Kenneth J. Holroyd

Genetic Susceptibility to Asthma — Bronchial Hyperresponsiveness Coinherited with a Major Gene for Atopy

BACKGROUND Bronchial hyperresponsiveness, a risk factor for asthma, consists of a heightened bronchoconstrictor response to a variety of stimuli. The condition has a heritable component and is closely related to serum IgE levels and airway inflammation. The basis for these relations is unknown, as is the mechanism of genetic susceptibility to bronchial hyperresponsiveness. We attempted to define the interrelation between atopy and bronchial hyperresponsiveness and to investigate the chromosomal location of this component of asthma. METHODS We studied 303 children and grandchildren of 84 probands with asthma selected from a homogeneous population in the Netherlands. Ventilatory function, bronchial responsiveness to histamine, and serum total IgE were measured. The association between the last two variables was evaluated. Using analyses involving pairs of siblings, we tested for linkage between bronchial hyperresponsiveness and genetic markers on chromosome 5q31-q33, previously shown to be linked to a genetic locus regulating serum total IgE levels. RESULTS Serum total IgE levels were strongly correlated (r = 0.65, P < 0.01) in pairs of siblings concordant for bronchial hyperresponsiveness (defined as a > or = 20 percent decrease in the forced expiratory volume in one second produced by histamine [threshold dose, < or = 16 mg per milliliter]), suggesting that these traits are coinherited. However, bronchial hyperresponsiveness was not correlated with serum IgE levels (r = 0.04, P > 0.10). Analyses of pairs of siblings showed linkage of bronchial hyperresponsiveness with several genetic markers on chromosome 5q, including D5S436 (P < 0.001 for a histamine threshold value of < or = 16 mg per milliliter). CONCLUSIONS This study demonstrates that a trait for an elevated level of serum total IgE is coinherited with a trait for bronchial hyperresponsiveness and that a gene governing bronchial hyperresponsiveness is located near a major locus that regulates serum IgE levels on chromosome 5q. These findings are consistent with the existence of one or more genes on chromosome 5q31-q33 causing susceptibility to asthma.

Systemic glutathione deficiency in symptom-free hiv-seropositive individuals

To find out whether systemic glutathione deficiency is associated with human immunodeficiency virus (HIV) infection, thus contributing to the immunodeficiency state, glutathione concentrations in venous plasma and lung epithelial lining fluid (ELF) of symptom-free HIV-seropositive and normal individuals were measured. Total and reduced glutathione concentrations in the plasma of the HIV-infected subjects were about 30% of those in the normal individuals. Concentrations of these substances in the ELF of HIV-infected subjects were about 60% of those in the controls. There was no correlation between ELF and plasma concentrations of total or reduced glutathione. Since glutathione enhances immune function, glutathione deficiency may contribute to the progressive immune dysfunction of HIV infection.

IL-9 and its receptor in allergic and nonallergic lung disease: Increased expression in asthma

BACKGROUND Bronchial asthma is a chronic inflammatory disease associated with genetic components. Recently IL-9 has been reported as a candidate gene for asthma and to be associated with bronchial hyperresponsiveness and elevated levels of total serum IgE. OBJECTIVE To investigate the contribution of IL-9 to the pathogenesis of asthma, we examined the expression of IL-9 and its receptor (IL-9R) in bronchial tissue from subjects with atopic asthma (n = 10), chronic bronchitis (n = 11), and sarcoidosis (n = 9) and from atopic (n = 7) and nonatopic (n = 10) healthy control subjects. METHODS Bronchial biopsy specimens were examined for the presence of IL-9 and IL-9R protein and messenger RNA (mRNA) by immunocytochemistry and in situ hybridization, respectively. To phenotype the cells expressing IL-9 in asthmatic tissue, combined in situ hybridization and immunocytochemistry was also performed. RESULTS There was a highly significant difference (P <.001) in the expression of IL-9 mRNA in asthmatic airways (20.6 +/- 4.0 cells/mm of basement membrane) compared with chronic bronchitis (5.6 +/- 4.4), sarcoidosis (2.5 +/- 1.8), atopic control subjects (7.7 +/- 2.2), and healthy control subjects (2.7 +/- 2.3). The number of IL-9 immunoreactive cells was also greater in asthmatic patients compared with the other groups (P <.05). Although the level of IL-9R mRNA expression did not differ in any of the groups (P >.05), IL-9R immunoreactivity was significantly higher in asthmatic compared with control subjects. Furthermore, IL-9 mRNA expression levels were also significantly correlated with FEV(1) (P <.05) and the airway responsiveness to methacholine producing a 20% fall in FEV(1) (P <. 01). The cells expressing IL-9 mRNA in asthmatic tissue were CD3(+) lymphocytes (68%), major basic protein(+) eosinophils (16%), and elastase(+) neutrophils (8%). CONCLUSION The results of this study demonstrate the potential of IL-9 to be a marker for atopic asthma and furthermore suggest an important role for this cytokine in the pathophysiologic mechanisms of this disease.

