Alexander C. Castillo

Modulation of microRNAs in hypertension-induced arterial remodeling through the β1 and β3-adrenoreceptor pathways.

BACKGROUND Dysregulation of microRNAs (miRNAs) in arterial dysfunction and hypertension has not been extensively investigated yet. This project determined the effects of two anti-hypertensive β1 adrenergic selective blockers on miRNA expression in the Dahl Salt Sensitive (DSS) hypertensive rat model. METHODS AND RESULTS Microarray analysis showed that a set of miRNAs is differently expressed in the aorta of high salt (HS) treated rats with miR-320 increased and miR-26b and -21 decreased. All of these changes were reverted to normal by nebivolol (NEB, a β1 selective-blocker and β3 activator). The selective β3-adrenoceptor antagonist S-(-)-cyanopindolol (Syc) counteracted the effect of NEB on these miRNAs. Atenolol (ATN, a pure β1-blocker) combined with specific β3 agonist BRL37344 restored the expression of all three miRNAs, similar to NEB, while ATN alone had only a partial effect on miR-320 expression. Computational analysis found Insulin Growth Factor-1 Receptor (IGF1R) as a putative target of miR-320, and Phosphatase and tensin homolog on chromosome ten (PTEN) as a putative target of miR-26b and -21. The targets were verified by luciferase reporter assays. Inhibition of miR-320 by an antisense inhibitor or NEB increased IGF1R expression, while miR-320 overexpression reversed the effect of NEB. Overexpression of miR-26b or -21 or NEB decreased PTEN levels, while inhibition of miR-26b or -21 attenuated the effect of NEB. HS diet induced downregulation of IGF1R and upregulation of PTEN in the aorta. NEB normalized the aberrant expression of IGF1R and PTEN and also improved the impairment of vascular AKT/eNOS signaling. Moreover, both NEB and ATN showed to have protective effects on salt-induced hypertension, oxidative stress, and vascular remodeling. NEB had a greater effect than ATN. CONCLUSIONS Our data supports a differential miRNA expression profile in salt-induced hypertension. Manipulation of dysregulated miRNAs by β-blockers may substantially induce alterations of gene expression and prevent arterial dysfunction and remodeling.

Phosphodiesterase-3 inhibition augments the myocardial infarct size-limiting effects of exenatide in mice with type 2 diabetes

Glucagon-like peptide (GLP)-1 receptor activation increases intracellular cAMP with downstream activation of PKA. Cilostazol (CIL), a phosphodiesterase-3 inhibitor, prevents cAMP degradation. We assessed whether CIL amplifies the exenatide (EX)-induced increase in myocardial cAMP levels and PKA activity and augments the infarct size (IS)-limiting effects of EX in db/db mice. Mice fed a Western diet received oral CIL (10 mg/kg) or vehicle by oral gavage 24 h before surgery. One hour before surgery, mice received EX (1 μg/kg sc) or vehicle. Additional mice received H-89, a PKA inhibitor, alone or with CIL + EX. Mice underwent 30 min of coronary artery occlusion and 24 h of reperfusion. Both EX and CIL increased myocardial cAMP levels and PKA activity. Levels were significantly higher in the EX + CIL group. Both EX and CIL reduced IS. IS was the smallest in the CIL + EX group. H-89 completely blocked the IS-limiting effects of EX + CIL. EX + CIL decreased phosphatase and tensin homolog on chromosome 10 upregulation and increased Akt and ERK1/2 phosphorylation after ischemia-reperfusion. These effects were blocked by H-89. In conclusion, EX and CIL have additive effects on IS limitation in diabetic mice. The additive effects are related to cAMP-induced PKA activation, as H-89 blocked the protective effect of CIL + EX.

Nebivolol Induces Distinct Changes in Profibrosis MicroRNA Expression Compared With Atenolol, in Salt-Sensitive Hypertensive Rats

Nebivolol is a selective &bgr;1-blocker with nitric oxide–enhancing effects. MicroRNAs are small noncoding RNA molecules that downregulate gene expression. We compared the effects of nebivolol and atenolol, a first generation &bgr;1-selective blocker, on left ventricular hypertrophy, fibrosis, and function and microRNA expression in a rodent model of hypertension. Dahl salt-sensitive rats received either low-salt chow (control) or AIN-76A high-salt (8% NaCl) diet and randomized to vehicle (high-salt), nebivolol (20 mg/kg per day), or atenolol (50 mg/kg per day) for 8 weeks. High-salt induced left ventricular hypertrophy and fibrosis and decreased the expression of miR-27a, -29a, and -133a. Nebovolol attenuated deterioration of left ventricular systolic function, remodeling, and fibrosis more than atenolol, despite similar effects on heart rate and blood pressure. Nebivolol, but not atenolol, prevented the decrease in miR-27a and -29a induced by high-salt. Nebivolol and atenolol equally attenuated the decrease in miR-133a. In vitro overexpression of miR-27a,-29a, and -133a inhibited cardiomyocyte hypertrophy and reduced collagen expression. Both miR-27a and -29a target Sp1, and miR-133a targets Cdc42. Pharmacological inhibition of Sp1 and Cdc42 decreased myocardial fibrosis and hypertrophy. Our data support a differential microRNAs expression profile in salt-induced hypertension. Nebivolol substantially attenuated cardiac remodeling, hypertrophy, and fibrosis more than atenolol. These effects are related to attenuation of the hypertension-induced decrease in miR-27a and -29a (with a subsequent decrease in Sp1 expression) and miR-133a (with a subsequent decrease in Cdc42).

