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. 2009 Jul 20;4(7):e6285.
doi: 10.1371/journal.pone.0006285.

Dysregulation of human beta-defensin-2 protein in inflammatory bowel disease

Marian C Aldhous  1 , Colin L Noble, Jack Satsangi
Affiliations

Dysregulation of human beta-defensin-2 protein in inflammatory bowel disease

Marian C Aldhous et al. PLoS One. .

Abstract

Background: Human beta-defensin-2 (HBD2) is an antimicrobial peptide implicated in the pathogenesis of inflammatory bowel disease (IBD). Low copy number and concomitant low mRNA expression of the HBD2 gene have been implicated in susceptibility to colonic Crohn's Disease (CD). We investigated the colonic distribution of HBD2 mRNA expression, and the contributions of genetic and environmental factors on HBD2 protein production.

Methodology/principal findings: We examined HBD2 mRNA expression at three colonic locations by microarray analysis of biopsies from 151 patients (53 CD, 67 ulcerative colitis [UC], 31 controls). We investigated environmental and genetic influences on HBD2 protein production using ex vivo cultured sigmoid colon biopsies from 69 patients (22 CD, 26 UC, 21 controls) stimulated with lipopolysaccharide (LPS) and/or nicotine for 24 hours. HBD2 and cytokines were measured in culture supernatants. Using DNA samples from these patients, regions in the HBD2 gene promoter were sequenced for NF-kappaB binding-sites and HBD2 gene copy number was determined. HBD2 mRNA expression was highest in inflamed (vs. uninflamed p = 0.0122) ascending colon in CD and in inflamed (vs. uninflamed p<0.0001) sigmoid colon in UC. HBD2 protein production was increased in inflamed UC biopsies (p = 0.0078). There was no difference in HBD2 protein production from unstimulated biopsies of CD, UC and controls. LPS-induced HBD2 production was significantly increased in CD (p = 0.0375) but not UC (p = 0.2017); this LPS-induced response was augmented by nicotine in UC (p = 0.0308) but not CD (p = 0.6872). Nicotine alone did not affect HBD2 production. HBD2 production correlated with IL8 production in UC (p<0.001) and with IL10 in CD (p<0.05). Variations in the HBD2 promoter and HBD2 gene copy number did not affect HBD2 production.

Significance/conclusions: Colonic HBD2 was dysregulated at mRNA and protein level in IBD. Inflammatory status and stimulus but not germline variations influenced these changes.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Expression of HBD2 mRNA with disease (A), inflammation (B) and colonic location of inflamed biopsies (C).
All graphs show the log2 expression values from comparison with a reference marker (of value = 1) for HBD2 mRNA. Horizontal bars denote the median values for each analysis. P values from Mann-Whitney or Kruskall-Wallis tests are given, where significantly different.
Figure 2
Figure 2. Production of HBD2 protein by LPS or LPS+nicotine in CD and UC patients and controls.
HBD2 protein production (mean+sem) from culture supernatants of unstimulated or LPS- or LPS+nicotine (denoted LN)-stimulated biopsies in organ culture. * denotes P values of<0.05 from the results of Wilcoxon signed rank tests and the groups compared are shown. The actual p values are given in Results.
Figure 3
Figure 3. HBD2 production according to disease and inflammation status.
HBD2 production (mean+sem) from biopsies from CD, UC patients or controls, unstimulated or stimulated with LPS or LPS+nicotine (denoted LN) and grouped according to disease and inflammation. P value given is from a two-way ANOVA compared by disease/inflammation or stimulation.
Figure 4
Figure 4. Increased HBD2 with inflammation in UC sigmoid colon is seen in protein (A) and mRNA (B).
(A) HBD2 protein production from UC patients according to stimulation and inflammation status. Legend is as given for figure 3. The P value from a two-way ANOVA is given. (B) HBD2 mRNA expression for UC biopsies in sigmoid colon, grouped according to inflammation status. Horizontal bars denote median values. P values are from Mann-Whitney tests and the groups compared are indicated. The P value from a one-way ANOVA is also given.
Figure 5
Figure 5. HBD2 production according to DEFB4 CNV.
HBD2 production (mean+sem) from biopsies from CD, UC patients or controls, unstimulated or stimulated with LPS or LPS+nicotine (denoted LN) and grouped according to copy number.
See this image and copyright information in PMC

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