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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

Effect of H2S modulation on the pro-inflammatory cytokines in the plasma of methionine-treated mice and Hcy-treated raw264.7 cells. (A–C) H2S-releasing agent GYY4137 ameliorated while CSE inhibitor PAG aggravated the increases of plasma TNF-α (A) and IL-1β (B) levels in methionine diet-treated mice. Neither GYY4137 nor PAG altered the plasma Hcy level (C); For methionine diet, C57BL/6 mice were administered with 2% methionine in drinking water for 14 consecutive days. For GYY4137 and PAG treatment, mice were pre-treated with GYY4137 (50 mg/kg/day, i.p.) or PAG (37.5 mg/kg/day, i.p.) for three days before subjected to 2% methionine supplement. n = 4–7 animals in each group; (D) Hcy treatment reduced H2S production in raw264.7 macrophages; (E,F) GYY4137 (12.5, 25, 50 µM) pre-treatment for 1 h attenuated the increases of TNF-α and IL-1β in Hcy (100 µM, 24 h)-treated macrophages; (G,H) Raw264.7 cells were pre-treated with Cys (1 mM), in the presence or absence of PAG (1 mM) co-treatment for 30 min, before being subjected to Hcy (100 µM, 24 h) treatment. n = 4–9. *p < 0.05, **p < 0.01, ***p < 0.001 compared to its corresponding control group. #p < 0.05, ##p < 0.01, ###p < 0.001 compared to Hcy group. N.S., not significant.
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ijms-16-12560-f002: Effect of H2S modulation on the pro-inflammatory cytokines in the plasma of methionine-treated mice and Hcy-treated raw264.7 cells. (A–C) H2S-releasing agent GYY4137 ameliorated while CSE inhibitor PAG aggravated the increases of plasma TNF-α (A) and IL-1β (B) levels in methionine diet-treated mice. Neither GYY4137 nor PAG altered the plasma Hcy level (C); For methionine diet, C57BL/6 mice were administered with 2% methionine in drinking water for 14 consecutive days. For GYY4137 and PAG treatment, mice were pre-treated with GYY4137 (50 mg/kg/day, i.p.) or PAG (37.5 mg/kg/day, i.p.) for three days before subjected to 2% methionine supplement. n = 4–7 animals in each group; (D) Hcy treatment reduced H2S production in raw264.7 macrophages; (E,F) GYY4137 (12.5, 25, 50 µM) pre-treatment for 1 h attenuated the increases of TNF-α and IL-1β in Hcy (100 µM, 24 h)-treated macrophages; (G,H) Raw264.7 cells were pre-treated with Cys (1 mM), in the presence or absence of PAG (1 mM) co-treatment for 30 min, before being subjected to Hcy (100 µM, 24 h) treatment. n = 4–9. *p < 0.05, **p < 0.01, ***p < 0.001 compared to its corresponding control group. #p < 0.05, ##p < 0.01, ###p < 0.001 compared to Hcy group. N.S., not significant.

Mentions: To determine whether H2S down-regulation was related to the elevations of pro-inflammatory cytokines in the mice with mild HHcy, methionine-fed mice were injected with H2S-releasing agent GYY4137 and CSE inhibitor DL-propargylglycine (PAG). As can be seen from Figure 2A,B, GYY4137 (50 mg/kg/day, i.p.) co-treatment led to a marked decrease of TNF-α and IL-1β levels in the plasma of methionine-treated mice, while PAG (37.5 mg/kg/day, i.p.) aggravated the increases of these cytokines level. Neither GYY4137 nor PAG had any influence on the plasma Hcy level (Figure 2C) induced by methionine diet.


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)

Effect of H2S modulation on the pro-inflammatory cytokines in the plasma of methionine-treated mice and Hcy-treated raw264.7 cells. (A–C) H2S-releasing agent GYY4137 ameliorated while CSE inhibitor PAG aggravated the increases of plasma TNF-α (A) and IL-1β (B) levels in methionine diet-treated mice. Neither GYY4137 nor PAG altered the plasma Hcy level (C); For methionine diet, C57BL/6 mice were administered with 2% methionine in drinking water for 14 consecutive days. For GYY4137 and PAG treatment, mice were pre-treated with GYY4137 (50 mg/kg/day, i.p.) or PAG (37.5 mg/kg/day, i.p.) for three days before subjected to 2% methionine supplement. n = 4–7 animals in each group; (D) Hcy treatment reduced H2S production in raw264.7 macrophages; (E,F) GYY4137 (12.5, 25, 50 µM) pre-treatment for 1 h attenuated the increases of TNF-α and IL-1β in Hcy (100 µM, 24 h)-treated macrophages; (G,H) Raw264.7 cells were pre-treated with Cys (1 mM), in the presence or absence of PAG (1 mM) co-treatment for 30 min, before being subjected to Hcy (100 µM, 24 h) treatment. n = 4–9. *p < 0.05, **p < 0.01, ***p < 0.001 compared to its corresponding control group. #p < 0.05, ##p < 0.01, ###p < 0.001 compared to Hcy group. N.S., not significant.
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Related In: Results  -  Collection

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ijms-16-12560-f002: Effect of H2S modulation on the pro-inflammatory cytokines in the plasma of methionine-treated mice and Hcy-treated raw264.7 cells. (A–C) H2S-releasing agent GYY4137 ameliorated while CSE inhibitor PAG aggravated the increases of plasma TNF-α (A) and IL-1β (B) levels in methionine diet-treated mice. Neither GYY4137 nor PAG altered the plasma Hcy level (C); For methionine diet, C57BL/6 mice were administered with 2% methionine in drinking water for 14 consecutive days. For GYY4137 and PAG treatment, mice were pre-treated with GYY4137 (50 mg/kg/day, i.p.) or PAG (37.5 mg/kg/day, i.p.) for three days before subjected to 2% methionine supplement. n = 4–7 animals in each group; (D) Hcy treatment reduced H2S production in raw264.7 macrophages; (E,F) GYY4137 (12.5, 25, 50 µM) pre-treatment for 1 h attenuated the increases of TNF-α and IL-1β in Hcy (100 µM, 24 h)-treated macrophages; (G,H) Raw264.7 cells were pre-treated with Cys (1 mM), in the presence or absence of PAG (1 mM) co-treatment for 30 min, before being subjected to Hcy (100 µM, 24 h) treatment. n = 4–9. *p < 0.05, **p < 0.01, ***p < 0.001 compared to its corresponding control group. #p < 0.05, ##p < 0.01, ###p < 0.001 compared to Hcy group. N.S., not significant.
Mentions: To determine whether H2S down-regulation was related to the elevations of pro-inflammatory cytokines in the mice with mild HHcy, methionine-fed mice were injected with H2S-releasing agent GYY4137 and CSE inhibitor DL-propargylglycine (PAG). As can be seen from Figure 2A,B, GYY4137 (50 mg/kg/day, i.p.) co-treatment led to a marked decrease of TNF-α and IL-1β levels in the plasma of methionine-treated mice, while PAG (37.5 mg/kg/day, i.p.) aggravated the increases of these cytokines level. Neither GYY4137 nor PAG had any influence on the plasma Hcy level (Figure 2C) induced by methionine diet.

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