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Biomedical subjects

Pierre Lekeux

Publications and source records attributed to Pierre Lekeux.

13 recordsLinked to original sources
PubMed2006

DNA binding activity of transcription factors in bronchial cells of horses with recurrent airway obstruction.

Horses with recurrent airway obstruction (RAO) present many similarities with human asthmatics including airway inflammation, hyperresponsiveness, reversible obstruction, and increased NF-kappaB expression. Studies in experimental asthma models have shown that transcriptions factors such as activator protein-1 (AP-1), GATA-3, cyclic AMP response element binding protein (CREB) and CAAT/enhancer binding protein (C/EBP) may also play an important role in airway inflammation. The purpose of this study was to measure DNA binding activity of these transcription factors in the airways of horses with RAO and to compare it to pulmonary function and bronchoalveolar lavage fluid (BALF) cytology. Seven horses with RAO and six control animals were studied during a moldy hay challenge and after 2 months at pasture. Pulmonary function, BALF cytology and transcription factors' activities in bronchial brushings were measured during hay and pasture exposures. During moldy hay challenge, RAO-affected horses developed severe airway obstruction and inflammation and a significantly higher airway AP-1 binding activity than in controls. After 2 months on pasture, pulmonary function and airway AP-1 binding activity were not different between RAO and control horses. The DNA binding activity of CREB in airways of RAO-affected horses increased significantly after 2 months at pasture and became higher than in controls. A significant positive correlation was detected between AP-1 binding activity and indicators of airway obstruction and inflammation. Airway GATA-3, CEBP and CREB binding activities were negatively correlated with indices of airway obstruction. However, contrarily to CREB binding activity, GATA-3 and CEBP binding activities were not different between RAO and control horses and were unaffected by changes in environment. These data support the view that AP-1 and CREB play a role in modulating airway inflammation in horses with RAO.

Animals↗
PubMed2006

Myeloperoxidase concentration in bronchoalveolar lavage fluid from healthy horses and those with recurrent airway obstruction.

The aim of this work was to measure the myeloperoxidase (MPO) concentration in bronchoalveolar lavage (BAL) fluid collected from horses with recurrent airway obstruction (RAO), both in crisis and in remission, as well as from healthy horses. Seven horses with RAO were exposed to moldy hay until the maximum change in pleural pressure was greater than 1.5 kPa. At that point, BAL was performed, and the total cell counts and percentages in the fluid were immediately determined. To measure the MPO concentration in BAL-fluid supernatant, we used a specific enzyme-linked immunosorbent assay with polyclonal antibodies against equine MPO. The tests were repeated on the horses with RAO after they had spent 2 mo on pasture. Six healthy horses serving as controls underwent the same tests. The absolute and relative neutrophil counts and the MPO concentration in the BAL fluid were significantly greater in the horses with an RAO crisis than in the control horses. After 2 mo on pasture, the horses that had been in RAO crisis were clinically normal, and their neutrophil counts and MPO levels in BAL fluid had significantly decreased; during remission their neutrophil counts were not significantly different from those in the healthy horses, but their MPO concentration remained significantly higher. This study showed that determining the MPO concentration in a horse's BAL fluid is technically possible and that during remission from RAO the concentration remains higher than normal. Thus, MPO may be a marker of neutrophil presence and activation in the lower airways.

Animals↗
PubMed2005

Treatment of experimental asthma by decoy-mediated local inhibition of activator protein-1.

RATIONALE: Asthma is associated with increased expression of a typical array of genes involved in immune and inflammatory responses, including those encoding the prototypic Th2 cytokines interleukin (IL) 4, IL-5, and IL-13. Most of these genes contain binding sites for activator protein-1 (AP-1) within their promoter and are therefore believed to depend on AP-1 for their expression, suggesting that this transcription factor could be of particular importance in asthma pathophysiology. OBJECTIVE: To clarify the role of AP-1 in the effector phase of pulmonary allergy. METHODS: Ovalbumin (OVA)-sensitized mice were intratracheally given decoy oligodeoxyribonucleotides (ODNs) specifically directed to AP-1 or scrambled control ODNs before challenge with aerosolized OVA. Twenty-four hours after the last OVA challenge, airway hyperresponsiveness was measured and allergic airway inflammation was evaluated quantitatively. AP-1 decoys were localized using flow cytometry and immunohistochemistry. AP-1 activity in the lung was assessed using electrophoretic mobility shift assay. MEASUREMENTS AND MAIN RESULTS: Intratracheally delivered AP-1 decoys efficiently targeted airway immune cells, thus precluding AP-1 activation on OVA challenge. Decoy-mediated local inhibition of AP-1 resulted in significant attenuation of all the pathophysiologic features of experimental asthma-namely, eosinophilic airway inflammation, airway hyperresponsiveness, mucous cell hyperplasia, production of allergen-specific immunoglobulins, and synthesis of IL-4, IL-5, and IL-13. Scrambled control ODNs had no detectable effects. CONCLUSIONS: Our results reveal a key role for AP-1 in the effector phase of pulmonary allergy and indicate that specific AP-1 inhibition in the airways may have therapeutic value in the control of established asthma.

