Specific Agonist Research Articles

Microglia Regulating Neuronal Apoptosis Via Alpha7 Nicotinic Acetylcholine Receptor in HIV-Associated Neurocognitive Disorders

Background: Microglia, the innate immune cells of the central nervous system (CNS), originate from erythromyeloid progenitor cells in the embryonic yolk sac. As the innate immune cells of the CNS, microglia play an important role in innate immunity, neurogenesis, and brain tissue repair by activating the alpha7 nicotinic acetylcholine receptor (α7nAChR). They are the key target cells for HIV-1 infection in the CNS and have been shown to produce a chronic inflammatory response in the brain which underlies HIV-associated neurocognitive disorders (HAND). Apart from the microglial neuroinflammation, recent studies have reported that activated microglia could induce neuronal apoptosis through the release of neurotoxic factors (e.g., ROS and NLRP3 inflammasome) in HAND. In addition, α7nAChR was significantly up-regulated in the striatum which is the most serious part of neuron apoptosis in gp120 transgenic mice brains. However, the underlying mechanism of neuronal cell apoptosis by gp120-activated microglia remains unclear. Here, this study aimed to explore the mechanism by which HIV-1 gp120-activated microglia induce neuronal apoptosis. Materials and methods: The expression of α7nAChR was examined by immunohistochemistry in the brain of HIV-1 LAV gp120 transgenic (Tg) mice (C57BL/6J background, 12-month-old). Methyllycaconitine (MLA, specific α7nAChR agonists) and Nicotine (NT, specific α7nAChR antagonists) were used to evaluate the effect of α7nAChR on apoptosis induced by gp120. Immortalized microglial cells (BV2) were incubated for 24 hours with gp120, NT, and gp120+NT, respectively, with or without preincubation with MLA for 15 minutes to obtain their supernatants. Next, the neuronal cells (SH-SY5Y) were treated with the same as BV2 or with collected BV2 culture supernatants. The apoptosis effect of SH-SY5Y and the level of ROS in the BV2 culture supernatants were assessed via quantitative analysis of flow cytometry. Comparisons between supernatant groups and drug groups were conducted to evaluate the effects of the SH-SY5Y apoptosis induced by microglia. Western blotting of microglia cell lysates was employed for the analysis of cellular signaling pathways. Student's t-tests and ANOVA were applied to determine statistical significance. Results: The expression of α7nAChR in HIV-1 gp120 transgenic mice was significantly upregulated (P < 0.001). The effect of apoptosis was more significant in microglia culture supernatants groups compared to that in drug-treated groups (P < 0.001). Neuronal activity was not changed in the NT group or MLA group than in the control, but HIV-1 gp120 could increase the number of apoptotic neurons (P < 0.01). Significant neuronal apoptosis was observed when treated with BV2 supernatants from the group treated by combining the gp120 with NT (P < 0.001), and this effect was in turn inhibited by MLA (P < 0.001). These results suggested that gp120-activated microglia might induce neuronal apoptosis invitro owing to gp120 upregulating α7nAChR. In addition, the ROS level in microglia was significantly upregulated following gp120 exposure (P < 0.001), and this effect could be enhanced by NT (P < 0.001). Notably, there was a positive correlation between the levels of ROS in microglia culture supernatants and the levels of neuronal apoptosis treated in the same supernatants. This positive relevance indicated that microglia might induce neuronal apoptosis by producing excessive ROS. The expressions of p53, OMI, and caspase-3 significantly upregulated following gp120 exposure with the down-regulate expression of XIAP (P < 0.001). And this effect could be enhanced by NT (P < 0.001). The results of western blotting indicated that gp120 and NT can up-regulate the ROS to activate p53 by α7nAChR, which could lead to an increased OMI and decreased XIAP levels. (P < 0.001). Conclusions: Microglia may play a critical role in regulating neuronal apoptosis in HAND. HIV-1 gp120 and NT could increase the generation of ROS through α7nAChR in microglia, which leads to neuronal apoptosis. Moreover, our results showed that the combined action of NT and gp120 may upregulate p53 and Omi / HtrA2 protein expression, and the downregulation of XIAP protein may significantly activate the level of caspase-3. (Acknowledgements:Corresponding author: Hong Cao, gzhcao@smu.edu.cn; National Natural Science Foundation of China, No. 82172259 to H.C.) Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

SRT1720 as an SIRT1 activator for alleviating paraquat-induced models of Parkinson's disease