Topical versus Systemic Antimicrobial Therapy for Treating Mildly Infected Diabetic Foot Ulcers: A Randomized, Controlled, Double-Blinded, Multicenter Trial of Pexiganan Cream

BACKGROUND Topical antimicrobial therapy of infected diabetic foot ulcers can focus on the wound and avoid the adverse effects of systemic anti-infective agents. We compared the efficacy of outpatient treatment using an investigational topical antimicrobial peptide, pexiganan acetate cream, with the efficacy of systemic therapy using an oral fluoroquinolone antibiotic, ofloxacin, for mildly infected diabetic foot ulcers. METHODS In 2 consecutive, double-blind, controlled trials (study 303 and study 304), we randomized diabetic patients with a mildly infected diabetic foot ulcer to receive the active topical agent or active oral antibiotic, plus a respective inactive placebo. The primary outcome of interest was clinical cure or improvement of the infection. Secondary outcomes included eradication of wound pathogens and wound healing, which was documented by a semiquantitative scoring system. RESULTS Overall, 835 patients were randomized; those in each treatment arm were similar with regard to demographic and clinical characteristics. Although study 303 failed to demonstrate equivalence, study 304 and the combined data for the 2 trials demonstrated equivalent results (within the 95% confidence interval) for topical pexiganan and oral ofloxacin in clinical improvement rates (85%-90%), overall microbiological eradication rates (42%-47%), and wound healing rates. The incidence of worsening cellulitis (2%-4%) and amputation (2%-3%) did not differ significantly between treatment arms. Bacterial resistance to ofloxacin emerged in some patients who received ofloxacin, but no significant resistance to pexiganan emerged among patients who received pexiganan. CONCLUSIONS Topical pexiganan might be an effective alternative to oral antibiotic therapy in treating diabetic patients with a mildly infected foot ulcer, and might reduce the risk of selecting antimicrobial-resistant bacteria.

Interleukin-9 promotes allergen-induced eosinophilic inflammation and airway hyperresponsiveness in transgenic mice

Human atopic asthma is a complex heritable inflammatory disorder of the airways associated with clinical signs of allergic inflammation and airway hyperresponsiveness. Recent studies demonstrate that the degree of airway responsiveness is strongly associated with interleukin (IL)-9 expression in murine lung. To investigate the contribution of IL-9 to airway hyperresponsiveness, and to explore directly its relationship to airway inflammation, we studied transgenic mice overexpressing IL-9. In this report we show that IL-9 transgenic mice (FVB/N-TG5), in comparison with FVB/NJ mice, display significantly enhanced eosinophilic airway inflammation, elevated serum total immunoglobulin E, and airway hyperresponsiveness following lung challenge with a natural antigen (Aspergillus fumigatus). These data support a central role for IL-9 in the complex pathogenesis of allergic inflammation.

Effect of glutathione aerosol on oxidant-antioxidant imbalance in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterised by alveolar inflammation, exaggerated release of oxidants, and subnormal concentrations of the antioxidant glutathione in respiratory epithelial lining fluid (ELF). Glutathione (600 mg twice daily for 3 days) was given by aerosol to 10 patients with IPF. Total ELF glutathione rose transiently, ELF oxidised glutathione concentrations increased, and there was a decrease in spontaneous superoxide anion release by alveolar macrophages. Thus, glutathione by aerosol could be a means of reversing the oxidant-antioxidant imbalance in IPF.

IL‐9 induces chemokine expression in lung epithelial cells and baseline airway eosinophilia in transgenic mice

Recent data have identified IL‐9 as a key cytokine in determining susceptibility to asthma. These data are supported by the finding that allergen‐exposed IL‐9‐transgenic mice exhibit many features that are characteristic of human asthma (airway eosinophilia, elevated serum IgE and bronchial hyperresponsiveness) as compared to the background strain. A striking feature of these animals is a robust peribronchial and perivascular eosinophilia after allergen challenge, suggesting that IL‐9 is a potent factor in regulating this process. In an attempt to gain insights into the molecular mechanism governing IL‐9 modulation of lung eosinophilia, we investigated the ability of this cytokine to induce the expression of CC‐type chemokines in the lung because of their effect on stimulating eosinophil chemotaxis. Here we show that IL‐9‐transgenic mice in contrast to their congenic controls exhibit baseline lung eosinophilia that is associated with the up‐regulation of CC‐chemokine expression in the airway. This effect appears to be through a direct action of IL‐9 because the addition of recombinant IL‐9 to primary epithelial cultures and cell lines induced the expression of these chemokines in vitro. These data support a mechanism for IL‐9 in regulating the expression of eosinophil chemotactic factors in lung epithelial cells.

