The Heart Research Institute

Several diseases show geographic clustering, giving insights into possible genetic and environmental causes. The pathogenesis of Congenital Heart Disease (CHD) remains largely unknown and analysis of geographic distribution of CHD cases lacks input from large, national-scale datasets. People with structural CHD were selected from the Australia and New Zealand CHD Registry. Of people known to be still living, from linkage with the National Death Index, addresses were geocoded and aggregated to standardised geographic regions with measures of the Australian population. Areas were described based on measures of their remoteness and driving time to hospitals. The relationship between the distribution of the CHD and Australian populations was compared with bivariate spatial correlation. Of 81,349 people with structural CHD in the Registry, 63,863 were still living and could be geocoded. Overall, most people lived in Major Cities, and within 1-hour drive from a hospital, with the proportion the same across the CHD population, the "complex CHD" population and the Australian population. Across the country, there was a strong positive correlation between the Australian population and the CHD population. There were only a small number of areas (6%) where the Australian and the CHD populations were proportionally different. Overall, there was clear evidence that the geographic distribution of the CHD population proportionally follows the general Australian population. This suggests that there is unlikely to be any spatial clusters that are driven by genetic or environmental causes.

Impaired angiogenesis underpins cardiovascular disease, particularly in people with diabetes; however, molecular mechanisms are still poorly understood. This study aims to decipher the role of an emerging antiangiogenic protein, FKBPL (FK506-binding protein-like), on cardiac structure and function, vascular integrity, and inflammatory signaling in in vivo and in vitro models of diabetes. In vivo, FKBPL transgenic mice (fkbpl+/-) were used to examine the metabolic and cardiovascular function and FKBPL-mediated mechanisms in streptozotocin-induced diabetes. In addition, comprehensive in vitro assessments of endothelial function and mechanisms were performed in normal/high-glucose and high/low-FKBPL conditions. Fkbpl+/- mice show signs of early cardiac remodeling (increased E/A [early-to-atrial filling velocity ratio] ratio, P=0.047, and cardiomyocytes size, P=0.0018; reduced collagen deposition, P=0.013; col1a1 mRNA reduction, P=0.0028) and aberrant expression of cardiac vascular dysfunction proteins (ICAM-1 [intercellular adhesion molecule 1], P<0.001, SIRT-1 [sirtuin 1]; P<0.001). Proinflammatory cardiac profile was prominent in fkbpl+/- murine hearts with increased protein expression of ICAM-1, IL (interleukin)-12p40, IL-15, IL-22, LIF (leukemia inhibitory factor), lipocalin-2, MMP (matrix metalloproteinase)-3/-9, periostin, serpin E1, and VCAM-1 (vascular cell adhesion molecule 1), which were decreased in diabetes. In diabetic mice with low FKBPL expression, glucose metabolism deteriorated, whereas vascular dysfunction improved. In normal glucose conditions, FKBPL knockdown in human aortic endothelial cells reduced VE-cadherin (vascular endothelial cadherin; P=0.0016) and impaired endothelial barrier (P<0.001). In high-glucose conditions, endothelial FKBPL knockdown improved angiogenesis, however overexpression of FKBPL reduced angiogenesis by inhibiting the FGF (fibroblast growth factor) and PDGF (platelet-derived growth factor) pathways (P<0.001) and increasing proinflammatory pathways (TGF [transforming growth factor]-β, P<0.001; leukocyte migration, P=0.033; IL-7 signaling, P=0.039), by upregulating microRNA (miR)-29b-3p (P=0.01) and miR-302b-5p (P=0.03), likely via CD44 (cluster of differentiation). FKBPL-based peptide mimetic, AD-01 (1 nM), in high-glucose conditions, upregulated endothelial vcam1 and glut1 mRNA expression, independent of miR-302b-5p. FKBPL plays an important role in glucose metabolism, endothelial function, angiogenesis, cardiac inflammation and function, and could be explored as a therapeutic target of cardiovascular disease both in nondiabetes and diabetes settings using precision medicine approach.

