Pediatric Respiratory Infections - Pathogenesis of Bronchiolitis

A. Focus group


Bronchiolitis, the major cause of hospitalization in the first year of life is primarily caused by respiratory syncytial virus (RSV) infections. Exposure to second hand tobacco smoke (SHTS) occurs in up to 60% of the infants with RSV bronchiolitis in the US, and different studies have suggested that SHTS is a risk factor for the development of severe RSV infection. Oxidative stress response in the airways plays a major role in the pathogenesis of severe RSV bronchiolitis particularly if the process is enhanced by the exposure to pro-oxidative toxicants such as tobacco smoke.


B. Areas of investigation

  • Biomarkers and predictors of viral bronchiolitis and pneumonia
  • Innate immune response in the lung
  • Oxidative injury, antioxidant gene regulation and gene polymorphism
  • Second hand tobacco smoke exposure as co-factor of disease severity

C. ICTSA pilot project


We have recently discovered that RSV potently inhibits the expression of antioxidant genes in epithelial cells. We hypothesize that combination of SHTS-induced reactive oxygen species (ROS) and virus-mediated inhibition of antioxidant enzymes leads to severe manifestations of bronchiolitis. Moreover, we hypothesize that the effect of SHTS on severity of RSV infection is linked to certain GST genotypes, such as the GST M1 null genotype which are associated with a complete lack of the enzyme. In this pilot project we will obtain nasopharyngeal secretions (NPS) from infants during the acute phase of naturally-acquired RSV infection. GST genotypes will be performed from NPS cell DNA. NPS samples will be tested for a panel of oxidative stress markers and cytokines which are associated with innate and inflammatory responses. To assess exposure to SHTS, levels of cotinine will be measured in urine of RSV-infected infants. Overall, these studies may lead to the identification of novel biomarker predictors of respiratory infection progression and disease severity and to the design of anti-oxidative pharmacologic interventions for the treatment of viral respiratory infections.


D. Impact and Innovation of ICTSA pilot project


Work proposed in this pilot application, in particular aggressive recruitment of viral-infected infants, assessment of second hand smoke exposure and characterization of GST genotype/innate immune responses in this population will be critical for the competitiveness of several grant applications, which are going to be submitted by members of our clinical pediatric team, including:

  1. NIH R01 – "Genetics and environmental determinants of viral bronchiolitis" – Garofalo/Casola/Brasier – to be submitted as new application on/after February 2009.
  2. NIH P01 – "Signaling in Airway Inflammation" Brasier/Garofalo/Casola/Sur/Boldogh – to be submitted as competitive renewal, on February 2010 (two out of five projects will need clinical data from this RSV-infected population).
  3. Thrasher Research Fund Clinical Translational Grant in Pediatric Research – "NRF2 controls oxidative responses in viral bronchiolitis" – Casola/Garofalo/Xiaoyong - to be submitted within the next six months (open deadlines) as new application (were invited to submit after preliminary abstract submission).
  4. Medimmune Fellowship – Gallite-Esham/Garofalo – Funded – Will support salary of Dr. Gallite-Esham for 1 year during her clinical fellowship in AI.
  5. NIEHS Center Competing Renewal – Major (programmatic) component of clinical and translational research will come from the Integrated Health Research Core and will be focused around the environmental and genetic aspects of the oxidative response that affects the severity of viral respiratory infection.
  6. NHLBI Clinical Proteomics Centers – NHLBI is currently preparing to issue a RFA for the establishment of (few) Clinical Proteomics Centers, possibly associated to those currently existing, such as the one at UTMB. The RSV program, which is a major component of the current UTMB Proteomics Center at UTMB, represents a strength of our protein discovery work and an obvious central theme of a competitive submission of a Clinical Center – Thus the need for more preliminary data in infants.


We believe that our project present a number of innovative aspects that link basic discoveries we have made over the past 15 years to the pathogenesis of viral bronchiolitis in infants. Finally, a major focus of our studies in viral respiratory infections is the discovery of biomarkers that can be used to predict disease progression from milder upper respiratory infections to bronchiolitis and to optimize pharmacologic interventions. There is major emphasis at NIH on biomarker discovery.


E. CTSA Key Resource Involvement


We anticipate need for the following CTSA Key Resources: 1. Bioinformatics: will be used for pattern recognition of cytokine, innate molecule/biomarkers, and antioxidant gene expression patterns; 2 Biostatistics: will be used to develop a web page for clinical data collection and primary statistical analysis; 3. CRC: our study protocol has been approved by the CRC committee and we anticipate that we will need CRC ancillary support for follow-up visits and collection of NPS convalescence samples; 4. Translational technologies: while the initial analysis of SNPs for GST will be performed in the PI's laboratory, we will engage expertise from this key resource for analysis of additional antioxidant gene polymorphisms by genomic array technologies. In addition, we will consider at a later point to set up a repository of NPS samples.


F. Milestones and Timeline of pilot project


Year 1. November 2008: recruit a clinical research coordinator; 2. November 2008-March 2009: enroll ~ 80 infants with different clinical forms of RSV infection (~ 50 bronchiolitis, 20 URTI); April-June 2009: measure mediators in NPS and test urine for cotinine levels, run PCR for GST; July 2009-October 2009: perform statistical analysis; submit abstract to IDSA. Year 2. Refine the enrollment process, recruit 100 infants with RSV-proven infection.


G. Members of MTT Pediatric Respiratory Infections – Pathogenesis of bronchiolitis (collaborative NIH-funded projects)

  • Roberto Garofalo, M.D., Clinical and Experimental Immunology and Infectious Disease (CEIID)
  • Antonella Casola, M.D., Pediatric Infectious Disease
  • Bao Xiaoyong, Ph.D. (CEIID)
  • Alex Kurosky, Ph.D. (BMB)
  • Krishna Rajarathnam, Ph.D. (BMB)
  • Allan Brasier, M.D. (Medicine)
  • Mira Gupta, M.D. (Medicine and Pediatrics)
  • Reena Mehta, M.D. (Pediatrics)
  • Dana Esham, M.D. (Pediatrics)

New Investigators:

  • Bao Xiaoyong, Ph.D. (Assistant Professor, CRISP, K22, American Heart, Parker fellowship)
  • Mira Gupta, M.D. (Assistant Professor, CRISP, CTSA faculty development award applicant)
  • Deepthi Kolli, Ph.D. (Instructor)


In training:

  • Dana Esham, M.D. (AI clinical fellow, Medimmune)