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Biomedical subjects

Ho Jin Kim

Publications and source records attributed to Ho Jin Kim.

10 recordsLinked to original sources
PubMed2006

Natalizumab effects on immune cell responses in multiple sclerosis.

OBJECTIVE: Our objective was to study in vivo biological effects of natalizumab on immune cell phenotype and function in multiple sclerosis (MS) patients. METHODS: Blood was obtained before and after serial monthly natalizumab infusions to track functional expression of VLA-4 and migratory capacity of immune cells. The impact of infusion on activation thresholds of immune cells was evaluated. RESULTS: Preinfusion VLA-4 expression differed across immune cell subsets. Natalizumab significantly, albeit partially, diminished VLA-4 expression on circulating immune cells. Cell subsets were differentially affected. Treatment significantly decreased migratory capacity of immune cells, correlating well with changes in VLA-4 expression. Effects of a single dose were not saturating and did not persist through the monthly dose interval. Infusion effect varied across patients but was remarkably stable in individual patients, over multiple infusions. Treatment significantly modulated proliferative responses of immune cells. INTERPRETATION: To our knowledge, we provide first proof of concept that natalizumab diminishes migratory capacity of immune cells. Our prospective study further shows that effects of therapy likely (1) differ for distinct immune cell subsets, (2) are not sustained over current dose interval, (3) have unique profiles in individual patients, and (4) include modulation of activation threshold of immune cells. Monitoring these parameters could be relevant to ongoing safety and efficacy considerations.

Antibodies, Monoclonal↗
PubMed2005

Folic acid supplementation can reduce the endothelial damage in rat brain microvasculature due to hyperhomocysteinemia.

To evaluate the effects of dietary folic acid supplementation on the cerebral vascular damage induced by hyperhomocysteinemia, rats were fed a diet containing 3.0 g/kg homocystine for 2 wk and then either 3.0 g/kg homocystine or 3.0 g/kg homocystine plus 0.008 g/kg folic acid for 8 wk. Control rats consumed the AIN-93 Maintenance diet throughout the experiment. The cerebral expression of glucose transporter-1 was measured by Western blot analysis and cerebrovascular structural alterations were evaluated by electron microscopy. The homocystine diet significantly increased the plasma levels of homocysteine and TBARS and decreased the cerebral expression of glucose transporter-1 (GLUT-1) with a concomitant increase in the percentage of damaged cerebral vessels. The inclusion of dietary folic acid for 8 wk caused plasma homocysteine levels to be the same as in control rats and it significantly upregulated the cerebral expression of GLUT-1 that was significantly reduced by hyperhomocysteinemia. Folic acid supplementation also significantly decreased the incidence of damaged vessels due to hyperhomocysteinemia. These results and the electron microscopy findings suggested that folic acid supplementation might reduce the detrimental effects on the endothelium caused by experimentally induced hyperhomocysteinemia.

Animals↗
PubMed2004

Type 2 monocyte and microglia differentiation mediated by glatiramer acetate therapy in patients with multiple sclerosis.

Glatiramer acetate (GA) therapy of patients with multiple sclerosis (MS) represents a unique setting in which in vivo Th2 deviation of T cells is consistently observed and associated with clinical benefit in a human autoimmune disease. We postulated that APCs are important targets of GA therapy and demonstrate that treatment of MS patients with GA reciprocally regulates the IL-10/IL-12 cytokine network of monocytes in vivo. We further show that Th1- or Th2-polarized GA-reactive T cells isolated from untreated or treated MS patients mediate type 1 and 2 APC differentiation of human monocytes, based on their ability to efficiently induce subsequent Th1 and Th2 deviation of naive T cells, respectively. These observations are extended to human microglia, providing the first demonstration of type 2 differentiation of CNS-derived APCs. Finally, we confirm that the fundamental capacity of polarized T cells to reciprocally modulate APC function is not restricted to GA-reactive T cells, thereby defining a novel and dynamic positive feedback loop between human T cell and APC responses. In the context of MS, we propose that GA therapy results in the generation of type 2 APCs, contributing to Th2 deviation both in the periphery and in the CNS of MS patients. In addition to extending insights into the therapeutic mode of action of GA, our findings revisit the concept of bystander suppression and underscore the potential of APCs as attractive targets for therapeutic immune modulation.

