Association of elevated plasminogen activator inhibitor 1 levels with diminished lung function in patients with asthma

BACKGROUND

We previously reported that plasminogen activator inhibitor 1 (PAI-1) was upregulated in human asthmatic airways and promotes airway fibrosis in an allergen-challenged murine model of asthma.

OBJECTIVES

To examine whether elevated plasma levels of PAI-1 are associated with poor lung function in asthmatic patients.

METHODS

Five hundred nineteen adults were eligible for the study, and ultimately 353 adults were enrolled and completed the baseline protocol between January 24, 2004, and July 30, 2005. Of these, 231 adults with asthma from the Chicago Initiative to Raise Asthma Health Equity study were randomly selected and the plasma levels of PAI-1 were measured by enzyme-linked immunosorbent assay. Asthma burden, medication, smoking status, and body mass index (BMI) were obtained by history and spirometry was performed. A multivariate regression analysis was performed to evaluate the association of PAI-1 levels and lung function and the potential determinant variables that were associated with PAI-1.

RESULTS

We found associations between PAI-1 and BMI (β = 0.606, P = .002), smoking (β = 7.526, P = .001), and African American race (β = -9.061, P = .01). Obese patients showed a significant increase in PAI-1, and current smokers demonstrated higher levels of PAI-1 compared with nonsmokers. When we evaluated the associations between lung function parameters and PAI-1, we found that PAI-1 was negatively associated with forced vital capacity (FVC) (β = -0.098, P = .011) but not with forced expiratory volume in 1 second (FEV(1)) or the FEV(1)/FVC ratio. There was a negative association between BMI and FVC, and PAI-1 may mediate some of this association.

CONCLUSIONS

This study suggests a significant association between PAI-1 and lung function in patients with asthma. The effect of obesity on FVC may in part be mediated by PAI-1.

Differential enzymatic activity of common haplotypic versions of the human acidic Mammalian chitinase protein

Mouse models have shown the importance of acidic mammalian chitinase activity in settings of chitin exposure and allergic inflammation. However, little is known regarding genetic regulation of AMCase enzymatic activity in human allergic diseases. Resequencing the AMCase gene exons we identified 8 non-synonymous single nucleotide polymorphisms including three novel variants (A290G, G296A, G339T) near the gene area coding for the enzyme active site, all in linkage disequilibrium. AMCase protein isoforms, encoded by two gene-wide haplotypes, and differentiated by these three single nucleotide polymorphisms, were recombinantly expressed and purified. Biochemical analysis revealed the isoform encoded by the variant haplotype displayed a distinct pH profile exhibiting greater retention of chitinase activity at acidic and basic pH values. Determination of absolute kinetic activity found the variant isoform encoded by the variant haplotype was 4-, 2.5-, and 10-fold more active than the wild type AMCase isoform at pH 2.2, 4.6, and 7.0, respectively. Modeling of the AMCase isoforms revealed positional changes in amino acids critical for both pH specificity and substrate binding. Genetic association analyses of AMCase haplotypes for asthma revealed significant protective associations between the variant haplotype in several asthma cohorts. The structural, kinetic, and genetic data regarding the AMCase isoforms are consistent with the Th2-priming effects of environmental chitin and a role for AMCase in negatively regulating this stimulus.

[Referral to internal medicine for alcoholism: influence on follow-up care]

BACKGROUND AND AIMS

The problem of high rates of patient drop-out in alcohol treatment programs is frequently reported in the literature. Our aim was to investigate if internal medicine referral could improve abstinence and retention rates in a cohort of alcoholic patients.

PATIENTS AND METHODS

A retrospective observational study was conducted comparing 200 alcoholic patients attending a psychiatric unit (group 1) with 100 patients attending both this unit and an internal medicine unit (group 2). We collected sociodemographic and clinical variables and analysed differences regarding abstinence and retention rates by means of univariate and multivariate analysis.

RESULTS

At 3 and 12 months follow-up, group 2 patients had higher retention and abstinence rates than group 1 patients. Multivariate analysis including potential confounding variables showed that independent predictors of one-year retention were internal medicine referral and being married. Independent predictors of one-year abstinence were being married, age > 44 years and receipt of drug treatment.

CONCLUSIONS

The higher retention rate found among patients referred to Internal Medicine specialists, a result that has not been previously reported to the best of our knowledge, emphasizes the importance of a multidisciplinary team approach in the treatment of alcoholism.

