Università degli studi di Modena e Reggio Emilia

Vortioxetine (VTX) is a multimodal antidepressant with an extensive pharmacological profile that includes modulation of various neurotransmitter systems, neuroprotective activity, and beneficial effects on cognitive functions. Recent research has revealed a novel aspect of VTX's activity - its antiinflammatory effects - that suggests an intriguing molecular mechanism may underpin its therapeutic benefits. Neuroinflammation, dysfunctional neurogenesis and neurotransmission, and dysregulation of the hypothalamus– pituitary–adrenal (HPA) axis are all pivotal in the onset and progression of depression. One particular immune-inflammatory pathway overactivated in brain disorders is the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, a multiprotein complex. This complex's activation is mediated by NF-kB and reactive oxygen species (ROS) signalling pathways, leading to caspase-1-dependent release of the proinflammatory cytokines, IL-1β and IL-18. Mounting evidence implicates NLRP3 inflammasome in neuroinflammation- related disorders, with its activation associated with cognitive function impairment. Of note, microglia, the resident immune cells crucial for brain plasticity, express high levels of the NLRP3-inflammasome components. Our initial findings indicate that VTX exerts a region-dependent modulatoryeffect on the NLRP3-inflammasome system in a LPS-induced memory impairment in vivo model. Furthermore, VTX's ability to modulate immune response suggests that microglia could be a direct target of the drug. AIM: In light of the compelling evidence surrounding the role of the NLRP3 inflammasome in cognitive dysfunctions and the recent discovery of VTX's anti-inflammatory activity, we aimed to investigate the molecular effects induced by VTX pre-treatment in the presence or absence of the inflammasome-inducer LPS in a well-established in vitro model of mouse microglia: BV2 cells. METHODS: To dissect the influence of VTX pre-treatment (24h) on the NLRP3 inflammasome signaling pathway and microglial polarization, we analyzed gene and protein expression in BV2 cells stimulated with LPS or vehicle for 6h. We also scrutinized the activation/translocation of NF-kB and ROS release under these conditions. We applied one-way or two-way ANOVA followed by Tukey’s post hoc test for statistical analysis based on the experimental design. RESULTS: Our data demonstrate that short-term exposure to LPS significantly induces the activation/translocation of NF-kB signaling and ROS release in BV2 cells. We observed a time-dependent transcriptional upregulation of the inflammasome complex, IL-1β and IL-18, and microglial pro-inflammatory targets post-LPS stimulation, alongside a downregulation of the anti-inflammatory factors. Interestingly, a pre-treatment with VTX (10 nM) for 24h effectively modulated the LPS-induced NF-kB translocation and ROS production compared to control cells. Cells pre-treated with VTX exhibited lower levels of LPS-induced NLRP3 inflammasome- and microglia pro-inflammatory-related targets. However, VTX did not influence the expression of anti-inflammatory factors in both unstimulated and LPS-stimulated BV2 cells. CONCLUSIONS: Our findings reinforce the emerging evidence that supports VTX's anti-inflammatory activity. This activity is mediated via modulation of the inflammasome signaling pathway, which plays a pivotal role in the inflammatory response of microglia cells.