Detection of Nε-(carboxymethyl) lysine (CML) and non-CML advanced glycation end-products in the anterior horn of amyotrophic lateral sclerosis spinal cord

Introduction: The involvement of glycation in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis (ALS) was recently indicated. We previously reported the existence of an Amadori product, 1-hexitol-lysine (1-HL), which is formed in the early glycation reaction, in axonal spheroids of the anterior horn of the ALS spinal cord. Objective: The purpose of the present study was to confirm the occurrence of the later-stage glycation reaction that follows the early glycation reaction and leads to the formation of advanced glycation end products (AGEs). Method: We examined whether N-epsilon-(carboxymethyl) lysine (CML) and non-CML AGE are present in ALS spinal cords. Results: Immunohistochemical staining with anti-CML antibody revealed intense positivity in the cell bodies of the remaining atrophic motor neurons and in microglia. Microglia were also positive on staining with anti-non-CML antibody. Axonal spheroids were also positive on anti-non-CML-antibody staining. Vascular endothelial cells were slightly stained by both antibodies. Conclusions: The presence of non-CML AGE in the anterior horn of the ALS spinal cord indicates that the later stage of the glycation reaction is involved in the pathology of ALS. The presence of CML in the anterior horn was also confirmed, and this may reflect augmented oxidative stress.