133 results on '"Tan, Rusung"'
Search Results
102. Antigen–specific release of β-chemokines by anti-HIV-1 cytotoxic T lymphocytes
- Author
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Price, David A., primary, Sewell, Andrew K., additional, Dong, Tao, additional, Tan, Rusung, additional, Goulder, Philip J.R., additional, Rowland-Jones, Sarah L., additional, and Phillips, Rodney E., additional
- Published
- 1998
- Full Text
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103. Control of HIV co-receptor expression: Implications for pathogenesis and treatment
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Rowland-Jones, Sarah, primary and Tan, Rusung, additional
- Published
- 1997
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104. Immunology of HIV inflation
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Tan, Rusung, primary
- Published
- 1997
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105. Rapid and Fatal Meningococcal Disease Due to a Strain of Neisseria meningitidis Containing the Capsule Null Locus.
- Author
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Hoang, Linda M. N., Thomas, Eva, Tyler, Sliaun, Pollard, Andrew J., Stephens, Gwen, Gustafson, Larry, McNabb, Alan, Pocock, Ingrid, Tsang, Raymond, and Tan, Rusung
- Subjects
NEISSERIA meningitidis ,PATHOGENIC bacteria ,BACTERIAL diseases ,MEDICAL bacteriology ,CEREBROSPINAL fluid ,IMMUNE serums - Abstract
Background. Neisseria meningitidis continues to be an important cause of invasive bacterial disease among children and young adults worldwide. In Canada, N. meningitidis strains that bear serogroups B and C polysaccharide capsules predominate. We report the first documented case of invasive meningococcal disease in an immunocompetent host caused by an acapsular strain of N. meningitidis containing the capsule null locus (cnl). Methods. Analysis of the isolate was performed with use of serological and molecular methods, including multilocus sequence typing and cnl gene identification. Analysis of 16S ribosomal RNA (rRNA) and porA genes was also performed to confirm the identity of the bacterium. Results. The patient was a healthy, immunocompetent 13-year-old child, and N. meningitidis was recovered from a sample of her cerebrospinal fluid before death. The isolate was nontypeable by both conventional antisera and indirect whole-cell enzyme-linked immuosorbent assay methods using antibodies to serogroups B, C, Y, and W135. The isolate was further identified as a cnl strain, serotype 15 (ST-198). N. meningitidis-specific DNA was identified in the isolate and in the pre- and postmortem specimens by 16S rRNA and porA gene analysis. Conclusions. This is the first reported case of fatal meningococcal disease caused by an acapsular cnl strain of N. meningitidis that was isolated from an immunocompetent host. Routine molecular diagnostic methods targeted at the cnl locus failed to detect this organism, indicating a need to determine the incidence of infection with cnl strains among patients with culture-negative invasive disease. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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106. Identification of a beta-cell-specific HLA class I restricted epitope in type 1 diabetes.
- Author
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Panagiotopoulos, Constadina, Qin, Huilian, Tan, Rusung, and Verchere, C Bruce
- Abstract
Type 1 diabetes is an autoimmune disease in which pancreatic beta-cells are destroyed by cytotoxic T-cells that recognize peptide epitopes presented by HLA class I molecules. The identification of human beta-cell epitopes may significantly improve the prospects for immunodiagnosis and immunotherapy in type 1 diabetes. Using algorithms to predict nonameric beta-cell peptides that would bind to the common HLA allele, HLA-A*0201, we identified a potential epitope from the leader sequence of islet amyloid polypeptide (human islet amyloid polypeptide [IAPP] precursor protein [preproIAPP] 5-13: KLQVFLIVL). Peripheral blood mononuclear cells (PBMCs) were isolated from 18 HLA-A*0201 patients with type 1 diabetes (9 with recent-onset [<180 days; range, 1-120 days] and 9 with long-standing diabetes [>180 days; range, 183-3,273 days]) and 9 healthy, nondiabetic control subjects. PBMCs were screened for peptide recognition using interferon-gamma enzyme-linked immunospot (ELISpot) assays. Of the nine patients with recent-onset type 1 diabetes, six had ELISpot responses to preproIAPP 5-13 that were >3 SDs above the mean of the nondiabetic control subjects (P = 0.002). In contrast, no patients with type 1 diabetes for >180 days had a response above this threshold. In summary, preproIAPP 5-13 is a novel HLA class I epitope recognized by a significant proportion of cytotoxic T-cells from HLA-A*0201 patients with recent-onset type 1 diabetes and may prove to be a useful tool for the prediction and/or prevention of this disease. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
107. Current approaches for the prediction and identification of CD8 T-cell epitopes in type 1 diabetes
- Author
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Standifer, Nathan E, Panagiotopoulos, Constadina, and Tan, Rusung
- Abstract
Type 1 diabetes results from the destruction of β cells by autoreactive T cells that recognize islet-derived peptides. The identification of these β-cell-specific peptides is, therefore, imperative for an understanding of type 1 diabetes pathogenesis. In this review the authors describe current approaches that can be used to identify and characterize these peptides.
- Published
- 2005
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108. Optimal Use of MRSA Select and PCR to Maximize Sensitivity and Specificity of MRSA Detection.
- Author
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Hasan, Mohammad, Brunstein, John, Al-Rawahi, Ghada, Tan, Rusung, Thomas, Eva, and Tilley, Peter
- Subjects
METHICILLIN-resistant staphylococcus aureus ,STAPHYLOCOCCUS aureus ,POLYMERASE chain reaction ,POLYMERIZATION ,DRUG resistance in microorganisms - Abstract
Suspected colonies of methicillin-resistant Staphylococcus aureus (MRSA) on chromogenic, MRSA Select (BioRad) medium were confirmed using routine microbiological methods, and a multiplex real-time PCR ( n = 108). Although the specificity of MRSA Select assessed at 24 h of incubation was much higher than that of 48 h (91.4 vs. 60 %), extending the incubation time to 48 h, along with PCR confirmation, increased the total number of true positive samples by 27.8 %. These results provide a cost effective method for sensitive and specific detection of MRSA. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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109. Su.14. Identification of Hla Class I-Restricted β-Cell Epitopes in Type 1 Diabetes
- Author
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Ouyang, Qin, Panagiotopoulos, Constadina, and Tan, Rusung
- Published
- 2006
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110. Manifestations of X-linked lymphoproliferative disease without prior Epstein-Barr virus exposure
- Author
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Schuster, Volker, Steppberger, Kerstin, Borte, Michael, Tan, Rusung, Dutz, Jan, Benoit, Loralyn, de Sa, Derek, and Junker, Anne
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- 2001
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111. Evaluation of Amplification Targets for the Specific Detection of Bordetella pertussis Using Real-Time Polymerase Chain Reaction
- Author
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Rubayet Hasan, Mohammad, Tan, Rusung, N Al-Rawahi, Ghada, Thomas, Eva, and Tilley, Peter
- Abstract
BACKGROUND: Bordetella pertussis infections continue to be a major public health challenge in Canada. Polymerase chain reaction (PCR) assays to detect B pertussis are typically based on the multicopy insertion sequence IS481, which offers high sensitivity but lacks species specificity.METHODS: A novel B pertussis real-time PCR assay based on the porin gene was tested in parallel with several previously published assays that target genes such as IS481, ptx-promoter, pertactin and a putative thialase. The assays were evaluated using a reference panel of common respiratory bacteria including different Bordetella species and 107 clinical nasopharyngeal specimens. Discrepant results were confirmed by sequencing the PCR products.RESULTS: Analytical sensitivity was highest for the assay targeting the IS481 element; however, the assay lacked specificity for B pertussis in the reference panel and in the clinical samples. False-positive results were also observed with assays targeting the ptx-promoter and pertactin genes. A PCR assay based on the thialase gene was highly specific but failed to detect all reference strains of B pertussis. However, a novel assay targeting the porin gene demonstrated high specificity for B pertussis both in the reference panel and in clinical samples and, based on sequence-confirmed results, correctly predicted all B pertussis-positive cases in clinical samples. According to Probit regression analysis, the 95% detection limit of the new assay was 4 colony forming units/reaction.CONCLUSION: A novel porin assay for B pertussis demonstrated superior performance and may be useful for improved molecular detection of B pertussis in clinical specimens.
