Asthma is a common inflammatory disease that results in airway narrowing and wheezing and affects peopleof all ages (one in ten adults and one in four children). Mycoplasma pneumoniae is an important cause ofairway disorders, and a growing body of evidence implicates M. pneumoniae in the initiation, exacerbationand chronicity of asthma. However, the mechanisms by which M. pneumoniae infection leads to changes inpulmonary function and airway obstruction and hyper-reactivity are not understood. In addition, deficienciesin diagnosis of M. pneumoniae, plus the lack of known virulence determinants that can be directly linked toM. pneumon/ae-mediated pathologies handicap our current understanding of its true prevalence andpathogenic potential. Recently, we discovered a surfactant protein-A binding, ADP-ribosylating andvacuolating cytotoxin of M. pneumoniae (see Preliminary results) designated Community AcquiredRespiratory Distress Syndrome Toxin (CARDS TX). Recombinant CARDS TX by itself is capable ofreplicating the proinflammatory cytokine/chemokine responses, associated histopathology, and changes inairway hyper-responsiveness observed with M. pneumoniae infections (see Preliminary results of Projects1-3). In addition, results from ELISA and PCR assays implicate M. pneumoniae and CARDS TX in asthmadevelopment and progression (Projects 3 and 4). Considering these findings, we hypothesize that CARDSTX is responsible for acute, chronic, and exacerbation of M. pneumon/ae-mediated asthma. We furtherhypothesize that the presence and titer of antibodies reactive against CARDS TX and the frequency ofcards tx gene PCR positivity are key indicators of disease status. Also, the development of antigen (i.e.,CARDS TX) capture methodologies will further link CARDS TX to asthma and associated symptomatology.To test these hypotheses, we will: 1. Characterize CARDS TX-mediated ADP-ribosyl transferase (ART)activity through detecting CARDS TX minimal domain(s) and amino acids essential for enzymatic activity;and identify the mammalian proteins that are ADP-ribosylated by CARDS TX. 2. Perform transcriptional andproteomic analysis of CARDS TX in wild type strains and in M. pneumoniae strains having their CARDS TXpromoter fused to GFP and luciferase under different environmental conditions (in collaboration withProjects 1 and 2). 3. Map CARDS TX epitopes that serve as antigenic and diagnostic determinants inhumans (Project 3) and mice (Projects 1 and 2); and identify epitopes of CARDS TX capable of inducingneutralizing antibodies. We believe that this project is innovative and should lead to effective strategies tounderstand the role of M. pneumoniae infection and CARDS TX in asthma development and progression.Our long-term goal is to develop effective strategies to diagnose, treat and prevent asthma and relatedairway diseases in a substantial population of both children and adults.
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