Jana Lauzon

Prevention of Type I Diabetes in NOD Mice by Adjuvant Immunotherapy

The nonobese diabetic (NOD) mouse is an excellent model of insulin-dependent (type I) human diabetes mellitus. We report that a single injection of complete Freunds adjuvant (CFA) given at an early age (5 wk) prevented the appearance of diabetes and greatly increased the life span of NOD mice without additional therapy. No treated mouse developed hyperglycemia by the age of 12 mo (n = 13), whereas all untreated mice died of diabetes before 8 mo of age (n = 38). All CFA-treated mice were alive and healthy at 12 mo of age. Some CFA-treated NOD mice that were monitored for long-term survival are still alive with no sign of disease at 18 mo of age (n = 5). Administration of CFA resulted in decreased in vitro splenic lymphocyte proliferative responses to alloantigen and mitogen. Cell-mixing experiments indicated that antigen-nonspecific inhibitory cells were elicited in the spleen and increased in the bone marrow. These regulatory cells were Thy-1− ; and nonadherent to nylon wool, as has been described for natural suppressor (NS) cells. These data lend support to a relationship between the boosting of endogenous NS activity and the establishment of tolerance to self in the context of autoimmunity. Our results suggest that early nonspecific immunotherapy of genetically predisposed individuals could prevent the development of autoimmune diabetes.

Immunization With the Larger Isoform of Mouse Glutamic Acid Decarboxylase (GAD67) Prevents Autoimmune Diabetes in NOD Mice

The 65-kDa isoform of glutamic acid decarboxylase (GAD65) has been implicated in autoimmune diabetes in NOD mice, but the role of the 67-kDa GAD isoform (GAD67) is less clear. We found that immunization of 4-week-old NOD mice with purified recombinant mouse GAD67 prevented or significantly delayed the onset of diabetes. To further explore this phenomenon, we characterized anti-GAD67 immune responses in naive and GAD-immunized NOD mice. Anti-GAD67 antibodies titers were relatively low in naive mice at all ages, but a single immunization with GAD67 at 4 weeks induced high titers of anti-GAD antibodies by 6 weeks of age. In both 4-week-old and diabetic NOD mice, there were significant endogenous T-cell proliferative responses against purified recombinant mouse GAD67. These T-cell proliferative responses were blocked by anti-I-ANOD and anti-CD4 antibodies. To characterize the anti-GAD T-cell responses in the NOD mice, we established T-cell lines and T-cell clones which recognized GAD67, and we used recombinant subfragments of GAD to localize the predominant T-cell epitopes in GAD67. T-cells from naive NOD mice proliferated in response to all GAD subfragments, whereas T-cells from diabetic mice responded primarily to the COOH-terminal 83 amino acids of GAD67. These results suggest that GAD67 is an autoantigen in IDDM and immunization of prediabetic NOD mice with GAD67 can prevent the onset of diabetes.

An enclosed in-gel PCR amplification cassette with multi-target, multi-sample detection for platform molecular diagnostics

This work describes a self-contained, simple, disposable, and inexpensive gel capillary cassette for DNA amplification in near point of care settings. The cassette avoids the need for pumps or valves during raw sample delivery or polymerase chain reaction (PCR) amplification steps. The cassette contains capillary reaction units that can be stored at room temperature for up to 3 months. The current cassette configuration format simultaneously tests up to 16 patients for two or more targets, accommodates different sample types on the same cassette, has integrated positive and negative controls and allows flexibility for multiple geometries. PCR reagents in the cassette are desiccated to allow storage at room temperature with rehydration by raw sample at the time of testing. The sample is introduced to the cassette via a transfer pipette simply by capillary force. DNA amplification was carried out in a portable prototype instrument for PCR thermal cycling with fluorescence detection of amplified products by melt curve analysis (MCA). To demonstrate performance, raw genital swabs and urine were introduced to the same cassette to simultaneously detect four sexually transmitted infections. Herpes Simplex Viruses (HSV-1 and HSV-2) were detected from raw genital swabs. Ureaplasma urealyticum (UU) and Mycoplasma homonis (MH) were detected from raw urine. Results for multiple patients were obtained in as little as 50 min. This platform allows multiparameter clinical testing with a pre-assembled cassette that requires only the introduction of raw sample. Modification of the prototype device to accommodate larger cassettes will ultimately provide high throughput simultaneous testing of even larger numbers of samples for many different targets, as is required for some clinical applications. Combinations of wax and/or polymer cassettes holding capillary reaction units are feasible. The components of the cassette are suited to mass production and robotic assembly to produce a readily manufactured disposable reaction cassette that can be configured for disease-specific testing panels. Rapid testing with a disposable reaction cassette on an inexpensive instrument will enable on the spot evaluation of patients in the clinic for faster medical decision-making and more informed therapeutic choices.

