Prevention of asthma exacerbations by the regular use of a bacterial lysate (Broncho-Vaxom).

Rationale: Bacterial lysates can modulate the immune system by effects on T-cells (skewing to the Th1-type by Treg cells) and on the inflammatory response to microorganisms. There is evidence for a reduction of infectious- and asthmatic symptoms in young children after using bacterial lysates. Yet, the effect of bacterial lysates on reduction of asthma severity and inflammatory parameters in adolescents and adults with moderate to severe asthma has not yet been studied. However, they might well benefit well from reduction of respiratory infections and attenuation of Th2-related inflammation. Therefore, we want to initiate a clinical- and laboratory study into the effects of regular treatment with bacterial lysates in adolescents and adults with proven asthma.
Main objective: To diminish the number and duration of asthma exacerbations with the regular use of a bacterial lysate.
Study design: Investigator-initiated double-blind randomized controlled trial.
Study population: Patients aged 12-60 years with proven asthma (airway responsiveness proven by reversibility and histamine PC20 < 8 mg/ml)) who have recurrent airway signs and symptoms despite optimal maintenance medication (medium/high dose inhalation corticosteroid and long-acting B2-agonist; GINA 4) and >= 2 exacerbations in the previous year.
Intervention (if applicable): Bacterial lysate OM-85 (Broncho-Vaxom, OM Pharma) 7 mg capsules versus identical placebo capsules; given in the first consecutive 10 days of each month (October-March (6 months/year)), during 2 years.
Main study parameters/endpoints: Number of astma exacerbations within 18 months after initiation of intervention.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Broncho-Vaxom is a bacterial lysate that has been used for years in children and adults with recurrent respiratory tract infections. However, for study purposes, it is hardly studied in asthmatic individuals, till now only in young children. In older subjects with COPD, bacterial lysates seem to have a positive effect on lung health. We want to investigate whether this observed positive effect on lung health could also be observed in adolescent and adult asthmatic patients.

Primary:
The number and duration of asthma exacerbations will diminish with the regular use of a bacterial lysate.

Secondary:
-Regular bacterial lysate treatment improves health (pulmonary function, quality of life, medication use).
- Respiratory- and gut microbial colonization dynamics change with the regular use of a bacterial lysate
-Airway- and blood immunological markers (T-cell dynamics; cytokine production, ILC2-activity) will change with the regular use of a bacterial lysate.

Primary outcome: T= 18 months.
Other outcomes: T=18 and T=30 months

Bacterial lysate OM-85 (Broncho-Vaxom, OM Pharma) 7 mg capsules versus identical placebo capsules; given in the first consecutive 10 days of each month (October-March (6 months/year)), during 2 years.