Junya Masumoto

ASC, a novel 22-kDa protein, aggregates during apoptosis of human promyelocytic leukemia HL-60 cells

The cytoskeletal and/or nuclear matrix molecules responsible for morphological changes associated with apoptosis were identified using monoclonal antibodies (mAbs). We developed mAbs against Triton X-100-insoluble components of HL-60 cells pretreated with all-trans retinoic acid. In particular, one mAb recognized a 22-kDa protein that exhibited intriguing behavior by forming an aggregate and appearing as a speck during apoptosis induced by retinoic acid and other anti-tumor drugs. Cloning and sequencing of its cDNA revealed that this protein comprises 195 amino acids and that its C-terminal half has a caspaserecruitment domain (CARD) motif, characteristic of numerous proteins involved in apoptotic signaling. We referred to this protein as ASC (apoptosis-associatedspeck-like protein containing a CARD). TheASC gene was mapped on chromosome 16p11.2–12. The antisense oligonucleotides of ASC were found to reduce the expression of ASC, and consequently, etoposide-mediated apoptosis of HL-60 cells was suppressed. Our results indicate that ASC is a novel member of the CARD-containing adaptor protein family.

Inflammasome Activation of Cardiac Fibroblasts Is Essential for Myocardial Ischemia/Reperfusion Injury

Background— Inflammation plays a key role in the pathophysiology of myocardial ischemia/reperfusion (I/R) injury; however, the mechanism by which myocardial I/R induces inflammation remains unclear. Recent evidence indicates that a sterile inflammatory response triggered by tissue damage is mediated through a multiple-protein complex called the inflammasome. Therefore, we hypothesized that the inflammasome is an initial sensor for danger signal(s) in myocardial I/R injury. Methods and Results— We demonstrate that inflammasome activation in cardiac fibroblasts, but not in cardiomyocytes, is crucially involved in the initial inflammatory response after myocardial I/R injury. We found that inflammasomes are formed by I/R and that its subsequent activation of inflammasomes leads to interleukin-1&bgr; production, resulting in inflammatory responses such as inflammatory cell infiltration and cytokine expression in the heart. In mice deficient for apoptosis-associated speck-like adaptor protein and caspase-1, these inflammatory responses and subsequent injuries, including infarct development and myocardial fibrosis and dysfunction, were markedly diminished. Bone marrow transplantation experiments with apoptosis-associated speck-like adaptor protein–deficient mice revealed that inflammasome activation in bone marrow cells and myocardial resident cells such as cardiomyocytes or cardiac fibroblasts plays an important role in myocardial I/R injury. In vitro experiments revealed that hypoxia/reoxygenation stimulated inflammasome activation in cardiac fibroblasts, but not in cardiomyocytes, and that hypoxia/reoxygenation–induced activation was mediated through reactive oxygen species production and potassium efflux. Conclusions— Our results demonstrate the molecular basis for the initial inflammatory response after I/R and suggest that the inflammasome is a potential novel therapeutic target for preventing myocardial I/R injury.

Expression of Apoptosis-associated Speck-like Protein Containing a Caspase Recruitment Domain, a Pyrin N-terminal Homology Domain-containing Protein, in Normal Human Tissues

Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is a pyrin N-terminal homology domain (PYD)- and caspase recruitment domain (CARD)-containing a proapoptotic molecule. This molecule has also been identified as a target of methylation-induced silencing (TMS)-1. We cloned the ASC cDNA by immunoscreening using an anti-ASC monoclonal antibody. In this study, we determined the binding site of the anti-ASC monoclonal antibody on ASC and analyzed the expression of ASC in normal human tissues. ASC expression was observed in anterior horn cells of the spinal cord, trophoblasts of the placental villi, tubule epithelium of the kidney, seminiferous tubules and Leydig cells of the testis, hepatocytes and interlobular bile ducts of the liver, squamous epithelial cells of the tonsil and skin, hair follicle, sebaceous and eccrine glands of the skin, and peripheral blood leukocytes. In the colon, ASC was detected in mature epithelial cells facing the luminal side rather than immature cells located deeper in the crypts. These observations indicate that high levels of ASC are abundantly expressed in epithelial cells and leukocytes, which are involved in host defense against external pathogens and in well-differentiated cells, the proliferation of which is regulated.

