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367 result(s) for "Masaaki Murakami"
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Intracellular zinc homeostasis and zinc signaling
Zinc (Zn) is an essential heavy metal that is incorporated into a number of human Zn metalloproteins. Zn plays important roles in nucleic acid metabolism, cell replication, and tissue repair and growth. Zn deficiency is associated with a range of pathological conditions, including impaired immunity, retarded growth, brain development disorders and delayed wound healing. Moreover, many reports have suggested that Zn is involved in cancer development and levels of Zn in serum and malignant tissues of patients with various types of cancer are abnormal. Zn may directly affect tumor cells by regulating gene expression profiles and/or cell viability, both of which are mediated in part by tumor‐induced changes in Zn transporter expression. On the other hand, Zn may indirectly influence tumor cells by affecting processes within the cancer microenvironment, including immune responses; the functions and/or activity levels of immune cells that attack tumor cells are influenced by the intracellular Zn concentrations within those cells. In both cases, Zn contributes to intracellular metal homeostasis and/or signal transduction in tumor and immune cells. In this review article, we will summarize the current understanding of the roles of Zn homeostasis and signaling primarily in immune cells, with a discussion of the contributions of these processes to oncogenesis. (Cancer Sci 2008; 99: 1515–1522)
How COVID-19 induces cytokine storm with high mortality
The newly emerging coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, China, but has rapidly spread all over the world. Some COVID-19 patients encounter a severe symptom of acute respiratory distress syndrome (ARDS) with high mortality. This high severity is dependent on a cytokine storm, most likely induced by the interleukin-6 (IL-6) amplifier, which is hyper-activation machinery that regulates the nuclear factor kappa B (NF-κB) pathway and stimulated by the simultaneous activation of IL-6-signal transducer and activator of transcription 3 (STAT3) and NF-κB signaling in non-immune cells including alveolar epithelial cells and endothelial cells. We hypothesize that IL-6-STAT3 signaling is a promising therapeutic target for the cytokine storm in COVID-19, because IL-6 is a major STAT3 stimulator, particularly during inflammation. We herein review the pathogenic mechanism and potential therapeutic targets of ARDS in COVID-19 patients.
Calcitonin receptor downregulation and exercise-conditioned blood enable systemic muscle stem cell proliferation
Quiescent muscle stem cells (MuSCs) respond to exercise; however, the coordinated regulation of increased loading, exerkines, and quiescence signaling remains unclear. We found that increased loading reduces calcitonin receptor (CalcR) expression, and forced activation of protein kinase A (PKA), a downstream of CalcR signaling, suppresses MuSC proliferation. Although MuSC-specific Calcr knockout (C-cKO) alone is insufficient, exercised C-cKO mice exhibit significant MuSC proliferation independent of increased loading. Reinforcement of CalcR signaling, either through PKA induction or Yap1 depletion, suppresses MuSC proliferation. Load-independent MuSC proliferation is also suppressed by the deletion of gp130 in C-cKO mice. Serum from exercised mice recapitulates MuSC proliferation in all analyzed muscles of sedentary C-cKO mice, which is abrogated by anti-IL-6 antibodies, and we find cross-talk between CalcR and gp130 signaling via Yap1 phosphorylation. Together, our findings reveal an integrated mechanism by which increased loading, exerkine-gp130, and CalcR signaling converge to fine-tune MuSC activity during exercise. Here they show that muscle stem cells lacking calcitonin receptor (CalcR) undergo proliferation in running-exercised mice, independent of mechanical load, and demonstrate that CalcR functions to suppress activation of exerkine (IL-6)-gp130–YAP axis.
Neurobiology of COVID‐19‐Associated Psychosis/Schizophrenia: Implication of Epidermal Growth Factor Receptor Signaling
COVID‐19 exhibits not only respiratory symptoms but also neurological/psychiatric symptoms rarely including delirium/psychosis. Pathological studies on COVID‐19 provide evidence that the cytokine storm, in particular (epidermal growth factor) EGF receptor (EGFR, ErbB1, Her1) activation, plays a central role in the progression of viral replication and lung fibrosis. Of note, SARS‐CoV‐2 virus (specifically, S1 spike domain) mimics EGF and directly transactivates EGFR, preceding the inflammatory process. In agreement, the anticancer drugs targeting EGFR such as Nimotuzumab and tyrosine kinase inhibitors are markedly effective on COVID‐19. However, these data might raise a provisional caution regarding implication of psychiatric disorder such as schizophrenia. The author's group has been investigating the etiologic and neuropathologic associations of EGFR signaling with schizophrenia. There are significant molecular associations between schizophrenia and EGFR ligand levels in blood as well as in the brain. In addition, perinatal challenges of EGFR ligands and intraventricular administration of EGF to rodents and monkeys both resulted in severe behavioral and/or electroencephalographic endophenotypes relevant to this disorder. These animal models also display postpubertal abnormality in soliloquy‐like self‐vocalization as well as in intercortical functional connectivity. Here, we discuss neuropsychiatric implication of coronavirus infection and its interaction with the EGFR system, by searching related literatures in PubMed database as of the end of 2023. Coronavirus directly transactivates epidermal growth factor receptors. Coronavirus stimulates epidermal growth factor release by ectodomain shedding. The brain activation of epidermal growth factor receptors results in acute or chronic psychotic behaviors.
