Jun-Gyo Suh

Human umbilical cord blood-derived mesenchymal stem cells improve neuropathology and cognitive impairment in an Alzheimer's disease mouse model through modulation of neuroinflammation

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSC) have a potential therapeutic role in the treatment of neurological disorders, but their current clinical usage and mechanism of action has yet to be ascertained in Alzheimers disease (AD). Here we report that hUCB-MSC transplantation into amyloid precursor protein (APP) and presenilin1 (PS1) double-transgenic mice significantly improved spatial learning and memory decline. Furthermore, amyloid-β peptide (Aβ) deposition, β-secretase 1 (BACE-1) levels, and tau hyperphosphorylation were dramatically reduced in hUCB-MSC transplanted APP/PS1 mice. Interestingly, these effects were associated with reversal of disease-associated microglial neuroinflammation, as evidenced by decreased microglia-induced proinflammatory cytokines, elevated alternatively activated microglia, and increased anti-inflammatory cytokines. These findings lead us to suggest that hUCB-MSC produced their sustained neuroprotective effect by inducing a feed-forward loop involving alternative activation of microglial neuroinflammation, thereby ameliorating disease pathophysiology and reversing the cognitive decline associated with Aβ deposition in AD mice.

SIRT1 regulates tyrosine hydroxylase expression and differentiation of neuroblastoma cells via FOXO3a

To examine the function of SIRT1 in neuronal differentiation, we employed all‐trans retinoic acid (ATRA)‐induced differentiation of neuroblastoma cells. Nicotinamide inhibited neurite outgrowth and tyrosine hydroxylase (TH) expression. Inhibition of PARP or histone deacetylase did not inhibit TH expression, showing the effect to be SIRT1 specific. Expression of FOXO3a and its target proteins were increased during the differentiation and reduced by nicotinamide. FOXO3a deacetylation was increased by ATRA and blocked by nicotinamide. SIRT1 and FOXO3a siRNA inhibited ATRA‐induced up‐regulation of TH and differentiation. Taken together, these results indicate that SIRT1 is involved in ATRA‐induced differentiation of neuroblastoma cells via FOXO3a.

The over-expression of somatostatin in the gerbil entorhinal cortex induced by seizure

In present study, we investigated the immunohistochemical distribution of somatostatin (SRIF) in the hippocampal complex of the Mongolian gerbil and its association with different sequelae of spontaneous seizures, in an effort to identify the roles of SRIF in the self-recovery mechanisms in these animals. In the dentate gyrus and subiculum, SRIF immunoreactive (SRIF(+)) cells were similar in both the seizure resistant and the pre-seizure group of seizure sensitive gerbils. Interestingly, SRIF immunoreactivity was markedly decreased until 12 h postictal. Twenty-four hours after the on-set of seizure, the distribution of SRIF immunoreactivity in these regions had slightly increased. In contrast, in the entorhinal cortex the population of SRIF(+) cells and their density were significantly elevated compared to pre-seizure group 30 min postictal. Twelve hours after the on-set of seizure, however, the population of SRIF(+) cells and their density declined, approximately 70-80% compared to the situation at 30 min postictal. These findings suggest that the enhancement of SRIF expression in gerbil entorhinal cortex may affect tissue excitability and have a role in modulating recurrent excitation following seizures.

The temporal and spatial expressions of neuropeptide Y induced by seizure in the hippocampal complex of gerbil

Recent studies reported changes in neuropeptide Y (NPY) expression induced by seizures in the experimental epileptic models. However, there have been few reports of the alteration of NPY expression in hippocampal complexes of genetic epilepsy models. In the present study, we performed spatial and temporal analyses of NPY expression in the hippocampal complexes of the seizure-resistant (SR) and seizure-sensitive (SS) gerbils, one of the genetic models. In SR gerbils, most NPY(+) cells were located at the dentate hilus (DH) and the subiculum (SC). In the pre-seizure group of SS gerbils, neurons in the DH and SC were nearly devoid of NPY immunoreactivity. Interestingly, the acute NPY expressions were observed in these areas of the post-seizure group at 30 min, and its immunoreactivity was declined at 12 h after the onset of seizure. These findings suggest that in seizure, the deficiency of NPY in DH and SC may be one of the factors, and that the acute expression of NPY after seizure in these areas may be the compensatory response for reduction of seizure activity in this animal.

