NF-kappaB Activation In Lung Research Articles

Maturational differences in lung NF-kappaB activation and their role in tolerance to hyperoxia.

Neonatal rodents are more tolerant to hyperoxia than adults. We determined whether maturational differences in lung NF-kappaB activation could account for the differences. After hyperoxic exposure (O2 > 95%), neonatal (<12 hours old) lung NF-kappaB binding was increased and reached a maximum between 8 and 16 hours, whereas in adults no changes were observed. Additionally, neonatal NF-kappaB/luciferase transgenic mice (incorporating 2 NF-kappaB consensus sequences driving luciferase gene expression) demonstrated enhanced in vivo NF-kappaB activation after hyperoxia in real time. In the lungs of neonates, there was a propensity toward NF-kappaB activation as evidenced by increased lung I-kappaB kinase protein levels, I-kappaBalpha phosphorylation, beta-transducin repeat-containing protein levels, and total I-kappaBalpha degradation. Increased lung p-JNK immunoreactive protein was observed only in the adult lung. Inhibition of pI-kappaBalpha by BAY 11-7085 resulted in decreased Bcl-2 protein levels in neonatal lung homogenates and decreased cell viability in lung primary cultures after hyperoxic exposure. Furthermore, neonatal p50-null mutant (p50(-/-)) mice showed increased lung DNA degradation and decreased survival in hyperoxia compared with WT mice. These data demonstrate that there are maturational differences in lung NF-kappaB activation and that enhanced NF-kappaB may serve to protect the neonatal lung from acute hyperoxic injury via inhibition of apoptosis.

Hypothermia inhibits cytokine release of alveolar macrophage and activation of nuclear factor kappaB in endotoxemic lung.

We have previously reported that endotoxin-induced neutrophil infiltration of the lung is lower during hypothermia than during normothermia. Because neutrophil infiltration of the lung is considered a downstream phenomenon following an activation of tissue macrophages, we examined the effects of induced hypothermia on the proximal aspects of acute lung injury, which involves alveolar macrophages and nuclear transcription of cytokine genes. Animal study in an institutional animal laboratory. Thirty-six Sprague-Dawley rats. Rats were assigned to the following groups: normothermia (37 degrees C) with saline; hypothermia (27 degrees C) with saline; normothermia with lipopolysaccharide; hypothermia with lipopolysaccharide. After 1 h of stable temperature rats were intraperitoneally given lipopolysaccharide or an equivalent volume of normal saline. The temperature of rats was maintained within +/-1 degrees C of the target temperature for the subsequent 2 h, after which rats were subjected to lung lavage. Neutrophil count, TNF-alpha, and IL-1beta in lavage fluid were all higher with normothermia-LPS than in normothermia-saline. Neutrophil count, TNF-alpha, and IL-1beta levels of lavage fluid were lower with hypothermia-LPS than with normothermia-LPS. TNF-alpha release from cultured alveolar macrophages and NF-kappaB activity in lung tissue were both lower with hypothermia-LPS than with normothermia-LPS. I-kappaBalpha level in lung tissue was lower with normothermia-LPS than with the normothermia-saline, whereas I-kappaBalpha level in lung tissue did not differ between normothermia-saline and hypothermia-LPS. Induced hypothermia suppressed the release of inflammatory cytokine from alveolar macrophages and NF-kappaB activation in endotoxemic lung.

Selective I kappa B kinase expression in airway epithelium generates neutrophilic lung inflammation.

To determine whether NF-kappaB activation is sufficient to generate lung inflammation in vivo, we selectively expressed a constitutively active form of IkappaB kinase 1 (cIKK1) or IkappaB kinase 2 (cIKK2) in airway epithelium. After intratracheal administration of adenoviral vectors expressing cIKK1 or cIKK2 to transgenic reporter mice that express Photinus luciferase under the control of an NF-kappaB-dependent promoter, we detected significantly increased luciferase activity over time (up to 96 h). Compared with control mice treated with adenoviral vectors expressing beta-galactosidase, lung bioluminescence and tissue luciferase activity were increased in NF-kappaB reporter mice treated with adenovirus (Ad)-cIKK1 or Ad-cIKK2. NF-kappaB activation in lungs of Ad-cIKK1- and Ad-cIKK2-treated mice was confirmed by immunoblots for RelA and EMSA from lung nuclear protein extracts. Mice treated with Ad-cIKK1 or Ad-cIKK2 showed induction of mRNA expression of several chemokines and cytokines in lung tissue. In lung lavage fluid, mice treated with Ad-cIKK1 or Ad-cIKK2 showed elevated concentrations of NF-kappaB-dependent chemokines macrophage-inflammatory protein 2 and KC and increased numbers of neutrophils. Coadministration of adenoviral vectors expressing a transdominant inhibitor of NF-kappaB with Ad-cIKK1 or Ad-cIKK2 resulted in abrogated NF-kappaB activation and other parameters of lung inflammation, demonstrating that the observed inflammatory effects of Ad-cIKK1 and Ad-cIKK2 were dependent on NF-kappaB activation by these kinases. These data show that selective expression of IkappaB kinases in airway epithelium results in NF-kappaB activation, inflammatory mediator production, and neutrophilic lung inflammation. Therapies targeted to NF-kappaB in lung epithelium may be beneficial in treating inflammatory lung diseases.

