Rationale: Pulmonary infections can impair alveolar fluid clearance (AFC), contributing to formation of lung edema. Effects of influenza A virus (IAV) on AFC are unknown. Objectives: To determine effects of IAV infection on AFC, and to identify intercellular signaling mechanisms underlying influenzamediated inhibition of AFC. Methods: BALB/c mice were infected intranasally with influenza A/WSN/33 (10,000 or 2,500 focus-forming units per mouse). AFC was measured in anesthetized, ventilated mice by instilling 5% bovine serum albumin into the dependent lung. Measurements and Main Results: Infection with high-dose IAV resulted in a steady decline in arterial oxygen saturation and increased lung water content. AFC was significantly inhibited starting 1 hour after infection, and remained suppressed through Day 6. AFC inhibition at early time points (1-4 h after infection) did not require viral replication, whereas AFC inhibition later in infection was replication-dependent. Low-dose IAV infection impaired AFC for 10 days, but induced only mild hypoxemia. High-dose IAV infection increased bronchoalveolar lavage fluid ATP and UTP levels. Impaired AFC at Day 2 resulted primarily from reduced amiloride-sensitive AFC, mediated by increased activation of the pyrimidine-P2Y purinergic receptor axis. However, an additional component of AFC impairment was due to activation of A 1 adenosine receptors and stimulation of increased cystic fibrosis transmembrane regulator-mediated anion secretion. Finally, IAV-mediated inhibition of AFC at Day 2 could be reversed by addition of b-adrenergic agonists to the AFC instillate. Conclusions: AFC inhibition may be an important feature of early IAV infection. Its blockade may reduce the severity of pulmonary edema and hypoxemia associated with influenza pneumonia.

Aeffner F, Traylor ZP, Yu ENZ, Davis IC. Double-stranded RNA induces similar pulmonary dysfunction to respiratory syncytial virus in BALB/c mice.

Adrenergic agonists (␤-agonists) are commonly used to treat respiratory syncytial virus (RSV) bronchiolitis but are generally ineffective for unknown reasons. We have previously shown that RSV strain A2 inhibits bronchoalveolar epithelial responses to ␤-agonists in a BALB/c mouse model by inducing heterologous keratinocyte cytokine (KC)/CXCR2-mediated desensitization of epithelial ␤ 2-adrenergic receptors. The aim of the current study was to determine whether RSV also induces airway insensitivity to ␤-agonists. Total lung resistance (R) was measured in anesthetized female BALB/c mice undergoing mechanical ventilation on a flexiVent computer-controlled piston ventilator. Data were analyzed using the single-compartment model. Infection with RSV A2 did not induce airway hyperresponsiveness to increasing doses of the nebulized cholinergic agonist methacholine (MCh) at any time point after RSV infection. Prenebulization with the ␤-agonist terbutaline (100 M) significantly attenuated bronchoconstrictive responses to 20 and 50 mg/ml MCh in uninfected mice and in mice infected with RSV 4 -8 days postinfection (d.p.i.). However, in mice infected with replication-competent, but not UV-inactivated, RSV for 2 days, significant terbutaline insensitivity was found. Terbutaline insensitivity at 2 d.p.i. could be reversed by systemic preinfection treatment with neutralizing anti-CXCR2 antibodies, which reduced bronchoalveolar lavage (BAL) neutrophil counts but did not alter viral replication, BAL KC levels, or lung edema. Terbutaline insensitivity was also reversed by postinfection nebulization with neutralizing anti-KC or anti-CXCR2 antibodies and could be replicated in normal, uninfected mice by nebulization with recombinant KC. These data suggest that KC/CXCR2-mediated airway insensitivity to ␤-agonists may underlie the modest utility of these drugs as bronchodilators in therapy for acute RSV bronchiolitis. CXCL8; CXCR2; keratinocyte cytokine; airway hyperresponsiveness RESPIRATORY SYNCYTIAL VIRUS (RSV) is the most common cause of lower respiratory tract disease in infants and children worldwide (36). In the United States, 50 -70% of infants are infected with RSV in the first year of life (29) with bronchiolitis now accounting for approximately 75,000 -125,000 hospitalizations annually (32, 33). RSV-related mortality has decreased over the last 20 yr, but RSV remains the leading cause of viral deaths in infants (33). In addition, this virus is increasingly recognized as being underdiagnosed as a cause of communityacquired lower respiratory tract infections among adults (10) and is a significant cause of excess morbidity and mortality in immune-compromised adults (41). Indeed, recent studies suggest that RSV has a disease impact comparable with that of nonpandemic influenza A in the elderly (9).

High tidal volume ventilation is detrimental to alveolar fluid clearance (AFC), but effects of ventilation pressure (P) on AFC are unknown. In anesthetized BALB/c mice ventilated at constant tidal volume (8 ml/kg), mean AFC rate was 12.8% at 6 cmH(2)O P, but increased to 37.3% at 18 cmH(2)O P. AFC rate declined at 22 cmH(2)O P, which also induced lung damage. Increased AFC at 18 cmH(2)O P did not result from elevated plasma catecholamines, hypercapnia, or hypocapnia, but was due to augmented Na(+) and Cl(-) absorption. PKA agonists and beta-agonists stimulated AFC at 10 cmH(2)O P by upregulating amiloride-sensitive Na(+) transport. However, at 18 cmH(2)O P, PKA agonists and beta-agonists reduced AFC. At 15 cmH(2)O P, the AFC rate was intermediate (mean 26.6%), and forskolin and beta-agonists had no effect. Comparable P dependency of AFC and beta-agonist responsiveness was found in C57BL/6 mice. The effect on AFC of increasing P to 18 cmH(2)O was blocked by adenosine deaminase or an A(2b)-adenosine receptor antagonist, and could be mimicked by adenosine in mice ventilated at 10 cmH(2)O P. Modulation of adenosine signaling also resulted in altered responsiveness to beta-agonists. These findings indicate that, in the normal mouse lung, basal AFC rates and responses to beta-agonists are impacted by ventilation pressure in an adenosine-dependent manner.

Benign and malignant pulmonary tumors have been reported in both Old World and New World monkeys but are uncommon. Hemangiomas are also rarely reported in nonhuman primates. Here we present a case of two primary neoplasms (a papillary adenocarcinoma of bronchioloalveolar origin and multiple cavernous subcutaneous hemangiomas) arising in an aged squirrel monkey (Saimiri sciureus).