Cys327Cys polymorphism of the PAPP-A gene (pregnancy associated plasma protein A) is related to mortality of long term hemodialysis patients

Sclerostin levels predict cardiovascular mortality in long-term hemodialysis patients: A prospective observational cohort study

Sclerostin is a protein which is involved in bone metabolism and probably also in vessel wall function. This prospective observational cohort study evaluated the prognostic significance of sclerostin in hemodialysis (HD) patients. In total, 106 HD patients and 25 healthy controls participated in the study. HD patients were prospectively followed up for five years. Sclerostin was measured in serum using standard ELISA kits by Biomedica. Sclerostin concentrations in serum were higher in HD patients compared to the controls (89.2±40.3 pmol/l vs. 32.8±13.0 pmol/l, p<0.001). Sclerostin levels were significant for cardiovascular mortality but not for overall mortality and mortality due to infection. A higher cardiovascular risk was connected to sclerostin concentrations above the median (>84 pmol/l), HR (95 % CI): 2.577 (1.0002-10.207), p=0.04. When sclerostin was evaluated together with residual diuresis in Kaplan-Meier analysis the worst prognosis due to cardiovascular events was observed in the group with high sclerostin and zero residual diuresis compared to all other patients (p=0.007). In summary, serum sclerostin levels in HD patients were increased when compared to healthy subjects. High sclerostin levels were demonstrated as a risk factor for cardiovascular mortality. Further studies are required to clarify the pathophysiological mechanisms of sclerostin action in patients with renal failure before therapeutic measures can be established.

Pregnancy-associated plasma protein A and mortality in haemodialysis

BACKGROUND

Elevated pregnancy-associated plasma protein A (PAPP-A) levels are associated with increased risk of death in ischaemic heart disease as well as in haemodialysis patients. Previous research indicates that the prognostic value of PAPP-A may be stronger in patients with concomitant diabetes mellitus or signs of inflammation. We studied the association between PAPP-A and outcomes in prevalent haemodialysis patients and hypothesized that diabetes mellitus and inflammation status act as effect modifiers.

MATERIALS AND METHODS

Circulating PAPP-A levels were quantified using ELISA. Cox proportional hazards and quantile regression models were used for associations between PAPP-A and mortality. PAPP-A levels were log-transformed for Normality.

RESULTS

During 60-month follow-up, 37 (40%) of the 92 participants died. Higher PAPP-A was associated with increased risk of mortality in unadjusted analysis (HR per SD = 1.4, 95% CI = 1-1.9, P = .03) and when adjusted for confounders and cardiovascular risk factors (HR = 1.8, 95% CI = 1.18-2.73, P = .006). An interaction between PAPP-A levels and diabetes mellitus on mortality was found (HR for the multiplicative interaction term = 2.74 95% CI = 1.02-7.37, P = .05). In a quantile regression adjusted for age and sex, one SD increase in PAPP-A was associated with 22 months shorter estimated time until 25% of the patients died (95% CI -35 to -9.1 months).

CONCLUSIONS

Increased PAPP-A levels are associated with higher all-cause mortality in prevalent haemodialysis patients with concomitant diabetes mellitus.

Pregnancy-Associated Plasma Protein A2 in Hemodialysis Patients: Significance for Prognosis

BACKGROUND

Pregnancy-associated plasma protein A (PAPP-A) is associated with adverse outcome of long-term hemodialysis patients (HD). The aim of the study was to test whether its homolog pregnancy-associated plasma protein A2 (PAPP-A2) can be detected in serum of HD patients and to define its significance.

METHODS

The studied group consisted of 102 long-term HD patients and 25 healthy controls. HD patients were prospectively followed up for five years (2009-2014). PAPP-A2 was measured by surface plasmon resonance biosensor, PAPP-A by time resolved amplified cryptate emission.

RESULTS

PAPP-A2, similarly as PAPP-A, was significantly increased in HD patients (median (interquartile range)) PAPP-A2: 6.2 (2.6-10.8) ng/mL, vs. 3.0 (0.7-5.9) ng/mL, p=0.006; PAPP-A: 18.9 (14.3-23.4) mIU/L, vs. 9.5 (8.4-10.5) mIU/L, p<0.001). In HD patients, PAPP-A2 correlated weakly but significantly with PAPP-A (τ=0.193, p=0.004). Unlike PAPP-A, PAPP-A2 was not significant for prognosis of HD patients when tested alone. There was a significant interaction between PAPP-A and PAPP-A2 on the mortality due to infection of HD patients (p=0.008). If PAPP-A was below median, mortality due to infection was significantly higher for patients with PAPP-A2 values above median than for patients with low PAPP-A2 levels (p=0.011).

CONCLUSION

PAPP-A2 is increased in HD patients and interacts with PAPP-A on patients´ prognosis.