Ren Guo

Calcitonin gene-related peptide-mediated cardioprotection of postconditioning in isolated rat hearts.

Previous studies have demonstrated that endogenous calcitonin gene-related peptide (CGRP) plays an important role in mediation of ischemic preconditioning. In the present study, we tested whether CGRP is also involved in mediation of the protective effects of postconditioning in isolated rat hearts. Sixty minutes of left coronary artery occlusion and followed by 60 min of reperfusion caused a significant decrease in cardiac function and a significant increase in creatine kinase (CK) release and infarct size. Postconditioning with three cycles of 1-min ischemia and 1-min reperfusion produced a marked improvement of cardiac function and decreased CK release and infarct size, concomitantly with an increase in the release of CGRP release in coronary effluent. However, the cardioprotection afforded by postconditioning was abolished by CGRP 8-37 (10(-7) M), a selective CGRP receptor antagonist, or pretreatment with capsaicin (50 mg/kg, s.c.), which depletes transmitters in sensory nerves. Exogenous CGRP (5 x 10(-9) M) administration of CGRP reappeared postconditioning-like cardioprotection in the rats pretreated with capsaicin. These results suggest that the protective effects of ischemic postconditioning are related to stimulation of endogenous CGRP release in rat hearts.

Evidence for involvement of the CD40/CD40L system in post-stroke epilepsy.

Post-stroke epilepsy (PSE) has a negative effect on stroke prognosis and quality of life. The CD40/CD40L system is reported to be involved in the progression of multiple disease states. We investigated the association between functional polymorphism of CD40 and PSE susceptibility, and we also explored the role of the CD40/CD40L system in PSE. A case-control study was performed in 410 ischemic stroke (IS) patients and in 389 PSE patients. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The CD40 mRNA and protein levels were determined by real-time PCR and western blotting, respectively. The plasma sCD40L level was detected using an ELISA kit. The frequency of the T allele in PSE patients was significantly higher than in IS patients (P<0.05). The plasma sCD40L level was significantly higher in the PSE patients than in the healthy controls and IS patients (P<0.01, P<0.05, respectively). The peripheral blood mononuclear cells (PBMCs) from PSE patients showed significantly higher CD40 mRNA and protein expression than the healthy controls and IS patients (P<0.01, P<0.05, respectively). In the PSE patients, the T-allele carriers showed increased plasma sCD40L levels and increased CD40 mRNA expression. Our study suggested that the T allele of the CD40 -1C/T polymorphism may be associated with PSE susceptibility. The CD40/CD40L system is involved in the process of PSE.

The ALDH2 rs671 polymorphism affects post-stroke epilepsy susceptibility and plasma 4-HNE levels.

Recent studies have demonstrated the protective effect of mitochondrial aldehyde dehydrogenase 2 (ALDH2) in cardiovascular diseases. Increased levels of the potential ALDH2 substrate 4-hydroxynonenal (4-HNE) are involved in myocardial/cerebral ischemia accompanied by a high level of oxidative stress. In this investigation, we first performed a case-control study to explore the potential association of ALDH2 rs671 polymorphism and post-stroke epilepsy (PSE). Then, we performed an in vitro study to determine whether the overexpression of ALDH2 could decrease the level of oxidative stress and the apoptosis ratio induced by 4-HNE. There was a significant difference in the distribution of the allele and genotype frequencies of the rs671 polymorphism between PSE patients and ischemic stroke (IS) patients. Individuals with the rs671 A allele showed significantly higher levels of plasma 4-HNE. The overexpression of ALDH2 partially blocked the increased levels of malondialdehyde (MDA), reactive oxygen species (ROS) and apoptosis ratio induced by 4-HNE and also partially restored the ALDH2 activity in PC12 cells; these effects were reversed in the presence of εV1-2. Our results suggest that the ALDH2 rs671 polymorphism is associated with PSE susceptibility and affects the 4-HNE levels. Targeting ALDH2 might be a useful strategy for the treatment or prevention of PSE.

NF-kappaB p65 modulates the telomerase reverse transcriptase in the HepG2 hepatoma cell line

Nuclear factor-kappa B (NF-kappaB) regulates the expression of various genes, several genes involved in inflammation and tumorigenesis, including those of the liver. A role for NF-kappaB has been implicated in the pathogenesis of hepatocellular carcinoma. This transcription factor can regulate hTERT gene transcription. Expression of hTERT was found to be at high levels in hepatocellular carcinoma. However, positive effects of NF-kappaB on hTERT protein synthesis in HepG(2) cells are unknown. In this study, we show that LPS (specific binding to TLR4 to activate NF-kappaB) was positive for NF-kappaB p65 mRNA expression and activation, and also up-regulated hTERT mRNA and protein expressions at 36h in a dose-dependent manner. In contrast, MG-132 (blocking the activity of 26S proteasome and thereby preventing nuclear translocation of NF-kappaB) significantly inhibited activation of NF-kappaB and mRNA expression. And also reduced the expression of hTERT at both mRNA and protein levels at 36h in a dose-dependent manner. Furthermore, dexamethasone inhibited LPS-induced activation of NF-kappaB and expression of the hTERT in HepG(2) cells. These findings suggest that NF-kappaB may modulate hTERT mRNA level, importantly, in protein level in HepG(2) cells and dexamethasone inhibits LPS-induced hTERT via blocking NF-kappaB.

