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. 2011 Jul;4(4):409-19.
doi: 10.1038/mi.2010.83. Epub 2011 Jan 19.

Epigenetic regulation of human β-defensin 2 and CC chemokine ligand 20 expression in gingival epithelial cells in response to oral bacteria

L Yin  1 , W O Chung
Affiliations
Free PMC article

Epigenetic regulation of human β-defensin 2 and CC chemokine ligand 20 expression in gingival epithelial cells in response to oral bacteria

L Yin et al. Mucosal Immunol. 2011 Jul.
Free PMC article

Abstract

Gingival epithelia utilize multiple signaling pathways to regulate innate immune responses to various oral bacteria, but little is understood about how these bacteria alter epithelial epigenetic status. In this study we report that DNA methyltransferase (DNMT1) and histone deacetylase expression were decreased in gingival epithelial cells treated with oral pathogen Porphyromonas gingivalis and nonpathogen Fusobacterium nucleatum. Pretreatment with trichostatin A and sodium butyrate, which increase acetylation of chromatin histones, significantly enhanced the gene expression of antimicrobial proteins human β-defensin 2 (hBD2) and CC chemokine ligand 20 (CCL20) in response to both bacterial challenges. Pretreatment with DNMT inhibitor 5'-azacytidine increased hBD2 and CCL20 expression in response to F. nucleatum, but not to P. gingivalis. Furthermore, we observed a differential pattern of protein levels of H3K4me3, which has been associated with chromatin remodeling and activation of gene transcription, in response to P. gingivalis vs. F. nucleatum. This study provides a new insight into the bacteria-specific innate immune responses via epigenetic regulation.

