Tumor Necrosis Factor- α (TNF-α) and Rho-Associated Kinase 2 (ROCK2) Inhibitors Improve Erectile Function in a Bilateral Cavernous Nerve Injury Rat Model

Abstract

ABSTRACT Introduction Prior studies suggest Rho-kinase (ROCK) upregulation and pro-inflammatory cytokines such as Tumor Necrosis Factor-α as causative factors of axonal degeneration, neuropathy, and penile fibrosis following peripheral cavernous nerve (CN) injury. We hypothesize, the combination therapy using inhibitors/antagonists of ROCK and TNF-α may prevent end-organ damage and neuroinflammation in the penis. The current study was designed to investigate selective inhibition of ROCK2 (SAR407899) and TNF-α (Infliximab) in a pre-clinical model of post-radical prostatectomy ED to prevent penile neuroinflammation, fibrosis, and preserve penile hemodynamics. Objective This study investigates the effect of FDA approved TNF- α inhibitor (Infliximab) in combination with ROCK2 selective inhibitor (SAR407899) on erectile function restoration in the bilateral crush nerve injury (BCNI) rat model. Methods Sprague Dawley rats were randomized to undergo either sham (6) or BCNI (28). The BCNI rats were further randomly stratified to receive saline (6), Infliximab (5 mg/kg once weekly) (6), low dose of SAR407899 (1.5 mg/kg QD) (5), high dose of SAR407899 (3 mg/kg QD) (5), or combination treatment SAR407899 (1.5 mg/kg QD) + Infliximab (5 mg/kg once weekly) (6). At 14 days after injury rats underwent cavernous nerve stimulation to determine erectile function. Penes were collected and immune infiltrate analyses were performed using multicolor flow-cytometry. Results Erectile response studies demonstrated that rodents treated with combination of Infliximab and SAR407899 had significantly improved (p<0.05) erectile function (ICP/MAP) at all voltages compared to BCNI alone (2V: 0.243 vs 0.051, 4V: 0.321 vs 0.0782, 6V: 0.456 vs 0.091, p <0.05). Peak ICP and total ICP were also significantly (p<0.05) improved compared to BCNI rats. Combination therapy, however, did not show a significant change compared to each treatment alone. Likewise, there was no significant difference between low and high dose SAR407899. Flow cytometry showed that Infliximab and SAR407899 significantly (p<0.05) decreased % of CD11b+ CD45+ monocytes in the penis. While combination therapy had no effect. The percent of CD11b+ MHCII+ CD45+ macrophages were increased (p<0.05) in the penes of rats treated with Infliximab and SAR407899 while combination therapy decreased penile macrophage population. We found no change in TNF- α+ monocytes and macrophages compared in penes from all groups investigated. Conclusions Our study suggests that treatment with commercially available TNF-α and ROCK2 inhibitors result in mitigation of erectile dysfunction in a BCNI rat model when administered at the time of nerve injury. The mechanism of the beneficial effects may involve reduction in macrophage population in the penis. Disclosure No