Mechanoadaptive Responses In this cover image, the newly found mechanoadaptive response of neutrophils adhesion and the membrane tether coalescence MI-SIM super-resolution images under abrupt flow acceleration are emphasized and represented. More details can be found in the Research Article by Lining Arnold Ju and co-workers (DOI: 10.1002/anbr.202500113).

Abstract Background Phosphoinositide 3-kinase (PI3K, p110α) is a critical regulator of normal heart size in mice, and is conserved in humans. Under basal conditions, cardiomyocyte-specific heterozygote transgenic mice expressing a dominant negative PI3K (dnPI3K) mutant have reduced cardiac PI3K activity and smaller heart weights, but left ventricular (LV) function is relatively normal. With advances in ultrasound, we recently identified atrial dysfunction in dnPI3K mice (&amp;gt;40% drop in left atrial (LA) reservoir and booster pump function) despite atria weight being smaller vs. non-transgenic (Ntg, control) and no elevation in atrial fibrosis. We also characterized dnPI3K homozygote transgenic mice with two copies of the dnPI3K transgene, designed to inhibit PI3K activity further. DnPI3K homozygote mice presented with LV dysfunction, significant fibrosis (LV and LA), and a subset of mice presented with arrhythmia including intermittent atrial fibrillation, atrial enlargement and atrial thrombi. LA function was also depressed in homozygote dnPI3K, but not dramatically reduced vs. dnPI3K heterozygote mice. In another study, heterozygote dnPI3K mice and mice with increased PI3K due to expression of a constitutively active PI3K (caPI3K) mutant were subjected to pressure overload (aortic banding) for 1 week. Atrial enlargement (based on raw atria weight alone) appeared to be greater in banded heterozygote dnPI3K vs. Ntg and lower in caPI3K. However, analysis of normalized atrial weights and atrial weight/heart weight ratios had not been assessed. Purpose 1) To more comprehensively characterize collagen deposition in atria from heterozygote and homozygote dnPI3K mice, and 2) evaluate atrial enlargement in heterozygote dnPI3K and caPI3K in response to pressure overload. Methods 1) LA from 20 week old female dnPI3K (heterozygote &amp; homozygote) and Ntg were fixed and stained with Masson’s trichrome or the predominant collagens in the heart (collagen I and III by immunohistochemistry). 2) Atria weight/tibia length (AW/TL) and atria weight/heart weight (AW/HW) were analyzed from a prior study in adult male Ntg, heterozygote dnPI3K and caPI3K that were subjected to ascending aortic-constriction (AAC/Band) or sham for 1 week. This procedure leads to pathological cardiac hypertrophy within 1 week in Ntg. Results 1) Fibrosis, collagen I and collagen III expression were elevated in atria from homozygote dnPI3K vs. heterozygote dnPI3K and Ntg (Fig 1A). 2) Normalized AW/TL and AW/HW were elevated in control Ntg in response to AAC (Band), elevated further in heterozygote dnPI3K (dnP Band), but not elevated in caPI3K (caP Band, Figure 1B). Conclusions Reduced PI3K(p110α) in cardiomyocytes alone leads to atrial dysfunction in the absence of atrial fibrosis and increased collagen expression. In a setting of pressure overload, increased PI3K(p110α) protects against atrial enlargement whereas reduced PI3K(p110α) accelerates atrial enlargement.Figure 1

