Proliferative mechanism of benign prostatic hyperplasia by NLRP3 inflammasome through the complement pathway

The expressions of complement component C5a and NLRP3 inflammasome and the antiproliferative effect of resveratrol in benign prostatic hyperplasia (BPH) model rat were analyzed to clarify the BPH proliferative mechanism.

This study used the pathological stromal-dominant BPH model rat by urogenital sinus implantation (UGS). Expression of C5a, NLRP3, Caspase-1, IL-1β, and IL-18 using rat BPH tissues at 2, 3, and 8 weeks (n = 6, respectively) after UGS implantation were analyzed by qRT-PCR, western blotting analysis, and immunohistochemical (IHC) analysis. Serum IL-1β levels in BPH model and sham rats were measured by enzyme-linked immunosorbent assay. Furthermore, resveratrol, as the NLRP3 pathway inhibitor, was administered to BPH model rat to assess the antiproliferative effect on the BPH proliferative process. The proliferative effect on prostate was evaluated by Ki-67 protein expression.

The expression levels of C5a, NLRP3, Caspase-1, IL-1β, and IL-18 in qRT-PCR, western blotting, and IHC were significantly upregulated in BPH tissues compared to control prostate tissues and showed increases with time (all p < 0.05). Serum IL-1β levels in BPH model rats had significantly increased compared to sham rats. On IHC, deposition of C5a, NLRP3, Caspase-1, IL-1β, and IL-18 was abundant in stromal areas of BPH. The administration of resveratrol significantly decreased prostate weight and expressions of NLRP3, IL-1β, IL-18, and Ki-67 (all p < 0.05).

NLRP3 inflammasome activation by complement C5a produces IL-1β and IL-18 through Caspase-1 during the BPH proliferative process. NLRP3 inflammasome have the possibilities to be a therapeutic target for BPH proliferation by inhibiting the NLRP3 inflammasome pathway.