A few previous studies indicate an ongoing of low-grade systemic inflammation in chronic pain patients (CPP) [1, 2]. In the present study we investigated the plasma inflammatory profile in severely impaired chronic pain patients. In addition we studied if there were any alterations in inflammation patterns at one-year follow up, after the patients had taken part in a CBT-ACT based 4 weeks in-hospital pain rehabilitation program (PRP).
Blood samples were collected from 52 well characterized chronic pain patients. Plasma from matched healthy blood donors were used as controls. At one year after the treatment program, 28 of the patients were available for follow up. Instead of only analyzing single inflammation-related substances, we used a new multiplex panel enabling the simultaneous analysis of 92 inflammation-related proteins, mainly cytokines and chemokines (Proseek Inflammation, Olink, Uppsala, Sweden). Multivariate statistics were used for analysis.
Clear signs of increased inflammatory activity were detected in the pain patients. Accepting a false discovery rate (FDR) of 5%, there were significant differences in 43 of the 92 inflammatory biomarkers. The expression of 8 biomarkers were 4 times higher in patients compared to controls. Three biomarkers, CXCL5, SIRT2, AXIN1 were more than 8 times higher. The conventional marker for inflammation, CRP, did not differ. Of the 28 patients available for follow up one year after the intervention, all showed lower levels of the inflammatory biomarker initially raised.
The results indicate that CPP suffer from a low grade of chronic systemic inflammation, not detectable by CRP analysis. This may have implications for the general pain hypersensitivity, and other symptoms, often described in this group of patients. We conclude that inflammatory plasma proteins may be measureable molecular markers to distinguishes CPP from pain free controls, and that a CBT-ACT pain rehab program seem to decrease this inflammatory activity.