PPAR-α genetic variants influence on-treatment platelet reactivity in patients treated with clopidogrel and lipid-lowering drugs and undergoing non-urgent percutaneous coronary intervention with stent implantation

Background: Response to clopidogrel varies between patients, due to many factors, like polymorphisms in genes encoding for metabolizing enzymes. The CYP3A4∗22 polymorphism has been proven to decrease the expression of CYP3A4, while the PPAR-α genetic variants G209A and A208G have been identified as determinants that affect CYP3A4. Statins and fibrates, which are the ligands of PPAR-α as well as being metabolized by CYP3A4, might also affect the response of clopidogrel through these two proteins. Objectives: To investigate the association between on-treatment platelet reactivity and the CYP3A4∗22 allele and genetic variations of the PPAR-α genes in clopidogrel-treated patients undergoing non-urgent percutaneous coronary intervention (PCI) with stenting and to evaluate the influence of statin/fibrate co-medication on these associations. Methods: A total of 1126 patients with non-urgent PCI and stenting pre-treated with clopidogrel and aspirin were genotyped for CYP3A4∗22 and PPAR-α (G209A and A208G). Platelet reactivity was measured using the VerifyNow® P2Y12-assay, expressed in PRU. Multivariate linear regression analysis was used to assess the association between the genetic variants and platelet reactivity, adjusted for confounders, including the CYP2C19 metabolizer status. A stratified analysis was conducted for patients with statin/fibrate co-medication. A recessive model was used for all associations. Results: The CYP3A4∗22/∗22 genotype was present in 0.4% of patients, 6.8% had the PPAR-α G209A AA genotype, and 7.0% had the PPAR-α A208G GG genotype. CYP3A4∗22 was not associated with platelet reactivity. PPAR-α genetic variants were significantly associated with platelet reactivity (PPAR-α G209A AA: -23.87 PRU [-43.54, -4.19]; PPAR-α A208G GG: -23.70 PRU [-43.13, -4.27]). In patients who were on statin/fibrate co-medication, these PPAR-α genetic variants were associated with an even lower platelet reactivity (-29.74 PRU [-50.94, -8.54], and -29.38 PRU [-50.26, -8.49], respectively), while those without statin/fibrate co-medication did not show a significant change in platelet reactivity (13.00 PRU [-39.79, 65.80]). Conclusions: Two genetic variants in PPAR-α (G209A and A208G) were associated with lower platelet reactivity in patients with non-urgent PCI and stenting co-treated with clopidogrel and lipid-lowering drugs

Vascular CXCR4 Limits Atherosclerosis by Maintaining Arterial Integrity Evidence From Mouse and Human Studies

BACKGROUND: The CXCL12/CXCR4 chemokine ligand/receptor axis controls (progenitor) cell homeostasis and trafficking. So far, an atheroprotective role of CXCL12/CXCR4 has only been implied through pharmacological intervention, in particular, because the somatic deletion of the CXCR4 gene in mice is embryonically lethal. Moreover, cell-specific effects of CXCR4 in the arterial wall and underlying mechanisms remain elusive, prompting us to investigate the relevance of CXCR4 in vascular cell types for atheroprotection. METHODS: We examined the role of vascular CXCR4 in atherosclerosis and plaque composition by inducing an endothelial cell (BmxCreERT2-driven)-specific or smooth muscle cell (SMC, SmmhcCreERT2-or TaglnCre-driven)-specific deficiency of CXCR4 in an apolipoprotein E-deficient mouse model. To identify underlying mechanisms for effects of CXCR4, we studied endothelial permeability, intravital leukocyte adhesion, involvement of the Akt/WNT/beta-catenin signaling pathway and relevant phosphatases in VE-cadherin expression and function, vascular tone in aortic rings, cholesterol efflux from macrophages, and expression of SMC phenotypic markers. Finally, we analyzed associations of common genetic variants at the CXCR4 locus with the risk for coronary heart disease, along with CXCR4 transcript expression in human atherosclerotic plaques. RESULTS: The cell-specific deletion of CXCR4 in arterial endothelial cells (n=1215) or SMCs (n=13-24) markedly increased atherosclerotic lesion formation in hyperlipidemic mice. Endothelial barrier function was promoted by CXCL12/\CXCR4, which triggered Akt/WNT/beta-catenin signaling to drive VE-cadherin expression and stabilized junctional VE-cadherin complexes through associated phosphatases. Conversely, endothelial CXCR4 deficiency caused arterial leakage and inflammatory leukocyte recruitment during atherogenesis. In arterial SMCs, CXCR4 sustained normal vascular reactivity and contractile responses, whereas CXCR4 deficiency favored a synthetic phenotype, the occurrence of macrophage-like SMCs in the lesions, and impaired cholesterol efflux. Regression analyses in humans (n=259 796) identified the C-allele at rs2322864 within the CXCR4 locus to be associated with increased risk for coronary heart disease. In line, C/C risk genotype carriers showed reduced CXCR4 expression in carotid artery plaques (n=188), which was furthermore associated with symptomatic disease. CONCLUSIONS: Our data clearly establish that vascular CXCR4 limits atherosclerosis by maintaining arterial integrity, preserving endothelial barrier function, and a normal contractile SMC phenotype. Enhancing these beneficial functions of arterial CXCR4 by selective modulators might open novel therapeutic options in atherosclerosis