- Published
- 2014
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112. The CaV1.4 Calcium Channel Is a Critical Regulator of T Cell Receptor Signaling and Naive T Cell Homeostasis
- Author
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Omilusik, Kyla, Priatel, John J., Chen, Xiaoxi, Wang, Yiwen Teresa, Xu, Hongjian, Choi, Kyung Bok, Gopaul, Rayshad, McIntyre-Smith, Adam, Teh, Hung-Sia, Tan, Rusung, Bech-Hansen, N. Torben, Waterfield, Douglas, Fedida, David, Hunt, Simon V., and Jefferies, Wilfred A.
- Subjects
- *
CALCIUM channels , *INTRACELLULAR calcium , *T cell receptors , *HOMEOSTASIS , *CALCIUM ions , *CELL membranes , *NF-kappa B - Abstract
Summary: The transport of calcium ions (Ca2+) to the cytosol is essential for immunoreceptor signaling, regulating lymphocyte differentiation, activation, and effector function. Increases in cytosolic-free Ca2+ concentrations are thought to be mediated through two interconnected and complementary mechanisms: the release of endoplasmic reticulum Ca2+ “stores” and “store-operated” Ca2+ entry via plasma membrane channels. However, the identity of molecular components conducting Ca2+ currents within developing and mature T cells is unclear. Here, we have demonstrated that the L-type “voltage-dependent” Ca2+ channel CaV1.4 plays a cell-intrinsic role in the function, development, and survival of naive T cells. Plasma membrane CaV1.4 was found to be essential for modulation of intracellular Ca2+ stores and T cell receptor (TCR)-induced rises in cytosolic-free Ca2+, impacting activation of Ras-extracellular signal-regulated kinase (ERK) and nuclear factor of activated T cells (NFAT) pathways. Collectively, these studies revealed that CaV1.4 functions in controlling naive T cell homeostasis and antigen-driven T cell immune responses. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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113. A phase 1b open-label dose-finding study of ustekinumab in young adults with type 1 diabetes.
- Author
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Marwaha AK, Chow S, Pesenacker AM, Cook L, Sun A, Long SA, Yang JHM, Ward-Hartstonge KA, Williams E, Domingo-Vila C, Halani K, Harris KM, Tree TIM, Levings MK, Elliott T, Tan R, and Dutz JP
- Abstract
Objectives: We assessed the safety of ustekinumab (a monoclonal antibody used in psoriasis to target the IL-12 and IL-23 pathways) in a small cohort of recent-onset (<100 days of diagnosis) adults with type 1 diabetes (T1D) by conducting a pilot open-label dose-finding and mechanistic study (NCT02117765) at the University of British Columbia., Methods: We sequentially enrolled 20 participants into four subcutaneous dosing cohorts: (i) 45 mg loading weeks 0/4/16, (ii) 45 mg maintenance weeks 0/4/16/28/40, (iii) 90 mg loading weeks 0/4/16, and (iv) 90 mg maintenance weeks 0/4/16/28/40. The primary endpoint was safety as assessed by an independent data and safety monitoring board (DSMB) but we also measured mixed meal tolerance test C-peptide, insulin use/kg, and HbA1c. Immunophenotyping was performed to assess immune cell subsets and islet antigen-specific T cell responses., Results: Although several adverse events were reported, only two (bacterial vaginosis and hallucinations) were thought to be possibly related to drug administration by the study investigators. At 1 year, the 90 mg maintenance dosing cohort had the smallest mean decline in C-peptide area under the curve (AUC) (0.1 pmol/ml). Immunophenotyping showed that ustekinumab reduced the percentage of circulating Th17, Th1, and Th17.1 cells and proinsulin-specific T cells that secreted IFN-γ and IL-17A., Conclusion: Ustekinumab was deemed safe to progress to efficacy studies by the DSMB at doses used to treat psoriasis in adults with T1D. A 90 mg maintenance dosing schedule reduced proinsulin-specific IFN-γ and IL-17A-producing T cells. Further studies are warranted to determine if ustekinumab can prevent C-peptide AUC decline and induce a clinical response., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Immunology.)
- Published
- 2021
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114. Virome-wide serological profiling reveals association of herpesviruses with obesity.
- Author
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Hasan MR, Rahman M, Khan T, Saeed A, Sundararaju S, Flores A, Hawken P, Rawat A, Elkum N, Hussain K, Tan R, Tang P, and Marr N
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- Adult, Endocrine System metabolism, Endocrine System virology, Female, Herpesviridae genetics, Herpesviridae pathogenicity, Humans, Male, Metabolic Diseases metabolism, Metabolic Diseases virology, Middle Aged, Virology methods, Virome genetics, Obesity metabolism, Obesity virology, Virome physiology
- Abstract
The relationship between viral infection and obesity has been known for several decades but epidemiological data is limited to only a few viral pathogens. The association between obesity and a wide range of viruses was assessed using VirScan, a pan-viral serological profiling tool. Serum specimens from 457 Qatari adults (lean = 184; obese = 273) and 231 Qatari children (lean = 111; obese = 120) were analyzed by VirScan. Associations with obesity were determined by odds ratio (OR) and Fisher's test (p values), and by multivariate regression analysis to adjust for age and gender. Although there was no association of viral infections with obesity in the pediatric population, a nominal association of obesity with seropositivity to members of the Herpesviridae family is observed for the adult population (OR = 1.5-3.3; p < 0.05). After adjusting p values for multiple comparisons (Bonferroni correction) the odds of being obese is significantly higher in herpes simplex virus 1 (HSV-1) seropositive Qatari adults (OR = 3.3; 95% CI 2.15-4.99; p = 2.787E - 08). By VirScan, the sero-prevalence of HSV1 is 81.3% and 57.1% among Qatari obese and lean adult populations, respectively. Higher prevalence of antibodies against several peptide epitopes of HSV-1/2 is positively associated with obesity (OR = 2.35-3.82; p ≤ 3.981E - 05). By multivariate regression analysis, HSV-1 was independently associated with obesity irrespective of age and gender. Our results suggest that obesity among Qataris may be associated with a higher prevalence of herpesvirus infections, in particular HSV-1. Furthermore, the high prevalence of antibodies against peptide antigens specific to HSV-1 and -2 in the obese population suggests that these viral peptides may play a role in adipogenesis. Further studies with these candidate peptides in cell culture or animal models may confirm their adipogenic roles.
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- 2021
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115. A metagenomics-based diagnostic approach for central nervous system infections in hospital acute care setting.
