Adipose-immune cross-talks in two pig lines divergently selected for feed efficiency - Part 2

Chronic immune stimulation deteriorates adipose tissue accretion through the release of pro- and anti-inflammatory cytokines. In turn, adipokines modulate immune cell activity. It has been shown that pig genetic selection for residual feed intake (RFI), a measure of feed efficiency, influences their energy and protein metabolism, both in healthy and inflammatory states. This study aimed to determine if this selection also interfered with immuneadipose cross-talks. Male and female growing pigs of low (RFI-, n=28) or high (RFI+, n=25) RFI were reared in clean or dirty housing conditions for 6 weeks (n=26 and 27), to obtain healthy and chronically inflamed animals, respectively. Gene expression levels were determined in adipocytes and in cells of the stromal vascular fraction (SVF) of subcutaneous adipose tissue, and in whole blood cells (WB) cultured for 20 h in the absence or presence of lipopolysaccharide (LPS). Levels of adiponectin were greater (P<0.05) in adipocytes of RFI+ than RFI- pigs but did not differ with the line in SVF cells. In WB, there was a greater expression in RFI+ compared with RFI- pigs of adiponectin receptor 1 (AdipoR1, P<0.05) and Transforming Growth Factor-beta (TGF-β, P=0.05 and 0.09) in the 2 culture conditions, and of interleukin (IL)-1 (P<0.05), IL-10 (P=0.06) and Tumor Necrosis Factor-alpha (TNF-α, P<0.01) in LPS-stimulated cultures only (P<0.05). The line effect in WB was mainly due to 5 of the 12 RFI+ females who expressed dramatically greater levels of nearly all tested genes. When excluding them, the AdipoR1 gene was still more expressed in RFI+ pigs (P<0.05) whereas the expressions of AdipoR2, leptin receptor and IL-6 were not affected by the line. Unstimulated WB from dirty pigs expressed more AdipoR1 and TGF-β (P<0.05), and tended to express more Toll-like receptors 2 and 4 (P