Sandra K. Leeper-Woodford

Acute hypoxia increases alveolar macrophage tumor necrosis factor activity and alters NF-κB expression

Alterations in alveolar macrophage (AM) function during sepsis-induced hypoxia may influence tumor necrosis factor (TNF) secretion and the progression of acute lung injury. Nuclear factor (NF)-κB is thought to regulate the expression of endotoxin [lipopolysaccharide (LPS)]-induced inflammatory cytokines such as TNF, and NF-κB may also be influenced by changes in O2tension. It is thus proposed that acute changes in O2 tension surrounding AMs alter NF-κB activation and TNF secretion in these lung cells. AM-derived TNF secretion and NF-κB expression were determined after acute hypoxic exposure of isolated Sprague-Dawley rat AMs. Adhered AMs (106/ml) were incubated (37°C at 5% CO2) for 2 h with LPS ( Pseudomonas aeruginosa, 1 μg/ml) in normoxia (21% O2-5% CO2) or hypoxia (1.8% O2-5% CO2). AM-derived TNF activity was measured with a TNF-specific cytotoxicity assay. Electrophoretic mobility shift and supershift assays were used to determine NF-κB activation and to identify NF-κB isoforms in AM extracts. In addition, mRNAs for selected AM proteins were determined with RNase protection assays. LPS-exposed AMs in hypoxia had higher levels of TNF ( P < 0.05) and enhanced expression of NF-κB ( P < 0.05); the predominant isoforms were p65 and c-Rel. Increased mRNA bands for TNF-α, interleukin-1α, and interleukin-1β were also observed in the hypoxic AMs. These results suggest that acute hypoxia in the lung may induce enhanced NF-κB activation in AMs, which may result in increased production and release of inflammatory cytokines such as TNF.

Human blood vessels release tumor necrosis factor-alpha from a smooth muscle cell source

OBJECTIVES In septic shock, the principal source of increased plasma concentrations of tumor necrosis factor alpha (TNF) is considered to be the macrophage. Release from the macrophage is stimulated by bacterial lipopolysaccharide (endotoxin). We tested the hypothesis that vascular tissue also responds to endotoxin by releasing TNF. DESIGN Prospective repeated measures analysis of timed-release curves. SETTING Anesthesia research laboratory in an academic medical center. SUBJECTS With Institutional Review Board approval and patient consent, segments of internal mammary artery and saphenous vein were obtained during coronary artery bypass surgery. INTERVENTIONS None MEASUREMENTS AND MAIN RESULTS Segments of saphenous veins were incubated for 24 hrs in the presence or absence of bacterial lipopolysaccharide. At 0.5, 1, 3, 6, and 24 hrs, medium was assayed for TNF. In other experiments, smooth muscle cells were cultured from saphenous veins, incubated with our without bacterial lipopolysaccharide, and a time-course of TNF release determined. Bacterial lipopolysaccharide (20 micrograms/mL) significantly stimulated release of TNF from venous tissue in a time-dependent manner. At 0.5 hrs, TNF was undetectable in untreated tissue and was 48 +/- 8 U/g wet tissue weight in the presence of bacterial lipopolysaccharide. At 3 hrs, TNF was 43 +/- 27 U/g wet tissue weight in untreated and 388 +/- 185 U/g wet tissue weight in treated (p < .01 vs. control) tissue. Segments of internal mammary artery responded in a similar manner. In smooth muscle cells cultured from saphenous vein and internal mammary artery, bacterial lipopolysaccharide triggered the release of TNF. At 3 hrs, the release of TNF in control cells was 0.2 +/- 0.15 U/mg cell protein and 17 +/- 2 U/mg in the presence of 20 micrograms/mL of bacterial lipopolysaccharide (p < .01 vs. control). CONCLUSIONS Human blood vessels, both artery and vein, produce TNF potentially from a smooth muscle cell source in response to bacterial lipopolysaccharide.

