Fibroblast growth factor 18 alleviates hyperoxia-induced lung injury in mice by adjusting oxidative stress and inflammation.

OBJECTIVE: Bronchopulmonary dysplasia (BPD) is one of the most common chronic lung diseases in infants, but the ways to prevent and treat BPD are still very limited. We tried to find an effective method for treating BPD by studying the effect of fibroblast growth factor 18 (FGF18) on hyperoxia-induced lung injury in mice. MATERIALS AND METHODS: We placed newborn mice in high-oxygen environment (60-70%) and collected mouse lung tissue for histological examination at 3, 7, 14 and 21 days after birth. The correlation between FGF18 and BPD was studied by analyzing the expression of FGF18 in mouse lung tissue. In addition, we used exogenous FGF18 to stimulate primary mouse type II alveolar epithelial cells (AECs II), and detected changes in oxidative stress, inflammation and NF-κB signaling pathway activity of AECs II to analyze the effects of FGF18 on AECs II. RESULTS: From the 7th day after the birth of the mouse, the lung tissue of the hyperoxia-induced mice suffered significant lung injury relative to the control group. The expression of FGF18 in lung tissue induced by hyperoxia was lower than that in the control group. Cell viability of AECs II stimulated by exogenous FGF18 increased, and FGF18 also reduced oxidative stress and inflammation levels of AECs II and inhibited the AECs II injury caused by hyperoxia. NF-κB signaling pathway activity in hyperoxia-induced lung increased, while exogenous FGF18 could reduce the expression and phosphorylation of NF-κB p65 in AECs II. CONCLUSIONS: Hyperoxia-induced lung injury was accompanied by a decrease in FGF18. FGF18 can reduce oxidative stress and inflammation levels of AECs II by inhibiting the NF-κB signaling pathway, thereby reducing hyperoxia-induced cell injury.

Stable expression of a human HSP70 gene in a rat myogenic cell line confers protection against endotoxin.

Recent reports show that a pre-heat shock has a protective effect against endotoxin "in vivo" in rodents. It has remains unclear what actually confers the protection against endotoxin. One candidate for this protective effect is the heat shock protein of 70 kDa (HSP70). We found that a mild heat shock pretreatment is the rat myogenic cell line, H9c2(2-1), confers resistance to a subsequent exposure to endotoxin. A myogenic rat cell line stably transfected with the human inducible HSP70 exhibits an increased survival rate compared with cells stably transfected solely with the selectable neomycin marker gene or the parental cell line H9c2(2-1) when exposed to endotoxin. The mechanism of endotoxin-induced cell injury is postulated to be through the generation of nitric oxide in these myogenic cells during exposure to endotoxin. We conclude that HSP70, regardless of the particular mechanism of cytotoxicity, plays a role in protecting the cell against the deleterious effects of endotoxin.

Expression of inducible stress protein 70 in rat heart myogenic cells confers protection against simulated ischemia-induced injury.

Myocardial ischemia markedly increases the expression of several members of the stress/heat shock protein (HSP) family, especially the inducible HSP70 isoforms. Increased expression of HSP70 has been shown to exert a protective effect against a lethal heat shock. We have examined the possibility of using this resistance to a lethal heat shock as a protective effect against an ischemic-like stress in vitro using a rat embryonic heart-derived cell line H9c2 (2-1). Myogenic cells in which the heat shock proteins have been induced by a previous heat shock are found to become resistant to a subsequent simulated ischemic stress. In addition, to address the question of how much does the presence of the HSP70 contribute to this protective effect, we have generated stably transfected cell lines overexpressing the human-inducible HSP70. Embryonal rat heart-derived H9c2(2-1) cells were used for this purpose. This stably transfected cell line was found to be significantly more resistant to an ischemic-like stress than control myogenic cells only expressing the selectable marker (neomycin) or the parental cell line H9c2(2-1). This finding implicates the inducible HSP70 protein as playing a major role in protecting cardiac cells against ischemic injury.

Induction of HSP70 in cultured rat neonatal cardiomyocytes by hypoxia and metabolic stress.

BACKGROUND: A cultured neonatal rat cardiomyocyte model is used to investigate the expression of the inducible heat shock protein 70 (HSP70i) during hypoxia/reoxygenation and metabolic stress. METHODS AND RESULTS: The major HSP70i is increased in its expression at the mRNA and protein level in myocytes exposed to hypoxia/reoxygenation and metabolic stress by the addition of 2-deoxyglucose and sodium cyanide, which are inhibitors known to block ATP production. Surprisingly, the appearance of HSP70 mRNA precedes the intracellular ATP depletion caused by hypoxia, which is contrary to what we observe when the cardiomyocytes are subjected to metabolic stress. CONCLUSIONS: It has been postulated recently that the decrease in intracellular ATP content in cells under stress may be the trigger that leads to the induction of HSP70i by reducing the pool of free HSP70, thus activating the stress response. Our results indicate that although this may be the case during metabolic stress, another route of activation must be used during the early stages of hypoxia in cardiomyocytes. The induction of HSP70i also appears to precede the onset of cellular damage as measured by the release of cytoplasmic enzymes and preincorporated arachidonic acid. This indicates that cardiomyocytes are able to respond to hypoxia/reoxygenation and metabolic stress with increased HSP70i production and points to a potential protective role of heat shock proteins during ischemia/reperfusion injury.