zuki N, Kitakaze M. An interaction between glucagon-like peptide-1 and adenosine contributes to cardioprotection of a dipeptidyl peptidase 4 inhibitor from myocardial ischemia-reperfusion injury. Am J Physiol Heart Circ Physiol 308: H1287-H1297, 2015. First published March 7, 2015; doi:10.1152/ajpheart.00835.2014.-Dipeptidyl peptidase 4 (DPP4) inhibitors suppress the metabolism of the potent antihyperglycemic hormone glucagon-like peptide-1 (GLP-1). DPP4 was recently shown to provide cardioprotection through a reduction of infarct size, but the mechanism for this remains elusive. Known interactions between DPP4 and adenosine deaminase (ADA) suggest an involvement of adenosine signaling in DPP4 inhibitor-mediated cardioprotection. We tested whether the protective mechanism of the DPP4 inhibitor alogliptin against myocardial ischemia-reperfusion injury involves GLP-1-and/or adenosine-dependent signaling in canine hearts. In anesthetized dogs, the coronary artery was occluded for 90 min followed by reperfusion for 6 h. A 4-day pretreatment with alogliptin reduced the infarct size from 43.1 Ϯ 2.5% to 17.1 Ϯ 5.0% without affecting collateral flow and hemodynamic parameters, indicating a potent antinecrotic effect. Alogliptin also suppressed apoptosis as demonstrated by the following analysis: 1) reduction in the Bax-to-Bcl2 ratio; 2) cytochrome c release, 3) an increase in Bad phosphorylation in the cytosolic fraction; and 4) terminal deoxynucleotidyl transferase dUTP nick end labeling assay. This DPP4 inhibitor did not affect blood ADA activity or adenosine concentrations. In contrast, the nonselective adenosine receptor blocker 8-(p-sulfophenyl)theophylline (8SPT) completely blunted the effect of alogliptin. Alogliptin did not affect Erk1/2 phosphorylation, but it did stimulate phosphorylation of Akt, glycogen synthase kinase-3, and cAMP response element-binding protein (CREB). Only 8SPT prevented alogliptin-induced CREB phosphorylation. In conclusion, the DPP4 inhibitor alogliptin suppresses ischemia-reperfusion injury via adenosine receptor-and CREB-dependent signaling pathways. dipeptidyl peptidase 4 inhibitor; ischemia-reperfusion injury; myocardial infarction; cardioprotection; adenosine GLUCAGON-LIKE PEPTIDE-1 (GLP-1) is mostly known as a potent antihyperglycemic hormone secreted by intestinal cells to stimulate glucose-dependent insulin secretion from pancreatic beta cells. Once in circulation, GLP-1 is rapidly metabolized by dipeptidyl peptidase 4 (DPP4). Therefore, GLP-1 analogs and DPP4 inhibitors are commonly prescribed for the treatment of diabetes mellitus (6, 11). DPP4 inhibitors also exert extrapancreatic effects in the brain, stomach, and heart (39). However, the mechanisms by which they mediate these effects remain largely unknown. Several reports showed that DPP4 inhibitors limit the infarct size after ischemia-reperfusion in the heart (15, 51), but the extent of their beneficial effects remains controversial (7,52). Recently, several reports have indicated that DPP4 forms a complex with adenosin...
In conclusion, the administration of 2,2,6,6-tetramethylpiperidine-1-oxyl as a RNP exerted cardioprotective effects against ischemia and reperfusion injury in canine hearts without exerting unfavorable hemodynamic effects. RNPs may represent a promising new therapy for patients with acute myocardial infarction.
Since diabetes mellitus (DM) is the most common cause of heart failure (HF), it is critically important to clarify whether incretin hormones including glucagon-like peptide-1 (GLP-1), which play an important role in blood glucose control, mediate cardioprotection. There are many lines of basic research evidence indicating that GLP-1 improves the pathophysiology of HF: In murine and canine HF models, either GLP-1 analogues or DPP-IV inhibitors improved cardiac functions. The first question that arises is how either GLP-1 analogues or DPP-IV inhibitors mediate cardioprotection. Cardiovascular diseases are tightly linked to impaired glucose tolerance (IGT): IGT is not only one of the causes of cardiovascular events but also the result of HF. Indeed, the treatment of IGT improved HF, showing that one of the mechanisms attributable to DPP-IV inhibitors is related to the improvement of IGT. Intriguingly, either DPP-IV inhibitors or GLP-1 analogues mediate cardioprotection even without IGT, suggesting two possible explanations: One is that GLP-1 analogues directly activate the prosurvival kinases, such as Akt and Erk1/2, and another is that DPP-IV inhibition increases cardioprotective peptides such as BNP and SDF-1α. The next question is whether cardioprotection is translated to clinical medicine. Small scale clinical trials proved their cardioprotective effects; however, several large scale clinical trials have not proved the beneficial effects of DPP-IV inhibitors. Taken together, GLP-1 analogues or DPP-IV inhibitors can mediate cardioprotection, however, what needs to be clarified is who mainly receives their benefits among the patients with cardiovascular diseases and/or DM.
Objectives
We aimed to compare the coronary angioscopic appearance of neointimal coverage (NIC) over durable‐polymer everolimus‐eluting stents (XIENCE‐EES) and bioresorbable‐polymer everolimus‐eluting stents (SYNERGY‐EES) 1 year after implantation.
Background
XIENCE‐EES and SYNERGY‐EES have been developed to prevent delayed arterial healing associated with first generation drug‐eluting stents. However, the process of arterial healing after XIENCE‐EES and SYNERGY‐EES implantation has not been clarified.
Methods
Patients who underwent implantation of XIENCE‐EES (n = 20) or SYNERGY‐EES (n = 20) were enrolled in this study. Coronary angiography and coronary angioscopy were performed 12 ± 1 months after stent implantation. The NIC over the stent was classified into four grades: grade 0, stent struts fully exposed; grade 1, stent struts bulging into the lumen and, still visible; grade 2, stent struts embedded in neointima but still visible; and grade 3, stent struts fully embedded and invisible. Stents exhibiting more than one NIC grade was defined as heterogeneous. Moreover, presence of thrombi was investigated.
Results
The distribution of dominant NIC grade (XIENCE‐EES: grade 0, 0%; grade 1, 25%; grade 2, 50%; grade 3, 25%; SYNERGY‐EES: grade 0, 0%; grade 1, 5%; grade 2, 15%; grade 3, 80%; P = 0.002) and NIC heterogeneity was significantly different (P = 0.004). Thrombi were more frequent in XIENCE‐EES than in SYNERGY‐EES (40 versus 10%, respectively; P = 0.03).
Conclusion
Compared with XIENCE‐EES, SYNERGY‐EES were well covered by neointima and accompanied by fewer thrombi. These findings implied arterial healing of SYNERGY‐EES was better than that of XIENCE‐EES.
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