Uremic neurotoxin in the middle molecular weight range

Area of Science:

• Nephrology
• Neurology
• Biochemistry

Background:

• Middle molecules accumulate in patients with chronic kidney disease.
• Neuropathy is a common complication in uremic patients.
• The specific uremic toxins responsible for neuropathy remain largely unidentified.

Purpose of the Study:

• To identify and quantify specific middle molecule fractions in plasma ultrafiltrates.
• To investigate the neurotoxic potential of identified middle molecule fractions.
• To correlate middle molecule concentrations with neuropathy in polyneuropathic patients.

Main Methods:

• High-performance gel chromatography (Sephadex G-15) and ion exchange chromatography (DEAE Sephadex A-25) were used for fractionating plasma ultrafiltrates.
• Quantitative determination of the b4-2 solute in biological fluids.
• In vitro sural nerve bioassay to evaluate neurotoxicity.

Main Results:

• A specific fraction, b4-2, was significantly elevated in polyneuropathic patients compared to uremic patients without neuropathy.
• Plasma concentrations of b4-2 were 1 mg/L in healthy subjects, 4.6 mg/L in uremic patients, and 13-19 mg/L in polyneuropathic patients.
• The b4-2 solute demonstrated neurotoxic effects in vitro at concentrations found in neuropathic patients' plasma.

Conclusions:

• The b4-2 solute is a potential neurotoxin contributing to neuropathy in polyneuropathic patients.
• Elevated b4-2 levels may serve as a biomarker for neuropathy.
• Further research is needed to fully identify the acid-polyol derivative responsible for neurotoxicity.