Thermosensitive TRPV4 channels mediate temperature-dependent microglia movement.

Microglia maintain central nervous system homeostasis by monitoring changes in their environment (resting state) and by taking protective actions to equilibrate such changes (activated state). These surveillance and protective roles both require constant movement of microglia. Interestingly, induced hypothermia can reduce microglia migration caused by ischemia, suggesting that microglia movement can be modulated by temperature. Although several ion channels and transporters are known to support microglia movement, the precise molecular mechanism that regulates temperature-dependent movement of microglia remains unclear. Some members of the transient receptor potential (TRP) channel superfamily exhibit thermosensitivity and thus are strong candidates for mediation of this phenomenon. Here, we demonstrate that mouse microglia exhibit temperature-dependent movement in vitro and in vivo that is mediated by TRPV4 channels within the physiological range of body temperature. Our findings may provide a basis for future research into the potential clinical application of temperature regulation to preserve cell function via manipulation of ion channel activity.

The Japanese Epidemiologic Study for Perioperative Anaphylaxis, a prospective nationwide study: allergen exposure, epidemiology, and diagnosis of anaphylaxis during general anaesthesia.

BACKGROUND: Diagnosis of perioperative anaphylaxis is often challenging. This study describes the utility of a newly developed tool for identifying patients with a high possibility of anaphylaxis, and aimed to investigate the frequency of anaphylaxis with each drug during the perioperative period in Japan. METHODS: This study included patients with anaphylaxis of Grade 2 or higher severity during general anaesthesia at 42 facilities across Japan in 2019 and 2020. We developed and adopted a unique objective evaluation tool yielding a composite score for diagnosing anaphylaxis, which includes the results of skin tests and basophil activation tests, and clinical scores for perioperative anaphylaxis. The number of cases using each drug and the total number of anaphylaxis cases were investigated to calculate the frequency of anaphylaxis. RESULTS: General anaesthesia was performed in 218 936 cases, which included 55 patients with suspected perioperative anaphylaxis. The developed composite score diagnosed 43 of them with a high probability of anaphylaxis. The causative agent was identified in 32 cases. Plasma histamine levels showed high diagnostic accuracy for anaphylaxis. The top causative agents were rocuronium (10 cases in 210 852 patients, 0.005%), sugammadex (7 cases in 150 629 patients, 0.005%), and cefazolin (7 cases in 106 005 patients, 0.007%). CONCLUSIONS: We developed a composite tool to diagnose anaphylaxis, and found that the combination of tryptase levels, skin testing, and basophil activation testing results and clinical score improved the certainty of anaphylaxis diagnosis. The incidence of perioperative anaphylaxis in our study was 1 in about 5000 general anaesthesia cases. CLINICAL TRIAL REGISTRATION: UMIN000035350.

An Assessment of the Practice of Neuromuscular Blockade and the Association Between Its Prophylactic Use and Outcomes Among Postoperative Pediatric Cardiac Patients.

OBJECTIVES: The authors investigated the management of neuromuscular blocking agents (NMBAs) for pediatric patients after cardiac surgery, and compared the outcomes of patients who received prophylactic NMBA (pNMBA) infusions and patients without pNMBA infusions. DESIGN: A retrospective cohort study. SETTING: At a tertiary teaching hospital. PARTICIPANTS: Patients younger than 18, with congenital heart disease, who underwent cardiac surgery. INTERVENTIONS: Commencement of NMBA infusion in the first 2 hours after surgery MEASUREMENTS AND MAIN RESULTS: The primary endpoint was a composite of one or more of the following major adverse events (MAEs) that occurred within 7 days after surgery: death from any cause, a circulatory collapse that needed cardiopulmonary resuscitation, and requirement for extracorporeal membrane oxygenation. The secondary endpoints included the total duration of mechanical ventilation for the first 30 days after surgery. A total of 566 patients were included in this study. The MAEs occurred in 13 patients (2.3%). An NMBA was commenced within 2 hours after surgery in 207 patients (36.6%). There were significant differences in the incidence of postoperative MAEs between the pNMBA group and the non-pNMBA group (5.3% v 0.6%; p < 0.001). In multivariate regression models, pNMBA infusion was not significantly associated with the incidence of MAEs (odds ratio: 1.79, 95% CI: 0.23-13.93, p = 0.58), but was significantly associated with prolonged mechanical ventilation by 3.85 days (p < 0.001). CONCLUSIONS: Postoperative prophylactic neuromuscular blockade after cardiac surgery can be associated with prolonged mechanical ventilation, but has no association with MAEs among pediatric patients with congenital heart disease.

