Inhalation of 20 mu-g endotoxins (from the membrane of Gram-negative bacteria) has been reported to induce a bronchial obstructive response in asthmatic subjects. The aim of the present study was to evaluate in asthmatic patients the possibility of an inflammatory response to inhaled endotoxins. Eight patients with mild asthma were submitted to bronchial challenge tests, in a single-blind trial, on Day 1 with control solution and on Day 7 with 20 mug endotoxin of Escherichia coli (0.26:B6). Local inflammatory response was indirectly evaluated by the degree of bronchial hyperresponsiveness (BHR) expressed as PD20 FEV1 histamine (the dose of histamine inducing a 20% decrease in FEV1) at 0, 6, 24, and 48 h and 7 days. Systemic inflammation was investigated by sequential blood determinations of total (and differential) white cells, complement anaphylatoxin C5a, interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and C-reactive protein (CRP). A significant (p < 0.01) bronchial obstructive response was demonstrable 45 min after lipopolysaccharide (LPS) inhalation, lasting 5 h. Comparing the level of BHR after control inhalation, a significant (p < 0.05) increase in BHR was shown 6 h after LPS, partially normalized at 24 and 48 h. A short peak in TNF-alpha at 60 min (p < 0.05) and an increase in total while blood cells (p < 0.01) and neutrophil polymorphonuclear neutrophils at 360 min (p < 0.05) and of CRP at 24 and 48 h (p < 0.05 and p < 0.01) were significant. The other blood parameters did not change significantly. The present results suggest that, in asthmatic patients, bronchial obstructive response to 20 mug inhaled endotoxin could be associated with an inflammatory process.
