CD14- and Toll-Like Receptor 4-Dependent Regulation of c-Fos, c-Jun and c-Jun Phosphorylation in the Adrenal Gland afterBurn Injury

Abstract

Objectives: Although the pathophysiology of the adrenocortical response after injury has been described, alterations in the molecular profile (e.g. transcription factors) of the adrenal gland itself are not well understood. The regulation of c-Fos, c-Jun, and c-Jun phosphorylation in the adrenal gland after burn injury was investigated in this study. In addition, since burn injury is often associated with lipopolysaccharide (LPS)-mediated sepsis, we examined the involvement of the LPS signaling pathway in the regulation of these transcription factors utilizing CD14 knockout and C3H/HeJ (encoding defective toll-like receptor 4) mice. Methods: Adrenal glands harvested after an 18% total body surface area burn were subjected to RT-PCR and Western blot analyses of c-Jun and c-Fos. Results: There was a rapid induction of c-Jun and c-Fos expression (mRNA and protein), and c-Jun serine phosphorylation. The induction of c-Jun and its phosphorylation after injury was greater in CD14 knockout and C3H/HeJ mice compared to their respective controls. A similar pattern was observed in the c-Fos regulation. Conclusions: These data suggest that c-Fos and c-Jun are activated in the adrenal gland in response to burn injury. In addition, an LPS-mediated signaling pathway may influence the regulation of these transcription factors after injury.

Burn serum causes a CD14-dependent mitochondrial damage in primary cardiomyocytes

“…Although CD14 has been recognized as an important inflammation mediator in burn-associated pathological responses in multiple organs including the liver (11,13,14), lung (14), skin (43), and adrenal gland (12), its role in myocardium and myocardial mitochondrial function has not been elucidated. A recent study from our laboratory suggests that burn injury significantly elevated CD14 expression in the heart tissue and in cardiomyocytes (5).…”

“…CD14, a member of the toll-like receptor 4 (TLR4) signalosome, is involved in the regulation of postburn pathogenic responses in distant organs such as the liver (11,13,14), lung (14), skin (43), and adrenal gland (12). Consistently, recent clinical research has correlated genetic variations within the TLR4 gene with the risk of post-trauma organ failure (4,41).…”

Second Hit Post Burn Increased Proximal Gut Mucosa Epithelial Cells Damage

“…One in vivo study showed that lymphocyte apoptosis is increased in the gut local immune environment, with gut epithelial atrophy in response to severe burn, which displays the importance of immune responses related to a severe burn. Recently, the Toll-like receptor pathway was found to regulate transcription factors after a severe burn or endotoxemia (23). Toll-like receptor 4/ CD14 serves as a specific receptor for LPS and plays a role at the immediate or innate immune response against diverse microbial pathogens (24).…”

Imaging C-Fos Gene Expression in Burns Using Lipid Coated Spion Nanoparticles

“…Furthermore, we produced a superior lipid coated contrast agent, which was self-targeted and accumulated at the burn site and that was administered systemically as opposed to locally. Previous methodologies employed ex vivo observation of the gene expression by western blotting [6] which allowed only indirect assessment of gene activation. The most recent improvement include in situ hybriditzation using bispyrene-modified 2′-O-methyl RNA probes which is useful in the evaluation of ex vivo samples and cultured cells.…”

“…Since c-Fos activation is implicated in numerous crucial intracellular functions such as cell cycle activity and apoptosis, regulation of signal transduction pathways, cellular trafficking, cell proliferation and differentiation, cell survival, and protein folding and proessing and its detection is important in establishing the pathology and path-physiology of burn and the regenerative processes [3]. Detection of c-Fos up to now is done using ex vivo assays following the induction of burn [5], using methodologies such as RT-PCR, Western blot [6] or in situ hybridization [1]. …”