Chemokines and galectins form heterodimers to modulate inflammation

Chemokines and galectins are simultaneously upregulated and mediate leukocyte recruitment during inflammation. Until now, these effector molecules have been considered to function independently. Here, we tested the hypothesis that they form molecular hybrids. By systematically screening chemokines for their ability to bind galectin‐1 and galectin‐3, we identified several interacting pairs, such as CXCL12 and galectin‐3. Based on NMR and MD studies of the CXCL12/galectin‐3 heterodimer, we identified contact sites between CXCL12 β‐strand 1 and Gal‐3 F‐face residues. Mutagenesis of galectin‐3 residues involved in heterodimer formation resulted in reduced binding to CXCL12, enabling testing of functional activity comparatively. Galectin‐3, but not its mutants, inhibited CXCL12‐induced chemotaxis of leukocytes and their recruitment into the mouse peritoneum. Moreover, galectin‐3 attenuated CXCL12‐stimulated signaling via its receptor CXCR4 in a ternary complex with the chemokine and receptor, consistent with our structural model. This first report of heterodimerization between chemokines and galectins reveals a new type of interaction between inflammatory mediators that can underlie a novel immunoregulatory mechanism in inflammation. Thus, further exploration of the chemokine/galectin interactome is warranted

Vibrational-rotational structure of the silane molecule in the band of v2+v4 (F2)

In recent years, extensive theoretical studies have been carried out on the silane molecule, namely their vibrational-rotational structure. In this work, we continue our research series and focus on the 28SiD4 isotopologue. The IR-spectrum of the silane molecule was recorded in the range 1250-1450 cm-1 (pentad region) on Bruker IFS 120HR Fourier interferometer. The P, Q, and R branches with Jmax up to 17 were assigned, and spectroscopic constants of the v2+v4 (F2) band were derived for 28SiD4. As a result, a set of spectroscopic parameters was obtained which describe the vibrational-rotational structure of the silane molecule close to the experimental uncertainties

Clinical characteristics of women captured by extending the definition of severe postpartum haemorrhage with 'refractoriness to treatment': a cohort study

Background: The absence of a uniform and clinically relevant definition of severe postpartum haemorrhage hampers comparative studies and optimization of clinical management. The concept of persistent postpartum haemorrhage, based on refractoriness to initial first-line treatment, was proposed as an alternative to common definitions that are either based on estimations of blood loss or transfused units of packed red blood cells (RBC). We compared characteristics and outcomes of women with severe postpartum haemorrhage captured by these three types of definitions. Methods: In this large retrospective cohort study in 61 hospitals in the Netherlands we included 1391 consecutive women with postpartum haemorrhage who received either ≥4 units of RBC or a multicomponent transfusion. Clinical characteristics and outcomes of women with severe postpartum haemorrhage defined as persistent postpartum haemorrhage were compared to definitions based on estimated blood loss or transfused units of RBC within 24 h following birth. Adverse maternal outcome was a composite of maternal mortality, hysterectomy, arterial embolisation and intensive care unit admission. Results: One thousand two hundred sixty out of 1391 women (90.6%) with postpartum haemorrhage fulfilled the definition of persistent postpartum haemorrhage. The majority, 820/1260 (65.1%), fulfilled this definition within 1 h following birth, compared to 819/1391 (58.7%) applying the definition of ≥1 L blood loss and 37/845 (4.4%) applying the definition of ≥4 units of RBC. The definition persistent postpartum haemorrhage captured 430/471 adverse maternal outcomes (91.3%), compared to 471/471 (100%) for ≥1 L blood loss and 383/471 (81.3%) for ≥4 units of RBC. Persistent postpartum haemorrhage did not capture all adverse outcomes because of missing data on timing of initial, first-line treatment. Conclusion: The definition persistent postpartum haemo

Atherogenic mononuclear cell recruitment is facilitated by oxidized lipoprotein-induced endothelial junctional adhesion molecule-A redistribution

Background: Junctional adhesion molecule (JAM-) A is a transmembrane protein expressed in many cell types and maintains junctional integrity in endothelial cells. Upon inflammatory stimulation, JAM-A relocates to the apical surface and might thereby facilitate the recruitment of leukocytes. Objective: Although inflammatory JAM-A redistribution is an established process, further effort is required to understand its exact role in the transmigration of mononuclear cells, particularly under atherogenic conditions. Methods: By the use of RNA interference and genetic deletion, the role of JAM-A in the transmigration of T cells and monocytes through aortic endothelial cells was investigated. JAM-A-localization and subsequent mononuclear cell rolling, adhesion and transmigration were explored during endothelial inflammation, induced by oxidized LDL or cytokines. Results: RNA interference or genetic deletion of JAM-A in aortic endothelial cells resulted in a decreased transmigration of mononuclear cells. Treatment of the endothelial cells with oxLDL resulted in an increase of both permeability and apical JAM-A presentation, as shown by bead adhesion and confocal microscopy experiments. Redistribution of JAM-A resulted in an increased leukocyte adhesion and transmigration, which could be inhibited with antibodies against JAM-A or by lovastatin-treatment, but not with the peroxisome proliferator activated receptor gamma-agonist pioglitazone. Conclusions: This study demonstrates that redistribution of JAM-A in endothelial cells after stimulation with pro-atherogenic oxidized lipoproteins results in increased transmigration of mononuclear cells. This inflammatory dispersal of JAM-A could be counteracted with statins, revealing a novel aspect of their mechanism of action