Renaud Louis

Tumour necrosis factor (TNF) gene polymorphism influences TNF-α production in lipopolysaccharide (LPS)-stimulated whole blood cell culture in healthy humans

TNF‐α is involved in infectious and immuno‐inflammatory diseases. Different individuals may have different capacities for TNF‐α production. This might determine a predisposition to develop some complications or phenotypes of these diseases. The aims of our study were to assess the inter‐individual variability of TNF‐α production and to correlate this variability to a single base pair polymorphism located at position −308 in TNF gene. We studied 62 healthy individuals. TNF‐α production after LPS stimulation was evaluated using a whole blood cell culture model. The TNF gene polymorphism was studied by an allele‐specific polymerase chain reaction. Other cytokines produced in the culture, soluble CD14 concentrations and expression of CD14 on blood cells were also measured. Among the 62 individuals, 57 were successfully genotyped. There were 41 TNF1 homozygotes and 16 TNF1/TNF2 heterozygotes. TNF‐α production after LPS stimulation of whole blood cell culture was higher among TNF2 carriers than among TNF1 homozygotes (929 pg/ml (480–1473 pg/ml) versus 521 pg/ml (178–1307 pg/ml); P < 0.05). This difference was even more significant after correction of TNF‐α production for CD14 expression on blood cells. In conclusion, the single base pair polymorphism at position −308 in the TNF gene may influence TNF‐α production in healthy individuals.

MMP-2- and MMP-9-Linked Gelatinolytic Activity in the Sputum from Patients with Asthma and Chronic Obstructive Pulmonary Disease

Background: The course of asthma and chronic obstructive pulmonary disease (COPD) is associated with bronchial morphological changes. Metalloproteinases are thought to play a role in these structural changes. Methods: We studied the gelatinolytic activity present in the induced sputum from 20 patients with asthma, 20 with COPD and 19 healthy controls. The assessment of gelatinolytic activity was performed by quantitative zymography, and gelatinolytic species were identified by Western blot analysis. Tissue inhibitor of metalloproteinase-1 (TIMP-1) was detected by reverse zymography and ELISA. Results: From zymography, we found significantly higher gelatinolytic activity linked to pro-matrix metalloproteinase-9 (pro-MMP-9) in the sputum from asthmatics (p < 0.0001) and COPD patients (p < 0.0001) compared to the control group. Furthermore, the activated form of MMP-9 (85 kD) was found in the sputum from 60% of asthmatics and 85% of COPD patients, but was absent in that of control subjects (p < 0.0001). Importantly, although less frequently detectable than pro-MMP-9, pro- MMP-2 (72 kD) was found more frequently in asthmatics (50%) than in control subjects (5%) (p < 0.005). We also described two unusual gelatinolytic species of 45 and 120 kD and showed that they derived from MMP-9 according to their ability to bind gelatin and anti-MMP-9 antibody. Levels of TIMP-1 were higher in asthmatics (p < 0.05) and COPD patients (p < 0.05) than in controls. Conclusion: Asthmatics and COPD patients display an increased gelatinolytic activity linked to MMP-2 and MMP-9 and higher levels of TIMP-1 in their sputum.

Methods of sputum processing for cell counts, immunocytochemistry and in situ hybridisation

Since the first attempts to use standardised methods for sampling induced airways sputum, two methods for processing the expectorate have evolved. The first involves selecting all viscid or denser portions from the expectorated sample with the aid of an inverted microscope 1, 2. This method has been extensively evaluated and reported in detail 2–4. The second approach involves processing the entire expectorate, comprising sputum plus variable amounts of saliva 5. Recent modifications to this method include collecting saliva and sputum separately in order to reduce salivary contamination 6–8. Both methods have advantages and disadvantages. The advantages of using selected sputum are: squamous cell contamination is 20% of all recovered cells 4. There is conflicting data as to whether or not differential cell counts (DCCs) differ between the two methods. One study reported a higher percentage of eosinophils in sputum processed by the selection method compared to the entire expectorate 9 but this has not been confirmed in other studies 2, 6, 10. Although, both the selected …

Matrix metalloproteinase-9 deficiency impairs cellular infiltration and bronchial hyperresponsiveness during allergen-induced airway inflammation.

We investigated the specific role of matrix metalloproteinase (MMP)-9 in allergic asthma using a murine model of allergen-induced airway inflammation and airway hyperresponsiveness in MMP-9(-/-) mice and their corresponding wild-type (WT) littermates. After a single intraperitoneal sensitization to ovalbumin, the mice were exposed daily either to ovalbumin (1%) or phosphate-buffered saline aerosols from days 14 to 21. Significantly less peribronchial mononuclear cell infiltration of the airways and less lymphocytes in the bronchoalveolar lavage fluid were detected in challenged MMP-9(-/-) as compared to WT mice. In contrast, comparable numbers of bronchoalveolar lavage fluid eosinophils were observed in both genotypes. After allergen exposure, the WT mice developed a significant airway hyperresponsiveness to carbachol whereas the MMP-9(-/-) mice failed to do so. Allergen exposure induced an increase of MMP-9-related gelatinolytic activity in WT lung extracts. Quantitative reverse transcriptase-polymerase chain reaction showed increased mRNA levels of MMP-12, MMP-14, and urokinase-type plasminogen activator after allergen exposure in the lung extracts of WT mice but not in MMP-9-deficient mice. In contrast, the expression of tissue inhibitor of metalloproteinases-1 was enhanced after allergen exposure in both groups. We conclude that MMP-9 plays a key role in the development of airway inflammation after allergen exposure.