Epidemiological studies have linked herbicides and Parkinson's disease (PD), with the strongest associations resulting from long exposure durations. Paraquat (PQ), an herbicide, induces PD-like syndromes and has widely been accepted as a PD mimetic. Currently, there is still no cure to prevent the progression of PD, and the search for effective therapeutic ways is urgent. Recently, the impairing activity of sirtuins (SIRTs), such as SIRT1, may correlate with PD etiology. However, the nonspecificity of SIRT1 agonists has made the protective mechanisms against PD unclear and hampered the therapeutic application of SIRT1. Thus, this study investigated the protective mechanism and therapeutic potential of SRT1720, a more specific agonist for SIRT1 synthesized by Sirtris, in alleviating the toxicity of PQ-induced cellular and animal models of PD. Here we show that SRT1720 alleviates PQ-induced toxicity in cell and animal models. Genetic silencing and pharmacological inhibition of SIRT1 attenuated SRT1720's protection against PQ-induced toxicity. Moreover, SRT1720 not only attenuated PQ-induced increased oxidative stress and mitochondrial free radical formations but also decreased mitochondrial membrane potential. Furthermore, SRT1720 reversed PQ-induced decreased PGC-1α levels and mitochondrial biogenesis. Although PQ and SRT1720 elevated NRF2 and antioxidative enzyme levels, only PQ decreased antioxidative enzyme activity but not SRT1720. NRF2 and PGC-1α silencing attenuated SRT1720 protection against PQ-induced toxicity. SRT1720 targeted SIRT1 and activated downstream PGC-1α and NRF2 signalings to prevent PQ-induced toxicity involving oxidative stress and mitochondrial dysfunction. Thus, SRT1720 might have therapeutic potential in preventing PD.

TRPA1 promotes UVB-induced skin pigmentation by regulating melanosome luminal pH.

Melanocytes stimulated by ultraviolet radiation (UVR) produce melanin and melanosomes, which causes skin pigmentation and acts as an important physiological defence process for photoprotection. Neutral luminal pH of melanosomes is critical for providing optimal conditions for the rate-limiting, pH-sensitive melanin synthesizing enzyme tyrosinase (TYR). As a major component of extraocular phototransduction pathway, transient receptor potential ankyrin1 (TRPA1) can be activated by ultraviolet B (UVB) and reported to be expressed in melanocytes. However, whether TRPA1 is involved in the regulation of melanogenesis remains unclear. Melanogenic activity of TRPA1 was evaluated in primary normal human epidermal melanocytes (HEMs) and murine B16-F10 cell cultures, and the effects of topical applications of TRPA1 specific agonist and antagonist on UVB-induced skin pigmentation were confirmed on in vivo guinea pig models. Calcium (Ca2+ ) imaging and pH imaging were performed to analyse the effects of TRPA1 on intracellular Ca2+ concentration ([Ca2+ ]ic ) and melanosome luminal pH. TRPA1 regulated melanin synthesis, UVB-induced Ca2+ influx and melanosome luminal pH in HEMs and B16-F10 cells. Topical treatment of TRPA1 specific agonist JT010 increased UVB-induced skin pigmentation in guinea pigs, while topical using of TRPA1 selective antagonist HC-030031 mitigated such pigmentation. Our results indicated that TRPA1 activated by UVB enhanced the skin pigmentation, most likely by regulating the [Ca2+ ]ic and the melanosomal pH, consequently influencing the enzymatic activity of TYR. Therefore, the results suggest TRPA1 as a potential therapeutic target in the treatment of skin pigmented disorders that are at high risk under UVB irradiation.

Abstract 9834: Lysosomal Ca 2+ Release Contribute to Arrhythmia After Myocardial Infarction

Introduction: In heart failure (HF), mitochondria Ca 2+ handling is involved in arrhythmogenesis by modulating diastolic sarcoplasmic reticulum (SR) Ca 2+ release. Recently, it has been reported that lysosomal Ca 2+ release can trigger a SR Ca 2+ release. Hypothesis: We investigated whether lysosomal Ca 2+ flux could contribute to ischemic HF arrhythmia in a similar manner to mitochondria. Methods: Ischemic HF was induced in wild type FVB/NJ mice by ligated left anterior descending coronary artery. Mice were studied at three weeks after myocardial infarction (MI). Results: The lysosomal-restricted transient receptor potential mucolipin 1 (TRPML1) Ca 2+ release channel, but not the two-pore channel 2, was significantly upregulated by 84.8% in cardiac border zone and 55.4% in a remote zone after MI, and cardiomyocyte TRPML1 was significantly increased in human patients with ischemic or nonischemic cardiomyopathy. As expected, TRPML1 co-localized with the lysosome marker, LAMP1. The master transcriptional lysosomal regulator, dephosphorylated TFEB (i.e., active TFEB) and LAMP1 labelled lysosomes increased after MI. Lysosomal Ca 2+ release directly as indicated by GCaMP7-TRPML1, a fluorescent Ca 2+ sensor coupled to TRPML1, was upregulated in MI mouse CMs. TRPML1 specific agonist, ML-SA1, could evoke Ca 2+ sparks in the CMs isolated from MI mice, and these sparks were inhibited by a specific antagonist, ML-SI1. Furthermore, thapsigargin or high concentration ryanodine, inhibited Ca 2+ loading and release from the SR respectively and prevented TRPML1-dependent Ca 2+ sparks in the MI CMs. TRPML1-dependent sparks were not affected by S107, a drug which specifically inhibits Ca 2+ leak, however. Blocking TRPML1depressed early and delayed afterdepolarizations (EADs and DADs) in CMs isolated from MI mice while increasing TRPML1 activity enhanced triggered activity. The inhibition of TRPML1 had no effect on the APs recorded from sham mouse CMs, however. ML-SA1 could increase induced ventricular fibrillation episodes in MI mice while ML-SI1 could reduce arrhythmia by optical mapping and pacing. Conclusions: Lysosomes contribute to arrhythmic risk in MI by releasing Ca 2+ during diastole causing SR diastolic Ca 2+ release and triggered activity.

