The molecular mechanisms involved in lectin-induced human platelet aggregation

Oxidative Stress Induced by Cortisol in Human Platelets

Hypercortisolism is known to affect platelet function. However, few studies have approached the effect of exogenous cortisol on human platelets, and the results obtained are conflicting and unconvincing. In this study, the effect of exogenous cortisol on several parameters indicative of oxidative status in human platelets has been analysed. We have found that cortisol stimulates ROS production, superoxide anion formation, and lipid peroxidation, with these parameters being in strict correlation. In addition, cortisol decreases GSH and membrane SH-group content, evidencing that the hormone potentiates oxidative stress, depleting platelet antioxidant defence. The involvement of src, syk, PI3K, and AKT enzymes in oxidative mechanisms induced by cortisol is shown. The main sources of ROS in cells can include uncontrolled increase of NADPH oxidase activity and uncoupled aerobic respiration during oxidative phosphorylation. Both mechanisms seem to be involved in ROS formation induced by cortisol, as the NADPH oxidase 1 inhibitor 2(trifluoromethyl)phenothiazine, and rotenone and antimycin A, complex I and III inhibitor, respectively, significantly reduce oxidative stress. On the contrary, the NADPH oxidase inhibitor gp91ds-tat, malate and NaCN, complex II and IV inhibitor, respectively, have a minor effect. It is likely that, in human platelets, oxidative stress induced by cortisol can be associated with venous and arterial thrombosis, greatly contributing to cardiovascular diseases.

Platelet Metabolic Flexibility: A Matter of Substrate and Location

Platelets are cellular elements that are physiologically involved in hemostasis, inflammation, thrombotic events, and various human diseases. There is a link between the activation of platelets and their metabolism. Platelets possess considerable metabolic versatility. Although the role of platelets in hemostasis and inflammation is known, our current understanding of platelet metabolism in terms of substrate preference is limited. Platelet activation triggers an oxidative metabolism increase to sustain energy requirements better than aerobic glycolysis alone. In addition, platelets possess extra-mitochondrial oxidative phosphorylation, which could be one of the sources of chemical energy required for platelet activation. This review aims to provide an overview of flexible platelet metabolism, focusing on the role of metabolic compartmentalization in substrate preference, since the metabolic flexibility of stimulated platelets could depend on subcellular localization and functional timing. Thus, developing a detailed understanding of the link between platelet activation and metabolic changes is crucial for improving human health.

Mechanism Research of Platelet Core Marker Prediction and Molecular Recognition in Cardiovascular Events

BACKGROUND

Thrombosis triggered by platelet activation plays a vital role in the pathogenesis of cardiovascular and cerebrovascular diseases.

OBJECTIVE

This study aims to find platelet combined biomarkers for cardiovascular diseases and investigate the possibility of Concanavalin A (ConA) acting on platelets as a new pharmacological target.

METHODS

High-throughput Technology and bioinformatics analysis were combined and groups of microarray chip gene expression profiles for acute myocardial infarction (AMI) and sickle cell disease (SCD) were obtained using GEO database screening. R language limma package was used to obtain differentially expressed genes (DEGs). GO, KEGG, and other databases were utilized to perform the enrichment analysis of DEGs' functions, pathways, etc. PPI network was constructed using STRING database and Cytoscape software, and MCC algorithm was used to obtain the 200 core genes of the two groups of DEGs. Core targets were confirmed by constructing an intersection area screening. A type of molecular probe, ConA, was molecularly docked with the above core targets on the Zdock, HEX, and 3D-DOCK servers.

RESULTS

We found six core markers, CD34, SOCS2, ABL1, MTOR, VEGFA, and SMURF1, which were simultaneously related to both diseases, and the docking effect showed that VEGFA is the best-performing.

CONCLUSION

VEGFA is most likely to reduce its expression by binding to ConA, which could affect the downstream regulation of the PI3K/Akt signaling pathway during platelet activation. Some other core targets also have the opportunity to interact with ConA to affect platelet-activated thrombosis and trigger changes in cardiovascular events.

Lectin-induced oxidative stress in human platelets

Previously we have shown that wheat germ agglutinin (WGA) and, with minor potency, Phaseolus vulgaris agglutinin (PHA), but not lens culinarian agglutinin (LCA), induce platelet aggregation, through the PLCƴ2 activation by the concerted action of src/syk and PI3K/BTK pathways. In this study, we have investigated platelet oxidative stress induced by lectins. Several parameters indicative of oxidative stress, such as reactive oxygen species (ROS), superoxide anion, lipid peroxidation and the efficiency of the aerobic metabolism, have been measured. It was found that ROS, superoxide anion formation and lipid peroxidation are significantly increased upon platelet treatment with WGA and PHA while LCA is ineffective. WGA is always more effective than PHA in all experimental conditions tested. In addition, the involvement of NADPH oxidase 1, syk and PI3K in oxidative stress induced by WGA and PHA has been shown. Concerning the lectins effect on aerobic metabolism, WGA and PHA, but not LCA, act as uncoupling agents, determining an increase of oxygen consumption and a decrease of ATP synthesis, with a consequent decrease of P/O value. These results are confirmed by the impairment of platelets proton gradient formation, evaluated by membrane potential, in platelets treated with WGA and PHA. In conclusion lectins, especially WGA, induce oxidative stress in platelets and decrease energy availability through modifications of membrane structure leading to the inefficiency of the aerobic machinery that steers platelets toward death as suggested by the decreased metabolic activity of platelets and the increased lactic dehydrogenase release.

Improving Human Dietary Choices Through Understanding of the Tolerance and Toxicity of Pulse Crop Constituents

Chickpea, dry bean, dry pea, and lentil are prominent dietary grain legumes commonly referred to as pulses. Pulses have been a staple component of the human diet for more than 8,000 years; however, in the last 70 years they have virtually disappeared from most Western diets. Reduced intake has occurred concomitantly with inadequate dietary fiber consumption and the onset of the obesity pandemic. Misinformation about tolerance and toxicity of several pulse crop constituents remains a barrier to public health efforts to increase dietary intake. Of particular concern are lectins which participate in agglutination reactions with cell surface proteins and galacto-oligosaccharides which have been associated with intestinal discomfort and flatulence. The scientific basis of these concerns is reviewed.