Saturday, January 11, 2025

Head trauma wakes the brain’s sleeping viruses

What a nightmare! Pardon my bad joke!

More evidence that concussions and other head injuries are dangerous!

"Boxers, football players, and other athletes who engage in contact sports frequently shrug off concussions and other head injuries. But according to numerous epidemiological studies, which have established a link between head trauma and neurodegenerative diseases like Alzheimer’s, these players end up paying for those blows later on in life. Now, new research suggests that blows to the head can reactivate viruses sleeping inside the brain, leading to inflammation and dementia. ..."

From the editor's summary and abstract:
"Editor’s summary
Infection with herpes simplex virus type 1 (HSV-1) is common, lifelong, and often in a latent state with periodic reactivation. It is a risk factor for neurodegenerative disease and dementia in some individuals, as are repeated head injuries like concussions. Cairns et al. found that latent HSV-1 was reactivated by repeated mechanical injury to mimic concussions in a three-dimensional human brain tissue model. This mechanism triggered the aggregation of β amyloid and other pathological features associated with neurodegenerative diseases in a manner dependent on the inflammatory cytokine IL-1β. The findings directly link two risk factors in a mechanism that may contribute to dementia-related disease.  ...
Abstract
Infection with herpes simplex virus type 1 (HSV-1) in the brains of APOE4 carriers increases the risk of Alzheimer’s disease (AD). We previously found that latent HSV-1 in a three-dimensional in vitro model of APOE4-heterozygous human brain tissue was reactivated in response to neuroinflammation caused by exposure to other pathogens.
Because traumatic brain injury also causes neuroinflammation, we surmised that brain injury might similarly reactivate latent HSV-1. Here, we examined the effects of one or more controlled blows to our human brain model in the absence or presence of latent HSV-1 infection. After repeated, mild controlled blows, latently infected tissues showed reactivation of HSV-1; the production and accumulation of β amyloid and phosphorylated tau (which promotes synaptic dysfunction and neurodegeneration); and activated gliosis, which is associated with destructive neuroinflammation. These effects are collectively associated with AD, dementia, and chronic traumatic encephalopathy (CTE) and were increased with additional injury but were absent in mock-infected tissue. Blocking the cytokine IL-1β prevented the induction of amyloid and gliosis in latently infected monolayer cultures after scratch wounding. We thus propose that after repeated mechanical injuries to the brain, such as from direct blows to the head or jarring motions of the head, the resulting reactivation of HSV-1 in the brain may contribute to the development of AD and related diseases in some individuals."

ScienceAdviser

Study shows head trauma may activate latent viruses, leading to neurodegeneration "Researchers at Tufts University suggest results may lead to preventive strategies using antiviral drugs"

Using lab-grown human mini-brains, scientists find links between head trauma, herpes, and Alzheimer’s "Research suggests concussions could awaken latent infections in the brain and lead to dementia"

Head Trauma May Activate Latent Viruses in the Brain, Leading to Neurodegeneration (original news release) "Researchers at Tufts suggest results may lead to preventive strategies using antiviral drugs after concussions"



Fig. 1. 3D human brain models of TBI mimic direct impact injury and mild concussion.


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