A new in vitro model of polymyositis reveals CD8+ T cell invasion into muscle cells and its cytotoxic role.

OBJECTIVES: The hallmark histopathology of PM is the presence of CD8+ T cells in the non-necrotic muscle cells. The aim of this study was to clarify the pathological significance of CD8+ T cells in muscle cells. METHODS: C2C12 cells were transduced retrovirally with the genes encoding MHC class I (H2Kb) and SIINFEKL peptide derived from ovalbumin (OVA), and then differentiated to myotubes (H2KbOVA-myotubes). H2KbOVA-myotubes were co-cultured with OT-I CD8+ T cells derived from OVA-specific class I restricted T cell receptor transgenic mice as an in vitro model of PM to examine whether the CD8+ T cells invade into the myotubes and if the myotubes with the invasion are more prone to die than those without. Muscle biopsy samples from patients with PM were examined for the presence of CD8+ T cells in muscle cells. The clinical profiles were compared between the patients with and without CD8+ T cells in muscle cells. RESULTS: Analysis of the in vitro model of PM with confocal microscopy demonstrated the invasion of OT-I CD8+ T cells into H2KbOVA-myotubes. Transmission electron microscopic analysis revealed an electron-lucent area between the invaded CD8+ T cell and the cytoplasm of H2KbOVA-myotubes. The myotubes invaded with OT-I CD8+ T cells died earlier than the uninvaded myotubes. The level of serum creatinine kinase was higher in patients with CD8+ T cells in muscle cells than those without these cells. CONCLUSION: CD8+ T cells invade into muscle cells and contribute to muscle injury in PM. Our in vitro model of PM is useful to examine the mechanisms underlying muscle injury induced by CD8+ T cells.

Autophagy-deficient mice develop multiple liver tumors.

Autophagy is a major pathway for degradation of cytoplasmic proteins and organelles, and has been implicated in tumor suppression. Here, we report that mice with systemic mosaic deletion of Atg5 and liver-specific Atg7⁻/⁻ mice develop benign liver adenomas. These tumor cells originate autophagy-deficient hepatocytes and show mitochondrial swelling, p62 accumulation, and oxidative stress and genomic damage responses. The size of the Atg7⁻/⁻ liver tumors is reduced by simultaneous deletion of p62. These results suggest that autophagy is important for the suppression of spontaneous tumorigenesis through a cell-intrinsic mechanism, particularly in the liver, and that p62 accumulation contributes to tumor progression.

Splicing variant of WDFY4 augments MDA5 signalling and the risk of clinically amyopathic dermatomyositis.

OBJECTIVES: Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases in which both genetic and environmental factors play important roles. To identify genetic factors of IIM including polymyositis, dermatomyositis (DM) and clinically amyopathic DM (CADM), we performed the first genome-wide association study for IIM in an Asian population. METHODS: We genotyped and tested 496 819 single nucleotide polymorphism for association using 576 patients with IIM and 6270 control subjects. We also examined the causal mechanism of disease-associated variants by in silico analyses using publicly available data sets as well as by in in vitro analyses using reporter assays and apoptosis assays. RESULTS: We identified a variant in WDFY4 that was significantly associated with CADM (rs7919656; OR=3.87; P=1.5×10-8). This variant had a cis-splicing quantitative trait locus (QTL) effect for a truncated WDFY4isoform (tr-WDFY4), with higher expression in the risk allele. Transexpression QTL analysis of this variant showed a positive correlation with the expression of NF-κB associated genes. Furthermore, we demonstrated that both WDFY4 and tr-WDFY4 interacted with pattern recognition receptors such as TLR3, TLR4, TLR9 and MDA5 and augmented the NF-κB activation by these receptors. WDFY4 isoforms also enhanced MDA5-induced apoptosis to a greater extent in the tr-WDFY4-transfected cells. CONCLUSIONS: As CADM is characterised by the appearance of anti-MDA5 autoantibodies and severe lung inflammation, the WDFY4 variant may play a critical role in the pathogenesis of CADM.

Elevation of KL-6 serum levels in clinical trials of tumor necrosis factor inhibitors in patients with rheumatoid arthritis: a report from the Japan College of Rheumatology Ad Hoc Committee for Safety of Biological DMARDs.

