Presented by: Wei Wang MD
Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China

Introduction

Unresolved inflammation can lead to tissue fibrosis and impaired organ function. Macrophage–myofibroblast transition (MMT) is one newly identified process to generate collagen-producing myofibroblasts in fibrotic disease. However, the mechanisms underlying MMT remain to be determined. Here, we investigated the potential role of methyl-CpG binding domain 2 (MBD2)-mediated MMT in bladder fibrosis with bladder outlet obstruction (BOO) mice.

Materials

Male C57BL/6 mice were subjected to a surgical operation for BOO as previously reported. Bladder tissues were harvested for assays of flow cytometry, western blot, histological examinations, immunohistochemistry staining and immunofluorescence. In vitro, bone marrow-derived macrophages (BMDM) were isolated from mice by flushing the femur and tibia with DMEM/F12 medium, dispersing the cells and isolating F4/80+ cells via FACS (> 99% purity). Generation of MMT cells from BMDMs was stimulated by TGF-β1 as described previously.

Results

,

The expression of MBD2 was abnormally increased in the BOO group, accompanied by MMT cell accumulation. Interestingly, we found that MBD2 was highly expressed by macrophages undergoing MMT in sites of bladder fibrosis. In vitro study demonstrated that TGF-β1 treatment significantly upregulated the expression of collagen-1, fibronectin, α-smooth muscle actin and MBD-2 in macrophages. Furthermore, systemic knockout of MBD2 alleviated bladder fibrosis and pathological damage. MBD2 deficiency significantly attenuated MMT cell infiltration in the bladder following BOO induction.

Conclusion

Our findings establish a role for MBD2 in MMT and bladder fibrosis and suggest that MBD2 may be a therapeutic target for BOO with progressive bladder fibrosis.

Funding

This study was supported by the National Natural Science Foundation of China (Grant No. 81800667, 82270811), and the Project of Science and Technology Department of Sichuan Province (Grant No. 22NSFSC1447).

Co-Authors

Lede Lin, MD
Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China

Huiling Chen, MD
Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China

Liang Zhou, MD
Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China