Mani S. Kavuru

A prospective evaluation of esophageal testing and a double-blind, randomized study of omeprazole in a diagnostic and therapeutic algorithm for chronic cough

Objective:Recent studies suggest an association between chronic cough and gastroesophageal reflux. Our study aims were 1) to define the prevalence of acid reflux induced cough in the general community, 2) to examine the ability of esophageal testing to identify gastroesophageal reflux related cough, and 3) to assess the utility of omeprazole in a chronic cough algorithm.Methods:Patients with chronic cough of unknown etiology, who were mostly from the community, were evaluated. Subjects underwent a chest x-ray, methacholine challenge test, and empiric trial of postnasal drip therapy, and completed daily cough symptom diaries subjectively evaluating cough frequency and severity on a graded scale of 0–4 (combined maximum 8). After excluding other causes of cough, the remaining patients underwent esophageal and pH testing. Those testing positive were randomized to omeprazole 40 mg b.i.d. or placebo for 12 weeks. Follow-up was 1 yr.Results:A total of 71 patients were screened; 48 were excluded. Twenty-three patients were evaluated for gastroesophageal reflux disease; six (26%) were eventually determined to have an acid-related cough. Of these patients, 17 had a positive pH test, six (35%) of whom showed a striking improvement or resolution of their cough during omeprazole treatment which was sustained for up to 1 yr. Six had a negative pH test, none of whom responded to omeprazole therapy. No significant differences were seen between responders (n = 6) and nonresponders (n = 11) for demographic factors, baseline symptom frequency and duration, or physiological parameters (motility/pH).Conclusions:Acid-related chronic cough was present in 26% (six of 23) of patients evaluated for gastroesophageal reflux disease. Esophageal testing does not reliably identify patients with acid induced chronic cough responsive to proton pump inhibitor therapy. We suggest that the best diagnostic and therapeutic approach, after excluding asthma and postnasal drip syndrome, is empiric treatment for 2 wk with a high dose proton pump inhibitor.

Eosinophils Are a Major Source of Nitric Oxide-Derived Oxidants in Severe Asthma: Characterization of Pathways Available to Eosinophils for Generating Reactive Nitrogen Species

Eosinophil recruitment and enhanced production of NO are characteristic features of asthma. However, neither the ability of eosinophils to generate NO-derived oxidants nor their role in nitration of targets during asthma is established. Using gas chromatography-mass spectrometry we demonstrate a 10-fold increase in 3-nitrotyrosine (NO2Y) content, a global marker of protein modification by reactive nitrogen species, in proteins recovered from bronchoalveolar lavage of severe asthmatic patients (480 ± 198 μmol/mol tyrosine; n = 11) compared with nonasthmatic subjects (52.5 ± 40.7 μmol/mol tyrosine; n = 12). Parallel gas chromatography-mass spectrometry analyses of bronchoalveolar lavage proteins for 3-bromotyrosine (BrY) and 3-chlorotyrosine (ClY), selective markers of eosinophil peroxidase (EPO)- and myeloperoxidase-catalyzed oxidation, respectively, demonstrated a dramatic preferential formation of BrY in asthmatic (1093 ± 457 μmol BrY/mol tyrosine; 161 ± 88 μmol ClY/mol tyrosine; n = 11 each) compared with nonasthmatic subjects (13 ± 14.5 μmol BrY/mol tyrosine; 65 ± 69 μmol ClY/mol tyrosine; n = 12 each). Bronchial tissue from individuals who died of asthma demonstrated the most intense anti-NO2Y immunostaining in epitopes that colocalized with eosinophils. Although eosinophils from normal subjects failed to generate detectable levels of NO, NO2−, NO3−, or NO2Y, tyrosine nitration was promoted by eosinophils activated either in the presence of physiological levels of NO2− or an exogenous NO source. At low, but not high (e.g., >2 μM/min), rates of NO flux, EPO inhibitors and catalase markedly attenuated aromatic nitration. These results identify eosinophils as a major source of oxidants during asthma. They also demonstrate that eosinophils use distinct mechanisms for generating NO-derived oxidants and identify EPO as an enzymatic source of nitrating intermediates in eosinophils.

NO chemical events in the human airway during the immediate and late antigen-induced asthmatic response

A wealth of evidence supports increased NO (NO⋅) in asthma, but its roles are unknown. To investigate how NO participates in inflammatory airway events in asthma, we measured NO⋅ and NO⋅ chemical reaction products [nitrite, nitrate, S-nitrosothiols (SNO), and nitrotyrosine] before, immediately and 48 h after bronchoscopic antigen (Ag) challenge of the peripheral airways in atopic asthmatic individuals and nonatopic healthy controls. Strikingly, NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} was the only NO⋅ derivative to increase during the immediate Ag-induced asthmatic response and continued to increase over 2-fold at 48 h after Ag challenge in contrast to controls [P < 0.05]. NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{-}}}\end{equation*}\end{document} was not affected by Ag challenge at 10 min or 48 h after Ag challenge. Although SNO was not detectable in asthmatic airways at baseline or immediately after Ag, SNO increased during the late response to levels found in healthy controls. A model of NO⋅ dynamics derived from the current findings predicts that NO⋅ may have harmful effects through formation of peroxynitrite, but also subserves an antioxidant role by consuming reactive oxygen species during the immediate asthmatic response, whereas nitrosylation during the late asthmatic response generates SNO, safe reservoirs for removal of toxic NO⋅ derivatives.

