title: Short-term consumption of n-3 PUFAs increases murine IL-5 levels, but IL-5 is not the mechanistic link between n-3 fatty acids and changes in B-cell populations.
abstract: N-3 polyunsaturated fatty acids (PUFAs) exert immunomodulatory effects on B cells. We previously demonstrated that n-3 PUFAs enhanced the relative percentage and/or frequency of select B2 cell subsets. The objectives here were to determine if n-3 PUFAs (a) could boost cytokines that target B-cell frequency, (b) enhance the frequency of the B1 population and (c) to identify the mechanism by which n-3 PUFAs modify the proportion of B cells. Administration of n-3 PUFAs as fish oil to C57BL/6 mice enhanced secretion of the Th2 cytokine IL-5 but not IL-9 or IL-13. N-3 PUFAs had no influence on the percentage or frequency of peritoneal B1 or B2 cells. Subsequent experiments with IL-5(-/-) knockout mice showed n-3 PUFAs decreased the percentage of bone marrow B220(lo)IgM(hi) cells and increased the proportion and number of splenic IgM(+)IgD(lo)CD21(lo) cells compared to the control. These results, when compared with our previous findings with wild-type mice, suggested IL-5 had no role in mediating the effect of n-3 PUFAs on B-cell populations. To confirm this conclusion, we assayed IL-5 secretion in a diet-induced obesity model in which n-3 PUFAs enhanced the frequency of select B-cell subsets. N-3 PUFA supplementation as ethyl esters to obesogenic diets did not alter circulating IL-5 levels. Altogether, the data establish that n-3 PUFAs as fish oil can increase circulating IL-5 in lean mice, which has implications for several disease end points, but this increase in IL-5 is not the mechanistic link between n-3 PUFAs and changes in B-cell populations.
authors.affiliation: Department of Biochemistry & Molecular Biology, East Carolina University; East Carolina Diabetes & Obesity Institute, East Carolina University.
authors.forename: Heather
authors.initials: H
authors.lastname: Teague
authors.affiliation: Department of Biochemistry & Molecular Biology, East Carolina University; East Carolina Diabetes & Obesity Institute, East Carolina University.
authors.forename: Mitchel
authors.initials: M
authors.lastname: Harris
authors.affiliation: Department of Biochemistry & Molecular Biology, East Carolina University; East Carolina Diabetes & Obesity Institute, East Carolina University.
authors.forename: Jarrett
authors.initials: J
authors.lastname: Whelan
authors.affiliation: Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI.
authors.forename: Sarah S
authors.initials: SS
authors.lastname: Comstock
authors.affiliation: Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI; College of Osteopathic Medicine, Michigan State University, East Lansing, MI.
authors.forename: Jenifer I
authors.initials: JI
authors.lastname: Fenton
authors.affiliation: Department of Biochemistry & Molecular Biology, East Carolina University; East Carolina Diabetes & Obesity Institute, East Carolina University; Department of Microbiology & Immunology, East Carolina University. Electronic address: shaikhsa@ecu.edu.
authors.forename: Saame Raza
authors.initials: SR
authors.lastname: Shaikh
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects*; D004041:Dietary Fats / Q000008:administration & dosage*; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D015848:Interleukin-5 / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D004041:Dietary Fats; D015525:Fatty Acids, Omega-3; D015848:Interleukin-5
keywords: B cells; DHA; EPA; IL-5; n-3 PUFAs