Diuretic use and outcomes in patients with heart failure with reduced ejection fraction: Insights from the VICTORIA trial

AIMS

In VICTORIA, vericiguat compared with placebo reduced the risk of cardiovascular death (CVD) and heart failure hospitalization (HFH) in patients enrolled after a worsening heart failure (WHF) event. We examined clinical outcomes and efficacy of vericiguat as it relates to background use of loop diuretics in patients with WHF.

METHODS AND RESULTS

We calculated the total daily loop diuretic dose equivalent to furosemide dosing at randomization and categorized these as: no loop diuretic, 1-39, 41-80, 40, and >80 mg total daily dose (TDD). The primary composite outcome of CVD/HFH and its components were evaluated based on TDD loop diuretic and expressed as adjusted hazard ratios with 95% confidence intervals. Post-randomization rates of change in TDD were also examined. Of 4974 patients (98% of the trial) with diuretic dose information available at randomization, 540 (10.8%) were on no loop diuretic, 647 (13.0%) were on 1-39, 1633 (32.8%) were on 40, 1185 (23.8%) were on 41-80, and 969 (19.4%) were on >80 mg TDD. Patients with higher TDD had a higher rate of primary and secondary clinical outcomes. There were no significant interactions with TDD at randomization and efficacy of vericiguat versus placebo for any outcome (all pinteraction  > 0.5). Post-randomization diuretic dose changes for vericiguat and placebo showed similar rates of up-titration (19.6 and 20.2/100 person-years), down-titration (16.8 and 18.1/100 person-years), and stopping diuretics (22.9 and 24.2/100 person-years).

CONCLUSIONS

Loop diuretic TDD at randomization was independently associated with worse outcomes in this high-risk population. The efficacy of vericiguat was consistent across the range of diuretic doses.

Recurrent heart failure hospitalizations increase the risk of mortality in heart failure patients with atrial fibrillation and type 2 diabetes mellitus in the United Kingdom: a retrospective analysis of Clinical Practice Research Datalink database

BACKGROUND

Heart failure (HF) is a global illness and is a leading cause of hospitalizations. Recurrent HF hospitalization (HFH) is associated with increased risk of cardiovascular (CV) and all-cause mortality, thereby burdening the health system. Type 2 diabetes mellitus (T2DM) and atrial fibrillation (AF) are two important comorbidities in patients living with HF. This study aims to assess the association between recurrent HFHs with CV and all-cause mortality in patients living with HF and having AF and/or T2DM.

METHODS

This study was conducted using primary care data from the Clinical Practice Research Datalink database with linkage to hospital data and mortality data. Adults living with HF and with at least 1 HFH were identified from January 2010 to December 2014. Patients were grouped based on the number of recurrent HFHs. During follow-up, all-cause mortality or CV mortality for the HF population with AF and T2DM was recorded.

RESULTS

Overall, 32.9% of 2344 T2DM patients and 28.2% of 4585 AF patients had at least 1 recurrent HFH. The patients were relatively elderly and were predominantly male. The mean number of all-cause hospitalizations in HF patients having T2DM and AF, with ≥ 1 recurrent HFH were significantly higher than patients without recurrent HFH. The annualized mortality rates in CV mortality as the primary cause and for all-cause mortality and increased with recurrent HFHs, in T2DM and AF patients. The risk of CV mortality as primary cause and all cause morality were 5.39 and 3.19 times higher in T2DM patients with 3 recurrent HFHs versus no recurrent HFH. Similarly, the risk of CV mortality as primary cause and all cause morality was 5.98 and 4.3 times higher in AF patients with 3 recurrent HFHs versus those with no recurrent HFH.

CONCLUSIONS

Recurrent HFHs are strongly associated with CV mortality and all-cause mortality in HF patients with TD2M or AF. The hospitalization rate highlights the need for treatment and disease management, which will improve the course of the disease and help patients stay out of hospital.

Recurrent heart failure hospitalizations increase the risk of cardiovascular and all-cause mortality in patients with heart failure in Sweden: a real-world study

Aims

Heart failure (HF) is a leading cause of hospitalization and is associated with high morbidity and mortality. We examined the impact of recurrent HF hospitalizations (HFHs) on cardiovascular (CV) mortality among patients with HF in Sweden.

Methods and results

Adults with incident HF were identified from linked national health registers and electronic medical records from 01 January 2005 to 31 December 2013 for Uppsala and until 31 December 2014 for Västerbotten. CV mortality and all‐cause mortality were evaluated. A time‐dependent Cox regression model was used to estimate relative CV mortality rates for recurrent HFHs. Assessment was also done for ejection fraction‐based HF phenotypes and for comorbid atrial fibrillation, diabetes, or chronic renal impairment. Overall, 3878 patients with HF having an index hospitalization were included, providing 9691.9 patient‐years of follow‐up. Patients were relatively old (median age: 80 years) and were more frequently male (55.5%). Compared with patients without recurrent HFHs, the adjusted hazard ratio (HR [95% confidence interval; CI]) for CV mortality and all‐cause mortality were statistically significant for patients with one, two, three, and four or more recurrent HFHs. The risk of CV mortality and all‐cause mortality increased approximately six‐fold in patients with four or more recurrent HFHs vs. those without any HFHs (HR [95% CI]: 6.26 [5.24–7.48] and 5.59 [4.70–6.64], respectively). Similar patterns were observed across the HF phenotypes and patients with comorbidities.

Conclusions

There is a strong association between recurrent HFHs and CV and all‐cause mortality, with the risk increasing progressively with each recurrent HFH.

Real-world effectiveness and safety of sacubitril/valsartan in heart failure: A systematic review

BACKGROUND

PARADIGM-HF demonstrated superiority of sacubitril/valsartan (sac/val) over enalapril in patients with heart failure with reduced ejection fraction (HFrEF). However, patients in clinical practice may differ in their characteristics and overall risk compared with patients in clinical trials, and additional outcomes can be observed in real world (RW). Hence, a systematic review was conducted to identify and describe RW data on sac/val.

METHODS

RW studies evaluating the effects of sac/val in adult patients with HFrEF with a sample size ≥100 were identified via MEDLINE® and Embase® from 2015 to January 2020. Citations were screened, critically appraised and relevant data were extracted.

RESULTS

A total of 68 unique studies were identified. Nearly half of the studies were conducted in Europe (n = 34), followed by the US (n = 15) and Asia (n = 11). Median follow-up period varied from 1 to 19 months. Mean age ranged between 48.7 and 79.0 years; patients were mostly male and in New York Heart Association (NYHA) functional class II/III, and mean left ventricular ejection fraction varied between 23%and 38%. Of studies performing comparisons, most reported superior efficacy of sac/val in reducing the risk of HF hospitalisations, all-cause hospitalisations, and all-cause mortality as compared to standard-of-care. Many studies reported significant improvements in NYHA functional class and reduction in biomarker levels post sac/val. Hypotension and hyperkalaemia were the most frequently reported adverse events.

