Paramètres influençant la structure et la fonction du globule rouge chez le cheval

The erythrocyte, as an oxygen carrier, is submitted to areas where oxidative stress is important. The maintenance of the structure and fluidity of its membrane is essential to its function. Indeed, oxygen must diffuse through the membrane and the deformability of the cell is essential to its progression through capillaries. The structure and, as a consequence, the fluidity of the membrane influence these properties. The red blood cell presents antioxydant capacities, but in some cases, free radical production is increased and exceeds antiradical defences leading to irreversible defects of the membrane, and, as a consequence, of its function. Horse erythrocyte seems to be more sensitive to oxidative stress than other species and resulting hemorheological changes could have tissular and organic consequences.Le globule rouge, de par sa fonction de transport de l’oxygène, est soumis à des milieux où le stress oxydant est important. Le maintien de la structure et de la dynamique de sa membrane est essentiel à la réalisation de sa fonction. En effet, l’oxygène doit pouvoir diffuser à travers la membrane et la cellule doit être capable de se déformer pour progresser dans les capillaires. La structure et, en conséquence, la fluidité de la membrane influencent ces propriétés. Le globule rouge présente des défenses antioxydantes importantes, mais dans certaines situations la production de radicaux libres est accrue et dépasse ces défenses aboutissant à des lésions irréversibles de la membrane cellulaire et donc de la fonction. L’érythrocyte équin semble plus sensible au stress oxydant que celui des autres espèces et les modifications hemorhéologiques qui en résultent peuvent avoir des conséquences au niveau tissulaire et organique.Peer reviewe

Characterization of pentraxin 3 in the horse and its expression in airways

The long pentraxin 3 (PTX3) plays an important role in host defence and its over-expression may contribute to airway injury. The aim of the present study was therefore to characterize in more detail PTX3 and its expression in the horses’ airway. Six healthy horses and six horses affected by recurrent airway obstruction (R.A.O.) were submitted to a dusty environment challenge. PTX3 DNA and cDNA were cloned and sequenced. PTX3 expression was evaluated by RT-qPCR, Western blotting and immuno-histochemistry in bronchoalveolar lavage fluid (BALF) cells, BALF supernatant and bronchial epithelial cells. An alternative splicing of the second exon of PTX3 occurred, resulting in two forms of the protein: “spliced” (32 kDa) and “full length” (42 kDa). PTX3 was detected in BALF macrophages, neutrophils and bronchial epithelial cells. It was over-expressed in the BALF supernatant from R.A.O.-affected horses in crisis. However, dust was unable to induce PTX3 in BALF cells ex vivo, indicating that dust is an indirect inducer of PTX3. Dust exposure in-vivo induced PTX3 in BALF macrophages but there was no significant difference between healthy and R.A.O.-affected horses. Conversely, PTX3 was over-expressed in the bronchial epithelial cells from R.A.O.-affected horses in crisis. These data indicate a differential regulatory mechanism in inflammatory and bronchial epithelial cells and offer therapeutically interesting perspectives

Comparison of inulin with urea as dilutional markers of bronchoalveolar lavage in healthy and heaves-affected horses.

Solute analysis in bronchoalveolar lavage fluid involves the use of dilutional markers to correct for variable recovery of pulmonary epithelial lining fluid (PELF). Urea is the best characterised endogenous marker, whereas inulin appears to meet the requirements of an exogenous marker. In horses, the use of inulin has never been investigated and the impact of lower airway diseases such as heaves, on PELF recovery is unknown. In this study, five healthy and five heaves-affected horses underwent airway endoscopy and bronchoalveolar lavage. PELF recovery from bronchoalveolar lavage was calculated by the inulin and the urea method. The inulin method was compared to the urea method and differences between healthy and heaves-affected horses were analysed. From a technical and analytical point of view, inulin fulfilled the requirements of a marker of dilution as well as urea. When both healthy and heaves-affected horses groups were pooled together, PELF recovery calculated by the inulin method was significantly higher than by the urea method (6.43+/-4.08% versus 0.789+/-0.299%, P < 0.005). No significant differences were observed between healthy and heaves-affected horses, neither by the inulin nor by the urea method. Inulin did not present major advantages over urea, but the combined use of both markers can improve the standardisation of studies comparing PELF compounds, by providing upper limits (inulin dilution) and lower limits (urea dilution) of PELF recovery.Peer reviewe

In Vitro Inhibitory Effect of SR 27417, a Potent Platelet-Activating Factor (PAF) Receptor Antagonist, on the PAF-Induced Bovine Platelet Aggregation

