Defensin, beta 1

Human beta defensin 1 belongs to the large group of antimicrobial peptides (AMP), a heterogeneous group of naturally occurring, small (< 100 amino acids), cationic amphiphilic peptides with broad microbicidal activity, known as "endogenous antibiotics". Antimicrobial peptides are synthesized by plants, bacteria, insects, invertebrates and vertebrates.

Human antimicrobial peptides play a major role in the defense against infectious pathogens in the innate, non-specific immune defense (see below Immunity, innate) as part of an epithelial barrier function in the respiratory, urogenital and gastrointestinal tract as well as the skin. In addition to the cellular epithelial barrier, they represent a kind of chemical barrier. In addition to their direct antimicrobial functions, they also act as moderators of inflammatory processes.

Human defensin beta 1 is a human protein encoded by the DEFB1 gene located on chromosome 8 gene locus: Chr 8: 6.87 - 6.88 Mb p23.1, in the vicinity of other defensins.

The members of the defensin family are very similar in their protein sequence.

All beta-defensins have antimicrobial properties in common. Although beta-defensin-1 is expressed by numerous epithelia, the antimicrobial function of this beta-defensin is still unclear. This is due to its largely lacking antibiotic efficiency in experimental approaches (Schroeder BO 2012).

Other functions:

Keratinocytes express beta-defensin-1, the defensin is elevated in proliferating cells (Frye M et al. 2001). Beta-defensin-1 HBD-1 is overexpressed in various cell lines of oral carcinomas (Han Q et al. 2014). Beta-defensin-1 plays a role in the differentiation of keratinocytes. Defensin-beta 1 regulates the development of tight junctions in cultured human keratinocytes (Goto H et al. 2013).

Furthermore, it seems to play a moderating role in renal carcinomas and prostate cancer.

Gingival epithelial cell lines to which different amounts (25-200 μg/ml) of green tea extracts or epigallocatechin-3-gallate were added showed an upregulation of beta-defensins 1 and 2.

Elevated levels of defensin beta 1 can be detected in COPD and severe bronchial asthma. The production of defensin beta depends on the severity of the respiratory disease. Defensin can be considered an efficient biomarker (Baines KJ et al.2015).

In alveolar macrophages of HIV-infected persons the expression of beta-defensin 1 is reduced (Alp S et al. 2005).

Beta defensin 1 is involved in the pathogenesis of cystic fibrosis.

1. https://www.ncbi.nlm.nih.gov/pubmed/23150110AlpS et al (2005) Expression of beta-defensin 1 and 2 in nasal epithelial cells and alveolar macrophages from HIV-infected patients. Eur J Med Res 10:1-6.
2. Baines KJ et al (2015) Airway β-Defensin-1 Protein Is Elevated in COPD and Severe Asthma. Mediators Inflamm 2015:407271.
3. Frye M et al (2001) Expression of human beta-defensin-1 promotes differentiation of keratinocytes. J Mol Med (Berl) 79:275-282.
4. Goto H et al (2013) Human beta defensin-1 regulates the development of tight junctions in cultured human epidermal keratinocytes. J Dermatol Sci 71:145-148.
5. Han Q et al (2014) Human beta-defensin-1 suppresses tumor migration and invasion and is an independent predictor for survival of oral squamous cell carcinoma patients. PLoS One 9:e91867.
6. Li Y et al (2015) Host Avian Beta-Defensin and Toll-Like Receptor Responses of Pigeons following Infection with Pigeon Paramyxovirus Type 1 Appl Environ Microbiol 81:6415-6424.
7. Lombardo Bedran TB et al (2014) Green tea extract and its major constituent, epigallocatechin-3-gallate, induce epithelial beta-defensin secretion and prevent beta-defensin degradation by Porphyromonas gingivalis. J Periodontal Res 49:615623.
8. Németh BC et al (2014) Relevance of α-defensins (HNP1-3) and defensin β-1 in diabetes. World J Gastroenterol 20:9128-9137.
9. Schroeder BO (2012) Human beta-defensin 1: from defence to offence. Z Gastroenterol 50:1171-1175.
10. Wang XF et al (2015) Antimicrobial activity of human β-defensins against lactic acid bacteria. Nat Prod Res 29:2164-2166.