Tadashi Nakamura

Association of human leukocyte antigen with interstitial lung disease in rheumatoid arthritis: a protective role for shared epitope.

Introduction Interstitial Lung Disease (ILD) is frequently associated with Rheumatoid Arthritis (RA) as one of extra-articular manifestations. Many studies for Human Leukocyte Antigen (HLA) allelic association with RA have been reported, but few have been validated in an RA subpopulation with ILD. In this study, we investigated the association of HLA class II alleles with ILD in RA. Methods An association study was conducted on HLA-DRB1, DQB1, and DPB1 in 450 Japanese RA patients that were or were not diagnosed with ILD, based on the findings of computed tomography images of the chest. Results Unexpectedly, HLA-DRB1*04 (corrected P [Pc]u200a=u200a0.0054, odds ratio [OR] 0.57), shared epitope (SE) (Pu200a=u200a0.0055, OR 0.66) and DQB1*04 (Pcu200a=u200a0.0036, OR 0.57) were associated with significantly decreased risk of ILD. In contrast, DRB1*16 (Pcu200a=u200a0.0372, OR 15.21), DR2 serological group (DRB1*15 and *16 alleles) (Pu200a=u200a0.0020, OR 1.75) and DQB1*06 (Pcu200a=u200a0.0333, OR 1.57, respectively) were significantly associated with risk of ILD. Conclusion HLA-DRB1 SE was associated with reduced, while DR2 serological group (DRB1*15 and *16) with increased, risk for ILD in Japanese patients with RA.

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.

Protective effect of the HLA-DRB1*13:02 allele in Japanese rheumatoid arthritis patients.

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease. Certain HLA-DRB1 “shared-epitope” alleles are reported to be positively associated with increased RA susceptibility, whereas some of the other alleles may be negatively associated. However, studies on the latter are rare. Here, we focus on the protective effects of DRB1 alleles in Japanese RA patients in an association study. Relative predispositional effects (RPE) were analyzed by sequential elimination of carriers of each allele with the strongest association. The protective effects of DRB1 alleles were investigated in patients stratified according to whether they possessed anti-citrullinated peptide antibodies (ACPA). The DRB1*13:02 allele was found to be negatively associated with RA (Pu200a=u200a4.59×10−10, corrected P (Pc)u200a=u200a1.42×10−8, odds ratio [OR] 0.42, 95% CI 0.32–0.55, P [RPE]u200a=u200a1.27×10−6); the genotypes DRB1*04:05/*13:02 and *09:01/*13:02 were also negatively associated with RA. The protective effect of *13:02 was also present in ACPA-positive patients (Pu200a=u200a3.95×10−8, Pcu200a=u200a1.22×10−6, OR 0.42, 95%CI 0.31–0.58) whereas *15:02 was negatively associated only with ACPA-negative RA (Pu200a=u200a8.87×10−5, Pcu200a=u200a0.0026, OR 0.26, 95%CI 0.12–0.56). Thus, this study identified a negative association of DRB1*13:02 with Japanese RA; our findings support the protective role of DRB1*13:02 in the pathogenesis of ACPA-positive RA.

Identification of a novel hypocholesterolemic protein, major royal jelly protein 1, derived from royal jelly.

Royal jelly (RJ) intake lowers serum cholesterol levels in animals and humans, but the active component in RJ that lowers serum cholesterol level and its molecular mechanism are unclear. In this study, we set out to identify the bile acid-binding protein contained in RJ, because dietary bile acid-binding proteins including soybean protein and its peptide are effective in ameliorating hypercholesterolemia. Using a cholic acid-conjugated column, we separated some bile acid-binding proteins from RJ and identified the major RJ protein 1 (MRJP1), MRJP2, and MRJP3 as novel bile acid-binding proteins from RJ, based on matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Purified MRJP1, which is the most abundant protein of the bile acid-binding proteins in RJ, exhibited taurocholate-binding activity in vitro. The micellar solubility of cholesterol was significantly decreased in the presence of MRJP1 compared with casein in vitro. Liver bile acids levels were significantly increased, and cholesterol 7α-hydroxylase (CYP7A1) mRNA and protein tended to increase by MRJP1 feeding compared with the control. CYP7A1 mRNA and protein levels were significantly increased by MRJP1 tryptic hydrolysate treatment compared with that of casein tryptic hydrolysate in hepatocytes. MRJP1 hypocholesterolemic effect has been investigated in rats. The cholesterol-lowering action induced by MRJP1 occurs because MRJP1 interacts with bile acids induces a significant increase in fecal bile acids excretion and a tendency to increase in fecal cholesterol excretion and also enhances the hepatic cholesterol catabolism. We have identified, for the first time, a novel hypocholesterolemic protein, MRJP1, in RJ. Interestingly, MRJP1 exhibits greater hypocholesterolemic activity than the medicine β-sitosterol in rats.