Animals↗
PubMed2004

Pro-inflammatory properties for thiazolidinediones.

Thiazolidinediones (TZDs) are pharmacological ligands of the peroxisome proliferator-activated receptor (PPAR)-gamma that are extensively used in the treatment of type II diabetes. Recently, an anti-inflammatory potential for TZDs has been suggested, based on observations that these compounds may inhibit pro-inflammatory cytokine expression in vitro and may attenuate the inflammatory response in vivo. Here, we show that the TZDs rosiglitazone (RSG) and troglitazone (TRO) do not inhibit the inflammatory response to tumor necrosis factor (TNF)-alpha in various epithelial cell types. On the contrary, both RSG and TRO significantly potentiated TNF-alpha-induced production of granulocyte/macrophage-colony-stimulating factor, interleukin (IL)-6 and/or IL-8 in these cells. This increase in pro-inflammatory cytokine expression was functionally significant as supernatants from cells co-treated with TNF-alpha and TZDs displayed increased neutrophil pro-survival activity when compared with supernatants from cells treated with TNF-alpha alone. Additionally, it was shown that TZDs enhance cytokine expression at the transcriptional level, but that the pro-inflammatory effects of TZDs are independent on PPARgamma, nuclear factor kappaB or mitogen-activated protein kinase activation. Our study shows that TZDs may potentiate the inflammatory response in epithelial cells, a previously unappreciated effect of these compounds.

Cell Line↗
PubMed2004

Selective blockade of NF-kappa B activity in airway immune cells inhibits the effector phase of experimental asthma.

Knockout mice studies have revealed that NF-kappaB plays a critical role in Th2 cell differentiation and is therefore required for induction of allergic airway inflammation. However, the questions of whether NF-kappaB also plays a role in the effector phase of airway allergy and whether inhibiting NF-kappaB could have therapeutic value in the treatment of established asthma remain unanswered. To address these issues, we have assessed in OVA-sensitized wild-type mice the effects of selectively antagonizing NF-kappaB activity in the lungs during OVA challenge. Intratracheal administration of NF-kappaB decoy oligodeoxynucleotides to OVA-sensitized mice led to efficient nuclear transfection of airway immune cells, but not constitutive lung cells and draining lymph node cells, associated with abrogation of NF-kappaB activity in the airways upon OVA provocation. NF-kappaB inhibition was associated with strong attenuation of allergic lung inflammation, airway hyperresponsiveness, and local production of mucus, IL-5, IL-13, and eotaxin. IL-4 and OVA-specific IgE and IgG1 production was not reduced. This study demonstrates for the first time that activation of NF-kappaB in local immune cells is critically involved in the effector phase of allergic airway disease and that specific NF-kappaB inhibition in the lungs has therapeutic potential in the control of pulmonary allergy.

Allergens↗
PubMed2003

Use of the impulse oscillometry system for testing pulmonary function during methacholine bronchoprovocation in horses.

OBJECTIVE: To compare sensitivity of the impulse oscillometry system (IOS) with that of the conventional reference technique (CRT; ie, esophageal balloon method) for pulmonary function testing in horses. ANIMALS: 10 horses (4 healthy; 6 with recurrent airway obstruction [heaves] in remission). PROCEDURE: Healthy horses (group-A horses) and heaves-affected horses (group-B horses) were housed in a controlled environment. At each step of a methacholine bronchoprovocation test, threshold concentration (TC(2SD); results in a 2-fold increase in SD of a value) and sensitivity index (SI) were determined for respiratory tract system resistance (R(rs)) and respiratory tract system reactance (X(rs)) at 5 to 20 Hz by use of IOS and for total pulmonary resistance (RL) and dynamic lung compliance (C(dyn)), by use of CRT. RESULTS: Bronchoconstriction resulted in an increase in R(rs) at 5 Hz (R(5Hz)) and a decrease in X(rs) at all frequencies. Most sensitive parameters were X(rs) at 5 Hz (X(5Hz)), R(5Hz), and R(5Hz):R(10Hz) ratio; RL and the provocation concentration of methacholine resulting in a 35% decrease in dynamic compliance (PC(35)C(dyn)) were significantly less sensitive than these IOS parameters. The TC(2SD) for X(rs) at 5 and 10 Hz was significantly lower in group-B horses, compared with group-A horses. The lowest TC(2SD) was obtained for X(5Hz) in group-B horses and R(5Hz) in group-A horses. CONCLUSIONS AND CLINICAL RELEVANCE: In contrast to CRT parameters, IOS parameters were significantly more sensitive for testing pulmonary function. The IOS provides a practical and noninvasive pulmonary function test that may be useful in assessing subclinical changes in horses.