Intrathecal Administration of the α1 Adrenergic Antagonist Phentolamine Upregulates Spinal GLT-1 and Improves Mirror Image Pain in SNI Model Rats.

Mirror image pain (MIP) is a type of extraterritorial pain that results in contralateral pain or allodynia. Glutamate transporter-1 (GLT-1) is expressed in astrocytes and plays a role in maintaining low glutamate levels in the synaptic cleft. Previous studies have shown that GLT-1 dysfunction induces neuropathic pain. Our previous study revealed bilateral GLT-1 downregulation in the spinal cord of a spared nerve injury (SNI) rat. We hypothesized that spinal GLT-1 is involved in the mechanism of MIP. We also previously demonstrated noradrenergic GLT-1 regulation. Therefore, this study aimed to investigate the effect of an α1 adrenergic antagonist on the development of MIP. Rats were subjected to SNI. Changes in pain behavior and GLT-1 protein levels in the SNI rat spinal cords were then examined by intrathecal administration of the α1 adrenergic antagonist phentolamine, followed by von Frey test and western blotting. SNI resulted in the development of MIP and bilateral downregulation of GLT-1 protein in the rat spinal cord. Intrathecal phentolamine increased contralateral GLT-1 protein levels and partially ameliorated the 50% paw withdrawal threshold in the contralateral hind paw. Spinal GLT-1 upregulation by intrathecal phentolamine ameliorates MIP. GLT-1 plays a role in the development of MIPs.

Incidence Rates of Postoperative Pulmonary Embolisms in Symptomatic and Asymptomatic Patients, Detected by Diagnostic Images　- A Single-Center Retrospective Study.

BACKGROUND: Pulmonary embolism (PE) is a serious complication during the perioperative period. However, because most previous studies on the incidence of postoperative PE are based on symptoms, asymptomatic occurrences of PE have been overlooked, and the absolute incidence of postoperative PE remains unknown. The aim of this study was to investigate the incidence of perioperative PE, regardless of its symptoms, by reviewing the clinical interpretations of the diagnostic images obtained during the postoperative period. Methods and Results: This study included all patients aged at least 18 years who underwent operations under general and/or neuraxial anesthesia in our institution from 2013 to 2016. We reviewed all interpretations of the diagnostic imaging performed in the postoperative period. We analyzed the 90-day cumulative incidence of postoperative PE and the characteristics, risk factors, and symptoms of patients with and without postoperative PE. Among 21,763 operations, postoperative diagnostic imaging was performed in 1,168 patients, which found PE in 217 patients. Symptoms appeared in 11.1% (24/217) of the PE patients, and 66.7% of these symptoms were decreased levels of SpO2alone. Mortality from PE was 0.5% (1/217). CONCLUSIONS: Diagnostic imaging found a number of postoperative PE cases, regardless of the presence of symptoms. Although symptomatic PE was not a frequent occurrence, these findings suggest that clinicians should be aware of postoperative PE even under current prophylaxis.

Possible biased analgesic of hydromorphone through the G protein-over ß-arrestin-mediated pathway: cAMP, CellKey™, and receptor internalization analyses.

Morphine, fentanyl, and oxycodone are widely used as analgesics, and recently hydromorphone has been approved in Japan. Although all of these are selective for µ-opioid receptors (MORs) and have similar structures, their analgesic potencies and adverse effects (AEs) are diverse. Recent molecular analyses of MOR signaling revealed that the G protein-mediated signaling pathway causes analgesic effects and the ß-arrestin-mediated signaling pathway is responsible for AEs. We used several cell-based analyses that selectively measure cellular responses activated by either G protein- or ß-arrestin-mediated pathways. GloSensor™ cAMP, CellKey™, and receptor internalization assays were performed with four different types of cells stably expressing differentially labelled MOR. EC50 values measured by cAMP and CellKey™ assays had potencies in the order fentanyl ≤ hydromorphone < morphine ≤ oxycodone, all also exhibiting full agonist responses. However, in the internalization assay, only fentanyl elicited a full agonist response. Hydromorphone had the strongest potency next to fentanyl; however, contribution of the ß-arrestin-mediated pathway was small, suggesting that its effect could be biased toward the G protein-mediated pathway. Based on these properties, hydromorphone could be chosen as an effective analgesic.

