Effect of GFR on plasma N-terminal connective tissue growth factor (CTGF) concentrations.

BACKGROUND

Connective tissue growth factor (CTGF) has a key role in the pathogenesis of renal and cardiac fibrosis. Its amino-terminal fragment (N-CTGF), the predominant form of CTGF detected in plasma, has a molecular weight in the middle molecular range (18 kDa). However, it is unknown whether N-CTGF is a uremic retention solute that accumulates in chronic kidney disease (CKD) due to decreased renal clearance and whether it can be removed by hemodiafiltration.

STUDY DESIGN

4 observational studies in patients and 2 pharmacokinetic studies in rodents.

SETTING & PARTICIPANTS: 4 single-center studies. First study (cross-sectional): 88 patients with CKD not receiving kidney replacement therapy. Second study (cross-sectional): 23 patients with end-stage kidney disease undergoing low-flux hemodialysis. Third study: 9 kidney transplant recipients before and 6 months after transplant. Fourth study: 11 low-flux hemodialysis patients and 12 hemodiafiltration patients before and after one dialysis session.

PREDICTOR

First, second, and third study: (residual) glomerular filtration rate (GFR). Fourth study: dialysis modality.

OUTCOMES & MEASUREMENTS: Plasma (N-)CTGF concentrations, measured by enzyme-linked immunosorbent assay.

RESULTS

In patients with CKD, we observed an independent association between plasma CTGF level and estimated GFR (β = -0.72; P < 0.001). In patients with end-stage kidney disease, plasma CTGF level correlated independently with residual kidney function (β = -0.55; P = 0.046). Successful kidney transplant resulted in a decrease in plasma CTGF level (P = 0.008) proportional to the increase in estimated GFR. Plasma CTGF was not removed by low-flux hemodialysis, whereas it was decreased by 68% by a single hemodiafiltration session (P < 0.001). Pharmacokinetic studies in nonuremic rodents confirmed that renal clearance is the major elimination route of N-CTGF.

LIMITATIONS

Observational studies with limited number of patients. Fourth study: nonrandomized, evaluation of the effect of one session; randomized longitudinal study is warranted.

CONCLUSION

Plasma (N-)CTGF is eliminated predominantly by the kidney, accumulates in CKD, and is decreased substantially by a single hemodiafiltration session.