Trans-10, cis-12 Conjugated Linoleic Acid Modulates Nuclear Factor- p65 Activity on the Production of Tumor Necrosis Factor- in Porcine Peripheral Blood Mononuclear Cells

Nuclear factor ${\kappa}B$ (NF-${\kappa}B$) is a nuclear transcription factor that modulates the expression of inflammatory cytokines such as tumor necrosis factor (TNF)-${\alpha}$. trans-10, cis-12 (t10c12)-conjugated linoleic acid (CLA) participates in the inhibition of TNF-${\alpha}$ production upon lipopolysaccharide (LPS)-stimulation. However, in our previous study, t10c12-CLA enhanced the production of TNF-${\alpha}$ by LPS-unstimulated porcine peripheral blood mononuclear cells (PBMCs) and RAW 264.7 macrophages in vitro. To resolve this apparent contradiction, we hypothesized that the effect of t10c12-CLA on TNF-${\alpha}$ production depends on NF-${\kappa}B$ activation induced by LPS stimulation. To test this hypothesis, we assessed the in vitro effect of t10c12-CLA on TNF-${\alpha}$ production and NF-${\kappa}B$ p65 activity in LPS-stimulated and LPS-unstimulated porcine PBMCs. t10c12-CLA treatment resulted in increased TNF-${\alpha}$ production by LPS-unstimulated PBMCs but decreased TNF-${\alpha}$ production by LPS-stimulated PBMCs. t10c12-CLA increased the degradation of inhibitory ${\kappa}B$ ($I{\kappa}B$)-${\alpha}$ protein and activated NF-${\kappa}B$ p65 in LPS-unstimulated PBMCs, but had the opposite effect in LPS-stimulated PBMCs. Notably, t10c12-CLA enhanced NF-${\kappa}B$ p65 binding activity in LPS-unstimulated PBMCs exposed to caffeic acid phenethyl ester (CAPE), a NF-${\kappa}B$ inhibitor. Conversely, it inhibited NF-${\kappa}B$ p65 binding activity in LPS-stimulated PBMCs exposed to CAPE. These results suggest that t10c12-CLA may have different actions under different physiological conditions, and that its effect may be associated with a change in NF-${\kappa}B$ p65 activity.

돼지 말초혈액 단핵구세포에서 trans-10, cis-12 conjugated linoleic acid의 TNF- 생산에 대한 nuclear factor- p65 활성 조절 효과

본 연구에서 돼지 PBMC에 t10c12-CLA 처리는 TNF-${\alpha}$생산을 증가시켰으나, LPS 자극 PBMC에서는 TNF-${\alpha}$생산을 감소시켰다. t10c12-CLA 처리는 PBMC의 inhibitory ${\kappa}B$ ($I{\kappa}B$)-${\alpha}$ 단백질 분해를 증가시키고 NF-${\kappa}B$ p65 활성 수준을 증가시켰다. 그러나 LPS 자극 PBMC에서는 상반되는 효과가 관찰되었다. 특히, LPS 비자극 PBMC에서 t10c12-CLA는 NF-${\kappa}B$ 저해제인 caffeic acid phenethyl ester (CAPE)를 처리한 경우 NF-${\kappa}B$ p65 활성 수준을 증가시켰으나 반대로 LPS로 자극한 CAPE 처리 PBMC에서는 NF-${\kappa}B$ p65 활성 수준을 억제시켰다. 이상의 결과는 t10c12-CLA가 돼지 PBMC에 있어 LPS 자극 유무에 따라 다른 효과를 가질 수 있으며, 이는 NF-${\kappa}B$ p65 활성도의 변화와 관련성이 있음을 보여주고 있다.