Inflammatory factors derived from adipose tissue (AT) can set the stage for chronic, low-grade inflammation. This meta-inflammation can predispose the individual to further inflammatory-based disorders and diseases. Polyunsaturated fatty acids (PUFAs) are known to have immune modulating effects, with omega-6 (n-6) PUFAs typically being associated with increased production of inflammatory molecules, and n-3 PUFAs having been shown to be anti-inflammatory, in both in vivo and in vitro studies. The 3T3-L1 cell line is an embryonic mouse fibroblast line that can be differentiated into an adipocyte phenotype making it a suitable line for studies on the effects of PUFAs on inflammatory molecule production by AT. The aim of this research was to determine the effects of n-6 and n-3 PUFAs on the release of inflammatory adipokines in lipopolysaccharide (LPS)-challenged and LPS-unchallenged adipocytes. Fibroblasts were differentiated into adipocytes with the addition of 100 μM of linoleic acid (LA; n-6), arachidonic acid (ARA; n-6) or eicosapentaenoic acid (EPA; n-3) throughout the differentiation period, followed by a 6 h, 1 μg/ml LPS challenge. Cell-conditioned media was collected before and after the LPS challenge for interleukin (IL)-6 and prostaglandin E2 (PGE2) quantification via enzyme-linked immunosorbent assays. Differentiation of adipocytes with n-6 ARA caused a significant increase in PGE2 levels compared to control cells, or cells differentiated with LA or EPA, both after LPS challenge (two-way ANOVA; plt;0.0001) and before LPS challenge (two-way ANOVA; plt;0.0001). We did not observe differences in PGE2 levels between LPS-challenged and non-challenged cells differentiated with ARA (matched pairs t-test; p=0.42) and EPA (p=0.57), while control (p=0.0005) and LA-treated cells (p=0.0003) produced higher amounts of PGE2 after LPS stimulation. Interestingly, quantified levels of IL-6 across treatments did not differ before and after LPS stimulation (matched pairs t-test; p=0.75), although, as observed with PGE2, there was a significant increase in IL-6 production by ARA-differentiated cells compared to control, LPS, LA, and EPA-treated cells (two-way ANOVA; p=0.004). In conclusion, use of ARA in the differentiation process of 3T3-L1 fibroblasts into a final adipocyte phenotype increases their endogenous (non-LPS stimulated) production of IL-6 and PGE2.
