CEACAM2 negatively regulates hemi (ITAM-bearing) GPVI and CLEC-2 pathways and thrombus growth in vitro and in vivo.

Carcinoembryonic antigen-related cell adhesion molecule-2 (CEACAM2) is a cell-surface glycoprotein expressed on blood, epithelial, and vascular cells. CEACAM2 possesses adhesive and signaling properties mediated by immunoreceptor tyrosine-based inhibitory motifs. In this study, we demonstrate that CEACAM2 is expressed on the surface and in intracellular pools of platelets. Functional studies of platelets from Ceacam2(-/-)-deficient mice (Cc2(-/-)) revealed that CEACAM2 serves to negatively regulate collagen glycoprotein VI (platelet) (GPVI)-FcRγ-chain and the C-type lectinlike receptor 2 (CLEC-2) signaling. Cc2(-/-) platelets displayed enhanced GPVI and CLEC-2-selective ligands, collagen-related peptide (CRP), collagen, and rhodocytin (Rhod)-mediated platelet aggregation. They also exhibited increased adhesion on type I collagen, and hyperresponsive CRP and CLEC-2-induced α and dense granule release compared with wild-type platelets. Furthermore, using intravital microscopy to ferric chloride (FeCl3)-injured mesenteric arterioles and laser-induced injury of cremaster muscle arterioles, we herein show that thrombi formed in Cc2(-/-) mice were larger and more stable than wild-type controls in vivo. Thus, CEACAM2 is a novel platelet immunoreceptor that acts as a negative regulator of platelet GPVI-collagen interactions and of ITAM receptor CLEC-2 pathways.

CEACAM2 positively regulates integrin αIIbß3-mediated platelet functions.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is an Ig-ITIM superfamily member that regulates integrin αIIbß3 function. We hypothesized that its twin protein, CEACAM2, exerts a similar physiologic role in murine platelets. CEACAM2-deficient mice (Cc2-/-) displayed prolonged tail bleeding times and increased volume of blood loss. Cc2-/- platelets have moderate integrin αIIbß3-mediated functional defects with impaired kinetics of platelet spreading on fibrinogen and type I collagen and delayed kinetics in the retraction of fibrin clots in vitro. This functional integrin αIIbß3 defect could not be attributed to altered integrin αIIbß3 expression. Cc2-/- platelets displayed normal 'inside-out' signaling properties as demonstrated by normal agonist-induced binding of soluble fluorescein isothiocyanate (FITC)-fibrinogen and JON/A antibody binding. This data provides direct evidence that disruption of CEACAM2 induces a moderate integrin αIIbß3-mediated platelet function defect, and that CEACAM2 is essential to maintain a normal integrin αIIbß3-mediated platelet function.

Detections of organophosphate and pyrethroid insecticide metabolites in urine and sweat obtained from women during infrared sauna and exercise: A pilot crossover study.

Synthetic pesticides such as organophosphates and pyrethroids are commonly used worldwide yet the metabolic and long-term human health effects of these environmental exposures are unclear. Urinary detections of metabolites involving both classes of insecticides have been documented in various global populations. However, reports documenting similar detections in human sweat are sparse. In this study, the concentrations of four insecticide metabolites were measured using liquid chromatography coupled with tandem mass spectrometry in repeated sweat and urine collections (n = 85) from 10 women undergoing three interventions (control, infrared sauna and indoor bicycling) within a single-blinded randomised crossover trial. The Friedman test with post-hoc two-way analysis of variance, the related-samples Wilcoxon signed rank test and the Spearman's rank-order correlation test were used to analyse the results. Organophosphate metabolites were detected in 84.6% (22/26) and pyrethroids in 26.9% (7/26) of the collected sweat samples (pooled per individual, per intervention). Urinary concentrations of three of the four metabolites marginally increased after infrared sauna bathing: 3,5,6-trichloro-2-pyridinol (z = 2.395, p = 0.017); 3-phenoxybenzoic acid (z = 2.599, p = 0.009); and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (z = 2.090, p = 0.037). Urinary 3-phenoxybenzoic acid also increased after exercise (z = 2.073, p = 0.038) and demonstrated the most temporal variability (days to weeks) of any of the urinary metabolites. Definitive sweat/urine correlations were not demonstrated. These results indicate metabolites from organophosphate and pyrethroid pesticides can be detected in human sweat and this raises intriguing questions about perspiration and its role in the metabolism and excretion of synthetic pesticides.

Infrared sauna as exercise-mimetic? Physiological responses to infrared sauna vs exercise in healthy women: A randomized controlled crossover trial.

