title: Changes in epithelial cell turnover and extracellular matrix in human small intestine after TPN.
abstract: BACKGROUND
  The atrophy and architectural remodeling of the jejunal mucosa arising in adults receiving total parenteral nutrition (TPN) has been suggested to originate from a disturbance in tissue homeostasis. The present study aims at examining (1) whether there are differences in proliferation and apoptosis of epithelial cells between enterally and parenterally nourished patients and (2) whether the distribution pattern of extracellular matrix (ECM) proteins known to influence cell turnover along the the crypt-villus axis is changed after TPN.
  
  
  METHODS
  The mitotic frequency and the proliferation index [using an antibody against Ki-67 antigen (MIB 1)] were determined on epoxy semithin and paraffin sections, respectively. Morphological techniques and the TUNEL assay were applied to detect apoptotic events. Immunolocalization of collagen IV, laminin, fibronectin, tenascin, and collagen VI was performed on cryosections.
  
  
  RESULTS
  After TPN the cell renewal was significantly enhanced, while epithelial cell death was drastically reduced. The comparison of TPN and EN patients revealed differences in the distribution patterns of the ECM proteins laminin, fibronectin, and tenascin along the crypt-villus axis. Moreover, after TPN an increased expression of collagen types IV and VI was observed.
  
  
  CONCLUSIONS
  TPN in human adults is associated with alterations in epithelial cell turnover and changes in expression and/or localization of ECM proteins. Thus, the inverted route of nutrient supply in patients might modify environmental tissue conditions, which may influence the interactions between intestinal epithelial cells and the extracellular matrix.
authors.affiliation: Department of Microscopic Anatomy, Center of Anatomy, Hannover Medical School, Hannover, Germany. groos.stephanie@mh-hannover.de
authors.forename: Stephanie
authors.initials: S
authors.lastname: Groos
authors.forename: Enrico
authors.initials: E
authors.lastname: Reale
authors.forename: Günter
authors.initials: G
authors.lastname: Hünefeld
authors.forename: Liliana
authors.initials: L
authors.lastname: Luciano
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D004750:Enteral Nutrition; D005109:Extracellular Matrix / Q000187:drug effects / Q000473:pathology* / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D007583:Jejunum / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010289:Parenteral Nutrition, Total
chemical_list: D016326:Extracellular Matrix Proteins