DIETARY-LIPID SOURCE ALTERS MURINE MACROPHAGE VASCULAR SMOOTH-MUSCLE CELL-INTERACTIONS IN-VITRO/

This study was conducted to compare the impact of dietary lipids on th e ability of macrophages to modulate vascular smooth muscle cell (SMC) DNA synthesis in vitro. C57BL/6 female mice were fed six different di ets (6 mice/diet) containing 10% fat from corn oil (CO), borage oil (B O), primrose oil (PO), fish-corn oil mix (FC, 9:1, w/w), fish-borage o il mix (FB, 1:3, w/w), or fish-primrose oil mix (FP, 1:3, w/w) for 2 w k. Peritoneal macrophages were isolated from these mice, stimulated wi th zymosan or vehicle, and subsequently co-cultured with naive mouse a ortic SMC in the presence of H-3-thymidine to measure SMC DNA synthesi s. In this co-culture system, macrophages were seeded on 25-mm culture inserts (upper chamber) and SMC were seeded on 35-mm culture dishes ( lower chamber). The two cell types were separated by a semi-permeable membrane with a 30-kD cut-off. When quiescent SMC were co-cultured wit h macrophages, only the PO and FP diet groups had significantly (P < 0 .05) lower SMC DNA synthesis compared with the control CO group whose diet contained no gamma-linolenic acid (GLA) or (n-3) polyunsaturated fatty acids (PUFA). In contrast, when cycling SMC were co-cultured wit h diet-modulated macrophages, all dietary groups except for those fed FC had significantly lower (P < 0.05) SMC DNA synthesis relative to th e CO group. Although the level of GLA in PO and BO diets was different (11.5 and 22.3 g/100 g fatty acids, respectively), these treatments e xerted comparable inhibitory effects on SMC DNA synthesis. The FP trea tment consistently exhibited the lowest SMC DNA synthetic profile amon g the six dietary groups irrespective of SMC growth conditions. These data suggest that BO and PO alone or in combination with fish oil infl uence macrophage/smooth muscle cell interactions in a manner consisten t with favorable modulation of the atherogenic process.