Free amino acids in fibromyalgia syndrome: relationship with clinical picture

Abstract

The objectives of our study were to evaluate free amino acid (FAA) concentrations in the serum of patients affected by fibromyalgia syndrome (FMS) and to determine the relationships between FAA levels and FMS clinical parameters. Thus, serum amino acid concentrations were quantified (HPLC analysis) in 23 females with fibromyalgia (according to the American College of Rheumatology classification criteria) and 20 healthy females. The results showed significantly higher serum concentrations of aspartate, cysteine, glutamate, glycine, isoleucine, leucine, methionine, ornithine, phenylalanine, sarcosine, serine, taurine, tyrosine and valine in FMS patients vs. healthy controls. Patients with higher Fibromyalgia Impact Questionnaire (FIQ) scores showed increased levels of alanine, glutamine, isoleucine, leucine, phenylalanine, proline and valine. In conclusion, our results indicate an imbalance in some FAAs in FMS patients. Increased Glu is particularly interesting, as it could explain the deficit in monoaminergic transmission involved in pain.

Metabolomic Differentials in Women With and Without Fibromyalgia

“…Elevated levels of taurine have been previously reported in serum and urine in women diagnosed with FM. Similarly, elevated levels of methionine sulfoxide and anthranilate have been reported . Methionine sulfoxide is a primary oxidation product of methionine (Met) via its nucleophilic oxidation and is sometimes considered a biomarker of oxidative stress, whereas anthranilate is a tryptophan metabolite that has been implicated in brain/immune communication .…”

“… References used to pinpoint the pathway for each metabolite were the Human Metabolome Database (http://www.hmdb.ca/) and the Kyoto Encyclopedia of Genes and Genomes KEGG (https://www.genome.jp/kegg/). …”

“…Similarly, we found elevated levels of taurine, a sulfur-containing amino acid whose pathway is understood to be associated with alterations in lipid metabolism in women. 29 Elevated levels of taurine have been previously reported in serum 30,31 and urine 32 in women diagnosed with FM. Similarly, elevated levels of methionine sulfoxide and anthranilate have been reported.…”

“…Similarly, elevated levels of methionine sulfoxide and anthranilate have been reported. 8,30 Methionine sulfoxide is a primary oxidation product of methionine (Met) via its nucleophilic oxidation and is sometimes considered a biomarker of oxidative stress, 33 whereas anthranilate is a tryptophan metabolite that has been implicated in brain/immune communication. 34 In addition to higher levels of the metabolites described above, we found lower levels of alpha-ketoglutaric acid and metabolites associated with cellular metabolism in individuals with FM.…”

Inflammatory activation of human cardiac fibroblasts leads to altered calcium signaling, decreased connexin 43 expression and increased glutamate secretion

“…A fine-tuned regulation of clearance and maintenance of extracellular glutamate is important for normal metabolism in neurons and impairments of this regulation can lead to excitotoxicity [19]. Increased glutamate concentrations were also reported in synovial fluid from patients with active arthropathies [20] and in serum from patients with fibromyalgia [21]. Cytoskeletal reorganization is pivotal in many cellular processes, especially during inflammation.…”