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Homocysteine Triggers Inflammatory Responses in Macrophages through Inhibiting CSE-H2S Signaling via DNA Hypermethylation of CSE Promoter.

Li JJ, Li Q, Du HP, Wang YL, You SJ, Wang F, Xu XS, Cheng J, Cao YJ, Liu CF, Hu LF - Int J Mol Sci (2015)

Bottom Line: Unfortunately, Hcy-lowering strategies were found to have limited effects in reducing cardiovascular events.DNMT inhibition or knockdown reversed the decrease of CSE transcription induced by Hcy in macrophages.In sum, our findings demonstrate that Hcy may trigger inflammation through inhibiting CSE-H2S signaling, associated with increased promoter DNA methylation and transcriptional repression of cse in macrophages.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, the Second Affiliated Hospital of Soochow University, Soochow University, Suzhou 215004, China. dragonrabbit@163.com.

ABSTRACT
Hyperhomocysteinemia (HHcy) is an independent risk factor of atherosclerosis and other cardiovascular diseases. Unfortunately, Hcy-lowering strategies were found to have limited effects in reducing cardiovascular events. The underlying mechanisms remain unclear. Increasing evidence reveals a role of inflammation in the pathogenesis of HHcy. Homocysteine (Hcy) is a precursor of hydrogen sulfide (H2S), which is formed via the transsulfuration pathway catalyzed by cystathionine β-synthase and cystathionine γ-lyase (CSE) and serves as a novel modulator of inflammation. In the present study, we showed that methionine supplementation induced mild HHcy in mice, associated with the elevations of TNF-α and IL-1β in the plasma and reductions of plasma H2S level and CSE expression in the peritoneal macrophages. H2S-releasing compound GYY4137 attenuated the increases of TNF-α and IL-1β in the plasma of HHcy mice and Hcy-treated raw264.7 cells while CSE inhibitor PAG exacerbated it. Moreover, the in vitro study showed that Hcy inhibited CSE expression and H2S production in macrophages, accompanied by the increases of DNA methyltransferase (DNMT) expression and DNA hypermethylation in cse promoter region. DNMT inhibition or knockdown reversed the decrease of CSE transcription induced by Hcy in macrophages. In sum, our findings demonstrate that Hcy may trigger inflammation through inhibiting CSE-H2S signaling, associated with increased promoter DNA methylation and transcriptional repression of cse in macrophages.

No MeSH data available.


Related in: MedlinePlus

Plasma homocysteine (Hcy) (A), hydrogen sulfide (H2S) (B) and cytokines levels (C,D), as well as cystathionine γ-lyase (CSE) mRNA (E) and protein expressions (F) in the peritoneal macrophages of C57BL/6 mice with or without methionine-supplementation. The measurements of Hcy, H2S and cytokines level were performed as described in Materials and Methods. CSE mRNA level was examined by quantitative PCR while its protein expression determined by immunoblotting analysis. 18S mRNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein served as loading controls. Results are presented as mean ± SEM, n = 4–7 in each group. *p < 0.05, **p < 0.01, ***p < 0.001 compared to control groups.
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ijms-16-12560-f001: Plasma homocysteine (Hcy) (A), hydrogen sulfide (H2S) (B) and cytokines levels (C,D), as well as cystathionine γ-lyase (CSE) mRNA (E) and protein expressions (F) in the peritoneal macrophages of C57BL/6 mice with or without methionine-supplementation. The measurements of Hcy, H2S and cytokines level were performed as described in Materials and Methods. CSE mRNA level was examined by quantitative PCR while its protein expression determined by immunoblotting analysis. 18S mRNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein served as loading controls. Results are presented as mean ± SEM, n = 4–7 in each group. *p < 0.05, **p < 0.01, ***p < 0.001 compared to control groups.

Mentions: Dietary supplementation with 2% methionine in drinking water resulted in significant elevations in plasma Hcy (15.56 ± 1.553 µM in methionine-treated group versus 6.3 ± 0.298 µM in control group) and pro-inflammatory cytokine (TNF-α, IL-1β) levels, accompanied by the reduction in plasma H2S level in C57BL/6 mice (Figure 1A–D). Moreover, the CSE mRNA and protein expressions decreased approximately by 60% and 45%, respectively, in the peritoneal macrophages isolated from the methionine-treated mice compared to control dieted mice.


