Biomedical subjects

Bumseok Kim

Publications and source records attributed to Bumseok Kim.

15 recordsLinked to original sources

PubMed2026

Genomic characterization and pathogenicity of ruminant Listeria monocytogenes isolates in a murine oral infection model.

Listeria monocytogenes is a major foodborne pathogen; its ruminant isolates display zoonotic characteristics, causing similar clinical signs in humans, including abortion and encephalitis. However, data on whole genome sequencing and pathogenicity of ruminant L. monocytogenes isolates remain sparse. This study aimed to analyze the genotypic characteristics of L. monocytogenes isolates from ruminants with listeriosis. Furthermore, we assessed the in vivo pathogenicity of four ruminant L. monocytogenes isolates, characterized via whole-genome sequencing-based genetic clustering, in orogastrically inoculated mice. The isolate LM18 (serotype 1/2b, ST224, SL6178) had the lowest lethal dose compared to the other three isolates including previous hypervirulence type (serotype 4b, ST1, SL1) and caused secondary bacteremia in lungs, with sustained bacterial loads in the spleen and liver. Genomic (listeria pathogenicity island -1 and -3) and virulence gene (actA and llsX) mutation analyses associated with virulence suggested from well-recognized studies could not elucidate the virulence of the isolates. SSI-1, which only exists in the isolate LM18 (serotype 1/2b, ST224, SL6178), may help L. monocytogenes survive in the gastrointestinal environment, thereby affecting its virulence. Further research should investigate the role of SSI-1 in the pathogenicity of L. monocytogenes. Moreover, additional studies utilizing larger datasets of ruminant isolates are required to validate our genotypic characterization and to obtain a comprehensive picture of further genotypic differences crucial for L. monocytogenes pathogenicity.

Animals↗

PubMed2006

Depletion of MCP-1 increases development of herpetic stromal keratitis by innate immune modulation.

Chemokines are important chemoattractant inflammatory molecules, but their interdependent network in disease pathogenesis remains unclear. Studies in mouse models have shown that herpetic stromal keratitis (SK) is produced by the consequence of a tissue-destructive immunoinflammatory reaction involving herpes simplex virus type 1 (HSV) infection. Here we found that ocular HSV infection leads to increased expression of monocyte chemoattractant protein-1 (MCP-1), one of the major chemoattractants for immune cells that express CCR2, in the SK cornea. However, MCP-1 is unlikely to be a chemoattractant for infiltrating Gr-1(+), CD11b(+) cells in SK, as these cells are found to be CCR2 negative. Nevertheless, infection of MCP-1(-/-) mice resulted in more severe SK lesion severity compared with WT mice (P<0.01). We demonstrated that the loss of MCP-1 in the SK cornea caused a significant overexpression of macrophage inflammatory protein-2 (MIP-2) (P<0.01) on days 2 and 4 postinfection and increased infiltration of inflammatory cells (Gr-1-high and CD11b(+)) expressing CXCR2, a receptor for MIP-2, into the cornea. Subsequently, increased infiltration of inflammatory cells accelerated by MIP-2 overexpression might result in the high production of inflammatory molecules, including vascular endothelial growth factor (VEGF) and IL-1beta in SK, as well as CpG oligodeoxynucleotide (ODN)-implanted eyes of MCP-1(-/-) mice. These results indicate that MCP-1 in the SK cornea might regulate the expression of other chemokines, as well as the infiltration of inflammatory cells and control development of SK.

Animals↗

PubMed2006

Vascular endothelial growth factor receptor 2-based DNA immunization delays development of herpetic stromal keratitis by antiangiogenic effects.

Stromal keratitis (SK) is an immunoinflammatory eye lesion caused by HSV-1 infection. One essential step in the pathogenesis is neovascularization of the normally avascular cornea, a process that involves the vascular endothelial growth factor (VEGF) family of proteins. In this report, we targeted the proliferating vascular endothelial cells expressing VEGFR-2 in the SK cornea by immunization with recombinant Salmonella typhimurium containing a plasmid encoding murine VEGFR-2. This form of DNA immunization resulted in diminished angiogenesis and delayed development of SK caused by HSV-1 infection and also reduced angiogenesis resulting from corneal implantation with rVEGF. CTL responses against endothelial cells expressing VEGFR-2 were evident in the VEGFR-2-immunized group and in vivo CD8+ T cell depletion resulted in the marked reduction of the antiangiogenic immune response. These results indicate a role for CD8+ T cells in the antiangiogenic effects. Our results may also imply that the anti-VEGFR-2 vaccination approach might prove useful to control pathological ocular angiogenesis and its consequences.

