Biology subjects

Hirai, S.

Publications and source records attributed to Hirai, S..

9 recordsLinked to original sources

bioRxiv2026

Dual targeting of astrocytic and endothelial GLUT1 enables functional rescue in GLUT1 deficiency syndrome

Glucose transporter 1 deficiency syndrome (GLUT1-DS) is a severe neurometabolic disorder caused by impaired brain glucose transport. Because GLUT1 has been classically viewed as predominantly localized to blood-brain barrier endothelial cells, gene therapy strategies have largely focused on endothelial GLUT1 restoration. However, whether this endothelial-centered model fully explains disease pathogenesis and therapeutic rescue has remained unclear. Using enhanced detection in mouse brain and human postmortem tissue, we show that GLUT1 is broadly expressed in astrocytes as well as endothelial cells, extending beyond perivascular endfeet into astrocytic somata and processes. Conditional Glut1 haploinsufficiency in either astrocytes or endothelial cells reproduced GLUT1-DS-like reductions in cerebrospinal fluid glucose availability and brain parenchymal glucose responses, together with cognitive and motor impairments. To determine the therapeutic consequence of this revised cellular model, we used complementary endothelial- and astrocyte-directed AAV delivery to restore GLUT1 in systemic Glut1 haploinsufficient mice. Single-compartment restoration produced partial benefit, whereas dual-compartment restoration more robustly improved cerebrospinal fluid glucose availability and cognitive function. These findings indicate that endothelial GLUT1 restoration alone is insufficient for robust rescue and redefine GLUT1-DS as a multicellular disorder of the neurovascular unit.

neuroscience↗

bioRxiv2022

Pulmonary dust foci as rat pneumoconiosis lesion induced by titanium dioxide nanoparticles in 13-week inhalation study

BackgroundMost toxicological studies on titanium dioxide (TiO2) particles to date have concentrated on carcinogenicity and acute toxicity, with few studies focusing of pneumoconiosis, which is a variety of airspace and interstitial lung diseases caused by particle-laden macrophages. The present study examined rat pulmonary lesions associated with pneumoconiosis after inhalation exposure to TiO2 nanoparticles (NPs). MethodsMale and female F344 rats were exposed to 6.3, 12.5, 25, or 50 mg/m3 anatase type TiO2 NPs for 6 hours/day, 5 days/week for 13 weeks using a whole-body inhalation exposure system. After the last exposure the rats were euthanized and blood, bronchoalveolar lavage fluid, and all tissues including lungs and mediastinal lymph nodes were collected and subjected to biological and histopathological analyses. ResultsNumerous milky white spots were present in the lungs after exposure 25 and 50 mg/m3 TiO2 NPs. Histopathological analysis revealed that the spots were alveolar lesions, characterized predominantly by the agglomeration of particle-laden macrophages and the presence of reactive alveolar epithelial type 2 cell (AEC2) hyperplasia. We defined this characteristic lesion as pulmonary dust foci (PDF). The PDF is an inflammatory niche, with decreased vascular endothelial cells in the interstitium, and proliferating AEC2 transformed into alveolar epithelial progenitor cells. The AEC2 in the PDF had acquired DNA damage. Based on PDF induction, the lowest observed adverse effect concentration for pulmonary disorders in male and female rats in this study was 12.5 mg/m3 and 6.3 mg/m3, respectively. The no observed adverse effect concentration for male rats was 6.3 mg/m3. There was a sex difference in lung lesion development, with females showing more pronounced lesion parameters than males. ConclusionsInhalation exposure to TiO2 NPs caused PDF, an air-space lesion which is an alveolar inflammatory niche containing particle-laden macrophages and proliferating AEC2. This PDF histopathologically resembles some pneumoconiosis lesions (pulmonary siderosis and hard metal pneumoconiosis) in workers and lung disease in smokers, suggesting that it is an early pneumoconiosis lesion caused by exposure to TiO2 NPs in rats and a common alveolar reaction in mammals.

pathology↗

bioRxiv2021

Dose-response relationship of pulmonary disorders by inhalation exposure to cross-linked water-soluble acrylic acid polymers in F344 rats

