Effect of recombinant Lactococcus lactis producing myelin peptides on neuroimmunological changes in rats with experimental allergic encephalomyelitis.

Multiple sclerosis (MS) is a human autoimmune neurodegenerative disease with an unknown etiology. Despite various therapies, there is no effective cure for MS. Since the mechanism of the disease is based on autoreactive T-cell responses directed against myelin antigens, oral tolerance is a promising approach for the MS treatment. Here, the experiments were performed to assess the impact of oral administration of recombinant Lactococcus lactis producing encephalogenic fragments of three myelin proteins: myelin basic protein, proteolipid protein, and myelin oligodendrocyte glycoprotein, on neuroimmunological changes in rats with experimental allergic encephalomyelitis (EAE) - an animal model of MS. Lactococcus lactis whole-cell lysates were administered intragastrically at two doses (103 and 106 colony forming units) in a twenty-fold feeding regimen to Lewis rats with EAE. Spinal cord slices were subjected to histopathological analysis and morphometric evaluation, and serum levels of cytokines (IL-1b, IL-10, TNF-α and IFN-γ) were measured. Results showed that administration of the L. lactis preparations at the tested doses to rats with EAE, diminished the histopathological changes observed in EAE rats and reduced the levels of serum IL-1b, IL-10 and TNF-α, previously increased by evoking EAE. This suggests that oral delivery of L. lactis producing myelin peptide fragments could be an alternative strategy to induce oral tolerance for the treatment of MS.

Diversity of immunophenotypes of endothelial cells participating in new vessel formation following surgical rat brain injury.

Surgical brain injury causes neovascularization in the disrupted brain parenchyma, which occurs with the participation of endothelial-like cells. Differentiation of angioblasts from embryonic mesothelial cells has been proposed on the ground of biochemical and antigenic similarities between mesothelial and endothelial cells. Therefore, a transient localization of cytokeratin, the main mesothelial intermediate filament protein, to some embryonic vessels and endothelial progenitors, prompted us to use it to identify the source of cells participating in vessel formation after surgical brain injury. To determine the immunophenotypes of immature endothelial cells involved in new vessel formation following surgical rat brain injury, we used immunohistochemical and electron microscopic immunocytochemical techniques. Subcellular localization of protein markers: Flk-1, cytokeratin, and vimentin was examined in the cells investigated. Our results confirmed the existence of a diversity of immunophenotypes of immature endothelial cells in case of surgical-related brain injury.

Locomotion induces changes in Trk B receptors in small diameter cells of the spinal cord.

INTRODUCTION AND METHODS: Locomotor training leads to improvement of stepping ability in animals after spinal cord transection (1). Recent data point to neurotrophins as possible factors involved in this improvement. Motoneurones synthesising BDNF, NT-4 and NT-3 are a potent source of neurotrophins for the spinal network (2, 3). Physical exercise increases BDNF neurotrophin gene expression in the rat hippocampus (4). If exercise enhances BDNF expression also in the spinal cord, upregulation of its receptor Trk B may occur. To verify this hypothesis we tested whether exercise influences TrkB receptor system in the spinal cord. Six adult, male Wistar rats walked on the treadmill five days a week, 1,000 m daily with the speed of 20 to 25 cm/s. After 4 weeks of training animals were anaesthetised with pentobarbital sodium (80 mg/kg b.w.) and perfused with 0.01 M PBS followed by 2% paraformaldehyde and 0.2% parabenzoquinone in 0.1 M PB. Three non-trained animals were used as controls. Cryostat 40 microns sections were processed free-floating with TrkB polyclonal antibody (1:1,000, Santa Cruz) and ABC Vectastain detection system. Sections were examined under Nikon light microscope and analysed with Image-Pro Plus 4 software. RESULTS AND DISCUSSION: TrkB immunoreactivity (IR) was detected in number of spinal cells at the lumbar level in non-trained animals (Fig. 1A). The strongest IR appeared in the perikarya and processes of small diameter cells rarely scattered in the grey and white matter. The average area of these cells was 50 micron 2 (+/- 10). Exercise increased by over 50% the number of TrkB immunostained small cells (Fig. 1B). An enhancement of perikaryonal immunostaining of these cells was also observed (Fig. 1B, inset). Testing the identity of Trk B IR small diameter cells did not prove their astroglial (GFAP IR) and gabaergic (GAD IR) phenotype in the grey matter. Some of TrkB IR cells in the white matter were astrocytes. Our data point to physical exercise as a potent method to make spinal cells more receptive to neurotrophic stimuli.