Background: As survival into adulthood improves for congenital heart disease (CHD) patients, the quality of survival is paramount. We assessed health-related quality of life (HRQL) in a large Australian adult CHD cohort and identified clinical, psychosocial and system-level predictors of better or worse HRQL. Methods: We conducted a multicenter, registry-based cross-sectional study of a random stratified sample of adults from the Registry, assessing 868 participants who completed the PedsQL 4.0 Generic Core Scales and had complete covariate data. Analyses were structured into three stages: Stage I examined CHD complexity (mild, moderate, severe) across the lower (bottom 15%), middle (70%), and upper (top 15%) HRQL score bands; Stage II identified predictors of worse or better HRQL at the tails of the distribution; and Stage III assessed predictors of overall HRQL within the severe CHD group. Results: PedsQL Total scores were generally high (median 76.1, IQR 64.1-87.0) and best in Social functioning; Emotional and Psychosocial scales showed longer lower tails. Severe CHD was over-represented in the lower 15% and under-represented in the upper 15% bands (Total HRQL: p&lt;0.001;[(Cramér's V= 0.10,95% CI [0.06,0.15]). At the 15th percentile, worse HRQL was associated with severe CHD (≈-5.9 points), poor transition support (≈-11.2), mood disorder (≈-12.7), and diabetes (≈-16.6). At the 85th percentile, severe CHD (≈-5.2) and mental-health comorbidity (mood ≈ -7.3; anxiety ≈-5.6) was associated with worse HRQL. In severe CHD, poor transition support and mood or anxiety disorders (OR≈0.48,0.30,and 0.36, respectively; p ≤ 0.01) markedly increased the odds of worse HRQL and reduced the odds of better HRQL. Very well-supported transition (OR≈1.91, posterior probability = 0.99) was associated with better HRQL. Conclusion: In adult CHD, anatomic complexity contributes modestly to HRQL extremes. Modifiable predictors (transition experience and mental-health comorbidity, location and diabetes) emerge as key targets to improve HRQL, particularly in severe CHD.

ABSTRACT Background Women with peripheral artery disease (PAD) experience poorer clinical outcomes than men, particularly in the setting of diabetes. However, the mechanistic basis for these sex- specific disparities remains unclear. Methods Here, we investigated endothelial cell (EC) function(s) in diabetes-associated PAD, with a focus on sex differences. Limb tissues from patients with diabetes and chronic limb-threatening ischemia (CLTI) undergoing amputation, and a diabetes mouse model of hindlimb ischemia (HLI), were assessed for vasodilatory capacity, angiogenesis, oxidative stress and changes to expression of mitochondrial complex genes. ECs exposed to a hyperglycemic environment in vitro were assessed for mitochondrial function. The therapeutic potential of the mitochondrial-targeted antioxidant MitoQ was investigated. Results ECs from females with diabetes-associated PAD have altered responses compared to males. Specifically, limb vessels and skeletal muscle from females exhibit reduced arterial relaxation, angiogenesis and increased oxidative stress in response to HLI in mice, and in tissues from patients. Single-cell RNA sequencing of murine limbs revealed marked suppression of EC mitochondrial complex genes in females with diabetes. Female human ECs exposed to high glucose had reduced respiration, reduced expression of mitochondrial genes and increased oxidative stress. Remarkably, MitoQ restored arterial relaxation and the angiogenic response in female diabetes- associated PAD. Conclusion Our findings uncover a striking sex-specific vulnerability involving oxidative stress and mitochondrial dysfunction in EC health in diabetes-associated PAD. These results highlight the need for sex-specific therapeutic strategies in diabetic PAD, which might include mitochondrial targeted antioxidant strategies.

Microangiopathy is a major complication of SARS-CoV-2 infection and contributes to the acute and chronic complications of the disease1. Endotheliopathy and dysregulated blood coagulation are prominent in COVID-19 and are considered to be major causes of microvascular obstruction1,2. Here we demonstrate extensive endothelial cell (EC) death in the microvasculature of COVID-19 organs. Notably, EC death was not associated with fibrin formation or platelet deposition, but was linked to microvascular red blood cell (RBC) haemolysis. Importantly, this RBC microangiopathy was associated with ischaemia-reperfusion injury, and was prominent in the microvasculature of humans with myocardial infarction, gut ischaemia, stroke, and septic and cardiogenic shock. Mechanistically, ischaemia induced MLKL-dependent EC necroptosis and complement-dependent RBC haemolysis. Deposition of haemolysed RBC membranes at sites of EC death resulted in the development of a previously unrecognized haemostatic mechanism preventing microvascular bleeding. Exaggeration of this haemolytic response promoted RBC aggregation and microvascular obstruction. Genetic deletion of Mlkl from ECs decreased RBC haemolysis, microvascular obstruction and reduced ischaemic organ injury. Our studies demonstrate the existence of a RBC haemostatic mechanism induced by dying ECs, functioning independently of platelets and fibrin. Therapeutic targeting of this haemolytic process may reduce microvascular obstruction in COVID-19, and other major human diseases associated with organ ischaemia.