Early over expression of messenger RNA for multiple genes, including insulin, in the Pancreatic Lymph Nodes of NOD mice is associated with Islet Autoimmunity.
BACKGROUND
Autoimmune diabetes (T1D) onset is preceded by a long inflammatory process directed against the insulin-secreting beta 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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Immunophysiology and Intracellular Parasitism Unit, Department of Parasitology and Mycology, 75015 Paris, France. regnault@pasteur.fr
Béatrice
B
Regnault
José
J
Osorio Y Fortea
Dongmei
D
Miao
George
G
Eisenbarth
Evie
E
Melanitou
D000818:Animals; D001323:Autoantibodies / Q000276:immunology; D015551:Autoimmunity / Q000276:immunology*; D002874:Chromosome Mapping; D016000:Cluster Analysis; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D016678:Genome / Q000235:genetics; D007150:Immunohistochemistry; D007328:Insulin / Q000235:genetics / Q000276:immunology; D007515:Islets of Langerhans / Q000276:immunology*; D008198:Lymph Nodes / Q000378:metabolism*; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010179:Pancreas / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D001323:Autoantibodies; D007328:Insulin; D012333:RNA, Messenger