Effects of Janus kinase inhibitor tofacitinib on circulating serum amyloid A and interleukin‐6 during treatment for rheumatoid arthritis

The Janus kinase inhibitor tofacitinib is currently being investigated as a disease‐modifying agent in rheumatoid arthritis (RA). We investigated the in‐vivo effects of tofacitinib treatment for 4 weeks on elevated circulating acute‐phase serum amyloid (SAA) levels in 14 Japanese patients with RA. SAA levels fell from 110·5u2009±u2009118·5u2009μg/ml (meanu2009±u2009standard deviation) at treatment initiation to 15·3u2009±u200913·3u2009μg/ml after 4 weeks treatment with tofacitinib. The reduction in SAA levels was greater in patients receiving tofacitinib plus methotrexate compared with those receiving tofacitinib monotherapy. Tofacitinib was also associated with reduced serum interleukin (IL)‐6, but had no effect on serum levels of soluble IL‐6 receptor. Patients were divided into groups with adequate (normalization) and inadequate SAA responses (without normalization). Serum IL‐6 levels were reduced more in the group with adequate SAA response compared with those with inadequate SAA response. These results suggest that tofacitinib down‐regulates the proinflammatory cytokine, IL‐6, accompanied by reduced serum SAA levels in patients with active RA. The ability to regulate elevated serum IL‐6 and SAA levels may explain the anti‐inflammatory activity of tofacitinib.

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 triggers the mosodium urate -mediated mature interleukin-1β production from human synovial fibroblasts

BackgroundMonosodium urate (MSU) has been shown to promote inflammasome activation and interleukin-1β (IL-1β) secretion in monocyte/macrophages, but the cellular pathway and nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation in synovial tissues, remain elusive. In this study, we investigated the effects of MSU on synovial fibroblasts to elucidate the process of MSU-mediated synovial inflammation.MethodsHuman synovial fibroblasts were stimulated with MSU in the presence or absence of serum amyloid A (SAA). The cellular supernatants were analyzed by immunoblotting using anti-IL-1β or anti-caspase-1 antibodies. IL-1β or NLRP3 mRNA expressions were analyzed by real-time PCR or reverse transcription-PCR (RT-PCR) method.ResultsNeither SAA nor MSU stimulation resulted in IL-1β or interleukin-1α (IL-1α) secretions and pro-IL-1β processing in synovial fibroblasts. However, in SAA-primed synovial fibroblasts, MSU stimulation resulted in the activation of caspase-1 and production of active IL-1β and IL-1α. The effect of SAA on IL-1β induction was impaired in cells by silencing NLRP3 using siRNA or treating with caspase-1 inhibitor. In addition, SAA induced the secretion of cathepsin B and NLRP3 mRNA expression in synovial fibroblasts.ConclusionsOur data demonstrate that exposure of human synovial fibroblasts to SAA promotes MSU-mediated caspase-1 activation and IL-1β secretion in the absence of microbial stimulation. These findings provide insight into the molecular processes underlying the synovial inflammatory condition of gout.

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.

HLA-DRB1 Alleles and Rheumatoid Arthritis-related Pulmonary Fibrosis

To the Editor: nnPulmonary fibrosis is a well recognized extraarticular manifestation of rheumatoid arthritis (RA)1. Several studies have shown an association between the HLA-DRB1 gene and extraarticular manifestations of RA2,3. We analyzed the effect of the HLA-DRB1 gene and cytokine gene polymorphisms on the association of pulmonary fibrosis in Japanese patients with RA.nnWe examined 131 adult patients with RA, who fulfilled the American Rheumatism Association 1987 revised criteria for RA4. Clinical characteristics were (mean ± SD) age at study 62.4 ± 13.0 years and disease duration 11.2 ± 4.7 years. Pulmonary fibrosis was diagnosed by chest radiograph and chest high-resolution computed tomography (HRCT). Patients with dry cough or exertional dyspnea or suspicious findings for interstitial changes in chest radiography were further investigated with HRCT at suspended end-inspiratory effort without intravenous contrast material. The abnormalities used to screen for pulmonary fibrosis were ground-glass attenuation and honeycombing defined as areas of cystic spaces with thickened walls. Patients with RA with other autoimmune … nnAddress correspondence to Dr. K. Migita, Clinical Research Center, NHO Nagasaki Medical Center, Kubara 2-1001-1, Omura 856-8652, Japan; E-mail: migita{at}nmc.hosp.go.jp

Combined treatment with cyclophosphamide and prednisolone is effective for secondary amyloidosis with SAA1γ/γ genotype in a patient with rheumatoid arthritis

Abstract A 41-year-old woman, who had been diagnosed with rheumatoid arthritis (RA), was admitted because of proteinuria, and rheumatoid and gastrointestinal symptoms just 1 year after onset. Renal biopsy revealed marked amyloid deposits of AA (amyloid A)-type. Genotyping of serum amyloid A (SAA) showed that she was homozygous for SAA1γ. Combined treatment with cyclophosphamide and prednisolone led to remission of both RA disease activity and proteinuria. Since the renal dysfunction arose from amyloidosis, arrested renal deterioration and a remission of proteinuria would result from a reduction of amyloid deposits. Therefore, early usage of immunosuppresive therapy such as a combined treatment with these two medicines would be useful against systemic amyloidosis secondary to RA, even if the patient has the risky SAA1γ/γ genotype.