CD8(+) T cell/adipocyte inflammatory cross talk and ensuing M1 macrophage polarization are reduced by fish-oil-derived n-3 polyunsaturated fatty acids, in part by a TNF-alpha-dependent mechanism

摘要

Obese visceral adipose tissue (AT) inflammation is driven by adipokine-mediated cross talk between CD8(+) T cells and adipocytes, a process mitigated by long-chain (LC) n-3 polyunsaturated fatty acids (PUFA) but underlying mechanisms and ensuing effects on macrophage polarization status are unknown. Using an in vitro co-culture model that recapitulates the degree of CD8(+) T cell infiltration reported in obese AT, 3T3-L1 adipocytes were co-cultured for 24 h with purified splenic CD8(+) T cells from C57B1/6 mice consuming either a 10% w/w safflower oil (control, CON) or 7% w/w safflower oil + 3% w/w fish oil (FO) diet for 4 weeks (n=8-10/diet). Co-cultured cells were in direct contact or in a contact-independent condition separated by a Transwell permeable membrane and stimulated with lipopolysaccharide (10 ng/ml) to mimic in vivo obese endotoxin levels. In contact-dependent co-cultures, FO reduced inflammatory (IL-6, TNF-alpha, IFN-gamma) and macrophage chemotactic (CCL2, CCL7, CCL3) mRNA expression and/or secreted protein, NF-kappa B p65 activation, ROS accumulation, NLRP3 inflammasome priming (Nlrp3, Il1 beta mRNA) and activation (caspase-1 activity) compared to CON (P<.05). The anti-inflammatory action of FO was reproduced by the addition of a TNF-alpha neutralizing antibody (1 mu g/ml) to CON co-cultures (CON/anti-TNF-alpha), albeit to a lesser degree. Conditioned media from FO and CON/anti-TNF-alpha co-cultures, in turn, reduced RAW 264.7 macrophage mRNA expression of M1 polarization markers (iNos, Cd11c, Ccr2) and associated inflammatory cytokines (Il6, Tnf alpha, Il1 beta) compared to CON. These data suggest that inflammatory CD8(+) T cell/adipocyte cross talk is partially attributable to TNF-alpha signaling, which can be mitigated by LC n-3 PUFA. (C) 2020 Elsevier Inc. All rights reserved.