Ph.D., Faculty of Health Sciences, University of the Witwatersrand, 2006. / Objectives. Autoantibodies to the 65kDa isoform of glutamic acid decarboxylase (GAD65Abs) are accepted markers for type 1 diabetes and, together with autoantibodies to insulin (IAA) and a protein tyrosine phosphatase-like islet cell antigen (IA-2), predict the disease. IAA are often the first autoantibodies detected in type 1 diabetics and can be present before the onset of clinical diabetes. These autoantibodies and their epitopes are however not well characterized. We explored the use of monoclonal antibodies and their recombinant Fab (rFab) as reagents for epitope analysis. Methods and Results. Four rFab specific for insulin were cloned from murine monoclonal antibodies (mAbs) 1E2, HB-126, HB-123, HB-127, and one rFab specific for GAD65 was cloned from human mAb IgG antibody DP-D (derived from autoimmune disease patients), to characterise insulin and GAD65 autoantibodies present in the sera of patients with type 1 diabetes. Only rFab 126 and DP-D showed insulin and GAD65 specific binding, respectively in radiobinding assays. In competition experiments with sera positive for autoantibodies to insulin the rFab 126 significantly reduced the binding to 125I-insulin by sera of type 1 (n=35) and type 1.5 diabetes (or LADA) (n=14) patients (p<0.0001). There was no difference in the competition pattern in IAA positive type 1 diabetes patients (n=35) and IAA positive type 1.5 diabetes patients (n=14). The insulin epitope that the rFab binds to was mapped using competitive radiobinding assays with two monoclonal antibodies (mAb 1 and mAb 125) whose epitopes are on the B chain and A chain loop of insulin, respectively. We found the epitope of this recombinant antibody to be located on the A chain loop of the insulin molecule. The 3-dimensional structure of rFab 123, 126 and DP-D were determined using an automated homology modelling programme. Using the computer programme ‘PatchDock’ we attempted to further map the epitope that rFab 126 binds to on insulin. Of the three models generated, only one supported our findings that rFab 126 binds to the A chain loop of insulin. The binding of GAD65Ab in 61 type 1 diabetes patients to GAD65 was analyzed by competitive radioimmunoassays with rFab DP-D to ascertain disease-specific GAD65Ab binding specificities. The median binding was reduced significantly by rFab DP-D (80%) (p<0.0001). The competition pattern in type 1 diabetes patients was different from that in GAD65Ab-positive type 1.5 diabetes patients (n=44), first degree relatives (n=38), and healthy individuals (n=14) (Padoa et al., 2003). Conclusions. We have shown that rFab specific for insulin and GAD65 can be generated using PCR technology and that such agents can be used to determine the insulin/GAD65 epitopes recognized by autoantibodies from type 1 and 1.5 diabetics. These novel findings with GAD65- and insulin-specific rFab support the view that type 1 diabetes is associated with disease- and epitope-specific GAD65- and insulin-autoantibodies and supports the notion that the middle epitope of GAD65 is disease-specific. These GAD65-specific rFab should prove useful in predicting type 1 diabetes. Furthermore, rFabs may be a novel method for blocking autoimmune responses against β cell autoantigens in type 1 diabetics.

Subsets of systemic lupus erythematosus (SLE) patients with distinct patterns of disease manifestations and autoantibody production have been reported, but seldom have these two phenomena been analysed together. Cluster analysis was performed on 1928 Chinese SLE patients based on autoantibody profile and the frequencies of various clinical manifestations were compared between each cluster. Separate association analyses between individual autoantibodies and clinical manifestations, as well as between clinical manifestations, were also performed. This study identifies three separate autoantibody clusters each with different clinical manifestations, and proposes that the phenomena of autoantibody clustering and clinical subsets may be inter-related. Patient clusters could also be stratified into a bipolar spectrum. On one end are patients with over-representation of anti-dsDNA and renal disorder; whilst on the other end are two distinct autoantibody clusters (anti-Sm/anti-RNP/aPL and aPL/anti-Ro/anti-La) with overlapping of other non-renal manifestations. Patient stratification could aid disease prediction and subsequent management. These findings may also elucidate disease pathogenesis and guide future study on potential common pathological processes within autoantibody clusters. / published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Research in Medicine

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20282号 / 医博第4241号 / 新制||医||1021(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 三森 経世, 教授 鈴木 茂彦, 教授 生田 宏一 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