CONCLUSIONS

This comprehensive overview of currently available RW evidence on sac/val complements the evidence from randomised controlled trials, substantiating its effectiveness in heterogeneous real-world HF populations.

Caregivers of Patients with Heart Failure: Burden and the Determinants of Health-Related Quality of Life

PURPOSE

To assess the burden among caregivers of patients with heart failure (HF) with left ventricular ejection fraction (LVEF) ≤60%. The burden by New York Heart Association (NYHA) functional class was also characterized.

PATIENTS AND METHODS

A cross-sectional study was conducted in France, Germany, Italy, Spain, and UK from June to November 2019. Patient record forms were completed by 257 cardiologists and 158 general practitioners for consecutive HF patients. Caregivers who accompanied the patient to their consultation completed a caregiver self-completion survey voluntarily, which included the Family Caregiver Quality of Life Questionnaire (FAMQOL) and 5-level 5-dimension EuroQol questionnaire (EQ-5D-5L).

RESULTS

We analyzed 361 caregivers of patients with HF (NYHA class I, n=41; II, n=212; III IV, n=108). Mean age of caregivers was 58.8 years (NYHA I/II/III-IV: 59.1/60.8/54.6 years; p=0.0029), with majority being females (73.1%). Caregivers spent on average 19.8 hours/week caring for a HF patient, which increased with increase in NYHA class (I/II/III-IV: 11.8/18.1/25.9 hours/week; p=0.0094). Caregivers (24.1%) reported providing emotional support/encouragement to patients as the most troublesome/inconvenient caregiving activity (no significant difference across NYHA class). Nearly one-third of caregivers experienced stress (NYHA I/II/III-IV: 17.1%/28.8%/40.7%; p=0.0111) and anxiety (26.8%/24.1%/39.8%; p=0.0127) due to caregiving burden. The overall FAMQOL mean score decreased significantly (poorer QoL) with increase in NYHA class (I/II/III-IV: 58.1/56.3/52.2; p=0.0069). A trend of decreasing scores with increasing NYHA class was observed across physical, emotional, and social domains (each p≤0.012).

CONCLUSION

Caregivers of HF patients with LVEF ≤60% experienced a significant burden, which was higher among caregivers of patients with more severe and symptomatic disease.

Burden and Quality of Life Among Female and Male Patients with Heart Failure in Europe: A Real-World Cross-Sectional Study

PURPOSE

To characterize symptoms, clinical burden, and health-related quality of life (HRQoL) among women and men with heart failure (HF) with a left ventricular ejection fraction (LVEF) of ≤60% in Europe.

PATIENTS AND METHODS

A real-world cross-sectional study was conducted in France, Germany, Italy, Spain, and United Kingdom from June to November 2019. Patient record forms were completed by 257 cardiologists and 158 general practitioners for consecutive patients with HF. The same patients were invited to complete a questionnaire comprising patient-reported outcomes: the Minnesota Living with Heart Failure Questionnaire (MLHFQ), five-level five-dimension EuroQol questionnaire (EQ-5D-5L), Visual Analogue Scale (VAS), and Work Productivity and Activity Impairment questionnaire.

RESULTS

The mean age of 804 patients (men, n=517; women, n=287) was 68.6 years (men, 67.8 years; women, 70.2 years; p=0.0022). The mean LVEF was 44.7% (men, 43.6%; women, 46.8%; p<0.0001). Patients reported dyspnoea when active (overall, 55.7%; men, 56.0%; women, 55.3%), fatigue/weakness/faintness (34.5%; men, 32.9%; women, 37.2%), and oedema (20.3%; men, 18.7%; women, 23.1%) as the most troublesome HF symptoms. Overall, 54.1% of patients reported low mood/depression (men, 50.8%; women, 60.1%). The overall MLHFQ mean score was higher (ie, poorer HRQoL) among women vs men (37.9 vs 34.6; p=0.0481). MLHFQ was consistently higher (ie, poorer HRQoL) for women vs men across the physical (18.6 vs 16.6; p=0.0041) and emotional (9.4 vs 7.9; p=0.0021) scoring domains. Mean EQ-5D utility (0.69 vs 0.75; p=0.0046) and VAS scores (55.4 vs 61.3; p<0.0001) were lower among women compared with men. Overall, 23.4% of patients were hospitalized owing to HF in the previous year (men, 22.7%; women, 24.6%). Patients reported 43.2% activity impairment due to HF (men, 41.6%; women, 46.4%; p=0.01).

CONCLUSION

HF causes a substantial burden on patients, with a greater burden among women vs men. This gender-related difference is consistent with other HF studies, warranting further research to understand the underlying reasons.

Caregiver burden of patients with heart failure with a left-ventricular ejection fraction (LVEF) less than or equal to 60%: a cross-sectional survey in the EU

Background and purpose

The majority of patients with heart failure (HF) have difficulties in independently carrying out activities of daily living and hence, require support from caregivers (CGs). This study assessed the quality of life (QoL) of CGs of HF patients with sub-normal LVEF (≤60%).

Methods

A cross-sectional survey of HF patients and their CGs was conducted in France, Germany, Italy, Spain and the UK. Cardiologists and primary care physicians completed patient record forms (PRF) between June and November 2019. Caregivers of the same patients were invited to complete a caregiver self-completion survey, which included the Family Caregiver QoL Scale (FAMQOL) and EQ-5D. Patient demographics were derived from PRFs.

Results

361 CGs (73.1% female, mean age: 58.8 yrs) and HF patients (39.9% female, mean age: 71.2 yrs) were included. 58.2% of the CGs were spouses, 23.4% a child of the patient. On average, CGs devoted 20 hrs/week in the care of HF patients; this CG time increased from 12 to 26 hrs/week with NYHA class I to III/IV of the HF patient. Further, anxiety/stress was experienced overall by 29/31% of CGs which increased from 27/17% for NYHA I to 40/41% for NYHA III/IV of the HF patient (Table 1).

Conclusions

Caregivers of patients with HF and LVEF ≤60% spend a significant amount of time to provide daily support to HF patients. Patients with progressive disease were older, more polymorbid and had a higher disease duration. These factors likely contributed towards increased caregiver burden of HF patients with increased NYHA class.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Novartis Pharma AG

A real-world assessment of the burden associated with hospitalizations in US patients with heart failure and left ventricular ejection fraction (LVEF) greater than 40%

Background and purpose

Heart failure (HF) is one of the leading causes of hospitalization among older adults and is associated with a large burden of disease for the individual, the patient's family, healthcare systems, and society. This study assessed the burden of hospitalizations in patients with HF with LVEF &gt;40% in the United States (US).