Familial Mediterranean fever in Japan.

AbstractFamilial Mediterranean fever (FMF) is a hereditary autoinflammatory disease that is prevalent in Mediterranean populations. While it is considered a rare disease in the rest of world, a significant number of FMF patients have been reported in East Asia, including Japan. Our aim was to determine the prevalence of FMF in Japan and elucidate the clinical and genetic features of Japanese patients. A primary nationwide survey of FMF was conducted between January and December 2009. Hospitals specializing in pediatrics and hospitals with pediatric, internal medicine, and rheumatology/allergy departments were asked to report all patients with FMF during the survey year. The estimated total number of Japanese FMF patients was 292 (95% confidence interval, 187–398 people). We evaluated the clinical and genetic profiles of Japanese patients from the data obtained in a secondary survey of 134 FMF patients. High-grade fever was observed in 95.5%, chest pain (pleuritis symptoms) in 36.9%, abdominal pain (peritonitis symptoms) in 62.7%, and arthritis in 31.3%. Of the patients profiled, 25.4% of patients experienced their first attack before 10 years of age, 37.3% in their teens, and 37.3% after age 20 years. Colchicine was effective in 91.8% of patients at a relatively low dose (mean dose, 0.89 ± 0.45 mg/d). AA amyloidosis was confirmed in 5 patients (3.7%). Of the 126 patients studied, 109 (86.5%) were positive for 1 or more genetic mutations and 17 (13.5%) had no mutation detected. Common Mediterranean fever gene (MEFV) mutations were E148Q/M694I (19.8%) and M694I/normal (12.7%). The differences in the prevalence of peritonitis, pleuritis, and a family history of FMF were statistically significant between FMF patients with MEFV exon 10 mutations compared with those without exon 10 mutations.In conclusion, a significant number of patients with FMF exist in Japan. Although Japanese patients with FMF are clinically or genetically different from Mediterranean patients, the delay in diagnosis is an issue that should be resolved.

Essential role of gastric gland mucin in preventing gastric cancer in mice.

Gastric gland mucin secreted from the lower portion of the gastric mucosa contains unique O-linked oligosaccharides (O-glycans) having terminal α1,4-linked N-acetylglucosamine residues (αGlcNAc). Previously, we identified human α1,4-N-acetylglucosaminyltransferase (α4GnT), which is responsible for the O-glycan biosynthesis and characterized αGlcNAc function in suppressing Helicobacter pylori in vitro. In the present study, we engineered A4gnt(-/-) mice to better understand its role in vivo. A4gnt(-/-) mice showed complete lack of αGlcNAc expression in gastric gland mucin. Surprisingly, all the mutant mice developed gastric adenocarcinoma through a hyperplasia-dysplasia-carcinoma sequence in the absence of H. pylori infection. Microarray and quantitative RT-PCR analysis revealed upregulation of genes encoding inflammatory chemokine ligands, proinflammatory cytokines, and growth factors, such as Ccl2, Il-11, and Hgf in the gastric mucosa of A4gnt(-/-) mice. Further supporting an important role for this O-glycan in cancer progression, we also observed significantly reduced αGlcNAc in human gastric adenocarcinoma and adenoma. Our results demonstrate that the absence of αGlcNAc triggers gastric tumorigenesis through inflammation-associated pathways in vivo. Thus, αGlcNAc-terminated gastric mucin plays dual roles in preventing gastric cancer by inhibiting H. pylori infection and also suppressing tumor-promoting inflammation.

Vibrio parahaemolyticus effector proteins suppress inflammasome activation by interfering with host autophagy signaling.

