Systemic Inflammatory Response to CCRE

Purpose: The purpose of this study is to classify volunteers as endotoxin-responders or non-responders following inhalation of 20,000 EU Clinical Center Reference Endotoxin (CCRE). Endotoxin is a commonly encountered bioaerosol and component of indoor and outdoor air pollution. For reasons that remain unclear, some individuals appear to be more susceptible to the inflammatory effects of inhaled endotoxin than are others, possibly owing to single nucleotide polymorphisms in the Toll-like receptor 4 (TLR4) gene that influence TLR4 signaling and function. These susceptible individuals represent a population of particular interest for further mechanistic studies of the effects of endotoxin and for therapeutic trials. Susceptibility to inhaled endotoxin will be determined by measuring change in peripheral blood neutrophil counts, a biomarker of systemic inflammation, following inhaled CCRE. In our previous work, the investigators have found that inhalation of 20,000 EU CCRE is well tolerated and induces measurable increase in neutrophil content of peripheral blood in susceptible individuals. Our hope is that this CCRE inhalation protocol can be employed to screen large populations for susceptibility to the inflammatory effect of inhaled endotoxin.