Chronic kidney disease (CKD) affects > 10% of the global adult population and significantly increases the risk of cardiovascular disease (CVD), which remains the leading cause of death in this population. The development and progression of CVD—compared to the general population—is premature and accelerated, manifesting as coronary artery disease, heart failure, arrhythmias, and sudden cardiac death. CKD and CV disease combine to cause multimorbid cardiorenal syndrome (CRS) due to contributions from shared risk factors, including systolic hypertension, diabetes mellitus, obesity, and dyslipidemia. Additional neurohormonal activation, innate immunity, and inflammation contribute to progressive cardiac and renal deterioration, reflecting the strong bidirectional interaction between these organ systems. A shared molecular pathophysiology—including inflammation, oxidative stress, senescence, and hemodynamic fluctuations characterise all types of CRS. This review highlights the evolving paradigm and recent advances in our understanding of the molecular biology of CRS, outlining the potential for disease-specific therapies and biomarker disease detection.

Corpora amylacea (CoA) are spherical aggregates of glucose polymers and proteins within the periventricular, perivascular and subpial regions of the cerebral cortex and the hippocampal cornu ammonis (CA) subfields. The present study quantified the distribution of CoA in autopsied hippocampi of patients with obstructive sleep apnoea (OSA) using ethanolamine-induced fluorescence. CoA were observed in 29 of 30 patients (96.7%). They were most abundant in periventricular regions (wall of lateral ventricle, alveus, fimbria and CA4), rarely found in the CA3 and CA1, and undetectable in the CA2 or subiculum. A spatiotemporal sequence of CoA deposition was postulated, beginning in the fimbria and progressively spreading around the subpial layer until they extended medially to the wall of the lateral ventricle and laterally to the collateral sulcus. This ranked CoA sequence was positively correlated with CoA packing density (count and area fraction) and negatively correlated with CoA minimum diameters (p < 0.05). Although this sequence was not correlated with age or body mass index (BMI), age was positively correlated with the mean and maximum diameters of CoA. These findings support the view that the spatiotemporal sequence of CoA deposition is independent of age, and that CoA become larger due to the accretion of new material over time.

Chronic kidney disease (CKD) accelerates vascular dysfunction and cardiovascular disease, partly through the accumulation of the uraemic toxin indoxyl sulphate (IS). Thrombospondin-1 (TSP1) and its receptor CD47 have been implicated in vascular pathology, but their role in CKD-associated vascular remodelling is unknown. We investigated the contribution of TSP1–CD47 signalling to vascular smooth muscle cell (VSMC) dysfunction in CKD. Human aortic VSMCs (hVSMCs) were exposed to IS, TSP1, or plasma from patients with CKD. CKD was induced in wild-type (WT) and CD47-deficient (CD47KO) mice using 5/6 nephrectomy. Vascular changes were assessed by histology, immunohistochemistry, and molecular analyses. IS, TSP1, and CKD plasma increased TSP1 expression in hVSMCs, reduced proliferation, elevated β-galactosidase activity, and activated phosphorylated ERK1/2 and cytoplasmic aryl hydrocarbon receptor. These effects were attenuated by CD47 blockade. CKD plasma further enhanced IS- and TSP1-induced senescence. In vivo, 5/6 nephrectomy induced aortic wall thickening in WT but not in CD47KO mice. Aortic pERK1/2 was reduced in CD47KO mice despite persistent TSP1 upregulation. IS and TSP1 promote VSMC senescence through CD47-dependent ERK1/2 and AhR signalling. CD47 deletion protects against CKD-induced vascular remodelling, suggesting that CD47 blockade may represent a novel therapeutic strategy to mitigate vascular complications in CKD.