Adult↗
PubMed2004

Effects of dietary folic acid supplementation on cerebrovascular endothelial dysfunction in rats with induced hyperhomocysteinemia.

This study shows, for the first time, that hyperhomocysteinemia induces endothelial dysfunction in a rat brain, and that this can be alleviated by dietary folic acid supplementation. Our experiments examined the effects of folic acid supplementation on the endothelial nitric oxide synthase (eNOS) expression in the hyperhomocysteinemic rat brain, and related the observed changes in eNOS expression to the expression of the cell adhesion molecule and the glucose transporter protein. The animals were raised on an experimental diet containing 0.3% homocystine for 2 weeks and then they were placed either on a 0.3% homocystine, 0.3% homocystine with 8 mg/kg folic acid, or folic acid (8 mg/kg) diet for 2 weeks. The cerebrovascular eNOS activity was examined immunohistochemically. Cerebral levels of eNOS, glucose transporter-1 (GLUT-1), and the vascular cell adhesion molecule-1 (VCAM-1) proteins were evaluated by Western blot analysis. At 4 weeks, the homocystine diet induced a fourfold increase in plasma homocysteine (control: 6.5+/-0.4 micromol/l, homocystine: 26.2+/-2.5 micromol/l), and a reduction in the cerebral eNOS and GLUT-1 expression levels with a concomitant increase in the level of VCAM-1 expression. Dietary folic acid supplementation caused a significant decrease in the plasma homocysteine levels, a concomitant increase in the hyperhomocysteinemia-induced reduction in the cerebral eNOS and GLUT-1 expression levels, and a decrease in the hyperhomocysteinemia-induced VCAM-1 expression levels.

Animals↗
PubMed2004

Inflammatory potential and migratory capacities across human brain endothelial cells of distinct glatiramer acetate-reactive T cells generated in treated multiple sclerosis patients.

We asked whether GA-reactive T cells with distinct cytokine profiles (Th2 versus Th1/Th0), induced during GA therapy of multiple sclerosis (MS) patients, have different migratory capacities across human brain endothelial cells (HBECs), and distinct effects on inflammatory responses at the level of the blood-brain barrier (BBB). We confirmed that GA therapy induces a range of GA-reactive T cells defined by distinct profiles of cytokine expression. Supernatants from Th0/Th1 GA-reactive cells significantly upregulated pro-inflammatory chemokine and adhesion molecule expression in HBECs. Post-treatment Th2-polarized GA-reactive cells were significantly less pro-inflammatory but did not suppress the effects induced by Th1 cells. All lines migrated across a HBEC/fibronectin-based model of the BBB with similar efficiencies. We conclude that the spectrum of GA-reactive T cells induced in treated MS patients may differentially impact inflammatory responses at the BBB level. Future studies will determine whether this could contribute to variable clinical response to GA therapy.

Adult↗
PubMed2003

Induction of apoptosis and expression of cell cycle regulatory proteins in response to a phytosphingosine derivative in HaCaT human keratinocyte cells.

Ceramide, a compound derived from sphingomyelin, a sphingolipid precursor, affects cell functions such as growth, differentiation, cell division and apoptosis. We have shown that the phytosphingosine derivative, tetra-acetyl phytosphingosine (TAPS), inhibits the growth of HaCaT cells mainly by inducing apoptosis. In this study, we investigated its effect on the cell cycle and on cell cycle regulatory proteins. We showed by flow cytometry and staining for BrdU and phosphorylated histone H3 that the cells accumulated in S phase and arrested in G2 phase and did not divide before undergoing apoptosis. The level of the pro-apoptotic regulator Bax peaked after 6 h and then returned to normal, whereas the level of the anti-apoptotic regulator Bcl-xL, which is presumably induced in order to inhibit apoptosis, started to increase at 6 h, and remained high for 24 h. Phosphorylation of Cdc2 on Tyr-15 greatly increased while p21 rose to a plateau at 8 h. Levels of p53 and Mad2 proteins were unchanged. Our observations suggest that TAPS induces apoptosis of the HaCaT cells at least in part via transient G2 arrest.