Efficacy of infliximab in extrapulmonary sarcoidosis: results from a randomised trial

The aim of the present study was to investigate the efficacy of infliximab for the treatment of extrapulmonary sarcoidosis. A prospective, randomised, double-blind, placebo-controlled trial was conducted, with infliximab at 3 and 5 mg·kg−1 body weight administered over 24 weeks. Extrapulmonary organ severity was determined by a novel severity tool (extrapulmonary physician organ severity tool; ePOST) with an adjustment for the number of organs involved (ePOSTadj). In total, 138 patients enrolled in the trial of infliximab versus placebo for the treatment of chronic corticosteroid-dependent pulmonary sarcoidosis. The baseline severity of extrapulmonary organ involvement, as measured by ePOST, was similar across treatment groups. After 24 weeks of drug-therapy study, the change from baseline to week 24 in ePOST was greater for the combined infliximab group compared with the placebo group. After adjustment for the number of extrapulmonary organs involved, the improvement in ePOSTadj observed in the combined infliximab group was also greater than that observed in placebo-treated patients, after 24 weeks of therapy. The improvements in ePOST and ePOSTadj were not maintained during a subsequent 24-week washout period. Infliximab may be beneficial compared with placebo in the treatment of extrapulmonary sarcoidosis in patients already receiving corticosteroids, as assessed by the severity tool described in the present study.

Rapid loss of superoxide dismutase activity during antigen-induced asthmatic response.

Loss of superoxide dismutase activity occurs within minutes of an acute asthmatic response to segmental antigen instillation into the lung of individuals with atopic asthma. Decreased activity undoubtedly contributes to airway inflammation and injury through increased formation of reactive oxygen and nitrogen species, and suggests that enrichment of lung antioxidants is therapeutic for asthma.

Differential Proteomic Analysis of Bronchoalveolar Lavage Fluid in Asthmatics following Segmental Antigen Challenge

Allergic asthma is characterized by persistent airway inflammation and remodeling. Bronchoalveolar lavage conducted with fiberoptic bronchoscopy has been widely used for investigating the pathogenesis of asthma and other lung disorders. Identification of proteins in the bronchoalveolar lavage fluid (BALF) and their expression changes at different stages of asthma could provide further insights into the complex molecular mechanisms involved in this disease. In this report, we describe the first comprehensive differential proteomic analysis of BALF from both asthmatic patients and healthy subjects before and 24 h after segmental allergen challenge. Our proteomic analysis involves affinity depletion of six abundant BALF proteins, SDS-PAGE fractionation, protein in-gel digestion, and subsequent nano-LC-MS/MS analysis in conjunction with database searching for protein identification and semiquantitation. More than 1,500 distinct proteins were identified of which about 10% displayed significant up-regulation specific to the asthmatic patients after segmental allergen challenge. The differentially expressed proteins represent a wide spectrum of functional classes such as chemokines, cytokines, proteases, complement factors, acute phase proteins, monocyte-specific granule proteins, and local matrix proteins, etc. The majority of these protein expression changes are closely associated with many aspects of the pathophysiology of asthma, including inflammation, eosinophilia, airway remodeling, tissue damage and repair, mucus production, and plasma infiltration. Importantly a large portion of these proteins and their expression changes were identified for the first time from BALF, thus providing new insights for finding novel pathological mediators and biomarkers of asthma.

Genome-wide search for sarcoidosis susceptibility genes in African Americans

Sarcoidosis, a systemic granulomatous disease of unknown etiology, likely results from an environmental insult in a genetically susceptible host. In the US, African Americans are more commonly affected with sarcoidosis and suffer greater morbidity than Caucasians. We searched for sarcoidosis susceptibility loci by conducting a genome-wide, sib pair multipoint linkage analysis in 229 African-American families ascertained through two or more sibs with a history of sarcoidosis. Using the Haseman–Elston regression technique, linkage peaks with P-values less than 0.05 were identified on chromosomes 1p22, 2p25, 5p15-13, 5q11, 5q35, 9q34, 11p15 and 20q13 with the most prominent peak at D5S2500 on chromosome 5q11 (P=0.0005). We found agreement for linkage with the previously reported genome scan of a German population at chromosomes 1p and 9q. Based on the multiple suggestive regions for linkage found in our study population, it is likely that more than one gene influences sarcoidosis susceptibility in African Americans. Fine mapping of the linked regions, particularly on chromosome 5q, should help to refine linkage signals and guide further sarcoidosis candidate gene investigation.