Norepinephrine-induced downregulation of GLT-1 mRNA in rat astrocytes.

AIM OF THE RESEARCH: Glutamate transporter-1 (GLT-1; also known as excitatory amino acid transporter 2) plays an important role in the maintenance of glutamate homeostasis in the synaptic cleft. Downregulation of GLT-1 in the spinal cord has been reported in chronic pain models, which suggests that GLT-1 is involved in the development of chronic pain. However, the mechanism by which GLT-1 is downregulated in the spinal cord is still unknown. We hypothesized that norepinephrine is involved in the regulation of GLT-1. The aim of this study was to investigate the effect of norepinephrine on GLT-1 expression in cultured astrocytes. METHODS: This study involved both in vivo and in vitro experiments. We first validated changes in GLT-1 mRNA expression in the spinal cord of rats with spared nerve injury (SNI) using real-time RT-PCR. Next, cultured primary astrocytes from the rat spinal cord were stimulated with norepinephrine, and GLT-1 mRNA was subsequently quantitated. RNB cells, an astrocytic cell line, were also stimulated with norepinephrine and other α-adrenoceptor agonists. RESULTS: SNI resulted in bilateral downregulation of GLT-1 in rat spinal cord. The in vitro study showed that norepinephrine and phenylephrine dose-dependently downregulated GLT-1 in primary astrocytes and RNB cells. Furthermore, the effect of norepinephrine was reversed by an α-adrenoceptor antagonist. CONCLUSION: Norepinephrine downregulates GLT-1 mRNA expression in astrocytes via the α1-adrenoceptor. Our results provide new insight into the mechanisms involved in downregulation of GLT-1 in the chronic pain models.

Quercetin Attenuates Neuropathic Pain in Rats with Spared Nerve Injury.

Quercetin is a flavonoid widely found in plants and marketed to the public as a supplement. Several studies have reported its effect on glial cells. This study aimed to examine the effect of quercetin on the development of neuropathic pain and the underlying mechanism in a spared nerve injury (SNI) rat model. Male Sprague-Dawley rats randomly assigned to the control or the quercetin group were subjected to SNI of the sciatic nerve. We measured pain behaviors on the hind paw and glial fibrillary acidic protein (GFAP) in the dorsal root ganglion (DRG) and spinal cord. Oral administration of 1% quercetin, begun before surgery, attenuated mechanical allodynia compared to the control group at days 7 and 10 after SNI. On the other hand, established pain was not attenuated in a post-dose group in which quercetin was begun 7 days after SNI. Quercetin inhibited GFAP in the satellite glial cells of the ipsilateral L5 DRG on day 7 compared to the control group. Quercetin suppressed the development of neuropathic pain through a mechanism partly involving the inhibition of satellite glial cells. As its safety is well established, quercetin has great potential for clinical use in pain treatment.

Prospectively Isolated Human Bone Marrow Cell-Derived MSCs Support Primitive Human CD34-Negative Hematopoietic Stem Cells.

