Publications

The mechanism by which chronic stress affects the course of inflammatory diseases is still not well understood. We have evaluated the effect of two types of nonhabituating stress on a major component of the inflammatory response, synovial plasma extravasation, induced by perfusion of the potent inflammatory mediator, bradykinin and evaluated the underlying neuroendocrine mechanism in the rat. Chronic intermittent noise or ether stress induced profound inhibition of bradykinin-induced plasma extravasation, which is associated with increased adjuvant-arthritis severity. This inhibition, however, took 24 h to fully develop after the last exposure to stress and persisted for at least 48 h. The inhibition could be reversed by an additional exposure to the stressor, just prior to measuring the inflammatory response, suggesting that the delay is due to stress-induced release of a factor that acutely masks the inhibition of the inflammatory response. This novel, unexpected feature of the effect of nonhabituating stress on inflammation may help explain variability in effects of stress in patients with inflammatory disease. The effect of nonhabituating stress on inflammation was dependent on the sympathoadrenal axis with no detectable contribution by the hypothalamic-pituitary-adrenal axis.

The nef gene products encoded by human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus type 1 (SIV-1) increase viral loads in infected hosts and accelerate clinical progression to AIDS. Nef exhibits a spectrum of biological activities, including the ability to downregulate surface expression of CD4 and major histocompatibility complex (MHC) class I antigens, to alter the state of T-cell activation, and to enhance the infectivity of viral particles. To determine which of these in vitro functions most closely correlates with the pathogenic effects of Nef in vivo, we constructed recombinant HIV-1 NL4-3 viruses carrying mutations within the nef gene that selectively impair these functions. These mutant viruses were evaluated for pathogenic potential in severe combined immunodeficiency (SCID) mice implanted with human fetal thymus and liver (SCID-hu Thy/Liv mice), in which virus-mediated depletion of thymocytes is known to be Nef dependent. Disruption of the polyproline type II helix (Pxx)4 within Nef (required for binding of Hck and p21-activated kinase-like kinases, downregulation of MHC class I, and enhancement of HIV-1 infectivity in vitro but dispensable for CD4 downregulation) did not impair thymocyte depletion in virus-infected Thy/Liv human thymus implants. Conversely, three separate point mutations in Nef that compromised its ability to downregulate CD4 attenuated thymocyte depletion while not diminishing viral replication. These findings indicate that the functional ability of Nef to downregulate CD4 and not MHC class I downregulation, Hck or PAK binding, or (Pxx)4-associated enhancement of infectivity most closely correlates with Nef-mediated enhancement of HIV-1 pathogenicity in vivo. Nef-mediated CD4 downregulation merits consideration as a new target for the development of small-molecule inhibitors.

We review two new HIV counseling and testing guidelines by the U.S. Centers for Disease Control and Prevention. The guidelines, which address the general population and pregnant women, reflect an important shift in the goals and methods of counseling and testing that has widespread implications. The guidelines' defining characteristic is the greater emphasis on increasing the numbers of people knowing their HIV status while maintaining the historical focus on extensive pretest counseling and consent procedures. We discuss the policy and practice implications by evaluating five factors: 1) Will the guidelines be adopted? 2) Will at-risk and infected individuals be identified for counseling and testing? 3) Will health care providers offer counseling and testing and patients accept counseling and testing, obtain their test results, seek treatment, and change risky behaviors? 4) Will the guidelines be relatively cost-effective? 5) Will the guidelines be compatible with ethical standards?