Methods

This retrospective, non-interventional study identified adult patients with incident or prevalent HF in Optum® de-identified Electronic Health Record (EHR) dataset (2007–2018) between 01/01/2013 and 31/12/2017. Optum's longitudinal EHR repository is derived from dozens of healthcare provider organizations in the US, that include more than 700 Hospitals and 7000 Clinics; treating &gt;95 million patients receiving care in the US. Patients were followed for up to 1 year or until last active date whichever occurred first. Comorbidities, all-cause hospitalizations (AcH) and primary cause HF hospitalizations (HFH) were analysed.

Results

120,606 patients with HF and LVEF &gt;40% (54% female) with a mean (SD) age of 71 (13) yrs were included, representing 80,324.74 patient-yrs follow-up (days). Common comorbidities were hypertension (91.8%), ischemic heart disease (IHD, 71.4%), atrial fibrillation (AF, 54.8%), renal disease (54.1%), type 2 diabetes (T2D, 50.7%), obesity (44.6%) and anemia (39%). Comorbidities including IHD (72.9% vs. 68.4%), AF (56.4% vs. 51.6%) and T2D (51.1% vs. 49.9%) were more often recorded in patients with LVEF &gt;40-≤60% than &gt;60% cohort while hypertension (91.6% vs. 92.2%), renal disease (53.8% vs. 54.6%), obesity (43.9% vs. 46.1%) and anemia (38.1% vs. 40.9%) had significantly higher frequency in the LVEF &gt;60% cohort. The annualized AcH rate for patients with LVEF&gt;40% was 1.44 and annualized HFH rate was 0.24 with a median length of stay of 3 and 4 days, respectively. Annualized hospitalization rates were significantly higher for women than men (both AcH and HFH). AcH rates were significantly higher and HFH rates were significantly lower for patients with LVEF&gt;60% compared with LVEF &gt;40-≤60.

Conclusions

This study demonstrates that patients with HF and LVEF &gt;40% experience significant burden from comorbidities and hospitalizations from any-cause and for HF. The hospitalization rates are higher in women (both AcH and HFH) or patients with LVEF &gt;60% (AcH only). Further focus on reduction of hospitalizations and interdisciplinary management of patients with HF should be warranted.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Novartis Pharma AG

Patients with heart failure and a LVEF less than 40% present an overall lower health related quality of life than those with LVEF between 40% and 60%: a multinational real-world survey in EU

Background and purpose

Heart Failure (HF) is associated with symptoms such as dyspnoea and fatigue which can impact patients' health related quality of life (HRQoL). This study aimed to characterize and assess the HRQoL of patients with HF and left-ventricular ejection fraction (LVEF) &lt;40% versus those with ≥40%-60%.

Methods

A cross-sectional study of patients with HF was conducted in France, Germany, Italy, Spain and United Kingdom. Patient record forms (PRFs) were completed by 257 cardiologists and 158 general practitioners (GPs) for consecutively consulting patients. The same patients were invited to provide patient-reported outcomes including self-completion questionnaires, Minnesota Living with Heart Failure Questionnaire (MLHFQ) and EQ-5D-5L VAS.

Results

204 HF patients with LVEF &lt;40% (mean age 67.7 years) and 600 patients with LVEF ≥40–60% (mean age 68.9 years) were included. Proportion of males was significantly higher in the lower LVEF group (73.5% vs. 61.2%, p=0.0017). Overall, the patients with lower LVEF more frequently presented with comorbidities than those with LVEF ≥40–60% (p&lt;0.05, Figure 1). NYHA stage III/IV (35.8%/7.4% vs. 15.3%/0.8%) as well as self-reported HF symptoms were more frequently reported in the lower LVEF group (p&lt;0.05, Figure 1). Similarly, patients with LVEF &lt;40% reported statistically significantly worse HRQoL compared to those with LVEF ≥40–60% (Table 1).

Conclusions

The HRQoL of all HF patients with LVEF ≤60% appears impacted, while those with LVEF &lt;40% had significantly worse HRQoL than those with LVEF ≥40–60%. These differences in HRQoL may not only be related to the LVEF but also to the overall characteristics of these patients. Addressing the HRQoL burden for patients should be a key aspect of HF management strategies for all HF patients.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Novartis Pharma AG

Recurrent hospitalizations are associated with increased mortality across the ejection fraction range in heart failure

AIMS

The proportion of patients hospitalized for heart failure (HF) with preserved left ventricular ejection fraction (LVEF) is rising, but no approved treatment exists, in part owing to incomplete characterization of this particular HF phenotype. In order to better define the characteristics of HF phenotypes in Finland, a large cohort with 12 years' follow-up time was analysed.

METHODS AND RESULTS

Patients diagnosed between 2005 and 2017 at the Hospital District of Southwest Finland were stratified according to LVEF measure and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels. For this retrospective registry study, previously diagnosed HF patients were defined as follows: patients with reduced ejection fraction (HFrEF; LVEF ≤ 40%; n = 4042), mid-range ejection fraction (HFmrEF; LVEF > 40-50% and NT-proBNP ≥ 125 pg/mL; n = 1468), and preserved ejection fraction (HFpEF; LVEF > 50% and NT-proBNP ≥ 125 pg/mL; n = 3122) and followed up for 15 022, 4962, and 10 097 patient-years, respectively. Cardiovascular (CV) hospitalization and mortality, influence of pre-selected covariates on hospitalization and mortality, and the proportion of HFpEF and HFmrEF patients with a drop in LVEF to HFrEF phenotype were analysed. All data were extracted from the electronic patient register. HFrEF patients were rehospitalized slightly earlier than HFpEF/HFmrEF patients, but the second, third, and fourth rehospitalization rates did not differ between the subgroups. Female gender and better kidney function were associated with reduced rehospitalizations in HFmrEF and HFrEF, with a non-significant trend in HFpEF. Each additional hospitalization was associated with a two-fold increased risk of death and 2.2- to 2.3-fold increased risk of CV death. All-cause mortality was higher in patients with HFpEF. Although CV mortality was less frequent in HFpEF patients, it was associated with increased NT-proBNP concentrations at index in all patient groups. During the 10 years following the index date, 26% of HFmrEF patients and 10% of HFpEF patients progressed to an HFrEF phenotype.

CONCLUSIONS

These findings suggest that disease progression, in terms of increased frequency of hospitalizations, and the relationship between increased number of hospitalizations and mortality are similar by LVEF phenotypes. These data highlight the importance of effective treatments that can reduce hospitalizations and suggest a role for monitoring NT-proBNP levels in the management of HFpEF patients in particular.

Recurrent heart failure hospitalizations are associated with increased cardiovascular mortality in patients with heart failure in Clinical Practice Research Datalink

Aims

Heart failure (HF) is a leading cause of hospitalization and is associated with high morbidity and mortality post‐diagnosis. Here, we examined the impact of recurrent HF hospitalization (HFH) on cardiovascular (CV) and all‐cause mortality among HF patients.

