Ligands and Signaling of Mas-Related G Protein-Coupled Receptor-X2 in Mast Cell Activation.

Mas-related G protein-coupled receptor-X2 (MRGPRX2) is known as a novel receptor to activate mast cells (MCs). MRGPRX2 plays a dual role in promoting MC-dependent host defense and immunomodulation and contributing to the pathogenesis of pseudo-allergic drug reactions, pain, itching, and inflammatory diseases. In this article, we discuss the possible signaling pathways of MCs activation mediated by MRGPRX2 and summarize and classify agonists and inhibitors of MRGPRX2 in MCs activation. MRGPRX2 is a low-affinity and low-selectivity receptor, which allows it to interact with a diverse group of ligands. Diverse MRGPRX2 ligands utilize conserved residues in its transmembrane (TM) domains and carboxyl-terminus Ser/Thr residues to undergo ligand binding and G protein coupling. The coupling likely initiates phosphorylation cascades, induces Ca2+ mobilization, and causes degranulation and generation of cytokines and chemokines via MAPK and NF-κB pathways, resulting in MCs activation. Agonists of MRGPRX2 on MCs are divided into peptides (including antimicrobial peptides, neuropeptides, MC degranulating peptides, peptide hormones) and nonpeptides (including FDA-approved drugs). Inhibitors of MRGPRX2 include non-selective GPCR inhibitors, herbal extracts, small-molecule MRGPRX2 antagonists, and DNA aptamer drugs. Screening and classifying MRGPRX2 ligands and summarizing their signaling pathways would improve our understanding of MRGPRX2-mediated physiological and pathological effects on MCs.

Dual epigenetic agents plus rituximab-gemcitabine-oxaliplatin as salvage treatment in relapsed/refractory diffuse large B-cell lymphoma patients failure of salvage chemotherapy.

Refractory/relapsed (R/R) diffuse large B-cell lymphoma (DLBCL) patients' failure of salvage chemotherapy had extremely worse prognoses. Herein, 14 R/R DLBCL patients failed to salvage chemotherapy were exposed to dual epigenetic agents (Chidamide 30 mg biw*2w and Decitabine 10 mg/m2 qd*d1-d5) and sequential R-GemOx (rituximab 375 mg/m2 qd d6; gemcitabine 1 g/m2 d7, d14; and oxaliplatin 100 mg/m2 d7) for further salvage chemotherapy. Finally, 11/14(78.6%) patients achieved overall response with 6/14(42.9%) achieving complete remission and 2-year overall survival (OS)/progression free survival (PFS) rate was 42.7%, extremely higher than reported previously. Further subgroup analysis demonstrated that 2-year OS/PFS rate was significantly higher in patients achieved complete/partial remission or with low international prognosis index (IPI 0-2) than that in patients with steady disease or high IPI (3-5). Common grade 3-4 adverse events were hematological toxicities. All toxicities were transient and reversible. Our report implicates that combination of dual epigenetic agents and R-GemOx is a safe and promising alternative for R/R DLBCL patients.

Secondhand cigarette smoke induces increased expression of contractile endothelin receptors in rat coronary arteries via a MEK1/2 sensitive mechanism.

OBJECTIVES: Cigarette smoke, a strong risk factor for cardiovascular diseases, upregulates contractile endothelin (ET) receptors in coronary arteries. The present study examined the effects of second hand cigarette smoke exposure on the contractile endothelin receptors and the role of the MEK1/2 pathway in rat coronary arteries. Design: Rats were exposed to secondhand smoke (SHS) for 8 weeks followed by intraperitoneal injection of a MEK1/2 inhibitor, U0126 daily for another 4 weeks. Contractile responses of isolated coronary arteries were recorded by a sensitive wire myograph. The receptor protein expression levels were examined by Western blotting. Results: The results showed that SHS in vivo caused increased expression of ET receptors ETA and ETB, and that the MEK1/2 blocker U0126 significantly reversed SHS exposure-increased ETA-mediated contractile responses and protein levels. Similar alterations were observed in ETB receptors. U0126 showed dose-dependent effects on SHS-induced response on contractile property and protein levels of the ETB receptor. However, only the higher dose U0126 (15 mg/kg) had inhibitory effects on the ETA receptor. Conclusions: Taken together, our data show that SHS increases contractile ET receptors and MEK1/2 pathway inhibitor offsets SHS exposure-induced ETA and ETB receptor upregulation in rat coronary arteries.

