Characterization of the distinct mechanism of agonist-induced canine platelet activation

P2Y1 and P2Y12 Receptors Mediate Aggregation of Dog and Cat Platelets: A Comparison to Human Platelets

Thrombosis is one of the most prevalent and serious health issues amongst humans. A key component of thrombotic events is the activation and aggregation of platelets, of which the P2Y1 and P2Y12 receptors play a crucial role in this process. Despite a breadth of knowledge on thrombosis and its mechanisms and treatment in various disorders in humans, there is less of an understanding of the expression and exact role of these receptors in companion animals such as dogs and cats. Therefore, this study aimed to investigate P2Y1 and P2Y12 receptors on dog and cat platelets in platelet-rich plasma and compare them to human platelets. Immunoblotting revealed the presence of P2Y1 and P2Y12 receptor proteins on dog and cat platelets, although relative amounts of each receptor appeared to contrast those of human platelets, with increased amounts of P2Y1 compared to P2Y12 receptors in dogs and cats. Using a modified 384-well plate aggregation assay, designed for use with small volumes, the human P2Y1 and P2Y12 receptor agonists adenosine 5'-diphosphate and 2-methylthio-adenosine 5'-diphosphate caused aggregation of dog and cat platelets. This aggregation was near-completely inhibited by the selective P2Y12 antagonist ticagrelor. Aggregation of dog and cat platelets was partly inhibited by the human P2Y1 receptor antagonist MRS2179. The agonist and antagonist responses in dog and cat platelets were like those of human platelets. In contrast, the aggregation of dog platelets in the absence of added nucleotides was two-fold greater than that of cats and humans. This study indicates that platelets of cats and dogs possess functional P2Y1 and P2Y12 receptors that can be inhibited by human antagonists. The data presented suggest differing roles or responses of the platelet P2Y receptors in dogs and cats compared to humans but also highlight the potential of using currently available P2Y1 or P2Y12 antiplatelet drugs such as ticagrelor for the treatment of thrombosis in these companion animals.

G protein-coupled P2Y12 receptor is involved in the progression of neuropathic pain

The pathological mechanism of neuropathic pain is complex, which seriously affects the physical and mental health of patients, and its treatment is also difficult. The role of G protein-coupled P2Y12 receptor in pain has been widely recognized and affirmed. After nerve injury, stimulated cells can release large amounts of nucleotides into the extracellular matrix, act on P2Y12 receptor. Activated P2Y12 receptor activates intracellular signal transduction and is involved in the development of pain. P2Y12 receptor activation can sensitize primary sensory neurons and receive sensory information. By transmitting the integrated information through the dorsal root of the spinal cord to the secondary neurons of the posterior horn of the spinal cord. The integrated information is then transmitted to the higher center through the ascending conduction tract to produce pain. Moreover, activation of P2Y12 receptor can mediate immune cells to release pro-inflammatory factors, increase damage to nerve cells, and aggravate pain. While inhibits the activation of P2Y12 receptor can effectively relieve pain. Therefore, in this article, we described P2Y12 receptor antagonists and their pharmacological properties. In addition, we explored the potential link between P2Y12 receptor and the nervous system, discussed the intrinsic link of P2Y12 receptor and neuropathic pain and as a potential pharmacological target for pain suppression.

The canine activated platelet secretome (CAPS): A translational model of thrombin-evoked platelet activation response

BACKGROUND

Domestic dogs represent a translational animal model to study naturally occurring human disease. Proteomics has emerged as a promising tool for characterizing human platelet pathophysiology; thus a detailed characterization of the core canine activated platelet secretome (CAPS) will enhance utilization of the canine model. The objectives of this study were development of a robust, high throughput, label-free approach for proteomic identification and quantification of the canine platelet (i) thrombin releasate proteins, and (ii) the protein subgroup that constitutes CAPS.

METHODS

Platelets were isolated from 10 healthy dogs and stimulated with 50 nmol/L of γ-thrombin or saline. Proteins were in-solution trypsin-digested and analyzed by nano-liquid chromatography-tandem spectrometry. Core releasate proteins were defined as those present in 10 of 10 dogs, and CAPS defined as releasate proteins with a significantly higher abundance in stimulated versus saline controls (corrected P < .05).

RESULTS

A total of 2865 proteins were identified; 1126 releasate proteins were present in all dogs, 650 were defined as CAPS. Among the differences from human platelets were a canine lack of platelet factor 4 and vascular endothelial growth factor C, and a 10- to 20-fold lower concentration of proteins such as haptoglobin, alpha-2 macroglobulin, von Willebrand factor, and amyloid-beta A4. Twenty-eight CAPS proteins, including cytokines, adhesion molecules, granule proteins, and calcium regulatory proteins have not previously been attributed to human platelets.

CONCLUSIONS

CAPS proteins represent a robust characterization of a large animal platelet secretome and a novel tool to model platelet physiology, pathophysiology, and to identify translational biomarkers of platelet-mediated disease.

Feasibility study of use of rabbit blood to evaluate platelet activation by medical devices

It is important to ascertain platelet responses to blood-contacting medical devices as part of a complete hemocompatibility evaluation. Nevertheless, researchers often face the problem of insufficient quantities of human blood for evaluation of platelet activation by actual medical devices. If animal blood can replace human blood to evaluate platelet activation by medical devices, testing will be smoother and will aid for quality control of related products. Therefore, in this study, we exposed representative biomaterials to human blood, rabbit blood and mouse blood, and evaluated similarities and differences in platelet activation among the three types of blood by measuring various molecular markers. We found that rabbit blood and human blood had considerable similarity in terms of platelet activation, while mouse blood and human blood showed considerable differences. Therefore, rabbit blood may replace human blood for platelet function testing.