An in vitro study to explore the modulation of eosinophil effector function in human allergic peripheral blood eosinophils using enzymatically extracted salmonid oil

Abstract

Background: The consumption of oily fish in early childhood diets has been correlated to a reduction in the progression of asthma during adolescence and young adulthood. Extending these results to studies on supplementation with omega-3 fish oils has led to equivocal results, with no clear results. One subset of asthma patients is classified as steroid-treatment resistant, which may be attributable to eosinophil dysfunction. This in-vitro study investigated the prophylactic effect of enzymatically extracted salmon oil, as a proxy for eating fresh whole oily fish, on eosinophil function using allergic human peripheral blood eosinophils.

Methods: We measured three eosinophil effector functions in allergic human peripheral blood eosinophils after prophylactic treatment with enzymatically extracted salmonid oil. We measured changes in: i) eosinophil shape change in normal PMNL ii) integrin upregulation in normal PMNL and iii) eosinophil apoptosis. We further measured changes in these functions after prophylactic treatment with omega-3 fish oil, krill oil, and fractions of the salmon oil subjected to several commercial fish oil processing conditions.

Results: Prophylactic treatment of allergic human peripheral blood eosinophil with 100 ug/ml of enzymatically extracted salmonid oil showed modulation of eosinophil effect functions and apoptosis comparable to APOA-IV at 3ug/ml. Vigorous processing conditions applied to the salmon oil degraded the observed eosinophil modulation. Krill oil and standard fish oil showed no to low eosinophil modulation.

Conclusions: Enzymatically extracted salmonid oil demonstrates potential therapeutic promise for the treatment of eosinophil effector malfunction-based allergic and inflammatory conditions, particularly certain types of asthma and COPD. Treatment of the oil with commercial marine oil processing conditions significantly reduces or eliminates this eosinophil effector function modulation.

Keywords: Eosinophils, asthma, salmon oil, APOA-IV, apoptosis