Bacterial pathogens utilize pore-forming toxins or sophisticated secretion systems to establish infection in hosts. Recognition of these toxins or secretion system by nucleotide-binding oligomerization domain leucine-rich repeat proteins (NLRs) triggers the assembly of inflammasomes, the multiprotein complexes necessary for caspase-1 activation and the maturation of inflammatory cytokines such as IL-1β or IL-18. Here we demonstrate that both the NLRP3 and NLRC4 inflammasomes are activated by thermostable direct hemolysins (TDHs) and type III secretion system 1 (T3SS1) in response to V. parahaemolyticus infection. Furthermore, we identify T3SS1 secreted effector proteins, VopQ and VopS, which induce autophagy and the inactivation of Cdc42, respectively, to prevent mainly NLRC4 inflammasome activation. VopQ and VopS interfere with the assembly of specks in infected macrophages. These data suggest that bacterial effectors interfere with inflammasome activation and contribute to bacterial evasion from the host inflammatory responses.

Familial Mediterranean fever: genotype-phenotype correlations in Japanese patients.

AbstractFamilial Mediterranean fever (FMF) is an autoinflammatory disease caused by MEditerranean FeVer gene (MEFV) mutations. In Japan, patients with FMF have been previously reported, including a mild or incomplete form. Several factors are presumed to contribute to the variable penetrance and to the phenotypic variability of FMF. We conducted the current study to investigate the correlation of variable clinical presentations and MEFV genotypic distributions in Japanese FMF patients.We analyzed demographic, clinical, and genetic data for 311 FMF patients enrolled in the study. Clinically, we classified FMF into 2 phenotypes: 1) the “typical” form of FMF, and 2) the “atypical” form of FMF according to the Tel Hashomer criteria. Patients with the typical FMF phenotype had a higher frequency of febrile episodes, a shorter duration of febrile attacks, more frequent thoracic pain, abdominal pain, a family history of FMF, and MEFV exon 10 mutations. Conversely, patients with the atypical FMF phenotype had a lower frequency of fever episodes and more frequent arthritis in atypical distribution, myalgia, and MEFV exon 3 mutations. Multivariate analysis showed that the variable associated with typical FMF presentation was the presence of MEFV exon 10 mutations. Typical FMF phenotype frequencies were decreased in patients carrying 2 or a single low-penetrance mutations compared with those carrying 2 or a single high-penetrance mutations (M694I), with an opposite trend for the atypical FMF phenotype. In addition, patients having more than 2 MEFV mutations had a younger disease onset and a higher prevalence of thoracic pain than those carrying a single or no mutations. Thus, MEFV exon 10 mutations are associated with the more typical FMF phenotype. In contrast, more than half of the Japanese FMF patients without MEFV exon 10 mutations presented with an atypical FMF phenotype, indicating that Japanese FMF patients tend to be divided into 2 phenotypes by a variation of MEFV mutations.

Novel heterozygous C243Y A20/TNFAIP3 gene mutation is responsible for chronic inflammation in autosomal-dominant Behçet's disease

Objective Although Behçets disease (BD) is a chronic inflammatory disorder of uncertain aetiology, the existence of familial BD with autosomal-dominant traits suggests that a responsibility gene (or genes) exists. We investigated a Japanese family with a history of BD to search for pathogenic mutations underlying the biological mechanisms of BD. Methods 6 patients over 4 generations who had suffered from frequent oral ulcers, genital ulcers and erythaema nodosum-like lesions in the skin were assessed. Whole-exome sequencing was performed on genomic DNA, and cytokine production was determined from stimulated mononuclear cells. Inflammatory cytokine secretion and Nod2-mediated NF-κB activation were analysed using the transfected cells. Results By whole-exome sequencing, we identified a common heterozygous missense mutation in A20/TNFAIP3, a gene known to regulate NF-κB signalling, for which all affected family members carried a heterozygous C243Y mutation in the ovarian tumour domain. Mononuclear cells obtained from the proband and his mother produced large amounts of interleukin 1β, IL-6 and tumour necrosis factor α (TNF-a) on stimulation as compared with those from normal controls. Although inflammatory cytokine secretion was suppressed by wild-type transfected cells, it was suppressed to a much lesser extent by mutated C243Y A20/TNFAIP3-transfected cells. In addition, impaired suppression of Nod2-mediated NF-κB activation by C243Y A20/TNFAIP3 was observed. Conclusions A C243Y mutation in A20/TNFAIP3 was likely responsible for increased production of human inflammatory cytokines by reduced suppression of NF-κB activation, and may have accounted for the autosomal-dominant Mendelian mode of BD transmission in this family.

