Ho-Won Lee

Inhibition of glial inflammatory activation and neurotoxicity by tricyclic antidepressants

Glial activation and neuroinflammatory processes play an important role in the pathogenesis of neurodegenerative diseases such as Alzheimers disease, Parkinsons disease, and HIV dementia. Activated glial cells can secrete various proinflammatory cytokines and neurotoxic mediators, which may contribute to neuronal cell death. Inhibition of glial activation may alleviate neurodegeneration under these conditions. In the present study, the antiinflammatory and neuroprotective effects of tricyclic antidepressants were investigated using cultured brain cells as a model. The results showed that clomipramine and imipramine significantly decreased the production of nitric oxide or tumor necrosis factor-alpha (TNF-alpha) in microglia and astrocyte cultures. Clomipramine and imipramine also attenuated the expression of inducible nitric oxide synthase and proinflammatory cytokines such as interleukin-1beta and TNF-alpha at mRNA levels. In addition, clomipramine and imipramine inhibited IkappaB degradation, nuclear translocation of the p65 subunit of NF-kappaB, and phosphorylation of p38 mitogen-activated protein kinase in the lipopolysaccharide-stimulated microglia cells. Moreover, clomipramine and imipramine were neuroprotective as the drugs reduced microglia-mediated neuroblastoma cell death in a microglia/neuron co-culture. Therefore, these results imply that clomipramine and imipramine have antiinflammatory and neuroprotective effects in the central nervous system by modulating glial activation.

Neuronal pentraxin receptor in cerebrospinal fluid as a potential biomarker for neurodegenerative diseases

Neurodegenerative diseases, such as Alzheimers disease (AD) and Parkinsons disease (PD), are characterized by progressive loss of cognitive function, dementia, and problems with movements. In order to find new protein biomarkers of high specificity from cerebrospinal fluid (CSF) of AD and PD patients, one-dimensional gel electrophoresis (1-DE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) as well as 2-DE analysis were performed. In 1-DE and LC-MS/MS 371 proteins were identified, among which levels of proteins such as isoform 1 of contactin-1, contactin-2, carnosine dipeptidase 1 (CNDP1), 120 kDa isoform precursor of neural cell adhesion molecule 1 (NCAM-120), alpha-dystroglycan, secreted protein acidic and rich in cysteine-like protein 1 precursor (SPARCL1), isoform 2 of calsyntenin 1 (CLSTN1), and neuronal pentraxin receptor (NPR) showed significant changes in AD or PD CSF compared with normal subjects. In 2-DE analysis approximately 747-915 spots were detected in CSF of AD or PD patients, from which 17-24 proteins with more than a 1.2 fold change were identified by tandem MS. Most proteins identified showed consistent changes in LC-MS/MS and 2-DE analysis. Three proteins that showed significant changes were selected for further validation by Western blot analysis. While NCAM-120 and alpha-dystroglycan exhibited higher levels in both AD and PD CSF compared with normal subjects, the level of NPR was increased only in AD CSF in Western blot analysis. The results were consistent with quantitative analysis of 2-DE spots. A higher level of NPR was also found in AD serum. This study suggests that NCAM-120, alpha-dystroglycan, and NPR are candidate biomarkers in CSF for neurodegenerative diseases, and that the changes in the CSF level of NPR may be specific for AD.

Tinnitus: Characteristics, Causes, Mechanisms, and Treatments

Tinnitus-the perception of sound in the absence of an actual external sound-represents a symptom of an underlying condition rather than a single disease. Several theories have been proposed to explain the mechanisms underlying tinnitus. Tinnitus generators are theoretically located in the auditory pathway, and such generators and various mechanisms occurring in the peripheral auditory system have been explained in terms of spontaneous otoacoustic emissions, edge theory, and discordant theory. Those present in the central auditory system have been explained in terms of the dorsal cochlear nucleus, the auditory plasticity theory, the crosstalk theory, the somatosensory system, and the limbic and autonomic nervous systems. Treatments for tinnitus include pharmacotherapy, cognitive and behavioral therapy, sound therapy, music therapy, tinnitus retraining therapy, massage and stretching, and electrical suppression. This paper reviews the characteristics, causes, mechanisms, and treatments of tinnitus.