BackgroundIn Japan, six workers handling cross-linked water-soluble acrylic acid polymer (CWAAP) at a chemical plant suffered from lung diseases, including fibrosis, interstitial pneumonia, emphysema, and pneumothorax. We recently demonstrated that inhalation of CWAAP-A, one type of CWAAP, causes pulmonary disorders in rats. It is important to investigate dose-response relationships and recoverability from exposure to CWAAPs for establishing occupational health guidelines, such as setting threshold limit value for CWAAPs in the workplace. MethodsMale and female F344 rats were exposed to 0.3, 1, 3, or 10 mg/m3 CWAAP-A for 6 hours/day, 5 days/week for 13 weeks using a whole-body inhalation exposure system. At 1 hour, 4 weeks, and 13 weeks after the last exposure the rats were euthanized and blood, bronchoalveolar lavage fluid, and all tissues including lungs and mediastinal lymph nodes were collected and subjected to biological and histopathological analyses. In a second experiment, male rats were pre-treated with clodronate liposome or polymorphonuclear leukocyte-neutralizing antibody to deplete macrophages or neutrophils, respectively, and exposed to CWAAP-A for 6 hours/day for 2 days. ResultsCWAAP-A exposure damaged only the alveoli. The lowest observed adverse effect concentration (LOAEC) was 1 mg/m3 and the no observed adverse effect concentration (NOAEC) was 0.3 mg/m3. Rats of both sexes were able to recover from the tissue damage caused by 13 weeks exposure to 1 mg/m3 CWAAP-A. In contrast, tissue damage caused by exposure to 3 and 10 mg/m3 was irreversible due to the development of interstitial lung lesions. There was a gender difference in the recovery from CWAAP-A induced pulmonary disorders, with females recovering less than males. Finally, acute lung effects caused by CWAAP-A were significantly reduced by depletion of alveolar macrophages. ConclusionsPulmonary damage caused by inhalation exposure to CWAAP-A was dose-dependent, specific to the lung and lymph nodes, and acute lung damage was ameliorated by depleting macrophages in the lungs. CWAAP-A had both a LOAEC and a NOAEC, and tissue damage caused by exposure to 1 mg/m3 CWAAP-A was reversible: recovery in female rats was less than for males. These findings indicate that concentration limits for CWAAPs in the workplace can be determined.

pharmacology and toxicology↗

bioRxiv2021

Lack of pulmonary fibrogenicity and carcinogenicity of titanium dioxide nanoparticles in 26-week inhalation study in rasH2 mouse model

BackgroundWith the rapid development of alternative methods based on the spirit of animal welfare, the publications of animal studies evaluating endpoints such as cancer have been extremely reduced. There have been no systemic inhalation exposure studies of titanium dioxide nanoparticles (TiO2 NPs) using CByB6F1-Tg(HRAS)2Jic (rasH2) 26-week study mice model for detecting carcinogenicity. MethodsMale and female rasH2 mice were exposed to 2, 8 or 32 mg/m3 of TiO2 NPs for 6 hours/day, 5 days/week for 26 weeks using a whole-body inhalation exposure system, with reference to the Organization for Economic Co-operation and Development principles of Good Laboratory Practice. All tissues including lungs, and blood were collected and subjected to biological and histopathological analyses. Additionally, Ki67 positive index were evaluated in mice lung alveolar epithelial type 2 cell (AEC2). ResultsThis study established a stable method for generating and exposing TiO2 NPs aerosol, and clarified the dose-response relationship by TiO2 NPs inhalation to rasH2 mice. TiO2 NPs exposure induced deposition of particles in lungs and mediastinal lymph nodes in a dose-dependent manner in each exposure group. Additionally, alveolar inflammation was only observed in 32 mg/m3 exposure group in both the sexes. Exposure to TiO2 NPs, as well as other organs, did not increase the incidence of lung tumors in any group, and pulmonary fibrosis and pre-neoplastic lesions were not observed in all groups. Finally, the cell proliferative activity of AEC2 was examined, and it was not increased by exposure to TiO2 NPs. ConclusionsThis is the first report showing the lack of pulmonary fibrogenicity and carcinogenicity (no evidence of carcinogenic activity) of TiO2 NPs in 26-week inhalation study in rasH2 mice exposed up to 32 mg/m3, which is considered to be a high concentration. Macrophages undergoing phagocytosis due to TiO2 NPs exposure formed inflammatory foci in the alveolar regions of exposed mice but did not develop fibrosis or hyperplasia or tumors. Moreover, the cell proliferative ability of AEC2 in lesions was not increased. In addition, no carcinogenicity was observed for any organs other than the lungs in this study.