Familial Mediterranean fever is no longer a rare disease in Japan.

BackgroundThe aim of this study was to evaluate the clinical manifestations and prevalence of familial Mediterranean fever (FMF) in Japanese patients with unexplained fever and rheumatic manifestations.MethodsWe enrolled 601 patients with unexplained fever or suspected FMF throughout Japan between 2009 and 2015. Patients were divided into three groups according to Tel Hashomer criteria: sure FMF, probable FMF, and non-FMF patients, including definitive rheumatic diseases. Mutation detection in exons 1, 2, 3, and 10 of the FMF gene MEFV was performed by direct sequencing.ResultsA total of 192 patients (31.9xa0%) were diagnosed with FMF according to FMF diagnostic criteria. These could be divided into sure FMF (56.3xa0%, nu2009=u2009108) and probable FMF (43.7xa0%, nu2009=u200984) patients. Fever, abdominal symptoms, and thoracic symptoms were significantly more common in FMF than non-FMF patients. Among FMF patients, 26 (13.5xa0%) had concomitant rheumatic diseases. Most FMF patients (94.3xa0%, 181/192) carried at least one MEFV mutation. Allele frequencies of M694I (13.5xa0% vs 0xa0%) and E148Q (39.1xa0% vs 24.8xa0%) mutations were significantly higher in FMF compared with healthy subjects. Allele frequencies of common MEFV mutations in FMF patients were M694I (13.5xa0%), P369S (8.6xa0%), R408Q (8.1xa0%), G304R (2.9xa0%), R202Q (4.4xa0%), E148Q (39.1xa0%), L110P (11.7xa0%), and E84K (3.1xa0%). Patients with a sure FMF phenotype had a higher frequency of MEFV exon 10 mutation (M694I) and a lower frequency of MEFV exon 3 mutations (P369S, R408Q) compared with those with a probable FMF phenotype.ConclusionThe high prevalence of FMF in Japanese patients with unexplained fever was confirmed in the present study. FMF should be suspected in cases of unexplained fever or non-specific rheumatic manifestations, and mutational analysis of MEFV could be useful to predict the clinical phenotypes of FMF in Japan.

Serum Amyloid A Induces NLRP-3-Mediated IL-1β Secretion in Neutrophils

Background/Aims Serum amyloid A (SAA) is an acute phase reactant with significant immunological activities, including effects on cytokine synthesis and neutrophil chemotaxis. Neutrophils can also release cytokines with proinflammatory properties. IL-1β is a key proinflammatory cytokine, the secretion of which is controlled by inflammasome. We investigated the proinflammatory effects of SAA in vitro in relation to the NLRP3 inflammasome in neutrophils. Methodology/Principal Findings Human neutrophils isolated form healthy subjects were stimulated with serum amyloid A (SAA). The cellular supernatants were analyzed by western blot using anti-IL-1β or anti-caspase-1 antibodies. IL-1β or Nod-like receptor family, pyrin domain containing 3 (NLRP3) mRNA expressions were analyzed by real-time PCR or reverse transcription-PCR (RT-PCR) method. SAA stimulation induced pro-IL-1β mRNA expression in neutrophils. Furthermore, SAA engaged the caspase-1-activating inflammasome, resulting in the production of active IL-1β. SAA-induced pro-IL-1β expression was marginally suppressed by the Syk specific inhibitor, R406, and SAA-induced pro-IL-1β processing in neutrophils was prevented by R406. Furthermore, SAA-induced NLRP3 mRNA expression was completely blocked by R406. Analysis of intracellular signaling revealed that SAA stimulation activated the tyrosine kinase Syk and mitogen-activated protein kinase (MAPK). Conclusions/Significance These results demonstrate that the innate neutrophil immune response against SAA involves a two-step activation process: an initial signal promoting expression of pro-IL-1β and a second signal involving Syk-dependent activation of the NLRP3 inflammasome and caspase-1, allowing processing of pro-IL-1β and secretion of mature IL-1β.