Fibronectin in patients with chronic renal failure undergoing dialysis

Comparative analysis of therapeutic effects between medium cut-off and high flux dialyzers using metabolomics and proteomics: exploratory, prospective study in hemodialysis

In this single-center prospective study of 20 patients receiving maintenance hemodialysis (HD), we compared the therapeutic effects of medium cut-off (MCO) and high flux (HF) dialyzers using metabolomics and proteomics. A consecutive dialyzer membrane was used for 15-week study periods: 1st HF dialyzer, MCO dialyzer, 2nd HF dialyzer, for 5 weeks respectively. ¹H-nuclear magnetic resonance was used to identify the metabolites and liquid chromatography-tandem mass spectrometry (LC–MS/MS) analysis was used to identify proteins. To compare the effects of the HF and MCO dialyzers, orthogonal projection to latent structure discriminant analysis (OPLS-DA) was performed. OPLS-DA showed that metabolite characteristics could be significantly classified by 1st HF and MCO dialyzers. The Pre-HD metabolites with variable importance in projection scores ≥ 1.0 in both 1st HF versus MCO and MCO versus 2nd HF were succinate, glutamate, and histidine. The pre-HD levels of succinate and histidine were significantly lower, while those of glutamate were significantly higher in MCO period than in the HF period. OPLS-DA of the proteome also substantially separated 1st HF and MCO periods. Plasma pre-HD levels of fibronectin 1 were significantly higher, and those of complement component 4B and retinol-binding protein 4 were significantly lower in MCO than in the 1st HF period. Interestingly, as per Ingenuity Pathway Analysis, an increase in epithelial cell proliferation and a decrease in endothelial cell apoptosis occurred during the MCO period. Overall, our results suggest that the use of MCO dialyzers results in characteristic metabolomics and proteomics profiles during HD compared with HF dialyzers, which might be related to oxidative stress, insulin resistance, complement-coagulation axis, inflammation, and nutrition.

Assessment of plasma fibronectin in malnourished Nigerian children

BACKGROUND

Severe malnutrition is associated with septic infections. The concentrations of fibronectin, albumin, and transferrin in plasma were measured in three groups of children with protein-energy malnutrition, aged 1-3 years, each group comprising 20 children. The aim of which was to test whether plasma fibronectin, being an opsonic protein, was reduced in such children, and if it was a useful index for assessing the severity of malnutrition.

METHODS

The concentrations of fibronectin, albumin, and transferrin in plasma were studied by enzyme immunoassay/ immunoblotting, spectrophotometry and immunoturbidimetry respectively.

RESULTS

All values were significantly lower in the patients with malnutrition than in the age- and sex-matched well-nourished Nigerian reference children. Within the malnourished group, the fibronectin value was evenly reduced in all subgroups. Albumin and transferrin values were lowest in the patients with kwashiorkor, highest in the marasmic patients, and intermediate in the patients with marasmic kwashiorkor; the values correlated mutually in individual cases as well, but not with the fibronectin levels. Neither plasma fibronectin fragmentation nor tissue fibronectin was detected in any patient with malnutrition or in the reference subjects.

CONCLUSIONS

The reduced plasma fibronectin values in these patients may be due to reduced synthesis by the liver, as evidenced by the equally reduced albumin and transferrin concentrations and/or to the multiple infections characteristic of the patients.

Correlates of vascular access occlusion in hemodialysis

Vascular access occlusion results in significant morbidity in hemodialysis patients. Age, diabetes, and synthetic grafts (polytetrafluoroethylene [PTFE]) have been associated with vascular access occlusion in univariate analysis. However, the independent risk associated with each of these factors has not been assessed adjusting for confounding among the factors or by other variables, such as blood pressure (BP) or hematocrit. The influence of serum lipoprotein(a) [Lp(a)] and fibronectin on vascular access occlusion has not been widely studied despite their theoretical or demonstrated importance in vascular bypass occlusion. In a cohort study of 124 hemodialysis patients monitored for up to 14 months, we reported that Lp(a) values in the upper tertile (> or = 57 mg/dL) were associated with vascular access occlusion risk in white and Hispanic patients, but not in black patients. We now report an expanded analysis of this data set to determine the independent correlates of vascular access occlusion. Variables tested included age, race, gender, diabetes, access type (PTFE v endogenous), treatment time, systolic BP, hematocrit, heparin and erythropoietin dosage, and serum levels of Lp(a) and fibronectin. In univariate analysis, access occlusion was associated with age, diabetes, PTFE, Lp(a) > or = 57 mg/dL, serum fibronectin, and reduced BP. The independent correlates of first access occlusion were determined with the Cox proportional hazards model. Since the overall model included a significant race x Lp(a) interaction term, we stratified by race. In black patients, risk correlated directly with PTFE (P < 0.01) and inversely with systolic BP (P < 0.001), whereas for white and Hispanic patients, age (P = 0.04) and Lp(a) > or = 57 mg/dL (P = 0.05) were associated with increased risk. In summary, vascular access occlusion was found to be associated with a number of factors. Important independent correlates were PTFE and lower BP in black patients, and age and serum Lp(a) > or = 57 mg/dL in white and Hispanic patients. Diabetes mellitus and increased serum fibronectin may contribute additional risk.