Biology subjects

Miyake, S.

Publications and source records attributed to Miyake, S..

7 recordsLinked to original sources

bioRxiv2021

Longitudinal changes in diet cause repeatable and largely reversible shifts in gut microbial communities of laboratory mice and are observed across segments of the entire intestinal tract

Dietary changes are known to alter the composition of the gut microbiome. However, it is less understood how repeatable and reversible these changes are and how diet-switches affect the microbiota in the various segments of the gastrointestinal tract. Here, a treatment group of conventionally raised laboratory mice is subjected to two periods of western diet (WD) interrupted by a period of standard diet (SD) of the same duration. Beta-diversity analyses show that diet-induced microbiota changes are largely reversible (q = 0.1501; PERMANOVA, weighted-UniFrac comparison of the treatment-SD group to the control-SD group) and repeatable (q = 0.032; PERMANOVA, weighted-UniFrac comparison of both WD treatments). Furthermore, we report that diet switches alter the gut microbiota composition along the length of the intestinal tract in a segment-specific manner, leading to gut segment-specific Firmicutes/Bacteroidota ratios. We identified prevalent and distinct Amplicon Sequencing Variants (ASVs), particularly in genera of the recently described Muribaculaceae, along the gut as well as ASVs that are differentially abundant between segments of treatment and control groups. Overall, this study provides insights into the reversibility of diet-induced microbiota changes and highlights the importance to expand sampling efforts beyond the collections of fecal samples to characterize diet-dependent and segment-specific microbiome differences.

microbiology↗

bioRxiv2021

IL-6 blockade suppresses the blood-brain barrier disorder, leading to prevention of onset of NMOSD

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune astrocytopathy caused by antibodies against the aquaporin 4(AQP4) in end-feet of astrocytes. Breakdown of the blood-brain barrier (BBB) allowing ingress of AQP4 antibodies into the central nervous system (CNS) plays a key role in NMOSD. Although IL-6 blockade therapies such as satralizumab are effective in NMOSD, the therapeutic mechanism of IL-6 blockade, especially with respect to BBB disruption, are not fully understood because of the lack of the human models that are specialized to evaluate the BBB function. We constructed new in vitro human BBB models for evaluating continued barrier function, leukocyte transmigration and intracerebral transferability of IgGs utilizing the newly established triple co-culture system. In vitro and vivo experiments revealed that NMO-IgG increased intracerebral transferability of satralizumab, and that satralizumab suppressed the NMO-IgG-induced transmigration of T cells and barrier dysfunction. These results suggest that satralizumab, which can pass through the BBB in the presence of NMO-IgG, suppresses the barrier dysfunction and the disrupting controlled cellular infiltration at the BBB, leading to prevention of onset of NMOSD. One sentence summarySatralizumab and IL-6 blockade prevent lymphocyte migration and barrier dysfunction induced by NMO-IgG in EAE and novel triple co-culture BBB models.

immunology↗

bioRxiv2020

Host-age prediction from fecal microbiome composition in laboratory mice

The life-long relationship between microorganisms and hosts has a profound impact on the overall health and physiology of the holobiont. Changes in microbiome composition throughout the lifespan of a host remain, however, largely understudied. In this study, the fecal microbiome of conventionally raised C57BL/6J mice was analyzed throughout almost the entire expected lifespan, from maturing (9 weeks) until very old age (112 weeks). Analysis of alpha and beta diversity suggests that gradual microbiome changes occur throughout the entire murine life but appear to be more pronounced in maturing to middle-aged phases. Phylum-level analysis indicates a shift in the Firmicutes/Bacteroidetes ratio in favor of the Firmicutes in the second year of adulthood. Varying successional patterns throughout life were observed for many Firmicutes OTUs, while relative abundances of Bacteroidetes OTUs varied primarily in the early life phases. Microbiome configurations at given time points were used as training sets in a Bayesian model, which in turn effectively enabled the prediction of host age. The fecal microbiome composition may therefore serve as an accurate biomarker for aging. This study further suggests that age-associated compositional differences may have considerable implications for the interpretation and comparability of animal model-based microbiome studies. ImportanceThe life-long relationship between microorganisms and hosts has a profound impact on the overall physiology of the holobiont. Understanding the extent of gut microbiome compositional changes over the expected mouse lifespan may allow to better understand the interplay of microbiome and the host at the different life stages. In this study, we performed a two-year longitudinal study of murine fecal microbiome. Using fine-scale microbiome profiling we were able to predict the host age from the fecal microbiome composition. Moreover, we observed that the rate of compositional change appears to slow with age. The description of the compositional changes in commonly used C57BL/6J mice can be used to optimize selection of age-associated mouse models and highlights the use of microbiome-profiling as biomarker for aging.

