Showing papers by "Barbara Casadei published in 2023"

Endothelial cell-specific roles for tetrahydrobiopterin in myocardial function, cardiac hypertrophy, and response to myocardial ischemia-reperfusion injury

Abstract: INTRODUCTION The cofactor tetrahydrobiopterin (BH4) is a critical regulator of nitric oxide synthase (NOS) function and redox signalling, with reduced BH4 implicated in multiple cardiovascular disease states. In the myocardium, augmentation of BH4 levels can impact on cardiomyocyte function, preventing hypertrophy and heart failure. However, the specific role of endothelial cell BH4 biosynthesis in the coronary circulation and its role in cardiac function and the response to ischaemia has yet to be elucidated. METHODS/RESULTS Endothelial cell specific Gch1 knock out mice were generated by crossing Gch1fl/f with Tie2cre mice, generating Gch1fl/flTie2cre mice and littermate controls. GTPCH protein and BH4 levels were reduced in heart tissues from Gch1fl/flTie2cre mice, localized to endothelial cells, with normal cardiomyocyte BH4. Deficiency in coronary endothelial cell BH4 led to NOS uncoupling, decreased NO bioactivity, and increased superoxide and hydrogen peroxide production in hearts of Gch1fl/flTie2cre mice. Under physiological condition, loss of endothelial cell-specific BH4 led to mild cardiac hypertrophy in Gch1fl/flTie2cre hearts. Endothelial cell BH4 loss was also associated with increased nNOS protein, loss of eNOS protein and increased phospholamban phosphorylation at Ser17 in cardiomyocytes. Loss of cardiac endothelial cell BH4 led to coronary vascular dysfunction, reduced functional recovery and increased myocardial infarct size following ischemia/reperfusion injury. CONCLUSION Taken together, these studies reveal a specific role for endothelial cell Gch1/BH4 biosynthesis in cardiac function and the response to cardiac ischemia/reperfusion injury. Targeting endothelial cell Gch1 and BH4 biosynthesis may provide a novel therapeutic target for the prevention and treatment of cardiac dysfunction and ischaemia-reperfusion injury.

Reduced Left Atrial Rotational Flow Is Independently Associated With Embolic Brain Infarcts.

Abstract: Up to 25% of embolic strokes occur in individuals without atrial fibrillation (AF) or other identifiable mechanisms.To assess whether left atrial (LA) blood flow characteristics are associated with embolic brain infarcts, independently of AF.The authors recruited 134 patients: 44 with a history of ischemic stroke and 90 with no history of stroke but CHA2DS2VASc (congestive heart failure, hypertension, age ≥75 [doubled], diabetes, stroke [doubled], vascular disease, age 65 to 74, and sex category [female]) score ≥1. Cardiac magnetic resonance (CMR) evaluated cardiac function and LA 4-dimensional flow parameters, including velocity and vorticity (a measure of rotational flow), and brain magnetic resonance imaging (MRI) was performed to detect large noncortical or cortical infarcts (LNCCIs) (likely embolic), or nonembolic lacunar infarcts.Patients (41% female; age 70 ± 9 years) had moderate stroke risk (median CHA2DS2VASc = 3, Q1-Q3, 2-4). Sixty-eight (51%) had diagnosed AF, of whom 58 (43%) were in AF during CMR. Thirty-nine (29%) had ≥1 LNCCI, 20 (15%) had ≥1 lacunar infarct without LNCCI, and 75 (56%) had no infarct. Lower LA vorticity was significantly associated with prevalent LNCCIs after adjustment for AF during CMR, history of AF, CHA2DS2VASc score, LA emptying fraction, LA indexed maximum volume, left ventricular ejection fraction, and indexed left ventricular mass (odds ratio [OR]: 2.06 [95% CI: 1.08-3.92 per SD]; P = 0.027). By contrast, LA flow peak velocity was not significantly associated with LNCCIs (P = 0.21). No LA parameter was associated with lacunar infarcts (all P > 0.05).Reduced LA flow vorticity is significantly and independently associated with embolic brain infarcts. Imaging LA flow characteristics may aid identification of individuals who would benefit from anticoagulation for embolic stroke prevention, regardless of heart rhythm.

