Modulation of Steroid Immunosuppression by Alveolar Efferocytosis

Treating chronic obstructive pulmonary disease (COPD) patients with inhaled glucocorticosteroids has been convincingly shown to increase their risk of pneumonia, but the responsible mechanisms are undefined. Work from this laboratory suggests a possible mechanism, related to the increased numbers of cells dying by apoptosis in the lungs in COPD, especially in emphysema. Uptake of apoptotic cells ("efferocytosis") suppresses the ability of alveolar macrophages (AM) to fight infections. By markedly increasing AM efferocytosis, glucocorticoids plus apoptotic cells cause greater immune defects than either stimulus alone. These defects include reductions in killing of Streptococcus pneumoniae by human AM and murine AM in vitro, and in clearance of viable pneumococci from lungs of mice. This effect is called glucocorticoid augmented efferocytosis (GCAE). MicroRNAs (miRNAs) are 19-25 nucleotide-long non-coding RNAs that coordinately target large numbers of genes and reduce their protein products. Preliminary data imply that defective AM function is caused by down-regulation of specific miRNAs by GCAE (but not by apoptotic cells alone or glucocorticosteroids alone). The long-term goal of this project is to develop novel inhalational treatments based on transient over-expression of these specifically decreased miRNAs, to reverse defective AM immune function when COPD patients taking inhaled glucocorticoids present with community-acquired pneumonia. This project will use both ex vivo investigation of AM from human volunteers (never-smokers; smokers with normal spirometry; and COPD subjects who are current or former smokers), and an established murine model of pneumococcal pneumonia. Its immediate goals are to: (a) confirm that GCAE increases pneumococcal pneumonia risk and severity, and in the process, validate a murine model for testing strategies to reverse those defects; (b) define GCAE-induced AM defects functionally and by whole-transcriptome analysis, identifying genes and miRNAs uniquely regulated by the GCAE x pneumococcus interaction; (c) validate and optimize miRNA-over-expression to reverse the adverse effects of GCAE on AM defensive functions. Successful completion of this project could lead to more precisely personalized therapies and better outcomes in COPD, currently the third leading cause of death in the USA

Inclusion criteria

• Inclusion Criteria for healthy subjects without COPD:
• Age 18-80 years, inclusive
• Males or females
• Never smoker (< 100 cigarettes in lifetime)

• OR
• Current smoker (>10 pack-years) with normal spirometry
• Able to perform satisfactory spirometry
• Abe to give informed consent
• Able to complete questionnaires
• Inclusion Criteria for COPD subjects:
• Age 18-80 years, inclusive
• Males or females
• Current smoker

• (>10 pack-years) & (≥1/2 pack/day)

• OR
• Former smoker

• (>10 pack-years) & (>6 months of non-smoking)
• Diagnosis of COPD by ATS/ERS1 criteria
• Able to perform satisfactory spirometry
• Able to give informed consent
• Able to complete questionnaires
• 1 ATS/ERS, American Thoracic Society/European Respiratory Society.

Exclusion criteria

• Exclusion Criteria for healthy subjects without COPD:
• Unstable cardiovascular disease, including uncontrolled hypertension, CHF, angina
• Significant renal (creatinine >2.5) or hepatic dysfunction (Childs B or C)
• Mental incompetence/active psychiatric illness
• Prednisone or other immunosuppressive medications
• Participation in another interventional experimental protocol within 6 weeks
• Pregnancy
• Use of antibiotics for any reason within 42 days
• Judged to be unsuitable for bronchoscopy by PI
• Resting SaO2<93%
• FEV1 < 70% predicted
• Respiratory infections within 42 days regardless of antibiotic use
• Diagnosed COPD or Asthma
• Use of inhaled corticosteroids
• Active pulmonary tuberculosis or other serious chronic respiratory infection
• Diffuse panbronchiolitis or Cystic fibrosis
• Clinically significant bronchiectasis
• History of thoracic radiation therapy for any cause
• Other inflammatory or fibrotic lung disease
• Exclusion Criteria for COPD subjects:
• Unstable cardiovascular disease, including uncontrolled hypertension, CHF, angina
• Significant renal (creatinine >2.5) or hepatic dysfunction (Childs B or C)
• Mental incompetence/active psychiatric illness
• Prednisone or other immunosuppressive medications
• Participation in another interventional experimental protocol within 6 weeks
• Pregnancy
• Use of antibiotics for any reason within 42 days
• Judged to be unsuitable for bronchoscopy by PI
• Resting daytime SaO2<90% while breathing room air
• FEV1 < 50% predicted
• Respiratory infections within 42 days regardless of antibiotic use
• Use of inhaled corticosteroids
• Active pulmonary tuberculosis or other serious chronic respiratory infection
• Diffuse panbronchiolitis or Cystic fibrosis
• Clinically significant bronchiectasis
• History of thoracic radiation therapy for any cause
• Other inflammatory or fibrotic lung disease