Outcomes of Hypospadias Repair Based on Surgical Techniques: A 4-Year Retrospective Study

Purpose

This study aimed to report the outcomes of hypospadias repair performed at a tertiary-level hospital during 2018 to 2021.

Methods

A retrospective chart review of 119 patients was performed.

Results

The most frequent coronal hypospadias cases were distal. However, the most common scrotal hypospadias cases were proximal. The average age at the time of the first surgery was 2.4 years (standard deviation, ±2.3 years). The tubularised incised plate technique was performed for 57 of these 119 patients. Urethral fistula was the most common complication associated with distal and proximal cases (23.96% and 30.43%, respectively). No significant correlation was observed between any complication and the surgical technique. Based on the logistic regression model, the duration of urethral stenting was statistically significant (p=0.025), indicating that a urinary catheter duration of more than 5 days resulted in a 2.9-times increased risk of postoperative urethral fistula.

Conclusion

Prolonged urethral stenting for more than 5 days may result in subsequent urethral fistula development. Neither the severity of hypospadias nor the surgical technique seems to affect postoperative complications.

Oxidation-reduction imaging of myoglobin reveals two-phase oxidation in the reperfused myocardium

Myocardial infarction (MI) is a serious acute cardiovascular syndrome that causes myocardial injury due to blood flow obstruction to a specific myocardial area. Under ischemic-reperfusion settings, a burst of reactive oxygen species is generated, leading to redox imbalance that could be attributed to several molecules, including myoglobin. Myoglobin is dynamic and exhibits various oxidation-reduction states that have been an early subject of attention in the food industry, specifically for meat consumers. However, rarely if ever have the myoglobin optical properties been used to measure the severity of MI. In the current study, we develop a novel imaging pipeline that integrates tissue clearing, confocal and light sheet fluorescence microscopy, combined with imaging analysis, and processing tools to investigate and characterize the oxidation-reduction states of myoglobin in the ischemic area of the cleared myocardium post-MI. Using spectral imaging, we have characterized the endogenous fluorescence of the myocardium and demonstrated that it is partly composed by fluorescence of myoglobin. Under ischemia-reperfusion experimental settings, we report that the infarcted myocardium spectral signature is similar to that of oxidized myoglobin signal that peaks 3 h post-reperfusion and decreases with cardioprotection. The infarct size assessed by oxidation-reduction imaging at 3 h post-reperfusion was correlated to the one estimated with late gadolinium enhancement MRI at 24 h post-reperfusion. In conclusion, this original work suggests that the redox state of myoglobin can be used as a promising imaging biomarker for characterizing and estimating the size of the MI during early phases of reperfusion.

Impaired cardiac structure and systolic function in athletes using supra-physiological doses of anabolic androgenic steroids

OBJECTIVES

Athletes are increasingly using supra-physiological doses of anabolic androgenic steroids without weighing health side effects. This study aims to conjointly evaluate the effect of supraphysiological doses of anabolic androgenic steroids on global cardiovascular structure and functional capacity.

DESIGN

Cross-sectional study.

METHODS

92 males enrolled in the study, including 18 sedentary subjects, 26 anabolic androgenic steroid non-user athletes, and 48 anabolic androgenic steroid-user athletes. Two-dimensional echocardiography was done to evaluate the cardiovascular structure and function.

RESULTS

Anabolic androgenic steroid-users presented increased cardiac remodeling of the left ventricle and left atrium compared to control groups (p < 0.001). Anabolic androgenic steroid-users showed increased left ventricular mass/body surface area versus control groups (p < 0.001), with 28 steroid-users (58.3 %) having cardiac remodeling, which is more than control groups (p < 0.001). Anabolic androgenic steroid-users presented lower diastolic function (E and E/A) compared to non-users (p = 0.003 and <0.001, respectively). Ejection fraction was decreased among anabolic androgenic steroid-users versus the sedentary group only (p = 0.020), while anabolic androgenic steroid-users presented reduced global longitudinal strain of 15.43 % compared to both control groups (p < 0.001). Moreover, anabolic androgenic steroid-users experienced more tricuspid valve regurgitation (p = 0.001).

CONCLUSIONS

Anabolic androgenic steroid consumption is associated with global cardiac remodeling with increased dimensions of the left ventricle, and atrium. Anabolic androgenic steroid-users present left ventricular hypertrophy with reduced subclinical systolic function. Moreover, anabolic androgenic steroid consumption is correlated with valve regurgitation and dilation of the sino-tubular junction.

Antimesenteric sleeve tapering enteroplasty with end-to-end anastomosis versus primary end-to-side anastomosis for the management of jejunal/ileal atresia

BACKGROUND/OBJECTIVE

Small bowel atresia commonly causes neonatal intestinal obstructions. Technical problems are associated with the surgical management of atresia using primary end-to-end anastomosis. Furthermore, the significantly dilated proximal loop may be associated with the stasis of intestinal fluid, thus increasing pressure on the anastomosis and prolonging fasting time before initiation of oral intake. This study aimed to perform antimesenteric tapering of the proximal loop using a linear stapler to reduce its diameter and facilitate anastomosis with the distal loop.

METHODS

This retrospective study included 57 neonates diagnosed with jejunoileal atresia. They were categorised into two groups: Group A (n = 29), which included neonates treated using antimesenteric sleeve enteroplasty tapering using a linear stapler and Group B (n = 28), which included neonates treated at the primary end of the proximal loop to the side of the distal loop anastomosis.

RESULTS

The mean operative time was 122.5 min in group A vs. 118 min in group B, and the mean duration to reach full oral intake was 17 days in group A vs. 20.2 days in group B (p = 0.03). The mean length of hospital stay was 25 and 35 days in groups A and B, respectively (p = 0.042).

CONCLUSION

Tapering the proximal dilated bowel loop to achieve anastomosis with the distal loop improved the transient time, reduced stasis and its associated translocation and colonisation, and allowed for early initiation and maintenance of oral intake. All these parameters shortened the overall length of hospital stay.

Chronic anabolic androgenic steroid administration reduces global longitudinal strain among off-cycle bodybuilders

BACKGROUND

Supra-physiologic doses of anabolic androgenic steroids (AAS) lead to multiple cardiovascular complications. The long-term clinical effect of AAS overuse on cardiac structure and function, which persists during off-cycle periods, remains unclear.

METHODS

A total of 15 sedentary subjects and 79 bodybuilders (26 AAS non-users and 53 AAS-users), matched for age and male gender, were assessed in a cross-sectional design for echocardiography measures. AAS-users were included during an off-cycle phase, abstained from AAS for at least 1 month. 2D standard M-mode and speckle tracking echocardiography were used to measure cardiac dimensions and functions.

RESULTS

Inter-ventricular septum and posterior wall thickness were significantly higher among chronic off-cycle AAS-users compared to AAS non-users and sedentary group. Off-cycle AAS-users showed lower E/A ratio of the diastolic function. Left ventricular systolic function was not affected in terms of ejection fraction, but significant subclinical systolic dysfunction, assessed by GLS, was observed for chronic off-cycle AAS-users compared to AAS non-users (GLS = -16.8% vs. -18.5%, respectively; p = 0.001). Diameter of left atrium and right ventricle were significantly enlarged among off-cycle AAS-user bodybuilders (p = 0.002 and 0.040). TAPSE and RV S', and cardiac vasculature of aorta were comparable in all groups.

