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. 2020 Jul 29;9(8):1799. doi: 10.3390/cells9081799

Figure 2.

Figure 2

MIP-1α co-induction by palmitate and TNF-α implicates the TLR4-mediated signaling. TLR4 signaling activity in THP-1 cells was intercepted by multiple approaches such as genetic ablation with TLR4-specific siRNA, receptor blocking with TLR4 neutralizing antibody, and chemical inhibition with TLR4 inhibitor OxPAPC as described in the Materials and Methods section. The representative data (mean ± SEM) from three independent determinations with similar results show that co-induction of MIP-1α by palmitate and TNF-α was suppressed at the levels of (A) MIP-1α transcripts (P = 0.02) and (B) MIP-1α secreted protein (P = 0.0002) in THP-1 monocytic cells transfected with TLR4 siRNA as compared to controls transfected with scrambled siRNA. Similarly, MIP-1α expression co-induced by palmitate and TNF-α was reduced at the levels of (C) MIP-1α mRNA (P = 0.002) and (D) MIP-1α secreted protein (P = 0.01) in THP-1 cells that were treated with anti-TLR4 neutralizing antibody compared to controls treated with isotype-matched IgA2 antibody. In line with these results, treatment of THP-1 monocytic cells with OxPAPC inhibitor also reduced the expression of (E) MIP-1α transcripts (P = 0.0007) and (F) MIP-1α secreted protein (P = 0.003) compared to controls treated with the vehicle only before co-stimulation with palmitate and TNF-α. * P < 0.05, ** P < 0.01, *** P < 0.001.