Oligodendroglia Are Primed for Antigen Presentation in Response to Chronic Stress-Induced Microglial-Derived Inflammation.

Chronic stress is a major contributor to the development of major depressive disorder, one of the leading causes of disability worldwide. Using a model of repeated social defeat stress in mice, we and others have reported that neuroinflammation plays a dynamic role in the development of behavioral deficits consistent with social avoidance and impaired reward responses. Animals susceptible to the model also exhibit hypomyelination in the medial prefrontal cortex, indicative of changes in the differentiation pathway of cells of the oligodendroglial lineage (OLN). We computationally confirmed the presence of immune oligodendrocytes, a population of OLN cells, which express immune markers and myelination deficits. In the current study, we report that microglia are necessary to induce expression of antigen presentation markers (and other immune markers) on oligodendroglia. We further associate the appearance of these markers with changes in the OLN and confirm that microglial changes precede OLN changes. Using co-cultures of microglia and OLN, we show that under inflammatory conditions the processes of phagocytosis and expression of MHCII are linked, suggesting potential priming for antigen presentation by OLN cells. Our findings provide insights into the nature of these OLN cells with immune capabilities, their obligatory interaction with microglia, and identify them as a potential cellular contributor to the pathological manifestations of psychosocial stress.