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Meta-analysis of brain and blood transcriptional signatures of neuroimmune dysregulation in Schizophrenia: convergent evidence for excessive complement system activity and CX3CL1-CX3CR1 axis disruption

Boughanmi ME, Lespine LF, Leboyer M, Demily C, Rey R

Brain, behavior, and immunity, 2026

532 participants

Abstract

Background: Schizophrenia pathogenesis may involve aberrant synaptic pruning mediated by excessive complement system activity (CSA) and altered microglial function. Microglia and CSA are tightly regulated by neuro-immune regulators (NIREGs) which regulate adverse innate response and play a critical role in the regulation of the synaptic pruning process. This study investigated transcriptional alterations of NIREGs in the brain and blood tissues of individuals living with schizophrenia (SZ individuals) vs. healthy controls (HC).

Methods: Meta-analyses were performed on gene expression data from 532 SZ individuals and 623 HC in postmortem brain tissue, and 197 SZ individuals and 164 HC in peripheral blood. In addition to C4 gene, 9 NIREGs coding genes were analyzed: 3 genes encoding complement regulators (CD46, CD55, CD59), 3 genes encoding "don't eat me signals" (CX3CL1, CD200, CD47) and a further 3 genes encoding their microglial counter-receptors (CX3CR1, CD200R, SIRPα). Exploratory network analysis was performed in brain datasets.

Results: In brain tissue, SZ was associated with C4 overexpression and underexpression of CD46 and CX3CL1. Sex-specific transcriptional differences emerged for CD200 (female-specific) and CD59, CX3CR1 (male-specific). In the peripheral blood, CD46, CD55 and CD59 were overexpressed, while CX3CR1 was underexpressed. Brain and blood showed distinct altered expression patterns. However, disruption of the CX3CL1-CX3CR1 axis was observed in both…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 532 participants or records.

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