Neuroinflammation in Neuropathic Pain Signaled by Chemokine Levels in CSF
Patients with neuropathic pain have higher levels of a set of proinflammatory chemokines.
Patients with neuropathic pain have elevated levels of a set of proinflammatory chemokines compared with healthy individuals, suggesting ongoing neuroinflammation, according to a study published in the journal Pain.
Researchers in this study collected cerebrospinal fluid (CSF) samples from patients with neuropathic pain (n=11) and healthy controls (n=11) and measured the levels of 92 proteins related to inflammation. The levels of the following proinflammatory chemokines were found to be higher in the CSF samples of those with neuropathic pain compared with healthy controls: C-X-C motif chemokine ligand 6 (CXCL6; P <.001), CXCL10 (P <.001), C-C motif ligand 8 (CCL8; P =.011), CCL11 (P =.004), and CCL23 (P =.002).
In addition, investigators compared samples from healthy controls with those of patients with neuropathic pain who were undergoing spinal cord stimulation. A total of 11 proteins had a variable influence on projection >1.3 and were present in high amounts in patients with neuropathic pain. These 100 proteins included CCL11, 4EBP1, CXCL10, CX3CL1, CCL23, CXCL6, CCL8, CCL25, CD5, CXCL11, and LAPTGF-beta-1 (in falling order of variable influence on projection, range 1.75-1.31).
To explore common mediators of neuropathic pain, the investigators suggest future studies should examine common comorbidities, such as anxiety, depression, tiredness, and poor sleep, in people with neuropathic pain.
This study is limited by its small sample size, and would thus require larger patient cohorts for validation. In addition, causality between ongoing inflammation and neuropathic pain was not established.
The researchers commented that their study may “have mirrored central neuroinflammation in this very debilitating chronic pain condition.”
Bäckryd E, Lind AL, Thulin M, Larsson A, Gerdle B, Gordh T. High levels of cerebrospinal fluid chemokines point to the presence of neuroinflammation in peripheral neuropathic pain - a cross-sectional study of two cohorts of patients compared to healthy controls [published online September 18, 2017]. Pain. doi: 10.1097/j.pain.0000000000001061