Abstract: Objective To study the effect of palmitate on toll-like receptor 4 (TLR4) expression and signaling in vascular
endothelial cells. Methods Pig iliac endothelial cells (PIECs) were incubated with palmitate. TLR4 gene expression levels were
measured by quantitative real-time PCR, and TLR4 and IκBα protein expressions by Western blotting. The expression levels of
TLR4 protein on the surface of PIECs were quantified using flow cytometry. ELISA was employed to detect tumor necrosis
factor-α (TNF-α) and interleukin-6 (IL-6) concentrations in the cell medium. Results Palmitate treatment significantly
increased TLR4 mRNA and protein expression levels in PIECs compared with those in the control cells (4.73±0.61 vs 1.25±0.90,
P<0.05; 5.79±0.05 vs 4.07±0.31, P<0.05). The expression levels of TLR4 on the cell surface significantly increased (38.070±3.907 vs
29.390±1.072, P<0.05), while IκBα protein level was significantly lowered in PIECs after palmitate treatment as compared with
those in the control cells (2.04±0.22 vs 3.98±0.18, P<0.05). Palmitate treatment significantly elevated TNF-α (2.52±0.30 vs 1.38±
0.26, P<0.05) and IL-6 (IL-6: 3.28±0.32 vs 1.44±0.28, P<0.05) concentrations in the cell culture medium. Conclusion Palmitate can
enhance TLR4 expression and signaling in porcine vascular endothelial cells.