GGT1 is a SNP eQTL gene involved in STAT3 activation and associated with the development of Post-ERCP pancreatitis
Post-ERCP pancreatitis (PEP) is an acute pancreatitis caused by endoscopic-retrograde-cholangiopancreatography (ERCP). About 10% of patients develop PEP after ERCP. Here we show that gamma-glutamyltransferase 1 (GGT1)-SNP rs5751901 is an eQTL in pancreatic cells associated with PEP and a positive regulator of the IL-6 amplifier. More PEP patients had the GGT1 SNP rs5751901 risk allele (C) than that of non-PEP patients at Hokkaido University Hospital. Additionally, GGT1 expression and IL-6 amplifier activation were increased in PEP pancreas samples with the risk allele. A mechanistic analysis showed that IL-6-mediated STAT3 nuclear translocation and STAT3 phosphorylation were suppressed in GGT1-deficient cells. Furthermore, GGT1 directly associated with gp130, the signal-transducer of IL-6. Importantly, GGT1-deficiency suppressed inflammation development in a STAT3/NF-κB-dependent disease model. Thus, the risk allele of GGT1-SNP rs5751901 is involved in the pathogenesis of PEP via IL-6 amplifier activation. Therefore, the GGT1-STAT3 axis in pancreas may be a prognosis marker and therapeutic target for PEP.
Photopic light-mediated down-regulation of local α1A-adrenergic signaling protects blood-retina barrier in experimental autoimmune uveoretinitis
We have reported the gateway reflex, which describes specific neural activations that regulate immune cell gateways at specific blood vessels in the central nervous system (CNS). Four types of gateway reflexes exist, all of which induce alterations in endothelial cells at specific vessels of the blood-brain barrier followed by inflammation in the CNS in the presence of CNS-autoreactive T cells. Here we report a new gateway reflex that suppresses the development of retinal inflammation by using an autoreactive T cell-mediated ocular inflammation model. Exposure to photopic light down-regulated the adrenoceptor pathway to attenuate ocular inflammation by suppressing breaching of the blood-retina barrier. Mechanistic analysis showed that exposure to photopic light down-regulates the expression of α 1A -adrenoceptor (α 1A AR) due to high levels of norepinephrine and epinephrine, subsequently suppressing inflammation. Surgical ablation of the superior cervical ganglion (SCG) did not negate the protective effect of photopic light, suggesting the involvement of retinal noradrenergic neurons rather than sympathetic neurons from the SCG. Blockade of α 1A AR signaling under mesopic light recapitulated the protective effect of photopic light. Thus, targeting regional adrenoceptor signaling might represent a novel therapeutic strategy for autoimmune diseases including those that affect organs separated by barriers such as the CNS and eyes.
Interleukin-6/interleukin-21 signaling axis is critical in the pathogenesis of pulmonary arterial hypertension
Significance Pulmonary arterial hypertension (PAH) is a serious disease characterized by vascular remodeling in pulmonary arteries. Although an elevated IL-6 serum level correlates with poor prognosis of PAH patients, it is unclear how IL-6 promotes PAH. Here we identified IL-21 as a downstream target of IL-6 signaling in PAH. In mice with hypoxia-induced pulmonary hypertension (HPH), Th17 cells and M2 macrophages accumulate in the lungs after hypoxia exposure. IL-21 primarily derived from Th17 cells promotes M2 macrophage polarization. Consistently, IL-21 receptor-deficient mice show resistance to HPH with no accumulation of M2 macrophages in the lungs. IL-21 and M2 macrophage markers were upregulated in the lungs of patients with end-stage idiopathic PAH. These findings suggest promising therapeutic strategies for PAH targeting IL-6/IL-21–signaling axis. IL-6 is a multifunctional proinflammatory cytokine that is elevated in the serum of patients with pulmonary arterial hypertension (PAH) and can predict the survival of patients with idiopathic PAH (IPAH). Previous animal experiments and clinical human studies indicate that IL-6 is important in PAH; however, the molecular mechanisms of IL-6–mediated pathogenesis of PAH have been elusive. Here we identified IL-21 as a downstream target of IL-6 signaling in PAH. First, we found that IL-6 blockade by the monoclonal anti-IL-6 receptor antibody, MR16-1, ameliorated hypoxia-induced pulmonary hypertension (HPH) and prevented the hypoxia-induced accumulation of Th17 cells and M2 macrophages in the lungs. Consistently, the expression levels of IL-17 and IL-21 genes, one of the signature genes for Th17 cells, were significantly up-regulated after hypoxia exposure in the lungs of mice treated with control antibody but not in the lungs of mice treated with MR16-1. Although IL-17 blockade with an anti–IL-17A neutralizing antibody had no effect on HPH, IL-21 receptor-deficient mice were resistant to HPH and exhibited no significant accumulation of M2 macrophages in the lungs. In accordance with these findings, IL-21 promoted the polarization of primary alveolar macrophages toward the M2 phenotype. Of note, significantly enhanced expressions of IL-21 and M2 macrophage markers were detected in the lungs of IPAH patients who underwent lung transplantation. Collectively, these findings suggest that IL-21 promotes PAH in association with M2 macrophage polarization, downstream of IL-6-signaling. The IL-6/IL-21–signaling axis may be a potential target for treating PAH.
