The meninges consist of three membranes that surround and protect the central nervous system (CNS). Recent studies have noted the existence of myeloid cells residing there, but little is known about their ontogenesis and function, and it is not known whether other populations of meningeal immune cells play an important role (see Perspective from Nguyen and Kubes). Cugurra et al. found in mice that much of the continually replenished myeloid cells in the dura are not derived from the blood, but rather pass through the cranial bone marrow through specialized channels. In models of CNS injury and neuroinflammation, the authors demonstrated that these myeloid cells have an immunoregulatory phenotype compared to their more inflammatory blood-derived counterparts. Likewise, Brioschi et al. show that the meninges harbor B cells which are also derived from the bone marrow of the skull, mature locally and probably acquire a tolerogenic phenotype. They further found that the brains of aging mice are infiltrated by a second population of age-associated B cells, which originate from the periphery and can differentiate into plasma cells secreting autoantibodies after encountering CNS antigens. Together, these two studies could inform future treatment of neurological diseases.
Science, abf7844, abf9277, this number p. eabf7844, p. eabf9277; see also abj8183, p. 396