The role of Inflammation in platelet activation (and in anti-neutrophil cytoplasmic antibody (ANCA) vasculitis)

Introduction Although the platelets’ role in haemostasis is well established, their contribution to the inflammatory response remains poorly understood. This is particularly true for the complex interactions between inflammatory factors and platelet agonists.

ANCA vasculitis is a group of rare autoimmune diseases that cause inflammation in small blood vessels throughout the body, leading to damage in various organs. It is characterized by the presence of anti-neutrophil cytoplasmic antibodies (ANCA) that target white blood cells, contributing to excessive inflammation and tissue injury.

Therefore, this study aims to determine the effects of inflammatory factors such as different cytokines and hormones on their own and in combination with platelet agonists.

Fig. 1  The comparison graph provided clearly illustrates the impact of using single and double agonists on platelet activation percentages versus the control tube, focusing on CD62 PE expression as the marker. The data highlights the potential synergistic effects when combining two agonists, leading to a notable increase in platelet activation within the population.; The comparison graph of different agonists on platelet activation

Method The platelets from healthy donors are exposed to well-defined agonists, including ADP, PAR1, TRAP, Epinephrine, IL-4, IL-12 and serotonin alone or in combination to achieve a high level of platelet activation in an in vitro environment. The resulting changes in platelet activation will be analysed using flow cytometry to measure various markers.

Results Low concentrations of different individual agonists did not lead to significant platelet activation according to CD62P expression by activated platelets. PAR1 agonist with 0/5µM concentration caused 7.3%±4.2% (P=0.3365) CD62P expression in comparison with Control Tube (3.06%±2.3%). 5µM Epinephrine agonist led to 15.8%±14.26% CD62P expression by activated platelet in contrast to no-agonist condition (P=0.4594). The presence of 1µg/ml LPS agonist, displayed a very mild activation of 4.5%±3.5% in CD62P expression (P=0.9999) in parallel with the absence of agonists test.

However, the combination of two and three agonists illustrates a significant platelet activation level increase and a remarkable synergy. The mixture of 1µg/ml LPS and 0/5µM PAR1 led to 17.37%±5.6% (P=0.3305), 1µg/ml LPS and 5µM Epinephrine caused 31.83%±4.4% (P=0.0045) and also, the combination of 5µM Epi and 5µM led to 73%±9.8% (P=<0.0001) CD62P expression by activated platelets.

The combination of all named agonists with the same concentrations could reach 66.8%±7.8% (P=<0.0001) CD62P expression which is a noticeable platelet activation level ([Fig. 1]).

Conclusion In conclusion, the early results from the first phase of the study using in vitro condition display that different agonists in combination together lead to a significant activation percentage in the platelet population, however, a similar process should be examined during in vivo models that would be evaluated in further study.

Publication History

Article published online:
26 February 2024