Researchers have found a link between increased levels of claudin-5 in the bloodstream and age-related neurodegeneration. This is distinct from the normal decline in claudin-5 levels associated with aging. Claudin-5 is a critical protein in the blood-brain barrier, which prevents unwanted substances from entering the brain. Dysfunction of the blood-brain barrier is characteristic of neurodegenerative conditions and aging, leading to inflammation in the brain. The reason for the increased levels of claudin-5 in the bloodstream in the context of neurodegenerative disease is still unknown, but it may be a response to barrier dysfunction or another underlying process.
A study investigated the diagnostic utility of claudin-5 in patients with mild cognitive impairment or Alzheimer’s disease. It found that plasma levels of claudin-5 were increased in patients with Alzheimer’s disease compared to cognitively normal individuals. The study also highlighted the role of the blood-brain barrier in transporting essential molecules and preventing harmful substances from entering the brain. Dysfunction of the blood-brain barrier has been observed in neuroinflammatory disorders and early Alzheimer’s disease, indicating a potential impairment of barrier components in related pathology.
Furthermore, breakdown of the blood-brain barrier in central nervous system diseases is associated with the invasion of immune cells and activation of astrocytes. This breakdown may lead to the degradation of claudin-5, reflected in elevated circulating levels of the protein in various CNS diseases. Interestingly, the study also found a negative correlation between plasma claudin-5 levels and age in patients with mild cognitive impairment and Alzheimer’s disease, suggesting a potential role of aging in claudin-5 levels in the context of cognitive deficits.
Link: https://doi.org/10.3390/ijms25031419
