Modulation of the upper airway host defences to prevent pneumonia in ventilated patients. (360G-Wellcome-108768_Z_15_Z)

Ventilator-acquired pneumonia (VAP) is the commonest fatal hospital-acquired infection. It arises from colonisation of subglottic epithelium with pathogens that are micro-aspirated into the lung. Preventive strategies for VAP are significantly hampered by lack of a cellular model. My preliminary work generated human primary subglottic epithelial air-liquid interface cultures (SEALICs) for the first time. Hypotheses: -Increased mucin production by the subglottic epithelium of critically ill mechanically ventilated patients promotes growth of VAP pathogens and impairs neutrophil function. -Down-regulation of mucin expression reduces growth of VAP pathogens. -Phagocytosis of VAP pathogens can be promoted in subglottic epithelium by over-expression of phagocytic receptors. Experimental Phases: -Derive SEALICs from critically ill intensive care unit (ICU) patients; compare mucus composition and pathogen binding, in ICU patients and controls. -Isolate human neutrophils and apply these to purified human mucin. -Use a myristoylated alanine-rich C-kinase substrate (MARCKS) related peptide to reduce mucin expression in my SEALIC model -Transfect SEALICs with phagocytic receptor genes and assess whether this augments their capacity to ingest and kill bacteria. The research is therefore expected to -consolidate a unique model of VAP pathogenesis -suggest novel ways to prevent VAP -provide me with broad training as a clinician-scientist.