Methods and Results

Adult HF patients identified in the Clinical Practice Research Datalink with a first (index) hospitalization due to HF recorded in the Hospital Episode Statistics data set from January 2010 to December 2014 were included. Patients were followed up until death or end of study (December 2017). CV mortality as primary and as any reported cause and all‐cause mortality were evaluated. An extended Cox regression model was used for reporting adjusted relative CV mortality rates for time‐dependent recurrent HFHs. Overall, 8603 HF patients with an index hospitalization were included, providing 15 964 patient‐years of follow‐up. Patients were relatively old (median age: 80 years) and were mostly male (54.6%), with main co‐morbidities being hypertension and atrial fibrillation. Recurrent HFHs occurred one, two, three, and more than four times in 1561 (18.2%), 518 (6.02%), 206 (2.4%), and 153 (1.8%) patients, respectively. The median time to mortality was 215 (38–664) days for 50.8% of patients who died for any cause during the study period and 139 (27–531) days for 31.3% who died with CV reasons as primary cause. Compared with those of patients without recurrent HFHs, the adjusted hazard ratios (95% CI) for CV mortality as primary cause were 2.65 (2.35–2.99), 3.69 (3.06–4.43), 5.82 (4.48–7.58), and 5.95 (4.40–8.05) for those with one, two, three, and more than four recurrent HFHs.

Conclusions

There is a strong association between recurrent HFH and CV mortality, with the risk increasing progressively with each recurrent HFH.

3267Impact of recurrent heart failure hospitalizations on cardiovascular mortality in subpopulations with atrial fibrillation and Type 2 diabetes mellitus in a UK database

Background

Previous studies have suggested that recurrent heart failure hospitalizations (HFh) are a predictor of cardiovascular (CV) and all-cause mortality. Patients with atrial fibrillation (AF) or type 2 diabetes mellitus (T2DM) may be at increased risk.

Purpose

This real-world study examined the impact of recurrent HFh on CV mortality in subgroups of patients with (i) AF or (ii) T2DM in the UK.

Methods

Adult HF patients identified in the CPRD database with a first (index) hospitalization due to HF recorded in the HES dataset from 01/01/2010 to 31/12/2014 and with a claim for AF or T2DM (not mutually exclusive) within the year prior to the index hospitalization were included. Patients were followed until death, transfer out or end of study period (31/12/2017). CV death as primary cause and death due to any cause were evaluated. An extended Cox regression model was used for reporting adjusted relative CV mortality rates for time dependent recurrent HFh.

Results

4585 (53.30%) HF patients with AF and 2344 (27.25%) HF patients with T2DM were included, providing 7846 and 4269 patient-years follow-up, respectively. Patients were relatively old (median [IQR] age of 81 [74–87] and 78 [70–84]) and majority were male (54.2% and 59.1%, respectively). All-cause and CV mortality rates are provided in the table. Compared with those without recurrent HFh, the adjusted hazard ratios (95% CI) for CV death for the AF group were 2.6 (2.3–3.1), 3.2 (2.5–4.1), 5.8 (4.1–8.1) and 6.9 (4.6–10.5) for 1, 2, 3 and ≥4 recurrent HFh, and for the T2DM group were 2.2 (1.7–2.8), 3.3 (2.3–4.7), 5.1 (3.3–8.1) and 3.9 (2.3–6.6), respectively.

All-cause and CV mortality rates 0 Recurrent HFh 1 Recurrent HFh 2 Recurrent HFh 3 Recurrent HFh 4+ Recurrent HFh All patients AF n=3294 (71.8%) n=817 (17.8%) n=282 (6.2%) n=116 (2.5%) n=76 (1.2%) n=4585 (100.0%) Follow-up time (days) from respective recurrent HF hospitalization (median [IQR]) 345 [57–906] 118 [27–522] 80 [19–367] 54 [19–240] 126 [50–379] 254 [42–793] All-cause death (n (%)) 1755 (53.3%) 483 (59.1%) 159 (56.4%) 80 (69.0%) 46 (60.5%) 2523 (55.0%) CV death- primary cause (n (%)) 1059 (32.2%) 325 (39.8%) 109 (38.7%) 56 (48.3%) 34 (44.7%) 1583 (34.5%) T2DM n=1573 (67.1%) n=456 (19.5%) n=170 (7.3%) n=85 (3.6%) n=60 (2.6%) n=2344 (100.0%) Follow-up time (days) from respective recurrent HF hospitalization (median [IQR]) 360 [63–933] 198 [43–545] 68 [17–292] 106 [26–251] 160 [68–389] 267 [49–771] All-cause death (n (%)) 824 (52.4%) 248 (54.4%) 99 (58.2%) 51 (60.0%) 40 (66.7%) 1262 (53.8%) CV death – primary cause (n (%)) 501 (31.9%) 159 (34.9%) 69 (40.6%) 36 (42.4%) 26 (43.3%) 791 (33.8%)

Conclusion

Recurrent HFh are a strong predictor of CV death in the HF population with AF or with T2DM. The risk of CV and all-cause death increases with recurrent HFh in these subpopulations, highlighting the relevance of reducing hospitalizations in the management of HF patients with such comorbid conditions.

A Database Cohort Study to Assess the Risk of Angioedema Among Patients with Heart Failure Initiating Angiotensin-Converting Enzyme Inhibitors in the USA

INTRODUCTION

Real-world evidence on the risk of angioedema associated with angiotensin-converting enzyme inhibitors (ACEIs) in patients with heart failure (HF) is scarce.

OBJECTIVE

This non-interventional study aimed to estimate the incidence of and risk factors for angioedema in patients with HF initiating an ACEI in real-world practice.

METHODS

This was a retrospective cohort study using claims data from the PharMetrics Plus database, supplemented with consumer health data, from 1 January 2007 to 31 March 2015. Patients with HF initiating an ACEI were followed up for a maximum of 1 year, until the first occurrence of angioedema or until cohort exit. Angioedema incidence rates were estimated and stratified by potential risk factors such as race, age, sex, and time from initiation of ACEI therapy. For each risk factor, the unadjusted and adjusted hazard ratio (HR) was calculated; exploratory analyses were carried out to account for all potential confounders.

RESULTS

We identified 21,639 patients with HF initiating an ACEI (mean age 58 years; 35.6% women; mean follow-up 205 days). The 1-year incidence of angioedema per 1000 patient-years was 3.3 [95% confidence interval (CI) 2.4-4.5]. The incidence was higher in Black [6.2 (95% CI 3.1-12.5)] than in non-black [2.9 (95% CI 2.1-4.1)] patients, higher in women [5.2 (95% CI 3.4-7.9)] than in men [2.3 (95% CI 1.5-3.6)], and greatest in the first 30 days of ACEI therapy.

CONCLUSIONS

The risk of angioedema in patients with HF initiating an ACEI observed in this study is in line with published estimates for the general patient population treated with ACEIs.

