Biomarkers in Saliva of Fibromyalgia Patients May Be Diagnostic Tool

Biomarkers in Saliva of Fibromyalgia Patients May Be Diagnostic Tool

Researchers have found that increased levels of three proteins in the saliva, namely alpha-enolase, phosphoglycerate mutase 1 and serotransferrin, may help differentiate fibromyalgia (FM) patients from those with other inflammatory diseases.

The study with that finding, “Putative salivary biomarkers useful to differentiate patients with fibromyalgia,” was published in the Journal of Proteomics.

Researchers investigated whether saliva from FM patients has potential diagnostic and/or prognostic biomarkers that could improve how patients are managed and treated.

They performed a proteomics analysis – a strategy to identify all the proteins  – in saliva samples from four groups: an FM group, a group of healthy subjects, one with patients who have rheumatoid arthritis (RA) (model of inflammatory chronic pain), and one group with people suffering migraines (model of non-inflammatory chronic pain). Each group was composed of 30 participants.

The RA and migraine groups were added as positive controls, i.e., to ensure that the proteomics analysis was performed correctly.

The outcome of the analysis identified 17 protein spots showing a difference of expression (quantity) in FM relative to RA; they also found 19 and 23 protein spots showing differences relative to migraines and healthy subjects, respectively.

“In particular, we found 5 spots differentially expressed solely in FM,” researchers wrote.

Further analysis identified four of these spots as isoforms – similar proteins, but with a different structure – of a protein called serotransferrin, and one spot belonged to the alpha-enolase protein.

To validate these findings and make sure the expression of the proteins was indeed changing in the saliva of FM patients, researchers quantified the proteins using a different assay, the so-called enzyme-linked immunosorbent assay or ELISA.

They analyzed the levels of the two identified proteins, serotransferrin and alpha-enolase, and included in the assay other proteins whose levels previously were reported as increased in FM patients’ saliva – the phosphoglycerate mutase 1 and transaldolase proteins.

The ELISA assay confirmed that the saliva of FM patients carries statistically significant differences in the levels of serotransferrin, alpha-enolase and phosphoglycerate mutase 1, compared to controls ((healthy subjects plus the migraine group).

The assay failed to confirm the increase in the expression of transaldolase in FM.

While the results indicated that the proteinalpha-enolase was the best biomarker, its discriminative power increased when combined with the two other proteins, phosphoglycerate mutase 1 and serotransferrin.

Overall, these findings suggest a panel of three salivary proteins – alpha-enolase, phosphoglycerate mutase 1 and serotransferrin  – as potential biomarkers for FM.

“We believe that this panel could be a useful tool in supporting clinicians’ diagnosis and defining FM clusters and targeted treatment,” researchers wrote.