Dexmedetomidine Promotes Angiogenesis and Vasculogenic Mimicry in Human Hepatocellular Carcinoma through α2-AR/HIF-1α/VEGFA Pathway

ObjectiveDexmedetomidine (DEX), the most specific α2-adrenergic receptor agonist widely used for its sedative and analgesic properties, has been reported to upregulate HIF-1α expression to protect hypoxic and ischemic tissues. However, it is largely unclear whether DEX can also upregulate Hypoxia-inducible factor-1 alpha (HIF-1α) expression and its downstream vascular endothelial growth factor-A (VEGFA) in cancer tissues with oxygen-deficient tumor microenvironment. MethodsWe used SMMC-7721 cells, MHCC97-H cells, and a mouse model of orthotopic hepatic carcinoma to explore the effect of DEX on angiogenesis and vasculogenic mimicry (VM) and its mechanism. Under normoxic (20% O2) and hypoxic (1% O2) conditions, DEX was used to intervene cells, and yohimbine was used to rescue them. ResultsThe results showed that DEX promoted angiogenesis and VM in human liver cancer cells within a certain dose range, and the addition of yohimbine inhibited this effect. DEX could activate HIF-1α/VEGFA pathway, which was further verified by silencing HIF-1α. Consistently, in vivo results also showed that DEX can up-regulate HIF-1α/VEGFA expression, and enhance the number of VM channels and microvessel density (MVD). ConclusionWe believe that HIF-1α/VEGFA might be an important signaling pathway by which DEX promotes angiogenesis and VM formation in human hepatocellular carcinoma, whereas α2-adrenergic receptor mediation might be the critical mechanisms.

Targeting the brain 5-HT7 receptor to prevent hypomyelination in a rodent model of perinatal white matter injuries

Approximately 15 million babies are born prematurely every year and many will face lifetime motor and/or cognitive deficits. Children born prematurely are at higher risk of developing perinatal brain lesions, especially white matter injuries (WMI). Evidence in humans and rodents demonstrates that systemic inflammation-induced neuroinflammation, including microglial and astrocyte reactivity, is the prominent processes of WMI associated with preterm birth. Thus, a new challenge in the field of perinatal brain injuries is to develop new neuroprotective strategies to target neuroinflammation to prevent WMI. Serotonin (5-HT) and its receptors play an important role in inflammation, and emerging evidence indicates that 5-HT may regulate brain inflammation by the modulation of microglial reactivity and astrocyte functions. The present study is based on a mouse model of WMI induced by intraperitoneal (i.p.) injections of IL-1β during the first 5 days of life. In this model, certain key lesions of preterm brain injuries can be summarized by (i) systemic inflammation, (ii) pro-inflammatory microglial and astrocyte activation, and (iii) inhibition of oligodendrocyte maturation, leading to hypomyelination. We demonstrate that Htr7 mRNA (coding for the HTR7/5-HT7 receptor) is significantly overexpressed in the anterior cortex of IL-1β-exposed animals, suggesting it as a potential therapeutic target. LP-211 is a specific high-affinity HTR7 agonist that crosses the blood–brain barrier (BBB). When co-injected with IL-1β, LP-211 treatment prevented glial reactivity, the down-regulation of myelin-associated proteins, and the apparition of anxiety-like phenotypes. Thus, HTR7 may represent an innovative therapeutic target to protect the developing brain from preterm brain injuries.

Hormonal therapies up-regulate MANF and overcome female susceptibility to immune checkpoint inhibitor myocarditis.

