No abstract

Acid aspiration lung injury may be mediated primarily by neutrophils recruited to the lung by acid-induced cytokines. We hypothesized that a major acid-induced cytokine was

Sputum from patients with cystic fibrosis, bronchiectasis, and chronic bronchitis contains neutrophils and neutrophil proteases, which have been implicated in the pathophysiology of mucus hypersecretion in airways. We asked whether interleukin-8 (IL-8), a potent neutrophil chemoattractant, might be involved in recruiting neutrophils into airways of patients with cystic fibrosis, bronchiectasis, and chronic bronchitis. We found significant neutrophil chemotactic activity in sputum obtained from these patients. The IL-8 concentrations that we measured in sputum of patients with cystic fibrosis (7.1 +/- 1.0 x 10(-9) M, mean +/- SE), bronchiectasis (9.6 +/- 2.9 x 10(-9) M), and chronic bronchitis (2.8 +/- 1.0 x 10(-9) M) have been reported to cause significant chemotaxis in vitro and in airways in vivo, whereas concentrations measured in induced sputum from healthy subjects (1.1 +/- 0.3 x 10(-10) M) do not. A monoclonal antibody to IL-8 significantly inhibited the chemotactic activity in patients' sputum by 75-98%, but not in induced sputum from healthy subjects (9%). We conclude that IL-8 is an important chemotactic factor in sputum of patients with cystic fibrosis, bronchiectasis, and chronic bronchitis, and we suggest that IL-8 accounts, at least in part, for neutrophil recruitment into airways of patients with these diseases.

These findings support the premise that federal policies encouraging the meaningful use of EHRs may improve the quality of care across insurance types.

Chemokines play an important role in inflammation. The mechanism via which they bind to more than one receptor and activate them is not well understood. The chemokines are thought to interact with their receptors via two distinct sites, one necessary for binding and the other for activation of signal transduction. In this study we have used alanine scanning mutagenesis to identify residues on RANTES that specifically interact with its receptors CCR1, CCR3, and CCR5 for binding and activation. Residues within a potential receptor binding site known as the N-loop (residues 12-20) and near the N-terminus of RANTES were individually mutated to alanine. The results of this study show that, within the N-loop, the side chain of R17 is necessary for RANTES binding to CCR1, F12 for binding to CCR3, and F12 and I15 for binding to CCR5, thus forming distinct but overlapping binding epitopes. In addition, our finding that P2 is necessary for binding to CCR5 is the first to show that a residue near the N-terminus of a CC-chemokine is involved in binding to a receptor. We have also found that P2, D6, and T7 near the N-terminus are involved in activating signal transduction via CCR1, P2 and Y3 via CCR3, and Y3 and D6 via CCR5. These results indicate that RANTES interacts with each of its receptors in a distinct and specific manner and provide further evidence to support the two-site model of interaction between chemokines and their receptors.