Phosphatase and tensin homologue deleted on chromosome ten (PTEN) as a molecular target in lung epithelial wound repair.

BACKGROUND AND PURPOSE: Epithelial injury contributes to lung pathogenesis. Our work and that of others have identified the phosphoinositide-3 kinase (PI3K)/Akt pathway as a vital component of survival in lung epithelia. Therefore, we hypothesized that pharmacological inhibition of PTEN, a major suppressor of this pathway, would enhance wound closure and restore lung epithelial monolayer integrity following injury. EXPERIMENTAL APPROACH: We evaluated the ability of two bisperoxovanadium derivatives, bpV(phen) and bpV(pic), in differentiated primary human airway epithelia and BEAS2B cultures for their ability to inhibit PTEN, activate the PI3K/Akt pathway and restore epithelial monolayer integrity following mechanical injury. KEY RESULTS: BpV(phen) and bpV(pic) induced Akt phosphorylation in primary and BEAS2B cells in a dose and time dependent manner. Minimal toxicity was observed as measured by lactate dehydrogenase (LDH) release. To verify that Akt phosphorylation is specifically induced by PTEN inhibition, the PTEN positive cell line, DU145, and two PTEN negative cell lines, LNCaP and PC3, were examined. PTEN positive cells demonstrated a dose responsive increase in Akt phosphorylation whereas PTEN negative cells showed no response indicating that bpV(phen) directly suppresses PTEN without affecting auxiliary pathways. Next, we observed that exposure to either compound resulted in accelerated wound closure following mechanical injury. Similar effects were observed after transfection with a dominant negative isoform of PTEN and PTEN specific siRNA. CONCLUSIONS AND IMPLICATIONS: From these studies, we conclude that PTEN is a valid target for future studies directed at restoring epithelial barrier function after lung injury.

Sequential processing of human ProIL-1beta by caspase-1 and subsequent folding determined by a combined in vitro and in silico approach.

PURPOSE: Interleukin-1beta is a multifunctional cytokine produced by activated monocytes and macrophages that requires caspase-1 (IL-1 converting enzyme/ICE) to process the 31kDa inactive precursor protein to the biologically active 17kDa peptide. This activation event involves ICE cleavage at Asp27 (site 1) and Asp116 (site 2). To address the sequential processing at ICE cut sites we combined in vitro analysis and molecular modeling to investigate the sequence of molecular events. METHODS: Pulse chase labeling followed by immunoprecipitation of IL-1beta in activated human monocyte lysates demonstrated sequential cutting by ICE at site 1 before site 2 in vitro. To corroborate these findings, we constructed a homology model of proIL-1beta after the crystal structure of another ICE substrate, human alpha1-antitrypsin (23% sequence identity). RESULTS: Comparative modeling revealed that site 1 on proIL-1beta is accessible to ICE but site 2 is not. Molecular dynamics simulations following ICE cleavage at site 1 and removal of the 3kDa amino-terminal fragment, rendered site 2 accessible to ICE. CONCLUSIONS: The close agreement between the in vitro and modeled behavior of IL-1beta support our contention that IL-1beta may be structurally related to alpha1-antitrypsin and also predicts that proIL-1beta requires sequential processing for activation. These findings may facilitate the development of novel pharmacological agents that control posttranslational proIL-1beta modification, thereby preventing excessive production of this potent inflammatory cytokine.

Induction of interleukin-8 release by lung epithelium with cystic fibrosis epithelial lining fluid is marginally affected by inhibitors of interleukin-1beta.