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Figures

Figure 1
Figure 1
Differential mRNA expression of HDAC1, HDAC2 and DNMT1 in human TERT cells in response to oral bacteria. Differential mRNA expression of (a) histone deacetylases 1 and 2 (HDAC1 and HDAC2) and (b) DNA methyltransferase (DNMT1) in human TERT cells in response to Porphyromonas gingivalis vs. Fusobacterium nucleatum. Human TERT cells were stimulated with P. gingivalis (Pg) or F. nucleatum (Fn) at multiplicities of infection (MOIs) of 10:1, 50:1, and 100:1 for 4 or 24 h. Unstimulated cells at 4 and 24 h served as controls. Changes in mRNA expression were evaluated by quantitative real-time PCR (QRT-PCR) and results are expressed as fold change in gene expression compared with the corresponding unstimulated controls (4 and 24 h) after normalization with glyceraldehydes-3-phosphate dehydrogenase (GAPDH). The experiment was repeated twice using TERT cells. Error bars indicate s.e.m. Asterisks indicate statistically significant difference compared with unstimulated control (Ctl) (*P<0.05, **P<0.01).
Figure 2
Figure 2
Differential decreased mRNA expression of HDAC1, HDAC2 and DNMT1 in gingival epithelial cells in response to various doses of oral bacteria. mRNA expression of (a) DNA methyltransferase (DNMT1), (b) histone deacetylase 1 (HDAC1), and (c) histone deacetylase 2 (HDAC2) are differentially decreased in gingival epithelial cells (GECs) in response to various doses of Porphyromonas gingivalis vs. Fusobacterium nucleatum. GECs were stimulated with P. gingivalis (Pg) or F. nucleatum (Fn) at multiplicities of infection (MOIs) of 10:1, 50:1, 100:1, and 200:1 for 24 h. Changes in mRNA expression were evaluated by quantitative real-time PCR (QRT-PCR) and results are expressed as fold change in gene expression compared with the unstimulated control after normalization with the housekeeping gene glyceraldehydes-3-phosphate dehydrogenase (GAPDH). The data are derived from three different cell donors tested in duplicate. Error bars indicate s.e.m. Asterisks indicate statistically significant difference compared with unstimulated control (Ctl) (*P<0.05, **P<0.01).
Figure 3
Figure 3
Protein levels of histone deacetylases 1 and 2 (HDAC1 and HDAC2) and DNA methyltransferase (DNMT1) are differentially expressed in gingival epithelial cells (GECs) in response to Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn). GECs were stimulated with P. gingivalis (Pg) or F. nucleatum (Fn) at multiplicities of infection (MOIs) of 100:1 for 24 h. Nuclear proteins were extracted, denatured at 70 °C for 10 min, and separated by NuPAGE electrophoresis system. Nuclear extracts of Hela cells probed with individual primary antibody were used as positive controls. The data are derived from two different cell donors tested in duplicate.
Figure 4
Figure 4
mRNA expression of innate immune markers human β-defensin 2 (hBD-2) are increased when histone deacetylase (HDAC) and DNA methyltransferase (DNMT) are inhibited. Gingival epithelial cells (GECs) were pretreated with trichostatin A (TSA; 9 and 45 m), sodium butyrate (SB; 0.5 and 2.0 m) or 5′-azacytidine (AZA; 1 and 10 μ) for 4 h, and subsequently exposed to Porphyromonas gingivalis (multiplicity of infection (MOI) 100:1) or Fusobacterium nucleatum (MOI 100:1) for 16 h. Gene expression of hBD2 was evaluated by quantitative real-time PCR (QRT-PCR) compared with unstimulated control after normalization with glyceraldehydes-3-phosphate dehydrogenase (GAPDH). Controls include unstimulated control, bacteria-alone treatment, and various inhibitors alone as indicated. No significant changes were found in the gene expression of hBD2 in GECs treated with inhibitor only: (a) SB, (b) TSA, (c) SB+TSA, and (d) AZA compared with unstimulated control. Data are expressed as means of fold change±s.e.m. from three donors evaluated in duplicate. Asterisks indicate statistically significant difference compared with unstimulated control (Ctl) (*P<0.05, **P<0.01).
Figure 5
Figure 5
mRNA expression of innate immune markers CC chemokine ligand 20 (CCL20) are increased when histone deacetylase (HDAC) and DNA methyltransferase (DNMT) are inhibited. Gingival epithelial cells (GECs) were pretreated with trichostatin A (TSA; 9 and 45 m), sodium butyrate (SB; 0.5 and 2.0 m), or 5′-azacytidine (AZA; 1 and 10 μ) for 4 h, and subsequently exposed to Porphyromonas gingivalis (multiplicity of infection (MOI) 100:1) or Fusobacterium nucleatum (MOI 100:1) for 16 h. Gene expression of (b) CCL20 was evaluated by quantitative real-time PCR (QRT-PCR) compared with unstimulated control after normalization with glyceraldehydes-3-phosphate dehydrogenase (GAPDH). Controls include unstimulated control, bacteria-alone treatment, and various inhibitors alone as indicated. No significant changes were found in the gene expression of CCL20 in GECs treated with inhibitor only: (a) SB, (b) TSA, (c) SB+TSA, and (d) AZA compared with unstimulated control. Data are expressed as means of fold change±s.e.m. from three donors evaluated in duplicate. Asterisks indicate statistically significant difference compared with unstimulated control (Ctl) (*P<0.05, **P<0.01).
Figure 6
Figure 6
Interleukin-8 (IL-8) secretion is increased when histone deacetylase (HDAC) and DNA methyltransferase (DNMT) are inhibited. Gingival epithelial cells (GECs) were pretreated with trichostatin A (TSA; 9 and 45 m), sodium butyrate (SB; 0.5 and 2.0 m), or 5′-azacytidine (AZA; 1 and 10 μ) for 4 h, and subsequently exposed to Porphyromonas gingivalis (multiplicity of infection (MOI) 100:1) or Fusobacterium nucleatum (MOI 100:1) for 16 h. Secretion of IL-8 in response to various oral bacteria is evaluated by enzyme-linked immunosorbent assay (ELISA). Cell-free supernatant was collected and the amount of IL-8 secreted is shown in pg ml–1. Unstimulated cells (UN) are used as controls in each experiment. Data from duplicates with cells from three different donors are shown. No significant changes were found in the secretion of IL-8 in GECs treated with inhibitor only: (a) SB, (b) TSA, (c) SB+TSA, and (d) AZA compared with unstimulated control. Asterisks indicate statistically significant difference compared with unstimulated control (Ctl) (*P<0.05, **P<0.01).
Figure 7
Figure 7
Protein levels of histone H3 methylated at Lys4 were evaluated with PathScan enzyme-linked immunosorbent assay (ELISA). Gingival epithelial cells (GECs) were exposed to Porphyromonas gingivalis or Fusobacterium nucleatum for 24 h at multiplicity of infection (MOI) of 100:1, and then nuclear protein was extracted followed by sonication. The H3 tri-methylated at Lys4 was captured by coated antibody after incubation with cell lysates, and histone H3 protein level was quantified according to the absorbance readings at 450 nm. Protein expression was expressed as the ratio of absorbance readings normalized to relative protein amount. The data are average from three different donor cells tested with standard error deviation. The asterisks indicate the significant difference vs. the respective unstimulated control (**P<0.01).
Figure 8
Figure 8
Relevant gene networks based on literature co-occurrence. We submitted queried genes DEFB4 (human β-defensin 2 (hBD2)), CC chemokine ligand 20 (CCL20), interleukin-8 (IL-8), and methylated genes in Table 1 to the PubGene and identified coexpressed possibility based on the literature co-occurrence. Red color represents query genes, purple color represents the first-order literature, and black color represents the second-order literature. The color reproduction of this figure is available on the html full text version of the manuscript.
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