EFFECT OF MYELOPEROXIDASE ON MITOCHONDRIAL RESPIRATORY FUNCTION OF PERMEABILIZED PRIMARY EQUINE SKELETAL MYOBLASTS IN CULTURE.

Poster (2012, November)

Specific immuno-extraction followed by enzymatic detection (SIEFED) of myeloperoxidase and mitochondrial complex I in muscular microbiopsies: preliminary results in endurance horses

in Equine Veterinary Journal. Supplement (2010), 42(Suppl. 38), 296-302

Effect of intensive exercise on plasmatic neutrophil elastase level in eventing and endurance horses

in Equine Veterinary Journal. Supplement (2010), 48

Reasons for performing the study – Intensive exercise induces a systemic inflammatory response characterized by an increase of blood neutrophil count and myeloperoxidase (MPO) release. Neutrophil elastase ... [more ▼]

Reasons for performing the study – Intensive exercise induces a systemic inflammatory response characterized by an increase of blood neutrophil count and myeloperoxidase (MPO) release. Neutrophil elastase (NE) could also contribute to tissues lesions by their proteinase activities. Objective – To compare plasmatic NE concentrations before and after different forms of intensive exercise. Materials and Methods – EDTA blood samples were taken from 51 eventing horses (EvH) and 32 endurance horses (EndH) were sampled before the race (T0). Blood sampling was performed 2 h (T1) after completing either phase D of a one or two star eventing competition (n=51) or a 120 or 160 km endurance race (n=32). Plasmatic NE and MPO were measured by a specific equine ELISA. Neutrophil counts and creatine kinase (CK) levels were also measured. A Wilcoxon test for paired samples was used to compare mean values of neutrophils, CK, MPO and NE at T0 and T1 in EvH and in EndH. Correlations were calculated between all the 4 parameters in EvH and EndH. Results – At T0, mean NE levels were 14.43 ± 3.63 ng/ml for EvH and 11.7 ± 2.11 ng/ml for EndH. The competition induced a significant increase of NE levels in (58.57 ± 24.06 ng/mL) EvH and (95.74 ± 22.70 ng/mL) EndH (p < 0,05). NE was significantly (p < 0,0001) correlated to MPO in EvH (r = 0.293) and EndH (0.594) and to CK (r = 0.297) in EndH (p<0.0001). Neutrophils, CK and MPO were significantly increased between T0 and T1 in both types of horses. Conclusions – Significant increase of NE was observed after intense exercise with a significant correlation between NE and MPO. The huge variability in MPO and ELT, indicates, that not all horses show the same intensity of systemic inflammatory response. [less ▲]

AMADEOX method : combination of various techniques to distinguish stoichiometric and anticatalytic activities of antioxidant molecules or natural extracts

in International Society of Antioxidants in Nutrition & Health, 5th International Conference on Polyphenols Applications, Bridging Bioefficacy to Innovations & Applications, October 29th-30th 2009, Malta (2009, October 29)

We developed an original method called AMADEOX (for « Action Modulatrice de l'Activité Des Enzymes Oxydantes ») able to distinguish stoichiometric, metabolic and anticatalytic activities of antioxidant ... [more ▼]

We developed an original method called AMADEOX (for « Action Modulatrice de l'Activité Des Enzymes Oxydantes ») able to distinguish stoichiometric, metabolic and anticatalytic activities of antioxidant molecules or natural extracts on stimulated neutrophils and purified myeloperoxidase (MPO), a key enzyme released by neutrophil and acting as one of the major ROS generating systems. [less ▲]

Activation of equine neutrophils by phorbol myristate acetate or N-formyl-methionyl-leucyl-phenylalanine induces a different response in reactive oxygen species production and release of active myeloperoxidase.

in Veterinary Immunology and Immunopathology (2009)

Neutrophil (PMN) contribution to the acute inflammatory processes may lead to an excessive generation of reactive oxygen metabolites species (ROS) and secretion of granule enzymes. We compared the effects ... [more ▼]

Neutrophil (PMN) contribution to the acute inflammatory processes may lead to an excessive generation of reactive oxygen metabolites species (ROS) and secretion of granule enzymes. We compared the effects of either phorbol myristate acetate (PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP) in combination with a pre-treatment by cytochalasin B (CB) on the production of ROS and the release of total and active myeloperoxidase (MPO) by isolated equine PMNs. The ROS production was assessed by lucigenin dependent chemiluminescence (CL) and ethylene release by alpha-keto-gamma-methylthiobutyric acid (KMB) oxidation. In the supernatant of activated PMNs, total equine MPO was measured by ELISA and active MPO by the SIEFED (Specific Immunologic Extraction Followed by Enzymatic Detection) technique that allows for the study of the interaction of a compound directly with the enzyme. The stimulation of PMNs with CB-fMLP only modestly increased the release of MPO, but more than 70% of released MPO was active. PMA stimulation markedly increased the production of ROS and release of MPO, but more than 95% of released MPO was inactive. When PMNs were pre-incubated with superoxide dismutase (SOD) prior to PMA activation, the lucigenin enhanced CL, which is linked to the superoxide anion (O(2)(-)) production, was much more decreased than KMB oxidation, linked to the hydroxyl-like radical production. The addition of SOD prior to the activation of PMNs by PMA also limited the loss of the activity of released MPO. These results confirm the key role of O(2)(-) generation in the ROS cascade in PMN and reveal its critical role on MPO inactivation. [less ▲]