Differential expression of cytokines in painful and painless neuropathies

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Neurology. 2007 Jul 3;69(1):42-9.

Differential expression of cytokines in painful and painless

neuropathies.

Uçeyler N, Rogausch JP, Toyka KV, Sommer C.

Department of Neurology, University of Würzburg, Würzburg, Germany.

BACKGROUND: Pain is a common symptom in peripheral neuropathies. The

factors determining why some peripheral neuropathies are painful and

others are not are incompletely understood. Pro-inflammatory

cytokines have been implicated to play a crucial role in the

generation of pain.

OBJECTIVE: To investigate whether cytokine profiles differ between

patients with painful or painless neuropathy.

METHODS: In this prospective study, we analyzed blood mRNA and

protein levels of the pro-inflammatory cytokines interleukin-2 (IL-

2) and tumor necrosis factor-alpha (TNF) and the anti-inflammatory

cytokines IL-4 and IL-10 in 32 patients with painful neuropathy, 20

patients with painless neuropathy, and 38 healthy control subjects,

using quantitative real-time PCR and ELISA.

RESULTS: Patients with a painful neuropathy had about twofold higher

IL-2 mRNA (p = 0.001) and TNF mRNA (p < 0.0001) and protein levels

(p = 0.009) than healthy control subjects and about twofold higher

IL-2 and TNF mRNA (p = 0.03; p = 0.001) and protein levels (p =

0.04; p = 0.04) than patients with painless neuropathy.

In contrast, mRNA levels of the anti-inflammatory cytokine IL-10

were about twofold higher in patients with painless neuropathy than

in patients with painful neuropathy (p = 0.001) and controls (p =

0.004). IL-4 protein levels were 20-fold higher in patients with

painless neuropathy (p < 0.0001) and 17-fold higher in patients with

painful neuropathy (p < 0.0001) than in healthy control subjects.

CONCLUSIONS: A pro-inflammatory cytokine profile seems to be

associated with pain in the setting of a peripheral neuropathy,

corroborating findings in animal models with experimental painful

neuropathies.

This may have implications for future treatment strategies.