Matrix metalloproteinase-9-mediated dendritic cell recruitment into the airways is a critical step in a mouse model of asthma

Dendritic cells (DCs) appear to be strategically implicated in allergic diseases, including asthma. Matrix metalloproteinase (MMP)-9 mediates transmigration of inflammatory leukocytes across basement membranes. This study investigated the role of MMP-9 in airway DC trafficking during allergen-induced airway inflammation. MMP-9 gene deletion affected the trafficking of pulmonary DCs in a specific way: only the inflammatory transmigration of DCs into the airway lumen was impaired, whereas DC-mediated transport of airway Ag to the thoracic lymph nodes remained unaffected. In parallel, the local production of the Th2-attracting chemokine CC chemokine ligand 17/thymus and activation-regulated chemokine, which was highly concentrated in purified lung DCs, fell short in the airways of allergen-exposed MMP-9−/− mice. This was accompanied by markedly reduced peribronchial eosinophilic infiltrates and impaired allergen-specific IgE production. We conclude that the specific absence of MMP-9 activity inhibits the development of allergic airway inflammation by impairing the recruitment of DCs into the airways and the local production of DC-derived proallergic chemokines.

Matrix Metalloproteinase-8 Deficiency Promotes Granulocytic Allergen-Induced Airway Inflammation

Matrix metalloproteinases (MMPs) are involved in inflammatory reaction, including asthma-related airway inflammation. MMP-8, mainly produced by neutrophils, has recently been reported to be increased in the bronchoalveolar lavage fluid (BALF) from asthmatic patients. To evaluate the role of MMP-8 in asthma, we measured MMP-8 expression in lung tissue in an OVA-sensitized mouse model of asthma and addressed the effect of MMP-8 deletion on allergen-induced bronchial inflammation. MMP-8 production was increased in lungs from C57BL/6 mice exposed to allergens. After allergen exposure, MMP-8−/− mice developed an airway inflammation characterized by an increased neutrophilic inflammation in BALF and an increased neutrophilic and eosinophilic infiltration in the airway walls. MMP-8 deficiency was associated with increased levels of IL-4 and anti-OVA IgE and IgG1 in BALF and serum, respectively. Although allergen exposure induced an enhancement of LPS-induced CXC chemokine, KC, and MIP-2 levels in BALF and lung parenchyma, no difference was observed between the two genotypes. Inflammatory cell apoptosis was reduced in the lungs from MMP-8−/− mice. For the first time, our study evidences an important role of MMP-8 in the control of neutrophilic and eosinophilic infiltration during allergen-induced lung inflammation, and demonstrates that the anti-inflammatory effect of MMP-8 is partly due to a regulation of inflammatory cell apoptosis.

''Real-life'' effectiveness of omalizumab in patients with severe persistent allergic asthma: The PERSIST study *

OBJECTIVE To evaluate the 16- and 52-week effectiveness of add-on omalizumab treatment under real-life heterogeneity in patients, settings, and physicians in an open-label, multicenter, pharmaco-epidemiologic study of patients with severe persistent allergic asthma in Belgium. METHODS Effectiveness outcomes included improvement in 2005 global initiative for asthma (GINA) classification, physician-rated global evaluation of treatment effectiveness (GETE), quality of life (Juniper asthma-related quality of life (AQLQ) and European quality of life questionnaire 5 dimensions (EQ-5D)), and severe asthma exacerbations. Patients studied included both intent-to-treat and per-protocol populations. RESULTS The sample (n=158) had a mean age of 48.17+/-17.18 years, and a slight majority were female (53.8%). Despite being treated with high-dose inhaled corticosteroids and long-acting beta2-agonists, all patients experienced frequent symptoms and had exacerbations in the past year. At 16 weeks, >82% had good/excellent GETE (P values <0.001), >82% had an improvement in total AQLQ scores of > or =0.5 points (P<0.001), and >91% were severe exacerbation-free (P<0.001). At 52 weeks, >72% had a good/excellent GETE rating (P<0.001), >84% had improvements in total AQLQ score of > or =0.5 points (P<0.001), >56% had minimally important improvements in EQ-5D utility scores (P=0.012), and >65% were severe exacerbation-free (P<0.001). Significant reductions in healthcare utilization compared to the one year prior to treatment were noted. CONCLUSION The PERSIST study shows better physician-rated effectiveness, greater improvements in quality of life, greater reductions in exacerbation rates, and greater reductions in healthcare utilization than previously reported in efficacy studies. Under real-life conditions, omalizumab is effective as add-on therapy in the treatment of patients with persistent severe allergic asthma.

