HIV/AIDS Presentation Flashcards
Trojan Horse mechanism
How HIV sneaks into the central nervous system by hiding inside immune cells
Trojan horse mechanism steps
1) HIV infects monocytes in the bloodstream because they are naturally able to cross the blood brain barrier
2) Inflammation from HIV infection increases chemokines, which attract monocytes to the brain
3) The infected monocytes migrate across the blood brain barrier using diapedesis, which is a normal immune cell route where the whit blood cells squeeze between the endothelial cells of the blood brain barrier
4) Once inside, monocytes become macrophages and infect resident microglia
5) HIV replicates inside microglia and triggers chronic inflammation through cytokines, damaging neurons and causing neurocognitive problems
Neurotoxic viral proteins
Proteins produced by viruses
HIV creates many viral proteins, but GP120 and Tat are the ones that matter most
GP120 binds to the endothelial and glial cell receptors, which damages tight junctions and increases cytokine production
This allows more infected cells to cross the blood brain barrier and the cytokines cause a positive feedback loop of inflammation
Tat increases reactive oxygen species, leading to the cell death of BBB endothelial cells, further allowing more virus infected cells to enter the CNS
Picture
In this picture, the cell is carrying HIV-1 in the blood stream, and it crosses the endothelial cell layer of the BBB via diapedesis
G120 and Tat are released by the macrophage and damage the BBB
The macrophage infects the microglia
Infected microglia releases cytokines to damage the BBB
Leads to positive feedback loop of inflammation and brain injury
Effects of HIV inside of the brain
Causes significant inflammation in the body
Damages the spinal cord and brain
Prevent nerve cells from working properly
HIV vs AIDS
AIDS is the last and most severe form of HIV
HIV causes mild neurological damage, such as subtle memory/focus problems and mild symptoms of DSP, which I will talk about in a second
Opportunistic infections and seizure are rare
AIDS causes profound immunosuppression
The immune system is very weak, soi there is a high risk of opportunistic infections and cancers, and DSP and very severe
The neurological damage has heightened, so now there’s severe memory loss and confusion, spasticity, motor decline, seizures, and sometimes blindness
HIV/AIDS Central Nervous System Problems
Vacuolar myelopathy
HIV associated neurocognitive disorders
Vacuolar myelopathy
A condition where the white matter of the spinal cord develops vacuoles, or fluid filled spaces, due to myelin sheath damage
This is the most common cause of spinal cord dysfunction in people with AIDS
Its found in people who have advanced HIV or AIDS
Caused by chronic HIV-related inflammation, not direct viral infection of neurons
HAND
HIV associated neurocognitive disorders
a group of conditions that describe cognitive, motor, and behavioral impairments caused by HIV effects
Asymptomatic neurocognitive impairment and mild neurocognitive disorder are the first two stages of HAND
They are found in people who have early or treated HIV
Affects attention, memory, and multitasking with little interference in daily activities
HIV associated dementia is found in people who have advanced HIV or AIDS
it causes severe cognitive deficits, such as memory loss, motor problems, and behavioral changes
This is a result of chronic inflammation affecting the brains neurons
HIV related peripheral neuropathy
distal symmetric polyneuropathy
inflammatory demyelinating polyneuropathy
distal symmetric polyneuropathy
a bilateral and symmetrical degeneration of peripheral nerves, especially in feet and lower legs, causing numbness and pain
most common neurological complication of hiv infection, especially in post-treatment
inflammatory demyelinating polyneuropathy
a group of autoimmune nerve disorders where the bodys immune system attacks the myeline sheath, leading to nerve dysfunction
opportunistic infections
cryptococcal meningits
cytomegalovirus retinis
toxoplasma encephalitis
cryptococcal meningitis
infects the meninges and causes chronic meningeal inflammation
cytomegalovirus retinis
infects and destroys retinal cells and blood vessels in retina
causes retinal necrosis
leads to vision loss
toxoplasma encephalitis
forms multiple abscesses, or localized swelling and necrosis, in the brain
picture 2
top left: neuroinflammation due to infected microglia
top right: hiv indirectly causes neuronal death through inflammatory cytokines and neurotoxic viral proteins
bottom right: synaptic damage and dysregulated neurotransmitter release
bottom left: shows amyloid beta plaques and protein deposition, which are usually associated with Alzheimer’s disease which refers to HIV-associated neurological disorder, or HAND, that affects memory and brain function
