Figure 1.

Inflammation in Huntington's disease. The mutant HTT transcript and protein are expressed in many cell types, including neurons, astrocytes, and blood cells of HD patients. The pathogenic effect may be triggered by expanded CAG repeat hairpins, cytoplasmic protein aggregates, N-terminal fragments of huntingtin, or toxic frameshifting products, and so forth. It is currently not clear what pathways are primarily involved in inducing the inflammatory response observed in the CNS and peripheral immune system. This effect is observed in the brain and peripheral tissues, indicating crosstalk in the signaling between distant tissues. The observed immune effects include elevated cytokine levels, caspase pathways activation, induction of apoptosis, dysregulation of gene expression, or decreased immune cell migration.