- Author
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Hasan MR, Sundararaju S, Tang P, Tsui KM, Lopez AP, Janahi M, Tan R, and Tilley P
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- Adolescent, Central Nervous System Infections cerebrospinal fluid, Central Nervous System Infections microbiology, Child, Child, Preschool, Computational Biology, DNA, Bacterial genetics, DNA, Bacterial isolation & purification, DNA, Viral genetics, DNA, Viral isolation & purification, Datasets as Topic, Feasibility Studies, Female, High-Throughput Nucleotide Sequencing, Hospitals, Humans, Infant, Infant, Newborn, Male, Retrospective Studies, Sensitivity and Specificity, Sequence Analysis, DNA, Young Adult, Central Nervous System Infections diagnosis, Cerebrospinal Fluid microbiology, Metagenome, Metagenomics methods
- Abstract
The etiology of central nervous system (CNS) infections such as meningitis and encephalitis remains unknown in a large proportion of cases partly because the diversity of pathogens that may cause CNS infections greatly outnumber available test methods. We developed a metagenomic next generation sequencing (mNGS)-based approach for broad-range detection of pathogens associated with CNS infections suitable for application in the acute care hospital setting. The analytical sensitivity of mNGS performed on an Illumina MiSeq was assessed using simulated cerebrospinal fluid (CSF) specimens (n = 9). mNGS data were then used as a training dataset to optimize a bioinformatics workflow based on the IDseq pipeline. For clinical validation, residual CSF specimens (n = 74) from patients with suspected CNS infections previously tested by culture and/or PCR, were analyzed by mNGS. In simulated specimens, the NGS reads aligned to pathogen genomes in IDseq were correlated to qPCR C
T values for the respective pathogens (R = 0.96; p < 0.0001), and the results were highly specific for the spiked pathogens. In clinical samples, the diagnostic accuracy, sensitivity and specificity of the mNGS with reference to conventional methods were 100%, 95% and 96%, respectively. The clinical application of mNGS holds promise to benefit patients with CNS infections of unknown etiology.- Published
- 2020
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116. Unusual accumulation of a wide array of antimicrobial resistance mechanisms in a patient with cytomegalovirus-associated hemophagocytic lymphohistiocytosis: a case report.
- Author
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Hasan MR, Sundaram MS, Sundararaju S, Tsui KM, Karim MY, Roscoe D, Imam O, Janahi MA, Thomas E, Dobson S, Tan R, Tang P, and Lopez AP
- Subjects
- Anti-Bacterial Agents adverse effects, Anti-Bacterial Agents therapeutic use, Antiviral Agents adverse effects, Antiviral Agents therapeutic use, Carbapenem-Resistant Enterobacteriaceae drug effects, Carbapenem-Resistant Enterobacteriaceae genetics, Child, Cytomegalovirus genetics, Cytomegalovirus immunology, Cytomegalovirus Infections diagnosis, Cytomegalovirus Infections drug therapy, Cytomegalovirus Infections virology, Fatal Outcome, Ganciclovir adverse effects, Ganciclovir therapeutic use, Genotype, Humans, Lymphohistiocytosis, Hemophagocytic diagnosis, Lymphohistiocytosis, Hemophagocytic drug therapy, Male, Sepsis drug therapy, Sepsis microbiology, Vancomycin-Resistant Enterococci drug effects, Vancomycin-Resistant Enterococci genetics, Cytomegalovirus drug effects, Cytomegalovirus Infections complications, Drug Resistance, Multiple, Bacterial genetics, Drug Resistance, Multiple, Viral, Lymphohistiocytosis, Hemophagocytic virology, Sepsis mortality
- Abstract
Background: Infections with multidrug-resistant organisms (MDRO) pose a serious threat to patients with dysregulated immunity such as in hemophagocytic lymphohistiocytosis (HLH), but such infections have rarely been comprehensively characterized. Here, we present a fatal case of HLH secondary to cytomegalovirus (CMV) infection complicated by both anti-viral drug resistance and sepsis from multiple MDROs including pandrug-resistant superbug bacteria., Case Presentation: A previously healthy, six-year-old boy presented with a 45-day history of fever prior to a diagnosis of hemophagocytic lymphohistiocytosis and hemorrhagic colitis, both associated with CMV. On hospital admission, the patient was found to be colonized with multiple, multidrug-resistant (MDR) bacteria including vancomycin-resistant enterococci (VRE) and carbapenamase-producing organisms (CPO). He eventually developed respiratory, urine and bloodstream infections with highly drug-resistant, including pandrug-resistant bacteria, which could not be controlled by antibiotic treatment. Antiviral therapy also failed to contain his CMV infection and the patient succumbed to overwhelming bacterial and viral infection. Whole genome sequencing (WGS) of the MDR bacteria and metagenomic analysis of his blood sample revealed an unusual accumulation of a wide range of antimicrobial resistance mechanisms in a single patient, including antiviral resistance to ganciclovir, and resistance mechanisms to all currently available antibiotics., Conclusions: The case highlights both the risk of acquiring MDR superbugs and the severity of these infections in HLH patients.
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- 2020
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117. A novel real-time PCR assay panel for detection of common respiratory pathogens in a convenient, strip-tube array format.
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Hasan MR, Al Mana H, Young V, Tang P, Thomas E, Tan R, and Tilley P
- Subjects
- Costs and Cost Analysis, Multiplex Polymerase Chain Reaction methods, Sensitivity and Specificity, Molecular Diagnostic Techniques methods, Real-Time Polymerase Chain Reaction methods, Respiratory Tract Infections diagnosis
- Abstract
Commercial multiplex assays, built on different chemistries and platforms are widely available for simultaneous detection of pathogens that cause respiratory infections. However, these tests are often difficult to implement in a resource limited setting because of high cost. In this study, we developed and validated a method for simultaneous testing of common respiratory pathogens (Respanel) by real-time PCR in a convenient, strip-tube array format. Primers and probes for sixteen PCR assays were selected from the literature or newly designed. Following optimization of individual PCR assays, strip-tube arrays were prepared by dispensing primer-probe mixes (PPM) into two sets of 8-tube strips. Nucleic acid extracts from specimens were mixed with PCR master mix, and dispensed column-wise into 2 × 8-wells of a 96-well plate. PPMs from strip-tubes were then added to the wells using a multichannel pipette for real-time PCR. Individual PCR assays were optimized using previously known specimens (n = 394) with 91%-100% concordance with culture, DFA or PCR results. Respanel was then tested in a routine manner at two different sites using specimens (n = 147) previously tested by Qiagen Resplex I&II or Fast-Track Diagnostics Respiratory Pathogens 21 assays. The sensitivity, specificity and accuracy of Respanel were 94%, 95% and 95%, respectively, against Resplex and 88%, 100% and 99%, respectively, against FTDRP21. Respanel detected more pathogens (p < 0.05) than Resplex but the rate of pathogen detection was not significantly different from FTDRP21. Respanel is a convenient and inexpensive assay that is more sensitive than Resplex and comparable to FTDRP21 for the detection of common respiratory pathogens., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2019
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118. Comparative evaluation of laboratory developed real-time PCR assays and RealStar(®) BKV PCR Kit for quantitative detection of BK polyomavirus.