The in vitro inhibitory effect of SR 27417, an antagonist of the platelet-activating factor (PAF) receptor, on PAF-induced platelet aggregation was studied in blood collected from seven healthy Friesien calves. Inhibitory effects of SR 27417 were determined at thirteen different concentrations (0.1-400 nM) by using the dose-response curves of PAF on calf platelet aggregation. In the presence of SR 27417, the maximal slopes of aggregation (%/min) induced by low and high concentrations of PAF were significantly different from the control values obtained without an antagonist at p < or = 0.05 and p < or = 0.01 respectively. In vitro PAF-induced calf platelet aggregation was dose-dependently inhibited by SR 27417. The drug inhibited PAF-induced platelet aggregation in a competitive reversible manner (pA2 = 10.46 +/- 2.36 mol x L(-1)). In conclusion, the results of our study showed that addition of SR 27417 to bovine platelet in vitro inhibits PAF-induced platelet aggregation.Effet inhibiteur in vitro du SR 27417, un puissant antagoniste du récepteur du facteur d'activation plaquettaire sur l'agrégation des plaquettes induite par le PAF chez le bovin. L'effet inhibiteur in vitro du SR 27417, un antagoniste du récepteur du facteur d'activation plaquettaire (PAF) induite par le PAF sur l'agrégation plaquettaire a été étudiée dans le sang prélevé des sept veaux sains de race Frisonne. L'effet inhibiteur du SR 27417 a été déterminé avec treize concentrations différentes (0,1 - 400 nM) en utilisant les courbes dose-effet du PAF sur l'agrégation plaquettaire des veaux. En présence du SR 27417, la pente d'agrégation maximale de la courbe ( concentrations du PAF ont été significativement différentes des valeurs de base ( et respectivement). L'agrégation des plaquettes induites par le PAF a été inhibée in vitro par le SR 27417 d'une manière dépendante de la dose. Le médicament a inhibé in vitro l'agrégation induite par le PAF des plaquettes chez le bovin de façon compétitive et réversible (pA2 = 10.46 2.36 molL-1). En conclusion, les résultats de notre étude montrent in vitro que l'addition du SR 27417 aux plaquettes chez le bovin inhibe l'agrégation plaquettaire induite par le PAF.Peer reviewe

Resident CD11b(+)Ly6C(-) Lung Dendritic Cells Are Responsible for Allergic Airway Sensitization to House Dust Mite in Mice.

peer reviewedConventional dendritic cells (DCs) are considered to be the prime initiators of airway allergy. Yet, it remains unclear whether specific DC subsets are preferentially involved in allergic airway sensitization. Here, we systematically assessed the respective pro-allergic potential of individually sorted lung DC subsets isolated from house dust mite antigen (HDM)-treated donor mice, following transfer to naive recipients. Transfer of lung CD11c(+)CD11b(+) DCs, but not CD11c(+)CD11b(-)CD103(+) DCs, was sufficient to prime airway allergy. The CD11c(+)CD11b(+) DC subpopulation was composed of CD11c(+)CD11b(+)Ly6C(+) inflammatory monocyte-derived cells, whose numbers increase in the lungs following HDM exposure, and of CD11c(+)CD11b(+)Ly6C(-) DCs, which remain stable. Counterintuitively, only CD11c(+)CD11b(+)Ly6C(-) DCs, and not CD11c(+)CD11b(+)Ly6C(+) DCs, were able to convey antigen to the lymph nodes and induce adaptive T cell responses and subsequent airway allergy. Our results thus support that lung resident non-inflammatory CD11c(+)CD11b(+)Ly6C(-) DCs are the essential inducers of allergic airway sensitization to the common aeroallergen HDM in mice

Sternal recumbency or suspension by the hind legs immediately after delivery improves respiratory and metabolic adaptation to extra uterine life in newborn calves delivered by caesarean section.

The aim of this study was to evaluate the effect of body positioning immediately after delivery on respiratory and metabolic adaptation to extra-uterine life in newborn calves. One hundred and one Belgian White and Blue calves were delivered at term by an elective caesarean section and were assigned into three categories according to the body position imposed immediately after umbilical cord rupture: 71 calves were placed in lateral recumbency; 16 calves were placed in sternal recumbency and 14 calves were suspended by the hind legs for less than 90 seconds (75 +/- 5 s). Following this initial body position, the calves were allowed to move without restraint. They were examined at birth, 5, 15, 30, 45 and 60 minutes, and 2, 3, 6, 12 and 24 hours after birth by the following measurements: physical examination, heart rate, arterial blood gas analysis, pulmonary function tests using the esophageal balloon catheter technique, arterial and venous blood acid-base balance analysis, rectal temperature, jugular venous blood sampling for the determination of blood glucose, plasma lactate and serum cortisol concentrations, haematologic variables and passive immune transfer variables. Body positioning immediately after delivery clearly influenced respiratory and metabolic adaptation to extra-uterine life in term calves delivered by an elective caesarean section. Systematic sternal recumbency and suspension by the hind legs for less than 90 seconds immediately after umbilical cord rupture had a positive functional impact on postnatal pulmonary mechanics and gas exchange and on postnatal correction of mixed acidosis present at birth, contributing in turn to an enhanced passive immune transfer. These two body positions should be encouraged to improve adaptation at birth in healthy term calves delivered by an elective caesarean section. Evaluation of possible side-effects is required before application in severely asphyxiated calves.Peer reviewe

