Emodin suppresses mast cell migration via modulating the JAK2/STAT3/JMJD3/CXCR3 signaling to prevent cystitis.

Aims: This study aimed to determine the preventive effects of emodin on cyclophosphamide (CYP)-induced cystitis and to explore the molecular mechanism.
Methods: In vivo, mice were modeled by CYP. Before a half hour of CYP treatment, Jumonji domain-containing protein-3 (JMJD3) inhibitors (GSK-J4) and emodin were used to treat CYP model mice. Bladder samples were stained for hematoxylin-eosin and toluidine blue. Next, JMJD3 was quantified by immunofluorescence staining, RT-PCR, and Western blot. CXCR3 was quantified by Western blot and ELISA. In vitro, before stimulated by lipopolysaccharide (LPS), human bladder smooth muscle cells (hBSMCs) were transfected with pcDNA3.1-JMJD3 plasmids, shRNA-JMJD3 plasmids or pretreated with emodin. Collected cells to detect JMJD3 and CXCR3 ligands again; collected supernatant of culture for Transwell assay. Finally, as the JAK2 inhibitor, AG490 was used to pretreat LPS-induced hBSMCs. Western blot was performed to quantify proteins.
Results: Emodin inhibited mast cell migration and suppressed the expression of JMJD3, CXCR3, and CXCR3 ligands, not only in vivo but also in vitro. The pharmacological effects of emodin were similar to GSK-J4 or JMJD3 inhibition. In addition, emodin significantly downregulated the phosphorylation of JAK2 and STAT3, and inhibited JMJD3/CXCR3 axis transduction like AG490.
Conclusion: Emodin has a preventive effect on cystitis by inhibiting mast cell migration through inhibition of the JAK2/STAT3/JMJD3/CXCR3 signaling pathway.
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