OBJECTIVE: The associations between elevated levels of serum Krebs von den Lungen-6 (KL-6) and treatment of rheumatoid arthritis (RA) with tumor necrosis factor (TNF) inhibitors were investigated in five Japanese clinical trials. METHODS: Percentages and incidence rates were calculated for elevated serum KL-6 levels. Adverse events associated with elevated levels of serum KL-6 were investigated. RESULTS: In RISING, a clinical trial for infliximab, 15.6 % of the enrolled patients met criterion B (KL-6 ≥500 U/ml and >1.5-fold increase over the baseline value) by week 54. In HIKARI, 7.8 % of the certolizumab pegol (CZP) group and 0 % of the placebo group met criterion B during the double-blind (DB) period (p = 0.003). In J-RAPID, 8.4 % of the methotrexate (MTX) + CZP and 3.9 % of the MTX + placebo groups met criterion B during the DB period. In GO-MONO, 1.8 % of the golimumab (GLM) and 1.3 % of the placebo groups met criterion B during the DB period. In GO-FORTH, 7.1 % of the MTX + GLM and 0 % of the MTX + placebo groups met criteron B during the DB period (p = 0.017). No adverse events accompanied the elevation of serum KL-6 levels in 95.7 % of these patients. CONCLUSION: Serum KL-6 levels may increase during anti-TNF therapy without significant clinical events. In these patients, continuing treatment with TNF inhibitors under careful observation is a reasonable option.

A retrospective study of serum KL-6 levels during treatment with biological disease-modifying antirheumatic drugs in rheumatoid arthritis patients: a report from the Ad Hoc Committee for Safety of Biological DMARDs of the Japan College of Rheumatology.

OBJECTIVE: We investigated associations between treatment with methotrexate (MTX) or biological disease-modifying antirheumatic drugs (DMARDs) and elevation of serum Krebs von den Lungen-6 (KL-6) levels in Japanese patients with rheumatoid arthritis (RA). METHODS: Using a standardized form, data were collected retrospectively from medical records and analyzed descriptively. RESULTS: Of a total of 198 RA patients with KL-6 serum levels measured at initiation of treatment (month 0) and two or more times by month 12, 27 (17.9 %) of 151 RA patients treated with biological DMARDs, including infliximab, etanercept, adalimumab, and tocilizumab (the biological DMARDs group), and 5 (10.6 %) of 47 patients treated without biological DMARDs but with MTX (MTX group), met criterion B (max. KL-6 ≥500 U/ml and >1.5-fold from baseline) by 12 months. The majority of patients (n = 28) meeting criterion B had no apparent interstitial lung disease or malignancy. Of these 28 patients, 21 had serum KL-6 levels available after reaching their maximum level, and 13 (61.9 %) of the 21 then met criterion R [decrease to less than 500 U/ml or to less than (baseline + 0.5 × (maximum - baseline))] by month 12. CONCLUSION: Serum KL-6 levels may increase during treatment with MTX or these biological DMARDs without significant clinical events.

A severe case of thrombocytopenia, anasarca, fever, renal insufficiency or reticulin fibrosis, and organomegaly syndrome with myocardial and skeletal muscle calcification despite hypocalcemia: a case report.

BACKGROUND: TAFRO (thrombocytopenia, anasarca, fever, renal insufficiency or reticulin fibrosis, and organomegaly) syndrome is a recently recognized disease with a variety of presentations of variable severity. In acute settings, this disease also involves organ dysfunction because of the associated systemic inflammation. However, cases of TAFRO syndrome with myocardial and/or skeletal muscle calcification have never been reported. CASE PRESENTATION: A 24-year-old healthy young Asian man was admitted with intermittent epigastric pain and fever for 2 weeks. Computed tomography revealed pleural effusion, ascites and systemic lymphadenopathy. Laboratory tests showed thrombocytopenia, elevated C-reactive protein, hypoalbuminemia, anemia and renal dysfunction. Based on these findings and bone marrow biopsy, we diagnosed his disease as TAFRO syndrome and commenced hemodialysis for the renal dysfunction. However, he developed refractory hypocalcemia with unstable vital signs, for which we administered calcium gluconate hydrate. Thereafter, myocardial and skeletal muscle calcification was revealed radiologically, with the myocardial calcification causing sick sinus syndrome. He was treated with tocilizumab and finally discharged in an ambulatory condition after prolonged hospitalization, with residual calcific lesions. CONCLUSION: This is the first report of a patient with TAFRO syndrome and the complication of organ calcification. The etiology of calcification in this case is not clear. Systemic inflammation with possible hypercytokinemia might have been involved in the unexpected complication of systemic calcification. It is important to carefully handle the general management of TAFRO syndrome because of the possibility of various complications.

The first case of thrombocytopenia, anasarca, fever, renal impairment or reticulin fibrosis, and organomegaly (TAFRO) syndrome with unilateral adrenal necrosis: a case report.

