinium enhancement. Coronary angiography on day 35 revealed no spasm, and myocardial biopsy showed the absence of vasculitis. There was no improvement in myocardial oedema. CMR showed enlargement of late gadolinium enhancement and formation of a ventricular aneurysm. As myocarditis did not improve sufficiently, five courses of intravenous cyclophosphamide pulse therapy were administered. CMR on day 152 showed the disappearance of myocardial oedema. We report a unique case of successful treatment of severe myocarditis and the usefulness of follow-up CMR.

Antinuclear antibodies produced in HLA-DR transgenic humanized mice developed chronic graft-versus-host disease.

BACKGROUND: Chronic graft versus host disease (GVHD) has been reported in humanized mice after the implantation of human hematopoietic stem cells (hu-HSC). As such, humanized mice have been applied to a mouse model of chronic GVHD; however, B-cell activation and autoantibody production did not occur, and the clinical features of chronic GVHD were not sufficiently reproduced. The purpose of this study was to establish an improved humanized mouse model with chronic GVHD using HLA-DR transgenic NOD/Shi-scid, IL-2RγKO (NOG) mice. METHODS: CD34-positive cells were isolated from blood extracted from HLA-DRB1∗0405-positive umbilical cords using magnetic cell isolation. Then these were transplanted into NOG-Iab KO, HLA-DR 0405 Tg mice aged 8-16 weeks. GVHD symptoms were observed 26 weeks after transplantation. Histological findings of the skin, lung, liver, and spleen were compared with those of non-humanized mice. Antinuclear antibodies (ANA) were measured by indirect immunofluorescence using sera isolated 26 weeks after transplantation. RESULTS: Although GVHD symptoms were not observed in humanized (hu-HSC) NOG-Iab KO, HLA-DR 0405 Tg mice during the observation period, histological findings of human T-cell infiltration were observed in the skin, liver, and lung, suggesting that GVDH was present; human tingible body macrophages or clusters of BCL-6-positive human B-cells were observed in the spleen. Furthermore, human IgG ANA with peripheral or homogeneous staining patterns were also detected in the sera. CONCLUSION: Hu-HSC NOG-Iab KO, HLA-DR 0405 Tg mice differed from conventional models in terms of B-cell activation and ANA production. This study is the first to report on B-cell activation and autoantibody production in humanized mice with chronic GVHD, suggesting that hu-HSC NOG-Iab KO, HLA-DR 0405 Tg mice could be applied to a new humanized mouse model of chronic GVHD.

Successful early introduction of mepolizumab for peripheral neuropathy with a peripheral circulatory disorder in a patient with myeloperoxidase anti-neutrophil cytoplasmic antibody-negative eosinophilic granulomatosis with polyangiitis.

A 26-year-old woman presented with abdominal pain, diarrhoea, vomiting, fever, and progressive paralysis in the lower limbs. She had a history of bronchial asthma and experienced sinusitis, progressive peripheral neuropathy, polyarthritis, and leukocytosis with prominent eosinophilia. The patient was diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA). Abdominal pain was considered to be an ischaemic enteritis associated with EGPA. She was administered 1,000 mg/day of methylprednisolone for 3 days and intravenous immunoglobulin (400 mg/kg/day of γ-globulin for 5 days) followed by 50 mg (1 mg/kg)/day of oral prednisolone due to rapidly progressing peripheral neuropathy. Her symptoms temporarily improved; however, peripheral neuropathy recurred after a week, and the eosinophil count increased. Eighteen days after following the resumed treatment, 300 mg of mepolizumab, a humanised monoclonal antibody, was administered. Subjective symptoms, nerve conduction velocity, and skin perfusion pressure (an index of peripheral circulation in the lower extremities) improved after 4 weeks. Although mepolizumab has been approved for EGPA, there is no evidence of its efficacy against peripheral neuropathy. Early introduction of mepolizumab may contribute to an the early improved progressive peripheral neuropathy with eosinophilia.

Human osteoclastogenesis in Epstein-Barr virus-induced erosive arthritis in humanized NOD/Shi-scid/IL-2Rγnull mice.

Many human viruses, including Epstein-Barr virus (EBV), do not infect mice, which is challenging for biomedical research. We have previously reported that EBV infection induces erosive arthritis, which histologically resembles rheumatoid arthritis, in humanized NOD/Shi-scid/IL-2Rγnull (hu-NOG) mice; however, the underlying mechanisms are not known. Osteoclast-like multinucleated cells were observed during bone erosion in this mouse model, and therefore, we aimed to determine whether the human or mouse immune system activated bone erosion and analyzed the characteristics and origin of the multinucleated cells in hu-NOG mice. Sections of the mice knee joint tissues were immunostained with anti-human antibodies against certain osteoclast markers, including cathepsin K and matrix metalloproteinase-9 (MMP-9). Multinucleated cells observed during bone erosion stained positively for human cathepsin K and MMP-9. These results indicate that human osteoclasts primarily induce erosive arthritis during EBV infections. Human osteoclast development from hematopoietic stem cells transplanted in hu-NOG mice remains unclear. To confirm their differentiation potential into human osteoclasts, we cultured bone marrow cells of EBV-infected hu-NOG mice and analyzed their characteristics. Multinucleated cells cultured from the bone marrow cells stained positive for human cathepsin K and human MMP-9, indicating that bone marrow cells of hu-NOG mice could differentiate from human osteoclast progenitor cells into human osteoclasts. These results indicate that the human immune response to EBV infection may induce human osteoclast activation and cause erosive arthritis in this mouse model. Moreover, this study is the first, to our knowledge, to demonstrate human osteoclastogenesis in humanized mice. We consider that this model is useful for studying associations of EBV infections with rheumatoid arthritis and human bone metabolism.