Evidence for Involvement of Calcitonin Gene-Related Peptide in Nitroglycerin Response and Association With Mitochondrial Aldehyde Dehydrogenase-2 (ALDH2) Glu504Lys Polymorphism

OBJECTIVES This study sought to determine whether calcitonin gene-related peptide (CGRP) is involved in glyceryl trinitrate (GTN) response in humans, and its association with mitochondrial aldehyde dehydrogenase-2 (ALDH2) Glu504Lys (ALDH2*2) polymorphism. BACKGROUND In animal models, CGRP contributes to the cardiovascular effects of GTN. The enzyme principally responsible for GTN bioactivation is ALDH2. The common ALDH2*2 polymorphism is associated with a lack of GTN efficacy. METHODS In 18 ALDH2*2-genotyped Chinese volunteers, we observed the changes in plasma concentrations of CGRP after sublingual GTN administration and its correlation with GTN response, and assessed the expression of CGRP messenger ribonucleic acid (mRNA) in cultured peripheral blood mononuclear cells (PBMCs) pre-treated with 10(-5) mol/l GTN. RESULTS In contrast to carriers of the ALDH2*2 allele, ALDH2*1/*1 homozygotes showed a significantly higher extent of absolute changes in both systolic blood pressure (DeltaSBP) and HR (DeltaHR) at several time points after GTN administration. Plasma concentrations of CGRP were increased significantly 12 min after GTN administration, the percentage increase in plasma concentrations of CGRP correlated positively with both DeltaSBP and DeltaHR, and percentage increase in plasma concentrations of CGRP was significantly higher in ALDH2*1/*1 homozygotes. In addition, PBMCs from ALDH2*1/*1 homozygotes showed a higher-fold increase in both CGRP I and CGRP II mRNA after GTN stimulation, and the GTN-induced increase in CGRP mRNA expression in PBMCs from ALDH2*1/*1 homozygotes was inhibited by the ALDH2 inhibitor chloral hydrate. CONCLUSIONS We found that CGRP is associated with the cardiovascular effect of GTN through an ALDH2-dependent pathway in humans.

miRNA-145 inhibits VSMC proliferation by targeting CD40

Recent studies have demonstrated functions of miR-145 in vascular smooth muscle cells (VSMCs) phenotypes and vascular diseases. In this study, we aim to determine whether CD40 is involved in miR-145 mediated switch of VSMC phenotypes. In cultured VSMCs, the effects of miR-145 and CD40 on TNF-α, TGF-β, and Homocysteine (Hcy) induced cell proliferation were evaluated by over-expression of miR-145 or by siRNA-mediated knockdown of CD40. We also used ultrasound imaging to explore the effect of miR-145 on carotid artery intima-media thickness (CIMT) in atherosclerotic cerebral infarction (ACI) patients. The results showed 50 ng/mL TNF-α, 5 ng/mL TGF-β, and 500 μmol/L Hcy significantly increased the expression of CD40, both at mRNA and protein levels, and also induced the proliferation of VSMCs. We found that over-expression of miR-145 significantly inhibited the expression of CD40 and the differentiation of VSMCs, and over-expression of miR-145 decreased IL-6 levels in VSMC supernatants. In ACI patients, the lower expression of miR-145 was associated with thicker CIMT and higher levels of plasma IL-6. Our results suggest that the miR-145/CD40 pathway is involved in regulating VSMC phenotypes in TNF-α, TGF-β, and Hcy induced VSMCs proliferation model. Targeting miR-145/CD40 might be a useful strategy for treating atherosclerosis.

No effect of MDR1 C3435T polymorphism on oral pharmacokinetics of telmisartan in 19 healthy Chinese male subjects.

Abstract Background: Considerable interindividual differences in both drug response and pharmacokinetics of telmisartan have been identified. This study was designed to investigate the influence of MDR1 C3435T polymorphism on pharmacokinetics of telmisartan after a single oral dose in healthy Chinese volunteers. Methods: A total of 61 unrelated male volunteers were genotyped for MDR1 C3435T polymorphism by using the polymerase chain reaction-restriction fragment length polymorphism method. Six 3435CC homozygotes, eight 3435CT heterozygotes, and five 3435TT homozygotes were randomly selected and received a single oral dose of 40 mg telmisartan. Plasma concentrations of telmisartan were determined by the high performance liquid chromatography-mass spectrometry method up to 48 h after telmisartan administration. Results: Interindividual variation for tmax, Cmax, t1/2, AUC0–48, AUC0–∞, and clearance (CL) for telmisartan was approximately 6-, 33-, 16-, 17-, 20-, and 20-fold, respectively. Cmax (p=0.010), t1/2 (p=0.029) and CL (p=0.010) of telmisartan were not normally distributed. MDR1 3435TT homozygotes seemed to show increases in Cmax, tmax, t1/2, AUC0–48, and AUC0–∞. However, no significant differences in Cmax, tmax, t1/2, AUC0–48, AUC0–∞, and CL among MDR1 C3435T genotypes were observed. Conclusions: MDR1 C3435T polymorphism does not affect oral pharmacokinetics of telmisartan. Clin Chem Lab Med 2009;47:38–43.