Airway Obstruction↗
PubMed2002

Constitutive nuclear factor-kappaB activity preserves homeostasis of quiescent mature lymphocytes and granulocytes by controlling the expression of distinct Bcl-2 family proteins.

Constitutive nuclear factor kappaB (NF-kappaB) activity protects quiescent mature immune cells from spontaneous apoptosis. Here, we examined whether NF-kappaB exerts its antiapoptotic function in these cells through the control of Bcl-2 family proteins. Specific pharmacologic inhibitors of NF-kappaB were used to achieve total NF-kappaB inactivation in quiescent human blood lymphocytes, granulocytes, and monocytes. NF-kappaB inhibition induced drastic lymphocyte and granulocyte apoptosis, but only moderate monocyte apoptosis. T- and B-cell apoptosis was slow and associated with a gradual down-regulation of the prosurvival Bcl-2 family proteins Bcl-x(L) and Bcl-2, respectively. By contrast, granulocyte apoptosis was fast and accompanied by a rapid cellular accumulation of Bcl-x(S), the proapoptotic Bcl-x isoform that is generated from alternative splicing of the bcl-x pre-mRNA. Finally, antisense bcl-x(L) and bcl-2 knockdown in T and B cells, respectively, and induction of Bcl-x(S) expression in granulocytes through antisense oligonucleotide-mediated redirection of bcl-x pre-mRNA splicing were sufficient to induce significant apoptosis in these cells. Taken together, these results reveal that basal NF-kappaB activity preserves homeostasis of quiescent mature lymphocytes and granulocytes through regulation of distinct members of the Bcl-2 family. This study sheds light on the constitutive mechanisms by which NF-kappaB maintains defense integrity.

Apoptosis↗
PubMed2002

A proinflammatory role for the cyclopentenone prostaglandins at low micromolar concentrations: oxidative stress-induced extracellular signal-regulated kinase activation without NF-kappa B inhibition.

An anti-inflammatory role and therapeutic potential for cyclopentenone PGs (cyPGs) has been suggested, based on observations that levels of cyPGs in exudates increase during the resolution phase of inflammation, and that exogenous cyPGs may attenuate the inflammatory response in vivo and in vitro mainly through inhibition of NF-kappaB, a critical activator of inflammatory gene expression. However, exogenous cyPGs inhibit NF-kappaB only at concentrations substantially higher than those of endogenous cyPGs present in inflammatory fluids, thus challenging the hypothesis that cyPGs are naturally occurring inhibitors of inflammation and suggesting that cyPGs at low concentrations might have previously unappreciated effects. In this study, using various cell types, we report that cyPGs, when used at concentrations substantially lower than required for NF-kappaB inhibition (viz, low micromolar concentrations), significantly potentiate the inflammatory response to TNF-alpha. At these concentrations, cyPGs induce production of reactive oxygen species, thereby synergizing with TNF-alpha to activate the extracellular signal-regulated kinase 1/2, an activation which in turn potentiates proinflammatory cytokine expression at both transcriptional and posttranscriptional levels. Our study establishes a proinflammatory role for cyPGs at low micromolar concentrations, raises the possibility that cyPGs do not act as physiologic anti-inflammatory mediators, and questions the therapeutic potential of these compounds.

Adjuvants, Immunologic↗
PubMed2002

CD40 engagement enhances eosinophil survival through induction of cellular inhibitor of apoptosis protein 2 expression: Possible involvement in allergic inflammation.