- Author
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Hasan MR, Tan R, Al-Rawahi G, Thomas E, and Tilley P
- Subjects
- Antigens, Viral, Tumor genetics, BK Virus genetics, Capsid Proteins genetics, DNA Primers, DNA, Viral blood, Genome, Viral, Humans, Kidney Diseases diagnosis, Kidney Diseases virology, Limit of Detection, Nucleic Acids genetics, Polyomavirus Infections virology, Reagent Kits, Diagnostic economics, BK Virus isolation & purification, Polyomavirus Infections diagnosis, Real-Time Polymerase Chain Reaction economics, Real-Time Polymerase Chain Reaction methods, Viral Load
- Abstract
Background: Quantitative, viral load monitoring for BK virus (BKV) by real-time PCR is an important tool in the management of polyomavirus associated nephropathy in renal transplant patients. However, variability in PCR results has been reported because of polymorphisms in viral genes among different subtypes of BKV, and lack of standardization of the PCR assays among different laboratories. In this study we have compared the performance of several laboratory developed PCR assays that target highly conserved regions of BKV genome with a commercially available, RealStar(®) BKV PCR Kit., Method: Three real-time PCR assays (i) VP1 assay: selected from the literature that targets the major capsid protein (VP1) gene (ii) VP1MOD assay: VP1 assay with a modified probe, and (iii) BKLTA assay: newly designed assay that targets the large T antigen gene were assessed in parallel, using controls and clinical specimens that were previously tested using RealStar(®) BKV PCR Kit (Altona Diagnostics GmbH, Hamburg, Germany). Nucleic acid from all samples were extracted using the QIA symphony virus/bacteria kit on an automated DNA extraction platform QIA symphony SP (Qiagen). Primer and probe concentration, and reaction conditions for laboratory developed assays were optimized and the limit of detection of different assays was determined. Positive control for laboratory developed BK assays was prepared through construction of a plasmid carrying respective amplicon sequences., Results: The 95% detection limit of VP1, VP1MOD and BKLTA assays were 1.8×10(2), 3×10(3) and 3.5×10(2) genomic copies/ml, respectively, as determined by Probit regression analysis of data obtained by testing a dilution series of a titered patient specimen, using RealStar(®) BKV PCR Kit. The inter-assay and intra-assay, coefficient of variations of these assays using calibrated, plasmid standards were <1%. All assays, including the RealStar(®) BKV PCR assay, were highly specific when tested against a panel of external proficiency specimens containing both BK and JC viruses. All assays, except the VP1MOD assay determined BK viral load in proficiency specimens within the same log values. With reference to results obtained by RealStar(®) BKV PCR assay, the sensitivity and specificity of different assays tested in 116 serum specimens submitted for BK viral load assay were 91% and 97% for VP1 assay, 88% and 97% for VP1MOD assay, and 97% and 98% for BKLTA assay, respectively. BK Viral load in positive specimens determined by various assays was highly correlated (R(2)>0.97), based on linear regression analysis., Conclusions: The performance characteristics of the newly designed, BKLTA assay were highly comparable to RealStar(®) BKV PCR assay, and can be used for routine detection and viral load monitoring of BKV in a cost-effective manner., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2016
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119. T regulatory cell chemokine production mediates pathogenic T cell attraction and suppression.
- Author
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Patterson SJ, Pesenacker AM, Wang AY, Gillies J, Mojibian M, Morishita K, Tan R, Kieffer TJ, Verchere CB, Panagiotopoulos C, and Levings MK
- Subjects
- Adolescent, Adoptive Transfer, Animals, Cell Proliferation, Cells, Cultured, Chemokine CCL3 metabolism, Chemokine CCL4 metabolism, Chemotaxis, Leukocyte, Child, Child, Preschool, Diabetes Mellitus, Experimental immunology, Diabetes Mellitus, Experimental metabolism, Diabetes Mellitus, Type 1 immunology, Encephalomyelitis, Autoimmune, Experimental immunology, Encephalomyelitis, Autoimmune, Experimental therapy, Female, Humans, Infant, Male, Mice, Inbred BALB C, Mice, Inbred C57BL, Mice, Transgenic, Receptors, CCR5 physiology, Chemokine CCL3 biosynthesis, Chemokine CCL4 biosynthesis, T-Lymphocytes, Regulatory physiology
- Abstract
T regulatory cells (Tregs) control immune homeostasis by preventing inappropriate responses to self and nonharmful foreign antigens. Tregs use multiple mechanisms to control immune responses, all of which require these cells to be near their targets of suppression; however, it is not known how Treg-to-target proximity is controlled. Here, we found that Tregs attract CD4+ and CD8+ T cells by producing chemokines. Specifically, Tregs produced both CCL3 and CCL4 in response to stimulation, and production of these chemokines was critical for migration of target T cells, as Tregs from Ccl3-/- mice, which are also deficient for CCL4 production, did not promote migration. Moreover, CCR5 expression by target T cells was required for migration of these cells to supernatants conditioned by Tregs. Tregs deficient for expression of CCL3 and CCL4 were impaired in their ability to suppress experimental autoimmune encephalomyelitis or islet allograft rejection in murine models. Moreover, Tregs from subjects with established type 1 diabetes were impaired in their ability to produce CCL3 and CCL4. Together, these results demonstrate a previously unappreciated facet of Treg function and suggest that chemokine secretion by Tregs is a fundamental aspect of their therapeutic effect in autoimmunity and transplantation.
- Published
- 2016
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120. Multiple sclerosis-associated CLEC16A controls HLA class II expression via late endosome biogenesis.
- Author
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van Luijn MM, Kreft KL, Jongsma ML, Mes SW, Wierenga-Wolf AF, van Meurs M, Melief MJ, der Kant Rv, Janssen L, Janssen H, Tan R, Priatel JJ, Neefjes J, Laman JD, and Hintzen RQ
- Subjects
- Adaptor Proteins, Signal Transducing metabolism, Adolescent, Adult, Aged, Antigen-Presenting Cells drug effects, Antigen-Presenting Cells metabolism, Case-Control Studies, Cells, Cultured, Dendritic Cells drug effects, Dendritic Cells metabolism, Female, Gene Knockdown Techniques, Humans, Lectins, C-Type genetics, Leukocytes, Mononuclear drug effects, Leukocytes, Mononuclear metabolism, Leukocytes, Mononuclear ultrastructure, Male, Middle Aged, Monosaccharide Transport Proteins genetics, Protein Transport genetics, RNA, Small Interfering pharmacology, Up-Regulation drug effects, Vitamin D pharmacology, White Matter metabolism, Young Adult, Endosomes metabolism, Genetic Predisposition to Disease genetics, Histocompatibility Antigens Class II biosynthesis, Lectins, C-Type physiology, Monosaccharide Transport Proteins physiology, Multiple Sclerosis genetics
- Abstract
C-type lectins are key players in immune regulation by driving distinct functions of antigen-presenting cells. The C-type lectin CLEC16A gene is located at 16p13, a susceptibility locus for several autoimmune diseases, including multiple sclerosis. However, the function of this gene and its potential contribution to these diseases in humans are poorly understood. In this study, we found a strong upregulation of CLEC16A expression in the white matter of multiple sclerosis patients (n = 14) compared to non-demented controls (n = 11), mainly in perivascular leukocyte infiltrates. Moreover, CLEC16A levels were significantly enhanced in peripheral blood mononuclear cells of multiple sclerosis patients (n = 69) versus healthy controls (n = 46). In peripheral blood mononuclear cells, CLEC16A was most abundant in monocyte-derived dendritic cells, in which it strongly co-localized with human leukocyte antigen class II. Treatment of these professional antigen-presenting cells with vitamin D, a key protective environmental factor in multiple sclerosis, downmodulated CLEC16A in parallel with human leukocyte antigen class II. Knockdown of CLEC16A in distinct types of model and primary antigen-presenting cells resulted in severely impaired cytoplasmic distribution and formation of human leucocyte antigen class II-positive late endosomes, as determined by immunofluorescence and electron microscopy. Mechanistically, CLEC16A participated in the molecular machinery of human leukocyte antigen class II-positive late endosome formation and trafficking to perinuclear regions, involving the dynein motor complex. By performing co-immunoprecipitations, we found that CLEC16A directly binds to two critical members of this complex, RILP and the HOPS complex. CLEC16A silencing in antigen-presenting cells disturbed RILP-mediated recruitment of human leukocyte antigen class II-positive late endosomes to perinuclear regions. Together, we identify CLEC16A as a pivotal gene in multiple sclerosis that serves as a direct regulator of the human leukocyte antigen class II pathway in antigen-presenting cells. These findings are a first step in coupling multiple sclerosis-associated genes to the regulation of the strongest genetic factor in multiple sclerosis, human leukocyte antigen class II., (© The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2015
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121. Evaluation of amplification targets for the specific detection of Bordetella pertussis using real-time polymerase chain reaction.