Deletion of PPARγ in Alveolar Macrophages Is Associated with a Th-1 Pulmonary Inflammatory Response

Peroxisome proliferator-activated receptor γ (PPARγ) is constitutively expressed at high levels in healthy alveolar macrophages, in contrast to other tissue macrophages and blood monocytes. PPARγ ligands have been shown to down-regulate IFN-γ-stimulated inducible NO synthase (iNOS) in macrophages. Because NO is an important inflammatory mediator in the lung, we hypothesized that deletion of alveolar macrophage PPARγ in vivo would result in up-regulation of iNOS and other inflammatory mediators. The loss of PPARγ in macrophages was achieved by crossing floxed (+/+) PPARγ mice and a transgenic mouse containing the CRE recombinase gene under the control of the murine M lysozyme promoter (PPARγKO). Alveolar macrophages were harvested by bronchoalveolar lavage (BAL). Lymphocytes (CD8:CD4 ratio = 2.8) were increased in BAL of PPARγKO vs wild-type C57BL6; p ≤ 0.0001. Both iNOS and IFN-γ expression were significantly elevated (p ≤ 0.05) in BAL cells. Th-1 associated cytokines including IL-12 (p40), MIP-1α (CCL3), and IFN inducible protein-10 (IP-10, CXCL10) were also elevated. IL-4 and IL-17A were not detected. To test whether these alterations were due to the lack of PPARγ, PPARγ KO mice were intratracheally inoculated with a PPARγ lentivirus construct. PPARγ transduction resulted in significantly decreased iNOS and IFN-γ mRNA expression, as well as reduced BAL lymphocytes. These results suggest that lack of PPARγ in alveolar macrophages disrupts lung homeostasis and results in a Th1-like inflammatory response.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis is a rare syndrome characterized by intra-alveolar accumulation of surfactant components and cellular debris, with minimal interstitial inflammation or fibrosis. The condition has a variable clinical course, from spontaneous resolution to respiratory failure and death due to disease progression or superimposed infections. The standard of care for alveolor proteinosis therapy is represented by whole lung lavage. Important discoveries have been made in the last decade with respect to disease pathogenesis and therapy of both congenital and acquired forms of the disease. Granulocyte-macrophage colony-stimulating factor (GM-CSF) pathway has been shown to be involved in the disease pathogenesis of both acquired and congenital disease. Furthermore, anti-GMCSF blocking autoantibodies have been found in the serum and bronchoalveolar lavage fluid and seem to interfere with the surfactant clearance by alveolar macrophages in many acquired cases. In the congenital form, the most common defects identified to date are several mutations of the genes encoding GM-CSF receptor subunits or surfactant proteins. Using GM-CSF as a therapeutic tool has also been shown to be effective in at least half of the acquired cases treated, while the importance of quantitative determination of anti-GM-CSF antibodies before and during the course of the therapy, as well as the autoantibody titer-GM-CSF dose relationship are to be elucidated. The congenital form of the disease does not respond to therapy with GM-CSF, consistent with the known primary defects and differences in disease pathogenesis.

ABCG1 is deficient in alveolar macrophages of GM-CSF knockout mice and patients with pulmonary alveolar proteinosis

Patients with pulmonary alveolar proteinosis (PAP) display impaired surfactant clearance, foamy, lipid-filled alveolar macrophages, and increased cholesterol metabolites within the lung. Neutralizing autoantibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF) are also present, resulting in virtual GM-CSF deficiency. We investigated ABCG1 and ABCA1 expression in alveolar macrophages of PAP patients and GM-CSF knockout (KO) mice, which exhibit PAP-like pulmonary pathology and increased pulmonary cholesterol. Alveolar macrophages from both sources displayed a striking similarity in transporter gene dysregulation, consisting of deficient ABCG1 accompanied by highly increased ABCA1. Peroxisome proliferator-activated receptor γ (PPARγ), a known regulator of both transporters, was deficient, as reported previously. In contrast, the liver X receptor α, which also upregulates both transporters, was highly increased. GM-CSF treatment increased ABCG1 expression in macrophages in vitro and in PAP patients in vivo. Overexpression of PPARγ by lentivirus-PPARγ transduction of primary alveolar macrophages, or activation by rosiglitazone, also increased ABCG1 expression. These results suggest that ABCG1 deficiency in PAP and GM-CSF KO alveolar macrophages is attributable to the absence of a GM-CSF-mediated PPARγ pathway. These findings document the existence of ABCG1 deficiency in human lung disease and highlight a critical role for ABCG1 in surfactant homeostasis.