PLoS ONE 2011-01-01

Nerve injury evoked loss of latexin expression in spinal cord neurons contributes to the development of neuropathic pain.

Hilmar Nils Kühlein, Irmgard Tegeder, Christine Möser, Hee-Young Lim, Annett Häussler, Katharina Spieth, Ingo Jennes, Rolf Marschalek, Tobias Beckhaus, Michael Karas, Markus Fauth, Corina Ehnert, Gerd Geisslinger, Ellen Niederberger

Index: PLoS ONE 6(4) , e19270, (2011)

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Abstract

Nerve injury leads to sensitization mechanisms in the peripheral and central nervous system which involve transcriptional and post-transcriptional modifications in sensory nerves. To assess protein regulations in the spinal cord after injury of the sciatic nerve in the Spared Nerve Injury model (SNI) we performed a proteomic analysis using 2D-difference gel electrophoresis (DIGE) technology. Among approximately 2300 protein spots separated on each gel we detected 55 significantly regulated proteins after SNI whereof 41 were successfully identified by MALDI-TOF MS. Out of the proteins which were regulated in the DIGE analyses after SNI we focused on the carboxypeptidase A inhibitor latexin because protease dysfunctions contribute to the development of neuropathic pain. Latexin protein expression was reduced after SNI which could be confirmed by Western Blot analysis, quantitative RT-PCR and in-situ hybridisation. The decrease of latexin was associated with an increase of the activity of carboxypeptidase A indicating that the balance between latexin and carboxypeptidase A was impaired in the spinal cord after peripheral nerve injury due to a loss of latexin expression in spinal cord neurons. This may contribute to the development of cold allodynia because normalization of neuronal latexin expression in the spinal cord by AAV-mediated latexin transduction or administration of a small molecule carboxypeptidase A inhibitor significantly reduced acetone-evoked nociceptive behavior after SNI. Our results show the usefulness of proteomics as a screening tool to identify novel mechanisms of nerve injury evoked hypernociception and suggest that carboxypeptidase A inhibition might be useful to reduce cold allodynia.© 2011 Kühlein et al.