Koon-Chu Yaiw - Academia.edu (original) (raw)

Papers by Koon-Chu Yaiw

Objective-A growing body of evidence indicates that platelets contribute to the onset and progres... more Objective-A growing body of evidence indicates that platelets contribute to the onset and progression of atherosclerosis by modulating immune responses. We aimed to elucidate the effects of oxidized low-density lipoprotein (OxLDL) on platelet-monocyte interactions and the consequences of these interactions on platelet phagocytosis, chemokine release, monocyte extravasation, and foam cell formation. Approach and Results-Confocal microscopy and flow cytometric analysis revealed that in vitro and in vivo stimulation with OxLDL resulted in rapid formation of platelet-monocyte aggregates, with a preference for CD16+ monocyte subsets. This platelet-monocyte interaction facilitated OxLDL uptake by monocytes, in a process that involved platelet CD36-OxLDL interaction, release of chemokines, such as CXC motif ligand 4, direct platelet-monocyte interaction, and phagocytosis of platelets. Inhibition of cyclooxygenase with acetylsalicylic acid and antagonists of ADP receptors, P2Y1 and P2Y12, partly abrogated OxLDL-induced platelet-monocyte aggregates and platelet-mediated lipid uptake in monocytes. Platelets also enhanced OxLDL-induced monocyte transmigration across an endothelial monolayer via direct interaction with monocytes in a transwell assay. Importantly, in LDLR −/− mice, platelet depletion resulted in a significant decrease of peritoneal macrophage recruitment and foam cell formation in a thioglycollate-elicited peritonitis model. In platelet-depleted wild-type mice, transfusion of ex vivo OxLDL-stimulated platelets induced monocyte extravasation to a higher extent when compared with resting platelets. Conclusions-Our results on OxLDL-mediated platelet-monocyte aggregate formation, which promoted phenotypic changes in monocytes, monocyte extravasation and enhanced foam cell formation in vitro and in vivo, provide a novel mechanism for how platelets potentiate key steps of atherosclerotic plaque development and plaque destabilization.

A simple and rapid real-time reverse transcription-PCR (RT-PCR) technique using SYBR green fluore... more A simple and rapid real-time reverse transcription-PCR (RT-PCR) technique using SYBR green fluorescence was developed to quantify Zonula Occludens-1 (ZO-1) mRNA expression in histamine-treated cultured bovine retinal microvessel endothelial cells. There was no dif-ference between the quantity of ZO-1 mRNA expression in histamine-treated (10-7M to 10-9 M) and untreated bovine retinal endothelial cells at high magnesium levels. Immunohisto-chemistry staining and western blot assay unequivocally demonstrated the approximately similar levels of ZO-1 protein in both histamine-treated and non-treated endothelial cells at high magnesium concentrations.

Little is known about the relationship between cerebral beta amyloid (Aβ) deposition and apolipop... more Little is known about the relationship between cerebral beta amyloid (Aβ) deposition and apolipoprotein E (ApoE) genotype in either Alzheimer disease or the aging brain in multi-ethnic Southeast Asia. We prospectively examined Aβ deposition in relation to ApoE genotype in 50 normal, non-demented, aging brains drawn from a Malaysian population, aged 52-92 years, using immunohistochemistry to detect Aβ and direct PCR sequencing for genotyping. The prevalence of Aβ deposition was 8%. There was no apparent association between Aβ deposition and possession of the ApoE e4 allele in our cohort. Out of 4 cases with Aβ deposition, only one case was heterozygous for the e4 allele; 3 cases did not have the e4 allele. The Aβ deposition appears to increase with age and is more likely to be vascular-type deposition (cerebral amyloid angiopathy) rather than parenchymal deposition in the form of diffuse and neuritic plaques. A larger sample size with more cases of ApoE e4 and Aβ deposition is needed...

