LPS receptor CD14 participates in release of TNF-α in RAW 264.7 and peritoneal cells but not in Kupffer cells

Abstract

Lipopolysaccharide (LPS) is a bacterial polymer that stimulates macrophages to release tumor necrosis factor-α (TNF-α). In macrophages (RAW 264.7 and peritoneal cells), LPS binds to the CD14 surface receptor as the first step toward signaling. Liver macrophages, Kupffer cells, are the most numerous fixed-tissue macrophage in the body. The presence of CD14 on Kupffer cells and its role in LPS stimulation of TNF-α were examined. TNF-α release by Kupffer cells after LPS stimulation was the same in the presence and absence of serum. RAW 264.7 and peritoneal cells, which utilize the CD14 receptor, released significantly less TNF-α after LPS stimulation in the absence of serum because of the absence of LPS-binding protein. Phosphatidylinositol-phospholipase C treatment, which cleaves the CD14 receptor, decreased LPS-stimulated TNF-α release by RAW 264.7 cells but not by Kupffer cells. Deacylated LPS (dLPS) competes with LPS at the CD14 receptor when incubated in a ratio of 100:1 (dLPS/LPS). Such competition blocked LPS-stimulated TNF-α release from RAW 264.7 cells but not from Kupffer cells. Western and fluorescence-activated cell sorter analysis directly demonstrated the presence of CD14 on RAW 264.7 cells and murine peritoneal cells but showed only minimal amounts of CD14 in murine Kupffer cells. LPS stimulation did not increase the amount of CD14 detectable on mouse Kupffer cells. CD14 expression is very low in Kupffer cells, and LPS-stimulated TNF-α release is independent of CD14 in these cells.

Suppression of lipopolysaccharide-induced nitric oxide synthase expression by platelet-activating factor receptor antagonists in the rat liver and cultured rat kupffer cells

“…This pattern of response of KCs to LPS is quite unlike that observed in murine macrophages, which display a classical CD14-dependent mechanism for LPSinduced iNOS mRNA expression. 35,36 It is of consequence to note here that the concentrations of LPS required to cause signaling in macrophages are much higher than those used in the present study. Furthermore, it has been observed that in KCs, low concentrations of LPS can cause maximal signaling (in either the presence or absence of serum), whereas other macrophages by comparison respond to much higher concentrations of LPS only in the presence of serum.…”

“…Furthermore, it has been observed that in KCs, low concentrations of LPS can cause maximal signaling (in either the presence or absence of serum), whereas other macrophages by comparison respond to much higher concentrations of LPS only in the presence of serum. 35,36,39 Thus, an alternative receptor-mediated signal transduction pathway other than CD14 has been proposed to exist for LPS in KCs. 34,36 It has been previously reported that transfection of the PAF receptor into Xenopus oocytes and Chinese hamster ovary (CHO) cells enables these CD14-deficient cells to respond to LPS by causing only an elevation in intracellular calcium levels.…”

Effect of silica and gold nanoparticles on macrophage proliferation, activation markers, cytokine production, and phagocytosis in vitro

“…It is well known that LPS is a potent inducer of pro-inflammatory cytokines 31 and, therefore, it has been extensively used as a positive control in in vitro studies involving macrophages. [32][33][34] In the current study, therefore, LPS-treated cells were used as a positive control.…”

Ultrastructural Changes and Cd14 Expression in the Liver in the Short Bowel Syndrome

“…The Kupffer cells have relatively less CD14 expression base when compared to peripheral blood monocytes (18)(19)(20). CD14 expression of Kupffer cells is upregulated by multistimulation of polysaccharide by means of an increase in functional receptor number (21)(22)(23). Upregulation of CD14 expression in liver cells occurs in many conditions of liver injury such as alcoholic and cholestatic liver injury (24).…”