Brain-derived neurotrophic factor and inflammation in depression: Pathogenic partners in crime?

Figure 4 Brain-derived neurotrophic factor deficiency impairs resolution of microglial inflammatory phenotypes. Brain-derived neurotrophic factor (BDNF) levels are altered by genetics and environmental circumstances. Reduced levels of BDNF impair microglia regulation after inflammation. Hyper-active microglia contribute to blood-brain barrier disruption and express higher levels of pro-inflammatory cytokines and kynurenine metabolism pathway enzymes. Individuals with hyper-active microglia are vulnerable to developing symptoms of depression after inflammatory challenge. BDNF: Brain-derived neurotrophic factor.