title: Fish oil disrupts MHC class II lateral organization on the B-cell side of the immunological synapse independent of B-T cell adhesion.
abstract: Fish oil-enriched long chain n-3 polyunsaturated fatty acids disrupt the molecular organization of T-cell proteins in the immunological synapse. The impact of fish oil derived n-3 fatty acids on antigen-presenting cells, particularly at the animal level, is unknown. We previously demonstrated B-cells isolated from mice fed with fish oil-suppressed naïve CD4(+) T-cell activation. Therefore, here we determined the mechanistic effects of fish oil on murine B-cell major histocompatibility complex (MHC) class II molecular distribution using a combination of total internal reflection fluorescence, Förster resonance energy transfer and confocal imaging. Fish oil had no impact on presynaptic B-cell MHC II clustering. Upon conjugation with transgenic T-cells, fish-oil suppressed MHC II accumulation at the immunological synapse. As a consequence, T-cell protein kinase C theta (PKCθ) recruitment to the synapse was also diminished. The effects were independent of changes in B-T cell adhesion, as measured with microscopy, flow cytometry and static cell adhesion assays with select immune ligands. Given that fish oil can reorganize the membrane by lowering membrane cholesterol levels, we then compared the results with fish oil to cholesterol depletion using methyl-B-cyclodextrin (MβCD). MβCD treatment of B-cells suppressed MHC II and T-cell PKCθ recruitment to the immunological synapse, similar to fish oil. Overall, the results reveal commonality in the mechanism by which fish oil manipulates protein lateral organization of B-cells compared to T-cells. Furthermore, the data establish MHC class II lateral organization on the B-cell side of the immunological synapse as a novel molecular target of fish oil.
authors.affiliation: Department of Biochemistry and Molecular Biology, Brody School of Medicine and the East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834.
authors.forename: Benjamin Drew
authors.initials: BD
authors.lastname: Rockett
authors.forename: Mark
authors.initials: M
authors.lastname: Melton
authors.forename: Mitchel
authors.initials: M
authors.lastname: Harris
authors.forename: Lance C
authors.initials: LC
authors.lastname: Bridges
authors.forename: Saame Raza
authors.initials: SR
authors.lastname: Shaikh
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002784:Cholesterol / Q000172:deficiency; D005395:Fish Oils / Q000494:pharmacology*; D000949:Histocompatibility Antigens Class II / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D054992:Immunological Synapses / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D021962:Membrane Microdomains / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D011493:Protein Kinase C / Q000378:metabolism; D000074121:Protein Kinase C-theta; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D005395:Fish Oils; D000949:Histocompatibility Antigens Class II; D007527:Isoenzymes; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta
keywords: B-cells; MHC class II; Plasma membrane; n-3 polyunsaturated fatty acids