Transgenic animals demonstrate a role for the IL-1 receptor in regulating IL-1beta gene expression at steady-state and during the systemic stress induced by acute pancreatitis.
Interleukin-1 (IL-1) gene expression is selectively induced in tissues involved in multisystem organ failure during acute pancreatitis, suggesting a role in the pathogenesis of distant organ dysfunction. This study was undertaken to investigate the mechanism of pancreatitis-induced end organ cytokine production and to better understand the processes by which IL-1 production is regulated. Seventy adult male transgenic mice in which the type 1 IL-1 receptor had been deleted by gene targeting in embryonic stem cells were utilized (homozygous -/- IL-1R knockout). Acute pancreatitis was induced by one of two methods: (A) IP injections of caerulein (50 microgram/kg/hr x 4) with animals sacrificed at 0, .5, 1, 2, 4, 6, and 8 hr; (B) 48-hr exposure to a choline deficient ethionine supplemented (CDE) diet with animals sacrificed at 0 and 72 hr. Knockout animals were compared to strain-specific control mice expressing the normal wild-type IL-1 receptor gene in which pancreatitis was similarly induced. The severity of pancreatitis was stratified by serum amylase, lipase, and blind histologic grading. IL-1 mRNA production was determined within the pancreas, lungs, liver, and spleen by quantitative differential RT-PCR. Deletion of the IL-1R1 attenuated the severity of pancreatitis, reaching statistical significance in the less severe edematous model. There was little or no constitutive expression of IL-1 mRNA within any of the tissues examined from wild-type animals; however, knockout animals showed elevated steady-state levels in each tissue. IL-1 mRNA became detectable in all tissues of wild-type animals shortly after either form of pancreatitis became apparent and increased significantly with worsening pancreatitis. Despite the attenuated pancreatitis, knockout animals produced significantly greater levels of IL-1 mRNA in each tissue, typically demonstrating a 30-50% increase over time matched IL-1 mRNA production in wild-type animals which was not pancreatitis model dependent. We conclude that genetic deletion of IL-1 receptors results in the overproduction of IL-1 mRNA in organs known to produce cytokines during pancreatitis even when the severity of pancreatitis is lessened. This suggests that a negative feedback loop exists between the IL-1 receptor and IL-1 gene expression.
Norman
J G
JG
Department of Surgery and the Pancreas Study Group, University of South Florida, Tampa 33612, USA.
Fink
G W
GW
Sexton
C
C
Carter
G
G
D000208:Acute Disease; D000818:Animals; D001483:Base Sequence; D002108:Ceruletide / Q000633:toxicity; D002796:Choline Deficiency; D016207:Cytokines / Q000096:biosynthesis*; D017931:DNA Primers; D004032:Diet; D005001:Ethionine; D005260:Female; D017353:Gene Deletion; D015870:Gene Expression; D006579:Heterozygote; D006720:Homozygote; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000235:genetics*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010195:Pancreatitis / Q000139:chemically induced / Q000235:genetics / Q000276:immunology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D017472:Receptors, Interleukin-1 / Q000235:genetics / Q000502:physiology*; D013234:Stem Cells
D016207:Cytokines; D017931:DNA Primers; D007375:Interleukin-1; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; D002108:Ceruletide; D005001:Ethionine