CONCLUSIONS

This study demonstrates that during off-cycle phase, AAS-users show long-term impaired GLS, even after considerable AAS abstain, despite normal LVEF. It highlights the importance of following GLS to predict hypertrophy and heart failure events, and not relying on LVEF alone. In addition, the hypertrophic effect of chronic AAS consumption is transitional during AAS washout periods.

Peri-Kasai portoenterostomy sutures anchoring the jejunal loop to Glisson capsule: A novel modification to reduce the incidence of cholangitis

BACKGROUND

Kasai portoenterostomy (KPE) is the standard surgical management for biliary atresia (BA). To improve the outcome these infants were operated on within the first two months of life. The success of the procedure is reflected by clearance of jaundice and either absence or occurrence of fewer attacks of cholangitis. The failure of the procedure indicates liver transplantation (LT).

OBJECTIVE

to reduce the incidence of the recurrent attacks of cholangitis by peri-KPE sutures anchoring the jejunal loop to the Glisson capsule.

METHODS

It is a retrospective study that included 45 infants diagnosed with BA and who were operated on at an age younger than 60 days. They were categorized into two groups, Group A (n = 23) included infants treated with the classic KPE, and Group B (n = 22) included infants treated in the same way plus peri KPE sutures anchoring the jejunal loop to the Glisson capsule.

RESULTS

The mean operative time in Group A was 149.3 min versus 164.8 min in Group B (p-value 0.039). The mean level of bilirubin was 2.2 versus 2.1 in Group A and Group B respectively at two years follow up. The total attacks of cholangitis per patient were significantly lower in Group B than in Group A (cutoff value = 3), which was reflected by the significant reduction of the incidence of LT in Group B.

CONCLUSION

peri KPE sutures anchoring the jejunal loop to the Glisson capsule significantly reduced the incidence of recurrent attacks of cholangitis and subsequently decreased the requirement of LT on the short-term follow-up.

Non-adherence to antihypertensive medications in Lebanese adults hospitalized for hypertensive urgency and its cost

BACKGROUND

Drug non-adherence is assumed to play an important role in development of hypertensive urgency, which is a common health problem resulting in frequent emergency department admissions and thus increased healthcare spending wastage. The objective of this study is to assess the rate of non-adherence to antihypertensives and to evaluate influencing factors predicting this behavior in Lebanese hypertensive adults. In addition, this study aim to estimate the cost of hospitalization for hypertensive urgency covered by the Ministry of Public Health in patients' non-adherent to their antihypertensives.

METHODS

A multi-methods approach is used comprising a cross-sectional study, additionally to an observational, retrospective, cost of illness study. A cross-sectional questionnaire based study is conducted from May to Dec, 2019 to address the study objective. Using the Ministry of Public Health hospitalization data during 2019, the cost of hospitalization for hypertensive urgency is assessed. Multivariable analysis is performed to calculate the adjusted odd ratios by fitting a logistic regression model.

RESULTS

The cross-sectional study includes 494 participants and shows that 43.0% of patients hospitalized and covered by the Ministry of Public Health are non-adherent. The univariate regression model shows that adherence to antihypertensive medications is significantly associated with age (p-value = 0.005) and follow-up visits (p-value = 0.046). The odds of adherence for participants earning more than USD 2000 was 3.27 times that for those who earn less than USD 1000 (p = 0.026). The estimated cost of hospitalization for non-adherent patients is USD 452,353 in 2019.

CONCLUSION

Non-adherence associated hospitalization costs represents a financial burden to Lebanese health system.

UM171A-induced ROS promote antigen cross-presentation of immunogenic peptides by bone marrow-derived mesenchymal stromal cells

Background

Mesenchymal stromal cells (MSCs) have been extensively used in the clinic due to their exquisite tissue repair capacity. However, they also hold promise in the field of cellular vaccination as they can behave as conditional antigen presenting cells in response to interferon (IFN)-gamma treatment under a specific treatment regimen. This suggests that the immune function of MSCs can be pharmacologically modulated. Given the capacity of the agonist pyrimido-indole derivative UM171a to trigger the expression of various antigen presentation-related genes in human hematopoietic progenitor cells, we explored the potential use of UM171a as a means to pharmacologically instill and/or promote antigen presentation by MSCs.

Methods

Besides completing a series of flow-cytometry-based phenotypic analyses, several functional antigen presentation assays were conducted using the SIINFEKL-specific T-cell clone B3Z. Anti-oxidants and electron transport chain inhibitors were also used to decipher UM171a’s mode of action in MSCs. Finally, the potency of UM171a-treated MSCs was evaluated in the context of therapeutic vaccination using immunocompetent C57BL/6 mice with pre-established syngeneic EG.7T-cell lymphoma.

Results

Treatment of MSCs with UM171a triggered potent increase in H2-K^b cell surface levels along with the acquisition of antigen cross-presentation abilities. Mechanistically, such effects occurred in response to UM171a-mediated production of mitochondrial-derived reactive oxygen species as their neutralization using anti-oxidants or Antimycin-A mitigated MSCs’ ability to cross-present antigens. Processing and presentation of the immunogenic ovalbumin-derived SIINFEKL peptide was caused by de novo expression of the Psmb8 gene in response to UM171a-triggered oxidative stress. When evaluated for their anti-tumoral properties in the context of therapeutic vaccination, UM171a-treated MSC administration to immunocompetent mice with pre-established T-cell lymphoma controlled tumor growth resulting in 40% survival without the need of additional supportive therapy and/or standard-of-care.

Conclusions

Altogether, our findings reveal a new immune-related function for UM171a and clearly allude to a direct link between UM171a-mediated ROS induction and antigen cross-presentation by MSCs. The fact that UM171a treatment modulates MSCs to become antigen-presenting cells without the use of IFN-gamma opens-up a new line of investigation to search for additional agents capable of converting immune-suppressive MSCs to a cellular tool easily adaptable to vaccination.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02693-z.

Delayed vs. early enteral feeding after repair of congenital recto-vestibular fistula: The effect on perineal wound healing

INTRODUCTION

congenital Recto vestibular fistula represents the commonest type of anorectal malformation in females. The treatment of this anomaly is mainly approached either through anterior or posterior sagittal ano-rectoplasty approach. Several perioperative factors may affect the outcome. One of major postoperative complications is the occurrence of wound infection. We aimed to study the effect of delayed vs. early enteral feeding on the occurrence of perineal wound infection (PWI) after repair of congenital recto vestibular fistula.

PATIENTS AND METHODS

Fifty-five infants with recto-vestibular fistula were included. They were managed by single stage anterior sagittal anorectoplasty (ASARP) at an age ≥3 months. Groups A and B included infants who started oral intake on the 6th and 2nd postoperative days respectively. Group A infants were kept on peripheral parenteral nutrition (PPN) during the fasting period.

RESULTS

Superficial wound infection occurred in three cases in group A while it developed in seven cases in group B. Deep perineal infection occurred in two and five cases in group A and group B respectively. The mean hospital stay was 8 days in group A vs. 13 days in group B when PWI developed.

CONCLUSION

Delayed enteral feeding with PPN keeps the perineal wound less contaminated with stool. This promoted proper and fast healing with lower incidence of PWI. Also, PPN compensates the catabolic effects of both surgical trauma and fasting during the postoperative period and ensures maintenance of normal levels of essential nutrients that allow for proper healing.