BACKGROUND: TAFRO syndrome, which was first reported in 2010 in Japan, is a relatively rare disease characterized by thrombocytopenia, anasarca, fever, renal impairment, reticulin fibrosis, and organomegaly. Although this disease is considered similar to multicentric Castleman disease, some of the clinical features, such as thrombocytopenia, are different from typical cases of multicentric Castleman disease. In addition, the etiology of TAFRO syndrome remains unknown and controversial. There have only been a few cases of TAFRO syndrome complicated with adrenal gland lesions, and all of them have had hemorrhagic involvement. CASE PRESENTATION: This report describes the case of a 46-year-old Asian man who presented with fever, epigastric pain, and back pain for 1 month. A computed tomographic scan revealed ascites, mild lymphadenopathy, and left adrenal necrosis without hemorrhage. A blood test showed thrombocytopenia, anemia, and elevated C-reactive protein, alkaline phosphatase, and creatinine levels. Based on the edema, severe thrombocytopenia, fever, reticulin myelofibrosis shown by bone marrow biopsy, mild lymphadenopathy, and progressive renal insufficiency, we diagnosed this patient as having TAFRO syndrome. He was successfully treated by immediate administration of glucocorticoids and tocilizumab. CONCLUSIONS: There have been no previous reports of a case of TAFRO syndrome complicated with adrenal necrosis. Because the biopsy of the left adrenal gland revealed necrosis without any evidence of hemorrhage, we concluded that the unilateral adrenal necrosis in this case was caused by either ischemia from infarction or organomegaly itself under severe hypercytokinemia. This unusual clinical course is useful for further analysis of the etiology of TAFRO syndrome.

Anti-EJ antibody positive interstitial lung disease with skin changes at the fingertips.

  Antisynthetase syndrome is characterized by the presence of anti-aminoacyl-tRNA synthetase antibodies and characteristic clinical features. We report an anti-EJ antibody-positive case presenting an ILD with slight hyperkeratotic skin changes on the fingertips that appeared simultaneously with respiratory symptoms. We suspected those skin changes of a disease manifestation of antisynthetase syndrome, and thus investigated anti-synthetase antibodies. This case implies that broader spectrum of the patients should fall in antisynthetase syndrome even though the present diagnostic criteria call for mechanic's hand as a skin manifestation. Careful examination of the finger skin and antibody testing should lead to a proper understanding of the pathological processes.

Nutrient-dependent mTORC1 association with the ULK1-Atg13-FIP200 complex required for autophagy.

Autophagy is an intracellular degradation system, by which cytoplasmic contents are degraded in lysosomes. Autophagy is dynamically induced by nutrient depletion to provide necessary amino acids within cells, thus helping them adapt to starvation. Although it has been suggested that mTOR is a major negative regulator of autophagy, how it controls autophagy has not yet been determined. Here, we report a novel mammalian autophagy factor, Atg13, which forms a stable approximately 3-MDa protein complex with ULK1 and FIP200. Atg13 localizes on the autophagic isolation membrane and is essential for autophagosome formation. In contrast to yeast counterparts, formation of the ULK1-Atg13-FIP200 complex is not altered by nutrient conditions. Importantly, mTORC1 is incorporated into the ULK1-Atg13-FIP200 complex through ULK1 in a nutrient-dependent manner and mTOR phosphorylates ULK1 and Atg13. ULK1 is dephosphorylated by rapamycin treatment or starvation. These data suggest that mTORC1 suppresses autophagy through direct regulation of the approximately 3-MDa ULK1-Atg13-FIP200 complex.

FIP200, a ULK-interacting protein, is required for autophagosome formation in mammalian cells.

Autophagy is a membrane-mediated intracellular degradation system. The serine/threonine kinase Atg1 plays an essential role in autophagosome formation. However, the role of the mammalian Atg1 homologues UNC-51-like kinase (ULK) 1 and 2 are not yet well understood. We found that murine ULK1 and 2 localized to autophagic isolation membrane under starvation conditions. Kinase-dead alleles of ULK1 and 2 exerted a dominant-negative effect on autophagosome formation, suggesting that ULK kinase activity is important for autophagy. We next screened for ULK binding proteins and identified the focal adhesion kinase family interacting protein of 200 kD (FIP200), which regulates diverse cellular functions such as cell size, proliferation, and migration. We found that FIP200 was redistributed from the cytoplasm to the isolation membrane under starvation conditions. In FIP200-deficient cells, autophagy induction by various treatments was abolished, and both stability and phosphorylation of ULK1 were impaired. These results suggest that FIP200 is a novel mammalian autophagy factor that functions together with ULKs.