Complement Pathway
complement pathway
The role of the complement pathway in post-traumatic sleep disruption and epilepsy
While traumatic brain injury (TBI) acutely disrupts the cortex, most TBI-related disabilities reflect secondary injuries that accrue over time. The thalamus is a likely site of secondary damage because of its reciprocal connections with the cortex. Using a mouse model of mild cortical injury that does not directly damage subcortical structures (mTBI), we found a chronic increase in C1q expression specifically in the corticothalamic circuit. Increased C1q expression co-localized with neuron loss and chronic inflammation, and correlated with disruption in sleep spindles and emergence of epileptic activities. Blocking C1q counteracted these outcomes, suggesting that C1q is a disease modifier in mTBI. Single-nucleus RNA sequencing demonstrated that microglia are the source of thalamic C1q. Since the corticothalamic circuit is important for cognition and sleep, which can be impaired by TBI, this circuit could be a new target for treating TBI-related disabilities
More than Bystanders in Dementia, Learning What Microglia Do
Genome-wide association studies implicate microglia in Alzheimer’s disease (AD) pathogenesis, but how microglia contribute to cognitive decline in AD is unclear. Emerging research suggests microglia, the resident macrophages of the central nervous system, to be active participants in brain wiring. One mechanism by which microglia help eliminate synapses is through the classical complement pathway (C1q, CR3/C3). Data from multiple laboratories collectively suggest that there may be an aberrant reactivation of the complement-dependent pruning pathway in multiple models of neurologic diseases including AD. These data altogether suggest that microglia participate in synaptic pathology. However, how and which synapses are targeted are unknown. Furthermore, whether microglia directly impair synaptic function is unknown. Primary goals of my laboratory are to understand how higher cognitive functions such as learning and memory involve microglial biology in the healthy adult brain and dissect immune mechanisms behind the region-specific vulnerability of synapse loss and neuronal dysfunction during disease. Mechanistic insight into local signals that regulate neuroglia interactions will be key to developing potential therapeutic avenues to target in disease.