Significant correlation between plasma proteome profile and pain intensity, sensitivity, and psychological distress in women with fibromyalgia

Abstract

Fibromyalgia (FM) is a complex pain condition where the pathophysiological and molecular mechanisms are not fully elucidated. The primary aim of this study was to investigate the plasma proteome profile in women with FM compared to controls. The secondary aim was to investigate if plasma protein patterns correlate with the clinical variables pain intensity, sensitivity, and psychological distress. Clinical variables/background data were retrieved through questionnaires. Pressure pain thresholds (PPT) were assessed using an algometer. The plasma proteome profile of FM (n = 30) and controls (n = 32) was analyzed using two-dimensional gel electrophoresis and mass spectrometry. Quantified proteins were analyzed regarding group differences, and correlations to clinical parameters in FM, using multivariate statistics. Clear significant differences between FM and controls were found in proteins involved in inflammatory, metabolic, and immunity processes. Pain intensity, PPT, and psychological distress in FM had associations with specific plasma proteins involved in blood coagulation, metabolic, inflammation and immunity processes. This study further confirms that systemic differences in protein expression exist in women with FM compared to controls and that altered levels of specific plasma proteins are associated with different clinical parameters.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Differences in plasma proteins between FM and CON using OPLS-DA modeling. (a) Score plot showing the separation between the FM and CON group. (b) Loading plot displaying proteoforms with VIP > 1. Numbers in the loading plot refers to equal spot numbers in (c), Table 2 and in supplementary Figure S1 and Table S1. (c) Heatmap showing individual (from each participant) optical density (OD) of quantified proteins for each proteoform with a VIP > 1 between FM and CON. The darker the color intensity, the higher OD of the proteoform (see color key). The loading and score plots were created in SIMCA P + (version 15), and the heatmap was created in R using the gplots package. +, upregulated in FM compared to CON; —, downregulated in FM compared to CON.

Figure 2

Pathways analysis group differences FM and CON. Investigation of functional protein network from significant plasma proteins that could discriminate between FM and CON. The STRING version 11 was used to create the network analysis (https://string-db.org/). A2M Alpha-2-macroglobulin, GSN Gelsolin, HP Haptoglobin, FGA Fibrinogen alpha chain, FGB Fibrinogen beta chain, APOH Beta-2-glycoprotein 1, PLG Plasminogen, SERPINF2 Alpha-2-antiplasmin, KNG1 Kininogen-1, CFI Complement factor I, A1BG Alpha-1B-glycoprotein, C3 Complement C3, TF Serotransferrin, APOC3 Apolipoprotein C-III, C1R Complement C1r subcomponent, C4B Complement C4-B.

Figure 3

Pain intensity and associated plasma proteins in FM. The Score plot (left) shows a within-group separation in the FM group based on pain intensity (visual analogue scale, VAS). The plot shows that FM patients are grouped as having mild (5–44), moderate (45–74), and severe (75–100) pain intensity. The larger the triangle, the higher the pain intensity. The loading plot (right) shows 13 significant proteoforms (VIP > 1) associated with pain intensity. Nine proteoforms were associated with higher pain intensity in FM (VAS > 45). Numbers in the loading plot equals the spot numbers in Table 3 and supplementary Figure S1 and Table S1. The loading and score plots were created in SIMCA P + (version 15).

Figure 4

Pathway analysis of pain intensity in FM. Protein–protein network analysis of plasma proteins correlated with pain intensity in FM. The STRING version 11 was used to create the network analysis (https://string-db.org/). A2M Alpha-2-macroglobulin, HP Haptoglobin, IGJ Immunoglobulin J chain, FGB Fibrinogen beta chain, FGA Fibrinogen alpha chain, TF Serotransferrin, APOH Beta-2-glycoprotein 1, CP Ceruloplasmin, CLU Clusterin, SERPINC1 Antithrombin-III, HPX Hemopexin.

Figure 5

Pressure pain thresholds (PPT) and associated plasma proteins in FM. Score plot (left) shows a within-group separation in the FM group based on measured PPT. The larger the triangles, the higher the score. The loading plot (right) shows 14 proteoforms correlated with PPT (VIP > 1); five out of 11 proteoforms were associated with a very low pain sensitivity score (

Figure 6

Pathway analysis of pressure pain thresholds (PPT) in FM. Functional protein network analysis of significant plasma proteins associated with PPT in FM. The STRING version 11 was used to create the network analysis (https://string-db.org/). C3 Complement C3, FGB Fibrinogen beta chain, SERPINA1 Alpha-1-antitrypsin, SERPINF2 Alpha-2-antiplasmin, KNG1 Kininogen-1, AGT Angiotensinogen, AHSG Alpha-2-HS-glycoprotein, HPX Hemopexin.

Figure 7

Psychological distress and associated plasma proteins in FM. Score plot (left) shows a within-group separation among the FM group based on HADS total score. The larger the triangles, the higher the score. The loading plot (right) shows 26 proteoforms correlated with HADS total (VIP > 1); eight out of 26 proteoforms were associated with moderate psychological distress (HADS total > 21). Numbers in the loading plot equals the spot numbers in Table 5 and supplementary Figure S1 and Table S1. The loading and score plots were created in SIMCA P + (version 15).

Figure 8

Pathway analysis of plasma proteins associated with psychological distress in FM. Functional protein network analysis of significant proteins associated with psychological distress in FM. The STRING version 11 was used to create the network analysis (https://string-db.org/). FCN3, Ficolin-3, A1BG Alpha-1B-glycoprotein, HP Haptoglobin, FGB Fibrinogen beta chain, FGA Fibrinogen alpha chain, C4BPA C4b-binding protein alpha chain, SERPINF2 Alpha-2-antiplasmin, KNG1 Kininogen-1, APOA1 Apolipoprotein A-I, AHSG Alpha-2-HS-glycoprotein, C1R Complement C1r subcomponent, HPX Hemopexin, SAA4 Serum amyloid A-4 protein, GC Vitamin D-binding protein.

Figure 9

Venn diagram of shared proteoforms and proteins. (a) Venn diagram showing shared proteoforms between all models. Group group differences FM and CON, PPT PPT in FM, HADS Psychological distress in FM, VAS pain intensity in FM. Numbers prior protein name refer to unique spot numbers, while UniProt accession number for each protein is indicated in parenthesis. (b) Upper Venn diagram shows shared proteins between all four MVDA models. Venn diagrams below shows the comparison between two models individually, displaying the total number of shared proteins between respective models. UniProt accession number is indicated in parenthesis. The Venn diagrams were created in R using the Venndiagram package.