title: Grouped caging predisposes male mice to ankylosing enthesopathy.
abstract: OBJECTIVE
  To evaluate the number of males per cage as a possible risk factor for murine ankylosing enthesopathy (ANKENT)--a spontaneous joint disease with parallels to human seronegative spondylarthropathies--since ANKENT shows incomplete penetrance of genetic susceptibility factors among individuals living in a stable environment.
  
  
  METHODS
  Frequency of ANKENT was compared among males housed with females, with other males, or alone.
  
  
  RESULTS
  In three independent cohorts, a trend was observed that males housed with females rarely develop the disease, in contrast to males housed with other males (P < 0.25, P < 0.05, and P < 0.01). Furthermore, no males caged alone developed ANKENT, whereas disease did occur in males grouped together (P < 0.01). When healthy males (retired breeders) were recaged either alone or with other males, ANKENT developed among the grouped males only (P < 0.005).
  
  
  CONCLUSIONS
  Caging males together is a relative risk factor for ANKENT. Grouped caging may perturb the immune system through endocrine pathways or modify microbiological load through behaviour (for example, infection due to biting).
authors.affiliation: Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam.
authors.forename: S
authors.initials: S
authors.lastname: Weinreich
authors.forename: J
authors.initials: J
authors.lastname: Capkova
authors.forename: B
authors.initials: B
authors.lastname: Hoebe-Hewryk
authors.forename: C
authors.initials: C
authors.lastname: Boog
authors.forename: P
authors.initials: P
authors.lastname: Ivanyi
mesh_terms: D000818:Animals; D001947:Breeding; D004198:Disease Susceptibility; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D012307:Risk Factors; D012931:Social Environment; D013167:Spondylitis, Ankylosing / Q000209:etiology* / Q000235:genetics