The role of the blood–brain barrier in hypertension

Abstract

What is the topic of this review? This review highlights the importance of the blood-brain barrier in the context of diseases involving autonomic dysfunction, such as hypertension and heart failure. What advances does it highlight? It highlights the potential role of pro-inflammatory cytokines, leucocytes and angiotensin II in disrupting the blood-brain barrier in cardiovascular diseases. Advances are highlighted in our understanding of neurovascular unit cells, astrocytes and microglia, with a specific emphasis on their pathogenic roles within the brain. The blood-brain barrier (BBB) is a crucial barrier that provides both metabolic and physical protection to an immune-privileged CNS. The BBB has been shown to be disrupted in hypertension. This review addresses the importance of the BBB in maintaining homeostasis in the context of diseases related to autonomic dysfunction, such as hypertension. We highlight the potentially important roles of the immune system and neurovascular unit in the maintenance of the BBB, whereby dysregulation may lead to autonomic dysfunction in diseases such as heart failure and hypertension. Circulating leucocytes and factors such as angiotensin II and pro-inflammatory cytokines are thought ultimately to downregulate endothelial tight junction proteins that are a crucial component of the BBB. The specific mechanisms underlying BBB disruption and their role in contributing to autonomic dysfunction are not yet fully understood but are a growing area of interest. A greater understanding of these systems and advances in our knowledge of the molecular mechanisms causing BBB disruption will allow for the development of future therapeutic interventions in the treatment of autonomic imbalance associated with diseases such as heart failure and hypertension.

The role of CNS macrophages in streptococcal meningoencephalitis

“…The BBB permeability can be affected by a plethora of factors such as viral and bacterial infection, traumatic brain injury, poisoning, or hypertension . Interestingly, it seems that factors from the gut microbiota can also affect BBB permeability, because germ‐free or antibiotic‐treated mice show an increased BBB permeability and altered expression of tight junction proteins .…”

Nicorandil preserves blood-brain barrier and improves memory impairment in hypertensive rats

“…Microvessel culture studies have shown that AT1R activation increases BBB permeability [44,45]. Inflammatory IL-1β, and TNF-α, which are shown to increase in the circulation of RVH rats also disrupt the integrity of BBB [46,47]. Another mechanism that damages the BBB in RVH is the disintegration of adventitia layer in the cerebral vascular endothelium by MMP enzymes, which are activated by inadequate cerebral blood flow.…”

COVID-19, Angiotensin Receptor Blockers, and the Brain

“…SARS-CoV-2 may bind to its receptor Angiotensin Converting Enzyme 2 (ACE2) expressed in endothelial cells of cerebral capillaries (Peña Silva et al 2012), and within the brain parenchyma in both neurons and microglia (Yamagata et al 2020). Since the blood-brain barrier is disrupted in hypertension (Setiadi et al 2018) and hypertension is a frequent comorbidity for COVID-19, these patients may have a higher risk of cerebral complications.…”