Recent data indicate that cystic fibrosis (CF) airway mucus is anaerobic. This suggests that Pseudomonas aeruginosa infection in CF reflects biofilm formation and persistence in an anaerobic environment. P. aeruginosa formed robust anaerobic biofilms, the viability of which requires rhl quorum sensing and nitric oxide (NO) reductase to modulate or prevent accumulation of toxic NO, a byproduct of anaerobic respiration. Proteomic analyses identified an outer membrane protein, OprF, that was upregulated approximately 40-fold under anaerobic versus aerobic conditions. Further, OprF exists in CF mucus, and CF patients raise antisera to OprF. An oprF mutant formed poor anaerobic biofilms, due, in part, to defects in anaerobic respiration. Thus, future investigations of CF pathogenesis and therapy should include a better understanding of anaerobic metabolism and biofilm development by P. aeruginosa.

Adenoviral (Ad)-mediated in vivo gene transfer and expression are limited in part by cellular immune responses to viral-encoded proteins and͞or transgene immunogenicity. In an attempt to diminish the former responses, we have previously developed and described helper-dependent (HD) Ad vectors in which the viral protein coding sequences are completely eliminated. These HD vectors have up to 37 kb insert capacity, are easily propagated in a Cre recombinasebased system, and can be produced to high concentration and purity (>99.9% helper-free vector). In this study, we compared safety and efficacy of leptin gene delivery mediated by an HD vector (HD-leptin) and a first-generation E1-deleted Ad vector (Ad-leptin) in normal lean and ob͞ob (leptindeficient) mice. In contrast to evidence of liver toxicity, inf lammation, and cellular infiltration observed with Adleptin delivery in mice, HD-leptin delivery was associated with a significant improvement in associated safety͞toxicity and resulted in efficient gene delivery, prolonged elevation of serum leptin levels, and associated weight loss. The greater safety, efficient gene delivery, and increased insert capacity of HD vectors are significant improvements over current Ad vectors and represent favorable features especially for clinical gene therapy applications. Adenoviral (Ad) vectors are currently among the most efficient gene transfer vehicles for both in vitro and in vivo delivery, but the utilization of current Ad vectors for many gene therapy applications is limited by the transient nature of transgene expression obtained by these vectors (1-7). Several factors have been shown to contribute to and modulate the duration of Ad-mediated gene expression and the immunogenicity of these vectors, including ''leaky'' viral protein expression and the transgene that is delivered (8-15). The development of Ad vectors that are deleted in all viral protein-coding sequences offers the prospect of a potentially safer, less immunogenic vector with an insert capacity of up to 37 kb (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). This vector is supplied in trans with the structural proteins required for packaging and rescue and is thus helper-dependent (HD) (24).Leptin has been recently identified as a potent modulator of weight and food intake. Daily delivery of recombinant leptin protein was shown to induce weight reduction, suppress appetite, and decrease blood insulin and glucose levels in ob͞ob (leptindeficient) mice (27)(28)(29). It has been shown that delivery of the leptin cDNA by first-generation Ad vectors (Ad-leptin) may substitute for daily recombinant leptin protein treatment, although the effects were transient in both lean and ob͞ob treated mice (7,30). In the present study, we delivered the leptin cDNA using the HD virus (HD-leptin), testing the hypothesis that elimination of the viral protein coding sequences would diminish the vector's cellular immunogenicity and toxicity, and hence support its longevity in vivo. Because both the viral proteins and the trans...

Pulmonary inflammation, abnormalities in alveolar type II cell and macrophage morphology, and pulmonary fibrosis are features of Hermansky-Pudlak Syndrome (HPS). We used the naturally occurring “pearl” HPS2 mouse model to investigate the mechanisms of lung inflammation observed in HPS. Although baseline bronchoalveolar lavage (BAL) cell counts and differentials were similar in pearl and strain-matched wild-type (WT) mice, elevated levels of proinflammatory (MIP1γ) and counterregulatory (IL-12p40, soluble TNFr1/2) factors, but not TNF-α, were detected in BAL from pearl mice. After intranasal LPS challenge, BAL levels of TNF-α, MIP1α, KC, and MCP-1 were 2- to 3-fold greater in pearl than WT mice. At baseline, cultured pearl alveolar macrophages (AMs) had markedly increased production of inflammatory cytokines. Furthermore, pearl AMs had exaggerated TNF-α responses to TLR4, TLR2, and TLR3 ligands, as well as increased IFN-γ/LPS-induced NO production. After 24 h in culture, pearl AM LPS responses reverted to WT levels, and pearl AMs were appropriately refractory to continuous LPS exposure. In contrast, cultured pearl peritoneal macrophages and peripheral blood monocytes did not produce TNF-α at baseline and had LPS responses which were no different from WT controls. Exposure of WT AMs to heat- and protease-labile components of pearl BAL, but not WT BAL, resulted in robust TNF-α secretion. Similar abnormalities were identified in AMs and BAL from another HPS model, pale ear HPS1 mice. We conclude that the lungs of HPS mice exhibit hyperresponsiveness to LPS and constitutive and organ-specific macrophage activation.