Sameer K. Mathur

Reslizumab for Poorly Controlled, Eosinophilic Asthma: A Randomized, Placebo-controlled Study

RATIONALE Eosinophilic asthma is a phenotype of asthma characterized by the persistence of eosinophils in the airways. IL-5 is involved in the activation and survival of eosinophils. OBJECTIVES To evaluate the effect of the antibody to IL-5, reslizumab, in patients with eosinophilic asthma that is poorly controlled with high-dose inhaled corticosteroid. METHODS Patients were randomly assigned to receive infusions of reslizumab at 3.0 mg/kg (n = 53) or placebo (n = 53) at baseline and at Weeks 4, 8, and 12, with stratification by baseline Asthma Control Questionnaire (ACQ) score less than or equal to 2 or greater than 2. The primary efficacy measure was the difference between the reslizumab and placebo groups in the change in ACQ score from baseline to end of therapy (Week 15 or early withdrawal). MEASUREMENTS AND MAIN RESULTS Mean changes from baseline to end of therapy in ACQ score were -0.7 in the reslizumab group and -0.3 in the placebo group (P = 0.054) and in FEV(1) were 0.18 and -0.08 L, respectively (P = 0.002). In those patients with nasal polyps, the changes in ACQ score were -1.0 and -0.1, respectively (P = 0.012). Median percentage reductions from baseline in sputum eosinophils were 95.4 and 38.7%, respectively (P = 0.007). Eight percent of patients in the reslizumab group and 19% of patients in the placebo group had an asthma exacerbation (P = 0.083). The most common adverse events with reslizumab were nasopharyngitis, fatigue, and pharyngolaryngeal pain. CONCLUSIONS Patients receiving reslizumab showed significantly greater reductions in sputum eosinophils, improvements in airway function, and a trend toward greater asthma control than those receiving placebo. Reslizumab was generally well tolerated.

Heat shock response and protein degradation: regulation of HSF2 by the ubiquitin-proteasome pathway.

ABSTRACT Mammalian cells coexpress a family of heat shock factors (HSFs) whose activities are regulated by diverse stress conditions to coordinate the inducible expression of heat shock genes. Distinct from HSF1, which is expressed ubiquitously and activated by heat shock and other stresses that result in the appearance of nonnative proteins, the stress signal for HSF2 has not been identified. HSF2 activity has been associated with development and differentiation, and the activation properties of HSF2 have been characterized in hemin-treated human K562 erythroleukemia cells. Here, we demonstrate that a stress signal for HSF2 activation occurs when the ubiquitin-proteasome pathway is inhibited. HSF2 DNA-binding activity is induced upon exposure of mammalian cells to the proteasome inhibitors hemin, MG132, and lactacystin, and in the mouse ts85 cell line, which carries a temperature sensitivity mutation in the ubiquitin-activating enzyme (E1) upon shift to the nonpermissive temperature. HSF2 is labile, and its activation requires both continued protein synthesis and reduced degradation. The downstream effect of HSF2 activation by proteasome inhibitors is the induction of the same set of heat shock genes that are induced during heat shock by HSF1, thus revealing that HSF2 affords the cell with a novel heat shock gene-regulatory mechanism to respond to changes in the protein-degradative machinery.

Asthma in the elderly: Current understanding and future research needs—a report of a National Institute on Aging (NIA) workshop

Asthma in the elderly is underdiagnosed and undertreated, and there is a paucity of knowledge on the subject. The National Institute on Aging convened this workshop to identify what is known and what gaps in knowledge remain and suggest research directions needed to improve the understanding and care of asthma in the elderly. Asthma presenting at an advanced age often has similar clinical and physiologic consequences as seen with younger patients, but comorbid illnesses and the psychosocial effects of aging might affect the diagnosis, clinical presentation, and care of asthma in this population. At least 2 phenotypes exist among elderly patients with asthma; those with longstanding asthma have more severe airflow limitation and less complete reversibility than those with late-onset asthma. Many challenges exist in the recognition and treatment of asthma in the elderly. Furthermore, the pathophysiologic mechanisms of asthma in the elderly are likely to be different from those seen in young asthmatic patients, and these differences might influence the clinical course and outcomes of asthma in this population.

