Expression Analysis of Intestinal Stem Cell Signaling Pathways in Acute Celiac Disease
Celiac disease is an autoimmune disease triggered by ingestion of gluten, the key proteic component of wheat, in genetically predisposed individuals. The intestinal mucosa presents lesions with varying degrees of inflammation secondary to the autoimmune insult characterized by villous atrophy and crypts hyperplasia. Aims: The current study is aimed at understanding the biochemical response to inflammation of the intestinal stem cell compartment (ISC) during the acute phase of celiac disease.
The expression profile of 86 genes previously identified to be involved in stem cell signaling pathways in mouse intestine and cancer cells were evaluated. As stem cells are under-represented in duodenal biopsies when compared to differentiated cells, we used stem-progenitor enriched cells from intestinal crypts to prepare RNA. Crypts from biopsies of active celiac patients (N=3) and healthy controls (N=2) were isolated by laser capture microscopy (LCM). The genes expression was evaluated by quantitative RT-PCR array, according to the manufacturer protocol (Stem cell signaling Profiler Array SABiosciences-Qiagen).
Our results indicated that only a few pathways, involved in stem cell differentiation and proliferation, were altered. Namely: FGF, Tgf-beta/BMP and Notch were upregulated. Furthermore, genes involved in regulating the Epithelial Mesenchymal Transition (EMT) like ZEB2 and LIFR were down-regulated compared to healthy control. Interestingly, the Wnt pathway was unchanged as regards of transcription.
Our data suggest that in celiac patients the immature compartment is expanded. Upregulation of Notch and FGF might be responsible for expansion of this compartment and involved in crypt hyperplasia. Further studies are required to evaluate this hypothesis. On the contrary the stem cell compartment is not expanded based on absence of Wnt pathway upregulation. Although celiac duodenal biopsies have elevated TGF-beta expression compared to normal control, this cytokine appears to be inversely regulated in stem/progenitor cells compartment from celiac disease patients. Interestingly Tgf-beta promotes EMT and differentiation. Further ZEB2 and LIFR, key components of EMT, were also downregulated suggesting that EMT might be critical during the acute phase of the disease. Confirmation of these preliminary results is necessary to provide more insights on the contribution of ISC network pathways to the onset and maintenance of the celiac disease histopathology.
Authors: Stefania Senger, Anna Sapone, Giuseppe Mazzarella, Alessio Fasano>