Cognitive effects of low-dose topiramate monotherapy in epilepsy patients: A 1-year follow-up

The present study was conducted to evaluate the long-term effects of low-dose topiramate (TPM) monotherapy on the cognitive function of epilepsy patients. Forty-seven epilepsy patients received TPM, with target doses of 50, 75, and 100 mg/day. Cognitive tests were performed twice, at baseline and 1 year after starting medication. Thirty-six patients completed the follow-up neuropsychological tests. After a year of treatment, 16 patients (44%) complained of cognitive problems. Although it improved seizure frequency and EEG abnormalities, TPM had significantly negative effects on the digit span and verbal fluency tests. These cognitive effects were dose-related and significantly improved after withdrawal from TPM and substitution with older antiepileptic drugs. In conclusion, even at a low dose, TPM has long-term, negative effects on working memory and verbal fluency.

Long-term cognitive and mood effects of zonisamide monotherapy in epilepsy patients.

This study was a prospective, randomized, open-label investigation of the long-term effects of zonisamide (ZNS) monotherapy on cognition and mood of patients with epilepsy. Forty-three patients with epilepsy received ZNS, with final dose groups of 100, 200, 300, and 400mg/day. Cognitive and mood tests were done twice, at baseline and 1 year after starting medication. Nine patients were withdrawn prior to their follow-up tests. Three patients (33%) dropped out during the titration period because of cognitive and mood problems. Thirty-four patients completed follow-up neuropsychological tests. After 1 year of treatment, 16 patients (47%) complained of cognitive deficits. Only 5 patients (15%) experienced mood changes. Although ZNS decreased seizure frequency and EEG abnormalities and did not elicit significant mood changes, it had negative effects on several cognitive tests. Worse performance on delayed word recall, Trail Making Test Part B, and verbal fluency was related to dose. In conclusion, ZNS has adverse effects on cognition even after 1 year of treatment.

Regulation of systemic energy homeostasis by serotonin in adipose tissues

Central serotonin (5-HT) is an anorexigenic neurotransmitter in the brain. However, accumulating evidence suggests peripheral 5-HT may affect organismal energy homeostasis. Here we show 5-HT regulates white and brown adipose tissue function. Pharmacological inhibition of 5-HT synthesis leads to inhibition of lipogenesis in epididymal white adipose tissue (WAT), induction of browning in inguinal WAT and activation of adaptive thermogenesis in brown adipose tissue (BAT). Mice with inducible Tph1 KO in adipose tissues exhibit a similar phenotype as mice in which 5-HT synthesis is inhibited pharmacologically, suggesting 5-HT has localized effects on adipose tissues. In addition, Htr3a KO mice exhibit increased energy expenditure and reduced weight gain when fed a high-fat diet. Treatment with an Htr2a antagonist reduces lipid accumulation in 3T3-L1 adipocytes. These data suggest important roles for adipocyte-derived 5-HT in controlling energy homeostasis.

Neurotoxicity of microglial cathepsin D revealed by secretome analysis

Microglia‐driven inflammatory responses have both neuroprotective and neurotoxic effects in the CNS. The excessive and chronic activation of microglia, however, may shift the balance towards neurotoxic effects. In this regard, proteins secreted from activated microglia likely play a key role in the neurotoxic effects. To characterize secreted proteins of activated microglia, conditioned media obtained from BV‐2 mouse microglia cells were analyzed by two‐dimensional gel electrophoresis or liquid chromatography coupled with tandem mass spectrometry. Among many proteins identified in the secretome of activated microglia, an aspartic endoprotease cathepsin D has been found to mediate microglial neurotoxicity based on the following results: (i) the expression of cathepsin D protein was markedly increased in lipopolysaccharide/interferon‐γ‐stimulated microglia compared with resting microglia as determined by western blot analysis of conditioned media; (ii) knockdown of cathepsin D expression in microglia using short hairpin RNA diminished the neurotoxicity in the coculture of microglia and neuroblastoma cells and (iii) recombinant procathepsin D protein exerted cytotoxic effects toward cultured neurons. In conclusion, cathepsin D appears to play a central role in the microglial neurotoxicity, and could be a potential biomarker or drug target for the diagnosis and treatment of neurodegenerative diseases that are associated with excessive microglial activation and subsequent neurotoxic inflammation.

