Zhang, Y.; Gong, S.; He, W.; Yuan, J.; Dong, D.; Zhang, J.; Wang, H.; Chen, B.

Background: Melatonin (MEL) is an indole amine molecule primarily produced in the pineal gland. Melatonin has been shown in numerous studies to have anti-fibrosis characteristics in the kidney, liver, and other organs. However, it is still unclear how melatonin works in bladder fibrosis. We explored how melatonin affected animals with bladder fibrosis and its underlying mechanisms. Materials and Methods: MEL was used to treat human bladder smooth muscle cells (HBdSMCs) after they were stimulated with TGF-{beta}1 in vitro. Proteomic analysis and then bioinformatic analysis based on the alterations in these proteins were then performed on HBdSMCs from the different processing methods. To construct an in vivo bladder fibrosis model, we injected protamine sulfate (PS) and lipopolysaccharide (LPS) twice a week into the rat bladder for six weeks. After two weeks of PS/LPS treatment, the treatment group was treated with MEL (20mg/kg/d) for 4 weeks. Finally, we detected the expression of fibrosis markers from different perspectives. The TGF-{beta}1/Smad pathway, and EMT in cell and bladder tissues were also identified. Further proteomic analysis was also performed. Results: In the in vitro experiment, we found that TGF-{beta}1 treatment enhanced the fibrosis markers Collagen III and -SMA of HBdSMCs. E-cadherin expression decreased while TGF-{beta}1/Smad pathway was activated. Vimentin and N-cadherin expressions were also elevated at the same time. Similar findings were observed in the LPS group. After MEL treatment, the expression of collagen III and -SMA decreased, and the expression of E-cadherin increased, while the expression of Vimentin and N-cadherin also decreased. CCN1 and SQLE may be the important proteins in the development of bladder fibrosis, according to quantitative proteomics analysis. MEL can decrease their expressions which leadis to relief of bladder fibrosis. Bioinformatics analysis shows that the extracellular space structure related to metabolic pathways, actin filament binding, and stress fibers can serve as a pivotal focus in the management of fibrosis. Conclusion: Melatonin attenuates bladder fibrosis by blocking the TGF-{beta}1/Smad pathway and EMT. CCN1 appears to be a possible therapeutic target for bladder fibrosis.