Experimental study on the regulation of PC12 cell growth by activated BV2 cells via IL-33

Background　Microglia-neuron interactions are crucial for neural repair after spinal cord injury. Interleukin-33 (IL-33) is a multifunctional cytokine from the interleukin-1 family, which plays a key role in regulating microglia-neuron interactions following spinal cord injury.Object　Investigate the regulatory effect of activated BV2 cells on the growth of PC12 cells.Methods Using the cell counting kit-8 (CCK8) to detect the number of activated BV2 cells and BV2 cell viability after intervention with different concentrations of lipopolysaccharide (LPS), to screen for the optimal concentration affecting their activation. Immunofluorescence staining was used to observe changes in BV2 cell process length and branching. BV2 cells cultured in regular medium and BV2 cells cultured in LPS-containing medium were co-cultured with PC12 cells, respectively, and immunofluorescence staining was used to detect changes in PC12 cell process length and branching. Real-time quantitative PCR (RT-qPCR) was used to detect the relative expression levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), and interleukin-10 (IL-10) genes. Activated BV2 cells were treated with 10 ng/mL IL-33 and co-cultured with PC12 cells, and immunofluorescence staining was used to detect changes in PC12 cell process length and branching..Results　CCK8 results showed that when the LPS concentration was less than 1 μg/mL, the number of cells exhibiting obvious activated morphology was low, while when the LPS concentration was greater than 1 μg/mL, cell viability decreased. Therefore, 1μg/mL is the optimal concentration affecting BV2 cell activation. Observations under an optical microscope and results from immunofluorescence staining experiments showed that, compared to resting BV2 cells, activated BV2 cells had shorter processes and more proximal branching of the cell body, exhibiting an amoeboid morphology. RT-qPCR results showed that the expression levels of pro-inflammatory factors IL-6 and TNF-α were upregulated (P＜0.01), while the expression of anti-inflammatory factors IL-4 and IL-10 showed no significant difference (P＞0.05). Optical microscopy and immunofluorescence staining results indicated that after co-culture with activated BV2 cells, PC12 cells exhibited shorter processes and fewer branches; IL-33 intervention alleviated this phenomenon. Conclusion　IL-33 can regulate activated BV2 cells and reduce their inhibitory effect on PC12 cell growth.