Anti-Inflammatory Effects of Mutant Forms of Secretory Leukocyte Protease Inhibitor

The secretory leukocyte protease inhibitor (SLPI) is found in a variety of secreted fluids in mammals and is a known inhibitor of serine proteases. Wild-type (WT) SLPI has recently been shown to block nuclear factor kappaB (NF-kappaB) activation in rat lungs and to interfere with the ensuing inflammatory response and recruitment of neutrophils after an intrapulmonary deposition of IgG immune complexes. In this study, WT SLPI and SLPI mutants with various degrees of protease-inhibitory capacity (for trypsin, chymotrypsin, and elastase) were evaluated for their ability to suppress the lung-vascular leak, neutrophil accumulation, and NF-kappaB activation in the lung inflammatory model. The SLPI mutant with Gly(72) (replacing Leu(72) ) lost its ability to block in vivo activation of NF-kappaB, as well as its ability to suppress the lung vascular leak and neutrophil recruitment. The Phe(72) and Gly(20) mutants were as effective as the WT SLPI in suppressing NF-kappaB activation and neutrophil recruitment. The Lys(72) mutant had the most suppressive effects of the lung vascular leak and for neutrophil recruitment into the lung. The in vivo suppressive effects of SLPI mutants on lung vascular permeability, neutrophil recruitment, and NF-kappaB activation appear to be most closely related to their trypsin-inhibiting activity. These data suggest that the suppressive effects of SLPI on the intrapulmonary activation of NF-kappaB and neutrophil recruitment into the lung may be linked to their antiprotease activity, directed, perhaps, at the intracellular proteases.

Interleukin-10 inhibits pulmonary NF-kappaB activation and lung injury induced by hepatic ischemia-reperfusion.

Hepatic ischemia and reperfusion cause local and remote organ injury. This injury culminates from an integrated cascade of proinflammatory cytokines, chemokines, and adhesion molecules, many of which are regulated by the transcription factor nuclear factor-kappaB (NF-kappaB). The anti-inflammatory cytokine interleukin-10 (IL-10) has been shown to have inhibitory effects on NF-kappaB. The objective of the current study was to determine whether IL-10 could suppress pulmonary NF-kappaB activation and ensuing lung injury induced by hepatic ischemia-reperfusion. C57BL/6 mice underwent partial hepatic ischemia with or without intravenous administration of IL-10. Hepatic ischemia-reperfusion resulted in pulmonary NF-kappaB activation, increased mRNA expression of tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2), as well as increased pulmonary neutrophil accumulation and lung edema. Administration of IL-10 suppressed lung NF-kappaB activation, reduced TNF-alpha and MIP-2 mRNA expression, and decreased pulmonary neutrophil recruitment and lung injury. The data suggest that IL-10 protects against hepatic ischemia and reperfusion-induced lung injury by inhibiting lung NF-kappaB activation and the resulting pulmonary production of proinflammatory mediators.

Early activation of pulmonary nuclear factor kappaB and nuclear factor interleukin-6 in polymicrobial sepsis.

Transcription factor activation may be a pivotal step in the pathophysiology of sepsis syndrome and adult respiratory distress syndrome. This study investigated the activation of lung nuclear factor kappaB (NFkappaB) and nuclear factor interleukin-6 (NF-IL6) and how they correlate to proinflammatory cytokine expression and mortality in a murine model of cecal ligation and puncture (CLP). Polymicrobial sepsis was induced by CLP. Transcription factor activation was assessed at 0, 1, 2, 3, 4, 5, 6, 8, and 24 hours after CLP by the electrophoretic mobility-shift assay. Lung cytokine mRNA levels were established by reverse transcriptase-polymerase chain reaction. CLP induced pulmonary NFkappaB activation at 3, 4, and 8 hours (p < 0.05). Lung NFkappaB activation peaked at 3 hours (533% vs. no surgery, 2,900% vs. sham treatment) after CLP. Supershift analysis revealed a predominance of p50 subunits in the lung nuclear extracts of septic mice 3 hours after CLP, indicating the presence of p50 homodimer. In contrast, liver nuclear extracts from septic mice indicated the presence of both p65 and p50 subunits at 3 hours. Lung NF-IL6 activation (p < 0.05) was observed at 4 hours (649% vs. no surgery, 296% vs. sham treatment) and 6 hours after CLP. Lung tumor necrosis factor-alpha mRNA levels were increased (p < 0.05) at all time intervals after CLP. Lung IL-6 mRNA levels were increased at 3, 6, and 8 hours after CLP. Early activation of lung NFkappaB and NF-IL6 and lung cytokine mRNA expression correlated with mortality in polymicrobial sepsis. Although IL-6 mRNA levels correlated with NFkappaB and NF-IL6 activation, tumor necrosis factor-alpha mRNA levels did not, in that they preceded transcription factor activation. These data suggest a potential role for NFkappaB and NF-IL6 activation in the initiation and propagation of acute lung injury.