Tag: abdominal aortic aneurysm

Categories : Cardiovascular DiseaseTags :

Sleep Apnoea May Increase Risk of Abdominal Aortic Aneurysms

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Photo by Mert Kahveci on Unsplash

Obstructive sleep apnoea may be a risk factor for developing abdominal aortic aneurysms, according to researchers from the University of Missouri School of Medicine and NextGen Precision Health.

Abdominal aortic aneurysms occur when the aorta swells and potentially ruptures, causing life-threatening internal bleeding. Obstructive sleep apnoea is characterised by episodes of a complete or partial airway collapse with an associated drop in oxygen saturation or arousal from sleep. It can increase the risk of developing cardiovascular problems. Citing studies that indicate a higher prevalence of abdominal aortic aneurysms in patients with obstructive sleep apnoea, MU researchers examined the link between the two using mouse models.

The research team found that intermittent hypoxia caused by obstructive sleep apnoea increased the susceptibility of mice to develop abdominal aortic aneurysms.

“Chronic intermittent hypoxia by itself is not enough to cause abdominal aortic aneurysms, but for a patient with obstructive sleep apnoea who also has additional metabolic problems like obesity, our findings suggest it may help degrade aortic structures and promote aneurysm development,” said Luis Martinez-Lemus, study author and a professor of medical pharmacology and physiology.

Intermittent hypoxia happens during obstructive sleep apnoea when throat muscles relax and block the flow of air into the lungs. According to the research, the loss of oxygen triggers certain enzymes called MMPs. The increased enzyme activity can degrade the extracellular matrix, which acts like a cell scaffolding network, weakening the aorta.

“Patients with abdominal aortic aneurysms usually don’t notice any symptoms, except for some back and belly pain, until the aneurysm bursts. Once that happens, it’s crucial to get the patient to surgery quickly so doctors can repair the aorta,” said Neekun Sharma, the lead author of the study. “Learning how these aneurysms develop can help us find ways to monitor or slow down their progression, especially for patients who have obstructive sleep apnoea.”

Source: University of Missouri-Columbia

Categories : Cardiovascular DiseaseTags :

Uncovering the Mechanical Basis for Abdominal Aortic Aneurysm

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Source: Mat Napo on Unsplash

A new study reveals the mechanical basis underlying abdominal aortic aneurysm (AAA), a complex and life-threatening vascular disease with high incidence worldwide.

Known as the ‘silent killer’, most AAAs are asymptomatic, often undetected until rupture, and involve a poorly understood set of mechanical and biochemical events. Studies have shown that AAA is associated with both vascular inflammation and increased stiffness. That the latter happens with ageing partly explains why AAA is almost only ever seen in people over 65.

Evidence suggests that abnormal acclimation of vascular smooth muscle cells (VSMC) to biomechanical disturbances, such as increased circumferential stress in hypertension, can lead to the development of AAA. However, not much is known about the molecular drivers of altered mechanobiological behaviors of VSMC. Understanding these might provide promising targetable signals that could repress AAA progression and limit rupture incidents.

Now, researchers have demonstrated mechanobiological changes in VSMC and identified a key ion channel that is involved in the development of AAA. In a new study, in Nature Communications, they describe how VSMC gradually adopts a solid-like state by upregulating cytoskeleton crosslinker, α-actinin2, which powers the mechanosensitive ion channel Piezo1.

“Our team applied biomechanical engineering to study aneurysm pathology,” explained study leader Professor Weiqiang Chen. “In contrast to the extensive study of aorta wall properties, we explored how a cell’s mechanical sensitivity, or ‘mechanosensation’ to mechanical stimuli presents an innovative perspective in revealing disease pathogenesis and progression mechanisms.”

Measuring misshapen VSMC with a novel ultrasound tweezers system and a single-cell RNA sequencing technique, the researchers identified Piezo1, which critically regulates VSMC mechanical sensitivity. Inhibiting Piezo1 in mice prevented them from developing AAA, by relieving pathological vascular remodeling. The researchers concluded that deviations of mechanosensation behaviours of VSMC is detrimental for AAA, and Piezo1 could be responsible for mechanically fatigued aorta in AAA. This could lead to new mechano-medical approaches to treating this devastating cardiovascular disease.

Source: EurekAlert!