On the preparation of TiO2-sepiolite hybrid materials for the photocatalytic degradation of TCE: influence of TiO2 distribution in the mineralization

Hybrid structured photocatalysts based on sepiolite, an adsorbent, and TiO2 were prepared by extrusion of ceramic dough and conformed as plates. The influence of the photocatalyst configuration was studied either by including TiO2 in the extrusion process (incorporated materials) or by coating the sepiolite plates with a TiO2 film (coated materials). The influence of the OH- surface concentration in the photocatalytic performance was studied by treating the ceramic plates at different temperatures. The samples were characterized by N2 adsorption-desorption, MIP, SEM, XRD, and UV-vis-NIR spectroscopy and tested in the photocatalytic degradation of trichloroethylene (TCE) as a target VOC molecule. Most of the catalysts presented high photoactivity, but considerable differences were observed when the CO2 selectivity was analyzed. The results demonstrate that there is a significant effect of the catalyst configuration on the selectivity of the process. An intimate contact between the sepiolite fibers and TiO2 particles for incorporated materials with a corncob-like structure favored the migration of nondesirable reaction products such as COCl2 and dichloroacetyl chloride (DCAC) to the adsorbent, reacting with OH- groups of the adsorbent and favoring the TCE mimeralization.

Rhinovirus induces airway epithelial gene expression through double-stranded RNA and IFN-dependent pathways

Rhinovirus (RV) infection is the major cause of common colds and of asthma exacerbations. Because the epithelial cell layer is the primary target of RV infection, we hypothesize that RV-induced airway disease is associated with the perturbation of airway epithelial gene expression. In this study, well differentiated primary human airway epithelial cells were infected with either RV16 (major group) or RV1B (minor group). Transcriptional gene profiles from RV-infected and mock-infected control cells were analyzed by Affymetrix Genechip, and changes of the gene expression were confirmed by real-time RT-PCR analysis. At 24 h after infection, 48 genes induced by both viruses were identified. Most of these genes are related to the IFN pathway, and have been documented to have antiviral functions. Indeed, a significant stimulation of IFN-beta secretion was detected after RV16 infection. Neutralizing antibody specific to IFN-beta and a specific inhibitor of the Janus kinase pathway both significantly blocked the induction of RV-inducible genes. Further studies demonstrated that 2-aminopurine, a specific inhibitor double-stranded RNA-dependent protein kinase, could block both IFN-beta production and RV-induced gene expression. Thus, IFN-beta-dependent pathway is a part of the double-stranded RNA-initiated pathway that is responsible for RV-induced gene expression. Consistent with its indispensable role in the induction of antiviral genes, deactivation of this signaling pathway significantly enhanced viral production. Because increase of viral yield is associated with the severity of RV-induced airway illness, the discovery of an epithelial antiviral signaling pathway in this study will contribute to our understanding of the pathogenesis of RV-induced colds and asthma exacerbations.

Relationship between airway inflammation, hyperresponsiveness, and obstruction in asthma

BACKGROUND

Although the role of eosinophils in airway inflammation in chronic asthma has been extensively studied, a role for neutrophils has not been well characterized. Furthermore, prior studies have not systematically sought or controlled for factors that might confound the relationship between cellular markers of inflammation and physiologic measures of airway function.

OBJECTIVE

The purpose of this study was to determine whether eosinophilic and neutrophilic inflammation independently contribute to abnormalities of airway function in asthma.

METHODS

Multivariate analysis of data collected during screening and enrollment of 205 asthmatic adults for clinical trials was conducted to examine the relationships between cellular inflammation in induced sputum and FEV(1) and methacholine responsiveness (PC(20)) while confounding factors were controlled for.

RESULTS

We found that age, sex, ethnicity, and use of inhaled corticosteroids were important confounding factors of the relationship between cellular inflammation and airway function. When these factors were controlled for, multivariate analysis showed that eosinophil percentage in induced sputum is independently associated with lower FEV(1) and lower PC(20) (P = .005 and P = .005, respectively). In the same models, increased sputum neutrophil percentage is independently associated with lower FEV(1) (P = .038) but not with PC(20) (P = .49).

CONCLUSIONS

These results suggest that both eosinophilic inflammation and neutrophilic inflammation independently contribute to abnormalities of FEV(1) in asthma. Therapies directed specifically at control of neutrophilic inflammation might be useful in improving airway caliber in patients with chronic asthma.

