Dissociation between systemic and pulmonary anti-inflammatory effects of dexamethasone in humans

The local pulmonary inflammatory response has a different temporal and qualitative profile compared with the systemic inflammatory response. Although glucocorticoids substantially downregulate the systemic release of acute-phase mediators, it is not clear whether they have comparable inhibitory effects in the human lung compartment. Therefore, we compared the anti-inflammatory effects of a pure glucocorticoid agonist, dexamethasone, on bronchoalveolar lavage and blood cytokine concentrations in response to bronchially instilled endotoxin.

In this randomized, double-blind and placebo-controlled trial, 24 volunteers received dexamethasone or placebo and had endotoxin instilled into a lung segment and saline instilled into a contralateral segment, followed by bronchoalveolar lavage.

Bronchially instilled endotoxin induced a local and systemic inflammatory response. Dexamethasone strongly blunted the systemic interleukin (IL) 6 and C-reactive protein release. In sharp contrast, dexamethasone left the local release of acute-phase mediators in the lungs virtually unchanged: bronchoalveolar lavage levels of IL-6 were only 18% lower and levels of IL-8 were even higher with dexamethasone compared with placebo, although the differences between treatments were not statistically significant (P = 0.07 and P = 0.08, respectively). However, dexamethasone had inhibitory effects on pulmonary protein extravasation and neutrophil migration.

The present study demonstrated a remarkable dissociation between the systemic anti-inflammatory effects of glucocorticoids and its protective effects on capillary leak on the one hand and surprisingly low anti-inflammatory effects in the lungs on the other.