Early over expression of messenger RNA for multiple genes, including insulin, in the Pancreatic Lymph Nodes of NOD mice is associated with Islet Autoimmunity

<p>Abstract</p> <p>Background</p> <p>Autoimmune diabetes (T1D) onset is preceded by a long inflammatory process directed against the insulin-secreting β cells of the pancreas. Deciphering the early autoimmune mechanisms represents a challenge due to the absence of clinical signs at early disease stages. The aim of this study was to identify genes implicated in the early steps of the autoimmune process, prior to inflammation, in T1D. We have previously established that insulin autoantibodies (E-IAA) predict early diabetes onset delineating an early phenotypic check point (window 1) in disease pathogenesis. We used this sub-phenotype and applied differential gene expression analysis in the pancreatic lymph nodes (PLN) of 5 weeks old Non Obese Diabetic (NOD) mice differing solely upon the presence or absence of E-IAA. Analysis of gene expression profiles has the potential to provide a global understanding of the disease and to generate novel hypothesis concerning the initiation of the autoimmune process.</p> <p>Methods</p> <p>Animals have been screened weekly for the presence of E-IAA between 3 and 5 weeks of age. E-IAA positive or negative NOD mice at least twice were selected and RNAs isolated from the PLN were used for microarray analysis. Comparison of transcriptional profiles between positive and negative animals and functional annotations of the resulting differentially expressed genes, using software together with manual literature data mining, have been performed.</p> <p>Results</p> <p>The expression of 165 genes was modulated between E-IAA positive and negative PLN. In particular, genes coding for insulin and for proteins known to be implicated in tissue remodelling and Th1 immunity have been found to be highly differentially expressed. Forty one genes showed over 5 fold differences between the two sets of samples and 30 code for extracellular proteins. This class of proteins represents potential diagnostic markers and drug targets for T1D.</p> <p>Conclusion</p> <p>Our data strongly suggest that the immune related mechanisms taking place at this early age in the PLN, correlate with homeostatic changes influencing tissue integrity of the adjacent pancreatic tissue. Functional analysis of the identified genes suggested that similar mechanisms might be operating during pre-inflammatory processes deployed in tissues i) hosting parasitic microorganisms and ii) experiencing unrestricted invasion by tumour cells.</p

Development of an enzyme-linked immunosorbent assay with a monoclonal antibody prepared against alpha 1-antitrypsin for diagnostic screening of inflammatory disorders.

A monoclonal antibody, designated A2a18b8, of IgG1 class prepared against human alpha 1-antitrypsin, cross-reacts with alpha 1-antitrypsin in the serum of rat and baboon, but not with alpha 1-antitrypsin in serum of rabbit, pig, hamster, guinea pig, dog, or turtle. We used A2a18b8 in an enzyme-linked immunosorbent assay (ELISA) developed for human alpha 1-antitrypsin. Preliminary ELISA screening of 247 serum samples from patients with various inflammatory disorders indicated that the concentration of a specific epitope(s) on alpha 1-antitrypsin recognized by this monoclonal antibody was increased significantly in patients with active systemic lupus erythematosus, mixed connective tissue disease, and rheumatoid arthritis, but not in patients with sclerodermic disorders or Sjögren's syndrome. Evidently, A2a18b8 has diagnostic value in that it selectively recognizes a specific epitope(s) on alpha 1-antitrypsin that is (are) apparently exposed during selective inflammatory disorders

Anti-islet autoantibodies trigger autoimmune diabetes in the presence of an increased frequency of islet-reactive CD4 T cells

OBJECTIVE To define cellular mechanisms by which B cells promote type 1 diabetes.RESEARCH DESIGN AND METHODS The study measured islet-specific CD4 T cell regulation in T-cell receptor transgenic mice with elevated frequencies of CD4 T cells recognizing hen egg lysozyme (HEL) autoantigen expressed in islet β-cells and thymic epithelium under control of the insulin-gene promoter. The effects of a mutation in Roquin that dysregulates T follicular helper (Tfh) cells to promote B-cell activation and anti-islet autoantibodies were studied, as were the effects of HEL antigen–presenting B cells and passively transferred or maternally transmitted anti-islet HEL antibodies.RESULTS Mouse anti-islet IgG antibodies—either formed as a consequence of excessive Tfh activity, maternally transmitted, or passively transferred—caused a breakdown of tolerance in islet-reactive CD4+ cells and fast progression to diabetes. Progression to diabetes was ameliorated in the absence of B cells or when the B cells could not secrete islet-specific IgG. Anti-islet antibodies increased the survival of proliferating islet-reactive CD4+ T cells. FcγR blockade delayed and reduced the incidence of autoimmune diabetes.CONCLUSIONS B cells can promote type 1 diabetes by secreting anti-islet autoantibodies that act in an FcγR-mediated manner to enhance the expansion of islet-reactive CD4 T cells and cooperate with inherited defects in thymic and peripheral CD4 T–cell tolerance. Cooperation between inherited variants affecting CD4 T–cell tolerance and anti-islet autoantibodies should be examined in epidemiological studies and in studies examining the efficacy of B-cell depletion