title: IL-1 mediates amyloid-associated islet dysfunction and inflammation in human islet amyloid polypeptide transgenic mice.
abstract: OBJECTIVE
  Aggregation of islet amyloid polypeptide (IAPP) to form amyloid contributes to beta cell dysfunction in type 2 diabetes. Human but not non-amyloidogenic rodent IAPP induces islet macrophage proIL-1β synthesis. We evaluated the effect of IL-1 receptor antagonist (IL-1Ra) on islet inflammation and dysfunction in a mouse model of type 2 diabetes with amyloid formation.
  
  
  METHODS
  Lean and obese male mice (A/a or A(vy)/A at the agouti locus, respectively) with or without beta cell human IAPP expression (hIAPP(Tg/0)) were treated with PBS or IL-1Ra (50 mg kg(-1) day(-1)) from 16 weeks of age. Intraperitoneal glucose and insulin tolerance tests were performed after 8 weeks. Pancreases were harvested for histology and gene expression analysis.
  
  
  RESULTS
  Aggregation of human IAPP was associated with marked upregulation of proinflammatory gene expression in islets of obese hIAPP(Tg/0) mice, together with amyloid deposition and fasting hyperglycaemia. IL-1Ra improved glucose tolerance and reduced plasma proinsulin:insulin in both lean and obese hIAPP(Tg/0) mice with no effect on insulin sensitivity. The severity and prevalence of islet amyloid was reduced by IL-1Ra in lean hIAPP (Tg/0) mice, suggesting a feed-forward mechanism by which islet inflammation promotes islet amyloid at the early stages of disease. IL-1Ra limited Il1a, Il1b, Tnf and Ccl2 expression in islets from obese hIAPP(Tg/0) mice, suggesting an altered islet inflammatory milieu.
  
  
  CONCLUSIONS
  These data provide the first in vivo evidence—using a transgenic mouse model with amyloid deposits resembling those found in human islets—that IAPP-induced beta cell dysfunction in type 2 diabetes may be mediated by IL-1. Anti-IL-1 therapies may limit islet inflammation and dysfunction associated with amyloid formation.
authors.affiliation: Department of Pathology & Laboratory Medicine, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Clara Y
authors.initials: CY
authors.lastname: Westwell-Roper
authors.forename: Cyrus A
authors.initials: CA
authors.lastname: Chehroudi
authors.forename: Heather C
authors.initials: HC
authors.lastname: Denroche
authors.forename: Jaques A
authors.initials: JA
authors.lastname: Courtade
authors.forename: Jan A
authors.initials: JA
authors.lastname: Ehses
authors.forename: C Bruce
authors.initials: CB
authors.lastname: Verchere
mesh_terms: D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000378:metabolism; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism*; D058228:Islet Amyloid Polypeptide / Q000235:genetics / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic
chemical_list: D000682:Amyloid; D007375:Interleukin-1; D058228:Islet Amyloid Polypeptide