The Thyroid Hormone Inactivator Enzyme, Type 3 Deiodinase, Is Essential for Coordination of Keratinocyte Growth and Differentiation

Background: Thyroid hormones (THs) are key regulators of development, tissue differentiation, and maintenance of metabolic balance in virtually every cell of the body. Accordingly, severe alteration of TH action during fetal life leads to permanent deficits in humans. The skin is among the few adult tissues expressing the oncofetal protein type 3 deiodinase (D3), the TH inactivating enzyme. Here, we demonstrate that D3 is dynamically regulated during epidermal ontogenesis. Methods: To investigate the function of D3 in a postdevelopmental context, we used a mouse model of conditional epidermal-specific D3 depletion. Loss of D3 resulted in tissue hypoplasia and enhanced epidermal differentiation in a cell-autonomous manner. Results: Accordingly, wound healing repair and hair follicle cycle were altered in the D3-depleted epidermis. Further, in vitro ablation of D3 in primary culture of keratinocytes indicated that various markers of stratified epithelial layers were upregulated, thereby confirming the pro-differentiative action of D3 depletion and the consequent increased intracellular triiodothyronine levels. Notably, loss of D3 reduced the clearance of systemic TH in vivo, thereby demonstrating the critical requirement for epidermal D3 in the maintenance of TH homeostasis. Conclusion: In conclusion, our results show that the D3 enzyme is a key TH-signaling component in the skin, thereby providing a striking example of a physiological context for deiodinase-mediated TH metabolism, as well as a rationale for therapeutic manipulation of deiodinases in pathophysiological contexts

Lights and shadows of long-term dual antiplatelet therapy in "real life" clinical scenarios

Dual antiplatelet therapy (DAPT) is a cornerstone of treatment for patients with acute coronary syndromes (ACS). Mounting evidences have opened the debate about the optimal DAPT duration. Considering the ACS-pathophysiology, the most recent guidelines recommend DAPT in all ACS patients for at least 12 months unless there are contraindications such as excessive risk of bleeding. Thus, it can be considered acceptable earlier discontinuation if the risk of morbidity from bleeding outweighs the anticipated benefit. On the other hand, several studies have clearly indicated that a significant burden of platelet related-events, such as stroke and new ACS might occur after this period, suggesting that potential benefits might derive by prolonging DAPT beyond 12 months (Long DAPT). Indeed, although current guidelines give some indications about patients eligible for Long DAPT, they do not embrace several real-life clinical scenarios. Thus, in such scenarios, how to decide whether a patient is eligible for Long DAPT or not might be still challenging for clinicians. This position paper presents and discusses various real-life clinical scenarios in ACS patients, in order to propose several possible recommendations to overcome guidelines potential limitations

A comparison of reduced-dose prasugrel and standard-dose clopidogrel in elderly patients with acute coronary syndromes undergoing early percutaneous revascularization: Design and rationale of the randomized Elderly-ACS 2 study

Background Elderly patients display higher on clopidogrel platelet reactivity as compared with younger patients. Treatment with prasugrel 5 mg has been shown to provide more predictable and homogenous antiplatelet effect, as compared with clopidogrel, suggesting the possibility of reducing ischemic events after an acute coronary syndrome (ACS) without increasing bleeding. Study design The Elderly-ACS 2 study is a multicenter, randomized, parallel-group, open-label trial designed to demonstrate the superiority of a strategy of dual antiplatelet treatment using a reduced 5-mg daily dose of prasugrel over a standard strategy with a daily clopidogrel dose of 75 mg in patients older than 74 years with ACS (either ST- or non–ST-elevation myocardial infarction) undergoing early percutaneous revascularization. The primary end point is the composite of all-cause mortality, myocardial reinfarction, disabling stroke, and rehospitalization for cardiovascular causes or bleeding within 1 year. Taking advantage of the planned size of 2,000 patients, the secondary objective is to assess the prognostic impact of selected prerandomization variables (age, sex, diabetic status, serum creatinine level, electrocardiogram changes, abnormal troponin levels, basal and residual SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery [SYNTAX] score). Conclusion The Elderly-ACS 2 study is a multicenter, randomized trial comparing a strategy of dual antiplatelet therapy with a reduced dose of prasugrel with a standard dose of clopidogrel in elderly patients with ACS undergoing percutaneous revascularization (the Elderly ACS 2 trial: NCT01777503)

A Comparison of Reduced-Dose Prasugrel and Standard-Dose Clopidogrel in Elderly Patients with Acute Coronary Syndromes Undergoing Early Percutaneous Revascularization

Background -Elderly patients are at elevated risk of both ischemic and bleeding complications after an acute coronary syndrome (ACS), and display higher on-clopidogrel platelet reactivity as compared to younger patients. Prasugrel 5 mg provides more predictable platelet inhibition, as compared to clopidogrel, in the elderly, suggesting the possibility of reducing ischemic events without increasing bleeding. Methods -In a multicenter, randomized, open-label, blinded-endpoint trial, we compared a once daily maintenance dose of prasugrel 5 mg with the standard clopidogrel 75 mg in patients >74 years with ACS undergoing percutaneous coronary intervention (PCI). The primary endpoint was the composite of mortality, myocardial infarction, disabling stroke and re-hospitalization for cardiovascular causes or bleeding within one year. The study was designed to demonstrate superiority of prasugrel 5 mg over clopidogrel 75 mg. Results -Enrolment was interrupted, according to pre-specified criteria, after a planned interim analysis, when 1443 patients (40% women, mean age 80 years) had been enrolled, with a median follow-up of 12 months, due to futility for efficacy. The primary endpoint occurred in 121 patients (17%) with prasugrel and 121 (16.6%) with clopidogrel (HR 1.007, 95% CI, 0.78-1.30;P=0.955). Definite/probable stent thrombosis rates were 0.7% with prasugrel vs 1.9% with clopidogrel (OR 0.36, C.I. 0.13-1.00, p=0.06). Bleeding Academic Research Consortium types ≥2 were 4.1% with prasugrel vs 2.7% with clopidogrel (OR 1.52, C.I. 0.85-3.16, P= 0.18). Conclusions -The present study in elderly ACS patients showed no difference in the primary endpoint between reduced-dose prasugrel and standard-dose clopidogrel. However, the study should be interpreted in the light of premature termination of the trial. Clinical Trial Registration -URL: https://clinicaltrials.gov/ Unique Identifier: NCT01777503