Impact of Fasting on Cardiovascular Outcomes in Patients With Hypertension

ABSTRACT

Fasting has been frequently practiced for religious or medical purposes worldwide. However, limited literature assesses the impact of different fasting patterns on the physiologic and cardiac-related parameters in patients with hypertension. This review aims to examine the effect of fasting on cardiovascular outcomes in hypertensive patients. Medline, Embase, and Cochrane library were systematically screened until March 2021 for observational prospective cohorts investigating the effect of fasting on cardiovascular outcomes. Articles were assessed by searching for hypertension and fasting, both as Medical Subject Headings (MeSH) terms and text words. The review included studies assessing Ramadan, intermittent, and water-only fasting. Water-only fasting reduces body weight, blood pressure, and lipolytic activity of fasting hypertensive patients without affecting average heart rate. Ramadan fasting enhances lipid profile, although it shows conflicting results for body weight, blood pressure, and heart rate variability. Considering the limited studies in this field, further research should be conducted to support the clinical impact of fasting on the cardiovascular health of patients with hypertension.

Reduced reticulum-mitochondria Ca2+ transfer is an early and reversible trigger of mitochondrial dysfunctions in diabetic cardiomyopathy

Type 2 diabetic cardiomyopathy features Ca²⁺ signaling abnormalities, notably an altered mitochondrial Ca²⁺ handling. We here aimed to study if it might be due to a dysregulation of either the whole Ca²⁺ homeostasis, the reticulum-mitochondrial Ca²⁺ coupling, and/or the mitochondrial Ca²⁺ entry through the uniporter. Following a 16-week high-fat high-sucrose diet (HFHSD), mice developed cardiac insulin resistance, fibrosis, hypertrophy, lipid accumulation, and diastolic dysfunction when compared to standard diet. Ultrastructural and proteomic analyses of cardiac reticulum-mitochondria interface revealed tighter interactions not compatible with Ca²⁺ transport in HFHSD cardiomyocytes. Intramyocardial adenoviral injections of Ca²⁺ sensors were performed to measure Ca²⁺ fluxes in freshly isolated adult cardiomyocytes and to analyze the direct effects of in vivo type 2 diabetes on cardiomyocyte function. HFHSD resulted in a decreased IP3R-VDAC interaction and a reduced IP3-stimulated Ca²⁺ transfer to mitochondria, with no changes in reticular Ca²⁺ level, cytosolic Ca²⁺ transients, and mitochondrial Ca²⁺ uniporter function. Disruption of organelle Ca²⁺ exchange was associated with decreased mitochondrial bioenergetics and reduced cell contraction, which was rescued by an adenovirus-mediated expression of a reticulum-mitochondria linker. An 8-week diet reversal was able to restore cardiac insulin signaling, Ca²⁺ transfer, and cardiac function in HFHSD mice. Therefore, our study demonstrates that the reticulum-mitochondria Ca²⁺ miscoupling may play an early and reversible role in the development of diabetic cardiomyopathy by disrupting primarily the mitochondrial bioenergetics. A diet reversal, by counteracting the MAM-induced mitochondrial Ca²⁺ dysfunction, might contribute to restore normal cardiac function and prevent the exacerbation of diabetic cardiomyopathy.

Factors Associated with Antihypertensive Medication Non-Adherence: A Cross-Sectional Study Among Lebanese Hypertensive Adults

BACKGROUND

Poor adherence to antihypertensives is associated with negative outcome of the disease as well as loss of health-care resources. Addressing the epidemic of poor adherence requires identifying factors associated with this behaviour. The aim of this study is to describe adherence to antihypertensive medication among Lebanese hypertensive patients and to evaluate the association between socio-economic, patient- and conditions-related factors and non-adherence.

METHODS

A cross-sectional study was carried out on adherence to antihypertensive medications covering all governorates of Lebanon. This study was conducted between February 2018 and January 2019 on a random sample of 1497 hypertensive patients. A face-to-face questionnaire was used to assess adherence to antihypertensive medication and its determinants according to the five World Health Organization (WHO) main categories. Logistic regression analysis was performed to test the adjusted association between the multiple exposure factors, and drug adherence data were collected by trained interviewers.

RESULTS

Adherence to antihypertensive medications was reported by 1253 (83.7%) of the patients. After multivariate analysis, patients who tried to control their stress level (OR = 0.77, 95% CI [0.38-0.95]), those who had normal BP readings (OR =0.49, 95% CI [0.18-0.97]), and those who believed in the effectiveness of their treatment (OR = 0.31, 95% CI [0.14-0.76]) had a significantly lower chance to exhibit non-adherence to their treatment. However, older patients (OR= 1.87, 95% CI [1.23-2.21]), divorced/separated patients (OR= 2.14, 95% CI [1.31-5.48]), married (OR=1.96, 95% CI [1.27-3.90]), widowed (OR=2.11, 95% CI [1.62-6.50]), obese patients (OR = 1.76, 95% CI [1.21-1.94]), and patients who smoked hookah and cigarettes (OR = 2.62, 95% CI [1.17-6.76]) were more likely to exhibit non-adherence.

CONCLUSION

Our study highlights the influence of factors such as old age, marital status, BMI and high level of emotional stress on non-adherence to medication in hypertensive patients. These determinants should be incorporated into adherence improving strategies.

A Dynamic Transcriptional Analysis Reveals IL-6 Axis as a Prominent Mediator of Surgical Acute Response in Non-ischemic Mouse Heart

Background

Ischemic heart diseases are a major cause of death worldwide. Different animal models, including cardiac surgery, have been developed over time. Unfortunately, the surgery models have been reported to trigger an important inflammatory response that might be an effect modifier, where involved molecular processes have not been fully elucidated yet.

Objective

We sought to perform a thorough characterization of the sham effect in the myocardium and identify the interfering inflammatory reaction in order to avoid misinterpretation of the data via systems biology approaches.

Methods and Results

We combined a comprehensive analytical pipeline of mRNAseq dataset and systems biology analysis to characterize the acute phase response of mouse myocardium at 0 min, 45 min, and 24 h after surgery to better characterize the molecular processes inadvertently induced in sham animals. Our analysis showed that the surgical intervention induced 1209 differentially expressed transcripts (DETs). The clustering of positively co-regulated transcript modules at 45 min fingerprinted the activation of signalization pathways, while positively co-regulated genes at 24 h identified the recruitment of neutrophils and the differentiation of macrophages. In addition, we combined the prediction of transcription factors (TF) regulating DETs with protein-protein interaction networks built from these TFs to predict the molecular network which have induced the DETs. By mean of this retro-analysis of processes upstream gene transcription, we revealed a major role of the Il-6 pathway and further confirmed a significant increase in circulating IL-6 at 45 min after surgery.

Conclusion

This study suggests that a strong induction of the IL-6 axis occurs in sham animals over the first 24 h and leads to the induction of inflammation and tissues’ homeostasis processes.

