Circulation Jul 18, 2017 Issue

Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor, from the National Heart Center and Duke-National University of Singapore.

Now, the SGLT2 inhibitor, empagliflozin, has been shown to improve outcomes in the EMPA-REG OUTCOMES trial. But do these benefits also apply in the real world, and to other SGLT2 inhibitors as a class? Well, we may just have some answers this week in the CVD-REAL study. More soon right after these summaries.

The first original paper this week uncovers the mechanism of beneficial action of T-cells for proper healing after myocardial infarction. Now, the pro-inflammatory danger signal, adenosine triphosphate or ATP, is released from damaged cells, and degraded by the ectonucleotidase CD73 to the anti-inflammatory mediator, adenosine.

Using newly-generated CD4-CD73 null mice, first author, Dr. Borg, corresponding author, Dr. Schrader, and colleagues from Heinrich Heine University of Düsseldorf in Germany, showed that a lack of CD73 on T-cells enhanced tissue fibrosis and worsened myocardial function in the remodeling phase after myocardial infarction.

T-cells migrated into the injured heart and upregulated their enzymatic machinery to enhance the extracellular degradation of ATP to adenosine. T-cells lacking CD73 showed accelerated production of pro-inflammatory and profibrotic cytokines. Finally, the adenosine 2B receptor was upregulated on cardiac immune cells in the remodeling phase.

In summary, therefore, local adenosine formation by CD73 on T-cells appears to be the body's own defense mechanism to control inflammation induced by myocardial infarction. This is a mechanism that might be exploited to promote healing or remodeling by specifically targeting the adenosine 2B receptor in the infarcted heart.

The next paper provides insights on genetic determinants of susceptibility to peripheral artery disease, and specifically puts the spotlight on Bcl-2-associated athanogene-3, or Bag3, which is a cell chaperone protein previously identified in a genetic screen for determinants of tissue loss with hindlimb ischemia.

In the current study, Dr. McClung from East Carolina University, Brody School of Medicine in Greenville, North Carolina, and colleagues, used adeno-associated viruses to show that an isoleucine to methionine variant at position 81 in Bag3 was sufficient to confer susceptibility to ischemic tissue necrosis in BALB/c mice.

In a series of elegant experiments, they demonstrated that Bag3 was a modulator of ischemic muscle necrosis and blood flow. In summary, this study provides evidence that genetic variation in Bag3 plays an important role in the prevention of ischemic tissue necrosis, and highlights a pathway that preserves tissue survival and muscle function in the setting of ischemia.

The next study provides insights into inflammatory atherogenesis by studying psoriasis, a chronic inflammatory disease associated with an accelerated risk of myocardial infarction. First author, Dr. Lerman, corresponding author, Dr. Mehta from the NHLBI, National Institutes of Health in Bethesda, United States, and colleagues, hypothesized that the increased cardiovascular risk observed in psoriasis would be partially attributable to an elevated subclinical coronary artery disease burden composed of non-calcified plaques with high-risk features.

To test this hypothesis, they compared total coronary plaque burden, non-calcified coronary plaque burden, and high-risk plaque prevalence between 105 psoriasis patients, 100 older hypolipidemic patients eligible for statin therapy, and 25 non-psoriasis healthy volunteers. All patients underwent CT coronary angiography, and a sample of the first 50 psoriasis patients were scanned again at one year following therapy.

The authors found that patients with psoriasis had greater non-coronary burden and increased high-risk plaque prevalence compared to healthy volunteers. Furthermore, compared to older hypolipidemic patients, patients with psoriasis had elevated non-calcified burden, and equivalent high-risk plaque prevalence. Finally, improvement in skin disease severity was associated with an improvement in non-calcified coronary burden at one year.

The clinical implications are that patients with psoriasis have similar coronary artery disease risk as hyperlipidemic patients one decade older, and these patients with psoriasis should be screened earlier for cardiovascular disease and educated about their elevated risks. Further investigations focus on the longitudinal impact of psoriasis treatment on high-risk plaque morphology, as well as on the extent of cardiovascular risk mitigation in randomized trials.

Well, those were your summaries. Now for our feature discussion. Now, we've heard of the EMPA-REG OUTCOME trial, that prospect...