Circulating eNAMPT in Glaucoma: A Semi-Quantitative Plasma Analysis Before and After Nicotinamide Supplementation.

A semi-quantitative Western blotting assay was successfully developed to detect eNAMPT in plasma from glaucoma patients and healthy controls.

• The assay detects eNAMPT at 52 kilodalton (kDa) and transferrin at 77 kDa as a housekeeping protein.
• Only 0.2 µL of EDTA-plasma was required per assay.
• Intra-assay variability was 14.9% and inter-assay variability was 37.9%.
• The assay was described as specific and semiquantitative.

Circulating eNAMPT levels showed no statistically significant difference between patients with glaucoma and healthy controls.

• The study included 30 controls and 90 patients with glaucoma.
• Samples were derived from a prospective clinical trial at the Eye Clinic, Umeå University Hospital, Sweden.
• No significant difference in plasma eNAMPT was detected between the two groups.

Two weeks of nicotinamide supplementation did not produce detectable changes in circulating eNAMPT levels.

• The supplementation period was 2 weeks.
• eNAMPT levels were assessed before and after nicotinamide supplementation.
• No changes in plasma eNAMPT were observed following supplementation in patients with glaucoma.

The study provides a detection platform for eNAMPT in liquid biopsies as a basis for future biomarker development in glaucoma.

• The authors note that eNAMPT is 'readily and specifically detected by Western blotting in plasma from healthy controls and patients with glaucoma.'
• Reduced circulating eNAMPT was hypothesized to potentially indicate impaired NAD biosynthetic capacity and susceptibility to glaucomatous neurodegeneration.
• The authors state that 'further studies specifically designed to study eNAMPT are needed to clarify its role in retinal ganglion cell degeneration and the therapeutic response to nicotinamide.'

Nicotinamide supplementation has demonstrated neuroprotective potential in glaucoma through the NAD salvage pathway dependent on NAMPT.

• Nicotinamide raises retinal and optic nerve nicotinamide adenine dinucleotide (NAD) via the salvage pathway.
• NAMPT is described as essential for retinal function.
• The extracellular form of NAMPT (eNAMPT) has been detected in blood and was the focus of this study.