Alterations in Na+/H+ exchanger and Na+/HCO3- cotransporter immunoreactivities within the gerbil hippocampus following seizure.

In this study, a chronological and comparative analysis of the immunoreactivities of Na(+)/H(+) exchanger 1 (NHE1), Na(+)/HCO(3)(-) cotransporter (NBC) and Na(+)/Ca(2+) exchanger (NCE) was conducted in order to identify the effects of spontaneous seizure on their protein expression levels using the gerbil model. The distribution of NHE1 and NBC immunoreactivity in the hippocampus of seizure-resistant (SR) gerbils was similar to that observed in the pre-seizure group of seizure-sensitive (SS) gerbils. From 30 min to 3 h after the onset of the seizure, both NHE1 and NBC immunoreactivities were elevated in the hippocampus, as compared to the pre-seizure group of SS gerbils. At 6 h postictal, these immunoreactivities in the hippocampus had reduced to the pre-seizure level. However, NCE immunoreactivity within the hippocampus was unaltered. These findings suggest that the changes in both NHE1 and NBC immunoreactivity within the hippocampus following seizure may affect tissue excitability and play a role in the reduction of the seizure activity in the gerbil.

Production of antibodies with peptide-CpG-DNA-liposome complex without carriers

BackgroundThe screening of peptide-based epitopes has been studied extensively for the purpose of developing therapeutic antibodies and prophylactic vaccines that can be potentially useful for treating cancer and infectious diseases such as influenza virus, malaria, hepatitis B, and HIV. To improve the efficacy of antibody production by epitope-based immunization, researchers evaluated liposomes as a means of delivering vaccines; they also formulated adjuvants such as flagella and CpG-DNA to enhance the magnitude of immune responses. Here, we provide a potent method for peptide-based epitope screening and antibody production without conventional carriers.ResultsWe present that a particular form of natural phosphodiester bond CpG-DNA encapsulated in a specific liposome complex (Lipoplex(O)) induces potent immunomodulatory activity in humans as well as in mice. Additionally, Lipoplex(O) enhances the production of IgG2a specific to antigenic protein in mice. Most importantly, immunization of mice with several peptides co-encapsulated with Lipoplex(O) without carriers significantly induces each peptide-specific IgG2a production in a TLR9-dependent manner. A peptide-specific monoclonal antibody produced against hepatocellular carcinoma-associated antigen has functional effects on the cancer cells.ConclusionsOur overall results show that Lipoplex(O) is a potent adjuvant and that complexes of peptide and Lipoplex(O) are extremely useful for B cell epitope screening and antibody production without carriers. Therefore, our strategy may be promptly used for the development of therapeutic antibodies by rapid screening of potent B cell epitopes.

The differential expression of corticotropin releasing factor and its binding protein in the gerbil hippocampal complex following seizure.

Considerable attention has been focused on the role of corticotropin releasing factor (CRF) as well as CRF-binding protein (CRF-BP) in neuropsychiatric disorders and neurodegenerative diseases including epilepsy. Therefore, in the present study, we investigated the temporal and spatial alteration of CRF and CRF-BP in the gerbil hippocampal complex in order to characterize the possible changes and associations with different sequelae of spontaneous seizure in these animals. CRF immunoreactivity was shown in the interneurons of the hippocampal complex at 30 min following seizure. Additionally, alteration of CRF-BP immunoreactivity was restricted to the entorhinal cortex after seizure. These results indicate some factors for consideration. First, in the gerbil hippocampal complex, the delayed increase of CRF immunoreactivity, in spite of its excitatory function, may attenuate seizure activity, but may not do so in epileptogenesis. Second, in contrast to the hippocampal complex, the increase in CRF-BP immunoreactivity in the entorhinal cortex following seizure may participate in feedback inhibitory modulation.