microbiology↗

bioRxiv2020

Intermitochondrial signaling regulates the uniform distribution of stationary mitochondria in axons

In the central nervous system, many neurons develop axonal arbors that are crucial for information processing. Previous studies have demonstrated that premature axons contain motile and stationary mitochondria, and their balance is important for axonal arborization. However, the mechanisms by which neurons determine the positions of stationary mitochondria as well as their turnover remain to be elucidated. In this study, we investigated the regulation of spatiotemporal group dynamics of stationary mitochondria. We observed that the distribution of stationary mitochondrial spots along the unmyelinated and nonsynaptic axons is not random but rather relatively uniform both in vitro and in vivo. Intriguingly, whereas the positions of each mitochondrial spot changed over time, the overall distribution remained uniform. In addition, local inactivation of mitochondria inhibited the translocation of mitochondrial spots in adjacent axonal regions, suggesting that functional mitochondria enhance the motility of neighboring mitochondria. Furthermore, we showed that the ATP concentration was relatively high around mitochondria, and treating axons with phosphocreatine, which supplies ATP, reduced the immobile mitochondria induced by local mitochondrial inhibition. These observations indicate that intermitochondrial interactions, mediated by ATP signaling, control the uniform distribution of axonal mitochondria. The present study reveals a novel cellular system that collectively regulates stationary mitochondria in axons.

neuroscience↗

bioRxiv2019

Missense mutations in the MLKL brace region lead to lethal neonatal inflammation in mice and are present in high frequency in humans.

We have isolated a mouse strain with a single missense mutation in the gene encoding MLKL, the essential effector of necroptotic cell death. The resulting substitution lies within the two-helix brace and confers constitutive, RIPK3 independent, killing activity to MLKL. Mice homozygous for MlklD139V develop lethal inflammation within days of birth, implicating the salivary glands and pericardium as hotspots for necroptosis and inflammatory infiltration. The normal development of MlklD139V homozygotes until birth, and the absence of any overt phenotype in heterozygotes provides important in vivo precedent for the capacity of cells to clear activated MLKL. These observations offer an important insight into the potential disease-modulating roles of three common human MLKL polymorphisms that encode amino acid substitutions within or adjacent to the brace region. Compound heterozygosity of these variants is found at up to 12-fold the expected frequency in patients that suffer from a pediatric autoinflammatory disease, CRMO.

cell biology↗

bioRxiv2018

Description of Schaedlerella arabinophila gen. nov., sp. nov., a D-arabinose utilizing bacterium isolated from feces of C57BL/6J mice and a close relative of Clostridium sp. ASF 502

