Metabolomic analyses of amyotrophic lateral sclerosis, muscle cramps, and TJ-68 treatment.

INTRODUCTION

Most patients with amyotrophic lateral sclerosis (ALS), a fatal motor neuron disease, experience painful muscle cramps. Our recent pilot trial of the Japanese Kampo medicine TJ-68 suggested its efficacy in improving muscle cramps in patients with ALS.

OBJECTIVES

This study analyzed plasma metabolomic changes to identify the underlying mechanisms of muscle cramps in ALS and the effects of TJ-68.

METHODS

Plasma was obtained from 11 participants with ALS in the repeated crossover trial at five time points (baseline, two placebo phases, and two TJ-68 phases). Metabolites were analyzed using mass spectrometry. Linear mixed-effects models were applied to identify metabolite changes associated with muscle cramps, determine the effects of TJ-68 on metabolites, and predict which participants would respond to TJ-68.

RESULTS

Higher glutamine/glutamate, arginine, and leucine levels were associated with more severe muscle cramps. TJ-68 treatment increased tryptophan and aconitate levels but reduced serotonin and acetylcarnitine levels. Long-chain acylcarnitine levels were correlated with muscle cramp severity, and their levels tended to decrease with treatment. Uric acid, β-aminoisobutyric acid, α-aminoadipic acid, and acetylcholine emerged as predictors of the efficacy of TJ-68.

CONCLUSION

This study identified the metabolite profile of muscle cramps in ALS and the changes in metabolite levels after TJ-68 treatment. Several baseline metabolites were associated with the prediction of the response to muscle cramps following TJ-68 treatment. Uric acid might be particularly useful because of its easy measurement in standard assays. Our study affirms the value of metabolomic technology for future pharmacotherapy and studies in ALS.