Tidal volume reduction during mechanical ventilation reduces mortality in patients with acute lung injury and the acute respiratory distress syndrome. To determine the mechanisms underlying the protective effect of low tidal volume ventilation, we studied the time course and reversibility of ventilator-induced changes in permeability and distal air space edema fluid clearance in a rat model of ventilator-induced lung injury. Anesthetized rats were ventilated with a high tidal volume (30 ml/kg) or with a high tidal volume followed by ventilation with a low tidal volume of 6 ml/kg. Endothelial and epithelial protein permeability were significantly increased after high tidal volume ventilation but returned to baseline levels when tidal volume was reduced. The basal distal air space fluid clearance (AFC) rate decreased by 43% (P < 0.05) after 1 h of high tidal volume but returned to the preventilation rate 2 h after tidal volume was reduced. Not all of the effects of high tidal volume ventilation were reversible. The cAMP-dependent AFC rate after 1 h of 30 ml/kg ventilation was significantly reduced and was not restored when tidal volume was reduced. High tidal volume ventilation also increased lung inducible nitric oxide synthase (NOS2) expression and air space total nitrite at 3 h. Inhibition of NOS2 activity preserved cAMP-dependent AFC. Because air space edema fluid inactivates surfactant and reduces ventilated lung volume, the reduction of cAMP-dependent AFC by reactive nitrogen species may be an important mechanism of clinical ventilator-associated lung injury.

Brain natriuretic peptide (BNP) gene expression is a well documented marker of hypertrophy in the cardiac myocyte. Triiodothyronine (T(3)), the bioactive form of thyroid hormone, triggers a unique form of hypertrophy in cardiac myocytes that accompanies the selective activation or suppression of specific gene targets. In this study, we show that the BNP gene is a target of T(3) action. BNP secretion was increased 6-fold, BNP mRNA levels 3-fold, and BNP promoter activity 3-5-fold following T(3) treatment. This was accompanied by an increase in myocyte size, sarcomeric organization, and protein synthesis. Of note, several of the responses to T(3) synergized with those to the conventional hypertrophic agonist endothelin. The response to the liganded thyroid hormone receptor (TR) was mediated by an unusual thyroid hormone response element located between -1000 and -987 relative to the transcription start site. Both TR homodimers and TR.retinoid X receptor heterodimers associated with this element in an electrophoretic mobility shift assay. Protein fragments harboring the LXXLL motifs of the coactivators GRIP1 and SRC1 or TRAP220 interacted predominantly with the TR.retinoid X receptor heterodimeric pair in a ligand-dependent fashion. Both TR homodimers and heterodimers in the unliganded state selectively associated with glutathione S-transferase-nuclear receptor corepressor fragments harboring one of three receptor interaction domains containing the sequence (I/L)XX(I/V)I. These interactions were dissociated following the addition of T(3). Collectively, these findings identify the BNP gene as a potential model for the investigation of TR-dependent gene regulation in the heart.

BACKGROUND

Moderate alcohol intake has been associated with lower cardiovascular mortality. However, data evaluating the relationship between C-reactive protein (CRP), a predictor of cardiovascular risk, and alcohol consumption are sparse.

METHODS AND RESULTS

The relationship between alcohol consumption and CRP was evaluated in a cross-sectional survey and over time among 1732 men and 1101 women participating in the Pravastatin Inflammation/CRP Evaluation Study. CRP levels were lower in those with moderate alcohol intake versus light or occasional intake: in 5 categories of alcohol intake (no alcohol or <1 drink monthly, 1 to 3 drinks monthly, 1 to 4 drinks weekly, 5 to 7 drinks weekly, and > or =2 drinks daily), median CRP levels were 2.60 mg/L (interquartile range (IQR), 1.20 to 5.30 mg/L), 2.20 mg/L (IQR, 1.00 to 4.40 mg/L), 1.70 mg/L (IQR, 0.80 to 3.80 mg/L), 1.60 mg/L (IQR, 0.80 to 3.30 mg/L), and 1.80 mg/L (IQR, 0.80 to 2.90 mg/L), respectively. This relationship was present among men, women not taking hormone replacement therapy, nonsmokers, and those individuals with and without a history of cardiovascular disease (all P<0.001). In multivariate analysis, the relationship between alcohol consumption and CRP remained significant after controlling for multiple traditional cardiovascular risk factors. Alcohol consumption did not significantly affect the change in CRP or lipid levels associated with statin use.

CONCLUSION

Moderate alcohol consumption was associated with lower CRP concentrations than no or occasional alcohol intake, an effect that was independent of alcohol-related effects on lipids. Alcohol may attenuate cardiovascular mortality in part through an anti-inflammatory mechanism.