Bifidobacterium lactis-Derived Vesicles Attenuate Hippocampal Neuroinflammation by Targeting IL-33 to Regulate FoxO6/P53 Signaling

Hippocampal Neuroinflammation (HNF) is a critical driver of cognitive impairment. The lipopolysaccharide (LPS) accumulate amyloid beta (Aβ) and lead to HNF. The Bifidobacterium lactis (BL) 99 have anti-inflammatory ability. However, whether BL99-derived microbiota-derived vesicles (MV) could alleviate LPS-induced HNF remains unclear.

Here, we hypothesized that BL99-MV alleviated LPS-induced HNF to promote HT22 survival and synaptic development by regulating FoxO6/P53 signaling by targeting IL-33.

To investigate, we used ultrafiltration with ultracentrifuge to extract BL99-derived-MV (BL99-MV). We used hippocampal neuronal HT22 cells (HT22) to establish the LPS-induced HNF model, and explored whether BL99-MV alleviate LPS-induced HNF.

The confocal microscopy showed that BL99-MV were taken up by HT22 and reduced the oxidative stress (ROS) level. The PCR showed that BL99-MV up-regulate IL-10 level, and down-regulate TNF-α, IL-1β, and IL-6. Transcriptomic analysis revealed 4127 differentially expressed genes, with 2549 genes upregulated and 1578 genes downregulated in the BL99-MV group compared to the LPS group. Compared to the LPS group, BL99-MV decreased FoxO6, IL-33, P53, and NFκB expression, but increased FoxO1 and Bcl2 expression. The WB showed that BL99-MV modulated NFκB, FoxO6, P53, Caspase9, and Caspase3 protein expression by reducing IL-33 expression in HT22. The findings demonstrated IL-33 as a regulator for FoxO6/P53 signaling. Conclusions: Here, we hypothesized that BL99-MV alleviated LPS-induced HNF to promote HT22 survival and synaptic development by regulating FoxO6/P53 signaling by targeting IL-33.