Immune checkpoint inhibitors (ICIs) have been increasingly used in combination for cancer treatment but are associated with myocarditis. Here, we report that tumor-bearing mice exhibited response to treatment with combinatorial anti-programmed cell death 1 and anti-cytotoxic T lymphocyte antigen-4 antibodies but also presented with cardiovascular toxicities observed clinically with ICI therapy, including myocarditis and arrhythmia. Female mice were preferentially affected with myocarditis compared to male mice, consistent with a previously described genetic model of ICI myocarditis and emerging clinical data. Mechanistically, myocardial tissue from ICI-treated mice, the genetic mouse model, and human heart tissue from affected patients with ICI myocarditis all exhibited down-regulation of MANF (mesencephalic astrocyte-derived neurotrophic factor) and HSPA5 (heat shock 70-kDa protein 5) in the heart; this down-regulation was particularly notable in female mice. ICI myocarditis was amplified by heart-specific genetic deletion of mouse Manf and was attenuated by administration of recombinant MANF protein, suggesting a causal role. Ironically, both MANF and HSPA5 were transcriptionally induced by liganded estrogen receptor β and inhibited by androgen receptor. However, ICI treatment reduced serum estradiol concentration to a greater extent in female compared to male mice. Treatment with an estrogen receptor β-specific agonist and androgen depletion therapy attenuated ICI-associated cardiac effects. Together, our data suggest that ICI treatment inhibits estradiol-dependent expression of MANF/HSPA5 in the heart, curtailing the cardiomyocyte response to immune injury. This endocrine-cardiac-immune pathway offers new insights into the mechanisms of sex differences in cardiac disease and may offer treatment strategies for ICI myocarditis.

H1 HISTAMINE RECEPTOR SPECIFIC AGONISTS DIFFERENTIALLY MODIFIES TH1/TH2 CYTOKINE SYNTHESIS BY MONONUCLEAR AND DENDRITIC CELLS

<h3>Introduction</h3> Histamine exhibits immunoregulatory effects via H1 -H4 receptors. Histamine can produce multiple effects on cytokine synthesis: inhibit the release of IL-1, IL-2, IFN-γ, and TNF and increase the release of IL-5, IL-6 and IL-8. The role of H1 receptors in the synthesis of Th1/Th2 regulatory cytokines was assessed. <h3>Methods</h3> The concentration of Th1/Th2 immunoregulatory cytokines were assessed in supernatants of peripheral blood mononuclear cells (PBMC) and dendritic cells (DC) derived from PBMC of 6 healthy donors. PBMC and DC were cultivated in the presence of specific H1 histamine receptor agonist 2-methyl-histamine (2-MH) during 48h by Luminex xMAP technology using 45-plex Human Cytokine/Chemokine/Growth Factor Elisa Kit (eBioscience, Procarta) (10 -5 M/ml). <h3>Results</h3> Activation of H1 histamine receptors by 2-MH differentially impacted synthesis of Th1/Th2 regulatory cytokines by PBMC and DC derived from the same population of PBMC healthy donors. Decreased synthesis of IL-4, IL-12 and IL-21 occurred by1.48, 1.23 and 2.89 fold, respectively (p<0.01) from PBMC and no effect on the synthesis of the same cytokines by DC. Opposite effects on production of IL-10, gIFN and IL-17A were seen, with a decrease after cultivation of PBMC by 1.19-2.64 fold (p<0.01) but increased after cultivation of DC in the presence of 2-MH. Synthesis of IL-13, IL-18 and IL-27 increased by both DC and PBMC. The most pronounced effect occurred in production of IL-27 by PBMC in more than 27 fold. <h3>Conclusion</h3> H1 receptors regulate Th1/Th2 cytokine synthesis by PBMC and DC.

Lasmiditan abortive therapy for episodic migraine in Phase II/III randomized clinical trials: A meta-analysis.

Although migraine is common, there are very few treatment options. Recently, lasmiditan, a specific 5-HT1F agonist, has gained approval as abortive therapy for migraine. This meta-analysis and trial sequential analysis (TSA) was performed to analyze efficacy and tolerability of lasmiditan therapy for episodic migraine. Phase II and Phase III double-blinded placebo-controlled randomized controlled trials (RCTs) evaluating lasmiditan for episodic migraine were searched for from electronic databases. The risk of bias was estimated, data were extracted, and relative risk (RR) were calculated for efficacy and safety outcomes with a fixed/random effect model. Forest plots and funnel plots were created. TSA graph was plotted. Therapeutic gain with lasmiditan was calculated. Six high-quality RCTs were included with 7122 patients. Compared to placebo, lasmiditan demonstrated a significant proportion of migraineurs reporting freedom from headache, most bothersome symptom, headache response, no disability, global impression "very much/much better" 2 h posttreatment and sustained pain freedom at 24 and 48 h with 50, 100, 200, and 400 mg doses (RR range = 1.26-2.50). 39.3% of patients in the lasmiditan group (RR = 2.43) reported one or more treatment-emergent adverse event (TEAE). Dizziness, somnolence, paresthesia, fatigue, nausea, vertigo, hypoesthesia, asthenia, muscular weakness, lethargy, and malaise had a high incidence (RR range = 3.16-12.77). Most TEAEs were mild to moderate. No vasoconstriction-related TEAE was reported. Lasmiditan demonstrated efficacy as abortive therapy for episodic migraine with central nervous system-related side effects.