Angiogenesis Inhibitors↗

PubMed2006

Application of FGF-2 to modulate herpetic stromal keratitis.

PURPOSE: Herpetic stromal keratitis (SK) is a tissue destructive eye lesion caused by infection of herpes simplex virus-1 (HSV-1). One step by which HSV-1 enters the cell is through binding to surface heparan sulfate proteoglycans (HSPG), a process that can be inhibited by fibroblast growth factor 2 (FGF-2). The current study examined the effect of FGF-2 application on the outcome of ocular HSV infection. METHODS: Vero cells were infected with HSV-1 after preincubation with FGF-2 protein, and viral infectivity was determined by plaque reduction assay. In an in vivo study, mice were ocularly treated with FGF-2 before (plasmid DNA) or after (recombinant protein) HSV-1 infection, and SK lesion severity was observed. RESULTS: Whereas FGF-2 had excellent antiviral effects in vitro, it was without significant inhibitory effects when given as plasmid DNA encoding FGF-2 (100 microg/application) onto the cornea of the susceptible mouse (BALB/c) before virus infection. Only minor antiviral effects of FGF-2 in vivo were initially observed. Interestingly, topical treatment of recombinant FGF-2 protein (50 ng, two times daily until day 10 postinfection) into HSV-1-infected corneas significantly reduced SK lesion severity and incidence, presumably by promoting epithelial ulcer healing. CONCLUSIONS: These results suggest that treatment of FGF-2 has therapeutic effects on herpetic SK progression via its role in wound healing.

Administration, Topical↗

PubMed2006

Viruses and autoimmunity.

Viruses have been suspected as causes and contributors of human autoimmune diseases (AID), although direct evidence for the association is lacking. However, several animal models provide strong evidence that viruses can induce AIDs as well as act to accelerate and exacerbate lesions in situations where self-tolerance is broken. Many models support the hypothesis by acting as molecular mimics that stimulate self-reactive lymphocytes. Mimicry alone is usually inadequate and with human AID, no compelling evidence supports a role for viruses that are acting as molecular mimics. Alternative mechanisms by which viruses participate in autoimmunity are non-specific, involving a mechanistically poorly understood process termed bystander activation or perhaps viral interference with regulatory cell control systems. This review briefly discusses examples where viruses are involved, taking the view point that molecular mimicry is over emphasized as a critical mechanism during AID pathogenesis.

Animals↗

PubMed2005

Application of plasmid DNA encoding IL-18 diminishes development of herpetic stromal keratitis by antiangiogenic effects.

HSV-1 infection of the eye can cause a blinding immunoinflammatory stromal keratitis (SK) lesion. Using the mouse model, we have demonstrated that angiogenesis is an essential step in lesion pathogenesis because its inhibition results in diminished severity. The molecules involved in causing corneal angiogenesis are multiple and include the vascular endothelial growth factor (VEGF) family of proteins. In this report we show that application of plasmid DNA encoding IL-18 to the cornea of mice before HSV-1 ocular infection resulted in reduced angiogenesis and diminished SK immunoinflammatory lesions. The antiangiogenic effects of IL-18 treatment appeared to be mediated by inhibition of VEGF production in the cornea. We also showed that IL-18 controlled VEGF expression in vitro and also decreased CpG oligodeoxynucleotide induced VEGF-dependent neovascularization. In addition the administration of IL-18-binding protein, an IL-18 antagonist, into the inflammatory eye resulted in elevated angiogenesis and increased VEGF expression. Our results indicate that IL-18 is an important endogenous negative regulator of HSV-induced angiogenesis resulting in reduced SK lesion severity. Our results could mean that IL-18 administration may represent a useful approach to manage unwanted angiogenesis.

Animals↗

PubMed2005

A novel flow cytometry based assay for quantification of corneal angiogenesis in the mouse model of herpetic stromal keratitis.

In this study a novel flow cytometry based quantitative assay for measuring corneal angiogenesis is demonstrated. Corneas of Balb/c mice were lightly scarified and infected with 5 x 10(5), 5 x 10(4) and 5 x 10(3) pfu Herpes simplex virus 1 (HSV-1) RE virus. Development of corneal angiogenesis was studied on day 15 post infection by direct visualisation of infected cornea with a slit-lamp biomicroscope. Endothelial cells constituting the newly developed blood vessels in cornea were stained with murine anti CD31 antibody on frozen corneal sections and corneal whole mounts at day 15 post infection. Total number of endothelial cells was quantified at day 15 post infection by flow cytometry. Mice infected with different doses of HSV-1 RE developed severe to mild corneal angiogenesis at day 15 post infection. Endothelial cells constituting the newly formed blood vessels expressed CD31 at day 15 post infection. Flow cytometry revealed that, the number of CD31 positive cells isolated from diseased corneas increased with the increase in Neovascularisation index. The flow cytometry analysis used in this present study is a useful, accurate and cost effective method for quantifying corneal angiogenesis.