BACKGROUND: Passive heat therapies have been reported to have similar effects on the cardiovascular system as exercise. Studies supporting these findings in healthy populations have predominantly been done with men using warm water immersions or traditional saunas, rather than newer infrared-based saunas. OBJECTIVE: To explore short-term thermal and cardiovascular responses in women using an infrared sauna as compared to moderate-intensity exercise. STUDY DESIGN: Randomized controlled crossover trial with balanced allocations. SETTING: Brisbane, Australia (August 2019 - March 2020) PARTICIPANTS: Ten healthy women (36 ±â€¯9 years) INTERVENTIONS: 45 min of resting, infrared sauna or indoor bicycling PRIMARY OUTCOME MEASURES: tympanic/skin temperatures; respiratory rate; blood pressure; arterial stiffness; heart rate variability RESULTS: Tympanic temperatures were elevated during infrared sauna as compared to both control (mean diff = +1.05 oC ±â€¯SEM 0.12 oC, 95% C.I.: 0.73 - 1.36, p < 0.0005) and exercise (mean diff = +0.79 oC ±â€¯SEM 0.12 oC, 95% C.I.: 0.49 - 1.08, p < 0.0005). Respiratory rates were higher during exercise as compared to both control (mean diff = +7.66 ±â€¯SEM 1.37, 95% C.I.: 4.09 - 11.23, p < 0.0005) and infrared sauna (mean diff = +6.66 ±â€¯SEM 1.33, 95% C.I.: 3.20 - 10.11, p < 0.0005). No significant differences in non-invasive measures of blood pressure, arterial stiffness or heart rate variability were detected between any of the interventions. CONCLUSIONS: These findings suggest the physiological effects of infrared sauna bathing are underpinned by thermoregulatory-induced responses, more so than exercise-mimetic cardiorespiratory or cardiovascular activations.

Molecular mechanisms of immunoreceptors in platelets.

BACKGROUND: The main role of platelets is to control haemostasis when there is a blood vessel injury in order to minimise blood loss at the injury site. Under normal circumstances, platelets flow freely within blood vessels as the endothelial cells provide a non-adhesion surface. Naturally, bioactive mediators are released from endothelial cells to prevent and control platelet activation. However, when the vascular endothelium is ruptured, the local concentration of nitric oxide and prostaglandin is diminished and receptors containing a sequence of amino acids known as, immunoreceptor tyrosine-based inhibition motifs (ITIMs), serve as natural inhibitors within platelets. The main role of ITIMs is to decrease immunoreceptor tyrosine-based activation motif (ITAM) signalling in platelets; however, some studies have revealed their novel role in integrin αIIbß3 activation. This review highlights the main structural and functional features of immunoreceptors in platelets.

The tyrosine kinase inhibitor, nilotinib potentiates a prothrombotic state.

Tyrosine kinase inhibitors (TKI) such as imatinib, nilotinib and dasatinib are now established as highly effective frontline therapies for chronic myeloid leukaemia (CML). Disease control is achieved in the majority of patients and survival is excellent such that recent focus has been on toxicities of these agents. Cumulative data have reported an excess of serious vascular complications, including arterial thrombosis and peripheral arterial occlusive disease, in patients receiving nilotinib in comparison with other TKIs, with resultant interest in delineating the pathophysiology and implications for rationale cardiovascular risk modification. To address this issue, we studied the effects of imatinib, nilotinib and dasatinib on platelet function and thrombus formation in human and mouse models using in vitro, ex vivo and in vivo approaches. In vitro studies demonstrated that dasatinib and imatinib but not nilotinib inhibited ADP, CRP, and collagen-induced platelet aggregation and moreover, that nilotinib potentiated PAR-1-mediated alpha granule release. Pretreatment of wild-type C57BL/6 mice with nilotinib but not imatinib or dasatinib, significantly increased thrombus growth and stability, on type I collagen under ex vivo arterial flow conditions and increased thrombus growth and stability following FeCl3-induced vascular injury of mesenteric arterioles and carotid artery injury in vivo. Whole blood from nilotinib-treated CML patients, demonstrated increased platelet adhesion ex vivo under flow, increased plasma soluble P- and E-selectin, sICAM-1, sVCAM-1, TNF-alpha, IL-6 levels and endogenous thrombin potential (ETP) levels in vivo, despite being on daily low-dose aspirin. These results demonstrate that nilotinib can potentiate platelet and endothelial activation and platelet thrombus formation ex vivo and in vivo.