Homocysteine Triggers Inflammatory Responses in Macrophages through Inhibiting CSE-H2S Signaling via DNA Hypermethylation of CSE Promoter.

Li JJ, Li Q, Du HP, Wang YL, You SJ, Wang F, Xu XS, Cheng J, Cao YJ, Liu CF, Hu LF - Int J Mol Sci (2015)

Plasma homocysteine (Hcy) (A), hydrogen sulfide (H2S) (B) and cytokines levels (C,D), as well as cystathionine γ-lyase (CSE) mRNA (E) and protein expressions (F) in the peritoneal macrophages of C57BL/6 mice with or without methionine-supplementation. The measurements of Hcy, H2S and cytokines level were performed as described in Materials and Methods. CSE mRNA level was examined by quantitative PCR while its protein expression determined by immunoblotting analysis. 18S mRNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein served as loading controls. Results are presented as mean ± SEM, n = 4–7 in each group. *p < 0.05, **p < 0.01, ***p < 0.001 compared to control groups.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4490461&req=5

ijms-16-12560-f001: Plasma homocysteine (Hcy) (A), hydrogen sulfide (H2S) (B) and cytokines levels (C,D), as well as cystathionine γ-lyase (CSE) mRNA (E) and protein expressions (F) in the peritoneal macrophages of C57BL/6 mice with or without methionine-supplementation. The measurements of Hcy, H2S and cytokines level were performed as described in Materials and Methods. CSE mRNA level was examined by quantitative PCR while its protein expression determined by immunoblotting analysis. 18S mRNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein served as loading controls. Results are presented as mean ± SEM, n = 4–7 in each group. *p < 0.05, **p < 0.01, ***p < 0.001 compared to control groups.
Mentions: Dietary supplementation with 2% methionine in drinking water resulted in significant elevations in plasma Hcy (15.56 ± 1.553 µM in methionine-treated group versus 6.3 ± 0.298 µM in control group) and pro-inflammatory cytokine (TNF-α, IL-1β) levels, accompanied by the reduction in plasma H2S level in C57BL/6 mice (Figure 1A–D). Moreover, the CSE mRNA and protein expressions decreased approximately by 60% and 45%, respectively, in the peritoneal macrophages isolated from the methionine-treated mice compared to control dieted mice.

Bottom Line: Unfortunately, Hcy-lowering strategies were found to have limited effects in reducing cardiovascular events.DNMT inhibition or knockdown reversed the decrease of CSE transcription induced by Hcy in macrophages.In sum, our findings demonstrate that Hcy may trigger inflammation through inhibiting CSE-H2S signaling, associated with increased promoter DNA methylation and transcriptional repression of cse in macrophages.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, the Second Affiliated Hospital of Soochow University, Soochow University, Suzhou 215004, China. dragonrabbit@163.com.

ABSTRACT
Hyperhomocysteinemia (HHcy) is an independent risk factor of atherosclerosis and other cardiovascular diseases. Unfortunately, Hcy-lowering strategies were found to have limited effects in reducing cardiovascular events. The underlying mechanisms remain unclear. Increasing evidence reveals a role of inflammation in the pathogenesis of HHcy. Homocysteine (Hcy) is a precursor of hydrogen sulfide (H2S), which is formed via the transsulfuration pathway catalyzed by cystathionine β-synthase and cystathionine γ-lyase (CSE) and serves as a novel modulator of inflammation. In the present study, we showed that methionine supplementation induced mild HHcy in mice, associated with the elevations of TNF-α and IL-1β in the plasma and reductions of plasma H2S level and CSE expression in the peritoneal macrophages. H2S-releasing compound GYY4137 attenuated the increases of TNF-α and IL-1β in the plasma of HHcy mice and Hcy-treated raw264.7 cells while CSE inhibitor PAG exacerbated it. Moreover, the in vitro study showed that Hcy inhibited CSE expression and H2S production in macrophages, accompanied by the increases of DNA methyltransferase (DNMT) expression and DNA hypermethylation in cse promoter region. DNMT inhibition or knockdown reversed the decrease of CSE transcription induced by Hcy in macrophages. In sum, our findings demonstrate that Hcy may trigger inflammation through inhibiting CSE-H2S signaling, associated with increased promoter DNA methylation and transcriptional repression of cse in macrophages.

No MeSH data available.


Related in: MedlinePlus