ABSTRACT
Extracellular traps (ETs) are webs of DNA, citrullinated histones, anti-microbial peptides, and proteins that were not previously reported in Atlantic salmon (Salmo salar). ETs are mainly released from polymorphonuclear neutrophils (PMN) and are considered a novel PMN-derived effector mechanism against different invasive pathogens. Here, we showed that Atlantic salmon-derived PMN released ETs-like structures in vitro in response to highly pathogenic facultative intracellular rickettsial bacteria Piscirickettsia salmonis. PMN were isolated from pre-smolt Atlantic salmon and stimulated in vitro with oleic acid and P. salmonis. Extracellular DNA was measured using the PicoGreen™ dye, while immunofluorescence image analysis was used to confirm the classical components of salmonid-extruded ETs. Future studies are required to better understand the role of Atlantic salmon-derived ETs orchestrating innate/adaptive immunity and the knowledge on regulation pathways involved in this cell death process. Thus, comprehension of salmonid-derived ETs against P. salmonis might represent novel alternative strategies to improve host innate defense mechanisms of farmed salmon against closely related rickettsial bacteria, as a complement to disease prevention and control strategies.
ABSTRACT
Myelosupression resulting from chemotherapy has been widely described in veterinary medicine; however, there is limited information relating to alterations in neutrophil function after chemotherapy in dogs with cancer. The aim of this study was to determine the non-proliferative effects of vincristine, carboplatin, and cisplatin on canine neutrophils by evaluating activation of oxidative and non-oxidative responses. Neutrophils were isolated from venous blood. Levels of reactive oxygen species (ROS) and metalloproteinase 9 (MMP-9) were measured in vitro during neutrophil exposure to these chemotherapeutic agents for 15 min followed by stimulation with platelet activating factor (PAF). ROS production was detected via luminescence, and MMP- 9 liberation was determined by zymography. The chemotherapeutic agents caused an increase in PAF-induced ROS production, but no change in the non-oxidative response was observed. These results suggest that these chemotherapeutic agents may act as priming agents by increasing the oxidative response. These effects could be beneficial for dogs with cancer by supporting their immune systems; however, excessive ROS liberation has been associated with inflammation, neutrophil-mediated cell injury, carcinogenesis, and metastasis. Clinical studies are necessary to evaluate the significance of these findings.
