Daisuke Hasegawa

Abnormally High Levels of Virus-Infected IFN-γ+CCR4+CD4+CD25+ T Cells in a Retrovirus-Associated Neuroinflammatory Disorder

Background Human T-lymphotropic virus type 1 (HTLV-1) is a human retrovirus associated with both HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), which is a chronic neuroinflammatory disease, and adult T-cell leukemia (ATL). The pathogenesis of HAM/TSP is known to be as follows: HTLV-1-infected T cells trigger a hyperimmune response leading to neuroinflammation. However, the HTLV-1-infected T cell subset that plays a major role in the accelerated immune response has not yet been identified. Principal Findings Here, we demonstrate that CD4+CD25+CCR4+ T cells are the predominant viral reservoir, and their levels are increased in HAM/TSP patients. While CCR4 is known to be selectively expressed on T helper type 2 (Th2), Th17, and regulatory T (Treg) cells in healthy individuals, we demonstrate that IFN-γ production is extraordinarily increased and IL-4, IL-10, IL-17, and Foxp3 expression is decreased in the CD4+CD25+CCR4+ T cells of HAM/TSP patients as compared to those in healthy individuals, and the alteration in function is specific to this cell subtype. Notably, the frequency of IFN-γ-producing CD4+CD25+CCR4+Foxp3− T cells is dramatically increased in HAM/TSP patients, and this was found to be correlated with disease activity and severity. Conclusions We have defined a unique T cell subset—IFN-γ+CCR4+CD4+CD25+ T cells—that is abnormally increased and functionally altered in this retrovirus-associated inflammatory disorder of the central nervous system.

Severe loss of invariant NKT cells exhibiting anti-HTLV-1 activity in patients with HTLV-1-associated disorders.

Invariant natural killer T (iNKT) cells are unique T cells that regulate the immune response to microbes, cancers, and autoimmunity. We assessed the characteristics of iNKT cells from persons infected with human T-lymphotropic virus type 1 (HTLV-1). Whereas most infected persons remain asymptomatic carriers (ACs) throughout their lives, a small proportion, usually with high equilibrium proviral loads,develop 2 diseases: HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia (ATL). We demonstrated that the frequency of iNKT, NK, and dendritic cells in the peripheral blood of HAM/TSP and ATL patients is decreased. We also observed an inverse correlation between the iNKT cell frequency and the HTLV-1 proviral load in the peripheral blood of infected persons. Notably, in vitro stimulation of peripheral blood cells with alpha-galactosylceramide led to an increase in the iNKT cell number and a subsequent decrease in the HTLV-1-infected T-cell number in samples from ACs but not HAM/TSP or ATL patients. Our results suggest that iNKT cells contribute to the immune defense against HTLV-1, and iNKT-cell depletion plays an important role in the pathogenesis of HAM/TSP and ATL. Therefore, iNKT cell-based immunotherapy may be an effective strategy for preventing these HTLV-1-associated disorders.

Fucoidan therapy decreases the proviral load in patients with human T-lymphotropic virus type-1-associated neurological disease.

BACKGROUNDnHuman T-lymphotropic virus type-1 (HTLV-1) is a human retrovirus that causes HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukaemia (ATL). A higher viral load in individuals with HTLV-1 infection increases their risk of developing HAM/TSP and ATL. Moreover, the high proviral load is associated with the clinical progression of HAM/TSP. Reduction of the number of HTLV-1-infected cells is therefore crucial for preventing and treating HTLV-1-associated diseases. Recently, fucoidan, a complex sulphated polysaccharide derived from marine seaweed, has been demonstrated to exert inhibitory effects on HTLV-1 infection in vitro. In this study, we examined the in vivo effects of fucoidan on HTLV-1 infection.nnnMETHODSnIn this single-centre open-label trial, 13 patients with HAM/TSP were treated with 6 g fucoidan daily for 6-13 months. The HTLV-1 proviral DNA load and frequencies of HTLV-1-specific CD8(+) T-cells, natural killer cells, invariant natural killer T-cells and dendritic cells in the peripheral blood were analysed. Furthermore, the in vitro inhibitory effect of fucoidan on cell-to-cell HTLV-1 infection was examined by using luciferase reporter cell assays.nnnRESULTSnFucoidan inhibited the cell-to-cell transmission of HTLV-1 in vitro. Furthermore, fucoidan therapy resulted in a 42.4% decrease in the HTLV-1 proviral load without affecting the host immune cells. During the treatment, no exacerbation was observed. Four patients with HAM/TSP developed diarrhoea, which improved immediately after stopping fucoidan administration.nnnCONCLUSIONSnFucoidan is a new potential therapeutic agent for the prevention and treatment of HTLV-1-associated diseases.

