title: In vivo gene expression profiling of human intestinal epithelial cells: analysis by laser microdissection of formalin fixed tissues.
abstract: BACKGROUND
  The small intestinal epithelium mediates vital functions of nutrient absorption and host defense. The spatial organization of the epithelial cells along the crypt-villus axis segregates them into regions of specialized function. However, the differences in transcriptional programming and the molecular machinery that governs the migration, adhesion, and differentiation of intestinal epithelial cell lineages in humans remain under-explored. To increase our understanding of these mechanisms, we have evaluated gene expression patterns of ileal epithelial cells isolated by laser capture microdissection from either the villus epithelial or crypt cell regions of healthy human small intestinal mucosa. Expression profiles in villus and crypt epithelium were determined by DNA microarray, quantitative real-time PCR, and immunohistochemistry based methods. The expression levels of selected epithelial biomarkers were also compared between gastrointestinal tissues.
  
  
  RESULTS
  Previously established biomarkers as well as a novel and distinct set of genes believed to be linked to epithelial cell motility, adhesion, and differentiation were found to be enriched in each of the two corresponding cell populations (GEO accession: GSE10629). Additionally, high baseline expression levels of innate antimicrobials, alpha defensin 5 (HD5) and regenerating islet-derived 3 alpha (Reg3A), were detected exclusively within the small bowel crypt, most notably in the ileum in comparison to other sites along the gastrointestinal tract.
  
  
  CONCLUSIONS
  The elucidation of differential gene expression patterns between crypt and villus epithelial cell lineages in human ileal tissue provides novel insights into the molecular machinery that mediates their functions and spatial organization. Moreover, our findings establish an important framework of knowledge for future investigations of human gastrointestinal diseases.
authors.affiliation: Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis CA 95616, USA. mdgeorge@ucdavis.edu
authors.forename: Michael D
authors.initials: MD
authors.lastname: George
authors.forename: Jan
authors.initials: J
authors.lastname: Wehkamp
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kays
authors.forename: Christian M
authors.initials: CM
authors.lastname: Leutenegger
authors.forename: Sadiah
authors.initials: S
authors.lastname: Sabir
authors.forename: Irina
authors.initials: I
authors.lastname: Grishina
authors.forename: Satya
authors.initials: S
authors.lastname: Dandekar
authors.forename: Charles L
authors.initials: CL
authors.lastname: Bevins
mesh_terms: D002448:Cell Adhesion; D002454:Cell Differentiation; D002465:Cell Movement; D004847:Epithelial Cells / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D007082:Ileum / Q000166:cytology* / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D000073718:Pancreatitis-Associated Proteins