Chronic kidney disease (CKD) accelerates vascular dysfunction and cardiovascular disease, partly through accumulation of the uraemic toxin indoxyl sulphate (IS). Thrombospondin-1 (TSP1) and its receptor CD47 have been implicated in vascular pa-thology, but their role in CKD-associated vascular remodelling is unknown. We inves-tigated the contribution of TSP1–CD47 signalling to vascular smooth muscle cell (VSMC) dysfunction in CKD. Human aortic VSMCs (hVSMCs) were exposed to IS, TSP1, or plasma from patients with CKD. CKD was induced in wild-type (WT) and CD47-deficient (CD47KO) mice using 5/6 nephrectomy. Vascular changes were assessed by histology, immunohistochemistry, and molecular analyses. IS, TSP1, and CKD plasma increased TSP1 expression in hVSMCs, reduced proliferation, elevated β-galactosidase activity, and activated phosphorylated ERK1/2 and cytoplasmic aryl hydrocarbon receptor. These effects were attenuated by CD47 blockade. CKD plasma further enhanced IS- and TSP1-induced senescence. In vivo, 5/6 nephrectomy induced aortic wall thickening and fibrosis in WT but not CD47KO mice. Aortic pERK1/2 was reduced in CD47KO mice despite persistent TSP1 upregulation. IS and TSP1 pro-mote VSMC senescence through CD47-dependent ERK1/2 and AhR signalling. CD47 deletion protects against CKD-induced vascular remodelling, suggesting that CD47 blockade may represent a novel therapeutic strategy to mitigate vascular complications in CKD.

In mice, intermittent hypoxia is associated with an increase in microvessels in the hippocampus, whereas in humans with obstructive sleep apnoea (OSA), microvessels are lost from the heart and retina. The present study investigated microvascular changes in the hippocampus of patients with OSA, and whether patient age or use of continuous positive airway pressure (CPAP) influence microvascularisation. Using autopsy samples from 31 people with confirmed OSA, microvessels were immunolabelled and quantitatively analysed. Compared to the Low OSA group, the High OSA group had larger mean microvessel diameters in the fimbria and CA4, and greater mean microvessel length in the fimbria, which are indicative of microvascular remodelling. An absence of angiogenesis was indicated by similar mean vessel counts in both OSA severity groups. Increased age was associated with microvascular remodelling in the fimbria only. Treatment with CPAP was not associated with changed patterns of microvascularisation. We conclude that: (i) no evidence was found for angiogenesis in the human hippocampus in OSA or ageing; (ii) increased OSA severity is associated with microvascular remodelling in the fimbria and CA4; (iii) microvascular remodelling does not appear to be influenced by CPAP use; (iv) limited adaptability of the microvasculature may underpin the vulnerability of the hippocampus to hypoxic injury, particularly in severe OSA.

Ischemia is a primary cause of microvascular disease, particularly in the hippocampus, which is unusually vulnerable to hypoperfusion and hypoxia. Since intermittent hypoxia is a defining feature of obstructive sleep apnoea (OSA), the present study examined microvessels in autopsy tissue from patients with clinically confirmed OSA. Immunohistochemistry was performed on 30 hippocampal autopsy samples to investigate whether the incidence of microvascular abnormalities is associated with increased OSA severity, and if so, whether regular use of continuous positive airway pressure (CPAP) is protective. There were significantly more string vessels (4.3 ± 0.9 vs. 1.7 ± 0.4, p = 0.014), narrowing vessels (3.5 ± 1.0 vs. 0.9 ± 0.3, p = 0.024), strictures (2.6 ± 0.4 vs. 1.1 ± 0.2, p = 0.002) and total abnormalities (10.3 ± 1.5 vs. 3.7 ± 0.6, p = 0.001) in the CA1 subregion of the moderate–severe OSA group (mean ODI 35.9 ± 6.4 events/h sleep) than in the mild–moderate OSA group (mean ODI 18.5 ± 3.7 events/h sleep). There were no significant differences between regular CPAP users and non-CPAP users, or between younger and older individuals. We conclude that in moderate–severe OSA, the preponderance of microvascular abnormalities in the CA1, which are too narrow to carry blood, amplify its vulnerability to ischemia.