Heart failure, female sex and atrial fibrillation are the main drivers of human atrial cardiomyopathy: results from the CATCH ME consortium

Abstract: Background: Atrial cardiomyopathy (AtCM) is emerging as an independent prognostic factor in cardiovascular disease. Fibrotic remodeling, cardiomyocyte hypertrophy, and capillary density are histological hallmarks of atCM. The contribution of etiological factors and atrial fibrillation (AF) to the development of differential atCM phenotypes has not been robustly quantified. We aimed to evaluate the association between histological features of atCM and the clinical phenotype. Methods: We examined left (LA,n=95) and right (RA,n=76) atrial appendages from a European cohort of patients undergoing cardiac surgery. Quantification of histological atCM features was performed using the JavaCyte algorithm, following staining with agglutinin (WGA), CD31 and vimentin. The contributions of AF, heart failure (HF), sex and age to histological characteristics were determined in multivariate models. K-means clustering of histological features was performed to identify different types of atCM. Results: In both atria, persistent AF was associated with increased endomysial fibrosis (LA:+1.07{+/-}0.41 m,p=0.01; RA:+0.89{+/-}0.43m,p=0.032), whereas total extracellular matrix (ECM) content was unchanged in AF. Men had larger cardiomyocytes (LA:+1.87{+/-}0.72m,p=0.012), while women had a higher degree of endomysial fibrosis (LA:+0.99{+/-}0.51m,p=0.048). Heart failure patients showed more endomysial fibrosis (LA:+1.79{+/-}0.41 m,p<0.001) and ECM content (LA:+2.93{+/-}1.15%, p=0.014), and a higher capillary density (LA:+0.14{+/-}0.06,p=0.032) and size (LA:+0.48{+/-}0.23 m,p=0.041; RA:+0.31{+/-}0.16m,p=0.047). Clustering of samples based on structural features identified 2 distinct atCM phenotypes; one characterized by enhanced endomysial fibrosis (LA:+3.35 m,p<0.001; RA:+1.88m,p<0.001), ECM content (LA:+5.68%,p<0.001; RA:+7.78%,p<0.001), and a higher fibroblast density (LA:+4.79%,p<0,001) and one characterized by cardiomyocyte hypertrophy (LA:+1.20 m,p=0.009; RA:+2.95m ,p<0.001). Patients with fibrotic atCM were more often female (LA:OR=1.31,p=0.003; RA:OR=1.55,p=0.003), had more often persistent AF (LA:OR=1.23,p=0.031) or heart failure (LA:OR=1.62,p<0.001) whereas hypertrophic features were more common in men (LA:OR=1.31,p=0.031; RA:OR= 1.55,p=0.003). Conclusions: AtCM phenotypes vary with patient characteristics. Fibrotic atCM is associated with female sex, persistent AF and heart failure, while hypertrophic features are more common in men.

Etiological and molecular determinants of atrial endomysial fibrosis: results from the CATCH ME consortium

