Homocysteine modifies extracellular ATP availability in macrophages.
Increased levels of plasma homocysteine (hyperhomocysteinemia-HHcy) are associated to the development of coronary artery disease (CAD), peripheral vascular disease and thrombosis. In addition, recent studies have shown that inflammation, probably mediated by macrophages, mediates the pathogenesis associated to high levels of homocysteine (Hcy). In the present study, we evaluated the Hcy effects in the ATP hydrolysis and its breakdown products in murine macrophages. The results showed that micromolar concentrations of Hcy increased the ATP, ADP and AMP hydrolysis. Additionally, our results show decreased inosine levels in the extracellular milieu of Hcy-exposed macrophages. The increasing in ATP, ADP and AMP hydrolysis are not explained by increased transcription or protein expression of NTPDases and ecto-5'-nucleotidase (ecto-5'-NT/CD73) enzymes. Moreover, the formation of reactive oxygen species did not interfere in the Hcy effects, which suggest that Hcy or Hcy metabolites act directly on the modulation of NTPDases and ecto-5'-NT/CD73 activities. In conclusion, Hcy induces the rapid breakdown of ATP, ADP and AMP to adenosine (ADO), which is classically known as an anti-inflammatory response in immune cells. However, by the action of these enzymes, the extracellular adenosine generated during Hcy treatment probably is uptaken into the cells, as evidenced by the decreased in inosine formation, and thus collaborating to the inflammatory complications associates to HHcy.
Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul-UFRGS, Porto Alegre, RS, Brazil; Faculdade de Farmácia, Programa de Pós-Graduação em Biologia Celular e Molecular e Instituto de Toxicologia e Farmacologia, Pontifícia Universidade Católica do Rio Grande do Sul-PUCRS, Porto Alegre, RS, Brazil. Electronic address: rafaelzaninn@gmail.com.
Rafael Fernandes
RF
Zanin
Letícia Scussel
LS
Bergamin
Elizandra
E
Braganhol
Jean
J
Sévigny
Angela Terezinha
AT
de Souza Wyse
Ana Maria Oliveira
AM
Battastini
D000251:Adenosine Triphosphatases / Q000235:genetics; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001081:Apyrase / Q000235:genetics; D006710:Homocysteine / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D011755:Pyrophosphatases / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000235:genetics; D018048:Receptors, Purinergic P2 / Q000235:genetics
D012333:RNA, Messenger; D018047:Receptors, Purinergic P1; D018048:Receptors, Purinergic P2; D006710:Homocysteine; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D011755:Pyrophosphatases; D001081:Apyrase
ADO; CAD; Ecto-5′-nucleotidase; FBS; HHcy; Hcy; Homocysteine; Macrophages; NTPDase; adenosine; coronary artery disease; ectonucleoside triphosphate diphosphohydrolases; fetal bovine serum; homocysteine; hyperhomocysteinemia