Activation of arcuate nucleus glucagon-like peptide-1 receptor-expressing neurons suppresses food intake

BackgroundCentral nervous system (CNS) control of metabolism plays a pivotal role in maintaining energy balance. In the brain, Glucagon-like peptide 1 (GLP-1), encoded by the proglucagon ‘Gcg’ gene, produced in a distinct population of neurons in the nucleus tractus solitarius (NTS), has been shown to regulate feeding behavior leading to the suppression of appetite. However, neuronal networks that mediate endogenous GLP-1 action in the CNS on feeding and energy balance are not well understood.ResultsWe analyzed the distribution of GLP-1R-expressing neurons and axonal projections of NTS GLP-1-producing neurons in the mouse brain. GLP-1R neurons were found to be broadly distributed in the brain and specific forebrain regions, particularly the hypothalamus, including the arcuate nucleus of the hypothalamus (ARC), a brain region known to regulate energy homeostasis and feeding behavior, that receives dense NTSGcg neuronal projections. The impact of GLP-1 signaling in the ARC GLP-1R-expressing neurons and the impact of activation of ARC GLP-1R on food intake was examined. Application of GLP-1R specific agonist Exendin-4 (Exn-4) enhanced a proportion of the ARC GLP-1R-expressing neurons and pro-opiomelanocortin (POMC) neuronal action potential firing rates. Chemogenetic activation of the ARC GLP-1R neurons by using Cre-dependent hM3Dq AAV in the GLP-1R-ires-Cre mice, established that acute activation of the ARC GLP-1R neurons significantly suppressed food intake but did not have a strong impact on glucose homeostasis.ConclusionsThese results highlight the importance of central GLP-1 signaling in the ARC that express GLP-1R that upon activation, regulate feeding behavior.

Adiponectin Suppresses Metastasis of Nasopharyngeal Carcinoma through Blocking the Activation of NF-κB and STAT3 Signaling.

Adiponectin is an adipocytokine with anti-inflammatory and anticancer properties. Our previous study has shown that blood adiponectin levels were inversely correlated to the risk of nasopharyngeal carcinoma (NPC), and that adiponectin could directly suppress the proliferation of NPC cells. However, the effect of adiponectin on NPC metastasis remains unknown. Here, we revealed in clinical studies that serum adiponectin level was inversely correlated with tumor stage, recurrence, and metastasis in NPC patients, and that low serum adiponectin level also correlates with poor metastasis-free survival. Coculture with recombinant adiponectin suppressed the migration and invasion of NPC cells as well as epithelial-mesenchymal transition (EMT). In addition, recombinant adiponectin dampened the activation of NF-κB and STAT3 signaling pathways induced by adipocyte-derived proinflammatory factors such as leptin, IL-6, and TNF-α. Pharmacological activation of adiponectin receptor through its specific agonist, AdipoRon, largely stalled the metastasis of NPC cells. Taken together, these findings demonstrated that adiponectin could not only regulate metabolism and inhibit cancer growth, but also suppress the metastasis of NPC. Pharmacological activation of adiponectin receptor may be a promising therapeutic strategy to stall NPC metastasis and extend patients' survival.

IL-18BP Alleviates Anxiety-Like Behavior Induced by Traumatic Stress via Inhibition of the IL-18R-NLRP3 Signaling Pathway in a Mouse Model of Hemorrhagic Shock and Resuscitation.

Psychological distress and posttraumatic stress, including anxiety, severely influence life quality. Previously, we reported that interleukin-18 (IL-18) was involved in pyroptosis-induced emotional changes in a rodent model of hemorrhagic shock and resuscitation (HSR). Here, we aimed to continue our investigation on the role of IL-18 binding protein (IL-18BP), which exhibits excellent anti-inflammatory effects as an IL-18 negative regulator. Mice were administered with an intraperitoneal injection of IL-18BP after HSR exposure and anxiety-like behavior was examined using the open-field test and elevated plus maze test. Moreover, the following variables post-HSR were measured: (1) the activation of astrocytes; (2) pyroptosis-associated factors including cleaved caspase-1, GSDMD, IL-18; (3) the roles of IL-18 receptor (IL-18R)-NOD-like receptor pyrin domain-containing-3 (NLRP3) signal with the application of the NLRP3 specific agonist or astrocyte-specific NLRP3 knockout mice. IL-18BP administration remarkably alleviated HSR-induced anxiety-like behavior, astrocytic activation, and increases in pyroptosis-associated factors, while NLRP3 agonist nigericin partially reversed IL-18BP-induced neuroprotective effects. Astrocyte-specific NLRP3 knockout mice exhibited relatively less anxiety-like behavior. Similarly, IL-18BP exhibited an anti-pyroptosis effect in astrocytes in an in vitro model of low oxygen-glucose deprivation. These findings offer unique perspectives on HSR-induced posttraumatic stress and indicate that inhibition of IL-18R-NLRP3 signal via IL-18BP can attenuate astrocytic activation and pyroptosis, broadening the therapeutic landscape for patients with psychological distress and posttraumatic stress.

