Inflammation and innate immune response in chronic widespread pain

Introduction Dysregulation of the immune system may play a role in
chronic widespread pain (CWP) although study findings so far are
inconsistent. This cross-sectional study examined whether basal inflammatory
markers and the innate immune response are associated with the
presence and severity of CWP. Methods Data are from the Netherlands
Study of Depression and Anxiety including 1632 subjects. The Chronic
Pain Grade questionnaire was used to determine the presence and severity
of CWP. Subjects were categorized in a CWP group (n=754) and a
control group (n=878). Blood levels of the basal inflammatory markers
C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor
(TNF-) alpha were determined. To obtain a measure of the innate immune
response, 13 inflammatory markers were assessed after lipopolysaccharide
(LPS) stimulation in a random subsample (n=707). Results Compared
to controls, subjects with CWP showed elevated levels of basal
inflammatory markers. However, this association was no longer significant
after adjustment for lifestyle and disease factors. For the LPSstimulated
inflammatory markers, we did find elevated levels in CWP
subjects both before and after adjustment for covariates. Within CWP
subjects, pain severity was not associated with inflammation. Conclusion
This study demonstrates an exaggerated innate immune response in CWP.
Elevated basal inflammatory levels in CWP were driven by lifestyle and
disease factors. We suggest that the innate immune response could be a
potential biomarker for the onset or perpetuation of CWP.