Two active-site tyrosyl residues of protein TrwC act sequentially at the origin of transfer during plasmid R388 conjugation

Protein TrwC is the relaxase-helicase responsible for the initiation and termination reactions of DNA processing during plasmid R388 conjugation. Site-directed mutagenesis was used to change to phenylalanine each of a set of four conserved tyrosyl residues in the sequence of the N-terminal relaxation domain of the protein. Simultaneous mutation of both Y18 and Y26 was required to abolish in vitro cleavage and strand-transfer reactions catalyzed by protein TrwC on oligonucleotides containing the nic site. Thus, both Y18 and Y26 could be involved independently in the formation of oligonucleotide-protein covalent complexes that constitute presumed intermediates of these reactions. This hypothesis was confirmed by the observation of Y18 and Y26-specific peptide-oligonucleotide adducts after protease digestion of TrwC and mutant derivatives. Finally mutation Y18F, but not mutation Y26F, abolished nic-cleavage of a supercoiled DNA containing the R388 origin of transfer (oriT). These data allowed the construction of a model for conjugative DNA processing in which Y18 specifically catalyzes the initial cleavage reaction, while Y26 is used for the second strand-transfer reaction, which terminates conjugation. The model suggests a control mechanism that can be effective at each conjugative replication cycle.

A hot spot in plasmid F for site-specific recombination mediated by Tn21 integron integrase

Integron In2 integrase (IntI1)-mediated site-specific recombination between two primary sites occurs at a high frequency, while that between a primary and a secondary site occurs at frequencies around 10,000 times lower. Secondary sites consist of a pentanucleotide with only two fully conserved residues (GWTMW). The analysis of IntI1-mediated recombinants in the plasmid pOX38 revealed the existence in this plasmid of a site used at a frequency intermediate between those of primary and secondary sites. Analysis of this site showed two potentially relevant structural features: first, a set of two consensus pentanucleotides, separated by 5 bp and in opposite orientations, forming what will be called a double site; and second, a longer sequence with some extent of sequence symmetry with the double site at its 3' end. A recombinant plasmid, pSU18P, containing a double site was constructed. Examination of R388-pSU18P recombinants showed that double sites were used preferentially over single pentanucleotides by IntI1. Comparisons of the nucleotide sequences of known 59-bp elements showed that in most cases there was a double site at each element end. Mutagenesis of the F hot spot was carried out to make it look more like the consensus 59-bp element. The improved sites showed recombination frequencies and specificities almost comparable to those observed at IntI1 primary sites.

Genes involved in conjugative DNA processing of plasmid R6K

The conjugative transfer region of the IncX plasmid R6K (TRA(x)) was analysed by transposon mutagenesis and DNA sequencing. Tn5tac1 insertional mutations localized TRA(x) to a 14.8 kb segment containing the alpha origin of transfer (oriT alpha), genes involved in conjugative DNA-processing (Dtr(x)) and genes involved in pilus synthesis and assembly (Mpf(x)). A second functional oriT, oriTbeta, was located at a distance of 5.3 kb from oriT alpha and was outside TRA(x). Mpf(x) occupied a segment of 10kb, as judged by the location of insertions conferring resistance to infection by the X pilus-specific phage X-2. At both sides of Mpf(x) there were insertions that were Tra but X-2 sensitive, suggesting that the mutations were in Dtr(x). This region was sequenced and three genes were identified: taxA, taxB, and taxC. The overall organization was oriT alpha-taxA-taxC-Mpf(x)-taxB. taxC coded for a oriT-relaxase that belongs to the VirD2 family. taxA coded for a protein of 181 amino acids that showed similarity to TraY of F-like plasmids and to the Arc-repressor superfamily. TaxB showed similarity to TraG-like proteins, a protein superfamily probably involved in coupling the relaxosome to the DNA-transport apparatus. TaxA and TaxC are required for oriT nicking in vivo. The nicking reaction was mistakenly assumed by Flashner et al. (1996) to represent a feature of the vegetative replication origins. However, insertions or deletions disrupting taxA and taxC affected conjugation but not replication of R6K. Conversely, protein pi, which is absolutely required for replication of R6K, was not required for conjugative transfer. In addition, protein DDP3, which is also assumed to have a role in replication, was found to be a positive modulator of bacterial conjugation. Taken together, these results rule out a direct and essential involvement of conjugation proteins in R6K vegetative replication, and also rule out the requirement of replication protein pi for conjugation.