An Update on the Multifaceted Roles of STAT3 in the Heart

Signal transducer and activator of transcription 3 (STAT3) is a signaling molecule and transcription factor that plays important protective roles in the heart. The protection mediated by STAT3 is attributed to its genomic actions as a transcription factor and other non-genomic roles targeting mitochondrial function and autophagy. As a transcription factor, STAT3 upregulates genes that are anti-oxidative, anti-apoptotic, and pro-angiogenic, but suppresses anti-inflammatory and anti-fibrotic genes. Its suppressive effects on gene expression are achieved through competing with other transcription factors or cofactors. STAT3 is also linked to the modification of mRNA expression profiles in cardiac cells by inhibiting or inducing miRNA. In addition to these genomic roles, STAT3 is suggested to function protectively in mitochondria, where it regulates ROS production, in part by regulating the activities of the electron transport chain complexes, although our recent evidence calls this role into question. Nonetheless, STAT3 is a key player known to be activated in the cardioprotective ischemic conditioning protocols. Through these varied roles, STAT3 participates in various mechanisms that contribute to cardioprotection against different heart pathologies, including myocardial infarction, hypertrophy, diabetic cardiomyopathy, and peripartum cardiomyopathy. Understanding how STAT3 is involved in the protective mechanisms against these different cardiac pathologies could lead to novel therapeutic strategies to treat them.

Critical appraisal of STAT3 pattern in adult cardiomyocytes

The signal transducer and activator of transcription 3, STAT3, transfers cellular signals from the plasma membrane to the nucleus, acting as a signaling molecule and a transcription factor. Reports proposed an additional non-canonical role of STAT3 that could regulate the activity of complexes I and II of the electron transport chain and the opening of the mitochondrial permeability transition pore (PTP) after ischemia-reperfusion in various cell types. The native expression of STAT3 in heart mitochondria, together with a direct versus an indirect transcriptional role in mitochondrial functions, have been recently questioned. The objective of the present study was to investigate the cellular distribution of STAT3 in mouse adult cardiomyocytes under basal and stress conditions, along with assessing its presence and activity in cardiac mitochondria using structural and functional approaches. The analysis of the spatial distribution of STAT3 signal in the cardiomyocytes interestingly showed that it is transversely distributed along the T-tubules and in the nucleus. This distribution was neither affected by hypoxia nor by hypoxia/re‑oxygenation conditions. Focusing on the mitochondrial STAT3 localization, our results suggest that serine-phosphorylated STAT3 (PS727-STAT3) and total STAT3 are detected in crude but not in pure mitochondria of mouse adult cardiomyocytes, under basal and ischemia-reperfusion conditions. The inhibition of STAT3, with a pre-validated non-toxic Stattic dose, had no significant effects on mitochondrial respiration, but a weak effect on the calcium retention capacity. Overall, our results exclusively reveal a unique cellular distribution of STAT3 in mouse adult cardiomyocytes, along the T-tubules and in nucleus, under different conditions. They also challenge the expression and activity of STAT3 in mitochondria of these cells under basal conditions and following ischemia-reperfusion. In addition, our results underline technical methods, complemental to cell fractionation, to evaluate STAT3 roles during hypoxia-reoxygenation and at the interface between nucleus and endoplasmic reticulum.

Stress and Heart Rate Variability during University Final Examination among Lebanese Students

Real-life stressors, such as university examination, cause an increase in sympathetic activity of the nervous system innervating the heart, and thus an increase in heart rate (HR). Our study aimed to detect changes in heart rate variability (HRV) during different stages of an exam in a group of 90 healthy university students (30 males and 60 females), over 4 h of monitoring divided into 1 h before, 2 h during, and 1 h after the examination. HRV was significantly highest after the exam, indicating release from stress, as compared to before and during the examination when stress was observable. Undergraduate students in different academic years did not differ in terms of stress, indicating the absence of adaptation to exam procedures. However, HR and R-R interval after the exam showed significant difference between first year undergraduate studies and first year of a graduate program, indicating a higher degree of confidence in graduate students. Results also suggest that HRV in females is significantly lower than that in males before and after examination, despite men having greater sympathetic input. In conclusion, the results of our novel study assessing stress in real-time examination show important gender differences, and lack of adaptation with academic study year.

Recent Developments on the Crosstalk Between STAT3 and Inflammation in Heart Function and Disease

The transcription factor STAT3 has a protective function in the heart. Until recently, the role of STAT3 in hypertension-induced cardiac hypertrophy was unsettled. Earlier studies revealed that global reduction of STAT3 activity reduced cardiac hypertrophy with hypertension, but caused a disruption of myofilaments and increased contractile dysfunction. However, newer studies with cardiomyocyte-specific deletion of STAT3 indicate that STAT3 does not cause cardiac hypertrophy with increased blood pressure. Rather, cardiac STAT3 is important for maintaining metabolic homeostasis, and loss of STAT3 in cardiomyocytes makes the heart more susceptible to chronic pathological insult, for example by disrupting glucose metabolism and protective signaling networks via the upregulation of certain microRNAs. This scenario has implications for understanding peripartum cardiomyopathy as well. In viral myocarditis, STAT3 opposes the initiation of the dilated phenotype by maintaining membrane integrity via the expression of dystrophin. STAT3 signaling was also found to attenuate myocarditis by polarizing macrophages to a less inflammatory phenotype. On the other hand, STAT3 contributes to immune-mediated myocarditis due to IL-6-induced complement component C3 production in the liver, as well as the differentiation of Th17 cells, which play a role in initiation and development of myocarditis. Besides canonical signaling pathways, unphosphorylated STAT3 (U-STAT3) and redox-activated STAT3 have been shown to couple to transcription in the heart. In addition, tissue signaling cytokines such as IL-22 and IL-17 have been proposed to have actions on the heart that involve STAT3, but are not fully defined. Understanding the novel and often protective aspects of STAT3 in the myocardium could lead to new therapeutic approaches to treat heart disease.

Targeting Obesity and Diabetes to Treat Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major unmet medical need that is characterized by the presence of multiple cardiovascular and non-cardiovascular comorbidities. Foremost among these comorbidities are obesity and diabetes, which are not only risk factors for the development of HFpEF, but worsen symptoms and outcome. Coronary microvascular inflammation with endothelial dysfunction is a common denominator among HFpEF, obesity, and diabetes that likely explains at least in part the etiology of HFpEF and its synergistic relationship with obesity and diabetes. Thus, pharmacological strategies to supplement nitric oxide and subsequent cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling may have therapeutic promise. Other potential approaches include exercise and lifestyle modifications, as well as targeting endothelial cell mineralocorticoid receptors, non-coding RNAs, sodium glucose transporter 2 inhibitors, and enhancers of natriuretic peptide protective NO-independent cGMP-initiated and alternative signaling, such as LCZ696 and phosphodiesterase-9 inhibitors. Additionally, understanding the role of adipokines in HFpEF may lead to new treatments. Identifying novel drug targets based on the shared underlying microvascular disease process may improve the quality of life and lifespan of those afflicted with both HFpEF and obesity or diabetes, or even prevent its occurrence.

Adherence to treatment and evaluation of disease and therapy knowledge in Lebanese hypertensive patients

BACKGROUND

Adherence to treatment, healthy lifestyle, physical activities, smoking, diet, and salt intake are important factors to control for an effective decrease in blood pressure (BP) values for patients diagnosed with essential hypertension (HT). The aim of this work was to study the adherence to antihypertensive treatment and factors predicting this behavior in Lebanese patients. In addition, we evaluated the extent of patient's knowledge and perceptions about HT, risk factors, and medication side effects.

