Lipopolysaccharide induces prostaglandin H synthase-2 protein and mRNA in human alveolar macrophages and blood monocytes.

Abstract

We and others have previously demonstrated that human alveolar macrophages produce more PGE2 in response to lipopolysaccharide (LPS) than do blood monocytes. We hypothesized that this observation was due to a greater increase in prostaglandin H synthase-2 (PGHS-2) enzyme mass in the macrophage compared to the monocyte. To evaluate this hypothesis, alveolar macrophages and blood monocytes were obtained from healthy nonsmoking volunteers. The cells were cultured in the presence of 0 to 10 ,g/ml LPS. LPS induced the synthesis of large amounts of a new 75-kD protein in human alveolar macrophages, and a lesser amount in monocytes. Synthesis of this protein required more than 6 h and peaked in 24 to 48 h; the protein reacted with an anti-PGHS-2 antibody prepared against mouse PGHS-2. Associated with synthesis of the protein was a marked increase in LPS-stimulated and arachidonic acid-stimulated synthesis of PGE2 by alveolar macrophages compared to monocytes. Cells not exposed to LPS contained only PGHS-1 and synthesized very little PGE2 during culture or in response to exogenous arachidonic acid. An LPSinduced mRNA, which hybridized to a human cDNA probe for PGHS-2 mRNA, was produced in parallel with production of this new protein and was produced in much greater amounts by alveolar macrophages compared to blood monocytes. This mRNA was not detectable in cells not exposed to LPS. In contrast, both types of cells contain mRNA, which hybridizes to a cDNA probe for PGHS-1. This mRNA did not increase in response to LPS. LPS also had no effect on PGHS-1 protein.These data demonstrate that PGE2 synthesis in human alveolar macrophages and blood monocytes correlates to the mass of PGHS-2 in the cell. We conclude that the greater ability of the macrophage to synthesize PGE2 in response to LPS is due to greater synthesis of PGHS-2 by the macrophage. (J. Clin. Invest. 1994. 93:391-396.)

Modulation of phagocytosis by anisoosmolarity and betaine in rat liver macrophages (Kupffer cells) and RAW 264.7 mouse macrophages

“…Upon stimulation with endotoxin these cells produce a variety of cytokines, lipid mediators and radicals. Recent studies have indicated that endotoxin enhances the expression of inducible cyclooxygenase-2 (Cox-2) [2][3][4][5][6], which results in the increased formation of prostanoids by Kupffer cells and other macrophages [3,[7][8][9]. Interestingly, lipopolysaccharide (LPS)-induced prostaglandin E2, D2 and thromboxane B2 formation and Cox-2 expression are stimulated up to 10-fold when ambient osmolarity increases from 300 to 350 mosmol/1 [3].…”

Tyrosine Phosphorylation of I-κB Kinase α/β by Protein Kinase C-Dependent c-Src Activation Is Involved in TNF-α-Induced Cyclooxygenase-2 Expression

“…The induction of COX-2 expression requires de novo mRNA and protein synthesis (21), indicating regulation at the transcriptional level. The promoter region of human COX-2 gene has been cloned and sequenced, and shown to contain putative recognition sequences for a variety of transcriptional factors, including NF-B, NF-IL-6, and cAMP response element (22).…”

What is the cellular source of prostaglandins in the brain in response to systemic inflammation? Facts and controversies

“…In contrast, the COX-2 isoform is undetectable in most tissues under basal conditions, but marked transcriptional activation can be observed in macrophages and other cell types by the endotoxin lipopolysaccharide (LPS) and proinflammatory cytokines. [1][2][3] Interestingly, systemic inflammatory insults cause a robust transcriptional activation of COX-2 along cells of the mouse and rat microvasculature, although the intensity of the signal and the pattern of expression depend on the challenge and the dose of the inflammatory agents. [4][5][6][7][8] Intravenous (i.v.)…”