Abstract: Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): CATCH ME: Characterizing Atrial fibrillation by Translating its Causes into Health Modifiers in the Elderly Background We recently demonstrated that in human atria, endomysial fibrosis causes conduction disturbances during atrial fibrillation (AF), while overall connective tissue content (over-all fibrosis) has no effect. Etiological and molecular determinants of endomysial fibrosis are largely unknown. Methods We quantified over-all and endomysial atrial fibrosis using staining with WGA in left (LA, n=95) and right (RA, n=76) atrial appendages sampled from a European cohort (CATCH ME) of patients undergoing cardiac surgery. The contributions of AF, heart failure (HF), sex, age, and 4 principal components accounting for confounding clinical characteristics to over-all and endomysial fibrosis were determined in a multivariate model. RNA sequencing was performed to explore biological pathways associated with the two types of fibrosis. Results Over-all and endomysial fibrosis were moderately correlated (LA: r=0.69, RA: 0.61, both p<0.001) and more pronounced in RA than in LA samples (p<0.001). In LA, persistent AF, female sex, and HF were independently associated with endomysial fibrosis, while over-all fibrosis was only associated with sex and HF. Likewise, in RA, persistent AF was associated with endomysial fibrosis, while over-all fibrosis was not. Expression of 18 genes was univariately associated with endomysial fibrosis in LA but only 1 in RA. There were no genes associated with over-all fibrosis. After correction for relevant clinical traits, BMP10 showed the strongest association with endomysial fibrosis amongst coding genes (p=3.16E-04, LA). In an independent validation cohort (RACE V Tissue Bank Project, n=162 pts undergoing cardiac surgery), out of 11 biomarkers reflecting inflammation, fibrosis, vascular dysfunction, or ischemia, BMP10 plasma levels were most strongly associated with endomysial fibrosis (p<0.001), but not with over-all fibrosis. Conclusions Taken together, female sex, HF, and AF are the main drivers of fibrosis in human atria. However, endomysial fibrosis is independently associated with AF whereas over-all fibrosis is not. BMP10 is a specific marker of endomysial fibrosis. Our findings suggest that distinct mechanisms are involved in the development of over-all versus endomysial fibrosis in human atria and may provide an explanation for the recently reported predictive value of BMP10 biomarkers levels for AF recurrences after AF ablation and for stroke.

Recruited macrophages elicit atrial fibrillation

Abstract: Atrial fibrillation disrupts contraction of the atria, leading to stroke and heart failure. We deciphered how immune and stromal cells contribute to atrial fibrillation. Single-cell transcriptomes from human atria documented inflammatory monocyte and SPP1+ macrophage expansion in atrial fibrillation. Combining hypertension, obesity, and mitral valve regurgitation (HOMER) in mice elicited enlarged, fibrosed, and fibrillation-prone atria. Single-cell transcriptomes from HOMER mouse atria recapitulated cell composition and transcriptome changes observed in patients. Inhibiting monocyte migration reduced arrhythmia in Ccr2−∕− HOMER mice. Cell-cell interaction analysis identified SPP1 as a pleiotropic signal that promotes atrial fibrillation through cross-talk with local immune and stromal cells. Deleting Spp1 reduced atrial fibrillation in HOMER mice. These results identify SPP1+ macrophages as targets for immunotherapy in atrial fibrillation. Description Editor’s summary Atrial fibrillation (AFib), the most common type of heart arrhythmia, is a serious condition that can result in atrial blood clots and thromboembolic stroke. Hulsmans et al. performed single-cell RNA sequencing on atrial tissue from AFib patients and healthy controls to better understand how stromal and immune cells contribute to this disease. They found that recruited CCR2+ SPP1+ macrophages expanded in AFib patients. These cellular and transcriptomic changes were recapitulated in a mouse model of AFib that integrated hypertension, obesity, and mitral valve regurgitation (HOMER). Disrupting Ccr2, which coordinates inflammatory macrophage recruitment to atria, or Spp1, which helps to drive inflammatory fibroblast activation by macrophages, ameliorated disease burden in HOMER mice, suggesting two potential immunotherapy targets for Afib patients. —STS A subset of recruited macrophages drives atrial fibrillation in patients and in mouse models.