Epithelial expression of mRNA and protein for IL-6, IL-10 and TNF-α in endobronchial biopsies in horses with recurrent airway obstruction

BACKGROUND: The aim of this study was to evaluate the contribution of bronchial epithelium to airway inflammation, with focus on mRNA and protein expression of cytokines of innate immunity IL-6, IL-10 and TNF-alpha, in horses with Recurrent Airway Obstruction (RAO) during exacerbation and in remission. RESULTS: Despite marked clinical and physiologic alterations between exacerbation and after remission in the RAO horses no differences were detected in either cytokine mRNA or protein levels. Moreover, the expression of investigated cytokines in RAO horses on pasture did not differ from controls.In comparing real-time PCR analysis to results of immunohistochemistry only IL-10 mRNA and protein levels in RAO horses on pasture were significantly correlated (rs = 0.893, p = 0.007). Curiously, in controls examined on pasture the TNF-alpha protein level was positively correlated to IL-10 mRNA expression (rs = 0.967, p = 0.007) and negatively correlated to IL-6 mRNA expression (rs = -0.971, p = 0.001). CONCLUSION: Given the complementary relationship of assessing cytokines directly by immunohistochemistry, or indirectly by PCR to mRNA, the lack of significant changes in either mRNA or protein levels of IL-6, IL-10 or TNF-alpha mRNA in RAO horses in exacerbation suggests that these particular cytokines in bronchial tissue may not play a substantive role in the active inflammation of this disease. To support this contention further studies examining time dependency of expression of IL-6, IL-10 or TNF-alpha are needed, as is expansion of the range of cytokines to include other key regulators of airway inflammation.Peer reviewe

Exercise modifies the innate immune response in equine bronchial epithelial cells

Peer reviewe

Aerossolterapia nas doenças respiratórias em eqüinos

Respiratory problems are frequently implicated in horses as a cause of poor sportive performances. The most frequently occurring lower respiratory tract disorders are chronic obstructive pulmonary disease (COPD), inflammatory airway disease and exercise-induced pulmonary haemorrhage (EIPH). Classically, their treatment includes systemic administration of drugs, but aerosol therapy is now known to be a more specific way to treat these disorders. This article describes the equipment and drugs currently available for aerosol therapy in horses.Affecções respiratórias na espécie eqüina são freqüentemente implicadas como uma das causas de fraco desempenho esportivo. A maior freqüência ocorre nas doenças do sistema respiratório inferior, como a doença pulmonar crônica obstrutiva (COPD), doenças inflamatórias das vias aéreas e hemorragia pulmonar induzida pelo exercício (HPIE). Classicamente, os tratamentos dessas enfermidades incluem as drogas de administração sistêmica, porém, a aerossolterapia é hoje conhecida por ser especificamente um dos melhores tratamentos dessas doenças. A finalidade deste trabalho é de descrever o equipamento e as drogas normalmente utilizadas na aerossolterapia em eqüinos

STAT5 Is an Ambivalent Regulator of Neutrophil Homeostasis

BACKGROUND: Although STAT5 promotes survival of hematopoietic progenitors, STAT5-/- mice develop mild neutrophilia. METHODOLOGY/PRINCIPAL FINDINGS: Here, we show that in STAT5-/- mice, liver endothelial cells (LECs) autonomously secrete high amounts of G-CSF, allowing myeloid progenitors to overcompensate for their intrinsic survival defect. However, when injected with pro-inflammatory cytokines, mutant mice cannot further increase neutrophil production, display a severe deficiency in peripheral neutrophil survival, and are therefore unable to maintain neutrophil homeostasis. In wild-type mice, inflammatory stimulation induces rapid STAT5 degradation in LECs, G-CSF production by LECs and other cell types, and then sustained mobilization and expansion of long-lived neutrophils. CONCLUSION: We conclude that STAT5 is an ambivalent factor. In cells of the granulocytic lineage, it exerts an antiapoptotic function that is required for maintenance of neutrophil homeostasis, especially during the inflammatory response. In LECs, STAT5 negatively regulates granulopoiesis by directly or indirectly repressing G-CSF expression. Removal of this STAT5-imposed brake contributes to induction of emergency granulopoiesis.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe