Cerebral complement C1q activation in chronic Toxoplasma infection

Jianchun Xiao, Ye Li, Kristin L. Gressitt, Helen He, Geetha Kannan, Tracey L. Schultz, Nadezhda Svezhova, Vern B. Carruthers, Mikhail Pletnikov, Robert H. Yolken, Emily G. Severance

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Exposure to the neurotropic parasite, Toxoplasma gondii, causes significant brain and behavioral anomalies in humans and other mammals. Understanding the cellular mechanisms of T. gondii-generated brain pathologies would aid the advancement of novel strategies to reduce disease. Complement factor C1q is part of a classic immune pathway that functions peripherally to tag and remove infectious agents and cellular debris from circulation. In the developing and adult brain, C1q modifies neuronal architecture through synapse marking and pruning. T. gondii exposure and complement activation have both been implicated in the development of complex brain disorders such as schizophrenia. Thus, it seems logical that mechanistically, the physiological pathways associated with these two factors are connected. We employed a rodent model of chronic infection to investigate the extent to which cyst presence in the brain triggers activation of cerebral C1q. Compared to uninfected mice, cortical C1q was highly expressed at both the RNA and protein levels in infected animals bearing a high cyst burden. In these mice, C1q protein localized to cytoplasm, adjacent to GFAP-labeled astrocytes, near degenerating cysts, and in punctate patterns along processes. In summary, our results demonstrated an upregulation of cerebral C1q in response to latent T. gondii infection. Our data preliminarily suggest that this complement activity may aid in the clearance of this parasite from the CNS and in so doing, have consequences for the connectivity of neighboring cells and synapses.

Original languageEnglish (US)
Pages (from-to)52-56
Number of pages5
JournalBrain, Behavior, and Immunity
StatePublished - Nov 1 2016


  • Glia
  • MAG1 antibodies
  • Neurons
  • Prefrontal cortex
  • Psychiatry
  • Toxoplasmosis

ASJC Scopus subject areas

  • Immunology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience


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