[Analysis of the early and late gene expression of lipopolysaccharide activated macrophages by cDNA microarray]

To study the early and late changes in mRNA expression in macrophages in response to lipopolysaccharide (LPS) with a cDNA microarray approach using the Clontech Atlas microarray.

mRNA was isolated from unstimulated control and LPS stimulated murine peritoneal macrophages at 2 hours and 24 hours poststimulation, converted to (33)P radiolabeled cDNA, and hybridized to mouse array membranes.

In macrophages being stimulated for 2 hours, 69 out of 1 176 genes were found to differ by over 3-fold compared with the control. Among them 44 genes were up-regulated and 25 genes were down-regulated. In macrophages stimulated for 24 hours, 11 genes were up-regulated and 26 genes were down-regulated compared with the control. Only 8 genes were identified both at 2 hours and at 24 hours poststimulation. The expressions of many genes encoding transcription factor, cytokines, cell signaling modulators and apoptosis associated proteins were found to have changed. Some genes that were not previously linked to this model, such as bric-a-brac (BTB) and cap-n-collar(CNC) homology 1(BACH1), early growth response protein 2 (EGR2), E47 interaction protein 1 (EIP1), Ngfi-A binding protein 2 (NAB2), myeloblastosis oncogene-like protein (MYBL2), neurofibromatosis 1 (NF1), ciliarry neurotropic factor (CNTF) and semaphorin 4A (Sema4A).

This study has allowed us to identify genes that may potentially be regulated by LPS at early and late phase in macrophages. These may contribute to better understanding of the mechanism underlying LPS or bacteria induced inflammatory and immune response following infection and trauma.