hbd-1

β-Defensin 1 (DEFB1) is a member of the β-defensin family, which is highly expressed by epithelial cells. β-defensins are expressed as the C-terminal portion of precursors and are released by proteolytic cleavage of a signal peptide. β-defensins contain a six-cysteine motif that forms three intra-molecular disulfide bonds. β-defensin 1 is an antimicrobial peptide implicated in the resistance of epithelial surfaces to microbial colonization. Defects in β-Defensin-1 contribute to asthma diagnosis, with apparent gender-specific effects in human. β-defensin 1 may also play a role in the pathogenesis of severe sepsis. In addition, β-defensin 1 is associated with induction profiles in gingival keratinocytes.

β-Defensin 4A is a membrane-active cationic peptide that functions in inflammation and innate immune responses. There are at least 30 β-Defensins, which are distinguished from α-Defensins by the connectivity pattern of their three intermolecular disulfide bonds. Members of the Defensin family are highly similar in protein sequence. This gene encodes Defensin, DEFB4;, which has broad-spectrum antimicrobial activity and may play an important role in innate epithelial defense. They are highly expressed in skin and tonsils, and to a lesser extent in trachea, uterus, kidney, thymus, adenoid, pharynx and tongue. β-Defensin 4A has low expression in salivary gland, bone marrow, colon, stomach, polyp and larynx. No expression in small intestine. The 45 amino acid mature human BD3 shares 38% and 33% amino acid sequence identity with mouse and rat BD3, respectively.

The DEFB1 gene, encoding for the constitutively expressed human beta-defensin 1 (hBD1) antimicrobial peptide is a potential candidate when studying genetic susceptibility to caries. DEFB1 genetic variations have been reported as contributing to hBD1 production impairment, leading to a greater susceptibility to be infected by oral pathogens, also leading to periodontitis. To counteract host immunity, Cryptosporidium parvum has evolved multiple strategies to suppress host antimicrobial defense. One such strategy is to reduce the production of the antimicrobial peptide beta-defensin 1 (DEFB1) by host epithelial cells. Beta-Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity.