title: Interleukin-2 gene therapy of chronic neuropathic pain.
abstract: Previous research has revealed an antinociceptive (analgesic) effect of interleukin-2 (IL-2) in central and peripheral nervous systems. Unfortunately IL-2 is very short-lived in vivo, so it is impractical to apply IL-2 for analgesia in clinic. This study was performed to evaluate the effect of intrathecal delivery of human IL-2 gene on rat chronic neuropathic pain induced by chronic constriction injury of the sciatic nerve. Human IL-2 cDNA was cloned into pcDNA3 containing a cytomegalovirus promoter. The paw-withdrawal latency induced by radiant heat was used to measure the pain threshold. The results showed that recombinant human IL-2 had a dose-dependent antinociceptive effect, but that this only lasted for 10-25 min. The pcDNA3-IL-2 or pcDNA3-IL-2/lipofectamine complex in contrast also showed dose-dependent antinociceptive effects, but these reached a peak at day 2-3 and were maintained for up to 6 days. Liposome-mediated pcDNA3-IL-2 produced a more powerful antinociceptive effect than pcDNA3-IL-2 alone. The paw-withdrawal latencies were not affected by control treatments such as vehicle, lipofectamine, pcDNA3, or pcDNA3-lipofectamine. In the experimental groups, human IL-2 mRNA was detected by reverse transcription-polymerase chain reaction in the lumbar spinal pia mater, dorsal root ganglion, sciatic nerve, and spinal dorsal horn, but not in gastrocnemius muscle. The expressed IL-2 profile detected by western blot coincided with its mRNA profile except it was present in the spinal dorsal horn at a higher level. Furthermore, human IL-2 assayed by enzyme-linked immunosorbent assay in cerebrospinal fluid could still be detected at day 6, but lower than day 3. The antinociceptive effect of pcDNA3-IL-2 could be blocked by naloxone, showing some relationship of the antinociceptive effect produced by IL-2 gene to the opioid receptors. It is hoped that the new delivery approach of a single intrathecal injection of the IL-2 gene described here may be of some practical use as a part of a gene therapy for treating neuropathic pain.
authors.affiliation: Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, PR China.
authors.forename: M-Z
authors.initials: MZ
authors.lastname: Yao
authors.forename: J-F
authors.initials: JF
authors.lastname: Gu
authors.forename: J-H
authors.initials: JH
authors.lastname: Wang
authors.forename: L-Y
authors.initials: LY
authors.lastname: Sun
authors.forename: M-F
authors.initials: MF
authors.lastname: Lang
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: Z-Q
authors.initials: ZQ
authors.lastname: Zhao
authors.forename: X-Y
authors.initials: XY
authors.lastname: Liu
mesh_terms: D000818:Animals; D019556:COS Cells / Q000187:drug effects / Q000378:metabolism; D002411:Cation Exchange Resins; D002908:Chronic Disease; D018076:DNA, Complementary / Q000008:administration & dosage; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007278:Injections, Spinal; D007376:Interleukin-2 / Q000134:cerebrospinal fluid / Q000235:genetics / Q000627:therapeutic use*; D008026:Ligation; D008055:Lipids; D008081:Liposomes; D008297:Male; D009270:Naloxone / Q000008:administration & dosage; D009292:Narcotic Antagonists / Q000008:administration & dosage; D009928:Organ Specificity; D010146:Pain / Q000209:etiology / Q000503:physiopathology; D059408:Pain Management; D010147:Pain Measurement / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000134:cerebrospinal fluid / Q000235:genetics / Q000627:therapeutic use; D020426:Sciatic Neuropathy / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D015398:Signal Transduction / Q000187:drug effects; D014018:Tissue Distribution; D014162:Transfection
chemical_list: D002411:Cation Exchange Resins; D018076:DNA, Complementary; D007376:Interleukin-2; D008055:Lipids; C086724:Lipofectamine; D008081:Liposomes; D009292:Narcotic Antagonists; D012333:RNA, Messenger; D011994:Recombinant Proteins; D009270:Naloxone