Tight Junctions (TJs) are areas where adjacent cell membranes join together to form an almost imp... more Tight Junctions (TJs) are areas where adjacent cell membranes join together to form an almost impermeable barrier to fluid. They hold cells together and serve both as protective and functional barriers. The integrity of the tight junction is crucial to restrict the dissemination of microorganisms [1]. Thus, it is conceivable that microbes may target tight junctions during their life cycle. Using Immuno Histo Chemistry (IHC) applied on formalin-fixed, paraffin tissue sections [2]; we have investigated the possible involvement of Zonula Occludens-1 (ZO-1), a 225 kDa tight junction protein, in several different viral infections.

Cells

Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality in immuno... more Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality in immunocompromised patients and a major etiological factor for congenital birth defects in newborns. Ganciclovir and its pro-drug valganciclovir are the preferred drugs in use today for prophylaxis and treatment of viremic patients. Due to long treatment times, patients are at risk for developing viral resistance to ganciclovir and to other drugs with a similar mechanism of action. We earlier found that the endothelin receptor B (ETBR) is upregulated during HCMV infection and that it plays an important role in the life cycle of this virus. Here, we tested the hypothesis that ETBR blockade could be used in the treatment of HCMV infection. As HCMV infection is specific to humans, we tested our hypothesis in human cell types that are relevant for HCMV pathogenesis; i.e., endothelial cells, epithelial cells and fibroblasts. We infected these cells with HCMV and treated them with the ETBR specific a...

Microorganisms

Human cytomegalovirus (HCMV) is an opportunistic pathogen that has been implicated in the pathoge... more Human cytomegalovirus (HCMV) is an opportunistic pathogen that has been implicated in the pathogenesis of atherosclerosis. Endothelin-1 (ET-1), a potent vasoconstrictive peptide, is overexpressed and strongly associated with many vasculopathies. The main objective of this study was to investigate whether HCMV could affect ET-1 production. As such, both endothelial and smooth muscle cells, two primary cell types involved in the pathogenesis of atherosclerosis, were infected with HCMV in vitro and ET-1 mRNA and proteins were assessed by quantitative PCR assay, immunofluorescence staining and ELISA. HCMV infection significantly decreased ET-1 mRNA and secreted bioactive ET-1 levels from both cell types and promoted accumulation of the ET-1 precursor protein in infected endothelial cells. This was associated with inhibition of expression of the endothelin converting enzyme-1 (ECE-1), which cleaves the ET-1 precursor protein to mature ET-1. Ganciclovir treatment did not prevent the virus...

BMC cancer, Feb 6, 2018

Glioblastoma (GBM) is the most common malignant brain tumor with median survival of 12-15 months.... more Glioblastoma (GBM) is the most common malignant brain tumor with median survival of 12-15 months. Owing to uncertainty in clinical outcome, additional prognostic marker(s) apart from existing markers are needed. Since overexpression of endothelin B receptor (ETBR) has been demonstrated in gliomas, we aimed to test whether ETBR is a useful prognostic marker in GBM and examine if the clinically available endothelin receptor antagonists (ERA) could be useful in the disease treatment. Data from The Cancer Genome Atlas and the Gene Expression Omnibus database were analyzed to assess ETBR expression. For survival analysis, glioblastoma samples from 25 Swedish patients were immunostained for ETBR, and the findings were correlated with clinical history. The druggability of ETBR was assessed by protein-protein interaction network analysis. ERAs were analyzed for toxicity in in vitro assays with GBM and breast cancer cells. By bioinformatics analysis, ETBR was found to be upregulated in gliob...

Biomedicines

In the past decade, it was observed that the relationship between the emerging New Molecular Enti... more In the past decade, it was observed that the relationship between the emerging New Molecular Entities and the quantum of R&D investment has not been favorable. There might be numerous reasons but few studies stress the introduction of target based drug discovery approach as one of the factors. Although a number of drugs have been developed with an emphasis on a single protein target, yet identification of valid target is complex. The approach focuses on an in vitro single target, which overlooks the complexity of cell and makes process of validation drug targets uncertain. Thus, it is imperative to search for alternatives rather than looking at success stories of target-based drug discovery. It would be beneficial if the drugs were developed to target multiple components. New approaches like reverse engineering and translational research need to take into account both system and target-based approach. This review evaluates the strengths and limitations of known drug discovery approaches and proposes alternative approaches for increasing efficiency against treatment.