Active monitoring for atrial fibrillation (AMALFI): a streamlined randomised controlled trial of remote screening for subclinical atrial fibrillation

Abstract: Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health and Care Research Oxford Biomedical Research Centre ECG patches (and respective monitoring data analysis) were granted free of charge by the manufacturer (iRhythm) Background Incidence of stroke could be reduced by detection of subclinical atrial fibrillation (AF) and appropriate anticoagulation. Opportunistic screening by pulse-taking or ECG is recommended by some international guidelines. In contrast, there is uncertainty regarding the benefits and harms of systematic screening across populations and/or using longer monitoring durations. Purpose To assess if screening using a one-off single-lead continuous non-invasive ECG patch worn for 14 days increases AF detection at 2.5 years compared to standard care, and whether this approach is cost-effective. Methods AMALFI is an ongoing mail-based open-label randomised controlled trial of remote AF screening in England. Streamlined design includes integration with national electronic health data and care pathways for participant identification, invitation, and management. The target population are individuals aged ≥65 years with CHA2DS2VASc score of ≥3 in men and ≥4 in women, and with no prior history of AF or allergy to latex. Participants in the intervention arm self-apply the ECG patch and return it for analysis after 14 days. AF findings (duration ≥30 seconds at any rate) are communicated to primary care physicians, with further clinical management at their discretion. Participants in the control arm receive usual care (which is expected to include opportunistic AF screening). The primary outcome is the proportion of participants with newly-detected AF recorded in primary care electronic health records in each group at 2.5 years after randomisation. Results From 2019 to 2022, AMALFI invited 22,188 people, of whom 5,040 (23%) were randomised. Baseline characteristics included age 77±6 years, 47% female, and median CHA2SD2VASc score 3 (Table 1). Of 2520 individuals randomised to the intervention, 2127 (84%) wore and returned the patch. Median wear time was 13.9 days and median proportion of time analysable was 98.8%. AF was present in 102 patch reports, representing 4.8% of reports received and 4% of the intervention arm (in line with a priori estimates for power calculations for the primary outcome); median AF burden was 11.3%. AF was present at commencement of recording in 40% of these reports, by the end of the first day in 58%, and by the end of the first week in 83% (Figure 1). Incidental findings included supraventricular tachycardia (in 90% of reports), non-sustained ventricular tachycardia (VT; in 32%), sustained VT (in 0.1%), Mobitz II/high-grade/3rd degree AV block (in 1.1%), and pauses >6s (in 0.3%). Conclusion AMALFI’s innovative design facilitated recruitment and demonstrates that a remote ECG patch-based AF screening strategy is feasible, resulting in a new diagnosis of AF in ~4% of individuals selected due to moderate-to-high clinical stroke risk. Longer term follow-up will provide data on the incremental value and cost-effectiveness of AF diagnosis by systematic screening compared to routine opportunistic detection. Table 1: Baseline Characteristics Figure 1: Day of first AF episode

Mechanisms and Predictors of Acute Kidney Injury with Perioperative Rosuvastatin in Patients Undergoing Cardiac Surgery

