The chromosomal protein HMGN 2 mediates lipopolysaccharide-induced expression of b-defensins in A 549 cells

Antimicrobial peptides are produced by many different tissues of the body when the innate immune system is activated by lipopolysaccharide (LPS) or other inflammatory cytokines and chemokines. Defensins are small cationic antimicrobial peptides which have usually been categorized into three major families based on the molecular structure: a-, b-, and h-defensins [1–3]. They regulate both the innate and adaptive immune responses, exhibiting broad-spectrum antimicrobial activity against most Gram-positive and Gram-negative bacteria, fungi and viruses such as influenza viruses. b-defensins are largely expressed in epithelial cells on the surface of respiratory, gastrointestinal and genitourinary tracts and skin [3,4]. Human b-defensin (HBD) 1 is constitutively expressed in the epithelial surface of the respiratory and genitourinary tracts [5]. In contrast, the expression of HBD-2, HBD-3 and HBD-4 is inducible in response to LPS, tumour necrosis factor a (TNF-a), interleukin 1b or Gram-negative pathogens, underscoring their crucial role in epithelial host defence under inflammatory conditions [4,6]. Inducible expression of b-defensins by human epithelial