- Author
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Hasan MR, Tan R, Al-Rawahi GN, Thomas E, and Tilley P
- Abstract
Background: Bordetella pertussis infections continue to be a major public health challenge in Canada. Polymerase chain reaction (PCR) assays to detect B pertussis are typically based on the multicopy insertion sequence IS481, which offers high sensitivity but lacks species specificity., Methods: A novel B pertussis real-time PCR assay based on the porin gene was tested in parallel with several previously published assays that target genes such as IS481, ptx-promoter, pertactin and a putative thialase. The assays were evaluated using a reference panel of common respiratory bacteria including different Bordetella species and 107 clinical nasopharyngeal specimens. Discrepant results were confirmed by sequencing the PCR products., Results: Analytical sensitivity was highest for the assay targeting the IS481 element; however, the assay lacked specificity for B pertussis in the reference panel and in the clinical samples. False-positive results were also observed with assays targeting the ptx-promoter and pertactin genes. A PCR assay based on the thialase gene was highly specific but failed to detect all reference strains of B pertussis. However, a novel assay targeting the porin gene demonstrated high specificity for B pertussis both in the reference panel and in clinical samples and, based on sequence-confirmed results, correctly predicted all B pertussis-positive cases in clinical samples. According to Probit regression analysis, the 95% detection limit of the new assay was 4 colony forming units/reaction., Conclusion: A novel porin assay for B pertussis demonstrated superior performance and may be useful for improved molecular detection of B pertussis in clinical specimens.
- Published
- 2014
- Full Text
- View/download PDF
122. Innate immune control of EBV-infected B cells by invariant natural killer T cells.
- Author
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Chung BK, Tsai K, Allan LL, Zheng DJ, Nie JC, Biggs CM, Hasan MR, Kozak FK, van den Elzen P, Priatel JJ, and Tan R
- Subjects
- Antigens, CD1d immunology, Antigens, CD1d metabolism, B-Lymphocytes virology, Cell Communication immunology, Cell Transformation, Neoplastic immunology, Epstein-Barr Virus Infections complications, Humans, Immunity, Innate immunology, Lymphoid Enhancer-Binding Factor 1 immunology, Lymphoid Enhancer-Binding Factor 1 metabolism, Lymphoproliferative Disorders virology, Natural Killer T-Cells metabolism, Natural Killer T-Cells virology, Palatine Tonsil immunology, Palatine Tonsil virology, B-Lymphocytes immunology, Epstein-Barr Virus Infections immunology, Herpesvirus 4, Human immunology, Lymphoproliferative Disorders immunology, Natural Killer T-Cells immunology
- Abstract
Individuals with X-linked lymphoproliferative disease lack invariant natural killer T (iNKT) cells and are exquisitely susceptible to Epstein-Barr virus (EBV) infection. To determine whether iNKT cells recognize or regulate EBV, resting B cells were infected with EBV in the presence or absence of iNKT cells. The depletion of iNKT cells increased both viral titers and the frequency of EBV-infected B cells. However, EBV-infected B cells rapidly lost expression of the iNKT cell receptor ligand CD1d, abrogating iNKT cell recognition. To determine whether induced CD1d expression could restore iNKT recognition in EBV-infected cells, lymphoblastoid cell lines (LCL) were treated with AM580, a synthetic retinoic acid receptor-α agonist that upregulates CD1d expression via the nuclear protein, lymphoid enhancer-binding factor 1 (LEF-1). AM580 significantly reduced LEF-1 association at the CD1d promoter region, induced CD1d expression on LCL, and restored iNKT recognition of LCL. CD1d-expressing LCL elicited interferon γ secretion and cytotoxicity by iNKT cells even in the absence of exogenous antigen, suggesting an endogenous iNKT antigen is expressed during EBV infection. These data indicate that iNKT cells may be important for early, innate control of B cell infection by EBV and that downregulation of CD1d may allow EBV to circumvent iNKT cell-mediated immune recognition.
- Published
- 2013
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123. RasGRP1 regulates antigen-induced developmental programming by naive CD8 T cells.
- Author
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Priatel JJ, Chen X, Huang YH, Chow MT, Zenewicz LA, Coughlin JJ, Shen H, Stone JC, Tan R, and Teh HS
- Subjects
- Animals, Cell Differentiation immunology, Cell Proliferation, Guanine Nucleotide Exchange Factors deficiency, Guanine Nucleotide Exchange Factors immunology, Interleukin-2 pharmacology, Lymphocyte Activation immunology, Mice, Mice, Knockout, Signal Transduction immunology, Transgenes, Antigens immunology, CD8-Positive T-Lymphocytes immunology, Guanine Nucleotide Exchange Factors physiology
- Abstract
Ag encounter by naive CD8 T cells initiates a developmental program consisting of cellular proliferation, changes in gene expression, and the formation of effector and memory T cells. The strength and duration of TCR signaling are known to be important parameters regulating the differentiation of naive CD8 T cells, although the molecular signals arbitrating these processes remain poorly defined. The Ras-guanyl nucleotide exchange factor RasGRP1 has been shown to transduce TCR-mediated signals critically required for the maturation of developing thymocytes. To elucidate the role of RasGRP1 in CD8 T cell differentiation, in vitro and in vivo experiments were performed with 2C TCR transgenic CD8 T cells lacking RasGRP1. In this study, we report that RasGRP1 regulates the threshold of T cell activation and Ag-induced expansion, at least in part, through the regulation of IL-2 production. Moreover, RasGRP1(-/-) 2C CD8 T cells exhibit an anergic phenotype in response to cognate Ag stimulation that is partially reversible upon the addition of exogenous IL-2. By contrast, the capacity of IL-2/IL-2R interactions to mediate Ras activation and CD8 T cell expansion and differentiation appears to be largely RasGRP1-independent. Collectively, our results demonstrate that RasGRP1 plays a selective role in T cell signaling, controlling the initiation and duration of CD8 T cell immune responses.
- Published
- 2010
- Full Text
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124. Apolipoprotein-mediated lipid antigen presentation in B cells provides a pathway for innate help by NKT cells.