METHODS

The cross-sectional study was conducted between May and September 2015 among 249 participants randomly recruited from community and hospital pharmacies (56.6%), private cardiology clinics (37%), and outpatient clinics located in hospitals (6.4%) in Baabda region of Lebanon. The questionnaire was prepared after reviewing published literature. Data were collected by trained and certified interviewers and analyzed by Statistical Package for the Social Sciences program. p-value less than 0.05 was considered to determine the statistical significance.

RESULTS

Among the 249 patients interviewed, 48% were females with a mean age of 62±17.2 years. Overweight and obesity was declared in 42.2% and 35.3%, respectively. Only 52.6% of participants reported visiting their physicians for regular checkups, and 72% claimed checking their BP routinely at home. Awareness of complications related to HT was very high (97%). However, our results showed that 89.2% of the participants were found to be adherent to treatment, and forgetfulness was cited as the main reason for non-adherence to therapy. Only health coverage showed statistical significance (p=0.01) between adherent and non-adherent participants.

CONCLUSION

A better communication between patients and their physicians, the use of a special container for medication packaging, and reminder to refill prescriptions are important parameters to enhance adherence to treatment. HT can be better managed if an educational system is implemented to increase awareness.

Macroarray analysis in the hypertrophic left ventricle of renin-dependent hypertensive rats: identification of target genes for renin

Introduction The aim of this work was to identify new renin target genes in left ventricular hypertrophy during hypertension.

Materials and methods We compared left ventricle gene expression from four transgenic TGR(mRen2)27 (TG+/-) rats and four non-transgenic littermates (TG-/-) using cDNA macroarray. Hybridisation signals were quantified with a phosphorimager, and normalised to an external scale. Data analysis was performed with Statistical Analysis for Microarrays (SAM 1.21) software. The mRNA levels of candidate genes were determined by semi-quantitative RT-PCR in three different hypertensive rats: TG+/-, spontaneously hypertensive (SHR) and genetically Lyon hypertensive (LH) rats, compared to their respective controls (TG-/-, Wistar-Kyoto, Lyon low blood pressure rats).

Results Out of 1,200 genes present on the macroarray, 233 were reliably measured and only three were overexpressed (Biglycan, β1-adenosine monophosphate-activated protein kinase [AMPK] and amyloid precursor like protein 2 [APLP2]) and 19 were underexpressed in the left ventricle of TG+/compared with TG-/-. APLP2 is a member of the amyloid precursor protein (APP) family. APLP2 and APP mRNA levels were increased in TGR(mRen2)27 but significantly decreased in LH rats, while only APP was increased in SHR rats.

Conclusions We report new genes associated with renin-dependent left ventricular hypertrophy. Moreover, this work shows for the first time that the APP family gene expression could be altered in response to high renin activity and this effect is independent of cardiac remodelling and hypertension.

Pivotal Importance of STAT3 in Protecting the Heart from Acute and Chronic Stress: New Advancement and Unresolved Issues

The transcription factor, signal transducer and activator of transcription 3 (STAT3), has been implicated in protecting the heart from acute ischemic injury under both basal conditions and as a crucial component of pre- and post-conditioning protocols. A number of anti-oxidant and antiapoptotic genes are upregulated by STAT3 via canonical means involving phosphorylation on Y705 and S727, although other incompletely defined posttranslational modifications are involved. In addition, STAT3 is now known to be present in cardiac mitochondria and to exert actions that regulate the electron transport chain, reactive oxygen species production, and mitochondrial permeability transition pore opening. These non-canonical actions of STAT3 are enhanced by S727 phosphorylation. The molecular basis for the mitochondrial actions of STAT3 is poorly understood, but STAT3 is known to interact with a critical subunit of complex I and to regulate complex I function. Dysfunctional complex I has been implicated in ischemic injury, heart failure, and the aging process. Evidence also indicates that STAT3 is protective to the heart under chronic stress conditions, including hypertension, pregnancy, and advanced age. Paradoxically, the accumulation of unphosphorylated STAT3 (U-STAT3) in the nucleus has been suggested to drive pathological cardiac hypertrophy and inflammation via non-canonical gene expression, perhaps involving a distinct acetylation profile. U-STAT3 may also regulate chromatin stability. Our understanding of how the non-canonical genomic and mitochondrial actions of STAT3 in the heart are regulated and coordinated with the canonical actions of STAT3 is rudimentary. Here, we present an overview of what is currently known about the pleotropic actions of STAT3 in the heart in order to highlight controversies and unresolved issues.

Abstract 110: Importance of the C-Terminal Transactivation Domain of STAT3 in Hypertension-Induced Cardiac Hypertrophy

Signal transducer and activator of transcription 3 (STAT3) is known to have protective effects in the heart in acute oxidative stress such as myocardial infarction; however, the role of STAT3 in the heart in response to chronic stress, such as hypertension, is not defined. Here, we assessed the importance of STAT3 on cardiac remodeling post abdominal aortic constriction (AAC) using mice expressing a STAT3 protein lacking the transactivation domain (TAD; aa701-732) selectively in cardiomyocytes (cm-STAT3Δ). Loss of the TAD region impairs both the mitochondrial and transcriptional actions of STAT3. Both WT and cm-STAT3Δ mice developed hypertension to a comparable extent. However, cm-STAT3Δ mice exhibited a significant (p < 0.01) decline in ejection fraction (58.3 ± 4.7 to 24.2 ± 3.6, n=4) and fractional shortening (30.8 ± 3.4 to 11.2 ± 1.7, n=4) over 28 days following AAC, while WT mice exhibited a compensatory response in EF (58.6 ± 3.2 to 59.4 ± 6.0) and FS (30.7 ± 2.1 to 33.0 ± 2.8). Notably, hearts of cm-STAT3Δ exhibited a marked increase in diastolic left ventricular internal diameter (LVIDd), symptomatic of eccentric hypertrophy and dilated cardiomyopathy. In contrast, the pattern of change in LVIDd for WT mice was consistent with concentric remodeling. Banding caused comparable increases in heart to body weight ratios in WT (4.1 ± 0.1 to 6.4 ± 1.0) and cm-STAT3Δ (4.0 ± 0.1 to 7.2 ± 0.6) mice, although on average the increase was larger in cm-STAT3Δ mice. Interestingly, we also found that miR-199a-5p levels were only moderately higher (36%) after AAC in the ventricles of cm-STAT3Δ mice vs. wild type hearts as compared to cardiomyocyte-targeted STAT3 KO mice in which the DNA binding domain of STAT3 is deleted. miR-199a-5p is a known inhibitor of peroxisome proliferator-activated receptor delta (PPARδ) expression and mitochondrial fatty acid oxidation in the heart. These new findings emphasize the distinctive and important role of the C-terminus of STAT3 in the hypertrophic response of the heart to hypertension and the progression to heart failure.