Thromboxane A2/Prostaglandin H2 Receptor Activation Mediates Angiotensin II–Induced Postischemic Neovascularization

Objective— We analyzed the involvement of thromboxane (TX) A 2 /prostaglandin (PG) H 2 (TP) receptor in ischemia-induced neovascularization in mice.

Methods and Results— Unilateral hindlimb ischemia was induced by right femoral artery ligature in male C57BL/6J mice (n=7 per group). Animals were then treated with or without TP receptor antagonist (S18886, 5 or 10 mg/kg per day; ramatroban, 10 mg/kg per day) or aspirin (30 mg/kg per day) in drinking water for 21 days. Hindlimb ischemia raised plasma level of TXB 2, the stable metabolite of TXA 2 , by 4.7-fold. This increase was blocked by aspirin treatment whereas S18886 (5 or 10 mg/kg per day) had no effect. However, neither S 18886 nor aspirin affected postischemic neovascularization. We next assessed the putative involvement of TXA 2 signaling in angiotensin II (Ang II) proangiogenic pathway. Ang II (0.3 mg/kg per day) enhanced TXB 2 plasma levels by 2.6-fold over that of control ( P <0.01). Ang II-induced TXB 2 upregulation was reduced by cotreatment with Ang II type I receptor antagonist (candesartan, 20 mg/kg per day). Angiographic score, capillary number, and foot perfusion were improved by 1.7-, 1.7-, and 1.4-fold, respectively, in Ang II-treated mice compared with controls ( P <0.05). Ang II proangiogenic effect was associated with a 1.6-fold increase in VEGF-A protein content ( P <0.05) and a 1.4-fold increase in the number of Mac-3–positive cells (ie, macrophages) in ischemic areas ( P <0.05). Interestingly, treatments with TP receptor antagonists or aspirin hampered the proangiogenic effects of Ang II.

Conclusion— Endogenous activation of TXA 2 receptor by eicosanoids did not modulate spontaneous neovascularization in the setting of ischemia. Conversely, TXA 2 signaling is involved in Ang II-induced AT1-dependent vessel growth.

The thromboxane receptor antagonist S18886 attenuates renal oxidant stress and proteinuria in diabetic apolipoprotein E-deficient mice

Arachidonic acid metabolites, some of which may activate thromboxane A(2) receptors (TPr) and contribute to the development of diabetes complications, including nephropathy, are elevated in diabetes. This study determined the effect of blocking TPr with S18886 or inhibiting cyclooxygenase with aspirin on oxidative stress and the early stages of nephropathy in streptozotocin-induced diabetic apolipoprotein E(-/-) mice. Diabetic mice were treated with S18886 (5 mg . kg(-1) . day(-1)) or aspirin (30 mg . kg(-1) . day(-1)) for 6 weeks. Neither S18886 nor aspirin affected hyperglycemia or hypercholesterolemia. There was intense immunohistochemical staining for nitrotyrosine in diabetic mouse kidney. In addition, a decrease in manganese superoxide dismutase (MnSOD) activity was associated with an increase in MnSOD tyrosine-34 nitration. Tyrosine nitration was significantly reduced by S18886 but not by aspirin. Staining for the NADPH oxidase subunit p47(phox), inducible nitric oxide synthase, and 12-lipoxygenase was increased in diabetic mouse kidney, as were urine levels of 12-hydroxyeicosatetraenoic acid and 8-iso-prostaglandin F(2alpha). S18886 attenuated all of these markers of oxidant stress and inflammation. Furthermore, S18886 significantly attenuated microalbuminuria in diabetic mice and ameliorated histological evidence of diabetic nephropathy, including transforming growth factor-beta and extracellular matrix expression. Thus, in contrast to inhibiting cyclooxygenase, blockade of TPr may have therapeutic potential in diabetic nephropathy, in part by attenuating oxidative stress.

The extracellular matrix and the cytoskeleton in heart hypertrophy and failure

Cell characteristics and phenotype depend on the nature of the extracellular matrix, the type and organization of integrins and cytoskeleton. The interactions between these components are poorly known at the myocyte level and during cardiac remodeling associated with cardiac hypertrophy and heart failure. We analyze here the nature and organization of extracellular matrix (ECM) proteins, cytoskeleton and integrins and their regulation by growth factors, such as angiotensin II, in normal myocyte growth and in pathological growth (hypertrophy) of the myocardium and heart failure.

Extracellular matrix and growth factors during heart growth

The effects of growth factors on tissue remodeling and cell differentiation depend on the nature of the extracellular matrix, the type and organization of integrins, the activation of metalloproteinases and the presence of secreted proteins associated to the matrix. These interactions are actually poorly known in the cardiovascular system. We describe here: 1) the main components of extracellular matrix within the cardiovascular system; 2) the role of integrins in the transmission of growth signals; 3) the shift in the expression of the components of the extracellular matrix (fibronectin and collagens) and the stimulation of the synthesis of metalloproteinases during normal and hypertrophic growth of the myocardium; 4) the effects of growth factors, such as Angiotensin II, Fibroblast Growth Factors (FGF), Transforming Growth Factor-beta (TGF-beta), on the synthesis of proteins of the extracellular matrix in the heart.

The thromboxane A2 receptor antagonist S18886 prevents enhanced atherogenesis caused by diabetes mellitus

BACKGROUND

S18886 is an orally active thromboxane A2 (TXA2) receptor (TP) antagonist in clinical development for use in secondary prevention of thrombotic events in cardiovascular disease. We previously showed that S18886 inhibits atherosclerosis in apolipoprotein E-deficient (apoE(-/-)) mice by a mechanism independent of platelet-derived TXA2. Atherosclerosis is accelerated by diabetes and is associated with increased TXA(2) and other eicosanoids that stimulate TP. The purpose of this study was to determine whether S18886 lessens the enhanced atherogenesis in diabetic apoE(-/-) mice.

METHODS AND RESULTS

Diabetes mellitus was induced in apoE(-/-) mice with streptozotocin and was treated or not with S18886 (5 mg.kg(-1).d(-1)). After 6 weeks, aortic lesion area was increased >4-fold by diabetes in apoE(-/-) mice, associated with similar increases in serum glucose and cholesterol. S18886 largely prevented the diabetes-related increase in lesion area without affecting the hyperglycemia or hypercholesterolemia. S18886 prevented deterioration of endothelial function and endothelial nitric oxide synthase expression, as well as increases in intimal markers of inflammation associated with diabetes. In human aortic endothelial cells in culture, S18886 also prevented the induction of vascular cell adhesion molecule-1 and prevented the decrease in endothelial nitric oxide synthase expression caused by high glucose.

CONCLUSIONS

The TP antagonist inhibits inflammation and accelerated atherogenesis caused by diabetes, most likely by counteracting effects on endothelial function and adhesion molecule expression of eicosanoids stimulated by the diabetic milieu.