Organ specific cytokine therapy. Local activation of mononuclear phagocytes by delivery of an aerosol of recombinant interferon-gamma to the human lung.

In the context of the central role of the alveolar macrophage in host defense of the respiratory epithelial surface, and the ability of IFN-gamma to activate mononuclear phagocytes, we have evaluated strategies to use rIFN-gamma to activate human alveolar macrophages in vivo. To accomplish this, rIFN-gamma was administered to nonsmoking normals, the amounts of IFN-gamma quantified in serum and respiratory epithelial lining fluid (ELF) and the status of IFN-gamma related activation of blood monocytes and alveolar macrophages was evaluated by quantifying the expression of mRNA transcripts of IP-10, a gene induced specifically by IFN-gamma. Systemic administration (subcutaneous) of maximally tolerated amounts of rIFN-gamma (250 micrograms) was followed by detectable levels of IFN-gamma in serum but not ELF, the expression of IP-10 transcripts in blood monocytes but not alveolar macrophages, and multiple systemic adverse effects. To circumvent the inability of systemic administration to reach respiratory ELF and activate alveolar macrophages, rIFN-gamma (250-1,000 micrograms) was inhaled as an aerosol once daily for 3 d. Strikingly, while IFN-gamma was not detected in serum it was detectable in respiratory ELF in a dose-dependent fashion. Further, alveolar macrophages, but not blood monocytes, expressed IP-10 mRNA transcripts and, importantly, inhalation of aerosolized rIFN-gamma was not associated with local or systemic adverse effects. Thus, it is feasible to use rIFN-gamma to activate alveolar macrophages by targeting the cytokine directly to the lung. These data suggest a potential strategy for targeted cytokine therapy, without systemic side effects, to augment respiratory tract defenses in individuals at risk for or with lung infection.

In vitro susceptibility to pexiganan of bacteria isolated from infected diabetic foot ulcers

During two clinical trials involving the treatment of 835 outpatients with infected diabetic foot ulcers, 2515 bacterial isolates, including 2337 aerobes and 178 anaerobes, were grown from cultures of the ulcers. The in vitro susceptibility of these isolates was determined to pexiganan, a peptide anti-infective evaluated in these clinical trials, and to other classes of antibiotics. Pexiganan demonstrated broad spectrum antimicrobial activity against Gram-positive and Gram-negative aerobes and anaerobes. The MIC90 values for the most common species among 1735 Gram-positive aerobes isolated, such as Staphylococcus aureus, coagulase-negative staphylococci, Group A streptococci, and Group B streptococci, were 16 micrograms/mL or less. Of 602 Gram-negative aerobes tested, the MIC90 values for pexiganan were 16 micrograms/mL or less for Acinetobacter, Pseudomonas, Stenotrophomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, and Flavobacterium species. Pexiganan had a MIC90 of 4 to 16 micrograms/mL against the anaerobic isolates of Bacteroides, Peptostreptococcus, Clostridium, and Prevotella species. Importantly, pexiganan did not exhibit cross-resistance with other commonly used antibiotics, including beta-lactams, quinolones, macrolides, and lincosamides. The broad spectrum in vitro antimicrobial activity of pexiganan against clinical isolates from infected diabetic foot ulcers supports its potential as a local therapy for infected diabetic foot ulcers.

Coronary artery revascularization before abdominal aortic aneurysm surgery : a decision analytic approach

Decision analysis is a method for quantitatively comparing the risks and benefits of diagnostic and therapeutic procedures, and for determining the influence of variation in a priori probabilities assigned to different outcomes. Therefore, we have constructed a decision tree to determine outcome probabilities between performing abdominal aortic surgery alone or to perform preoperative testing which may lead to coronary revascularization before noncardiac surgery. Sensitivity analyses were performed in which the assigned probabilities, obtained from the literature, were varied within a reported range to determine its influence on the optimal decision pathway. The optimal decision whether to perform preoperative testing and coronary revascularization prior to abdominal aortic reconstruction is dependent on both the mortality associated with coronary revascularization and the mortality of the surgical procedure performed without preoperative interventions. Within the range of mortality reported in the literature, strategies of either selective preoperative testing or no preoperative testing can be justified.