BACKGROUND: CD40 engagement enhances eosinophil survival, suggesting a role for this receptor in the development of eosinophilia. OBJECTIVE: We examined whether CD40 enhances eosinophil survival by inducing the expression of antiapoptotic proteins. Three members of the inhibitor of apoptosis protein (IAP) family, namely cellular (c)-IAP1, c-IAP2, and XIAP, and 2 antiapoptotic proteins of the Bcl-2 family, namely Bcl-x(L) and Bfl-1/A1, were investigated. METHODS: Blood and sputum were obtained from healthy subjects and atopic asthmatic patients. Blood eosinophils were isolated by means of magnetic selection. Expression of CD40, IAPs, and Bcl-2 proteins was investigated by using flow cytometry, immunoblotting, or both. CD40 stimulation was achieved with agonistic antibodies or soluble ligands. Apoptosis was assessed by staining with propidium iodide and FITC-conjugated annexin-V. c-IAP2 expression was inhibited with antisense oligonucleotides. RESULTS: Freshly isolated eosinophils from healthy and asthmatic patients did not express CD40. Conversely, eosinophils expressed CD40 spontaneously when cultured for 48 hours. At this time point, CD40 stimulation significantly delayed eosinophil apoptosis. Inhibition of eosinophil apoptosis was accompanied by induction of c-IAP2 but not c-IAP1, XIAP, Bcl-x(L), or Bfl-1/A1 expression. Antisense knockdown of c-iap2 abolished CD40-induced enhancement of eosinophil survival. Sputum cells from asthmatic patients, unlike those from healthy subjects, substantially expressed CD40 and c-IAP2. Moreover, a strong correlation was found between the percentage of eosinophils in the sputum from asthmatic patients and the sputum level of CD40 and c-IAP2 expression. CONCLUSION: The results demonstrate that CD40 engagement enhances eosinophil survival through induction of c-IAP2 expression and suggest a role for this mechanism in allergic inflammation.

Adult↗
PubMed2002

Adaptation to multiday ozone exposure is associated with a sustained increase of bronchoalveolar uric acid.

The phenomenon of ozone tolerance is described, but the underlying mechanisms remain unknown. We tested whether adaptation to multiday ozone exposure was related to an upregulated pulmonary antioxidant defence. Six calves were exposed to 0.75 ppm ozone, 12 h day(-1) for seven consecutive days. Pulmonary function tests and bronchoalveolar lavage (BAL) were performed before, after the first (D1), third (D3) and seventh (D7) exposure. Differential cell count, total proteins, 8-epi-PGF2alpha, glutathione and uric acid were determined in BAL. Dynamic lung compliance and arterial oxygen tension were significantly decreased and lung oedema impaired pulmonary function on D1. By repeating ozone exposures, progressive functional adaptation occurred. Ozone induced a significant increase of BAL neutrophil percentage on D1. On D3 and D7, neutrophil percentage was progressively decreased, but remained significantly elevated. BAL total proteins were significantly increased on D1 and decreased progressively until D7. 8-Epi-PGF2alpha was significantly increased on D1 and was returned to baseline on D3 and D7, whilst glutathione significantly increased on D3 and returned to baseline on D7. Uric acid was increased ten-fold on D1. On D3, uric acid was increased six-fold and was persistently elevated at D7. This study suggests that ozone adaptation of functional and inflammatory variables is accompanied with sustained BAL uric acid elevation.

Animals↗
PubMedDate not supplied

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.

Acid-Base Equilibrium↗
PubMedDate not supplied

Effect of beclomethasone dipropionate and dexamethasone isonicotinate on lung function, bronchoalveolar lavage fluid cytology, and transcription factor expression in airways of horses with recurrent airway obstruction.

Glucocorticoid (GC) therapy is recognized to be effective for the treatment of recurrent airway obstruction (RAO) in horses. Anti-inflammatory properties of GC are thought to be mediated by suppression of inflammatory gene expression via inhibition of transcription factors such as nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). The purpose of this study was to evaluate the effect of low-dose inhaled beclomethasone dipropionate and injectable dexamethasone 21-isonicotinate on clinical signs, pulmonary function, airway cytology, and activity of NF-kappaB and AP-1 in bronchial cells of RAO-affected horses. Seven horses with RAO were exposed to moldy hay until they developed airway obstruction on 3 separate occasions. In a crossover design, they were then treated with a placebo (injection on day 1), inhaled beclomethasone (500 microg q12h for 10 days), or dexamethasone (0.06 mg/kg, IM on day 1) and monitored for 10 days. Pulmonary function, bronchoalveolar lavage fluid cytology, and NF-kappaB and AP-1 activity in bronchial brushing cells were measured before (day 1) and after treatment (day 10). Treatment with beclomethasone resulted in significantly improved pulmonary function of RAO-affected horses compared with placebo and dexamethasone treatments. However, none of the treatments had an effect on bronchoalveolar lavage fluid cytology or NF-kappaB and AP-1 activity. These findings reveal that, in a model of severe RAO, the benefits of low-dose inhaled beclomethasone on pulmonary function are not accompanied by a decrease in airway inflammatory cells or a suppression of transcription factors NF-kappaB and AP-1 DNA-binding activity.

Animals↗