- Author
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Allan LL, Hoefl K, Zheng DJ, Chung BK, Kozak FK, Tan R, and van den Elzen P
- Subjects
- Antigen Presentation drug effects, Apolipoproteins E immunology, B-Lymphocytes drug effects, Cells, Cultured, Flow Cytometry, Galactosylceramides pharmacology, Humans, Lymphocyte Activation drug effects, Natural Killer T-Cells drug effects, Receptors, LDL metabolism, Signal Transduction, Antigen Presentation immunology, Antigens, CD1d immunology, Apolipoproteins E metabolism, B-Lymphocytes immunology, Natural Killer T-Cells immunology
- Abstract
Natural killer T (NKT) cells are innate-like lymphocytes that recognize lipid antigens and have been shown to enhance B-cell activation and antibody production. B cells typically recruit T-cell help by presenting internalized antigens recognized by their surface antigen receptor. Here, we demonstrate a highly efficient means whereby human B cells present lipid antigens to NKT cells, capturing the antigen using apolipoprotein E (apoE) and the low-density lipoprotein receptor (LDL-R). ApoE dramatically enhances B-cell presentation of alpha-galactosylceramide (alphaGalCer), an exogenous CD1d presented antigen, inducing activation of NKT cells and the subsequent activation of B cells. B cells express the LDL-R on activation, and the activation of NKT cells by B cells is completely LDL-R dependent, as shown by blocking experiments and the complete lack of presentation when using apoE2, an isoform of apoE incapable of LDL-R binding. The dependence on apoE and the LDL-R is much more pronounced in B cells than we had previously seen in dendritic cells, which can apparently use alternate pathways of lipid antigen uptake. Thus, B cells use an apolipoprotein-mediated pathway of lipid antigen presentation, which constitutes a form of innate help for B cells by NKT cells.
- Published
- 2009
- Full Text
- View/download PDF
125. IFN-gamma-mediated extravillous trophoblast outgrowth inhibition in first trimester explant culture: a role for insulin-like growth factors.
- Author
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Hu Y, Tan R, MacCalman CD, Eastabrook G, Park SH, Dutz JP, and von Dadelszen P
- Subjects
- Apoptosis drug effects, Apoptosis genetics, Cell Movement drug effects, Cell Surface Extensions drug effects, Cell Surface Extensions physiology, Cells, Cultured, Chorionic Villi metabolism, Chorionic Villi physiology, Down-Regulation drug effects, Down-Regulation physiology, Female, Humans, Insulin-Like Growth Factor Binding Proteins genetics, Insulin-Like Growth Factor Binding Proteins metabolism, Insulin-Like Growth Factor I genetics, Insulin-Like Growth Factor I metabolism, Insulin-Like Growth Factor I physiology, Insulin-Like Growth Factor II genetics, Insulin-Like Growth Factor II metabolism, Insulin-Like Growth Factor II physiology, Integrins genetics, Integrins metabolism, Organ Culture Techniques, Pregnancy, Pregnancy Trimester, First genetics, Pregnancy Trimester, First metabolism, Receptor, IGF Type 1 genetics, Receptor, IGF Type 1 metabolism, Receptor, IGF Type 2 genetics, Receptor, IGF Type 2 metabolism, Somatomedins genetics, Somatomedins metabolism, Trophoblasts metabolism, Trophoblasts physiology, Chorionic Villi drug effects, Interferon-gamma pharmacology, Pregnancy Trimester, First drug effects, Somatomedins physiology, Trophoblasts drug effects
- Abstract
Pre-eclampsia is often associated with inadequate cytotrophoblast invasion and remodelling of the uterine spiral arteries. Examining a first trimester, 2D in vitro explant culture model which mimics in vivo placentation, including trophoblast column formation and extravillous cytotrophoblast (EVT) migration, we previously suggested that excessive maternal decidual natural killer cell interferon (IFN-gamma) limits EVT migration. Types-1 and -2 insulin-like growth factor (IGF-1, IGF-2) are trophic for EVT, act through their surface receptors, IGFR-1 and IGFR-2, and are regulated by the IGF-binding proteins (IGFBPs). Could the observed IFN-gamma-mediated inhibition of EVT outgrowth and migration be related to either expression changes of IGF-1 or IGF-2, their receptors, their binding proteins, or apoptosis? Using the 2D explant culture model, we examined the effect of IFN-gamma exposure on IGF-1 and -2, IGFR-1 and -2, IGFBPs and apoptosis. IFN-gamma relatively increased IGF-1 and -2 secretion. In EVT, IFN-gamma decreased IGFR-2, but not IGFR-1 expression. IGBP-2, -3 and -4 production were not influenced by IFN-gamma. IFN-gamma induced trophoblast apoptosis measured by the highly sensitive M30 neo-epitope, but not caspase 3 activity, in conditioned medium and EVT cell lysates. The observed IFN-gamma-mediated EVT migration inhibition may occur through the down-regulation of IGFR-2 and subtle induction of EVT apoptosis.
- Published
- 2008
- Full Text
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126. Critical role for IFN-gamma in natural killer cell-mediated protection from diabetes.
- Author
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Lee IF, Qin H, Priatel JJ, and Tan R
- Subjects
- Adoptive Transfer, Animals, Cytotoxicity, Immunologic, Diabetes Mellitus, Type 1 prevention & control, Female, Flow Cytometry, Interferon-gamma metabolism, Killer Cells, Natural drug effects, Killer Cells, Natural metabolism, Mice, Mice, Inbred NOD, Mice, Knockout, Reverse Transcriptase Polymerase Chain Reaction, Spleen cytology, Spleen immunology, Adjuvants, Immunologic pharmacology, Diabetes Mellitus, Type 1 immunology, Freund's Adjuvant pharmacology, Interferon-gamma immunology, Killer Cells, Natural immunology
- Abstract
Autoimmune diabetes in nonobese diabetic (NOD) mice can be prevented by a single injection of complete Freund's adjuvant (CFA), but the mechanisms mediating protection remains unclear. We previously showed that NOD mice immunized with CFA have a markedly reduced incidence of diabetes that is associated with a significant decrease in the number of beta-cell-specific, autoreactive cytotoxic T lymphocytes and, furthermore, that the effect of CFA is mediated by natural killer (NK) cells. In this study, we report one mechanism by which NK cells regulate the onset of diabetes. Administration of CFA produced a rapid increase in NK cell frequency and function, including cytotoxicity and IFN-gamma secretion. By co-transferring NK cells from IFN-gamma-deficient (or wild-type) NOD mice and spleen cells from diabetic NOD mice to NOD/SCID recipients, we show that IFN-gamma secretion by NK cells significantly influences the effect of CFA protection. In contrast, NK cytotoxicity does not appear to participate in CFA-mediated protection from diabetes. Our findings demonstrate that NK cells mediate the protective effects of CFA through secretion of IFN-gamma.
