B12 Regulation of PUFA Synthesis

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Age-related cognitive decline is strongly associated with increases in neuro-inflammation and oxidative stress. Long-term dietary deficiencies in both B12 and n-3 essential fatty acids are also associated with chronic systemic inflammation as well as neuro-inflammation contributing to myelin breakdown and neurodegenerative diseases. There are intriguing links between B12 metabolism, complex fatty acid synthesis, and pro-inflammatory mechanisms. B12 might directly or indirectly regulate the elongation and desaturation of dietary PUFAs required for the conversion of dietary α-linolenic acid (ALA) to complex anti-inflammatory n-3 fatty acids such as eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), suggesting an interaction between B12 metabolism and n-3 PUFA synthesis. The major aims of this proposal are designed to investigate the benefit of combined supplementation of vitamin B12 with n-3 polyunsaturated fatty acids (PUFAs), as opposed to their individual administration, in reducing the basic pro-inflammatory mechanisms thought to underly age-related neurodegenerative disorders. Thus, the specific hypothesis to be tested is that B12 is necessary for the synthesis and efficacy of long chain n-3 fatty acids, EPA and DHA- bioactive lipids with known anti-inflammatory function. To address this hypothesis, an in vitro model using macrophage RAW264.7 cell line will be used. The first specific aim is to address whether B12 or the combined supplementation of B12 and -linolenic acid (ALA) will influence macrophage pro-inflammatory and/or anti-inflammatory responses. In the second aim, the expression of integral elongases and desaturases involved in PUFA synthesis as well as the concentration of n-3 and n-6 PUFAs will be assessed in macrophages following exposure to B12 or the combined exposure of B12 and ALA. One expected outcome would be that combined supplementation of B12 and n-3 PUFAs acts synergistically to reduce inflammation. This finding would support a mechanistic link between B12 metabolism possibly through epigenetic regulation of PUFA synthesis pathways to inflammatory mechanisms. We would expect that this interaction between B12 and PUFA synthesis is not limited to only inflammatory cells but also to other cells and tissues, such as mammary or neuronal tissue, where complex PUFA formation integral to overall human health takes place.