Journal of General Virology

Human cytomegalovirus (HCMV) infection results in the production of virions, dense bodies (DBs) a... more Human cytomegalovirus (HCMV) infection results in the production of virions, dense bodies (DBs) and non-infectious enveloped particles, all of which incorporate proteins and RNAs that can be transferred to host cells. Here, we investigated whether virions and DBs also carry microRNAs (miRNAs) and assessed their delivery and functionality in cells. Human lung fibroblasts (MRC-5) were infected with the HCMV strain AD169, and conditioned cell culture medium was collected and centrifuged. The pellets were treated with RNase-ONE, and the virions and DBs were purified with a potassium tartrate-glycerol gradient and dialysed. The virions and DBs were incubated with micrococcal nuclease, DNA and RNA were extracted and then analysed with TaqMan PCR assays, while the proteins were examined with Western blots. To assess the delivery of miRNAs to cells and their functionality, virions and DBs were irradiated with UV light. The purity of the virions and DBs was confirmed by typical morphology, the presence of the structural protein pp65 and the HCMV genome, the ability to infect MRC-5 cells and the absence of the host genome. RNA analysis revealed the presence of 14 HCMV-encoded miRNAs (UL22A-5p, US25-1-5p, UL22A-3p, US5-2-3p, UL112-3p, US25-2-3p, US25-2-5p, US33-3p, US5-1, UL36-5p, US4-5p, UL36-3p, UL70-5p and US25-1-3p), HCMV immediateearly mRNA and long non-coding RNA2.7, moreover, two host-encoded miRNAs (hsa-miR-218-5p and hsa-miR-21-5p) and beta-2-microglobulin RNA. UV-irradiated virions and DBs delivered viral miRNAs (US25-1-5p and UL112-3p) to the host cells, and miR-US25-1-5p was functional in a luciferase reporter assay. We conclude that virions and DBs carry miRNAs that are biologically functional and can be delivered to cells, which may affect cellular processes.

Open Forum Infectious Diseases, 2015

Background. Both endothelin receptor type B ([ETBR], a G protein-coupled receptor that mediates ... more Background. Both endothelin receptor type B ([ETBR], a G protein-coupled receptor that mediates the vascular effects of the potent vasoconstrictor endothelin-1) and human cytomegalovirus ([HCMV], a ubiquitous herpesvirus) have been implicated in the pathogenesis of cardiovascular disease (CVD). The effects of HCMV infection on ETBR expression are unknown. We hypothesized that HCMV may contribute to the pathogenesis of CVD via ETBR modulation. Methods. Human CMV effects on ETBR were studied in vitro in endothelial cells (ECs) and smooth muscle cells (SMCs) and ex vivo in human carotid plaque tissue specimens. Expression of ETBR and viral immediate-early were quantified using quantitative polymerase chain reaction. Functional consequences after ETBR blockade in ECs were examined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide proliferation, wound healing, tube formation, and flow adhesion assays. Results. Human CMV is capable of upregulating both ETBR mRNA and prot...

Journal of General Virology, 2015

Human cytomegalovirus (hCMV) is a beta herpesvirus that establishes lifelong infection. Although ... more Human cytomegalovirus (hCMV) is a beta herpesvirus that establishes lifelong infection. Although the virus does not usually cause overt clinical symptoms in immunocompetent individuals it can have deleterious effects in immunocompromised patients, such as those on post-transplant medication or with HIV infection. hCMV is the most common congenital infection and can lead to serious fetal sequelae. Endothelial cells (ECs) are natural hosts for hCMV in vivo, therefore, investigations of how this cell type is modulated by infection are key to understanding hCMV pathogenesis. Previous studies have examined the effect of secretomes from hCMV-infected cells on EC angiogenesis, whereas the effect of direct infection on this process has not been so well investigated. Here, we show that placental ECs are viral targets during congenital infection and that vessels in infected tissue appear morphologically abnormal. We demonstrate that the clinical hCMV strain VR1814 impaired EC tube assembly in...