Altered corticotropin-releasing factor (CRF) receptor immunoreactivity in the gerbil hippocampal complex following spontaneous seizure

Considerable attention has been focused on the role of corticotropin-releasing factor (CRF) in neuropsychiatric disorders and neurodegenerative diseases including epilepsy. Therefore, in the present study, we investigated the temporal and spatial alteration of CRF receptor in the gerbil hippocampal complex in order to characterize the possible changes and associations with different sequelae of spontaneous seizure in these animals. Thirty minutes postictal, a decline in CRF receptor immunoreactivity was observed in the granule cells and hilar neurons. In the subiculum, CRF receptor immunoreactivity was also significantly decreased at this time point. Twenty-four hours after seizure onset, the immunoreactivity in these regions recovered to the pre-seizure level. Moreover, 30 min after seizure in the entorhinal cortex, the density of CRF receptor immunoreactivity began to decrease, particularly in the layers II and III, compared to pre-seizure group. Nevertheless, 24h after seizure onset, CRF receptor immunodensity had recovered to its seizure-sensitive (SS) level. These results suggest that altered CRF receptor expression in the hippocampal complex may affect tissue excitability and seizure activity in SS gerbils.

Changes in Na(+)-K(+)-Cl(-) cotransporter immunoreactivity in the gerbil hippocampus following spontaneous seizure.

The immunoreactivity of Na(+)-K(+)-Cl(-) cotransporter (NKCC) in the gerbil hippocampus associated with various sequelae of spontaneous seizures were investigated in order to identify the roles of NKCC in the epileptogenesis and the recovery mechanisms in these animals. The NKCC immunoreactivities in the CA2-3 regions, the subiculum and the entorhinal cortex, were significantly more intensified in the pre-seizure group of seizure sensitive (SS) gerbils than in the seizure resistant (SR) gerbils. Following the on-set of seizure, the immunoreactivity of NKCC was significantly changed. In the hippocampal complex except the CA1 region, NKCC immunoreactivity in GABAergic neurons was significantly decreased 30 min after seizure on-set, versus the pre-seizure group. On the other hand, NKCC immunoreactivity was dramatically elevated in the CA1 regions, and 3 h postictal NKCC immunoreactivity increased significantly in the dentate gyrus and the dendrites of the pyramidal cells in the CA2-3 regions. These findings suggest that altered NKCC expression may be associated with seizure activity, and have an important role in the postictal recovery by regulating GABA-mediated inhibitory circuit in the hippocampal complex of the gerbil.

Galanin-Immunoreactive Cells and Their Relation to Calcitonin Gene-Related Peptide-, Substance P- and Somatostatin-Immunoreactive Cells in Rat Lumbar Dorsal Root Ganglia

We report upon the distribution of galanin‐immunoreactive (GAL‐IR) cells in the lumbar dorsal root ganglia (DRG) of the rat, and upon the distribution of GAL‐IR cells, which also contain calcitonin gene‐related peptide (CGRP)‐, substance P (SP)‐ and somatostatin (SOM)‐immunoreactivity. Neuropeptide‐immunoreactive lumbar DRG cells were 55.8% for CGRP, 12.7% for SP, and 6.5% for GAL in lumbar DRG cells. There was no significant difference between the right and left DRGs (L1−L6) for any neuropeptide‐immunoreactive cell (P<0.01). In terms of size distribution, CGRP‐immunoreactive cells were identified below 1500 μm2, and SP‐, and GAL‐IR cells below 600 μm2. Neuropeptide immunoreactive cells showed various immunoreactivities in the cytoplasm according to each neuropeptide. CGRP and SP immunoreactive cells were colocalized with GAL immunoreactive cells in the serial sections about 83.3 and 60% respectively, but SOM colocalizing with GAL‐IR cells were not in evidence. The current results confirm and extend previous results, and show that neuropeptides can coexist in single sensory neurones of the rat DRG. In addition, our results demonstrate that the normal distribution of some neurotransmitters modulating sensory action in Wistar Kyoto rat, make this model more prone to develop neuropathic pain than Sprague‐Dawley rat.