The genomic response of human granulosa cells (KGN) to melatonin and specific agonists/antagonists to the melatonin receptors

Melatonin is a known modulator of follicle development; it acts through several molecular cascades via binding to its two specific receptors MT1 and MT2. Even though it is believed that melatonin can modulate granulosa cell (GC) functions, there is still limited knowledge of how it can act in human GC through MT1 and MT2 and which one is more implicated in the effects of melatonin on the metabolic processes in the dominant follicle. To better characterize the roles of these receptors on the effects of melatonin on follicular development, human granulosa-like tumor cells (KGN) were treated with specific melatonin receptor agonists and antagonists, and gene expression was analyzed with RNA-seq technology. Following appropriate normalization and the application of a fold change cut-off of 1.5 (FC 1.5, p ≤ 0.05) for each treatment, lists of the principal differentially expressed genes (DEGs) are generated. Analysis of major upstream regulators suggested that the MT1 receptor may be involved in the melatonin antiproliferative effect by reprogramming the metabolism of human GC by activating the PKB signaling pathway. Our data suggest that melatonin may act complementary through both MT1 and MT2 receptors to modulate human GC steroidogenesis, proliferation, and differentiation. However, MT2 receptors may be the ones implicated in transducing the effects of melatonin on the prevention of GC luteinization and follicle atresia at the antral follicular stage through stimulating the PKA pathway.

Ganoderic Acid A Inhibits High Glucose-Induced Oxidative Stress and Extracellular Matrix Accumulation in Rat Glomerular Mesangial Cells.

Objective We aimed to investigate the role of ganoderic acid A (GAA) in glomerular mesangial cells (GMCs) under high glucose (HG). Methods GMCs were pretreated with GAA and then cultured under HG condition for 24 h. Cell proliferation was measured by CCK-8 assay. The production of intracellular ROS was determined using DCFH-DA. The activities of SOD and CAT were measured using ELISA kits. The expressions of NOX2, NOX4, fibronectin (FN), collagen IV (col IV), p38, and p-p38 were detected by western blot. Results GAA suppressed GMC proliferation in response to HG stimulation. GAA significantly attenuated HG-caused increase in ROS production and decreases in SOD and CAT activities in GMCs. In addition, the increased expressions of NOX2 and NOX4 and NOX activity in HG-induced GMCs were significantly decreased by GAA. Furthermore, GAA greatly inhibited the levels of FN and col IV in HG-stimulated GMCs. Mechanistic investigations showed that HG caused activation of p38 MAPK pathway, whereas the induction was mitigated by GAA. Notably, the specific agonist of p38 MAPK pathway (P79350) reversed the effects of GAA on GMCs. Conclusion GAA protected GMCs from HG-induced oxidative stress and ECM production, which was mediated by the inhibition of the p38 MAPK pathway.

Citrullination of histoneH3 in neutrophil via CXCL1 enhances neutrophil adhesion to femoral artery of LDLR−/− mice fed HFD

Abstract Background Vascular inflammation plays an important role in the development of atherosclerosis. Previously we have shown that a high-fat diet (HFD) increased neutrophil adhesion to the vascular intima in wild-type (wt) mice (Osaka M. Sci Rep. 2016). However, the involvement of neutrophils in atherosclerosis-related vascular inflammation is not well known. Purpose This study examined that neutrophil extracellular trap (NETs) or the hypercitrullination of histone H3 in neutrophils enhances neutrophil adhesion to atheroprone-arteries in LDL receptor null (LDLR−/−) mice. Methods We observed leukocyte adhesion in the femoral artery of LDLR−/− mice fed normal chow (NC) or HFD, and determined leukocyte subtype that adhered on vascular endothelium under neutrophil or monocyte depletion using intravital microscopy. Importantly, neutrophil adhesion was examined under the administration of TDFA which inhibits NETs and citrullination of histone H3, in LDLR−/− mice fed HFD. Furthermore, immunohistochemistry for citrullinated histone H3 in peripheral neutrophils of mice was examined. Comprehensive cytokine/chemokine analysis for a plasma of mice was performed to determine the factors citrullinating histone H3 in LDLR−/− mice. Moreover, these mice were treated with a novel specific PPARα agonist, to reduce the elevation of plasma triglyceride levels. Results Leukocyte adhesion in LDLR−/− mice fed HFD significantly increased compared to NC. More interestingly, it significantly enhanced compared to wt mice fed HFD. Furthermore, neutrophil depletion rather than monocyte depletion diminished leukocyte adhesion, suggesting that the leukocyte subtype that adhered in LDLR−/− mice fed HFD was neutrophil. Neutrophil adhesion in these mice significantly was reduced by the administration of TDFA, suggesting a pivotal role for histone H3 citrullination in neutrophil adhesion. Moreover, citrullination of histone H3 in neutrophils from LDLR−/− mice fed HFD but not from those without HFD was significantly enhanced. In addition, comprehensive cytokine/chemokine analysis revealed an increase of CXCL1 in plasma of LDLR−/− mice fed HFD. CXCL1 enhanced neutrophil adhesion to HUVECs, and the adhesion significantly decreased by the treatment of TDFA to neutrophil in vitro non-static adhesion assay. These results showed that CXCL1 enhanced neutrophil adhesion in LDLR−/− mice fed HFD through citrullination. Furthermore, when these mice were treated with PPARα agonist, observed histone citrullination, as well as neutrophil adhesion, was significantly reduced. Conclusion These results suggest that HFD induced histone citrullination in neutrophils in LDLR−/− mice and PPARα agonist plays a role during hypertriglyceridemia-mediated vascular inflammation in atherosclerosis. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research(C)

