title: Ubiquitin-proteasome-rich cytoplasmic structures in neutrophils of patients with Shwachman-Diamond syndrome.
abstract: BACKGROUND
  Shwachman-Diamond syndrome is an autosomal recessive disorder in which severe bone marrow dysfunction causes neutropenia and an increased risk of leukemia. Recently, novel particulate cytoplasmic structures, rich in ubiquitinated and proteasomal proteins, have been detected in epithelial cells and neutrophils from patients with Helicobacter pylori gastritis and several epithelial neoplasms.
  
  
  METHODS
  Blood neutrophils from 13 cases of Shwachman-Diamond syndrome - ten with and three without SBDS gene mutation - and ten controls were investigated by confocal microscopy and ultrastructural immunocytochemistry using antibodies against ubiquitinated proteins, proteasomes, p62 protein, and Helicobacter pylori VacA, urease and outer membrane proteins.
  
  
  RESULTS
  Many extensively disseminated particulate cytoplasmic structures, accounting for 22.78 ± 5.57% (mean ± standard deviation) of the total cytoplasm, were found in blood neutrophils from mutated Shwachman-Diamond syndrome patients. The particulate cytoplasmic structures showed immunoreactivity for polyubiquitinated proteins and proteasomes, but no reactivity for Helicobacter pylori products, which are present in particulate cytoplasmic structures of Helicobacter pylori-positive gastritis. Neutrophils from patients with Shwachman-Diamond syndrome frequently showed p62-positive autophagic vacuoles and apoptotic changes in 5% of cells. No particulate cytoplasmic structures were observed in most control neutrophils; however, in a few cells from two cases we noted focal development of minute particulate cytoplasmic structures, accounting for 0.74 ± 0.56% of the total cytoplasm (P<0.001 versus particulate cytoplasmic structures from mutated Shwachman-Diamond syndrome patients). Neutrophils from non-mutated Shwachman-Diamond-syndrome-like patients resembled controls in two cases, and a third case showed particulate cytoplasmic structure patterns intermediate between those in controls and those in mutated Shwachman-Diamond syndrome patients.
  
  
  CONCLUSIONS
  Particulate cytoplasmic structures are a prominent feature of neutrophils from patients with Shwachman-Diamond syndrome. They may help us to understand the mechanism of granulocyte dysfunction and the neoplastic risk of the disease.
authors.affiliation: Department of Human Pathology and Genetics, University of Pavia and Fondazione IRCCS Policlinico S. Matteo, Pavia, Italy.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Necchi
authors.forename: Antonella
authors.initials: A
authors.lastname: Minelli
authors.forename: Patrizia
authors.initials: P
authors.lastname: Sommi
authors.forename: Agostina
authors.initials: A
authors.lastname: Vitali
authors.forename: Roberta
authors.initials: R
authors.lastname: Caruso
authors.forename: Daniela
authors.initials: D
authors.lastname: Longoni
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Frau
authors.forename: Cristina
authors.initials: C
authors.lastname: Nasi
authors.forename: Fabiola
authors.initials: F
authors.lastname: De Gregorio
authors.forename: Marco
authors.initials: M
authors.lastname: Zecca
authors.forename: Vittorio
authors.initials: V
authors.lastname: Ricci
authors.forename: Cesare
authors.initials: C
authors.lastname: Danesino
authors.forename: Enrico
authors.initials: E
authors.lastname: Solcia
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology*; D001855:Bone Marrow Diseases / Q000150:complications / Q000235:genetics / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D022083:Cytoplasmic Structures / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D010188:Exocrine Pancreatic Insufficiency / Q000150:complications / Q000235:genetics / Q000473:pathology*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008068:Lipomatosis / Q000150:complications / Q000235:genetics / Q000473:pathology*; D008297:Male; D018613:Microscopy, Confocal; D009154:Mutation; D009503:Neutropenia / Q000150:complications / Q000235:genetics / Q000473:pathology*; D009504:Neutrophils / Q000378:metabolism* / Q000648:ultrastructure; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D000071456:Sequestosome-1 Protein; D000081003:Shwachman-Diamond Syndrome; D025801:Ubiquitin / Q000378:metabolism; D057149:Ubiquitinated Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001426:Bacterial Proteins; D011506:Proteins; C470521:SBDS protein, human; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D025801:Ubiquitin; D057149:Ubiquitinated Proteins; C074689:VacA protein, Helicobacter pylori; D046988:Proteasome Endopeptidase Complex