NERP-1 modifications in amyotrophic lateral sclerosis

VGF peptides, such as NERPs (neuroendocrine regulatory peptides 1 and 2), are derived from amino acids 282-306 and 313-350, respectively, of the human proVGF, which is produced in spinal cord motor neurons. Although certain VGF-derived peptides are changed in ALS, less is known about NERPs. Possible modulations of NERPs and additional VGF peptides (NAPP and TPGH) were investigated using specific antibodies through competitive ELISA in the plasma of ALS patients (at both the initial and advanced phases; n = 46 each vs. 46 controls). As additional controls, naïve PD patients were also enrolled (n = 19 vs. 18 controls) while the potential VGF peptide role in oxidative stress was investigated using a motoneuron-like cell line (NSC34) stressed with sodium arsenate (SA). Western blot (WB) and sephadex chromatography (SC) were used to identify the molecular weight (MW) forms recognized by the VGF antibodies. Exclusively NERP-1 immunoreactivity was changed (elevated) in all plasma samples of ALS patients (compared to controls). Therefore, the NERP-1 antibody was the sole antibody used in ELISA with PD samples and NSC-34 cells. No alterations were seen in PD samples (vs. controls) while NERP-1 immunoreactivity decreased within SA-treated cells but increased in their culture medium. The viability test performed by adding NERP-1 to the stressed cells showed no protective effect. Using WB and SC, we revealed NERP-1 antibody reactivity against various MW forms, including those compatible with the NERP-1 peptide and/or proVGF. NERP-1 is suggested as a possible ALS blood biomarker.