Abstract: Background In patients undergoing cardiac surgery perioperative statin therapy has been associated with an unexpected increase in postoperative plasma creatinine. Here we investigated mechanisms and predictors of acute kidney injury (AKI) in 1922 patients enrolled in the Statin Therapy in Cardiac Surgery (STICS) randomized placebo-controlled trial of perioperative rosuvastatin (20 mg once daily). Methods AKI was defined according to international guidelines (KDIGO) using plasma creatinine, and also by cystatin C. Potentially mechanistically relevant plasma/serum biomarkers of muscle injury, inflammation, and kidney injury were investigated, including total creatine kinase (CK), growth differentiation factor 15 (GDF-15), interleukin-6 (IL-6), procalcitonin (PCT), placental growth factor (PLGF), kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). Results At 48 hours post-surgery, the incidence of AKI was greater in the rosuvastatin group than in the placebo group when defined by a rise in creatinine (24.7% vs 19.3%, p=0.005) or cystatin C (9.2% vs 5.1%, p<0.001); the majority of AKI was stage 1 in severity (87% when defined by creatinine, and 80% when defined by cystatin C). Compared with placebo, rosuvastatin led to higher postoperative serum levels of KIM-1 (278+/-5 pg/ml versus 259+/-5 pg/ml, P=0.01), and to more frequent elevations in CK to >10x and >40x the baseline level (30.9% versus 26.5%, p=0.032, and 2.1% versus 0.7%, p=0.016, respectively), whereas postoperative concentrations of GDF-15, IL-6, PCT, PLGF, and NGAL were similar between groups. In multivariable analyses, insulin treatment, baseline KIM-1, combined coronary artery bypass grafting (CABG) and aortic valve replacement (AVR) surgery, and allocation to rosuvastatin were all independently associated with AKI as defined by creatinine or cystatin C. Odds ratios for rosuvastatin compared to placebo for both creatinine- and cystatin C-defined AKI were not materially altered by further adjustment for post-randomization increases in CK. Conclusions Perioperative rosuvastatin initiation increased the absolute risk of AKI after cardiac surgery by 4-5%, whether defined by creatinine or cystatin C, and led to higher post-operative KIM-1, suggesting a deleterious effect on renal function, possibly mediated by proximal tubular injury. Insulin treatment, baseline KIM-1, combined CABG/AVR surgery, and allocation to rosuvastatin were all independently associated with AKI by any definition.

Heart failure, female sex and atrial fibrillation are the main drivers of atrial cardiomyopathy in cardiac surgery patients: results from the CATCH ME consortium

Abstract: Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): CATCH ME: Characterizing Atrial fibrillation by Translating its Causes into Health Modifiers in the Elderly Background Atrial cardiomyopathy is emerging as independent prognostic factor in cardiovascular disease. Fibrotic remodeling, cardiomyocyte hypertrophy and a reduction in capillary density are histological hallmarks of atrial cardiomyopathy. The contribution of etiological factors to atrial cardiomyopathy has not been robustly quantified. Purpose To quantify the relation between histological features of atrial cardiomyopathy and the clinical profile of patients. Methods We examined left (LA, n=91) and right (RA, n=75) atrial appendages sampled from a European cohort of patients undergoing cardiac surgery. Quantification of histological cardiomyopathy features was performed a recently developed and validated imaging analysis algorithm following myocardial triple staining with wheat germ agglutinin (WGA), CD31 and vimentin. The contributions of AF, heart failure (HF), sex, age, and 4 principal components accounting for confounding clinical characteristics to over-all and endomysial fibrosis were determined in a multivariate model. K-means clustering of 6 atrial histological features was performed to identify different types of remodeling. Results LA samples showed less fibrosis (p<0.001), a higher capillary density (p<0.05), a smaller capillary size (p<0.05), and larger cardiomyocytes (p<0.01) than RA samples. In both LA and RA, persistent AF was associated with endomysial fibrosis, while over-all fibrosis was not. Men had larger cardiomyocytes (LAA), while women had a higher degree of endomysial fibrosis (LA). Heart failure patients had more endomysial and over-all fibrosis (LA), a higher capillary density (LA) and capillary size (LA/RA). Samples clustered into 2 distinct clusters. One cluster showed fibrotic cardiomyopathy, with more endomysial (p<0.001) and overall fibrosis (p<0.001), more fibroblasts (p<0,001) and a higher capillary density (p<0.001). The other cluster showed hypertrophic cardiomyopathy, with hypertrophic cardiomyocytes (p<0.001). Patients with fibrotic cardiomyopathy were more often female (LA and RA, p<0.003) and had more often persistent AF (LA, p=0.031) or heart failure (LA, p<0.001). Patients with hypertrophic cardiomyopathy were more often male (LA and RA, p<0.003). Conclusions Fibrotic cardiomyopathy is associated with female sex, persistent AF and heart failure while hypertrophic cardiomyopathy more often occurs in men. More research is needed to establish whether treatment of AF and heart failure prevents the development of atrial cardiomyopathy.