[C1q-neutralizing antibodies improves postpartum depressive-like behaviors in mice by regulating the C1q/C3 pathway]

To explore the role of C1q, the promoter of the classical pathway of the complement system, in regulating postpartum depressive-like behaviors in mice and the therapeutic mechanism of C1q-neutralizing antibodies.

Female C57BL/6 mouse models of postpartum depression established by hormone-simulated pregnancy (HSP) were evaluated for depression-like behaviors, and peripheral blood levels and hippocampal expressions of C1q were detected using ELISA and Western blotting. Immunofluorescence staining was used for detecting co-labeling of C1q and microglia, and the differentially expressed mRNAs in the hippocampus of HSP mice were analyzed using RNA sequencing. The Edinburgh Postnatal Depression Scale was used to screen patients with postpartum depression, from whom peripheral blood mononuclear cells were extracted for detecting C1q expression levels with Western blotting. The HSP mice were subjected to stereotactic injection of C1q-neutralizing antibody or a control IgG in the hippocampus, and the changes in depressive-like behaviors and hippocampal expression of C3 were examined.

The HSP mice exhibited obvious depressive behaviors, demonstrated by significantly decreased preference for sugar water and increased forced swimming and tail suspension time. The mouse models showed significantly increased peripheral blood C1q level and hippocampal expression level of C1q, accompanied by an increase in Iba1 and C1q co-labeling in the hippocampus. The expression level of C1q in peripheral monocytes was also significantly increased in patients with postpartum depression. In HSP mice, stereotactic injection of C1q-neutralizing antibody, but not the control IgG, obviously alleviated depressive-like behaviors, shown by significantly increased preference for sugar water and decreased forced swimming and tail suspension time, resulting also in decreased expression of C3 in the hippocampus and lowered serum levels of IL-6 and TNF-α.

C1q-neutralizing antibodies improve postpartum depressive-like behaviors in mice possibly by regulating the C1q/C3 signaling pathway.