- Published
- 2008
- Full Text
- View/download PDF
127. Xenogeneic beta 2-microglobulin substitution affects functional binding of MHC class I molecules by CD8+ T cells.
- Author
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Benoit LA and Tan R
- Subjects
- Amino Acid Substitution immunology, Animals, Antigen Presentation genetics, Antigens, Heterophile chemistry, Egg Proteins immunology, Egg Proteins metabolism, H-2 Antigens biosynthesis, H-2 Antigens genetics, Humans, Immunophenotyping, Mice, Mice, Inbred C57BL, Mice, Knockout, Mice, Transgenic, Ovalbumin immunology, Ovalbumin metabolism, Peptide Fragments, Protein Binding genetics, Protein Binding immunology, Protein Conformation, beta 2-Microglobulin chemistry, Amino Acid Substitution genetics, Antigens, Heterophile genetics, Antigens, Heterophile metabolism, CD8-Positive T-Lymphocytes immunology, CD8-Positive T-Lymphocytes metabolism, H-2 Antigens metabolism, beta 2-Microglobulin genetics, beta 2-Microglobulin metabolism
- Abstract
NK cells and CD8+ T cells bind MHC-I molecules using distinct topological interactions. Specifically, murine NK inhibitory receptors bind MHC-I molecules at both the MHC-I H chain regions and beta2-microglobulin (beta2m) while TCR engages MHC-I molecules at a region defined solely by the class I H chain and bound peptide. As such, alterations in beta2m are not predicted to influence functional recognition of MHC-I by TCR. We have tested this hypothesis by assessing the capability of xenogeneic beta2m to modify the interaction between TCR and MHC-I. Using a human beta2m-transgenic C57BL/6 mouse model, we show that human beta2m supports formation and expression of H-2K(b) and peptide:H-2K(b) complexes at levels nearly equivalent to those in wild-type mice. Despite this finding, the frequencies of CD8+ single-positive thymocytes in the thymus and mature CD8+ T cells in the periphery were significantly reduced and the TCR Vbeta repertoire of peripheral CD8+ T cells was skewed in the human beta2m-transgenic mice. Furthermore, the ability of mouse beta2m-restricted CTL to functionally recognize human beta2m+ target cells was diminished compared with their ability to recognize mouse beta2m+ target cells. Finally, we provide evidence that this effect is achieved through subtle conformational changes occurring in the distal, peptide-binding region of the MHC-I molecule. Our results indicate that alterations in beta2m influence the ability of TCR to engage MHC-I during normal T cell physiology.
- Published
- 2007
- Full Text
- View/download PDF
128. Xenogeneic beta 2-microglobulin substitution alters NK cell function.
- Author
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Benoît LA and Tan R
- Subjects
- Animals, Cell Line, Tumor, Cytotoxicity, Immunologic genetics, Female, Graft Rejection genetics, Graft Rejection immunology, H-2 Antigens genetics, H-2 Antigens immunology, Humans, Immunophenotyping, Killer Cells, Lymphokine-Activated immunology, Killer Cells, Lymphokine-Activated metabolism, Killer Cells, Natural transplantation, Mice, Mice, Inbred C57BL, Mice, Knockout, Mice, Transgenic, Self Tolerance genetics, Self Tolerance immunology, beta 2-Microglobulin biosynthesis, beta 2-Microglobulin deficiency, Killer Cells, Natural immunology, Killer Cells, Natural metabolism, beta 2-Microglobulin genetics
- Abstract
Recently, it has been shown that human beta(2)-microglobulin (h-beta(2)m) blocks the association between the NK cell inhibitory receptor Ly49C and H-2K(b). Given this finding, we therefore sought to assess the immunobiology of NK cells derived from C57BL/6 (H-2(b)) mice expressing exclusively h-beta(2)m. Initial analysis revealed that the Ly49C expression profile of NK cells from h-beta(2)m(+) mice was modified, despite the fact that H-2K(b) expression was normal in these mice. Moreover, the NK cells were not anergic in that IL-2 treatment of h-beta(2)m(+) NK cells in vitro enabled efficient lysis of prototypic tumor cell lines as well as of syngeneic h-beta(2)m(+) lymphoblasts. This loss of self-tolerance appeared to correlate with the activation status of h-beta(2)m(+) NK cells because quiescent h-beta(2)m(+) transplant recipients maintained h-beta(2)m(+) grafts but polyinosine:polycytidylic acid-treated recipients acutely rejected h-beta(2)m(+) grafts. NK cell reactivity toward h-beta(2)m(+) targets was attributed to defective Ly49C interactions with h-beta(2)m:H-2K(b) molecules. With regard to NK cell regulatory mechanisms, we observed that h-beta(2)m:H-2K(b) complexes in the cis-configuration were inefficient at regulating Ly49C and, furthermore, that receptor-mediated uptake of h-beta(2)m:H-2K(b) by Ly49C was impaired compared with uptake of mouse beta(2)m:H-2K(b). Thus, we conclude that transgenic expression of h-beta(2)m alters self-MHC class I in such a way that it modulates the NK cell phenotype and interferes with regulatory mechanisms, which in turn causes in vitro-expanded and polyinosine:polycytidylic acid-activated NK cells to be partially self-reactive similar to what is seen with NK cells derived from MHC class I-deficient mice.
- Published
- 2007
- Full Text
- View/download PDF
129. Decidual NK cells alter in vitro first trimester extravillous cytotrophoblast migration: a role for IFN-gamma.
- Author
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Hu Y, Dutz JP, MacCalman CD, Yong P, Tan R, and von Dadelszen P
- Subjects
- Adult, Cell Communication, Cells, Cultured, Coculture Techniques, Female, Humans, Matrix Metalloproteinase 2 genetics, Matrix Metalloproteinase 9 genetics, Placentation, Pregnancy, Cell Movement, Interferon-gamma physiology, Killer Cells, Natural physiology, Placenta cytology, Pregnancy Trimester, First, Trophoblasts cytology
- Abstract
Abnormal placentation results in either inadequate (consequences: recurrent miscarriage, intrauterine growth restriction, and preeclampsia) or overzealous (consequences: placenta accreta, increta, and percreta) placentation. NK cells dominate in first trimester decidua and probably control extravillous cytotrophoblast (EVT) invasion. We examined this interaction in a novel way, using NK cells and villous explants from concordant first trimester pregnancies cocultured using a new collagen (two-dimensional) model of placentation. Decidual NK (dNK) cells exerted contact-independent inhibition of normal cytotrophoblast migration, associated with changes in the cytotrophoblast expression of metalloproteases-2 and -9, and plasminogen activator inhibitor-1. dNK cells did not affect EVT proliferation and apoptosis, and cell column formation. dNK cell effects were partially reversed by neutralizing Abs against IFN-gamma. We provide ex vivo human evidence of a direct role for dNK in modulating EVT differentiation as they form columns and then migrate from anchoring villi.
- Published
- 2006
- Full Text
- View/download PDF
130. Recognition of HLA class I-restricted beta-cell epitopes in type 1 diabetes.
- Author
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Ouyang Q, Standifer NE, Qin H, Gottlieb P, Verchere CB, Nepom GT, Tan R, and Panagiotopoulos C
- Subjects
- Amino Acid Sequence, Antibody Affinity, Epitopes genetics, HLA-A Antigens genetics, HLA-A Antigens immunology, Histocompatibility Antigens Class I genetics, Humans, Peptide Fragments chemistry, Reference Values, B-Lymphocytes immunology, CD8-Positive T-Lymphocytes immunology, Diabetes Mellitus, Type 1 immunology, Epitopes immunology, Histocompatibility Antigens Class I immunology, Insulin-Secreting Cells immunology
- Abstract
Type 1 diabetes results from the autoimmune destruction of insulin-producing pancreatic beta-cells by cytotoxic T-lymphocytes (CTLs). In humans, few beta-cell epitopes have been reported, thereby limiting the study of beta-cell-specific CTLs in type 1 diabetes. To identify additional epitopes, HLA class I peptide affinity algorithms were used to identify a panel of peptides derived from the beta-cell proteins islet amyloid polypeptide (IAPP), islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP), insulin, insulinoma-associated antigen 2 (IA-2), and phogrin that were predicted to bind HLA-A*0201. Peripheral blood mononuclear cells from 24 HLA-A*0201 recent-onset type 1 diabetic patients and 11 nondiabetic control subjects were evaluated for gamma-interferon secretion in response to peptide stimulation in enzyme-linked immunospot assays. We identified peptides IAPP9-17, IGRP215-223, IGRP152-160, islet IA-2(172-180), and IA-2(482-490) as novel HLA-A*0201-restricted T-cell epitopes in type 1 diabetic patients. Interestingly, we observed a strong inverse correlation between the binding affinity of beta-cell peptides to HLA-A*0201 and CTL responses against those peptides in recent-onset type 1 diabetic patients. In addition, we found that self-reactive CTLs with specificity for an insulin peptide are frequently present in healthy individuals. These data suggest that many beta-cell epitopes are recognized by CTLs in recent-onset type 1 diabetic patients. These epitopes may be important in the pathogenesis of type 1 diabetes.
