Abstract
BACKGROUND: Therapies for peanut allergy (PNA) are urgently needed. Food Allergy Herbal Formula-2 (FAHF-2) has profound therapeutic effects in a murine PNA model and is safe for food-allergic adults in clinical trials. However, the large FAHF-2 pill-load is not conducive to clinical studies in children. Thus, refining FAHF-2 to decrease pill-load is essential for the inclusion of children in clinical trials and to facilitate studying FAHF-2 as a clinically useful botanical drug. OBJECTIVES: Testing long-term efficacy and safety of a butanol-purified extract of FAHF-2 (B-FAHF-2) in a murine model of PNA, and to explore its immunological mechanisms of action. METHODS: FAHF-2 was purified by butanol extraction. C3H/HeJ mice with established PNA received the first course of B-FAHF-2 at 6 mg, twice daily for 7 weeks (PNA/B-FAHF-2) or water (PNA/sham) and were then challenged immediately after completing the treatment and six more times every 1-2 months post-treatment up to week 50. Mice then received a second course of B-FAHF-2 treatment at week 52 and were challenged at week 65. In vivo and in vitro immunological effects on T, B and mast cells were also determined. RESULTS: Butanol purification reduced the volume of the effective dose ∼5-fold. All PNA/B-FAHF-2 mice were completely protected from PN anaphylaxis until the fifth challenge after the first course of treatment, as compared with PNA/sham mice. Partial protection persisted up to 50 weeks. A second treatment course restored complete protection. B-FAHF-2 significantly suppressed Th2 cytokine, IgE and histamine levels in vivo, and showed direct inhibition of Th2, IgE-producing B cells and mast cell activation in vitro. B-FAHF-2 had a high margin of safety. CONCLUSION AND CLINICAL RELEVANCE: B-FAHF-2 produced long-lasting protection against PN anaphylaxis for approximately half of the murine life span without side-effects. B-FAHF-2 exhibited direct effects on multiple food allergy effector cells.