Tolerability and clinical outcome of coseasonal treatment with Escherichia coli strain Nissle 1917 in grass pollen-allergic subjects.

BACKGROUND

Nonpathogenic Escherichia coli strain Nissle 1917 (EcN) has immunomodulatory properties and can act on different cells which are important for the allergic immune response. Herein, we investigated the efficacy and tolerability of EcN in subjects with grass pollen-dependent allergic rhinoconjunctivitis.

METHODS

Grass pollen-allergic subjects were randomly allocated to receive EcN in a double-blind, placebo-controlled manner. The treatment was performed from 2 months before onset until the end of one grass pollen season (in total: 6 months). The clinical symptom score and the intake of symptomatic medications were assessed. A skin prick test and grass pollen-specific immunoglobulin (Ig) E and IgA were evaluated before and after treatment.

RESULTS

Our results show that coseasonal treatment with EcN in grass pollen-allergic subjects was not superior to placebo as assessed using the symptom-medication score (p = 0.257). Interestingly, an increase [median (range)] in grass pollen-specific IgA was detectable in the EcN group [20,556 LU/ml (1,812-60,800)] versus placebo [5,246 LU/ml (944-50,467)] (p = 0.048).

CONCLUSIONS

The results indicate that 6 months of coseasonal nonspecific immunomodulation by EcN is not sufficient to achieve clinical efficacy in grass pollen-allergic subjects. Future approaches in which such immunomodulators are combined with an allergen-specific protocol might enhance the clinical efficacy of the allergen-specific treatment.