Málstofa Lífvísindaseturs verður haldin fimmtudaginn 25. september kl. 12:00-12:40 í stofu 343 í Læknagarði.

Dr. Jenifer Fenton, dósent við matvæla- og næringafræðideild Michigan State University, mun halda erindi um Áhrif fiskolíu á B eitilfrumur og innlimun ómega-3 fjölómettaðra fitusýra í frumuhimnur músa með garnabólgu.

Ágrip: Ómega-3 fjölómettaðar fitusýrur (FÓFS), sérstaklega eikósapentaenóik sýra (EPA) og dókósahexaenóik sýra (DHA), hafa áhrif á ónæmissvör og eru taldar vernda gegn langvarandi bólgu. Hins vegar benda niðurstöður dýratilrauna einnig til þess að fiskolía geti dempað ónæmissvör með alvarlegum afleiðingum í sýkingum. Í flestum rannsóknum á áhrifum fiskolíu á ónæmiskerfið hefur verið lögð áhersla á T eitilfrumur, mónócýta og angafrumur en fáar rannsóknir hafa beinst að áhrifum fiskolíu á B eitilfrumur. Fyrri niðurstöður sýndu að SMAD3-/- músum sem fengu DHA-ríka fiskolíu reiddi verr af eftir Helicobacter hepaticus miðlaða garnabólgu, hugsanlega vegna áhrifa fiskolíunnar á starfsemi B frumna. Til að kanna þetta var SMAD3-/- músum gefið viðmiðunarfæði eða fiskolíu fæði með mismunandi samsetningu af ómega-3 FÓFS. Niðurstöðurnar sýndu að áhrif fiskolíu á starfsemi B frumnanna var háð ómega-3 FÓFS samsetningu fiskolíunnar. Einnig sýndu þær að samsetning ómega-3 FÓFS í himnu B frumna tengdist samsetningu þeirra í rauðum blóðkornum. Niðurstöðurnar staðfesta að ómega-3 FÓFS geta gegnt hlutverki við ónæmisstýringu B frumna. Í ljósi vaxandi notkunar á fiskolíu sem fæðubótarefnis, m.a. í Bandaríkjunum, er mikilvægt að auka skilning á áhrifum hennar á ónæmissvör. 

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This week BMC seminar will be given by Dr. Jenifer Fenton, Associate Professor, Department of Food Science and Human Nutrition, Michigan State University, Columbia, USA.

Title: B Cell Immunomodulation and Fatty Acid Incorporation of Dietary Fish Oils in Colitis-prone Mice

Thursday 25th September, 12:00-12:40 in room 343 at Læknagarður

Short Biosketch: Dr. Fenton is an Associate Professor in the Department of Food Science and Human Nutrition at Michigan State University. She completed a PhD in Nutrition at Michigan State University. She then moved on and became a Fellow at the National Cancer Institute for 5 years. During that time, she completed a Master’s in Public Health at the University of Michigan in Epidemiology. She conducted research in the laboratory of Stephen Hursting on the effects of energy balance on cancer. She has continued that work along with other research areas. She has significant expertise in nutrition/dietary compounds and the effect on health. She has experience and training in basic science, animal modeling of human disease and human subject research related to nutrition and disease prevention. She has received funding from the NIH for research related to nutrition and inflammation in all three types of research. In addition, Dr. Fenton’s laboratory also studies how diet and energy balance alter the immune response to pathogenic bacteria in the GI tract and disease outcomes. Dr. Fenton has trained undergraduate, graduate and postdoctoral students. She has served as graduate affairs committee chair for the department for three years and is the past chair of the Diet and Cancer Research Section of the American Society for Nutrition. Currently, she is the undergraduate curriculum coordinator for the Nutritional Sciences major.

Abstract: Over 30 million people report the use of fish oil supplements in the United States, where dietary fish intake remains low. Prescription fish oil is approved to treat high triglycerides; however, there is increasing evidence that consumption of fish oil may be beneficial for other diseases, such as cardiovascular and autoimmune diseases. It is generally accepted that these potential health benefits stem from omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs) found in fish oil. n-3 LCPUFAs, notably eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), alter immune function and are proposed to be beneficial against chronic inflammatory conditions; however, observations across multiple models of pathogen-exposed animals suggest deleterious immunosuppression due to fish oil. The majority of research on fish oil and the immune system has focused primarily on T cells, monocytes, and dendritic cells of the immune system. However, the extent to which fish oil alters the function of B cells, a vital component of humoral immunity, remains relatively uninvestigated. Previous research demonstrated that DHA-enriched fish oil (DFO) exacerbated Helicobacter hepaticus-induced colitis in SMAD3-/- mice. Given the aberrant response to H. hepaticus in DFO-fed SMAD3-/- mice, it was hypothesized that fish oils alter humoral immunity, specifically B cell function. To test this hypothesis, SMAD3-/- mice were fed either control or various dietary fish oils, including non-enriched (e.g., menhaden oil [MO]) and enriched (e.g., EPA- or DHA-enriched) fish oils, and then assessed for B cell development and function. The results indicate that the n-3 LCPUFA composition of fish oil mediates observed B cell immunological outcomes. All dietary treatments were found to markedly increase n-3 LCPUFAs and decrease n-6 LCPUFAs of red blood cell (RBC) and B cell phospholipid fatty acid profiles. B cells from SMAD3-/- mice fed MO and DFO dietary treatments share a number of mechanistic and immunological outcomes, such as decreased clustering of membrane microdomains concomitant with increased cytokine production in response to ex vivo stimulation. In contrast, EPA-enriched fish oil (EFO) had increased microdomain clustering, decreased expression of B cell surface markers, and ex vivo function. The n-3 LCPUFA composition of B cells was tightly correlated to RBCs phospholipid fatty acids, a common biomarker of n-3 LCPUFA exposure; however, it is unclear how levels of n-3 LCPUFAs in the blood relate to levels of n-3 LCPUFAs in other tissues, which may be more prognostic of health benefit at the tissue-level. This prompted the characterization of the phospholipid fatty acid profile of blood and gastrointestinal (GI) tissues, of colitis-prone, SMAD3-/- fed increasing amounts of EPA+DHA. Levels of EPA+DHA were chosen to mirror recommended intakes of n-3 LCPUFAs in humans. RBCs were highly correlated to the n-3 and n-6 LCPUFAs of all other GI; however, the absolute levels of n-3 and n-6 LCPUFAs varied considerably between blood and tissue. These findings confirm a novel role for B cell immunomodulation by dietary fish oil and provide further evidence that RBCs serve as an adequate, surrogate biomarker for n-3 LCPUFA incorporation. As an increasing popular dietary supplement, understanding the mechanistic and functional outcomes of fish oil consumption provide a foundation for research of more targeted fish oil therapeutics