[Role of mast cells in experimental autoimmune prostatitis in rats]

To investigate the role of mast cells in chronic prostatitis / chronic pelvic pain syndrome (CP/CPPS).

Forty-five male SD rats were equally randomized into a control, an experimental autoimmune prostatitis (EAP) model, and an intervention group. The EAP model was made in the latter two groups by subcutaneous injection of mixed suspension of complete Freund's adjuvant and prostate tissue, while the controls were treated subcutaneously with 0.9% sodium chloride. Tactile allodynia was quantified in the pelvic region of the control and EAP animals using Von-Frey filaments at 5, 10, 20, 30 and 40 days. After successful establishment of the EAP model, the rats of the intervention group were injected intraperitonieally with cromolyn sodium for 10 days, and meanwhile tactile allodynia was detected in the rats of the intervention and EAP model groups every other day. Then the prostates of the rats were harvested for HE and toluidine blue staining and measurement of the expression of mast cell tryptase by immunohistochemistry and Western blot.

Von-Frey assessment showed a more severe pelvic pain in the EAP model than in the control rats, but milder in the intervention group than in the EAP models. HE staining revealed infiltration of lymphocytes and neutrophils in the prostate and congestion surrounding the gland in the EAP model rats, but none in the controls. However, both the infiltration and congestion were significantly alleviated in the intervention group. Toluidine blue staining shown that. Compared with the control group, the total count of mast cells and the number degranulated mast cells were markedly increased in the EAP models (P <0.01) but decreased in the intervention group (P <0.05). Both immunohistochemistry and Western blot manifested that the expression of tryptase in the mast cells was remarkably upregulated in the EAP (both P <0.01) but down-regulated in the intervention group (P <0.05 and P <0.01).

Both the total count of mast cells and the number of degranulated mast cells are significantly increased in the prostate of EAP rats. Mast cells are one of the most important mediators of type Ⅲ prostatitis-induced chronic pelvic pain, which can be used as a target for the intervention and treatment of type Ⅲ prostatitis.