In vitro canine platelet aggregation caused byDirofilaria immitis extract

[摘要] Platelet function hyper-activity has been reported in Dirofilariaimmitis (heartworm, HW)-infected dogs. Although the mechanism of increasedplatelet hyper-activity has not yet been elucidated, it is suggested to be mediated byunknown factors, which may be related to adult HW components. This study aims to determinewhether adult male HW whole body extract induces canine platelet aggregation invitro. The results indicate that HW extract caused an aggregation of canineplatelets in a concentration-dependent manner. This aggregation ability of the HW extractwas not mediated by the adenosine diphosphate receptor. In addition, the mechanisms ofaggregation did not require cyclooxygenase-dependent pathways, and the aggregatingactivity of substances contained in the HW extract was heat stable; therefore, the activesubstances may be different from collagen. Furthermore, the platelet aggregating activityremained within the molecular weight (MW)≥100,000 fraction obtained by ultrafiltrating theHW extract. In contrast, the MW <100,000 fraction also had a platelet aggregationability, but the aggregation pattern was reversible and the maximum extent decreased,compared with the MW≥100,000 fraction response. Our experiments have been conducted usinga whole body extract from adult HWs to determine with certainty the aggregating activityof HW elements on canine platelets. More studies are necessary to evaluate the effects ofthe metabolic products released from live adult worms in pulmonary arteries and thesymbiont bacterium Wolbachia-derived antigens on canine plateletaggregation.

[学科分类] 兽医学

[关键词] Dirofilaria immitis;dog;heartworm extract;platelet aggregation