Phospholipid transfer protein (PLTP) plays important roles in macrophage mediated inflammation. In the current study we observed that endogenous PLTP modulated pro-inflammatory pathways in macrophage. With the presence of LPS, peritoneal derived macrophage (PDM) or bone marrow derived macrophage (BMDM) from PLTP deficient mice (PLTP-/-) expressed significantly higher level of pro-inflammatory cytokines compared with PDM or BMDM from wild-type mice (WT), respectively. LPS induced TNFα expression in PLTP-/- BMDM or PLTP knockdown RAW264.7 were suppressed by (5Z)-7-Oxozeaenol, a TAK1 inhibitor, suggesting PLTP deficiency enhanced the expression of pro-inflammatory cytokines via TAK1-NFκB pathway in macrophage. Furthermore, abundance of TLR4 on the membrane was dramatically increased in BMDM from PLTP-/- compared with WT. In addition, inhibition of ABCA1 by chemical inhibitor, glyburide, did not reduce nuclear levels of active STAT3 of BMDM, which indicated that no autocrine PLTP triggered ABCA1-JAK2-STAT3 pathway in this study. In conclusion, PLTP deficiency or low expression may enhance LPS induced pro-inflammatory cytokines expression via TLR4-TAK1-NFκB pathway in macrophage.
Purification and properties of a phospholipid transfer protein from Rhodopseudomonas sphaeroides.