Biased Signaling through G Protein-coupled Receptors

It is well-established that G protein-coupled receptors (GPCRs) transduce signals into cells using G proteins as intermediary molecules. β-Arrestins are molecules involved in regulating GPCRs; however, it has recently been reported that β-arrestins can also mediate signaling through GPCRs. Signaling through G proteins or β-arrestins can be activated selectively using specific agonists; of the latter, those that can selectively activate either G proteins or β-arrestins are called biased agonists. The clinical use of biased agonists could potentially induce fewer side effects. However, partial agonists can also explain the mechanism of G protein-biased agonists; thus, appropriate assay systems must be considered. Endogenous agonists are known to bind to orthosteric and allosteric sites in the agonist binding site, and the allosteric site is associated with the activity of biased agonists. This current review presents a detailed discussion of biased agonists.

TRPV1 channels in nitric oxide-mediated signalling: insight on excitatory transmission in rat CA1 pyramidal neurons.

Nitric oxide (NO) is a fascinating signalling molecule implicated in a plethora of biological functions, especially at the synaptic level. Exploring neurotransmission in the hippocampus could be instrumental in the individuation of putative targets for nitric-oxide mediated neuromodulation, especially in terms of the potential repercussions on fundamental processes i.e. synaptic plasticity and excitability-related phenomena. Among these targets, endovanilloid signalling constitutes an object of study since Transient Receptors Vanilloid type 1 (TRPV1) channels possess a NO-sensitive gate modulating its activation. Also, NO has been referred to as a mediator for numerous endocannabinoid effects. Notwithstanding, the linkage between TRPV1 and NO systems in neuromodulation still remains elusive. To this end, we aim at investigating the involvement of TRPV1 in nitric oxide-mediated influence on hippocampal processes. Electrophysiological whole-cell recordings in CA1 pyramidal neurons were applied to evaluate excitatory neurotransmission in rat brain slices. Indeed, miniature excitatory postsynaptic currents (mEPSCs) were analysed upon pharmacological manipulation of TRPV1 and NO signalling pathways. In detail, only the administration of the specific TRPV1 exogenous agonist - capsaicin - reduced the frequency and amplitude of mEPSC similarly to the inhibitor of neuronal nitric oxide synthase (nNOS), 7-nitroindazole (7NI). In contrast, capsazepine, TRPV1 antagonist, does not influence excitatory transmission. The combined TRPV1 activation and nNOS blockade confirm the presence of a putative common mechanism. When we administered the endovanilloid-endocannabinoid ligand, i.e. anandamide, we unveiled a potentiation of neurotransmission that was selectively reverted by 7NI. Our data suggest that nitric oxide influences TRPV1 hippocampal signalling since these channels are not constitutively active, but can be "on-demand" activated to modulate excitation in CA1 pyramidal neurons, and that this effect is linked to nitric oxide production.

The Interplay of GPER1 with 17β-Aminoestrogens in the Regulation of the Proliferation of Cervical and Breast Cancer Cells: A Pharmacological Approach.