A miniaturized and integrated gel post platform for multiparameter PCR detection of herpes simplex viruses from raw genital swabs.

Herpes simplex virus (HSV) is one of the most prevalent viruses, with acute and recurrent infections in humans. The current gold standard for the diagnosis of HSV is viral culture which takes 2-14 days and has low sensitivity. In contrast, DNA amplification by polymerase chain reaction (PCR) can be performed within 1-2 h. We here describe a multiparameter PCR assay to simultaneously detect HSV-1 and HSV-2 DNA templates, together with integrated positive and negative controls, with product detection by melting curve analysis (MCA), in an array of semi-solid polyacrylamide gel posts. Each gel post is 0.67 μL in volume, and polymerized with all the components required for PCR. Both PCR and MCA can currently be performed in one hour and 20 min. Unprocessed genital swabs collected in universal transport medium were directly added to the reagents before or after polymerization, diffusing from atop the gel posts. The gel post platform detects HSV templates in as little as 2.5 nL of raw sample. In this study, 45 genital swab specimens were tested blindly as a preliminary validation of this platform. The concordance of PCR on gel posts with conventional PCR was 91%. The primer sequestration method introduced here (wherein different primers are placed in different sets of posts) enables the simultaneous detection of multiple pathogens for the same sample, together with positive and negative controls, on a single chip. This platform accepts unprocessed samples and is readily adaptable to detection of multiple different pathogens or biomarkers for point-of-care diagnostics.

Role of the first external domain of I-Aβ chain in immune responses and diabetes in non-obese diabetic (NOD) mice

Diabetes in the non-obese diabetic (NOD) mouse is a multigenic autoimmune disease and is possibly controlled by three recessive loci, including one that is linked to the major histocompatibility complex (MHC). The first external domain of the Class II MHC I-A beta chain in these mice is unique and has been suggested as being responsible for autoimmunity. The I-A alpha chain in these mice is I-A alpha d, and they lack the expression of I-E molecules. We have investigated immune responses to various Ir gene control antigens in NOD mice to determine the influence of the NOD Ia and particularly the I-A beta chain. We find that sheep insulin is highly immunogenic while other insulins are weakly immunogenic in these mice. Hen egg lysozyme, pigeon cytochrome C and the synthetic polypeptide Poly 18, Poly EYK(EYA)5 antigen produce good antibody responses. Apart from H-2d, NOD are the only mice where Poly 18 antigen is immunogenic. In these mice Poly 18 induced good T-cell proliferative response, which was inhibited by anti-Ia antibody, and the mice were able to respond to tyrosine-containing polypeptide Poly EYA but not to the phenylalanine-containing antigen Poly EFA. We also found that synthetic peptide 48-60 of the NOD I-A beta chain is highly immunogenic in syngeneic NOD mice both for T cells and B cells. Using an I-A beta chain-specific monoclonal antibody, we are able to prevent induction of diabetes when the antibody was administrated in prediabetic, young mice. Our results suggest that the immune response to various antigens and autoimmune diabetes in NOD mice is directly influenced by the I-A beta chain.