Interleukin-1beta (IL-1beta) and neutrophil elastase (NE) are present in the epithelial lining fluid (ELF) of patients with cystic fibrosis (CF). Both factors activate surrounding cells including lung epithelial cells, causing release of IL-8, a potent chemoattractant for neutrophils. Previous studies showed up-regulation of IL-8 release by lung epithelial cells as a function of NE in CF; however, few studies addressed the relationship between IL-1beta and activation of lung epithelial cells in CF lungs. Confluent layers of A549 cells, a type II-like human lung epithelial cell line, were incubated overnight with IL-1beta (0-5 ng/ml) or NE (100 nM), and supernatants were analyzed for IL-8 by enzyme-linked immunosorbent assay (ELISA). Both IL-1beta and NE led to a significant increase in IL-8: 12.8 +/- 2.8 ng/ml and 0.8 +/- 0.3 ng/ml, respectively. Next, bronchoalveolar lavage (BAL) samples were obtained from one healthy adult volunteer and six patients with CF and measured for IL-8 and IL-1beta concentrations by ELISA. Both IL-8 (range 169.00 +/- 56.57 to 1742.04 +/- 338.98 pg/ml) and IL-1beta (range 0-24.26 +/- 0.52 pg/ml) were detected in CF specimens, whereas neither was detected in the volunteer's specimen. Normal and CF BALs then were incubated overnight at a 1:10 dilution with confluent A549 cells. Analysis by ELISA of cell-free supernatants revealed increased IL-8 production from cells stimulated with CF BALs only. Similar experiments were performed with BAL supernatants that had been incubated with soluble IL-1 type II receptor, soluble IL-1 receptor antagonist, or a peptide inhibitor of NE. Addition of IL-1 inhibitors had a marginal effect on the amount of IL-8 release after incubation with CF BAL samples, whereas inhibition of NE had no effect. Our results indicate that other factors present in ELF in CF account for IL-8 release from lung epithelial cells.

Extracellular regulation of interleukin (IL)-1beta through lung epithelial cells and defective IL-1 type II receptor expression.

Interleukin (IL)-1beta is produced primarily by activated mononuclear phagocytic cells in the lung airway and functions as a potent proinflammatory cytokine. Release of IL-1beta in the airway microenvironment induces the production of proinflammatory factors from parenchymal airway cells, including IL-8. To study the regulation of lung epithelial cell responsiveness to IL-1beta, the human type II-like airway epithelial cell line A549 and primary normal human bronchial epithelial (NHBE) cells were assayed for IL-1-specific response modifiers. Specifically, the IL-1 type I receptor (IL-1RI), IL-1 type II receptor (IL-1RII), IL-1 receptor accessory protein (IL-1RAcP), and IL-1 receptor antagonist (IL-1Ra) were analyzed. Constitutive expression of IL-1RI, IL-1RAcP, and IL-1Ra was detected in both immortalized and primary human airway epithelial cells. Interestingly, a complete absence of IL-1RII expression was demonstrated under all study conditions in both A549 and NHBE cells. Both cell types were responsive to IL-1beta at concentrations as low as 50 to 500 pg/ml when measured by IL-8 release into cell supernatants. IL-1beta-induced chemokine production and release were inhibited by a 10- to 1,000-fold molar excess of recombinant IL-1RII or IL-1Ra, whereas IL-1RI was a less effective inhibitor. On the basis of our results, we propose that human lung epithelial cells lack the ability to downregulate IL-1beta activity extracellularly because of an inability to express IL-1RII. Release of extracellular IL-1 inhibitors, including soluble IL-1Ra and soluble IL-1RII, by other inflammatory cells present in the airway may be critical for regulation of IL-1beta activity in the airway microenvironment.

Measurement of outcomes in adults receiving pharmaceutical care in a comprehensive asthma outpatient clinic.

We hypothesized that a pharmacist-provided comprehensive education program in conjunction with care provided by a pulmonologist would lead to improved economic, clinical, and humanistic outcomes in adults with asthma, compared with similar patients receiving care from a pulmonologist alone. The experimental group reported receiving more information about asthma self-management (p=0.001), were more likely to monitor peak flow readings (p=0.004), and had increased satisfaction with care, and perceived higher quality of care. Both groups had less lost productivity, fewer emergency department visits, fewer hospitalizations, and fewer physician visits, as well as improvement in symptoms scores within 45 days. Both groups improved in all functional status domains except the mental component score of the SF-12. Our results show a positive impact on outcomes in adults with asthma who received pharmaceutical care.