Coronary cross-sectional area stenosis severity determined using coronary CT highly correlated with coronary functional flow reserve: a pilot study
Fractional flow reserve (FFR) is the gold standard for assessing the physiological significance of coronary stenosis. We examined the potential correlation between digitally measured coronary cross-sectional area stenosis using coronary computed tomography (CT) angiography and FFR. We analyzed data of 32 consecutive patients with stenoses who underwent invasive FFR determination. The cross-sectional area was assessed using 128-slice coronary detector-based spectral CT angiography. Power analysis revealed that the sample size enabled the detection of an area under the receiver operating characteristic (ROC) curve (AUC) of 0.90. FFR ≤ 0.8 and > 0.8 were defined as FFR-positive and FFR-negative, respectively. Intra- and interobserver differences were negligible. Percentage cross-sectional area stenosis was calculated as 100 × (A−B)/A, where A is the cross-sectional area at non-stenotic pre-stenotic segment and B is the cross-sectional area of the most severe stenotic lesion. AUC indicated that percentage cross-sectional area stenosis effectively discriminated between FFR-positive and FFR-negative cases, yielding a sensitivity of 0.882 and specificity of 0.933 at a cutoff of 50% area reduction, with an AUC of 0.976. Lesions with less than 45% cross-sectional area stenosis on coronary CT angiography were not FFR-positive. When ROC analysis was conducted for lesion characteristics, AUC did not significantly improve. In conclusion, the percent coronary cross-sectional area stenosis measured using coronary CT angiography distinguished between FFR-positive and FFR-negative lesions with high accuracy. The severity of coronary cross-sectional area stenosis determined using CT angiography is clinically useful for predicting FFR.
Brachial artery transposition versus catheters as tertiary vascular access for maintenance hemodialysis: a single-center retrospective study
Some hemodialysis patients are not suitable for creation of an arteriovenous fistula (AVF) or arteriovenous graft (AVG). However, they can receive a tunneled cuffed central venous catheter (tcCVC), but this carries risks of infection and mortality. We aimed to evaluate the safety and effectiveness of brachial artery transposition (BAT) versus those of tcCVC. This retrospective study evaluated hemodialysis patients who underwent BAT or tcCVC placement because of severe heart failure, hand ischemia, central venous stenosis or occlusion, inadequate vessels for creating standard arteriovenous access, or limited life expectancy. The primary outcome was whole access circuit patency. Thirty-eight patients who underwent BAT and 25 who underwent tcCVC placement were included. One-year patency rates for the whole access circuit were 84.6% and 44.9% in the BAT and tcCVC groups, respectively. The BAT group was more likely to maintain patency (unadjusted hazard ratio: 0.17, 95% confidence interval: 0.05–0.60, p  = 0.006). The two groups did not have significantly different overall survival (log-rank p  = 0.146), although severe complications were less common in the BAT group (3% vs. 28%, p  = 0.005). Relative to tcCVC placement, BAT is safe and effective with acceptable patency in hemodialysis patients not suitable for AVF or AVG creation.
The gateway reflex regulates tissue-specific autoimmune diseases
The dynamic interaction and movement of substances and cells between the central nervous system (CNS) and peripheral organs are meticulously controlled by a specialized vascular structure, the blood-brain barrier (BBB). Experimental and clinical research has shown that disruptions in the BBB are characteristic of various neuroinflammatory disorders, including multiple sclerosis. We have been elucidating a mechanism termed the \"gateway reflex\" that details the entry of immune cells, notably autoreactive T cells, into the CNS at the onset of such diseases. This process is initiated through local neural responses to a range of environmental stimuli, such as gravity, electricity, pain, stress, light, and joint inflammation. These stimuli specifically activate neural pathways to open gateways at targeted blood vessels for blood immune cell entry. The gateway reflex is pivotal in managing tissue-specific inflammatory diseases, and its improper activation is linked to disease progression. In this review, we present a comprehensive examination of the gateway reflex mechanism.