Atherosclerosis regression and TP receptor inhibition: effect of S18886 on plaque size and composition—a magnetic resonance imaging study

AIMS

Endothelial dysfunction, platelet hyperactivity, and inflammation play a crucial role in atherogenesis. A growing body of evidence suggests that inhibition of the thromboxane A2 (TxA2 or TP) receptor may improve endothelial function and reduce the inflammatory component of atherosclerosis in addition to its demonstrated antiplatelet activity. Consequently, we sought to assess the effect of a novel TP receptor antagonist S18886, on atherosclerotic lesion progression and composition by serial non-invasive magnetic resonance imaging (MRI).

METHODS AND RESULTS

S18886 was compared with control in an experimental model of established aortic atherosclerosis in New Zealand White rabbits (n=10). The animals underwent MRI of the abdominal aorta at the time of randomization and at the end of treatment. Subsequently, animals were euthanized and specimens were stained for histopathology and immunohistochemistry with anti-alpha-actin antibodies for vascular smooth muscle cells (VSMC), anti-RAM-11 for macrophages, anti-caspase-3 for apoptotic cells, anti-MMP-1 for metalloproteinases, and anti-endothelin-1 (ET-1) as a marker of endothelial dysfunction. MRI analysis revealed a significant reduction in total vessel area (TVA) and vessel wall area (VWA) in the S18886 group (P<0.05). Immunostaining analysis showed a significant decrease in RAM-11, caspase-3, MMP-1, ET-1 and an increase in alpha-actin in the treated group (P<0.05 vs. control).

CONCLUSION

Inhibition of the TP receptor by S18886 causes a regression of advanced atherosclerotic plaques. In addition, the reduction in the markers for macrophages, apoptotic cells, metalloproteinases, and endothelin-1 and the increase in VSMC, suggests that S18886 may not only halt the progression of atherosclerosis, but also transform lesions towards a more stable phenotype. The possibility of combining antithrombotic and antiatherosclerotic activity by means of the administration of TP inhibitors deserves further investigation in a clinical setting.

Rapid reactive oxygen species production by mitochondria in endothelial cells exposed to tumor necrosis factor-alpha is mediated by ceramide

Tumor necrosis factor (TNF)-alpha increases mitochondrial reactive oxygen species (ROS) production in tumor cells and hepatocytes. However, whether TNF-alpha stimulates mitochondrial ROS production in endothelial cells (EC) has not yet been reported. We studied the effect of TNF-alpha on mitochondrial ROS generation in EC and the signaling pathways involved. Cultured human umbilical vein EC (HUVEC) were studied by fluorescence microscopy, using dichlorodihydrofluorescein diacetate (DCFH-DA) as a marker of ROS production and propidium iodide uptake for cell viability. TNF-alpha increased DCFH oxidation in HUVEC dose-dependently. To determine the source of ROS, the mitochondrial respiratory chain inhibitors rotenone + thenoyltrifluoroacetone (TTFA), which inhibit electron entry to ubiquinone, and antimycin A (AA), a blocker of ubisemiquinone, were used. Rotenone and TTFA inhibited (n = 7, P < 0.05), whereas AA increased (118% in 3 min; n = 4, P < 0.01) ROS generation in HUVEC. In contrast, ROS production was not abolished by the nicotinamide adenine dinucleotide phosphate-dependent oxidase inhibitor diphenylene iodonium, by the xanthine oxidase inhibitor allopurinol, nor by the nitric oxide and cyclooxygenase pathway inhibitors N(omega)-nitro-L-arginine and mefenamic acid. In addition, TNF-alpha-induced ROS production was inhibited by the acidic sphingomyelinase inhibitor desipramine (5 microM; -80%, n = 4, P < 0.01) and totally blocked by the ceramide-activated protein kinase (CAPK) inhibitor dimethylaminopurine (1 mM; n = 6, P < 0.05). Thus, TNF-alpha induces mitochondrial ROS production in HUVEC that primarily occurs at the ubisemiquinone site and is mediated by ceramide-dependent signaling pathways involving CAPK.

Activation of NADPH oxidase by AGE links oxidant stress to altered gene expression via RAGE

Engagement of the receptor for advanced glycation end products (RAGE) by products of nonenzymatic glycation/oxidation triggers the generation of reactive oxygen species (ROS), thereby altering gene expression. Because dissection of the precise events by which ROS are generated via RAGE is relevant to the pathogenesis of complications in AGE-related disorders, such as diabetes and renal failure, we tested the hypothesis that activation of NADPH oxidase contributed, at least in part, to enhancing oxidant stress via RAGE. Here we show that incubation of human endothelial cells with AGEs on the surface of diabetic red blood cells, or specific AGEs, (carboxymethyl)lysine (CML)-modified adducts, prompted intracellular generation of hydrogen peroxide, cell surface expression of vascular cell adhesion molecule-1, and generation of tissue factor in a manner suppressed by treatment with diphenyliodonium, but not by inhibitors of nitric oxide. Consistent with an important role for NADPH oxidase, although macrophages derived from wild-type mice expressed enhanced levels of tissue factor upon stimulation with AGE, macrophages derived from mice deficient in a central subunit of NADPH oxidase, gp91phox, failed to display enhanced tissue factor in the presence of AGE. These findings underscore a central role of NADPH oxidase in AGE-RAGE-mediated generation of ROS and provide a mechanism for altered gene expression in AGE-related disorders.

Hydrogen peroxide decreases pHi in human aortic endothelial cells by inhibiting Na+/H+ exchange

Postischemic endothelial dysfunction may occur as a result of the effects of endogenous oxidants like hydrogen peroxide. Since endothelium-dependent vasodilator function may be affected by pHi, the effect of hydrogen peroxide on endothelial pHi was examined. Hydrogen peroxide (100 micromol/L for 10 minutes) decreased pHi from 7.24+/-0.01 to 7.02+/-0.02 and inhibited recovery from an ammonium chloride-induced intracellular acid load in carboxy SNARF 1 (c-SNARF 1)-loaded human aortic endothelial cells in bicarbonate-free solution. Prior inhibition of Na+/H+ exchange with 5-(N-ethyl-N-isopropyl)amiloride (10 micromol/L), by removal of extracellular Na+, or by glycolytic inhibition with iodoacetic acid blocked the subsequent effect of hydrogen peroxide on pHi. A 2-minute exposure to 100 micromol/L H2O2 decreased intracellular ATP levels by approximately 40%; this was prevented by 3-aminobenzamide and nicotinamide (1 mmol/L each), inhibitors of the DNA repair enzyme poly(ADP-ribose) polymerase. Both 3-aminobenzamide and nicotinamide significantly inhibited the hydrogen peroxide-induced intracellular acidification and the effect of hydrogen peroxide on recovery from an intracellular acid load. Hydrogen peroxide decreases pHi in human endothelial cells by inhibiting Na+/H+ exchange. This appears to be mediated by activation of the DNA repair enzyme poly(ADP-ribose) polymerase and subsequent depletion of intracellular ATP. Since a decrease in pHi in this range may alter the activity of NO synthase or affect the synthesis of vasodilator prostaglandins, the effect of hydrogen peroxide on the endothelial Na+/H+ exchanger may be important in the pathogenesis of postischemic endothelial dysfunction.