The E3 ligase synoviolin controls body weight and mitochondrial biogenesis through negative regulation of PGC‐1β

Obesity is a major global public health problem, and understanding its pathogenesis is critical for identifying a cure. In this study, a gene knockout strategy was used in post‐neonatal mice to delete synoviolin (Syvn)1/Hrd1/Der3, an ER‐resident E3 ubiquitin ligase with known roles in homeostasis maintenance. Syvn1 deficiency resulted in weight loss and lower accumulation of white adipose tissue in otherwise wild‐type animals as well as in genetically obese (ob/ob and db/db) and adipose tissue‐specific knockout mice as compared to control animals. SYVN1 interacted with and ubiquitinated the thermogenic coactivator peroxisome proliferator‐activated receptor coactivator (PGC)‐1β, and Syvn1 mutants showed upregulation of PGC‐1β target genes and increase in mitochondrion number, respiration, and basal energy expenditure in adipose tissue relative to control animals. Moreover, the selective SYVN1 inhibitor LS‐102 abolished the negative regulation of PGC‐1β by SYVN1 and prevented weight gain in mice. Thus, SYVN1 is a novel post‐translational regulator of PGC‐1β and a potential therapeutic target in obesity treatment.

E3 ubiquitin ligase synoviolin is involved in liver fibrogenesis.

Background and Aim Chronic hepatic damage leads to liver fibrosis, which is characterized by the accumulation of collagen-rich extracellular matrix. However, the mechanism by which E3 ubiquitin ligase is involved in collagen synthesis in liver fibrosis is incompletely understood. This study aimed to explore the involvement of the E3 ubiquitin ligase synoviolin (Syno) in liver fibrosis. Methods The expression and localization of synoviolin in the liver were analyzed in CCl4-induced hepatic injury models and human cirrhosis tissues. The degree of liver fibrosis and the number of activated hepatic stellate cells (HSCs) was compared between wild type (wt) and Syno+/− mice in the chronic hepatic injury model. We compared the ratio of apoptosis in activated HSCs between wt and Syno+/− mice. We also analyzed the effect of synoviolin on collagen synthesis in the cell line from HSCs (LX-2) using siRNA-synoviolin and a mutant synoviolin in which E3 ligase activity was abolished. Furthermore, we compared collagen synthesis between wt and Syno−/− mice embryonic fibroblasts (MEF) using quantitative RT-PCR, western blotting, and collagen assay; then, we immunohistochemically analyzed the localization of collagen in Syno−/− MEF cells. Results In the hepatic injury model as well as in cirrhosis, synoviolin was upregulated in the activated HSCs, while Syno+/− mice developed significantly less liver fibrosis than in wt mice. The number of activated HSCs was decreased in Syno+/− mice, and some of these cells showed apoptosis. Furthermore, collagen expression in LX-2 cells was upregulated by synoviolin overexpression, while synoviolin knockdown led to reduced collagen expression. Moreover, in Syno−/− MEF cells, the amounts of intracellular and secreted mature collagen were significantly decreased, and procollagen was abnormally accumulated in the endoplasmic reticulum. Conclusion Our findings demonstrate the importance of the E3 ubiquitin ligase synoviolin in liver fibrosis.