Churg-Strauss syndrome associated with zafirlukast.

The leukotriene receptor antagonist zafirlukast (Accolate; Zeneca Pharmaceuticals; Wilmington, Del) recently was approved for use as maintenance therapy for persistent asthma. This new product has been well received due to convenient dosing and relatively few side effects. Based on initial success with this product, it is likely that similar compounds will be available for use in the near future. In this report, a case is described of a 47-year-old white man with moderate persistent asthma in whom Churg-Strauss syndrome developed while he was receiving zafirlukast therapy. Acute respiratory insufficiency, arthralgia, and prominent rash developed which required hospitalization. The patient's symptoms rapidly reversed following discontinuation of zafirlukast therapy and administration of systemic corticosteroids. Although the incidence of Churg-Strauss syndrome associated with zafirlukast therapy is rare, this case report illustrates steps that may be taken to diagnose quickly and treat this life-threatening condition should it occur.

Human gene therapy for hereditary diseases: a review of trials.

Human gene therapy trials directed at hereditary diseases, including adenosine deaminase (ADA) deficiency, familial hypercholesterolemia, and cystic fibrosis, are reviewed. Human gene therapy involves the introduction and expression of recombinant genes in somatic, nonreproductive cells with the intent to reverse or prevent a particular disease. Two methods for introducing genes into human cells are currently being used in clinical trials. Ex vivo gene delivery involves removing targeted cells from the patient's body, introducing the recombinant gene into the cells, and placing the modified cells back into the patient's body. In vivo gene delivery involves placing the recombinant gene directly into the patient's body, targeting the tissue or cell of interest. The transfer of the recombinant gene into the cell and the subsequent expression of the transgene product are the rate-limiting steps for successful gene therapy. A variety of methods, including the use of modified viruses and synthetic vectors, are currently being used in clinical trials. Since the approval and initiation of the first human gene therapy trial to treat ADA deficiency in 1989, there have been more than 170 approved gene therapy trials in the United States. More than 1500 patients have been enrolled in human gene therapy trials worldwide. Preliminary clinical trials have targeted diseases such as ADA deficiency, familial hypercholesterolemia, and cystic fibrosis. These trials have employed variable designs and strategies, making interpretation of the results difficult. However, the initial data are encouraging, and the procedures have been well tolerated. The clinical utility of human gene therapy remains to be defined; immediate efforts will focus on improving vector design to limit toxicity and enhance the efficiency of gene transfer.

Lymphocytes produce IL-1beta in response to Fcgamma receptor cross-linking: effects on parenchymal cell IL-8 release.

Neutrophils mediate tissue injury in response to immune complexes, although the factors that induce their recruitment are incompletely understood. We have reported that lymphocytes may be important regulators of monocyte and macrophage IL-8 release in the presence of immobilized IgG. Since tissue parenchymal cells are important local producers of IL-8 but are not directly stimulated by FcgammaR cross-linking, we hypothesized that lymphocytes may also regulate parenchymal IL-8 release. Supernatants from lymphocytes incubated on immobilized IgG induced primary human fibroblasts and human mesangial cells to produce IL-8 (17 +/- 3.5 and 44 +/- 8 ng/ml, respectively). Fibroblast and mesangial cell IL-8 mRNA levels were similarly increased by the conditioned lymphocyte supernatant. Immobilized anti-human FcgammaRIII, but not FcgammaRI or FcgammaRII Abs, could stimulate this IL-8-inducing activity in lymphocytes, suggesting that FcgammaRIII-bearing lymphocytes were responsible. Supernatants from lymphocytes incubated on immobilized IgG contained 2.2 +/- 0.8 ng/ml of IL-1beta, while enriched monocyte preparations from the same donors incubated on immobilized IgG released only 0.1 +/- 0.04 ng/ml of IL-1beta (p = 0.05). Consistent with the identification of IL-1beta as the lymphocyte factor, fibroblast or mesangial cell IL-8 release induced by the IgG-stimulated lymphocyte supernatants was inhibited by 1) the combination of IL-1R antagonist and soluble type II IL-1R, 2) an IL-1-converting enzyme inhibitor, or 3) anti-IL-1beta but not preimmune Abs. These data suggest that targeted deposits of IgG can stimulate FcgammaRIII-bearing lymphocytes to produce IL-1beta, which induces parenchymal cell IL-8 release.

