Hyperhomocysteinemia abrogates fasting-induced cardioprotection against ischemia/reperfusion by limiting bioavailability of hydrogen sulfide anions.
Elevated plasma homocysteine levels are considered an independent risk factor for cardiovascular diseases. Experimental evidence has shown that hydrogen sulfide anion (HS(-)) protects the myocardium from ischemia/reperfusion (IR) injury. Both homocysteine levels and endogenous HS(-) production are mainly regulated by two transsulfuration enzymes, cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH). We hypothesized that the transsulfuration pathway plays essential roles in the development of cardiac adaptive responses against ischemia, and investigated the roles of homocysteine, HS(-), and transsulfuration enzymes in fasting-induced cardioprotection against IR injury utilizing hyperhomocysteinemic Cbs (-/-) and Cth (-/-) mice. Langendorff-perfused hearts were subjected to 25-min global ischemia, followed by 60-min reperfusion. Two-day fasting ameliorated left ventricular dysfunction after reperfusion via propargylglycine- and glibenclamide-sensitive pathways in wild-type mice but not in Cbs (-/-) or Cth (-/-) mice, although fasting induced cardiac expression of several Nrf2 target antioxidant genes in both wild-type and Cth (-/-) mice. Intraperitoneal administration of sodium hydrosulfide (a HS(-) donor) at 24 h prior to IR improved myocardial recovery in wild-type mice but not in Cth (-/-) or high-methionine-diet-fed (thus intermediately hyperhomocysteinemic) wild-type mice. Quantitative analysis of reactive sulfur species using monobromobimane derivatization methods revealed that homocysteine efficiently captures HS(-) to form homocysteine persulfide in the hearts as well as in the in vitro reactions. Here we propose a novel molecular and pathophysiological basis for hyperhomocysteinemia; excessive circulatory homocysteine interferes with HS(-)-related cardioprotection against IR injury by capturing endogenous HS(-) to form homocysteine persulfide.


CONCLUSIONS
Two-day fasting of mice ameliorates ischemia/reperfusion injury in Langendorff hearts. H2S-producing enzymes, CBS and CTH, are essential in fasting-induced cardioprotection. Administration of a H2S donor (NaHS) confers cardioprotection against IR injury. NaHS effects are absent in Cth (-/-), Cbs (-/-), and dietary hyperhomocysteinemic mice. Homocysteine captures cardioprotective HS(-) to form homocysteine persulfide.
Department of Biochemistry, Keio University School of Medicine, Tokyo, Japan.
Shintaro
S
Nakano
Isao
I
Ishii
Ken
K
Shinmura
Kayoko
K
Tamaki
Takako
T
Hishiki
Noriyuki
N
Akahoshi
Tomoaki
T
Ida
Tsuyoshi
T
Nakanishi
Shotaro
S
Kamata
Yoshito
Y
Kumagai
Takaaki
T
Akaike
Keiichi
K
Fukuda
Motoaki
M
Sano
Makoto
M
Suematsu
D000818:Animals; D003541:Cystathionine beta-Synthase / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000378:metabolism; D005215:Fasting; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism*; D020138:Hyperhomocysteinemia / Q000150:complications* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015428:Myocardial Reperfusion Injury / Q000150:complications* / Q000178:diet therapy* / Q000378:metabolism; D013440:Sulfides / Q000627:therapeutic use*
D013440:Sulfides; D003541:Cystathionine beta-Synthase; D003542:Cystathionine gamma-Lyase; C025451:sodium bisulfide; D006862:Hydrogen Sulfide