Autoimmune Mechanisms in Fibromyalgia

Visit 1 (duration approx. 2,5-4 hours)

Questionnaires: A check of inclusion and exclusion criteria was made, including the palpation of tender points (ACR 1990 FM criteria). Subjects completed a set of validated questionnaires regarding pain (pain intensity ratings on visual analogue scale (VAS), pain duration, pain drawing, Short form McGill), fibromyalgia severity (fibromyalgia impact questionnaire, (FIQ)), sleep (Pittsburgh Sleep Inventory Questionnaire, (PSQI)), fatigue (Multidimensional Fatigue Inventory (MFI-20)), depression/anxiety (Hospital anxiety depression scale (HADS), Becks depression inventory (BDI), State Trait Anxiety Questionnaire (STAI)), pain coping (Coping Strategy Questionnaire (PCS)), acceptance and flexibility (chronic pain acceptance questionnaire (CPAQ-8), acceptance and action questionnaire (SAAQ)), the Tampa Scale for Kinesiophobia (TSK) and health related quality of life (EQ-5D).

Quantitative sensory testing: Perception thresholds for non-painful and painful heat/cold were examined using a Thermotest. A thermode (2x2cm) was placed at the skin and the temperature was modulated by a computer (0-50 degrees C). The subject signaled the respective perception by pressing a button, which terminated the stimulation. Subjects were instructed to press the button at the sensation of the slightest warmth/cold and when the heat/cold become painful. Sensitivity to suprathreshold heat/cold pain stimuli were determined by asking the subject to press the button when they would rate a pain intensity corresponding to 4 and 7/10. Pain sensitivity to pressure was assessed by pressure algometry at 8 different sites in the body. The subjects were instructed to press a signal button when the pressure turned into the slightest sensation of pain (pressure pain threshold) and when the pain corresponded to 4 and 7/10, respectively.

Blood test: Venous blood tests were taken (maximal volume 50 ml/individual). The levels of human IgG binding to murine satellite glia cells (SGC) will be determined as % SGC binding human IgG. In addition, we will also assess the amount of IgG binding to human DRG sections and possibly also to human SGC (postmortem donors). The blood samples will also be analysed for algogenic and inflammatory substances, lipids and metabolites and immune cell activation, including fluorescence-activated cell sorting (FACS)(in a subgroup). As an extension of the study, IgG antibodies will be purified to evaluate the effect on cell cultures and in the rodent FM model.

Skin biopsies: Two punch skin biopsies (4 mm diameter) were performed at the thigh. The skin was sterilized, and anesthetized using a local anesthetic (10mg/ml Xylocain with adrenalin). If needed the was treated with spongostan/BloodStop and a special plaster (Steri-Strip) was always applied for 7-10 days. The skin will be analyzed regarding morphological changes of intradermal small fibres and IENFD and thick myelinated fibers will be determined. In addition, immune cell activation will be assessed using various methods.