Alpha 1-antitrypsin and protease complexation is induced by lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha in monocytes.

Local regulation of alpha1-antitrypsin (alpha1-AT) may have importance in maintenance of the protease-antiprotease balance in the microenvironment of inflammatory cells. We therefore studied whether lipopolysaccharide (LPS), interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNFalpha) affect the pericellular concentration of alpha1-AT in human peripheral blood mononuclear cells (PBMC). PBMC taken from normal healthy volunteers were treated with LPS, IL-1beta, and TNFalpha, and the concentration of human alpha1-AT in conditioned supernatants was measured. When compared with unstimulated control supernatants (147 +/- 19 ng/ml), LPS (439 +/- 66 ng/ml; p < or = 0.001), IL-1beta (263 +/- 37 ng/ml; p < or = 0.01), and TNFalpha (316 +/- 59 ng/ml; p < or = 0.05) induced a 2- to 3-fold increase of alpha1-AT. Up-regulation of alpha1-AT protein correlated with an increase in alpha1-AT mRNA, suggesting a simultaneous increase in alpha1-AT synthesis. Despite the increase in alpha1-AT concentration, functional antiprotease activity could not be detected. Furthermore, protease activity was present in all samples, with the amount of activity being inversely related to the amount of alpha1-AT measured in supernatants. These findings suggest that local inflammatory conditions up-regulate alpha1-AT production by monocytes which complex with a protease derived from the PBMC population.

Gene targeting of CFTR DNA in CF epithelial cells.

A goal of cystic fibrosis (CF) gene therapy is correction of the mutant CF transmembrane conductance regulator (CFTR) gene with wild-type (wt) DNA sequences to restore normal CFTR protein and function. Experiments with wtCFTR cDNA expression vectors have shown that the Cl ion transport phenotype associated with CF can be corrected to resemble that in normal cells. An alternative to cDNA-based gene therapy strategies is one that corrects endogenous mutant sequences by targeted replacement with the wt homologue. To test whether such a strategy was feasible, a small fragment homologous replacement (SFHR) strategy was used to replace specific genomic sequences in human epithelial cells. Small fragments of genomic wtCFTR DNA were transfected into transformed CF epithelial cells. Replacement by exogenous CFTR DNA at the appropriate genomic locus and its expression as mRNA was indicated by: (1) allele-specific polymerase chain reaction (PCR) amplification of genomic DNA and mRNA-derived cDNA; and (2) hybridization of PCR products with allele-specific probes. In addition, the functional activity of CFTR protein was determined by whole cell patch clamp. Southern hybridization and patch clamp analyses suggested that approximately 1 in 100 CF cells underwent a homologous replacement event that resulted in intact Cl transport.

Targeted gene delivery with a low molecular weight glycopeptide carrier.

A low molecular weight glycopeptide carrier was prepared by coupling a tyrosinamide-triantennary oligosaccharide to dp19 poly-L-lysine resulting in a 1:1 conjugate. The glycopeptide carrier complexed with plasmid DNA as evidenced by displacement of intercalated dye, light scattering by condensed DNA, and immobility of complexed DNA upon agarose gel electrophoresis. DNA-carrier complexes were endocytosed into HepG2 cells via the asialoglycoprotein receptor due to recognition of terminal galactose residues on the oligosaccharide. The resulting luciferase reporter gene expression was dramatically influenced by the solubility of complexes, the extent of complexation, and the presence of the lysosomotropic agent chloroquine. The results suggest that low molecular weight glycopeptides may be suitable for further development as well-defined DNA carriers for receptor-mediated gene delivery in vivo.