Identification of inflammatory genes suppressed by heat shock

To clarify inflammatory genes whose expression is suppressed at high temperatures, we performed comprehensive analysis of gene expression by using a DNA microarray. Two independent primary cultures of mouse embryo fibroblasts (MEF1 and MEF2) were treated with LPS for 4 hours, or treated with LPS for 4 hours after the pretreatment with heat shock at 42˚C for 1 hour, and we identified 100 genes that undergo more than a 3-fold increase with LPS treatment. Remarkably, 86 genes (86%) underwent less than a 2-fold increase after combined treatments with heat shock and LPS in MEF1 and MEF2 cells. Total RNAs were prepared from two primary cultures of mouse embryo fibroblasts (MEF) derived from two independent embryos at embryonic day 15.5 (ICR mice). Cells were maintained at 37˚C (Control), treated with lipopolysaccharide (LPS, E. coli 0127:B8, Sigma, 1 μg/ml) for 4 hours, or treated with LPS for 4 hours after the pretreatment of heat shock at 42˚C for 1 hour. Gene expression was analyzed by using GeneChip Mouse Genome 430 2.0 Array (Affymetrix, Santa Clara, CA).