Aicardi-Goutières syndrome (AGS) presents as a severe autosomal recessively inherited neurological brain disease. Clinical and neurological manifestations closely resemble those of congenital viral infection and are generally attributed to a perturbation of innate immunity including a long lasting lymphocytosis and production of interferon-alpha (IFNalpha) in the central nervous system. To clarify the innate immune response evoked in these diseases, we used a 30-mer multiplexed luminex system to measure multiple cytokines and growth factors in the cerebrospinal fluid and serum of patients with AGS and viral meningitis or encephalitis, and febrile controls in whom infection could not be substantiated. In addition to the previously described IFNalpha, both AGS and viral diseases were characterized by expression of CXCL10 and CCL2. In contrast to AGS, viral infection resulted in high levels of IL-6 and CXCL8 in the CNS. Postmortem immunohistochemical staining of brain sections showed that in both AGS and viral CNS infection, astrocytes were responsible for the production of cytokines and not the infiltrating leukocytes. In summary, our data indicate that astrocytes are the predominant cell type responsible for the production of IFNalpha and CXCL10 in AGS. Whereas IFNalpha is assumed to be involved in the neurodegeneration, calcifications and seizures in AGS, CXCL10 may act as the chemoattractant responsible for the influx of activated lymphocytes into the brain. The lack of the inflammatory cytokines IL-6 and CXCL8 in AGS suggest that the neuroinflammatory reaction in this disease is distinct from viral disease.

In Aicardi-Goutières syndrome (AGS), as in systemic lupus erythematosus (SLE) and Sjögren's syndrome, an increased level of interferon alpha (IFN-alpha) is involved in the pathogenesis of the disease. In SLE and Sjögren's syndrome, cytokine production originates in plasmacytoid dendritic cells (pDCs) under the influence of immune complexes formed by DNA and RNA from improperly removed apoptotic or necrotic cells, together with IgG autoantibodies. We studied the role of soluble factors in the serum or cerebrospinal fluid (CSF) of AGS patients and their capacity to stimulate pDCs to produce IFN-alpha. Our findings show that, in contrast to SLE, there is no decrease in the number of circulating pDCs in AGS patients. Secondly, unlike the autoantibodies in the serum of patients with SLE or Sjögren's syndrome, there is no increased frequency of antinuclear antibodies (ANA) or other soluble factors inducing IFN-alpha from pDCs. These data indicate that the origin of IFN-alpha in AGS is different from that in the autoimmune diseases tested.