Hematopoietic stem cells (HSCs) are maintained in a specialized bone marrow (BM) niche, which consists of osteoblasts, endothelial cells, and a variety of mesenchymal stem/stromal cells (MSCs). However, precisely what types of MSCs support human HSCs in the BM remain to be elucidated because of their heterogeneity. In this study, we succeeded in prospectively isolating/establishing three types of MSCs from human BM-derived lineage- and CD45-negative cells, according to their cell surface expression of CD271 and stage-specific embryonic antigen (SSEA)-4. Among them, the MSCs established from the Lineage(-) CD45(-) CD271(+) SSEA-4(+) fraction (DP MSC) could differentiate into osteoblasts and chondrocytes, but they lacked adipogenic differentiation potential. The DP MSCs expressed significantly higher levels of well-characterized HSC-supportive genes, including IGF-2, Wnt3a, Jagged1, TGFß3, nestin, CXCL12, and Foxc1, compared with other MSCs. Interestingly, these osteo-chondrogenic DP MSCs possessed the ability to support cord blood-derived primitive human CD34-negative severe combined immunodeficiency-repopulating cells. The HSC-supportive actions of DP MSCs were partially carried out by soluble factors, including IGF-2, Wnt3a, and Jagged1. Moreover, contact between DP MSCs and CD34-positive (CD34(+) ) as well as CD34-negative (CD34(-) ) HSCs was important for the support/maintenance of the CD34(+/-) HSCs in vitro. These data suggest that DP MSCs might play an important role in the maintenance of human primitive HSCs in the BM niche. Therefore, the establishment of DP MSCs provides a new tool for the elucidation of the human HSC/niche interaction in vitro as well as in vivo.

Citrin-deficient patient-derived induced pluripotent stem cells as a pathological liver model for congenital urea cycle disorders.

Citrin deficiency is a congenital secondary urea cycle disorder lacking useful disease models for effective treatment development. In this study, human induced pluripotent stem cells (iPSCs) were generated from two patients with citrin deficiency and differentiated into hepatocyte-like cells (HLCs). Citrin-deficient HLCs produced albumin and liver-specific markers but completely lacked citrin protein and expressed argininosuccinate synthase only weakly. In addition, ammonia concentrations in a medium cultured with citrin-deficient HLCs were higher than with control HLCs. Sodium pyruvate administration significantly reduced ammonia concentrations in the medium of citrin-deficient HLCs and slightly reduced ammonia in HLCs differentiated from control iPSCs, though this change was not significant. Our results suggest that sodium pyruvate may be an efficient treatment for patients with citrin deficiency. Citrin-deficient iPSCs are a pathological liver model for congenital urea cycle disorders to clarify pathogenesis and develop novel therapies.

Decreased expression of hyaluronan synthase and loss of hyaluronan-rich cells in the anterior tibial fascia of the rat model of chemotherapy-induced peripheral neuropathy.

Introduction: Previous studies on chemotherapy-induced peripheral neuropathy (CIPN) have focused on neuronal damage. Although some studies have revealed that the fascia is an important sensory organ, currently, we do not know about chemotherapy drug-induced fascial dysfunction. Objectives: This study aimed to explore the fascia as a nonneural cause of mechanical hypersensitivity in CIPN by investigating the expression of hyaluronic acid synthase (HAS) and histology of the fascia in an animal model of CIPN. Methods: Rats were intraperitoneally administered with vincristine (VCR). Mechanical hypersensitivities of the hind paw and the anterior tibial muscle were assessed. The expression of HAS mRNA in the fascia of the anterior tibial muscles was quantitated using reverse transcription polymerase chain reaction. Immunohistochemistry was also performed for HAS2, hyaluronic acid-binding protein, and S100A4 in the fascia. Results: Vincristine administration significantly decreased mechanical withdrawal thresholds in the hind paw and the anterior tibial muscle after day 3. Quantitative polymerase chain reaction showed significant downregulation of HAS mRNAs in the fascia of VCR-treated rats. Immunohistochemical analysis showed that the number of cells with strong HAS2 immunoreactivity, classified as fasciacytes by morphology and colocalized marker S100A4, decreased significantly in the VCR group. Conclusion: Hyaluronic acid plays a critical role in somatic pain sensation. Damaged fascia could be a possible cause of musculoskeletal pain in patients with CIPN. This study suggests that fascia is a nonneural cause and novel therapeutic target for chemotherapy-induced "peripheral neuropathy."

Clinical Impact of Prehabilitation on Elective Laparoscopic Surgery in Frail Octogenarians With Colorectal Cancer.

