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A varying T cell subtype explains apparent tobacco smoking induced single CpG hypomethylation in whole blood.

Bauer M, Linsel G, Fink B, Offenberg K, Hahn AM, Sack U, Knaack H, Eszlinger M, Herberth G - Clin Epigenetics (2015)

Bottom Line: Within two independent cohorts, we confirmed the differentially expression of the GPR15 gene when smokers and non-smokers subjects are compared.Treatment of peripheral blood mononuclear cell (PBMC) cultures with aqueous cigarette smoke extract did not induce a higher proportion of this T cell subtype.Our results underline that DNA hypomethylation at cg19859270 site, observed in WBCs of smokers, did not arise by direct effect of tobacco smoking compounds on methylation of DNA but rather by the enrichment of a tobacco-smoking-induced lymphocyte population in the peripheral blood.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Immunology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, 04318 Germany.

ABSTRACT

Background: Many recent epigenetic studies report that cigarette smoking reduces DNA methylation in whole blood at the single CpG site cg19859270 within the GPR15 gene.

Results: Within two independent cohorts, we confirmed the differentially expression of the GPR15 gene when smokers and non-smokers subjects are compared. By validating the GPR15 protein expression at the cellular level, we found that the observed decreased methylation at this site in white blood cells (WBC) of smokers is mainly caused by the high proportion of CD3+GPR15+ expressing T cells in peripheral blood. In current smokers, the percentage of GPR15+ cells among CD3+ T cells in peripheral blood is significantly higher (15.5 ± 7.2 %, mean ± standard deviation) compared to non-smokers (3.7 ± 1.6 %). Treatment of peripheral blood mononuclear cell (PBMC) cultures with aqueous cigarette smoke extract did not induce a higher proportion of this T cell subtype.

Conclusions: Our results underline that DNA hypomethylation at cg19859270 site, observed in WBCs of smokers, did not arise by direct effect of tobacco smoking compounds on methylation of DNA but rather by the enrichment of a tobacco-smoking-induced lymphocyte population in the peripheral blood.

No MeSH data available.


Methylation of CpG site cg19859270 in PBMCs and sorted CD3+GPR15- and CD3+GPR15+ cells. CpG was analyzed by pyrosequencing of PBMCs and flow cytometric-sorted cells of non-smoker (white plots, n = 6) and smokers (gray plots, n = 6). P values from Mann-Whitney U Test
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Fig4: Methylation of CpG site cg19859270 in PBMCs and sorted CD3+GPR15- and CD3+GPR15+ cells. CpG was analyzed by pyrosequencing of PBMCs and flow cytometric-sorted cells of non-smoker (white plots, n = 6) and smokers (gray plots, n = 6). P values from Mann-Whitney U Test

Mentions: Analysis of methylation of CpG site cg19859270 located within the GPR15 gene was performed in isolated PBMCs, in flow cytometric-sorted CD3+GPR15+ as well as CD3+GPR15- T cells of smokers (n = 6) and non-smokers (n = 6). At the PBMC level, a methylation difference of 3.0 % (p = 0.009) between smoker and non-smoker was observed as expected (Fig. 4). A hypomethylation at cg19859270 was specific for GPR15 expressing cells independent on smoking habit. The methylation difference between GPR15− and GPR15+ T cells was 49.5 % in smoker (p = 0.005) and similar in non-smoker (38 %, p = 0.005). Within the CD3+GPR15+ population, the hypomethylation of cg19859270 site was slightly more pronounced in smokers than non-smokers (delta methylation = −15.0 %, p = 0.029). Due to the low frequency of GPR15+ B cells, sorting for this cell type was not performed.Fig. 4


A varying T cell subtype explains apparent tobacco smoking induced single CpG hypomethylation in whole blood.

Bauer M, Linsel G, Fink B, Offenberg K, Hahn AM, Sack U, Knaack H, Eszlinger M, Herberth G - Clin Epigenetics (2015)

Methylation of CpG site cg19859270 in PBMCs and sorted CD3+GPR15- and CD3+GPR15+ cells. CpG was analyzed by pyrosequencing of PBMCs and flow cytometric-sorted cells of non-smoker (white plots, n = 6) and smokers (gray plots, n = 6). P values from Mann-Whitney U Test
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4526203&req=5

Fig4: Methylation of CpG site cg19859270 in PBMCs and sorted CD3+GPR15- and CD3+GPR15+ cells. CpG was analyzed by pyrosequencing of PBMCs and flow cytometric-sorted cells of non-smoker (white plots, n = 6) and smokers (gray plots, n = 6). P values from Mann-Whitney U Test
Mentions: Analysis of methylation of CpG site cg19859270 located within the GPR15 gene was performed in isolated PBMCs, in flow cytometric-sorted CD3+GPR15+ as well as CD3+GPR15- T cells of smokers (n = 6) and non-smokers (n = 6). At the PBMC level, a methylation difference of 3.0 % (p = 0.009) between smoker and non-smoker was observed as expected (Fig. 4). A hypomethylation at cg19859270 was specific for GPR15 expressing cells independent on smoking habit. The methylation difference between GPR15− and GPR15+ T cells was 49.5 % in smoker (p = 0.005) and similar in non-smoker (38 %, p = 0.005). Within the CD3+GPR15+ population, the hypomethylation of cg19859270 site was slightly more pronounced in smokers than non-smokers (delta methylation = −15.0 %, p = 0.029). Due to the low frequency of GPR15+ B cells, sorting for this cell type was not performed.Fig. 4

Bottom Line: Within two independent cohorts, we confirmed the differentially expression of the GPR15 gene when smokers and non-smokers subjects are compared.Treatment of peripheral blood mononuclear cell (PBMC) cultures with aqueous cigarette smoke extract did not induce a higher proportion of this T cell subtype.Our results underline that DNA hypomethylation at cg19859270 site, observed in WBCs of smokers, did not arise by direct effect of tobacco smoking compounds on methylation of DNA but rather by the enrichment of a tobacco-smoking-induced lymphocyte population in the peripheral blood.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Immunology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, 04318 Germany.

ABSTRACT

Background: Many recent epigenetic studies report that cigarette smoking reduces DNA methylation in whole blood at the single CpG site cg19859270 within the GPR15 gene.

Results: Within two independent cohorts, we confirmed the differentially expression of the GPR15 gene when smokers and non-smokers subjects are compared. By validating the GPR15 protein expression at the cellular level, we found that the observed decreased methylation at this site in white blood cells (WBC) of smokers is mainly caused by the high proportion of CD3+GPR15+ expressing T cells in peripheral blood. In current smokers, the percentage of GPR15+ cells among CD3+ T cells in peripheral blood is significantly higher (15.5 ± 7.2 %, mean ± standard deviation) compared to non-smokers (3.7 ± 1.6 %). Treatment of peripheral blood mononuclear cell (PBMC) cultures with aqueous cigarette smoke extract did not induce a higher proportion of this T cell subtype.

Conclusions: Our results underline that DNA hypomethylation at cg19859270 site, observed in WBCs of smokers, did not arise by direct effect of tobacco smoking compounds on methylation of DNA but rather by the enrichment of a tobacco-smoking-induced lymphocyte population in the peripheral blood.

No MeSH data available.