AIM: This study aims to determine what portion of specific autoantibody phenotypes are genetically determined by using a twin model. METHODS: This study specifically examines Anti-Ro(SSA), Anti-La (SSB), Anti-Sn/RNP, Anti-Sm, Anti-Jo-1, Anti-Scl-70, Anti-Tg & Anti-TPO, Anti-dsDNA, Anti-PS, and Anti-cardiolipin antibodies for their heritability. This study examined 104 same-sex adult twins (66 monozygous, 38 dizygous) for the above mentioned autoantibody values. The serum autoantibody values in each subject were quantified using automated ELISA. Descriptive statistics including, distributions, quantiles, and moments were calculated by zygosity for continuous antibody values, subject ages, gender, race and smoking status. Categorical antibody levels were used to determine twin pair concordance rates. Continuous and rank ordered autoantibody values were used to determine the presence and portion of a genetic component. To evaluate how strongly the antibody values in each twin group resembled each other, the intraclass correlation was calculated for each antibody by zygosity. The genetic variances, environmental variances, and heritability were estimated using path models with maximum likelihood estimation techniques. The phenotypic variance was modeled as a linear function of underlying additive genetic (A), dominant genetic (D), common environmental (C), and random environmental (E) effects. RESULTS: Several antibodies demonstrated a genetic component in our study population. Anti-cardiolipin had a genetic component with an estimated 69% heritability. Anti-dsDNA yielded a genetic component with a heritability estimate of 55-62%. Anti-Jo-1 presented a genetic component with the heritability estimate to be 41-51%. Anti-SCL-70 demonstrated a genetic component with a heritability estimate of 42-59%. Anti-PL had a genetic component with a heritability estimate of 52-54%. Several antibodies did not have a measurable genetic component. These included anti-Sm, anti-Ro(SSA), anti-La(SSB), anti-sn/RNP, anti-Tg, and anti-TPO. Some possibilities for the lack of a measureable genetic component may be due to the limited number of discordant twin pairs and/or the small number of subjects with higher levels of antibodies. CONCLUSION: The results of this study suggest several clinically relevant markers of auto-immunity may be partially genetically determined. These include: anti-cardiolipin, anti-dsDNA, anti-Jo-1, anti-SCL-70, and anti-phospholid.

<p>The chaperone protein GRP78 is primarily expressed in the endoplasmic reticulum, but it is also aberrantly expressed on the surface of cells under pathological conditions. One the cell membrane, GRP78 acts as a signaling molecule with unique properties. The amino-terminal domain acts as a growth factor receptor-like protein, while the carboxyl-terminal domain functions as a death-signaling receptor-like protein to extrinsically induce apoptosis. Autoantibodies that react with cell-surface GRP78 on many tumor cell lines occur in the sera of patients with prostate cancer, melanoma, and ovarian cancer. These autoantibodies are a negative prognostic factor in prostate cancer and melanoma, and when purified, stimulate tumor cell proliferation in vitro. It is unclear, however, whether these IgGs are merely a biomarker, or if they actually promote tumor growth in vivo. We immunized C57Bl/6 mice with recombinant GRP78 and then implanted the B16F1 murine melanoma cell line as flank tumors. We employed the antisera from these mice for in vitro cell signaling and proliferation assays. The immunodominant epitope in human cancer patients was well represented in the antibody repertoire of these immunized mice. We observed significantly accelerated tumor growth, as well as shortened survival in GRP78-immunized mice as compared to controls. Furthermore, antisera from these mice, as well as purified anti-GRP78 IgG from similarly immunized mice, stimulate Akt phosphorylation and proliferation in B16F1 and human DM6 melanoma cells in culture. These studies demonstrate a causal link between a humoral response to GRP78 and the progression of cancer in a murine melanoma model. They support the hypothesis that such autoantibodies are involved in the progression of human cancers and are not simply a biomarker. Because GRP78 is present on the surface of many types of cancer cells, this hypothesis has broad clinical and therapeutic implications.</p><p>We generated and characterized a panel of monoclonal murine antibodies (mAbs) against GRP78 with the goal of identifying therapeutic candidate IgGs. We developed three stable hybridomas that produce interesting antibodies. The N88 IgG reacts with the NH2-terminal domain and is an agonist. The C38 IgG reacts with the COOH-terminal domain and is an antagonist of NH2-terminal signaling. The C107 IgG binds the COOH-terminal domain and induces apoptosis. </p><p>We examined the effect of these three mAbs on the growth of B16 flank tumors. N88 accelerated and C107 slowed tumor growth, while C38 had no net effect. We are currently developing these antibodies and derivatives thereof as therapeutics for melanoma as well as for cancers of the brain, breast, ovary, and prostate. In fact, any tumor cell that over-expresses GRP78 on its surface is a potential therapeutic target for our future studies.</p> / Dissertation