Applying fractal dimension and image analysis to quantify fibrotic collagen deposition and organization in the normal and hypertensive heart

Hearts of mice with reduction of function mutation in STAT3 (SA/SA) develop fibrotic collagen foci and reduced systolic function with hypertension. This model was used to determine if fractal dimension and image analysis can provide a quantitative description of myocardial fibrosis using routinely prepared trichome-stained material. Collagen was characterized by relative density [integrated optical density/area (IOD/A)] and fractal dimension (D), an index of complexity. IOD/A of collagen in wild type mice increased with hypertension while D decreased, suggesting tighter collagen packing that could eventually stiffen the myocardium as in diastolic heart failure. Reduced STAT3 function caused modest collagen fibrosis with increased IOD/A and D, indicating more tightly packed, but more disorganized collagen than normotensive and hypertensive controls. Hypertension in SA/SA mice resulted in large regions where myocytes were lost and replaced by fibrotic collagen characterized by decreased density and increased disorder. This indicates that collagen associated with reparative fibrosis in SA/SA hearts experiencing hypertension was highly disorganized and more space filling. Loss of myocytes and their replacement by disordered collagen fibers may further weaken the myocardium leading to systolic heart failure. Our findings highlight the utility of image analysis in revealing importance of a cellular protein for normal and reparative extracellular matrix deposition.

Loss of STAT3 in mouse embryonic fibroblasts reveals its Janus-like actions on mitochondrial function and cell viability

STAT3 has been implicated in mitochondrial function; however, the physiological relevance of this action is not established. Here we studied the importance of STAT3 to the cellular response to stimuli, TNFα and serum deprivation, which increase mitochondrial reactive oxygen species (ROS) formation. Experiments were performed using wild type (WT) and STAT3 knockout (KO) mouse embryonic fibroblasts (MEF). Both WT and STAT3 KO MEF expressed similar levels of tumor necrosis factor receptor 1 (TNFR1) and exhibited comparable IκBα degradation with TNFα. However, in the absence of STAT3 nuclear accumulation of NFκB p65 with TNFα was attenuated and induction of the survival protein c-FLIPL was eliminated. Nonetheless, WT MEF were more sensitive to TNFα-induced death which was attributed to necrosis. Deletion of STAT3 decreased ROS formation induced by TNFα and serum deprivation. STAT3 deletion was associated with lower levels of complex I and rates of respiration. Relative to WT cells, mitochondria of STAT3 KO cells released significantly more cytochrome c in response to oxidative stress and had greater caspase 3 cleavage due to serum deprivation. Our findings are consistent with STAT3 being important for mitochondrial function and cell viability by ensuring mitochondrial integrity and the expression of pro-survival genes.

Abstract 387: Role of STAT3 in Collagen Deposition and Organization in the Normal and Hypertensive Heart

Hypertension causes concentric hypertrophy of the left ventricle that may progress to systolic heart failure by means not defined. We reported that mice with a S727A reduced function mutation in STAT3 have reduced systolic function with angiotensin II (Ang II)-induced hypertension and foci of fibrotic collagen in the myocardium as occurs in hypertensive heart disease. We applied image analysis of relative density (IOD/A) and fractal dimension (D) to quantify foci. Hypertension in WT mice did not affect % area and relative density, but D values decreased (P<0.001) suggesting tighter packing of fibrotic collagen stiffening the myocardium. SA/SA+saline hearts showed significant increases in fibrotic collagen (P=0.025) and density (P<0.001) vs. WT hearts. D values indicate an increase (P=0.002) in chaos of collagen matrix. In SA/SA mice Ang II caused remodeling of myocardial collagen with loss of myocytes within fibrotic foci. Hypertension in SA/SA hearts induced further increase (P<0.001) in collagen, while the relative density was significantly less (P=0.015) than the SA/SA+saline group but greater than WT+saline and WT+Ang II groups. The decrease in collagen density was associated with a large (P<0.001) increase in D values, indicating collagen in fibrotic foci was highly disorganized and more space filling. Loss of myocytes and their replacement by chaotic and randomly organized collagen may further weaken the myocardium leading to systolic heart failure. Our results show that STAT3 is essential in normal regulation and organization of the collagen matrix in the heart. Suppression of STAT3 results in fibrotic lesions in the myocardium that are exacerbated by hypertension.

Differential STAT3 signaling in the heart: Impact of concurrent signals and oxidative stress

Multiple lines of evidence suggest that the transcription factor STAT3 is linked to a protective and reparative response in the heart. Thus, increasing duration or intensity of STAT3 activation ought to minimize damage and improve heart function under conditions of stress. Two recent studies using genetic mouse models, however, report findings that appear to refute this proposition. Unfortunately, studies often approach the question of the role of STAT3 in the heart from the perspective that all STAT3 signaling is equivalent, particularly when it comes to signaling by IL-6 type cytokines, which share the gp130 signaling protein. Moreover, STAT3 activation is typically equated with phosphorylation of a critical tyrosine residue. Yet, STAT3 transcriptional behavior is subject to modulation by serine phosphorylation, acetylation, and redox status of the cell. Unphosphorylated STAT3 is implicated in gene induction as well. Thus, how STAT3 is activated and also what other signaling events are occurring at the same time is likely to impact on the outcome ultimately linked to STAT3. Notably STAT3 may serve as a scaffold protein allowing it to interact with other singling pathways. In this context, canonical gp130 cytokine signaling may function to integrate STAT3 signaling with a protective PI3K/AKT signaling network via mutual involvement of JAK tyrosine kinases. Differences in the extent of integration may occur between those cytokines that signal through gp130 homodimers and those through heterodimers of gp130 with a receptor α chain. Signal integration may have importance not only for deciding the particular gene profile linked to STAT3, but for the newly described mitochondrial stabilization role of STAT3 as well. In addition, disruption of integrated gp130-related STAT3 signaling may occur under conditions of oxidative stress, which negatively impacts on JAK catalytic activity. For these reasons, understanding the importance of STAT3 signaling to heart function requires a greater appreciation of the plasticity of this transcription factor in the context in which it is investigated.

Dancing rhinos in stilettos: The amazing saga of the genomic and nongenomic actions of STAT3 in the heart

A substantial body of evidence has shown that signal transducer and activator of transcription 3 (STAT3) has an important role in the heart in protecting the myocardium from ischemia and oxidative stress. These actions are attributed to STAT3 functioning as a transcription factor in upregulating cardioprotective genes. Loss of STAT3 has been implicated as well in the pathogenesis of heart failure and, in that context and in addition to the loss of a cardioprotective gene program, nuclear STAT3 has been identified as a transcriptional repressor important for the normal functioning of the ubiquitin-proteasome system for protein degradation. The later finding establishes a genomic role for STAT3 in controlling cellular homeostasis in cardiac myocytes independent of stress. Surprisingly, although a well-studied area, very few downstream gene targets of STAT3 in the heart have been definitively identified. In addition, STAT3 is now known to induce gene expression by noncanonical means that are not well characterized in the heart. On the other hand, recent evidence has shown that STAT3 has important nongenomic actions in cardiac myocytes that affect microtubule stability, mitochondrial respiration, and autophagy. These extranuclear actions of STAT3 involve protein–protein interactions that are incompletely understood, as is their regulation in both the healthy and injured heart. Moreover, how the diverse genomic and nongenomic actions of STAT3 crosstalk with each other is unchartered territory. Here we present an overview of what is and is not known about both the genomic and nongenomic actions of STAT3 in the heart from a structure-function perspective that focuses on the impact of posttranslational modifications and oxidative stress in regulating the actions and interactions of STAT3. Even though we have learnt a great deal about the role played by STAT3 in the heart, much more awaits to be discovered.

