Project 2: Hygiene Hypothesis

(A) Type One Diabetes

Each year in this country more than 13,000 young people are diagnosed with type 1 diabetes (T1D). In this autoimmune disease, insulin-producing b cells are destroyed by CD4 and CD8 T cells infiltrating the pancreatic islets, causing defects in blood glucose homeostasis and ultimately vascular and neurological complications. T1D is potentially life threatening, and an increasingly significant public health problem worldwide, particularly in western European countries where there is an alarming decrease in the age of onset. The “hygiene hypothesis” links the increase in autoimmune phenomena in humans to excessively sanitary conditions early in life. In retrospective studies that seek to link the relationship of typical childhood infectious diseases to T1D, exposure to Streptococcus pyogenes (GAS) had a significant negative correlation with acquisition of T1D. In rodent models treatment with GAS preparations leads to diabetes resistance. In GAS infections antibodies are made against cell wall-associated N-acetyl-D-glucosamine (GlcNAc). We will test the hypothesis that alternative GlcNAc-specific B lymphocyte activities can influence the development of autoimmune diabetes by contributing to protection or acceleration of disease. Anti-GlcNAc antibodies also bind proteins and insulin-containing secretory granules enriched in pancreatic β cells. We will examine a role for GlcNAc specific B lymphocytes in modulating T1D in mouse models and test the hypothesis that anti-GlcNAc lymphocytes protect against T1D by generating anti-GlcNAc antibodies that dampen the autoimmune response to GlcNAcylated molecules associated with β islet cells. In an alternative context, we propose that anti-GlcNAc B-lymphocytes can be involved on presenting GlcNAcylated β cell autoantigens to diabetogenic T cells. In Aim 1 we will determine how early immunization and timed passive anti-GlcNAc antibody influence the rate and severity of T1D progression in NOD mice. Aim 2 will study the effects of antibodies on antigen-presenting cell activation of diabetogenic T cells in vitro. Finally in Aim 3 we will determine the mechanisms of protection against T1D development in intact NOD mice.


The knowledge of how a common infectious organism, GAS, alters an individual’s propensity to develop type I diabetes (T1D) will be applied to understanding mechanisms involved in T1D induction and progression in the NOD model which simulates many aspects of human T1D. The long-term goal of this project is to identify factors that can influence the progression of T1D in susceptible individuals, which may improve T1D diagnosis and development of immunization strategies for prevention of T1D.

(B) Characterization of Pancreas-Infiltrating GlcNAc-Reactive B cell Clonotypes in Human T1D

Very little is known regarding the specificity and clonal heterogeneity of islet infiltrating B cells in human T1D, and the progression of successive targets within the B cell response of T1D remains unknown In addition to the studes of our mouse models we plan to develop reagents that enable longitudinal tracking of clonal frequencies represented in GlcNAc-reactive B cell pool of pre-autoantibody positive T1D patients. Many innate-like B cell antigen specificities, such as GlcNAc, exhibit high levels of clonal restriction in the human population. In cases of these B cell clonotypes, anti-idiotypic antibodies may be used to identify B cell receptor-restricted epitopes that correlate with certain clonal and fine-specificity antibody qualities. The goal of this aim is to translate our findings in mice regarding T1D-suppressive GlcNAc-reactive B cells into diagnostic tools through the generation of anti-idiotypic antibody reagents specific for human GlcNAc-reactive B cells. Following our findings in NOD mice, we propose that GlcNAc-reactive B cells clones will be recoverable from pancreatic tissue of T1D patients. The goal of this aim is to pair our antibody cloning technology, with Laser Microdissection Microscopy to identify GlcNAc-reactive B cell clonotypes recovered from human pancreas biopsies. Identification of cryptic glycan-reactive B cell clonotypes, particularly class-switched clonotypes involved in T1D progression, will facilitate the development and validation of specific anti-Id reagents to monitor the activation and differentiation of disease-associated clonotypes.

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