- Published
- 2006
- Full Text
- View/download PDF
131. Signaling lymphocytic activation molecule-associated protein controls NKT cell functions.
- Author
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Chung B, Aoukaty A, Dutz J, Terhorst C, and Tan R
- Subjects
- Animals, Antigens, CD1 metabolism, Antigens, CD1d, Cytokines biosynthesis, Galactosylceramides immunology, Galactosylceramides pharmacology, Humans, Intracellular Signaling Peptides and Proteins deficiency, Intracellular Signaling Peptides and Proteins genetics, Killer Cells, Natural drug effects, Lymphocyte Activation, Lymphoproliferative Disorders genetics, Lymphoproliferative Disorders immunology, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Mutation, Signaling Lymphocytic Activation Molecule Associated Protein, T-Lymphocyte Subsets drug effects, T-Lymphocytes, Cytotoxic immunology, Intracellular Signaling Peptides and Proteins immunology, Killer Cells, Natural immunology, T-Lymphocyte Subsets immunology
- Abstract
X-linked lymphoproliferative disease (XLP) is a fatal immunological disorder that typically manifests following EBV infection. XLP patients exhibit a number of immune defects including abnormal T, B, and NK lymphocyte function. These defects have been attributed to mutations of Src homology 2 domain-containing gene 1A (SH2D1A), the gene encoding signaling lymphocytic activation molecule-associated protein (SAP), an intracellular adaptor molecule expressed in lymphocytes. We have observed that SAP knockout (SAPKO) mice and humans with XLP have a complete lack of CD1d-restricted NKT cells. As expected, SAPKO mice injected with the NKT cell agonist, alpha-galactosylceramide failed to generate NKT cell IFN-gamma or IL-4. Furthermore, in contrast to wild-type littermates, SAPKO mice coinjected with OVA and alpha-galactosylceramide failed to mount OVA-specific CTL responses. These data suggest that an absence of NKT cells may underlie part of the immune dysregulation seen in SAPKO mice and in XLP patients.
- Published
- 2005
- Full Text
- View/download PDF
132. Evaluation of a diagnostic polymerase chain reaction assay for Neisseria meningitidis in North America and field experience during an outbreak.
- Author
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Pollard AJ, Probe G, Trombley C, Castell A, Whitehead S, Bigham JM, Champagne S, Isaac-Renton J, Tan R, Guiver M, Borrow R, Speert DP, and Thomas E
- Subjects
- Adolescent, Adult, Aged, British Columbia epidemiology, Child, Child, Preschool, DNA Primers chemistry, DNA, Bacterial blood, DNA, Bacterial classification, Female, Humans, Infant, Male, Meningitis, Meningococcal microbiology, Meningitis, Meningococcal mortality, Microbiological Techniques, Neisseria meningitidis genetics, Neisseria meningitidis growth & development, Sensitivity and Specificity, Survival Rate, Disease Outbreaks, Meningitis, Meningococcal diagnosis, Neisseria meningitidis isolation & purification, Polymerase Chain Reaction methods
- Abstract
Context: Meningococcal infection has a high public profile because of its dramatic presentation, high fatality rate, and propensity to occur in outbreaks and clusters of cases. Use of a diagnostic polymerase chain reaction (PCR) assay could enhance laboratory confirmation of cases and guide the public health response in North America., Objective: To assess the performance of a PCR assay for the diagnosis of meningococcal disease after its implementation in a North American setting and to evaluate sensitivity and specificity of the assay for the detection of prevalent bacterial isolates., Design: Laboratory evaluation of the sensitivity and specificity of a PCR assay for Neisseria meningitidis and observational study of a series of cases comparing molecular diagnosis against the criterion standard of conventional laboratory diagnostic tests., Setting: A Canadian province with a population of 4 million people., Patients: Children and adults presenting with suspected meningococcal disease in British Columbia., Main Outcome Measures: The sensitivity and specificity of the PCR assay when compared against standard laboratory methods., Results: The PCR assay correctly identified all of 38 Canadian isolates of Neisseria meningitidis and correctly assigned the serogroup to each isolate. None of 57 other gram-positive or gram-negative bacteria or yeasts were detected by the PCR assay. In a clinical evaluation, for diagnosis of meningococcal disease, the PCR assay had a sensitivity and specificity of 91% and 76%, respectively, against conventional methods of diagnosis. Use of the PCR assay increased the laboratory confirmation of clinically suspected cases by 36%. During an outbreak, the PCR assay allowed serogroup determination in 3 of 7 cases, aiding in the public health decision to launch an immunization campaign., Conclusions: The PCR assay is more sensitive than conventional methods for the diagnosis of meningococcal disease, and enhanced surveillance may help direct the public health response to the changing epidemiology of disease in North America.
- Published
- 2002
- Full Text
- View/download PDF
133. In situ beta cell death promotes priming of diabetogenic CD8 T lymphocytes.
- Author
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Zhang Y, O'Brien B, Trudeau J, Tan R, Santamaria P, and Dutz JP
- Subjects
- Adjuvants, Immunologic administration & dosage, Adoptive Transfer, Animals, Autoantigens immunology, CD8-Positive T-Lymphocytes drug effects, CD8-Positive T-Lymphocytes transplantation, Cytotoxicity, Immunologic drug effects, Cytotoxicity, Immunologic immunology, Diabetes Mellitus, Type 1 pathology, Female, Injections, Intraperitoneal, Lymph Nodes immunology, Lymph Nodes pathology, Lymphocyte Activation drug effects, Male, Mice, Mice, Inbred C57BL, Mice, Inbred NOD, Streptozocin administration & dosage, Time Factors, Apoptosis immunology, CD8-Positive T-Lymphocytes immunology, CD8-Positive T-Lymphocytes pathology, Diabetes Mellitus, Type 1 immunology, Islets of Langerhans immunology, Islets of Langerhans pathology, Lymphocyte Activation immunology
- Abstract
CTLs are important mediators of pancreatic beta cell destruction in the nonobese diabetic mouse model of type 1 diabetes. Cross-presentation of Ag is one means of priming CTLs. The death of Ag-bearing cells has been implicated in facilitating this mode of priming. The role of beta cell death in facilitating the onset of spontaneous autoimmune diabetes is unknown. Here, we used an adoptive transfer system to determine the time course of islet-derived Ag presentation to naive beta cell-specific CD8 T cells in nonobese diabetic mice and to test the hypothesis that beta cell death enhances the presentation of beta cell autoantigen. We have determined that beta cell death enhances autoantigen presentation. Priming of diabetogenic CD8 T cells in the pancreatic lymph nodes was negligible before 4 wk, progressively increased until 8 wk of age, and was not influenced by gender. Administration of multiple low doses of the beta cell toxin streptozotocin augmented in situ beta cell apoptosis and accelerated the onset and magnitude of autoantigen presentation to naive CD8 T cells. Increasing doses of streptozotocin resulted in both increased pancreatic beta cell death and significantly enhanced T cell priming. These results indicate that in situ beta cell death facilitates autoantigen-specific CD8 T cell priming and can contribute to both the initiation and the ongoing amplification of an autoimmune response.
- Published
- 2002
- Full Text
- View/download PDF
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