Inhibition of release of tumor necrosis factor-alpha from human vascular tissue and smooth muscle cells by glucocorticoids

OBJECTIVES Based on our previous study that bacterial lipopolysaccharide stimulates release of tumor necrosis factor (TNF)-alpha from human vascular tissue and smooth muscle cells, we tested the hypothesis that release of TNF could be inhibited by pretreatment with glucocorticoids. DESIGN Prospective, repeated-measures analysis of concentration-response relationships. SETTING Academic anesthesiology research laboratory. SUBJECTS Segments of internal mammary artery and saphenous vein were obtained during coronary artery bypass surgery. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Confluent human smooth muscle cells, cultured from saphenous vein and internal mammary artery, were exposed to 20 micrograms/mL of bacterial lipopolysaccharide following pretreatment for 18 hrs with either 0.1, 1.0, or 10.0 microM of dexamethasone. At 1, 3, 6, 18, and 24 hrs, the culture medium was removed and analyzed for biologically active TNF-alpha using the L929 cell cytotoxicity assay. Smooth muscle cells exposed to bacterial lipopolysaccharide but not treated with dexamethasone served as controls. In control internal mammary cells, bacterial lipopolysaccharide stimulated TNF-alpha release in a time-dependent manner to a peak of 36 +/- 2.3 U/mg of cell protein at 6 hrs, compared with 0.7 +/- 0.3 U/mg of cell protein in cells not exposed to lipopolysaccharide. Dexamethasone inhibited bacterial lipopolysaccharide-stimulated release at all time points in a concentration-dependent manner. For instance, at 6 hrs, TNF-alpha was 12 +/- 2.2, 6.9 +/- 1.7, and 2.3 +/- 0.9 U/mg of cell protein for cells pretreated with 0.1, 1.0, and 10.0 microM of dexamethasone, respectively (p < .05 vs. control). In separate experiments, segments of internal mammary artery and saphenous vein were obtained from five patients who received 1 g of methylprednisolone intravenously during induction of anesthesia, and from seven patients who did not receive methylprednisolone. Bacterial lipopolysaccharide induced release of TNF-alpha from vascular tissues of untreated patients in a time-dependent manner (e.g., 733 +/- 44 U/g of tissue at 6 hrs in saphenous vein). In contrast, in patients treated with methylprednisolone, bacterial lipopolysaccharide did not stimulate release from vascular tissues incubated for up to 24 hrs. CONCLUSIONS These results indicate that human vascular tissue, particularly the smooth muscle cell, may be a source of TNF-alpha and that glucocorticoids inhibit release stimulated by bacterial lipopolysaccharide.

Family-environmental factors associated with attention deficit hyperactivity disorder in Chinese children: a case-control study.

Background Attention deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders, affecting an estimated 5 to 12% of school-aged children worldwide. From 15 to 19 million Chinese children suffer from ADHD. The aim of this study was to investigate the association between family-environmental factors and ADHD in a sample of Chinese children. Methods A pair-matched, case-control study was conducted with 161 ADHD children and 161 non-ADHD children of matching age and sex, all from 5–18 years of age. The ADHD subjects and the normal controls were all evaluated via structured diagnostic interviews. We examined the association between family-environmental factors and ADHD using the conditional multiple logistic regression with backward stepwise selection to predict the associated factors of ADHD. Results Having experienced emotional abuse and being a single child were both significant factors associated with children diagnosed with ADHD. ADHD subjects were more likely to have suffered from emotional abuse (OR = 11.09, 95% CI = 2.15–57.29, P = 0.004) and have been a single child in the family (OR = 6.32, 95% CI = 2.09–19.14, P = 0.001) when compared to normal controls. The results were not modified by other confounding factors. Conclusion Our findings provide evidence that family-environmental factors are associated with ADHD among children in China. These findings, if confirmed by future research, may help to decrease ADHD by increasing the awareness of the effects of childhood emotional abuse.

Socioeconomic, environmental and lifestyle factors associated with gestational diabetes mellitus: A matched case-control study in Beijing, China

Gestational diabetes mellitus (GDM) is a common health problem during pregnancy and its prevalence is increasing globally, especially in China. The aim of this study was to investigate socioeconomic, environmental and lifestyle factors associated with GDM in Chinese women. A matched pair case-control study was conducted with 276 GDM women and 276 non-GDM women in two hospitals in Beijing, China. Matched factors include age and pre-pregnancy body mass index (BMI). GDM subjects were defined based on the International Association of Diabetes Study Group criteria for GDM. A conditional logistic regression model with backward stepwise selection was performed to predict the odds ratio (OR) for associated factors of GDM. The analyses of data show that passive smoking at home (OR = 1.52, p = 0.027), passive smoking in the workplace (OR = 1.71, p = 0.01), and family history of diabetes in first degree relatives (OR = 3.07, p = 0.004), were significant factors associated with GDM in Chinese women. These findings may be utilized as suggestions to decrease the incidence of GDM in Chinese women by improving the national tobacco control policy and introducing public health interventions to focus on the social environment of pregnant women in China.