Journal of Clinical Virology, 2015

s / Journal of Clinical Virology 70 (2015) S1–S126 S117 confirmed with recomLine imunoblot test. ... more s / Journal of Clinical Virology 70 (2015) S1–S126 S117 confirmed with recomLine imunoblot test. Corresponding values for Dia.Pro test were 2.5% and 1,1%, respectively. This work is supported by IGA grant NT/13884/2012 of Ministry of Health of the Czech Republic http://dx.doi.org/10.1016/j.jcv.2015.07.270

Herpesviridae, 2013

Background Human cytomegalovirus (HCMV) infection is associated with cardiovascular disease (CVD)... more Background Human cytomegalovirus (HCMV) infection is associated with cardiovascular disease (CVD) but the role of this virus in CVD progression remains unclear. We aimed to examine the HCMV serostatus in Russian patients (n = 90) who had undergone carotid endarterectomy (CEA) and controls (n = 82) as well as to determine the prevalence of HCMV immediate early (IE) and late (LA) antigens in carotid atherosclerotic plaques obtained from 89 patients. In addition, we sought to determine whether HCMV infection was associated with inflammatory activity in the plaque by quantifying infiltrating CD3 and CD68 positive cells and 5-LO immunoreactivity. Methods HCMV serology was assessed with ELISA and immunohistochemistry staining was performed to detect HCMV antigens, CD3, CD68 and 5-LO reactivity. The Fisher’s exact test was used to compare i) seroprevalence of HCMV IgG between patients and controls and ii) HCMV-positive or –negative to that of CD3, CD68 and 5-LO immunoreactive cells in plaq...

Translational Oncology, 2014

BACKGROUND: Brain metastases (BMs) develop by largely unknown mechanisms and cause major morbidit... more BACKGROUND: Brain metastases (BMs) develop by largely unknown mechanisms and cause major morbidity and mortality in patients with solid tumors. Human cytomegalovirus (HCMV) is frequently detected in tumor tissue from patients with different cancers. Here, we aimed to determine the prevalence and potential prognostic role of HCMV in BMs. METHODS: We obtained archived samples of BMs from 41 patients with breast cancer and 37 with colorectal cancer and paired primary tumor tissues from 13 and 12 patients in each respective group. In addition, primary breast cancer tissues from 15 patients were included. HCMV proteins were detected with an immunohistochemical technique and Western blot. HCMV nucleic acids were detected with TaqMan polymerase chain reaction (PCR) assay. RESULTS: HCMV proteins were abundantly expressed in 99% of BM specimens, and in 12 of 13 (92%) paired primary breast cancer specimens. All 12 paired colon cancer samples were positive for HCMV proteins. Protein staining was mainly confined to neoplastic cells. Western blot analysis detected an HCMV-IE reactive protein in 53% of breast cancer specimens, and PCR detected the presence of HCMV DNA and transcripts in 92% and 80% of samples, respectively. Patients with high-level expression of HCMV-IE proteins in their tumors had a shorter time to tumor progression and shorter overall survival. CONCLUSIONS: The prevalence of HCMV proteins and nucleic acids is very www.transonc.com Tr a n s l a t i o n a l O n c o l o g y

Arteriosclerosis, Thrombosis, and Vascular Biology, 2014

Objective— Human cytomegalovirus (HCMV) is a widespread pathogen that correlates with various cli... more Objective— Human cytomegalovirus (HCMV) is a widespread pathogen that correlates with various clinical complications, including atherosclerosis. HCMV is released into the circulation during primary infection and periodic viral reactivation, allowing virus–platelet interactions. Platelets are important in the onset and development of atherosclerosis, but the consequences of platelet–HCMV interactions are unclear. Approach and Results— We studied the effects of HCMV–platelet interactions in blood from healthy donors using the purified clinical HCMV isolate VR1814. We demonstrated that HCMV bound to a Toll-like receptor (TLR) 2–positive platelet subpopulation, which resulted in signal transduction, degranulation, and release of proinflammatory CD40L and interleukin-1β and proangiogenic vascular endothelial–derived growth factor. In mice, murine CMV activated wild-type but not TLR2-deficient platelets. However, supernatant from murine CMV–stimulated wild-type platelets also activated TL...