pharmacology and toxicology↗

bioRxiv2021

Pathological characteristics of pulmonary toxicity in F344 rats exposed by inhalation to cross-linked water-soluble acrylic acid polymers

BackgroundRecently in Japan, six workers at a chemical plant that manufactures resins developed interstitial lung diseases after being involved in loading and packing cross-linked water-soluble acrylic acid polymers (CWAAPs). Since CWAAPs are not on the list of occupational diseases, the present study examined the lung damage potential of two CWAAPs (CWAAP-A and CWAAP-B) in rats, investigated pathological mechanisms, and established a method to rapidly evaluate the harmfulness of CWAAPs. MethodsUsing a whole-body inhalation exposure system, male F344 rats were exposed once to 40 or 100 mg/m3 of CWAAP-A for 4 hours or to 15 or 40 mg/m3 of CWAAP-A for 4 hours per day once per week for 2 months (a total of 9 exposures). In a separate set of experiments, male F344 rats were administered 1 mg/kg CWAAP-A or CWAAP-B by intratracheal instillation once every two weeks for 2 months (a total of five doses). Lung tissues, mediastinal lymph nodes, and bronchoalveolar lavage fluid were collected and subjected to biological and histopathological analyses. ResultsA single 4-hour exposure to CWAAP caused alveolar injury, and repeated exposures resulted in regenerative changes in the alveolar epithelium with activation of TGF{beta} signaling. During the recovery period after the last exposure, some alveolar lesions were partially healed, but other lesions developed into alveolitis with fibrous thickening of the alveolar septum. Rats administered CWAAP-A by intratracheal instillation developed qualitatively similar pulmonary pathology as rats exposed to CWAAP-A by inhalation. At 2 weeks after intratracheal instillation, rats administered CWAAP-B appeared to have a slightly higher degree of lung lesions compared to rats administered CWAAP-A, however, there was no difference in these lesions of CWAAP-A and CWAAP-B in rats examined 18 weeks after administration of these materials. ConclusionsThe present study provides evidence of rat lung pathogenesis after inhalation exposure to CWAAP-A. This study also demonstrates that the lung pathology of rats exposed to CWAAP-A by systemic inhalation was qualitatively similar to that of rats administered CWAAP-A by intratracheal instillation. The use of intratracheal instillation as an adjunct to systemic inhalation is expected to significantly accelerate the risk assessment for a variety of CWAAPs.

pharmacology and toxicology↗

bioRxiv2021

Integrative analysis of scRNAs-seq and scATAC-seq revealed transit-amplifying thymic epithelial cells expressing autoimmune regulator

Medullary thymic epithelial cells (mTECs) are critical for self-tolerance induction in T cells via promiscuous expression of tissue-specific antigens (TSAs), which are controlled by transcriptional regulator AIRE. Whereas AIRE-expressing (Aire+) mTECs undergo constant turnover in the adult thymus, mechanisms underlying differentiation of postnatal mTECs remain to be discovered. Integrative analysis of single-cell assays for transposase accessible chromatin (scATAC-seq) and single-cell RNA sequencing (scRNA-seq) suggested the presence of proliferating mTECs with a specific chromatin structure, which express high levels of Aire and co-stimulatory molecules CD80 (Aire+CD80hi). Proliferating Aire+CD80hi mTECs detected by using Fucci technology express a minimal level of Aire-dependent TSAs and are converted into quiescent Aire+CD80hi mTECs expressing high levels of TSAs after a transit amplification. These data provide evidence for the existence of transit amplifying Aire+mTEC precursors during Aire+mTEC differentiation process of the postnatal thymus.