Animals↗

PubMed2005

Viruses and autoimmunity.

Viruses have been suspected as causes and contributors of human autoimmune diseases (AID), although direct evidence for the association is lacking. However, several animal models provide strong evidence that viruses can induce AIDs as well as act to accelerate and exacerbate lesions in situations where self-tolerance is broken. Many models support the hypothesis by acting as molecular mimics that stimulate self-reactive lymphocytes. Mimicry alone is usually inadequate and with human AID, no compelling evidence supports a role for viruses that are acting as molecular mimics. Alternative mechanisms by which viruses participate in autoimmunity are non-specific, involving a mechanistically poorly understood process termed bystander activation or perhaps viral interference with regulatory cell control systems. This review briefly discusses examples where viruses are involved, taking the viewpoint that molecular mimicry is over emphasized as a critical mechanism during AID pathogenesis.

Animals↗

PubMed2005

Blocking mouse MMP-9 production in tumor cells and mouse cornea by short hairpin (sh) RNA encoding plasmids.

In this study, we assessed the efficacy of the specific knockdown of matrix metalloprotein-9 (MMP-9) in vitro and in vivo using short hairpin RNA (shRNA) against MMP-9. Two plasmids were generated encoding shRNA (pshRNA) targeted against two distinct MMP-9 gene sequences. Transfection of these pshMMP-9s could be shown to specifically inhibit MMP-9 expression both in vivo and in vitro. The effect occurred in vitro both in cells that endogenously produce MMP-9 and in cells exogenously transfected with an MMP-9-encoding plasmid. Using an in vivo transfection approach, the pshMMP- 9 was also effective at inhibiting MMP-9 protein expression in the mouse cornea. pshMMP-9s were also tested against herpes simplex virus (HSV) in the cornea. Delivery of the pshMMP-9 stopped angiogenesis and decreased the severity of herpetic keratitis. However, interferon-alpha (IFN-alpha) and IFN- beta induced by pshRNA might also contribute to inhibition of herpetic simplex keratitis (HSK) in the cornea.

Animals↗

PubMed2005

Role of inflammatory cytokine-induced cyclooxygenase 2 in the ocular immunopathologic disease herpetic stromal keratitis.

Ocular infection with herpes simplex virus (HSV) results in a blinding immunoinflammatory stromal keratitis (SK) lesion. Early preclinical events include polymorphonuclear neutrophil (PMN) infiltration and neovascularization in the corneal stroma. We demonstrate here that HSV infection of the cornea results in the upregulation of the cyclooxygenase 2 (COX-2) enzyme. Early after infection, COX-2 was produced from uninfected stromal fibroblasts as an indirect effect of virus infection. Subsequently, COX-2 may also be produced from other inflammatory cells that infiltrate the cornea. The induction of COX-2 is a critical event, since inhibition of COX-2 with a selective inhibitor was shown to reduce corneal angiogenesis and SK severity. The administration of a COX-2 inhibitor resulted in compromised PMN infiltration into the cornea, as well as diminished corneal vascular endothelial growth factor levels, likely accounting for the reduced angiogenic response. COX-2 stimulation by HSV infection represents a critical early event accessible for therapy and the control of SK severity.

Animals↗

PubMed2005

In vivo kinetics of GITR and GITR ligand expression and their functional significance in regulating viral immunopathology.

This report evaluates the role of interaction between glucocorticoid-induced tumor necrosis factor receptor (GITR) and GITR ligand (GITR-L) in the immuno-inflammatory response to infection with herpes simplex virus (HSV). Both GITR and GITR-L were transiently upregulated after ocular HSV infection, on antigen-specific T cells and antigen-presenting cells, respectively, in the draining lymph node (DLN). In addition, virus-specific T-cell responses in the DLN and spleen were enhanced by anti-GITR antibody treatment, an outcome expected to result in more severe inflammatory lesions. Intriguingly, the treatment resulted in significantly diminished T-cell-mediated ocular lesions. The explanation for these findings was that anti-GITR antibody treatment caused a reduced production of ocular MMP-9, a molecule involved in ocular angiogenesis, an essential step in the pathogenesis of herpetic keratitis. Our results are the first observations to determine in vivo kinetics of GITR and GITR-L expression after virus infection, and they emphasize the role of GITR-GITR-L interaction to regulate virus-induced immuno-inflammatory lesions.