Paracrine regulation of cardiac myocytes in normal and septic heart

A paracrine pathway for the regulation of cardiac contractile function by nonmuscle cells is documented in the heart. Coronary and endocardial endothelium release several diffusible agents, such as prostaglandins, endothelin-1, and nitric oxide, with an action on cardiac myocyte function. Cardiac diseases involving an immune or inflammatory mechanism, such as endotoxic shock, are now seen as conditions in which cross-talk between different cell types in the heart is clearly implicated. The potential biological relevance of inducible nitric oxide synthase in the myocardium, and the subsequent production of nitric oxide has been proposed as a mechanism of the cardiac depression observed in septic shock. In addition to cardiac myocytes, activated microvascular endothelial cells and cardiac endothelial cells may contribute to nitric oxide generation and, ultimately, to the depression of myocardial contractile activity during sepsis. This article reviews the local intercellular communication between cardiac myocytes and endothelial cells in the normal heart and discusses some of the mechanisms potentially claimed to depress heart function in sepsis.

Hydrogen peroxide induces intracellular calcium oscillations in human aortic endothelial cells

BACKGROUND

Because the vascular endothelium is exposed to oxidant stress resulting from ischemia/reperfusion and from the products of polymorphonuclear leukocytes or monocytes, studies were performed to examine the effect of hydrogen peroxide (1 micromol/L to 10 mmol/L) on endothelial Ca2+ signaling.

METHODS AND RESULTS

At low concentrations (1 to 10 micromol/L), hydrogen peroxide did not affect intracellular Ca2+ concentration in subconfluent, indo 1-loaded human aortic endothelial monolayers. At a concentration of 100 micromol/L hydrogen peroxide, intracellular free Ca2+ gradually increased from 125.3+/-6.8 to 286.3+/-19.9 nmol/L over 4.2+/-0.9 minutes before repetitive Ca2+ oscillations were observed, consisting of an initial large, transient spike of approximately 1 micromol/L followed by several spikes of decreasing amplitudes at a frequency of 0.7+/-0.1 min-1 over 12.0+/-1.1 minutes. After these oscillations, intracellular Ca2+ reached a plateau of 543.4+/-64.0 nmol/L, which was maintained above baseline levels for >5 minutes and then partially reversible on washout of hydrogen peroxide in most monolayers. Intracellular Ca2+ oscillations were typically observed when monolayers were exposed to 100 to 500 micromol/L hydrogen peroxide. Higher concentrations of hydrogen peroxide (1 and 10 mmol/L) increased intracellular Ca2+ but only rarely (2 of 6 monolayers at 1 mmol/L) or never (at 10 mmol/L) stimulated intracellular Ca2+ oscillations. Removal of Ca2+ from the buffer either before hydrogen peroxide stimulation or during an established response did not block intracellular Ca2+ oscillations in response to 100 micromol/L hydrogen peroxide, but prior depletion of an intracellular Ca2+ store with either caffeine, histamine, or thapsigargin abolished Ca2+ oscillations.

CONCLUSIONS

Hydrogen peroxide induces concentration-dependent intracellular Ca2+ oscillations in human endothelial cells, which results from release of an endoplasmic reticulum Ca2+ store. Because oxidant production appears to occur in the micromolar range in the postischemic/anoxic endothelium and is associated with impaired endothelium-dependent relaxation, the effects of micromolar concentrations of hydrogen peroxide on endothelial Ca2+ signaling described in the present study may be important in the pathogenesis of postischemic endothelial dysfunction.

Trophic effect of human pericardial fluid on adult cardiac myocytes. Differential role of fibroblast growth factor-2 and factors related to ventricular hypertrophy

Pericardial fluid (PF) may contain myocardial growth factors that exert paracrine actions on cardiac myocytes. The aims of this study were (1) to investigate the effects of human PF and serum, collected from patients undergoing cardiac surgery, on the growth of cultured adult rat cardiac myocytes and (2) to relate the growth activity of both fluids to the adaptive changes in overloaded human hearts. Both PF and serum increased the rate of protein synthesis, measured by [14C]phenylalanine incorporation in adult rat cardiomyocytes (PF, +71.9 +/- 8.2% [n = 17]; serum, +14.9 +/- 6.5% [n = 13]; both P < .01 versus control medium). The effects of both PF and serum on cardiomyocyte growth correlated positively with the respective left ventricular (LV) mass. However, the magnitude of change with PF was 3-fold greater than with serum (P < .01). These trophic effects of PF were mimicked by exogenous basic fibroblast growth factor (FGF2) and inhibited by anti-FGF2 antibodies and transforming growth factor-beta (TGF-beta), suggesting a relationship to FGF2. In addition, FGF2 concentration in PF was 20 times greater than in serum. On the other hand, the LV mass-dependent trophic effect, present in both fluids, was independent of FGF2 concentration or other factors, such as angiotensin II, atrial natriuretic factor, and TGF-beta. These data suggest that FGF2 in human PF is a major determining factor in normal myocyte growth, whereas unidentified LV mass-dependent factor(s), present in both PF and serum, participates in the development of ventricular hypertrophy.

pH dependence of neutrophil-endothelial cell adhesion and adhesion molecule expression

Neutrophil adhesion to the vascular endothelium is enhanced during tissue ischemia and/or inflammation, conditions that are associated with tissue acidosis. This study examined the effects of hypercarbic acidosis (10 or 20% CO2) and of hypocarbic alkalosis (0% CO2) on human neutrophil CD18 and human aortic endothelial cell intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin expression quantified by flow cytometry. Acidosis with 20% CO2 for 4 h decreased ICAM-1 to 60.6 +/- 9.7% of control. In contrast, alkalosis with 0% CO2 for 4 h enhanced ICAM-1 expression to 143.8 +/- 10.1% of control. There was no pH dependence of VCAM-1 or E-selectin expression. Tumor necrosis factor-alpha (TNF-alpha; 10 ng/ml) increased endothelial ICAM-1, E-selectin, and VCAM-1; under these conditions, acidosis with 20% CO2 blunted both ICAM-1 and E-selectin surface expression compared with 5% CO2-, TNF-alpha-treated cells. Hypercarbic acidosis with 20% CO2 increased neutrophil CD18 expression and enhanced neutrophil adhesion. This latter effect was inhibited by neutrophil pretreatment with an anti-CD18 monoclonal antibody. In contrast, when only endothelial cells were preincubated with the hypercarbic buffer, neutrophil adhesion diminished to 55.6 +/- 7.8% of control. The results suggest that acidosis generated during tissue ischemia/inflammation may induce CD18-mediated neutrophil adhesion despite a decrease in ICAM-1 expression.

