Endogenous hydrogen sulfide-mediated MAPK inhibition preserves endothelial function through TXNIP signaling

Mounting evidence demonstrated deficient cystathionine-γ-lyase (CSE)/H₂S implicated the development of cardiovascular disease. The present study aimed to evaluating the favorable action of CSE derived H₂S on endothelial function in CSE^-/- mice. CSE^-/- mice exhibited attenuated endothelium-dependent relaxations, coupled with reduction of endothelial nitric oxide synthase (eNOS) phosphorylation at site of Ser1177, increase of thioredoxin interacting protein (TXNIP) level and MAPK phosphorylation, which were corrected by sodium hydrosulfide chronic treatment for 8 weeks. Impaired relaxations to ACh and upregulated TXNIP of CSE^-/- mice aorta were partially corrected by p38 inhibitor, extracellular regulated protein kinase (ERK) inhibitor and c-Jun N-terminal kinase (JNK) inhibitor and totally corrected by combined treatment. Pharmacological inhibition of CSE with DL-propargylglycine (PPG) in vivo and ex vivo induced endothelial dysfunction. PPG stimulated the phosphorylation of p38, JNK and ERK in human umbilical vein endothelial cells (HUVECs). MAPK inhibition by combined treatment of p38, JNK and ERK inhibitors normalized the endothelial changes of eNOS phosphorylation and TXNIP protein level in CSE^-/- mice aorta and PPG-treated HUVECs. NaHS offered similar effect with MAKP inhibitors. TXNIP siRNA prevented against endothelial function by PPG and TXNIP overexpression mimics the detrimental effect of PPG treatment on endothelial function, whereas MAPK inhibitor or NaHS has no beneficial effect. In a word, Endogenous CSE/H₂S benefits against endothelial dysfunction through suppressing MAPK/TXNIP cascade. CSE deficiency and consequently lowered endogenous H₂S level should be considered as risk factors and biomarkers for endothelial dysfunction.