Biomarkers of Irritant-Induced and Allergic Asthma

Overview

Asthma is a heterogeneous disease, and although much is understood about mechanisms of inflammation in allergic asthma, less is known about mechanisms of irritant-induced asthma (IA). Understanding the underlying similarities and differences in mechanisms of these two types of asthma will help focus current treatments and lead to development of new therapies. There is a longstanding NYU/Bellevue Asthma registry (NYUBAR), with a large population (N = 900) of asthma cases and controls, a program that has been housed at the CTSI (formerly GCRC). The destruction of the World Trade Center (WTC) resulted in massive dust, gas and fume exposures to local residents, workers and cleanup workers and individuals involved in rescue and recovery and adverse respiratory health effects of this disaster are reported more than 7 years after 9/11. Many responders, as well as those exposed as residents or local workers, have developed IA, asthma that arises after a lag from an environmental exposure . The WTC Environmental Health Center (WTC EHC) is one of the three New York City (NYC) WTC Centers of Excellence and the only one that focuses on treatment and monitoring of local workers and residents. As such, it has a large population of individuals with irritant-induced asthma. It has been proposed to use participants from the NYUBAR and the WTC EHC to expand the knowledge of irritant and allergic asthma. Non-invasive studies allow for the assessment of airway inflammation, a non-specific response to environmental exposure and injury. Recent technologies also allow for assessment of microRNA (miRNA), small RNAs that regulate gene expression at the post-transcriptional level and thus serve as a pathway to regulation of inflammation. The hypothesis will be tested in that airway inflammation in irritant and allergic asthma may be similar, but result from divergent miRNA regulatory pathways expressed in sputum cells. These studies will provide preliminary data for future studies that will help identify biological pathways to categorize these asthma phenotypes and target future treatment interventions.

This study will have two asthma phenotypes and one control population. Patients will be recruited from the WTC EHC = 30 with WTC dust cloud exposure, patients will be recruited from the NYUBAR (n=30) and have asthma as defined by NIH guidelines, and control patients will be recruited from the NYUBAR (n=30) and will have no respiratory sx, no asthma diagnosis, or no WTC dust exposure. The study will entail two to three visits. On visit 1 (V1) all individuals will sign informed consent to participate in the study under an NYU IRB approved protocol. A questionnaire will be completed with standardized questions that include information on WTC exposures, demographics, presence and severity of respiratory symptoms, tobacco history and past medical history. Individuals will undergo spirometry with inhaled bronchodilator. Individuals will undergo methacholine challenge test (visit 1a) if they have normal spirometry or no bronchial hyperresponsiveness. On visit 2, individuals will return to undergo ENO, EBC and spirometry with pre and post bronchodilator maneuvers and induced sputum. Blood will be obtained for CBC with differential cell count, and assessment of total IgE and allergen-specific IgE. Blood will also be stored for future analysis of inflammatory markers. Based on experience, there have been individuals unable to produce enough sputum and thus yield too small a number of cells. These individuals are excluded from data analysis. In addition, there will also be subjects who are able to produce sputum and return for repeat sputum testing.