Transcriptional inhibition of endotoxin–induced monokine synthesis following heat shock in murine peritoneal macrophages

Abstract

The role of heat shock proteins (HSP) during the inflammatory response has been controversial. The effect of heat shock (HS) on the synthesis of the monokines tumor necrosis factor (TNF) and interleukin 1 (IL-1) by endotoxin-stimulated thioglycollate-elicited peritoneal macrophages was investigated. HS was deemed to have affected macrophages if a 70 kD HSP appeared on SDS gels; identity of this protein as the highly conserved HSP70 was then confirmed by immunoprecipitation. Maximal increases in HSP70 were apparent 2-5 h after HS at 45 degrees C for 12 min. Synthesis of HSP70 was no longer detected 24 h post HS. A reciprocal relationship between HSP70 and TNF was apparent in kinetic studies. TNF was not detected in culture supernatants if macrophages were endotoxin-stimulated 2 to 6 h after HS; however, the same stimulation 24 h later induced significant TNF secretion. RNA analysis of HS and non-HS macrophage cultures demonstrated a 60-fold reduction in TNF message in the HS macrophages 1 h after endotoxin stimulation. TNF mRNA levels remained depressed at 6 h while the HSP70 message had increased 30-fold. The ability of HS macrophages to ingest antibody-coated erythrocytes was not significantly affected following heat treatment. Macrophage response to HS can be said to inhibit transcription of inducible monokines while retaining other macrophage functions.

Expression of intracellular cytokines, HSP72, and apoptosis in monocyte subsets during exertional heat stress in trained and untrained individuals

“…It is well documented that HSP induction within the cell can downregulate the inflammatory cascade by reducing TNF-␣ production to inflammatory stimuli (11,18,36,73,79). The mechanism responsible for the upregulation of HSP during inflammatory stimuli results from serine kinase and mitogen-activated protein kinase (MAPK) activation of the NF-B pathway, coupled with the production of reactive oxygen species and subsequent oxidative stress in the mitochondria.…”

The regulation of TNFα production after heat and endotoxin stimulation is dependent on Annexin-A1 and HSP70

“…To investigate if the inhibition of TNFα during stress was due to transcriptional regulation (Meng and Harken 2002;Snyder et al 1992), and if ANXA1 could modulate this, TNFα mRNA levels were assessed using realtime PCR. Treatment of cells with heat prior to LPS significantly inhibited TNFα mRNA expression in both WT and ANXA1 −/− macrophages (Fig.…”

Anti-Inflammatory Effect of Heat Shock Protein Induction Is Related to Stabilization of IκBα Through Preventing IκB Kinase Activation in Respiratory Epithelial Cells

“…TNF-␣ leads to sequential activation of the downstream NF-B-inducing kinase (NIK) and recently isolated TNF-␣-inducible I B kinase complex (IKK␣ and IKK␤, also known as IKK-1 and IKK-2, respectively) (7)(8)(9)(10)(11). Upon cell stimulation by a wide variety of stimuli, signal-responsive IKK␣ and -␤ are activated and directly phosphorylate Ser 32 and Ser 36 in the I B␣, triggering ubiquitination at Lys 21 and Lys 22 , and rapid degradation of I B␣ in 26S proteasome (4 -6). This process liberates NF-B, allowing it to translocate to the nucleus.…”

“…Because the release of pro-inflammatory mediators is associated with injury to the endothelial and epithelial cells of the lung (18,19), it can be assumed that the cytoprotective effect of HSPs may be related to the inhibition of pro-inflammatory cytokine gene expression. Actually, it is well documented that HSP induction inhibits pro-inflammatory cytokine gene expression in mononuclear cells (20,21). Recently, RANTES and inducible NO synthase gene expressions were shown to be inhibited by prior HSP induction in human and murine lung epithelial cells, respectively (22,23).…”