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Shah N.G.,University of Maryland Baltimore County | Tulapurkar M.E.,University of Maryland Baltimore County | Damarla M.,Johns Hopkins Medical Institutions | Singh I.S.,University of Maryland Baltimore County | And 6 more authors.
International Journal of Hyperthermia | Year: 2012

Fever commonly occurs in acute lung injury (ALI) and ALI occurs in 25 of victims of heat stroke. We have shown in mouse models of ALI that exposure to febrile-range hyperthermia (FRH), 39.5°C, increases non-cardiogenic pulmonary oedema. In this study we studied the direct effects of FRH on endothelial barrier integrity using human microvascular endothelial cells (HMVEC-Ls). We analysed the effect of exposure to culture temperatures between 38.5° and 41°C with and without tumour necrosis factor- (TNF-) up to 250U/mL for 624h. We found that exposure to 2.5250U/mL TNF- increased HMVEC-L permeability by 4.115.8-fold at 37°C. Exposure to 39.5°C alone caused variable, modest, lot-specific increases in HMVEC-L permeability, however raising culture temperature to 39.5°C in the presence of TNF- increased permeability an additional 1.64.5-fold compared with cells incubated with the same TNF- concentration at 37°C. Permeability occurred without measurable cytotoxicity and was reversible upon removal of TNF- and reduction in temperature to 37°C. Exposure to 39.5°C or TNF- each stimulated rapid activation of p38 and ERK but the effects were not additive. Treatment with inhibitors of ERK (U0126) or p38 (SB203580) each reduced TNF - induced permeability in 39.5°C monolayers to levels in 37°C cells, but did not alter TNF - induced permeability in the 37°C cells. These results demonstrate that FRH directly increases paracellular pathway opening through a process that requires ERK and p38 MAPKs. A better understanding of this mechanism may provide new understanding about how fever may contribute to the pathogenesis of ALI and provide new therapeutic targets to improve clinical outcomes. © 2012 Informa UK Ltd All rights reserved.

Shah N.G.,University of Maryland Baltimore County | Tulapurkar M.E.,University of Maryland Baltimore County | Singh I.S.,University of Maryland Baltimore County | Singh I.S.,Research Services of the Baltimore Medical Center | And 5 more authors.
Prostaglandins and Other Lipid Mediators | Year: 2010

The heat shock (HS) response is an important cytoprotective response comprising the expression of heat shock proteins (HSPs) and orchestrated by the heat/stress-induced transcription factor, heat shock factor-1 (HSF-1). Previous studies suggest that the activation threshold and magnitude of the HS response may be modified by treatment with arachidonic acid (AA). We analyzed the effect of exogenous AA and its metabolites, PGE2, LTD4, and 15-HETE on HSF-1-dependent gene expression in A549 human respiratory epithelial-like cells. When added at 1μM, PGE2 much more than LTD4, but not 15-HETE increased activity of a synthetic HSF-1-dependent reporter after HS exposure (42°C for 2h), but had no effect in the absence of HS. Exposing A549 cells to HS stimulated the release of PGE2 and treatment with the cyclooxygenase inhibitor, ibuprofen, reduced HS-induced HSF-1-dependent transcription. PGE2 increased HS-induced HSP72 mRNA and protein expression but EMSA and Western blot analysis failed to show an effect on HSF-1 DNA binding activity or post-translational modification. In summary, we showed that HS stimulates the generation of PGE2, which augments the generation of HSPs. The clinical consequences of this pathway have yet to be determined. © 2010 Elsevier Inc.

Maity T.K.,University of Maryland Baltimore County | Henry M.M.,University of Maryland Baltimore County | Tulapurkar M.E.,University of Maryland Baltimore County | Shah N.G.,University of Maryland Baltimore County | And 4 more authors.
Cytokine | Year: 2011

The heat shock (HS) response, a phylogenetically conserved ubiquitous response to stress, is generally characterized by the induced expression of heat shock protein (HSP) genes. Our earlier studies showed that the stress-activated transcription factor, heat shock factor-1 (HSF1), activated at febrile range or HS temperatures also modified expression of non-HSP genes including cytokine and chemokine genes. We also showed by in silico analysis that 28 among 29 human and mouse CXC chemokine genes had multiple putative heat shock response elements (HSEs) present in their gene promoters. To further determine whether these potential HSEs were functional and bound HSF1, we analyzed the recruitment of HSF1 to promoters of 5 human CXC chemokine genes (CXCL-1, 2, 3, 5 and 8) by chromatin immunoprecipitation (ChIP) assay and analyzed the effect of HS exposure on tumor necrosis factor-α (TNFα)-induced expression of these genes in human lung epithelial-like A549 cells. HSF1 ChIP analysis showed that HSF1 was recruited to all but one of these CXC chemokine genes (CXCL-3) and HS caused a significant increase in recruitment of HSF1 to one or multiple HSEs present in the promoters of CXCL-1, 2, 5 and 8 genes. However, the effect of HS exposure on expression of these genes showed a variable gene-specific effect. For example, CXCL8 expression was markedly enhanced (p<0.05) whereas CXCL5 expression was significantly repressed (p<0.05) in cells exposed to HS coincident with TNFα stimulation. In contrast, expression of CXCL1 and CXCL2, despite HSF1 recruitment to their promoters, was not affected by HS exposure. Our results indicate that some, if not all, putative HSEs present in the CXC chemokine gene promoters are functional and recruit HSF1 in vivo but the effects on gene expression are variable and gene specific. We speculate, the physical proximity and interactions of other transcription factors and co-regulators with HSF1 could be critical to determining the effects of HS on the expression of these genes. © 2010 Elsevier Ltd.

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