The relationship between bone morphogenic protein-7 and peritoneal transport characteristics

Background. After prolonged peritoneal dialysis (PD) and exposure to a non-physiological dialysis solution, peritoneal mesothelial cells undergo the epithelial-to-mesenchymal transition. In other biological systems, bone morphogenic protein-7 (BMP-7) is a key factor that controls this process. However, the role of BMP-7 in peritoneal physiology has not been studied. Methods. We studied the peritoneal transport characteristics of 50 consecutive new PD patients at 4 and 52 weeks after PD. Peritoneal permeability will be determined by the standard peritoneal equilibration test (PET). BMP-7 in PD effluent (PDE) at mRNA and protein level at 4 weeks was quantified. Results. At 4 weeks, the mRNA expression of BMP-7 in PDE significantly correlated with peritoneal transport characteristics, including the dialysate-to-plasma creatinine ratio at 4 h (D/P4) (r = 0.422, P = 0.015) and mass transfer area coefficient (MTAC) of creatinine (r = 0.457, P = 0.008). The PDE BMP-7 level by ELISA also had marginal correlation with D/P4 (r = 0.287, P = 0.072) and MTAC creatinine (r = 0.287, P = 0.073), although the result did not reach statistical significance. For the subgroup of patients who remained free of peritonitis, the PDE BMP-7 level by ELISA had significant correlation with the change in D/P4 (r = 0.441, P = 0.017) and MTAC creatinine in 52 weeks (r = 0.415, P = 0.025). The PDE BMP-7 level remained independently associated with the change in peritoneal transport adjusting for age, sex, serum C-reactive protein and PDE transforming growth factor-beta level. In patients who had peritonitis during the study period, the PDE BMP-7 level did not affect the change in peritoneal transport. Conclusion. We find that the peritoneal BMP-7 level correlates with peritoneal transport characteristics, and a high PDE BMP-7 level is associated with a gradual increase in peritoneal transport parameters with time. It remains un-clear, however, whether this effect is beneficial, and the therapeutic role of exogenous BMP-7 on peritoneal transport requires a further study.