Zalosnik, M. I. | Search bioRxiv

bioRxiv2020

MECP2 DEFICIENCY ALTERS M1/M2 GENE EXPRESSION IN BONE MARROW-DERIVED MACROPHAGES UPON STIMULATION

Rett Syndrome (RTT) is a neurodevelopmental disorder mostly caused by mutations in the X-linked gene, MeCP2, which encodes for methyl-CpG binding protein 2 (MeCP2). MeCP2 is member of a family of methyl binding proteins that control the expression of several genes according to the genomic context. Emerging evidence suggests that immune dysfunctions would actively contribute to the pathogenesis of RTT. Macrophages are key effector cells that participate in several critical aspects of immune responses. The aim of our work was to assess the response of macrophages in vitro in the context of polarizing stimuli. We used bone marrow-derived macrophages (BMDM) obtained from MeCP2308/y mice, a mouse model that carries a truncated form of MeCP2. Since MeCP2 is expressed as a "partially functional" protein in humans with RTT it becomes crucial to establish how the presence of a mutant form of MeCP2 affects immune responses to support the normal homeostasis of individuals. MeCP2 deficiency induced exacerbation of pro-inflammatory mediators and deficient immune regulatory responses under polarizing conditions. These findings suggest that MeCP2 plays a role in the establishment of macrophage polarization in the context of immune activation. Present results may have important implications in understanding RTT pathogenesis and for developing potential treatments. Conflict of interestThe authors declare no conflicts of interest.

immunology↗

bioRxiv2020

MeCP2 deficiency exacerbates the neuroinflammatory setting and autoreactive response during an autoimmune challenge: implications for Rett Syndrome.

Background: Rett syndrome is a severe and progressive neurological disorder linked to mutations in the MeCP2 gene located on the X chromosome. So far it has not been established how the presence of a mutant form of MeCP2 can maintain essential regulation of immune responses to support the normal homeostasis of individuals. Since MeCP2 is mostly expressed as a "partially functional" protein in humans with RTT, the aim of our work was to evaluate whether a mutation in MeCP2 interferes with the induction of neuroinflammatory responses in real time. Methods: We used MeCP2308/y mouse model (MUT) and exposed it to an autoimmune challenge, experimental autoimmune encephalomyelitis (EAE). WT and MUT mice were immunized with CFA-MOG or CFA alone (control) and clinical scores were evaluated daily. Animals were sacrificed at either 12 days post-induction (dpi, acute stage) or 30 dpi (chronic stage) and spleen and spinal cord were collected from individual mice for further studies. Cellular infiltration and microgliosis was evaluated by IHC. Cytokine production was assessed in spinal cord and in cultured splenocytes after MOG activation ex-vivo by cytometry and real time RT-PCR. Results: Our results showed that MeCP2 deficiency increased the susceptibility to develop EAE, along with a defective induction of anti-inflammatory responses and an exacerbated MOG-specific reactivity with high IFN{gamma} expression in peripheral immune sites. During the chronic stage, an increase in gene expression of pro-inflammatory cytokines (IFN{gamma}, TNF and IL-1{beta}) and downregulation of genes relevant for immune regulation (IL-10, FoxP3 and CX3CR1) was found in MUT-EAE spinal cords. Conclusions: This is the first study performed in a MeCP2 mutant mouse model that explores the pathophysiology and neuroinflammation in the context of an autoimmune challenge. We could establish that an MeCP2 mutation act intrinsically affecting neuroimmune interactions by promoting an inflammatory environment and a deficient immune regulatory setting. These results are relevant for understanding the consequences of MeCP2 mutations on immune homeostasis in MeCP2-related disorders, as well as setting the bases for further therapeutic interventions that consider the immune status in patients.

neuroscience↗