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20757号 / 医博第4287号 / 新制||医||1024(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 生田 宏一, 教授 濵﨑 洋子, 教授 髙折 晃史 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21252号 / 医博第4370号 / 新制||医||1029(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 川上 浩司, 教授 中山 健夫, 教授 小池 薫 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Salmonella enterica serotype Typhimurium is a rod-shaped, motile, Gram-negative bacterium that causes gastroenteritis in immunocompetent individuals. S. Typhimurium produces an extracellular protein termed curli, a bacterial amyloid with a cross beta-sheet tertiary structure that is common across all amyloids. Curli formation is critical for biofilm formation by enteric pathogens such as S. Typhimurium and E. coli. Curli expression requires the production of multiple proteins, which are encoded by two operons known as csgBAC and csgDEFG. Curli production can be induced in vitro by low temperature and low osmolarity, which is evident by growth on T-medium plates for 72 hours at 28oC. Earlier studies have shown that curli is expressed in sepsis patients with E. coli, as well as in mice after S. Typhimurium infection. This is evidenced by the production of antibodies to CsgA, the major subunit of curli. Our lab has shown that curli fibers are recognized by the TLR2/TLR1 complex of the innate immune system during infection. Infection with curli expressing bacteria causes elevated levels of proinflammatory cytokines, nitric oxide, and autoantibodies. Nonetheless, the details of curli expression in vivo during bacterial infection remain unknown. The focus of these studies was to elucidate the location where bacteria expresses curli in vivo during infection. Initially, we used S. Typhimurium strains carrying plasmids with csgB and csgD promoter regions fused to the gfp gene to study curli expression in vivo by use of flow cytometry. Unfortunately, we were unable to determine curli expression with this model, due to the diminished fluorescence intensity of GFP under anaerobic conditions in the gastrointestinal tract. As the question of curli expression in vivo was left unanswered, we next used a long-term infection model of S. Typhimurium with the goal of determining seroconversion to curli as well as the location and timing of curli expression. Using CBA/J mice infected with wild-type S. Typhimurium or a curli mutant strain, we were able to identify seroconversion to CsgA in the mice infected with the wild-type strain through ELISA and western blot analysis. We were also able to identify autoantibody production in mice infected with the wild-type strain through ELISA. However, we were unable to determine curli expression in the feces of mice either by western blot or qPCR data. We were also able to identify autoantibody production in mice infected with the wild-type strain through an anti-double stranded DNA ELISA. Preliminary findings lead us to hypothesize that curli expression may occur very early on in infection, and may be expressed inside cells such as macrophages. Overall, our results partially elucidate curli expression in vivo, although more research is needed in order to answer our remaining questions regarding location and timing of expression. / Biomedical Sciences

<p>IC2, a well known monoclonal autoantibody, derived from newly diabetic BB rat and seems to be an important biomarker for non-invasive functional imaging of beta cells in vivo. It specially and uniquely binds with pancreatic beta cells as confirmed in some previous studies. RIN-5AH is a pancreatic beta cell, which reacts with IC2 is used here to identify and characterize the molecular nature of the IC2 auto antigen by using TLC and HPTLC following by immuno-staining. An unpublished work already had done by Spitalnik et al, 1991 with another rat pancreatic beta cell (RINm5F) extracted glycolipids. In this study, the same work was done, not only with glycolipids from various cell lines but also lipids extracted from purified plasma membrane is made to confirm or refuge that IC2 was found to bind with only the glycolipids containing galactose-3-sulfate. This highly unique observation can however hardly explain the unique beta cell surface specificity without involvement of other more beta cell specific antigenic structures. We are therefore also searching the protein part involved in the auto antigenic determinant. Analyzing the molecular nature of IC2 binding auto-antigen, will help to understand both the role it might plays in the pathogenesis of insulin dependant diabetes. It could also help to elucidate the etiology of diabetes and finally to be a new serum autoantibody biomarker.</p>

IC2, a well known monoclonal autoantibody, derived from newly diabetic BB rat and seems to be an important biomarker for non-invasive functional imaging of beta cells in vivo. It specially and uniquely binds with pancreatic beta cells as confirmed in some previous studies. RIN-5AH is a pancreatic beta cell, which reacts with IC2 is used here to identify and characterize the molecular nature of the IC2 auto antigen by using TLC and HPTLC following by immuno-staining. An unpublished work already had done by Spitalnik et al, 1991 with another rat pancreatic beta cell (RINm5F) extracted glycolipids. In this study, the same work was done, not only with glycolipids from various cell lines but also lipids extracted from purified plasma membrane is made to confirm or refuge that IC2 was found to bind with only the glycolipids containing galactose-3-sulfate. This highly unique observation can however hardly explain the unique beta cell surface specificity without involvement of other more beta cell specific antigenic structures. We are therefore also searching the protein part involved in the auto antigenic determinant. Analyzing the molecular nature of IC2 binding auto-antigen, will help to understand both the role it might plays in the pathogenesis of insulin dependant diabetes. It could also help to elucidate the etiology of diabetes and finally to be a new serum autoantibody biomarker.