The choroid plexus and the paradox of interferons in the aging brain

The choroid plexus (CP) function is largely viewed as the source of cerebrospinal fluid (CSF) and as a barrier between the blood and the CSF. Other functions of the CP are becoming increasingly recognized as in the recent publication by Baruch et. al. who demonstrate increased expression of interferon type I mRNA signature (irf7, ifnß and ifit1) in CP of aged brains compared to younger brains, whereas interferon type II dependent genes (icam1, cxcl10, and ccl17) are reduced in the aging CP. The authors speculate an IFN-dependent mechanism that plays a role in the aging process and cognitive decline. This short communication summarizes the findings by the authors and highlights the seemingly paradoxical roles of IFN type I and type II in neuroinflammation.