Hydrogen-rich water alleviates cyclosporine A-induced nephrotoxicity via the Keap1/Nrf2 signaling pathway.

Oxidative stress induced by long-term cyclosporine A (CsA) administration is a major cause of chronic nephrotoxicity, which is characterized by tubular atrophy, tubular cell apoptosis, and interstitial fibrosis in the progression of organ transplantation. Although hydrogen-rich water (HRW) has been used to prevent various oxidative stress-related diseases, its underlying mechanisms remain unclear. This study investigated the effects of HRW on CsA-induced nephrotoxicity and its potential mechanisms. After administration of CsA (25 mg/kg/day), rats were treated with or without HRW (12 mL/kg) for 4 weeks. Renal function and vascular activity were investigated. Histological changes in kidney tissues were analyzed using Masson's trichrome and terminal deoxynucleotidyl transferase dUTP nick-end labeling stains. Oxidative stress markers and the activation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway were also measured. We found that CsA increased the levels of reactive oxygen species (ROS) and malonaldehyde (MDA), but it reduced glutathione (GSH) and superoxide dismutase (SOD) levels. Such alterations induced vascular dysfunction, tubular atrophy, interstitial fibrosis, and tubular apoptosis. This was evident secondary to an increase in urinary protein, serum creatinine, and blood urea nitrogen, ultimately leading to renal dysfunction. Conversely, HRW decreased levels of ROS and MDA while increasing the activity of GSH and SOD. This was accompanied by an improvement in vascular and renal function. Moreover, HRW significantly decreased the level of Keap1 and increased the expression of Nrf2, NADPH dehydrogenase quinone 1, and heme oxygenase 1. In conclusion, HRW restored the balance of redox status, suppressed oxidative stress damage, and improved kidney function induced by CsA via activation of the Keap1/Nrf2 signaling pathway.

Establishing a rat model for the study of vitamin K deficiency.

The main vitamin K-deficient model, minidose warfarin, is different from the pathological mechanism of vitamin K deficiency, which is a shortage of vitamin K. The objective of this study was to establish a new method of vitamin K-deficient model combining a vitamin K-deficient diet with the intragastrical administration of gentamicin in rats. The clotting was assayed by an automated coagulation analyser. The plasma PIVKA-II was assayed by ELISA. The vitamin K status was detected by an HPLC-fluorescence system. In the diet- and gentamicin-induced vitamin K-deficient 14-day group, the rats had undetected vitamin K1 and vitamin K2 in the liver and a prolonged APTT. In the 21-day group, there was also a prolonged PT and a decrease of the FIX activities. In the 28-day group, the undetected vitamin K1 and vitamin K2, the prolonged PT and APTT, and the decrease of the FII, FVII, FIX, and FX activities prompted the suggestion that there were serious deficiencies of vitamin K and vitamin K-dependent coagulation in rats. It is suggested that the diet- and gentamicin-induced vitamin K-deficient 14-day or 21-day model can be used for studies related to the status of vitamin K. The vitamin K-deficient 28-day model can be applied to research involving both the status of vitamin K and of vitamin K-dependent coagulation. In conclusion, the combination of a vitamin K-deficient diet with the administration of gentamicin results in a useful model of vitamin K-deficieny.

The effects of MEK1/2 inhibition on cigarette smoke exposure-induced ET receptor upregulation in rat cerebral arteries.

