Identification of hBD-3 in respiratory tract and serum: the increase in pneumonia

Abstract

Human b-defensin (hBD)-3, a 45 amino acid antimicrobial peptide, was originally isolated from human skin. hBD-3 mRNA has also been detected in the airways by RT-PCR. While hBD-3 may be involved in antimicrobial defences within the respiratory tract, the presence of hBD-3 peptide in the respiratory system has not yet been confirmed.The antimicrobial activity of the synthesised hBD-3 peptide was measured by a radial diffusion assay and a colony count assay. The present authors confirmed the presence of hBD-3 peptide in homogenates of human lung and serum using reverse-phase HPLC coupled with a highly sensitive RIA. The localisation of the hBD-3 peptide was investigated by immunohistochemistry. In addition, the serum concentrations of hBD-3 were measured by RIA.hBD-3 exhibited a strong antimicrobial activity, which was unaffected by increasing salt concentrations. Immunohistochemically, the current authors observed the expression of hBD-3 in bronchial and bronchiolar epithelial cells. The mean¡SD serum concentration of hBD-3 in patients with bacterial pneumonia was 239.4¡17.8 pg?mL -1 in the acute phase and, decreased to 159.3¡20.1 pg?mL -1 after the completion of therapy.In conclusion, these findings will help elucidate the role of human b-defensin-3 in host immune responses and identify the pathophysiological significance of this molecule in respiratory infections.

Klebsiella pneumoniae Capsule Polysaccharide Impedes the Expression of β-Defensins by Airway Epithelial Cells

“…Previously we have shown that K. pneumoniae CPS mediates resistance to different antimicrobial peptides, including hBD1 (8,45). However, in those studies, the sensitivities of K. pneumoniae to hBD2 and hBD3, whose levels increase in the lung during pneumonia, were not tested (29,33). Survival assays (Fig.…”

“…Thus, hBD2 and hBD3 play an important role in host defense as inducible components of the epithelial barrier. Indeed, hBD2 and hBD3 levels increase severalfold in the lung during pneumonia (29,33). The importance of BDs in lung defense has been established by the use of knockout mice.…”

Modulation of Antimicrobial Peptide Human β-defensin-3 by Toll-like Receptor Ligands in Vaginal Epithelial Cells

“…[13][14][15] Unlike other HBDs, HBD-3 is a salt-insensitive defensin with broad antimicrobial activity against multidrug-resistant nosocomial strains. 12,16,17 Concerning vaginal innate immunity, little is known about the mechanism by which epithelial cells are activated by the pathogens, receptors, and mediators involved in the immune response. A previous study reported HBD-2 expression and NF-κB activation in vaginal epithelial cells.…”

In Vitro and In Vivo Anticancer Activity of Human β-Defensin-3 and Its Mouse Homolog

“…Human β-defensin-3 (hBD3) was first isolated from human skin (7) and its expression was detected in many tissues, including airway epithelial cells (8,9). In contrast to other defensin isoforms, the prominent features of hBD3 antimicrobial activity are its salt-independency and its broad antimicrobial spectrum (7, 10, 11).…”

“…In the defensin family, there are α-defensin and β-defensin subfamilies, which conserve three specific disulfide pairings. These are produced by leukocytes and various types of epithelial cells constitutively, or in response to microbial signals and inflammatory cytokines (4-6).Human β-defensin-3 (hBD3) was first isolated from human skin (7) and its expression was detected in many tissues, including airway epithelial cells (8,9). In contrast to other defensin isoforms, the prominent features of hBD3 antimicrobial activity are its salt-independency and its broad antimicrobial spectrum (7, 10, 11).…”