The G-protein-coupled receptor for estrogen (GPER1) is a transmembrane receptor involved in the progression and development of various neoplasms whose ligand is estradiol (E2). 17β-aminoestrogens (17β-AEs) compounds, analogs to E2, are possible candidates for use in hormone replacement therapy (HRT), but our knowledge of their pharmacological profile is limited. Thus, we explored the molecular recognition of GPER1 with different synthetic 17β-AEs: prolame, butolame, and pentolame. We compared the structure and ligand recognition sites previously reported for a specific agonist (G1), antagonists (G15 and G36), and the natural ligand (E2). Then, the biological effects of 17β-AEs were analyzed through cell viability and cell-cycle assays in two types of female cancer. In addition, the effect of 17β-AEs on the phosphorylation of the oncoprotein c-fos was evaluated, because this molecule is modulated by GPER1. Molecular docking analysis showed that 17β-AEs interacted with GPER1, suggesting that prolame joins GPER1 in a hydrophobic cavity, similarly to G1, G15, and E2. Prolame induced cell proliferation in breast (MCF-7) and cervical cancer (SIHA) cells; meanwhile, butolame and pentolame did not affect cell proliferation. Neither 17β-AEs nor E2 changed the activation of c-fos in MCF-7 cells. Meanwhile, in SIHA cells, E2 and 17β-AEs reduced c-fos phosphorylation. Thus, our data suggest that butolame and pentolame, but not prolame, could be used for HRT without presenting a potential risk of inducing breast- or cervical-cancer-cell proliferation. The novelty of this work lies in its study of compound analogs to E2 that may represent important therapeutic strategies for women in menopause, with non-significant effects on the cell viability of cancer cells. The research focused on the interactions of GPER1, a molecule recently associated with promoting and maintaining various neoplasms.

Topical Application of Adenosine A2-Type Receptor Agonists Prevents Contact Hypersensitivity Reactions in Mice by Affecting Skin Dendritic Cells

Adenosine (Ado) produced by skin and skin migratory CD73+ dendritic cells is critically involved in tolerance tohaptens. We therefore investigated the use of Ado receptor agonists for the treatment of contact hypersensitivity reactions. A2A- 4-[2-[[6-Amino-9-(N-ethyl-β-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino] ethyl]benzenepropanoic acid hydrochloride (CGS) and A2B- 2-[[6-Amino-3,5-dicyano-4-[4-[cyclopropylmethoxy]phenyl]-2-pyridinyl]thio]-acetamide (BAY) specific Ado receptor agonists were epicutaneously applied to the skin before sensitization and challenge with DNFB. Both agonists reduced ear swelling compared with solvent controls. This was accompanied by fewer activated T cells in the skin after the challenge and by higher numbers of T cells expressing anergic markers such as LAG-3, CD137, PD-1, CD272, and TIM-3 in the lymph nodes of CGS-treated groups. In ear tissue, Ado receptor agonist treatment reduced the production of proinflammatory cytokines and chemokines as well as the infiltration by neutrophils after sensitization. Moreover, reduced numbers of skin migratory dendritic cells producing less IL-12 and exhibiting lower expression of CD86 were recorded in lymph nodes after sensitization. In cocultures of skin migratory dendritic cells from CGS-treated mice with T cells, reduced proliferation of T cells and decreased secretion of proinflammatory cytokines compared with that of solvent controls were apparent. In conclusion, topical application of Ado receptor agonists to the skin prevents sensitization of T cells against haptens by reducing the migration and activation of skin migratory dendritic cells.

Prostaglandins and calprotectin are genetically and functionally linked to the Inflammatory Bowel Diseases.

BackgroundGenome wide association studies (GWAS) have identified and validated more than 200 genomic loci associated with the inflammatory bowel disease (IBD), although for most the causal gene remains unknown. Given the importance of myeloid cells in IBD pathogenesis, the current study aimed to uncover the role of genes within IBD genetic loci that are endogenously expressed in this cell lineage.MethodsThe open reading frames (ORF) of 42 genes from IBD-associated loci were expressed via lentiviral transfer in the THP-1 model of human monocytes and the impact of each of these on the cell’s transcriptome was analyzed using a RNA sequencing-based approach. We used a combination of genetic and pharmacologic approaches to validate our findings in the THP-1 line with further validation in human induced pluripotent stem cell (hiPSC)-derived-monocytes.ResultsThis functional genomics screen provided evidence that genes in four IBD GWAS loci (PTGIR, ZBTB40, SLC39A11 and NFKB1) are involved in controlling S100A8 and S100A9 gene expression, which encode the two subunits of calprotectin (CP). We demonstrated that increasing PTGIR expression and/or stimulating PTGIR signaling resulted in increased CP expression in THP-1.This was further validated in hiPSC-derived monocytes. Conversely, knocking-down PTGIR endogenous expression and/or inhibiting PTGIR signaling led to decreased CP expression. These analyses were extended to the known IBD gene PTGER4, whereby its specific agonist also led to increased CP expression. Furthermore, we demonstrated that the PTGIR and PTGER4 mediated control of CP expression was dependent on signaling via adenylate cyclase and STAT3. Finally, we demonstrated that LPS-mediated increases in CP expression could be potentiated by agonists of PTGIR and PTGER4, and diminished by their antagonists.ConclusionOur results support a causal role for the PTGIR, PTGER4, ZBTB40, SLC39A11 and NFKB1 genes in IBD, with all five genes regulating the expression of CP in myeloid cells, as well as potential roles for the prostacyclin/prostaglandin biogenesis and signaling pathways in IBD susceptibility and pathogenesis.