[Effect of formononetin on inflammation and immunity in autoimmune prostatitis: An exploration based on JAK/STAT signaling pathways].

Objective: To investigate the action mechanism of formononetin (FN) in regulating T helper type 1 (Th1) cell differentiation and macrophage polarization through JAK/STAT signaling pathways in a mouse model of experimental autoimmune prostatitis (EAP).

Methods: Forty non-obese diabetic (NOD) male mice were randomly divided into four groups: normal control, EAP model control, low-dose FN (LFN, 50 mg/kg) and high-dose FN (HFN, 100 mg/kg). The EAP model was established in the latter three groups by subcutaneous injection of prostate antigens (PAgs) combined with complete Freund's adjuvant (CFA). After modeling, the mice in the LFN and HFN groups were treated intragastrically with FN at 50 and 100 mg/kg/d, respectively, and those in the normal and model controls groups with carboxymethylcellulose sodium (CMC-Na). At 42 days after treatment, all the animals were killed and relevant tissues collected for observation of the pathological changes in the prostate tissue by HE staining, detection of Th1 cell differentiation and macrophage polarization in the prostate by immunofluorescence double staining (labeling CD4 and interferon-γ ［IFN-γ］, inducible nitric oxide synthase ［iNOS］ and CD206), measurement of the ratio of Th1 cells/macrophages in the spleen by flow cytometry and the levels of IFN-γ and tumor necrosis factor-α (TNF-α) in the serum by ELISA, and determination of the expressions of phosphorylated (p)-Janus kinase (JAK)1, JAK1, p-JAK2, JAK2, p-signal transducer and activator of transcription (STAT1) in the prostate tissue by Western blot.

Results: Compared with the model controls, the mice treated with low- and high-dose FN exhibited more orderly arrangement of glandular epithelial cells, significantly reduced prostatic tissue inflammation scores (P<0.05), and decreased proportion of Th1 cells and expression of M1 macrophages (P<0.05), but increased expression of M2 macrophages in the prostate and spleen tissues (P<0.05). Besides, the levels of inflammatory cytokines IFN-γ (P<0.05) and TNF-α (P<0.05) in the serum of the mice in the LFN and HFN groups were remarkably reduced, and so were the ratios of p-JAK1/JAK1, p-JAK2/JAK2 and p-STAT1/STAT1 in the prostate tissues at the molecular level (P<0.05), indicating the therapeutic effect of FN on EAP by regulating JAK/STAT signaling pathways, promoting inflammation resolution, and restoring immune balance.

Conclusion: FN alleviates EAP by inhibiting JAK/STAT signaling pathways and regulating Th1 cell differentiation and macrophage polarization.