Endoplasmic reticulum Ca2+ depletion unmasks a caffeine-induced Ca2+ influx in human aortic endothelial cells

Intracellular Ca2+ pools contribute to changes in cytosolic [Ca2+] ([Ca2+]i), which play an important role in endothelial cell signaling. Recently, endothelial ryanodine-sensitive Ca2+ stores were shown to regulate agonist-sensitive intracellular Ca2+ pools. Since caffeine binds the ryanodine Ca2+ release channel on the endoplasmic reticulum in a variety of cell types, we examined the effect of caffeine on [Ca2+]i in human aortic endothelial cell monolayers loaded with the fluorescent probe indo 1. Under baseline conditions, 10 mmol/L caffeine induced a small increase in [Ca2+]i from 86 +/- 10 to 115 +/- 17 nmol/L (mean +/- SEM); this effect was similar to that of 5 mumol/L ryanodine and was unaffected by buffer Ca2+ removal. After depletion of an intracellular Ca2+ store by the irreversible endoplasmic reticulum Ca(2+)-ATPase inhibitor thapsigargin (1 mumol/L), ryanodine did not affect [Ca2+]i. In contrast, caffeine induced a large rapid increase in [Ca2+]i (176 +/- 19 to 338 +/- 35 nmol/L, P < .001) after thapsigargin exposure; this effect of caffeine was only observed when extracellular Ca2+ was present. A similar increase in [Ca2+]i was induced by caffeine after depletion of ryanodine- and histamine-sensitive Ca2+ stores or after pretreatment with the endoplasmic reticulum Ca(2+)-ATPase inhibitor cyclopiazonic acid (10 mumol/L). Thus, under baseline conditions the effect of caffeine on [Ca2+]i is similar to that of ryanodine and appears to be due to the release of an intracellular store. However, after depletion of an endoplasmic reticulum Ca2+ store, caffeine, but not ryanodine, stimulates Ca2+ influx, resulting in a large increase in [Ca2+]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Initial contact and subsequent adhesion of human neutrophils or monocytes to human aortic endothelial cells releases an endothelial intracellular calcium store

BACKGROUND

Increases in both leukocyte and endothelial cytosolic free [Ca2+] may be involved in intercellular adhesion by regulating the affinity of surface adhesion molecules or by facilitating transendothelial leukocyte migration. The purpose of this study was to examine the effect of initial contact and subsequent adhesion of human neutrophils or monocytes on human aortic endothelial [Ca2+].

METHODS AND RESULTS

Endothelial monolayers were loaded with the fluorescent Ca2+ indicator indo 1 and exposed to isolated human peripheral blood neutrophils or to a cultured human monocyte cell line. A rapid, fourfold to fivefold increase in endothelial cytosolic [Ca2+] occurred within seconds of leukocyte contact. No increase in endothelial [Ca2+] occurred on contact of 18.25-microns inert microspheres, isolated red blood cells, or suspensions of cultured human aortic endothelial cells. In experiments performed on monolayers grown in 1-mm2 capillary flow tubes, the increase in endothelial cytosolic [Ca2+] on initial leukocyte contact was found to be related to the subsequent resistance to leukocyte detachment during exposure to arterial levels of shear stress (13.4 dyne.cm-2). The increase in endothelial cytosolic [Ca2+] during leukocyte contact was not inhibited in Ca(2+)-free buffer but was abolished by prior depletion of an endoplasmic reticulum Ca2+ store by thapsigargin. Pretreatment of neutrophils with R15.7, a specific monoclonal antibody to the adhesion protein CD-18, inhibited the increase in endothelial cytosolic [Ca2+] on neutrophil contact.

CONCLUSIONS

Initial contact leading to subsequent adhesion of human leukocytes to human aortic endothelial cells releases an endothelial intracellular Ca2+ store. This may, in part, be mediated by specific adhesion proteins and may in turn regulate the affinity of surface adhesion molecules or facilitate transendothelial migration of leukocytes.

A functional ryanodine-sensitive intracellular Ca2+ store is present in vascular endothelial cells

The presence of the ryanodine receptor was recently demonstrated in vascular and endocardial endothelium, but its function has not been established. We investigated whether functional ryanodine-sensitive Ca2+ stores are present in cultured endothelial cells from rat aorta (RAECs), human aorta (HAECs), human umbilical vein (HUVECs), and bovine pulmonary artery (BPAECs) and what role these may play in intracellular Ca2+ regulation. Under resting conditions, HAECs, BPAECs, and HUVECs demonstrated a slow increase in intracellular Ca2+ (indexed by indo 1 fluorescence) on exposure to 5 mumol/L ryanodine, whereas RAECs did not. However, after an initial bradykinin exposure in RAECs, ryanodine markedly blunted the rapid increase in Ca2+ on a second exposure to bradykinin. In HUVECs, ryanodine in buffer with 1.5 mmol/L Ca2+ did not inhibit the agonist-sensitive Ca2+ increase, whereas it blunted the rapid increase in Ca2+ on histamine exposure in buffer with 5 mmol/L Ca2+, suggesting that increasing [Ca2+] enhances the binding of ryanodine to its receptor. Thus, functional ryanodine-sensitive Ca2+ stores are present in vascular endothelial cells. These appear to be involved in regulation of Ca2+ storage and release from agonist-sensitive intracellular compartments.

Endothelial cell Ca2+ increases upon tumor cell contact and modulates cell-cell adhesion

The signal transduction mechanisms involved in tumor cell adhesion to endothelial cells are still largely undefined. The effect of metastatic murine melanoma cell and human prostate carcinoma cell contact on cytosolic [Ca2+] of bovine artery endothelial cells was examined in indo-1-loaded endothelial cell monolayers. A rapid increase in endothelial cell [Ca2+] occurred on contact with tumor cells, but not on contact with 8-microns inert beads. A similar increase in endothelial cell [Ca2+] was observed with human neutrophils or monocyte-like lymphoma cells, but not with endothelial cells, red blood cells, and melanoma cell-conditioned medium. The increase in endothelial cell [Ca2+] was not inhibited by extracellular Ca2+ removal. In contrast, endothelial cell pretreatment with thapsigargin, which releases endoplasmic reticulum Ca2+ into the cytosol and depletes this Ca2+ store site, abolished the cytosolic [Ca2+] rise upon melanoma cell contact. Endothelial cell pretreatment with the membrane-permeant form of the Ca2+ chelator bis-(O-aminophenoxyl)ethane-N,N,N',N'-tetraacetic acid blocked the increase in cytosolic [Ca2+]. Under static and dynamic flow conditions (0.46 dyn/cm2) bis-(O-aminophenoxyl)ethane-N,N,N',N'-tetraacetic acid pretreatment of bovine pulmonary artery endothelial cell monolayers inhibited melanoma cell adhesion to the endothelial cells. Thus, tumor cell contact with endothelial cells induces a rapid Ca2+ release from endothelial intracellular stores, which has a functional role in enhancing cell-cell adhesion.