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Blood-brain barrier

From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history
(Redirected from Blood brain barrier)

The blood-brain barrier or BBB is a protects the central nervous system from potentially harmful chemicals and pathogens in the blood. In the BBB, the lining of the blood vessels (endothelium) is knitted closely together in tight junctions, becoming a powerful filter for blood that enters the brain.[1]

BBB Permeability[edit | edit source]

Blood-brain barrier permeability (BBBP) measures how much the BBB filters your blood. A more permeable BBB may potentially let in more harmful molecules, triggering local inflammation. Chronic brain inflammation can lead to cognitive symptoms like brain fog.[2]

Transforming growth factor beta (TGF-β) is a cytokine that can make the BBB more permeable.[2] A 2015 review found people with ME/CFS frequently have higher levels of TGF-β.[3] A 2017 study found that higher levels of TGF-β were linked to more severe ME/CFS symptoms.[4]

Circumventricular organs[edit | edit source]

Circumventricular organs (CVOs) are parts of the brain which sit outside the blood brain barrier. They interact directly with the blood through dense capillaries. This direct interaction is important for neuroendocrine organs that secrete chemicals directly into the blood, such as the pineal gland. CVOs also include sensory structures like the subfornical organ, which detects sodium levels in the blood and helps control thirst.[5]

Due to their direct connection with the bloodstream, CVOs are often the first parts of the central nervous system exposed to dangerous molecules. The microglia in charge of "guarding" the CVOs can then trigger a neuroinflammatory response.[5]

Sometimes, if inflammatory cytokines are present in very high levels, they can seep into the rest of the brain via the CVOs, bypassing the protective BBB.[6]

Diseases associated with weakened BBB[edit | edit source]

In addition to ME/CFS, several health conditions have been associated with a weakened blood-brain barrier:[2][7]

Drugs[edit | edit source]

Most drugs are unable to cross the BBB, which restricts treatment for certain conditions. Drugs that can cross the barrier need to be small and lipid soluble.[7]

See also[edit | edit source]

Notable Research[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. Tate, Warren; Walker, Max; Sweetman, Eiren; Helliwell, Amber; Peppercorn, Katie; Edgar, Christina; Blair, Anna; Chatterjee, Aniruddha (May 25, 2022). "Molecular Mechanisms of Neuroinflammation in ME/CFS and Long COVID to Sustain Disease and Promote Relapses". Frontiers in Neurology. 13. doi:10.3389/fneur.2022.877772. ISSN 1664-2295.
  2. Jump up to: 2.0 2.1 2.2 2.3 Greene, Chris; Connolly, Ruairi; Brennan, Declan; Laffan, Aoife; O’Keeffe, Eoin; Zaporojan, Lilia; O’Callaghan, Jeffrey; Thomson, Bennett; Connolly, Emma; Argue, Ruth; Martin-Loeches, Ignacio (February 22, 2024). "Blood–brain barrier disruption and sustained systemic inflammation in individuals with long COVID-associated cognitive impairment". Nature Neuroscience: 1–12. doi:10.1038/s41593-024-01576-9. ISSN 1546-1726.
  3. S, Blundell; Kk, Ray; M, Buckland; Pd, White (2015 Nov). "Chronic fatigue syndrome and circulating cytokines: A systematic review". Brain, behavior, and immunity. 50. doi:10.1016/j.bbi.2015.07.004. ISSN 1090-2139. PMID 26148446. Check date values in: |date= (help)
  4. Jg, Montoya; Th, Holmes; Jn, Anderson; Ht, Maecker; Y, Rosenberg-Hasson; Ij, Valencia; L, Chu; Jw, Younger; Cm, Tato; Mm, Davis (August 22, 2017). "Cytokine signature associated with disease severity in chronic fatigue syndrome patients". Proceedings of the National Academy of Sciences of the United States of America. 114 (34). doi:10.1073/pnas.1710519114. ISSN 1091-6490. PMID 28760971.
  5. Jump up to: 5.0 5.1 S, Miyata (October 6, 2022). "Glial functions in the blood-brain communication at the circumventricular organs". Frontiers in neuroscience. 16. doi:10.3389/fnins.2022.991779. ISSN 1662-4548. PMID 36278020.
  6. VanElzakker, M (January 9, 2019). "Neuroinflammation and Cytokines in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): A Critical Review of Research Methods". Frontiers in Neurology. 9.
  7. Jump up to: 7.0 7.1 Dotiwala, Ari (2023). "Anatomy, Head and Neck: Blood Brain Barrier". National Library of Medicine.