Characterization of agretopes and epitopes involved in the presentation of beef insulin to T cells

Beef insulin-specific I-Ad-restricted T cell hybridomas were derived from the fusion of antigen-primed (BALB/c X B6)F1 T cells with BW5147 thymoma. Specificity analysis revealed that the A-chain loop region is involved in antigen recognition. Hybridoma A20.2.15 is specific for beef insulin and cross-reacted with sheep insulin, but not with pork insulin. Using synthetic peptides we showed that the A-chain loop containing peptide A1-A14 jointed to the B7-B15 peptide by a disulfide bond can activate this hybridoma. Fragments generated by enzyme digest further suggest that the peptide recognized on beef insulin appears to involve A-chain loop residues A5-A12 and B-chain residues B7-B13 that are linked by the A7-B7 disulfide bridge. We found that beef insulin needs to be processed prior to T cell activation. Glutaraldehyde fixation and chloroquine treatment of presenting cells abolished their capacity to present insulin. Beef insulin denatured by pH changes cannot activate, thus suggesting that simple denaturation is not sufficient for presentation by antigen presenting cells. Finally, the agretope on beef insulin is comprised of two functional regions B7-B13 on the B chain and the A-chain loop in the A-chain, while residues A8 and A10 are probably involved in interaction with the T cell receptor.

Genotyping Single Nucleotide Polymorphisms in Human Genomic DNA with an Automated and Self-Contained PCR Cassette

Point-of-care devices can lower costs through reduced reagent costs, shifting diagnostics from centralized laboratories to local clinics or hospitals, rapidly informing on the spot medical decision making, and enabling personalized treatment options. We have previously described a self-contained miniaturized device that uses an array of gel-based reaction units that can simultaneously detect multiple biomarkers and/or multiple patients in one PCR cassette and can be stored for up to 7 months. In this article, we document the ability of cassette PCR to detect single nucleotide polymorphisms (SNPs) in human genomic DNA from buccal swabs. Swab processing takes 8 minutes, and PCR is completed in just more than an hour. To demonstrate potential for genotyping, we used allele-specific PCR and melt curve analysis to detect major and minor alleles of two SNPs in the fibroblast growth factor receptor 2 gene (FGFR2) that are linked with breast cancer. After allele-specific PCR, seamless melt curve analysis and the presence or absence of melt peaks from melt curve analysis identifies the FGFR2 SNP genotypes for each patient. The near point-of-care/point-of-need genotyping methods reported here can be applied for detecting and assessing risks of diseases such as cancer and to detect SNPs that alter drug metabolism and hence response to therapy.

Monitoring food pathogens: Novel instrumentation for cassette PCR testing

In this manuscript, we report the design and development of a fast, reliable instrument to run gel-based cassette polymerase chain reactions (PCR). Here termed the GelCycler Mark II, our instrument is a miniaturized molecular testing system that is fast, low cost and sensitive. Cassette PCR utilizes capillary reaction units that carry all reagents needed for PCR, including primers and Taq polymerase, except the sample, which is loaded at the time of testing. Cassette PCR carries out real time quantitative PCR followed by melt curve analysis (MCA) to verify amplicon identity at the expected melt temperature (Tm). The cassette PCR technology is well developed, particularly for detecting pathogens, and has been rigorously validated for detecting pathogenic Escherichia coli in meat samples. However, the work has been hindered by the lack of a robust and stable instrument to carry out the PCR, which requires fast and accurate temperature regulation, improved light delivery and fluorescent recording, and faster PCR reactions that maintain a high sensitivity of detection. Here, we report design and testing of a new instrument to address these shortcomings and to enable standardized testing by cassette PCR and commercial manufacture of a robust and accurate instrument that can be mass produced to deliver consistent performance. As a corollary to our new instrument development, we also report the use of an improved design approach using a machined aluminum cassette to meet the new instrument standards, prevent any light bleed across different trenches in each cassette, and allow testing of a larger number of samples for more targets in a single run. The GelCycler Mark II can detect and report E. coli contamination in 41 minutes. Sample positives are defined in as having a melt curve comparable to the internal positive control, with peak height exceeding that of the internal negative control. In a fractional analysis, as little as 1 bacterium per capillary reaction unit is directly detectable, with no enrichment step, in 35 cycles of PCR/MCA, in a total time of 53 minutes, making this instrument and technology among the very best for speed and sensitivity in screening food for pathogenic contamination.