Animals↗

PubMed2004

Mice transgenic for IL-1 receptor antagonist protein are resistant to herpetic stromal keratitis: possible role for IL-1 in herpetic stromal keratitis pathogenesis.

Ocular infection with HSV may result in the blinding immunoinflammatory lesion stromal keratitis (SK). This represents a CD4+ T cell-mediated immunopathologic lesion in both humans and a mouse model. Early events in the pathogenesis that set the stage for SK are poorly understood. The present study evaluates the role of IL-1 using a transgenic mouse that overexpresses the IL-1 receptor antagonist (IL-1ra) protein. Such transgenic mice were markedly resistant to SK compared with IL-1ra(-/-) and C57BL/6 control animals. The resistance was shown to be the consequence of reduced expression of molecules such as IL-6, macrophage-inflammatory protein-2, and vascular endothelial growth factor, normally up-regulated directly or indirectly by IL-1. A critical event impaired in IL-1ra transgenic mice was vascular endothelial growth factor production with a consequent marked reduction in angiogenesis, an essential step in SK pathogenesis. Targeting IL-1 could prove to be a worthwhile therapeutic approach to control SK, an important cause of human blindness.

Animals↗

PubMed2004

CXCR2-/- mice show enhanced susceptibility to herpetic stromal keratitis: a role for IL-6-induced neovascularization.

Ocular infection with HSV results in a blinding immunoinflammatory lesion known as herpetic stromal keratitis (HSK). Early preclinical events include inflammatory cell, mainly neutrophils, infiltration of the stroma, and neovascularization. To further evaluate the role of neutrophils in pathogenesis, HSV infection was compared in BALB/c and mice of the same background, but lacking CXCR2, the receptor for chemokines involved in neutrophil recruitment. Our results show clear differences in the outcome of ocular HSV infection in CXCR2-/- compared with control BALB/c mice. Thus, CXCR2-/- animals had minimal PMN influx during the first 7 days postinfection, and this correlated with a longer duration of virus infection in the eye compared with BALB/c mice. The CXCR2-/- mice were also more susceptible to HSV-induced lesions and developed HSK upon exposure to a dose of HSV that was minimally pathogenic to BALB/c mice. The basis for the greater HSK lesion susceptibility of CXCR2-/- mice was associated with an elevated IL-6 response, which appeared in turn to induce the angiogenic factor, vascular endothelial growth factor. Our results serve to further demonstrate the critical role of angiogenesis in the pathogenesis of ocular lesions.

Administration, Topical↗

PubMed2004

Inhibition of ocular angiogenesis by siRNA targeting vascular endothelial growth factor pathway genes: therapeutic strategy for herpetic stromal keratitis.

Ocular neovascularization often results in vision impairment. Frequently vascular endothelial cell growth factors (VEGFs) are mainly responsible for the pathological neovascularization as in the case in neovascularization induced by CpG oligodeoxynucleotides and herpes simplex virus infection in this report. siRNAs targeting either VEGFA, VEGFR1, VEGFR2, or a mix of the three were shown to significantly inhibit neovascularization induced by CpG when given locally or systemically. The efficacy of systemic administration was facilitated by the use of a polymer delivery vehicle. Additional experiments showed a significant inhibitory effect of the siRNAs mix when given either locally or systemically in vehicle against herpes simplex virus-induced angiogenesis as well as against lesions of stromal keratitis. These results indicate that the use of VEGF pathway-specific siRNAs represents a useful therapy against neovascularization-related eye diseases.

Animals↗

PubMed2002

Role of matrix metalloproteinase-9 in angiogenesis caused by ocular infection with herpes simplex virus.

In this report, we demonstrate that herpes simplex virus (HSV) infection of the cornea results in the upregulation of the matrix-degrading metalloproteinase enzyme MMP-9. This enzyme was shown to contribute to the neovascularization process that occurs in the corneal stroma in response to HSV infection. The likely source of MMP-9, at least initially after infection, was neutrophils that were signaled to invade the cornea soon after infection. Corneal infiltrating neutrophils were shown to express MMP-9, and preventing the neutrophil response with specific mAb diminished MMP-9 expression as well as the extent of angiogenesis. Further supporting a role for MMP-9 in HSV-induced corneal angiogenesis was the observation that inhibition of MMP-9 with the specific inhibitor TIMP-1 resulted in reduced angiogenesis. In addition, angiogenesis was diminished in ocularly infected MMP-9 knockout mice. Our results demonstrate that MMP-9 is involved in angiogenesis caused by HSV. Since angiogenesis appears to represent a vital step in the pathogenesis of herpetic stromal keratitis, these results indicate that targeting MMP-9 for inhibition should prove useful for the therapy of herpetic stromal keratitis.

Animals↗