BACKGROUND/AIM: The aim of the present study was to clarify the clinical impact of prehabilitation by the perioperative management center (PERIO) at our hospital in severely frail octogenarians with colorectal cancer. PATIENTS AND METHODS: We compared the clinicopathological characteristics of octogenarians who underwent surgery for colorectal cancer before the establishment of PERIO intervention (Control group) with those who received prehabilitation (PERIO group). All patients were classified as American Society of Anesthesiologists (ASA) class 3 or higher. The primary outcome was the incidence of postoperative complications. RESULTS: There were 21 patients in the Control group and 19 patients in the PERIO group. Operative time was significantly longer in the PERIO group (Control group, 200 min vs. PERIO group, 230 min; p=0.03) and blood loss was significantly higher in the PERIO group (Control group, 5 ml vs. PERIO group, 30 ml; p=0.02). Postoperative complications occurred in 10 patients (47.6%) in the Control group and 3 patients (15.8%) in the PERIO group and were significantly lower in the PERIO group (p=0.03). Postoperative hospital stay was 13 days (range=7-31 days) in the Control group and 11 days (range=8-70 days) in the PERIO group (p=0.39). The rate of discharge directly to home was 81% in the Control group and 93.3% in the PERIO group (p=0.29). CONCLUSION: In frail octogenarians with colorectal cancer of ASA class 3 or higher, the incidence of postoperative complications was significantly lower after PERIO intervention.

Efficient protocol for the differentiation of kidney podocytes from induced pluripotent stem cells, involving the inhibition of mTOR.

The mechanistic/mammalian target of rapamycin (mTOR) is involved in a wide range of cellular processes. However, the role of mTOR in podocytes remains unclear. In this study, we aimed to clarify the role of mTOR in podocyte differentiation from human induced pluripotent stem cells (hiPSCs) and to establish an efficient differentiation protocol for human podocytes. We generated podocytes from hiPSCs by modifying protocol. The expression of the podocyte-specific slit membrane components nephrin and podocin was measured using PCR, western blotting, flow cytometry, and immunostaining; and the role of mTOR was evaluated using inhibitors of the mTOR pathway. Nephrin and podocin were found to be expressed in cells differentiated from hiPSCs, and their expression was increased by mTOR inhibitor treatment. S6, a downstream component of the mTOR pathway, was also found to be involved in podocyte differentiation. we evaluated its permeability to albumin, urea, and electrolytes. The induced podocytes were permeable to the small molecules, but only poorly permeable to albumin. We have shown that the mTOR pathway is involved in podocyte differentiation. Our monolayer podocyte differential protocol, using an mTOR inhibitor, provides a novel in vitro model for studies of kidney physiology and pathology.

The Induction of Parathyroid Cell Differentiation from Human Induced Pluripotent Stem Cells Promoted Via TGF-α/EGFR Signaling.

The parathyroid gland plays an essential role in mineral and bone metabolism. Cultivation of physiological human parathyroid cells has yet to be established and the method by which parathyroid cells differentiate from pluripotent stem cells remains uncertain. Therefore, it has been hard to clarify the mechanisms underlying the onset of parathyroid disorders, such as hyperparathyroidism. In this study, we developed a new method of parathyroid cell differentiation from human induced pluripotent stem (iPS) cells. Parathyroid cell differentiation occurred in accordance with embryologic development. Differentiated cells, which expressed the parathyroid hormone, adopted unique cell aggregation similar to the parathyroid gland. In addition, these differentiated cells were identified as calcium-sensing receptor (CaSR)/epithelial cell adhesion molecule (EpCAM) double-positive cells. Interestingly, stimulation with transforming growth factor-α (TGF-α), which is considered a causative molecule of parathyroid hyperplasia, increased the CaSR/EpCAM double-positive cells, but this effect was suppressed by erlotinib, which is an epidermal growth factor receptor (EGFR) inhibitor. These results suggest that TGF-α/EGFR signaling promotes parathyroid cell differentiation from iPS cells in a similar manner to parathyroid hyperplasia.

CD48 as a novel molecular target for antibody therapy in multiple myeloma.