Role of STAT3 in angiotensin II-induced hypertension and cardiac remodeling revealed by mice lacking STAT3 serine 727 phosphorylation

STAT3 is involved in protection of the heart provided by ischemic preconditioning. However, the role of this transcription factor in the heart in chronic stresses such as hypertension has not been defined. We assessed whether STAT3 is important in hypertension-induced cardiac remodeling using mice with reduced STAT3 activity due to a S727A mutation (SA/SA). Wild type (WT) and SA/SA mice received angiotensin (ANG) II or saline for 17 days. ANG II increased mean arterial and systolic pressure in SA/SA and WT mice, but cardiac levels of cytokines associated with heart failure were increased less in SA/SA mice. Unlike WT mice, hearts of SA/SA mice showed signs of developing systolic dysfunction as evidenced by reduction in ejection fraction and fractional shortening. In the left ventricle of both WT and SA/SA mice, ANG II induced fibrosis. However, fibrosis in SA/SA mice appeared more extensive and was associated with loss of myocytes. Cardiac hypertrophy as indexed by heart to body weight ratio and left ventricular anterior wall dimension during diastole was greater in WT mice. In WT+ANG II mice there was an increase in the mass of individual myofibrils. In contrast, cardiac myocytes of SA/SA+ANG II mice showed a loss in myofibrils and myofibrillar mass density was decreased during ANG II infusion. Our findings reveal that STAT3 transcriptional activity is important for normal cardiac myocyte myofibril morphology. Loss of STAT3 may impair cardiac function in the hypertensive heart due to defective myofibrillar structure and remodeling that may lead to heart failure.

Abstract 71: STAT3 Affects Myofibrillar Structure and Its Loss May Contribute to Heart Failure in Hypertension

How hypertension causes heart failure is not known. Since patients with heart failure have reduced cardiac STAT3 and STAT3 KO mice develop heart failure with age, we tested the hypothesis that reduced STAT3 transcriptional activity contributes at an early stage to remodeling that precedes heart failure in hypertension using SA mice with a STAT3 S727A mutation. SA and wild type (WT) mice received angiotensin (A) II (1000 ng/kg/min) or saline (S) for 17 days. Hearts of WT and SA mice had similar levels of STAT3-induced protective proteins Bcl-xL and SOD2, and unlike STAT3 KO mice, cardiac miR-199a levels were not increased in SA mice. AII increased systolic blood pressure measured by telemetry in SA (124 ± 1 to 167 ± 3) and WT (122 ± 3 to 162 ± 3) mice to the same extent. AII increased cardiac levels of cytokines (pg/μg protein) associated with heart failure in both WT and SA mice, but significantly less so (P<0.05) in SA mice; IL-6, 13.6 ± 1.4 vs. 9.1 ± 0.6; TGFβ, 56 ± 4 vs. 38 ± 3 and MCP1 35 ± 2 vs. 22 ± 2. Compared to WT mice, hearts of SA mice showed signs of developing systolic dysfunction with AII as seen by a significant (P<0.05) reduction in ejection fraction (63.7 ± 7.1 to 51.7 ± 6.9) and fractional shortening (34.3 ± 4.9 to 26.4 ± 4.3). AII caused fibrosis in the left ventricle of both WT and SA mice characterized by cardiac myocyte loss and increased % collagen: WT+S, 5.59 ± 0.34; WT+AII, 15.70 ± 1.87; SA+S, 6.70 ± 0.40; SA+AII, 16.50 ± 1.91. In WT+AII mice there was a nonsignificant trend towards a loss of myofibrillar content of cardiac myocytes, but an increase in the mass of the myofibrils (IOD/myofibrillar area). In contrast, cardiac myocytes of SA+AII mice had a significant (P<0.001) % loss in myofibrils (5.71 ± 0.28) compared to SA+S (0.75 ± 0.07), WT+S (0.80 ± 0.06) and WT+AII (1.54 ± 0.10) mice. In addition, the mass of the myofibrils in SA+AII mice (6.01 ± 0.07) was significantly less (P<0.001) than those of SA+S mice (6.46 ± 0.04), although greater than WT+S (4.85 ± 0.06) or WT+AII (5.27 ± 0.08) mice. Our findings reveal that STAT3 transcriptional activity is important for proper morphology of the myofibrils of cardiac myocytes. Loss of STAT3 activity may impair cardiac function in the hypertensive heart due to defective myofibrillar structure and remodeling that may lead to heart failure.

Abstract 219: Acyloxy Nitroso Compounds Inhibit LIF Signaling in Endothelial Cells and Cardiac Myocytes: Evidence That STAT3 Signaling is Redox-Sensitive

Nitroxyl donors have positive inotropic and lusitropic effects that may have therapeutic potential for treating heart failure, but their effects on other signaling pathways are not well studied. Previously we showed that leukemia inhibitory factor (LIF)-induced signaling is inhibited by oxidative stress, which targets JAK1 activation. In addition, we recently reported evidence for a cysteine-based redox switch in the JH1 catalytic domain of JAK 1 and 2. Since nitroxyl is thiophylic, we postulated that nitroxyl donors would inhibit LIF-induced JAK-STAT3 activation. Pretreatment of human microvascular endothelial cells (HMEC-1) or neonatal rat ventricular myocytes with the nitroxyl donors Angeli’s salt and the recently-described nitrosocyclohexyl acetate (NCA) inhibited LIF-induced STAT3 activation as indexed by Y705 phosphorylation. Pretreatment of HMEC-1 with NCA also blocked LIF-induced expression of the inflammation-related genes, ICAM-1 and CEBPD. The related acyloxy nitroso compound 1-nitrosocyclohexyl pivalate (NCP), which is not a nitroxyl donor, was equally effective in inhibiting STAT3 activation, suggesting that these compounds were acting as electrophiles on a thiolate residue. NCA had no effect on the catalytic activity of JAK1 and modestly affected JAK1-induced tyrosine phosphorylation of the LIF receptor. Thus, the JH1 redox switch is not a direct target of the acyloxy nitroso compound. However, pretreatment of recombinant human STAT3 with NCA or NCP reduced the labeling of free sulfhydryl residues with fluorescein-5-maleimide. In addition, we document by dimedone labeling that oxidation of STAT3 is associated with formation of sulfenic acid residues, a hallmark of redox-sensitive proteins. Altogether our evidence indicates that STAT3 has redox-sensitive cysteines that regulate its activation and are targeted by nitroxyl donors and related acyloxy nitroso compounds. These findings raise the possibility of new therapeutic strategies to target STAT3 signaling.