Stress-Specific Activation and Repression of Heat Shock Factors 1 and 2

ABSTRACT Vertebrate cells express a family of heat shock transcription factors (HSF1 to HSF4) that coordinate the inducible regulation of heat shock genes in response to diverse signals. HSF1 is potent and activated rapidly though transiently by heat shock, whereas HSF2 is a less active transcriptional regulator but can retain its DNA binding properties for extended periods. Consequently, the differential activation of HSF1 and HSF2 by various stresses may be critical for cells to survive repeated and diverse stress challenges and to provide a mechanism for more precise regulation of heat shock gene expression. Here we show, using a novel DNA binding and detection assay, that HSF1 and HSF2 are coactivated to different levels in response to a range of conditions that cause cell stress. Above a low basal activity of both HSFs, heat shock preferentially activates HSF1, whereas the amino acid analogue azetidine or the proteasome inhibitor MG132 coactivates both HSFs to different levels and hemin preferentially induces HSF2. Unexpectedly, we also found that heat shock has dramatic adverse effects on HSF2 that lead to its reversible inactivation coincident with relocalization from the nucleus. The reversible inactivation of HSF2 is specific to heat shock and does not occur with other stressors or in cells expressing high levels of heat shock proteins. These results reveal that HSF2 activity is negatively regulated by heat and suggest a role for heat shock proteins in the positive regulation of HSF2.

Age-related changes in immune function: Effect on airway inflammation

Immunosenescence is defined as changes in the innate and adaptive immune response associated with increased age. The clinical consequences of immunosenescence include increased susceptibility to infection, malignancy and autoimmunity, decreased response to vaccination, and impaired wound healing. However, there are several immune alterations that might facilitate persistence of asthma into late adulthood or development of asthma after the age of 50 to 60 years. Asthma in older patients is not uncommon, and this is a growing population as the average lifespan increases. Specific innate changes that might affect severity of asthma in older patients or be involved in the development of late-onset asthma include impaired mucociliary clearance and changes in airway neutrophil, eosinophil, and mast cell numbers and function. Additionally, age-related altered antigen presentation and decreased specific antibody responses might increase the risk of respiratory tract infections. Respiratory tract infections exacerbate asthma in older patients and possibly play a role in the pathogenesis of late-onset asthma. Furthermore, cytokine profiles might be modified with aging, with some investigators suggesting a trend toward T(H)2 cytokine expression. This review examines specific innate and adaptive immune responses affected by aging that might affect the inflammatory response in older adults with asthma.

Lower Airway Rhinovirus Burden and the Seasonal Risk of Asthma Exacerbation

RATIONALE Most asthma exacerbations are initiated by viral upper respiratory illnesses. It is unclear whether human rhinovirus (HRV)–induced exacerbations are associated with greater viral replication and neutrophilic inflammation compared with HRV colds. OBJECTIVES To evaluate viral strain and load in a prospective asthma cohort during a natural cold. METHODS Adults were enrolled at the first sign of a cold, with daily monitoring of symptoms, medication use, and peak expiratory flow rate until resolution. Serial nasal lavage and induced sputum samples were assessed for viral copy number and inflammatory cell counts. MEASUREMENTS AND MAIN RESULTS A total of 52 persons with asthma and 14 control subjects without atopy or asthma were studied for over 10 weeks per subject on average; 25 participants developed an asthma exacerbation. Detection of HRVs in the preceding 5 days was the most common attributable exposure related to exacerbation. Compared with other infections, those by a minor group A HRV were 4.4- fold more likely to cause exacerbation (P = 0.038). Overall, sputum neutrophils and the burden of rhinovirus in the lower airway were similar in control subjects without atopy and the asthma group. However, among HRV-infected participants with asthma, exacerbations were associated with greater sputum neutrophil counts (P = 0.005). CONCLUSIONS HRV infection is a frequent cause of exacerbations in adults with asthma and a cold, and there may be group-specific differences in severity of these events. The absence of large differences in viral burden among groups suggests differential lower airway sensitization to the effects of neutrophilic inflammation in the patients having exacerbations.

Human airway and peripheral blood eosinophils enhance Th1 and Th2 cytokine secretion

Background:  The effector function of eosinophils involves their release of toxic granule proteins, reactive oxygen species, cytokines, and lipid mediators. Murine studies have demonstrated that eosinophils can also enhance T cell function. Whether human eosinophils, in particular, airway eosinophils, have similar immunoregulatory activity has not been fully investigated. The aim of this study was to determine whether human blood and airway eosinophils can contribute to Th1 and Th2 cytokine generation from CD4+ T cells stimulated with superantigen.