The XBP1 Arm of the Unfolded Protein Response Induces Fibrogenic Activity in Hepatic Stellate Cells Through Autophagy

Autophagy and the unfolded protein response (UPR) both promote activation of hepatic stellate cells (HSC), however the link between the two stimuli remains unclear. Here we have explored the role of X-box binding protein 1 (XBP1), one of three UPR effector pathways and sought to establish the interdependence between autophagy and the UPR during HSC activation. XBP1 induction accompanied both culture-based HSC activation and ER stress induced by tunicamycin. Ectopic overexpression of XBP1 induced collagen 1-alpha expression in HSCs, which was inhibited by knockdown of ATG7, a critical autophagy mediator. Genome-wide transcriptomic profiling indicated an upregulation of collagen synthesis pathways, but not of the transforming growth factor (TGF)-b pathway, a canonical fibrogenic driver, suggesting that XBP1 activates a specific subset of fibrogenesis pathways independent of TGF-β1. XBP1 target gene signatures were significantly induced in rodent liver fibrosis models (nu2009=u20093–5) and in human samples of non-alcoholic fatty liver disease (NAFLD) (nu2009=u200972–135). Thus, XBP1-mediated UPR contributes to fibrogenic HSC activation and is functionally linked to cellular autophagy.

Activation of synoviolin promoter in rheumatoid synovial cells by a novel transcription complex of interleukin enhancer binding factor 3 and GA binding protein α

OBJECTIVEnSynoviolin is an E3 ubiquitin ligase, and its overexpression is implicated in the pathogenesis of rheumatoid arthritis (RA). We reported previously that Ets binding site 1 (EBS-1) within the synoviolin promoter is crucial for the expression of synoviolin, and GA binding protein (GABP) binds to this site. This study was undertaken to elucidate the precise mechanisms of transcriptional regulation via EBS-1.nnnMETHODSnWe performed purification and identification of complex components that bind to EBS-1 and inspected their contributions to the transcriptional regulation of synoviolin in rheumatoid synovial cells. We biochemically purified proteins that had EBS-1 binding activity and identified the proteins using liquid chromatography tandem mass spectrometry analysis. The identified proteins were verified to recruit and form the complex on EBS-1 using electrophoretic mobility shift assay and coimmunoprecipitation assay. Furthermore, their transcription activities were tested by reporter assays and RNA interference experiments.nnnRESULTSnWe identified interleukin enhancer binding factor 3 (ILF-3) as a novel factor in the complex. ILF-3 was demonstrated to activate the synoviolin promoter via association with GABPalpha in rheumatoid synovial cells. In addition, further activation was observed with ILF-2 and GABPbeta, previously reported interactants of ILF-3 and GABPalpha, respectively. Moreover, ILF-3-knockdown experiments showed reduced expression of the synoviolin gene.nnnCONCLUSIONnOur findings indicate that ILF-3, which has been known to regulate IL-2 expression in T cells, up-regulates synoviolin expression with GABPalpha in rheumatoid synovial cells. ILF-3 might be a target for RA treatment through its effect on IL-2 in T cells and synoviolin in rheumatoid synovial cells.

Increased prevalence of group A β-hemolytic streptococcus among an ethnic population in Kyrgyzstan detected by the rapid antigen detection test

The incidence of rheumatic fever (RF) has markedly increased in the last 10 years in Kyrgyzstan. Therefore, investigating the prevalence of group A β-hemolytic streptococcus (GABHS), which is the cause of RF, in the Kyrgyzstan population is crucial. We studied 189 subjects: 59 children [29 with RF and/or rheumatic heart disease (RHD)] and 130 adults (15 with RHD). The average age of the subjects was 41.0±10.0 years (range 8 months to 72 years). A general clinical examination and medical history including eating habits was carried out. The prevalence of GABHS was tested using the highly sensitive rapid antigen detection test (RADT) to detect the outcrop of streptococcus antigen in smears taken from the mucosal surface of the tonsils or the back of the throat. GABHS antigen was positive in 70 of a total 189 subjects [37.0%; 22/59 children (37.2%), 48/130 adults (36.9%)]. In patients with RF/RHD (n=44), GABHS was positive in 14 subjects [31.8%; 8/29 children (27.6%), 6/15 adults (40.0%)]. Thirty-two subjects with RF/RHD had frequent episodes of tonsillopharyngitis. In subjects without RF/RHD (n=145), GABHS was positive in 56 subjects [38.6%; 14/30 children (46.6%), 42/115 adults (36.5%)]. Thirty of these subjects had frequent episodes of tonsillopharyngitis. Of the 130 adults, the most-consumed dairy products included yoghurt (n=115; 88.4%), milk kasha (n=75; 57.7%) and milk (n=40; 30.7%). Of the 115 subjects in the yoghurt-consuming group, 44 (38.2%) had positive results for GABHS. In the non-yoghurt-consuming group, 4/15 subjects (26.6%) had positive results for GABHS. Using RADT for GABHS, a high prevalence of GABHS antigen was detected not only in patients with RF/RHD, but also in the healthy population (without RF/RHD). The low GABHS prevalence in children with RF/RHD (27.6%) was probably due to corresponding antibiotic therapy. In conclusion, the high prevalence of GABHS is one of the main reasons for the rapid increase in RF/RHD in Kyrgyzstan, and RADT would be an effective tool for its detection.