Apoptosis↗
PubMed2003

Analyses of all matrix metalloproteinase members in leukocytes emphasize monocytes as major inflammatory mediators in multiple sclerosis.

Matrix metalloproteinases (MMPs) are implicated in multiple sclerosis where one of their roles may be to facilitate the transmigration of circulating leukocytes into the CNS. Studies have focused on only a few MMPs, and much remains unknown of which of the 23 MMP family members is/are critical to the multiple sclerosis disease process. Using quantitative real time polymerase chain reactions, we have systematically analysed the expression of all 23 MMP members in subsets of leukocytes isolated from the blood of normal individuals. We found a distinctive pattern of MMP expression in different cellular populations: MMP-11, MMP-26 and MMP-27 were enriched in B cells, while MMP-15, MMP-16, MMP-24 and MMP-28 were prominent in T lymphocytes. Of interest is the enrichment of a majority of MMP members in monocytes: MMP-1, MMP-3, MMP-9, MMP-10, MMP-14, MMP-19 and MMP-25. MMP-2 and MMP-17 were also significantly represented in monocytes, although B cells had significant amounts of these MMPs. In correspondence with their strong expression of many MMP members, monocytes migrated more rapidly across a model of the blood-brain barrier in culture than T or B lymphocytes. Finally, we found higher levels of two of the monocyte-expressed MMPs in multiple sclerosis patients compared with normal individuals: MMP-2 and MMP-14. Tissue inhibitor of metalloproteinases (TIMP)-2 was also elevated in monocytes from multiple sclerosis patients, providing a mechanism for the reported activation of MMP-2 by MMP-14 and TIMP-2. These results emphasize that monocytes are prominent contributors of the neuroinflammation in multiple sclerosis through a mechanism that involves their high MMP expression and that they identify specific MMP members as targets for novel therapeutics in the disease.

Adult↗
PubMed2003

Streptococcal intertrigo: an underrecognized condition in children.

Group A beta-hemolytic streptococci have been implicated in a variety of common childhood cutaneous infections. Infants and young children may be particularly susceptible to a form of streptococcal intertrigo that has heretofore been underrecognized in this population. Manifesting as intense, fiery-red erythema and maceration in the intertriginous folds of the neck, axillae, or inguinal spaces, the condition is characterized by a distinctive foul odor and an absence of satellite lesions. Specific clinical features help differentiate this condition from its clinical mimics. Topical and oral antibiotic therapy with or without concomitant low-potency topical steroid application is generally curative.

Diagnosis, Differential↗
PubMed2003

Neurologic complications of human immunodeficiency virus-type 1 infection.

A wide variety of neurologic complications associated with human immunodeficiency virus-type 1 (HIV-1) infection result from HIV-1 itself or secondarily related to immunosuppression. In Korea, the number of HIV-1 seropositive populations is increasing, but little has been known about the neurologic complications of HIV-1 infection. To investigate the neurologic complications in HIV-1 infected Korean patients, we performed a cross-sectional study in consecutive admissions to the Seoul National University Hospital between March 1998 and June 1999. Thirty-four HIV-1 seropositive patients were included. As a result, a total of 26 HIV-1 related neurologic complications were identified from 17 patients. Among them, 10 patients showed cognitive/motor abnormalities: 3 HIV-1-associated dementia and 7 possible HIV-1-associated minor cognitive/motor disorder. Neuromuscular complications were found in 10 patients: 9 distal symmetric polyneuropathy, and 1 possible chronic inflammatory demyelinating polyradiculoneuropathy. In 3 patients with focal brain lesions, 2 were presumptively diagnosed as having primary CNS lymphoma, and 1 as having progressive multifocal leukoencephalopathy in the posterior fossa, based on history, clinical findings, serology, radiological appearances, and response to empirical therapy. Other complications included cryptococcal meningitis and only soft neurologic signs without any neurologic disease. Most of these complications (88%) occurred in the advanced stage of infection.

Adult↗