PLoS ONE, 2014

Background: microRNAs (miRNA) are 18-22 nucleotides long non-coding RNAs that regulate gene expre... more Background: microRNAs (miRNA) are 18-22 nucleotides long non-coding RNAs that regulate gene expression at a post-transcriptional level. Human cytomegalovirus (HCMV) encodes at least 26 known mature miRNAs. hcmv-miR-UL112-3p (miR-UL112-3p) is the most well characterized HCMV miRNA, which is suggested to play role in establishment and maintenance of viral latency. Elevated miR-UL112-3p levels have been reported to be present in plasma of patients with hypertension. Objectives: In this study, we aimed to quantify miR-UL112-3p levels in the plasma/ serum of patients with Diabetes Mellitus (DM; from the DIGAMI-2 cohort), Glioblastoma multiforme (GBM), Rheumatoid Arthritis (RA) and Healthy Controls (HC). Study Design: Total RNA was isolated from plasma/serum samples of 87 patients and controls, a TaqMan miRNA assay was performed to detect miR-UL112-3p and the copy numbers were normalized to 10 ng of total RNA. HCMV IgG and IgM were analysed using ELISA. Results: HCMV miR-UL112-3p was detected in 14/27 (52%) of DM, 5/20 (25%) of GBM, 1/20 (5%) of RA patients and in 2/20 (10%) of HC, respectively. Anti-HCMV IgG was detected in 85%, 65%, 75% of patients and 70% of HC, respectively. Anti-HCMV IgM was found only in one GBM patient of 87 examined patients and controls.

Retrovirology, 2013

Background Emerging evidence suggests that human cytomegalovirus (HCMV) is highly prevalent in tu... more Background Emerging evidence suggests that human cytomegalovirus (HCMV) is highly prevalent in tumours of different origin. This virus is implied to have oncogenic and oncomodulatory functions, through its ability to control host gene expression. Human endogenous retroviruses (HERV) are also frequently active in tumours of different origin, and are supposed to contribute as cofactors to cancer development. Due to the high prevalence of HCMV in several different tumours, and its ability to control host cell gene expression, we sought to define whether HCMV may affect HERV transcription. Findings Infection of 3 established cancer cell lines, 2 primary glioblastoma cells, endothelial cells from 3 donors and monocytes from 4 donors with HCMV (strains VR 1814 or TB40/F) induced reverse transcriptase (RT) activity in all cells tested, but the response varied between donors. Both, gammaretrovirus-related class I elements HERV-T, HERV-W, HERV-F and ERV-9, and betaretrovirus-related class II...

PLoS ONE, 2013

Background: Breast cancer is a leading cause of death among women worldwide. Increasing evidence ... more Background: Breast cancer is a leading cause of death among women worldwide. Increasing evidence implies that human cytomegalovirus (HCMV) infection is associated with several malignancies. We aimed to examine whether HCMV is present in breast cancer and sentinel lymph node (SLN) metastases. Materials and Methods: Formalin-fixed paraffin-embedded tissue specimens from breast cancer and paired sentinel lymph node (SLN) samples were obtained from patients with (n = 35) and without SLN metastasis (n = 38). HCMV immediate early (IE) and late (LA) proteins were detected using a sensitive immunohistochemistry (IHC) technique and HCMV DNA by realtime PCR. Results: HCMV IE and LA proteins were abundantly expressed in 100% of breast cancer specimens. In SLN specimens, 94% of samples with metastases (n = 34) were positive for HCMV IE and LA proteins, mostly confined to neoplastic cells while some inflammatory cells were HCMV positive in 60% of lymph nodes without metastases (n = 35). The presence of HCMV DNA was confirmed in 12/12 (100%) of breast cancer and 10/11 (91%) SLN specimens from the metastatic group, but was not detected in 5/5 HCMV-negative, SLN-negative specimens. There was no statistically significant association between HCMV infection grades and progesterone receptor, estrogen receptor alpha and Elston grade status. Conclusions: The role of HCMV in the pathogenesis of breast cancer is unclear. As HCMV proteins were mainly confined to neoplastic cells in primary breast cancer and SLN samples, our observations raise the question whether HCMV contributes to the tumorigenesis of breast cancer and its metastases.