HIV Protein Turns Brain's Own 'Gardeners' Against Neural Connections

Neurological complications like cognitive decline and pain are common in people with HIV, a phenomenon linked to the loss of synapses—the crucial connections between neurons. The precise mechanism, however, has remained a puzzle. New research using a mouse model with an HIV protein, gp120, reveals a destructive partnership between the virus and the brain’s own maintenance crew.

Scientists observed that two types of glial cells, microglia and astrocytes, became overzealous in their normal role of synaptic pruning. In the presence of the HIV protein, these cells began to engulf and destroy healthy synapses. This behaviour was highly specific: in the brain's frontal cortex, microglia trimmed one part of the synapse, while in the spinal dorsal horn, they removed entire connections. Astrocytes, meanwhile, exclusively targeted excitatory synapses in both regions.

Crucially, the team confirmed this destructive engulfment also occurs in brain tissue from human HIV patients, providing a direct link between this cellular behaviour and the damage seen in the human central nervous system.