Decrease in the synthesis and release of calcitonin gene-related peptide in dorsal root ganglia of spontaneously hypertensive rat: role of nitric oxide synthase inhibitors.

Calcitonin gene-related peptide (CGRP), the major transmitter in capsaicin-sensitive sensory nerves, and asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, participate in the regulation of blood pressure. In the present study, we tested the relationship between CGRP and ADMA in spontaneously hypertensive rats (SHRs). For the in vivo study, SHRs were treated with or without L-arginine for 2 weeks, and Wistar Kyoto (WKY) rats were used as controls. Systolic arterial pressure was measured, and the levels of CGRP, ADMA, and NO were analyzed. For the in vitro study, neural cells from dorsal root ganglia were treated with NO inhibitor or donor. Synthesis and release of CGRP were measured. Compared with WKY rats, serum concentration of ADMA in SHRs increased while CGRP and NO level decreased. Treatment with L-arginine significantly decreased blood pressure, concomitantly with an increase in the level of NO and the synthesis and release of CGRP in SHRs, but it did not affect ADMA levels. In cultured neural cells, ADMA reduced the level of NO and inhibited the synthesis and release of CGRP in a concentration-dependent manner. The effects of ADMA were reversed by L-arginine. Treatment with NOC-18, a donor of NO, increased the release and synthesis of CGRP in neural cells in a concentration-dependent manner. Decreased synthesis and release of CGRP is related to a reduction in NO levels, and corresponds to the increased concentrations of ADMA in spontaneously hypertensive rats.

Association of the LOX-1 rs1050283 Polymorphism with Risk for Atherosclerotic Cerebral Infarction and its Effect on sLOX-1 and LOX-1 Expression in a Chinese Population

Aims: The interaction between lectin-like oxidized low density lipoprotein (LDL) receptor-1 (LOX-1) and oxidized LDL (ox-LDL) has been viewed as an important pathogenic factor for cardiovascular diseases. This study aimed to explore the association of a functional polymorphism rs1050283 in the 3′-untranslated region of the LOX-1 gene with atherosclerotic cerebral infarction (ACI) susceptibility, and we also investigated the effects of the rs1050283 polymorphism on LOX-1 expression and serum levels of sLOX-1 in patients with ACI. Methods: A case-controlled study was performed in 526 patients with ACI and 640 healthy controls. Genotyping was performed by DNA sequencing method. Real-time PCR and Western blotting were used to determine the level of LOX-1 expression. Serum levels of sLOX-1 were quantified using ELISA according to the manufacturers instruction. Results: The results of the present study showed that the frequency of rs1050283 T allele was significantly higher in patients with ACI than in healthy controls. We also found that the rs1050283 polymorphism T allele was associated with increased LOX-1 expression at mRNA and protein levels in patients with ACI. Furthermore, we also observed that among patients with ACI, those with the rs1050283 T allele showed an increased serum level of sLOX-1. Conclusion: Our research demonstrated that the rs1050283 T allele of LOX-1 is strongly associated with an increased risk for ACI in a Chinese population, which also affects levels of LOX-1 and sLOX-1.

Contrast Media-Induced Renal Inflammation Is Mediated Through HMGB1 and Its Receptors in Human Tubular Cells

With the rapid development of imaging diagnosis and interventional therapy, contrast media (CM) are widely used in clinics. However, contrast-induced nephropathy (CIN) is the third leading cause of hospital-acquired acute renal failure accounting for 10-12% of all causes of hospital-acquired renal failure. Recent study found that inflammation may participate in the pathogenesis of CIN, but the role of it remains unclear. HK-2 cells were treated with Iohexol, Urografin, and mannitol. Two types of CM increased the release of HMGB1 in cell supernatant accompanied by increased expression of TLR2 and CXCR4. Iohexol and Urografin also caused a significant increase in NF-κB followed by the release of IL-6 and MCP-1. To clarify the role of HMGB1, TLR2, and CXCR4, glycyrrhizin, anti-TLR2-IgG, and AMD3100 were used to inhibit HMGB1, TLR2, and CXCR4, respectively. Significant decrease in the expression of TLR2, CXCR4, nuclear NF-κB, and the release of IL-6 and MCP-1 were observed. These results indicate that TLR2 and CXCR4 signaling are involved in CM-induced HK-2 cell injury model in an HMGB1-dependent pathway, which may provide a new target for the prevention and the treatment of CIN.