Dietary fatty acid modulation of mucosally-induced tolerogenic immune responses

Abstract

Immunological unresponsiveness or hyporesponsiveness (tolerance) can be induced by feeding protein antigens to naïve animals. Using a classical oral ovalbumin gut-induced tolerance protocol in BALB/c mice we investigated the effects of dietary n -6 and n -3 polyunsaturated fatty acids (PUFA) on high-and low-dose oral tolerance (and in non-tolerised animals, i.e. effects of antigen challenge alone) in relation to lymphoproliferative, cytokine and antibody responses. Fish oil rich in long-chain n -3 fatty acids decreased both T-helper (Th) 1- and Th2-like responses. In contrast, borage ( Borago officinalis ) oil rich in n -6 PUFA, of which γ-linolenic acid is rapidly metabolised to longer-chain n -6 PUFA, increased Th1-like responses and decreased Th2-like responses, and possibly enhanced suppressor cell or Th3-like activity. These findings are in general agreement with other studies on the effects of long chain n -3 PUFA on immune system functions, and characterise important differences between long-chain n -3 and n -6 PUFA, defining more precisely and broadly the immunological regulatory mechanisms involved. They are also discussed in relation to autoimmune disease.