ABSTRACT: Dietary polyunsaturated fatty acids (PUFA) are suggested to modulate immune function, but the effects of dietary fatty acids composition on gene expression patterns in immune organs have not been fully characterized. In the current study we investigated how dietary fatty acids composition affects the total transcriptome profile, and especially, immune related genes, in bone marrow cells (BMC) and spleen (SPL). Four tissues with metabolic function, skeletal muscle (SKM), white adipose tissue (WAT), brown adipose tissue (BAT), and liver (LIV), were investigated as a comparison. Following 8 weeks on low fat diet (LFD), high fat diet (HFD) rich in saturated fatty acids (HFD-S), or HFD rich in PUFA (HFD-P), tissue transcriptomics were analyzed by microarray and metabolic health assessed by fasting blood glucose level, HOMA-IR index, oral glucose tolerance test as well as quantification of crown-like structures in WAT. Interestingly, SKM and BMC were relatively inert to the diets, whereas the two adipose tissues (WAT and BAT) were mainly affected by HFD per se (both HFD-S and HFD-P). In particular, WAT gene expression was driven closer to that of the immune organs SPL and BMC by HFDs. Remarkably, the spleen, showed a major response to HFD-P, but not to HFD-S, whereas the LIV exhibited different responses to both of the HFDs. Further, HFD-P corrected the metabolic phenotype induced by HFD-S. Hence, the quantity and composition of dietary fatty acids affected the transcriptome in a distinct manner. Especially, PUFA prompted a specific regulation of immune related genes in the spleen. Thus, PUFA can regulate immune function by influencing gene expression.