Depletion of cellular glutathione modulates LIF-induced JAK1-STAT3 signaling in cardiac myocytes

Previously we reported that the sesquiterpene lactone parthenolide induces oxidative stress in cardiac myocytes, which blocks Janus kinase (JAK) activation by the interleukin 6 (IL-6)-type cytokines. One implication suggested by this finding is that IL-6 signaling is dependent upon cellular anti-oxidant defenses or redox status. Therefore, the present study was undertaken to directly test the hypothesis that JAK1 signaling by the IL-6-type cytokines in cardiac myocytes is impaired by glutathione (GSH) depletion, since this tripeptide is one of the major anti-oxidant molecules and redox-buffers in cells. Cardiac myocytes were pretreated for 6h with l-buthionine-sulfoximine (BSO) to inhibit GSH synthesis. After 24h, cells were dosed with the IL-6-like cytokine, leukemia inhibitory factor (LIF). BSO treatment decreased GSH levels and dose-dependently attenuated activation of JAK1, Signal Transducer and Activator of Transcription 3 (STAT3), and extracellular signal regulated kinases 1 and 2 (ERK1/2). Addition of glutathione monoethyl ester, which is cleaved intracellularly to GSH, prevented attenuation of LIF-induced JAK1 and STAT3 activation, as did the reductant N-acetyl-cysteine. Unexpectedly, LIF-induced STAT1 activation was unaffected by GSH depletion. Evidence was found that STAT3 is more resistant than STAT1 to intermolecular disulfide bond formation under oxidizing conditions and more likely to retain the monomeric form, suggesting that conformational differences explain the differential effect of GSH depletion on STAT1 and STAT3. Overall, our findings indicate that activation of both JAK1 and STAT3 is redox-sensitive and the character of IL-6 type cytokine signaling in cardiac myocytes is sensitive to changes in the cellular redox status. In cardiac myocytes, activation of STAT1 may be favored over STAT3 under oxidizing conditions due to GSH depletion and/or augmented reactive oxygen species production, such as in ischemia-reperfusion and heart failure.

Acyloxy nitroso compounds inhibit LIF signaling in endothelial cells and cardiac myocytes: evidence that STAT3 signaling is redox-sensitive

We previously showed that oxidative stress inhibits leukemia inhibitory factor (LIF) signaling by targeting JAK1, and the catalytic domains of JAK 1 and 2 have a cysteine-based redox switch. Thus, we postulated that the NO sibling and thiophylic compound, nitroxyl (HNO), would inhibit LIF-induced JAK-STAT3 activation. Pretreatment of human microvascular endothelial cells (HMEC-1) or neonatal rat cardiomyocytes with the HNO donors Angeli’s salt or nitrosocyclohexyl acetate (NCA) inhibited LIF-induced STAT3 activation. NCA pretreatment also blocked the induction of downstream inflammatory genes (e.g. intercellular adhesion molecule 1, CCAAT/enhancer binding protein delta). The related 1-nitrosocyclohexyl pivalate (NCP; not a nitroxyl donor) was equally effective in inhibiting STAT3 activation, suggesting that these compounds act as thiolate targeting electrophiles. The JAK1 redox switch is likely not a target of acyloxy nitroso compounds, as NCA had no effect on JAK1 catalytic activity and only modestly affected JAK1-induced phosphorylation of the LIF receptor. However, pretreatment of recombinant human STAT3 with NCA or NCP reduced labeling of free sulfhydryl residues. We show that NCP in the presence of diamide enhanced STAT3 glutathionylation and dimerization in adult mouse cardiac myocytes and altered STAT3 under non-reducing conditions. Finally, we show that monomeric STAT3 levels are decreased in the Gαq model of heart failure in a redox-sensitive manner. Altogether, our evidence indicates that STAT3 has redox-sensitive cysteines that regulate its activation and are targeted by HNO donors and acyloxy nitroso compounds. These findings raise the possibility of new therapeutic strategies to target STAT3 signaling via a redox-dependent manner, particularly in the context of cardiac and non-cardiac diseases with prominent pro-inflammatory signaling.

Selenate enhances STAT3 transcriptional activity in endothelial cells: differential actions of selenate and selenite on LIF cytokine signaling and cell viability

Sodium selenate may have utility in treating Alzheimer's disease and diabetes; however, its impact on the associated proinflammatory cytokine signaling of endothelial cells has not been investigated. We report that treatment of human microvascular endothelial cells with sodium selenate at a pharmacological dose (100 μM) enhanced tyrosine phosphorylation of nuclear STAT3 on Y705 in response to IL-6-type cytokine, leukemia inhibitory factor (LIF), indicative of enhanced STAT3 activity. Accordingly, STAT3 nuclear binding to DNA was increased, as well as LIF-induced gene expression of chemokine (C-C motif) ligand 2 (CCL2). CCL2 plays a key role in inflammatory processes associated with neuronal degenerative and vascular diseases. The enhancing action of selenate on LIF-induced STAT3 Y705 phosphorylation was replicated by vanadate and a specific inhibitor of protein tyrosine phosphatase, non-receptor type 1 (PTP1B). Moreover, we observed that selenite, the cellular reduction bioproduct of selenate but not selenate itself, inhibited enzymatic activity of human recombinant PTP1B. Our findings support the conclusion that in human microvascular endothelial cells selenate has a vanadate-like effect in inhibiting PTP1B and enhancing proinflammatory STAT3 activation. These findings raise the possibility that beneficial actions of supranutritional levels of selenate for treating Alzheimer's and diabetes may be offset by a proinflammatory action on endothelial cells.

Calyculin A reveals serine/threonine phosphatase protein phosphatase 1 as a regulatory nodal point in canonical signal transducer and activator of transcription 3 signaling of human microvascular endothelial cells

Vascular inflammation is initiated by stimuli acting on endothelial cells. A clinical feature of vascular inflammation is increased circulating interleukin 6 (IL-6) type cytokines such as leukemia inhibitory factor (LIF), but their role in vascular inflammation is not fully defined. IL-6 type cytokines activate transcription factor signal transducer and activator of transcription 3 (STAT3), which has a key role in inflammation and the innate immune response. Canonical STAT3 gene induction is due to phosphorylation of (1) Y705, leading to STAT3 dimerization and DNA binding and (2) S727, enhancing homodimerization and DNA binding by recruiting p300/CBP. We asked whether enhancing S727 STAT3 phosphorylation using the protein phosphatase 1 (PP1) inhibitor, calyculin A, would enhance LIF-induced gene expression in human microvascular endothelial cells (HMEC-1). Cotreatment with calyculin A and LIF markedly increased STAT3 S727 phosphorylation, without affecting the increase in the nuclear fraction of STAT3 phosphorylated on Y705. PP2A inhibitors, okadaic acid and fostriecin, did not enhance STAT3 S727 phosphorylation. Surprisingly, calyculin A eliminated LIF-induced gene expression: (1) calyculin A reduced binding of nuclear extracts to a STAT3 consensus site, thereby reducing the overall level of binding observed with LIF; and (2) calyculin A caused p300/CBP phosphorylation, thus resulting in reduced acetylation activity and degradation. Together, these findings reveal a pivotal role of a protein serine/threonine phosphatases that is likely PP1 in HMEC in controlling STAT3 transcriptional activity.

Hydrogels as a platform for stem cell delivery to the heart

Stem cell therapy offers great promise to repair the injured or failing heart. The outcomes of clinical trials to date, however, have shown that the actual benefit realized falls far short of the promise. A number of factors may explain why that is the case, but poor stem cell retention and engraftment in the hostile environment of the injured heart would seem to be a major factor. Improving stem cell retention and longevity once delivered would seem a logical means to enhance their reparative function. One way to accomplish this goal may be injectable hydrogels, which would serve to fix stem cells in place while providing a sheltering environment. Hydrogels also provide a means to allow for the paracrine factors produced by encapsulated stem cells to diffuse into the injured myocardium. Alternatively, hydrogels themselves can be used for the sustained delivery of reparative factors. Here the authors discuss chitosan-based hydrogels.