Fetal and Perinatal Expression Profiles of Proinflammatory Cytokines in the Neuroplacodes of Rats with Myelomeningoceles: A Contribution to the Understanding of Secondary Spinal Cord Injury in Open Spinal Dysraphism.

The cellular and molecular mechanisms that presumably underlie the progressive functional decline of the myelomeningocele (MMC) placode are not well understood. We previously identified key players in post-traumatic spinal cord injury cascades in human MMC tissues obtained during postnatal repair. In this study, we conducted experiments to further investigate these mediators in the prenatal time course under standardized conditions in a retinoic acid-induced MMC rat model. A retinoic acid MMC model was established using time-dated Sprague-Dawley rats, which were gavage-fed with all-trans retinoic acid (RA; 60 mg/kg) dissolved in olive oil at E10. Control animals received olive oil only. Fetuses from both groups were obtained at E16, E18, and E22. The spinal cords (SCs) of both groups were formalin-fixed or snap-frozen. Tissues were screened by real-time reverse transcription polymerase chain reaction for the expression of cytokines and chemokines known to play a role in the lesion cascades of the central nervous system after trauma. MMC placodes exhibited inflammatory cells and glial activation in the later gestational stages. At the messenger RNA (mRNA) level, interleukin-1 beta, tumor necrosis factor alpha, and tumor necrosis factor receptor type 1 exhibited significant induction at E22. interleukin-1 beta receptor type 1 mRNA was induced significantly at E16 and E22. Double labeling experiments confirmed the co-staining of these cytokines and their receptors with ionized calcium-binding adapter molecule 1 (i.e., inflammatory cells), vimentin, and nestin in different anatomical SC areas and neuronal nuclear protein in ventral horn neurons. C-X-C motif chemokine 12 mRNA was elevated in control and MMC animals at E16 compared with E18 and E22. C-X3-C motif ligand 1 mRNA was lower in MMC tissues than in control tissues on E16. The presented findings contribute to the concept that pathophysiological mechanisms, such as cytokine induction in the neuroplacode, in addition to the "first hit," promote secondary spinal cord injury with functional loss in the late fetal time course. Further, these mediators should be taken into consideration in the development of new therapeutic approaches for open spinal dysraphism.

Expression profiles of pro-inflammatory and pro-apoptotic mediators in secondary tethered cord syndrome after myelomeningocele repair surgery.

PURPOSE: The literature on histopathological and molecular changes that might underlie secondary tethered cord syndrome (TCS) after myelomeningocele (MMC) repair surgeries remains sparse. To address this problem, we analyzed specimens, which were obtained during untethering surgeries of patients who had a history of MMC repair surgery after birth. METHODS: Specimens of 12 patients were analyzed in this study. Clinical characteristics were obtained retrospectively including pre-operative neurological and bowel/bladder-function, contractures and spasticity of lower extremities, leg and back pain, syringomyelia, and conus position on spinal MRI. Cellular marker expression profiles were established. Further, immunoreactivities (IR) of IL-1ß/IL-1R1, TNF-α/TNF-R1, and HIF-1α/-2α were analyzed qualitatively and semi-quantitatively by densitometry. Co-labeling with cellular markers was determined by multi-fluorescence-labeling. Cytokines were further analyzed on mRNA level. Immunostaining for cleaved PARP and TUNEL was performed to detect apoptotic cells. RESULTS: Astrocytosis, appearance of monocytes, activated microglia, and apoptotic cells in TCS specimens were one substantial finding of these studies. Besides neurons, these cells co-stained with IL-1ß and TNF-α and their receptors, which were found on significantly elevated IR-level and partially mRNA-level in TCS specimens. Staining for HIF-1α/-2α confirmed induction of hypoxia-related factors in TCS specimens that were co-labeled with IL-1ß. Further, hints for apoptotic cell death became evident by TUNEL and PARP-positive cells in TCS neuroepithelia. CONCLUSIONS: Our studies identified pro-inflammatory and pro-apoptotic mediators that, besides mechanical damaging and along with hypoxia, might promote TCS development. Besides optimizing surgical techniques, these factors should also be taken into account when searching for further options to improve TCS treatment.