Production of β-defensins by human airway epithelia

TLDR

Human β‑defensins are antimicrobial peptides that contribute to mucosal defense, and reduced activity of these peptides has been linked to cystic fibrosis lung disease. The study found that HBD‑1 and HBD‑2 are expressed in airway epithelia, with IL‑1β selectively inducing HBD‑2; both peptides are present in bronchoalveolar lavage at several ng/ml, are salt‑sensitive bactericidal, and HBD‑2 is upregulated by inflammation while HBD‑1 provides baseline defense.

Abstract

Human β-defensins (HBDs) are antimicrobial peptides that may play a role in mucosal defense. Diminished activity of these peptides has been implicated in the pathogenesis of cystic fibrosis (CF) lung disease. We show that HBD-1 and HBD-2 mRNAs are expressed in excised surface and submucosal gland epithelia from non-CF and CF patients. The pro-inflammatory cytokine interleukin-1β stimulated the expression of HBD-2 but not HBD-1 mRNA and peptide in primary cultures of airway epithelia. HBD-1 was found in bronchoalveolar lavage (BAL) fluid from normal volunteers, CF patients, and patients with inflammatory lung diseases, whereas HBD-2 was detected in BAL fluid from patients with CF or inflammatory lung diseases, but not in normal volunteers. Both HBD-1 and HBD-2 were found in BAL fluid in concentrations of several ng/ml, and both recombinant peptides showed salt-sensitive bactericidal activity. These data suggest that in the lung HBD-2 expression is induced by inflammation, whereas HBD-1 may serve as a defense in the absence of inflammation.