Figure 1.

Inflammatory responses after intracerebral hemorrhage (ICH). After ICH, multiple blood components (e.g. erythrocytes, leukocytes, platelets) are released into the brain parenchyma where they can activate microglia, astrocytes, and mast cells by distinct pathways. After activation, microglia upregulate the expression of NLRP3 and TSPO and produce large amounts of pro-inflammatory factors. However, they also produce anti-inflammatory factors such as TGF-β which contributes to brain repair. Astrocytes contribute to the composition of the blood–brain barrier (BBB) and are destroyed directly after ICH, leading to BBB disruption. In addition, astrocytes secrete various pro-inflammatory factors that aggravate neuronal injury and brain damage. Pro-inflammatory factors from diverse cell types not only exacerbate BBB disruption and leukocyte infiltration, but also kill neurons directly. NLRP3: the nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3; TSPO: translocator protein.