Mitochondrial ubiquitin ligase activator of NF-κB regulates NF-κB signaling in cells subjected to ER stress.

The nuclear factor-κB (NF-κB) transcription factor family members control various biological processes, such as apoptosis and proliferation. The endoplasmic reticulumxa0(ER) has emerged as a major site of cellular homeostasis regulation. The accumulation of misfolded protein in the ER causes stress and ER stress-induced NF-κB activation to protect cells from apoptosis. In this study, we found a putative ER stress-response elementxa0(ERSE) on the promoter of mitochondrial ubiquitin ligase activator of NF-κBxa0(MULAN), and that MULAN expression was upregulated by ER stress. MULAN specifically activated NF-κB dependent gene expression in an E3xa0ligase activity-dependent manner. The ectopic expression of MULAN induced the nuclear translocation of endogenous p65 and the degradation of IκB. Binding assay revealed that MULAN was associated with transforming growth factorxa0β-activated kinasexa0(TAK1). The knockdown of MULAN using siRNA inhibited the activation of NF-κB in the cells subjected to ER stress. The findings of our study indicate that MULAN is an E3xa0ligase that regulates NF-κB activation to protect cells from ER stress-induced apoptosis.

Proposal of Classification Criteria for HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis Disease Activity

Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a rare chronic neuroinflammatory disease. While the disease usually progresses slowly without remission, there is a subgroup of patients with rapid progression and another subgroup with very slow progression. However, there have been no reports to date that have successfully determined the criteria to differentiate these subgroups. Therefore, we initially conducted a statistical modeling analysis to explore representative patterns of disease progression using data from our nationwide HAM/TSP patient registration system (“HAM-net”). The latent class mixed model analysis on the retrospective data (n = 205) of disease progression measured by the change in Osame Motor Disability Score from the onset of the disease to diagnosis demonstrated three representative progression patterns of HAM/TSP. Next, to test the effect of the progression rate at the initial phase of the disease on long-term prognosis, we divided 312 “HAM-net” registered patients into three groups (rapid, slow, and very slow progressors) based on the progression rate, then analyzed long-term functional prognosis of each group using the Kaplan–Meier method. Our data clearly demonstrated that the rapid progression at the early phase of the disease is an important poor prognostic factor. Moreover, to determine the biomarkers capable of discriminating the difference in disease activity, we compared the value of potential biomarkers of HAM/TSP among rapid (n = 15), slow (n = 74), very slow (n = 7), and controls (non-HAM/TSP patients, n = 18). The cerebrospinal fluid (CSF) levels of neopterin and C-X-C motif chemokine 10 (CXCL10) were the most valuable markers to discriminate among rapid, slow, and very slow progressors. To differentiate between rapid and slow progressors, the cut-off values of neopterin and CXCL10 were determined to be 44 pmol/mL and 4400 pg/mL, respectively. Furthermore, to differentiate between slow and very slow progressors, these values were determined to be 5.5 pmol/mL and 320 pg/mL, respectively. Notably, we found that CSF levels of these markers in very slow progressors were within the reference range. Thus, we propose a new classification criteria for disease activity of HAM/TSP that may contribute to improving the treatment algorithm for HAM/TSP.