Regulation of phosphatase and tensin homolog on chromosome 10 in response to hypoxia

Phosphatase and tensin homolog on chromosome 10 (PTEN) is downregulated during hypertrophic and cancerous cell growth, leading to activation of the prosurvival Akt pathway. However, PTEN regulation in cardiac myocytes upon exposure to hypoxia remains unclear. We explored the role of PTEN in response to hypoxia/ischemia in the myocardium. We validated that PTEN is a transcriptional target of activating transcription factor 2 (ATF-2) and is positively regulated via a p38/ATF-2 signaling pathway. Accordingly, hypoxia-induced upregulation of phosphorylation of ATF-2 and PTEN were reversed by a dominant negative mutant p38. Inhibition of PTEN in cardiomyocytes attenuated hypoxia-induced cell death and apoptosis. Cardiac-specific knockout of PTEN resulted in increased phosphorylation of Akt and forkhead box O 1 (forkhead transcription factors), limited infarct size in animals exposed to ischemia-reperfusion injury, and ameliorated deterioration of left ventricular function and remodeling following permanent coronary artery occlusion. In addition, the activation of Bim, FASL, and caspase was coupled with PTEN activation, all of which were attenuated by PTEN inhibition. In conclusion, cardiomyocyte-specific conditional PTEN deletion limited myocardial infarct size in an in vivo model of ischemia-reperfusion injury and attenuated adverse remodeling in a model of chronic permanent coronary artery ligation.

Surgical Timing and the Menstrual Cycle Affect Wound Healing in Young Breast Reduction Patients.

Background: Young female subjects are known to have the highest baseline menstrual hormone levels of any female age group. Studies have found an association between hormone levels and wound healing. This has been researched in the orthopedic, gynecologic, and dermatologic literature, and more recently, in young patients undergoing augmentation mammaplasty. The purpose of this study was to determine whether the timing of surgery relative to the menstrual cycle plays a role in surgical complications following bilateral reduction mammaplasty. Methods: All female patients aged 25 years or younger with a documented last menstrual cycle undergoing a bilateral reduction mammaplasty from 2005 to 2013 were reviewed. Surgical timing and postoperative complications relative to the last menstrual cycle were recorded. The preovulatory phase referred to days 1 to 14 after the patient’s last menstrual cycle, whereas the postovulatory phase referred to days 15 to 28. Results: Forty-nine patients met inclusion criteria. Undergoing bilateral reduction mammaplasty during the postovulatory phase was associated with development of wound dehiscence and hypertrophic scarring (p < 0.005), which were the most common postoperative complications. Surgery in the preovulatory or postovulatory phase did not affect hematoma, seroma, wound infection, or nipple-areolar complex necrosis rates (p > 0.05). Age, race/ethnicity, body mass index, large resection mass, and medical comorbidities did not affect wound dehiscence or scar hypertrophy rates (p > 0.05). Conclusions: Young patients undergoing bilateral reduction mammaplasty during the postovulatory phase of the menstrual cycle have an increased risk of wound healing issues and poor scarring. This may be attributable to hormonal fluxes occurring during this phase and the already high hormone levels in this population.

Breast striae after cosmetic augmentation.

BACKGROUND Breast augmentation is the most popular cosmetic surgery procedure in the United States. Postoperative striae is a known but incompletely understood complication of breast augmentation. OBJECTIVES The authors investigated their own patient population to discern risk factors for new-onset striae after cosmetic breast augmentation. METHODS A retrospective chart review was performed for patients who underwent primary breast augmentation from 2005 to 2012 in a single-surgeon practice. Initial chart review revealed that only patients aged ≤25 years exhibited new striae; therefore, only patients from this age group were included. Potential risk factors examined included age, body mass index (BMI), oral contraceptive use, time of last menstrual period (LMP), parity, smoking and alcohol status, diabetes mellitus, and personal history of striae. Implant and surgical factors examined included implant material (silicone vs saline), volume, and location (submuscular vs subglandular placement) and the site of incision. RESULTS Of the 549 patients included in the study, 17 (3.10%) had new-onset striae, observed at a mean of 58 days postoperatively. The risk of striae was statistically significantly higher (P<.05) among patients who were younger (3.3 times), were nulliparous (14.38 times), began their LMP>14 days before surgery (9.24 times), and had a history of striae (6.11 times). There was a strong correlation between new-onset breast striae and implant size, as well as BMI (P=.07). CONCLUSIONS There is a strong correlation between new-onset striae and hormone levels, genetic factors, and tissue stretch components in patients who undergo cosmetic breast augmentation. This information can be utilized to better educate patients about this potential complication. LEVEL OF EVIDENCE 4.

Response to “Comments on ‘Breast Striae after Cosmetic Augmentation’”

Thank you very much for your comments on our paper.1 We absolutely agree with you that “a potentially significant hormonal imbalance is paramount in the development of striae distensae.” We recently performed a study on young women undergoing breast reduction. We found a statistically significant increased incidence of wound problems in women who had their surgery in the postovulatory period compared with women who …