Intratracheal E. coli lipopolysaccharide induces platelet-dependent bronchial hyperreactivity

Area of Science:

• Pulmonary immunology
• Respiratory physiology

Background:

• Bronchial hyperresponsiveness (BHR) is a hallmark of asthma and is associated with respiratory infections.
• Endotoxin (lipopolysaccharide, LPS) has complex effects on airway responsiveness and anaphylaxis.

Purpose of the Study:

• To investigate the role of platelets and leukocytes in LPS-induced BHR in guinea pigs.
• To compare the effects of LPS on airway responsiveness in sensitized versus nonsensitized animals.

Main Methods:

• Intratracheal administration of Escherichia coli LPS to guinea pigs.
• Assessment of bronchopulmonary responsiveness to serotonin and acetylcholine.
• Evaluation of leukocyte and platelet involvement using vinblastine, antineutrophil serum, antiplatelet serum, and prostacyclin.

Main Results:

• LPS induced significant BHR within 1-2 hours in both sensitized and nonsensitized guinea pigs.
• Neutrophil influx was observed, but BHR was independent of leukocytes.
• Platelet depletion or inhibition suppressed LPS-induced BHR, suggesting platelet involvement.
• A combination of methysergide, mepyramine, and aspirin prevented BHR by inhibiting platelet ATP release.

Conclusions:

• Platelets, or a platelet-derived factor, are key mediators of LPS-induced bronchial hyperresponsiveness.
• Leukocytes are not the primary drivers of this LPS-induced airway response.
• Findings suggest potential therapeutic strategies targeting platelet function in conditions involving LPS exposure.