Mouse models of asthma: a comparison between C57BL/6 and BALB/c strains regarding bronchial responsiveness, inflammation, and cytokine production.

ObjectiveAnimal models of asthma mimic major features of human disease. Since the genetic background of experimental animals might affect hyperresponsiveness and inflammation, we studied its potential influence and the mechanisms leading to differences in strains.MethodsWe applied a mouse model of allergic asthma to BALB/c and C57BL/6 mice.ResultsBALB/c mice displayed greater levels of airway reactivity to methacholine than C57BL/6 mice. Moreover, BALB/c mice exhibited higher numbers of mast cells in lung tissue when compared to C57BL/6. On the contrary, eosinophil and neutrophil counts in bronchoalveolar lavage fluid (BALF) as well as peribronchial eosinophilia were greater in C57BL/6. IL (Interleukin)-4, IL-5, IL-13, and CCL11 levels measured in whole-lung extracts were higher in BALB/c, while, in sharp contrast, CCL11 and CCL5 levels were higher in BALF of C57BL/6 mice.ConclusionsWe observed phenotypic differences between C57BL/6 and BALB/c mice in an asthma model with different distributions of pro-inflammatory cytokines and inflammatory cells.

Exhaled nitric oxide thresholds associated with a sputum eosinophil count ≥3% in a cohort of unselected patients with asthma

Background It has been claimed that exhaled nitric oxide (FeNO) could be regarded as a surrogate marker for sputum eosinophil count in patients with asthma. However, the FeNO threshold value that identifies a sputum eosinophil count ≥3% in an unselected population of patients with asthma has been poorly studied. Methods This retrospective study was conducted in 295 patients with asthma aged 15–84 years recruited from the asthma clinic of University Hospital of Liege. Receiver-operating characteristic (ROC) curve and logistic regression analysis were used to assess the relationship between sputum eosinophil count and FeNO, taking into account covariates such as inhaled corticosteroids (ICS), smoking, atopy, age and sex. Results Derived from the ROC curve, FeNO ≥41 ppb gave 65% sensitivity and 79% specificity (AUC=0.777, p=0.0001) for identifying a sputum eosinophil count ≥3%. Using logistic regression analysis, a threshold of 42 ppb was found to discriminate between eosinophilic and non-eosinophilic asthma (p<0.0001). Patients receiving high doses of ICS (≥1000 μg beclometasone) had a significantly lower FeNO threshold (27 ppb) than the rest of the group (48 ppb, p<0.05). Atopy also significantly altered the threshold (49 ppb for atopic vs 30 ppb for non-atopic patients, p<0.05) and there was a trend for a lower threshold in smokers (27 ppb) compared with non-smokers (46 ppb, p=0.066). Age and sex did not affect the relationship between FeNO and sputum eosinophilia. When combining all variables into the logistic model, FeNO (p<0.0001), high-dose ICS (p<0.05) and smoking (p<0.05) were independent predictors of sputum eosinophilia, while there was a trend for atopy (p=0.086). Conclusion FeNO is able to identify a sputum eosinophil count ≥3% with reasonable accuracy and thresholds which vary according to dose of ICS, smoking and atopy.

Distribution of sputum cellular phenotype in a large asthma cohort: predicting factors for eosinophilic vs neutrophilic inflammation.

BackgroundPhenotyping asthma according to airway inflammation allows identification of responders to targeted therapy. Induced sputum is technically demanding. We aimed to identify predictors of sputum inflammatory phenotypes according to easily available clinical characteristics.MethodsThis retrospective study was conducted in 508 asthmatics with successful sputum induction recruited from the University Asthma Clinic of Liege. Receiver-operating characteristic (ROC) curve and multiple logistic regression analysis were used to assess the relationship between sputum eosinophil or neutrophil count and a set of covariates. Equations predicting sputum eosinophils and neutrophils were then validated in an independent group of asthmatics.ResultsEosinophilic (≥3%) and neutrophilic (≥76%) airway inflammation were observed in 46% and 18% of patients respectively. Predictors of sputum eosinophilia ≥3% were high blood eosinophils, FENO and IgE level and low FEV1/FVC. The derived equation was validated with a Cohen’s kappa coefficient of 0.59 (p < 0.0001). ROC curves showed a cut-off value of 220/mm3 (AUC = 0.79, p < 0.0001) or 3% (AUC = 0.81, p < 0.0001) for blood eosinophils to identify sputum eosinophilia ≥3%. Independent predictors of sputum neutrophilia were advanced age and high FRC but not blood neutrophil count.ConclusionEosinophilic and paucigranulocytic asthma are the dominant inflammatory phenotypes. Blood eosinophils provide a practical alternative to predict sputum eosinophilia but sputum neutrophil count is poorly related to blood neutrophils.