Monoclonal antibody (mAb) drugs are desirable for the improvement of multiple myeloma (MM) treatment. In this study, we found for the first time that CD48 was highly expressed on MM plasma cells. In 22 out of 24 MM patients, CD48 was expressed on more than 90% of MM plasma cells at significantly higher levels than it was on normal lymphocytes and monocytes. CD48 was only weakly expressed on some CD34(+) haematopoietic stem/progenitor cells, and not expressed on erythrocytes or platelets. We next examined whether CD48 could serve as a target antigen for mAb therapy against MM. A newly generated in-house anti-CD48 mAb induced mild antibody-dependent cell-mediated cytotoxicity and marked complement-dependent cytotoxicity against not only MM cell lines but also primary MM plasma cells in vitro. Administration of the anti-CD48 mAb significantly inhibited tumour growth in severe combined immunodeficient mice inoculated subcutaneously with MM cells. Furthermore, anti-CD48 mAb treatment inhibited growth of MM cells transplanted directly into murine bone marrow. Finally and importantly, we demonstrated that the anti-CD48 mAb did not damage normal CD34(+) haematopoietic stem/progenitor cells. These results suggest that the anti-CD48 mAb has the potential to become an effective therapeutic mAb against MM.

Low level of c-kit expression marks deeply quiescent murine hematopoietic stem cells.

Although c-kit is expressed highly on murine hematopoietic stem cells (HSCs) and essential for bone marrow (BM) hematopoiesis, the significance of the high level of expression of c-kit on HSCs was not well determined. We show here that CD150(+) CD48(-) Lineage(-) Sca-1(+) c-kit(+) HSCs in adult BM are distributed within the range of roughly a 20-fold difference in the expression level of c-kit, and that c-kit density correlates with the cycling status of the HSC population. This predisposition is more evident in the BM of mice older than 30 weeks. The HSCs in G(0) phase express a lower level of c-kit both on the cell surface and inside the cells, which cannot be explained by ligand receptor binding and internalization. It is more likely that the low level of c-kit expression is a unique property of HSCs in G(0). Despite functional differences in the c-kit gradient, the HSCs are uniformly hypoxic and accessible to blood perfusion. Therefore, our data indicate the possibility that the hypoxic state of the HSCs is actively regulated, rather than them being passively hypoxic through a simple anatomical isolation from the circulation.

Antinociceptive effects of intrathecal landiolol injection in a rat formalin pain model.

Perioperative beta-blocker administration has recently been recommended for patients undergoing cardiac or other surgery due to the beneficial cardiovascular effects of these agents. In addition, some studies have reported that perioperatively administered beta-blockers also have analgesic effects. In this study, to investigate the antinociceptive effects and the analgesic profile of landiolol, we examined the effects of intrathecal landiolol administration on nociceptive pain behavior and c-fos mRNA expression (a neural marker of pain) in the spinal cord using a rat formalin model. We found that pain-related behavior was inhibited by intrathecal landiolol administration. Moreover, the increase in c-fos mRNA expression on the formalin-injected side was less pronounced in rats administered landiolol than in saline administered controls. Thus, intrathecal administration of landiolol exhibited antinociceptive effects. Further investigation of the antinociceptive mechanism of landiolol is required.

Ketamine Improves Desensitization of µ-Opioid Receptors Induced by Repeated Treatment with Fentanyl but Not with Morphine.

The issue of tolerance to continuous or repeated administration of opioids should be addressed. The ability of ketamine to improve opioid tolerance has been reported in clinical studies, and its mechanism of tolerance may involve improved desensitization of µ-opioid receptors (MORs). We measured changes in MOR activity and intracellular signaling induced by repeated fentanyl and morphine administration and investigated the effects of ketamine on these changes with human embryonic kidney 293 cells expressing MOR using the CellKey™, cADDis cyclic adenosine monophosphate, and PathHunter® ß-arrestin recruitment assays. Repeated administration of fentanyl or morphine suppressed the second MOR responses. Administration of ketamine before a second application of opioids within clinical concentrations improved acute desensitization and enhanced ß-arrestin recruitment elicited by fentanyl but not by morphine. The effects of ketamine on fentanyl were suppressed by co-treatment with an inhibitor of G-protein-coupled receptor kinase (GRK). Ketamine may potentially reduce fentanyl tolerance but not that of morphine through modulation of GRK-mediated pathways, possibly changing the conformational changes of ß-arrestin to MOR.