Background and aims
Fibromyalgia (FM) is a multifaceted chronic pain condition with known clinical symptoms; generalized pain, increased pain sensitivity, and often anxiety and depression. The complete pathophysiology behind FM is not fully understood and objective validated markers for FM are lacking. The aim of this study was to investigate the correlation between anxiety, depression and severity of fibromyalgia, with plasma proteins in FM patients. 

Methods
The plasma proteome profile of FM (n=30) and controls (CON, n=31) were analyzed with 2- dimensional gel electrophoresis in combination with mass spectrometry. Background data and clinical variables were retrieved via questionnaires. Multivariate statistical (Orthogonal Partial Least Squares, OPLS) and standard correlation analysis were used to evaluate correlation between plasma proteins, scores from hospital and anxiety depression scale, and Fibromyalgia impact questionnaire (FIQ). 

Results
Significant differences were found in the clinical variables FIQ, anxiety and depression between FM and CON. In the OPLS model of anxiety, 9 proteins expressed as 19 protein isoforms, significantly correlated with anxiety in FM. In the OPLS model of depression, 8 proteins expressed as 14 protein isoforms, significantly correlated to depression in FM. Three of the protein isoforms from both models correlated to FIQ. The majority of proteins in the anxiety and depression models were involved in inflammatory/immunity responses. 

Conclusion 
In this study anxiety, depression and severity of FM correlated to specific plasma proteins involved in immune response. This study shows that proteomic in combination with clinical data is a useful tool to study the biopsychosocial perspective of FM.

ALTERED BLOOD PROTEINS CORRELATE SIGNIFICANTLY WITH DEPRESSION, ANXIETY AND SEVERITY OF FIBROMYALGIA