Characterizing asthma from a drop of blood using neutrophil chemotaxis

Significance Asthma is a chronic inflammatory disorder that is notoriously difficult to diagnose, characterize, and properly treat with tests that are available to clinicians today. Therefore, clinicians would benefit from additional tools that objectively characterize asthma in patients. In this work, we describe a handheld microfluidic device that discriminates asthma from allergic rhinitis patients based on neutrophil function—an inflammatory cell that has been implicated in the pathogenesis of asthma. The device can sort neutrophils from a drop of whole blood within minutes, and was used in a clinical setting to characterize asthmatic and nonasthmatic patients. This technology provides a new tool for clinicians to characterize asthma based on cellular function. Asthma is a chronic inflammatory disorder that affects more than 300 million people worldwide. Asthma management would benefit from additional tools that establish biomarkers to identify phenotypes of asthma. We present a microfluidic solution that discriminates asthma from allergic rhinitis based on a patient’s neutrophil chemotactic function. The handheld diagnostic device sorts neutrophils from whole blood within 5 min, and generates a gradient of chemoattractant in the microchannels by placing a lid with chemoattractant onto the base of the device. This technology was used in a clinical setting to assay 34 asthmatic (n = 23) and nonasthmatic, allergic rhinitis (n = 11) patients to establish domains for asthma diagnosis based on neutrophil chemotaxis. We determined that neutrophils from asthmatic patients migrate significantly more slowly toward the chemoattractant compared with nonasthmatic patients (P = 0.002). Analysis of the receiver operator characteristics of the patient data revealed that using a chemotaxis velocity of 1.55 μm/min for asthma yields a diagnostic sensitivity and specificity of 96% and 73%, respectively. This study identifies neutrophil chemotaxis velocity as a potential biomarker for asthma, and we demonstrate a microfluidic technology that was used in a clinical setting to perform these measurements.

Airway neutrophil inflammatory phenotype in older subjects with asthma

Asthma in the elderly has been inadequately studied. The age demographic >65 years old is the fastest growing in the United States, and asthma in the elderly population is frequently underdiagnosed and undertreated(1). Furthermore, elderly asthmatics also have a higher rate of severe exacerbations, emergency department visits, and hospitalizations than younger asthmatics which represents significant disease impairment and risk(2). The airway inflammation in older asthma subjects differs from younger patients, which suggests that the phenotype of asthma in older asthmatics may be different. An understanding of this phenotype of asthma will be important for the diagnosis of the disease, determining optimal therapies, and improvement in the morbidity and mortality in the growing elderly asthmatic population.

Identification of Genes Expressed by Human Airway Eosinophils after an In Vivo Allergen Challenge

Background The mechanism for the contribution of eosinophils (EOS) to asthma pathophysiology is not fully understood. Genome-wide expression analysis of airway EOS by microarrays has been limited by the ability to generate high quality RNA from sufficient numbers of airway EOS. Objective To identify, by genome-wide expression analyses, a compendium of expressed genes characteristic of airway EOS following an in vivo allergen challenge. Methods Atopic, mild asthmatic subjects were recruited for these studies. Induced sputum was obtained before and 48h after a whole lung allergen challenge (WLAC). Individuals also received a segmental bronchoprovocation with allergen (SBP-Ag) 1 month before and after administering a single dose of mepolizumab (anti-IL-5 monoclonal antibody) to reduce airway EOS. Bronchoalveolar lavage (BAL) was performed before and 48 h after SBP-Ag. Gene expression of sputum and BAL cells was analyzed by microarrays. The results were validated by qPCR in BAL cells and purified BAL EOS. Results A total of 299 transcripts were up-regulated by more than 2-fold in total BAL cells following SBP-Ag. Mepolizumab treatment resulted in a reduction of airway EOS by 54.5% and decreased expression of 99 of the 299 transcripts. 3 of 6 post-WLAC sputum samples showed increased expression of EOS-specific genes, along with the expression of 361 other genes. Finally, the intersection of the 3 groups of transcripts (increased in BAL post SBP-Ag (299), decreased after mepolizumab (99), and increased in sputum after WLAC (365)) was composed of 57 genes characterizing airway EOS gene expression. Conclusion We identified 57 genes that were highly expressed by BAL EOS compared to unseparated BAL cells after in vivo allergen challenge. 41 of these genes had not been previously described in EOS and are thus potential new candidates to elucidate EOS contribution to airway biology.