immunology↗

bioRxiv2021

Regulation of the cognitive aging process by the transcriptional repressor RP58

SummaryIn humans, cognitive and motor functions develop in association with maturation, followed by a decline in advancing age. In this study, we aimed to provide a method for extending healthy lifespan by preventing age-related phenomena. Therefore, we focused on RP58, a transcriptional repressor, whose expression is reduced during aging in the human cortex. In the Rp58 hetero-knockout (KO) mice, object location memory was impaired even at 4-5 months, while it was normal in the wild-type mice at 4-5 months but was impaired at 12-18 months. These results indicate an early onset of impaired spatial memory in the mutant mice. As the underlying mechanism, the Rp58 hetero-KO mice showed early onset of DNA damage accumulation and microglial activation in the dentate gyrus due to a DNA repair defect that is generally observed with aging. As another hallmark of aging, we focused on mitochondrial function and detected mitochondrial abnormalities in the Rp58 hetero-KO mice at 4-5 months. Notably, continuous treatments with minocycline, a neuroprotective and anti-inflammatory antibiotic, prevented the facilitation of age-related phenomena in the Rp58 hetero-KO mice. These results suggest the availability of the Rp58 hetero-KO mice as a novel mouse model of human-like early aging and provide a therapeutic strategy to prevent age-related phenomena using minocycline. HighlightO_LIRp58 hetero-KO mice exhibit early aging phenotypes including impairment of spatial cognition C_LIO_LIRp58 hetero-KO mice show early accumulation of DNA damage due to a defect in the DNA repair system C_LIO_LITreatment with minocycline prevented cognitive dysfunction observed in Rp58 hetero-KO mice C_LI

neuroscience↗

bioRxiv2020

Induction of Alzheimer's disease pathology by early-life stress

BackgroundAlzheimers disease (AD), a progressive neurodegenerative disorder, is a serious social problem. Recently, several early-life factors have been associated with an increased risk of a clinical diagnosis of AD. MethodsWe investigated the involvement of early-life stress in AD pathogenesis using heterozygous the amyloid precursor protein (APP) mutant mice (AppNL-G-F/wt) and wild-type (Appwt/wt) mice. Maternal separation was used as an animal paradigm for early-life stress. Object location and fear conditioning tests were performed to measure cognitive functions, in addition to biochemical tests. Immunohistochemical analyses were performed after the behavioral tests. ResultsWe found that maternal-separated Appwt/wt mice showed narrowing of vessels and decreased pericyte coverage of capillaries in prefrontal cortex, while maternal-separated AppNL-G-F/wt mice additionally showed impairment of cognitive function, and earlier formation of A{beta} plaques and disruption of the blood-brain barrier. Severe activation of microglia was detected in the maternal-separated AppNL-G-F/wt mice and maternal-separated Appwt/wt mice. At the early stage, morphological changes and inflammatory responses were observed in the microglia of the maternal-separated AppNL-G-F/wt mice and maternal-separated Appwt/wt mice, as well as morphological changes in the microglia of the non-maternal-separated AppNL-G-F/wt mice. ConclusionsMicroglia activation induced by maternal separation in combination with the APP mutation may impairs the vascular system, leading to AD progression. These findings therefore suggest that maternal separation causes early induction of AD pathology via angiopathy.

neuroscience↗

bioRxiv2020

Angiopathy with impaired glucose logistics observed in schizophrenia-like model mice

Metabolic dysfunction is thought to contribute to the severity of psychiatric disorders; however, it has been unclear whether current high-simple-sugar diets contribute to pathogenesis of these diseases. Here we demonstrate that a high-sucrose diet during adolescence induces psychosis-related behavioral endophenotypes, including hyperactivity, poor working memory, impaired sensory gating, and disrupted interneuron function in mice deficient for glyoxalase-1 (Glo1), an enzyme involved in detoxification of sucrose metabolites. Further, the high-sucrose diet induced microcapillary impairments and reduced brain glucose uptake in brains of Glo1 deficient mice. Aspirin protected against this angiopathy, enhancing brain glucose uptake, and preventing abnormal behavioral phenotypes. Similar vascular damage to our model mice was found in the brains of randomly collected schizophrenia and bipolar disorder patients, suggesting that psychiatric disorders are associated with angiopathy in the brain caused by various environmental stresses, including metabolic stress.

neuroscience↗