Relationship between AOPP (Advanced Oxidation Protein Products) and bovine neutrophils "in vitro": AOPP production by neutrophils and AOPP effects on neutrophils ROS production and viability
Year: 2013
Type: article
Abstract: The aim of the present study was to evaluate the relationship between AOPP (Advanced oxidation protein products) and bovine neutrophils 'in vitro'. For this purpose AOPP were produced "in vitro" by oxidizing bovine serum albumin with HOCl (hypochlorous acid) and bovine neutrophils were isolated from whole blood of dairy cattles. AOPP-BSA were incubated with freshly isolated bovine neutrophils, unstimulated and stimulated with PMA a strong activator of the respiratory burst. Neutrophils ROS production and viability were measured by luminol-amplified chemiluminescence and by MTT and lactate dehydrogenase assays (LDH), respectively. Results obtained have shown that AOPP-BSA are able to reduce significantly ROS production of PMA stimulated neutrophil and their viability measured by MTT assay, no cell lysis was detected by LDH assay. On the basis of these results, our work has studied if AOPP are able to trigger apoptotic events. For this purpose, caspase 8-9-3 and DNA laddering were used as markers in order to discriminate between the 'intrinsic' and the 'extrinsic' pathway of apoptosis. The results obtained showed that un-stimulated bovine neutrophils incubated with AOPP-BSA show a higher but not significant production of active caspase 8 in comparison with the incubation with BSA. Also caspase 3 display an increase, but not significant, in un-stimulated neutrophils after 6 hours of incubation with AOPP-BSA, respects the incubation with BSA. No differences were obtained for caspase 9 and for DNA laddering. Therefore, in these experimental conditions is possible to conclude that the 'intrinsic' pathway of apoptosis was not involved in the reduced functionality of neutrophils or in their reduced viability, but bovine neutrophils incubated with AOPP-BSA seem to be "accompanied" to the early phases of the 'extrinsic' pathways of apoptosis. In addition, the present work wanted to evaluate the capacity of triggered neutrophils to generate AOPP in vitro. BSA was incubated with un-stimulated and PMA-stimulated bovine neutrophils for 1-2-3 hours and the production of specific markers of protein oxidation such as AOPP, dityrosines and carbonyls was assessed. BSA incubated with stimulated neutrophils presents a significant higher level of AOPP and dityrosines respects the incubation with un-stimulated neutrophils. Carbonyls don't seem to be produced in these condition, at least at the beginning of the incubation. In parallel, BSA incubated with the same concentration of HOCl produced by PMA-stimulated neutrophils, for 1-2-3 hours, presents a higher level of AOPP, dityrosines and carbonyls. Therefore, it's possible to conclude that bovine neutrophils are able to oxidize BSA in vitro and generate chemical and structural modification such as AOPP and dityrosines, in the experimental condition used. However, carbonyls seem to be a non-specific indicator of neutrophils-mediated protein oxidation. The direct exposure of BSA to HOCl couldn't fully mimic the complex events leading to BSA oxidation and AOPP production by activated neutrophils.
Author: Milena Bordignon
Language: English
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W187953777