Differential effects of seizure control and affective symptoms on quality of life in people with epilepsy

OBJECTIVE The purpose of the study was to delineate how affective symptoms (AS) influence quality of life (QOL) for individuals with drug-refractory epilepsy (DRE) and those with well-controlled epilepsy (WCE) independently. METHODS All subjects participating in the study were asked to complete reliable and validated self-report health questionnaires, including AS, measured with the Korean versions of the Beck Depression Inventory, Beck Anxiety Inventory, and Quality of Life in Epilepsy Inventory-31 (QOLIE-31). We examined predictors of QOLIE-31 scores among the various demographic and clinical factors. We compared the effects of AS on QOL between patients with DRE and those with WCE and investigated the differential effects of seizure control and AS on QOL. RESULTS Two hundred forty-nine patients with DRE or WCE were included in the study. The strongest predictor of QOL was AS, followed by seizure control and MRI abnormality. Affective symptoms had almost two times the effect of seizure control and six times the effect of MRI abnormality. Poorest QOL was noted in patients with DRE with AS, followed by those with WCE with AS, DRE without AS, and WCE without AS. CONCLUSION The major determinant of QOL in patients with epilepsy is AS rather than DRE or WCE status.

Increased plasma levels of lipocalin 2 in mild cognitive impairment

BACKGROUND Alzheimers disease (AD) is a progressive neurodegenerative disorder characterized by an irreversible cognitive decline and neuronal loss associated with neurofibrillary tangles and senile plaques. Mild cognitive impairment (MCI) is a prodromal stage of AD and is associated with memory loss and a high risk of developing AD. Lipocalin 2 (LCN2) is an acute phase protein. Our previous studies have shown that exposure to inflammatory stimuli resulted in elevated LCN2 levels in brain microglia and astrocytes implicating LCN2 in brain inflammation. Therefore, we hypothesize that there may be a significant change in the plasma LCN2 levels in patients with MCI and AD when compared to healthy control subjects. METHODS Forty-one patients with MCI, 62 patients with AD and 38 healthy elderly control subjects were recruited for this study. They were given a comprehensive battery of neuropsychological tests including a mini-mental status examination (MMSE) and clinical dementia rating (CDR). A variety of clinical information was collected from the semi-structured questionnaire administered. The LCN2 levels were measured using a specific enzyme-linked immunosorbent assay in the plasma, which had been collected early in the morning after overnight fasting. RESULTS The LCN2 levels were significantly higher in MCI patients compared to the healthy control subjects and AD patients [control vs. MCI (p=0.005); MCI vs. AD (p=0.009)]. There was a significant negative correlation between the LCN2 levels and CDR scores (r=-0.245, p=0.014), and there was a positive correlation between the LCN2 levels and MMSE scores (r=0.317, p=0.001) among all of the MCI and AD patients. CONCLUSION MCI represents a prodromal stage of AD, and inflammation occurs as one of the earliest pathological events in AD. Thus, increased plasma LCN2 levels during MCI could be helpful in predicting the progression from MCI to AD.

Plasma level of chitinase 3-like 1 protein increases in patients with early Alzheimer’s disease

Previously, chitinase 3-like 1 (CHI3L1) protein level was increased in various inflammatory conditions and cancers. This study was aimed to evaluate the plasma CHI3L1 level as a potential prognostic biomarker for Alzheimer’s disease (AD). Forty-nine patients with mild cognitive impairment (MCI), 61 patients with mild to severe AD, and 35 healthy elderly controls were recruited for this study. They were given a comprehensive neuropsychological test battery including a mini-mental status examination (MMSE), clinical dementia rating (CDR), and neuropsychiatric inventory (NPI). The CHI3L1 levels were measured using a specific enzyme-linked immunosorbent assay in the plasma and cerebrospinal fluid (CSF). A significant increase in the mean plasma level of CHI3L1 was found in early AD patients compared to control subjects and MCI patients. No significant difference was found between MCI patients and controls. There was a significant positive correlation between CHI3L1 levels and neuropsychological test scores such as CDR and NPI in MCI and early AD patients. Our results demonstrate that CHI3L1 plasma levels are elevated in early AD compared to control or MCI patients. Thus, CHI3L1 plasma levels may be useful as a biomarker, reflecting disease severity in AD patients.