Parallel expression of neurotrophic factors and their receptors in chronic inflammatory demyelinating polyneuropathy

The mRNA levels of nerve growth factor (NGF), glial cell line-derived neurotrophic factor (GDNF), ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), and interleukin-6 (IL-6) were examined in sural nerves of 22 patients with chronic inflammatory demyelinating polyneuropathy (CIDP). The mRNAs for NGF, GDNF, LIF, and IL-6 were upregulated, whereas CNTF mRNA was downregulated significantly in the nerves. The NGF, GDNF, and CNTF, but not LIF mRNA expressions were parallel to those of the cognate receptors, suggesting that these cognate soluble receptors effectively present these factors to maintain and regenerate the axons. Furthermore, IL-6 mRNA expression was significantly parallel to both binding and signal-transducing receptor expression, implying a role of the IL-6 signal for non-neuronal cells in CIDP. These findings indicate that multiple neurotrophic growth factors and cytokines are expressed cooperatively with their concomitant receptors in the nerve lesions of CIDP and play an important role particularly in nerve repair.