The use of gnotobiotics has gained large interest in recent years due to technological advances that have revealed the importance of host-associated microbiomes for host physiology and health. One of the oldest and most important gnotobiotics mouse model, the Altered Schaedler Flora (ASF) has been used for several decades. ASF comprises eight different bacterial species, which have been characterized to different extent, but only few are available through public strain collections. Here, the isolation of a close relative to one of the less studied ASF strains, Clostridium sp. ASF 502, is reported. Isolate TLL-A1, which shares 99.6% 16S rRNA gene sequence identity with Clostridium sp. ASF 502, was obtained from feces of C57BL/6J mice where is was detectable at a relative abundance of less than one percent. D-arabinose was used as sole carbon source in the anaerobic cultivation medium. Growth experiments with TLL-A1 on different carbon sources and analysis of its ~6.5 gigabase genome indicate that TLL-A1 harbors a large gene repertoire to utilize different carbohydrates for growth. Comparative genome analyses of TLL-A1 and Clostridium sp. ASF 502 reveal differences in genome content between the two strains, in particular with regards to carbohydrate activating enzymes. Based on physiology and genomic analysis it is proposed to name TLL-A1 to gen. nov. sp. nov Schaedlerella arabinophila TLL-A1 (DSMZ 106076T; KCTC 15657T). The closely related Clostridium sp. ASF 502 is proposed to be renamed to Schaedlerella arabinophila to reflect its taxonomic standing and to keep ASF 502 as strain designation.\n\nImportanceThe Altered Schaedler Flora (ASF) remains an important tool to mechanistically investigate host-microbe interactions in the mammalian alimentary tract. Extensively characterizing the eight different bacterial strains, which are constituting ASF, has the potential to further increase the definition of this widely used model microbial community and to enhance our understanding of how individual microorganism interact with a host and/or how they may affect its physiology. However, some of the ASF strains have unfortunately been lost or are not easily accessible to the scientific community. The isolation and characterization of the here described species, proposed to be named Schaedlerella arabinophila, which is closely related to Clostridium species ASF502, may therefore be an important corner stone in further improving the value of studies using ASF or other defined synthetic microbial communities that require usage of autochthonous microorganisms in gnotobiotic mice.

microbiology↗

bioRxiv2018

Insights into the microbiota of Asian seabass (Lates calcarifer) with tenacibaculosis symptoms and description of sp. nov. Tenacibaculum singaporense

Outbreaks of diseases in farmed fish remain a recurring problem despite the development of vaccines and improved hygiene standards on aquaculture farms. One commonly observed bacterial disease in tropical aquaculture of the South-East Asian region is tenacibaculosis, which is attributed to members of the Bacteroidetes genus Tenacibaculum, most notably T. maritimum. The impact of tenacibaculosis on fish microbiota remains poorly understood. In this study, we analysed the microbiota of different tissue types of commercially reared Asian seabass (Lates calcarifer) that showed symptoms of tenacibaculosis and compared the microbial communities to those of healthy and experimentally infected fish that were exposed to diseased farm fish. The microbiota of diseased farm fish was dominated by Proteobacteria (relative abundance{+/-}standard deviation, 74.5%{+/-}22.8%) and Bacteroidetes (18.07%{+/-}21.7%), the latter mainly comprised by a high abundance of Tenacibaculum species (17.6%{+/-}20.7%). In healthy seabass Proteobacteria had also highest relative abundance (48.04%{+/-}0.02%), but Firmicutes (34.2%{+/-}0.02%) and Fusobacteria (12.0%{+/-}0.03%) were the next two major constituents. Experimentally infected fish developed lesions characteristic for tenacibaculosis, but the microbiota was primarily dominated by Proteobacteria (90.4%{+/-}0.2%) and Firmicutes (6.2%{+/-}0.1%). The relative abundance of Tenacibaculum species in experimentally infected fish was significantly lower than in the commercially reared diseased fish and revealed a higher prevalence of different Tenacibaculum species. One strain was isolated and is described here as sp. nov. Tenacibaculum singaporense TLL-A1T (=DSM 106434T, KCTC 62393T). The genome of T. singaporense was sequenced and compared to those of T. maritimum DSM 17995T and the newly sequenced T. mesophilum DSM 13764T.\n\nImportanceFish production from aquaculture facility has become a major source of protein for human consumption and is expected to further grow to meet the growing demands. Devastating fish diseases, such as tenacibaculosis, can eradicate entire stocks of aquaculture fish in a short time and pose a serious threat to individual fish farmers and overall fish production. Understanding the disease processes and the individual microbial players involved has the potential to develop methods to prevent or mitigate infections on aquaculture farms. This study provides important insights into the microbial ecology of tenacibaculosis from an aquaculture facility in Singapore and highlights the complexity of this fish disease at two different disease stages. Furthermore, the isolation of a novel Tenacibaculum species and comparative genome analysis of three different Tenacibaculum species enhance our view of this economically and environmentally important bacterial genus.

microbiology↗