Effect of a Synbiotic "Probiotical®/Bactecal® " in Asthma

Thirty percent of asthmatic patients are not well controlled even with an optimal treatment. There is then a need for new therapeutics allowing a better asthma control. Synbiotic (association of probiotics and prebiotics) have been shown to have anti-inflammatory properties as well as immunomodulatory activities. Moreover, synbiotic appeared to be very well tolerated and safe. One hundred severe asthmatic patients (ACQ\> 1.5 and beclomethasone \> 200 µg per day) will receive "Probiotical ®/Bactecal®" (3 pills a day, content: Lactobacillus, Bifidobacterium et Streptococcus thermophilus, 18 billion of bacteria per pill) or a placebo during 3 months. They will be evaluated before and 1-3-6 months after the first administration and different tests will be realized: * lung function tests (spirometry, lung volumes, diffusing capacity) * exhaled nitric oxide value (FeNo, linked to airway eosinophilia) * blood tests: leucocyte count, c reactive protein, fibrinogen. Plasma and serum will be kept for inflammatory mediators measurements. * sputum induction: leucocyte count and mediators measurements using the sputum supernatant and sputum cells. * bronchial reactivity (bronchial challenge test) * microvascular health: to assess the glycocalyx state, see: http://glycocheck.com/ for details. * questionnaires: asthma control test (ACT), asthma control questionnaire (ACQ), asthma quality of life questionnaire (AQLQ ).