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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.


Tobacco-smoking-dependent GPR15 gene expression in human peripheral white blood cells. Implemented were blood specimens from two different cohorts (Working Place Cohort (gray box plot) and Replication Cohort (black boxplot)). The GPR15 gene expression was significantly increased in smokers (a, b) as well as formerly smokers (a), cig/d, cigarettes per day. Boxes indicate the 25 to 75 % percentile and whiskers the non-outlier range. P values from unpaired Student’s t test
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Fig1: Tobacco-smoking-dependent GPR15 gene expression in human peripheral white blood cells. Implemented were blood specimens from two different cohorts (Working Place Cohort (gray box plot) and Replication Cohort (black boxplot)). The GPR15 gene expression was significantly increased in smokers (a, b) as well as formerly smokers (a), cig/d, cigarettes per day. Boxes indicate the 25 to 75 % percentile and whiskers the non-outlier range. P values from unpaired Student’s t test

Mentions: To identify a phenotypic consequence of prominent reported hypomethylation at single CpG sites by tobacco smoking, gene expression of single CpG linked genes (GPR15, F2RL3, AHRR, LIM2, LRRN3, MYLK, PTPRO) was analyzed in a Working Place Cohort comprising 42 active smokers and 31 non-smokers as well as 20 formerly smokers (Table 1). Out of the 159 implemented genes of interest, differential expression of the two CpG linked genes GPR15 and AHRR next to other non-CpG linked genes (CCR5, CXCL7, FOXP3, ALOX12, and CCL2) between smoker and non-smoker remained significant after correction for multiple testing (see Additional file 1). GPR15 expression in whole blood differed mostly with respect to smoking status and independent of the daily time of blood donation (see Additional file 2). In active smokers (< or >10 cigarettes/day) the GPR15 expression was 5.3-fold higher than in non-smokers (p = 4.7 × 10−19) (Fig. 1b). Former smokers included in the Working Place Cohort showed a significant intermediate value with a 2.0-fold higher (p = 2.9 × 10−8) and 2.8-fold lower (p = 5.5 × 10−3) extent toward non-smoker and smoker (<10 cigarettes/day), respectively (Fig. 1a).Fig. 1


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)

Tobacco-smoking-dependent GPR15 gene expression in human peripheral white blood cells. Implemented were blood specimens from two different cohorts (Working Place Cohort (gray box plot) and Replication Cohort (black boxplot)). The GPR15 gene expression was significantly increased in smokers (a, b) as well as formerly smokers (a), cig/d, cigarettes per day. Boxes indicate the 25 to 75 % percentile and whiskers the non-outlier range. P values from unpaired Student’s t test
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig1: Tobacco-smoking-dependent GPR15 gene expression in human peripheral white blood cells. Implemented were blood specimens from two different cohorts (Working Place Cohort (gray box plot) and Replication Cohort (black boxplot)). The GPR15 gene expression was significantly increased in smokers (a, b) as well as formerly smokers (a), cig/d, cigarettes per day. Boxes indicate the 25 to 75 % percentile and whiskers the non-outlier range. P values from unpaired Student’s t test
Mentions: To identify a phenotypic consequence of prominent reported hypomethylation at single CpG sites by tobacco smoking, gene expression of single CpG linked genes (GPR15, F2RL3, AHRR, LIM2, LRRN3, MYLK, PTPRO) was analyzed in a Working Place Cohort comprising 42 active smokers and 31 non-smokers as well as 20 formerly smokers (Table 1). Out of the 159 implemented genes of interest, differential expression of the two CpG linked genes GPR15 and AHRR next to other non-CpG linked genes (CCR5, CXCL7, FOXP3, ALOX12, and CCL2) between smoker and non-smoker remained significant after correction for multiple testing (see Additional file 1). GPR15 expression in whole blood differed mostly with respect to smoking status and independent of the daily time of blood donation (see Additional file 2). In active smokers (< or >10 cigarettes/day) the GPR15 expression was 5.3-fold higher than in non-smokers (p = 4.7 × 10−19) (Fig. 1b). Former smokers included in the Working Place Cohort showed a significant intermediate value with a 2.0-fold higher (p = 2.9 × 10−8) and 2.8-fold lower (p = 5.5 × 10−3) extent toward non-smoker and smoker (<10 cigarettes/day), respectively (Fig. 1a).Fig. 1

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.