Cigarette smoking, a major stroke risk factor, upregulates endothelin receptors in cerebral arteries. The present study examined the effects of MEK1/2 pathway inhibition on cigarette smoke exposure-induced ET receptor upregulation. Rats were exposed to the secondhand smoke (SHS) for 8weeks followed by intraperitoneal injection of MEK1/2 inhibitor, U0126 for another 4weeks. The urine cotinine levels were assessed with high-performance liquid chromatography. Contractile responses of isolated cerebral arteries were recorded by a sensitive wire myograph. The mRNA and protein expression levels of receptor and MEK/ERK1/2 pathway molecules were examined by real-time PCR and Western blotting, respectively. Cerebral artery receptor localization was determined with immunohistochemistry. The results showed the urine cotinine levels from SHS exposure group were significantly higher than those from the fresh group. In addition, the MEK1/2 inhibitor, U0126 significantly reduced SHS exposure-increased ETA receptor mRNA and protein levels as well as contractile responses mediated by ETA receptors. The immunoreactivity of increased ETA receptor expression was primarily cytoplasmic in smooth muscle cells. In contrast, ETB receptor was noted in endothelial cells. However, the SHS-induced decrease in endothelium-dependent relaxation was unchanged after U0126 treatment. Furthermore, SHS increased the phosphorylation of MEK1/2 and ERK1/2 protein in cerebral arteries. By using U0126 could inhibit the phosphorylated ERK1/2 protein but not MEK1/2. Taken together, our data show that treatment with MEK1/2 pathway inhibitor offsets SHS exposure-induced ETA receptor upregulation in rat cerebral arteries.

Transcriptome sequencing reveals CHD1 as a novel fusion partner of RUNX1 in acute myeloid leukemia with t(5;21)(q21;q22).

BACKGROUND: RUNX1/AML1, which is a Runt family transcription factor critical for normal hematopoiesis, is frequently mutated or translocated in a broad spectrum of hematopoietic malignancies. FINDINGS: We describe here the case of a 54-year-old female developed acute myeloid leukemia with a t(5;21)(q21;q22). Transcriptome sequencing identified the chromodomain-helicase-DNA-binding protein 1 gene, CHD1, as a novel partner gene of RUNX1. Furthermore, the patient was found to harbor FLT3-ITD mutation, which might collaborated with CHD1-RUNX1 in the development of acute myeloid leukemia. CONCLUSIONS: We have identified CHD1 as the RUNX1 fusion partner in acute myeloid leukemia with t(5;21)(q21;q22).

An optimal initial tension for rat basilar artery in wire myography.

AIMS: The aim of the present study was to determine the optimal initial tension for the rat basilar artery when using wire myography. METHODS: Rat basilar arteries were mounted in myograph baths. A normalization procedure was performed. K(+)-rich (60mM) buffer solution-induced tension was measured in different initial tensions. RESULTS: The initial tension of the basilar artery increased from 0.47 to 2.68mN/mm. Contractile tension was also elevated along with the initial tension. When the initial tension reached 1.63mN/mm, K(+)-induced contractile tension of basilar artery achieved its maximum. Thereafter, contractile tension declined as initial tension increased. The duration of equilibration time did not affect K(+)-induced contractile tension. CONCLUSION: The optimal initial tension is 1.63±0.01mN/mm in rat basilar arteries when using wire myography.

H2S induces vasoconstriction of rat cerebral arteries via cAMP/adenylyl cyclase pathway.

Hydrogen sulfide (H2S), traditionally known for its toxic effects, is now involved in regulating vascular tone. Here we investigated the vasoconstrictive effect of H2S on cerebral artery and the underlying mechanism. Sodium hydrosulfide (NaHS), a donor of H2S, concentration-dependently induced vasoconstriction on basilar artery, which was enhanced in the presence of isoprenaline, a ß-adrenoceptor agonist or forskolin, an adenylyl cyclase activator. Administration of NaHS attenuated the vasorelaxant effects of isoprenaline or forskolin. Meanwhile, the NaHS-induced vasoconstriction was diminished in the presence of 8B-cAMP, an analog of cAMP, but was not affected by Bay K-8644, a selective L-type Ca(2+) channel agonist. These results could be explained by the revised effects of NaHS on isoprenaline-induced cAMP elevation and forskolin-stimulated adenylyl cyclase activity. Additionally, NaHS-induced vasoconstriction was enhanced by removing the endothelium or in the presence of L-NAME, an inhibitor of nitric oxide synthase. L-NAME only partially attenuated the effect of NaHS which was given together with forskolin on the pre-contracted artery. In conclusion, H2S induces vasoconstriction of cerebral artery via, at least in part, cAMP/adenylyl cyclase pathway.